WorldWideScience

Sample records for water repellents

  1. Soft, elastic, water-repellent materials

    Science.gov (United States)

    Coux, Martin; Clanet, Christophe; Quéré, David

    2017-06-01

    Small hydrophobic textures at solid surfaces provide water repellency, a situation whose detailed properties critically depend on the geometry of textures. Depending on their size, density, and shape, water slip, rain repellency, or antifogging can be achieved. Here, we discuss how the use of soft, elastic materials allows us to tune reversibly the texture density by stretching or relaxing the materials, which is found to impact water adhesion and rebounds. In addition, solid deformations can also be exploited to largely vary the shape of Wenzel drops, a consequence of the strong pinning of water in this state.

  2. Uneven moisture patterns in water repellent soils

    NARCIS (Netherlands)

    Dekker, L.W.; Ritsema, C.J.

    1996-01-01

    In the Netherlands, water-repellent soils are widespread and they often show irregular moisture patterns, which cause accelerated transport of water and solutes to the groundwater and surface water. Under grass cover, spatial variability in soil moisture content is high owing to fingered flow; in ar

  3. The hydrology of water repellent soils

    Science.gov (United States)

    Shillito, R.; Berli, M.; Ghezzehei, T. A.; Moore, H. K.

    2016-12-01

    The occurrence of wildfire throughout the western U.S. is expected to increase. So, too, will flooding and erosion associated with the aftereffects of the fires. Soil water repellency (hydrophobicity) has frequently been observed after fires and is believed to increase the post-fire runoff potential, although current runoff models cannot directly account for this effect. Many physically-based runoff models incorporate an infiltration reduction factor or manipulate the soil hydraulic conductivity parameter to account for water-repellent soils in runoff generation. Beginning with fundamental principles, we developed a methodology to physically account for soil water repellency and directly account for it in the Kineros2 runoff and erosion model.

  4. Buffer zone water repellency: effects of the management practice

    OpenAIRE

    Rasa, Kimmo; Räty, Mari; Nikolenko, Olga; Horn, Rainer; Yli-Halla, Markku; Uusi-Kämppä, Jaana; Pietola, Liisa

    2006-01-01

    Water repellency index R was measured in a heavy clay and a sandy loam, used as arable land or buffer zone (BZ). Further, effect of management practise and ageing of BZs were studied. Water repellency was proved to be a common phenomenon on these soils. Harvesting and grazing increased water repellency as does ageing.Low water repellency is supposed to prevent preferential flows and provide evenly distributed water infiltration pattern through large soil volume, which favours nutrient retention.

  5. Moisture variability resulting from water repellency in Dutch soils

    OpenAIRE

    Dekker, L.W.

    1998-01-01

    The present study suggests that many soils in the Netherlands, in natural as well as in agricultural areas, may be water repellent to some degree, challenging the common perception that soil water repellency is only an interesting aberration. When dry, water repellent soils resist or retard water infiltration into the soil matrix. Soil water repellency can lead to the development of unstable wetting and preferential flow paths. Preferential flow has wide-ranging significance for rapi...

  6. Methods for determining actual soil water repellence

    NARCIS (Netherlands)

    Dekker, L.W.; Ritsema, C.J.; Oostindie, K.; Moore, D.; Wesseling, J.G.

    2009-01-01

    In this paper we describe a simple and quick method for determining the presence of water repellency in a soil by using a small core sampler (1.5 cm in diameter, 25 cm long) and applying the water drop penetration time (WDPT) test at different depths on the sandy soil cores. Obtained results provide

  7. Moisture variability resulting from water repellency in Dutch soils.

    NARCIS (Netherlands)

    Dekker, L.W.

    1998-01-01

    The present study suggests that many soils in the Netherlands, in natural as well as in agricultural areas, may be water repellent to some degree, challenging the common perception that soil water repellency is only an interesting aberration. When dry, water repellent soils resist or retard water in

  8. Moisture variability resulting from water repellency in Dutch soils

    NARCIS (Netherlands)

    Dekker, L.W.

    1998-01-01

    The present study suggests that many soils in the Netherlands, in natural as well as in agricultural areas, may be water repellent to some degree, challenging the common perception that soil water repellency is only an interesting aberration. When dry, water repellent soils resist or retard

  9. Water repellent soils: a state-of-the-art

    Science.gov (United States)

    Leonard F. DeBano

    1981-01-01

    Water repellency in soils was first described by Schreiner and Shorey (1910), who found that some soils in California could not be wetted and thereby were not suitable for agriculture. Waxy organic substances were responsible for the water repellency. Other studies in the early 1900's on the fairy ring phenomenon suggested that water repellency could be caused by...

  10. Manufacturing and characterisation of water repellent surfaces

    DEFF Research Database (Denmark)

    De Grave, Arnaud; Botija, Pablo; Hansen, Hans Nørgaard

    2006-01-01

    design criteria for such surfaces. The problem of adapting this behaviour to artificially roughened surfaces is addressed by providing design criteria for superhydrophobic, water-repellent and self-cleaning surfaces according to the concrete performance desired for them. Different kind of manufacturing...

  11. Water repellency diminishes peatland evaporation after wildfire

    Science.gov (United States)

    Kettridge, Nick; Lukenbach, Max; Hokanson, Kelly; Devito, Kevin; Hopkinson, Chris; Petrone, Rich; Mendoza, Carl; Waddington, Mike

    2016-04-01

    Peatlands are a critically important global carbon reserve. There is increasing concern that such ecosystems are vulnerable to projected increases in wildfire severity under a changing climate. Severe fires may exceed peatland ecological resilience resulting in the long term degradation of this carbon store. Evaporation provides the primary mechanisms of water loss from such environments and can regulate the ecological stress in the initial years after wildfire. We examine variations in evaporation within burned peatlands after wildfire through small scale chamber and large scale remote sensing measurements. We show that near-surface water repellency limits peatland evaporation in these initial years post fire. Water repellent peat produced by the fire restricts the supply of water to the surface, reducing evaporation and providing a strong negative feedback to disturbance. This previously unidentified feedback operates at the landscape scale. High surface temperatures that result from large reductions in evaporation within water repellent peat are observed across the 60,000 ha burn scar three months after the wildfire. This promotes high water table positions at a landscape scale which limit the rate of peat decomposition and supports the post fire ecohydrological recovery of the peatlands. However, severe burns are shown to exceed this negative feedback response. Deep burns at the peatland margins remove the hydrophobic layer, increasing post fire evaporation and leaving the peatland vulnerable to drying and associated ecological shifts.

  12. Measurements of infiltration and water repellency on different soils

    OpenAIRE

    Lavrač, Rožle

    2012-01-01

    Infiltration is a process of water entering soil from its surface. Field measurements of infiltration are performed with infiltrometers. Calculation of hydraulic conductivity can be done by different equations. Infiltration exhibits large spatial and temporal variability due to many affecting factors. One of those effects is soil water repellency (hydrophobicity). Water-repellent soils do not wet up spontaneously. The intensity and persistence of water repellency vary widely due to variabilit...

  13. Engineering Characteristics of Chemically Treated Water-Repellent Kaolin

    OpenAIRE

    Youngmin Choi; Hyunwook Choo; Tae Sup Yun; Changho Lee; Woojin Lee

    2016-01-01

    Water-repellent soils have a potential as alternative construction materials that will improve conventional geotechnical structures. In this study, the potential of chemically treated water-repellent kaolin clay as a landfill cover material is explored by examining its characteristics including hydraulic and mechanical properties. In order to provide water repellency to the kaolin clay, the surface of clay particle is modified with organosilanes in concentrations (CO) ranging from 0.5% to 10%...

  14. Water repellent soils: the case for unsaturated soil mechanics

    Directory of Open Access Journals (Sweden)

    Beckett Christopher

    2016-01-01

    Full Text Available Water repellent (or “hydrophobic” or “non-wetting” soils have been studied by soil scientists for well over a century. These soils are typified by poor water infiltration, which leads to increased soil erosion and poor crop growth. However, the importance of water repellence on determining soil properties is now becoming recognised by geotechnical engineers. Water repellent soils may, for example, offer novel solutions for the design of cover systems overlying municipal or mine waste storage facilities. However, investigations into factors affecting their mechanical properties have only recently been initiated. This purpose of this paper is to introduce geotechnical engineers to the concept of water repellent soils and to discuss how their properties can be evaluated under an unsaturated soils framework. Scenarios in which water repellent properties might be relevant in geotechnical applications are presented and methods to quantify these properties in the laboratory and in the field examined.

  15. Water repellency induced by pulmonary surfactants.

    Science.gov (United States)

    Hills, B A

    1982-04-01

    1. Pure cotton fabric was partially carboxylated to produce a tough, porous, hydrophilic sub-phase to stimulate the epithelial membrane of the alveolar wall from a permeability standpoint. 2. Two of the predominant pulmonary surfactants, dipalmitoyl lecithin (DPL) and dipalmitoyl phosphatidylethanolamine (DPPE), were found to inhibit wetting of this synthetic membrane and of human cutaneous epithelium as manifest by a large contact angle. 3. When treated with DPL at physiological concentrations, the porous synthetic membrane was found to support a head of saline well in excess of systolic pulmonary artery pressure with no penetration and could do so for periods well in excess of 1 hr; untreated control samples allowed almost immediate fluid filtration. 4. Filtration could be initiated in the DPL-treated membranes by wetting the reverse side, confirming that the threshold pressure for fluid penetration was afforded by capillarity and, hence, by water repellency induced by the surfactant. 5. Water repellency induced by the amphoteric surfactants occurring naturally in the lung is discussed as a possible factor contributing to the pressure threshold to be exceeded for alveolar oedema to form. 6. Evidence is reviewed and several advantages discussed for the implied concept of an essentially dry lining to the alveolus with a discontinuous liquid layer largely confined to convex corners which could slowly resolve any oedema by surface forces.

  16. Citrus orchards management and soil water repellency in Eastern Spain

    Science.gov (United States)

    Cerdà, A.; González Peñaloza, F. A.; Jordán, A.; Zavala, L. M.

    2012-04-01

    Water repellent soils are found around the world, although originally was found on fire affected soil (DeBano, 1981). However, for decades, water repellency was found to be a rare soil property. One of the pioneer research that shown that water repellency was a common soil property is the Wander (1949) publication in Science. Wander researched the water repellency on citrus groves, and since then, no information is available about the water repellency on citrus plantations. The Mediterranean soils are prone to water repellency due to the summer dry conditions (Cerdà and Doerr, 2007). And Land Use and Land Management are key factors (Harper et al., 2000; Urbanek et al., 2007) to understand the water repellency behaviour of agriculture soils. Valencia region (Eastern Spain) is the largest exporter in the world and citrus plantations located in the alluvial plains and fluvial terraces are moving to alluvial fans and slopes where the surface wash is very active (Cerdà et al., 2009). This research aims to show the water repellency on citrus orchards located on the sloping terrain (water repellency in citrus orchards under different managements: annual addition of plant residues and manure with no tilling and no fertilizer (MNT), annual addition of plant residues with no tillage (NT), application of conventional herbicides and no tilling (HNT) and conventional tillage in June (CT). The period for each type of management ranged from 2 and 27 (MNT), 1 and 25 (NT), 2 and 27 (HNT) and 3 and 29 years (CT). At each plot, a ten points were selected every 10 cm along inter-rows and water drop penetration time test (WDTP; DeBano, 1981) was performed. The results show that the MNT treatment induced slight water repellency in citrus-cropped soils compared to other treatments. Small but significant soil water repellency was observed under NT and HNT treatments (mean WDTP 4 ± 4 s and 2 ± 2 s, respectively), which may be regarded as subcritical soil water repellency. Slight water

  17. Application of actinomycetes to soil to ameliorate water repellency.

    Science.gov (United States)

    McKenna, F; El-Tarabily, K A; Petrie, S; Chen, C; Dell, B

    2002-01-01

    The aim of this study was to develop a novel isolation technique using a mixture of Bacillus and Streptomyces phages to selectively isolate wax-utilizing non-streptomycete actinomycetes effective in ameliorating water repellency in a problem soil. Phages added to a soil suspension reduced the dominance of Bacillus and Streptomyces isolates and significantly increased the number of non-streptomycete actinomycetes on isolation plates. Promising isolates, grown on a medium containing beeswax as sole carbon source, were selected for application to water repellent soil. Their addition significantly reduced water repellency. Phage application significantly increased the isolation of non-streptomycete actinomycetes. Wax-utilizing isolates were found to significantly reduce water repellency in a problem soil. The phage technique can be used for the routine isolation of non-streptomycete actinomycetes. Beeswax medium can be used to selectively isolate wax-utilizing micro-organisms with the potential to ameliorate water repellency in soil.

  18. Engineering water repellency in granular materials for ground applications

    Science.gov (United States)

    Lourenco, Sergio; Saulick, Yunesh; Zheng, Shuang; Kang, Hengyi; Liu, Deyun; Lin, Hongjie

    2017-04-01

    Synthetic water repellent granular materials are a novel technology for constructing water-tight barriers and fills that is both inexpensive and reliant on an abundant local resource - soils. Our research is verifying its stability, so that perceived risks to practical implementation are identified and alleviated. Current ground stabilization measures are intrusive and use concrete, steel, and glass fibres as reinforcement elements (e.g. soil nails), so more sustainable approaches that require fewer raw materials are strongly recommended. Synthetic water repellent granular materials, with persistent water repellency, have been tested for water harvesting and proposed as landfill and slope covers. By chemically, physically and biologically adjusting the magnitude of water repellency, they offer the unique advantage of controlling water infiltration and allow their deployment as semi-permeable or impermeable materials. Other advantages include (1) volumetric stability, (2) high air permeability and low water permeability, (3) suitability for flexible applications (permanent and temporary usage), (4) improved adhesion aggregate-bitumen in pavements. Application areas include hydraulic barriers (e.g. for engineered slopes and waste containment), pavements and other waterproofing systems. Chemical treatments to achieve water repellency include the use of waxes, oils and silicone polymers which affect the soil particles at sub-millimetric scales. To date, our research has been aimed at demonstrating their use as slope covers and establishing the chemical compounds that develop high and stable water repellency. Future work will determine the durability of the water repellent coatings and the mechanics and modelling of processes in such soils.

  19. Water repellency of soils; the influence of ambient relative humidity

    NARCIS (Netherlands)

    Doerr, S.H.; Dekker, L.W.; Ritsema, C.J.; Shakesby, R.A.; Bryant, R.

    2002-01-01

    Adverse effects of soil water repellency (hydrophobicity) are of concern during or following rainfall or irrigation, and are often preceded by conditions of high atmospheric relative humidity (RH). Assessments of repellency are, however, commonly conducted on air-dried samples at ambient laboratory

  20. Soil water repellency in north-eastern Greece with adverse effects of drying on the persistence

    NARCIS (Netherlands)

    Ziogas, A.K.; Dekker, L.W.; Oostindie, K.; Ritsema, C.J.

    2005-01-01

    Many soils may be water repellent to some degree, challenging the common perception that soil water repellency is only an interesting aberration. When dry, water repellent soils resist or retard water infiltration into the soil matrix. Soil water repellency often leads to the development of unstable

  1. Soil water repellency in north-eastern Greece with adverse effects of drying on the persistence

    NARCIS (Netherlands)

    Ziogas, A.K.; Dekker, L.W.; Oostindie, K.; Ritsema, C.J.

    2005-01-01

    Many soils may be water repellent to some degree, challenging the common perception that soil water repellency is only an interesting aberration. When dry, water repellent soils resist or retard water infiltration into the soil matrix. Soil water repellency often leads to the development of unstable

  2. Measurements of water repellency and infiltration of the soil

    OpenAIRE

    Žnidaršič, Petra

    2013-01-01

    Soil water repellency is a reduction in the rate of wetting caused by the presence of hydrophobic coatings on soil particles. The occurrence of the absorption of water from the surface of the ground in its interior is called infiltration. Water resistance and infiltration are dependent on a number of influences. All measurements were done on three different soil types at each at the ground level and in the trench. Water repellency measurements were performed by two methods, namely with wat...

  3. Soil water repellency changes with depth and relationship to physical properties within wettable and repellent soil profiles

    Directory of Open Access Journals (Sweden)

    Sepehrnia Nasrollah

    2017-03-01

    Full Text Available This study explored the effect of soil water repellency (SWR on soil hydrophysical properties with depth. Soils were sampled from two distinctly wettable and water repellent soil profiles at depth increments from 0-60 cm. The soils were selected because they appeared to either wet readily (wettable or remain dry (water repellent under field conditions. Basic soil properties (MWD, SOM, θv were compared to hydrophysical properties (Ks, Sw, Se, Sww, Swh, WDPT, RIc, RIm and WRCT that characterise or are affected by water repellency. Our results showed both soil and depth affected basic and hydrophysical properties of the soils (p <0.001. Soil organic matter (SOM was the major property responsible for water repellency at the selected depths (0-60. Water repellency changes affected moisture distribution and resulted in the upper layer (0-40 cm of the repellent soil to be considerably drier compared to the wettable soil. The water repellent soil also had greater MWDdry and Ks over the entire 0-60 cm depth compared to the wettable soil. Various measures of sorptivity, Sw, Se, Sww, Swh, were greater through the wettable than water repellent soil profile, which was also reflected in field and dry WDPT measurements. However, the wettable soil had subcritical water repellency, so the range of data was used to compare indices of water repellency. WRCT and RIm had less variation compared to WDPT and RIc. Estimating water repellency using WRCT and RIm indicated that these indices can detect the degree of SWR and are able to better classify SWR degree of the subcritical-repellent soil from the wettable soil.

  4. A Water-repellent Silanization Coating Technique for MEMS

    Science.gov (United States)

    Shimaoka, Keiichi; Hosokawa, Hideki; Funabashi, Hirohumi; Mitsushima, Yasuichi

    A gas-phase water-repellent silanization coating technique, which prevents the microscopic structures used for micro-sensors and micro-electro-mechanical systems (MEMS) from sticking to the silicon substrates and other microscopic structures during operation, have been developed. Use of a water-repellent coating is one method that prevents sticking by reducing the surface energy of the structure. The water-repellency characteristics of three types of organosilicon compounds were evaluated. It was found that a water-repellent silanization coating layer using (tridecafluoro - 1, 1, 2, 2 -tetrahydrooctyl) trichlorosilane (C8H4Cl3F13Si) had most excellent durability. It was confirmed that the water contact angle of C8H4Cl3F13Si coating layer is exceeding 90 degrees at surface of standard semiconductor materials except nickel. In addition, the C8H4Cl3F13Si coating layer can be patterned by ultraviolet irradiation.

  5. Mitigation of water repellency in burned soils applying hydrophillic polymers

    Science.gov (United States)

    Neris, Jonay; de la Torre, Sara; Vidal-Vazquez, Eva; Lado, Marcos

    2017-04-01

    In this study, the effect of fire on water repellency was analyzed in soils from different parent materials, as well as the suitability of anionic polyacrylamide (PAM) to reduce water repellency in these soils. Samples were collected in four different sites where wildfires took place: two in the Canary Islands, with soils developed on volcanic materials, and two in Galicia (NW Spain), with soils developed on plutonic rocks. In Galicia, two soil samples were collected in each site, one in the burnt area and one in an adjacent unburnt area. In the Canary Islands, four samples were collected from each site, three inside the burnt area where the soils were affected by different fire intensities, and one in an unburnt adjacent area. Samples were air-dried and sieved by a 2-mm mesh sieve. Water repellency was measured using the Water Drop Penetration Time test. An amount of 10 g of soil was placed in a tray. Five drops of deionized water were place on the soil surface with a pipette, and the time for each drop to fully penetrate into the soil was recorded. PAM solution was applied to the burnt soils simulating a field application rate of 1gm-2. The polymer used was Superfloc A-110 (Kemira Water Solutions BV, Holland) with 1x107 Da molecular weigth and 15% hydrolysis. PAM was sprayed on the soil surface as solution with a concentration 0.2 g/L. After the application, the samples were dried and the WDPT test was performed. Three replicates for each treatment and soil were used, and the treatments included: dry soil, dry soil after a wetting treatment, dry PAM-treated soil. The results showed that water repellency was modified by fire differently in the various soils. In hydrophilic soils and soils with low water repellency, water repellency was increased after the action of fire. In soils with noticeable initial water repellency, this was reduced or eliminated after the fire. Wetting repellent soils caused a decrease in water repellency most probably because of the spatial

  6. Surface Treatment of Building Materials with Water Repellent Agents

    OpenAIRE

    Wittman, F.H.; Siemes, T.A.J.M.; Verhoef, L.G.W.

    1995-01-01

    Water repellent agents have been applied to proteet building materials and structural elements for thousands ofyears. Initially, natural products, such as oils and fats were used exclusively. More recently, synthetic organic compounds are being developed for special applications.

  7. Using Ethanol to Investigate Dynamic Soil Water Repellency

    Science.gov (United States)

    Smith, James E.; Beatty, Sarah M.

    2016-04-01

    Large gaps remain in our fundamental understanding of the behaviour of water in dynamically repellent soils. By investigating these systems using other miscible fluids that minimize or eliminate repellency, e.g. ethanol, we seek to better understand and quantify soil water repellency. The advantages of the enhanced wettability of water repellent soils to other miscible fluids, however, come with complications including shifts in effective pore water pressures induced through variable interfacial tensions as well as differences in fluid mobility due to variable fluid viscosities and densities. With these considerations in mind, we compare and contrast the observed behaviours of fluid infiltration and retention in dynamically hydrophobic soils and hydrophilic soils. We conducted field and laboratory studies using tension disc infiltrometers along with water and ethanol solutions to investigate dynamic repellency in post-wildfire soils from Northern Ontario, Canada. Tension infiltrometers maintain a constant negative liquid pressure at the surface which proved to be useful for isolating wettable behaviours sensitive to dynamic changes in wettability. We present the data and system conceptualised and explained through contact angle dynamics and variable fractional wettability of the soil. The limitations of extending hydrophilic concepts and hydraulic functions to hydrophobic soils are discussed along with persistent challenges to advance our ability to simulate and predict system behaviours in naturally occurring water repellent soils.

  8. Approaches to characterize the degree of water repellency

    Science.gov (United States)

    Letey, J.; Carrillo, M. L. K.; Pang, X. P.

    2000-05-01

    Measurement techniques that quantify the degree of soil water repellency are important for research and for the communication of research findings. The water drop penetration time (WDPT) is a commonly used measurement. If a water drop does not enter the soil spontaneously, the soil-water contact angle is greater than 90° and the soil is considered to be water repellent. The time for the drop to enter the soil (WDPT) provides an indication of the stability of the repellency. The liquid-air surface tension of an aqueous ethanol concentration series that enters the soil in approximately 5 s is identified as the ninety degree (ND) surface tension, γND, of the soil. The γND number can be used to calculate the solid-air surface tension, γs, by γs= γND/4. The water-soil contact angle can also be calculated from the γs value by the relationship cos θ=[(γ ND/γ w) 1/2-1], where θ is the contact angle and γw the water-air surface tension. The water entry pressure, hp, which is a function of both the soil water repellency and pore size, is an important parameter for predicting infiltration and the stability of water flow in the field. Measurements of WDPT, γND, and hp provide a complete characterization of the degree of water repellency.

  9. Ultra Water Repellent Polypropylene Surfaces with Tunable Water Adhesion.

    Science.gov (United States)

    Zhu, Tang; Cai, Chao; Guo, Jing; Wang, Rong; Zhao, Ning; Xu, Jian

    2017-03-22

    Polypropylene (PP), including isotactic PP (i-PP) and atactic PP (a-PP) with distinct tacticity, is one of the most widely used general plastics. Herein, ultra water repellent PP coatings with tunable adhesion to water were prepared via a simple casting method. The pure i-PP coating shows a hierarchical morphology with micro/nanobinary structures, exhibiting a water contact angle (CA) larger than 150° and a sliding angle less than 5° (for 5 μL water droplet). In contrast, the pure a-PP coating has a less rough morphology with a water contact angle of about 130°, and the water droplets stick on the coating at any tilted angles. For the composite i-PP/a-PP coatings, however, ultra water repellency with CA > 150° but water adhesion tailorable from slippery to sticky can be realized, depending on the contents of a-PP and i-PP. The different wetting behaviors are due to the various microstructures of the composite coatings resulting from the distinct crystallization ability of a-PP and i-PP. Furthermore, the existence of a-PP in the composite coatings enhances the mechanical properties compared to the i-PP coating. The proposed method is feasible to modify various substrates and potential applications in no-loss liquid transportation, slippery surfaces, and patterned superhydrophobic surfaces are demonstrated.

  10. Improvement of Water Movement in an Undulating Sandy Soil Prone to Water Repellency

    NARCIS (Netherlands)

    Oostindie, K.; Dekker, L.W.; Wesseling, J.G.; Ritsema, C.J.

    2011-01-01

    The temporal dynamics of water repellency in soils strongly influence water flow. We investigated the variability of soil water content in a slight slope on a sandy fairway exhibiting water-repellent behavior. A time domain reflectometry (TDR) array of 60 probes measured water contents at 3-h

  11. Visible NearInfrared Spectroscopy Predicts Water Repellency in Soil

    DEFF Research Database (Denmark)

    Hermansen, Cecilie; Møldrup, Per; Clothier, Brent;

    Soil water repellency (SWR) is a property which has consequences for agricultural water management. The SWR is caused by hydrophobic organic coatings on mineral particles and the severity is highly depending on the organic matter quantity and quality and on the moisture status of the soil...

  12. Causes and consequences of fire-induced soil water repellency

    Science.gov (United States)

    Letey, J.

    2001-10-01

    A wettable surface layer overlying a water-repellent layer is commonly observed following a fire on a watershed. High surface temperatures burn off organic materials and create vapours that move downward in response to a temperature gradient and then condense on soil particles causing them to become water repellent. Water-repellent soils have a positive water entry pressure hp that must be exceeded or all the water will runoff. Water ponding depths ho that exceeds hp will cause infiltration, but the profile is not completely wetted. Infiltration rate and soil wetting increase as the value of ho/hp increases. The consequence is very high runoff, which also contributes to high erosion on fire-induced water-repellent soils during rain storms. Grass establishment is impaired by seeds being eroded and lack of soil water for seeds that do remain and germinate. Extrapolation of these general findings to catchment or watershed scales is difficult because of the very high temporal and spatial variabilities that occur in the field.

  13. Water quality and surfactant effects on the water repellency of a sandy soil

    Science.gov (United States)

    Differences in irrigation water quality may affect the water repellency of soils treated or untreated with surfactants. Using simulated irrigations, we evaluated water quality and surfactant application rate effects upon the water repellency of a Quincy sand (Xeric Torripsamment). We used a split ...

  14. Water repellency and critical soil water content in a dune sand

    NARCIS (Netherlands)

    Dekker, L.W.; Doerr, S.H.; Oostindie, K.; Ziogas, A.K.; Ritsema, C.J.

    2001-01-01

    Assessments of water repellency of soils are commonly made on air-dried or oven-dried samples, without considering the soil water content. The objectives of this study were to examine the spatial and temporal variability of soil water content, actual water repellency over short distances, and the

  15. Fire-induced water repellency: An erosional factor in wildland environments

    Science.gov (United States)

    Leonard F. DeBano

    2000-01-01

    Watershed managers and scientists throughout the world have been aware of fire-induced water-repellent soils for over three decades. Water repellency affects many hydrologic processes, including infiltration, overland flow, and surface erosion (rill and sheet erosion). This paper describes; the formation of fire-induced water-repellent soils, the effect of soil water...

  16. Engineering Characteristics of Chemically Treated Water-Repellent Kaolin.

    Science.gov (United States)

    Choi, Youngmin; Choo, Hyunwook; Yun, Tae Sup; Lee, Changho; Lee, Woojin

    2016-12-02

    Water-repellent soils have a potential as alternative construction materials that will improve conventional geotechnical structures. In this study, the potential of chemically treated water-repellent kaolin clay as a landfill cover material is explored by examining its characteristics including hydraulic and mechanical properties. In order to provide water repellency to the kaolin clay, the surface of clay particle is modified with organosilanes in concentrations (CO) ranging from 0.5% to 10% by weight. As the CO increases, the specific gravity of treated clay tends to decrease, whereas the total organic carbon content of the treated clay tends to increase. The soil-water contact angle increases with an increase in CO until CO = 2.5%, and then maintains an almost constant value (≈134.0°). Resistance to water infiltration is improved by organosilane treatment under low hydrostatic pressure. However, water infiltration resistance under high hydrostatic pressure is reduced or exacerbated to the level of untreated clay. The maximum compacted dry weight density decreases with increasing CO. As the CO increases, the small strain shear modulus increases, whereas the effect of organosilane treatment on the constrained modulus is minimal. The results indicate that water-repellent kaolin clay possesses excellent engineering characteristics for a landfill cover material.

  17. Engineering Characteristics of Chemically Treated Water-Repellent Kaolin

    Directory of Open Access Journals (Sweden)

    Youngmin Choi

    2016-12-01

    Full Text Available Water-repellent soils have a potential as alternative construction materials that will improve conventional geotechnical structures. In this study, the potential of chemically treated water-repellent kaolin clay as a landfill cover material is explored by examining its characteristics including hydraulic and mechanical properties. In order to provide water repellency to the kaolin clay, the surface of clay particle is modified with organosilanes in concentrations (CO ranging from 0.5% to 10% by weight. As the CO increases, the specific gravity of treated clay tends to decrease, whereas the total organic carbon content of the treated clay tends to increase. The soil-water contact angle increases with an increase in CO until CO = 2.5%, and then maintains an almost constant value (≈134.0°. Resistance to water infiltration is improved by organosilane treatment under low hydrostatic pressure. However, water infiltration resistance under high hydrostatic pressure is reduced or exacerbated to the level of untreated clay. The maximum compacted dry weight density decreases with increasing CO. As the CO increases, the small strain shear modulus increases, whereas the effect of organosilane treatment on the constrained modulus is minimal. The results indicate that water-repellent kaolin clay possesses excellent engineering characteristics for a landfill cover material.

  18. Natural and fire-induced soil water repellency in a Portugese Shrubland

    NARCIS (Netherlands)

    Stoof, C.R.; Moore, D.; Ritsema, C.J.; Dekker, L.W.

    2011-01-01

    Post-fire land degradation is often attributed to fire-induced soil water repellency, despite the fact that soil water repellency is a natural phenomenon in many soils and is therefore not necessarily caused by fire. To improve our understanding of the role of soil water repellency in causing fire-i

  19. Development of Hydrophobic Coatings for Water-Repellent Surfaces Using Hybrid Methodology

    Science.gov (United States)

    2014-04-01

    windows, optical components, protective eyewear, and clothing, this type of surface is desired for the material to be soil repellent and water ...Development of Hydrophobic Coatings for Water - Repellent Surfaces Using Hybrid Methodology by Amanda S. Weerasooriya, Jacqueline Yim, Andres A...Proving Ground, MD 21005-5069 ARL-TR-6898 April 2014 Development of Hydrophobic Coatings for Water - Repellent Surfaces Using Hybrid

  20. Natural and fire-induced soil water repellency in a Portugese Shrubland

    NARCIS (Netherlands)

    Stoof, C.R.; Moore, D.; Ritsema, C.J.; Dekker, L.W.

    2011-01-01

    Post-fire land degradation is often attributed to fire-induced soil water repellency, despite the fact that soil water repellency is a natural phenomenon in many soils and is therefore not necessarily caused by fire. To improve our understanding of the role of soil water repellency in causing

  1. Fire-induced water-repellent soils, an annotated bibliography

    Science.gov (United States)

    Kalendovsky, M.A.; Cannon, S.H.

    1997-01-01

    The development and nature of water-repellent, or hydrophobic, soils are important issues in evaluating hillslope response to fire. The following annotated bibliography was compiled to consolidate existing published research on the topic. Emphasis was placed on the types, causes, effects and measurement techniques of water repellency, particularly with respect to wildfires and prescribed burns. Each annotation includes a general summary of the respective publication, as well as highlights of interest to this focus. Although some references on the development of water repellency without fires, the chemistry of hydrophobic substances, and remediation of water-repellent conditions are included, coverage of these topics is not intended to be comprehensive. To develop this database, the GeoRef, Agricola, and Water Resources Abstracts databases were searched for appropriate references, and the bibliographies of each reference were then reviewed for additional entries. Additional references will be added to this bibliography as they become available. The annotated bibliography can be accessed on the Web at http://geohazards.cr.usgs.gov/html_files/landslides/ofr97-720/biblio.html. A database consisting of the references and keywords is available through a link at the above address. This database was compiled using EndNote2 plus software by Niles and Associates, and is necessary to search the database.

  2. Exponential increase of publications related to soil water repellency

    NARCIS (Netherlands)

    Dekker, L.W.; Oostindie, K.; Ritsema, C.J.

    2005-01-01

    Soil water repellency is much more wide-spread than formerly thought. During the last decades, it has been a topic of study for soil scientists and hydrologists in at least 21 States of the USA, in Canada, Australia, New Zealand, Mexico, Colombia, Chile, Congo, Nepal, India, Hong Kong, Taiwan, China

  3. Exponential increase of publications related to soil water repellency

    NARCIS (Netherlands)

    Dekker, L.W.; Oostindie, K.; Ritsema, C.J.

    2005-01-01

    Soil water repellency is much more wide-spread than formerly thought. During the last decades, it has been a topic of study for soil scientists and hydrologists in at least 21 States of the USA, in Canada, Australia, New Zealand, Mexico, Colombia, Chile, Congo, Nepal, India, Hong Kong, Taiwan,

  4. Soil surfactant stops water repellency and preferential flow paths

    NARCIS (Netherlands)

    Oostindie, K.; Dekker, L.W.; Wesseling, J.G.; Ritsema, C.J.

    2008-01-01

    This study reports the effects of a soil surfactant on reduction and prevention of water repellency and preferential flow paths in a sandy soil of a golf course fairway, located at Bosch en Duin near Utrecht, the Netherlands. The golf course is constructed on inland dunes composed of fine sand with

  5. Water repellency of two forest soils after biochar addition

    Science.gov (United States)

    D. S. Page-Dumroese; P. R. Robichaud; R. E. Brown; J. M. Tirocke

    2015-01-01

    Practical application of black carbon (biochar) to improve forest soil may be limited because biochar is hydrophobic. In a laboratory, we tested the water repellency of biochar application (mixed or surface applied) to two forest soils of varying texture (a granitic coarse-textured Inceptisol and an ash cap fine-textured Andisol) at four different application rates (0...

  6. Water repellency in hydrophobic nanocapsules--molecular view on dewetting.

    Science.gov (United States)

    Müller, Achim; Garai, Somenath; Schäffer, Christian; Merca, Alice; Bögge, Hartmut; Al-Karawi, Ahmed Jasim M; Prasad, Thazhe Kootteri

    2014-05-26

    The hydrophobic effect plays a major role in a variety of important phenomena in chemistry, materials science and biology, for instance in protein folding and protein-ligand interactions. Studies--performed within cavities of the unique metal oxide based porous capsules of the type {(pentagon)12(linker)30}≡{(W)W5}12{Mo2(ligand)}30 with different acetate/water ligand ratios--have provided unprecedented results revealing segregation/repellency of the encapsulated "water" from the internal hydrophobic ligand walls of the capsules, while the disordered water molecules, interacting strongly with each other via hydrogen bonding, form in all investigated cases the same type of spherical shell. The present results can be (formally) compared--but only regarding the repellency effect--with the amazing "action" of the (super)hydrophobic Lotus (Nelumbo) leaves, which are self-cleaning based on water repellency resulting in the formation of water droplets picking up dirt. The present results were obtained by constructing deliberately suitable hydrophobic interiors within the mentioned capsules.

  7. Water content and water repellency in a field. Implications for irrigation strategies

    Science.gov (United States)

    Thwaites, L. A.; de Rooij, G. H.; Salzman, S.; Allinson, G.; Stagnitti, F.; Carr, R.; Versace, V.; Struck, S.; March, T.

    2010-05-01

    The degree of water repellency of soil material depends on its water content. Irrigated soils preferably should be kept sufficiently wet to render the soil wettable, in order to prevent irrigation water bypassing the root zone. But if this leads to overirrigation, the risk of groundwater pollution increases. We applied three irrigation regimes to individual trees in a Eucalyptus plantation on water-repellent soil. The resulting unimodal distribution of shallow water contents produced a bimodal distribution in the degree of water repellency: at any location, the soil would most likely be either wettable, or strongly water-repellent. We developed a procedure to estimate from both distributions the area of wettable soil based on a population of locally determined water contents.

  8. Durability of two water repelents applied to granite

    Directory of Open Access Journals (Sweden)

    Rivas, T.

    1998-06-01

    Full Text Available The durability of two water-repellents for granitic stonework was determined. Weathered and sound samples of granites widely used in building construction and restoration in Galicia (NW Spain were treated with water repellents of known efficacy, and then subjected to two artificial weathering tests: prolonged exposure to UV light, and sodium sulphate crystallization cycles. In both tests, but especially in the salt crystallization cycles, both treatments rapidly lost their water-repellency. Furthermore, the hydrophobic layer of water repellent impeded salt mobility, favouring fissuration parallel to the treated surface, which was eventually shed in the form of a plaque.

    Se presentan los resultados de la durabilidad de dos tratamientos de hidrofugación aplicados a rocas graníticas ampliamente utilizados en la construcción de edificios en Galicia (Noroeste de España. Tras la evaluación de la eficacia de dichos tratamientos, cuyos resultados se presentaron en un trabajo anterior, se someten las muestras tratadas a dos ensayos diferentes de envejecimiento acelerado: ciclos de exposición a la luz ultravioleta y ciclos de cristalización de sulfato de sodio. Los productos hidrofugantes muestran una escasa resistencia a ambos ensayos, sobre todo a los ciclos de cristalización de sulfato de sodio; esta débil durabilidad se manifiesta en una rápida pérdida de sus propiedades hidrofugantes. Así mismo, se observa que la presencia de la capa hidrófoba en la piedra funciona como una barrera frente a la movilidad de sales, lo que ocasiona el total desprendimiento de aquella y un fuerte deterioro del material rocoso.

  9. Facile Method to Prepare Superhydrophobic and Water Repellent Cellulosic Paper

    OpenAIRE

    Ioannis Karapanagiotis; Diana Grosu; Dimitra Aslanidou; Aifantis, Katerina E.

    2015-01-01

    Silica nanoparticles (7 nm) were dispersed in solutions of a silane/siloxane mixture. The dispersions were applied, by brush, on four types of paper: (i) modern, unprinted (blank) paper, (ii) modern paper where a text was printed using a common laser jet printer, (iii) a handmade paper sheet detached from an old book, and (iv) Japanese tissue paper. It is shown that superhydrophobicity and water repellency were achieved on the surface of the deposited films, when high particle concentrations ...

  10. Soil water repellency in long term drought and warming experiments

    Science.gov (United States)

    Urbanek, Emilia; Emmett, Bridget; Tietema, Albert; Robinson, David

    2017-04-01

    Increased global temperatures, altered rainfall patterns and frequently occurring extreme climatic events are already observed globally as a result of the climatic changes and further increases are predicted by the climatic models. Extreme weather events such as prolonged dry spells and heat waves can significantly affect soil ecosystem functions mainly due to decrease in soil moisture. Several studies suggested an increase in soil water repellency severity and spread as a consequence of the warming and drought, however, such understanding is based on the laboratory experimentations with soil treated as a 'black box'. In this study we tested the hypothesis of increased severity of soil water repellency subjected to drought and warming under field conditions. Occurrence and severity of soil water repellency was tested in soils subjected to a long-term (10 years) climatic simulation at two upland heathland sites in Oldebroek (Netherlands) and in Clocaenog (UK)[1]. Soil plots with similar vegetation were subjected to repeated drought and warming, compared with the control plots. Drought effect was created by a rainfall exclusion using an automatic self-retracting waterproof curtains while the warming effect was made by using a self-retracting curtains reflecting infrared radiation overnight. The results available to date provide a strong indication that climatic conditions do affect the development of SWR.

  11. Impact of water content and decomposition stage on the soil water repellency of peat soils

    Science.gov (United States)

    Dettmann, Ullrich; Sokolowsky, Liv; Piayda, Arndt; Tiemeyer, Bärbel; Bachmann, Jörg

    2017-04-01

    Soil water repellency is widely reported for all kinds of soils and mainly caused by hydrophobic organic compounds. It has a substantial influence on soil hydraulic processes such as water infiltration, preferential flow paths and evaporation and therefore on hydrological processes in general. The severity of soil water repellency strongly depends on the soil water content and the amount of soil organic carbon. Although peat soils are characterized by high soil organic carbon contents, studies about peat soils are rare and mostly available for horticultural substrates. Here, we present soil water repellency measurements for peat soils with varying porosities, bulk densities and stages of decomposition. The peat soils were sampled at two different sites in a bog complex. The sites have been drained for 1 and 100 years. Samples were taken from each soil layer and, additionally, in a vertical resolution of 0.03 m. To determine the soil water contents at which the peat becomes water repellent, we applied the commonly used water drop penetration time test on progressively dewatered samples. In order to identify the influence of the decomposition stage as determined by the depth within the soil profile and duration of drainage, the potential soil water repellency was measured at air-dried sieved samples by the sessile drop method. First results show that the soil water repellency of peat soils is strongly dependent on the soil water content. For air-dried peat samples, the influence of different decomposition stages of the bog peat is negligible. All air-dried samples are extremely water repellent with contact angles > 130°. However, comparing the results with the soil organic matter content shows a slightly tendency of increasing soil water repellency with increasing soil organic matter contents.

  12. Moisture characteristics of water-repellent consolidants and their applicability to existing buildings

    Science.gov (United States)

    Iba, Chiemi; Fukui, Kazuma; Hokoi, Shuichi

    2016-07-01

    Water-repellent agents are considered an effective measure of preventing moisture damage in building materials. However, data on the moisture transfer characteristics of repellent materials are insufficient. This study focused on the transfer of liquid water in a porous building material and quantitatively evaluated the applicability of a water-repellent consolidant as a protection agent via water infiltration experiments and numerical analysis. The experimental results could be reproduced by treating the water-repellent consolidant as having two layers with different water conductivities.

  13. From superhydrophobicity and water repellency to superhydrophilicity: smart polymer-functionalized surfaces.

    Science.gov (United States)

    Stratakis, Emmanuel; Mateescu, Anca; Barberoglou, Marios; Vamvakaki, Maria; Fotakis, Costas; Anastasiadis, Spiros H

    2010-06-21

    pH-responsive surfaces, reversibly switching between superhydrophilicity and superhydrophobicity/water repellency, are developed by "grafting from" a pH-sensitive polymer onto a hierarchically micro/nano-structured substrate. We quantify the water repellency by investigating the restitution coefficient of water droplets bouncing off the surfaces. The water repellent state requires appropriate hydrophobicity of the functionalizing polymer as well as very low values of contact angle hysteresis.

  14. Application of minidisk infiltrometer to estimate soil water repellency

    Science.gov (United States)

    Alagna, Vincenzo; Iovino, Massimo; Bagarello, Vincenzo; Mataix-Solera, Jorge; Lichner, Ľubomír

    2016-04-01

    Soil water repellency (SWR) reduces affinity of soils to water resulting in detrimental implication for plants growth as well as for hydrological processes. During the last decades, it has become clear that SWR is much more widespread than formerly thought, having been reported for a wide variety of soils, land uses and climatic conditions. The repellency index (RI), based on soil-water to soil-ethanol sorptivity ratio, was proposed to characterize subcritical SWR that is the situation where a low degree of repellency impedes infiltration but does not prevent it. The minidisk infiltrometer allows adequate field assessment of RI inherently scaled to account for soil physical properties other than hydrophobicity (e.g., the volume, connectivity and the geometry of pores) that directly influence the hydrological processes. There are however some issues that still need consideration. For example, use of a fixed time for both water and ethanol sorptivity estimation may lead to inaccurate RI values given that water infiltration could be negligible whereas ethanol sorptivity could be overestimated due to influence of gravity and lateral diffusion that rapidly come into play when the infiltration process is very fast. Moreover, water and ethanol sorptivity values need to be determined at different infiltration sites thus implying that a large number of replicated runs should be carried out to obtain a reliable estimate of RI for a given area. Minidisk infiltrometer tests, conducted under different initial soil moisture and management conditions in the experimental sites of Ciavolo, Trapani (Italy) and Javea, Alicante (East Spain), were used to investigate the best applicative procedure to estimate RI. In particular, different techniques to estimate the water, Sw, and ethanol, Se, sorptivities were compared including i) a fixed 1-min time interval, ii) the slope of early-time 1D infiltration equation and iii) the two-term transient 3D infiltration equation that explicitly

  15. Measuring and understanding soil water repellency through novel interdisciplinary approaches

    Science.gov (United States)

    Balshaw, Helen; Douglas, Peter; Doerr, Stefan; Davies, Matthew

    2017-04-01

    Food security and production is one of the key global issues faced by society. It has become evermore essential to work the land efficiently, through better soil management and agronomy whilst protecting the environment from air and water pollution. The failure of soil to absorb water - soil water repellency - can lead to major environmental problems such as increased overland flow and soil erosion, poor uptake of agricultural chemicals and increased risk of groundwater pollution due to the rapid transfer of contaminants and nutrient leaching through uneven wetting and preferential flow pathways. Understanding the causes of soil hydrophobicity is essential for the development of effective methods for its amelioration, supporting environmental stability and food security. Organic compounds deposited on soil mineral or aggregate surfaces have long been recognised as a major factor in causing soil water repellency. It is widely accepted that the main groups of compounds responsible are long-chain acids, alkanes and other organic compounds with hydrophobic properties. However, when reapplied to sands and soils, the degree of water repellency induced by these compounds and mixtures varied widely with compound type, amount and mixture, in a seemingly unpredictable way. Our research to date involves two new approaches for studying soil wetting. 1) We challenge the theoretical basis of current ideas on the measured water/soil contact angle measurements. Much past and current discussion involves Wenzel and Cassie-Baxter models to explain anomalously high contact angles for organics on soils, however here we propose that these anomalously high measured contact angles are a consequence of the measurement of a water drop on an irregular non-planar surface rather than the thermodynamic factors of the Cassie-Baxter and Wenzel models. In our analysis we have successfully used a much simpler geometric approach for non-flat surfaces such as soil. 2) Fluorescent and phosphorescent

  16. Solute leaching in a sandy soil with a water-repellent surface layer: a simulation.

    NARCIS (Netherlands)

    Rooij, de G.H.; Vries, de P.

    1996-01-01

    Many sandy soils in the Netherlands have a water-repellent surface layer covering a wettable soil with a shallow groundwater table. Fingers form in the water-repellent surface layer and rapidly transport water and solutes to the wettable soil in which the streamlines diverge. Although several field

  17. Water repellency of clay, sand and organic soils in Finland

    Directory of Open Access Journals (Sweden)

    K. RASA

    2008-12-01

    Full Text Available Water repellency (WR delays soil wetting process, increases preferential flow and may give rise to surface runoff and consequent erosion. WR is commonly recognized in the soils of warm and temperate climates. To explore the occurrence of WR in soils in Finland, soil R index was studied on 12 sites of different soil types. The effects of soil management practice, vegetation age, soil moisture and drying temperature on WR were studied by a mini-infiltrometer with samples from depths of 0-5 and 5-10 cm. All studied sites exhibited WR (R index >1.95 at the time of sampling. WR increased as follows: sand (R = 1.8-5.0 < clay (R = 2.4-10.3 < organic (R = 7.9-undefined. At clay and sand, WR was generally higher at the soil surface and at the older sites (14 yr., where organic matter is accumulated. Below 41 vol. % water content these mineral soils were water repellent whereas organic soil exhibited WR even at saturation. These results show that soil WR also reduces water infiltration at the prevalent field moisture regime in the soils of boreal climate. The ageing of vegetation increases WR and on the other hand, cultivation reduces or hinders the development of WR.;

  18. Laser removal of water repellent treatments on limestone

    Science.gov (United States)

    Gómez-Heras, Miguel; Alvarez de Buergo, Mónica; Rebollar, Esther; Oujja, Mohamed; Castillejo, Marta; Fort, Rafael

    2003-12-01

    Protective and water repellent treatments are applied on stone materials used on buildings or sculptures of artistic value to reduce water intrusion without limiting the natural permeability to water vapour of the material. The effect of the wavelength associated with the laser removal of two water repellent treatments applied on limestone, Paraloid B-72, a copolymer of methyl acrylate and ethyl methacrylate, and Tegosivin HL-100, a modified polysiloxane resin, was investigated by using the four harmonics of a Q-switched Nd:YAG laser (1064, 532, 355 and 266 nm). The modifications induced on the surface of limestone samples by laser irradiation were studied using colorimetry, roughness measurements and scanning electron microscopy (SEM). The removal of the treatments was found to be dependent on the laser irradiation conditions and on the characteristics of the coatings. The fundamental laser radiation was effective in removing both treatments, but thermal alteration processes were induced on the constituent calcite crystals. The best results were obtained by irradiation in the near UV at 355 nm.

  19. Laser removal of water repellent treatments on limestone

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Heras, Miguel; Alvarez de Buergo, Monica; Rebollar, Esther; Oujja, Mohamed; Castillejo, Marta; Fort, Rafael

    2003-12-15

    Protective and water repellent treatments are applied on stone materials used on buildings or sculptures of artistic value to reduce water intrusion without limiting the natural permeability to water vapour of the material. The effect of the wavelength associated with the laser removal of two water repellent treatments applied on limestone, Paraloid B-72, a copolymer of methyl acrylate and ethyl methacrylate, and Tegosivin HL-100, a modified polysiloxane resin, was investigated by using the four harmonics of a Q-switched Nd:YAG laser (1064, 532, 355 and 266 nm). The modifications induced on the surface of limestone samples by laser irradiation were studied using colorimetry, roughness measurements and scanning electron microscopy (SEM). The removal of the treatments was found to be dependent on the laser irradiation conditions and on the characteristics of the coatings. The fundamental laser radiation was effective in removing both treatments, but thermal alteration processes were induced on the constituent calcite crystals. The best results were obtained by irradiation in the near UV at 355 nm.

  20. Water repellency under natural conditions in sandy soils of southern Spain

    NARCIS (Netherlands)

    Moral García, F.J.; Dekker, L.W.; Oostindie, K.; Ritsema, C.J.

    2005-01-01

    The occurrence and consequences of fire-induced water repellency have been studied in several regions of Spain since 1989. The occurrence of water repellency formed under natural conditions, however, has only been described for a few areas in Spain since 1998. The purpose of the present study was to

  1. Temporal fluctuations in soil water repellency following wildfire in chaparral steeplands, southern California

    Science.gov (United States)

    K.R. Hubbert; V. Oriol

    2005-01-01

    Soil water repellency is partularly common in unburned chaparral, and its degree and duration can be influenced by seasonal weather conditions. Water repellency tends to increase in dry soils, whil eit decreases or vanishes following precipitation or extended periods of soil moisture. The 15426 ha Williams Fire provided an opportunity to investigate post-fire...

  2. Pre- and postfire distribution of soil water repellency in a steep chaparral watershed

    Science.gov (United States)

    K. R. Hubbert; P. M. Wohlgemuth; H. K. Preisler

    2008-01-01

    The development and nature of water repellent soils and their spatial distribution on the landscape are not well understood relative to evaluating hillslope response to fire. Soil water repellency is particularly common in chaparral communities, due in part to the coarse-textured soils, and the high resin content of the organic litter. Objectives of this study were 1)...

  3. Surfactant seed coating - a strategy to improve turfgrass establishment on water repellent soils

    Science.gov (United States)

    Turfgrass managers can experience poor seeding success when trying to establish golf course greens and sports fields on water repellent soils. Nonionic soil surfactant formulations based on ethylene oxide-propylene oxide (EO/PO) block copolymers are commonly used to treat water repellent soils. Rece...

  4. Layers of Porous Superhydrophobic Surfaces for Robust Water Repellency

    Science.gov (United States)

    Ahmadi, Farzad; Boreyko, Jonathan; Nature-Inspired Fluids; Interfaces Team

    2015-11-01

    In nature, birds exhibit multiple layers of superhydrophobic feathers that repel water. Inspired by bird feathers, we utilize porous superhydrophobic surfaces and compare the wetting and dewetting characteristics of a single surface to stacks of multiple surfaces. The superhydrophobic surfaces were submerged in water in a closed chamber. Pressurized gas was regulated to measure the critical pressure for the water to fully penetrate through the surfaces. In addition to using duck feathers, two-tier porous superhydrophobic surfaces were fabricated to serve as synthetic mimics with a controlled surface structure. The energy barrier for the wetting transition was modeled as a function of the number of layers and their orientations with respect to each other. Moreover, after partial impalement into a subset of the superhydrophobic layers, it was observed that a full dewetting transition was possible, which suggests that natural organisms can exploit their multiple layers to prevent irreversible wetting.

  5. The effect of land use on spatial variability of soil water repelency

    Science.gov (United States)

    Hrabovský, Andrej; Dlapa, Pavel; Chrenková, Katarína; Šimkovic, Ivan

    2016-04-01

    Soil water repellency was identified as a fundamental phenomenon during a soil survey dedicated to soil hydrological properties and processes in watersheds of the Little Carpathians Mts. (SW Slovakia). The investigated area represents the viticulture region with various soil management practices. Thus, soils of the region are influenced by deep ploughing during vineyard establishment, by cultivation of vineyards, by reforestation of abandoned vineyards as well as by long-term forestry practices. The soils developed from granitic rocks are naturally susceptible to water repellency development. The obtained results showed marked variability in physical and chemical soil properties. In particular, the soil pH values, the clay and organic carbon contents differed significantly depending on soil management. Due to these differences, the soil water repellency increased from wettable to extremely water repellent approximately in order: deeply ploughed vineyard soils water repellency on infiltration process was observed by means of field experiments.

  6. How to repel hot water from a superhydrophobic surface?

    KAUST Repository

    Yu, Zhejun

    2014-01-01

    Superhydrophobic surfaces, with water contact angles greater than 150° and slide angles less than 10°, have attracted a great deal of attention due to their self-cleaning ability and excellent water-repellency. It is commonly accepted that a superhydrophobic surface loses its superhydrophobicity in contact with water hotter than 50 °C. Such a phenomenon was recently demonstrated by Liu et al. [J. Mater. Chem., 2009, 19, 5602], using both natural lotus leaf and artificial leaf-like surfaces. However, our work has shown that superhydrophobic surfaces maintained their superhydrophobicity, even in water at 80 °C, provided that the leaf temperature is greater than that of the water droplet. In this paper, we report on the wettability of water droplets on superhydrophobic thin films, as a function of both their temperatures. The results have shown that both the water contact and slide angles on the surfaces will remain unchanged when the temperature of the water droplet is greater than that of the surface. The water contact angle, or the slide angle, will decrease or increase, however, with droplet temperatures increasingly greater than that of the surfaces. We propose that, in such cases, the loss of superhydrophobicity of the surfaces is caused by evaporation of the hot water molecules and their condensation on the cooler surface. © 2014 the Partner Organisations.

  7. Room temperature synthesis of water-repellent polystyrene nanocomposite coating

    Energy Technology Data Exchange (ETDEWEB)

    Guo Yonggang; Jiang Dong [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate School, Chinese Academy of Sciences, Beijing 100039 (China); Zhang Xia; Zhang Zhijun [Laboratory of Special Functional Materials, Henan University, Kaifeng 475001 (China); Wang Qihua, E-mail: wangqh@lzb.ac.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2010-09-15

    A stable superhydrophobic polystyrene nanocomposite coating was fabricated by means of a very simple and easy method. The coating was characterized by scanning electron microscopy and X-ray photoelectron spectrum. The wettability of the products was also investigated. By adding the surface-modified SiO{sub 2} nanoparticles, the wettability of the coating changed to water-repellent superhydrophobic, not only for pure water, but also for a wide pH range of corrosive liquids. The influence of the drying temperature and SiO{sub 2} content on the wettability of the nanocomposite coating was also investigated. It was found that both factors had little or no significant effect on the wetting behavior of the coating surface.

  8. Application of Super-Hydrophobic Coating for Enhanced Water Repellency of Ballistic Fabric

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Barton [ORNL; Rajic, Slobodan [ORNL; Hunter, Scott Robert [ORNL

    2014-10-01

    The objective of this work was to demonstrate that a superhydrophobic coating technology developed at Oak Ridge National Laboratory (ORNL) increases the water repellency of ballistic fabric beyond that provided by existing water repellency treatments. This increased water repellency has the potential to provide durable ballistic fabric for body armor without adding significant weight to the armor or significant manufacturing cost. Specimens of greige and scoured ballistic fabric were treated with a superhydrophobic coating and their weights and degree of water repellency were compared to specimens of untreated fabric. Treatment of both greige and scoured ballistic fabrics yielded highly water repellent fabrics. Our measurements of the water droplet contact angles gave values of approximately 150 , near the lower limit of 160 for superhydrophobic surfaces. The coatings increased the fabric weights by approximately 6%, an amount that is many times less than the estimated weight increase in a conventional treatment of ballistic fabric. The treated fabrics retained a significant amount of water repellency following a basic abrasion test, with water droplet contact angles decreasing by 14 to 23 . Microscopic analysis of the coating applied to woven fabrics indicated that the coating adhered equally well to fibers of greige and scoured yarns. Future evaluation of the superhydrophobic water repellent treatment will involve the manufacture of shoot packs of treated fabric for ballistic testing and provide an analysis of manufacturing scale-up and cost-to-benefit considerations.

  9. Soil water repellency in an old and young pasture in relation to N application

    NARCIS (Netherlands)

    Sonneveld, M.P.W.

    2008-01-01

    Ageing of pastures is likely to affect the degree of potential water repellency in the long term, whereas seasonal variation on a shorter term affects the actual repellency of soils. A 1-year study on two pastures of different ages was conducted on a sandy soil to assess changes in the degree of

  10. Synthesis and applications of vegetable oil-based fluorocarbon water repellent agents on cotton fabrics.

    Science.gov (United States)

    Zhao, Tao; Zheng, Junzhi; Sun, Gang

    2012-06-05

    Vegetable oil-based fluorocarbon water repellent agents were prepared by chemical modifications of different vegetable oils - soybean and linseed oils through several reactions, including saponification, acidification, acylation of vegetable oil and trans-esterification with 2,2,2-trifluoroethanol and 2,2,3,3-tetrafluoropropanol. The resulted fluorocarbon agents were then copolymerized with styrene. The structures of the vegetable oil based agents were characterized by FT-IR and NMR. By evaluating water contact angle and time of water disappearance on cotton fabrics, as well as whiteness and breaking strength of cotton fabrics that were treated by these agents, optimum fabric finishing conditions were explored. The cotton fabrics finished with the vegetable oil-based fluorocarbon agents showed excellent water repellency, while other properties of the cotton fabrics declined to certain level. The linseed oil-based tetrafluoropropanol water repellent agent displayed the highest water repellency among all modified oils. All the treated fabrics exhibited good durability of water repellency. The linseed oil-based tetrafluoropropanol water repellent agent demonstrated the best durability among all repellent agents. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. Impacts of grass removal on wetting and actual water repellency in a sandy soil

    National Research Council Canada - National Science Library

    Klaas Oostindie; Louis W. Dekker; Jan G. Wesseling; Violette Geissen; Coen J. Ritsema

    2017-01-01

    Soil water content and actual water repellency were assessed for soil profiles at two sites in a bare and grasscovered plot of a sand pasture, to investigate the impact of the grass removal on both properties...

  12. Formation process of a strong water-repellent alumina surface by the sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Feng Libang, E-mail: lepond@hotmail.com [School of Mechatronic Engineering, Lanzhou Jiaotong University, 88 West Anning Road, Lanzhou 730070 (China); Li Hui; Song Yongfeng; Wang Yulong [School of Mechatronic Engineering, Lanzhou Jiaotong University, 88 West Anning Road, Lanzhou 730070 (China)

    2010-03-01

    A novel strong water-repellent alumina thin film is fabricated by chemically adsorbing stearic acid (STA) layer onto the porous and roughened aluminum film coated with polyethyleneimine (PEI). The formation process and the structure of the strong water-repellent alumina film are investigated by means of contact angle measurement and atomic force microscope (AFM). Results show that the water contact angles for the alumina films increase with the increase of the immersion time in the boiling water, and meanwhile, the roughness of the alumina films increases with the dissolution of the boehmite in the boiling water. Finally, the strong water-repellent film with a high water contact angle of 139.1 deg. is obtained when the alumina films have distinct roughened morphology with some papillary peaks and porous structure. Moreover, both the roughened structure and the hydrophobic materials of the STA endow the alumina films with the strong water-repellence.

  13. Formation process of a strong water-repellent alumina surface by the sol-gel method

    Science.gov (United States)

    Feng, Libang; Li, Hui; Song, Yongfeng; Wang, Yulong

    2010-03-01

    A novel strong water-repellent alumina thin film is fabricated by chemically adsorbing stearic acid (STA) layer onto the porous and roughened aluminum film coated with polyethyleneimine (PEI). The formation process and the structure of the strong water-repellent alumina film are investigated by means of contact angle measurement and atomic force microscope (AFM). Results show that the water contact angles for the alumina films increase with the increase of the immersion time in the boiling water, and meanwhile, the roughness of the alumina films increases with the dissolution of the boehmite in the boiling water. Finally, the strong water-repellent film with a high water contact angle of 139.1° is obtained when the alumina films have distinct roughened morphology with some papillary peaks and porous structure. Moreover, both the roughened structure and the hydrophobic materials of the STA endow the alumina films with the strong water-repellence.

  14. Relationship between water repellency and native and petroleum-derived organic carbon in soils.

    Science.gov (United States)

    Roy, J L; McGill, W B; Lowen, H A; Johnson, R L

    2003-01-01

    Some soils develop severe and persistent water repellency following contamination with crude oil. This study was conducted to characterize and compare the spatial distribution of soil water repellency and residual oil contamination at 12 such sites. The molarity of ethanol droplet (MED) test was used to assess soil water repellency and the content of dichloromethane-extractable organics (DEO) was used to quantify residual oil in soil. We found a relatively strong positive correlation between MED and DEO in soil (r2 = 0.74). Both variables tended to decrease abruptly with depth at 11 of the 12 study sites. Dichloromethane-extractable organics similarly decreased with depth in control adjacent soil (MED = 0 M), but from an average concentration one to two orders of magnitude lower than in water-repellent soil. Using data from corresponding control adjacent and water-repellent soils, we determined that approximately 29 and 10% of measured total organic carbon in water-repellent A- and B-horizon soil, respectively, consists of dichloromethane-insoluble organic carbon of petroleum origin. We propose that this fraction contains most of the causative agents of soil water repellency at the studied sites.

  15. Water repellency in the rhizosphere of maize: measurements and modelling

    Science.gov (United States)

    Ahmed, Mutez; Kroener, Eva; Carminati, Andrea

    2016-04-01

    Although maize roots have been extensively studied, there is limited information on the effect of root exudates on the hydraulic properties of maize rhizosphere. Recent experiments suggested that the mucilaginous fraction of root exudates may cause water repellency of the rhizosphere. Our objectives were: 1) to investigate whether maize rhizosphere turns hydrophobic after drying and subsequent rewetting; 2) to develop a new method to collect root mucilage and test whether maize mucilage is hydrophobic; and 3) to find a quantitative relation between rhizosphere rewetting, particle size, soil matric potential and mucilage concentration. Maize plants were grown in aluminum containers filled with a sandy soil. When the plants were three-weeks-old, the soil was let dry and then it was irrigated. The soil water content during irrigation was imaged using neutron radiography. In a parallel experiment, ten maize plants were grown in sandy soil for five weeks. Mucilage was collected from young brace roots using a new developed method. Mucilage was placed on glass slides and let dry. The contact angle was measured with the sessile drop method for varying mucilage concentration. Additionally, we used neutron radiography to perform capillary rise experiments in soils of varying particle size mixed with maize mucilage. We then used a pore-network model in which mucilage was randomly distributed in a cubic lattice. The general idea was that rewetting of a pore is impeded when the concentration of mucilage on the pore surface (g cm-2) is higher than a given threshold value. The threshold value depended on soil matric potential, pore radius and contact angle. Then, we randomly distributed mucilage in the pore network and we calculated the percolation of water across a cubic lattice for varying soil particle size, mucilage concentration and matric potential. Our results showed that: 1) the rhizosphere of maize stayed temporarily dry after irrigation; 2) mucilage became water

  16. Water Repellency, Infiltration and Water Retention Properties of Forest Soils Under Different Management Practices

    Science.gov (United States)

    Wahl, N. A.; Bens, O.; Schäfer, B.; Hüttl, R. F.

    For soils under both agricultural and forest use, management and tillage practice can have significant influence on the hydraulic properties. It is therefore supposed, that management practices are capable of altering surface runoff, water retention and flood- ing risk for river catchments. Soil water repellency (hydrophobicity) can adversely affect soil hydrological properties, e.g. reduce infiltration capacity and induce pref- erential flow, thus enhancing the overall risk of flooding in river catchment areas. Hydrophobic effects are especially pronounced in coniferous forest soils. Investigations were carried out on several study plots in the German Northeastern Lowlands, located app. 50 km NE of Berlin in Brandenburg. Soils found in the area are mainly of glacifluvial origin with a pronounced sandy texture (with medium sized sand dominating). The four stands investigated represent different stages of forest transfor- mation, in a sense of a SfalseT chronosequence and are made up of populations of & cedil;Pinus sylvestris and Fagus sylvatica of different ages. Infiltration was measured with hood infiltrometers, and single infiltration rings at soil surface. Water retention capacity and the influence of soil organic matter on water storage were evaluated with laboratory methods. Water repellency was quantified with the water drop penetration time (WDPT) test, for determining the persistence of water repellency, and the ethanol percentage (EP) test, for measuring the severity/degree of water repellency. Soil samples from the four forest plots and different soil depths (0U160 cm) were used for the measurements. SPotentialT water repellencies were & cedil;determined after 3-day oven-drying at 45 C. The results indicate that for sandy forest soils, the overall infiltration capacity of the plots is low due to the effects of water repellency. The inter-variability of the plots is mainly caused by changes in the textural composition of the soils. For all plots a

  17. Soil water repellency induced by long-term irrigation with treated sewage effluent.

    Science.gov (United States)

    Wallach, R; Ben-Arie, O; Graber, E R

    2005-01-01

    This study describes soil water repellency developed under prolonged irrigation with treated sewage effluent in a semiarid environment. Soil surface layer (0-5 cm) and soil profile (0-50 cm) transects were sampled at a high resolution at the close of the irrigation season and rainy winter season. Samples from 0- to 5-cm transects were subdivided into 1-cm slices to obtain fine scale resolution of repellency and organic matter distribution. Extreme to severe soil water repellency in the 0- to 5-cm soil surface layer persisted throughout the 2-yr study period in the effluent-irrigated Shamouti orange [Citrus sinensis (L.) Osbeck cv. Shamouti] orchard plot. Nearby Shamouti orange plots irrigated with tap water were either nonrepellent or only somewhat repellent. Repellency was very variable spatially and with depth, appearing in vertically oriented "repellency tongues." Temporal and spatial variability in repellency in the uppermost 5-cm soil surface layer was not related to seasonality, soil moisture content, or soil organic matter content. Nonuniform distribution of soil moisture and fingered flow were observed in the soil profile after both seasons, demonstrating that the repellent layer had a persistent effect on water flow in the soil profile. A lack of correlation between bulk density and volumetric water content in the soil profile demonstrates that the observed nonuniform spatial distribution of moisture results from preferential flow and not heterogeneity in soil properties. Soil water repellency can adversely affect agricultural production, cause contamination of underlying ground water resources, and result in excessive runoff and soil erosion.

  18. Competitive sorption of intermixed heavy metals in water repellent soil in Southern Australia

    Science.gov (United States)

    Li, P. J.; Stagnitti, F.; Xiong, X.; Li, P.

    2007-04-01

    In water repellent soil, Cr, Pb and Cu showed higher adsorption intensities than Zn, Cd and Ni did. Soil water repellency is much more widespread than formerly thought. In order to promote fertility and productivity, the irrigation of recycled water onto water repellent soil may be an applied technology to be used in some areas of Southern Australia. Therefore, heavy metals in recycled water potentially enter into the soil. The competitive sorption and retention capacity of heavy metals in soil are important to be determined, especially considering the special geochemical origin of water repellent soil that was caused by waxes on or between the soil particles. Batch equilibrium sorption experiments on Cd, Cr, Cu, Ni, Pb and Zn in their typical proportion in recycled water were conducted in water repellent soil. The sorption intensity, sorption isotherm in the experiments together showed that Cr, Pb and Cu have higher sorption intensity than those of Zn, Ni and Cd in the competitive system. The risk assessment for the application of recycled water onto water repellent soil is definitely necessary, especially for the metal cations with relatively weak sorption.

  19. Transport of water and solutes in wettable and water repellent sandy soils

    NARCIS (Netherlands)

    Ritsema, C.J.; Dekker, L.W.

    1996-01-01

    The research yielded the following conclusions and results: preferential flow can be expected in recently deposited, loosely packed, wettable dune sands; preferential flow is common in most water-repellent sandy soils; distribution flow in topsoils isa process of major importance, resulting in a

  20. Superior water repellency of water strider legs with hierarchical structures: experiments and analysis.

    Science.gov (United States)

    Feng, Xi-Qiao; Gao, Xuefeng; Wu, Ziniu; Jiang, Lei; Zheng, Quan-Shui

    2007-04-24

    Water striders are a type of insect with the remarkable ability to stand effortlessly and walk quickly on water. This article reports the water repellency mechanism of water strider legs. Scanning electron microscope (SEM) observations reveal the uniquely hierarchical structure on the legs, consisting of numerous oriented needle-shaped microsetae with elaborate nanogrooves. The maximal supporting force of a single leg against water surprisingly reaches up to 152 dynes, about 15 times the total body weight of this insect. We theoretically demonstrate that the cooperation of nanogroove structures on the oriented microsetae, in conjunction with the wax on the leg, renders such water repellency. This finding might be helpful in the design of innovative miniature aquatic devices and nonwetting materials.

  1. Estimation of soil water repellency of different particle size fractions in relation with carbon content by different methods.

    Science.gov (United States)

    Rodríguez-Alleres, María; de Blas, Esther; Benito, Elena

    2007-05-25

    The water repellency of soils with different texture under different types of plant cover was determined by applying the WDPT and MED methods to both whole samples and the following size fractions: 2-1, 1-0.5, 0.5-0.25, 0.25-0.05 and water repellency in the finest fraction (<0.05 mm) as a result of its higher organic carbon content. On the other hand, all fractions in the forest soils, which were extremely water repellent, contributed to the overall repellency; in any case, the MED test revealed that the finest fraction was strongly repellent in the forest soils as well.

  2. Morphology and functions of astrocytes cultured on water-repellent fractal tripalmitin surfaces.

    Science.gov (United States)

    Hu, Wei-wei; Wang, Zhe; Zhang, Shan-shan; Jiang, Lei; Zhang, Jing; Zhang, Xiangnan; Lei, Qun-fang; Park, Hyun-Joo; Fang, Wen-jun; Chen, Zhong

    2014-08-01

    In the brain, astrocytes play an essential role with their multiple functions and sophisticated structure, as surrounded by a fractal environment which has not been available in our traditional cell culture. Water-repellent fractal tripalmitin (PPP) surfaces can imitate the fractal environment in vivo, so the morphology and biochemical characterization of astrocytes on these surfaces are examined. Water-repellent fractal PPP surface can induce astrocytes to display sophisticated morphology with smaller size of cell area, longer and finer filopodium-like processes, and higher morphological complexity. The super water-repellent fractal PPP surface with water contact angle of 150°∼160° produces the maximal effects compared with other surfaces at lower water contact angles. The trends of characteristic protein expression, including that of nestin, vimentin, GFAP and glutamine synthetase, for astrocytes cultured on super water-repellent fractal PPP surfaces approximate more to in vivo pattern. The super water-repellent PPP surface also render astrocytes to perform more pronounced promotion of neurogenesis by increasing the release of nerve growth factor in a co-culture system. Altogether, our results suggest that the super water-repellent fractal PPP surface facilitates the astrocytes to mimic their in vivo performance, thus provides a closer-to-natural culture environment for experimental assessment of glial structure and functions.

  3. Boron nitride nanosheet coatings with controllable water repellency.

    Science.gov (United States)

    Pakdel, Amir; Zhi, Chunyi; Bando, Yoshio; Nakayama, Tomonobu; Golberg, Dmitri

    2011-08-23

    The growth, structure, and properties of two-dimensional boron nitride (BN) nanostructures synthesized by a thermal chemical vapor deposition method have been systematically investigated. Most of the BN nanosheets (BNNSs) were less than 5 nm in thickness, and their purity was confirmed by X-ray energy dispersive spectroscopy, X-ray photoelectron spectroscopy, electron energy loss spectroscopy, and Raman spectroscopy. The effects of the process variables on the morphology and roughness of the coatings were studied using atomic force microscopy and scanning electron microscopy. A smooth BN coating was obtained at 900 °C, while compact BNNS coatings composed of partially vertically aligned nanosheets could be achieved at 1000 °C and higher temperatures. These nanosheets were mostly separated and exhibited high surface area especially at higher synthesis temperatures. The nonwetting properties of the BNNS coatings were independent of the water pH and were examined by contact angle goniometry. The present results enable a convenient growth of pure BNNS coatings with controllable levels of water repellency, ranging from partial hydrophilicity to superhydrophobicity with contact angles exceeding 150°. © 2011 American Chemical Society

  4. Lime-based repair mortars with water-repellent admixtures: laboratory durability assessment

    OpenAIRE

    Nunes, C.; Slížková, Z. (Zuzana)

    2015-01-01

    Conservation of architectural structures using lime binders is currently an important research topic aiming compatibility, durability and sustainability. In this study, lime (L) and lime-metakaolin (LM) mortars were prepared with the addition of water-repellent admixtures: linseed oil, stand oil and a silane based water-repellent. Experimental results demonstrate that oil imparts higher hydrophobicity to both L and LM mixtures. Durability was assessed through freeze-thaw and NaCl crystal...

  5. Spatial Patterns of Post-Fire Soil Water Repellency in Rangelands

    Science.gov (United States)

    Nelson, N. A.; Pierce, J. L.

    2006-12-01

    Water repellent soils are naturally occurring but can be created or enhanced by wildfires. Post-fire runoff and the occurrence of fire-related floods and debris flows are related to the extent and continuity of water repellent soils. While many studies have positively correlated post-fire soil water repellency with burn severity and ash thickness in forested and chaparral environments, few studies have examined fire-related water repellency in sage-bitterbrush rangelands (but see Pierson et al., 2001). Rangelands, which comprise 40% of the landmass of the United States and nearly 80% of the lands of the western U.S., burn frequently during the summer with burn areas that often exceed 200 km2. The most commonly used method to measure the extent and severity of post-fire soil water repellency is the water drop penetration test (WDPT): other tests include the molarity of ethanol test, infiltration measured with a minidisk infiltrometer, and patterns of water infiltration measured with blue dye. Unlike tests that measure time until infiltration, the blue dye test provides a means of measuring the spatial extent of water repellent soils as well as area quantification of water saturation and locations of subsurface flowpaths. In early July, 2006, fires burned approximately 1.6 km2 of sagebrush and bitterbrush-dominated rangelands in foothills near Boise, Idaho. Initial studies in August 2006 using both water drop penetration time and the blue dye test show that soil water repellency is highly variable in both extent and severity, and that repellency varies with proximity to burned sage or bitterbrush coppice sites. Out of sixty sample sites, slight soil water repellency occurred outside of coppice boundaries on three occasions, each time in an area with grass and within 1 m of a coppice. Not all coppices exhibited soil water repellency, and only 23% of sites within coppice boundaries exhibited moderate to strong water repellency, as measured by WDPT. Use of the blue dye

  6. Formation of Soil Water Repellency by Laboratory Burning and Its Effect on Soil Evaporation

    Science.gov (United States)

    Ahn, Sujung; Im, Sangjun

    2010-05-01

    Fire-induced soil water repellency can vary with burning conditions, and may lead to significant changes in soil hydraulic properties. However, isolation of the effects of soil water repellency from other factors is difficult, particularly under field conditions. This study was conducted to (i) investigate the effects of burning using different plant leaf materials and (ii) of different burning conditions on the formation of soil water repellency, and (iii) isolate the effects of the resulting soil water repellency on soil evaporation from other factors. Burning treatments were performed on the surface of homogeneous fully wettable sand soil contained in a steel frame (60 x 60 cm; 40 cm depth). As controls a sample without a heat treatment, and a heated sample without fuel, were also used. Ignition and heat treatments were carried out with a gas torch. For comparing the effects of different burning conditions, fuel types included oven-dried pine needles (fresh needles of Pinus densiflora), pine needle litter (litter on a coniferous forest floor, P. densiflora + P. rigida), and broad-leaf litter (Quercus mongolica + Q. aliena + Prunus serrulata var. spontanea + other species); fuel loads were 200 g, 300 g, and 500 g; and heating duration was 40 s, 90 s and 180 s. The heating duration was adjusted to control the temperature, based on previous experiments. The temperature was measured continuously at 3-second intervals and logged with two thermometers. After burning, undisturbed soil columns were sampled for subsequent experiments. Water Drop Penetration Time (WDPT) test was performed at every 1 mm depth of the soil columns to measure the severity of soil water repellency and its vertical extent. Soil water repellency was detected following all treatments. As the duration of heating increased, the thickness of the water repellent layer increased, whilst the severity of soil water repellency decreased. As regards fuel amount, the most severe soil water repellency was

  7. Facile Method to Prepare Superhydrophobic and Water Repellent Cellulosic Paper

    Directory of Open Access Journals (Sweden)

    Ioannis Karapanagiotis

    2015-01-01

    Full Text Available Silica nanoparticles (7 nm were dispersed in solutions of a silane/siloxane mixture. The dispersions were applied, by brush, on four types of paper: (i modern, unprinted (blank paper, (ii modern paper where a text was printed using a common laser jet printer, (iii a handmade paper sheet detached from an old book, and (iv Japanese tissue paper. It is shown that superhydrophobicity and water repellency were achieved on the surface of the deposited films, when high particle concentrations were used (≥1% w/v, corresponding to high static (θS ≈ 162° and low tilt (θt < 3° contact angles. To interpret these results, scanning electron microscopy (SEM was employed to observe the surface morphologies of the siloxane-nanoparticle films. Static contact angles, measured on surfaces that were prepared from dilute dispersions (particle concentration <1% w/v, increased with particle concentration and attained a maximum value (162° which corresponds to superhydrophobicity. Increasing further the particle concentration did not have any effect on θS. Colourimetric measurements showed that the superhydrophobic films had negligible effects on the aesthetic appearance of the treated papers. Furthermore, it is shown that the superhydrophobic character of the siloxane-nanoparticle films was stable over a wide range of pH.

  8. Water-repellent soil and its relationship to granularity, surface roughness and hydrophobicity: a materials science view

    OpenAIRE

    McHale, Glen; Newton, Michael; Shirtcliffe, Neil

    2005-01-01

    Considerable soil water repellency has been observed at a wide range of locations worldwide. The soil exhibiting water repellency is found within the upper part of the soil profile. The reduced rate of water infiltration into these soils leads to severe run-off erosion, and reduction of plant growth. Soil water repellency is promoted by drying of soil, and can be induced by fire or intense heating of soil containing hydrophobic organic matter. Recent studies outside of soil science have shown...

  9. Water repellent soils following prescribed burning treatments and a wildfire in the oak savannas of the Malpai Borderlands Region

    Science.gov (United States)

    Cody L. Stropki; Peter F. Ffolliott; Gerald J. Gottfried

    2009-01-01

    Water repellent (hydrophobic) soils impact the infiltration process of a water budget by restricting the movement of water into and through a soil body. The infiltration of water into a water repellent soil can be inhibited or completely impeded in which case much of the incoming precipitation reaching the soil surface becomes overland flow. One mechanism causing the...

  10. Temporal patterns of infiltration into a water repellent soil under field conditions

    Science.gov (United States)

    Ward, Phil; Roper, Margaret; Micin, Shayne; Jongepier, Ramona

    2014-05-01

    Water repellency causes substantial economic losses for farmers in southern Australia through impacts on crop growth and weed germination. However, recent research has demonstrated that laboratory measurements of water repellency may not be a reliable indicator of the severity of symptoms experienced in the field. In particular, crop residue retention and minimal soil disturbance led to increased water repellency, but was also associated with higher soil water contents measured at strategic times of the year. Little is known about the temporal patterns of soil water storage close to the soil surface in a water repellent sand. In this research we measured soil water content at a depth of 0.05 m at 15-minute intervals from June 2011 to October 2012, under various treatment combinations of residue retention and soil disturbance. Measurements were made in both 'crop row' and 'crop inter-row' positions. For a rainfall event (9.2 mm) in March 2012, prior to crop seeding, plots previously established with no-till absorbed significantly more water (increase in soil water content of 0.074 v/v) than plots conventionally cultivated (0.038 v/v). In June 2012 (12.6 mm), 4 weeks after crop seeding, tillage was again significant, and there was a significant interaction between tillage and 'row' or 'inter-row' position. These results demonstrate the importance of crop management in modifying the response of water repellent soils to rainfall in the field.

  11. Spatial and temporal variability of water repellency in a sandy soil contaminated with tar oil and heavy metals.

    Science.gov (United States)

    Buczko, Uwe; Bens, Oliver; Durner, Wolfgang

    2006-12-15

    Water repellency can induce preferential flow and thus affect water flow and contaminant transport at hazardous waste sites. Since the spatial patterns of water repellency are mostly unknown, it is problematic to use numerical transport models to predict leachate composition. In this study, the spatial variability of soil water repellency was studied at an industrial site contaminated with tar oil, chromium, copper and arsenic. The persistence of water repellency was assessed by the water drop penetration time (WDPT), and the degree of water repellency was quantified by the ethanol percentage (EP) test. Measurements were made at the soil surface along 3.5-12.1 m long transects at different times between March and October 2002. The spatial variability of WDPT, EP, water content, and organic matter content was quantified by variogram analyses. Both the persistence and the degree of water repellency varied seasonally, with the highest water repellency during the summer months. The correlation lengths of WDPT values ranged between 16 and 406 cm, whereas EP values showed no spatial correlation. For field-moist samples, a critical soil water threshold, below which water repellency prevails, was estimated to be 2.5-4%. For oven dry samples, the WDPT values were dependent on the water content prior to drying. The wide range of correlation lengths and the temporal dynamics of spatial repellency patterns suggest that simulations of solute leaching must consider the spatial and temporal variability of soil hydrophobic properties.

  12. Experimental Investigation of Evaporation and Drainage in Wettable and Water-Repellent Sands

    Directory of Open Access Journals (Sweden)

    Dae Hyun Kim

    2015-05-01

    Full Text Available This study presents experimental results on evaporation and drainage in both wettable and water-repellent sands whose surface wettability was artificially modified by silanization. The 2D optical and 3D X-ray computed tomographic imaging was performed during evaporation and the water retention during cyclic drainage and infiltration was measured to assess effects of wettability and initial wetting conditions. The evaporation gradually induces its front at the early stage advance regardless of the wettability and sand types, while its rate becomes higher in water-repellent Ottawa sand than the wettable one. Jumunjin sand which has a smaller particle size and irregular particle shape than Ottawa sand exhibits a similar evaporation rate independent of wettability. Water-repellent sand can facilitate the evaporation when both wettable and water-repellent sands are naturally in contact with each other. The 3D X-ray imaging reveals that the hydraulically connected water films in wettable sands facilitate the propagation of the evaporation front into the soil such that the drying front deeply advances into the soil. For cyclic drainage-infiltration testing, the evolution of water retention is similar in both wettable and water-repellent sands when both are initially wet. However, when conditions are initially dry, water-repellent sands exhibit low residual saturation values. The experimental observations made from this study propose that the surface wettability may not be a sole factor while the degree of water-repellency, type of sands, and initial wetting condition are predominant when assessing evaporation and drainage behaviors.

  13. Hyperspectral Remote Sensing to Detect Water Repellent Soil Conditions after Forest Fires

    Science.gov (United States)

    Lewis, S. A.; Robichaud, P. R.; Wu, J. Q.

    2002-12-01

    The burning of organic surface litter during forest fires often results in a water repellent soil layer at or near the soil surface. Organic matter is volatilized and a significant fraction moves into the upper soil layers (top 5 cm). Upon cooling, soil particles are coated with hydrophobic organic substances and the soil displays drastically reduced infiltration capabilities. The degree of water repellency is related to the amount of organic material on the surface prior to the fire, and the duration and temperature of the burn. Carbon compounds that are indicative of burned organic matter have been identified spectrally in soils under laboratory conditions. The 1000-2500 nm (near through short wave infrared) range is the span of the electromagnetic spectrum exhibiting significant adsorption for many organic compounds. Since burning alters surface organic matter and it is possible to detect such a change spectrally, a hyperspectral sensor should be able to provide information ultimately relating the change in organic matter to soil water repellency. This study aims to use a hyperspectral sensor to determine the degree of water repellency of surface soil in three burn classifications (low, moderate, and high) after a forest fire. One hundred eighty plots (sixty per burn class) were selected within the Hayman fire perimeter in southern Colorado in July 2002. A hand-held hyperspectral sensor was used to measure soil reflectance at several plots within each burn classification. An aerially- mounted hyperspectral sensor was also flown over the fire site. Twelve flight lines were flown to ensure contiguous coverage of the entire fire. The on-site ground truthing included both the Water Drop Penetration Time (WDPT) test and an infiltrometer test, with the former being a traditional method and the latter a new approach for testing water repellency. Both methods correlate the time to the start of infiltration with the degree of soil water repellency. The measured soil

  14. Thermal imaging of water repellence breakdown and build up following surfactant application

    Science.gov (United States)

    Alsih, Abdulkareem; Leopold, Matthias; McGrath, Gavan

    2017-04-01

    Surfactants are used in dry land cropping systems to improve water infiltration in water repellent soils, yet the dynamic nature of water repellence during various seasons and the associated hydrologic changes are still poorly understood. Here we evaluate surface temperature changes of a water repellent sand in response to irrigation and surfactant applications, reflecting infiltration, evaporation, and energy balance changes across multiple wetting-drying cycles. Using a near-infrared thermal camera soil surface temperatures of 15 1m2 plots were recorded at 10 minute intervals for three weeks. Plots differed by the width of surfactant application bands ( 16 cm, 25 cm, 50 cm, and 100 cm wide surfactant bands as well as a control with no surfactant), individual treatments were replicated three times. Temporal changes in the spatial variability was examined using semivariograms and wavelets. The semivariogram analysis indicates that in contrast to the thinnest surfactant bands, wide bands lead to a gradual increase in soil-temperature heterogeneity towards that seen in a control. Wavelets and time-distance plots reveal a non-linear switch in soil temperature dynamics for surfactant treated plots which were absent in 100 cm band and control plots. This switch, evident in the relative temperature differences across the plot during diurnal cycling, was associated with a gradual drop in ambient temperatures. These results image water repellence breakdown in the field. The study demonstrates the general suitability of using thermal surface properties of water repellent soils to investigate the dynamics of water repellence breakdown. This knowledge can be used to test the efficiency of available and new surfactant products to overcome water repellency.

  15. Soil-Water Repellency Characteristic Curves for Soil Profiles with Organic Carbon Gradients

    DEFF Research Database (Denmark)

    Wijewardana, Nadeeka Senani; Muller, Karin; Moldrup, Per

    2016-01-01

    Soil water repellency (SWR) of soils is a property with significant consequences for agricultural water management, water infiltration, contaminant transport, and for soil erosion. It is caused by the presence of hydrophobic agents on mineral grain surfaces. Soils were samples in different depths......, and the sessile drop method (SDM). The aim to (i) compare the methods, (ii) characterize the soil-water repellency characteristic curves (SWRCC) being SWR as a function of the volumetric soil-water content (θ) or matric potential (ψ), and (iii) find relationships between SWRCC parameters and SOC content. The WDPT...

  16. Role of flexibility in the water repellency of water strider legs: theory and experiment.

    Science.gov (United States)

    Ji, Xiang-Ying; Wang, Jia-Wen; Feng, Xi-Qiao

    2012-02-01

    Water striders enjoy an intriguing ability to stand and walk freely on water surfaces, which is mainly attributed to the superior water repellency of their slender legs. In previous theoretical analyses, the legs are usually treated as rigid beams and the results show that a tremendously deep dimple and a large supporting force can be achieved when the leg descends into water. In this paper, the effect of the flexibility of water strider legs on their water-repellent ability is investigated, both theoretically and experimentally. We analyze a hydrophobic and flexible leg pressing obliquely on water. The leg may undergo a large deformation and assume different geometric configurations. It is shown that the flexible leg can float easily on a water surface, inducing only a shallow water puddle and a moderate supporting force as observed in real water striders. When the long leg is sufficiently compliant, the water surface will never be pierced and the leg will never sink. The findings are experimentally testified by using flexible fibers to represent water strider legs pressing on water. © 2012 American Physical Society

  17. CO2 response to rewetting of hydrophobic soils - Can soil water repellency inhibit the 'Birch effect'?

    Science.gov (United States)

    Sanchez-Garcia, Carmen; Urbanek, Emilia; Doerr, Stefan

    2017-04-01

    Rewetting of dry soils is known to cause a short-term CO2 pulse commonly known as the 'Birch effect'. The displacement of CO2 with water during the process of wetting has been recognised as one of the sources of this pulse. The 'Birch effect' has been extensively observed in many soils, but some studies report a lack of such phenomenon, suggesting soil water repellency (SWR) as a potential cause. Water infiltration in water repellent soils can be severely restricted, causing overland flow or increased preferential flow, resulting in only a small proportion of soil pores being filled with water and therefore small gas-water replacement during wetting. Despite the suggestions of a different response of CO2 fluxes to wetting under hydrophobic conditions, this theory has never been tested. The aim of this study is to test the hypothesis that CO2 pulse does not occur during rewetting of water repellent soils. Dry homogeneous soils at water-repellent and wettable status have been rewetted with different amounts of water. CO2 flux as a response to wetting has been continuously measured with the CO2 flux analyser. Delays in infiltration and non-uniform heterogeneous water flow were observed in water repellent soils, causing an altered response in the CO2 pulse in comparison to typically observed 'Birch effect' in wettable systems. The main conclusion from the study is that water repellency not only affects water relations in soil, but has also an impact on greenhouse gas production and transport and therefore should be included as an important parameter during the sites monitoring and modelling of gas fluxes.

  18. Is topsoil water repellency a mechanism for improving water conservation in depth?

    Science.gov (United States)

    Lozano, Elena; Jiménez-Pinilla, Patricia; Mataix-Solera, Jorge; Arcenegui, Vicky; Mataix-Beneyto, Jorge

    2013-04-01

    Soil water repellency (WR) is widespread in forest soils under different climatic conditions, soil types and vegetation covers (Doerr et al., 2000). It is normally characterized by a high spatial variability in persistence, showing wettable and water repellent patches. This phenomenon has a special interest in semiarid areas, such as the Mediterranean ecosystems, where water resources are limited. For that reason, it is thought to be a possible mechanism for improving water conservation in soil profile, which would minimize evaporation losses from the soil surface (Doerr et al., 2000; Robinson et al. 2010). The ecological function of having a patchy hydrophobic surface might be the means of transporting water deeper into the soil profile and away from surface evaporation. In addition, it may also inhibit the growth of other vegetal species. This could increase the resistance of plants to drought by increasing water availability through reducing losses to surface evaporation or other plants. Our aim was to test the hypothesis that soil WR improves the water conservation within the soil. We have compared the temporal evolution of soil moisture between samples with repellent and wettable layers. Repellent and wettable soil samples were collected from an agricultural area in Biar (Alicante, Spain). Samples were put in 100ml plastic pots (n=30). Each one had two layers (WR and wettable or both wettable) with depth around 2.5cm for superficial and 3.5cm for deeper wettable horizon. We measured the evolution under different initial conditions of soil water content (around 20% and 9%) and soil superficial WR persistence (wettable, slight, strong and severe soil (n=5 per treatment)). Pots were kept under laboratory conditions (between 30-50% of relative air humidity and ? 20°C). Soil water content was controlled daily by weight measurement. Our results showed a clear significant difference in evaporation rates, which were higher in samples with a wettable superficial layer

  19. Fire impacts on water repellency of sandy soils in SW Spanish coast

    Science.gov (United States)

    Jordán, Antonio; Zavala, Lorena M.; Gordillo-Rivero, Ángel J.; Muñoz-Rojas, Miriam; Keesstra, Saskia; Cerdá, Artemi

    2017-04-01

    Although water repellency of sandy soils from dune areas and their consequences (irregular wetting front, preferential flow pathways) are well studied, there is not much information about the effect of fire on hydrophobicity and its consequences in these areas. In this paper we study the in-depth variation of water repellency of burnt sandy soils from south-western Spain. Generally, it was observed that water repellency from unburnt forest soils is relatively higher than in shrublands and grasslands (where the lowest values were observed). However, the impact of fire caused a strong increase of hydrophobicity in the first two cases, with no major differences between them. This study confirms the presence of natural water repellency in sandy soils, as well as some of its consequences (irregular infiltration or increased surface water flow) depending on the type of vegetation, although the differences observed in burnt soils suggest that, although the composition of vegetation is important in the formation of natural water repellency, organic matter content is much more important in the case of burnt soils.

  20. Linking fractional wettability and contact angle dynamics in water repellent soils

    Science.gov (United States)

    Beatty, Sarah; Smith, James

    2016-04-01

    Dynamic soil water repellency has become a highly documented soil phenomenon across a range of environmental conditions and investigated within a range of disciplines. With global climate change at the environmental science fore, there is growing concern and need for accurate quantification of fundamental soil hydraulic properties and model parameterization. In the presence of soil water repellency, however, substantial unknowns remain in terms of characterizing repellency and drawing linkages to fundamental hydraulic parameters. This is often related to the complexity of investigating soil water repellency, which is often a challenging environment because of its spatially and temporally variable nature. To help bridge this gap, this work reports on different approaches using various technologies to explore opportunities that yield greater quantification and parametrization of soil water repellency in natural hydrologic systems at different scales. These approaches include X-ray microtomography (μXCT), Axisymmetric Drop Shape Analysis (ADSA), Drop Penetration tests (MED/WDPT), and Tension Infiltrometry. This work has shown the strength of conceptually linking contact angle dynamics and fractional wettability as a means to understand the nature of infiltration in water repellent soils and provide a mechanistic foundation upon which repellency can be quantified and related to fundamental hydraulic properties. Contact angle dynamics and fractional wettability are complimentary terminology that appear in the multiphase flow and soil physics literature, but have largely/essentially only been applied in synthetic systems. Their utility in natural environments is potentially significant and conceptually useful since they can readily incorporate existing characterizations while providing greater opportunity for articulating and defining specific behaviours in systems with high spatial and temporal heterogeneity.

  1. Organic compounds of different extractability in total solvent extracts from soils of contrasting water repellency

    Science.gov (United States)

    Atanassova, Irena; Doerr, Stefan H.

    2010-05-01

    Previous studies examining organic compounds that may cause water-repellent behaviour of soils have typically focussed on analysing only the lipophilic fraction of extracted material. This study aimed to provide a more comprehensive examination by applying single- and sequential-accelerated solvent extraction (ASE), separation and analysis by GC/MS of the total solvent extracts of three soils taken from under eucalypt vegetation with different levels of water repellency. Water repellency increased in all the soils after extraction with DCM:MeOH (95:5), but was eliminated with iso-propanol/ammonia (95:5). Quantities of major lipid compound classes varied between solvents and soils. Iso-propanol/ammonia (95:5) solvent released saccharides, glycerol, aromatic acids and other polar organic compounds, which were more abundant in fractionated extracts from the single extraction and the third step sequential ASE extraction, than in the extracts from the DCM:MeOH ASE solvent. Dominant compounds extracted from all soils were long-chain alkanols (>C22), palmitic acid, C29 alkane, β-sitosterol, terpenes, terpenoids and other polar compounds. The soil with smallest repellency lacked >C18 fatty acids and had smallest concentrations of alkanols (C26, C28 and C30) and alkanes (C29, C31), but a greater abundance of more complex polar compounds than the more repellent soils. We therefore speculate that the above compounds play an important role in determining the water repellency of the soils tested. The results suggest that one-stage and sequential ASE extractions with iso-propanol:ammonia and subsequent fractionation of extracts are a useful approach in providing a comprehensive assessment of the potential compounds involved in causing soil water repellency.

  2. Establishing turfgrass on water repellent soil with ethylene oxide-propylene oxide block copolymer surfactant seed coatings

    Science.gov (United States)

    Turfgrass managers can experience poor seeding success when trying to establish golf course greens and sports fields in water repellent soils. Nonionic soil surfactant formulations are commonly used to treat water repellent soils and subsequently increase water reserves for seed germination and plan...

  3. Soil respiration (CO2 efflux) response to spatio-temporal variability of soil water repellency

    Science.gov (United States)

    Urbanek, Emilia; Doerr, Stefan

    2017-04-01

    Soil water repellency (SWR) is a common feature of many soils which restricts water infiltration and movement within the soil. SWR is expected to become more spread according to current climatic prediction, but its effect on soil carbon dynamics and specifically on soil CO2 fluxes is still not clear. Based on previous laboratory experiments it has been suggested that water repellency reduces soil respiration, but the responses of soil CO2 efflux to naturally varying hydrological conditions created by SWR are not yet known. This is the first field-based study testing the hypothesis that water repellency indeed reduces soil CO2 efflux. In situ field measurements of soil CO2 fluxes, temperature, water contents and water repellency were carried out over three consecutive years at a grassland and pine forest site under the humid temperate climate of the UK. SWR was observed for the majority of the warmer period, but exhibited high spatial variability. Soils showed similar levels of extreme water repellency only on a few occasions following long dry spells and this indeed resulted in reduction in CO2 efflux. Spatially patchy SWR with variable soil moisture content induced the highest respiration rates, significantly higher than when SWR was absent. This rather unexpected behaviour can be explained by SWR-induced preferential flow which created flow paths with water and nutrients supply to the microorganisms, while water repellent zones provided air-filled pathways to facilitate soil-atmosphere gas exchanges. This study demonstrates that SWR can have contrasting effects on CO2 fluxes and, when spatially-variable, enhance CO2 efflux.

  4. Effect of Thickness of a Water Repellent Soil Layer on Soil Evaporation Rate

    Science.gov (United States)

    Ahn, S.; Im, S.; Doerr, S.

    2012-04-01

    A water repellent soil layer overlying wettable soil is known to affect soil evaporation. This effect can be beneficial for water conservation in areas where water is scarce. Little is known, however, about the effect of the thickness of the water repellent layer. The thickness of this layer can vary widely, and particularly after wildfire, with the soil temperature reached and the duration of the fire. This study was conducted to investigate the effect of thickness of a top layer of water repellent soil on soil evaporation rate. In order to isolate the thickness from other possible factors, fully wettable standard sand (300~600 microns) was used. Extreme water repellency (WDPT > 24 hours) was generated by 'baking' the sand mixed with oven-dried pine needles (fresh needles of Pinus densiflora) at the mass ratio of 1:13 (needle:soil) at 185°C for 18 hours. The thicknesses of water repellent layers were 1, 2, 3 and 7 cm on top of wettable soil. Fully wettable soil columns were prepared as a control. Soil columns (8 cm diameter, 10 cm height) were covered with nylon mesh. Tap water (50 ml, saturating 3 cm of a soil column) was injected with hypoderm syringes from three different directions at the bottom level. The injection holes were sealed with hot-melt adhesive immediately after injection. The rate of soil evaporation through the soil surface was measured by weight change under isothermal condition of 40°C. Five replications were made for each. A trend of negative correlation between the thickness of water repellent top layer and soil evaporation rate is discussed in this contribution.

  5. Soil water repellency affects production and transport of CO2 and CH4 in soil

    Science.gov (United States)

    Urbanek, Emilia; Qassem, Khalid

    2016-04-01

    Soil moisture is known to be vital in controlling both the production and transport of C gases in soil. Water availability regulates the decomposition rates of soil organic matter by the microorganisms, while the proportion of water/air filled pores controls the transport of gases within the soil and at the soil-atmosphere interface. Many experimental studies and process models looking at soil C gas fluxes assume that soil water is uniformly distributed and soil is easily wettable. Most soils, however, exhibit some degree of soil water repellency (i.e. hydrophobicity) and do not wet spontaneously when dry or moderately moist. They have restricted infiltration and conductivity of water, which also results in extremely heterogeneous soil water distribution. This is a world-wide occurring phenomenon which is particularly common under permanent vegetation e.g. forest, grass and shrub vegetation. This study investigates the effect of soil water repellency on microbial respiration, CO2 transport within the soil and C gas fluxes between the soil and the atmosphere. The results from the field monitoring and laboratory experiments show that soil water repellency results in non-uniform water distribution in the soil which affects the CO2 and CH4 gas fluxes. The main conclusion from the study is that water repellency not only affects the water relations in the soil, but has also a great impact on greenhouse gas production and transport and therefore should be included as an important parameter during the sites monitoring and modelling of gas fluxes.

  6. Basic soil properties as a factor controlling the occurrence and intensity of water repellency in rankers of the White Carpathians

    Directory of Open Access Journals (Sweden)

    Kořenková Lucia

    2015-09-01

    Full Text Available Water repellency in soils is controlled by many different factors, basic physical and chemical properties might be considered the crucial ones. For the purpose of this study, 12 sites were selected and sampled (0–20 cm depth in the White Carpathians. Repellency tests were conducted under laboratory conditions in triplicate using water drop penetration time (WDPT test and the molarity of ethanol droplet (MED test. Results of WDPT measurements showed that three samples were marked by slight to extreme water repellency. Regarding the relationship between WDPT/MED and tested soil properties, the highest value of correlation coefficient was calculated for soil organic carbon (r = 0.706; p < 0.05, suggesting there is a positive, statistically significant correlation between repellency severity and total carbon content. A negative relationship between repellency and soil reaction/silt/silt + clay contents of studied soils was found. Samples taken from the surface horizon of arable soils showed no repellency.

  7. Impacts of grass removal on wetting and actual water repellency in a sandy soil

    Directory of Open Access Journals (Sweden)

    Oostindie Klaas

    2017-03-01

    Full Text Available Soil water content and actual water repellency were assessed for soil profiles at two sites in a bare and grasscovered plot of a sand pasture, to investigate the impact of the grass removal on both properties. The soil of the plots was sampled six times in vertical transects to a depth of 33 cm between 23 May and 7 October 2002. On each sampling date the soil water contents were measured and the persistence of actual water repellency was determined of field-moist samples. Considerably higher soil water contents were found in the bare versus the grass-covered plots. These alterations are caused by differences between evaporation and transpiration rates across the plots. Noteworthy are the often excessive differences in soil water content at depths of 10 to 30 cm between the bare and grass-covered plots. These differences are a consequence of water uptake by the roots in the grass-covered plots. The water storage in the upper 19 cm of the bare soil was at least two times greater than in the grass-covered soil during dry periods. A major part of the soil profile in the grass-covered plots exhibited extreme water repellency to a depth of 19 cm on all sampling dates, while the soil profile of the bare plots was completely wettable on eight of the twelve sampling dates. Significant differences in persistence of actual water repellency were found between the grass-covered and bare plots.

  8. Monitoring fire impacts in soil water repellency and structure stability during 6 years

    Directory of Open Access Journals (Sweden)

    A.J. Gordillo-Rivero

    2013-05-01

    Full Text Available Wildfires induce a series of soil changes affecting their physical and chemical properties and the hydrological and erosive response. Two of the properties that are commonly affected by burning are soil water repellency and structural stability. This paper carries out the study and monitoring of water repellency and soil structural stability during a period of 6 years after fire in calcareous soils of southern Spain in different aggregate size fractions (<2, 1-2, 0.5-1 and 0.25-0.5 mm. During this time, it was observed that both properties showed different tendencies in different aggregate size fractions. It was observed that water repellency increased after fire especially in the finer fractions (0.25-0.5 mm. Structural stability increased significantly after the fire and was progressively reduced during the experimental period.

  9. Composition and structure of agents responsible for development of water repellency in soils following oil contamination.

    Science.gov (United States)

    Litvina, Marina; Todoruk, Tiona R; Langford, Cooper H

    2003-07-01

    Soil from the Ellerslie site of experimental oil contamination in Alberta developed water repellency some years after initial remediation. The water-repellent soils were compared to clean soils and contaminated but wettable soils by solid-state nuclear magnetic resonance (NMR). The effects of extraction with CH2Cl2 (for petroleum hydrocarbons), NaOH (for natural organic matter), and 2-propanol/ammonia (IPA/NH3) on wettability were evaluated by the molarity of the ethanol droplet (MED) test. Soil extracts and whole soils, after extraction, were examined using NMR and Fourier transform infrared spectroscopy (FTIR). On the basis of the structure--MED correlations, a model of a thin-layer natural organic matter--petroleum products complex formed under strong drying conditions is proposed to account for the development of water repellency. Studies of two similar soils from accidental oil spills are supportive.

  10. Super water repellent surface 'strictly' mimicking the surface structure of lotus leaf

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Tae Gon; Kim, Ho Young [Seoul National University, Seoul (Korea, Republic of); Yi, Jin Woo; Lee, Kwang Ryeol; Moon, Myoung Woon [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2009-07-01

    To achieve the hierarchy of roughness as observed in lotus leaves, most artificial water-repellent surfaces have nano-asperities on top of micropillars. However, observation of real lotus leaves through SEM reveals that nonoscale roughness covers the entire surface including the base as well as bumps. Thus we fabricate surfaces having the same hierarchical roughness structure as the lotus leaf by forming nanopillars on both micropillars and base. We compare the measures of water-repellency (static contact angle, contact angle hysteresis, and transition pressure between the Cassie and Wenzel states) of the lotus-like surface with those of surfaces having single micro- and nano- roughness. The results show that nanoscale roughness covering entire surface area leads to superior water-repellency to other surface roughness structures. We also give a theoretical consideration of this observation.

  11. Soil Surface Structure: A key factor for the degree of soil water repellency

    Science.gov (United States)

    Ahn, S.; Doerr, S. H.; Douglas, P.; Bryant, R.; Hamlett, C.; McHale, G.; Newton, M.; Shirtcliffe, N.

    2012-04-01

    Despite of considerable efforts, the degree of water repellency has not always been fully explained by chemical property of soil (termed hydrophobicity). That might be because the structure of a soil surface was not considered properly, which is another main factor determining the severity of soil water repellency. Surface structure has only recently been considered in soil science, whilst it has been paid attention for several decades in materials science due to its relevance to industrial applications. In this contribution, comparison of critical contact angles measured on different surface structures (made with glass beads, glass shards and beach sands) is presented and the effect of surface structure on manifestation of soil water repellency is discussed in terms of several different variables such as the individual particles shape, and areal and structural factors of the actual surface.

  12. Bio-inspired water repellent surfaces produced by ultrafast laser structuring of silicon

    Energy Technology Data Exchange (ETDEWEB)

    Barberoglou, M.; Zorba, V. [Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas (IESL-FORTH), P.O. Box 1527, Heraklion 711 10 (Greece); Physics Department, University of Crete, Heraklion 714 09 (Greece); Stratakis, E. [Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas (IESL-FORTH), P.O. Box 1527, Heraklion 711 10 (Greece); Materials Science and Technology Department, University of Crete, Heraklion 710 03 (Greece); Technological Educational Institute of Crete, Heraklion 71004 (Greece)], E-mail: stratak@iesl.forth.gr; Spanakis, E. [Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas (IESL-FORTH), P.O. Box 1527, Heraklion 711 10 (Greece); Materials Science and Technology Department, University of Crete, Heraklion 710 03 (Greece); Technological Educational Institute of Crete, Heraklion 71004 (Greece); Tzanetakis, P. [Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas (IESL-FORTH), P.O. Box 1527, Heraklion 711 10 (Greece); Physics Department, University of Crete, Heraklion 714 09 (Greece); Anastasiadis, S.H. [Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas (IESL-FORTH), P.O. Box 1527, Heraklion 711 10 (Greece); Department of Chemical Engineering, Aristotle University of Thessaloniki, 541 24 Thessaloniki (Greece); Fotakis, C. [Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas (IESL-FORTH), P.O. Box 1527, Heraklion 711 10 (Greece); Physics Department, University of Crete, Heraklion 714 09 (Greece)

    2009-03-01

    We report here an efficient method for preparing stable superhydrophobic and highly water repellent surfaces by irradiating silicon wafers with femtosecond laser pulses and subsequently coating them with chloroalkylsilane monolayers. By varying the laser pulse fluence on the surface one can successfully control its wetting properties via a systematic and reproducible variation of roughness at micro- and nano-scale, which mimics the topology of natural superhydrophobic surfaces. The self-cleaning and water repellent properties of these artificial surfaces are investigated. It is found that the processed surfaces are among the most water repellent surfaces ever reported. These results may pave the way for the implementation of laser surface microstructuring techniques for the fabrication of superhydrophobic and self-cleaning surfaces in different kinds of materials as well.

  13. Initial water repellency affected organic matter depletion rates of manure amended soils in Sri Lanka

    Directory of Open Access Journals (Sweden)

    Leelamanie D.A.L.

    2014-12-01

    Full Text Available The wetting rate of soil is a measure of water repellency, which is a property of soils that prevents water from wetting or penetrating into dry soil. The objective of the present research was to examine the initial water repellency of organic manure amended soil, and its relation to the soil organic matter (SOM depletion rates in the laboratory. Soil collected from the Wilpita natural forest, Sri Lanka, was mixed with organic manure to prepare soil samples with 0, 5, 10, 25, and 50% organic manure contents. Locally available cattle manure (CM, goat manure (GM, and Casuarina equisetifolia leaves (CE were used as the organic manure amendments. Organic matter content of soils was measured in 1, 3, 7, 14, and 30 days intervals under the laboratory conditions with 74±5% relative humidity at 28±1°C. Initial water repellency of soil samples was measured as the wetting rates using the water drop penetration time (WDPT test. Initial water repellency increased with increasing SOM content showing higher increasing rate for hydrophobic CE amended samples compared with those amended with CM and GM. The relation between water repellency and SOM content was considered to be governed by the original hydrophobicities of added manures. The SOM contents of all the soil samples decreased with the time to reach almost steady level at about 30 d. The initial SOM depletion rates were negatively related with the initial water repellency. However, all the CE amended samples initially showed prominent low SOM depletion rates, which were not significantly differed with the amended manure content or the difference in initial water repellency. It is explicable that the original hydrophobicity of the manure as well has a potentially important effect on initiation of SOM decomposition. In contrast, the overall SOM depletion rate can be attributed to the initial water repellency of the manure amended sample, however, not to the original hydrophobicity of the amended manure

  14. Water repellency, plants, agriculture abandonment and fire in citrus plantations. The Canyoles river watershed study site

    Science.gov (United States)

    Cerdà, Artemi; Jordán, Antonio; Doerr, Stefan Helmut

    2017-04-01

    Soil water repellency (SWR) is a key soil property that determine the soil and water losses, soil fertility and plant development. Although until the 90's the soil water repellency was seeing as an uncommon soil characteristic, now is considered a key soil property to understand the soil hydrology (Alanís et al., 2016; Hewelke et al., 2016; Keesstra et al., 2016; Jiménez-Morillo et al., 2016). The inspiring research of Leonard DeBano and Stefan H Doerr changed the fate of the science (DeBano, 2000; Doerr et al. 2000). Soil water repellency was associated to forest fire affected land due to the pioneer contribution of professor DeBano in the 70's and Professor Doerr in the 90's. The research during the last two decades demonstrate that fire affects the reallocation of the hydrophobic substances and can reduce or increase the severity of the soil water repellence at different soil depths and horizons. The SWR is usually measured by sampling to show the influence of key soil properties (texture, structure, plant cover, litter, season…) on the degree of soil water repellency. The sampling is applied usually with a few drops when the Water Drop Penetration Time method is applied, and this inform of the time of penetration, but few researches focussed in the spatial distribution of the water repellency, which is a key factor of the runoff generation, the water infiltration and the water redistribution such as demonstrate the wetting fronts. Our approach research the spatial distribution of the water repellency by means of an intense sampling of soil surface water repellency. One thousand drops were distributed in a square meter (100 lines separated 1 cm and 100 drops per each line of 100 cm, with a total od 1000 drops in 1m2) on 10 sampling points on 4 land managements: ploughing and herbicide agriculture fields treatment), abandoned 10 years, and burnt. The research was carried out in citrus plantations of the Canyoles river watershed. The results show that the

  15. Laser scanning confocal microscopy characterization of water repellent distribution in a sandstone pore network.

    Science.gov (United States)

    Zoghlami, Karima; Gómez-Gras, David; Corbella, Mercè; Darragi, Fadila

    2008-11-01

    In the present work, we propose the use of the Laser Scanning Confocal Microscopy (LSCM) to determine the effect of water repellents on rock's pore-network configuration and interconnection. The rocks studied are sandstones of Miocene age, a building material that is commonly found in the architectural heritage of Tunisia. The porosity quantitative data of treated and untreated samples, obtained by mercury porosimetry tests, were compared. The results show a slight decrease in total porosity with the water repellent treatment, which reduced both microporosity and macroporosity. This reduction produced a modification in pore size distribution and a shift of the pore access size mode interval toward smaller pore diameters (from the 30-40 microm to the 20-30 microm intervals). The water repellent was observed in SEM images as a continuous film coating grain surfaces; moreover, it was easily visualized in LSCM, by staining the water repellent with Epodye fluorochrome, and the coating thickness was straightforwardly measured (1.5-2 microm). In fact, the combination of mercury intrusion porosimetry data and LSCM observations suggests that the porosity reduction and the shift of the pore diameter mode were mainly due to the general reduction of pore diameters, but also to the plugging of the smallest pores (less than 3-4 microm in diameter) by the water repellent film. Finally, the LSCM technique enabled the reconstruction of 3D views of the water repellent coating film in the pore network, indicating that its distribution was uniform and continuous over the 100 microm thick sample. The LSCM imaging facilitates the integration and interpretation of mercury porosimetry and SEM data.

  16. A simple apparatus for the determining contact angle of water repellent fabrics

    Directory of Open Access Journals (Sweden)

    B. M. Banerji

    1955-04-01

    Full Text Available A simple apparatus for the determination of fabric-water contact angle of water repellent fabrics is described. It is based on the tilting plate principle and the additional advantage that the end point can be sharply ascertained by optical means.

  17. Using hyperspectral imagery to predict post-wildfire soil water repellency

    Science.gov (United States)

    Sarah A. Lewis; Peter R. Robichaud; Bruce E. Frazier; Joan Q. Wu; Denise Y. M. Laes

    2008-01-01

    A principal task of evaluating large wildfires is to assess fire's effect on the soil in order to predict the potential watershed response. Two types of soil water repellency tests, the water drop penetration time (WDPT) test and the mini-disk infiltrometer (MDI) test, were performed after the Hayman Fire in Colorado, in the summer of 2002 to assess the...

  18. Assessing soil water repellency of a sandy field with visible near infrared spectroscopy

    DEFF Research Database (Denmark)

    Knadel, Maria; Masis Melendez, Federico; de Jonge, Lis Wollesen

    2016-01-01

    Soil water repellency (WR) is a widespread phenomenon caused by aggregated organic matter (OM) and layers of hydrophobic organic substances coating the surface of soil particles. These substances have a very low surface free energy, reducing a soil’s water attraction. There is focus on WR due...

  19. Biomimetic "water strider leg" with highly refined nanogroove structure and remarkable water-repellent performance.

    Science.gov (United States)

    Bai, Fan; Wu, Juntao; Gong, Guangming; Guo, Lin

    2014-09-24

    The water strider is a wonderful case that we can learn from nature to understand how to stride on the water surface. Inspired by the unique hierarchical micro/nanostructure of the water strider leg, in this article, we designed and fabricated an artificial strider leg with refined nanogroove structure by using an electrospinning and sacrificial template method. A model water strider that was equipped with four artificial legs showed remarkable water-repellent performance; namely, it could carry a load that was about 7 times heavier than its own weight. Characterization demonstrated that, even though the artificial leg did not possess a superhydrophobic surface, the numerous nanogrooves could still provide a huge supporting force for the man-made model strider. This work enlightens the development of artificial water-walking devices for exploring and monitoring the surface of water. Because of the advances of the applied materials, the devices may fulfill tasks in a harsh aquatic environment.

  20. Thermal properties and water repellency of cotton fabric prepared through sol-gel method

    Directory of Open Access Journals (Sweden)

    Gu Jia-Li

    2016-01-01

    Full Text Available Cotton fabrics were treated by one-step sol-gel method. The pure silica hydrosol and phosphorus-doped hydrosol were prepared with the addition of a hydrophobic hexadecyltrimethoxysilane to decrease the surface energy of cotton fabric. The thermal properties and water repellency of treated cotton fabric were characterized by thermo-gravimetric analysis, micro combustion, limiting oxygen index, and contact angle measurement. The results showed that cotton fabric treated by phosphorus-doped silica hydrosol had excellent flame retardance, and the water repellence was apparently improved with the addition of hexadecyltrimethoxysilane.

  1. Effects of soil water repellency on microbial community structure and functions in Mediterranean pine forests

    Science.gov (United States)

    Lozano, Elena; Grayston, Sue J.; Mataix-Solera, Jorge; Arcenegui, Victoria; Jimenez-Pinilla, Patricia; Mataix-Beneyto, Jorge

    2015-04-01

    Soil water repellency (SWR) is a property commonly observed in forest areas showing wettable and water repellent patches with high spatial variability. SWR can greatly influence the hydrology and the ecology of forest soils. The capacity of soil microorganisms to degrade different organic compounds depends upon species composition, so this may affect changes in SWR on the microsite scale (such as the presence of soil water repellent patches; Mülleret al., 2010). In the Mediterranean forest context, SWR has been found to be related to microbial community composition. The accumulation of different hydrophobic compounds might be causing the shifts in microbial community structure (Lozano et al., 2014). In this study we investigated the effects of SWR persistence on soil microbial community structure and enzyme activity under Pinus halepensis forest in three different sites: Petrer, Gorga and Jávea (Alicante, E Spain). Soil samples were classified into three different water repellency classes (wettable, slight or strongly water repellent samples) depending on the SWR persistence. The soil microbial community was determined through phospholipid fatty acids (PLFAs). Enzyme activities chosen for this study were cellulase, β-glucosidase and N-acetyl-β-glucosaminide (NAG). The relationships between microbiological community structure and some soil properties such as pH, Glomalin Related Soil Protein, soil organic matter content and soil respiration were also studied. Redundancy analyses and decomposition of the variances were performed to clarify how microbial community composition and enzyme activities are affected by SWR and soil properties. The effect of SWR on microbial community composition differed between locations. This effect was clearer in the Petrer site. Enzyme activity varied considerably depending on SWR persistence. The highest activities were found in slightly SWR samples and the lowest mostly in the strongly water repellent ones. These preliminary

  2. Effects of kaolinite and drying temperature on the persistence of soil water repellency induced by humic acids

    NARCIS (Netherlands)

    Lichner, L.; Babejová, N.; Dekker, L.W.

    2002-01-01

    The effects of kaolinite additions and drying temperature on the persistence of soil water repellency, induced by humic acids from peat, were assessed in this study. It was found that additions of 5 and 10% kaolinite (referred to as the most effective material in combating the water repellency) did

  3. Post-Fire soil water repellency, hydrologic response, and sediment yield compared between grass-converted and chaparral watersheds

    Science.gov (United States)

    Ken R. Hubbert; Pete M. Wohlgemuth; Jan L. Beyers; Marcia G. Narog; Ross Gerrard

    2012-01-01

    In 2002, the Williams Fire burned >90 % of the San Dimas Experimental Forest, providing an opportunity to investigate differences in soil water repellency, peak discharge, and sediment yield between grass-converted and chaparral watersheds. Post-fire water repellency and moisture content were measured in the winter and summer for four years. Peak discharge was...

  4. Hydrologic impacts of soil water repellency on fine-to-coarse-textured soils of wooded shrublands and shrub-steppe communities

    Science.gov (United States)

    The potential for soil water repellency to dominate rangeland hydrologic responses has significant implications for ongoing plant community transitions and disturbance regimes. Naturally occurring soil water repellency has been well documented on semiarid rangelands and chaparral plant communities....

  5. The influence of clay type on reduction of water repellency by applied clays: a review of some West Australian work

    Science.gov (United States)

    McKissock, I.; Walker, E. L.; Gilkes, R. J.; Carter, D. J.

    2000-05-01

    In Western Australia water repellency mostly occurs in soils with sandy texture; the severity of water repellency is influenced by very small changes in clay content. Additions of 1-2% clay can prevent water repellency and for some time clay amendments have been used by farmers to overcome water repellency. The aim of this study was to assess the effectiveness of clays in ameliorating water repellency. Clays were assessed for effectiveness in reducing water repellency by mixing with water repellent sands and measuring water drop penetration time (WDPT) on the resultant mixtures. WDPT was measured on the initial mixtures, a wetting and drying cycle was imposed and WDPT measured again. Two sets of clays were assessed: four simple clays containing kaolinite (2) or smectite (2) group minerals and a group of clayey subsoil materials which had been collected by farmers. For the simple clays, clay mineral type was the most significant factor in determining response. Kaolin was much more effective than smectite. Imposition of a wetting and drying cycle greatly reduced water repellency. The dominant exchangeable cation of the clays (sodium or calcium) had little effect on the ability of the clays to reduce water repellency. The factor that was most predictive of the effectiveness of clayey subsoils materials in reducing water repellency was texture: clay content ( r2=0.18) or clay+silt content ( r2=0.23). These properties were more predictive of water repellency values after the wetting and drying cycle treatment ( r2=0.36, r2=0.44). The proportion of the clay fraction that consisted of kaolinite was next most predictive in determining effectiveness which is again indicative of kaolin group minerals being more effective than smectite group minerals. The exchangeable sodium percentage and clay dispersibility had no systematic effect on the ability of these clays to reduce water repellency. These results provide a basis for developing a practical field procedure to enable

  6. Study on water-repellent and oil-repellent finishing process of fabric%织物拒水拒油整理工艺探讨

    Institute of Scientific and Technical Information of China (English)

    黄小华; 石小奕; 赵堃

    2012-01-01

    Water repellent agents commonly used are silicones and fluorochemieals, but fluoroehemicals a gents impart both water repellency and oil repcllency to fabrics for meeting people's demand on muhi functional textiles. In this paper, TG-581 water and oil repellent agent,as a fluorochemical,was used to finish four kinds of fabrics. This paper discusses the effect of various factors, like the concentration of water and oil repellent agent, pH value of solution,dry temperature,cure temperature,cure time on the water and oil repellent performance of fabrics, so as to provide reference for determining the optimum water and oil repellent finishing process conditions.%目前常用的拒水剂主要是有机硅化合物和有机氟化合物,但有机氟化合物可同时赋予整理织物拒水、拒油性能,可满足人们对多功能纺织品的需求.本文使用含氟化合物TG-581拒水拒油整理剂对4种织物进行整理.文章探讨了整理剂质量浓度、整理液pH值、烘干温度、焙烘温度、焙烘时间等工艺因素对拒水拒油性能的影响,从而为确定拒水拒油整理最佳工艺条件提供参考.

  7. Two-Region Model for Soil Water Repellency as a Function of Matric Potential and Water Content

    DEFF Research Database (Denmark)

    Karunarathna, Anurudda Kumara; Møldrup, Per; Kawamoto, Ken

    2010-01-01

    Soil water repellency (WR) occurs worldwide and affects hydrologic processes such as infiltration, preferential flow, and surface erosion. The degree of WR varies with soil organic C (SOC) and water contents. In this study, we measured WR (by ethanol molarity) as a function of moisture conditions...... for two soil profiles (17 layers, of which 13 exhibited WR), representing different vegetation and SOC between 0.6 and 14%. Generally, WR was found at SOC ≥2%. Based on measured data, a two-region water repellency (TRWR) model was developed. The model assumes two linear regions in a WR vs. pF (=log...... by the so-called Dexter index) is useful for predicting if soils are likely to exhibit WR. Expression of soil water repellency depends on soil water content; however, only a limited amount of predictive description is available to date. In this study, based on experimental data, a simple two-region model...

  8. A Simple Beta-Function Model for Soil-Water Repellency as a Function of Water and Organic Carbon Contents

    DEFF Research Database (Denmark)

    Karunarathna, Anurudda Kumara; Kawamoto, Ken; Møldrup, Per

    2010-01-01

    Soil-water content (θ) and soil organic carbon (SOC) are key factors controlling the occurrence and magnitude of soil-water repellency (WR). Although expressions have recently been proposed to describe the nonlinear variation of WR with θ, the inclusion of easily measurable parameters in predictive...... conditions for 19 soils were used to test the model. The beta function successfully reproduced all the measured soil-water repellency characteristic, α(θ), curves. Significant correlations were found between model parameters and SOC content (1%-14%). The model was independently tested against data...... for further three soils and performed accurately for all three. Consequently, we suggest that the α(θ) model represents a useful strategy to predict the entire soil-water repellency characteristic curve, and thus potential risks for enhanced runoff and preferential (fingered) soil-water flow at given initial...

  9. Effects of clay amendment on adsorption and desorption of copper in water repellent soils

    NARCIS (Netherlands)

    Xiong, X.; Stagnitti, F.; Allinson, G.; Turoczy, N.; Li, P.; LeBlanc, M.; Cann, M.A.; Doerr, S.H.; Steenhuis, M.M.; Parlange, J.Y.; Rooij, de G.; Ritsema, C.J.; Dekker, L.W.

    2005-01-01

    Copper is an important micronutrient and trace amounts are essential for crop growth. However, high concentrations of copper will produce toxic effects. Australia is increasingly developing production of crops in water repellent soils. Clay amendment, a common amelioration techniques used in Austral

  10. Effects of surfactant treatments on the wettability of a water repellent grass-covered dune sand

    NARCIS (Netherlands)

    Dekker, L.W.; Oostindie, K.; Kostka, S.J.; Ritsema, C.J.

    2005-01-01

    Copper is an important micronutrient and trace amounts are essential for crop growth. However, high concentrations of copper will produce toxic effects. Australia is increasingly developing production of crops in water repellent soils. Clay amendment, a common amelioration techniques used in Austral

  11. Effect of maize canopy and water repellency on moisture patterns in a Dutch black plaggen soil

    NARCIS (Netherlands)

    Dekker, L.W.; Ritsema, C.J.

    1997-01-01

    Man-made raised sandy soils in the Netherlands are classified as `brown' or `black' plaggen soils. When dry, the brown soils are wettable, but the black soils are water repellent. For one growing season, transects were sampled in a maize cropped black plaggen soil at the Heino experimental farm. Due

  12. Effect of Plant-derived Hydrophobic Compounds on Soil Water. Repellency in Dutch Sandy Soils

    NARCIS (Netherlands)

    Mao, J.|info:eu-repo/dai/nl/363508287; Dekker, S.C.|info:eu-repo/dai/nl/203449827; Nierop, K.G.J.|info:eu-repo/dai/nl/182329895

    2013-01-01

    Soil water repellency or hydrophobicity is a common and important soil property, which may diminish plant growth and promotes soil erosion leading to environmentally undesired situations. Hydrophobic organic compounds in the soil are derived from vegetation (leaves, roots, mosses) or microorganisms

  13. Improving rangeland seeding success in post-fire water repellent soil using surfactant seed coating technology

    Science.gov (United States)

    Severe disturbance from catastrophic wildfires often requires that native plant materials be reintroduced through reseeding, but the success rate of these restoration efforts in arid environments is notoriously low. Post-fire soil water repellency can limit reseeding success by decreasing soil moist...

  14. Soil water repellency and infiltration in coarse-textured soils of burned and unburned sagebrush ecosystems

    Science.gov (United States)

    Millions of dollars are spent each year in the United States to mitigate the effects of wildfires and reduce the risk of flash floods and debris flows. Research from forested, chaparral, and rangeland communities indicate severe wildfires can cause significant increases in soil water repellency res...

  15. Water repellency of Casuarina (Casuarina equisetifolia Forest.) windbreaks in central Taiwan

    Science.gov (United States)

    Chao-Yuan Lin

    2000-01-01

    Water repellent layer (WRL) in the Casuarina plantation near Taichung harbor in Central Taiwan is mainly due to the development of filamentous fungi. Not only are hyphae of the isolated fungi, the metabolites of fungi strongly hydrophobic, TCHC-5 and TCHC-20 are also significantly hydrophobic. Humic substances decrease the phosphorus fixation and contribute to the...

  16. Comparison of postfire soil water repellency amelioration strategies on bluebunch wheatgrass and cheatgrass survival

    Science.gov (United States)

    Soil water repellency may significantly limit site recovery following wildfire. This study was designed to compare survival and growth of the native plant species bluebunch wheatgrass (Pseudoroegneria spicata (Pursh) A. Löve) to the invasive annual weed cheatgrass (Bromus tectorum L.), and to compar...

  17. Soil water repellency within a burned pinon-juniper woodland: spatial distribution, severity, and ecohydrologic implications

    Science.gov (United States)

    Post-fire recovery of juniper-dominated ecosystems is dependent on the extent that ecological processes have been altered. Soil water repellency is a common condition in these ecosystems that may limit site recovery. In this study we examined the extent, severity, and ecohydrologic implications of p...

  18. Effect of Plant-derived Hydrophobic Compounds on Soil Water. Repellency in Dutch Sandy Soils

    NARCIS (Netherlands)

    Mao, J.; Dekker, S.C.; Nierop, K.G.J.

    2013-01-01

    Soil water repellency or hydrophobicity is a common and important soil property, which may diminish plant growth and promotes soil erosion leading to environmentally undesired situations. Hydrophobic organic compounds in the soil are derived from vegetation (leaves, roots, mosses) or microorganisms

  19. Water repellency under coniferous and deciduous forest - Experimental assessment and impact on overland flow

    NARCIS (Netherlands)

    Butzen, Verena; Seeger, Manuel; Marruedo, Amaia; Jonge, de Lianne; Wengel, René; Ries, Johannes B.; Casper, Markus C.

    2015-01-01

    Current climate change makes it necessary to gain a deeper understanding of the runoff generation processes in Central European forests. A changing climate might affect soil water repellency (SWR) which can be seen as an import trigger for overland flow generation in forested areas. In this study

  20. Soil water repellency and infiltration in coarse-textured soils of burned and unburned sagebrush ecosystems

    Science.gov (United States)

    F. B. Pierson; P. R. Robichaud; C. A. Moffet; K. E. Spaeth; C. J. Williams; S. P. Hardegree; P. E. Clark

    2008-01-01

    Millions of dollars are spent each year in the United States to mitigate the effects of wildfires and reduce the risk of flash floods and debris flows. Research from forested, chaparral, and rangeland communities indicate that severe wildfires can cause significant increases in soil water repellency resulting in increased runoff and erosion. Few data are available to...

  1. DIMENSIONAL STABILITY AND WATER REPELLENT EFFICIENCY MEASUREMENT OF CHEMICALLY MODIFIED TROPICAL LIGHT HARDWOOD

    OpenAIRE

    Md. Saiful Islam; Sinin Hamdan; Mohamad Rusop; Md. Rezaur Rahman; Abu Saleh Ahmed; M. A. M. Mohd Idrus

    2012-01-01

    Chemical modification is an often-followed route to improve physical and mechanical properties of solid wood materials. In this study five kinds of tropical light hardwoods species, namely jelutong (Dyera costulata), terbulan (Endospermum diadenum), batai (Paraserianthes moluccana), rubberwood (Hevea brasiliensis), and pulai (Alstonia pneumatophora), were chemically modified with benzene diazonium salt to improve their dimensional stability and water repellent efficiency. The dimensional stab...

  2. Self-assembly made durable: water-repellent materials formed by cross-linking fullerene derivatives.

    Science.gov (United States)

    Wang, Jiaobing; Shen, Yanfei; Kessel, Stefanie; Fernandes, Paulo; Yoshida, Kaname; Yagai, Shiki; Kurth, Dirk G; Möhwald, Helmuth; Nakanishi, Takashi

    2009-01-01

    Fullerene flakes: A diacetylene-functionalized fullerene derivative self-organizes into flakelike microparticles (see picture). Both the diacetylene and C(60) moieties can be effectively cross-linked, which leads to supramolecular materials with remarkable resistivity to solvent, heat, and mechanical stress. Moreover, the surface of the cross-linked flakelike objects is highly durable and water-repellent.

  3. The influence of compost addition on the water repellency of brownfield soils

    Science.gov (United States)

    Whelan, Amii; Kechavarzi, Cedric; Sakrabani, Ruben; Coulon, Frederic; Simmons, Robert; Wu, Guozhong

    2010-05-01

    Compost application to brownfield sites, which can facilitate the stabilisation and remediation of contaminants whilst providing adequate conditions for plant growth, is seen as an opportunity to divert biodegradable wastes from landfill and put degraded land back into productive use. However, although compost application is thought to improve soil hydraulic functioning, there is a lack of information on the impact of large amounts of compost on soil water repellency. Water repellency in soils is attributed to the accumulation of hydrophobic organic compounds released as root exudates, fungal and microbial by-products and decomposition of organic matter. It has also been shown that brownfield soils contaminated with petroleum-derived organic contaminants can exhibit strong water repellency, preventing the rapid infiltration of water and leading potentially to surface run off and erosion of contaminated soil. However, hydrophobic organic contaminants are known to become sequestrated by partitioning into organic matter or diffusing into nano- and micropores, making them less available over time (ageing). The effect of large amounts of organic matter addition through compost application on the water repellency of soils contaminated with petroleum-derived organic contaminants requires further investigation. We characterised the influence of compost addition on water repellency in the laboratory by measuring the Water Drop Penetration Time (WDPT), sorptivity and water repellency index through infiltration experiments on soil samples amended with two composts made with contrasting feedstocks (green waste and predominantly meat waste). The treatments consisted of a sandy loam, a clay loam and a sandy loam contaminated with diesel fuel and aged for 3 years, which were amended with the two composts at a rate equivalent to 750t/ha. In addition core samples collected from a brownfield site, amended with compost at three different rates (250, 500 and 750t/ha) in 2007, were

  4. 土壤疏水性研究进展%Research Progress in Soil Water Repellency

    Institute of Scientific and Technical Information of China (English)

    赵利坤; 秦纪洪; 孙辉

    2011-01-01

    土壤疏水性是指水分不能或很难湿润土壤颗粒表面的物理现象.土壤疏水性研究不仅有助于合理评价疏水性对生态环境的形响,而且能为当前水土流失问题的解决提供新思路.本文对国内外土壤硫水性研究现状进行总结.着重阐述了土壤疏水性及产生机理、影响因素、测定方法及水文效应,并结合存在问题展望未来的研究,以期为我国开展相关研究提供参考.%Soil water repellency is the hydrophobic property of soil which indicates the physical phenomenon that the surface of soil particles can not or hard to be moistened by soil water. Study on soil water repellency is not only helpful to assessing the impact of hydrophobic property of soils on ecological environment but also heneficial to providing soil erosion control with new approaches. The paper summarized the latest status on the researches in soil water repellency at home and abroad, mainly introduced the soil water repellency, mechanisms, determining methods and hydrological effect,and direction for the soil water repellency were advanced based on the existing problem. Then the strategies and suggestions were put forward in the end in order to research in China.

  5. Amyloid proteins are highly abundant in water-repellent but not wettable soils: microbial differentiation matters to soils

    Science.gov (United States)

    van Keulen, Geertje; Quinn, Gerry; Sinclair, Kat; Dudley, Ed; Swain, Martin; Doerr, Stefan; Matthews, Peter; Francis, Lewis; Gazze, Andrea; Hallin, Ingrid

    2017-04-01

    Soil water repellency is a common phenomenon affecting the hydrological responses of many soil and land use types in different climates. This in turn leads to decreased water infiltration, reduced vegetation cover, fertiliser run off and soil erosion. The fundamental (biological) causes of (bulk) soil repellency and its dynamic behaviour remain poorly understood. We have applied soil metaproteomics, the systemic extraction and identification of proteins from a soil, to understand the biological (adaptive) processes and potential for bio-modification of mineral surfaces, which occur at the molecular level in soils switching between wettable and repellent states. Extreme, moderate and sub-critical water-repellent UK silt-loam soils under permanent grass vegetation, including Park Grass at Rothamsted Research, were sampled below the root zone depth under wettable and repellent conditions. Soils were subjected to our new extraction methods for determining the specific ultrahydrophobic and total metaproteomes. Using our ultrahydrophobic extraction protocol, we have identified more than 200, mostly novel amyloid, proteins, which could be extracted from water-repellent soils, but were absent in the comparable wettable soils. One of the novel amyloid proteins was highly abundant in all soils, which has the potential as a soil biomarker for precision land management, especially in irrigation. Comparative profiling of the total metaproteomes of wettable and repellent soils has revealed similarities and dissimilarities in microbial diversity and their activities, which have created a deeper understanding of soil system processes common and adaptive to soil moisture and to the severity of repellence.

  6. Vegetation type and the presence of ash as factors in the evolution of soil water repellency after a forest fire

    Directory of Open Access Journals (Sweden)

    P. Jiménez-Pinilla

    2013-05-01

    Full Text Available After wildfires, burning may induce the occurrence of soil water repellency. Soil water repellency may vary in space and time in function of vegetation, the presence of ash and soil moisture. This study analyzes the evolution of fire-induced soil water repellency in function of these factors, and proposes measures to promote the restoration of fire-affected soils. Burnt and unburnt (control soil plots under pine and shrub from a recently burned area (Gorga, Alicante, SE Spain were established. Three treatments were applied: in some of the plots, the original ash layer was kept on the ground; in a second group, the ash layer was removed for simulating the effects of erosion; finally, in a third group, percolating irrigation was conducted to simulate a possible good input of water into the soil profile after burning, that could occur if the first rains were with high quantity but low intensity. During the dry season, soil moisture content was significantly lower in burned plots due to fire-induced water repellency and reduced vegetation cover. During the wet season, soil moisture decreased in the control unburnt plots due to direct evaporation of water intercepted by vegetation and consumption by roots. Fire increased soil water repellency only in plots under pine. Water repellency decreased during the wet season, disappearing in January and reappearing after declining rainfalls. This baseline recovery of soil water repellency was lower where ash removal was simulated. In unburned plots, seasonal fluctuations were less important. In general, ash removal promotes a rapid reduction of water repellency, since it can induce washing of hydrophobic compounds. Irrigation performed immediately after the fire also contributed to decreased water repellency.

  7. Application of minidisk infiltrometer to estimate water repellency in Mediterranean pine forest soils

    Directory of Open Access Journals (Sweden)

    Alagna Vincenzo

    2017-09-01

    Full Text Available Assessment of soil water repellency (SWR was conducted in the decomposed organic floor layer (duff and in the mineral soil layer of two Mediterranean pine forests, one in Italy and the other in Spain, by the widely-used water drop penetration time (WDPT test and alternative indices derived from infiltration experiments carried out by the minidisk infiltrometer (MDI. In particular, the repellency index (RI was calculated as the adjusted ratio between ethanol and water soil sorptivities whereas the water repellency cessation time (WRCT and the specifically proposed modified repellency index (RIm were derived from the hydrophobic and wettable stages of a single water infiltration experiment. Time evolution of SWR and vegetation cover influence was also investigated at the Italian site. All indices unanimously detected severe SWR conditions in the duff of the pine forests. The mineral subsoils in the two forests showed different wettability and the clay-loam subsoil at Ciavolo forest was hydrophobic even if characterized by organic matter (OM content similar to the wettable soil of an adjacent glade. It was therefore assumed that the composition rather than the total amount of OM influenced SWR. The hydraulic conductivity of the duff differed by a factor of 3.8–5.8 between the two forested sites thus influencing the vertical extent of SWR. Indeed, the mineral subsoil of Javea showed wettable or weak hydrophobic conditions probably because leaching of hydrophobic compounds was slowed or prevented at all. Estimations of SWR according to the different indices were in general agreement even if some discrepancies were observed. In particular, at low hydrophobicity levels the SWR indices gathered from the MDI tests were able to signal sub-critical SWR conditions that were not detected by the traditional WDPT index. The WRCT and modified repellency index RIm yielded SWR estimates in reasonable agreement with those obtained with the more cumbersome RI

  8. Inorganic Water Repellent Coatings for Thermal Protection Insulation on an Aerospace Vehicle

    Science.gov (United States)

    Fuerstenau, D. W.; Huang, P.; Ravikumar, R.

    1997-01-01

    The objective of this research was two-fold: first, to identify and test inorganic water-repellent materials that would be hydrophobic even after thermal cycling to temperatures above 600 C and, second, to develop a model that would link hydrophobicity of a material to the chemical properties of its constituent atoms. Four different materials were selected for detailed experimental study, namely, boron nitride, talc, molybdenite, and pyrophyllite, all of which have a layered structure made up of ionic/covalent bonds within the layers but with van der Waals bonds between the layers. The materials tested could be considered hydrophobic for a nonporous surface but none of the observed contact angles exceeded the necessary 90 degrees required for water repellency of porous materials. Boron nitride and talc were observed to retain their water-repellency when heated in air to temperatures that did not exceed 800 C, and molybdenite was found to be retain its hydrophobicity when heated to temperatures up to 600 C. For these three materials, oxidation and decomposition were identified to be the main cause for the breakdown of water repellency after repeated thermal cycling. Pyrophyllite shows the maximum promise as a potential water-repellent inorganic material, which, when treated initially at 900 C, retained its shape and remained hydrophobic for two thermal cycles where the maximum retreatment temperature is 900 C. A model was developed for predicting materials that might exhibit hydrophobicity by linking two chemical properties, namely, that the constituent ions of the compound belong to the soft acid-base category and that the fractional ionic character of the bonds be less than about 20 percent.

  9. Seasonal fluctuations in water repellency and infiltration in a sandy loam soil after a forest fire in Galicia (NW Spain

    Directory of Open Access Journals (Sweden)

    M. Rodríguez-Alleres

    2013-05-01

    Full Text Available The aim of this work was to analyze, after a wildfire of moderate severity, the temporal fluctuations in water repellency and infiltration in a sandy loam soil under a mixed plantation of pine and eucalyptus and the comparison with an adjacent area not affected by the fire. In the burnt area and in a neighboring area not affected by the fire were collected during one year (1, 4, 6, 8 and 12 months after the fire 10 soil samples along a transect of 18 m at four depths: 0-2, 2-5, 5-10 and 10-20 cm. Soil water repellency was determined using the water drop penetration time test (WDPT test and the infiltration was measured with a mini-disc infiltrometer (pressure head h0 = -2 cm.The results show a temporal pattern of soil water repellency in the burnt and unburnt areas. Significant correlations between water repellency and soil moisture were observed, with higher correlation coefficients in the unburned area and in the surface soil layer.Soil water infiltration was significantly lower than would be expected by the coarse texture of the soil in both burnt and unburnt areas. Temporal fluctuations in unburnt soil infiltration seem to be clearly related to the transient nature of the soil water repellency, with no infiltration in samples extremely repellent. In the burned area, the soil infiltration showed much more variability and temporal fluctuations appear to be less dependent on the persistence of water repellency and more dependent on environmental conditions.The unburnt area show significant and negative correlations of soil water repellency with hydraulic conductivity and sorptivity and positive of these two parameters with soil moisture. These relationships were not observed in the burnt area. The temporal fluctuations of soil water repellency have an evident impact on soil infiltration and seem to be more influent than the effects of fire.

  10. Room temperature synthesis of water repellent silica coatings by the dip coat technique

    Science.gov (United States)

    Bhagat, Sharad D.; Kim, Yong-Ha; Ahn, Young-Soo

    2006-12-01

    The present paper describes the room temperature synthesis of dip coated water repellent silica coatings onto stainless steel substrates using 1,1,1,3,3,3-hexamethyldisilazane as a surface modifying agent. The hydrophobic property of the silica coating was enhanced by increasing its surface roughness, which was achieved by a proper control over the MeOH/TMOS molar ratio ( S) during the synthesis. The contact angle of a water droplet (10 μl) increased from 72° to 145° with an increase in the S value from 9.1 to 36.4. The silica coating showed a minimum sliding angle of 15° for a water droplet of 10 μl. The water repellent silica coatings are thermally stable up to a temperature of 340 °C. The results have been discussed by taking into consideration the contact angle measurements, surface morphology and sol-gel parameters.

  11. A Comparison of Splash Erosion Behavior between Wettable and Water Repellent 'Soil' Particles

    Science.gov (United States)

    Ahn, S.; Hamlett, C. A.; Doerr, S.; Bryant, R.; Shirtcliffe, N.; McHale, G.; Newton, M.

    2011-12-01

    Wildfires remove vegetation and litter cover and expose soil surfaces to particle detachment by rain splash. This can serve as an agent of initial soil modification and erosion in the post-fire period. Splash behavior is mainly determined by the kinetic energy delivered by impacting water drops (erosivity), and the detachability (erodibility) of surface particles, affected by their size, aggregate stability and shear strength. Soil detachability may also be affected by water repellency (hydrophobicity). This soil characteristic is influenced by wildfire and may affect splash behavior by reducing capillary forces between particles. Previous work on splash behavior using cumulative drop impact reported larger ejection droplets and lower and shorter trajectories of ejections for water repellent soil compared with wettable soil (Terry and Shakesby 1993). A water film generated by delayed infiltration on water repellent soil was suggested to account for the difference. This study compares the trajectories of ejected wettable and hydrophobic model soil particles from single water drop impacts in order to isolate the effect of soil particle wettability on splash erosion behavior. Acid-washed (wettable) and hydrophobized (water repellent) glass beads used as model soil particles were held in an array within a squat cylinder of 1.5 cm diameter in the centre of a 20 cm diameter disk covered with a viscous adhesive film. A distilled water drop (20μL) was released 40 cm above the centre of the array and the resultant impact was recorded at 976 frames per second using a high speed video camera. The populations of, and distances travelled by, the particles were measured for three arrays of bead sizes within the range (180-400 μm). Three to five replications were made for each test. The trajectory of each ejected particle was traced on video frames and corrected for the actual distance and direction of travel measured from the adhesive film. The initial velocity and ejecting

  12. Soil water repellency as a vegetation-driven strategy for soil moisture sequestration in Banksia woodlands (Western Australia)

    Science.gov (United States)

    Muñoz-Rojas, Miriam; Jiménez-Morillo, Nicasio T.; González-Pérez, José A.; Zavala, Lorena M.; Stevens, Jason; Jordán, Antonio

    2016-04-01

    Water repellency is a property of some soils that inhibits or delays the rainwater infiltration. When a surface or subsurface soil horizon is water repellent, water is retained for periods of time that vary according to the severity of hydrophobicity, soil moisture and other parameters. Water repellency is caused by hydrophobic organic substances released by plant residues, roots or soil microorganisms. Certain abiotic agents, like fire, can increase the severity of soil water repellency in certain cases. Under water-repellent conditions, water can infiltrate only when the pressure of the water column is high enough or when macropores allow it. These macropores may be formed by galleries excavated by animals, dead roots or gaps between aggregate or rock fragments. Banksia plants have a dimorphic root morphology. Proteoid roots are formed by clusters of densely compacted short lateral rootlets that radiate from the parent root. These clusters spread just some centimeters below the soil surface constituting a thick dense sheet of roots and are known to secrete large amounts of organic acids and phenolics to increase the uptake of P and other minerals. In contrast, the parent root penetrates soil deeply, reaching the water table. Sandy soils below banksia woodlands from Western Australia coastal dunes show a characteristic vertical distribution of water repellency. We observed that the first soil layer (just some millimeters of depth) was formed by a wettable sand particles transported by wind, covering a wettable or subcritically water-repellent subsurface layer (0-20 cm). A second soil layer (20-40 cm) was formed by a severely water-repellent layer with aggregates bulked by dominant banksia proteoid roots. Below this layer, soil water repellency decreased with depth until soil material rendered wettable at depths between 40 and 80 cm under field conditions. It is hypothesized that banksia roots are capable of inducing soil water repellency, causing the occurrence of

  13. Pore-scale distribution of mucilage affecting water repellency in the rhizosphere

    Science.gov (United States)

    Benard, Pascal; Zarebanadkouki, Mohsen; Hedwig, Clemens; Holz, Maire; Ahmed, Mutez; Carminati, Andrea

    2017-04-01

    The hydraulic properties of the rhizosphere are altered by plants, fungi and microorganism. Plant roots release different compounds into the soil. One of these substances is mucilage, a gel which turns water repellent upon drying. We introduce a conceptual model of mucilage deposition during soil drying and its impact on the soil wettability. As the soil dries, water menisci recede and draw mucilage towards the contact region between particles where it is deposited. At high mucilage content, mucilage deposits expand into the open pore space and finally block water infiltration when a critical fraction of the pore space is blocked. To test this hypothesis, we mixed mucilage and particles of different grain size, we let them dry and measured the contact angle using the sessile drop method. Mucilage deposition was visualized by light microscopy imaging. Contact angle measurements showed a distinct threshold-like behavior with a sudden increase in apparent contact angle at high mucilage concentrations. Particle roughness induced a more uniform distribution of mucilage. The observed threshold corresponds to the concentration when mucilage deposition occupies a critical fraction of the pore space, as visualized with the microscope images. In conclusion, water repellency is critically affected by the distribution of mucilage on the pore-scale. This microscopic heterogeneity has to be taken into account in the description of macroscopic processes, like water infiltration or rewetting of water repellent soil.

  14. Seasonal changes in soil water repellency and their effect on soil CO2 fluxes

    Science.gov (United States)

    Urbanek, Emilia; Qassem, Khalid

    2016-04-01

    Soil water repellency (SWR) is a seasonally variable phenomenon controlled by moisture content and at the same time a regulator of the distribution and conductivity of water in the soil. The distribution and availability of water in soil is also an important factor for microbial activity, decomposition of soil organic matter and exchange of gases like CO2 and CH4 between the soil and the atmosphere. It has been therefore hypothesised that SWR by restricting water availability in soil can affect the production and the transport of CO2 in the soil and between the soil and the atmosphere. This study investigates the effect of seasonal changes in soil moisture and water repellency on CO2 fluxes from soil. The study was conducted for 3 year at four grassland and pine forest sites in the UK with contrasting precipitation. The results show the temporal changes in soil moisture content and SWR are affected by rainfall intensity and the length of dry periods between the storms. Soils exposed to very high annual rainfall (>1200mm) can still exhibit high levels of SWR for relatively long periods of time. The spatial variation in soil moisture resulting from SWR affects soil CO2 fluxes, but the most profound effect is visible during and immediately after the rainfall events. Keywords: soil water repellency, CO2 flux, hydrophobicity, preferential flow, gas exchange, rainfall

  15. Quantitative assessment to the structural basis of water repellency in natural and technical surfaces.

    Science.gov (United States)

    Wagner, P; Fürstner, R; Barthlott, W; Neinhuis, C

    2003-04-01

    Many plant surfaces are water-repellent because of a complex 3-dimensional microstructure of the epidermal cells (papillae) and a superimposed layer of hydrophobic wax crystals. Due to its surface tension, water does not spread on such surfaces but forms spherical droplets that lie only on the tips of the microstructures. Studying six species with heavily microstructured surfaces by a new type of confocal light microscopy, the number, height, and average distance of papillae per unit area were measured. These measurements were combined with those of an atomic force microscope which was used to measure the exposed area of the fine-structure on individual papillae. According to calculations based upon these measurements, roughening results in a reduction of the contact area of more than 95% compared with the projected area of a water droplet. By applying water/methanol solutions of decreasing surface tension to a selection of 33 water-repellent species showing different types of surface structures, the critical value at which wetting occurs was determined. The results impressively demonstrated the importance of roughening on different length scales for water-repellency, since extremely papillose surfaces, having an additional wax layer, are able to resist up to 70% methanol. Surfaces that lack papillae or similar structures on the same length scale are much more easily wetted.

  16. Water repellence assessment in humid mediterranean carbonated environments: influence of shrubland species

    Science.gov (United States)

    Oscar, Gonzalez-Pelayo; Vicente, Andreu; Luis, Rubio Jose; Carla Sofia, Ferreira; Dinis, Ferreira Antonio Jose

    2010-05-01

    The importance of natural or induced (fire) water repellence in terms of water redistribution in the soil profile, reduction in soil infiltration capacity and thus, in runoff magnification, is well established. Hydrophobicity has been identified around the world in different climatic conditions, land covers, soil and vegetation types. Regarding soil and vegetation, many studies are based on coarse acidic soils with pine forest, eucalyptus, deciduous trees, grassland, cropland, chaparral vegetation type, and lately in shrublands. However, few studies are related to shrubland in wet Mediterranean carbonated environments. This work is oriented to the study of soil water repellence in these environments by means of WDPT. The study was carried out in Podentes (Coimbra), central Portugal, on 4 ha of shrubland (mainly Quercus coccifera, Pistacia lentiscus and Arbutus unedo), developed on Umbric leptosol and Calcaric cambisol soil types (WRB). The WDPT was assessed depending on the shrubland type, slope orientation, soil depth (0-2 cm and 2-5 cm) and on different soil fractions ( Q. coccifera ≈ P. lentiscus; and depending on the orientation: NE > SW. Direct relationships were obtained between the soil organic matter content and the log WDPT on almost all the surface soil samples. The soil pH and carbonate content did not display correlation with soil water repellence. The different hydrophobic compounds generated by waxes and resins of the different shrubland types, which could be incorporated to the soil as binding agents, seem to be the explanation for the differences of the WDPT data. The patchy distribution of the vegetation rules the persistence of the natural soil water repellence, restraining water infiltration mainly by micropore flow, being then the soil hydrology controlled by the macropore flow, cracks and root system. Further research into soil organic matter quality in the finer soil aggregates could be necessary to confirm this link between the components

  17. The influence of water repellent products on the chromatic modifications of the ceramic brick

    Directory of Open Access Journals (Sweden)

    Coronado Martin, J. A.

    2011-12-01

    Full Text Available Chromatic variation, colour and luminosity, undergone by the ceramic support protected by the incorporation of a treatment with water repellent products, is analysed. A new methodology is suggested, based on RGB model where quantifiable values from each ceramic sample are obtained through digital measurement of the colour (image histograms, taking as a base the same type of ceramics with no water repellents. Chromatic variation is determined by the type of water repellent and the base material, obtaining the following results: - All the water repellent studied cause variations in the shade and luminosity of the piece. - English red brick (R is the one presenting less variation of luminosity and shade since it’s been treated with water repellents. - The water repellent of siliconates component is the one which causes less chromatic variation in two of the three bricks studied, the dark brown (T and the English red (R one.

    Se analiza la variación cromática, color y luminosidad, que sufre el soporte cerámico protegido por la incorporación de un tratamiento con productos hidrofugantes. Se propone una metodología nueva, basada en el modelo RGB donde se obtienen valores cuantificables de cada muestra cerámica mediante medición digital del color (histogramas de imagen, tomándose como base el mismo tipo de cerámica sin hidrofugar. La variación cromática está determinada por el tipo de hidrofugante y por el material de base, obteniéndose los siguientes resultados: - Todos los hidrofugantes estudiados producen variación en la tonalidad y luminosidad de la pieza. - El ladrillo rojo ingles (R es el que presenta menor variación de luminosidad y tonalidad al ser tratado con hidrofugantes. - El hidrofugante de componente siliconatos es el que menor variación cromática produce en dos de los tres ladrillos estudiados, tostado (T y rojo inglés (R.

  18. Mussel-inspired hydrophobic coatings for water-repellent textiles and oil removal.

    Science.gov (United States)

    García, Beatríz; Saiz-Poseu, Javier; Gras-Charles, Roser; Hernando, Jordi; Alibés, Ramon; Novio, Fernando; Sedó, Josep; Busqué, Félix; Ruiz-Molina, Daniel

    2014-10-22

    A series of catechol derivatives with a different number of linear alkyl chain substituents, and different length, have been shown to polymerize in the presence of aqueous ammonia and air, yielding hydrophobic coatings that present the ability to provide robust and efficient water repellency on weaved textiles, including hydrophilic cotton. The polymerization strategy presented exemplifies an alternative route to established melanin- and polydopamine-like functional coatings, affording designs in which all catechol (adhesive) moieties support specific functional side chains for maximization of the desired (hydrophobic) functionality. The coatings obtained proved effective in the transformation of polyester and cotton weaves, as well as filter paper, into reusable water-repellent, oil-absorbent materials capable of retaining roughly double their weight in model compounds (n-tetradecane and olive oil), as well as of separating water/oil mixtures by simple filtration.

  19. DIMENSIONAL STABILITY AND WATER REPELLENT EFFICIENCY MEASUREMENT OF CHEMICALLY MODIFIED TROPICAL LIGHT HARDWOOD

    Directory of Open Access Journals (Sweden)

    Md Saiful Islam,

    2012-01-01

    Full Text Available Chemical modification is an often-followed route to improve physical and mechanical properties of solid wood materials. In this study five kinds of tropical light hardwoods species, namely jelutong (Dyera costulata, terbulan (Endospermum diadenum, batai (Paraserianthes moluccana, rubberwood (Hevea brasiliensis, and pulai (Alstonia pneumatophora, were chemically modified with benzene diazonium salt to improve their dimensional stability and water repellent efficiency. The dimensional stability of treated samples in terms of volumetric swelling coefficient (S and anti-swelling-efficiency (ASE were found to improve with treatment. The water repellent efficiency (WRE values also seemed to improve considerably with treatment of wood samples. Furthermore, treated wood samples had lower water and moisture absorption compared to that of untreated ones.

  20. Post-Fire Moss Recovery in Northern Peatlands: Separating the Effects of Species and Water Content on Moss Water Repellency

    Science.gov (United States)

    Moore, Paul; Lukenbach, Max; Waddington, James Michael

    2016-04-01

    Wildfire is the largest disturbance affecting peatlands, where northern peat reserves are becoming increasingly vulnerable to wildfire as climate change is projected to enhance the length and severity of the fire season. However, little is known about the spatio-temporal variability of post-fire recovery in these ecosystems. High water table positions after wildfire are critical to limit atmospheric carbon losses and enable the re-establishment of keystone peatland mosses (i.e., Sphagnum). Post-fire recovery of the moss surface in Sphagnum-feathermoss peatlands, however, has been shown to be limited where moss type and burn severity interact to result in a water repellent surface. While in situ measurements of moss water repellency in peatlands has been shown to be greater for feathermoss in both a burned and unburned state in comparison to Sphagnum moss, it is difficult to separate effects of water content from species. Consequently, we carried out a drying experiment in the lab where we compared the water repellency of two dominant peatland moss species, Sphagnum and feathermoss, for several burn severity classes as well as for unburned samples. The results suggest that water repellency in moss is primarily controlled by water content, where a sharp threshold exists at gravimetric water contents (GWC) lower than ~3 g g-1. While GWC is shown to be a strong predictor of water repellency, the effect is enhanced by combustion. Based on field GWC, we show that there are significant differences in the frequency distribution of near-surface GWC between moss type and burn severity. The differences in the distributions of field GWC are related to characteristic moisture retention curves of unburned samples measured in the lab, as well as morphological differences between moss type.

  1. Effect of water content on the water repellency for hydrophobized sands

    Science.gov (United States)

    Subedi, S.; Kawamoto, K.; Kuroda, T.; Moldrup, P.; Komatsu, T.

    2011-12-01

    Alternative earthen covers such as capillary barriers (CBs) and evapotranspirative covers are recognized as useful technical and low-cost solutions for limiting water infiltration and controlling seepage flow at solid waste landfills in semi-arid and arid regions. However, their application to the landfills at wet regions seems to be matter of concern due to loss of their impending capability under high precipitation. One of the possible techniques to enhance the impermeable properties of CBs is to alter soil grain surfaces to be water-repellent by mixing/coating hydrophobic agents (HAs). In order to examine a potential use of model sands hydrophobized with locally available and environmental-friendly HAs such as oleic acid (OA) and stearic acid (SA) for hydrophobic CBs. In the present study, we first characterized the effect of water content on the degree of water repellency (WR) for hydrophobized sands and volcanic ash soil at different depth. Secondly, the time dependency of the contact angle in hydrophobized sands and volcanic ash soils at different water content was evaluated. Further, the effects of hydrophobic organic matter contents on the WR of hydrophobized sands were investigated by horizontal infiltration test. We investigated the degree of WR as functions of volumetric water content (θ) of a volcanic ash soil samples from different depth and water adjusted hydrophobized sand samples with different ratio of HAs by using sessile drop method (SDM). The initial contact angle (αi) measured from SDM decreased gradually with increasing water content in OA and SA coated samples. Measured αi values for volcanic ash soils increased with increasing water content and reached a peak values of 111.7o at θ= 0.325 cm3 cm-3, where-after αi gradually decreased. Each test sample exhibited sharp decrease in contact angle with time at higher water content. Sorptivity values for oleic acid coated samples decreased with increasing HA content and reached the minimum

  2. Inlfuence of Freeze-thaw Cycles on Properties of Integral Water Repellent Concrete

    Institute of Scientific and Technical Information of China (English)

    MA Zhiming; WITTMANN Folker H; XIAO Jianzhuang; ZHAO Tiejun

    2016-01-01

    Service life of reinforced concrete structures usually was designed on the basis of one selected deteriorating mechanism as for instance carbonation, chloride penetration, and frost action. It could be shown in the meantime by numerous authors, however, that combined actions such as chloride penetration under mechanical load or chloride penetration in combination with freeze-thaw cycles may shorten the service life of reinforced concrete structures more than individual processes acting alone. We have found that chloride penetration is accelerated significantly by freeze-thaw cycles. Frost damage not only reduces mechanical strength and elastic modulus but migration of chloride is facilitated in the damaged pore structure. Chloride penetration can be retarded by the addition of silane emulsion to the fresh concrete. In this way Integral Water Repellent Concrete (IWRC) can be produced. Migration of water and ions dissolved in water can not be prevented by integral water repellent treatment but it is slowed down. The combination of damage mechanisms and the protective measures by integral water repellent treatment have to be taken into consideration in realistic service life prediction and design.

  3. Effects of hydrophilic macropore fillings and coatings on the infiltration into water repellent porous media

    Science.gov (United States)

    Suetsugu, A.; Mori, Y.

    2012-12-01

    Macropores generate rapid flow paths in the surface soils by their high permeability under saturated/near-saturated moisture conditions. In natural soils, some macropores are filled/coated with various materials including decayed plant roots (Meek et al., 1989), exudates from plants/soil organisms (Jegou et al., 2001), iron oxides or other precipitates from preferentially-introduced solutes/colloids to the macropores (Rasmussen et al., 2001), or the surrounding soils with reduced bulk density (Ela et al., 1992). When we expect infiltration into water repellent soils through macropores or hydrophilic patches created from the macropore cementation processes, hydrophilicity of the macropore fillings/coatings should be understood. In the present study, we conducted an infiltration experiment with water repellent porous media and some macropore fillings/coatings, in order to clarify the roles of hydrophilic macropore fillings/coatings in infiltration. Ponding depth and flow distribution were monitored with a micro-focus X-ray computational tomography apparatus (SMX-90CT, Shimadzu Corp., Kyoto, Japan) at 90 kV and 110 μA. Dilute CsCl(aq) (density: 1.04 Mg m-3) was used as the contrast media to avoid density-driven alteration of the flows. Water repellency of the samples was evaluated by the water drop penetration time (WDPT, Van't Woudt, 1959). A glass beads (mean diameter: 0.46 mm, BZ-04, ASONE Corp., Osaka, Japan) was used as water repellent porous media. The glass beads sample was packed in 50-mL polypropylene centrifugation tubes at 1.55 Mg m-3 bulk density. A 2-mm hole was made at the bottom of each centrifugation tube for ventilation. The hole was covered with mesh cloth. Macroporous structure was made at the center of each tube from the surface. Each macroporous structure had 4-mm diameter and 30-mm length. Six types of macropores were prepared including 1) no macropore, 2) empty macropore, 3) an aluminum (Al) pipe (4-mm inner diameter, 5-mm outer diameter), 4) a

  4. Water-repellent coating: formation of polymeric self-assembled monolayers on nanostructured surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Woo Kyung [Department of Chemistry and School of Molecular Science (BK21), Center for Molecular Design and Synthesis, KAIST, Daejeon 305-701 (Korea, Republic of); Park, Sangjin [Research Center for Biomolecular Nanotechnology, Department of Life Science, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Jon, Sangyong [Research Center for Biomolecular Nanotechnology, Department of Life Science, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Choi, Insung S [Department of Chemistry and School of Molecular Science (BK21), Center for Molecular Design and Synthesis, KAIST, Daejeon 305-701 (Korea, Republic of)

    2007-10-03

    In this paper, we suggest a facile and effective method for water-repellent coating of oxide surfaces. As a coating material, we synthesized a new random copolymer, referred to as poly(TMSMA-r-fluoroMA), by the radical polymerization of 3-(trimethoxysilyl)propyl methacrylate (TMSMA) and a fluoromonomer'' (registered) bearing methacrylate moiety (fluoroMA). The random copolymer was designed to consist of a 'surface-reactive part' (trimethoxysilyl group) for anchoring onto oxide-based surfaces and a 'functional part' (perfluoro group) for water repellency. The polymeric self-assembled monolayers (pSAMs) of poly(TMSMA-r-fluoroMA) were constructed on three different aluminum oxide substrates, such as flat, concave-textured, and nanoporous plates, and the static water contact angle of each surface before and after the formation of pSAMs was measured. The formation of pSAMs resulted in significantly enhanced hydrophobicity compared with the corresponding bare surfaces. In particular, among three poly(TMSMA-r-fluoroMA)-coated surfaces, the nanoporous plate showed the highest water-repellent property, with a static contact angle of {approx}163 deg., which is indicative of superhydrophobic surfaces.

  5. Water-repellent coating: formation of polymeric self-assembled monolayers on nanostructured surfaces

    Science.gov (United States)

    Cho, Woo Kyung; Park, Sangjin; Jon, Sangyong; Choi, Insung S.

    2007-10-01

    In this paper, we suggest a facile and effective method for water-repellent coating of oxide surfaces. As a coating material, we synthesized a new random copolymer, referred to as poly(TMSMA-r-fluoroMA), by the radical polymerization of 3-(trimethoxysilyl)propyl methacrylate (TMSMA) and a fluoromonomer® bearing methacrylate moiety (fluoroMA). The random copolymer was designed to consist of a 'surface-reactive part' (trimethoxysilyl group) for anchoring onto oxide-based surfaces and a 'functional part' (perfluoro group) for water repellency. The polymeric self-assembled monolayers (pSAMs) of poly(TMSMA-r-fluoroMA) were constructed on three different aluminum oxide substrates, such as flat, concave-textured, and nanoporous plates, and the static water contact angle of each surface before and after the formation of pSAMs was measured. The formation of pSAMs resulted in significantly enhanced hydrophobicity compared with the corresponding bare surfaces. In particular, among three poly(TMSMA-r-fluoroMA)-coated surfaces, the nanoporous plate showed the highest water-repellent property, with a static contact angle of ~163°, which is indicative of superhydrophobic surfaces.

  6. Plasma treatment of polyester fabric to impart the water repellency property

    Indian Academy of Sciences (India)

    C J Jahagirdar; L B Tiwari

    2007-04-01

    Polyester fabric is treated with DCDMS solution by two methods: dipping the fabric directly in DCDMS solution for different intervals and dipping the fabric in DCDMS solution after its exposure into RF plasma chamber for different durations at optimized exposure power conditions. The physical properties of polyester fabric treated with DCDMS in the presence or absence of air plasma have been compared with control fabric. Different characterization techniques like scanning electron microscope, attenuated total reflectance-IR and Dataflash 100 colour measurement spectrophotometer are used to assess the surface morphology, composition and change in colour parameters. Water repellency property of both untreated and modified polyester fabric is studied using AATCC test method 39 (1971). The effectiveness of the water repellency property of modified polyester fabric is checked by repeated washing up to ten cycles.

  7. Nanoimprint lithography for green water-repellent film derived from biomass with high-light transparency

    Science.gov (United States)

    Takei, Satoshi; Hanabata, Makoto

    2015-03-01

    Newly eco-friendly high light transparency film with plant-based materials was investigated to future development of liquid crystal displays and optical devices with water repellency as a chemical design concept of nanoimprint lithography. This procedure is proven to be suitable for material design and the process conditions of ultraviolet curing nanoimprint lithography for green water-repellent film derived from biomass with high-light transparency. The developed formulation of advanced nanoimprinted materials design derived from lactulose and psicose, and the development of suitable UV nanoimprint conditions produced high resolutions of the conical shaped moth-eye regularly-nanostructure less than approximately 200 nm diameter, and acceptable patterning dimensional accuracy by the replication of 100 times of UV nanoimprint lithography cycles. The newly plant-based materials and the process conditions are expected as one of the defect less nanoimprint lithographic technologies in next generation electronic devices.

  8. Enhancing water repellence and mechanical properties of antibacterialgelatin/Ce(lll) fiber by heat treatment

    Institute of Scientific and Technical Information of China (English)

    LIU Lin; WANG Shiqi; HUANG Yaqin; ZHOU Yating; TONG Yuanjian; CHEN Xiaonong

    2011-01-01

    The water repellence and mechanical properties of the gelatin/Ce(Ⅲ) fiber (GCe fiber) were improved by heat treatment,which was an easy and non-toxic method.The microscopic morphology,mechanical properties,antibacterial activity,and cell culture of the GCe fibers by heat treatment (HGCe fiber) were investigated.It was found that the water repellence and mechanical properties of the HGCe fibers increased significantly along with temperature increase.SEM observation showed that HGCe fibers had a fairly smooth surface and a compact structure.Detailed characterization revealed that the HGCe fibers exhibited similar antibacterial activity with the GCe fibers against Staphylococcus aureus.In addition,the results of cell culture by morphological assessment and methylthiazolyl tetrazolium assay (MTT assay)indicated the good biocompatibility of GCe fibers.Therefore,the HGCe fibers could be a promising candidate biomaterial for biomedicine applications.

  9. Hydrophobic duck feathers and their simulation on textile substrates for water repellent treatment

    Energy Technology Data Exchange (ETDEWEB)

    Liu Yuyang; Chen Xianqiong; Xin, J H [Institute of Textiles and Clothing, Hong Kong Polytechnic University, Hong Kong (China)], E-mail: liuxx751@umn.edu

    2008-12-01

    Inspired by the non-wetting phenomena of duck feathers, the water repellent property of duck feathers was studied at the nanoscale. The microstructures of the duck feather were investigated by a scanning electron microscope (SEM) imaging method through a step-by-step magnifying procedure. The SEM results show that duck feathers have a multi-scale structure and that this multi-scale structure as well as the preening oil are responsible for their super hydrophobic behavior. The microstructures of the duck feather were simulated on textile substrates using the biopolymer chitosan as building blocks through a novel surface solution precipitation (SSP) method, and then the textile substrates were further modified with a silicone compound to achieve low surface energy. The resultant textiles exhibit super water repellent properties, thus providing a simple bionic way to create super hydrophobic surfaces on soft substrates using flexible material as building blocks.

  10. Basic soil properties as a factor controlling the occurrence and intensity of water repellency in rankers of the White Carpathians

    OpenAIRE

    Kořenková Lucia; Urík Martin

    2015-01-01

    Water repellency in soils is controlled by many different factors, basic physical and chemical properties might be considered the crucial ones. For the purpose of this study, 12 sites were selected and sampled (0–20 cm depth) in the White Carpathians. Repellency tests were conducted under laboratory conditions in triplicate using water drop penetration time (WDPT) test and the molarity of ethanol droplet (MED) test. Results of WDPT measurements showed that three samples were marked by slight ...

  11. Influence of water-repellent treatment on the properties lime and lime pozzolan mortars

    Directory of Open Access Journals (Sweden)

    Fortes Revilla, C.

    2001-06-01

    Full Text Available The influence that water-repellent products can have on physical and micro-structural properties of lime mortars, and lime plus pozzolan mortars has been studied. Three water repellent products have been used. Mixes of the previously mentioned three water repellents plus a biocide product were also applied. Treatments make the total porosity and saturation coefficient of both mortars to decrease, while colorimetric coordinates bear little alteration. All treatments with water repellent products provided mortars with a hydrophobic property index close to 100%. Durability of such mortars has been also studied: salt crystallization test, frost-thaw and dry-wet cycles, as well as ultraviolet radiation test were carried out. Relationship between mortars behavior and their porosity and saturation coefficient were found.

    En el presente trabajo se ha estudiado la influencia de la aplicación de productos hidrofugantes a morteros de cal y morteros de cal y puzolana sobre sus propiedades físicas y microestructurales. Se han estudiado tres productos hidrofugantes. También han sido estudiados dichos productos junto con un biocida. La porosidad total y el coeficiente de saturación de ambos tipos de morteros se ve reducido por el efecto de los tratamientos mientras que las coordenadas colorimétricas se ven poco alteradas. Todos los tratamientos confieren un índice de hidrofobicidad a los morteros próximo al 100%. Asimismo, también se ha estudiado la durabilidad de dichos morteros frente a la cristalización de sales, hielo-deshielo, los ciclos de humedad-sequedad y radiaciones ultravioleta. Se relaciona el comportamiento de los morteros con su porosidad y el coeficiente de saturación.

  12. Mussel-inspired hydrophobic coatings for water-repellent textiles and oil removal

    OpenAIRE

    García, Beatriz; Saiz-Poseu, Javier; Gras-Charles, Roser; Hernando, Jordi; Alibés, Ramón; Novio, Fernando; Sedó, Josep; Busqué, Félix; Ruiz Molina, Daniel

    2014-01-01

    A series of catechol derivatives with a different number of linear alkyl chain substituents, and different length, have been shown to polymerize in the presence of aqueous ammonia and air, yielding hydrophobic coatings that present the ability to provide robust and efficient water repellency on weaved textiles, including hydrophilic cotton. The polymerization strategy presented exemplifies an alternative route to established melanin- and polydopamine-like functional coatings, affording design...

  13. Advance of Study on Soil Water Repellency%土壤斥水性研究进展

    Institute of Scientific and Technical Information of China (English)

    李毅; 商艳玲; 李振华; 刘世宾

    2012-01-01

    简述了土壤斥水的基本概念,归纳了土壤斥水对农田水分循环、水土保持、地下水环境等的影响,分析了土壤斥水发生的原因,总结了国内外已采用的斥水度测定方法及其各自特点,并对土壤斥水度空间变异性、斥水土壤在入渗和蒸发过程中的水分运动规律及斥水土壤入渗性能改善方法的研究现状作了较全面的分析和评述.由于土壤斥水与农田水分循环、微生物活动、产流产沙和地下水环境污染之间存在密切联系,因此有必要进行相关问题的研究.%The basic concept of soil water repellency was introduced, the effects of soil water repellency on field water cycle, soil and water conservation, and ground water environment was summed up. The reasons of soil water repellency were analyzed. The domestic and international methods used for detecting the degree of soil water repellency and their characteristics were introduced. The research advancement of spatial variability for soil water repellency, soil water movement of water repellent soil during infiltration and evaporation process, and measures for improving infiltration ability of hydrophobic soil were also reviewed and assessed thoroughly. Since there were closed associations between soil water repellency and filed water cycle, microbe activity, runoff and sediment production, and pollution of ground water environment, it was urgent to do related research.

  14. Wetting properties of fungi mycelium alter soil infiltration and soil water repellency in a γ-sterilized wettable and repellent soil.

    Science.gov (United States)

    Chau, Henry Wai; Goh, Yit Kheng; Vujanovic, Vladimir; Si, Bing Cheng

    2012-12-01

    Soil water repellency (SWR) has a drastic impact on soil quality resulting in reduced infiltration, increased runoff, increased leaching, reduced plant growth, and increased soil erosion. One of the causes of SWR is hydrophobic fungal structures and exudates that change the soil-water relationship. The objective of this study was to determine whether SWR and infiltration could be manipulated through inoculation with fungi. The effect of fungi on SWR was investigated through inoculation of three fungal strains (hydrophilic -Fusarium proliferatum, chrono-amphiphilic -Trichoderma harzianum, and hydrophobic -Alternaria sp.) on a water repellent soil (WR-soil) and a wettable soil (W-soil). The change in SWR and infiltration was assessed by the water repellency index and cumulative infiltration respectively. F. proliferatum decreased the SWR on WR-soil and slightly increased SWR in W-soil, while Alternaria sp. increased SWR in both the W-soil and the WR-soil. Conversely T. harzianum increased the SWR in the W-soil and decreased the SWR in the WR-soil. All strains showed a decrease in infiltration in W-soil, while only the F. proliferatum and T. harzianum strain showed improvement in infiltration in the WR-soil. The ability of fungi to alter the SWR and enmesh soil particles results in changes to the infiltration dynamics in soil. Copyright © 2012 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

  15. Water repellency of fly ash-enriched forest soils from eastern Germany

    Energy Technology Data Exchange (ETDEWEB)

    Hartmann, P.; Fleige, H.; Horn, R. [Forest Research Institute, Freiburg (Germany). Dept. of Soils & Environment

    2010-12-15

    Fly ash-enriched soils occur widely throughout the industrial regions of eastern Germany and in other heavily industrialized areas. A limited amount of research has suggested that fly ash enrichment alters the water repellency (WR) characteristics of soil. This study concentrates on the influence of fly ash enrichment on WR of forest soils with a focus on forest floor horizons (FFHs). The soils were a Technosol developed from pure lignite fly ash, FFHs with lignite fly ash, and FFHs without lignite fly ash enrichment. Three different methods were used to characterize soil WR. Additionally, carbon composition was determined using {sup 13}C-NMR spectra to interpret the influence of the organic matter. This study showed that the actual WR characteristics of undisturbed, fly ash-enriched soils can be explained in terms of the composition of soil organic matter, with the fly ash content playing only a minimal role. Regardless of the huge amounts of mainly mineral fly ash enrichment, all undisturbed FFHs were comparable in their WR characteristics and their carbon compositions, which were dominated by recently-formed organic substances. The pure fly ash deposit was strongly influenced by lignite remains, with the topsoil having a greater content of recent plant residues. Thus, the undisturbed topsoil was more repellent than the subsoil. When homogenized samples were used, we found a distinct effect of fly ash enrichment and structure on WR. Water repellency of the pure fly ash horizons did not differ distinctly, while the fly ash enrichment in the FFHs caused a significant reduction in WR. These results led to the assumption that water-repellent structures of the topsoils were probably the result of hydrophobic coatings of recently formed organic substances, whereby the initially high wettability of the mainly mineral, hydrophilic fly ash particles was reduced.

  16. Spatial probability of soil water repellency in an abandoned agricultural field in Lithuania

    Science.gov (United States)

    Pereira, Paulo; Misiūnė, Ieva

    2015-04-01

    Water repellency is a natural soil property with implications on infiltration, erosion and plant growth. It depends on soil texture, type and amount of organic matter, fungi, microorganisms, and vegetation cover (Doerr et al., 2000). Human activities as agriculture can have implications on soil water repellency (SWR) due tillage and addition of organic compounds and fertilizers (Blanco-Canqui and Lal, 2009; Gonzalez-Penaloza et al., 2012). It is also assumed that SWR has a high small-scale variability (Doerr et al., 2000). The aim of this work is to study the spatial probability of SWR in an abandoned field testing several geostatistical methods, Organic Kriging (OK), Simple Kriging (SK), Indicator Kriging (IK), Probability Kriging (PK) and Disjunctive Kriging (DK). The study area it is located near Vilnius urban area at (54 49' N, 25 22', 104 masl) in Lithuania (Pereira and Oliva, 2013). It was designed a experimental plot with 21 m2 (07x03 m). Inside this area it was measured SWR was measured every 50 cm using the water drop penetration time (WDPT) (Wessel, 1998). A total of 105 points were measured. The probability of SWR was classified in 0 (No probability) to 1 (High probability). The methods accuracy was assessed with the cross validation method. The best interpolation method was the one with the lowest Root Mean Square Error (RMSE). The results showed that the most accurate probability method was SK (RMSE=0.436), followed by DK (RMSE=0.437), IK (RMSE=0.448), PK (RMSE=0.452) and OK (RMSE=0.537). Significant differences were identified among probability tests (Kruskal-Wallis test =199.7597 p<0.001). On average the probability of SWR was high with the OK (0.58±0.08) followed by PK (0.49±0.18), SK (0.32±0.16), DK (0.32±0.15) and IK (0.31±0.16). The most accurate probability methods predicted a lower probability of SWR in the studied plot. The spatial distribution of SWR was different according to the tested technique. Simple Kriging, DK, IK and PK methods

  17. Water and oil repellency of flexible silica-coated polymeric substrates

    Science.gov (United States)

    Hsieh, Chien-Te; Cheng, Yu-Shun; Hsu, Shu-Min; Lin, Jia-Yi

    2010-06-01

    A facile coating technique was used for the one-step creation of silica-sphere layers onto flexible polypropylene (PP) substrates, which showed the enhanced repellency toward liquid droplets with different surface tensions, ranging from 25.6 to 72.3 mN/m. One-step solution preparation comprised the homogenous mixing of colloidal silica nanospheres and perfluoroalkyl methacrylic copolymer, and the resulting F-silica slurry was subsequently deposited over the PP films, which showed good adhesion. The flexible silica-coated polymeric film displayed a remarkable repellency toward water and oil drops, when compared with the F-coated PP flat film. The silica-stacking layers on the PP substrate generated a roughened surface, owing to the creation of bionic surface hierarchically combined with multiple-scale architecture. To clarify this, the wetted fraction was determined from Cassie-Baxter equation, and the work of adhesion, based on Young-Duprè equation, was used to examine the sliding ability of the resulting polymeric films. The cross-cut test incorporated with film bending proved the excellent adherence between silica layer and PP substrate. A satisfactory durability in water and oil immersions for 10 days showed that the resulting PP film possesses strong adhesion and better repellency for a long period, confirming a promising commercial feasibility.

  18. Study of water repellent finishing on cotton with fluorosilicon soap-free water repellent agent%氟硅无皂拒水剂在棉织物拒水整理中的应用

    Institute of Scientific and Technical Information of China (English)

    李智斌; 樊增禄; 毛宁涛; 李庆; 蔡信彬

    2016-01-01

    为提高棉织物的拒水性能,采用自制的氟硅无皂拒水剂对棉织物进行整理.通过单因素试验优化拒水整理的工艺条件,测试拒水整理棉织物的拒水性及透气性等,并与市售拒水剂进行对比.结果表明,在氟硅无皂拒水剂60g/L ,二浸二轧,100℃下预烘4min ,170℃下焙烘3min ,整理后棉织物对水的接触角达到138.6°,静水压为2.83kPa ,表现出良好的拒水效果.%In order to improve the properties of water repellency for cotton fabrics ,selfmade flu-orosilicon soap-free water repellent agent is used to finish cotton fabric .The process conditions of water repellent finishing was optimized by single factor test ,the water repellency and air permeability of the finished cotton fabric were tested ,and compared with the market-sold water repellent agents .The result shows that using 60g/L fluorosilicon soap-free water repellent a-gent ,two-padding two-rolling ,drying at 100 ℃ for 4min ,baking at 170 ℃ for 3min ,the con-tact angle and hydrostatic pressure reached 138.6° and 2.83kPa ,the cotton fabric treated ex-hibited good water-repellent properties .

  19. Spatial distribution of soil water repellency in a grassland located in Lithuania

    Science.gov (United States)

    Pereira, Paulo; Novara, Agata

    2014-05-01

    Soil water repellency (SWR) it is recognized to be very heterogeneous in time in space and depends on soil type, climate, land use, vegetation and season (Doerr et al., 2002). It prevents or reduces water infiltration, with important impacts on soil hydrology, influencing the mobilization and transport of substances into the soil profile. The reduced infiltration increases surface runoff and soil erosion. SWR reduce also the seed emergency and plant growth due the reduced amount of water in the root zone. Positive aspects of SWR are the increase of soil aggregate stability, organic carbon sequestration and reduction of water evaporation (Mataix-Solera and Doerr, 2004; Diehl, 2013). SWR depends on the soil aggregate size. In fire affected areas it was founded that SWR was more persistent in small size aggregates (Mataix-Solera and Doerr, 2004; Jordan et al., 2011). However, little information is available about SWR spatial distribution according to soil aggregate size. The aim of this work is study the spatial distribution of SWR in fine earth (Mataix-Solera, J., Nava, A.L., Alanis, N. (2011) Effects of fire severity on water repellency and agregate stability on mexican volcanic soils, Catena, 84, 136-147. Mataix-Solera, J., Doerr, S. (2004) hydrophobicity and agregate stability in calcareous topsoils from fire-affected pine forests in south-easthern Spain, Geoderma, 118, 77-88. Wessel, A.T. (1988) On using the effective contact angle and the water drop penetration time for classification of water repellency in dune soils, Earth Surfaces Process. Landforms, 13, 555-562, 1988.

  20. Consolidating and water repellent treatments applied to wet and salt contaminated granite

    Directory of Open Access Journals (Sweden)

    Silva, B.

    2000-03-01

    Full Text Available A comparison was made of the efficacy of two consolidants and two water repellents applied to samples of granite under optimum conditions, with the efficacy of the same products applied to the granite in the presence of soluble salts or water. The amount of product absorbed and the amount of dry polymer remaining after treatment were compared. The results show that the presence of water and soluble salts in the stone significantly modifies the consumption of the products (in particular the water repellents and also the level of dry polymer retained. The water repellents were found to be much less effective when the substrate contained salts, whereas the presence of water did not appear to influence their efficacy. The lack of correlation between uptake, active dry polymer, and efficacy led to the conclusion that the presence of salts or water markedly changes the kinetics of the polymerization of the products.

    Se analiza la eficacia de dos consolidantes y dos hidrofugantes aplicados a rocas graníticas en condiciones óptimas comparativamente a la eficacia de los mismos productos aplicados sobre los mismos sustratos conteniendo cierta cantidad de sales solubles o de agua. Se compara la cantidad de producto absorbido y la cantidad de materia seca presente tras el curado. Los resultados indican que la presencia de agua y de sales solubles en la piedra modifica significativamente el consumo de los productos, sobre todo el de los hidrofugantes, así como la cantidad de materia seca. Se observa, asimismo, un fuerte detrimento en la eficacia de los hidrofugantes cuando el sustrato contiene sales mientras que, al contrario, la presencia de agua no parece infiuir en dicha eficacia. La falta de correlación entre el consumo, materia seca activa y eficacia lleva a concluir que la presencia de sales o agua modifica sensiblemente la cinética de la polimeración de los productos.

  1. Dynamic soil water repellency during infiltration of water, ethanol, and aqueous ethanol solutions in post wildfire soils

    Science.gov (United States)

    Beatty, Sarah; Smith, James

    2015-04-01

    Contact angle dynamics, the temporal dependence of repellency, and the persistence of repellency are all terms used to describe dynamic changes in soil water repellency with time. Studied over varied spatial and temporal scales, much remains to be known about dynamic soil water repellency and its role during infiltration. Of those approaches used to characterize dynamic soil water repellency and develop mechanistic insight, tension infiltration has become an important one. Removing positive pore water pressures through tension infiltration facilitates the observation of infiltration initiated by capillary pull and experimentally eliminates one of the competing mechanisms that generates non-uniqueness. This makes tension infiltrometers and the data they generate uniquely sensitive to (primary) changes in contact angles and fractional wettability. Changes, which are subsumed when positive pore water pressures are the primary drivers of infiltration, as is the case during ponded infiltration in water repellent soils. One pressing challenge, however, is that analytical approaches, based on idealized wettable-system principles (e.g. 0° and/or static contact angles), yield suspect results in non-wetting / fractionally wettable / dynamic systems. Consequently, complex infiltration behaviours, and linkages between fundamental process oriented understanding and real-world problems, remain poorly understood. This persistently impedes our ability to accurately describe, model, and predict flow in water repellent systems. To help address this knowledge gap, this work presents suites of in situ field (3D) and laboratory (1D) experimental data collected in naturally repellent post wildfire soils using tension infiltrometers (4.4cm and 8cm, respectively) and different infiltrating fluids. In the field, 49 infiltration tests using water, ethanol (95%), and Molarity of Ethanol Drop (MED)-derived aqueous ethanol solutions indicated that early- and late-time infiltration behaviours

  2. Contact Angles of Water-repellent Porous Media Inferred by Tensiometer- TDR Probe Measurement Under Controlled Wetting and Drying Cycles

    DEFF Research Database (Denmark)

    Subedi, Shaphal; Komatsu, Ken; Komatsu, Toshiko;

    2013-01-01

    The time dependency of water repellency (WR) in hydrophobic porous media plays a crucial role for water infiltration processes after rainfall and for the long-term performance of capillary barrier systems. The contact angle (CA) of hydrophobic media normally decreases with continuous contact...... equipped with a mini-time domain reflectometry (TDR) coil probe under controlled wetting and drying in a water-repellent volcanic ash soil (VAS) and in sands coated with different hydrophobic agents. The contact angle (CA–SWRC) under imbibition was evaluated based on the inflection points on the water...... retention curves. For both water-repellent VAS and hydrophobized sand samples, the calculated CA–SWRC increased with increasing WR. This was determined from both the water drop penetration time and the initial contact angle (CAi) by the sessile drop method. Calculated CA–SWRC values ranged from 20° to 48...

  3. The Influence of Plant Litter on Soil Water Repellency: Insight from 13C NMR Spectroscopy.

    Science.gov (United States)

    Cesarano, Gaspare; Incerti, Guido; Bonanomi, Giuliano

    2016-01-01

    Soil water repellency (SWR, i.e. reduced affinity for water owing to the presence of organic hydrophobic coatings on soil particles) has relevant hydrological implications because low rates of infiltration enhance water runoff, and untargeted diffusion of fertilizers and pesticides. Previous studies investigated the occurrence of SWR in ecosystems with different vegetation cover but did not clarify its relationships with litter biochemical quality. Here, we investigated the capability of different plant litter types to induce SWR by using fresh and decomposed leaf materials from 12 species, to amend a model sandy soil over a year-long microcosm experiment. Water repellency, measured by the Molarity of an Ethanol Droplet (MED) test, was tested for the effects of litter species and age, and compared with litter quality assessed by 13C-CPMAS NMR in solid state and elemental chemical parameters. All litter types were highly water repellent, with MED values of 18% or higher. In contrast, when litter was incorporated into the soil, only undecomposed materials induced SWR, but with a large variability of onset and peak dynamics among litter types. Surprisingly, SWR induced by litter addition was unrelated to the aliphatic fraction of litter. In contrast, lignin-poor but labile C-rich litter, as defined by O-alkyl C and N-alkyl and methoxyl C of 13C-CPMAS NMR spectral regions, respectively, induced a stronger SWR. This study suggests that biochemical quality of plant litter is a major controlling factor of SWR and, by defining litter quality with 13C-CPMAS NMR, our results provide a significant novel contribution towards a full understanding of the relationships between plant litter biochemistry and SWR.

  4. Soil water repellency under stones, forest residue mulch and bare soil following wildfire.

    Science.gov (United States)

    Martins, Martinho A. S.; Prats, Sérgio A.; van Keulen, Daan; Vieira, Diana C. S.; Silva, Flávio C.; Keizer, Jan J.; Verheijen, Frank G. A.

    2017-04-01

    Soil water repellency (SWR) is a physical property that is commonly defined as the aptitude of soil to resist wetting. It has been documented for a wide range of soil and vegetation types, and can vary with soil organic matter (SOM) content and type, soil texture, soil moisture content (SMC) and soil temperature. Fire can induce, enhance or destroy SWR and, therefore, lead to considerable changes in soil water infiltration and storage and increase soil erosion by water, thereby weakening soil quality. In Portugal, wildfires occur frequently and affect large areas, on average some 100000 ha per year, but over 300000 ha in extreme years such as 2003 and 2005. This can have important implications in geomorphological and hydrological processes, as evidenced by the strong and sometimes extreme responses in post-fire runoff and erosion reported from various parts of the world, including Portugal. Thereby, the application of mulches from various materials to cover burned areas has been found to be an efficient stabilization treatment. However, little is known about possible side effects on SWR, especially long term effects. Forest SWR is very heterogeneous, as a result of variation in proximity to trees/shrubs, litter type and thickness, cracks, roots, and stones. This study targeted the spatial heterogeneity of soil water repellency under eucalypt plantation, five years after a wildfire and forest residue mulching application. The main objectives of this work were: 1) to assess the long-term effect of mulching application on the strength and spatial heterogeneity of topsoil SWR, by comparing SWR on bare soil, under stones, and under mulching remains; 2) to assess SWR at 1 cm depth between O and Ah horizons. The soil surface results showed that untreated bare soil areas were slightly more water repellent than mulched areas. However, under stones there were no SWR differences between mulched and control areas. At 1 cm depth, there was a marked mulching effect on SWR, even

  5. The Influence of Plant Litter on Soil Water Repellency: Insight from 13C NMR Spectroscopy.

    Directory of Open Access Journals (Sweden)

    Gaspare Cesarano

    Full Text Available Soil water repellency (SWR, i.e. reduced affinity for water owing to the presence of organic hydrophobic coatings on soil particles has relevant hydrological implications because low rates of infiltration enhance water runoff, and untargeted diffusion of fertilizers and pesticides. Previous studies investigated the occurrence of SWR in ecosystems with different vegetation cover but did not clarify its relationships with litter biochemical quality. Here, we investigated the capability of different plant litter types to induce SWR by using fresh and decomposed leaf materials from 12 species, to amend a model sandy soil over a year-long microcosm experiment. Water repellency, measured by the Molarity of an Ethanol Droplet (MED test, was tested for the effects of litter species and age, and compared with litter quality assessed by 13C-CPMAS NMR in solid state and elemental chemical parameters. All litter types were highly water repellent, with MED values of 18% or higher. In contrast, when litter was incorporated into the soil, only undecomposed materials induced SWR, but with a large variability of onset and peak dynamics among litter types. Surprisingly, SWR induced by litter addition was unrelated to the aliphatic fraction of litter. In contrast, lignin-poor but labile C-rich litter, as defined by O-alkyl C and N-alkyl and methoxyl C of 13C-CPMAS NMR spectral regions, respectively, induced a stronger SWR. This study suggests that biochemical quality of plant litter is a major controlling factor of SWR and, by defining litter quality with 13C-CPMAS NMR, our results provide a significant novel contribution towards a full understanding of the relationships between plant litter biochemistry and SWR.

  6. 可聚合乳化剂对氟硅拒水剂拒水性能的影响%Effect of polymerizable emulsifier on water repellency of fluorosilicone water repellent agent

    Institute of Scientific and Technical Information of China (English)

    李智斌; 樊增禄; 李庆; 蔡信彬

    2016-01-01

    以甲基丙烯酸月桂酯(LMA)、甲基丙烯酸甲酯(MMA)、甲基丙烯酸十二氟庚酯(G-04)、乙烯基三乙氧基硅烷(KH-151)为反应单体,采用半连续乳液聚合法合成了氟硅改性丙烯酸酯无皂乳液。探讨了4种可聚合乳化剂(A、B、C、D)对所合成氟硅拒水剂拒水性能的影响,并与采用阴离子型乳化剂制得的拒水剂进行了拒水性能比较。结果表明,与采用阴离子乳化剂合成的拒水剂相比,采用可聚合乳化剂制备的无皂拒水剂的拒水效果更佳;将可聚合乳化剂A、B按质量比2∶1进行复配时,拒水剂的拒水效果最佳;纯棉织物经拒水整理后对水的接触角可达138.6°,静水压可达2.83 kPa,表现出良好的拒水效果。%The fluorosilicone modified acrylate soap- free emulsion was synthesized by semi continuous emulsion polymerization, employing lauryl methacrylate (LMA), methyl methacrylate (MMA), dodecafluorohep⁃tyl methacrylate (G- 04) and triethoxyvinylsilane (KH- 151) as monomers. The influences of four polymerizable emulsifiers (A,B,C,D) on the water repel ency of the fluorosilicone water repel ent agent were discussed, and the water repel ency were compared with another water repel ent agent prepared by anionic emulsifier. The re⁃sults showed that the soap free water repel ent agent performed better water repel ency. The properties of flu⁃orosilicone water repel ent agent were the optimum when A and B were mixed as the mass ratio of 2∶1. The cotton fabric treated by soap free water repel ent agent exhibited good water repel ent properties with 138.6° of contact angle and 2.83 kPa of hydrostatic pressure.

  7. Wet-dry cycles effect on ash water repellency. A laboratory experiment.

    Science.gov (United States)

    Pereira, Paulo; Cerdà, Artemi; Oliva, Marc; Mataix, Jorge; Jordán, Antonio

    2014-05-01

    In the immediate period after the fire, the ash layer has a strong influence on soil hydrological processes, as runoff, infiltration and erosion. Ash is very dynamic in the space and time. Until the first rainfall periods, ash is (re)distributed by the wind. After it can cover the soil surface, infiltrate or transported to other areas by water transport (Pereira et al., 2013a, b). This will have strong implications on nutrient redistribution and vegetation recovery. Ash layer may affect soil water repellency in different ways, depending on fire severity, soil properties and vegetation. Ash produced at low temperatures after low-severity burning is usually hydrophobic (Bodi et al., 2011, 2012). Wet-dry cycles have implications on ash physical and chemical properties, changing their effects in space and time. The aim of this study is to analyse the effects of fire temperature and severity on ash water repellency. Pinus sylvestris needles were collected in a Lithuania forest in Dzukija National Park (53º 54' N and 24º 22' E), transported to laboratory and washed with deionized water to remove soil particles and other residues. Needle samples were dried during 24 hours and exposed to different temperatures: 200, 300, 400 and 500 ºC, during 2 hours. Ash colour was analysed according to the Munsell Soil Color charts. Ash was black (10 YR 2/1) at 200 ºC, very dark grey (10YR 3/1) at 300 ºC, gray (10YR 5/1) at 400 ºC and light gray (10YR 7/1) at 500 ºC. Ten samples of ash released after each treatment were placed in plastic dishes (50 mm in diameter) in an amount enough to form a 5 mm thick layer, and ash water repellency was measured according to the Water Drop Penetration Test. Later, ash was carefully wetted with 15 ml of deionized water and placed in an oven during 4 days (96 hours), as in Bodí et al. (2012). This procedure was repeated 5 times in order to observe the effects of wet-dry cycles in ash water repellency. The results showed significant differences

  8. The influence of fire history, plant species and post-fire management on soil water repellency in a Mediterranean catchment

    NARCIS (Netherlands)

    Keesstra, Saskia; Wittenberg, Lea; Maroulis, Jerry; Sambalino, Francesco; Malkinson, Dan; Cerdà, Artemi; Pereira, Paulo

    2017-01-01

    Fire is a key factor impacting soil hydrology in many Mediterranean catchments. Soil water repellency (SWR) can stimulate land degradation processes by reducing the affinity of soil and water thereby triggering a reduction in soil fertility and increasing soil and water losses. The effects of two

  9. Evaluation of water repellent treatments applied to stones used in andalusian cathedrals. II. Salt crystallization test

    Directory of Open Access Journals (Sweden)

    Villegas Sánchez, R.

    1993-06-01

    Full Text Available In a previous paper we have studied the changes that have ocurred in the properties related to water access and movement in the stone after the application of water repellent treatments. In this work we compare the weathering resistance of treated and untreated samples by means of sodium sulphate crystallization test. After finishing the test (75 cycles properties related to water have been measured again to know if the treatments have undergone any kind of deterioration and lose their water repellent characteristics.

    En un artículo anterior se han evaluado los cambios producidos en las propiedades relacionadas con el acceso y movimiento de agua en la piedra como consecuencia de la aplicación de tratamientos de hidrofugación. En este trabajo se compara la resistencia a la alteración producida por sales de las probetas tratadas y sin tratar, sometiéndolas al ensayo de cristalización de sulfato sódico. Tras finalizar el ensayo (75 ciclos se han medido nuevamente las propiedades relacionadas con el agua, con objeto de comprobar si los tratamientos han sufrido alguna alteración y si mantienen sus características hidrófugas.

  10. Increased ambient air temperature alters the severity of soil water repellency

    Science.gov (United States)

    van Keulen, Geertje; Sinclair, Kat; Hallin, Ingrid; Doerr, Stefan; Urbanek, Emilia; Quinn, Gerry; Matthews, Peter; Dudley, Ed; Francis, Lewis; Gazze, S. Andrea; Whalley, Richard

    2017-04-01

    Soil repellency, the inability of soils to wet readily, has detrimental environmental impacts such as increased runoff, erosion and flooding, reduced biomass production, inefficient use of irrigation water and preferential leaching of pollutants. Its impacts may exacerbate (summer) flood risks associated with more extreme drought and precipitation events. In this study we have tested the hypothesis that transitions between hydrophobic and hydrophilic soil particle surface characteristics, in conjunction with soil structural properties, strongly influence the hydrological behaviour of UK soils under current and predicted UK climatic conditions. We have addressed the hypothesis by applying different ambient air temperatures under controlled conditions to simulate the effect of predicted UK climatic conditions on the wettability of soils prone to develop repellency at different severities. Three UK silt-loam soils under permanent vegetation were selected for controlled soil perturbation studies. The soils were chosen based on the severity of hydrophobicity that can be achieved in the field: severe to extreme (Cefn Bryn, Gower, Wales), intermediate to severe (National Botanical Garden, Wales), and subcritical (Park Grass, Rothamsted Research near London). The latter is already highly characterised so was also used as a control. Soils were fully saturated with water and then allowed to dry out gradually upon exposure to controlled laboratory conditions. Soils were allowed to adapt for a few hours to a new temperature prior to initiation of the controlled experiments. Soil wettability was determined at highly regular intervals by measuring water droplet penetration times. Samples were collected at four time points: fully wettable, just prior to and after the critical soil moisture concentrations (CSC), and upon reaching air dryness (to constant weight), for further (ultra)metaproteomic and nanomechanical studies to allow integration of bulk soil characterisations with

  11. Making thin polymeric materials, including fabrics, microbicidal and also water-repellent.

    Science.gov (United States)

    Lin, Jian; Murthy, Shashi K; Olsen, Bradley D; Gleason, Karen K; Klibanov, Alexander M

    2003-10-01

    A procedure is developed and validated for making a non-functionalized polyolefin fabric/film highly bactericidal and fungicidal which involves a free-radical grafting of maleic anhydride, followed by an attachment of polyethylenimine (PEI) and its subsequent N-alkylation. Separately, cotton fabric coated with a micron layer of a hydrophobic polymer using hot-filament chemical vapor deposition is rendered markedly hydrophobic; if this coating is preceded by immobilization of N-alkyl-PEI, the fabric becomes both water-repellent and bactericidal.

  12. The water-repellent cerotegument of whip-spiders (Arachnida: Amblypygi).

    Science.gov (United States)

    Wolff, Jonas O; Seiter, Michael; Gorb, Stanislav N

    2017-01-01

    The cuticle of arthropods is usually composed of layers of a chitin-protein-microcomposite, a proteinaceous epicuticle and a thin lipid coating. However, in some instances a thick cement layer (cerotegument) covers the cuticle and may produce elaborate microstructures. This has previously been described for millipedes and mites. Here we report the previously unknown presence of a superhydrophobic cerotegument in whip-spiders (Ambypygi) and reveal its variation in ultrastructure and water-repellence between species. We discuss the relevance of found micro-morphological and physical characters for taxonomy and phylogenetics of this group, and the potential biological functions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Electrodeposition of Water-Repellent Organic Dielectric Film as an Anti-Sticking Coating on Microelectromechanical System Devices

    Science.gov (United States)

    Sakata, Tomomi; Kuwabara, Kei; Shimamura, Toshishige; Sato, Norio; Nagase, Masao; Shimoyama, Nobuhiro; Kudou, Kazuhisa; Machida, Katsuyuki; Ishii, Hiromu

    2007-09-01

    In this paper, we propose a technique of preventing both wet-release-related and in-use sticking of actuators in microelectromechanical system (MEMS) devices. The technique involves the electrodeposition of a water-repellent organic dielectric film that renders the microstructure surface inactive towards the water used for rinsing. The source material is a core/shell emulsion, which consists of sulfonium cations with epoxy groups containing water-repellent silicone polymers. Applying this technique to the encapsulation of a microstructure confirms its effectiveness in preventing both release-related sticking and in-use sticking of a MEMS structure.

  14. Soil water repellency characteristic curves for soil profiles with natural organic carbon gradients

    Science.gov (United States)

    Kawamoto, Ken; Müller, Karin; Moldrup, Per; de Jonge, Lis; Clothier, Brent; Hiradate, Syuntaro; Komatsu, Toshiko

    2014-05-01

    Soil water repellency (SWR) is a phenomenon that influences many soil hydrologic processes such as reduction of infiltration, increase in overland flow, and enhanced preferential flow. SWR has been observed in various soil types and textures, and the degree of SWR is greatly controlled by soil moisture content and levels of organic matter and clay. One of the key topics in SWR research is how to describe accurately the seasonal and temporal variation of SWR with the controlling factors such as soil moisture, organic matter, and clay contents for soil profiles with natural organic carbon gradients. In the present study, we summarize measured SWR data for soil profiles under different land uses and vegetation in Japan and New Zealand, and compared these with literature data. We introduce the contact angle-based evaluation of SWR and predictive models for soil water repellency characteristic curves, in which the contact angle is a function of the moisture content. We also discuss a number of novel concepts, including i) the reduction in the contact angle with soil-water contact time to describe the time dependence of SWR, ii) the relationship between the contact angles from the measured scanning curves under controlled wetting and drying cycles, and iii) the initial contact angles measured by the sessile drop method.

  15. Water/oil repellent property of polyester fabrics after supercritical carbon dioxide finishing

    Directory of Open Access Journals (Sweden)

    Xu Yan-Yan

    2015-01-01

    Full Text Available The strong permeability and driving force of supercritical carbon dioxide renders it an ideal medium for fabrics finishing. This paper is to use supercritical carbon dioxide medium with a solution of organic fluorine to fabricate water/oil repellent polyester fabrics. A series of characterization methods including Fourier transform infrared spectrometry, energy dispersive spectrometry, and scanning electron microscopy were carried out to evaluate the fabrics finishing. Fourier transform infrared spectrometry showed that the transmittance peak appeared at 1202.4 and 1147.4 cm-1, indicating the presence of -CF2- group on the surface of polyester fabrics. The results of energy dispersive spectrometer and scanning electron microscopy showed that the fluorine was evenly distributed on the fibers surface. In addition, a series of physical properties were detected, including contact angel, air permeability, breaking strength, and wearing resistance. The average water and hexadecane contact angles were 147.58° and 143.78°, respectively. Compared with the initial fabrics, the treated one has little change in air permeability, while its strength increased greatly. The treated fabrics gained good water/oil repellent properties while keeping good air permeability and improving mechanical property.

  16. Preparation of Water-Repellent Glass by Sol-Gel Process Using Perfluoroalkylsilane and Tetraethoxysilane.

    Science.gov (United States)

    Jeong, Hye-Jeong; Kim, Dong-Kwon; Lee, Soo-Bok; Kwon, Soo-Han; Kadono, Kohei

    2001-03-01

    Coating films on glass substrate were prepared by sol-gel process using alkoxide solutions containing perfluoroalkylsilane (PFAS) and tetraethoxysilane (TEOS). The physical properties of the coating films were characterized by SEM, FT-IR, and XRD. And their surface properties were investigated by measuring contact angles and atomic compositions. Transparent coating films with smooth surface and uniform thickness could be obtained. The contact angles of the coating films for water and methylene iodide are extremely high, at 118 degrees and 97 degrees, respectively, and their surface free energies are about 9.7 dyn/cm. It was found that the water-repellent glass prepared is very hydrophobic and exhibits excellent water-repellency. Hydrophobic perfluoroalkyl groups are preferentially enriched to the outermost layer at the coating film-air interface, and two layers probably exist in the coating film. The upper layer oriented toward the air is composed of mainly perfluoroalkyl groups originating from PFAS, and the lower layer is composed of mainly -OSiO- groups originating from TEOS. The heat treatment after drying step cannot influence the surface enrichment of the perfluoroalkyl group. The hydrolysis reaction should be more completely done before the dip coating step to obtain lower surface free energy. The burning temperature should be less than 300 degrees C because the perfluoroalkyl group begins to decompose from this temperature. Copyright 2001 Academic Press.

  17. Design of Inorganic Water Repellent Coatings for Thermal Protection Insulation on an Aerospace Vehicle

    Science.gov (United States)

    Fuerstenau, D. W.; Ravikumar, R.

    1997-01-01

    In this report, thin film deposition of one of the model candidate materials for use as water repellent coating on the thermal protection systems (TPS) of an aerospace vehicle was investigated. The material tested was boron nitride (BN), the water-repellent properties of which was detailed in our other investigation. Two different methods, chemical vapor deposition (CVD) and pulsed laser deposition (PLD), were used to prepare the BN films on a fused quartz substrate (one of the components of thermal protection systems on aerospace vehicles). The deposited films were characterized by a variety of techniques including X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. The BN films were observed to be amorphous in nature, and a CVD-deposited film yielded a contact angle of 60 degrees with water, similar to the pellet BN samples investigated previously. This demonstrates that it is possible to use the bulk sample wetting properties as a guideline to determine the candidate waterproofing material for the TPS.

  18. Determination of the efficacy of two water repellents applied to granite

    Directory of Open Access Journals (Sweden)

    Rivas, T.

    1998-03-01

    Full Text Available We evaluated the efficacy of two water-repellents applied to three types of granitic rock widely used in building construction and restoration in Galicia (NW Spain. The depth of penetration of the water-repellents was determined by measuring capillary absorption by the treated rock. The efficacies of the water-repellent were evaluated in terms of two parameters characteristic of surface wet: water-rock contact angle and the time taken for absorption of microgroplets. The effects of the treatments on the rocks' surface color and permeability to water vapor were also determined. The results indicate that neither water-repellent effectively penetrates the rock surface, and both induce undesirably high reductions in vapor permeability. Notwithstanding, both agents effectively improved the rocks' resistance to surface wetting, without altering its surface color. Overall, determination of water-rock contact angle and the time taken for absorption of microdroplets, together with colorimetric characterization of the treated rock, constitutes an useful approach to evaluation of the effects of water-repellents on granitic rocks. Nonetheless, it should be borne in mind that the marked heterogeneity of this type of rock, and the associated mineralogy and dominant type of fissuration are sources of considerable variation in the measurement parameters.

    Se presentan los resultados de la aplicación de dos tratamientos hidrofugantes a tres rocas graníticas ampliamente utilizadas en la construcción y restauración en Galicia. Se ha determinado la profundidad de penetración de los hidrofugantes a través de la absorción capilar, la eficacia de los tratamientos comparando dos parámetros relacionados con el mojado superficial (ángulo de contacto roca-agua y tiempo de absorción de microgotas, y las variaciones en el color y en la permeabilidad al vapor. Se comprueba que si bien ambos tratamientos penetran deforma muy escasa en las rocas graníticas y

  19. Prescribed burning effects on soil physical properties and soil water repellency in a steep chaparral watershed, southern California, USA

    Science.gov (United States)

    K.R. Hubbert; H.K. Preisler; P.M. Wohlgemuth; R.C. Graham; M.G. Narog

    2006-01-01

    Chaparral watersheds associated with Mediterranean-type climate are distributed over five regions of the world. Because brushland soils are often shallow with low water holding capacities, and are on slopes prone to erosion, disturbances such as fire can adversely affect their physical properties. Fire can also increase the spatial coverage of soil water repellency,...

  20. The potential attractant or repellent effects of different water types on oviposition in Aedes aegypti L. (Dipt., Culicidae)

    NARCIS (Netherlands)

    Navarro, D.M.A.F.; Oliveira, de P.E.S.; Potting, R.P.J.; Brito, A.C.; Fital, S.J.F.; Goulart Sant Ana, A.E.

    2003-01-01

    The selection of oviposition sites by the yellow-fever mosquito, Aedes aegypti , was studied in the laboratory. The repellent or attractant effects of salinity and the presence of bacteria in water collected from a local community on the Brazilian coast were investigated. Water contaminated with

  1. The potential attractant or repellent effects of different water types on oviposition in Aedes aegypti L. (Dipt., Culicidae)

    NARCIS (Netherlands)

    Navarro, D.M.A.F.; Oliveira, de P.E.S.; Potting, R.P.J.; Brito, A.C.; Fital, S.J.F.; Goulart Sant Ana, A.E.

    2003-01-01

    The selection of oviposition sites by the yellow-fever mosquito, Aedes aegypti , was studied in the laboratory. The repellent or attractant effects of salinity and the presence of bacteria in water collected from a local community on the Brazilian coast were investigated. Water contaminated with bac

  2. Water repellent porous silica films by sol-gel dip coating method.

    Science.gov (United States)

    Rao, A Venkateswara; Gurav, Annaso B; Latthe, Sanjay S; Vhatkar, Rajiv S; Imai, Hiroaki; Kappenstein, Charles; Wagh, P B; Gupta, Satish C

    2010-12-01

    The wetting of solid surfaces by water droplets is ubiquitous in our daily lives as well as in industrial processes. In the present research work, water repellent porous silica films are prepared on glass substrate at room temperature by sol-gel process. The coating sol was prepared by keeping the molar ratio of methyltriethoxysilane (MTES), methanol (MeOH), water (H(2)O) constant at 1:12.90:4.74, respectively, with 2M NH(4)OH throughout the experiments and the molar ratio (M) of MTES/Ph-TMS was varied from 0 to 0.22. A simple dip coating technique is adopted to coat silica films on the glass substrates. The static water contact angle as high as 164° and water sliding angle as low as 4° was obtained for silica film prepared from M=0.22. The surface morphological studies of the prepared silica film showed the porous structure with pore sizes typically ranging from 200nm to 1.3μm. The superhydrophobic silica films prepared from M=0.22 retained their superhydrophobicity up to a temperature of 285°C and above this temperature the films became superhydrophilic. The porous and water repellent silica films are prepared by proper alteration of the Ph-TMS in the coating solution. The prepared silica films were characterized by surface profilometer, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier Transform Infrared (FT-IR) spectroscopy, humidity tests, chemical aging tests, static and dynamic water contact angle measurements.

  3. A Multifunctional Surface That Simultaneously Balances Hydrophilic Enzyme Catalysis and Hydrophobic Water Repellency.

    Science.gov (United States)

    Lawton, Timothy J; Uzarski, Joshua R; Filocamo, Shaun F

    2016-08-16

    The compatibility of multiple functions at a single interface is difficult to achieve, but is even more challenging when the functions directly counteract one another. This study provides insight into the creation of a simultaneously multifunctional surface formed by balancing two orthogonal functions; water repellency and enzyme catalysis. A partially fluorinated thiol is used to impart bulk hydrophobicity on the surface, and an N-hydroxysuccinimide ester-terminated thiol provides a specific anchoring sites for the covalent enzyme attachment. Different ratios of the two thiols are mixed together to form amphiphilic self-assembled monolayers, which are characterized with polarization-modulation infrared reflection-absorption spectroscopy and contact angle goniometry. The enzyme activity is measured by a fluorescence assay. With the results collected here, specific surface compositions are identified at which the orthogonal functions of water repellency and enzyme catalysis are balanced and exist simultaneously. An understanding of how to effectively balance orthogonal functions at surfaces can be extended to a number of higher-scale applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. The commercial development of water repellent coatings for high voltage transmission lines

    Energy Technology Data Exchange (ETDEWEB)

    Hunter, S. R. [ORNL; Daniel, A. [Southwire Company

    2013-10-31

    The purpose of the Cooperative Research and Development Agreement (CRADA) between UT-Battelle, LLC and Southwire Company was to jointly develop a low cost, commercially viable, water-repellant anti-icing coating system for high voltage transmission lines. Icing of power lines and other structures caused by freezing rain events occurs annually in the United States, and leads to severe and prolonged power outages. These outages cause untold economic and personal distress for many American families and businesses. Researchers at the Department of Energy?s Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee have previously developed a set of superhydrophobic coatings with remarkable anti-icing properties that could potentially be sprayed or painted onto high-tension power lines and pylons. These coatings drastically reduce ice accumulation on these structures during freezing rain events. The project involved obtaining technical input, supplies and test high voltage cables from Southwire, along with the joint development of anti-icing coating techniques, which would result in a commercial license agreement between Southwire and ORNL, and potentially other companies requiring water repellent anti-icing coatings.

  5. Do stones modify the spatial distribution of fire-induced soil water repellency? Preliminary data

    Directory of Open Access Journals (Sweden)

    J. García-Moreno

    2013-05-01

    Full Text Available Water repellency is a property of many fire-affected soils that contributes to delayed wetting rates and shows many hydrological and geomorphological consequences. Fire-induced soil water repellency (SWR may be modulated by pre-fire soil and vegetation properties. Many studies have been carried out to investigate the relationship between SWR and these properties. But, to our knowledge, no studies have considered the effect of surface stones in the spatial distribution of fire-induced SWR. In this research, we study the occurrence and spatial and vertical distribution of SWR and its consequences on soil structure after experimental burning in a previously wettable soil under different stone covers (0, 15, 30, 45 and 60%. In our experiment, burning induced critical or subcritical SWR in the upper millimetres of previously wettable soil. Fire-induced SWR did not vary with stone cover, but critical SWR was reached in inter-stone soil areas. At stone-covered soil areas, SWR was increased, but WDPTs remained mostly below the 5 s threshold.

  6. Enhancement of flame retardancy and water repellency properties of cotton fabrics using silanol based nano composites.

    Science.gov (United States)

    Mohamed, Amina L; El-Sheikh, Manal A; Waly, Ahmed I

    2014-02-15

    Environmental concerns related to fluorinated and organophosphorus compounds led to a consideration of the methods for imparting flame retardancy and water/oil repellency to textiles. A simple and facile method for fabricating the cotton fabric with superhydrophobicity and flame retardancy is described in the present work. Complex coating with amino-functionalized silica nano-particles on epoxy-functionalized cotton accompanied with ZnO nano-particles coating are carried out. In This context, new preparation techniques were used to prepare both aminated silica and ZnO nano-particles. The particle size was investigated using Transition Electron Microscope (TEM) and the chemical structure was investigated using FT-IR analysis and other analytical techniques. Cotton was functionalized with epoxy and carboxyl via grafting cotton with nano-emulsion consisted of mixture of glycidyl methacrylate (GMA) and acrylic acid (AA), and then treated for functional finishing through conventional pad-dry-cure method. The treated fabrics showed good water repellency and excellent flame retardant properties as determined by the standard test methods. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Impact of water repellency on infiltration of differently concentrated ethanol solutions

    Science.gov (United States)

    Dlapa, Pavel; Hrabovský, Andrej; Hriník, Dávid; Kuric, Peter

    2017-04-01

    Infiltration experiments were carried out on an extremely (WDPT > 3600 s) water repellent forest soil in the Little Carpathians Mts (SW Slovakia). Measurements were performed following a long dry warm period using the Mini Disk Infiltrometer (Decagon). Replicated infiltration experiments were conducted with water and five different ethanol solutions. The infiltrometer was set to a capillary pressure head of -2 cm and filled with solutions containing 0, 5, 10, 20, 40, and 95% of ethanol by volume, respectively. Solutions used in infiltration experiments differed in density, viscosity, and surface tension. Combined effect of solution properties on infiltration into soil is strongly dependent on soil surface properties. This may lead to a decrease of infiltration rate with increasing ethanol concentration. Such behaviour should be observable in wettable soils. However, the infiltration experiments revealed a significant increase in the rate of infiltration for increasing concentrations of ethanol. The solutions showed infiltration rates of 10-4, 10-3, and 10-2 cm/s for the 5, 20, and 95% ethanol solutions, respectively. This trend suggests the dominant influence of contact angle (affected by ethanol concentration) on infiltration process. Measurements allow quantifying changes of various infiltration parameters as a function of the solution properties. The obtained results showed that similar approach can be a valuable alternative to other methods used for the evaluation of severity of soil repellency and impacts to hydrological processes.

  8. The commercial development of water repellent coatings for high voltage transmission lines

    Energy Technology Data Exchange (ETDEWEB)

    Hunter, Scott Robert [ORNL

    2013-10-01

    The purpose of the Cooperative Research and Development Agreement (CRADA) between UT-Battelle, LLC and Southwire Company was to jointly develop a low cost, commercially viable, water-repellant anti-icing coating system for high voltage transmission lines. Icing of power lines and other structures caused by freezing rain events occurs annually in the United States, and leads to severe and prolonged power outages. These outages cause untold economic and personal distress for many American families and businesses. Researchers at the Department of Energy s Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee have previously developed a set of superhydrophobic coatings with remarkable anti-icing properties that could potentially be sprayed or painted onto high-tension power lines and pylons. These coatings drastically reduce ice accumulation on these structures during freezing rain events. The project involved obtaining technical input, supplies and test high voltage cables from Southwire, along with the joint development of anti-icing coating techniques, which would result in a commercial license agreement between Southwire and ORNL, and potentially other companies requiring water repellent anti-icing coatings.

  9. Linking hydraulic properties of fire-affected soils to infiltration and water repellency

    Science.gov (United States)

    Moody, J.A.; Kinner, D.A.; Ubeda, X.

    2009-01-01

    Heat from wildfires can produce a two-layer system composed of extremely dry soil covered by a layer of ash, which when subjected to rainfall, may produce extreme floods. To understand the soil physics controlling runoff for these initial conditions, we used a small, portable disk infiltrometer to measure two hydraulic properties: (1) near-saturated hydraulic conductivity, Kf and (2) sorptivity, S(??i), as a function of initial soil moisture content, ??i, ranging from extremely dry conditions (??i capillarity, and adsorption in a transitional domain corresponding to extremely dry soil, and moreover, it may explain the observed non-linear behavior, and the critical soil-moisture threshold of water repellent soils. Laboratory measurements of Kf and S(??i) are the first for ash and fire-affected soil, but additional measurements are needed of these hydraulic properties for in situ fire-affected soils. They provide insight into water repellency behavior and infiltration under extremely dry conditions. Most importantly, they indicate how existing rainfall-runoff models can be modified to accommodate a possible two-layer system in extremely dry conditions. These modified models can be used to predict floods from burned watersheds under these initial conditions.

  10. Water Repellence and Oxygen and Water Vapor Barrier of PVOH-Coated Substrates before and after Surface Esterification

    Directory of Open Access Journals (Sweden)

    Markus Schmid

    2014-11-01

    Full Text Available This study investigates chemical grafting with fatty acid chlorides as a method for the surface modification of hydrophilic web materials. The resulting changes in the water repellence and barrier properties were studied. For this purpose, different grades of polyvinyl alcohol (PVOH were coated on regenerated cellulose films (“cellophane” and paper and then grafted with fatty acid chlorides. The PVOH grades varied in their degree of hydrolysis and average molecular weight. The surface was esterified with two fatty acid chlorides, palmitoyl (C16 and stearoyl chloride (C18, by chemical grafting. The chemical grafting resulted in water-repellent surfaces and reduced water vapor transmission rates by a factor of almost 19. The impact of the surface modification was greater for a higher degree of hydrolysis of the polyvinyl alcohol and for shorter fatty acid chains. Although the water vapor barrier for palmitoyl-grafted PVOH was higher than for stearoyl-grafted PVOH, the contact angle with water was lower. Additionally, it was shown that a higher degree of hydrolysis led to higher water vapor barrier improvement factors after grafting. Furthermore, the oxygen permeability decreased after grafting significantly, due to the fact that the grafting protects the PVOH against humidity when the humidity is applied on the grafted side. It can be concluded that the carbon chain length of the fatty acid chlorides is the limiting factor for water vapor adsorption, but the grafting density is the bottleneck for water diffusing in the polymer.

  11. Relationships between soil water repellency and microbial community composition under different plant species in a Mediterranean semiarid forest

    Science.gov (United States)

    Lozano, Elena; García-Orenes, Fuensanta; Bárcenas-Moreno, Gema; Jiménez-Pinilla, Patricia; Mataix-Solera, Jorge; Arcenegui, Victoria; Morugán-Coronado, Alicia; Mataix-Beneyto, Jorge

    2014-05-01

    It is generally well accepted that soil water repellency (SWR) can greatly influence the hydrology and the ecology of the forest soils (Doerr et al., 2000). However, little is known whether SWR may influence the soil microbial community. Its appearance is mainly influence by many soil physic- chemical parameters like: SOM content and its quality, pH, moisture, texture etc. However, it might also be influence by the presence or activity of microorganisms. Early studies suggest that SWR might be caused by substances produced by the activity of certain fungi species (Savage et al., 1969). Soil WR is normally characterized by a high spatial variability in persistence, with wettable and water repellent patches (Lozano et al., 2013). Changes at the microsite scale (such as the presence of soil water repellent patches) might be reflected in the microbial community structure). In the current study we have analysed how SWR influence the microbial community in soil samples with a range of water repellency persistence under different plant species (P. halepensis, Q. rotundifolia, C. albidus and R officinalis) in a Mediterranean forest. The microbial community was determined through phospholipids fatty acids (PLFA). The relationships between microbiological community structure and other different soil properties like pH, Glomalin Related Soil Protein and Soil Organic Matter content were also studied. Different statistical analyses were used: Principal Component Analysis (PCA), ANOVA, Redundancy Analysis (RA) and Pearson correlations. The highest concentrations of PLFA were found in water repellent samples. PCA showed that microorganism composition was more dependent of the severity of SWR than the type of plant species. In the RA, SWR was the only significant factor (pMataix-Solera, J., Arcenegui, V., Bárcenas, G.M., González-Pérez, J.A., García-Orenes, F., Torres, M.P., Mataix-Beneyto, J., 2013. Biological and chemical factors controlling the patchy distribution of soil

  12. Fabrication of a silica aerogel and examination of its hydrophobic properties via contact angle and 3M water repellency tests

    Science.gov (United States)

    Mazrouei-Sebdani, Z.; Javazmi, L.; Khoddami, A.; Shams-Ghahfarokhi, F.; Low, T.

    2017-05-01

    Aerogels are dry gels with a very high specific pore volume. Aerogels with increased hydrophobicity have significant potential to expand their use as lightweight materials. Considering its special nanostructure and exceptional properties, this paper focuses on the synthesis and hydrophobic evaluation of a silica aerogel. The structural properties were investigated by measuring density, SEM micrographs, and BET analyses. Also, the hydrophobic evaluation was carried out by measuring 3M water repellency and water/alcohol contact angle. The BET analysis showed successful synthesis of the nanoporous silica aerogel with a pore size of 24 nm and porosity of 89%. The synthesized aerogel showed 3M water repellency of 3 and water contact angle of 129.6°. Also, it is worth-mentioning that as the alcohol content of the drops in 3M water repellency test is increased, the drop contact angle is decreased due to its lower surface tension. Thus, the contact angle reaches the zero at 3M water repellency test number of 4 (water/alcohol 60/40).

  13. Vegetation cover and land use impacts on soil water repellency in an Urban Park located in Vilnius, Lithuania

    Science.gov (United States)

    Pereira, Paulo; Cerda, Artemi

    2015-04-01

    It is strongly recognized that vegetation cover, land use have important impacts on the degree of soil water repellency (SWR). Soil water repellency is a natural property of soils, but can be induced by natural and anthropogenic disturbances as fire and soil tillage (Doerr et al., 2000; Urbanek et al., 2007; Mataix-Solera et al., 2014). Urban parks are areas where soils have a strong human impact, with implications on their hydrological properties. The aim of this work is to study the impact of different vegetations cover and urban soils impact on SWR and the relation to other soil variables as pH, Electrical Conductivity (EC) and soil organic matter (SOM) in an urban park. The study area is located in Vilnius city (54°.68' N, 25°.25' E). It was collected 15 soil samples under different vegetation cover as Pine (Pinus Sylvestris), Birch (Alnus glutinosa), Penduculate Oak (Quercus robur), Platanus (Platanus orientalis) and other human disturbed areas as forest trails and soils collected from human planted grass. Soils were taken to the laboratory, air-dried at room temperature and sieved with the 3600 (extremely water repellent). The results showed significant differences among the different vegetation cover (Kruskal-Wallis H=20.64, pgrass were significantly higher than Platanus soil. The soils from Pine, Birch, Penduculate Oak, forest trails and planted grass were majorly severely water repellent, while Platanus soils were mostly strong water repellent. Soil water repellency of Pine soils had a significant negative correlation with pH (-0.52, ppH (-0.88, ppH, EC and SOM. Acknowledgments POSTFIRE (Soil quality, erosion control and plant cover recovery under different post-fire management scenarios, CGL2013-47862-C2-1-R), funded by the Spanish Ministry of Economy and Competitiveness; Fuegored; RECARE (Preventing and Remediating Degradation of Soils in Europe Through Land Care, FP7-ENV-2013-TWO STAGE), funded by the European Commission; and for the COST action ES

  14. 拒水拒油剂FG-410对涤纶织物整理工艺探讨%Discussion on finishing technology of water-repellent and oil-repellent finishing agent FG-410 on polyester fabrics

    Institute of Scientific and Technical Information of China (English)

    王健; 江里友

    2011-01-01

    采用国产含氟拒水拒油整理剂FG-410,通过正交试验探讨了整理剂用量、交联剂用量、催化剂用量及焙烘温度等因素对拒水拒油整理效果的影响,优化工艺条件为:FG-410整理剂用量20g/L,FBA交联剂用量16g/L,催化剂MgCl2用量8g/L,155℃焙烘.整理后织物具有良好的拒水拒油性能及耐水洗性,且整理工艺对织物强力及透气性无明显影响.%Polyester fabrics were finished with homemade water-repellent and oil-repellent agent fluorinecontained FG-410.Through orthogonal test, the effects of the dosage of water-repellent and oil-repellent agent,the dosage of crosslinking agent and catalyst, and cure temperature on the properties of water-repellence and oil-repellence were investigated.The optimum technology conditions were as follows: 20 g/L of finishing agent FG-410, 16 g/L of crosslinking agent FBA, 8 g/L of catalyst MgC12, cured at 155 ℃.The finished fabric showed superior water-repellent and oil-repellent properties and durable laundries.And the finishing had unobvious change on the broken strength and the air permeability of the fabrics.

  15. Influence of organic manure amendments on water repellency, water entry value, and water retention of soil samples from a tropical Ultisol

    Directory of Open Access Journals (Sweden)

    Liyanage T.D.P.

    2016-06-01

    Full Text Available Lowered stability of soil aggregates governed by insufficient organic matter levels has become a major concern in Sri Lanka. Although the use of organic manure with water repellent properties lowers the wetting rates and improves the stability of soil aggregates, its effects on soil hydrophysical properties are still not characterized. Therefore, the objective of this study was to examine the relation of water repellency induced by organic manure amendments to the water entry value and water retention of a Sri Lankan Ultisol. The soil was mixed with ground powders of cattle manure (CM, goat manure (GM, Gliricidia maculata (GL and hydrophobic Casuarina equisetifolia (CE leaves to obtain samples ranging from non-repellent to extremely water repellent, in two series. Series I was prepared by mixing GL and CE with soil (5, 10, 25, 50%. Series II consisted of 5% CM, GM, and GL, with (set A and without (set B intermixed 2% CE. Water repellency, water entry value, and water retention of samples were determined in the laboratory. Soil-water contact angle increased with increasing organic matter content in all the samples showing positive linear correlations. Although the samples amended with CE showed high soil-water contact angles in series I, set A (without 2% CE and set B (with 2% CE in series II did not show a noticeable difference, where >80% of the samples had soil-water contact angles <90°. Water entry value (R2 = 0.83–0.92 and the water retention at 150 cm suction (R2 = 0.69–0.8 of all the samples increased with increasing soil-water contact angles showing moderate to strong positive linear correlations. However, set A (without 2% CE and set B (with 2% CE in series II did not differ noticeably. Water entry value of about 60% the samples was <2.5 cm. Mixing of a small amount (2% of hydrophobic organic matter with commonly used organic manures slightly increased the water repellency of sample soils, however not up to detrimental levels. It

  16. 'Natural background' soil water repellency in conifer forests of the north-western USA: Its prediction and relationship to wildfire occurrence

    Science.gov (United States)

    Doerr, S.H.; Woods, S.W.; Martin, D.A.; Casimiro, M.

    2009-01-01

    Soils under a wide range of vegetation types exhibit water repellency following the passage of a fire. This is viewed by many as one of the main causes for accelerated post-fire runoff and soil erosion and it has often been assumed that strong soil water repellency present after wildfire is fire-induced. However, high levels of repellency have also been reported under vegetation types not affected by fire, and the question arises to what degree the water repellency observed at burnt sites actually results from fire. This study aimed at determining 'natural background' water repellency in common coniferous forest types in the north-western USA. Mature or semi-mature coniferous forest sites (n = 81), which showed no evidence of recent fires and had at least some needle cast cover, were sampled across six states. After careful removal of litter and duff at each site, soil water repellency was examined in situ at the mineral soil surface using the Water Drop Penetration Time (WDPT) method for three sub-sites, followed by collecting near-surface mineral soil layer samples (0-3 cm depth). Following air-drying, samples were further analyzed for repellency using WDPT and contact angle (??sl) measurements. Amongst other variables examined were dominant tree type, ground vegetation, litter and duff layer depth, slope angle and aspect, elevation, geology, and soil texture, organic carbon content and pH. 'Natural background' water repellency (WDPT > 5 s) was detected in situ and on air-dry samples at 75% of all sites examined irrespective of dominant tree species (Pinus ponderosa, Pinus contorta, Picea engelmanii and Pseudotsuga menziesii). These findings demonstrate that the soil water repellency commonly observed in these forest types following burning is not necessarily the result of recent fire but can instead be a natural characteristic. The notion of a low background water repellency being typical for long-unburnt conifer forest soils of the north-western USA is

  17. Recurring fingered flow pathways in a water repellent sandy field soil

    Directory of Open Access Journals (Sweden)

    C. J. Ritsema

    1997-01-01

    Full Text Available Field evidence of finger formation and reformation during Successive rain events over an eight months' observation period from June 1994 until January 1995 is presented. Fingered flow pathways were monitored in a no-tilled, grass-covered water repellent sandy field soil using an automated, stand-alone TDR device. Within a 2 m long and 0.7 m deep transect, 98 three-wire probes were installed horizontally at depths of 4, 12, 20, 30, 40, 55, and 70 cm. The horizontal distance between two adjacent probes was IS cm. Finger formation occurred during distinct rainy periods and was most pronounced under heavy rainfall with initially wet topsoil conditions. The percentage of water infiltrated and transported preferentially through the fingers to the deep subsoil varied between 0 and 80%, depending on the wetting history of the soil and the rainfall characteristics.

  18. Influence of Long-term Application of Feedlot Manure Amendments on Water Repellency of a Clay Loam Soil.

    Science.gov (United States)

    Miller, Jim J; Beasley, Bruce W; Hazendonk, Paul; Drury, Craig F; Chanasyk, David S

    2017-05-01

    Long-term application of feedlot manure to cropland may increase the quantity of soil organic carbon (C) and change its quality, which may influence soil water repellency. The objective was to determine the influence of feedlot manure type (stockpiled vs. composted), bedding material (straw [ST] vs. woodchips [WD]), and application rate (13, 39, or 77 Mg ha) on repellency of a clay loam soil after 17 annual applications. The repellency was determined on all 14 treatments using the water repellency index ( index), the water drop penetration time (WDPT) method, and molarity of ethanol (MED) test. The C composition of particulate organic matter in soil of five selected treatments after 16 annual applications was also determined using C nuclear magnetic resonance-direct polarization with magic-angle spinning (NMR-DPMAS). Manure type had no significant ( > 0.05) effect on index and WDPT, and MED classification was similar. Mean index and WDPT values were significantly greater and MED classification more hydrophobic for WD than ST. Application rate had no effect on the index, but WDPT was significantly greater and MED classification more hydrophobic with increasing application rate. Strong ( > 0.7) but nonsignificant positive correlations were found between index and WDPT versus hydrophobic (alkyl + aromatic) C, lignin at 74 ppm (O-alkyl), and unspecified aromatic compounds at 144 ppm. Specific aromatic compounds also contributed more to repellency than alkyl, O-alkyl, and carbonyl compounds. Overall, all three methods consistently showed that repellency was greater for WD- than ST-amended clay loam soil, but manure type had no effect. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  19. Linking hydraulic properties of fire-affected soils to infiltration and water repellency

    Science.gov (United States)

    Moody, John A.; David Kinner,; Xavier Úbeda,

    2009-01-01

    Heat from wildfires can produce a two-layer system composed of extremely dry soil covered by a layer of ash, which when subjected to rainfall, may produce extreme floods. To understand the soil physics controlling runoff for these initial conditions, we used a small, portable disk infiltrometer to measure two hydraulic properties: (1) near-saturated hydraulic conductivity, Kf and (2) sorptivity, S(θi), as a function of initial soil moisture content, θi, ranging from extremely dry conditions (θi water repellency that influences Kf and S(θi).Values of Kf ranged from 4.5 × 10−3 to 53 × 10−3 cm s−1 for ash; from 0.93 × 10−3 to 130 × 10−3 cm s−1 for reference soils; and from 0.86 × 10−3 to 3.0 × 10−3 cm s−1, for soil unaffected by fire, which had the lowest values of Kf. Measurements indicated that S(θi) could be represented by an empirical non-linear function of θi with a sorptivity maximum of 0.18–0.20 cm s−0.5, between 0.03 and 0.08 cm3 cm−3. This functional form differs from the monotonically decreasing non-linear functions often used to represent S(θi) for rainfall–runoff modeling. The sorptivity maximum may represent the combined effects of gravity, capillarity, and adsorption in a transitional domain corresponding to extremely dry soil, and moreover, it may explain the observed non-linear behavior, and the critical soil-moisture threshold of water repellent soils. Laboratory measurements of Kf and S(θi) are the first for ash and fire-affected soil, but additional measurements are needed of these hydraulic properties for in situ fire-affected soils. They provide insight into water repellency behavior and infiltration under extremely dry conditions. Most importantly, they indicate how existing rainfall–runoff models can be modified to accommodate a possible two-layer system in extremely dry conditions. These modified models can be used to predict floods from burned watersheds

  20. Effects of Revolution on soil wetting, turf performance and nitrogen efficiency of a fairway prone to soil water repellency

    NARCIS (Netherlands)

    Oostindie, K.; Dekker, L.W.; Geissen, V.; Ritsema, C.J.

    2013-01-01

    This study reports on the effects of applications of the surfactant Revolution on soil wetting and turf performance of fairway 10 of the Rosendaelsche Golfclub, located near Arnhem, The Netherlands. In addition, the influence of Revolution on soil water repellency and the nitrogen contents in grass

  1. Influence of burning intensity on water repellency and hydrological processes at forest and shrub sites in Portugal

    NARCIS (Netherlands)

    Ferreira, A.J.D.; Coelho, C.O.A.; Boulet, A.K.; Leighton-Boyce, G.; Keizer, J.J.; Ritsema, C.J.

    2005-01-01

    In addition to the incineration of vegetation and litter layer, fires are also responsible for the formation of a water repellent layer with significantly different severity and spatial distribution patterns following different burning intensities. Those spatial distribution patterns have an enormou

  2. Small variations of soil properties control fire-induced water repellency

    Directory of Open Access Journals (Sweden)

    Jorge Mataix-Solera

    2014-03-01

    Full Text Available Fire induced soil water repellency (WR is controlled by many different factors (temperature reached, amount and type of fuel, etc.. Soil properties may determine the occurrence and intensity of this property in burned soils. The objectives of this paper are to make advances in the study of soil properties as key factors controlling the behaviour of fire-induced WR, and to study the impact of pre-fire SOM content and SOM quality in fire-induced soil WR. In this research, experimental laboratory burnings were carried out using soil samples from different sites with different lithologies, soil types and plant species. Soil samples taken from the same site differ only in quantity and quality of soil organic matter, as they were collected from under different plant species. All soil samples were heated in a muffle furnace at 200, 250, 300 and 350 ºC without the addition of any fuel load. WR was measured using the water drop penetration time test (WDPT. The results showed significant differences between soil types and plant species, indicating that small differences in soil properties may act as key factors controlling the development and persistence of WR reached, with burned soil samples ranging from wettable to extremely water repellent. The main soil property controlling the response was texture, specifically sand content. The quality of organic matter was also observed to have an effect, since soil samples from the same site with similar organic matter contents, but taken from beneath different plant species, showed different WR values after burning.

  3. Organic compounds characteristics associated with heat-induced increases of water repellency in Australian eucalypt forest soils

    Science.gov (United States)

    Atanassova, Irena; Doerr, Stefan H.

    2010-05-01

    Ground surface heating during wildfires often leads to increased water repellency in soils. The effect of elevated soil temperature on water repellency has been investigated in many laboratory-based studies and temperature thresholds for increases in, and destruction of, water repellency have been established. However, little is known about the changes in organic compounds patterns and their chemical structure that associated with these changes. Here we report on the characterisation of the chemical changes of organic compounds associated with heat-induced increases in water repellency in Eucalypt soils of different repellency levels. Fires are very common in eucalypt forest environments and soils under eucalypt species exhibit one of the most severe repellency levels, providing an ideal study case. Three SE Australian eucalypt forest soils from different locations (two sands and one sandy loam) were heated in the laboratory for 10 min at 300° C. Laboratory heating resulted in extreme repellency in the three soils studied. Heated and unheated control samples were then extracted by accelerated solvent extraction (ASE) with iso-propanol/ammonia mixture (IPA/NH3 95:5). Extraction led to the elimination of any water repellency present both in the original (heated) and the control samples. Organic compounds in the IPA/NH3 solvent were measured in extracts of increasing polarity in order to solubilise the residue. Before heating, the total solvent extracts from the soils with sandy texture were dominated by n-alkanols, terpenoids, C16 acid, C29 alkane, β-sitosterol and polar compounds such as glycerol, monosaccharides and glycosides. Fatty acids with chain length over C20 were detected in the sandy soils, while the soil of heavier texture (sandy loam) lacked longer than C20 fatty acids and had lower concentrations of alkanols (exceeding C26 chain lenght) and alkanes (C29, C31). Alkane patterns were characterized by the predominance of C21 - C31 homologues with a

  4. STATIC BENDING STRENGHT OF WOOD TREATED WITH FIRE RETERDANT AND WATER REPELLENT PRESERVATION CHEMICALS

    Directory of Open Access Journals (Sweden)

    Hüseyin PEKER

    1999-01-01

    Full Text Available This study has designed for determination of static bending strenght of mainly boron impregnated scots pine and east beech wood. Other chemicals used as control are polyethylene glycole (PEG-400 and some commercial preservatives such as Vacsol (V, Ammonıum sulphate (AS and Diammonium phospate (DAP were used by secondary process on the boron or PEG treated wood by the aim of improving static bending strenght and avoiding the leachability of both chemicals. Result indicated that static bending strenght of scots pine wood were reduced by acidic solutions of salts. In beech wood static bending strenght were also affected by neutral pH of the solution. Water repellent , surprisingly don't show their aspected protective properties of static bending strength, in general .

  5. Broadband anti-reflective and water-repellent coatings on glass substrates for self-cleaning photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiaoyu [Functional Nanomaterials Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry (TIPC), Chinese Academy of Sciences, Zhongguancun Donglu 29, Haidianqu, Beijing 100190 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); He, Junhui, E-mail: jhhe@mail.ipc.ac.cn [Functional Nanomaterials Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry (TIPC), Chinese Academy of Sciences, Zhongguancun Donglu 29, Haidianqu, Beijing 100190 (China); Liu, Weiyi [Institute of Optoelectronics, Nankai University, Tianjin 300071 (China)

    2013-07-15

    Graphical abstract: High performance broadband antireflective and water-repellent coatings were fabricated on glass substrates, which can improve the short-circuit current of solar cells as much as 6.6% in comparison with glass substrates without the coatings. - Highlights: • Broadband anti-reflective and water-repellent coatings were fabricated. • Transmittance increased to 99.0%, significantly higher than that of commercial solar glasses. • The performance of standard solar cells with the AR coating was enhanced as much as 6.6%. - Abstract: High performance broadband antireflective (AR) and water-repellent coatings were fabricated on glass substrates by assembly of silica nanoparticles and polyelectrolytes via the layer-by-layer (LbL) assembly technique, followed by calcination and hydrophobic modification. A porous poly(diallyladimethylammonium chloride) (PDDA)/20 nm SiO{sub 2} nanoparticles (S-20) multilayer coating with AR property was prepared first. The maximum transmittance is as high as 99.0%, while that of the glass substrate is only 91.3%. After calcination and hydrophobic modification, the coating became water-repellent while maintaining the good AR property. Such water-repellent AR coatings can improve the short-circuit current of solar cells as much as 6.6% in comparison with glass substrates without the coatings. Scanning electron microscopy (SEM) was used to observe the morphology and thickness of coatings. Transmission spectra and reflection spectra were characterized by UV–vis spectrophotometer. The surface wettability was studied by a contact angle/interface system.

  6. Geochemical indicators and characterization of soil water repellence in three dominant ecosystems of Western Australia

    Science.gov (United States)

    Muñoz-Rojas, Miriam; Jiménez-Morillo, Nicasio T.; Jordan, Antonio; Zavala, Lorena M.; Stevens, Jason; González-Pérez, Jose Antonio

    2016-04-01

    Introduction Soil water repellency (SWR) has critical implications for restoration of vegetation in degraded areas as it is responsible of poor plant establishment and a high incidence of erosion processes. Different organic substances are capable of inducing SWR but polar molecules such as certain fatty acids, and waxes i.e. esters and salts of fatty acids, appear to be the main constituents of hydrophobic coatings on soil mineral particles (Doerr et al., 2005). Plant species most commonly associated with SWR are evergreen trees with a considerable amount of resins, waxes or aromatic oils such as eucalypts and pines. Most of these substances are abundant in ecosystems and are released to soil by plants as root exudates or decaying organic debris, and by soil fauna, fungi and other microorganisms, but a thorough knowledge of substances capable of inducing hydrophobicity in soils is still not complete (Jordan et al., 2013). Although SWR has been reported in most continents of the world for different soil types, climate conditions and land uses, there are still many research gaps in this area, particularly in semi-arid areas largely affected by this phenomenon. Materials and methods This research was conducted in three dominant ecosystems of Western Australia (WA), e.g. semi-arid grassland in the Pilbara region (North WA), Banksia woodland, and a coastal dune (both located in South WA). These environments have different climate characteristics and soil types but similar vegetation communities. Soil samples were collected under the canopy of a broad range of plant species that compose the dominant vegetation communities of these ecosystems, and SWR was measured under lab conditions in oven-dry samples (48 h, 105 °C). Soil microbial activity was measured with the 1-day CO2 test, a cost-effective and rapid method to determine soil microbial respiration rate based on the measurement of the CO2 burst produced after moistening dry soil (Muñoz-Rojas et al., 2016). Soil p

  7. Optical and water repellant properties of Ag/SnO2 bilayer thin films

    Directory of Open Access Journals (Sweden)

    Ravipati Praveena

    2016-02-01

    Full Text Available The optical and water repellant properties of single layer and bilayer films of Ag and SnO2 deposited on glass substrates by thermal evaporation have been reported. Ag/SnO2 bilayers were deposited in two sequences wherein the deposition of SnO2 layer was followed by Ag deposition and vice versa. X-ray diffraction studies show that the Ag films crystallize in the FCC structure and SnO2 is amorphous, while atomic force microscopy images indicate the formation of large clusters of the order of 12 nm. The single layer Ag films exhibit localized surface plasmon resonance (LSPR that shifts from visible region to the infrared with increase in thickness from 5 to 12 nm. It is observed that, only the Ag films of thickness ≤ 8 nm exhibits LSPR peak whereas the critical thickness is 5 nm for Ag/SnO2 films. A blue shift is observed in the LSPR peak position when the SnO2 layer caps the Ag film. Whereas, the LSPR of Ag is suppressed significantly when the SnO2 layer is introduced between the glass and the Ag film and also when Ag and SnO2 were co-evaporated. Water repellant properties indicate that the pure Ag film has an average contact angle of 104o which decreases to 100o when SnO2 caps the Ag layer and 97o when Ag is deposited on top of the SnO2 buffer layer. Co-evaporated Ag-SnO2 films show a contact angle of 93o.

  8. A sequential extraction and hydrolysis approach to understand the chemical nature of soil water repellency

    Science.gov (United States)

    Mao, Jiefei; Dekker, Stefan C.; Nierop, Klaas G. J.

    2014-05-01

    Soil water repellency (SWR) biomarkers (SWR-biomarkers) are defined as hydrophobic organic compounds in soils causing SWR and originating from vegetation or microbes (Doerr et al., 2000). Free lipids and ester-bound biopolymers (cutins and suberins) are usually seen in the aliphatic part of soil organic matter (SOM) (Nierop, 1998). The method of sequential extraction can divide hydrophobic compounds into individual fractions with different characteristics. We aim to find out the SWR-biomarkers in soils within different fractions, investigate the effects of fractions on SWR and link them to their original sources. To extract free and ester-bound lipids from sandy soils, DCM (dichloromethane)/MeOH (methanol) and IPA(isopropanol)/NH3 were used in sequential steps. As a result, three fractions were obtained during these sequential experiments: a DCM/MeOH soluble fraction (D), a DCM-MeOH soluble (AS) fraction of IPA/NH3 extracts and its insoluble (AI) fraction. To date, research was limited to (organic) extractable fractions only. To investigate the DCM-MeOH insoluble part of IPA/NH3 extracts they were depolymerised by trans-methylation using BF3-MeOH. All fractions were analysed by gas chromatography-mass spectrometry. After DCM/MeOH extraction, water repellency of 80% of the soils studied increased while SWR of the other soils remained at the same level. Straight-chain fatty acids, alcohols and alkanes were the main compound groups in the D fractions. The distribution of fatty acids (C20-C32) and alcohols (C20-C32), both of which with an even-over-odd predominance suggest their source were higher plants, and so did the odd-over-even predominated alkanes. After extraction by IPA/NH3 , most soils became non-repellent. Both fatty acids (C16-C32) and alcohols (C16-C30) with an even-over-odd predominance were also found in the AS fractions, whereas no alkanes were detected. There were four main component groups identified in the AI fractions: fatty acids, alcohols,

  9. Fabrication of superhydrophobic silicone rubber by ArF-excimer-laser-induced microstructuring for repelling water in water

    Science.gov (United States)

    Okoshi, Masayuki; Setyo Pambudi, Wisnu

    2016-11-01

    Microswellings of 1 µm height, 1.5 µm diameter, and regular intervals of 2.5 µm on a silicone rubber surface were fabricated using a 193 nm ArF excimer laser. The laser was focused on silicone by each microsphere made of silica glass of 2.5 µm diameter; these microspheres covered the entire surface of the silicone. The surface underneath each microsphere selectively swelled owing to the photodissociation of the Si-O bonds of silicone. The contact angle of water was measured to be approximately 155°, indicating a clear superhydrophobicity. The samples successfully repelled water in water to form an air gap layer between silicone and water.

  10. Evaluation of consolidating and water repellent treatments applied to the miocene sandstone used in Tunisian Heritage Monuments

    Directory of Open Access Journals (Sweden)

    Zoghlami, K.

    2005-03-01

    Full Text Available Summary The research reported in the present paper focused on the behaviour of the Miocene sandstone used to build the Roman aqueduct at Zaghouan-Carthage and other Tunisian Heritage monuments, after application of water repellent and consolidating treatments as a preliminary to restoration. Commercial consolidants and water repellents were used in the experiments: two ethyl silicate consolidants, Tegovakon (TV and Keim-Silex OH (KSOH; two (siloxane water repellents, Tegosivin THE 328 (THE and Tegosivin HLJ00 (THE; and a dual (consolidate and water repellent action substance, Keim- Silex H (KSH (silicate acid ester base with siloxane. A mixed treatment consisting of successive coats of TV and THL (TVHL was also applied. These organosilicate consolidants and water repellents acted on the porous structure of the sandstone, reducing total porosity and water vapour permeability. The water repellent THE was found to affect these properties least, with a pore size distribution that resembled the distribution in the untreated sandstone most closely. Water repellents diminish water absorption and consolidants increase mechanical strength. The TV-THL mix, which yielded results similar to those obtained with water repellents alone, was unable to prevent the substantial scaling that occurs during (RILEM salt crystallisation-induced artificial ageing. The best results were found with the dual action consolidant! water repellent product (KSH, which improved the mechanical properties while affording protection from the decay caused by salts in artificial ageing trials. This substance was found to reduce water vapour permeability, however

    Esta investigación se centra en la evaluación del comportamiento de la arenisca miocénica utilizada en el acueducto de Zaghouan-Cartago y otros monumentos del Patrimonio Monumental de Túnez tras la aplicación de tratamientos de hidrofugación y de consolidación. Para los tratamientos se han seleccionado productos

  11. Transparent ultra water-repellent poly(ethylene terephthalate) substrates fabricated by oxygen plasma treatment and subsequent hydrophobic coating

    Science.gov (United States)

    Teshima, Katsuya; Sugimura, Hiroyuki; Inoue, Yasushi; Takai, Osamu; Takano, Atsushi

    2005-05-01

    Wettability of solid surfaces with water is well-known to be governed by chemical properties and nanotextures of the surfaces. A proper nanotexture of surfaces enhances their hydrophobicity. In this study, a novel method consisting of two dry process techniques, that is, nanotexturing by an oxygen plasma treatment and subsequent hydrophobic coating by means of low temperature chemical vapor deposition or plasma-enhanced chemical vapor deposition, was employed to form ultra water-repellent polymer sheets. A nanotexture was formed on a poly(ethylene terephthalate) substrate surface via selective oxygen plasma etching. This surface nanotexture remained after the hydrophobic coatings using organosilane precursors. The surface-modified substrate was transparent and ultra water-repellent, showing a water contact angle greater than 150°.

  12. Factors responsible for the patchy distribution of natural soil water repellency in Mediterranean semiarid forest

    Science.gov (United States)

    Lozano, E.; Jiménez-Pinilla, P.; Mataix-Solera, J.; González-Pérez, J. A.; García-Orenes, F.; Torres, M. P.; Arcenegui, V.; Mataix-Beneyto, J.

    2012-04-01

    Soil water repellency (WR) is commonly observed in forest areas showing wettable and water repellent patches with high spatial variability. This has important hydrological implications; in semiarid areas where water supply is limited, even slight WR may play an important role in infiltration patterns and distribution of water into the soil (Mataix-Solera et al., 2007). It has been proposed that the origin of WR is the release of organic compounds from different plants species and sources (due to waxes and other organic substances in their tissues; Doerr et al., 1998). However, the relationship between WR and plants may not always be a direct one: a group of fungi (mainly mycorrhizal fungi) and microorganisms could be also responsible for WR. The aim of this research is to study the relationships between WR in soils under different plant cover with selected soil properties and the quantity of fungi and their exudates. The study area is located in Southeast Spain, "Sierra de la Taja" near Pinoso (Alicante)), with a semiarid Mediterranean climate (Pm=260mm). Samples were taken in September 2011, when WR is normally strongest after summer drought. Soil samples were collected from the first 2.5cm of the mineral A horizon at microsites beneath each of the four most representative species (Pinus halepensis, Rosmarinus officinalis, Quercus. rotundifolia and Cistus albidus; n=15 per specie) and 5 samples from bare soil with no influence of any species. Different soil parameters were analyzed; water content, soil organic mater content (SOM), pH, WR, easily extractable glomalin (EEG), total mycelium and extractable lipids. The occurrence of WR was higher under P. halepensis (87% of samples) and Q. rotundifolia (60% of samples). Positive significant correlations were found between WR and SOM content for all species, with the best correlations for Pinus and Quercus (r=0.855**, r= 0.934** respectively). In addition, negative significant correlations were found between WR and p

  13. Analysis of soil water repellency under different eco-geomorphological conditions in Mediterranean environments (South of Spain)

    Science.gov (United States)

    Jimenez-Donaire, Virginia; Gabarron-Galeote, Miguel A.; Martinez-Murillo, Juan F.; Ruiz-Sinoga, Jose D.

    2013-04-01

    Soil water repellency (SWR) is a soil property that reduces its water affinity. Although it has been frequently related to wildfires, different studies in recent decades have shown that repellent soils are not rare, and they are widely spread around the world under various climatic, soil and vegetation conditions, on burned and unburned soils. The research described here was carried out in two Mediterranean rangelands containing similar Mediterranean tree and shrub species but differing in soil conditions. The aim of the study was to evaluate the effects of vegetal species, pH, soil organic matter (SOM), soil water content (SWC) and prescribed fire over SWR. In June 2011, two samples from the first 5 cm of soil, one up and one downslope from plants, were collected under the dominant species of the two study areas (Nerja -NE- and Almogía -AL-), in a north-facing hillslope . In NE the selected species were Pinus halepensis (Ph), Cistus clusii (Cc), Rosmarinus officinalis (Ro), Thymus vulgaris (Tv) and Stipa tenacissima (St). In addition samples were collected in bare soil (Bs, at least 1.5m far away from the nearest shrub), under burned shrubs (Bsc) and in burned bare soil (Bbs). A controlled fire was conducted in April 2011. In AL the selected species were Quercus suber (Qs), Cistus monspeliensis (Cm) and Cistus albidus (Ca). The results indicate: i) SWR is a common phenomenon in Mediterranean environments, in acid as well as in alkaline soils, but with a great variability in every study area depending on the vegetal species (Ro and Qs) were those more repellent to water; ii) OM seems to be a more influential factor over soil water repellency than acidity, which only was found a controlling factor for alkaline soils; iii climate and vegetation type, influencing SOM leading to hydrophobic conditions, are more key factors controlling SWR than bedrock characteristics; iv) SWC threshold for water repellency to be disappeared were not clearly stated independently of

  14. Evaluation of Water Repellency in Petroleum Drilling Cuttings Treated by Thermal Desorption: Implications for Use in Construction and Agriculture

    Science.gov (United States)

    Domínguez-Rodríguez, Verónica I.; Guzmán-Osorio, Francisco J.; Adams Schroeder, Randy H.; Bautista-Margulis, Raúl G.

    2010-05-01

    Thermal desorption is one of many methods used for the remediation of hydrocarbon contaminated soils and similar materials. It has several advantages over competing technologies, especially with respect to treatment times. While the biological treatment of contaminated soils may take several months depending principally on the type of hydrocarbons and starting concentration, thermal desorption typically takes less than one month, depending on the treatment capacities of the equipment involved, and the volume of material requiring treatment. In the petroleum producing region of southeastern Mexico, this has been one of the principal methods used for the treatment of drilling cuttings, due mostly to the short time required. As with most remediation projects, as well as in the treatment of exploration and production (E&P) wastes, the criteria used to consider the remediation finalized is the concentration of hydrocarbons in the treated material. This is based on the supposition that at some (relatively low) hydrocarbon concentration, the toxicological affects are reduced to acceptable levels. However, little attention has been paid to the physical-chemical properties of supposedly treated material, which may suffer from water repellency, especially in thermal treatment methods. This could greatly reduce the options for final use of treated materials, especially to support plant growth. Conversely, there may be some construction uses of treated material in which some water repellence could be beneficial (caps for land fills, for example). Considering the relevance of the physical-chemical impacts of petroleum on soil and similar materials, we felt it was important to evaluate the efficiency of the principal method used to treat E&P wastes in Mexico (thermal desporption) based on these factors. In this study different operating conditions (temperature and residence time) of a sub-pilot scale thermal desorption unit were evaluated with respect not only to reduction in

  15. Rock fragments induce patchy distribution of soil water repellency in burned soils

    Science.gov (United States)

    Gordillo-Rivero, Ángel; García-Moreno, Jorge; Bárcenas-Moreno, Gema; Jiménez-Morillo, Nicasio T.; Mataix-Solera, Jorge; Jordán, Antonio; Zavala, Lorena M.

    2013-04-01

    Forest fires are recurrent phenomena in the Mediterranean area and are one of the main causes of changes in the Mediterranean ecosystems, increasing the risk of soil erosion and desertification. Fire is an important agent which can induce important changes in the chemical and physical characteristics of soils. During wildfires, only a small part of the heat generated is transmitted to the first centimetres of the soil profile. The intensity of the changes produced in the physical and chemical characteristics of the soil depends on the temperatures reached at different soil depths, the time of residence of temperature peaks, and the stability of the different soil components. One of the soil physical properties strongly affected by fire is soil water repellency (WR). Depending on temperature, time of heating, type of soil and fuel, fire can induce, enhance or destroy soil WR. Soil WR is a key factor in controlling soil hydrology and water availability in burnt soils together with other factors as texture or aggregation. Although the occurrence and consequences of fire-induced soil WR have been deeply studied, some gaps still exist, as the influence of rock fragment cover during burning. During combustion of litter and aerial biomass, the soil surface under rock fragments is heated and reachs temperature peaks after a certain delay respect to exposed areas. In contrast, temperature peaks are longer, increasing the time of residence of high temperature. In consequence, rock fragments may change the expected spatial distribution of soil WR. Up to date, very scarce research concerns the effect of rock fragments at the soil surface on the fire-induced pattern of soil water repellency. METHODS Two experiments were carried out in this research. In the first case, an experiment was conducted in an experimental farm in Sevilla (southern Spain). The effect of a low severity prescribed fire was studied in soil plots under different rock fragment covers (0, 15, 30, 45 and 60

  16. Water repellency and infiltration of biological soil crusts on an arid and a temperate dunes

    Science.gov (United States)

    Fischer, Thomas; Yair, Aaron; Geppert, Helmut; Veste, Maik

    2014-05-01

    Biological soil crusts (BSCs) play an important role in many ecosystems and in all climates. We studies hydrological properties of BSCs under arid and temperate climates. The arid study site was located near Nizzana, in the northwestern Negev, Israel and the temperate site was near Lieberose, Brandenburg, Germany. BSCs were sampled at each site near the dune crest, at the center of the dune slope and at the dune base. Using principal component analysis (PCA), we studied the relationships between hydraulic properties and the molecular structure of organic matter using repellency indices, microinfiltrometry, and 13C-CP/MAS-NMR. The soil texture was finer and water holding capacities (WHCs) were higher in Nizzana, whereas surface wettability was reduced in Lieberose. At both sites, BSCs caused extra WHC compared to the mineral substrate. Infiltration after wetting along both catenas generally reached a maximum after 10 min and decreased after 30 min. Carbohydrates were the dominating components in all of the BSCs studied, where the relative peak areas of carbohydrate-derived structures (60-110 ppm) amounted to 28-46% and to 10-14% of total C-peak areas, respectively. PCA revealed that the WHC of the substrate was closely related to the amount of silt and clay, whereas the BSC induced extra WHC was closely related to carbohydrates. It was further found that water repellency was positively related to carbohydrate C, but negatively related to alkyl C. Infiltration kinetics was attributed to polysaccharide hydration and swelling. Our findings support the hypothesis that hydraulic properties of BSCs are determined by extracellular polymeric substances (EPS) and soil texture. Hydraulic properties in BSCs result from the combination of chemical properties related to C compounds mainly dominated by carbohydrates and physical surface properties related to texture, porosity and water holding capacity. References Fischer, T., Yair, A., Veste, M., Geppert, H. (2013) Hydraulic

  17. Impact of a prescribed fire on soil water repellency in a Banksia woodland (Western Australia)

    Science.gov (United States)

    Muñoz-Rojas, Miriam; Miller, Ben; Tangney, Ryan; Miller, Russell; González-Pérez, José A.; Jiménez-Morillo, Nicasio T.; Zavala, Lorena M.; Jordán, Antonio

    2016-04-01

    INTRODUCTION The Swan Coastal plain of Western Australia is dominated by fire-prone banksia woodland (Burrows and McCaw, 1990). In these areas, prescription burning is often used to reduce the risk of wildfires, by reducing available fuels (Boer et al., 2009). Little research has been conducted on the effects of prescription burning on Banksia woodlands, and, in particular, information on the impacts on soil properties and soil water repellency (SWR) is scarce. Here, we have studied the impact of fire on SWR in a Banksia woodland and monitored its evolution in the medium-term. It is expected that results are useful for management and restoration of fire-affected Banksia woodlands. METHODS An experimental fire was conducted on May 7th 2015 in Kings Park, Perth, Western Australia. The fire affected an area of 6 ha of mixed Banksia/Allocasuarina woodland under moderate fire intensity. At the time of ignition, the wind speed below the canopy was 1.2 km/h. During the prescribed burning, air temperatures were on average 20 ± 1 °C and relative humidity ranged between 45 and 55% (measured using a Kestrel portable weather station). Fuel moisture averaged 11.8% (measured using Wiltronics moisture meter) and soil moisture at 1 cm deep ranged from 0.1% to 8.6% (measured with a PR2 soil profile probe attached to a HH2 data logger). Temperatures greater than 120 °C were measured 1 cm below the soil surface using iButton temperature sensors. SWR was measured under lab conditions in oven-dry samples (48 h, 105 °C) with the water drop penetration time (WDPT) test. Soil microbial activity was determined with the 1-day CO2 test that is based on the measurement of the CO2 burst produced after moistening dry soil (Muñoz-Rojas et al., 2016). PRELIMINARY RESULTS AND DISCUSSION SWR was severe in the control (mean WDPT = 2608 s) and pre-burned areas (2722 s). One week after the prescribed fire, persistence of soil water repellency remained stable in the burned area (2402 s). In

  18. Antecedent rainfall effects on the annual variability of water repellency in a patchy-vegetated Mediterranean hillslope (Almogía experimental field site, Southern Spain)

    Science.gov (United States)

    Damian Ruiz Sinoga, Jose; Francisco Martinez Murillo, Juan; Gabarron Galeote, Miguel Angel

    2010-05-01

    Several abiotic and biotic factors have been reported to describe runoff generation in Mediterranean hillslopes: e.g., slope gradient, micro-topography, vegetation pattern, soil water content, rock fragment size and distribution on soil surface, crusts, organic matter, etc. However, few investigations have been focused on the influence of soil repellency to water as runoff mechanisms. Two factors used to control water repellency in Mediterranean environments: soil moisture and organic matter content. There is a direct control of temporal rainfall distribution on soil water repellency: generally, it tends to increase during dry weather while it decreases or completely vanishes after heavy precipitation or during extended periods with high soil water contents. Also, water repellency used to be higher in soils with litter, roots, resins, waxes and other organic substances from some types of vegetation as they can be a source of hydrophobic substances, including some typical species of the Mediterranean scrublands. Studies in unburnt Mediterranean environments or burnt long time ago and more exactly of water repellency related to some vegetal shrub species are not very frequent in scientific literature. The aim of this study is to assess the influence of the rainfall variability in the water repellency of soils from a patchy-vegetated Mediterranean hillslope. The objectives are next: i) to analyze the effects of the rainfall variability on water repellency during one complete year; and ii) to determine the differences in water repellency of soils under a Mediterranean shrub specie (Cistus monspeliensis) and bare soil. The study site corresponds to one hillslope located in Montes de Málaga (South of Spain) under dry-Mediterranean climate. The hillslope was characterized by: southfacing, mean slope gradient of 27%, metamorphic geology (phyllites), patchy-vegetated pattern and sporadic grazing. The site was cultivated with cereal and disperse almond trees until the 1950s

  19. An experimental design for the investigation of water repellent property of candle soot particles

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, Bichitra Nanda; Kandasubramanian, Balasubramanian, E-mail: meetkbs@gmail.com

    2014-11-14

    The mechanistic aspect of candle soot particles under controlled atmosphere has been reported. The soot particles were characterized using Fourier transformation Infrared Spectroscopy, Raman spectroscopy, Transmission electron microscopy and X-ray diffraction. Hydrophobicity of the candle soot particles was confirmed from the presence of C–H group which enhances water repellency and can be used as filler material for fabrication of superhydrophobic coatings. The layered soot particle on the glass slide exhibits maximum water contact angle of 168°. Roughness of soot particle and various hydrophobic groups involved for obtaining superhydrophobicity were exposed. The Raman spectrum of soot particles revealed the presence of disorder graphene which was confirmed from appearance of D1 band. The agglomeration of candle soot particles has been discussed by measuring fractal dimension (D{sub f}) of the particles. The in-depth investigation for bringing the mechanism of formation of soot particle inside the flame reveals the inception of the first particles, growth of soot particles, particle coalescence, agglomeration and oxidation. Here, we have found that the mechanism of particle formation in candle flame involves various steps, in which the sintering as well as coalescence/collision process plays a major role. - Highlights: • Mechanistic aspect for hydrophobicity of candle soot is demonstrated. • Hydrophobicity of soot particles at different exposure time is described. • Agglomeration of soot particles related to fractal dimension is reported. • Mechanism of formation of soot particles in the candle flame is also described.

  20. Study of water-repellent treatments applied on limestone from Andalusian Cathedrals

    Directory of Open Access Journals (Sweden)

    Villegas, R.

    1991-09-01

    Full Text Available Five types of stone used in Andalusian Cathedrals have been treated with different water-repellent treatments, to evaluate the effects of this products. The stones studied are limestone, calcarenite and dolomite; the products applied are organosilicones and acrylics. In this work properties related with water access and movement through the stone have been measured and compared their values before and after the application of the treatments.

    Se han tratado varios tipos de piedra utilizados en Catedrales Andaluzas con diversos productos hidrófugos, con el fin de evaluar las características conferidas por los mismos. Los tipos de piedra son de naturaleza caliza, calcarenitas y dolomías; los productos son organosilícicos y acrílicos. En este trabajo se han medido las propiedades relacionadas con el acceso y movimiento de agua en la piedra, comparándose sus valores antes y después de la aplicación del tratamiento.

  1. Experimental evaluation of effect on Cassie-Baxter equation of surface roughness with application to soil water repellency

    Science.gov (United States)

    Ahn, Sujung; Douglas, Peter; Doerr, Stefan; Gowenlock, Cathren; Hallin, Ingrid; Mabbett, Ian

    2014-05-01

    Manifestation of soil water repellency depends both on the surface chemistry and the physical structure of the particles making up the soil. In materials science the effect of physical structure on water repellency is often explained by the Cassie-Baxter equation. Recently, a few attempts have been made to explain water repellency of soil using the Cassie-Baxter equation for hexagonally-arrayed spheres on a flat plane. Experimental verification of this conceptual model using glass beads as model soil particles has been left somewhat incomplete, as the experimentally measured contact angles do not match well those expected from theory. This might be caused by a failure to generate a perfect arrangement of particles. Therefore, we have aimed to obtain highly precise arrangements of glass beads as model soil particles using 3D printing technology. Our aim is to generate particle frames of precise hexagonal arrangement with particles at differing separations, and to measure the water contact angles upon the particle arrays optically using a goniometer. In this contribution, we report our preliminary results in which we explore the applicability of the Cassie-Baxter equation to such regular arrays as both separation distance and surface roughness is varied. This research has been funded by Bridging the Gap in Swansea University, UK.

  2. Fluorescent probes for understanding soil water repellency: the novel application of a chemist's tool to soil science

    Science.gov (United States)

    Balshaw, Helen M.; Davies, Matthew L.; Doerr, Stefan H.; Douglas, Peter

    2015-04-01

    Food security and production is one of the key global issues faced by society. It has become essential to work the land efficiently, through better soil management and agronomy whilst protecting the environment from air and water pollution. The failure of soil to absorb water - soil water repellency can lead to major environmental problems such as increased overland flow and soil erosion, poor uptake of agricultural chemicals, and increased risk of groundwater pollution due to the rapid transfer of contaminants and nutrient leaching through uneven wetting and preferential flow pathways. Understanding the causes of soil hydrophobicity is essential for the development of effective methods for its amelioration, supporting environmental stability and food security. Organic compounds deposited on soil mineral or aggregate surfaces have long been recognised as a major factor in causing soil water repellency. It is widely accepted that the main groups of compounds responsible are long-chain acids, alkanes and other organic compounds with hydrophobic properties. However, when reapplied to sands and soils, the degree of water repellency induced by these compounds and mixtures varied widely with compound type, amount, and mixture, in a seemingly unpredictable way. Fluorescent and phosphorescent probes are widely used in chemistry and biochemistry due to their sensitive response to their physical and chemical environment, such as polarity, and viscosity. However, they have to-date not been used to study soil water repellency. Here we present preliminary work on the evaluation of fluorescent probes as tools to study two poorly understood features that determine the degree of wettability for water repellent soils: (i) the distribution of organics on soils; (ii) the changes in polarity at soil surfaces required for water drops to infiltrate. In our initial work we have examined probes adsorbed onto model soils, prepared by adsorption of specific organics onto acid washed sand

  3. Postfire soil water repellency in piñon-juniper woodlands: Extent, severity, and thickness relative to ecological site characteristics and climate.

    Science.gov (United States)

    Zvirzdin, Daniel L; Roundy, Bruce A; Barney, Nicholas S; Petersen, Steven L; Anderson, Val J; Madsen, Matthew D

    2017-07-01

    Wildfires can create or intensify water repellency in soil, limiting the soil's capacity to wet and retain water. The objective of this research was to quantify soil water repellency characteristics within burned piñon-juniper woodlands and relate this information to ecological site characteristics. We sampled soil water repellency across forty-one 1,000 m(2) study plots within three major wildfires that burned in piñon-juniper woodlands. Water repellency was found to be extensive-present at 37% of the total points sampled-and strongly related to piñon-juniper canopy cover. Models developed for predicting SWR extent and severity had R(2)adj values of 0.67 and 0.61, respectively; both models included piñon-juniper canopy cover and relative humidity the month before the fire as coefficient terms. These results are important as they suggest that postfire water repellency will increase in the coming years as infilling processes enhance piñon-juniper canopy cover. Furthermore, reductions in relative humidity brought about by a changing climate have the potential to link additively with infilling processes to increase the frequency and intensity of wildfires and produce stronger water repellency over a greater spatial extent. In working through these challenges, land managers can apply the predictive models developed in this study to prioritize fuel control and postfire restoration treatments.

  4. Does wastewater from olive mills induce toxicity and water repellency in soil?

    Science.gov (United States)

    Peikert, B.; Bandow, N.; Schaumann, G. E.

    2012-04-01

    Olive oil mill wastewater is the effluent generated by the olive oil extraction process. It is the main waste product of this industry mainly being produced in the Mediterranean Basin. Because proper treatment options are rare it is often disposed into the environment, e.g. fields or wadies. Due to its high concentration of fatty acids and phytotoxic phenolic compounds and its high chemical and biological oxygen demand, olive oil mill wastewater becomes a serious environmental problem. In this screening study we investigated long-term effects of olive oil mill wastewater application on soil properties in several locations in the West Bank and Israel. We determined wettability via water drop penetration time and the contact angle as well as general soil properties including pH, EC, carbon content, and we conducted thermogravimetrical analyses in order to characterize the impact of the waste water on the quality of soil organic matter. Our results show that application of olive oil mill wastewater has various effects. We determined contact angles between 110 and 120° and water drop penetration times up to 1367 s indicating significant reduction in wettability. Furthermore, soil carbon and nitrogen content and water extractable organic matter increased as well as electric conductivity, which could be pointed out as a fertilizing effect. In contrast soil pH was significantly reduced. Conducting thermal analyses we observed an increase in the labile and refractory carbon fraction. Probably first one is responsible for induced water repellency. As a consequence the reduced wettability negatively affects soil quality. It would therefore be promising to minimize the hydrophobizing impacts without losing fertilizing effects of the olive oil mill wastewater.

  5. Development of silicone water repellent agents in construction business%建筑用有机硅防水剂的研拓

    Institute of Scientific and Technical Information of China (English)

    王洪祚; 王颖

    2012-01-01

    The silicone water repellent agents has a lot of types and play very important role in the construction. In this paper, the developments of different silicone water repellent agents were introduced briefly.%对不同种类的有机硅防水剂在建筑防水材料中的应用及研究开拓进行了扼要的综述.

  6. Water repellency and soil moisture variations under Rosmarinus officinalis in a burned soil

    Science.gov (United States)

    Gimeno-García, E.; Pascual-Aguilar, J. A.; Llovet, J.

    2009-04-01

    Mediterranean semi-arid landscapes are characterised by the patchiness of the vegetation cover, in which variations in the distribution pattern of soil water repellency (SWR) can be of major importance for their hydrological and geomorphological effects in burned areas, and also for their ecological implications concerning to the re-establishment of their plant cover. Within a broader research framework, the present work studies the influence of Rosmarinus officinalis vegetated patches on SWR in burned and unburned soils and its relationship with the field soil moisture content (SMC). The results presented here are the first step analysing the spatial pattern of sink and source runoff areas in a burned hillslope. The study area is located in the municipality of Les Useres, 40 km from Castellón city (E Spain), where a wildfire occurred in August 2007. We selected a burned SSE facing hillslope, located at 570 m a.s.l., with 12 ° slope angle, in which it was possible to identify the presence of two unique shrub species: Quercus coccifera L. and Rosmarinus officinalis L., which were distributed in a patchy mosaic. Twenty microsites with burned R. officinalis and eight at the nearest unburned area were selected. At the burned microsites, it was possible to distinguish three concentric zones (I, II and III) around the stumps showing differences on their soil surface appearance, which indicate a gradient of fire severity. Those differences were considered for soil sampling (1 sample per zone at each microsite, n= 84, form the first 2 cm of the mineral A horizon) and field soil moisture measurements determined by means of the moisture meter HH2 with ThetaProbe sensor type ML2x (5 measurements per zone at each microsite, n= 420), which were taken one day after the first rainfall event after fire, when 11 mm were registered in the study area. Results showed that the largest repellency persistence (measured by means of the Water Drop Penetration Time test, WDPT) was found

  7. Preparation of fluorine containing water repellent modified with palm oil and its water repellency%棕榈油改性含氟拒水剂的合成及其拒水性能

    Institute of Scientific and Technical Information of China (English)

    任清庆; 赵涛

    2013-01-01

    A palm oil-modified fluorine-containing water repellent agent,higher fatty acid trifluoroethyl ester,is prepared with palm oil and 2,2,2-trifluoro ethanol as raw materials,and then is applied to water repellent finish of cotton fabric.The structure of the agent is characterized by Fourier Transform Infrared Spectroscopy,and the contact angle,time of waterdrop disappearance,whiteness and breaking strength of the treated fabric are also measured.The optimum process are defined as follows:water repellent agent 40 g/L with ether as a solvent,double-dip-double-nip,predrying at 100 ℃ for 40 min,and curing at 170 ℃ for 3 min.The adhesion status of the water repellent agent on the fabric is observed by SEM,and the permeability of the treated fabric is also tested.The results show that the finished fabric has favorable water repellency and permeability with a slight decrease in whiteness and breaking strength.%以棕榈油和2,2,2-三氟乙醇为原料,合成了棕榈油改性含氟拒水剂-高级脂肪酸三氟乙酯;采用傅里叶变换红外光谱,对合成物质的结构进行了表征;测定了该拒水剂整理棉织物的接触角、水滴消失时间、白度以及断裂强力等指标;确定了棉织物的最佳整理工艺条件:以乙醚为溶剂,棕榈油改性含氟拒水试剂用量40 g/L,二浸二轧,100℃预烘40 min,170℃焙烘3 min.结果表明,经过该棕榈油改性含氟拒水剂整理后,棉织物具有良好的拒水性能和透气性能,白度和断裂强力稍有下降.

  8. Fabrication of water-repellent cellulose fiber coated with magnetic nanoparticles under supercritical carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Xu Shengjie; Shen Danping; Wu Peiyi, E-mail: peiyiwu@fudan.edu.cn [Fudan University, State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Laboratory of Advanced Materials (China)

    2013-04-15

    Hematite nanoparticle-coated magnetic composite fiber was prepared in supercritical carbon dioxide (scCO{sub 2}). With the help of scCO{sub 2}, cellulose did not need to be dissolved and regenerated and it could be in any form (e.g., cotton wool, filter paper, textile, etc.). The penetrating and swelling effect of scCO{sub 2}, the slowing reaction rate of weak alkalis, and the template effect of cellulose fibers were discovered to be the key factors for the fabrication of ordered cellulose/Fe{sub 2}O{sub 3} composite fibers. The structures of the composite fibers as well as the layers of Fe{sub 2}O{sub 3} particles were characterized by means of scanning/transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman investigation. It was found that {alpha}-Fe{sub 2}O{sub 3} granules which ranged from 30 to 85 nm with average diameter around 55 nm would be generated on the surface of cellulose fibers via potassium acetate, while irregular square prisms (ranged from 200 to 600 nm) which were composed of smaller nanoparticles ({approx}10 nm) would be fabricated via urea. And, the obtained composite was highly water repellent with superparamagnetic or ferromagnetic properties.

  9. Impact of the extreme 2009 wildfire Victoria the wettability of naturally highly water repellent soils

    Science.gov (United States)

    Doerr, Stefan H.; Shakesby, Richard A.; Sheridan, Gary J.; Lane, Patrick Nj; Smith, Hugh G.; Bell, Tina; Blake, William H.

    2010-05-01

    The recent catastrophic wildfires near Melbourne, which peaked on Feb. 7 2009, burned ca 400,000 ha and caused the tragic loss of 173 people. They occurred during unprecedented extreme fire weather where dry northerly winds gusting up to 100 km/h coincided with the highest temperatures ever recorded in this region. These conditions, combined with the very high biomass of mature eucalypt forests, very low fuel moisture conditions and steep slopes, generated extreme burning conditions. A rapid response project was launched under the NERC Urgency Scheme aimed at determining the effects of this extreme event on soil properties. Three replicate sites each were sampled for extremely high burn severity, high burn severity and unburnt control terrain, within mature mixed-species eucalypt forests near Marysville in April 2009. Ash and surface soil (0-2.5 cm and 2.5-5 cm) were collected at 20 sample grid points at each site. Here we report on outcomes from Water Drop Penetration Time (WDPT) tests carried out on soil samples to determine the impact of this extreme event on the wettability of a naturally highly water repellent soil. Field assessment suggested that the impact of this extreme wildfire on the soil was less than might be supposed given the extreme burn severity (indicated by the complete elimination of the ground vegetation). This was confirmed by the laboratory results. No major difference in WDPT was detected between (i) burned and control samples, and (ii) between surface and subsurface WDPT patterns, indicating that soil temperatures in the top 0-2.5 cm did not exceed ~200° C. Seedling germination in burned soil was reduced by at least 2/3 compared to the control samples, however, this reduction is indicative an only modest heat input into the soil. The limited heat input into the soil stands in stark contrast to the extreme burn severity (based on vegetation destruction parameters). We speculate that limited soil heating resulted perhaps from the unusually

  10. Vegetation-induced soil water repellency as a strategy in arid ecosystems. A geochemical approach in Banksia woodlands (SW Australia)

    Science.gov (United States)

    Muñoz-Rojas, Miriam; Jiménez-Morillo, Nicasio T.; González-Pérez, Jose Antonio; Zavala, Lorena M.; Stevens, Jason; Jordan, Antonio

    2016-04-01

    Introduction Banksia woodlands (BW) are iconic ecosystems of Western Australia (WA) composed by an overstorey dominated by Proteaceae, e.g. Banksia menziesii and Banksia attenuata, in combination with other species, such as Eucalyptus spp., Verticordia spp. or Melaleuca spp. Although located in very poor dune soils, BW provide numerous ecosystem services and sustain a high biodiversity. In this area, annual rainfall is relatively high (about 800 mm) but permeability of the sandy substrate leads to a functionally arid ecosystem. Currently, BW are threatened by sand mining activities and urban expansion; therefore conservation and restoration of these woodlands are critical. Despite numerous efforts, the success of restoration plans is usually poor mostly due to the high sensitivity to drought stress and poor seedling survival rates (5-30%) (Benigno et al., 2014). A characteristic feature of BW is their root architecture, formed by a proteoid (cluster) system that spreads to form thick mats below the soil surface, favouring the uptake of nutrients (especially, P), and preventing soil erosion. Root exudates are related to numerous plant functions, as they facilitate penetration of roots in soil and enhance the extraction of scarce mineral nutrients and its further assimilation. Exudates may also interact directly with soil or indirectly through microbial mediated events being also related to soil water repellency (SWR; Lozano et al, 2014). Knowledge about the specific compounds able to induce SWR is limited (Doerr et al., 2000), but it is generally accepted that is caused by organic molecules coating the surface of soil mineral particles and aggregates (Jordán et al., 2013). Proteaceae release short-chained organic acids to enhance phosphate acquisition, which have been also reported to be related with SWR (Jiménez-Morillo et al., 2014). It is hypothesized that disruption of water dynamics in mature BW soils is underlying the failure of restoration plans. This

  11. Water repellency of sandy soil as a function of hydrophobic concentration Influência da concentração de extratos hidrofóbicos na repelência à água em solos arenosos

    Directory of Open Access Journals (Sweden)

    Yorleni Chang Cambronero

    2011-03-01

    Full Text Available

    Soil water repellency has been reported worldwide being most extremes cases observed in sandy soils. Soil  water repellency is accepted to be caused by recovering  of soil particles by hydrophobic compounds originated  from plant decomposition. This work aimed to evaluate  the influence of concentration of hydrophobic extracts  from a forest soil under Pinus taeda on water repellency  of sandy soil with different organic matter  content. Hydrophobic compounds were extracted from a  everely hydrophobic Lithosol, using  chloroform:acetone, followed by isopropanol:ammonia. The water drops penetration time test (WDPT was applied in dried samples under four temperatures, seven treatments (sand with 0%; 3%; 6.5%; 6.5% + 10% of humic acid (AH; 6,5% + 30% of AH; 6.5% + 50% of AH; and 10% of charcoal as organic matter, and three levels of hydrophobic extract. The extracted material induced hydrophobicity in all treatments, in variable intensity, but lower than those found in the original Lithosol. Treatments with extract level 1 (2.88 g kg-1 presented the highest times of water repellency.

    doi: 10.4336/2011.pfb.31.65.01

    A repelência à água é estudada em vários solos do  mundo, sendo os casos mais extremos encontrados  em solos arenosos. Acredita-se que a repelência à  água seja causada pelo recobrimento das partículas do  solo por compostos hidrofóbicos derivados da  decomposição de plantas. Este trabalho avaliou a  influência da concentração de extratos hidrofóbicos de  um Neossolo sob plantio de Pinus taeda, na repelência  à água em amostras de um solo arenoso preparado  em laboratório, com diferentes teores de matéria  orgânica. Os extratos hidrofóbicos do solo original foram extraídos com clorofórmio:acetona, seguido de   isopropanol:amônia. Os tratamentos constaram de  mistura de areia com sete níveis de matéria orgânica  (0%; 3%; 6,5%; 6,5% + 10% de ácido húmico (AH;  6

  12. Water repellency in an Alpine forest soil and its impact on hydraulic characteristics under simulated climate change

    Science.gov (United States)

    Schwen, Andreas; Zimmermann, Michael; Lamparter, Axel; Woche, Susanne; Bachmann, Jörg

    2014-05-01

    The climate of Alpine environments is expected to change dramatically as a consequence of global climate change. In this ecologically sensitive environment, prolonged dry periods and an increased occurence of extreme rainfall events is forecasted by many climate change models. On the other hand, soil water repellency (SWR) is known to affect hydraulic processes in soils, particularly in acidic forest soils and as a consequence of prolonged dry periods. By changing the soil surface properties, SWR also changes the hydraulically effective properties of soils. The quantification of the spatial occurence and degree of hydrophobicity is a crucial prerequirement for ecological and hydrological impact assessment and developing new models. Therefore, the objective of the present study was to quantify soil water repellency in an Alpine forest with respect to its spatial variability and affected by different simulated climatic regimes. The study was accomplished in the Rosalian mountains, some 60 km south of Vienna, Austria. The vegetation was a mature beech forest and the soil was a Podsolic Cambisol over weathered granitic rock debris. As parts of the experimental plot were covered by plastic roofs and artificially irrigated, three different treatments were tested: Compared to the natural precipitation (control), the irrigation amount was reduced with two drought degrees (moderate and extreme). Within a small grid, 9 samples were taken per treatment in two depths (surface and 0.10 m). The contact angle was determined with the modified sessile drop method. Additionally, total and organic carbon contents and the hydraulic soil properties were quantified. Infiltration experiments were performed with a tension infiltrometer using water and ethanol. The results showed considerable water repellency with at least subcritical contact angles for all treatments. Contact angles increased to above 90 degree at the moderate and extreme drought treatments. Differences between intrinsic

  13. Alteration of soil hydraulic properties and soil water repellency by fire and vegetation succession in a sagebrush steppe ecosystem

    Science.gov (United States)

    Chandler, D. G.; Seyfried, M. S.

    2016-12-01

    This study explores the impacts of fire and plant community succession on soil water repellency (SWR) and infiltration properties to improve understanding the long term impacts of prescribed fire on SWR and infiltration properties in sagebrush-steppe ecosystem. The objectives of this study were: 1) To explore the temporal effects of prescribed burning in sagebrush dominated landscape; 2) To investigate spatial variability of soil hydrologic properties; 3) To determine the relationship among soil organic fraction, soil hydrophobicity and infiltration properties. Fieldwork was conducted in paired catchments with three dominant vegetation cover communities: Low sage, big mountain sage and aspen. Detailed, heavily replicated analyses were conducted for unsaturated hydraulic conductivity, sorptivity water drop penetration time and static soil-water-air contact angle. The results show that the severity and presence of surface soil water repellency were considerably reduced six years after fire and that hydraulic conductivity increased significantly in each vegetation cover compared to pre-burn condition. Comparisons among soil hydrological properties shows that hydraulic conductivity is not strongly related to SWR, and that sorptivity is negatively correlated with SWR. The spatial variance of hydraulic properties within the burned high sage and low sage, in particularly, spatial variability of hydraulic conductivity is basically controlled by soil texture and sorptivity is affected by soil wettability. The average water repellency in Low Sage area was significantly different with Big Sage and Aspen as the gap of organic content between Low Sage and other vegetation area. The result of contact angle measurement and organic content analysis shows a strong positive correlation between SWR and organic matter.

  14. The influence of vegetation on soil water repellency-markers and soil hydrophobicity.

    Science.gov (United States)

    Mao, Jiefei; Nierop, Klaas G J; Rietkerk, Max; Sinninghe Damsté, Jaap S; Dekker, Stefan C

    2016-10-01

    Soil water repellency (SWR) markers are defined as hydrophobic compounds in soil causing SWR and are mainly derived from plants. Previous studies have shown the types and abundance of SWR-markers in soils. However, how these SWR-markers are exactly related to SWR and their origin is poorly understood. This study aims to understand the relationship between SWR-markers, vegetation type and cover and SWR for a simple sandy soil ecosystem, consisting of oaks with sedge and six grass species. All the soil (at different depth) and vegetation samples were collected in the field along a 6m transect, starting from an oak tree. Further along the transect grasses and sedges became more abundant. Free and ester-bound lipids from soils and plant leaves/roots were obtained using a sequential extraction method and identified by gas chromatography-mass spectrometry. Significant linear correlations were found between the main soil characteristics, such as total organic carbon content, and SWR. Single long-chain (>C20) SWR-markers derived from both plant leaf waxes and roots positively related to SWR. Both ester-bound ω-hydroxy fatty acids and C22 and C24 α,ω-dicarboxylic acids were predominantly present in the grass roots, but to a lesser extent in the roots of oak and sedge. These suberin-derived ω-hydroxy fatty acids and α,ω-dicarboxylic acids characteristic of roots could well predict the SWR. Additionally, the SWR predictors abundantly present in the soils matched well with high concentrations of the corresponding biomarkers in the dominant vegetation species that covered the soils. Our analyses demonstrated that grass roots influenced SWR more due to their more substantial contribution of organic matter to the topsoils than oak roots. This led to a stronger SWR of the soils covered with grass than those covered with oak vegetation. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Post-fire interactions between soil water repellency, soil fertility and plant growth in soil collected from a burned piñon-juniper woodland

    Science.gov (United States)

    Fernelius, Kaitlynn J.; Madsen, Matthew D.; Hopkins, Bryan G.; Bansal, Sheel; Anderson, Val J.; Eggett, Dennis L.; Roundy, Bruce A.

    2017-01-01

    Woody plant encroachment can increase nutrient resources in the plant-mound zone. After a fire, this zone is often found to be water repellent. This study aimed to understand the effects of post-fire water repellency on soil water and inorganic nitrogen and their effects on plant growth of the introduced annual Bromus tectorum and native bunchgrass Pseudoroegneria spicata. Plots centered on burned Juniperus osteosperma trees were either left untreated or treated with surfactant to ameliorate water repellency. After two years, we excavated soil from the untreated and treated plots and placed it in zerotension lysimeter pots. In the greenhouse, half of the pots received an additional surfactant treatment. Pots were seeded separately with B. tectorum or P. spicata. Untreated soils had high runoff, decreased soilwater content, and elevated NO3eN in comparison to surfactant treated soils. The two plant species typically responded similar to the treatments. Above-ground biomass and microbial activity (estimated through soil CO2 gas emissions) was 16.8-fold and 9.5-fold higher in the surfactant-treated soils than repellent soils, respectably. This study demonstrates that water repellency can influence site recovery by decreasing soil water content, promoting inorganic N retention, and impairing plant growth and microbial activity.

  16. Characterization of the optical properties of hydrophobic coatings and realization of high performance AR coatings with dust- and water-repellent properties

    Science.gov (United States)

    Bruynooghe, S.; Spinzig, S.; Fliedner, M.; Hsu, G. J.

    2008-09-01

    Hydrophobic coatings enable the manufacture of easy-to-clean surfaces having dust- and water-repellent properties. In this work, a hydrophobic coating is deposited as a top layer on an antireflective (AR) multilayer system comprising a MgF2 upper layer to produce low reflectance optical surfaces at a normal incident angle in the visible spectrum with dust- and water-repellent properties for applications in precision optics. We report on the preparation and characterization of the optical properties of hydrophobic coatings deposited using a vacuum evaporation process and a commercially available water repellent substance. By means of a grazing incidence X-ray reflectometer it is shown that the hydrophobic coating can be considered, from an optical point of view, as two adjacent thin layers having specific thicknesses and densities. In fact, the hydrophobic layer is one monolayer comprising molecular chains with anchoring groups responsible for the chemical bond with the substrate material and functional groups responsible for the water- and oil-repellent properties. Optical constants are determined using a spectroscopic ellipsometer and are taken into account in the final multilayer system design. High performance AR coatings having an average reflectance of 0.14% at 7° incident angle in the 400-680nm spectral range together with a pleasing purple-red reflex color are produced. Coated lenses exhibit an excellent abrasion resistance, environmental stability, resistance to cleaning agents, homogeneity and water repellence with contact angles against water higher than 110°.

  17. Effect of climatic conditions on the development of soil water repellency in soils treated with the wastewater of the olive oil production

    Science.gov (United States)

    Schaumann, Gabriele E.; Peikert, Benjamin; Tamimi, Nesreen; Steinmetz, Zacharias; Fischer, Jonas; Bibus, Daniel; Marei Sawalha, Amer; Dag, Arnon

    2014-05-01

    The disposal of untreated wastewater on soil can induce severe water repellency. The final degree of water repellency may strongly depend on the environmental conditions prevailing during and after disposal. Also unpolluted soil can develop severe water repellency upon exposure to extreme heat or draught events. The induced water repellency can be either persistent or of transient nature. However, the underlying mechanisms are not yet completely understood. The objective of this study was to investigate how climatic conditions determine the development and persistence of water repellency following wastewater disposal. Our hypothesis was that amphiphilic organic wastewater compounds physically sorb onto surfaces, which renders them hydrophobic. Depending on temperature and moisture, those compounds are degraded, chemically incorporated into SOM, or irreversibly sorbed to soil particles during the time after the first waste water-soil contact. According to our hypothesis, biological communities favor degradation and transformation of OM of waste water into SOM under moist soil conditions. This would reduce the initial hydrophobization. In contrast, drying irreversibly renders soil hydrophobic and phytotoxic due to immobilization of OMW OM in the soil. To test these hypotheses, we investigated effects of olive mil wastewater (OMW), the effluent originating from olive oil production, directly applied to soil. In Israel and Palastine, olive oil production generates large amounts of OMW within a short period of time between November and January. As sewage facilities do not accept OMW, it is often disposed onto soil, which leads to severe soil and groundwater pollution. If the above mentioned hypotheses match, pollution and hydrophobization might be minimized if the wastewater is discharged at the right time of the year. In order to test this, we conducted field (2-3 years) and laboratory (60 days) experiments in Israel (Gilat, arid climate) and in the West Bank (Bait

  18. Water Repellent Soils: The use of electrical resistivity tomography in a small scale catchment model to evaluate the effectiveness of surfactants.

    Science.gov (United States)

    Lowe, Mary-Anne; Mathes, Falko; McGrath, Gavan; Leopold, Matthias

    2017-04-01

    Soil water repellence effects large areas of land in Western Australia causing large forfeits in agricultural profit. Surfactants are a potential management tool, however, in field trials they have had varied success and their impact on water movement is poorly understood. This study employs a novel approach to determine the effectiveness of surfactants at modifying infiltration into water repellent soils. Using a physical catchment model (0.6 m × 0.6 m) with soils arranged in a ridge and furrow topography, irrigation and runoff were quantified. Electrical resistivity tomography (ERT) was used to measure changes in soil moisture patterns in two dimensions. Two sandy soils with contrasting severity of water repellence, as measured by the Molarity of Ethanol Droplet (MED) test, were assessed. The impact of two surfactants, at an equivalent rate of 1 L ha-1, and an untreated control were monitored over 5 wetting events. With surfactant application the very severely water repellent soil (MED 4.2 M) showed an increase in infiltration of up to 31%, which was concentrated under the area of surfactant application in the furrow. Volumetric water contents beneath the furrow increased up to 40% below 20 mm depth. Water infiltration into the untreated soil with low water repellence (MED 1.0 M) was 98%, and this did not significantly change with surfactant application. This physical catchment model, combined with hydrological and geophysical monitoring provides a useful tool to assess the effectiveness of surfactants in increasing water infiltration and subsurface soil moisture in water repellent soils. The work is part of the Australian CRC for Polymer project.

  19. Influence of soil water repellency on runoff and solute loss from New Zealand pasture

    Science.gov (United States)

    Jeyakumar, P.; Müller, K.; Deurer, M.; van den Dijssel, C.; Mason, K.; Green, S.; Clothier, B. E.

    2012-04-01

    Soil water repellency (SWR) has been reported in New Zealand, but knowledge on its importance for the country's economy and environment is limited. Our recent survey on the occurrence of SWR under pasture across the North Island of New Zealand showed that most soils exhibited SWR when dry independent of climate but influenced by the soil order. SWR is discussed as an important soil surface condition enhancing run-off and the transfer of fertilizers and pesticides from agricultural land into waterways. So far, the impact of SWR on run-off has rarely been measured. We developed a laboratory-scale run-off measurement apparatus (ROMA) to quantify directly the impact of SWR on run-off from undisturbed soil slabs. We compared the run-off resulting from the run-on of water with that resulting from an ethanol (30% v/v) solution, which is a fully-wetting liquid even in severely hydrophobic soils. Thus, the experiments with the ethanol solution can be understood as a proxy measure of the wetting-up behaviour of hydrophilic soils. We conducted ROMA run-off experiments with air-dried soil slabs (460 mm long x 190 mm wide x 50 mm deep) collected from pastoral sites, representing three major soil orders in the North Island: Recent Soil (Fluvisol), Gley Soil (Gleysol), and Organic Soil (Histosol), with water followed by the ethanol solution at a run-on rate of 60 mm/h. Bromide was applied at 80 kg KBr/ha prior to the water experiments to assess potential solute losses via run-off. The air-dried soils had a high degree and persistence of SWR (contact angles, 97, 98 and 104° , and potential water drop penetration times, 42, 54 and 231 min for the Fluvisol, Gleysol and Histosol, respectively). Under identical soil and experimental conditions, water generated run-off from all soils, but in the experiments with the ethanol solution, the entire ethanol solution infiltrated into the soils. The ranking of the run-off coefficients of the soils directly reflected their ranking in

  20. 拒水抗菌复合功能机织产品开发%Development of water repellent and antibacterial compound function of woven fabric

    Institute of Scientific and Technical Information of China (English)

    李景川; 李苏; 吴灶生; 智军

    2015-01-01

    将拒水整理剂和抗菌剂同浴整理,结果表明:抗菌剂的添加会降低机织物的拒水性,且无法同时满足拒水等级3级,抗菌级别A级标准的要求,为了获得满足要求的拒水抗菌复合功能机织产品,可采用抗菌原纱在拒水整理液中同时添加适当的抗菌剂来解决.%Water repellent finishing agent and anti- bacterial agents were applied to woven fabrics in one bath. The results showed that the addition of antibacterial agent would reduce the water repellency of woven fabrics. Grade 3 of water repellent rating and level A of antibacterial rating could not be met at the same time. In order to meet the requirements of water repellent and antibacterial compound function of woven fabric, the antibacterial yarn was used, and antibacterial agent was added to water repellent finishing liquid to enhance the antibacterial ability.

  1. Relationships between soil water repellency and microbial community composition under different plant species in a Mediterranean semiarid forest

    Directory of Open Access Journals (Sweden)

    Lozano Elena

    2014-06-01

    Full Text Available Soil water repellency (SWR can influence many hydrological soil properties, including water infiltration, uneven moisture distribution or water retention. In the current study we investigated how variable SWR persistence in the field is related to the soil microbial community under different plant species (P. halepensis, Q. rotundifolia, C. albidus and R. officinalis in a Mediterranean forest. The soil microbial community was determined through phospholipid fatty acids (PLFA. The relationships between microbiological community structure and the soil properties pH, Glomalin Related Soil Protein (GRSP and soil organic matter (SOM content were also studied. Different statistical analyses were used: Principal Component Analysis (PCA, ANOVA, Redundancy Analysis and Pearson correlations. The highest concentrations of PLFA were found in the most water repellent samples. PCA showed that microorganism composition was more dependent of the severity of SWR than the type of plant species. In the Redundancy Analysis, SWR was the only significant factor (p<0.05 to explain PLFA distributions. The only PLFA biomarkers directly related to SWR were associated with Actinobacteria (10Me16:0, 10Me17:0 and 10Me18:0. All the results suggest that a strong dependence between SWR and microbial community composition.

  2. Effects of Long-Term Water-Aging on Novel Anti-Biofilm and Protein-Repellent Dental Composite.

    Science.gov (United States)

    Zhang, Ning; Zhang, Ke; Melo, Mary A S; Weir, Michael D; Xu, David J; Bai, Yuxing; Xu, Hockin H K

    2017-01-18

    The aims of this study were to: (1) synthesize an anti-biofilm and protein-repellent dental composite by combining 2-methacryloyloxyethyl phosphorylcholine (MPC) with quaternary ammonium dimethylaminohexadecyl methacrylate (DMAHDM); and (2) evaluate the effects of water-aging for 180 days on protein resistance, bacteria-killing ability, and mechanical properties of MPC-DMAHDM composite. MPC and DMAHDM were added into a resin composite. Specimens were stored in distilled water at 37 °C for 1, 30, 90, and 180 days. Mechanical properties were measured in three-point flexure. Protein attachment onto the composite was evaluated by a micro bicinchoninic acid approach. An oral plaque microcosm biofilm model was employed to evaluate oral biofilm viability vs. water-aging time. Mechanical properties of the MPC-DMAHDM composite after 180-day immersion matched those of the commercial control composite. The composite with 3% MPC + 1.5% DMAHDM had much stronger resistance to protein adhesion than control (p composite were three orders of magnitude lower than commercial control. The protein-repellent and antibacterial effects were durable and showed no loss in water-aging from 1 to 180 days. The novel MPC-DMAHDM composite possessed strong and durable resistance to protein adhesion and potent bacteria-eradicating function, while matching the load-bearing ability of a commercial dental composite. The novel MPC-DMAHDM composite represents a promising means of suppressing oral plaque growth, acid production, and secondary caries.

  3. Surface properties of woody thin boards composed of commercially available lignin and cellulose: Relationship between the orientation of lignin and water repellency

    Energy Technology Data Exchange (ETDEWEB)

    Shimanouchi, Toshinori; Kamba, Tomoya; Yang, Wei [Graduate School of Environmental and Life Science, Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama 700-8530 (Japan); Aoyagi, Satoka [Department of Material and Lie Science, Seikei University, 3-3-1 Musashino, Tokyo 180-8633 (Japan); Kimura, Yukitaka, E-mail: yktkkimu@cc.okayama-u.ac.jp [Graduate School of Environmental and Life Science, Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama 700-8530 (Japan)

    2015-08-30

    Highlights: • Woody thin boards were formed by adequate ratio of lignin/cellulose/moisture. • Component ratio of lignin/cellulose/moisture determined water repellency. • Increase of water repellency resulted from the surface orientation of lignin. - Abstract: Woody thin boards were prepared from lignin, cellulose, and water by compression molding at 180 °C and 25 MPa for 10 min. Boards with higher contact angles gave lower values of relative permittivity on their surface. Attenuated-total reflection Fourier transfer infrared spectroscopy suggested that more lignin existed on the surface of the boards with the high contact angle, which was also supported by scanning electron microscopy and atomic force microscopy. Our findings thus revealed that the orientation of lignin at the surface resulted in increased hydrophobicity of the surface and contributed to the enhancement of water repellency.

  4. Organic carbon, water repellency and soil stability to slaking at aggregate and intra-aggregate scales

    Science.gov (United States)

    Jordán López, Antonio; García-Moreno, Jorge; Gordillo-Rivero, Ángel J.; Zavala, Lorena M.; Cerdà, Artemi; Alanís, Nancy; Jiménez-Compán, Elizabeth

    2015-04-01

    Water repellency (WR) is a property of some soils that inhibits or delays water infiltration between a few seconds and days or weeks. Inhibited or delayed infiltration contributes to ponding and increases runoff flow generation, often increasing soil erosion risk. In water-repellent soils, water infiltrates preferentially through cracks or macropores, causing irregular soil wetting patterns, the development of preferential flow paths and accelerated leaching of nutrients. Although low inputs of hydrophobic organic substances and high mineralization rates lead to low degrees of WR in cropped soils, it has been reported that conservative agricultural practices may induce soil WR. Although there are many studies at catchment, slope or plot scales very few studies have been carried out at particle or aggregate scale. Intra-aggregate heterogeneity of physical, biological and chemical properties conditions the transport of substances, microbial activity and biochemical processes, including changes in the amount, distribution and chemical properties of organic matter. Some authors have reported positive relationships between soil WR and aggregate stability, since it may delay the entry of water into aggregates, increase structural stability and contribute to reduce soil erosion risk. Organic C (OC) content, aggregate stability and WR are therefore strongly related parameters. In the case of agricultural soils, where both the type of management as crops can influence all these parameters, it is important to evaluate the interactions among them and their consequences. Studies focused on the intra-aggregate distribution of OC and WR are necessary to shed light on the soil processes at a detailed scale. It is extremely important to understand how the spatial distribution of OC in soil aggregates can protect against rapid water entry and help stabilize larger structural units or lead to preferential flow. The objectives of this research are to study [i] the OC content and the

  5. Lousicidal, ovicidal and repellent efficacy of some essential oils against lice and flies infesting water buffaloes in Egypt.

    Science.gov (United States)

    Khater, Hanem F; Ramadan, Mohamed Y; El-Madawy, Reham S

    2009-10-14

    The lousicidal and repellent effects of five essential oils were investigated for the first time against the buffalo louse, Haematopinus tuberculatus, and flies infesting water buffaloes in Qalyubia Governorate, Egypt. For the in vitro studies, filter paper contact bioassays were used to test the oils and their lethal activities were compared with that of d-phenothrin. Four minutes post-treatment, the median lethal concentration, LC50, values were 2.74, 7.28, 12.35, 18.67 and 22.79% for camphor (Cinnamomum camphora), onion (Allium cepa), peppermint (Mentha piperita), chamomile (Matricaria chamomilla) and rosemary oils (Rosmarinus officinalis), respectively, whereas for d-phenothrin, it was 1.17%. The lethal time (50) (LT50) values were 0.89, 2.75, 15.39, 21.32, 11.60 and 1.94 min after treatment with 7.5% camphor, onion, peppermint, chamomile, rosemary and d-phenothrin, respectively. All the materials used except rosemary, which was not applied, were ovicidal to the eggs of H. tuberculatus. Despite the results of the in vitro assays, the in vivo treatments revealed that the pediculicidal activity was more pronounced with oils. All treated lice were killed after 0.5-2 min, whereas with d-phenothrin, 100% mortality was reached only after 120 min. The number of lice infesting buffaloes was significantly reduced 3, 6, 4, 6 and 9 days after treatment with camphor, peppermint, chamomile, onion, and d-phenothrin, respectively. Moreover, the oils and d-phenothrin significantly repelled flies, Musca domestica, Stomoxys calcitrans, Haematobia irritans and Hippobosca equina, for 6 and 3 days post-treatment, respectively. No adverse effects were noted on either animals or pour-on operators after exposure to the applied materials. Consequently, some Egyptian essential oils show potential for the development of new, speedy and safe lousicides and insect repellents for controlling lice and flies which infest water buffaloes.

  6. (Virtual) Water-repellent Law? Why Legal Studies Should Be Brought Into the Virtual Water Debate

    Science.gov (United States)

    Turrini, Paolo

    2014-05-01

    Virtual water studies are a marvelous example of the much praised "interdisciplinary approach", efficaciously intertwining many threads woven by scholars of very diverse fields of research. After all, if water is an object of biological interest and the word "virtual" becomes especially significant in the framework of the international trade flows, why should agronomists and economists not work together? And, with them, hydrologists, environmental engineers, network analysis experts… either working side by side or, at least, following one another's steps. Browsing the relevant academic literature one may notice that a vast array of disciplines is dealing with the topic. As a consequence, it may come as a surprise that lawyers seem to have remained almost deaf to the charming call of virtual water. A social science thoroughly "social" even if sometimes deemed (also by its practitioners) akin to humanities - and for this reason not always timely in catching the hints by hard sciences - law has a lot to say about virtual water and its manifold aspects. And it is so, in my opinion, in at least two respects. First of all, legal provisions can be determinants of social facts no less than other types of norms, such as physical or economic laws. Law shapes the human behavior by giving incentives or establishing constraints to the conduct of virtually any kind of social actor, be they farmers needing to decide what to grow, entrepreneurs willing to invest in the water market, or governments requested to address their communities' problems. All of them will make their choices in consideration of the costs, opportunities, and limits set by a number of regulations. In the second place, and strictly connected with the first reason, law may offer some answers to the challenges that virtual water and, more in general, the water-food nexus bring with them. In fact, understanding the way legal provisions affect the taking of decisions in the water sector, one may try to devise

  7. A new modelling approach to simulate preferential flow and transport in water repellent porous media: Parameter sensitivity, and effects on crop growth and solute leaching

    NARCIS (Netherlands)

    Kramers, G.; Dam, van J.C.; Ritsema, C.J.; Stagnitti, F.; Oostindie, K.; Dekker, L.W.

    2005-01-01

    A modified version of the popular agrohydrological model SWAP has been used to evaluate modelling of soil water flow and crop growth at field situations in which water repellency causes preferential flow. The parameter sensitivity in such situations has been studied. Three options to model soil

  8. Water-Repellent Properties of Superhydrophobic and Lubricant-Infused "Slippery" Surfaces: A Brief Study on the Functions and Applications.

    Science.gov (United States)

    Cao, Moyuan; Guo, Dawei; Yu, Cunming; Li, Kan; Liu, Mingjie; Jiang, Lei

    2016-02-17

    Bioinspired water-repellent materials offer a wealth of opportunities to solve scientific and technological issues. Lotus-leaf and pitcher plants represent two types of antiwetting surfaces, i.e., superhydrophobic and lubricant-infused "slippery" surfaces. Here we investigate the functions and applications of those two types of interfacial materials. The superhydrophobic surface was fabricated on the basis of a hydrophobic fumed silica nanoparticle/poly(dimethylsiloxane) composite layer, and the lubricant-infused "slippery" surface was prepared on the basis of silicone oil infusion. The fabrication, characteristics, and functions of both substrates were studied, including the wettability, transparency, adhesive force, dynamic droplet impact, antifogging, self-cleaning ability, etc. The advantages and disadvantages of the surfaces were briefly discussed, indicating the most suitable applications of the antiwetting materials. This contribution is aimed at providing meaningful information on how to select water-repellent substrates to solve the scientific and practical issues, which can also stimulate new thinking for the development of antiwetting interfacial materials.

  9. Water repellency on a fluorine-containing polyurethane surface: toward understanding the surface self-cleaning effect.

    Science.gov (United States)

    Wu, Wanling; Zhu, Qingzeng; Qing, Fengling; Han, Charles C

    2009-01-06

    Surface geometrical microstructure and low surface free energy are the two most important factors for a self-cleaning surface. In this study, multiform geometrical microstructured surfaces were fabricated by casting and electrospinning polyurethanes with and without low surface energy segments. The effect of low surface energy on water repellency was evaluated. Low surface energy seems to make a more significant contribution to the static wetting behavior than do dynamic properties such as the improvement of sliding behavior. Sucking disk behavior was brought forward to explain the pinning state of a water droplet on hydrophobic surfaces with high water contact angles (>150 degrees ). A better understanding of the relationship between the static contact angle and the dynamic sliding property was provided.

  10. Comparing simple and complex approaches to simulate the impacts of soil water repellency on runoff and erosion in burnt Mediterranean forest slopes

    Science.gov (United States)

    Nunes, João Pedro; Catarina Simões Vieira, Diana; Keizer, Jan Jacob

    2017-04-01

    Fires impact soil hydrological properties, enhancing soil water repellency and therefore increasing the potential for surface runoff generation and soil erosion. In consequence, the successful application of hydrological models to post-fire conditions requires the appropriate simulation of the effects of soil water repellency on soil hydrology. This work compared three approaches to model soil water repellency impacts on soil hydrology in burnt eucalypt and pine forest slopes in central Portugal: 1) Daily approach, simulating repellency as a function of soil moisture, and influencing the maximum soil available water holding capacity. It is based on the Thornthwaite-Mather soil water modelling approach, and is parameterized with the soil's wilting point and field capacity, and a parameter relating soil water repellency with water holding capacity. It was tested with soil moisture data from burnt and unburnt hillslopes. This approach was able to simulate post-fire soil moisture patterns, which the model without repellency was unable to do. However, model parameters were different between the burnt and unburnt slopes, indicating that more research is needed to derive standardized parameters from commonly measured soil and vegetation properties. 2) Seasonal approach, pre-determining repellency at the seasonal scale (3 months) in four classes (from none to extreme). It is based on the Morgan-Morgan-Finney (MMF) runoff and erosion model, applied at the seasonal scale and is parameterized with a parameter relating repellency class with field capacity. It was tested with runoff and erosion data from several experimental plots, and led to important improvements on runoff prediction over an approach with constant field capacity for all seasons (calibrated for repellency effects), but only slight improvements in erosion predictions. In contrast with the daily approach, the parameters could be reproduced between different sites 3) Constant approach, specifying values for soil

  11. Ecohydrologic Implications and Management of Post-fire Soil Water Repellency in Burned Pinon-Juniper Woodlands

    Science.gov (United States)

    Madsen, Matthew; Zvirzdin, Daniel; Fernelius, Kaitlynn; McMillan, Mica; Kostka, Stanley

    2014-05-01

    Erosion and weed dominance often limit the recovery of piñon-juniper woodlands of western North America after high intensity wildfires. Soil water repellency (SWR) is one factor that may promote overland flow and impede seedling establishment. In spite of these effects, the influence of post-fire SWR on site recovery is poorly understood. Our presentation summarizes data collected within studies on burned piñon-juniper woodlands that provide new insight on: 1) the spatial distribution and severity of SWR, 2) influence of SWR on soil hydrology, nitrogen cycling, and site revegetation, and 3) the suitability of soil surfactants as a post-fire restoration tool. We demonstrate how patterns of SWR are highly correlated to pre-fire woodland canopy structure. At sites where SWR is present, infiltration, soil water content, and plant establishment is significantly less than at non-hydrophobic sites. We show how newly developed soil surfactants can significantly improve ecohydrologic properties required for plant growth by overcoming SWR; thus, increasing the amount and duration of available water for seed germination and plant growth. However, the application of soil surfactants in wildfire-affected ecosystems has been limited due to logistical and economic constraints associated with the standard practice of using large quantities of irrigation water as the surfactant carrier. We have developed a potential solution to this problem by using seed coating technology to use the seed as the carrier for the delivery of soil surfactant. Through this approach, precipitation leaches the surfactant from the seed into the soil where it absorbs onto the soil particles and ameliorates water repellency within the seeds microsite. We present findings from laboratory and field evaluations of surfactant seed coatings, which provide evidence that it may be plausible for the technology to improve post-fire seeding efforts by restoring soil hydrologic function and increasing seedling

  12. Occurrence and spatial pattern of water repellency in a beech forest subsoil

    Directory of Open Access Journals (Sweden)

    Bachmann Jörg

    2016-06-01

    Full Text Available Most recent studies on soil water repellency (WR were limited to the humous topsoil or to shallow subsoil layers slightly below the main root zone to approximately 0.5 m depth. Hence, the main objective of the present study was to investigate the wettability pattern of a forest soil including the deeper subsoil. The selected site was a 100 years old beech forest on a well-drained sandy Cambisol in northern Germany which showed moderate to partly extended acidification. Results obtained from three sampling transects (3 m length, 2 m depth; sampling grid 8 × 8 samples per transect; minimum distance of sampling locations to nearest tree about 0.5 m show that contact angles (CA were always in the subcritical WR range (0° < CA < 90°. Significant impact of the tree distance on WR was not observed for any of the transects. A prominent feature of two transects was the minimum WR level (CA < 10° for samples with soil organic carbon (SOC contents around 0.25–0.4%. For the topsoils it was observed that CA increased with SOC content from that minimum to a maximum CA of 60–75° for transects 1 and 2 with mean pH values < 3.5. For transect 3 with slightly higher average pH close to 4.0, average CA of samples were always < 10° and showed no trend to increase with increasing SOC content or other soil parameters like N content or C/N ratio. Subsoil samples, however, behave differently with respect to SOC: for these samples, generally low in SOC, the CA increase with decreasing SOC occurred at all transects for approximately 50% of the samples but did not show any clear tendencies with respect to further parameters like texture, pH or N content. We conclude that the SOC content is the most prominent parameter determining wettability, either positively correlated with WR for topsoils or negatively correlated for subsoil samples very low in SOC. We finally conclude for moderately acid beech forest stands that emerging WR starts in the A horizon after

  13. Effects of Long-Term Water-Aging on Novel Anti-Biofilm and Protein-Repellent Dental Composite

    Directory of Open Access Journals (Sweden)

    Ning Zhang

    2017-01-01

    Full Text Available The aims of this study were to: (1 synthesize an anti-biofilm and protein-repellent dental composite by combining 2-methacryloyloxyethyl phosphorylcholine (MPC with quaternary ammonium dimethylaminohexadecyl methacrylate (DMAHDM; and (2 evaluate the effects of water-aging for 180 days on protein resistance, bacteria-killing ability, and mechanical properties of MPC-DMAHDM composite. MPC and DMAHDM were added into a resin composite. Specimens were stored in distilled water at 37 °C for 1, 30, 90, and 180 days. Mechanical properties were measured in three-point flexure. Protein attachment onto the composite was evaluated by a micro bicinchoninic acid approach. An oral plaque microcosm biofilm model was employed to evaluate oral biofilm viability vs. water-aging time. Mechanical properties of the MPC-DMAHDM composite after 180-day immersion matched those of the commercial control composite. The composite with 3% MPC + 1.5% DMAHDM had much stronger resistance to protein adhesion than control (p < 0.05. MPC + DMAHDM achieved much stronger biofilm-eradicating effects than MPC or DMAHDM alone (p < 0.05. Biofilm colony-forming units on the 3% MPC + 1.5% DMAHDM composite were three orders of magnitude lower than commercial control. The protein-repellent and antibacterial effects were durable and showed no loss in water-aging from 1 to 180 days. The novel MPC-DMAHDM composite possessed strong and durable resistance to protein adhesion and potent bacteria-eradicating function, while matching the load-bearing ability of a commercial dental composite. The novel MPC-DMAHDM composite represents a promising means of suppressing oral plaque growth, acid production, and secondary caries.

  14. Statistical design applied to hydric property behaviour for monitoring granite consolidation and/or water-repellent treatments

    Directory of Open Access Journals (Sweden)

    Rives, V.

    2006-03-01

    Full Text Available The suitability of granite conservation treatments (consolidation and/or water-repellency wide/y used to protect heritage structures was evaluated on the basis of the changes occurring in the intrinsic characteristics of the stone (imbibition capacity open porosity total water-accessible porosity water vapour permeability and capillar absorption coefficient. A statistical analysis conducted of the values obtained for these properties/ which showed differences in fluid flow through the rocks/ found that the application of consolidants followed by water repellency treatment was more effective than either procedure alone, substantially enhancing the properties of the stone from the standpoint of its use as a construction material.La adecuación de tratamientos de conservación (consolidación y/o hidrofugación realizados sobre granitos ampliamente utilizados en el patrimonio cultura se evaluó por los cambios experimentados en las características intrínsecas de estas rocas (capacidad de imbibición/ porosidad abierta/ porosidad total accesible al agua/ permeabilidad al vapor de agua y coeficiente de absorción capilar. Se realizó un análisis estadístico de los valores obtenidos de estas propiedades que muestra diferentes capacidades para el transporte de fluidos a través de las rocas/ indicando que el tratamiento con consolidantes y posterior aplicación de hidrofugantes tiene mayor efecto que los dos aplicados independientemente y mejora notablemente sus propiedades como material de construcción.

  15. Effects of Long-Term Water-Aging on Novel Anti-Biofilm and Protein-Repellent Dental Composite

    Science.gov (United States)

    Zhang, Ning; Zhang, Ke; Melo, Mary A. S.; Weir, Michael D.; Xu, David J.; Bai, Yuxing; Xu, Hockin H. K.

    2017-01-01

    The aims of this study were to: (1) synthesize an anti-biofilm and protein-repellent dental composite by combining 2-methacryloyloxyethyl phosphorylcholine (MPC) with quaternary ammonium dimethylaminohexadecyl methacrylate (DMAHDM); and (2) evaluate the effects of water-aging for 180 days on protein resistance, bacteria-killing ability, and mechanical properties of MPC-DMAHDM composite. MPC and DMAHDM were added into a resin composite. Specimens were stored in distilled water at 37 °C for 1, 30, 90, and 180 days. Mechanical properties were measured in three-point flexure. Protein attachment onto the composite was evaluated by a micro bicinchoninic acid approach. An oral plaque microcosm biofilm model was employed to evaluate oral biofilm viability vs. water-aging time. Mechanical properties of the MPC-DMAHDM composite after 180-day immersion matched those of the commercial control composite. The composite with 3% MPC + 1.5% DMAHDM had much stronger resistance to protein adhesion than control (p < 0.05). MPC + DMAHDM achieved much stronger biofilm-eradicating effects than MPC or DMAHDM alone (p < 0.05). Biofilm colony-forming units on the 3% MPC + 1.5% DMAHDM composite were three orders of magnitude lower than commercial control. The protein-repellent and antibacterial effects were durable and showed no loss in water-aging from 1 to 180 days. The novel MPC-DMAHDM composite possessed strong and durable resistance to protein adhesion and potent bacteria-eradicating function, while matching the load-bearing ability of a commercial dental composite. The novel MPC-DMAHDM composite represents a promising means of suppressing oral plaque growth, acid production, and secondary caries. PMID:28106774

  16. Influence of soil water repellency on infiltration into fine- to coarse-textured soils of burned and unburned rangeland ecosystems in the Great Basin, USA

    Science.gov (United States)

    Soil water repellency and its spatial and temporal variability have been documented for a range of soil types and plant communities. The magnitude of its influence on infiltration of rainfall however remains uncertain, particularly for rangeland landscapes in the western United States. Very little i...

  17. Occurrence, prediction and hydrological effects of water repellency amongst major soil and land-use types in a humid temperate climate

    NARCIS (Netherlands)

    Doerr, S.H.; Shakesby, R.A.; Dekker, L.W.; Ritsema, C.J.

    2006-01-01

    Knowledge of soil water repellency distribution, of factors affecting its occurrence and of its hydrological effects stems primarily from regions with a distinct dry season, whereas comparatively little is known about its occurrence in humid temperate regions such as typified by the UK. To address

  18. Evolution of water repellency of organic growing media used in Horticulture and consequences on hysteretic behaviours of the water retention curve

    Science.gov (United States)

    Michel, Jean-Charles; Qi, Guifang; Charpentier, Sylvain; Boivin, Pascal

    2010-05-01

    Most of growing media used in horticulture (particularly peat substrates) shows hysteresis phenomena during desiccation and rehydration cycles, which greatly affects their hydraulic properties. The origins of these properties have often been related to one or several of the specific mechanisms such as the non-geometrical uniformity of the pores (also called ‘ink bottle' effect), presence of trapped air, shrinkage-swelling phenomena, and changes in water repellency. However, recent results showed that changes in wettability during desiccation and rehydration could be considered as one of the main factors leading to hysteretic behaviour in these materials with high organic matter contents (Naasz et al., 2008). The general objective was to estimate the evolutions of changes in water repellency on the water retention properties and associated hysteresis phenomena in relation to the intensity and the number of drying/wetting cycles. For this, simultaneous shrinkage/swelling and water retention curves were obtained using method previously developed for soil shrinkage analysis by Boivin (2006) that we have adapted for growing media and to their physical behaviours during rewetting. The experiment was performed in a climatic chamber at 20°C. A cylinder with the growing medium tested was placed on a porous ceramic disk which is used to control the pressure and to full/empty water of the sample. The whole of the device was then placed on a balance to record the water loss/storage with time; whereas linear displacement transducers were used to measure the changes in sample height and diameter upon drying and wetting in the axial and radial directions. Ceramic cups (2 cm long and 0.21 cm diameter) connected to pressure transducers were inserted in the middle of the samples to record the water pressure head. In parallell, contact angles were measured by direct droplet method at different steps during the drying/rewetting cycles. First results obtained on weakly decomposed

  19. Rainfall simulation experiments and Water Drop Penetration Time measurements shed light on the impact of water repellency on soils under organic farming management in Eastern Spain

    Science.gov (United States)

    Cerdà, Artemi; González, Óscar; León, Javier; Jordán, Antonio

    2015-04-01

    Water repellency is a well-know soil property since the research of professor Stefan Helmut Doerr recovered and powered the research developed by professor DeBano (Atanassova and Doerr, 2011; ; Jordán et al., 2011; Bodí et al., 2012; González Peñaloza et al., 2012 Bodí et al., 2013; García Moreno et al., 2013; Jordán et al., 2013; Badía-Villas et al., 2014; Jordán et al., 2013; Jiménez Morillo et al., 2015). However, little is known about the impact of water repellency in surface runoff generation, although usually is accepted that when more soil water repellent is a soil, higher will be the surface runoff discharge (Stoff et al., 2011; Madsen et al., 2011; León et al., 2013; Lozano et al., 2013; Mataix-Solera et al., 2013; Santos et al., 2015). And the impact of the water repellency and then the higher surface wash discharge can trigger high erosion rates (Kröpfl et al., 2013; Mandal and Sharda 2013; Zhao et al., 2013). However these relationships were not demonstrated as the most water repellent soils are the one with high organic contents, and those soils do not have soil losses, probably due to the high infiltration rates due to the macropore flow. Rainfall simulation experiments can shed light in the runoff generation mechanism as they can control the rainfall intensity (Bodí et al., 2012; Iserloh et al., 2012; Iserloh et al., 2013), and inform about the main mechanism of the soil erosion process Cerdà and Jurgensen, 2011; Daugherty et al., 2011; Podwojewski et al., 2011; Dunkerley, 2012; Garel et al., 2012; Jouquet et al., 2012; Kibet et al., 2013; Butzen et al., 2014; Ma et al., 2014; Martínez Murillo et al., 2013). To determine the relationship between surface runoff generated under simulated rainfall (Cerdà, 1988a; 1988b; Cerdà et al., 1998; Ziadat and Taimeh, 2013) with a small rainfall simulator (0.25 m2) and water repellency measurements with the Water Drop Penetration time methods were done (Bodí et al., 2012). The results show that

  20. Micro-compartmentalized cultivation of cyanobacteria for mutant screening using glass slides with highly water-repellent mark

    Directory of Open Access Journals (Sweden)

    Sayuri Arai

    2014-12-01

    Full Text Available Photosynthetic microorganisms such as cyanobacteria have attracted attention for their potential to produce biofuels and biochemicals directly from CO2. Cell isolation by colony has conventionally been used for selecting target cells. Colony isolation methods require a significant amount of time for cultivation, and the colony-forming ratio is potentially low for cyanobacteria. Here, we overcome such limitations by encapsulating and culturing cells in droplets with an overlay of dodecane using glass slides printed with highly water-repellent mark. In the compartmentalized culture, the oil phase protects the small volume of culture medium from drying and increases the CO2 supply. Since a difference in cell growth was observed with and without the addition of antibiotics, this compartmentalized culture method could be a powerful tool for mutant selection.

  1. Sharks senses and shark repellents.

    Science.gov (United States)

    Hart, Nathan S; Collin, Shaun P

    2015-01-01

    Despite over 70 years of research on shark repellents, few practical and reliable solutions to prevent shark attacks on humans or reduce shark bycatch and depredation in commercial fisheries have been developed. In large part, this deficiency stems from a lack of fundamental knowledge of the sensory cues that drive predatory behavior in sharks. However, the widespread use of shark repellents is also hampered by the physical constraints and technical or logistical difficulties of deploying substances or devices in an open-water marine environment to prevent an unpredictable interaction with a complex animal. Here, we summarize the key attributes of the various sensory systems of sharks and highlight residual knowledge gaps that are relevant to the development of effective shark repellents. We also review the most recent advances in shark repellent technology within the broader historical context of research on shark repellents and shark sensory systems. We conclude with suggestions for future research that may enhance the efficacy of shark repellent devices, in particular, the continued need for basic research on shark sensory biology and the use of a multi-sensory approach when developing or deploying shark repellent technology.

  2. Temperature peaks affect fire-induced soil water repellency, infiltration and erosion risk of Mediterranean shrublands. Implications for water and sediment connectivity

    Science.gov (United States)

    Jordán, Antonio; Zavala, Lorena M.; Gordillo-Rivero, Ángel J.; Miriam, Miriam; Keesstra, Saskia; Cerdà, Artemi

    2017-04-01

    We know that the impact of fire on soil water repellency varies largely with the availability of water and physical and chemical soil properties, as well as the intensity of pre-existing hydrophobicity. However, there are few studies that relate the intensity of post-fire soil hydrophobicity and its persistence to the intensity and duration of thermal peaks occurring during fire. Fundamentally, this is due to the difficulty of quantifying these factors in situ, so that experimental fires are an extremely useful tool. The objective of this work was to study the impact of the intensity and duration of the thermal peaks observed during an experimental fire in the hydrophobicity of previously wet or slightly hydrophobic soils and the consequences of these changes on infiltration, runoff and soil loss (through rainfall simulation) in the immediate (30 days) and medium-term (1 year) post-fire period. In general, soil water repellency increased in all cases, although high temperatures and residence times of moderate thermal peaks caused the greatest impact. Although infiltration rates determined by mini-disk infiltrometer with water generally declined, no significant changes were observed in the same measurement with ethanol (which negates the effect of hydrophobicity).

  3. Long-term water repellency in organic olive orchards in the Cànyoles River watershed. The impact of land management

    Science.gov (United States)

    Cerdà, Artemi; González Pelayo, Óscar; García Orenes, Fuensanta; Jordán, Antonio; Pereira, Paulo; Novara, Agata; Neris, Jonay

    2015-04-01

    Soil water repellency is being researched in many enviroments of the world due to the fact that after two decades of intense investigations we found that soil water repellency is a soil property that can be found at any ecosystem (Atanassava and Doerr, 2011; Goebel et al., 2011; Mataix-Solera et al., 2013; Roper et al., 2013; Young et al., 2013; Badía-Villas et al., 2014; Jordán et al., 2014; Whelan et al., 2014). Soil water repellency inhibits or delays infiltration, encourage surface runoff but also the preferential flow in cracks and other macropores (Arye et al., 2011; Jordán et al., 2011; Madsen et al., 2011; Spohn and Rilling, 2012; García-Moreno et al., 2013; Hallin et al., 2013). Water repellency has been found in many soil types and it is present after forest fire, on forested land and also in agriculture soils (Granjed et al., 2013; Bodí et al., 2012; García Orenes et al., 2013; Jordán et al., 2012; Bodí et al., 2013; Dlapa et al., 2013; González-Peñaloza et al., 2012; López Garrido et al., 2012; León et al., 2013; Hewelke et al., 2014; Santos et al., 2014; Kröpfl et al., 2013). This paper show the measurements caried out by means of the water drop penetration time (WDPT) method in olive plantation in the Cànyoles watershed in Eastern Spain. Conservation practices applied such as no-tillage, manure addition, application of herbicides may contribute to increase soil organic matter and, hence, soil water repellency, and this is unknow under Mediterranean type ecosystems. The effect of long-term addition of plant residues and organic manure, no-tillage and no chemical fertilization (MNT), annual addition of plant residues and no-tillage (NT), application of conventional herbicides and no-tillage (H), and conventional tillage (CT) on soil water repellency in Mediterranean calcareous citrus-cropped soils (Eastern Spain) has been studied. Water repellency was observed in MNT soils, which may be attributed to the input of hydrophobic organic

  4. WIRE project- Soil water repellence in biodiverse semi arid environments: new insights and implications for ecological restoration

    Science.gov (United States)

    Muñoz-Rojas, Miriam; Jiménez-Morillo, Nicasio T.; Jordan, Antonio; Zavala, Lorena M.; Stevens, Jason; González-Pérez, Jose Antonio

    2017-04-01

    Background Soil water repellency (SWR) can have a critical effect on the restoration of disturbed ecosystems causing poor plant establishment and promoting erosion processes. Although SWR has been reported in most continents of the world for different soil types, climate conditions and land uses, there are still many research gaps in the knowledge of its causes and controlling factors (Doerr et al.,2000; Jordan et al., 2013), particularly in Mediterranean arid semi arid environments which are largely affected by this phenomenon. The WIRE project aims to investigate SWR in soils under different vegetation types of dominant biodiverse ecosystems of Western Australia (WA), e.g. hummock grasslands and Banksia woodlands, as well as characterizing organic compounds that induce hydrophobicity in these soils. Banksia woodlands (BW) are of particular interest in this project. These are iconic ecosystems of WA composed by an overstorey dominated by Proteaceae that are threatened by sand mining activities and urban expansion. Conservation and restoration of these woodlands are critical but despite considerable efforts to restore these areas, the success of current rehabilitation programs is poor due to the high sensitivity of the ecosystem to drought stress and the disruption of water dynamics in mature BW soils that result in low seedling survival rates (5-30%). The main objectives of this collaborative research are: i) to identify SWR intensity and severity under different vegetation types and evaluate controlling factors in both hummock grasslands and BW (ii) to characterize hydrophobic compounds in soils using analytical pyrolysis techniques and iii) to investigate the impact of SWR on water economy in relation with soil functioning and plant strategies for water uptake in pristine BW. Methods In a series of field trials and experimental studies, we measured SWR of soil samples under lab conditions in oven-dry samples (48 h, 105 °C) that were previously collected under

  5. Properties, performance and associated hazards of state-of-the-art durable water repellent (DWR) chemistry for textile finishing.

    Science.gov (United States)

    Holmquist, H; Schellenberger, S; van der Veen, I; Peters, G M; Leonards, P E G; Cousins, I T

    2016-05-01

    Following the phase-out of long-chain per- and polyfluoroalkyl substances (PFASs), the textile industry had to find alternatives for side-chain fluorinated polymer based durable water repellent (DWR) chemistries that incorporated long perfluoroalkyl side chains. This phase-out and subsequent substitution with alternatives has resulted in a market where both fluorinated and non-fluorinated DWRs are available. These DWR alternatives can be divided into four broad groups that reflect their basic chemistry: side-chain fluorinated polymers, silicones, hydrocarbons and other chemistries (includes dendrimer and inorganic nanoparticle chemistries). In this critical review, the alternative DWRs are assessed with regards to their structural properties and connected performance, loss and degradation processes resulting in diffuse environmental emissions, and hazard profiles for selected emitted substances. Our review shows that there are large differences in performance between the alternative DWRs, most importantly the lack of oil repellence of non-fluorinated alternatives. It also shows that for all alternatives, impurities and/or degradation products of the DWR chemistries are diffusively emitted to the environment. Our hazard ranking suggests that hydrocarbon based DWR is the most environmentally benign, followed by silicone and side-chain fluorinated polymer-based DWR chemistries. Industrial commitments to reduce the levels of impurities in silicone based and side-chain fluorinated polymer based DWR formulations will lower the actual risks. There is a lack of information on the hazards associated with DWRs, in particular for the dendrimer and inorganic nanoparticle chemistries, and these data gaps must be filled. Until environmentally safe alternatives, which provide the required performance, are available our recommendation is to choose DWR chemistry on a case-by-case basis, always weighing the benefits connected to increased performance against the risks to the

  6. Formation of post-fire water-repellent layers in Monterrey pine (Pinus radiata D. Don) plantations in south-central Chile

    Science.gov (United States)

    P. Garcia-Chevesich; R. Pizarro; C. L. Stropki; P. Ramirez de Arellano; P. F. Ffolliott; L. F. DeBano; Dan Neary; D. C. Slack

    2010-01-01

    A wildfire burned about 15,000 ha of Monterrey Pine (Pinus radiata D. Don) plantations near Yungay, Chile, in January of 2007. Post-fire water repellency (hydrophobicity) was measured using the water-drop-penetration-time (WDPT) method at depths of 0, 5, and 10 mm from the soil surface. These measurements were collected on burned sites of both young (4-years old) and...

  7. Biological soil crusts cause subcritical water repellency in a sand dune ecosystem located along a rainfall gradient in the NW Negev desert, Israel

    Directory of Open Access Journals (Sweden)

    Keck Hannes

    2016-06-01

    Full Text Available The biological soil crusts (BSCs in the NW Negev cause local water redistribution by increasing surface runoff. The effects of pore clogging and swelling of organic and inorganic crust components were intensively investigated in earlier studies. However, the effect of water repellency (WR was not addressed systematically yet. This study investigates subcritical WR of BSCs in three different study sites in the NW Negev. For this purpose, three common methods to determine soil WR were used: (i the repellency index (RI method (ii the water drop penetration time (WDPT test and (iii the Wilhelmy plate method (WPM. Furthermore, the potential influence of WR on local water redistribution is discussed and the applied methods are compared. We found the BSC to be subcritically water repellent. The degree of WR may only affect water redistribution on a microscale and has little influence on the ecosystem as a whole. The RI method was clearly the most appropriate to use, whereas the WDPT and the WPM failed to detect subcritical WR.

  8. Extremely stretchable and conductive water-repellent coatings for low-cost ultra-flexible electronics

    Science.gov (United States)

    Mates, Joseph E.; Bayer, Ilker S.; Palumbo, John M.; Carroll, Patrick J.; Megaridis, Constantine M.

    2015-11-01

    Rapid advances in modern electronics place ever-accelerating demands on innovation towards more robust and versatile functional components. In the flexible electronics domain, novel material solutions often involve creative uses of common materials to reduce cost, while maintaining uncompromised performance. Here we combine a commercially available paraffin wax-polyolefin thermoplastic blend (elastomer matrix binder) with bulk-produced carbon nanofibres (charge percolation network for electron transport, and for imparting nanoscale roughness) to fabricate adherent thin-film composite electrodes. The simple wet-based process produces composite films capable of sustained ultra-high strain (500%) with resilient electrical performance (resistances of the order of 101-102 Ω sq-1). The composites are also designed to be superhydrophobic for long-term corrosion protection, even maintaining extreme liquid repellency at severe strain. Comprised of inexpensive common materials applied in a single step, the present scalable approach eliminates manufacturing obstacles for commercially viable wearable electronics, flexible power storage devices and corrosion-resistant circuits.

  9. EFFECTS OF SOME BORON COMPOUNDS AND/OR WATER REPELLENTS ON THE HIGROSCOPICITY OF BRUTIA PINE (Pinus brutia Ten. WOOD

    Directory of Open Access Journals (Sweden)

    M. Kemal YALINKILIÇ

    1995-03-01

    Full Text Available As a water borne salt type, boron salts also tend to increase in hygroscopicity of wood. This phonomenon is known as one of the disadvantages of these salts in wood preservation in spite of their protective effectiveness against biological agents and fire. This study was designed to determine the rate of higroscopicity both treated and untreated Brutia pine wood. Impregnation solutions of boric acid (BA and sodium perborate (SP was prepared by water and polyethylene glycol (PEG-400 (P4. Additionally, some water repellents (WRs such as paraffin wax (P, styrene (St, methylmethacrylate (MMA and isocyanate (ISO were used to keep the hygroscopicity level of wood at an acceptable level. Results indicated that paraffin wax and WRs were considerably lowered the hygroscopicity of wood. 4 homogenity groups were formed from the statistical analysis as follows (from the most hygroscopic treatments to lesser, respectively: (1 P4, (2 P4+BA or SP, control, (3 WRs, BA or SP+WRs and, (4 P+BA+Bx (% 15 aqueous solution. None of the solutions increased the hygroscopicity of wood than control treatments, but P4 (P? 0.05.

  10. Fire impact on soil-water repellency and functioning of semi-arid croplands and rangelands: Implications for prescribed burnings and wildfires

    Science.gov (United States)

    Stavi, Ilan; Barkai, Daniel; Knoll, Yaakov M.; Glion, Hiam Abu; Katra, Itzhak; Brook, Anna; Zaady, Eli

    2017-03-01

    An unintended fire outbreak during summer 2015 in the semi-arid Israeli Negev resulted in the burning of extensive croplands and rangelands. The rangelands have been managed over the long term for occasional grazing, while the croplands have been utilized for rainfed wheat cropping. Yet, during the studied year, the croplands were left fallow, allowing the growth of herbaceous vegetation, which was harvested and baled for hay before the fire outbreak. The study objectives were to investigate the impacts of fire, land-use, and soil depth on water-repellency and on the status and dynamics of some of the most important organic and mineral soil resources. Additionally, we aimed to assess the severity of this fire outbreak. The soil-water repellency was studied by measuring the soil's water drop penetration time (WDPT) and critical surface tension (CST). A significant effect of fire on soil hydrophobicity was recorded, with a slight increase in mean WDPT and a slight decrease in mean CST in the burnt sites than in the non-burnt sites. Yet, soil hydrophobicity in the burnt lands was rather moderate and remained within the water repellency's lowest class. A significant effect of land-use on the means of WDPT and CST was also recorded, being eleven-fold greater and 7% smaller, respectively, in the rangelands than in the croplands. This is consistent with the almost eightfold greater mean above-ground biomass recorded in the non-burnt rangelands than in the non-burnt post-harvest croplands, revealing the positive relations between available fuel load and soil-water repellency. The effect of soil depth was significant for CST but not for WDPT. Overall, the gathered data suggest that fire severity was low to moderate. Fire was also found to significantly affect the burnings or wildfires.

  11. Growth of high-density ZnO nanorods on wood with enhanced photostability, flame retardancy and water repellency

    Science.gov (United States)

    Kong, Lizhuo; Tu, Kunkun; Guan, Hao; Wang, Xiaoqing

    2017-06-01

    Zinc oxide (ZnO) nanorod arrays were successfully assembled on the wood surface in situ via a two-step process consisting of formation of ZnO seeds and subsequent crystal growth under hydrothermal conditions at a low temperature. The morphology and crystalline structure of the formed ZnO nanorods were studied by field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). Highly dense and uniform arrays of ZnO nanorods with well-defined hexagonal facets were generated on the wood surface by tuning the concentration of the ZnO growth solution during the hydrothermal treatment. Accelerated weathering tests indicated that the assembled ZnO nanorod arrays were highly protective against UV radiation and greatly enhanced the photostability of the coated wood. Meanwhile, the ZnO nanorod-coated wood can withstand continuous exposure to flame with only minor smoldering in contrast with the pristine wood catching fire easily and burning rapidly. Moreover, when further modified with low-surface-energy stearic acid, the ZnO nanorod decorated wood surface can be transformed into a superhydrophobic surface, with a water contact angle (CA) of ∼154°. Such ZnO nanorod-modified woods with enhanced photostability, flame retardancy and water repellency offer an interesting alternative to conventional wood preservation strategies, highlighting their potential applications in some novel wood products.

  12. TMOS based water repellent silica thin films by co-precursor method using TMES as a hydrophobic agent

    Energy Technology Data Exchange (ETDEWEB)

    Latthe, Sanjay S.; Nadargi, Digambar Y. [Air Glass Laboratory, Department of Physics, Shivaji University, Vidyanagar, Kolhapur 416 004, Maharashtra (India); Venkateswara Rao, A. [Air Glass Laboratory, Department of Physics, Shivaji University, Vidyanagar, Kolhapur 416 004, Maharashtra (India)], E-mail: raouniv@yahoo.com

    2009-01-01

    The present paper describes the room temperature synthesis of dip coated water repellent silica coatings on glass substrates using trimethylethoxysilane (TMES) as a co-precursor. Silica sol was prepared by keeping the molar ratio of tetramethoxysilane (TMOS) precursor, methanol (MeOH) solvent, water (H{sub 2}O) constant at 1:29.27:2.09 respectively, with 0.5 M NH{sub 4}OH throughout the experiments and the TMES/TMOS molar ratio (M) was varied from 0 to 3.8. It was found that with an increase in M value, the roughness and hydrophobicity of the films increased, however the optical transmission decreased from 93% to 57% in the visible range. The hydrophobic silica films retained their hydrophobicity up to a temperature of 250 deg. C and above this temperature the films became hydrophilic. The hydrophobic silica thin films were characterized by taking into consideration the surface roughness studies, Fourier transform infrared (FT-IR) spectroscopy, percentage of optical transmission, scanning electron microscopy (SEM) and contact angle measurements.

  13. The effect of pH modification on wetting kinetics of a naturally water repellent coniferous soil

    Science.gov (United States)

    Amer, Ahmad; Diehl, Dörte; Schaumann, Gabriele

    2017-04-01

    The interfacial dynamics of soil-water interactions are significantly affected by the hydrophobic properties of organic matter. The underlying mechanisms responsible for the development of soil water repellency (SWR) are still under discussion. Various environmental factors control the appearance and degree of SWR. The wetting of soil greatly depends on the physicochemical characteristics of soil surfaces which in turn depends on pH. In this contribution, we propose a mechanism for the change in SWR that is observed upon the artificial change in soil pH. Wetting kinetics were studied by the time dependent sessile drop measurements (TISED) of the contact angle, the work of spreading and the drop base diameter as time elapsed under controlled relative humidity. Modification of pH strongly affected the wetting kinetics, suggesting maximum wetting resistance at the control pH (3.60) and with decreased wetting resistance as pH was changed in either direction. The enhancement of the wetting kinetics by artificial modification of soil pH can be attributed to the chemical modification in organic materials coating soil particles based on the magnitude of spreading activation energy and the hydrophilic/hydrophobic moieties ratio of treated soil samples measured by (XPS & MIR spectroscopy). On the basis of our current state of knowledge, we propose that acid and base catalyzed hydrolysis-condensation reactions as dominant processes responsible for the chemical nature of SWR.

  14. Improvement of water-repellent and hydrodynamic drag reduction properties on bio-inspired surface and exploring sharkskin effect mechanism

    Science.gov (United States)

    Luo, Yuehao; Liu, Yufei; Anderson, James; Li, Xiang; Li, Yuanyue

    2015-07-01

    Bio-inspired/biomimetic surface technologies focusing on sharkskin, lotus leaf, gecko feet, and others have attracted so lots of attentions from all over the world; meanwhile, they have also brought great advantages and profits for mankind. Sharkskin drag-reducing/low-resistance surface is the imperative consequence of nature selection and self-evolution in the long history, which can enable itself accommodate the living environments perfectly. Generally speaking, sharkskin effect can become transparent only in some certain velocity scope. How to expand its application range and enhance the drag reduction function further has developed into the urgent issue. In this article, the water-repellent and hydrodynamic drag-reducing effects are improved by adjusting sharkskin texture. The experimental results show that contact angle of more than 150° is achieved, and drag-reducing property is improved to some extent. In addition, the drag-reducing mechanism is explored and generalized from different aspects adopting the numerical simulation, which has important significance to comprehend sharkskin effect.

  15. Isolation of the combined water content and salinity effects on ERT measurement to locate the preferential flow pathways in water repellent soils

    Science.gov (United States)

    Brindt, Naaran; Rahav, Matan; Furman, Alex; Wallach, Rony

    2016-04-01

    Electrical resistivity tomography (ERT) has been used for measuring the dynamics of water flow in soils without disturbing the soil, and recently for identifying the preferential flow pathways that are reported to develop in water repellent soils. Since electrical resistivity is affected mainly by soil saturation and salinity, and given that in many cases salinity in the root zone reaches high values, the isolation of spatial and temporal distribution of water content or salinity in the root zone from ERT scans is a challenge. A model for transient variation of soil water content and salinity within a well-mixed soil unit was developed in the frame of this challenge. The model aims to isolate the temporal changes in water content from subsequent ERT scans. The model assumes that four stages of water dynamics occur in the root zone during an irrigation cycle: 1) Soil water content decreases by evapotranspiration - no irrigation, 2) Irrigation with saline water begins, water content increases but remains below field capacity - negligible drainage, 3) Irrigation continues and drainage starts as the water content becomes higher than field capacity, and 4) Irrigation stops, water content is higher than field capacity, and water content decreases by drainage and evapotranspiration. These four stages restart when drainage stops and water content decreases solely by evapotranspiration. The model was solved analytically and successfully applied to a series of sequential ERT scans accomplished during and between subsequent irrigation events for a soil that was rendered hydrophobic by olive trees irrigated with saline water, and a soil in a citrus orchard that was rendered hydrophobic by prolonged effluent irrigation. The suggested model helps in distinguishing between the temporal changes in water content and salinity within a given soil volume, locating the preferential plow pathways, and tracking the spatial and temporal salinity variation within the root zone during and

  16. 微咸水灌溉对斥水土壤水盐运移的影响%Effect of brackish water irrigation on water and salt movement in repellent soils

    Institute of Scientific and Technical Information of China (English)

    刘春成; 李毅; 郭丽俊; 关冰艺; 廖轶群; 王娟

    2011-01-01

    The existence of soil water-repellency had impacts on crop yields. In order to study soil water and salt movements of water-repellent soils irrigated by brackish water, laboratory soil column infiltration experiments were conducted. Impacts of different mineralization degrees and different water-repellency degrees on the movements of soil water and soil salt were compared for two soil textures. The variations of soil water-repellency during infiltration were also discussed. The results showed that infiltration ability of non-water-repellent soils increased with the increase of mineralization degrees. Both the infiltration rates of wettable and repellent soils could be simply fitted by Kostiakov equation. For the water repellent soils, the infiltration ability was largest at mineral degree of lg/L, but decreased with the increase of mineralization degree when mineralization degree were larger than lg/L. There was good linear relationship between cumulative infiltration and the wetting front distance when irrigated by brackish water. Soil water content and soil salt content at the same depth of the water repellent soil profiles were smaller than those of the wettable soil profiles. To some extent, soil water repellency was caused after irrigated by brackish water. This work indicated that brackish water irrigation had some impacts on distributions of soil water and soil salt as well as water-repellency of salinized soil.%土壤斥水性影响着作物的产量,为了研究微成水灌溉对斥水土壤水盐运移的影响,进行了室内土柱微咸水入渗试验.对比了不同矿化度和斥水程度对两种土质水盐运移的影响,探讨了微咸水入渗后土壤斥水性的变化特征.结果表明,不斥水土壤的入渗能力随矿化度的增加而增加.亲水和斥水土壤的入渗率均可采用Kostiakov公式简单模拟.斥水土壤入渗能力在矿化度为1g/L时达到最大,超过1 g/L后则随矿化度的增大而减小.微咸水入渗的

  17. Why do pigeon feathers repel water? Hydrophobicity of pennae, Cassie-Baxter wetting hypothesis and Cassie-Wenzel capillarity-induced wetting transition.

    Science.gov (United States)

    Bormashenko, Edward; Bormashenko, Yelena; Stein, Tamir; Whyman, Gene; Bormashenko, Ester

    2007-07-01

    Wetting of pigeon feathers has been studied. It was demonstrated that the Cassie-Baxter wetting regime is inherent for pigeon pennae. The water drop, supported by network formed by barbs and barbules, sits partially on air pockets. Small static apparent angle hysteresis justifies the Cassie-Baxter wetting hypothesis. A twofold structure of a feather favors large contact angles and provides its water repellency. Cassie-Wenzel transition has been observed under drop evaporation, when drop radius becomes small enough for capillarity-induced water penetration into the protrusions, formed by barbules.

  18. Toward a Long-Chain Perfluoroalkyl Replacement: Water and Oil Repellency of Polyethylene Terephthalate (PET) Films Modified with Perfluoropolyether-Based Polyesters.

    Science.gov (United States)

    Demir, Tugba; Wei, Liying; Nitta, Naoki; Yushin, Gleb; Brown, Philip J; Luzinov, Igor

    2017-07-19

    Original perfluoropolyethers (PFPE)-based oligomeric polyesters (FOPs) of different macromolecular architecture were synthesized via polycondensation as low surface energy additives to engineering thermoplastics. The oligomers do not contain long-chain perfluoroalkyl segments, which are known to yield environmentally unsafe perfluoroalkyl carboxylic acids. To improve the compatibility of the materials with polyethylene terephthalate (PET) we introduced isophthalate segments into the polyesters and targeted the synthesis of lower molecular weight oligomeric macromolecules. The surface properties such as morphology, composition, and wettability of PET/FOP films fabricated from solution were investigated using atomic force microscopy, X-ray photoelectron spectroscopy, and contact angle measurements. It was demonstrated that FOPs, when added to PET film, readily migrate to the film surface and bring significant water and oil repellency to the thermoplastic boundary. We have established that the wettability of PET/FOP films depends on three main parameters: (i) end-groups of fluorinated polyesters, (ii) the concentration of fluorinated polyesters in the films, and (iii) equilibration via annealing. The most effective water/oil repellency FOP has two C4F9-PFPE-tails. The addition of this oligomeric polyester to PET allows (even at relatively low concentrations) reaching a level of oil repellency and surface energy comparable to that of polytetrafluorethylene (PTFE/Teflon). Therefore, the materials can be considered suitable replacements for additives containing long-chain perfluoroalkyl substances.

  19. Impact of biocrust succession on water retention and repellency on open-cast lignite mining sites under reclamation in Lower Lusatia, NE-Germany

    Science.gov (United States)

    Gypser, Stella; Fischer, Thomas; Lange, Philipp; Veste, Maik

    2016-04-01

    Mining activities can strongly affect ecosystem properties by destruction of naturally developed soils and removal of vegetation. The unstructured substrates show high bulk densities, compaction, low water infiltration rates, reduced water holding capacities and higher susceptibility to wind and water erosion. In the initial stage of the ecosystem development, the post-mining sites are open areas without or with a low cover of higher vegetation. It is well-known that biocrusts are able to colonize the soil surface under such extreme conditions without human support and affect soil hydrological processes such as water infiltration, run-off or re-distribution. Investigations were conducted on two former lignite open-cast mining sites, an artificial sand dune on the reclaimed watershed Welzow "Neuer Lugteich" and a reforestation area in Schlabendorf (Brandenburg, north-east Germany). The aim was to relate the hydrological characteristics of the topsoil to successional stages of biological soil crusts on reclaimed soils and their influence on repellency index and water holding capacity compared to pure mining substrate. Our study emphasized the influence of changing successional stages and species composition of biological soil crusts, forming a small-scale crust pattern, on water repellency and retention on sandy soils in temperate climate. Different successional stages of soil crusts were identified from initial scattered green algae crusts, dominated by Zygogonium spec. and Ulothrix spec., and more developed soil crusts containing mosses such as Ceratodon purpureus and Polytrichum piliferum. Lichens of the Genus Cladonia were more pronouncedly contributed to biocrusts at later and mature stages of development. The repellency index on the one hand increased due to the cross-linking of sand particles by the filamentous green algae Zygogonium spec. which resulted in clogging of pores, and on the other hand decreased with the occurrence of moss plants due to absorption

  20. Aleppo pine afforestation in the Massis del Caroig, Eastern Spain. The impact on soil water repellency and infiltration rates.

    Science.gov (United States)

    Cerdà, Artemi; González Pelayo, Óscar; Jordán, Antonio; Mataix Solera, Jorge; Úbeda, Xavier

    2015-04-01

    Paloma Hueso and co-workers (2014; 2015) researched the impact of soil treatment on soil erosion and organic matter recovery in Mediterranean types ecosystems and they demonstrated that the surface wash and the soil quality is determined by the soil management. Afforestation and proper management with fertilizers, mulches and vegetation recovery, are common strategies to flight against soil erosion in Mediterranean type ecosystems García Orenes et al., 2010; Barbera et al., 2012; García Orenes et al., 2012; Mekuria and Aynekulu, 2013; Jiménez et al., 2015; Tengberg et al., 2015; Tesfaye et al., 2015). However, Hueso et al., (2014; 2015) did not paid attention to the impact that water repellency can trigger in the runoff generation and water repellency when soils increase the organic matter. In Eastern Spain, afforestation with Aleppo Pine (Pinus halepensis Mill.) was very popular during the XX century, although little is know about his impact on soil hydrology. Many of the impacts of afforestation were found positive (García et al., 2000; Maestre et al., 2003; Bellot et al., 2004; Maestre and Cortina, 2004; Chirino et al., 2006; Querejeta et al., 2008; ). This research shows the impact of Pinus halepensis Mill. on soil water repellency, in comparison to the natural scrubland and the cover of Quercus ilex. Within the El Teularet-Sierra de Enguera Experimental Station five types of vegetation covers were selected: Pinus halepensis, Quercus Ilex, Quercus coccifera, Rosmarinus officinalis, Thymus vulgaris and Brachypodium retusum. The Water Drop Penetration Time method (Cerda and Doerr; 2007; 2008) was applied. A hundred drops were applied at the soil surface, 1, 2, 5 and 10 cm depth 5 times along the year 2013 under different soil moisture content. The results show that the water repllency of the soils is: Pinus Pinus halepensis > Quercus coccifera > Rosmarinus officinalis > Quercus ilex > Thymus vulgaris > Brachypodium retusum. This is related to the higher

  1. Superhydrophobic meshes that can repel hot water and strong corrosive liquids used for efficient gravity-driven oil/water separation

    Science.gov (United States)

    Li, Jian; Kang, Ruimei; Tang, Xiaohua; She, Houde; Yang, Yaoxia; Zha, Fei

    2016-03-01

    Oil-polluted water has become a worldwide problem due to increasing industrial oily wastewater as well as frequent oil-spill pollution. Compared with underwater superoleophobic (water-removing) filtration membranes, superhydrophobic/superoleophilic (oil-removing) materials have advantages as they can be used for the filtration of heavy oil or the absorption of floating oil from water/oil mixtures. However, most of the superhydrophobic materials used for oil/water separation lose their superhydrophobicity when exposed to hot (e.g. >50 °C) water and strong corrosive liquids. Herein, we demonstrate superhydrophobic overlapped candle soot (CS) and silica coated meshes that can repel hot water (about 92 °C) and strong corrosive liquids, and were used for the gravity driven separation of oil-water mixtures in hot water and strong acidic, alkaline, and salty environments. To the best of our knowledge, we are unaware of any previously reported studies on the use of superhydrophobic materials for the separation of oil from hot water and corrosive aqueous media. In addition, the as-prepared robust superhydrophobic CS and silica coated meshes can separate a series of oils and organic solvents like kerosene, toluene, petroleum ether, heptane and chloroform from water with a separation efficiency larger than 99.0%. Moreover, the as-prepared coated mesh still maintained a separation efficiency above 98.5% and stable recyclability after 55 cycles of separation. The robust superhydrophobic meshes developed in this work can therefore be practically used as a highly efficient filtration membrane for the separation of oil from harsh water conditions, benefiting the environment and human health.Oil-polluted water has become a worldwide problem due to increasing industrial oily wastewater as well as frequent oil-spill pollution. Compared with underwater superoleophobic (water-removing) filtration membranes, superhydrophobic/superoleophilic (oil-removing) materials have advantages as

  2. Superhydrophobic meshes that can repel hot water and strong corrosive liquids used for efficient gravity-driven oil/water separation.

    Science.gov (United States)

    Li, Jian; Kang, Ruimei; Tang, Xiaohua; She, Houde; Yang, Yaoxia; Zha, Fei

    2016-04-14

    Oil-polluted water has become a worldwide problem due to increasing industrial oily wastewater as well as frequent oil-spill pollution. Compared with underwater superoleophobic (water-removing) filtration membranes, superhydrophobic/superoleophilic (oil-removing) materials have advantages as they can be used for the filtration of heavy oil or the absorption of floating oil from water/oil mixtures. However, most of the superhydrophobic materials used for oil/water separation lose their superhydrophobicity when exposed to hot (e.g. >50 °C) water and strong corrosive liquids. Herein, we demonstrate superhydrophobic overlapped candle soot (CS) and silica coated meshes that can repel hot water (about 92 °C) and strong corrosive liquids, and were used for the gravity driven separation of oil-water mixtures in hot water and strong acidic, alkaline, and salty environments. To the best of our knowledge, we are unaware of any previously reported studies on the use of superhydrophobic materials for the separation of oil from hot water and corrosive aqueous media. In addition, the as-prepared robust superhydrophobic CS and silica coated meshes can separate a series of oils and organic solvents like kerosene, toluene, petroleum ether, heptane and chloroform from water with a separation efficiency larger than 99.0%. Moreover, the as-prepared coated mesh still maintained a separation efficiency above 98.5% and stable recyclability after 55 cycles of separation. The robust superhydrophobic meshes developed in this work can therefore be practically used as a highly efficient filtration membrane for the separation of oil from harsh water conditions, benefiting the environment and human health.

  3. Fabrication of ZnO submicrorod films with water repellency by surface etching and hydrophobic modification

    Energy Technology Data Exchange (ETDEWEB)

    Hou Xianming, E-mail: xmhou@tsu.edu.cn [Department of Chemistry and Environmental Science, Taishan University, Taian 271021 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Wang Lixia [Department of Chemistry and Environmental Science, Taishan University, Taian 271021 (China); Zhou Feng [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Li Liqing [Department of Chemistry and Environmental Science, Taishan University, Taian 271021 (China)

    2011-09-01

    Superhydrophobic ZnO submicrorod films have been fabricated on zinc sheets through an H{sub 2}O{sub 2}-assisted surface etching process and subsequent surface modification with a monolayer of 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FDS). The crystal structure, chemical compositions, morphologies, and wettability of the resultant ZnO films were analyzed by means of X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and water contact angle measurements. It is found that the surface of the as-prepared ZnO films on zinc substrate was hydrophobic with a water contact angle of 95 {+-} 2 deg., whereas after modification with FDS, the film exhibited superhydrophobicity and the water CA increased to 154 {+-} 2 deg. It is shown that both the higher surface roughness and the lower surface free energy play an important role in creating the superhydrophobic films.

  4. Bug repellent safety

    Science.gov (United States)

    ... insect is gone. Alternative Names Insect repellent safety Images Bee sting References Fradin MS. Insect repellents. In: Wolverton SE, ed. Comprehensive Dermatologic Drug Therapy . 3rd ed. Philadelphia, PA: Elsevier Saunders; ...

  5. Water repellent finish of cotton fabrics with fluorine modified flax oil%棉织物的含氟改性亚麻油拒水整理

    Institute of Scientific and Technical Information of China (English)

    郑俊芝; 赵涛

    2011-01-01

    亚麻油经过一系列改性后与四氟丙醇反应,得到含氟酯类拒水剂,然后将其溶于乙酸乙酯中,并应用于棉织物拒水整理.通过测试整理棉织物的接触角、水滴消失时间、白度以及断裂强度,评价拒水剂的性能,得到适合的整理工艺条件为:二浸二轧拒水剂(80 g/L)→预烘(100℃,4min)→焙烘(180℃,3min).经过整理的棉织物接触角达到141°,水滴消失时间为6 480 s;20次水洗后,接触角仍保持在137°左右,耐皂洗效果较好.%A fluorine-contained ester is prepared by the reaction of modified flax soil and 2,2,3,3-tetrafluoropropanol, and then it is dissolved in ethyl acetate and applied to water repellent finish of cotton fabric. The property of the agent is evaluated by testing the contact angle, whiteness and breaking strength of the treated fabric. The optimum finish conditions are determined as follows: double dip-double nip (the concentration of water repellent agent is 80 g/L)→predrying (100 ℃,4 min) →curing (180 ℃, 3 min).The contact angel of the treated cotton fabric reaches 141° and the time of disappearance of water drop is 6 480 s. The treated fabric features fast water repellent effect to soaping and its contact angel remains 137°after 20 cycles of washing.

  6. An experimental study of the effects of water repellant treatment on the acoustic properties of Kevlar

    Science.gov (United States)

    Smith, C. D.; Parrott, T. L.

    1978-01-01

    The treatment consisted of immersing samples of Kevlar in a solution of distilled water and Zepel. The samples were then drained, dried in a circulating over, and cured. Flow resistance tests showed approximately one percent decrease in flow resistance of the samples. Also there was a density increase of about three percent. It was found that the treatment caused a change in the texture of the samples. There were significant changes in the acoustic properties of the treated Kevlar over the frequency range 0.5 to 3.5 kHz. In general it was found that the propagation constant and characteristic impedance increased with increasing frequency. The real and imaginary components of the propagation constant for the treated Kevlar exhibited a decrease of 8 to 12 percent relative to that for the untreated Kevlar at the higher frequencies. The magnitude of the reactance component of the characteristic impedance decreased by about 40 percent at the higher frequencies.

  7. Apparent Contact Angle Calculated from a Water Repellent Model with Pinning Effect.

    Science.gov (United States)

    Suzuki, Shojiro; Ueno, Kazuyuki

    2017-01-10

    A set of new theoretical equations for apparent contact angles is proposed. The equations are derived from an equilibrium of interfacial tensions of a three-phase contact line pinned at the edges of a fine structure. These equations are validated by comparison with contact-angle measurement results for 2 μL water droplets on poly(methyl methacrylate) microstructured samples with square pillars or holes. The equilibrium contact angles predicted by the new equations reasonably agree with the experimental results. In contrast, the values predicted by the Cassie-Baxter equation or the Wenzel equation do not qualitatively agree with the experimental results in pillar pattern cases because the Cassie-Baxter equation and the Wenzel equation do not account for the pinning effect.

  8. Occurrence, spatial pattern, and influence of atmospheric deposition on top- and subsoil water repellency in a beech forest

    Science.gov (United States)

    Bachmann, Joerg; Böttcher, Jürgen; Krüger, Jiem; Woche, Susanne K.

    2017-04-01

    It is well known that enhanced solute input due to stemflow infiltration causes enhanced soil acidification near the tree base. Infiltration-driven alteration of chemical soil properties like pH, and carbon to nitrogen ratio (C/N) may also affect soil wettability (quantified as contact angle, CA) with a trend to increased soil water repellency (SWR) with decreased pH. Objective of this study was to analyze the impact of tree location on top- and subsoil wettability and selected soil chemical parameters on two large-scale transects (length  50 m, sampling depths 0.1-0.2 m). The transects were about 50 m apart from each other, time of sampling was in July 2013 and July 2015. To analyze subsoil wettability in the vicinity of selected trees, three transects (lengths =3 m, sampling depths = 0.1 - 2.0 m) were additionally sampled in June 2013. Sampling site is a 100 years old beech forest (Fagus sylvatica L.). Soil type is a well-drained sandy Dystric Cambisol in northern Germany with moderate to locally extended acidification. According to standard statistics, the total variance of chemical soil properties and SWR was independent of stemflow infiltration pattern. Results of spectral variance analyses, however, showed that the spatial variability of acidification (pH, Al content) as well as SWR in the soil horizon close to the surface was strongly affected by the pattern of patches with and without stemflow infiltration on both large-distance transects, no matter if sampling took place in 2013 (mean CA = 40°, SD = 12°) or 2015 (mean CA = 110°, SD = 14°). Regarding subsoil wettability on the smaller transects, CA were always in the range 0° < CA < 90°. A significant impact of the distance to the tree on SWR was observed for none of the transects, indicating that the impact of tree canopy is restricted to surface-near soil layers. Specific chemical surface properties analyzed via X-ray photoelectron spectroscopy (XPS) showed specific chemical alteration of the

  9. The influence of fire history, plant species and post-fire management on soil water repellency in a Mediterranean catchment: the Mount Carmel range, Israel

    Science.gov (United States)

    Keesstra, Saskia; Wittenberg, Lea; Maroulis, Jerry; Malkinson, Dan; Cerdà, Artemi; Pereira, Paulo

    2016-04-01

    Fire is a key factor impacting soil hydrology in many Mediterranean catchments. Soil water repellency (SWR) can stimulate land degradation processes by reducing the affinity of soil and water thereby triggering a reduction in soil fertility and increasing soil and water losses (. The effects of two consequent fires (1989 and 2005) on SWR were assessed in the Carmel Mountains, Israel. Fire history, plant recovery and post-fire management were investigated as determining factors in a time dependent system. SWR was highest in the >50 years unburnt plots, where soil under Pinus halepensis is most hydrophobic. In the most disturbed soils (twice burnt), many sites have a low to absent SWR even if the soil is very dry. The dynamics and fluctuations in SWR differ in magnitude under different plant species. The areas treated with CC (chipping of charred trees) showed a much higher SWR than areas left untreated. From these insights, a conceptual model of the reaction of SWR on multiple fires was developed. KEYWORDS: Soil water repellency, WDPT, Wildfires, Vegetation recovery, post-fire management, Mediterranean.

  10. Adhesion and Water Repellent Properties Of Nascent Dammar—Silicone Thin Film: A Bio Mimicry Approach

    Science.gov (United States)

    Zakaria, R.; Ahmad, A. H.

    2009-06-01

    Dammar, a local plant resin (Dipterocaupacea sp) has been used in coating formulation to produce dammar-modified silicone resin. Dammar and silicone were mixed in various compositions and then were coated onto Aluminum Q-panel by using spin coating method and left to dry at room temperature. Adhesion property was investigated by using impact test and pull-off test. There were no significant damage and delaminations were observed at the panel coated with 15 wt.% of dammar that has undergone the impact test. Hence, the addition of more than 15 wt.% of dammar resulted in large delaminations and cracks on the coating materials. Results from pull off test also showed that 15 wt.% of dammar organic coating has strong adhesion, 108 Psi. It made 15 wt% as optimized composition. This optimized composition was added with nanopowder as rheological modifier or additive. Again the modified samples were undergone the impact and pull off test to study the effect of adhesiveness. Contact angle measurement of wettability test was also being carried out. The surface coated with dammar-silicone resin was found to be hydrophobic where the contact angle obtained was 70° for the sample containing 10 wt% of dammar. The additional of nanopowder into optimized composition exhibited more hydrophobic phenomenon which approached towards bio-mimicry behaviour, when water droplets simply rest on the surface without actually wetting the surface to any significant extent (hydrophobic) where the angle of wetting tests more than 90° have been achieved.

  11. Keeping a surface ice/frost free with electro-conducting water-repellent coatings

    Science.gov (United States)

    Das, Arindam; Kapatral, Shreyas; Megaridis, Constantine M.

    2013-11-01

    Ice/frost formation on aircraft, wind turbines, power grids, marine vessels, telecommunication devices, etc. has propelled scientific research on surfaces that facilitate the removal of the water solid phase or retard its formation. Superhydrophobic, self-cleaning surfaces have been investigated recently (Jung et al., Langmuir 2011) for their passive anti-icing properties. Although superhydrophobic surfaces have been shown to delay the onset of frosting and icing, they cannot prevent it entirely. Hence active deicing/defrosting approaches are required to keep surfaces free of ice/frost. Defrosting experiments have been carried out on glass substrates coated with textured polymeric nanocomposite films of different surface wettability, porosity and roughness. A strong influence of these parameters on condensation, condensation frosting and defrosting was observed. The coatings are electro-conducting, thus allowing skin heating at the interface between ice and the substrate. Sustained ice- and frost-free operation is demonstrated at substrate temperatures well below the freezing point and in humid ambient atmospheres. Supported by NSF Grant CBET-1066426.

  12. Enhancing water repellence and mechanical properties of gelatin films by tannin addition.

    Science.gov (United States)

    Peña, Cristina; de la Caba, Koro; Eceiza, Arantxa; Ruseckaite, Roxana; Mondragon, Iñaki

    2010-09-01

    In order to reduce pollution caused by traditional non-biodegradable plastic films, renewable raw materials from plants and wastes of meat industries have been employed in this work. A hydrolysable chestnut-tree tannin was used for gelatin modification. Films of gelatin and gelatin-tannin were obtained by casting at room conditions. Transition temperatures of both gelatin and gelatin-tannin systems were determined by differential scanning calorimetry (DSC). Glass transition temperatures of modified gelatin occurred at higher temperatures than for neat gelatin. Enthalpy and temperature of helix-coil transition decreased when tannin content increased due to variations in the helical structure of gelatin as a consequence of tannin presence in agreement with X-ray analysis. Mechanical and thermal behaviour varied as a function of the content of tannin, showing optimum values for films modified with 10 wt% tannin. The transparency of films was maintained after modification with tannin. Solubility and swelling tests of the films revealed that the presence of tannin reduced the water affinity of gelatin. (c) 2010 Elsevier Ltd. All rights reserved.

  13. Stocking rate impact on soil water repellency and erodibility of burnt lands

    Science.gov (United States)

    Stavi, Ilan; Zaady, Eli

    2017-04-01

    Wildfires and prescribed burnings are common, modifying the functioning of geo-ecosystems. Such fires have been extensively studied, and reported to considerably affect soil properties. Yet, understanding of the impact of livestock grazing, or more precisely, trampling, in fire-affected lands is limited. The objective of this study was to assess the impact of livestock trampling (hoof action) on the functioning of burnt vs. non-burnt lands. This was studied by focusing on the effects on wettability and related properties of solid soil, as well as on the quantity of unconsolidated material (detached matter) lying on the solid ground surface. The study was implemented in the semi-arid northern Negev of Israel, in lands which experienced a one cycle of (unintended) low- to moderate-fire severity. The study was conducted by allowing livestock to access plots under high, medium, and low stocking rates. Also, livestock exclusion plots were assigned as a control treatment. Soil wettability was studied by water drop penetration time (WDPT) and critical surface tension (CST) tests. Results show that fire slightly decreased the soil wettability. However, WDPT was negatively related to the stocking rate, and CST was 13% smaller in the control plots than in the livestock-presence treatments. Also, the results show that following burning, the resistance of soil to shear decreased by 70%. Mass of unconsolidated material was similar in the control plots of the burnt and non-burnt plots. At the same time, it was three-, eight-, and nine- fold greater in the plots of the burnt × low, burnt × medium, and burnt × high stocking rates, respectively, than in the corresponding non-burnt ones. This study shows that livestock trampling in low- to moderate-intensity fire-affected lands increases the shearing of the ground surface layer. On the one hand, this increases soil wettability. On the other hand, this impact considerably increases risks of on-site soil erosion and land

  14. Water repellent spray-type encapsulation of quantum dot light-emitting diodes using super-hydrophobic self-assembled nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Han, Junebeom; Bong, Jihye; Lim, Taekyung [Department of Physics, Kyonggi University, Suwon, Gyeonggi-Do, 443-760 (Korea, Republic of); Lee, Ki-Heon; Yang, Heesun [Department of Materials Science and Engineering, Hongik University, Seoul, 121-791 (Korea, Republic of); Ju, Sanghyun, E-mail: shju@kgu.ac.kr [Department of Physics, Kyonggi University, Suwon, Gyeonggi-Do, 443-760 (Korea, Republic of)

    2015-10-30

    Graphical abstract: - Highlights: • A spray-type encapsulation method capable of being applied to flexible and concave/convex substrates has been demonstrated to have no negative effect on the luminance and efficiency of QD-LEDs. • The highly dense thin-film provided by SAM-NP encapsulation can increase the effective lifetime of QD-LED devices by a factor of 16. • The QD-LEDs with SAM-NP encapsulation were found to have an effective lifetime in ambient air and a stable light emission in water. - Abstract: We have developed a spray-type encapsulation method for quantum dot light-emitting diode (QD-LED) displays designed to prevent the penetration of oxygen and moisture in ambient air and repel water. The non-wettability and oxygen/moisture repellency afforded by the super-hydrophobic (contact angle of ∼158°) self-assembled Al{sub 2}O{sub 3} nanoparticles (SAM-NP) is attributed to a reduction in the number of defects sites such as pin-holes or cracks during the formation of the thin-film. The QD-LEDs with SAM-NP encapsulation were found to have an effective lifetime in ambient air and a stable light emission in water compared to those of equivalent QD-LEDs without encapsulation.

  15. Soil-Water Repellency and Critical Humidity as Cleanup Criteria for Remediation of a Hydrocarbon Contaminated Mud

    Science.gov (United States)

    Guzmán, Francisco Javier; Adams, Randy H.

    2010-05-01

    The majority of soil remediation programs focus mainly on reducing the hydrocarbon concentration, based on the assumption that the primary impact is toxicity and/or leachates and that these are directly proportional to concentration. None-the-less, interference with natural soil-water interactions are frequently more damaging, especially for sites contaminated with very viscous, weathered hydrocarbons. Therefore, the kind of hydrocarbons present in the soil and their interactions with soil surfaces may be more important than the overall hydrocarbon concentration in terms of soil restoration. One recently patented technology, the Chemical-Biological Stabilization process, focuses specifically on restoring soil fertility as the main objective for remediation of sites with agricultural use. This method was recently validated at an industrial scale by the treatment of 150 cubic meters of bentonitic drilling muds (70,5% fines) from an old sulphur mine, which were contaminated with very weathered oil (4° API), consisting of 31% asphaltenes. This material was treated by adding 4% (w/w, dry) of calcium hydroxide, followed by 4% (w/w, dry) of sugar cane cachasse (a fine fibered agricultural waste), thoroughly mixing between additions using an excavator. After the soil had dried sufficiently and the pH was soil water repellency. MED was measured on air dried soil and WDPT values were calculated from the extrapolation of penetration time vs. ethanol molarity functions (Rx=0,99). Additionally, water penetration times were measured at different humidities to determine critical moisture levels for absorption in soil humic substances while a vigorous vegetative growth was established. During two years of treatment the MED values were reduced 30% from 5,13 to 3,58M, and WDPT values were reduced over 25 times (from 10 exp5,6 s to 10 exp4,2 s). Critical humidity values varied from ~16,9 - 19,5%H for penetration in soil humidity was 20,3%, and thus values below the critical levels

  16. Development of water-repellent organic–inorganic hybrid sol–gel coatings on aluminum using short chain perfluoro polymer emulsion

    Energy Technology Data Exchange (ETDEWEB)

    Wankhede, Ruchi Grover, E-mail: 123.ruchi@gmail.com [IITB-Monash Research Academy, Mumbai 400076 (India); Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai 400076 (India); Morey, Shantaram [Dow Chemicals (India); Khanna, A.S. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai 400076 (India); Birbilis, N. [Department of Materials Engineering, Monash University, Victoria 3800 (Australia)

    2013-10-15

    The development of an organic–inorganic sol–gel coating system (thickness ∼ 2 μm) on aluminum is reported. The coating uses glycidoxytrimethoxysilane (GPTMS) and methyltrimethoxysilane (MTMS) as silane precursors, crosslinked with hexamethylmethoxymelamine (HMMM) and followed by hydrophobic modification using a water base short chain per-fluoro emulsion (FE). Such coating resulted in enhanced hydrophobicity with a contact angle of about 120° and sliding angle of 25° for a 20 μL water droplet. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements showed reduced corrosion upon coated substrates than the bare; correlated with both a higher degree of water repellency and formation of low permeable crosslinked sol–gel network. The structure of the coatings deposited was analyzed using Fourier transform infrared (FTIR) and X-ray photoelectron (XPS) spectroscopy, revealing replacement of hydrophillic surface hydroxyls groups with low energy per-fluoro groups.

  17. Experimental Study on the Infiltration Laws of Water-Repellent Soils Based on Alcohol Solution%酒精溶液对斥水土壤入渗规律的试验研究

    Institute of Scientific and Technical Information of China (English)

    刘春成; 李毅

    2012-01-01

    Comparative infiltration experimental study based on the 2 soils of different water-repellency degrees was conducted.Indoors soil column experiment were used to carry out the experiment of ponding infiltration to compare the variations of infiltration volumes and infiltration rates versus time of 2 soils in different water-repellency degrees,applicability of Kostiakov equation in water-repellent soils based on the alcohol infiltration was tested,the fitted relations of infiltration versus t-1/2 were explored,as well as distributions of total salt and Cl-contents in the profiles were researched.Results showed that the existence of soil water-repellency has some obvious impacts on the soil infiltration property,but variations of the infiltration capacity among water-repellent soils of different water-repellent degrees,and the infiltration capacity in water-repellent soils was lower than one in wettable soils;the rinsed results of total salt and Cl-were more obvious in water-repellent soils that those in wettable soils,and the maximum was reached at the wetting front;applicability of Kostiakov equation was well about the variations of the infiltration rates versus time;there was good exponential relationship between infiltration rates and t-1/2.The study showed that the existence of soil water-repellency affected alcohol solution infiltration,but water-repellent soil infiltrations of different water-repellent degrees were not influenced by alcohol solution.The process of infiltration based on alcohol solution was accelerated greatly compared to distilled water infiltration.%采用室内土柱积液入渗试验,进行了不同斥水程度的2种土质的酒精溶液和蒸馏水的对比入渗试验研究,对比了不同斥水程度的土壤累积入渗量和入渗率随时间的变化,验证了Kostiakov公式在斥水土壤酒精溶液入渗的适应性,探索了i与t-1/2的拟合关系,以及全盐量和氯离子的剖面分布。结果表明,酒精入渗条件下,

  18. Pile burning effects on soil water repellency, infiltration, and downslope water chemistry in the Lake Tahoe Basin, USA

    Science.gov (United States)

    Ken Hubbert; Matt Busse; Steven Overby; Carol Shestak; Ross Gerrard

    2015-01-01

    Thinning of conifers followed by pile burning has become a popular treatment to reduce fuel loads in the Lake Tahoe Basin. However, concern has been voiced about burning within or near riparian areas because of the potential effect on nutrient release and, ultimately, lake water quality. Our objective was to quantify the effects of pile burning on soil physical and...

  19. Exploring functional relationships between post-fire soil water repellency, soil structure and physico-chemical properties

    Science.gov (United States)

    Quarfeld, Jamie; Brook, Anna; Keestra, Saskia; Wittenberg, Lea

    2016-04-01

    Soil water repellency (WR) and aggregate stability (AS) are two soil properties that are typically modified after burning and impose significant influence on subsequent hydrological and geomorphological dynamics. The response of AS and soil WR to fire depends upon how fire has influenced other key soil properties (e.g. soil OM, mineralogy). Meanwhile, routine thinning of trees and woody vegetation may alter soil properties (e.g. structure and porosity, wettability) by use of heavy machinery and species selection. The study area is situated along a north-facing slope of Mount Carmel national park (Israel). The selected sites are presented as a continuum of management intensity and fire histories. To date, the natural baseline of soil WR has yet to be thoroughly assessed and must be investigated alongside associated soil aggregating parameters in order to understand its overall impact. This study examines (i) the natural baseline of soil WR and physical properties compared to those of disturbed sites in the immediate (controlled burn) and long-term (10-years), and (ii) the interactions of soil properties with different control factors (management, surface cover, seasonal-temporal, burn temperature, soil organic carbon (OC) and mineralogy) in Mediterranean calcareous soils. Analysis of surface soil samples before and after destruction of WR by heating (200-600°C) was implemented using a combination of traditional methods and infrared (IR) spectroscopy. Management and surface cover type conditioned the wettability, soil structure and porosity of soils in the field, although this largely did not affect the heat-induced changes observed in the lab. A positive correlation was observed along an increasing temperature gradient, with relative maxima of MWD and BD reached by most soils at the threshold of 400-500°C. Preliminary analyses of soil OC (MIR) and mineralogical composition (VIS-NIR) support existing research regarding: (i) the importance of soil OC quality and

  20. RF-PACVD of water repellent and protective HMDSO coatings on bell metal surfaces: Correlation between discharge parameters and film properties

    Energy Technology Data Exchange (ETDEWEB)

    Choudhury, A.J. [Materials Science Division, Institute of Advanced Study in Science and Technology, Paschim Boragaon, Guwahati 781035, Assam (India); Barve, S.A. [Laser and Plasma Technology Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085 (India); Chutia, Joyanti, E-mail: joyanti_c@sify.com [Materials Science Division, Institute of Advanced Study in Science and Technology, Paschim Boragaon, Guwahati 781035, Assam (India); Pal, A.R. [Materials Science Division, Institute of Advanced Study in Science and Technology, Paschim Boragaon, Guwahati 781035, Assam (India); Kishore, R. [Material Science Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085 (India); Jagannath [Technical Physics and Prototype Engineering Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085 (India); Pande, M. [High Pressure Physics Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085 (India); Patil, D.S. [Laser and Plasma Technology Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085 (India)

    2011-08-01

    Hexamethyldisiloxane (HMDSO) films have been deposited on bell metal using radiofrequency plasma assisted chemical vapor deposition (RF-PACVD) technique. The protective performances of the HMDSO films and their water repellency have been investigated as a function of DC self-bias voltage on the substrates during deposition. Plasma potential measurements during film deposition process are carried out by self-compensated emissive probe. Optical emission spectroscopy (OES) analyses of the plasma during deposition reveal no significant change in the plasma composition within the DC self-bias voltage range of -40 V to -160 V that is used. Raman and X-ray photoelectron spectroscopy (XPS) studies are carried out for film chemistry analysis and indicate that the impinging ion energy on the substrates influences the physio-chemical properties of the HMDSO films. At critical ion energy of 113 qV (corresponding to DC self-bias voltage of -100 V), the deposited HMDSO film exhibits least defective Si-O-Si chemical structure and highest inorganic character and this contributes to its best corrosion resistance behavior. The hardness and elastic modulus of the films are found to be bias dependent and are 1.27 GPa and 5.36 GPa for films deposited at -100 V. The critical load for delamination is also bias dependent and is 11 mN for this film. The water repellency of the HMDSO films is observed to be dependent on the variation in surface roughness. The results of the investigations suggest that HMDSO films deposited by RF-PACVD can be used as protective coatings on bell metal surfaces.

  1. Water and Oil Repellent Finishing of Textiles by UV Curing: Evaluation of the Influence of Scaled-Up Process Parameters

    Directory of Open Access Journals (Sweden)

    Franco Ferrero

    2017-04-01

    Full Text Available In this work, various textile fabrics were coated with silicone and fluorocarbon-based resins by photo-curing using ultraviolet irradiation. A great number of large fabric samples were impregnated by padding with commercial finishing agents and then irradiated in air with a high power, semi-industrial UV source. The add-on of various finishing agents was kept low to reduce the treatment cost. White and dyed samples of different textile composition were treated and evaluated in terms of conferred repellency, yellowing, or color changes. Most relevant process parameters were investigated, utilizing the thermal process normally adopted at industrial level as reference. The results were statistically evaluated by ANOVA using Minitab 16 software, in order to identify the most influential parameters and to evaluate the real possibility of replacing the thermal treatment with UV curing.

  2. Repellency Awareness Graphic

    Science.gov (United States)

    Companies can apply to use the voluntary new graphic on product labels of skin-applied insect repellents. This graphic is intended to help consumers easily identify the protection time for mosquitoes and ticks and select appropriately.

  3. Small-scale soil water repellency in pine rizhosphere associated with ectomycorrhiza is affected by nutrient patchiness: a soil microcosms study

    Science.gov (United States)

    Lozano, Elena; Hallett, Paul; Johnson, David; Moore, Lucy; Mataix-Solera, Jorge; Jiménez-Pinilla, Patricia; Arcenegui, Victoria

    2014-05-01

    Soil water repellency (SWR) or hydrophobicity has been commonly related to organic compounds released from the roots or decomposition of different plant species (Doerr et al., 2000). In addition, fungi and microorganisms that are associated with specific plants, could also influence SWR through the production of exudates or cellular material that form hydrophobic coatings on soil surfaces (Feeney et al., 2004; Hallett and Young, 1999) or act as surfactants. Nutrient availability, microbial biomass, organic matter and specific exudates have all been associated with the development of SWR. In terms of plant productivity, these impacts can be significant as their interaction with pore structure changes at the root-soil interface regulates both water transport and storage (Sperry et al., 1998). In boreal forests, basidiomycetous fungi are known to have a large impact on the development of SWR. These fungi are important degraders of organic material and symbionts forming ectomycorrhizal fungi (EF) associations with trees. Although many researchers have suggested a strong positive impact of EF on the ability of plants to capture water from soils, their impact on SWR at the root-soil interface and spatially within soil with a patchy nutrient distribution has not yet been investigated. This study used microcosms with mycelia systems of the EF extending from Pinus sylvestris host plants. Each microcosm was incubated during 15 days and contained plastic cup with 33P under the roots. The transfer of P from the mycelium to the host plant was monitored using a radioactive tracers and a non-destructive electronic autoradiography system in another study (data not published). SWR was measured using different approaches; as repellency index, R using a microinfiltrometer with a contact radius of 0.1 mm (modified from Hallet et al., 2002) and with the water drop penetration time test (WDPT). Sorptivity and SWR were measured between 40-50 points/microcosms. Results obtained with both

  4. Synthesis and Application of Fluorine-Containing Silicone Water-Repellent Finishing Agent%含氟有机硅拒水整理剂的合成及应用

    Institute of Scientific and Technical Information of China (English)

    袁京; 李战雄; 樊丹

    2013-01-01

    Mixed cyclosiloxane was prepared by catalytic condensation, with tridecafluorooctyloxa-propylmethyldichlorosilane and dimethyldichlorosilane as raw materials. Fluorine-containing silicone water-repellent finishing agent was prepared by ring-opening polymerization, with divinyl tetramethyl disiloxane as blocking agent. Three different fluorine content of fluorine-containing silicones were synthesized, and the hydrogen silicone as crosslinker was applied to water repellent finishing of cotton fabric. The structural properties of products were characterized by FT-IR and 1H-NMR. The effect of finishing efficiency on the type and amount of finishing agent was studied. The results show that the water-repellent effect of cotton fabrics is significant after finished with the water-repellent finishing agent. When the concentration is 15g/L, the water repellency rating can be up to five Level. Compared with the methyl silicone finishing agent, the water repellency and washability of the cotton fabric finished by the fluorine-containing silicone finishing agent are better.%以十三氟辛氧丙基甲基二氯硅烷和二甲基二氯硅烷为原料,通过催化缩合制备了混合环硅氧烷,再加入四甲基二乙烯基二硅氧烷作为封端剂,通过开环聚合制备了3种不同氟含量的氟硅拒水整理剂,并以氢基硅油作交联剂应用于棉织物整理.通过红外光谱(FT-IR)和核磁共振(1H-NMR)表征了产物的结构,研究了整理剂的种类及用量对整理效果的影响.结果表明,该拒水整理剂对棉织物的拒水效果明显,当浓度为15 g/L时,拒水等级均可达到5级.与甲基有机硅整理剂相比,含氟有机硅整理剂整理后的棉织物具有更好的拒水性和耐洗性.

  5. Short-term effects of prescribed fire for pasture management on soil water repellency in the Central Pyrenees (NE-Spain)

    Science.gov (United States)

    Girona García, Antonio; María Armas-Herrera, Cecilia; Martí-Dalmau, Clara; Badía-Villas, David; Ortiz-Perpiñán, Oriol

    2016-04-01

    The decrease of livestock grazing during the last decades in the Central Pyrenees has led to a regression of grasslands in favour of shrublands, mainly composed by Echinospartum horridum. Prescribed burning might be a suitable tool for the control of this species that limits pastures development and therefore, the reclamation of grasslands; although, its effects on soil properties are still uncertain [1]. Controlled burnings are usually performed in spring or autumn, when soil moisture is high and temperature low, being easier to control and also reducing its effects on soil properties. However, burning during the wet seasons can increase the risk of soil erosion as the vegetation cover is partially destroyed. In this sense, soil water repellency (SWR) plays an important role reducing the infiltration rates and, thus, increasing runoff and soil erosion [2]. Then, it is of special interest to study parameters that influence SWR such as soil moisture, soil organic carbon (SOC) content and soil biological activity [3]. The aim of this work is, to analyse the effects of controlled burning on SWR as well as some of the influencing factors on this parameter. To achieve this, soil sampling was carried out in two prescribed fire events that took place in the Central Pyrenees: Tella (April, 2015) and Buisán (November, 2015). Temperature was simultaneously recorded during the fire via thermocouples placed at the surface level and at 1 cm, 2 cm and 3 cm depth. In each event, topsoil was scrapped and sampled from 0-1 cm, 1-2 cm and 2-3 cm depth in each sampling point (3 for Tella and 4 for Buisán) just before and immediately after burning. We analysed SWR persistence (Water Drop Penetration Time, WDPT) and intensity (Ethanol Percentage Test, EPT) as well as total C and N, microbial C, β-glucosidase activity, soil moisture and pH. Temperature measurements indicated a higher fire intensity in Tella than in Buisán burning. Surface unburned samples presented extreme SWR values

  6. Soil Water Repellency of Sands and Clay as Affected by Particle Size%砂土和黏土的颗粒差异对土壤斥水性的影响

    Institute of Scientific and Technical Information of China (English)

    杨松; 吴珺华; 董红艳; 张燕明

    2016-01-01

    斥水性土壤广泛存在于自然界中,并且对土壤环境和作物生长等有重要影响。建立理想化的土壤颗粒模型对砂土和黏土的斥水特性进行计算分析。结果表明:当接触角很小时,砂土中不存在斥水现象。随着接触角的增大,砂土斥水性与含水率密切相关,砂土的密实度对其斥水性也有重要影响,当砂土比较密实时,土壤的“亲水”与“斥水”特性对含水率特别敏感,随着含水率的变化,砂土可能由亲水性较好的土壤转变为斥水性土壤;当砂土比较松散时,土壤颗粒的斥水性对含水率并不敏感。当黏土接触角略小于90°且湿润半径b也较小时,黏土也存在斥水现象。如果黏土颗粒的接触角较小或接触角小于90°且湿润半径b较大,黏土总是亲水的。黏土含水率较大时,斥水特性由土壤颗粒的接触角决定。%Water-repellent soils,existing widely in nature,have some important effects on soil environment and crop growth. In order to analyze water repellency of sand and clay,models of sand and clay different in particle size were built. Results showed that no phenomenon of water repellency was found in sand soil when the contact angle of water with sand was small. Water repellency of sand soil was closely related to soil water content when the sand-water contact angle was big. Compactness of the soil was another important factor affecting soil water repellency. When the sand soil was highly compacted,whether the soil was hydrophilic or hydrophobic was very sensitive to water content,and it might switch from one state to another with changing soil water content. When the sand soil was quite loose,it was no longer sensitive to soil water content. In clay soil with soil-water contact angle being slightly less than 90°and wetting radius b being small,the phenomenon of water repellency was observed. But when the clay soil was much smaller than 90°in soil-water and

  7. Preparation of water repellent agent of branched polysiloxane modified silica sols and its application%支链有机硅改性硅溶胶拒水剂的制备与应用

    Institute of Scientific and Technical Information of China (English)

    张春梅; 杨保栋; 王利民

    2013-01-01

    The branched silicone-modified silica sol water repellent is prepared by sol-gel method with KH-550, KH-560 and ep-oxy-modified polysiloxane as raw materials and dibutyl tin dilaurate as catalyst, and is applied to cotton fabric. The structure and performance of water repellent are characterized by FT-IR, TGA, particle size, contact angle and water absorption. Influences of agent dosage and curing temperature on water repellency are discussed. The finishing conditions are optimized as 0.8% of water repellent and curing temperature 120 ℃. The contact angle of finished fabric can reach 133.8°.%以环氧硅油、氨丙基三乙氧基硅烷(KH550)和3-缩水甘油醚氧丙基三甲氧基硅烷(KH560)为原料,以二丁基二月桂酸锡为催化剂,通过溶胶-凝胶法制备了支链有机硅改性硅溶胶型拒水剂,并将其应用于棉织物.通过测试分析傅里叶红外光谱、热失重、粒径、接触角和吸水率,对拒水剂的结构和拒水性能进行表征;考察了拒水剂用量、焙烘温度对织物拒水性能的影响,得出优化的整理条件为:拒水剂0.8%、焙烘温度120℃.整理后织物与水的接触角可达133.8°,表明支链有机硅改性的硅溶胶具有良好的拒水效果.

  8. Synthesis and application of flame retardant and water repellent coating agent NPSi-FR%阻燃-拒水涂层剂NPSi-FR的制备与应用

    Institute of Scientific and Technical Information of China (English)

    李强林; 黄方千; 刘妙丽; 冯西宁; 任建华

    2012-01-01

    NPSi-FR, a flame retardant and water repellent coating agent with -NCO reactive group, is prepared using hydroxyl phosphate, diisocyanate, triol, and epoxy silane as raw materials by selective reaction. Flame retardant finish of PET/cotton blends is carried out with NPSi-FR and crosslinker PEG. The optimum finish process is NPSi-FR 210 g/L,PEG-400 120 g/L , sodium alginate 60 g/L, curing at 140 ℃ The treated fabric features excellent flame retardant property with LOI27.6%, water contact angle 115°, and little strength loss and whiteness loss.%以羟基磷酸酯、二元异氰酸酯、三元醇和环氧基硅烷为原料,通过选择性反应制备了含有-NCO活性基的阻燃-拒水涂层剂NPSi-FR,并与交联剂PEG一起用于涤棉织物的阻燃整理.优化的整理工艺为:NPSi-FR 210g/L,PEG-400 120 g/L,海藻酸钠60g/L,焙烘温度140℃.织物整理后的极限氧指数为27.6%,接触角为115°,耐水洗性能较好,但白度和拉伸性能略有下降.

  9. Potential for Recycling Nutrients from Biosolids Amended with Clay and Lime in Coarse-Textured Water Repellence, Acidic Soils of Western Australia

    Directory of Open Access Journals (Sweden)

    Sanjutha Shanmugam

    2015-01-01

    Full Text Available Application of biosolids in soils is an efficient method of recycling nutrients from biosolids and it is considered even safer when it is modified after mixing and diluting with other suitable soil organic amendments. A variety of soil organic amendments, such as green manures and composts, are used for modifying and co-composting with biosolids. However, these may not be considered as appropriate biosolids disposal and remedial measures for soils with unique problems such as low soil pH, water repellence nature, and poor water and nutrient retention capacities due to soil textural issues. Historically, soil amendments such as lime, clay, and recently biochar are being applied for such problematic soils at Western Australia and these researches focused mostly on improvement in soil physical and chemical properties. However, studies with potential for applying modified biosolids with these amendments are not complete yet. This review focused on identifying such gaps in these studies from over 170 peer-reviewed key research and review articles published over decades to latest in these areas.

  10. In situ fabrication of depth-type hierarchical CNT/quartz fiber filters for high efficiency filtration of sub-micron aerosols and high water repellency

    Science.gov (United States)

    Li, Peng; Zong, Yichen; Zhang, Yingying; Yang, Mengmeng; Zhang, Rufan; Li, Shuiqing; Wei, Fei

    2013-03-01

    We fabricated depth-type hierarchical CNT/quartz fiber (QF) filters through in situ growth of CNTs upon quartz fiber (QF) filters using a floating catalyst chemical vapor deposition (CVD) method. The filter specific area of the CNT/QF filters is more than 12 times higher than that of the pristine QF filters. As a result, the penetration of sub-micron aerosols for CNT/QF filters is reduced by two orders of magnitude, which reaches the standard of high-efficiency particulate air (HEPA) filters. Simultaneously, due to the fluffy brush-like hierarchical structure of CNTs on QFs, the pore size of the hybrid filters only has a small increment. The pressure drop across the CNT/QF filters only increases about 50% with respect to that of the pristine QF filters, leading to an obvious increased quality factor of the CNT/QF filters. Scanning electron microscope images reveal that CNTs are very efficient in capturing sub-micron aerosols. Moreover, the CNT/QF filters show high water repellency, implying their superiority for applications in humid conditions.We fabricated depth-type hierarchical CNT/quartz fiber (QF) filters through in situ growth of CNTs upon quartz fiber (QF) filters using a floating catalyst chemical vapor deposition (CVD) method. The filter specific area of the CNT/QF filters is more than 12 times higher than that of the pristine QF filters. As a result, the penetration of sub-micron aerosols for CNT/QF filters is reduced by two orders of magnitude, which reaches the standard of high-efficiency particulate air (HEPA) filters. Simultaneously, due to the fluffy brush-like hierarchical structure of CNTs on QFs, the pore size of the hybrid filters only has a small increment. The pressure drop across the CNT/QF filters only increases about 50% with respect to that of the pristine QF filters, leading to an obvious increased quality factor of the CNT/QF filters. Scanning electron microscope images reveal that CNTs are very efficient in capturing sub-micron aerosols

  11. The distribution of organic material and its contribution to the micro-topography of particles from wettable and water repellent soils

    Science.gov (United States)

    Bryant, Rob; Cheng, Shuying; Doerr, Stefan H.; Wright, Chris J.; Bayer, Julia V.; Williams, Rhodri P.

    2010-05-01

    Organic coatings on mineral particles will mask the physic-chemical properties of the underlying mineral surface. Surface images and force measurements obtained using atomic force microscopy (AFM) provide information about the nature of and variability in surfaces properties at the micro- to nano-scale. As AFM technology and data processing advance it is anticipated that a significant amount of information will be obtained simultaneously from individual contacts made at high frequency in non-contact or tapping mode operation. For present purposes the surfaces of model materials (smooth glass surfaces and acid-washed sand (AWS)) provide an indication of the dependency of the so-called AFM phase image on the topographic image (which is obtained synoptically). Pixel wise correlation of these images reveals how the modulation of an AFM probe is affected when topographic features are encountered. Adsorption of soil-derived humic acid (HA) or lecithin (LE), used here as an example for natural organic material, on these surfaces provides a soft and compliant, albeit partial, covering on the mineral which modifies the topography and the response of an AFM tip as it partially indents the soft regions (which contributes depth to the phase image). This produces a broadening on the data domain in the topographic/phase scatter diagram. Two dimensional classifications of these data, together with those obtained from sand particles drawn from water repellent and wettable soils, suggest that these large adsorbate molecules appear to have little preference to attach to particular topographic features or elevations. It appears that they may effectively remain on the surface at the point of initial contact. If organic adsorbates present a hydrophobic outer surface, then it seems possible that elevated features will not be immune from this and provide scope for a local, albeit, small contribution to the expression of super-hydrophobicity. It is therefore speculated here that the water

  12. A Fat strange Repeller

    Institute of Scientific and Technical Information of China (English)

    申影; 何阅; 姜玉梅; 何大韧

    2004-01-01

    This article reports an observation on a fat strange repeller, which appears after a characteristic crisis observed in a kicked rotor subjected to a piecewise continuous force field. The discontinuity border in the definition range of the two-dimensional mapping, which describes the system, oscillates as the discrete time develops. At a threshold of a control parameter a fat chaotic attractor suddenly transfers to a fat transient set. The strange repeller, which appears after the crisis, is also a fat fractal. This is the reason why super-transience happens

  13. Wildfires effects on soils: water repellency, NIR models and post-fire treatments. My personal view (SSS Division Outstanding ECS Award Lecture)

    Science.gov (United States)

    Arcenegui, Victoria

    2017-04-01

    I first was intrigued by fire, because all summers we had some of them in our location, and then I was involve in fire effects on soils. We had, and also have, a lot of question to answer. I am absolutely sure that soil science was my best choice. Soils are amazing, a lot of things are happening in soils. Soils and fire, are my main research topics. I studied the immediately effect of fire on soils, focus on the effect of fire in soil water repellency and aggregate stability. Two physical properties that are crucial to post-fire soil response. I also construct NIR models to know the maximum temperature reached in soils. It is well known that temperature is a key factor affecting soils properties. Then, it is a really important tool to predict the temperature reached in a soil after a wildfire. Currently, I am involve in a project to investigate what are the best post-fire treatments in our soils and how this treatments affects soil properties.

  14. In situ fabrication of depth-type hierarchical CNT/quartz fiber filters for high efficiency filtration of sub-micron aerosols and high water repellency.

    Science.gov (United States)

    Li, Peng; Zong, Yichen; Zhang, Yingying; Yang, Mengmeng; Zhang, Rufan; Li, Shuiqing; Wei, Fei

    2013-04-21

    We fabricated depth-type hierarchical CNT/quartz fiber (QF) filters through in situ growth of CNTs upon quartz fiber (QF) filters using a floating catalyst chemical vapor deposition (CVD) method. The filter specific area of the CNT/QF filters is more than 12 times higher than that of the pristine QF filters. As a result, the penetration of sub-micron aerosols for CNT/QF filters is reduced by two orders of magnitude, which reaches the standard of high-efficiency particulate air (HEPA) filters. Simultaneously, due to the fluffy brush-like hierarchical structure of CNTs on QFs, the pore size of the hybrid filters only has a small increment. The pressure drop across the CNT/QF filters only increases about 50% with respect to that of the pristine QF filters, leading to an obvious increased quality factor of the CNT/QF filters. Scanning electron microscope images reveal that CNTs are very efficient in capturing sub-micron aerosols. Moreover, the CNT/QF filters show high water repellency, implying their superiority for applications in humid conditions.

  15. What is the role played by organic matter fractions from different sieve-size particles in the development of soil water repellency? A case study using analytical pyrolysis.

    Science.gov (United States)

    Jiménez-Morillo, Nicasio T.; González-Pérez, José A.; González-Vila, Francisco J.; Zavala, Lorena M.; Jordán, Antonio; Jiménez-González, Marco A.

    2014-05-01

    1. INTRODUCTION It is known that soil water repellency (WR) is induced by organic substances covering the surface of minerals particles and aggregates or present as interstitial substances in the soil matrix. It has also been suggested that the persistence of WR is largely conditioned by specific chemical characteristics of soil organic matter (SOM). Most of these substances are abundant in ecosystems and are released into soils as exudates of roots, organic residues in decomposition, or secretions by fungi and other microorganisms. Soil free lipids correspond to a diverse collection of hydrophobic substances including complex substances as sterols, terpenes, polynuclear hydrocarbons, chlorophylls, fatty acids, waxes, and resins. Some of these organic substances, responsible of soil water repellency may be studied using analytical pyrolisis (de la Rosa et al., 2011; González-Pérez et al., 2011). This research aims to study the relation between soil WR and SOM quantity and quality, assessing the impact of organic fractions and its distribution in soil particles of different size on soil WR from sandy soils. 2. METHODS Soil samples were collected under selected species growing in sandy soils from the Doñana National Park (SW Spain), cork oak (Quercus suber, QS), eagle fern (Pteridium aquilinum, PA), pine (Pinus pinea, PP) and rockrose (Halimium halimifolium, HH). Soil WR and physical chemical characteristics including SOM content were assessed in fine earth soil samples (PA>PP>HH. A positive correlation was observed between WR from each sieve size fraction and SOM content. The most severe WR was detected in QS for all sieve size fractions, followed by the finer fractions form PA, PP and HH samples, which that also shows the highest SOM content, ranging between 20.9% (PP) and 46.9% (QS). Coarser soil fractions (1-2 mm) under PA, PP and HH showed the highest long-chain-even C numbered fatty acids (LCE-FA) in the order PP>PA>HH. No fatty acids were detected neither

  16. Preparation and performance study of modified MBPP/water repellent PET oil-absorbing composite material%改性 MBPP/拒水PET复合吸油材料的制备及性能研究

    Institute of Scientific and Technical Information of China (English)

    王丹; 崔永珠; 王晓; 吕丽华

    2016-01-01

    The melt-blown polypropylene nonwovens were grafted with BMA by UV grafting to improve the absorbing oil property.The surface of the needle polyester nonwovens was padded by fluorine-free water repellent finishing agent NT-X018 to improve the surface properties of water repellent and lipophilic.A kind of MBPP/PET oil-absorbing composite material was prepared by hot-press bonding to improve the poor state of MBPP for mechanical property.The optimum routes were determined by orthogonal tests respectively for MBPP grafted with BMA and PET finished with water repellent.The performance was compared among MBPP, modified MBPP, PET and modified MBPP/water repellent PET composite material.The results showed the adsorption rate, retention for oil ratio, reusability and mechanical properties of the modified MBPP/water repellent PET oil-absorbing composite material were better than those of others.%利用紫外接枝技术将甲基丙烯酸丁酯( BMA)接枝到熔喷聚丙烯( MBPP)非织造材料中,提高材料亲油性;对涤纶( PET)针刺非织造材料表面浸轧无氟拒水剂NT-X018,使材料表面更加疏水亲油;采用热压黏合法,将改性MBPP非织造材料和拒水PET针刺非织造材料复合,制备改性MBPP/拒水PET复合吸油材料,以改善MBPP非织造材料力学性能较差的现状。分别采用正交试验确定紫外接枝改性MBPP非织造材料及PET针刺非织造材料拒水整理的最佳工艺,并将MBPP非织造材料、改性MBPP非织造材料、PET针刺非织造材料与改性MBPP/拒水PET复合吸油材料进行性能比较,结果表明:改性MBPP/拒水PET复合吸油材料吸附率与保油率、重复使用性能及力学性能都有较大的提高。

  17. Rabbit Repellent Paint

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Five gallons of rabbit repellent paint were sent to George Wilson to be applied on the trees of the Tewaukon tree plot. Mr. Wilson requires a 3 or 4 in. brush for...

  18. Research on the New Type Water-repellent Sealant for the Connection Box%密封接线盒防水平衡剂的研究

    Institute of Scientific and Technical Information of China (English)

    张能; 海洁; 赵鹏远

    2011-01-01

    The organic silicon modified polyether epoxy resin was prepared with using silicon oil which had different consistencies, epoxy resin and polyether by the method of blending modification. Then the water-repellent sealant for the cable connection box was prepared with using this organic silicon modified polyether epoxy resin as the matrix resin, and adding curing agent,?flame retardant, accelerant,?mold discharging agent and fillers. The sealant would not release heat nor absorb heat in the curing process, and had little shrinking, the cured product had good elasticity, electric insulativity, high temperatures-resistance, aging-resistance, salt water resistance, shock-resistance and dust free performence.%采用不同稠度的硅油与低分子液态环氧树脂和聚醚共混改性的方法,制备了有机硅改性聚醚环氧树脂。同时,采用该有机硅改性聚醚环氧树脂为密封剂的基体树脂,并向其中加入固化剂、阻燃剂、促进剂、脱模剂以及增强填料等制备了电缆接线盒密封防水平衡剂,该密封剂在固化过程中不放热也不吸热,且固化过程中无收缩,固化物具有良好的弹性、电绝缘性、耐高低温性、耐老化性和耐盐水性以及减震防尘性能。

  19. Temporal changes in soil water repellency after a forest fire in a Mediterranean calcareous soil: Influence of ash and different vegetation type.

    Science.gov (United States)

    Jiménez-Pinilla, P; Lozano, E; Mataix-Solera, J; Arcenegui, V; Jordán, A; Zavala, L M

    2016-12-01

    Forest fires usually modify soil water repellency (SWR), and its persistence and intensity show a high variability both in space and time. This research studies the evolution of SWR in a Mediterranean calcareous soil affected by a forest fire, which occurred in Gorga (SE Spain) in July 2011, comparing the effect of the main vegetation cover between pine (Pinus halepensis) and shrubs species (Quercus coccifera, Rosmarinus officinalis, Cistus albidus, Erica arborea and Brachypodium retusum) and the relationship with soil moisture content (SMC). Also the study analyzed the effect of ash on SWR dynamics under field conditions. Six plots were established on the fire-affected area and the unburned-control-adjacent area to monitoring SWR with the water drop penetration time (WDPT) test, SMC through moist sensors (5cm depth) and three different ash treatments: ash presence, ash absence and incorporation of ash into the soil. An immediate increase of SWR was observed in the fire-affected area, mainly in pine plots. SWR changes in control (unburned) plots were quite similar between different types of vegetation influence, despite higher SWR values being observed on pine plots during the study period. A noticeable decrease of SWR was observed during the first months after fire in the affected areas, especially after the first rainy period, both in pine and shrubs plots. SWR increase was registered in all plots, and the highest levels were in March 2012 in burned pine plots. SWR decrease was higher in plots where ash was removed. Fire-affected soils became wettable 1year and a half after the fire. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. 新型含氟丙烯酸酯拒水剂的合成及应用%Synthesis and application of new fluorinated acrylate water repellent

    Institute of Scientific and Technical Information of China (English)

    安恩来; 党会茹; 习智华

    2015-01-01

    采用甲基丙烯酸十二氟庚酯(Actyflon-G04)、甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)为主要单体,脂肪醇聚氧乙烯醚(AEO-9)和十二烷基硫酸钠(SDS)为复配乳化剂,过硫酸铵(APS)为引发剂,通过半连续种子乳液聚合法,制备出新型含氟丙烯酸酯共聚物乳液.分析了该含氟丙烯酸酯拒水剂的最佳合成工艺,并应用到棉织物上.最佳合成工艺为:m(BA)∶m(MMA)=5∶3,Actyflon-G0430%(对单体总质量),乳化剂2.5%(对单体总质量),引发剂0.9%(对单体总质量),聚合反应温度80℃,保温时间3 h.将拒水剂处理到棉织物上,整理后织物对水的接触角可达125.0°,耐静水压为145.8 mm,具有良好的拒水效果,并且织物手感、透气性能变化不大.%New fluorinated acrylate copolymer emulsion was prepared using dodecafluoroheptyl methacry⁃late (Actyflon- G04), methyl methacrylate (MMA), butyl acrylate (BA) as the monomers, fatty alcohol polyoxy⁃ethylene ether (AEO- 9) and sodium dodecyl sulfate (SDS) as emulsifier, ammonium persulfate as initiator through semi- continuous seed emulsion polymerization method. The optimal synthesis process of new fluori⁃nated acrylate water repel ent was analyzed. The prepared copolymer was applied in cotton fabric. The results showed that the optimum synthesis conditions were 5∶3 of BA and MMA mass ratio, 30% of Actyflon- G04 (on the total mass of monomers), 2.5% of emulsifier (on the total mass of monomers), 0.9% of initiator (on the total mass of monomers), 80 ℃ of polymerization temperature, 3 h of holding time. And the synthetic co⁃polymers was applied in cotton fabric, the water contact angle of finished cotton fabric was up to 125.0° , the hydrostatic pressure was up to 145.8 mm. The prepared fluorinated acrylate emulsion had good water repel en⁃cy and little effect on the handle and air permeability of cotton fabric.

  1. A study on effects of water repellent on the performance of expanded perlite products%憎水剂对膨胀珍珠岩制品性能影响的研究

    Institute of Scientific and Technical Information of China (English)

    郭现龙; 田英良; 孙诗兵; 陈华; 高庆

    2012-01-01

    Due to large absorbing water, expanded perlite is limited to apply in the field of building energy1-saving. In this paper, effects of water repellent on strength and water absorption of expanded perlite products are studied by selecting different kinds, concentration of absorbing water, and using different hydrophobic treatment. The results show, add composite water repellent to expanded perlite product raw materials by blending mix way can effectively reduce the water absorption rate, at the same time, hydrophobic rate can reach to 98%. This study is helpful to improve hydrophobic properties of perlite products and promote its application in building engineering.%膨胀珍珠岩因吸水率大,制约其在建筑节能领域的应用.通过选取不同种类、浓度的憎水剂,采用不同憎水处理方式,研究憎水剂对膨胀珍珠岩制品吸水率、强度等性能的影响规律.结果表明,采用掺拌方式将复合憎水剂加入到膨胀珍珠岩制品原料中,可有效降低其吸水率,同时憎水率可达98%.有利于改进珍珠岩制品的憎水性能,促进其在建筑工程中的应用.

  2. Repelling Point Bosons

    Science.gov (United States)

    McGuire, J. B.

    2011-12-01

    There is a body of conventional wisdom that holds that a solvable quantum problem, by virtue of its solvability, is pathological and thus irrelevant. It has been difficult to refute this view owing to the paucity of theoretical constructs and experimental results. Recent experiments involving equivalent ions trapped in a spatial conformation of extreme anisotropic confinement (longitudinal extension tens, hundreds or even thousands of times transverse extension) have modified the view of relevancy, and it is now possible to consider systems previously thought pathological, in particular point Bosons that repel in one dimension. It has been difficult for the experimentalists to utilize existing theory, mainly due to long-standing theoretical misunderstanding of the relevance of the permutation group, in particular the non-commutativity of translations (periodicity) and transpositions (permutation). This misunderstanding is most easily rectified in the case of repelling Bosons.

  3. Accumulation of oil and grease in soils irrigated with greywater and their potential role in soil water repellency.

    Science.gov (United States)

    Travis, Micheal J; Weisbrod, Noam; Gross, Amit

    2008-05-01

    The potential impact of oil and grease (O and G) to soils irrigated with greywater (GW) was investigated. Greywater streams were sampled and analyzed for O and G content, along with corresponding GW-irrigated soils. Untreated kitchen GW averaged 200 mg L(-1) O and G, over an order of magnitude more than other GW streams. GW-irrigated soils showed O and G accumulation of up to 200 mg kg(-l) within the first 20-cm of depth. To determine the potential effects of such O and G accumulation on water movement in soil, capillary rise and water drop penetration time (WDPT) experiments were conducted. The results showed up to 60% decrease in capillary rise when sand containing 250 mg kg(-1) O and G was used. Interestingly, no additional reduction in capillary rise was observed at concentrations above 250 mg kg(-1). WDPT was observed to increase linearly with increased O and G content, up to 1000 mg kg(-1). This work demonstrated that O and G in GW used for irrigation can accumulate in soil and may lead to a significant reduction in the soils ability to transmit water.

  4. Water-repellent property of ZrO sub 2 modified with fluoro-alkyl groups on steel sheets. Zoru-geru ho ni yoru Fluoro-alkyl ki hensei ZrO sub 2 coating kouban no hassuisei

    Energy Technology Data Exchange (ETDEWEB)

    Izumi, K.; Murakami, M.; Tanaka, H.; Uchida, Y. (Nisshin Steel Co. Ltd., Tokyo (Japan))

    1990-12-25

    With the purpose of obtaining the coating of ZrO {sub 2} modified with fluoro-alkyl groups, steel sheets were coated with the sol-gel solution of zirconium tetra-octylate (ZTO) and fluoro-alkyl silane (FAS), and the property of the film formed was investigated. As a result, remarkable water-repellent property was obtained by coating a steel sheet with the mixed coating solution of ZTO and FAS after aging the solution for 24 hours. When the FAS of the same mole ratio as that of ZTO was added to ZTO, the FAS whose intramolecular F has larger number of functional groups indicated superior water-repellent effect. The change in the contact angle of water drop brought about by the aging time of the coating solution corresponded well with the change in the FAS of the coating solution. Moreover, when the firing temperature was less than 400 {degree} C, the contact angle of water drop indicated generally a constant value (about 105 {degree}), and when the firing temperature exceeded 400 {degree} C, the contact angle of water drop decreased sharply. 17 refs., 12 figs., 1 tab.

  5. FAQ: Insect Repellent Use and Safety

    Science.gov (United States)

    ... Mosquito Surveillance Software Health Education Public Service Videos Insect Repellent Use & Safety Recommend on Facebook Tweet Share ... the repellent with you. Top of Page Can insect repellents be used on children? Yes. Most products ...

  6. Synthesis and water repellency of polyacrylate latex containing fluorine and silicone%含氟硅丙烯酸酯乳液的合成及拒水性能分析

    Institute of Scientific and Technical Information of China (English)

    李智斌; 樊增禄; 毛宁涛; 李庆; 蔡信彬

    2015-01-01

    为提高纯棉织物的拒水性,以丙烯酸丁酯(B A )、甲基丙烯酸十二氟庚酯(G‐04)和乙烯基三乙氧基硅烷(KH‐151)作为反应单体,在阴/非复合乳化剂和引发剂过硫酸钾(KPS)作用下,采用乳液聚合的方法制备含氟硅丙烯酸酯乳液.用红外光谱(FT‐IR)对含氟硅丙烯酸酯乳液主组分的结构进行表征,并考察其对棉织物的拒水性能.通过探讨不同合成工艺参数对含氟硅丙烯酸酯乳液的拒水性能的影响,确定合成的含氟硅丙烯酸酯乳液的最佳原料配比.将制备的乳液对纯棉织物进行拒水整理,可明显改善织物的拒水性能,整理后纯棉织物对水的接触角达到126.8°,静水压达到1.45kPa ,表现出良好的拒水效果.%In order to improve the properties of water repellency for cotton fabrics ,butyl acry‐late(BA),dodecafluoroheptyl methacrylate(G‐04) and triethoxyvinylsilane(KH‐151) were used as monomers to synthesize pololyacrylate latex containing ,fluorine and silicone ,by adop‐ting emulsion polymerization technique .K2S2O8 (KPS) and nionic/nonionic surfactants were employed as water soluble initiator and mixed emulsifier ,respectively .Structure information of polyacrylate latex containing fluorine and silicone was characterized by Fourier Transform In‐frared Spectrometer(FT‐IR) ,and the water repellent property of cotton fabric was investiga‐ted .The optimum raw material ratio of polyacrylate latex containing fluorine and silicone was set by the investigation of the influence of processing parameter on w ater repellency .T he trea‐ted cotton fabric exhibits good water repellency property ,the water contact angle of cotton fab‐ric treated with the finishing agent reaches 126.8° ,and hydrostatic pressure reaches 1.45kPa .

  7. Cotton fabric modification for imparting high water and oil repellency using perfluoroalkyl phosphate acrylate via γ-ray-induced grafting

    Science.gov (United States)

    Miao, Hui; Bao, Fenfen; Cheng, Liangliang; Shi, Wenfang

    2010-07-01

    The perfluoroalkyl phosphate acrylates were grafted onto a cotton fabric via γ-ray irradiation to improve the hydrophobic and oleophobic properties. The change in chemical structure of grafted cotton fabric was detected by the Fourier transform infrared spectroscopy and the X-ray photoelectron spectroscopy. The contact angles for water and sunflower oil were determined to be over 150° and 140°, respectively, after irradiated with a dose range of 471-5664 Gy. The flame retardancy of the fabric with a grafting ratio of over 13.0 wt% was improved, reaching to 24 compared with 18 of which before grafted, according to the limiting oxygen index measurement. The microstructure of the fabric before and after grafted was observed by the scanning electron microscope.

  8. Cotton fabric modification for imparting high water and oil repellency using perfluoroalkyl phosphate acrylate via gamma-ray-induced grafting

    Energy Technology Data Exchange (ETDEWEB)

    Miao Hui; Bao Fenfen; Cheng Liangliang [CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Jinzhai Road 96, Hefei, Anhui 230026 (China); Shi Wenfang, E-mail: wfshi@ustc.ed [CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Jinzhai Road 96, Hefei, Anhui 230026 (China)

    2010-07-15

    The perfluoroalkyl phosphate acrylates were grafted onto a cotton fabric via gamma-ray irradiation to improve the hydrophobic and oleophobic properties. The change in chemical structure of grafted cotton fabric was detected by the Fourier transform infrared spectroscopy and the X-ray photoelectron spectroscopy. The contact angles for water and sunflower oil were determined to be over 150 deg. and 140 deg., respectively, after irradiated with a dose range of 471-5664 Gy. The flame retardancy of the fabric with a grafting ratio of over 13.0 wt% was improved, reaching to 24 compared with 18 of which before grafted, according to the limiting oxygen index measurement. The microstructure of the fabric before and after grafted was observed by the scanning electron microscope.

  9. Research on water and oil-repellent finish of polyester needle punched nonwoven filter material%涤纶针刺滤料的拒水拒油整理工艺研究

    Institute of Scientific and Technical Information of China (English)

    曹小敏; 崔运花

    2015-01-01

    使用FG-910含氟拒水拒油整理剂对涤纶针刺滤料进行拒水拒油整理,研究了在整理过程中五个主要因素对整理效果的影响规律,并进行了正交优化试验. 结果表明:最佳的整理工艺参数是浸渍温度55 ℃、浸渍时间25 min、FG-910质量浓度60 g/L、焙烘温度150 ℃和焙烘时间150 s,在该条件下整理可使涤纶针刺滤料的拒水等级和拒油等级都达到8级,且透气率变化率达到18.75%,可有效地改善滤料的过滤性能.%Used fluorinated reagent FG-910 to do water an filter material , the influence of five major factors on the finishing effects was studied , and then did orthogonal optimization test .The results showed that the optimum finishing process as follows:dipping temperature was 55 ℃, dipping time was 25 min, FG-910 concentration was 60 g/L, curing tempera-ture was 150 ℃and curing time was 150 s.Under this condition water-repellency and oil-repellency grade of polyester needle punched filter material has reached eight , and the permeability has reached 18.75%, which improved the filtration performance of filter media effectively . d oil repellent finishing for polyester needle punched

  10. Super water repellent finishing technology by simulating bio-structures. Improvement of chemical durability by super water repellent finishing of hydroxy- apatite/titan composite films prepared by high-frequency plasma arc spraying; Seibutsu no kozo wo mohoshita chohassuika gijutsu. Koshuha plasma yoshaho ni yori sakuseishita suisan apataito/chitan fukugo himaku no chohassuika ni yoru kagakuteki taikyusei no kojo

    Energy Technology Data Exchange (ETDEWEB)

    Hozumi, A.; Inagaki, M.; Okuderaa, H.; Nishizawa, K.; Nagata, F.; Teraoka, H.; Yokogawa, Y.; Kameyama, T. [National Industrial Research Institute of Nagoya, Nagoya (Japan)

    2000-08-25

    Artificial joint and tooth root produced by coating hydroxy- apatite (HA) onto Ti alloy base surface by DC plasma torch arc spraying in commercially available in Europe, and have been used for persons not less than 100,000 since 1985. However, peeling and dissolution of coats after implant have been reported as a serious problem. The long-term stability of coats is dependent on the chemical durability of coats. Paying attention to physical structure of HA/Ti composite film surface. this study attempted super water repellent finishing of the surface through reduction of surface energy by chemical modification of the surface in a molecular level. Self-organization single-molecule film of organic silane compound with perfluoroalkyl group was formed by CVD on the HA/Ti composite film surface prepared on Ti alloy by high- frequency plasma arc spraying. The extremely hydrophobic HA/Ti composite film with a contact angle ranging 130-160 degrees was thus obtained from the highly hydrophilic coat. This sample showed a very high chemical durability as compared with conventional ones. (NEDO)

  11. Water and oil-repellent treatment on medical SMMS and wood-pulp nonwoven fabric%医用SMMS和木浆非织造布的拒水拒油整理

    Institute of Scientific and Technical Information of China (English)

    李银玲; 刘彦军

    2012-01-01

    采用乳液聚合制备了含氟整理剂,通过轧烘焙工艺对丙纶复合非织造布SMMS和木浆非织造布进行了整理,研究了整理剂用量、焙烘时间和焙烘温度对整理效果的影响.结果表明:当整理剂用量为20 g/L,120℃焙烘90s时,SMMS非织造布拒水等级为10级,拒油等级为8级.当整理剂用量为20 g/L,110℃焙烘100 s时,木浆非织造布拒水等级为10级,拒油等级为8级.非织造布具有良好的抗酒精性能、抗血液渗透、透气性、断裂强力及耐静水压性能,能满足医用要求.%The fluorine-containing finishing agent was prepared through emulsion polymerization. The polypropylene complexed nonwoven fabric SMMS and wood-pulp nonwoven fabric was treated with fluorine-containing finishing agent via pad-dry-cure technology, and the influence of the finishing agent dosage, curing temperature and time on the finishing result was investigated. The result showed that when finishing agent dosage was 20 g/L, cured at 120 ℃ for 90 s, the water-repellent rating of the treated SMMS nonwoven fabric was 10 and the oil-repellent rating was 8; when finishing agent dosage was 20 g/L, cured at 110 ℃ for 100 s, the water-repellent rating of the treated wood-pulp nonwoven fabric was 10 and the oil-repellent rating was 8. The nonwoven fabric had good resistance to alcohol, blood penetration, breathable property, breaking strength and static water pressure, which could meet the medical requirements.

  12. EFECTO DE LA TEMPERATURA DE SECADO SOBRE EL GRADO Y LA VARIABILIDAD ESPACIAL DE LA REPELENCIA AL AGUA EN ANDISOLES DE ANTIOQUIA, COLOMBIA DRYING TEMPERATURE, PERSISTENCE AND SPATIAL VARIABILITY OF WATER REPELLENCY IN ANDISOLS OF ANTIOQUIA, COLOMBIA

    Directory of Open Access Journals (Sweden)

    Daniel Francisco Jaramillo Jaramillo

    2007-12-01

    different times: one dry and the another humid to evaluate the persistence from the real water repellency and the answer from the water repellency to drying samples with different temperatures in both coverings, times and directions. Persistence evaluation was made by WDPT method under field conditions and in dried soils to temperatures of 15, 20, 25, 30, 35 and105°C. It was observed that when drying temperature was increased, water repellency and soil volume affected by the hydrophobicity were also increased. This situation presented in both coverings occurs with more intensity in soils under plantations of Pinus patula. An anisotropy in water repellency was found presenting a general tendency to develop highest grade of hydrophobicity in transects in E-O direction. In all studied transects a wide space variability of short range was detected in water repellency, as well as a distribution in patches of the phenomenon and the generation of preferential flow pathways for entrance and circulation of water in soil.

  13. Novel protein-repellent and biofilm-repellent orthodontic cement containing 2-methacryloyloxyethyl phosphorylcholine.

    Science.gov (United States)

    Zhang, Ning; Zhang, Ke; Melo, Mary Anne S; Chen, Chen; Fouad, Ashraf F; Bai, Yuxing; Xu, Hockin H K

    2016-07-01

    The objectives of this study were to develop the first protein-repellent resin-modified glass ionomer cement (RMGI) by incorporating 2-methacryloyloxyethyl phosphorylcholine (MPC) for orthodontic applications, and to investigate the MPC effects on protein adsorption, biofilm growth, and enamel bond strength. MPC was incorporated into RMGI at 0% (control), 1.5%, 3%, and 5% by mass. Specimens were stored in water at 37°C for 1 and 30 days. Enamel shear bond strength (SBS) was measured, and the adhesive remnant index (ARI) scores were assessed. Protein adsorption onto the specimens was determined by a micro bicinchoninic acid method. A dental plaque microcosm biofilm model with human saliva as inoculum was used. The results showed that adding 3% of MPC into RMGI did not significantly reduce the SBS (p > 0.1). There was no significant loss in SBS for RMGI containing 3% MPC after water-aging for 30 days, as compared to 1 day (p > 0.1). RMGI with 3% MPC had protein adsorption that was 1/10 that of control. RMGI with 3% MPC greatly reduced the bacterial adhesion, and lactic acid production and colony-forming units of biofilms, while substantially increasing the medium solution pH containing biofilms. The protein-repellent and biofilm-repellent effects were not decreased after water-aging for 30 days. In conclusion, the MPC-containing RMGI is promising to reduce biofilms and white spot lesions without compromising orthodontic bracket-enamel bond strength. The novel protein-repellent method may have applicability to other orthodontic cements, dental composites, adhesives, sealants, and cements to repel proteins and biofilms. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 949-959, 2016.

  14. Research Status and Research Prospect of Textile Materials Water Repellent by Plasma%纺织材料等离子体拒水改性的研究现状与展望

    Institute of Scientific and Technical Information of China (English)

    熊秋元

    2011-01-01

    Research status and development trend of textile material water repellent are discussed based on plasma processing technology.The modification method of textile materials water repellent by plasma is described.It is found that modification are focused on%探讨了基于等离子体处理技术的纺织材料拒水改性的研究现状及发展趋势。阐述了纺织材料等离子拒水改性的常用方法,指出国内外研究大多集中在利用氟系饱和或不饱和的化合物对织物进行拒水改性。其发展总趋势是:利用等离子体对纺织材料拒水改性的产业化、工业化;常压等离子体处理技术的发展;等离子体处理技术和常规加工技术的结合;利用等离子体对纺织材料改性,赋予其多种性能。

  15. 硅烷改性混凝土防水和抗氯离子性能试验研究%Experimental study of the water repellency and chloride resistance of modified concrete with silane

    Institute of Scientific and Technical Information of China (English)

    张鹏; 赵铁军; 戴建国; 郭平功; Wittmann F H

    2011-01-01

    The water repellency and chloride resistance of modified concrete with silane without and with cracks have been investigated through neutron radiography test, water absorption test and chloride penetration test. The results indicate that the process of water penetration into mortar specimens without silane can be visualized distinctly by means of neutron radiography, while water in the modified mortar with silane cannot be observed by naked eyes. The hydrophobic films formed in the capillary pores from the added silane effectively restrain liquid water from penetrating into mortar, and consequently it results in decreasing water absorption to be only 13% of mortar without silane. The hydrolysis and polymerization reaction of silane in cementitious materials do not block the respirability of the capillary pores. Cracks are instantaneously filled with water once specimens without silane crack, and after that water will penetrate into the adjacent areas around the cracks. However, even when the modified specimens with silane crack up to 0. 3mm, there is no obvious water movement observed. The cracks from 0.1mm to 0.4mm hardly decrease the integral water repellency of modified concrete with silane. Due to the high water repellency of the modified concrete with silane it thus also has high resistance to chloride penetration with or without cracks. It is an effective method to improve the water repellency and chloride resistance and thus the durability of cement-based materials by modifying concrete with silane.%通过中子成像试验、吸水试验和氯离子侵蚀试验,研究无裂缝和带裂缝情况下硅烷改性混凝土的防水和抗氯离子侵蚀性能.试验结果表明,中子成像能够清晰观测未掺硅烷试件的快速吸水过程,而掺加硅烷后在毛细孔隙壁上形成的憎水膜能够有效抑制液态水分侵入,中子成像观测不到肉眼可见的水分前锋,吸水量降为未掺硅烷时的13%,显示出良好的防水性能.硅

  16. Substitution of PFAS chemistry in outdoor apparel and the impact on repellency performance.

    Science.gov (United States)

    Hill, Philippa J; Taylor, Mark; Goswami, Parikshit; Blackburn, Richard S

    2017-08-01

    Intensifying legislation and increased research on the toxicological and persistent nature of per- and polyfluoroalkyl substances (PFASs) have recently influenced the direction of liquid repellent chemistry use; environmental, social, and sustainability responsibilities are at the crux. Without PFAS chemistry, it is challenging to meet current textile industry liquid repellency requirements, which is a highly desirable property, particularly in outdoor apparel where the technology helps to provide the wearer with essential protection from adverse environmental conditions. Herein, complexities between required functionality, legislation and sustainability within outdoor apparel are discussed, and fundamental technical performance of commercially available long-chain (C8) PFASs, shorter-chain (C6) PFASs, and non-fluorinated repellent chemistries finishes are evaluated comparatively. Non-fluorinated finishes provided no oil repellency, and were clearly inferior in this property to PFAS-finished fabrics that demonstrated good oil-resistance. However, water repellency ratings were similar across the range of all finished fabrics tested, all demonstrating a high level of resistance to wetting, and several non-fluorinated repellent fabrics provide similar water repellency to long-chain (C8) PFAS or shorter-chain (C6) PFAS finished fabrics. The primary repellency function required in outdoor apparel is water repellency, and we would propose that the use of PFAS chemistry for such garments is over-engineering, providing oil repellency that is in excess of user requirements. Accordingly, significant environmental and toxicological benefits could be achieved by switching outdoor apparel to non-fluorinated finishes without a significant reduction in garment water-repellency performance. These conclusions are being supported by further research into the effect of laundering, abrasion and ageing of these fabrics. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. HUMEDAD CRÍTICA Y REPELENCIA AL AGUA EN ANDISOLES COLOMBIANOS BAJO COBERTURA DE Pinus patula Schltdl y Cham CRITICAL MOISTURE AND WATER REPELLENCY OF COLOMBIAN ANDISOLS COVERED WITH Pinus patula Schltdl and Cham

    Directory of Open Access Journals (Sweden)

    Daniel Francisco Jaramillo Jaramillo

    2005-12-01

    Full Text Available En un lote con Andisoles bajo cobertura de Pinus patula Schltdl y Cham se ubicaron 4 transectos sobre los cuales se hizo un muestreo horizontal cada 5 cm, en 4 profundidades, con el fin de establecer si había una zona de transición de humedad crítica en el suelo que estuviera controlando la presencia de repelencia al agua en él. Se hicieron determinaciones de WDPT en el campo y luego en muestras secadas a 35 °C, en laboratorio. En cada condición se determinó el contenido gravimétrico de humedad a cada muestra y se relacionaron estos contenidos con su correspondiente WDPT. Los suelos presentaron altos contenidos de humedad, tanto en campo, como secos a 35 °C. La mayoría de los sitios fueron humectables en campo pero, al secar las muestras a 35 °C, la mayoría de ellas, en las tres primeras profundidades, se tornaron fuertemente repelentes al agua. Ambas propiedades tuvieron una alta variabilidad. En algunas profundidades de varios transectos fue posible definir, precariamente, zonas críticas de humedad para la repelencia al agua pero, al tratar de generalizar esta zona para todo el perfil del transecto, no fue posible definirla.In a stand with Andisoles planted with Pinus patula Schltdl and Cham, 4 transects were established for horizontal sampling every 5 cm in 4 depths to establish whether there was a transition zone for critical humidity in the soil that could determine the presence of water repellency in it. Determinations of WDPT were made in the field and later on samples dried at 35 °C in the laboratory. For each condition, the gravimetric content of humidity of each sample was determined and these contents were compared to their corresponding WDPT. The soils presented high humidity contents, both in the field and when dried at 35 °C. Most of the sites were humidified in the field, but upon drying the samples at 35 °C, the majority of them from the first three pit depths became strongly water repellent. Both properties were

  18. [Prevention with repellent in children].

    Science.gov (United States)

    Sorge, F

    2009-10-01

    Use of topical insect repellent is an important component in prophylaxis of arthropod bite vector borne diseases. Topical insect repellent are used in a three part management regimen, along with impregnated clothing and mosquito netting. Parental training for efficacious and secure use of repellents for their children is essential part of a successful strategy to combat Lyme borreliosis, dengue fever, Chikungunya, West Nile virus infection and malaria, amongst children, according to local epidemiological risks. Rational repellent prescription for a child must take into account age, active substance concentration, topical substance tolerance, nature and surface of the skin to protect, number of daily applications, and the length of use in a benefit-risk ratio assessment perspective. The 4 currently repellents recommended by Whopes (Who) for their long lasting efficacy and patient tolerance are: 1) Citriodiol (PMD), 2) DEET, 3) Icaridine (KB3023), and 4) IR3535. In field trials the minimum required concentration of each four of these agents to be effective for 3 hours against most arthropods is 20% (in cream, roll-on or spray vehicle). Described side effects of these agents are mild, being limited to local irritative dermatitis and allergy. The risk of severe side effects has been related to DEET misused and neurotoxicity. The international recommendations concerning utilization of topical repellent amongst children for prophylaxis of arthropod borne diseases is concerning short term usage (several weeks). But the use of repellent is sub chronic or chronic amongst the majority of children living in subtropical regions where these vector borne diseases are endemic. And toxicity of topical repellent when used sub-chronically and chronically is not well studied in pediatric age groups. Taking into account these considerations, the current recommendations of the French Group of Tropical Paediatrics are to teach the parents of children who live in arthropod vector disease

  19. Repellents Against Land Leeches for Military Use

    Directory of Open Access Journals (Sweden)

    T. Koshy

    1967-05-01

    Full Text Available A short account of the habits and nature of depredations of the leeches in the Himalayan region is given. The requirements for a leech repellent, to be of use in a hot humid and rainy area are stressed. A brief survey of the repellents and the need for their suitable screening for use in this area is made. Mention is made of some newer insect and mite repellents, which are likely to prove leech repellents as well.It is suggested that emphasis should be made on the choice of a impregnated repellent for military use in the area rather than on a 'skin repellent.

  20. Infodisruption of inducible anti-predator defenses through commercial insect repellents?

    Science.gov (United States)

    von Elert, Eric; Preuss, Katja; Fink, Patrick

    2016-03-01

    Commercial insect repellents like DEET (N,N-diethyl-m-toluamide), EBAAP (IR3535(®), (3-[N-butyl-N-acetyl]-aminopropionic acid, ethyl ester)) or Icaridine (picaridin, Bayrepel, 1-piperidinecarboxylic acid, 2-(2-hydroxyethyl), 1-methylpropyl ester) are used worldwide to protect against biting insects and ticks. The detection of these repellents in surface waters in concentrations up to several μg/L levels has caused concern that these substances might affect non-target organisms in freshwaters. Daphnia sp., a keystone organism in lakes and ponds, is known for diel vertical migration (DVM) and life-history changes (LHCs) as inducible defenses against predation by fish. Here we test whether (i) environmentally relevant concentrations of DEET, EBAPP or Icaridine have repellent effects on Daphnia magna and (ii) if these repellents are infodisruptors for DVM and LHCs. Using concentrations of up to 44 μg/L, the repellents neither had effects on juvenile somatic growth nor on clutch size. In thermally stratified water columns with a repellent-free hypolimnion, no repellent effects of the test compounds on D. magna were observed. The presence of fish-born infochemicals induced LHCs, which are characterized by a reduced size at first reproduction, and DVM in D. magna. These effects were not affected by the presence of either repellent. Hence no evidences for infodisruption of the chemical communication of fish and Daphnia by DEET, EBAAP or Icaridine were found.

  1. Durable Dust Repellent Coating for Metals Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Durable Dust Repellent Coating (DDRC) consists of nano-phase silica, titania, or other oxide coatings to repel dust in a vacuum environment over a wide range of...

  2. Coating for Nano Super Soil-repellency of Cashmere Fabric

    Institute of Scientific and Technical Information of China (English)

    WANG Jin-mei; ZHU Chang-chun

    2005-01-01

    The nano-size metal oxide was prepared by the single-disperse technique on liquid phase, and formed sol clusters, its uniform film was covered on the surface of cashmere fibers by coating, and it had good oil repellency and water repellency. The results of IR(infrared) Spectrometer analysis revealed: The nano material combines through the strong bonds with the surface of cashmere fibers by the live groups.These analyses by SEM techniques showed that the nano material was distributed on the fiber surface even, and the nano material formed the strong peak of the regular crystal phase structure using the X-Ray Diffractometry (XRD) to analysis the fabric. The optimum techniques were selected by a series of experiments, coated cashmere fabric not only has preserved original properties of softness and comfort,but also has good properties of Bi-repellency function.Therefore, the technique will have potential application in engineers.

  3. Evaluation of botanicals as repellents against mosquitoes.

    Science.gov (United States)

    Das, N G; Baruah, I; Talukdar, P K; Das, S C

    2003-01-01

    Repellent properties of three plant extracts--essential oil (steam distillate) of Zanthoxylum limonella (fruits), Citrus aurantifolia (leaf) and petroleum ether extract of Z. limonella (fruits) were evaluated as repellent against Aedes (S.) albopictus mosquitoes in mustard (Dhara) and coconut (Parachute) oil base under laboratory conditions. Three concentrations--10, 20 and 30% of the repellents were evaluated. Repellents in mustard oil afforded longer protection time against the bites of Aedes (S.) albopictus mosquitoes than those in coconut oil. At 30% concentration, 296-304 min protection time was achieved by the test repellents in mustard oil base while repellents in coconut oil exhibited 223.5-245 min protection time at the same concentration. Oil of Z. limonella gave the highest protection time against the bites of Aedes (S.) albopictus mosquitoes at all the concentrations than other herbal repellents tested both in mustard and coconut oil.

  4. Super toner and ink repellent superoleophobic surface.

    Science.gov (United States)

    Zhao, Hong; Law, Kock-Yee

    2012-08-01

    Offset of imaging material from a fuser surface to paper during fusing is highly undesirable in printing. Here the wetting and repellent characteristics of three imaging materials (a solid wax ink, a waxy polyester toner, and a polyester toner) in their molten states have been studied on three model print surfaces: a transparency (surrogate for paper), a PTFE film, and a model superoleophobic surface, with the aim of assessing their performance in fusing. The superoleophobic surface, with water and hexadecane contact angles of ∼156° and sliding angles at ∼10°, comprises 3 μm diameter pillar arrays on silicon wafer and was fabricated by photolithography followed by surface modification with a fluorosilane. The contact angles of the three imaging materials range from 40 to 79° on the transparency and the sessile drops do not slide even at 90° tilted angle, indicating that they all wet, adhere, and pin on the transparency. Although the contact angles of the three imaging materials are slightly higher (63-85°) on PTFE, the sessile drops do not slide on PTFE either. Because PTFE is widely used as a fuser surface material in combination with different waxy imaging materials commercially, we attribute the successful implementation of PTFE to the use of the wax additive. With the superoleophobic surface, there is a dramatic increase in advancing and static contact angles for all three imaging materials. The advancing and static contact angles are in the 150-168° range for waxy toner, indicative of superhigh repellency. Although the advancing and static contact angles for the polyester toner decrease slightly at 147 and 130°, respectively, the repellency is still very high. More importantly, the sessile drops of all three imaging materials are mobile upon tilting and they all have high receding contact angles. The overall results suggest that the adhesion between the superoleophobic surface and the ink and toner materials are very small relative to those with

  5. Synthesis and water repellency of polymer based on soybean off-based fluorine-containing ester and styrene%大豆油基含氟酯/苯乙烯聚合物的合成及拒水性研究

    Institute of Scientific and Technical Information of China (English)

    刘立珍; 赵涛; 王静静

    2013-01-01

    通过酯交换反应将含氟基团引入大豆油脂肪酸酯中,并将其作为软单体与硬单体苯乙烯进行阳离子聚合反应,生成大豆油基含氟拒水剂.用博里叶变换红外光谱及核磁共振波谱对中间产物及大豆油基含氟拒水剂进行结构表征;采用热重分析仪(rG)及差热扫描分析仪(DSC)对聚合物的热性能进行分析.测试整理前后棉织物的接触角、织物表面抗湿性(沾水性)来评价其拒水性能、耐洗性;并测试织物白度以及断裂强度评价该拒水剂对织物其他应用性能的影响.结果表明:n(大豆油基含氟酯):n(苯乙烯)=1:3时,玻璃化温度为46.22℃,熔点为120.46℃,适合作为纺织品用整理剂;该类拒水剂在质量浓度为45 g/L时拒水效果较好,接触角为143°,拒水等级为5级,具有较好的耐洗性,对白度及断裂强力的影响较小.%The fluorine-containing groups were introduced into soybean oil fatty acid ester through ester exchange reaction,and then oil-based fluorine-containing water repellent agent was synthesized through cationic polymerization reaction of fluorine-containing oil (soft monomers) and styrene (hard monomers).The structure of intermediate products and water repellent agent was characterized by Fourier transform infrared spectrum (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy.The thermal properties of the polymer were analyzed by thermal gravity (TG) and differential scanning calorimeter (DSC).The water repellent property and durability was evaluated through the contact angle and the fabric surface resistance to water before and after finishing.The influence of the water repellent agent on other applications of the fabric was investigated by the test of fabric whiteness and breaking strength.The results showed that the water repellent agent was suitable for textile finishing when n(oil-based fluorine-containing ester):n(styrene) was 1:3,the glass transition temperature was 46.22

  6. LARVICIDAL POTENTIAL AND MOSQUITO REPELLENT ACTIVITY OF CASSIA MIMOSOIDES EXTRACTS.

    Science.gov (United States)

    Alayo, M A; Femi-Oyewo, M N; Bakre, L G; Fashina, A O

    2015-07-01

    This study aims to investigate larvicidal activities of extracts of Cassia mimosoides leaves and pods as a potential agent in vector control of malaria and to evaluate repellent effect against Anopheles gambiae mosquito of the extract formulated in an aqueous cream base. Petroleum spirit, ethanol, water and dichloromethane extracts were tested against third and fourth instar Anopheles gambiae larvae. The petroleum extract was formulated in an aqueous cream base and repellency determined using N-N-diethyl-m-toluamide (DEET) as control. Phytochemical analysis showed the presence of saponins, tannins, anthraquinones, steroids, and flavonoids but absence of cardiac glycosides and alkaloids in powdered C. mimosoides. A dose related response was observed in the mortality rate of the extracts, with 2 mg/ml petroleum ether and dichloromethane extracts achieving 100 % mortality. Larvicidal activity of extracts based on LC50 values was petroleum ether > dichloromethane > ethanol > water. The formulated petroleum ether extract cream had a characteristic odor, hard and smooth texture, skin feeling of smoothness, ease of application by rubbing, easy removal using soap and water, non-irritating effect on skin and an acceptable pH value. The cream containing 2%-6% (w/w) extract and control achieved 100% repellency against mosquitoes after an exposure time of 5 minutes. There was a linear relationship between percent concentration of plant extract in the cream samples and repellent activity. These results suggest that crude extracts of C. mimosoides can be developed as eco-friendly larvicide and mosquito repellent and encourage further effort to investigate the bioactive compounds in the extracts.

  7. Evaluation of botanicals as repellents against mosquitoes

    Directory of Open Access Journals (Sweden)

    N.G. Das, I. Baruah, P.K. Talukdar & S.C. Das

    2003-03-01

    Full Text Available Repellent properties of three plant extracts—essential oil (steam distillate of Zanthoxylumlimonella (fruits, Citrus aurantifolia (leaf and petroleum ether extract of Z. limonella (fruitswere evaluated as repellent against Aedes (S. albopictus mosquitoes in mustard (Dhara and coconut(Parachute oil base under laboratory conditions. Three concentrations—10, 20 and 30% of therepellents were evaluated. Repellents in mustard oil afforded longer protection time against thebites of Aedes (S. albopictus mosquitoes than those in coconut oil. At 30% concentration, 296–304 min protection time was achieved by the test repellents in mustard oil base while repellents incoconut oil exhibited 223.5–245 min protection time at the same concentration. Oil of Z. limonellagave the highest protection time against the bites of Aedes (S. albopictus mosquitoes at all theconcentrations than other herbal repellents tested both in mustard and coconut oil.

  8. Insect Repellent Properties of Melaleuca alternifolia

    OpenAIRE

    Mohamad Adib Bin Edris; Awang Soh Yusuff Mamat; Muhammad Shahzad Aslam; Muhammad Syarhabil Ahmad

    2016-01-01

    The aim of this study is to compare the use of plant-based insect repellents that are environment friendly with the use of insect repellents based on chemical substances which can be harmful to the environment and human health. The plant studied here is "tea tree"; its scientific name is Melaleuca alternifolia. Essential oil from this plant is extracted by steam distillation method. Based on the previous research, tea tree oil has antimicrobial, antifungal, anti-inflammatory, and insect repel...

  9. 建筑表面用渗透型有机硅防水乳液的研制%Research of permeable organosilicon water repellent emulsion used on concrete surface

    Institute of Scientific and Technical Information of China (English)

    杨超

    2011-01-01

    本文研制了一种适用于硅酸盐建筑材料表面防护的渗透型有机硅防水乳液,通过筛选合适的复合乳化体系以及优化硅烷混合物的组成,在温和的反应条件与简便易行的工艺手段下,制备了储存稳定、防水效果良好的产品;并降低了产品的原料和生产成本,对其推广使用有积极意义。%The permeable organosilicon water repellent emulsion was prepared with silane mixture and compound emulsifier by conventional emulsion polymerization.In order to prepare stable and effective emulsion,a series of compound emulsifiers and various ratio of silane mixture were tested.Especially,the suitable compound emulsifiers we have found insure the stability of emulsion which prepared in convenient operations and mild reactions.

  10. Rodent-repellent studies. I. Method for the evaluation of chemical repellents

    Science.gov (United States)

    Bellack, E.; DeWitt, J.B.

    1949-01-01

    A biological assay procedure and a method for the numerical expression of results have been devised for the determination of the repellency to rodents of different chemical compounds. The procedure is based upon the degree of acceptability of foods containing the candidate repellents,. and has been shown. to offer a rapid, reliable measure of repellent activIty.

  11. Repellent Action of Neem (Azadirachta indica) Seed Oil Cream ...

    African Journals Online (AJOL)

    Nekky Umera

    potential of neem seed oil cream as mosquito repellent particularly at higher ... In the present study, neem Seed oil extracted from Azadirachta indica plant .... repellency was in two phases, first to determine the repellency properties of.

  12. Chapter 12: spatial or area repellents

    Science.gov (United States)

    Spatial repellents a three-dimensional zone of protection around a host from attacks by biting arthropods. This chapter reviews current knowledge and outlines future directions for utilization of spatial repellents. Current knowledge includes the kinds of products, both active and passive devices,...

  13. Structural optimization of super-repellent surfaces

    DEFF Research Database (Denmark)

    Cavalli, Andrea; Bøggild, Peter; Okkels, Fridolin

    2013-01-01

    Micro-patterning is an effective way to achieve surfaces with extreme liquid repellency. This technique does not rely on chemical coatings and is therefore a promising concept for application in food processing and bio-compatibile coatings. This super-repellent behaviour is obtained by suspending...

  14. Novel Carboxamides as Potential Mosquito Repellents

    Science.gov (United States)

    2010-09-01

    deet) is themost ef- fective andbest-studied arthropod repellent currently on the market . However, it does not provide a long duration of protection...Gaudin, J. M., T. Lander, and O. Nikolaenko. 2008. Carbox- amides combining favorable olfactory properties with insect repellency. Chem. Biodivers. 5

  15. Preparation and Application of a New Silicon-containing Acrylate Water Repellent%新型含硅丙烯酸酯拒水剂的合成及应用

    Institute of Scientific and Technical Information of China (English)

    杨番; 王柱; 刘海峰; 张涛; 李天龙

    2016-01-01

    (Tri) and TRIS, dosage of GMA, initiator and emulsi-fier on the gel rate , conversion rate and water repellency property were also discussed through the orthogonal test method .The obtained polymer emulsion was then characterized by IR spectroscopy , particle size , contact angle performance , spray test , transmission electron microscope and thermodynamic analysis .The results showed that the optimum synthesizing condition was obtained as follows:the dosage of organic silicon monomer was 25.0 wt%,mass ration of Si(Tri) and TRIS was 25/75, the dosage of GMA, emulsifier and initiator were 5 .0 wt%, 2 .7 wt%and 1 .4 wt%respectively .The polymer emulsion obtained under this condition showed-core/shell morphology obviously , and had excellent water repellent performance that the water contact angle was 114°,the oil contact angle was 64°, the surface energy was 15.4 mN/m, and the cotton fabric finished with this water repellent reached 90 points.

  16. Application of light curing silica sol in water repellence finish of cotton fabric%光固化SiO2溶胶在棉织物拒水整理中的应用

    Institute of Scientific and Technical Information of China (English)

    田太洲; 闵洁; 徐进进; 蔡丹

    2015-01-01

    The light curing silica sol was prepared by sol- gel technology using tetraethylorthosilicate (TEOS) and 3- azidopropyltriethoxysilane as precursor, ammonia as catalyst, which was applied in water repel⁃lence on cotton fabrics with hydrophobic additives hexadecyltrimethoxysilane (HDTMS) as additive. The water repel ence property of fabric was endowed by dip- padding the light curing silica sol, then dipping into alkane siloxane, and then was exposed to UV light without curing. The treated cotton fabrics were characterized by scanning electron microscopy (SEM) and X- ray photoelectron spectroscopy (XPS). The results showed that the light curing silica sol nanoparticles were coated on the cotton fiber surface and increased the surface roughness. Contact angle results demonstrated that the water contact angle of the treated cotton fabric was 155° for 5μL and was stil greater than 135° after 30 times soaping.%利用溶胶-凝胶技术,以正硅酸四乙酯、3-叠氮丙基三乙氧基硅烷为前驱体,氨水为催化剂制备光固化二氧化硅溶胶,以十六烷基三甲氧基硅烷为拒水剂对棉织物进行拒水整理。先浸轧光固化二氧化硅溶胶,再浸渍烷烃硅氧烷,无需焙烘,通过紫外光照直接赋予织物拒水性能。采用扫描电镜、X射线光电子能谱仪对整理后的棉织物进行测试。结果表明,光固化二氧化硅溶胶沉积在织物表面,提高了棉织物的粗糙度。接触角测试表明,棉织物对水接触角(5μL)达到155°;整理后的棉织物经30次皂洗后,与水的接触角仍大于135°。

  17. Insect Repellent Properties of Melaleuca alternifolia

    Directory of Open Access Journals (Sweden)

    Mohamad Adib Bin Edris

    2016-08-01

    Full Text Available The aim of this study is to compare the use of plant-based insect repellents that are environment friendly with the use of insect repellents based on chemical substances which can be harmful to the environment and human health. The plant studied here is "tea tree"; its scientific name is Melaleuca alternifolia. Essential oil from this plant is extracted by steam distillation method. Based on the previous research, tea tree oil has antimicrobial, antifungal, anti-inflammatory, and insect repellent properties. Some experiments were done on tea tree oil to determine its insect repellent properties and the suitable concentration that can be used to make sure its repelling effect is optimum. The purpose of this determination is to avoid its harmful effect on humans because it can be toxic if it is used at high concentration. The results showed that tea tree oil repelled Tribolium castaneum. Furthermore, the toxicity assays also gave positive result where the tea tree oil has toxic properties against Solenopsis invicta. The lethal dose (LD of tea tree oil to kill 50% of a group of S. invicta is 23.52 µL/mL. This LD50 is determined by using the arithmetic method of Karber. Broadly, the results showed that M. alternifolia has insect repellent properties and shows toxicity against certain insects.

  18. HUMEDAD CRÍTICA Y REPELENCIA AL AGUA EN ANDISOLES BAJO COBERTURA DE Cupressus lusitanica y Quercus humboldtii EN LA CUENCA DE LA QUEBRADA PIEDRAS BLANCAS (MEDELLÍN, COLOMBIA CRITICAL MOISTURE AND WATER REPELLENCY ON ANDISOLS UNDER Cupressus lusitanica AND Quercus humboldtii COVER IN THE PIEDRAS BLANCAS WATERSHED ( MEDELLÍN, COLOMBIA

    Directory of Open Access Journals (Sweden)

    Bibiana Caballero Mejía

    2007-12-01

    Full Text Available En dos vertientes de la cuenca de la quebrada Piedras Blancas (Medellín, Colombia se estudió la relación humedad - persistencia de la repelencia al agua en la parte superficial de andisoles bajo dos coberturas vegetales: Cupressus lusitanica (ciprés y Quercus humboldtii (roble, en tres posiciones a lo largo de la vertiente de colinas bajas: superior, media e inferior y en dos condiciones de humedad: con la humedad de campo y con la humedad adquirida al equilibrar al aire durante dos días muestras que habían sido secadas a 105 °C. En cada sitio de la vertiente se ubicó una parcela de 6 m x 5 m y en ella se tomaron 60 muestras de suelo en una malla de 1 m x 0,5 m. La persistencia de la repelencia al agua se evaluó con el método del WDPT en muestras tamizadas a 1 mm. Se presentó un alto número de muestras fuertemente repelentes al agua en todas las condiciones de trabajo, siendo mayor la frecuencia en ciprés que en roble. Tanto la repelencia al agua como la humedad presentaron comportamiento diferencial por cobertura y por posición en la vertiente dentro de la misma cobertura. No se pudo establecer una relación consistente entre el contenido de humedad de las muestras y la persistencia de la repelencia al agua que presentaron, así como tampoco se pudo definir una zona de transición de humedad crítica para que se manifestara la repelencia al agua en ellas, en ninguna de las dos coberturas vegetales y en ninguna posición en la vertiente.In two hillside of the Piedras Blancas watershed ( Medellín, Colombia was studied the relation humidity - persistence of the water repellency on the surface of the andisols under two vegetable covers: Cupressus lusitanica (cypress and Quercus humboldtii (oak groves. These were found in three different positions along the side of low hills: upper, middle and lower grounds, as well as in two conditions of humidity: with the humidity acquired when equilibrated with the air during two days (samples

  19. STUDY ON THE WATER REPELLENT SILICONE-POLYURETHANE BLOCK COPOLYMERS%拒水型有机硅改性聚氨酯嵌段共聚物的合成与表征

    Institute of Scientific and Technical Information of China (English)

    张怀文; 杜淼; 王楠; 郑强

    2013-01-01

    以氨丙基硅氧烷偶联剂和端羟基聚二甲基硅氧烷(PDMS)为原料,合成了端氨丙基聚二甲基硅氧烷低聚物(SN2),并将其作为扩链剂,制备了有机硅-聚氨酯(Si-PU)嵌段共聚物.考察了聚氨酯预聚体的加料比(rNCO/OH)、SN2与聚氨酯预聚体的加料比(rNH2/NCO)对Si-PU嵌段共聚物溶液流变行为及其膜性能的影响.研究发现,该Si-PU共聚物的异丙醇溶液呈现较低的表观黏度及牛顿特性;成膜时,有机硅链段向表面迁移;膜表面对水的接触角达110°以上,且随着有机硅链段含量的增高而增大;共聚物膜的24 h吸水率较低(<1.5 wt%);但当有机硅链段含量过高时,吸水率反而增高.%Amino-terminated polydimethylsiloane ( SN2 ) was synthesized by using hydroxyl-terminated polydimethylsiloxane ( PDMS ) and aminopropyl siloxane coupling agent ( DB-912). And the silicone-polyurethane (Si-PU) block copolymer was synthesized by using SN2 as a chain extender and polyurethane prepolymer. The effects of the SN2 and prepolymer of polyurethane feed ratio on the rheological behavior of the copolymer solution in isopropanol (IPA) and the properties of its film were studied in detail. It was found that the Si-PU block copolymer IPA solution with a concentration of 25 wt% exhibited low apparent viscosity and the characteristics of Newtonian fluid within the measuring shear rate scope. During film casting,the SN2 blocks may migrate toward the surface,which led to a surface contact angle to water over 110°. With the increasing of SN2 block content,the surface contact angles of films to water increased slightly. When the films were soaked in the water for 24 h, the water absorptions were very low, and the water-repellence was pretty good. The copolymer film showed water absorption lower than 1. 5 wt% . With the increasing of SN2 block content, the water absorptions were very low and did not change a lot. However,if the content of SN2 block was too high

  20. Field evaluation of herbal mosquito repellents.

    Science.gov (United States)

    Das, N G; Nath, D R; Baruah, I; Talukdar, P K; Das, S C

    1999-12-01

    Repellent properties of Zanthoxylum armatum DC. Syn. Z. alatum Roxb. (Timur), Curcuma aromatica (Jungli haldi) and Azadirachta indica (Neem) oils were evaluated against mosquitoes in mustard (Brassica sp.) and coconut (Cocos sp.) oil base and compared with synthetic repellent. Dimethyl phthalate (DMP) as standard. Timur and jungli haldi afforded better protection in the both the base at all the concentrations. Tepellents in mustard oil gave longer protection time than those in coconut oil. At 0.57 mg/cm2 concentration timur oil gave significantly higher protection both in mustard (445 min) as well as coconut oil (404 min) than the other repellents and DMP.

  1. Ice repellency behaviour of superhydrophobic surfaces: Effects of atmospheric icing conditions and surface roughness

    Energy Technology Data Exchange (ETDEWEB)

    Momen, G., E-mail: gmomen@uqac.ca; Jafari, R.; Farzaneh, M.

    2015-09-15

    Highlights: • A novel view on ice repellency of superhydrophobic surfaces in terms of contact angle hysteresis, roughness and icing condition has been discussed. • This study is the first to deal with the effect of icing parameters on the ice repellency behaviour of superhydrophobic surfaces. • Two fabricated superhydrophobic surfaces with similar wettability behaviour showed different icephobic behaviour. • Superhydrophobic surfaces are not always icephobic and ice repellency is governed by icing condition parameters like liquid water content and water droplet size. • Lower liquid water content and smaller water droplet size promote ice-repellency behaviour of superhydrophobic surfaces. - Abstract: This paper presents a novel view on ice repellency of superhydrophobic surfaces in terms of contact angle hysteresis, surface roughness and icing condition. Ice repellency performance of two superhydrophobic silicone rubber nanocomposite surfaces prepared via spin coating and spray coating methods were investigated. High contact angle (>150°), low contact angle hysteresis (<6°) and roll-off property were found for both spin and spray coated samples. The results showed a significant reduction of ice adhesion strength on the spin-coated sample while ice adhesion strength on the spray-coated sample was found to be unexpectedly similar to that of the uncoated sample. Indeed, this research study showed that the icephobic properties of a surface are not directly correlated to its superhydrphobicity and that further investigations, like taking icing condition effect into account, are required. It was found that icephobic behaviour of the spray coated sample improved at lower levels of liquid water content (LWC) and under icing conditions characterized by smaller water droplet size.

  2. Rural buyers' perception about mosquito repellants

    Directory of Open Access Journals (Sweden)

    D. MEHTA

    2010-06-01

    Full Text Available Mosquito repellants prevent mosquito bites and prevention of "man-mosquito contact" is a critical factor in transmission and spread of any disease through mosquitoes particularly in rural area. There has been a long standing 'bias' towards rural buyers. The rural markets are considered rigid in the nature but it is not the case in real sense. Marketing to rural buyers is not only a challenge to the marketers but to the manufacturers, communicators, national planners and economists as well. That is why it has been necessary to understand the various aspects of selected rural areas and consumption pattern for such a fast growing market i.e. mosquito repellants and rural buyers’ perception towards such urban products. The present paper aims to find out the factors influencing the purchase decisions of rural buyers for mosquito repellants and to study the perceptions of present and potential rural buyers' of selected mosquito repellant brands.

  3. Liquid repellency by a moving plate

    Science.gov (United States)

    Bouillant, Ambre; Anais Gauthier Team; David Quere Team; Christophe Clanet Team

    2016-11-01

    Moving solids can repel impacting drops, owing to their motion. Provided the solid velocity is larger than a threshold value, air entrained at the vicinity of the moving plate prevents the drop from wetting, and makes it bounce. In addition, the rebound is oblique, which enhances the evacuation of liquid. We discuss experiments and models on this theme, and extend them to case of small droplets (such as formed in a spray) found to be even more efficiently repelled by the moving plate.

  4. Effect of Water-repellent Admixtures on Repair Mortars Made of Lime and Metakaolin%防水剂对石灰偏高岭土修补砂浆性能的影响

    Institute of Scientific and Technical Information of China (English)

    彭小芹; 曹春鹏; 季晓丽; 曾路

    2016-01-01

    以石灰和偏高岭土为主要材料,制备一种适用于岩土类建筑的修补砂浆.用桐油和硬脂酸钙两种防水剂来改善砂浆的耐水性,研究桐油和硬脂酸钙对砂浆强度、反应过程、吸水率和软化系数、干燥收缩的影响,并通过XRD和SEM 对砂浆进行物相分析和微观形貌观测.结果表明:桐油和硬脂酸钙可以显著提高石灰偏高岭土砂浆的耐水性,可使吸水率下降至2.5%以下;桐油和硬脂酸都会阻碍偏高岭土的火山灰反应,在一定程度上降低砂浆的强度,但28 d的抗压强度仍在5 M Pa以上,达到天然水硬性石灰N HL5的强度等级;桐油和硬脂酸钙会影响石灰偏高岭土砂浆的微观形态和结构,桐油使产物的颗粒更细小、更致密,硬脂酸钙则会使产物结构比较疏松.综合考虑砂浆强度、耐水性等因素,得出桐油和硬脂酸钙的最佳掺量分别为5%和1.5%.%A kind of repair mortar for geotechnical building was prepared with lime and metakaolin as major materials .Two kinds of water‐repellent admixtures (tung oil and calcium stearate) were used to im‐prove the water resistance of the mortars .Different properties of the mortars were evaluated ,such as strength ,the process of reaction ,water absorption ,softening coefficient and shrinkage .Phase and micro‐structure analysis of the mortars were carried out through XRD and SEM .The results show that tung oil and calcium stearate can improve water resistance of the mortars significantly .Water absorption of the mortars with tung oil or calcium stearate can be below 2 .5% .Tung oil and calcium stearate hinder the poz‐zolanic reaction of metakaolin ,which as a result decrease the mortars’ strength .But 28 d compressive strength of the mortars are all above 5 MPa .Also ,tung oil and calcium stearate can regulate the growth of products and affect the micromorphology and structure of mortars .Tung oil make the

  5. Monoterpenes from thyme (Thymus vulgaris) as potential mosquito repellents.

    Science.gov (United States)

    Park, Byeoung-Soo; Choi, Won-Sik; Kim, Jeong-Han; Kim, Kap-Ho; Lee, Sung-Eun

    2005-03-01

    Five monoterpenes (carvacrol, p-cymene, linalool, alpha-terpinene, and thymol) derived from the essential oil of thyme (Thymus vulgaris) were examined for their repellency against the mosquito Culex pipiens pallens. All 5 monoterpenes effectively repelled mosquitoes based on a human forearm bioassay. Alpha-terpinene and carvacrol showed significantly greater repellency than a commercial formulation, N,N-diethyl-m-methylbenzamide (deet), whereas thymol showed similar repellency to that of deet. The duration of repellency after application for all these monoterpenes was equal to or higher than that of deet. These findings indicate that a spray-type solution containing 2% alpha-terpinene may serve as an alternative mosquito repellent.

  6. Breath figures of two immiscible substances on a repellent surface

    Science.gov (United States)

    Guadarrama-Cetina, J.; González-Viñas, W.

    2013-05-01

    The understanding of the competition between different substances while condensing on a cold surface is of high interest in situations in which it is desirable to control their condensation rates and the formed morphologies. We do the experiments for mixtures of water and hexamethyldisiloxane vapors at several concentrations. The dropwise condensation of the vapors forms breath figures on a substrate that is repellant to both substances. We report the average radius of the drops for each specie as a function of time. Also, we pay attention to the evolution of the corresponding morphologies and the appearance of hybrid clusters.

  7. Insect Repellents: Protect Your Child from Insect Bites

    Science.gov (United States)

    ... Español Text Size Email Print Share Choosing an Insect Repellent for Your Child Page Content Mosquitoes, biting ... sunscreen needs to be reapplied often. Reactions to Insect Repellents If you suspect that your child is ...

  8. Repellence and toxicity of Schinus molle extracts on Blattella germanica.

    Science.gov (United States)

    Ferrero, A A; Chopa, C Sánchez; González, J O Werdin; Alzogaray, R A

    2007-06-01

    The biological activities of ethanol and petroleum ether extracts from leaves and fruits of Schinus molle against adults of Blattella germanica were examined by repellence test and topical application. All extracts produced significant repellent effect and mortality.

  9. Repellency, toxicity, and oviposition inhibition of vegetable extracts against greenhouse whitefly Trialeurodes vaporariorum (Westwood (Hemiptera: Aleyrodidae

    Directory of Open Access Journals (Sweden)

    Edgar Eduardo Mendoza-Garcia

    2014-03-01

    Full Text Available In a search for sustainable options of greenhouse whitefly Trialeurodes vaporariorum (Westwood management, the toxic and/or repellent potential of water, ethanolic, and acetonic extracts of Ambrosia artemisiifolia L. (Asteraceae, Comocladia engleriana Loes (Anacardiaceae, Piper auritum Kunth (Piperaceae, Raphanus raphanistrum L. (Brassicaceae, and Taraxacum officinale F.H. Wigg. aggr.* (Asteraceae were evaluated. Repellency was assessed by the cylinder method (olfactometer, while toxicity and oviposition inhibition were assessed by the leaf immersion method. Acetonic extracts did not cause any repellent or insecticidal effect. In contrast, 200 mg mL-1 water and ethanolic extracts of R. raphanistrum and ethanolic extract of A. artemisiifolia had the highest repellent activity (76%, 72%, and 69%, respectively although their activity decreased gradually over time. Ethanolic extracts of P. auritum (66% and R. raphanistrum (56% at 200 mg mL¹ were highlighted as being toxic, while the most effective in inhibiting oviposition were water extracts of R. raphanistrum (76.1% and P. auritum (72.0% and ethanolic extract of P. auritum (69.5%; however, concentrations lower than 60 mg mL-1 caused oviposition stimulation. Our results suggest that water and ethanolic extracts of R. raphanistrum and P. auritum represent a useful tool in integrated whitefly management.

  10. The impact of agriculture terraces on soil organic matter, aggregate stability, water repellency and bulk density. A study in abandoned and active farms in the Sierra de Enguera, Eastern Spain.

    Science.gov (United States)

    Cerdà, Artemi; Burguet, Maria; Keesstra, Saskia; Prosdocimi, Massimo; Di Prima, Simone; Brevik, Erik; Novara, Agata; Jordan, Antonio; Tarolli, Paolo

    2016-04-01

    Soil erosion, land degradation, lack of organic matter, erodible soils, rock outcrops… are a consequence of the human abuse and misuse of the soil resources. And this is a worldwide environmental issue (Novara et al., 2011; Vanlauwe et al., 2015; Musinguzi et al., 2015; Pereira et al., 2015; Mwagno et al., 2016). Agriculture terraces are a strategy to reduce the soil erosion, improve the soil fertility and allow the ploughing (Cerdà et al., 2010; Li et al., 2014). Although this idea is well accepted there are few scientific evidences that demonstrate that soils in the terraced areas are more stable, fertile and sustainable that the soil in non terraced areas. In fact, the ploughing in comparison to the abandoned or not ploughed land results in the soil degradation (Lieskovský and Kenderessy, 2014; Gao et al., 2015; Parras-Alcántara et al., 2014). This is mainly due to the lack of vegetation that increase the surface runoff (Cerdà et al., 1998; Keesstra et al., 2007). And why is necessary to develop also in terraced landscapes soil erosion control strategies (Mekonnen et al., 2015a; Mekonnen et al., 2015b; Prosdocimi et al., 2016). Our objective was to assess the soil organic matter content (Walkley and Black, 1934), the soil bulk density (ring method), the aggregate stabilility (drop impact) and the water repellency (Water Drop Penetration Time test) in four study sites in the Sierra de Enguera. Two sites were terraced: one abandoned 40 years before the measurements and the other still active with olive crops. And two control sites non-terraced. We used the paired plot strategy to compare the impact of terracing and abandonment. At each site we collected randomly 50 soil samples at 0-2 cm, 4-6 and 8-10 cm depth. At each sampling point 100 WDPT measurements where carried out, and one sample for the bulk density, and one for the organic matter, and one for the soil aggregate stability were collected. The soil surface samples shown the largest differences. The

  11. Effectiveness of Gel Repellents on Feral Pigeons

    Directory of Open Access Journals (Sweden)

    Birte Stock

    2013-12-01

    Full Text Available Millions of feral pigeons (Columba livia live in close association with the human population in our cities. They pose serious health risks to humans and lead to high economic loss due to damage caused to buildings. Consequently, house owners and city authorities are not willing to allow pigeons on their buildings. While various avian repellents are regularly introduced onto the market, scientific proof of efficacy is lacking. This study aimed at testing the effectiveness of two avian gel repellents and additionally examined their application from animal welfare standpoint. The gels used an alleged tactile or visual aversion of the birds, reinforced by additional sensory cues. We mounted experimental shelves with the installed repellents in a pigeon loft and observed the behavior of free-living feral pigeons towards the systems. Both gels showed a restricted, transient repellent effect, but failed to prove the claimed complete effectiveness. Additionally, the gels’ adhesive effect remains doubtful in view of animal welfare because gluing of plumage presents a risk to feral pigeons and also to other non-target birds. This study infers that both gels lack the promised complete efficacy, conflict with animal welfare concerns and are therefore not suitable for feral pigeon management in urban areas.

  12. Mosquito repellency of novel Trifluoromethylphenyl amides

    Science.gov (United States)

    Human diseases caused by mosquito-transmitted pathogens include malaria, dengue and yellow fever and are responsible for several million human deaths every year, according to the World Health Organization (WHO). Our current research projects focus on the development of new insecticides and repellent...

  13. Mode of action of insect repellents

    Science.gov (United States)

    The mode of action of DEET and other insect repellents has been a topic of interest since the discovery of DEET in the mid twentieth century. Nearly 60 years have passed since DEET applied topically to the skin was shown to be effective in preventing mosquito bites. With the discovery and characte...

  14. Pest repelling properties of ant pheromones

    DEFF Research Database (Denmark)

    Offenberg, Joachim

    2014-01-01

    Ants control pests via predation and physical deterrence; however, ant communication is based on chemical cues which may serve as warning signals to potential prey and other intruders. The presence of ant pheromones may, thus, be sufficient to repel pests from ant territories. This mini...

  15. Comparison of Repellency Effect of Mosquito Repellents for DEET, Citronella, and Fennel Oil

    Science.gov (United States)

    Yoon, Jong Kwang; Kim, Kang-Chang; Cho, Yeondong; Gwon, Yong-Dae; Cho, Han Sam; Heo, Yoonki; Park, Kihoon; Lee, Yang-Won; Kim, Mijeong; Oh, Yu-Kyoung; Kim, Young Bong

    2015-01-01

    To confirm that Korean Food and Drug Administration (KFDA) guidelines are applicable to test the efficacy of mosquito repellents, these guidelines were used to test the efficacy and complete protection times (CPTs) of three representative mosquito repellents: N,N-diethyl-3-methylbenzamide (DEET), citronella, and fennel oil. The repellency of citronella oil decreased over time, from 97.9% at 0 h to 71.4% at 1 h and 57.7% at 2 h, as did the repellency of fennel oil, from 88.6% at 0 h to 61.2% at 1 h and 47.4% at 2 h. In contrast, the repellency of DEET remained over 90% for 6 h. The CPT of DEET (360 min) was much longer than the CPTs of citronella (10.5 min) and fennel oil (8.4 min). These results did not differ significantly from previous findings, and hence confirm that the KFDA guidelines are applicable for testing the efficacy of mosquito repellents. PMID:26527362

  16. Typical Monoterpenes as Insecticides and Repellents against Stored Grain Pests

    Directory of Open Access Journals (Sweden)

    Suelen L. Reis

    2016-02-01

    Full Text Available Five monoterpenes naturally occurring in essential oils were tested for their insecticidal and repellent activities against the bruchid beetle Callosobruchus maculatus and the maize weevil Sitophilus zeamais. The monoterpenes were highly efficient as inducers of mortality or repellency against both insect species. They were more efficient in their fumigant activity against C. maculatus than against S. zeamais, while this profile of action was inverted when considering the repellent activities. Eugenol was one the most effective fumigants against both insects and one the most effective repellent against C. maculatus, while citronellal and geranial were one the most effective repellents against S. zeamais. Functional and positional isomerism of the monoterpenes pairs appears to exert little or no influence on theirs effects, especially in case of repellency. The validation of the insecticidal/repellent efficacy of isolated monoterpenes may permit a more advantageous, rapid, economic and optimized approach to the identification of promising oils for commercial formulations when combined with ethnobotanical strategies.

  17. PERBANDINGAN EFEKTIFITAS REPELLENT KOMERSIL DENGAN EKSTRAK KULIT JERUK PURUT UNTUK MENCEGAH GIGITAN NYAMUK Aedes aegypti

    OpenAIRE

    Wana; Ishak, Hasanuddin; Manyullei, Syamsuar

    2015-01-01

    Repellent merupakan bahan yang mempunyai kemampuan untuk melindungi manusia dari gigitan nyamuk. Repellent kimia yang paling sering digunakan adalah repellent yang mengandung DEET yang beredar di supermarket, pasaran maupun warung-warung kecil. Selain itu adapula repellent alami yang dapat digunakan, yaitu kandungan minyak atsiri pada kulit jeruk purut. Penelitian ini bertujuan untuk membandingkan efektivitas repellent komersil yaitu repellent merek SL dan repellent alami yaitu minyak at...

  18. 反应型含磷氮元素的聚硅氧烷的制备及其对棉织物拒水阻燃性能研究%Synthesis of iodine butyl-dimethoxy dibenzyloxyphosphoiyl propionamide polysiloxane and its water repellency and flame retardancy on cotton fabric

    Institute of Scientific and Technical Information of China (English)

    董朝红; 吕洲; 朱平

    2013-01-01

    将 N-羟甲基-3-(二甲氧基膦酰基)丙酰胺、氢氧化钠、碘丁基硅油(IBu-PDMS)为原料,合成了反应型的具有拒水阻燃双重功能的碘丁基-co-N-甲氧基-3-(二甲氧基膦酰基)丙酰胺聚硅氧烷〔(I B-c o-N-MD-PA)PDMS〕,其与棉织物能以共价键结合,利用 FT-IR、1 H NMR表征了其结构。利用 TGA、氧指数仪分析了拒水阻燃多功能棉织物的热性能及其阻燃性与阻燃机理,通过测定其接触角表征其拒水性。结果表明,制备的(IB-co-N-MDPA)PDMS 与棉纤维反应,使棉织物有拒水性能,它实际上控制了棉纤维的热裂解,使纤维发生脱水炭化,促进了炭化层的形成,最后的残炭量由10.5%提高至42.4%,棉织物的极限氧指数从18提高到28,拒水等级为90,接触角从88.37°提高到119.73°。%Reactive iodine butyl-co-N-methoxy-3-(dimethoxy dibenzyloxyphosphoiyl)propionamide polysiloxane [(IB-co-N-MDPA)PDMS)]with double functions of water repellency and flame retardancy was synthesized using N-methylol-3-(dimethoxy dibenzyloxyphosphoiyl)acrylic amide,sodium hydroxide and poly (4-iodo-n-butoxy)methylsiloxane as raw materials.The structure of (IB-co-N-MDPA)PDMS was characterized by the FT-IR and 1 H NMR.It could be combined with cotton by covalent bonds.The morphology,thermal proper-ties,flame retardency and flame retardent mechanism of the multifunctional cotton fabric were analyzed using TGA and limit oxygen index (LOI)instruments.The contact angle and water repellency of it were tested.The results showed that(IB-co-N-MDPA)PDMS reacted with cotton fiber to form crosslinked membrane on the sur-face,which had water repellency function.And also the coexistence of silicon,nitrogen and phosphorus could produce synergistic flame-retardant effect.On one hand,the melting siloxane polymer formed a covering layer on the surface of fiber when the retardants were heated.The covering layer became a protective screen between the condensed phase and flame.On the

  19. Limitation of using synthetic human odours to test mosquito repellents

    Directory of Open Access Journals (Sweden)

    Mbeyela Edgar

    2009-07-01

    Full Text Available Abstract Background Gold-standard tests of mosquito repellents involve exposing human volunteers to host-seeking mosquitoes, to assess the protective efficacy of the repellents. These techniques are not exposure-free and cannot be performed prior to toxicological evaluation. It is postulated that synthetic lures could provide a useful assay that mimics in-vivo conditions for use in high-throughput screening for mosquito repellents. Methods This paper reports on a semi-field evaluation of repellents using a synthetic blend of human derived attractants for the malaria vector, Anopheles gambiae sensu stricto Different concentrations of known repellents, N, N diethyl-3-methylbenzamide (deet and Para-methane-3, 8, diol (PMD were added into traps baited with the synthetic blend, and resulting changes in mosquito catches were measured. Results All test concentrations of deet (0.001% to 100% reduced the attractiveness of the synthetic blend. However, PMD was repellent only at 0.25%. Above this concentration, it significantly increased the attractiveness of the blend. There was no relationship between the repellent concentrations and the change in mosquito catches when either deet (r2 = 0.033, P = 0.302 or PMD (r2 = 0.020, P = 0.578 was used. Conclusion It is concluded that while some repellents may reduce the attractiveness of synthetic human odours, others may instead increase their attractiveness. Such inconsistencies indicate that even though the synthetic attractants may provide exposure-free and consistent test media for repellents, careful selection and multiple-repellent tests are necessary to ascertain their suitability for use in repellent screening. The synthetic odour blend tested here is not yet sufficiently refined to serve as replacement for humans in repellent testing, but may be developed further and evaluated in different formats for exposure free repellent testing purposes.

  20. Rural buyers' perception about mosquito repellants

    OpenAIRE

    Mehta, D.; Anand GARG; Naveen K MEHTA

    2010-01-01

    Mosquito repellants prevent mosquito bites and prevention of "man-mosquito contact" is a critical factor in transmission and spread of any disease through mosquitoes particularly in rural area. There has been a long standing 'bias' towards rural buyers. The rural markets are considered rigid in the nature but it is not the case in real sense. Marketing to rural buyers is not only a challenge to the marketers but to the manufacturers, communicators, national planners and economists as well. Th...

  1. EFFECTS OF MOSQUITO REPELLENTS ON PULMONARY FUNCTIONS

    Directory of Open Access Journals (Sweden)

    Venkatesh

    2014-08-01

    Full Text Available Mosquito bite transmits diseases like Malaria, Filaria, Dengue etc. and usage of repellents is very common and has been in use for a long time. The smoke contains Polyaromatic Hydrocarbons, Aldehydes and Ketones. Review of literature has shown ill effects of this smoke. Hence we intended to study the effect of mosquito repellents on lung functions. This study would be important to create awareness regarding usage of mosquito repellent and to adapt to non-harmful methods of preventing mosquito bites. PFT parameters FVC, FEV1, FEV1/ FVC %, FEF 25-75 and PEFR were recorded in mosquito coil users, liquidator’s users and controls that used neither. It was found that FVC and FEV1 were significantly less in coil and liquidators users compared to controls (P < 0.05. Also it was found that in both coil users and liquidator users FVC, FEV1, FEF 25 -75 and PEFR and showed progressive decline with increased duration of usage (P < 0.05. Hence it was concluded that mosquito coils and liquidators can cause progressive decline in lung functions. Alternative methods to combat mosquito menace, like personal and environmental hygiene and non-chemical methods of protection are therefore recommended.

  2. DEET (N,N-diethyl-meta-toluamide)/PMD (para-menthane-3,8-diol) repellent-treated mesh increases Culicoides catches in light traps.

    Science.gov (United States)

    Murchie, A K; Clawson, S; Rea, I; Forsythe, I W N; Gordon, A W; Jess, S

    2016-09-01

    Biting midges (Culicoides spp.) are vectors of bluetongue and Schmallenberg viruses. Treatment of mesh barriers is a common method for preventing insect-vectored diseases and has been proposed as a means of limiting Culicoides ingression into buildings or livestock transporters. Assessments using animals are costly, logistically difficult and subject to ethical approval. Therefore, initial screening of test repellents/insecticides was made by applying treatments to mesh (2 mm) cages surrounding Onderstepoort light traps. Five commercial treatments were applied to cages as per manufacturers' application rates: control (water), bendiocarb, DEET/p-menthane-3,8-diol (PMD) repellent, Flygo (a terpenoid based repellent) and lambda-cyhalothrin. The experimental design was a 5 × 5 Latin square, replicated in time and repeated twice. Incongruously, the traps surrounded by DEET/PMD repellent-treated mesh caught three to four times more Obsoletus group Culicoides (the commonest midge group) than the other treatments. A proposed hypothesis is that Obsoletus group Culicoides are showing a dose response to DEET/PMD, being attracted at low concentrations and repelled at higher concentrations but that the strong light attraction from the Onderstepoort trap was sufficient to overcome close-range repellence. This study does not imply that DEET/PMD is an ineffective repellent for Culicoides midges in the presence of an animal but rather that caution should be applied to the interpretation of light trap bioassays.

  3. Nootkatone is a repellent for Formosan subterranean termite (Coptotermes formosanus).

    Science.gov (United States)

    Zhu, B C; Henderson, G; Chen, F; Maistrello, L; Laine, R A

    2001-03-01

    We examined the behavior of Formosan subterranean termites toward one of the components of vetiver grass oil, the roots of which manufacture insect repellents. We found nootkatone, a sesquiterpene ketone, isolated from vetiver oil is a strong repellent and toxicant to Formosan subterranean termites. The lowest effective concentration tested was 10 micrograms/g substrate. This is the first report of nootkatone being a repellent to insects.

  4. Mini Review: Mode of Action of Mosquito Repellents

    Science.gov (United States)

    2013-01-01

    Mini review: Mode of action of mosquito repellents Joseph C. Dickens ⇑, Jonathan D. Bohbot United States Department of Agriculture, Agricultural...Modulation a b s t r a c t The mode of action of mosquito repellents remains a controversial topic. However, electrophysiological studies and molecular...annoyance that can disrupt outdoor activities. The use of repellents decreases contacts between mosquitoes and their hosts, and may even lower the rate of

  5. Rodent-repellent studies. III. Advanced studies in the evaluation of chemical repellents

    Science.gov (United States)

    Bellack, E.; DeWitt, J.B.

    1949-01-01

    In order to bridge the gap between preliminary screening of chemicals for potential rodent repellency and the application ofthese compounds to paper cartons, more advanced studies in the evaluation ofpromising materials have been carried out. These studies have resulted in: (1) a modification of the food acceptance technique which eliminates doubtful compounds and also provides a closer analogy to the ultimate goal, and (2) a method for rapidly testing chemicals incorporated in paper. When the results of these latter tests are expressed as a function of time, it can be shown that a distinct correlation exists between the deterrency exhibited by treated paper and the repellency of treated food.

  6. Fabrication of durable super-repellent surfaces on cotton fabric with liquids of varying surface tension: Low surface energy and high roughness

    Science.gov (United States)

    Singh, Arun K.; Singh, Jayant K.

    2017-09-01

    In this study, we have developed super-repellent surface on cotton fabric via a facile and eco-friendly strategy using zirconia particles with water-soluble siloxane emulsion. The coated fabric using zirconia-siloxane (ZS) coating showed super-repellency of liquids with surface tension >47.7 mN/m, like water, mixtures of isopropyl alcohol with deionized water (2% and 5%, v/v), and ethylene glycol with contact angle of 158°, 155°, 153° and 152°, respectively. Furthermore, the coated fabric displays low sliding angle, materials with ability to repel water in the presence of oily pollutants are very useful in application related to sea water. Thus as-prepared coated fabric, with dual functionality, is a promising material for many applications including anti-wetting, self-cleaning, support for aquatic floating devices and as a filtration material for rapid and continuous oil-water separation.

  7. Repellent effects of pongam oil on settlement and oviposition of the common greenhouse whitefly Trialeurodes vaporariorum on chrysanthemum

    Institute of Scientific and Technical Information of China (English)

    ROMAN PAVELA; GERHARD HERDA

    2007-01-01

    The repellent activities, including host deterrence and anti-oviposion, of pongam oil against the adults of the common greenhouse whitefly Trialeurodes vaporariorum Westwood in greenhouses were tested. Chrysanthemum plants treated with different concentrations (0.5%-2.0%) of water-suspended pongam oil showed relatively longlasting host deterrent and anti-oviposition effects on the adults of greenhouse whitefly. Although the repellent effect declined in time and concentration, strong effects on the reduction of oviposition were found, which lasts, dependent on concentration at least 12 days after application.

  8. Observations on Snake Repellent Property of Some Plant Extracts

    Directory of Open Access Journals (Sweden)

    D.M. Renapurkar

    1991-01-01

    Full Text Available The repellent property of certain plant extracts and oils against snakes has been investigated. For this purpose 15 hexane extracts of plants and 11 oils were tested in the laboratory in a specially designed cage. Out of the materials tested. Across calamus extract and pine oil were found to exhibit excellent snake repellent property.

  9. Multiple activities of insect repellents on odorant receptors in mosquitoes

    Science.gov (United States)

    Several lines of evidence suggest that insect repellent molecules reduce mosquito-host contacts by interacting with odorants and odorant receptors (ORs) ultimately affecting olfactory-driven behaviors. We describe the molecular effects of ten insect repellents and a pyrethroid insecticide with known...

  10. Identification of mosquito repellent odours from Ocimum forskolei.

    Science.gov (United States)

    Dekker, Teun; Ignell, Rickard; Ghebru, Maedot; Glinwood, Robert; Hopkins, Richard

    2011-09-22

    Native mosquito repellent plants have a good potential for integrated mosquito control in local settings. Ocimum forskolei, Lamiaceae, is used in Eritrea as a spatial mosquito repellent inside houses, either through crushing fresh plants or burning dry plants. We verified whether active repellent compounds could be identified using gas-chromatography coupled electroantennogram recordings (GC-EAD) with headspace extracts of crushed plants. EAD active compounds included (R)-(-)-linalool, (S)-(+)-1-octen-3-ol, trans-caryophyllene, naphthalene, methyl salicylate, (R)-(-)-α-copaene, methyl cinnamate and (E)-ocimene. Of these compounds (R)-(-)-linalool, methyl cinnamate and methyl salicylate reduced landing of female Aedes aegypti on human skin-odor baited tubes. The latter two are novel mosquito repellent compounds. The identification of mosquito repellent compounds contributes to deciphering the mechanisms underlying repulsion, supporting the rational design of novel repellents. The three mosquito repellent compounds identified in this study are structurally dissimilar, which may indicate involvement of different sensory neurons in repulsion. Repulsion may well be enhanced through combining different repellent plants (or their synthetic mimics), and can be a locally sustainable part in mosquito control efforts.

  11. Repellent activity of five essential oils against Culex pipiens.

    Science.gov (United States)

    Erler, F; Ulug, I; Yalcinkaya, B

    2006-12-01

    Essential oils extracted from the seeds of anise (Pimpinella anisum), dried fruits of eucalyptus (Eucalyptus camaldulensis), dried foliage of mint (Mentha piperita) and basil (Ocimum basilicum) and fresh foliage of laurel (Laurus nobilis) were tested for their repellency against the adult females of Culex pipiens. All essential oils showed repellency in varying degrees, eucalyptus, basil and anise being the most active.

  12. Repellents Inhibit P450 Enzymes in Stegomyia (Aedes) aegypti

    Science.gov (United States)

    Jaramillo Ramirez, Gloria Isabel; Logan, James G.; Loza-Reyes, Elisa; Stashenko, Elena; Moores, Graham D.

    2012-01-01

    The primary defence against mosquitoes and other disease vectors is often the application of a repellent. Despite their common use, the mechanism(s) underlying the activity of repellents is not fully understood, with even the mode of action of DEET having been reported to be via different mechanisms; e.g. interference with olfactory receptor neurones or actively detected by olfactory receptor neurones on the antennae or maxillary palps. In this study, we discuss a novel mechanism for repellence, one of P450 inhibition. Thirteen essential oil extracts from Colombian plants were assayed for potency as P450 inhibitors, using a kinetic fluorometric assay, and for repellency using a modified World Health Organisation Pesticide Evaluations Scheme (WHOPES) arm-in cage assay with Stegomyia (Aedes) aegypti mosquitoes. Bootstrap analysis on the inhibition analysis revealed a significant correlation between P450-inhibition and repellent activity of the oils. PMID:23152795

  13. The mysterious multi-modal repellency of DEET

    Science.gov (United States)

    DeGennaro, Matthew

    2015-01-01

    DEET is the most effective insect repellent available and has been widely used for more than half a century. Here, I review what is known about the olfactory and contact mechanisms of DEET repellency. For mosquitoes, DEET has at least two molecular targets: Odorant Receptors (ORs) mediate the effect of DEET at a distance, while unknown chemoreceptors mediate repellency upon contact. Additionally, the ionotropic receptor Ir40a has recently been identified as a putative DEET chemosensor in Drosophila. The mechanism of how DEET manipulates these molecular targets to induce insect avoidance in the vapor phase is also contested. Two hypotheses are the most likely: DEET activates an innate olfactory neural circuit leading to avoidance of hosts (smell and avoid hypothesis) or DEET has no behavioral effect on its own, but instead acts cooperatively with host odors to drive repellency (confusant hypothesis). Resolving this mystery will inform the search for a new generation of insect repellents. PMID:26252744

  14. Repellents inhibit P450 enzymes in Stegomyia (Aedes aegypti.

    Directory of Open Access Journals (Sweden)

    Gloria Isabel Jaramillo Ramirez

    Full Text Available The primary defence against mosquitoes and other disease vectors is often the application of a repellent. Despite their common use, the mechanism(s underlying the activity of repellents is not fully understood, with even the mode of action of DEET having been reported to be via different mechanisms; e.g. interference with olfactory receptor neurones or actively detected by olfactory receptor neurones on the antennae or maxillary palps. In this study, we discuss a novel mechanism for repellence, one of P450 inhibition. Thirteen essential oil extracts from Colombian plants were assayed for potency as P450 inhibitors, using a kinetic fluorometric assay, and for repellency using a modified World Health Organisation Pesticide Evaluations Scheme (WHOPES arm-in cage assay with Stegomyia (Aedes aegypti mosquitoes. Bootstrap analysis on the inhibition analysis revealed a significant correlation between P450-inhibition and repellent activity of the oils.

  15. Field evaluation of picaridin repellents reveals differences in repellent sensitivity between Southeast Asian vectors of malaria and arboviruses.

    Directory of Open Access Journals (Sweden)

    Karel Van Roey

    2014-12-01

    Full Text Available Scaling up of insecticide treated nets has contributed to a substantial malaria decline. However, some malaria vectors, and most arbovirus vectors, bite outdoors and in the early evening. Therefore, topically applied insect repellents may provide crucial additional protection against mosquito-borne pathogens. Among topical repellents, DEET is the most commonly used, followed by others such as picaridin. The protective efficacy of two formulated picaridin repellents against mosquito bites, including arbovirus and malaria vectors, was evaluated in a field study in Cambodia. Over a period of two years, human landing collections were performed on repellent treated persons, with rotation to account for the effect of collection place, time and individual collector. Based on a total of 4996 mosquitoes collected on negative control persons, the overall five hour protection rate was 97.4% [95%CI: 97.1-97.8%], not decreasing over time. Picaridin 20% performed equally well as DEET 20% and better than picaridin 10%. Repellents performed better against Mansonia and Culex spp. as compared to aedines and anophelines. A lower performance was observed against Aedes albopictus as compared to Aedes aegypti, and against Anopheles barbirostris as compared to several vector species. Parity rates were higher in vectors collected on repellent treated person as compared to control persons. As such, field evaluation shows that repellents can provide additional personal protection against early and outdoor biting malaria and arbovirus vectors, with excellent protection up to five hours after application. The heterogeneity in repellent sensitivity between mosquito genera and vector species could however impact the efficacy of repellents in public health programs. Considering its excellent performance and potential to protect against early and outdoor biting vectors, as well as its higher acceptability as compared to DEET, picaridin is an appropriate product to evaluate the

  16. Field evaluation of picaridin repellents reveals differences in repellent sensitivity between Southeast Asian vectors of malaria and arboviruses.

    Science.gov (United States)

    Van Roey, Karel; Sokny, Mao; Denis, Leen; Van den Broeck, Nick; Heng, Somony; Siv, Sovannaroth; Sluydts, Vincent; Sochantha, Tho; Coosemans, Marc; Durnez, Lies

    2014-12-01

    Scaling up of insecticide treated nets has contributed to a substantial malaria decline. However, some malaria vectors, and most arbovirus vectors, bite outdoors and in the early evening. Therefore, topically applied insect repellents may provide crucial additional protection against mosquito-borne pathogens. Among topical repellents, DEET is the most commonly used, followed by others such as picaridin. The protective efficacy of two formulated picaridin repellents against mosquito bites, including arbovirus and malaria vectors, was evaluated in a field study in Cambodia. Over a period of two years, human landing collections were performed on repellent treated persons, with rotation to account for the effect of collection place, time and individual collector. Based on a total of 4996 mosquitoes collected on negative control persons, the overall five hour protection rate was 97.4% [95%CI: 97.1-97.8%], not decreasing over time. Picaridin 20% performed equally well as DEET 20% and better than picaridin 10%. Repellents performed better against Mansonia and Culex spp. as compared to aedines and anophelines. A lower performance was observed against Aedes albopictus as compared to Aedes aegypti, and against Anopheles barbirostris as compared to several vector species. Parity rates were higher in vectors collected on repellent treated person as compared to control persons. As such, field evaluation shows that repellents can provide additional personal protection against early and outdoor biting malaria and arbovirus vectors, with excellent protection up to five hours after application. The heterogeneity in repellent sensitivity between mosquito genera and vector species could however impact the efficacy of repellents in public health programs. Considering its excellent performance and potential to protect against early and outdoor biting vectors, as well as its higher acceptability as compared to DEET, picaridin is an appropriate product to evaluate the epidemiological

  17. Correlation between chemical structure and rodent repellency of benzoic acid derivatives

    Science.gov (United States)

    Fearn, J.E.; DeWitt, J.B.

    1965-01-01

    Sixty-five benzoic acid derivatives were either prepared or obtained from commercial concerns, tested for rat repellency, and their indices of repellency computed. The data from these tests were considered analytically for any correlation between chemical structure and rat repellency. The results suggest a qualitative relationship which is useful in deciding probability of repellency in other compounds.

  18. Synthesis of Fluorinated Polyacrylate Emulsion and Water -Repelling Capability of Fluorocarbon Paint and Coating Made of the Emulsion%氟代聚丙烯酸酯乳液的合成及其用于氟碳涂料的防水性能

    Institute of Scientific and Technical Information of China (English)

    宁姣姣; 安秋凤; 吴婧; 雷宁

    2013-01-01

    A kind of quaternary irregularly - copolymerized fluorinated polyacrylate emulsion (abridged as FSHC) was prepared by emulsion copolymerization of perfluoroalkylethyl acrylate (FA) , octadecyl methacrylate (SMA) , 2-hydroxypropyl acrylate (HPA) and 4 - chloromethyl styrene (CMS) in the presence of anionic/ nonionic surfactants as the mixed emulsifier and ( NH4)2S2O8 as the initiator. As-synthesized FSHC emulsion was then used to prepare water - borne paint and coating with desired water-repelling capability. The chemical structure of as - synthesized FSHC emulsion was analyzed by infrared spectrometry and nuclear magnetic resonance spectroscopy, and its size distribution and Zeta potential were determined with a nanoscale particle analyzer and a Zeta potential analyzer. Moreover, the chemical states of typical elements on the surface of the coating made of FSHC emulsion were analyzed by means of X-ray photoelectron spectroscopy, and the water contact angle of the coating was measured with a contact angle meter. It was found that as - synthesized FSHC emulsion had anticipated chemical structure, and its average size and Zeta potential were 146.2 nm and -21.2 mV. Besides, the coating made of FSHC emulsion contained a large amount of F on the surface, due to transfer of F-containing groups to the coating surface. As a result, as-obtained fluorocarbon coating had excellent water-repelling capability. Moreover, the paint and coating made of FSHC emulsion had good water resistance, showing a water contact angle of 128.6° .%为了制备一种廉价且具有优异防水性的水性涂料,用氟碳乳液,以阴/非离子复合表面活性剂为乳化剂,过硫酸铵为引发剂,通过乳液聚合法制得了全氟烷基乙基丙烯酸酯(FA)-甲基丙烯酸十八醇酯(SMA)-丙烯酸羟丙酯(HPA)-对氯甲基苯乙烯(CMS)四元无规共聚氟代聚丙烯酸酯乳液(FSHC),采用红外光谱仪(IR),核磁共振氢谱(1H-NMR),纳米粒度仪及Zeta电位分析仪,光电

  19. Performance of the plant-based repellent TT-4302 against mosquitoes in the laboratory and field and comparative efficacy to 16 mosquito repellents against Aedes aegypti (Diptera: Culicidae).

    Science.gov (United States)

    Bissinger, B W; Schmidt, J P; Owens, J J; Mitchell, S M; Kennedy, M K

    2014-03-01

    Repellent efficacy of the plant-based repellent, TT-4302 (5% geraniol), was compared with 16 other products in laboratory arm-in-cage trials against Aedes aegypti (L). Eight repellents (Badger, BioUD, Burt's bees, California Baby, Cutter Natural, EcoSMART, Herbal Armor, and SkinSmart) exhibited a mean repellency below 90% to Ae. aegypti at 0.5 h after application. Three repellents (Buzz Away Extreme, Cutter Advanced, and OFF! Botanicals lotion) fell below 90% repellency 1.5 h after application. TT-4302 exhibited 94.7% repellency 5 h posttreatment, which was a longer duration than any of the other repellents tested. The positive control, 15% DEET (OFF! Active), was repellent for 3 h before activity dropped below 90%. Additional arm-in-cage trials comparing TT-4302 with 15% DEET were carried out against Anopheles quadrimaculatus Say. At 6 h after treatment, TT-4302 provided 95.2% repellency while DEET exhibited 72.2%. In North Carolina field trials, TT-4302 provided 100% repellency 5 h after application against Aedes albopictus Skuse while DEET provided 77.6% repellency. These results demonstrate that TT-4302 is an efficacious plant-based repellent that provides an extended duration of protection compared with many other commercially available products.

  20. Nectar Theft and Floral Ant-Repellence: A Link between Nectar Volume and Ant-Repellent Traits?

    Science.gov (United States)

    Ballantyne, Gavin; Willmer, Pat

    2012-01-01

    As flower visitors, ants rarely benefit a plant. They are poor pollinators, and can also disrupt pollination by deterring other flower visitors, or by stealing nectar. Some plant species therefore possess floral ant-repelling traits. But why do particular species have such traits when others do not? In a dry forest in Costa Rica, of 49 plant species around a third were ant-repellent at very close proximity to a common generalist ant species, usually via repellent pollen. Repellence was positively correlated with the presence of large nectar volumes. Repellent traits affected ant species differently, some influencing the behaviour of just a few species and others producing more generalised ant-repellence. Our results suggest that ant-repellent floral traits may often not be pleiotropic, but instead could have been selected for as a defence against ant thieves in plant species that invest in large volumes of nectar. This conclusion highlights to the importance of research into the cost of nectar production in future studies into ant-flower interactions. PMID:22952793

  1. 蚊虫驱避剂的驱避机理研究%Repelling mechanism of mosquitoes repellent

    Institute of Scientific and Technical Information of China (English)

    廖圣良; 姜志宽; 宋杰; 王宗德; 韩招久; 陈金珠

    2012-01-01

    A review about the research of repelling mechanism is presented.Two mainstream hypotheses possible repelling mechanisms have been proposed:repellent interferes with the mosquitoes olfactory system to block the recognition of the host odor,therefore,mosquitoes can' t detect the existance of the host ; or mosquitoes evade host after its olfactory neuron is activated by repellent.Some research relating repellent in the author(s) laboratory was introduced as well,especially the investigation on repelling mechanism from the perspective of association between repellent and attractant.%本文就蚊虫驱避机理的研究进行了综述,详细介绍了目前两类主流的驱避机理假说:驱避剂干扰嗅觉系统以阻断蚊虫对宿主气味的识别、驱避剂激活嗅觉神经元引起蚊虫的主动躲避行为.介绍了笔者所在实验室近几年对驱避剂进行的相关研究,以及从驱避剂与引诱剂缔合作用的角度对驱避机理的研究.

  2. Essential Oil Repellents- A short Review

    Directory of Open Access Journals (Sweden)

    R V GEETHA

    2014-06-01

    Full Text Available Mosquitoes are the most important of insects in terms of public health importance which transmit a number of diseases such as dengue, chikungunya, Japanese B encephalitis, filariasis and malaria, causing millions of deaths every year. Mosquito control and personal protection from mosquito bites are currently the most important measures to prevent these diseases. Essential oils from plants have been recognized as important natural resources of insecticides because some are selective, biodegrade to non-toxic products and have few effects on non-target organisms and environment. Essential oils are volatile mixtures of hydrocarbons with a diversity of functional groups, and their repellent activity has been linked to the presence of mono - terpenes and sesquiterpenes. In some cases, these chemicals can work synergistically, improving their effectiveness. The aim of this review is to highlight the significance of essential oil from Cymbopogon winterianus Jowitt, Azadirchata indica, Lavandula angustifolia, Mentha piperita for control of vector- borne disease

  3. Pest repellent properties of ant pheromones

    DEFF Research Database (Denmark)

    Offenberg, Joachim

    2012-01-01

    Many ant species are efficient control agents against a wide range of pest insects in many crops. They control pest insects via predation; however, ant communication is based on chemical cues which may be eavesdropped by potential prey and serve as chemical warning signals. Thus, the presence...... of ant pheromones may be sufficient to repel pest insects from ant territories. The study of ant semiochemicals is in its infancy, yet, evidence for their potential use in pest management is starting to build up. Pheromones from four of five tested ant species have been shown to deter herbivorous insect...... prey and competing ant species are also deterred by ant deposits, whereas ant symbionts may be attracted to them. Based on these promising initial findings, it seems advisable to further elucidate the signaling properties of ant pheromones and to test and develop their use in future pest management....

  4. Using Repellent Products to Protect against Mosquito-Borne Illnesses

    Science.gov (United States)

    ... Us Share Using Repellent Products to Protect against Mosquito-Borne Illnesses More Information CDC-Avoid Mosquito Bites ... safety precautions . Top of Page Finding EPA-Registered Mosquito Adulticides and Larvicides The National Pesticide Information Center's ...

  5. Prevention of vector transmitted diseases with clove oil insect repellent.

    Science.gov (United States)

    Shapiro, Rochel

    2012-08-01

    Vector repellent is one element in the prevention of vector-borne diseases. Families that neglect protecting their children against vectors risk their children contracting illnesses such as West Nile virus, eastern equine encephalitis, Lyme disease, malaria, dengue hemorrhagic fever, yellow fever, babesiosis, Crimean-Congo hemorrhagic fever, Rocky Mountain spotted fever, Southern tick-associated rash illness, ehrlichiosis, tick-borne relapsing fever, tularemia, and other insect and arthropod related diseases (CDC, 2011). Identification of families at risk includes screening of the underlying basis for reluctance to apply insect repellent. Nurses and physicians can participate in a positive role by assisting families to determine the proper prophylaxis by recommending insect repellent choices that are economical, safe, and easy to use. A holistic alternative might include the suggestion of clove oil in cases where families might have trepidations regarding the use of DEET on children. This article will explore the safety and effectiveness of clove oil and its use as an insect repellent.

  6. Comparative repellency of 38 essential oils against mosquito bites.

    Science.gov (United States)

    Trongtokit, Yuwadee; Rongsriyam, Yupha; Komalamisra, Narumon; Apiwathnasorn, Chamnarn

    2005-04-01

    The mosquito repellent activity of 38 essential oils from plants at three concentrations was screened against the mosquito Aedes aegypti under laboratory conditions using human subjects. On a volunteer's forearm, 0.1 mL of oil was applied per 30 cm2 of exposed skin. When the tested oils were applied at a 10% or 50% concentration, none of them prevented mosquito bites for as long as 2 h, but the undiluted oils of Cymbopogon nardus (citronella), Pogostemon cablin (patchuli), Syzygium aromaticum (clove) and Zanthoxylum limonella (Thai name: makaen) were the most effective and provided 2 h of complete repellency. From these initial results, three concentrations (10%, 50% and undiluted) of citronella, patchouli, clove and makaen were selected for repellency tests against Culex quinquefasciatus and Anopheles dirus. As expected, the undiluted oil showed the highest protection in each case. Clove oil gave the longest duration of 100% repellency (2-4 h) against all three species of mosquito.

  7. Relative efficacy of various oils in repelling mosquitoes.

    Science.gov (United States)

    Ansari, M A; Razdan, R K

    1995-09-01

    Field studies were carried out to determine the relative efficacy of repellant action of vegetable, essential and chemical base oils against vector mosquitoes. Results revealed that essential oils viz. Cymbopogan martinii martinii var. Sofia (palmarosa), Cymbopogan citratus (lemon grass) and Cymbopogan nardus (citronella) oils are as effective as chemical base oil namely mylol. These oils provide almost complete protection against Anopheles culicifacies and other anopheline species. Per cent protection against Culex quinquefasciatus ranged between 95-96%. Camphor (C. camphora) oil also showed repellent action and provided 97.6% protection against An. culicifacies and 80.7% against Cx. quinquefasciatus. Vegetable oils namely mustard (B. compestris) and coconut (C. nucisera) showed repellent action, however the efficacy of these oils was not much pronounced against Cx. quinquefasciatus. Results of statistical analysis revealed significant difference between vegetable and essential oils (p mosquitoes. Essential oils were found marginally superior in repellancy than camphor and mylol (p < 0.01) against An. culicifacies and Cx. quinquefasciatus.

  8. Microencapsulated citronella oil for mosquito repellent finishing of cotton textiles.

    Science.gov (United States)

    Specos, M M Miró; García, J J; Tornesello, J; Marino, P; Vecchia, M Della; Tesoriero, M V Defain; Hermida, L G

    2010-10-01

    Microcapsules containing citronella essential oil were prepared by complex coacervation and applied to cotton textiles in order to study the repellent efficacy of the obtained fabrics. Citronella released from treated textiles was indirectly monitored by the extractable content of its main components. Repellent activity was assessed by exposure of a human hand and arm covered with the treated textiles to Aedes aegypti mosquitoes. Fabrics treated with microencapsulated citronella presented a higher and longer lasting protection from insects compared to fabrics sprayed with an ethanol solution of the essential oil, assuring a repellent effect higher than 90% for three weeks. Complex coacervation is a simple, low cost, scalable and reproducible method of obtaining encapsulated essential oils for textile application. Repellent textiles were achieved by padding cotton fabrics with microcapsules slurries using a conventional pad-dry method. This methodology requires no additional investment for textile finishing industries, which is a desirable factor in developing countries.

  9. Evaluation of the Repellent and Insecticidal Activities of the Leaf ...

    African Journals Online (AJOL)

    ADOWIE PERE

    high repellent and insecticidal activities demonstrated by the root powder ... generally low as a result of serious insect pest attacks ..... to have clear insecticidal properties (DeGeyter, 2012) ... nematicidal ingredients from neem leaves, siam.

  10. A repellent for protecting corn seed from blackbirds and crows

    Science.gov (United States)

    Stickley, A.R.; Guarineo, J.L.

    1972-01-01

    Methiocarb [4-(methylthio)-3,-5-xylyl N-methylcarbamate] was tested as a seed treatment for repelling blackbirds and crows (Corvus sp.) from sprouting corn in South Carolina. The test was conducted on eight fields within a 0.25-square-mile area. Marked repellency occurred; sprout damage averaged 44 percent in the control fields and 0.3 percent in the fields treated with methiocarb.

  11. Strange Quasi-Repeller in a Kicked Rotor

    Institute of Scientific and Technical Information of China (English)

    姜玉梅; 何大韧

    2003-01-01

    A new kind of crisis was observed in a system where a transition from conservative toquasi-dissipative can be observed. The crisis signifies a sudden and intrinsic change of a stochasticweb, which is formed by the end-results of the images of the discontinuous borderlines of the systemfunction. In the crisis, a strange quasi-repeller can be defined. When changing the controllingparameter, the variation of the fractile dimension of the quasi-repeller obeys a logarithmic rule.

  12. REPELLERS FOR MULTIFUNCTIONS OF SEMI-BORNOLOGICAL SPACES

    Institute of Scientific and Technical Information of China (English)

    M.R. Molaei; T. Waezizadeh

    2008-01-01

    In this article the notion of repeller for multifunctions from the viewpoints of semi-bornological spaces is considered. The concept of lower semi-continuous multifunc-tions is extended by the use of semi-bornological spaces. Semi-bornological vector spaces are studied. The notion of conjugacy for semi-bornological multifunctions is considered. The persistence of repeller under conjugate relation is proved.

  13. DEET Insect Repellent: Effects on Thermoregulatory Sweating and Physiological Strain

    Science.gov (United States)

    2011-01-01

    standard skin repellent, as it is effective against a wide variety of disease-transmitting insects, including mosquitoes, flies, fleas , ticks and chigger...evaporation, thus impeding evaporative heat loss. To our knowledge, only one study has experimentally examined the impact of an insect repellent on...body fat was then calculated using the Siri equation (1993). During heat acclimation and all experimental testing sessions, heart rate (HR) was

  14. Insect Repellents: Modulators of Mosquito Odorant Receptor Activity

    Science.gov (United States)

    2010-08-01

    products include the active ingredients N,N- diethyl -3-methylbenzamide (DEET), Insect Repellent 3535 (IR3535), and more recently Picaridin and 2...than the odorant. DEET and indole share an aromatic ring and a nitrogen-linked function. 2-U and octenol share a similar carbon backbone, and 2-U has a...effects of all four repellents were reversible upon fresh exposure to the odorant alone, suggesting that the interaction between the inhibitors and the ORs

  15. Toxicity of a plant based mosquito repellent/killer.

    Science.gov (United States)

    Singh, Bhoopendra; Singh, Prakash Raj; Mohanty, Manoj Kumar

    2012-12-01

    The mission to make humans less attractive to mosquitoes has fuelled decades of scientific research on mosquito behaviour and control. The search for the perfect topical insect repellent/killer continues. This analysis was conducted to review and explore the scientific information on toxicity produced by the ingredients/contents of a herbal product. In this process of systemic review the following methodology was applied. By doing a MEDLINE search with key words of selected plants, plant based insect repellents/killers pertinent articles published in journals and authentic books were reviewed. The World Wide Web and the Extension Toxicity Network database (IPCS-ITOX) were also searched for toxicology data and other pertinent information. Repellents do not all share a single mode of action and surprisingly little is known about how repellents act on their target insects. Moreover, different mosquito species may react differently to the same repellent. After analysis of available data and information on the ingredient, of the product in relation to medicinal uses, acute and chronic toxicity of the selected medicinal plants, it can be concluded that the ingredients included in the herbal product can be used as active agents against mosquitoes. If the product which contains the powder of the above said plants is applied with care and safety, it is suitable fo use as a mosquito repellent/killer.

  16. Graphene-coated meshes for electroactive flow control devices utilizing two antagonistic functions of repellency and permeability

    Science.gov (United States)

    Tabassian, Rassoul; Oh, Jung-Hwan; Kim, Sooyeun; Kim, Donggyu; Ryu, Seunghwa; Cho, Seung-Min; Koratkar, Nikhil; Oh, Il-Kwon

    2016-10-01

    The wettability of graphene on various substrates has been intensively investigated for practical applications including surgical and medical tools, textiles, water harvesting, self-cleaning, oil spill removal and microfluidic devices. However, most previous studies have been limited to investigating the intrinsic and passive wettability of graphene and graphene hybrid composites. Here, we report the electrowetting of graphene-coated metal meshes for use as electroactive flow control devices, utilizing two antagonistic functions, hydrophobic repellency versus liquid permeability. Graphene coating was able to prevent the thermal oxidation and corrosion problems that plague unprotected metal meshes, while also maintaining its hydrophobicity. The shapes of liquid droplets and the degree of water penetration through the graphene-coated meshes were controlled by electrical stimuli based on the functional control of hydrophobic repellency and liquid permeability. Furthermore, using the graphene-coated metal meshes, we developed two active flow devices demonstrating the dynamic locomotion of water droplets and electroactive flow switching.

  17. Do topical repellents divert mosquitoes within a community? Health equity implications of topical repellents as a mosquito bite prevention tool.

    Science.gov (United States)

    Maia, Marta Ferreira; Onyango, Sangoro Peter; Thele, Max; Simfukwe, Emmanuel Titus; Turner, Elizabeth Louise; Moore, Sarah Jane

    2013-01-01

    Repellents do not kill mosquitoes--they simply reduce human-vector contact. Thus it is possible that individuals who do not use repellents but dwell close to repellent users experience more bites than otherwise. The objective of this study was to measure if diversion occurs from households that use repellents to those that do not use repellents. The study was performed in three Tanzanian villages using 15%-DEET and placebo lotions. All households were given LLINs. Three coverage scenarios were investigated: complete coverage (all households were given 15%-DEET), incomplete coverage (80% of households were given 15%-DEET and 20% placebo) and no coverage (all households were given placebo). A crossover study design was used and coverage scenarios were rotated weekly over a period of ten weeks. The placebo lotion was randomly allocated to households in the incomplete coverage scenario. The level of compliance was reported to be close to 100%. Mosquito densities were measured through aspiration of resting mosquitoes. Data were analysed using negative binomial regression models. Repellent-users had consistently fewer mosquitoes in their dwellings. In villages where everybody had been given 15%-DEET, resting mosquito densities were fewer than half that of households in the no coverage scenario (Incidence Rate Ratio [IRR]=0.39 (95% confidence interval [CI]: 0.25-0.60); pmosquitoes (IRR=4.17; 95% CI: 3.08-5.65; pmosquitoes are diverted from households that use repellent to those that do not. Therefore, if repellents are to be considered for vector control, strategies to maximise coverage are required.

  18. Effect of restoring soil hydrological poperties on water conservation

    NARCIS (Netherlands)

    Moore, D.; Kostka, S.J.; Boerth, T.J.; Franklin, M.A.; Ritsema, C.J.; Dekker, L.W.; Oostindie, K.; Stoof, C.R.; Park, D.M.

    2008-01-01

    Water repellency in soil is more wide spread than previously thought ¿ and has a significant impact on irrigation efficiency and water conservation. Soil water repellency has been identified in many soil types under a wide array of climatic conditions world wide. Consequences include increased

  19. Effect of restoring soil hydrological poperties on water conservation

    NARCIS (Netherlands)

    Moore, D.; Kostka, S.J.; Boerth, T.J.; Franklin, M.A.; Ritsema, C.J.; Dekker, L.W.; Oostindie, K.; Stoof, C.R.; Park, D.M.

    2008-01-01

    Water repellency in soil is more wide spread than previously thought ¿ and has a significant impact on irrigation efficiency and water conservation. Soil water repellency has been identified in many soil types under a wide array of climatic conditions world wide. Consequences include increased runof

  20. Repellent activities of dichloromethane extract of Allium sativum (garlic (Liliaceae against Hyalomma rufipes (Acari

    Directory of Open Access Journals (Sweden)

    Felix Nchu

    2016-02-01

    Full Text Available Dichloromethane (DCM extract of garlic (Allium sativum Linn. bulbs was assessed for its repellent effect against the hard tick, Hyalomma rufipes (Acari: Ixodidae using two tick behavioural bioassays; Type A and Type B repellency bioassays, under laboratory conditions. These bioassays exploit the questing behaviour of H. rufipes, a tick that in nature displays ambush strategy, seeking its host by climbing up on vegetation and attaching to a passing host. One hundred microlitres (100 µL of the test solution containing DCM extract of garlic bulbs and DCM at concentrations of 0.35%, 0.7% or 1.4% w/v were evaluated. DCM only was used for control. Tick repellency increased significantly (R2 = 0.98 with increasing concentration (40.03% – 86.96% yielding an EC50 of 0.45% w/v in Type B repellency bioassay. At concentration of 1.4% w/v, the DCM extract of garlic bulbs produced high repellency index of 87% (male ticks and 87.5% (female ticks in the Type A repellency bioassay. Only 4% avoidance of male ticks or female ticks was recorded in the Type B repellency bioassay. In the corresponding controls, the mean numbers of non-repelled male or female ticks were 80% and 41 males or 38 females of 50 ticks in the Type A and Type B repellency bioassays, respectively. The variations in the results could be attributed to the difference in tick repellent behaviours that were assessed by the two repellency bioassays; the Type A repellency bioassay assessed repellent effect of garlic extracts without discriminating between deterrence and avoidance whereas the Type B repellency bioassay only assessed avoidance response. Generally, DCM extract of garlic was repellent against H. rufipes, albeit weak tick repellency was obtained in the Type B repellency bioassay. Furthermore, this study established that the tick repellent activity of garlic extracts is predominantly by deterrence.

  1. Repellent activities of dichloromethane extract of Allium sativum (garlic) (Liliaceae) against Hyalomma rufipes (Acari).

    Science.gov (United States)

    Nchu, Felix; Magano, Solomon R; Eloff, Jacobus N

    2016-12-02

    Dichloromethane (DCM) extract of garlic (Allium sativum Linn.) bulbs was assessed for its repellent effect against the hard tick, Hyalomma rufipes (Acari: Ixodidae) using two tick behavioural bioassays; Type A and Type B repellency bioassays, under laboratory conditions. These bioassays exploit the questing behaviour of H. rufipes, a tick that in nature displays ambush strategy, seeking its host by climbing up on vegetation and attaching to a passing host. One hundred microlitres (100 µL) of the test solution containing DCM extract of garlic bulbs and DCM at concentrations of 0.35%, 0.7% or 1.4% w/v were evaluated. DCM only was used for control. Tick repellency increased significantly (R2 = 0.98) with increasing concentration (40.03% - 86.96%) yielding an EC50 of 0.45% w/v in Type B repellency bioassay. At concentration of 1.4% w/v, the DCM extract of garlic bulbs produced high repellency index of 87% (male ticks) and 87.5% (female ticks) in the Type A repellency bioassay. Only 4% avoidance of male ticks or female ticks was recorded in the Type B repellency bioassay. In the corresponding controls, the mean numbers of non-repelled male or female ticks were 80% and 41 males or 38 females of 50 ticks in the Type A and Type B repellency bioassays, respectively. The variations in the results could be attributed to the difference in tick repellent behaviours that were assessed by the two repellency bioassays; the Type A repellency bioassay assessed repellent effect of garlic extracts without discriminating between deterrence and avoidance whereas the Type B repellency bioassay only assessed avoidance response. Generally, DCM extract of garlic was repellent against H. rufipes, albeit weak tick repellency was obtained in the Type B repellency bioassay. Furthermore, this study established that the tick repellent activity of garlic extracts is predominantly by deterrence.

  2. Laboratory evaluation of Indian medicinal plants as repellents against malaria, dengue, and filariasis vector mosquitoes.

    Science.gov (United States)

    Govindarajan, Marimuthu; Sivakumar, Rajamohan

    2015-02-01

    Mosquito-borne diseases have an economic impact, including loss in commercial and labor outputs, particularly in countries with tropical and subtropical climates; however, no part of the world is free from vector-borne diseases. Mosquitoes are the carriers of severe and well-known illnesses such as malaria, arboviral encephalitis, dengue fever, chikungunya fever, West Nile virus, and yellow fever. These diseases produce significant morbidity and mortality in humans and livestock around the world. In view of the recently increased interest in developing plant origin insecticides as an alternative to chemical insecticides, in the present study, the repellent activity of crude hexane, ethyl acetate, benzene, chloroform, and methanol extracts of leaf of Erythrina indica and root of Asparagus racemosus were assayed for their repellency against three important vector mosquitoes, viz., Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus. The crude extract was applied on a membrane used for membrane feeding of unfed mosquitoes in a 1-ft cage. About 50 unfed 3-4-day-old laboratory-reared pathogen-free strains of A. stephensi, A. aegypti, and C. quinquefasciatus were introduced in a 1-ft cage fitted with a membrane with blood for feeding with temperature maintained at 37 °C through circulating water bath maintained at 40-45 °C. Three concentrations (1.0, 2.0, and 5.0 mg/cm(2)) of the crude extracts were evaluated. Repellents in E. indica afforded longer protection time against A. stephensi, A. aegypti, and C. quinquefasciatus than those in A. racemosus at 5.0 mg/cm(2) concentration, and the mean complete protection time ranged from 120 to 210 min with the different extracts tested. In this observation, these two plant crude extracts gave protection against mosquito bites; also, the repellent activity is dependent on the strength of the plant extracts. These results suggest that the leaf extract of E. indica and root extract of A. racemosus have the potential to

  3. Do topical repellents divert mosquitoes within a community? Health equity implications of topical repellents as a mosquito bite prevention tool.

    Directory of Open Access Journals (Sweden)

    Marta Ferreira Maia

    Full Text Available OBJECTIVES: Repellents do not kill mosquitoes--they simply reduce human-vector contact. Thus it is possible that individuals who do not use repellents but dwell close to repellent users experience more bites than otherwise. The objective of this study was to measure if diversion occurs from households that use repellents to those that do not use repellents. METHODS: The study was performed in three Tanzanian villages using 15%-DEET and placebo lotions. All households were given LLINs. Three coverage scenarios were investigated: complete coverage (all households were given 15%-DEET, incomplete coverage (80% of households were given 15%-DEET and 20% placebo and no coverage (all households were given placebo. A crossover study design was used and coverage scenarios were rotated weekly over a period of ten weeks. The placebo lotion was randomly allocated to households in the incomplete coverage scenario. The level of compliance was reported to be close to 100%. Mosquito densities were measured through aspiration of resting mosquitoes. Data were analysed using negative binomial regression models. FINDINGS: Repellent-users had consistently fewer mosquitoes in their dwellings. In villages where everybody had been given 15%-DEET, resting mosquito densities were fewer than half that of households in the no coverage scenario (Incidence Rate Ratio [IRR]=0.39 (95% confidence interval [CI]: 0.25-0.60; p<0.001. Placebo-users living in a village where 80% of the households used 15%-DEET were likely to have over four-times more mosquitoes (IRR=4.17; 95% CI: 3.08-5.65; p<0.001 resting in their dwellings in comparison to households in a village where nobody uses repellent. CONCLUSIONS: There is evidence that high coverage of repellent use could significantly reduce man-vector contact but with incomplete coverage evidence suggests that mosquitoes are diverted from households that use repellent to those that do not. Therefore, if repellents are to be considered for

  4. New Candidates for Plant-Based Repellents Against Aedes aegypti.

    Science.gov (United States)

    Misni, Norashiqin; Nor, Zurainee Mohamed; Ahmad, Rohani

    2016-06-01

    Based on an ethnobotanical study on use for plant species against mosquito bites in the Kota Tinggi District, Johor State, Malaysia, 3 plants selected for study, Citrus aurantifolia (leaves), Citrus grandis (fruit peel), and Alpinia galanga (rhizome), were extracted using hydrodistillation to produce essential oils. These essential oils were then formulated as a lotion using a microencapsulation process and then tested for their repellent effect against Aedes aegypti. N,N-diethyl-m-toluamide (deet) was also prepared in the same formulation and tested for repellency as controls. Four commercial plant-based repellent (KAPS(®), MozAway(®), BioZ Natural(®), and Mosiquard(®)) also were incorporated in the bioassay for comparison purposes. Bioassays revealed that at 20% concentration all repellent formulations demonstrated complete protection for 2 h and >90% for 4 h post-application. The A. galanga-based formulation provided the greatest level of protection (98.91%), which extended for 4 h post-application and was not significantly different from deet at similar concentration. When compared with commercial plant-based repellents (KAPS(®), MozAway(®), and BioZ Natural(®)), the 3 lotion formulations showed significantly better protection against Ae. aegypti bites, providing >90% protection for 4 h. In conclusion, our 3 plant-based lotion formulations provided acceptable levels of protection against host-seeking Ae. aegypti and should be developed.

  5. Mosquito repellent activity of volatile oils from selected aromatic plants.

    Science.gov (United States)

    Lalthazuali; Mathew, Nisha

    2017-02-01

    Essential oils from fresh leaves of four aromatic plants viz., Ocimum sanctum, Mentha piperita, Eucalyptus globulus and Plectranthus amboinicus were extracted by hydrodistillation. The test solutions were prepared as 20% essential oil in ethanol and positive control as 20% DEET in ethanol. Essential oil blend was prepared as 5% concentration. Nulliparous, 3-5-day-old female adult Aedes aegypti mosquitoes were used for repellency screening as per ICMR protocol. The study showed that the repellency of 20% essential oil of O. sanctum, M. piperita and P. amboinicus were comparable with that of the standard DEET (20%) as no mosquito landing on the test was observed up to 6 h. The E. globulus oil exhibited mosquito repellency only upto 1½ h. Considerable mosquito landing and feeding was displayed in negative control. In the case of the oil blend, no landing of mosquitoes was seen up to 6 h as that of positive control. The results showed that the essential oil blend from O. sanctum, M. piperita, E. globulus and P. amboinicus could repel Ae. aegypti mosquitoes or prevent from feeding as in the case of DEET even at a lower concentration of 5%. This study demonstrates the potential of essential oils from O. sanctum, M. piperita, E. globulus and P. amboinicus and their blend as mosquito repellents against Ae. aegypti, the vector of dengue, chikungunya and yellow fever.

  6. Repellent effect of Lagenaria siceraria extracts against Culex pipiens.

    Science.gov (United States)

    Hassan, Mostafa I; Fouda, Mohamad A; Hammad, Kotb M; Tanani, Mohamad A; Shehata, Ahmed Z

    2014-04-01

    Ethanolic, acetone and petroleum ether extracts from leaves and stems of Lagenaria siceraria (Cucurbitaceae) were screened for their repellency effect against Culex pipiens L. mosquito. The repellent action of the present plant extracts were varied depending on the plant parts and the dose of extract. The petroleum ether extract of leaves showed the same repellency percent (100%) of commercial formulation, N. N.diethyl toulamide (DEET) at the higher dose (3.33 mg/cm2), while petroleum ether extract from stems exhibiting the repellent action (89.6%) at the same dose, respectively. Ethanolic extracts of leaves and stems exhibited the lowest repellent activity as it recorded (81.3% and 69.1%) at (6.67 mg/cm2), respectively. Results of this study may contribute to design an alternative way to control mosquitoes currently based on applications of synthetic insecticides. These extracts could be developed commercially as an effective personal protection measure against mosquito bites and thus to control diseases caused by mosquito-borne pathogens.

  7. POSSIBILITIES TO USE NATURAL EXTRACTS FROM MEDICINAL AND AROMATIC PLANTS (MAP LIKE BOTANICAL REPELLENT OR INSECTICIDE COMPOUNDS AGAINST PEST INSECTS IN ECOLOGICAL CROPS (II

    Directory of Open Access Journals (Sweden)

    Irina IONESCU-MĂLĂNCUŞ

    2013-12-01

    Full Text Available Botanical insecticides have long been touted as attractive alternatives to synthetic chemical insecticides for pest management because botanicals reputedly pose little threat to the environment or to human health. The body of scientific literature documenting bioactivity of plant derivatives to arthropods pests continues to expand i.e. repellents based on essential oils extracted from Chenopodium ambrosioides, Eucalyptus saligna, Rosmarinus officinalis to mosquitoes, or cinnamon oil, sandalwood oil and turmeric oil are previously reported as insect repellents evaluatede in the laboratory conditions. With the constantly increasing problems of insecticide resistance and increasing public concerns regarding pesticide safety, new, safer active ingredients are becoming necessary to replace existing compounds on the market. The present study carried out in the period 2010-2012 comprises a review of two insect repellents, followed by some new research conducted in our laboratory on plant-derived insect repellents. The two alkaloids tested against the Colorado potato beetle, Leptinotarsa decemlineata Say in laboratory conditions was obtained by water and alchohol extraction from two vegetal species, Cichorium intybus L. (Asterales:Asteraceae and Delphinium consolida L. (Ranales:Ranunculaceae. The tests carried out in laboratory and field experimentally plots under cages permit to evaluate several other compounds for repellent activity of lacctucin alkaloids.

  8. Insect repellents and associated personal protection for a reduction in human disease

    Science.gov (United States)

    Personal protection measures against biting arthropods include topical insect repellents, area repellents, insecticide-treated bednets and treated clothing. The literature on the effectiveness of personal protection products against arthropods is mainly limited to studies of prevention of bites, rat...

  9. Plant-based insect repellents: a review of their efficacy, development and testing

    Directory of Open Access Journals (Sweden)

    Maia Marta

    2011-03-01

    Full Text Available Abstract Plant-based repellents have been used for generations in traditional practice as a personal protection measure against host-seeking mosquitoes. Knowledge on traditional repellent plants obtained through ethnobotanical studies is a valuable resource for the development of new natural products. Recently, commercial repellent products containing plant-based ingredients have gained increasing popularity among consumers, as these are commonly perceived as “safe” in comparison to long-established synthetic repellents although this is sometimes a misconception. To date insufficient studies have followed standard WHO Pesticide Evaluation Scheme guidelines for repellent testing. There is a need for further standardized studies in order to better evaluate repellent compounds and develop new products that offer high repellency as well as good consumer safety. This paper presents a summary of recent information on testing, efficacy and safety of plant-based repellents as well as promising new developments in the field.

  10. Efficacy of the repellent N,N-diethyl-3-methyl-benzamide (DEET) against tabanid flies on horses evaluated in a field test in Switzerland.

    Science.gov (United States)

    Herholz, C; Kopp, C; Wenger, M; Mathis, A; Wägeli, S; Roth, N

    2016-05-15

    Female tabanid flies (Diptera: Tabanidae) can be a serious nuisance for horses because of their painful bites during blood feeding. They also play a primary role in mechanical transmission of a lentivirus causing Equine Infectious Anemia (EIA), a virus that has spread within Europe in recent years. According to the European law for products intended for use as a repellent on horses (recreational and sport horses), a field test is mandatory to demonstrate sufficient repellency of such a substance against the specific target fly species, but currently no agreed protocols are available for testing of potential repellents. The aim of the present study was to establish a protocol for a field test to investigate the efficacy of N,N-diethyl-3-methyl-benzamide (DEET, Brum®, Huebeli-Stud Horse Care AG) in a 15-17% oil-water emulsion against tabanid flies on horses up to four hours. Between July and August 2015, four horses on three farms each were tested on two consecutive days in a cross-over design. The four horses on Farm A were used in the pre-test as well as in the main test. Two and a half hours after repellent application the horses were lunged until sweating. Tabanid fly infestations were both photographed and directly counted during five minutes 3 and 4h after repellent application on the right side of the horses in the area from the head to the flank, belly and first third of the foreleg. Without repellent application, up to 29 tabanid flies were counted on a horse, whereas the maximum for the repellent treated horses was four. In 50% of the horses treated with DEET there were no Tabanids observed (efficacy 100%), and in all horses the tabanid fly counts were lower than in the control horses with one exemption at 4h. The efficacy of the DEET repellent was at least 80% and 71% respectively, three or four hours after application (with a confidence level of 89%). A fly trap (Horse Pal) revealed the presence of the tabanid species Tabanus brominus and Haematopota

  11. Development of novel repellents using structure-activity modeling of compounds in the USDA archival database

    Science.gov (United States)

    The United States Department of Agriculture (USDA) has developed repellents and insecticides for the U.S. military since 1942. Repellency and toxicity data for over 30,000 compounds are contained within the USDA archive. Repellency data from subsets of similarly structured compounds were used to dev...

  12. Antennal olfactory sensilla responses to insect chemical repellents in the common bed bug, Cimex lectularius.

    Science.gov (United States)

    Liu, Feng; Haynes, Kenneth F; Appel, Arthur G; Liu, Nannan

    2014-06-01

    Populations of the common bed bug Cimex lectularius (Hemiptera; Cimicidae), a temporary ectoparasite on both humans and animals, have surged in many developed countries. Similar to other haematophagous arthropods, C. lectularius relies on its olfactory system to detect semiochemicals in the environment, including both attractants and repellents. To elucidate the olfactory responses of the common bed bug to commonly used insect chemical repellents, particularly haematophagous repellents, we investigated the neuronal responses of individual olfactory sensilla in C. lectularius' antennae to 52 insect chemical repellents, both synthetic and botanic. Different types of sensilla displayed highly distinctive response profiles. While C sensilla did not respond to any of the insect chemical repellents, Dγ sensilla proved to be the most sensitive in response to terpene-derived insect chemical repellents. Different chemical repellents elicited neuronal responses with differing temporal characteristics, and the responses of the olfactory sensilla to the insect chemical repellents were dose-dependent, with an olfactory response to the terpene-derived chemical repellent, but not to the non-terpene-derived chemical repellents. Overall, this study furnishes a comprehensive map of the olfactory response of bed bugs to commonly used insect chemical repellents, providing useful information for those developing new agents (attractants or repellents) for bed bug control.

  13. Secondary Metabolite Profile, Antioxidant Capacity, and Mosquito Repellent Activity of Bixa orellana from Brazilian Amazon Region

    Directory of Open Access Journals (Sweden)

    Annamaria Giorgi

    2013-01-01

    Full Text Available The Brazilian flora was widely used as source of food and natural remedies to treat various diseases. Bixa orellana L. (Bixaceae, also known as annatto, urucù, or achiote, is a symbol for the Amazonian tribes that traditionally use its seeds as coloured ink to paint their bodies for religious ceremonies. The aim of this study was to investigate the volatile organic compounds (VOCs profile of B. orellana fresh fruits (in vivo sampled, dried seeds, wood, bark, and leaves analyzed with Headspace solid-phase microextraction coupled with gas chromatography and mass spectrometry. A screening on phenolic content (the Folin-Ciocalteu assay and antiradical activity (DPPH assay of seeds was also conducted. In addition, the repellent properties of seed extracts against Aedes aegypti L. were investigated. Volatile compounds detected in B. orellana samples consisted mainly of sesquiterpenes, monoterpenes, and arenes: α-humulene is the major volatile compound present in seed extracts followed by D-germacrene, γ-elemene, and caryophyllene. B. orellana proved to be a good source of antioxidants. Preliminary data on repellency against A. aegypti of three different dried seed extracts (hexane, ethanol, and ethanol/water indicated a significant skin protection activity. A protection of 90% and 73% for hexane and ethanol/water extracts was recorded.

  14. Percutaneous penetration and pharmacodynamics: Wash-in and wash-off of sunscreen and insect repellent.

    Science.gov (United States)

    Rodriguez, Jocelyn; Maibach, Howard I

    2016-01-01

    Increased awareness of skin cancer and mosquito-transmitted diseases has increased use of insect repellents and sunscreens. The challenge in setting recommendations for use and reapplication, especially when used concomitantly, lies in finding the balance between applying a durable product effective in withstanding natural and physical factors such as water, sweat, temperature and abrasion, while limiting percutaneous absorption and decreasing risk of potential dermal and systemic toxicity. Inorganic sunscreens show no or little percutaneous absorption or toxic effects in comparison to organic sunscreens, which show varying levels of dermal penetration and cutaneous adverse effects. An alternative to N,N-diethyl-m-toluamide (DEET), the traditional gold standard compound in insect repellents, picaridin appears as efficacious, has lower risk of toxicity, and when used simultaneously with sunscreen may decrease percutaneous absorption of both compounds. Conversely, combined use of DEET and sunscreen results in significantly higher absorption of both compounds. It is important to increase consumer awareness of "washing in" of various compounds leading to increased risk of toxicity, as well as differences in reapplication need due to "washing off" caused by water, sweat and abrasion. Although much remains to be studied, to maximize efficacy and decrease toxicity, contemporary research tools, including dermatopharmokinetics, should aid these prospective advances.

  15. Protein-Repellence PES Membranes Using Bio-grafting of Ortho-aminophenol

    Directory of Open Access Journals (Sweden)

    Norhan Nady

    2016-08-01

    Full Text Available Surface modification becomes an effective tool for improvement of both flux and selectivity of membrane by reducing the adsorption of the components of the fluid used onto its surface. A successful green modification of poly(ethersulfone (PES membranes using ortho-aminophenol (2-AP modifier and laccase enzyme biocatalyst under very flexible conditions is presented in this paper. The modified PES membranes were evaluated using many techniques including total color change, pure water flux, and protein repellence that were related to the gravimetric grafting yield. In addition, static water contact angle on laminated PES layers were determined. Blank and modified commercial membranes (surface and cross-section and laminated PES layers (surface were imaged by scanning electron microscope (SEM and scanning probe microscope (SPM to illustrate the formed modifying poly(2-aminophenol layer(s. This green modification resulted in an improvement of both membrane flux and protein repellence, up to 15.4% and 81.27%, respectively, relative to the blank membrane.

  16. Repelling periodic points of given periods of rational functions

    Institute of Scientific and Technical Information of China (English)

    CHANG Jianming; FANG Mingliang

    2006-01-01

    Let R(z) be a rational function of degree d ≥ 2. Then R(z) has at least one repelling periodic point of given period k ≥ 2, unless k = 4 and d=2, or k= 3 and d ≤ 3, or k=2 and d≤8. Examples show that all exceptional cases occur.

  17. Olfactory responses to attractants and repellents in tsetse

    NARCIS (Netherlands)

    Voskamp, KE; Everaarts, E; Den Otter, CJ

    1999-01-01

    The aims of this study were to investigate how antennal olfactory cells of tsetse (Diptera: Glossinidae) code odour quality and how they are able to discriminate between attractive and repellent odours. For Glossina pallidipes Austen, a survey is presented of the cells' responses to attractive (1-oc

  18. An autopsy case of fatal repellent air freshener poisoning.

    Science.gov (United States)

    Hitosugi, Masahito; Tsukada, Chie; Yamauchi, Shinobu; Matsushima, Kazumi; Furukawa, Satoshi; Morita, Satomu; Nagai, Toshiaki

    2015-09-01

    We describe a first fatal case of repellent air freshener ingestion. A 79-year-old Japanese man with Alzheimer-type senile dementia orally ingested repellent air freshener containing three surfactants: polyoxyethylene 9-lauryl ether, polyoxyethylene (40) hydrogenated castor oil, and lauric acid amidopropyl amine oxide (weight ratio of 1.3%). About 1h after the collapse, he was in cardiopulmonary arrest and subsequently died 10h after his arrival. The forensic autopsy performed 5.5h after death revealed the 380ml of stomach contents with a strong mint perfume identical to that of the repellent air freshener and the findings of acute death. Toxicologically, 9.1μg/ml and 558.2μg/ml of polyoxyethylene 9-lauryl ether were detected from the serum and stomach contents taken at autopsy. Generally, ingestion of anionic or non-ionic surfactants have been considered as safe. However, because the patient suffered from cardiac insufficiency with a low dose of repellent air freshener ingestion, medical staff members must evaluate the elderly patient for cardiac and circulatory problems regardless of the ingested dose. Not only medical and nursing staff members, but also families who are obliged to care for elderly persons must be vigilant to prevent accidental ingestion of toxic substances generally used in the household.

  19. Insect Repellents: Modulators of mosquito odorant receptor activity

    Science.gov (United States)

    Mosquitoes vector numerous pathogens that cause diseases including malaria, yellow fever, dengue fever and chikungunya. DEET, IR3535, Picaridin and 2-undecanone are insect repellents that are used to prevent interactions between humans and a broad array of disease vectors including mosquitoes. While...

  20. The role of repellents and hydrophobins in Ustilago maydis

    NARCIS (Netherlands)

    Teertstra, W.R.

    2009-01-01

    Ustilago maydis is an important model organism to study fungal pathogenicity. U. maydis can grow yeast-like and filamentous. In the latter form this fungus infects maize. In my Thesis the expression and function of hydrophobins and repellents of U. maydis were studied. Hydrophobins are produced by f

  1. The role of repellents and hydrophobins in Ustilago maydis

    NARCIS (Netherlands)

    Teertstra, W.R.

    2009-01-01

    Ustilago maydis is an important model organism to study fungal pathogenicity. U. maydis can grow yeast-like and filamentous. In the latter form this fungus infects maize. In my Thesis the expression and function of hydrophobins and repellents of U. maydis were studied. Hydrophobins are produced by f

  2. Repellency Effects of Essential Oils of Myrtle (Myrtus Communis, Marigold (Calendula Officinalis Compared with DEET Against Anopheles Stephensi on Human Volunteers

    Directory of Open Access Journals (Sweden)

    M Khoobdel

    2011-12-01

    Full Text Available Background: Malaria and leishmaniasis are two most significant parasitic diseases which are endemic in Iran. Over the past decades, interest in botanical repellents has increased as a result of safety to human. The comparative effi­cacy of essential oils of two native plants, myrtle (Myrtus communis and marigold (Calendula officinalis collected from natural habitats at southern Iran was compared with DEET as synthetic repellent against Anopheles stephensi on human subjects under laboratory condition. Methods: Essential oils from two species of native plants were obtained by Clevenger-type water distillation. The protec­tion time of DEET, marigold and myrtle was assessed on human subject using screened cage method against An. stephensi. The effective dose of 50% essential oils of two latter species and DEET were determined by modified ASTM method. ED50 and ED90 values and related statistical parameters were calculated by probit analysis. Results: The protection time of 50% essential oils of marigold and myrtle were respectively 2.15 and 4.36 hours com­pared to 6.23 hours for DEET 25%. The median effective dose (ED50 of 50% essential oils was 0.1105 and 0.6034 mg/cm2 respectively in myrtle and marigold. The figure for DEET was 0.0023 mg/cm2.Conclusion: This study exhibited that the repellency of both botanical repellents was generally lower than DEET as a synthetic repellent. However the 50% essential oil of myrtle showed a moderate repellency effects compared to mari­gold against An. stephensi.

  3. Repellency Effects of Essential Oils of Myrtle (Myrtus communis, Marigold (Calendula officinalis Compared with DEET against Anopheles stephensi on Human Volunteers

    Directory of Open Access Journals (Sweden)

    M Tavassoli

    2011-12-01

    Full Text Available Background: Malaria and leishmaniasis are two most significant parasitic diseases which are endemic in Iran. Over the past decades, interest in botanical repellents has increased as a result of safety to human. The comparative effi­cacy of essential oils of two native plants, myrtle (Myrtus communis and marigold (Calendula officinalis collected from natural habitats at southern Iran was compared with DEET as synthetic repellent against Anopheles stephensi on human subjects under laboratory condition. Methods:  Essential oils from two species of native plants were obtained by Clevenger-type water distillation. The protec­tion time of DEET, marigold and myrtle was assessed on human subject using screened cage method against An. stephensi. The effective dose of 50% essential oils of two latter species and DEET were determined by modified ASTM method. ED50 and ED90 values and related statistical parameters were calculated by probit analysis.   Results: The protection time of 50% essential oils of marigold and myrtle were respectively 2.15 and 4.36 hours com­pared to 6.23 hours for DEET 25%. The median effective dose (ED50 of 50% essential oils was 0.1105 and 0.6034 mg/cm2 respectively in myrtle and marigold. The figure for DEET was 0.0023 mg/cm2. Conclusion: This study exhibited that the repellency of both botanical repellents was generally lower than DEET as a synthetic repellent. However the 50% essential oil of myrtle showed a moderate repellency effects compared to mari­gold against An. stephensi.

  4. A Green Route for Substrate-Independent Oil-Repellent Coatings

    Science.gov (United States)

    Xu, Li-Ping; Han, Da; Wu, Xiuwen; Zhang, Qingqing; Zhang, Xueji; Wang, Shutao

    2016-11-01

    Oil repellent surface have lots of practical applications in many fields. Current oil repellent coating may suffer from limited liquid repellency to oils or environmental risks. In this work, we report an eco-friendly ‘green’ processes for preparing oil-repellent surface using a renewable and environmentally benign bioresource alginate. The oil-repellent coating was prepared by a two-step surface coating technique and showed stable oil repellency to many kinds of oils. The fabrication process was very simple with no need for special equipment, and this approach can be successfully employed to various substrates with different compositions, sizes and shapes, or even substrate-independent oil-repellent materials. The as-prepared coating of calcium alginate may have a good future in packaging oil-containing products and foods.

  5. Laboratory evaluation of four commercial repellents against larval Leptotrombidium deliense (Acari: Trombiculidae).

    Science.gov (United States)

    Hanifah, Azima Laili; Ismail, Siti Hazar Awang; Ming, Ho Tze

    2010-09-01

    Four commercial repellents were evaluated in the laboratory against Leptotrombidium deliense chiggers. Both in vitro and in vivo methods were used to determine repellency of the compounds. The repellents were Kellis (containing citronella oil, jojoba oil and tea tree oil), Kaps (containing citronella oil), BioZ (containing citronella oil, geranium oil and lemon grass oil) and Off (containing DEET). The combination of three active ingredients: citronella oil, geranium oil, lemon grass oil gave the highest repellency (87%) followed by DEET (84%). In vitro repellencies ranged from 73% to 87%. There was no significant difference between the four products. All the repellents had 100% in vivo repellency compared to 41-57% for the controls.

  6. Fingerlike wetting patterns in two water-repellent loam soils

    NARCIS (Netherlands)

    Dekker, L.W.; Ritsema, C.J.

    1995-01-01

    In soils with fingered flow, surface-applied solutes can reach the groundwater more rapidly than in the case of homogeneous wetting. This study was undertaken to demonstrate the occurrence of finger-like wetting patterns in a silt loam soil and a silty clay loam soil, and to investigate the

  7. Water-repellent cellulose fiber networks with multifunctional properties.

    Science.gov (United States)

    Bayer, Ilker S; Fragouli, Despina; Attanasio, Agnese; Sorce, Barbara; Bertoni, Giovanni; Brescia, Rosaria; Di Corato, Riccardo; Pellegrino, Teresa; Kalyva, Maria; Sabella, Stefania; Pompa, Pier Paolo; Cingolani, Roberto; Athanassiou, Athanassia

    2011-10-01

    We demonstrate a simple but highly efficient technique to introduce multifunctional properties to cellulose fiber networks by wetting them with ethyl-cyanoacrylate monomer solutions containing various suspended organic submicrometer particles or inorganic nanoparticles. Solutions can be applied on cellulosic surfaces by simple solution casting techniques or by dip coating, both being suitable for large area applications. Immediately after solvent evaporation, ethyl-cyanoacrylate starts cross-linking around cellulose fibers under ambient conditions because of naturally occurring surface hydroxyl groups and adsorbed moisture, encapsulating them with a hydrophobic polymer shell. Furthermore, by dispersing various functional particles in the monomer solutions, hydrophobic ethyl-cyanoacrylate nanocomposites with desired functionalities can be formed around the cellulose fibers. To exhibit the versatility of the method, cellulose sheets were functionalized with different ethyl-cyanoacrylate nanocomposite shells comprising submicrometer wax or polytetrafluoroethylene particles for superhydophobicity, MnFe(2)O(4) nanoparticles for magnetic activity, CdSe/ZnS quantum dots for light emission, and silver nanoparticles for antimicrobial activity. Morphological and functional properties of each system have been studied by scanning and transmission electron microscopy, detailed contact angle measurements, light emission spectra and E. coli bacterial growth measurements. A plethora of potential applications can be envisioned for this technique, such as food and industrial packaging, document protection, catalytic cellulosic membranes, textronic (electrofunctional textiles), electromagnetic devices, authentication of valuable documents, and antimicrobial wound healing products to name a few.

  8. Toxic alveolitis after inhalation of a water repellent.

    Science.gov (United States)

    Epping, Guido; Van Baarlen, Joop; Van Der Valk, Paul D L P M

    2011-12-01

    Inhalation of fluorocarbon polymers can cause pulmonary toxicity. Although multiple cases of lung injury have been reported, cellular characterization of the associated alveolitis occurring acutely after inhalation is limited. We report the case of a previously healthy woman who presented at our Emergency Department with an acute pneumonitis following inhalation of a fluorocarbon polymer-based rain-proofing spray. Bronchoalveolar lavage (BAL) performed shortly after the presentation showed an elevated total cell count, with a high proportion of neutrophils (58%) and eosinophils (9%). In addition, a lipid stain (Oil-Red-O-stain) showed a high level of lipid laden macrophages, a marker that could reflect a direct toxic effect of the spray on alveolar cells. The patient made a full recovery after four days of in-hospital observation with supportive care.

  9. Assessing the accuracy of contact angle measurements for sessile drops on liquid-repellent surfaces.

    Science.gov (United States)

    Srinivasan, Siddarth; McKinley, Gareth H; Cohen, Robert E

    2011-11-15

    Gravity-induced sagging can amplify variations in goniometric measurements of the contact angles of sessile drops on super-liquid-repellent surfaces. The very large value of the effective contact angle leads to increased optical noise in the drop profile near the solid-liquid free surface and the progressive failure of simple geometric approximations. We demonstrate a systematic approach to determining the effective contact angle of drops on super-repellent surfaces. We use a perturbation solution of the Bashforth-Adams equation to estimate the contact angles of sessile drops of water, ethylene glycol, and diiodomethane on an omniphobic surface using direct measurements of the maximum drop width and height. The results and analysis can be represented in terms of a dimensionless Bond number that depends on the maximum drop width and the capillary length of the liquid to quantify the extent of gravity-induced sagging. Finally, we illustrate the inherent sensitivity of goniometric contact angle measurement techniques to drop dimensions as the apparent contact angle approaches 180°.

  10. Repellent Activity of Bitter Almond Oil Against Aedes albopictus%苦杏仁精油对白纹伊蚊的驱避活性研究

    Institute of Scientific and Technical Information of China (English)

    马玉花; 赵忠; 江志利; 魏丽萍; 郭婵娟; 张兴

    2012-01-01

    采用个体涂肤有效保护时间试验研究了苦杏仁精油对白纹伊蚊的驱避活性.结果表明,含HCN和去除HCN的苦杏仁精油对白纹伊蚊都具有很强的驱避活性,涂药8h后,2种苦杏仁精油对白纹伊蚊的驱避率均在96.76%以上,作为对照的隆力奇花露水的驱避率为58.28%.另外,2种精油对人体的有效保护时间分别为6h和7h,高于隆力奇花露水4h.可见苦杏仁精油对白纹伊蚊具有很强的驱避效果,且其有效保护时间高于隆力奇花露水,因而有望开发成为新型的蚊虫驱避剂.%The repellent activity of bitter almond oil with and without HCN and toilet water (with the main component of DEET) against Aedes albopictus were studied with human body. The results showed that both of bitter almond oils had strong repellent activity against A. Albopictus, after 8 h the repellent rate of bitter almond oil with and without HCN was 96. 76% while the repellent rate of toilet water was 58. 28%. The available protective time of two types of bitter almond oil was 6 h and 7 h, respectively, higher than that of toilet water, indicating the potential of bitter almond oil to be developed as a new mosquito repellent agent.

  11. 聚氨酯-含氟丙烯酸酯防水防油性复合乳液的制备及性能%Synthesis and properties of polyurethane-fluorinated acrylate hybrid emulsion as water and oil- repellency agent

    Institute of Scientific and Technical Information of China (English)

    辛华; 李小瑞; 沈一丁

    2011-01-01

    以自乳化自交联的阳离子水性聚氨酯乳液(PU)为种子乳液进行含氟丙烯酸酯(FA)、苯乙烯(St)和丙烯酸丁酯 (BA)等乙烯基单体的自由基共聚合,制得阳离子聚氛醋-含氟丙烯酸酯(FPUA)复合乳液.通过红外光谱分析、接触角测试、表面自由能计算、粒径及粒径分布测试及透射电镜测试对聚合物乳液及其膜结构与性能进行了表征.结果表明w(FA)达到20%左右,FPUA才兼具良好防水防油性;水和二碘甲烷在FPUA (w (FA) =20%)乳胶膜上所成接触角分别为110和860;计算得30'C时FPUA(w(FA)=20%)乳胶膜表面自由能为14.64mJ/M2,比改性前PU膜表面自由能下降78.65%;120℃热处理后FPUA(w (FA) = 20 0 o)表面自由能可进一步降低17.69%;FPUA乳液粒径较PU明显增大且分布变宽;推测FPUA复合粒子既有胶束成核又有水相成核机理.%Novel cationic polyurethane-fluorinated acrylate(FPUA) hybrid emulsion was prepared with the copol ymerization of fluorinated acrylate(FA),styrene(St) and butyl acrylate(BA) in the medium of cationic polyure thane(PU) emulsion. The structure and properties of the emulsion and latex of FPUA were characterized by FT IR,contact angle measurements, submicron particle size analyzer and TEM respectively. The results show that only the FA content is beyond 20% ,FPUA can have good water and oil-repellency at the same time. The contact angle of water and CH2 I2 on the FPUA(ω(FA)=20%) film can achieved 110 and 86° respectively. The surface free energy of the FPUA(ω(FA)=20%) film annealed at 30℃ is 14.64mJ/m2 which decreased 78.65% in con trast with PU film. Moreover,the treatment of the films with high temperature can decrease the surface free en ergy by more than 17.69%. The results of submicron particle size analyzer and TEM indicate the particle size of FPUA is bigger than PU emulsion and wider in particle size distribution. Mechanism of core-forming of FPUA hybrid emulsion is discussed at last.

  12. Field trial of five repellent formulations against mosquitoes in Ahero, Kenya.

    Science.gov (United States)

    Sherwood, Van; Kioko, Elizabeth; Kasili, Sichangi; Ngumbi, Philip; Hollingdale, Michael R

    2009-01-01

    Twelve volunteers, using one leg for repellent application and the other leg as a control, field-tested 5 insect repellent formulations--Avon's (New York, NY) SS220 Spray, SS220 Lotion, and Bayrepel Lotion, and SC Johnson's (Racine, Wisconsin) Autan Bayrepel Lotion--against the standard N,N-diethyl-3-methyl-benzamide (deet) in a rice-growing district near Kisumu, western Kenya, in 2 trials in May and June 2004. In addition to a control leg for each volunteer, an additional control was introduced into the study by the use of a sixth repellent, a "null repellent," which was literally a treatment application of no repellent at all. The 5 active repellent formulations were uniformly applied at the maximum Environmental Protection Agency recommended dose of 1.5 g per 600 cm2 in the first trial and half that dose in the second trial, and none of them failed during the nightly 12-hour test period over 6 consecutive days, May 19 through May 24, 2004, and June 14 through June 19, 2004. However, the repellent control legs demonstrated a statistically significant increased landing rate compared to both the null repellent and the null repellent control leg. This suggests that, in this approach, active repellents increased the capture rate on an adjacent control leg compared to null controls. A single human volunteer can act as his/her own control provided null treatment controls are included.

  13. Insecticidal, repellent and fungicidal properties of novel trifluoromethylphenyl amides.

    Science.gov (United States)

    Tsikolia, Maia; Bernier, Ulrich R; Coy, Monique R; Chalaire, Katelyn C; Becnel, James J; Agramonte, Natasha M; Tabanca, Nurhayat; Wedge, David E; Clark, Gary G; Linthicum, Kenneth J; Swale, Daniel R; Bloomquist, Jeffrey R

    2013-09-01

    Twenty trifluoromethylphenyl amides were synthesized and evaluated as fungicides and as mosquito toxicants and repellents. Against Aedes aegypti larvae, N-(2,6-dichloro-4-(trifluoromethyl)phenyl)-3,5-dinitrobenzamide (1e) was the most toxic compound (24 h LC50 1940 nM), while against adults N-(2,6-dichloro-4-(trifluoromethyl)phenyl)-2,2,2-trifluoroacetamide (1c) was most active (24 h LD50 19.182 nM, 0.5 μL/insect). However, the 24 h LC50 and LD50 values of fipronil against Ae. aegypti larvae and adults were significantly lower: 13.55 nM and 0.787 × 10(-4) nM, respectively. Compound 1c was also active against Drosophila melanogaster adults with 24 h LC50 values of 5.6 and 4.9 μg/cm(2) for the Oregon-R and 1675 strains, respectively. Fipronil had LC50 values of 0.004 and 0.017 μg/cm(2) against the two strains of D. melanogaster, respectively. In repellency bioassays against female Ae. aegypti, 2,2,2-trifluoro-N-(2-(trifluoromethyl)phenyl)acetamide (4c) had the highest repellent potency with a minimum effective dosage (MED) of 0.039 μmol/cm(2) compared to DEET (MED of 0.091 μmol/cm(2)). Compound N-(2-(trifluoromethyl)phenyl)hexanamide (4a) had an MED of 0.091 μmol/cm(2) which was comparable to DEET. Compound 4c was the most potent fungicide against Phomopsis obscurans. Several trends were discerned between the structural configuration of these molecules and the effect of structural changes on toxicity and repellency. Para- or meta- trifluoromethylphenyl amides with an aromatic ring attached to the carbonyl carbon showed higher toxicity against Ae. aegypti larvae, than ortho- trifluoromethylphenyl amides. Ortho- trifluoromethylphenyl amides with trifluoromethyl or alkyl group attached to the carbonyl carbon produced higher repellent activity against female Ae. aegypti and Anopheles albimanus than meta- or para- trifluoromethylphenyl amides. The presence of 2,6-dichloro- substitution on the phenyl ring of the amide had an influence on larvicidal and repellent

  14. Studies toward the synthesis of the shark repellent pavoninin-5.

    Science.gov (United States)

    Williams, John R; Chai, Deping; Gong, Hua; Zhao, Wei; Wright, Dominic

    2002-12-01

    Sharks are the most dangerous predators of people in the sea, resulting in people being mauled and killed each year. A shark repellent could help to diminish this danger. The aglycone of the shark repellent pavoninin-5, (25R)-cholest-5-en-3beta,15alpha,26-triol (5a), was synthesized from diosgenin (9). Removing mercury from the Clemmensen reduction of 9 gave a higher yield of (25R)-cholest-5-en-3beta,16beta,26-triol, 10a, and was also more environmentally friendly. Attempted methods for the transposition of the C-16beta hydroxyl to the 15alpha position are described. A successful method for this transposition via the 15alpha-hydroxy-16-ketone, 8a, using the Barton deoxygenation reaction on the 16-alcohol 14b, is reported.

  15. Octanoic acid confers to royal jelly varroa-repellent properties

    Science.gov (United States)

    Nazzi, Francesco; Bortolomeazzi, Renzo; Della Vedova, Giorgio; Del Piccolo, Fabio; Annoscia, Desiderato; Milani, Norberto

    2009-02-01

    The mite Varroa destructor Anderson & Trueman is a parasite of the honeybee Apis mellifera L. and represents a major threat for apiculture in the Western world. Reproduction takes place only inside bee brood cells that are invaded just before sealing; drone cells are preferred over worker cells, whereas queen cells are not normally invaded. Lower incidence of mites in queen cells is at least partly due to the deterrent activity of royal jelly. In this study, the repellent properties of royal jelly were investigated using a lab bioassay. Chemical analysis showed that octanoic acid is a major volatile component of royal jelly; by contrast, the concentration is much lower in drone and worker larval food. Bioassays, carried out under lab conditions, demonstrated that octanoic acid is repellent to the mite. Field studies in bee colonies confirmed that the compound may interfere with the process of cell invasion by the mite.

  16. Elaboration of voltage and ion exchange stimuli-responsive conducting polymers with selective switchable liquid-repellency.

    Science.gov (United States)

    Taleb, Sabri; Darmanin, Thierry; Guittard, Frédéric

    2014-05-28

    In this work, we report the possibility to selectively switch by voltage and anion exchange the water-repellent properties, in comparison with the oil-repellent properties, of copolymers containing both fluorinated chain (EDOT-F8) and pyridinium (EDOT-Py(+)) moieties. Here, the fluorinated chains are necessary to reach superhydrophobic properties while the pyridinium moieties allow the switching in the wettability by counterion exchange. Because, conducting polymers can exist in their oxidized and reduced state, here, we report also the switching of their wettability by voltage. The best properties (superhydrophobic properties with low hysteresis and sliding and good oleophobic properties) are obtained for a % of EDOT-Py(+) of 25 %. Surprisingly, by reducing the polymer by changing the voltage, a selective decrease in the contact angle of water is observed, whereas that of oils (diiodomethane and hexadecane) remain unchanged, making it possible to have higher contact angles with diiodomethane than with water. Here, the switching in the wettability is due to the change of the water droplet from the Cassie-Baxter state to the Wenzel state by changing the voltage. Because of the presence of highly polar pyridinium groups and their perchlorate counterions, the wettability of oil droplets (diiodomethane and hexadecane) is not significantly affected. This effect is confirmed by changing the counterions with highly hydrophobic ones (C8F17SO3(-), Tf2N(-), or BF4(-)). Such materials are excellent candidates for oil/water separation membranes.

  17. Insecticidal, Repellent and Fungicidal Properties of Novel Trifluoromethylphenyl Amides

    Science.gov (United States)

    2013-01-01

    Insecticidal, repellent and fungicidal properties of novel trifluoromethylphenyl amidesq Maia Tsikolia a,⇑, Ulrich R. Bernier a, Monique R. Coy a...Swale e, Jeffrey R. Bloomquist e aU.S. Department of Agriculture - Agricultural Research Service, Center for Medical, Agricultural , and Veterinary...dU.S. Department of Agriculture - Agricultural Research Service, Natural Products Utilization Research Unit, The University of Mississippi, University

  18. A repellent net as a new technology to protect cabbage crops.

    Science.gov (United States)

    Martin, T; Palix, R; Kamal, A; Delétré, E; Bonafos, R; Simon, S; Ngouajio, M

    2013-08-01

    Floating row covers or insect-proof nets with fine mesh are effective at protecting vegetable crops against aphids but negatively impact plant health, especially under warm conditions. Furthermore, in control of cabbage insect pests, aphid parasitoids cannot enter the fine-mesh nets, leading to frequent aphid outbreaks. To surmount these difficulties, a 40-mesh-size repellent net treated with alphacypermethrin was studied in laboratory and field tests. Results showed both irritant and repellent effects of the alphacypermethrin-treated net on Myzus persicae (Sulzer) (Hemiptera: Aphididae) and its parasitoid Aphidius colemani (Haliday) (Hymenoptera: Braconidae). Under field conditions, there were no pests on cabbage protected with the repellent net. The repellent net allowed combining a visual and repellent barrier against aphids. Because of this additive effect, repellent nets allowed covering cabbage permanently with adequate protection against all pests.

  19. Neurophysiological and behavioral responses of gypsy moth larvae to insect repellents: DEET, IR3535, and picaridin.

    Directory of Open Access Journals (Sweden)

    Jillian L Sanford

    Full Text Available The interactions between insect repellents and the olfactory system have been widely studied, however relatively little is known about the effects of repellents on the gustatory system of insects. In this study, we show that the gustatory receptor neuron (GRN located in the medial styloconic sensilla on the maxillary palps of gypsy moth larvae, and known to be sensitive to feeding deterrents, also responds to the insect repellents DEET, IR3535, and picaridin. These repellents did not elicit responses in the lateral styloconic sensilla. Moreover, behavioral studies demonstrated that each repellent deterred feeding. This is the first study to show perception of insect repellents by the gustatory system of a lepidopteran larva and suggests that detection of a range of bitter or aversive compounds may be a broadly conserved feature among insects.

  20. Mosquito repellent activity of essential oils of aromatic plants growing in Argentina.

    Science.gov (United States)

    Gillij, Y G; Gleiser, R M; Zygadlo, J A

    2008-05-01

    Mosquitoes are important vectors of diseases and nuisance pests. Repellents minimize contact with mosquitoes. Repellents based on essential oils (EO) are being developed as an alternative to DEET (N,N-diethyl-m-methylbenzamide), an effective compound that has disadvantages including toxic reactions, and damage to plastic and synthetic fabric. This work evaluated the repellency against Aedes aegypti of EO from aromatic plants that grow in Argentina: Acantholippia seriphioides, Achyrocline satureioides, Aloysia citriodora, Anemia tomentosa, Baccharis spartioides, Chenopodium ambrosioides, Eucalyptus saligna, Hyptis mutabilis, Minthostachys mollis, Rosmarinus officinalis, Tagetes minuta and Tagetes pusilla. Most EO were effective. Variations depending on geographic origin of the plant were detected. At a 90% EO concentration, A. satureoides and T. pusilla were the least repellent. At concentrations of 12.5% B. spartioides, R. officinalis and A. citriodora showed the longest repellency times. Comparisons of the principal components of each EO suggest that limonene and camphor were the main components responsible for the repellent effects.

  1. Repellence of essential oils of aromatic plants growing in Argentina against Aedes aegypti (Diptera: Culicidae).

    Science.gov (United States)

    Gleiser, Raquel M; Bonino, Maria A; Zygadlo, Julio A

    2011-01-01

    Mosquitoes are vectors of pathogens to humans and domestic animals and may also have economical impacts. One approach to prevent mosquito-borne diseases is bite deterrence through the application of repellents. Currently, there is an interest to search for alternative bioactive products to the synthetic active ingredients most widely used in insect repellents. Repellence against Aedes aegypti of essential oils extracted from Acantholippia salsoloides, Aloysia catamarcensis, Aloysia polystachya, Lippia integrifolia, Lippia junelliana (Verbenaceae), Baccharis salicifolia, Euphatorium buniifolium, and Tagetes filifolia (Asteraceae) were assessed. Tests were conducted by alternatively exposing untreated and treated forehand to the mosquitoes and counting probing attempts. All essential oils tested were significantly repellent against A. aegypti when compared to untreated controls; L. junelliana was the most repellent and T. filifolia was the least based on the response of the mosquitoes to different concentrations of the essential oils (EO). Repellence may be attributed to the respective main components of each EO.

  2. Bacteria repelling on highly-ordered alumina-nanopore structures

    Science.gov (United States)

    Kim, Sunghan; Zhou, Yan; Cirillo, Jeffrey D.; Polycarpou, Andreas A.; Liang, Hong

    2015-04-01

    Bacteria introduce diseases and infections to humans by their adherence to biomaterials, such as implants and surgical tools. Cell desorption is an effective step to reduce such damage. Here, we report mechanisms of bacteria desorption. An alumina nanopore structure (ANS) with pore size of 35 nm, 55 nm, 70 nm, and 80 nm was used as substrate to grow Escherichia coli (E. coli) cells. A bacteria repelling experimental method was developed to quantitatively evaluate the area percentage of adherent bacterial cells that represent the nature of cell adhesion as well as desorption. Results showed that there were two crucial parameters: contact angle and contact area that affect the adhesion/desorption. The cells were found to be more easily repelled when the contact angle increased. The area percentage of adherent bacterial cells decreased with the decrease in the contact area of a cell on ANS. This means that cell accessibility on ANS depends on the contact area. This research reveals the effectiveness of the nanopored structures in repelling cells.

  3. Does Zika virus infection affect mosquito response to repellents?

    Science.gov (United States)

    Leal, Walter S.; Barbosa, Rosângela M. R.; Zeng, Fangfang; Faierstein, Gabriel B.; Tan, Kaiming; Paiva, Marcelo H. S.; Guedes, Duschinka R. D.; Crespo, Mônica M.; Ayres, Constância F. J.

    2017-01-01

    The World Health Organization (WHO) recommends that people travelling to or living in areas with Zika virus (ZIKV) outbreaks or epidemics adopt prophylactic measures to reduce or eliminate mosquito bites, including the use of insect repellents. It is, however, unknown whether repellents are effective against ZIKV-infected mosquitoes, in part because of the ethical concerns related to exposing a human subject’s arm to infected mosquitoes in the standard arm-in-cage assay. We used a previously developed, human subject-free behavioural assay, which mimics a human subject to evaluate the top two recommended insect repellents. Our measurements showed that DEET provided significantly higher protection than picaridin provided against noninfected, host-seeking females of the southern house mosquito, Culex quinquefasciatus, and the yellow fever mosquito, Aedes aegypti. When tested at lower doses, we observed a sig