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Sample records for repellent member method

  1. 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.

  2. 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

  3. 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.

  4. 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 ...

  5. 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.

  6. 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.

  7. Methods of Assessment for Affected Family Members

    Science.gov (United States)

    Orford, Jim; Templeton, Lorna; Velleman, Richard; Copello, Alex

    2010-01-01

    The article begins by making the point that a good assessment of the needs and circumstances of family members is important if previous neglect of affected family members is to be reversed. The methods we have used in research studies are then described. They include a lengthy semi-structured interview covering seven topic areas and standard…

  8. 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.

  9. 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.

  10. Assessment of methods used to determine the safety of the topical insect repellent N,N-diethyl-m-toluamide (DEET).

    Science.gov (United States)

    Chen-Hussey, Vanessa; Behrens, Ron; Logan, James G

    2014-06-03

    N,N-diethyl-m-toluamide (DEET) has been registered for commercial use as an insect repellent for over five decades, and is used widely across the world. Concerns over the safety of DEET first emerged during the 1980s after reports of encephalopathy following DEET exposure, particularly in children. However, the role of DEET in either the illness or deaths was and remains purely speculative. In response to these cases a number of reviews and investigations of DEET safety were carried out. Here we examine the methods used and information available to determine the safety of DEET in humans. Animal testing, observational studies and intervention trials have found no evidence of severe adverse events associated with recommended DEET use. Minor adverse effects noted in animal trials were associated with very large doses and were not replicated between different test species. The safety surveillance from extensive humans use reveals no association with severe adverse events. This review compares the toxicity assessment using three different models to define the risk assessment and safety threshold for DEET use in humans and discusses the clinical consequences of the thresholds derived from the models.The theoretical risks associated with wearing an insect repellent should be weighed against the reduction or prevention of the risk of fatal or debilitating diseases including malaria, dengue, yellow fever and filariasis. With over 48 million European residents travelling to regions where vector borne diseases are a threat in 2009, restricting the concentration of DEET containing repellents to 15% or less, as modelled in the 2010 EU directive, is likely to result in extensive sub-therapeutic activity where repellents are infrequently applied. Future European travellers, as a consequence of inadequate personal protection, could potentially be at increased risk of vector borne diseases. Risk assessments of repellents should take these factors into account when setting safe

  11. Method of recertifying a loaded bearing member

    Science.gov (United States)

    Allison, Sidney G. (Inventor)

    1992-01-01

    A method is described of recertifying a loaded bearing member using ultrasound testing to compensate for different equipment configurations and temperature conditions. The standard frequency F1 of a reference block is determined via an ultrasonic tone burst generated by a first pulsed phased locked loop (P2L2) equipment configuration. Once a lock point number S is determined for F1, the reference frequency F1a of the reference block is determined at this lock point number via a second P2L2 equipment configuration to permit an equipment offset compensation factor Fo1=((F1-F1a)/F1)(1000000) to be determined. Next, a reference frequency F2 of the unloaded bearing member is determined using a second P2L2 equipment configuration and is then compensated for equipment offset errors via the relationship F2+F2(Fo1)/1000000. A lock point number b is also determined for F2. A resonant frequency F3 is determined for the reference block using a third P2L2 equipment configuration to determine a second offset compensation factor F02=((F1-F3)/F1) 1000000. Next the resonant frequency F4 of the loaded bearing member is measured at lock point number b via the third P2L2 equipment configuration and the bolt load determined by the relationship (-1000000)CI(((F2-F4)/F2)-Fo2), wherein CI is a factor correlating measured frequency shift to the applied load. Temperature compensation is also performed at each point in the process.

  12. 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.

  13. 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...

  14. Application of clan member signal method in structural damage detection

    Institute of Scientific and Technical Information of China (English)

    Guo Xun; B.F. Spencer; Lu Shunan

    2007-01-01

    It is well known that in most cases, a reference is necessary for structural health diagnosis, and it is very difficult to obtain such a reference for a given structure. In this paper, a clan member signal method (CMSM) is proposed for use in structures consisting of groups (or clans) that have the same geometry, i.e., the same cross section and length, and identical boundary conditions. It is expected that signals measured on any undamaged member in a clan after an event could be used as a reference for any other members in the clan. To verify the applicability of the proposed method, a steel truss model is tested and the results show that the CMSM is very effective in detecting local damage in structures composed of identical slender members.

  15. Robust Polypropylene Fabrics Super-Repelling Various Liquids: A Simple, Rapid and Scalable Fabrication Method by Solvent Swelling.

    Science.gov (United States)

    Zhu, Tang; Cai, Chao; Duan, Chunting; Zhai, Shuai; Liang, Songmiao; Jin, Yan; Zhao, Ning; Xu, Jian

    2015-07-01

    A simple, rapid (10 s) and scalable method to fabricate superhydrophobic polypropylene (PP) fabrics is developed by swelling the fabrics in cyclohexane/heptane mixture at 80 °C. The recrystallization of the swollen macromolecules on the fiber surface contributes to the formation of submicron protuberances, which increase the surface roughness dramatically and result in superhydrophobic behavior. The superhydrophobic PP fabrics possess excellent repellency to blood, urine, milk, coffee, and other common liquids, and show good durability and robustness, such as remarkable resistances to water penetration, abrasion, acidic/alkaline solution, and boiling water. The excellent comprehensive performance of the superhydrophobic PP fabrics indicates their potential applications as oil/water separation materials, protective garments, diaper pads, or other medical and health supplies. This simple, fast and low cost method operating at a relatively low temperature is superior to other reported techniques for fabricating superhydrophobic PP materials as far as large scale manufacturing is considered. Moreover, the proposed method is applicable for preparing superhydrophobic PP films and sheets as well.

  16. 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; ...

  17. Rodent repellent studies. IV. Preparation and properties of trinitrobenzene-aryl amine complexes

    Science.gov (United States)

    DeWitt, J.B.; Bellack, E.; Welch, J.F.

    1953-01-01

    Data are presented on methods of preparation, chemical arid physical characteristics, toxicity, and repellency to rodents of complexes of symmetrical trinitrohenzene with various aromatic amines: When applied in suitable carriers or incorporated in plastic .films, members of this series ofmaterials were shown to offer significant increases in time required by wild rodents to damage common packaging materials.

  18. Two Methods for Deriving Members' Weights in Group Decision Making

    Institute of Scientific and Technical Information of China (English)

    XU Ze-shui

    2001-01-01

    The Analytic Hierarchy Process is a powerful technique for group decision making. Both theWeighted Arithmetic Mean Method (WAMM) and Weighted Geometric Mean Method (WGMM) are themost common group preference aggregation methods in AHP. In order to use the WAMM and WGMM, onehas to find the weights to be assigned to the members of the group. This is often a difficult task, especiallyso if the group is large as in the case of public policy decisions. These situations need an objective method toderive members'weights. But a few studies are available in the literature. Based on judgement matrices anderror analyses, this paper presents two practical and efficient methods for addressing such situations. Somenumerical examples are also given.

  19. Some basic design methods for HSC Structural Members

    DEFF Research Database (Denmark)

    Nielsen, Mogens Peter; Hoang, Cao Linh; Hagsten, Lars German

    1998-01-01

    Key-note paper.The paper deals with methods based on the theory of plasticity to be used in the design of reinforced concrete members of high strength concrete. Formulae for the bending capacity of beams subjected to pure bending are given. Methods for shear design of beams are described. Emphasis...... is put on the recently developed crack sliding model applicable to non-shear reinforced beams and lightly shear reinforced beams. The consequences of sliding in cracks on the strength of disk elements are also described. The methods described are compared with results of tests with high strength concrete...

  20. 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.

  1. 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.

  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. Stuck threaded member extractor tool and extraction methods

    Science.gov (United States)

    Roscosky, James M.; Essay, Shane M.

    2016-02-02

    Disclosed is a tool having a tapered first portion configured to translate a rotational force to the stuck member, a second portion connecting with the first portion and configured to translate the rotational force to the tapered first portion, a planar tip at an end of the first portion and perpendicular to a central axis passing through the first portion and the second portion, a plurality of left-handed splines extending helically around the central axis from the tip toward the second portion, a driver engaged with the second portion and configured to receive a third rotational force from a mechanical manipulator, and a leak seal connected to the driver and configured to form a seal around the stuck member and at least a portion of the driver and prevent gases opposite the stuck member from escaping.

  4. 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.

  5. Nanoformulation of poly(ethylene glycol) polymerized organic insect repellent by PIT emulsification method and its application for Japanese encephalitis vector control.

    Science.gov (United States)

    Balaji, A P B; Mishra, Prabhakar; Suresh Kumar, R S; Mukherjee, Amitava; Chandrasekaran, Natarajan

    2015-04-01

    The utilization of increased dosage of insect repellents to overcome mosquito resistance has raised environmental concerns globally. In accord to this, we have formulated an efficacious, water-dispersive, nanometric formulation of a poor water-soluble insect repellent, diethylphenylacetamide (DEPA) by poly(ethylene glycol) (PEG) polymerization followed by PIT emulsification method. The critical micelle concentration of PEG in the spontaneously emulsified conventional DEPA droplets was determined, based on the droplets physical stability. Subjecting them to PIT emulsification yielded monodispersed polymeric nanomicelles of DEPA (Nano DEPA) with hydrodynamic mean diameter of 153.74 nm. The high-resolution scanning and transmission electron microscopic studies revealed the characteristic core-shell structure of micelle. The comparative efficacy of Bulk DEPA and Nano DEPA was evaluated by larvicidal and WHO cone bioassay against the Japanese encephalitis vector Culex tritaeniorhynchus. The median lethal concentrations (48 h) for 3rd instars C. tritaeniorhynchus larvae were found to be 0.416 mg/L for Bulk DEPA and 0.052 mg/L for Nano DEPA, respectively. The median knockdown concentrations (60 min) for the two to three-day-old, sucrose-fed, female adult mosquitoes were 5.372% (v/v) and 3.471% (v/v) for Bulk and Nano DEPA, respectively. Further investigation by histopathological and biochemical studies propound that Nano DEPA exerted better bioefficacy as comparative to its bulk form even at minimal exposure concentrations. Hence, Nano DEPA will serve as an effective alternate in controlling the vector expansion with reduced dosage.

  6. 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

  7. 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...

  8. 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.

  9. Method of producing ceramic distribution members for solid state electrolyte cells

    Science.gov (United States)

    Clark, Douglas J. (Inventor); Galica, Leo M. (Inventor); Losey, Robert W. (Inventor); Suitor, Jerry W. (Inventor)

    1995-01-01

    A solid state electrolyte cells apparatus and method of producing is disclosed. The apparatus can be used for separating oxygen from an oxygen-containing feedstock or as a fuel cell for reacting fluids. Cells can be stacked so that fluids can be introduced and removed from the apparatus through ceramic distribution members having ports designed for distributing the fluids in parallel flow to and from each cell. The distribution members can also serve as electrodes to membranes or as membrane members between electrodes, The distribution member design does not contain any horizontal internal ports which allows the member to be thin. A method of tape casting in combination with an embossing method allows intricate radial ribs and bosses to be formed on each distribution member. The bosses serve as seals for the ports and allow the distribution members to be made without any horizontal internal ports.

  10. 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.

  11. An appropriate method for extracting the insect repellent citronellol from an indigenous plant (Pelargonium graveolens L'Her for potential use by resource-limited animal owners

    Directory of Open Access Journals (Sweden)

    B.M. Botha

    2000-07-01

    Full Text Available Veterinary needs appraisals in rural, peri-urban and urban areas have indicated a need for affordable and accessible veterinary health care. It was also found that farmers and animal owners used indigenous plants for treating animals. In Africa, insects such as Culex, Culicoides and Stomoxys may transmit diseases, cause irritation to animals or prevent wound healing. Insect repellents used topically are generally safer and cheaper than insecticides. Using readily available commercial sources of ethanol 43 %v/v (brandy and cane spirits, it was shown that citronellol could be extracted from uncrushed leaves of the indigenous shrub Pelargonium graveolens L'Hér. Efficacy of extraction was compared to that using reagent grade absolute ethanol. The peak concentration of citronellol was achieved within 7 days of extraction and thereafter remained constant for 4 months. Extraction methods using tap water and cooking oil were not successful. The extraction was also less successful when the leaves were crushed or macerated before being placed into ethanol. Gas chromatography was used to monitor the concentration of citronellol in the different extracts.

  12. 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 ...

  13. 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.

  14. 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.

  15. Insect repellent plants traditional usage practices in the Ethiopian malaria epidemic-prone setting: an ethnobotanical survey

    Science.gov (United States)

    2014-01-01

    Background The usage of insect repellent plants (IRPs) is one of the centuries-old practices in Africa. In Ethiopia, malaria remains a leading cause of morbidity and mortality, subsequently the majority of people have a tendency to apply various plants as repellents to reduce or interrupt the biting activity of insects. Accordingly, this survey was undertaken to document and evaluate knowledge and usage practices of the local inhabitants on IRPs in the malaria epidemic-prone setting of Ethiopia. Methods Ethnobotanical survey was conducted between January and May 2013. Selected 309 household members were interviewed by administering pre-tested questionnaire on knowledge and usage practices of repellent plants, in Bechobore Kebele, Jimma Zone, Ethiopia. Results Overall, 70.2% (217/309) and 91.8% (199/217) of the respondents have had ample awareness and usage practices of repellent plants, respectively. Informants cited about twenty-two plant species as repellents and also indicated that these plants are useful(85.5%), accessible(86.8%), and affordable(83.9%) too. Residents mainly applying dried leaves [93.9% (187/199)] by means of burning/smouldering [98.9% (197/199)] with the traditional charcoal stove to repel insects, primarily mosquitoes. About 52.8% (105/199) of the informants using aproximately15g of dried plant-materials every day. A Chi-square analysis shows statistically a significant link between the knowledge on repellent plants and gender as well as average monthly income although not with the age of the respondents. Nevertheless, the repellent plant usage custom was not significantly associated with gender, monthly income, and age of the informants. Conclusion Though most of the people have had an adequate awareness still a sizable faction of society suffers with deprivation of IRPs knowledge and usage practices. Therefore, this study calls for more surveys to conserve the existing indigenous knowledge and cultural practices. It could lay the first stone

  16. 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.

  17. 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...

  18. 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.

  19. 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.

  20. Bayesian methods for the conformational classification of eight-membered rings

    DEFF Research Database (Denmark)

    Pérez, J.; Nolsøe, Kim; Kessler, M.

    2005-01-01

    Two methods for the classification of eight-membered rings based on a Bayesian analysis are presented. The two methods share the same probabilistic model for the measurement of torsion angles, but while the first method uses the canonical forms of cyclooctane and, given an empirical sequence...... of eight torsion angles, yields the probability that the associated structure corresponds to each of the ten canonical conformations, the second method does not assume previous knowledge of existing conformations and yields a clustering classification of a data set, allowing new conformations...... to be detected. Both methods have been tested using the conformational classification of Csp3 eight-membered rings described in the literature. The methods have also been employed to classify the solidstate conformation in Csp3 eight-membered rings using data retrieved from an updated version of the Cambridge...

  1. Bayesian methods for the conformational classification of eight-membered rings

    DEFF Research Database (Denmark)

    Pérez, J.; Nolsøe, Kim; Kessler, M.;

    2005-01-01

    Two methods for the classification of eight-membered rings based on a Bayesian analysis are presented. The two methods share the same probabilistic model for the measurement of torsion angles, but while the first method uses the canonical forms of cyclooctane and, given an empirical sequence of e...

  2. Internal Stress Monitoring of In-Service Structural Steel Members with Ultrasonic Method

    Directory of Open Access Journals (Sweden)

    Zuohua Li

    2016-03-01

    Full Text Available Internal stress in structural steel members is an important parameter for steel structures in their design, construction, and service stages. However, it is hard to measure via traditional approaches. Among the existing non-destructive testing (NDT methods, the ultrasonic method has received the most research attention. Longitudinal critically refracted (Lcr waves, which propagate parallel to the surface of the material within an effective depth, have shown great potential as an effective stress measurement approach. This paper presents a systematic non-destructive evaluation method to determine the internal stress in in-service structural steel members using Lcr waves. Based on theory of acoustoelasticity, a stress evaluation formula is derived. Factor of stress to acoustic time difference is used to describe the relationship between stress and measurable acoustic results. A testing facility is developed and used to demonstrate the performance of the proposed method. Two steel members are measured by using the proposed method and the traditional strain gauge method for verification. Parametric studies are performed on three steel members and the aluminum plate to investigate the factors that influence the testing results. The results show that the proposed method is effective and accurate for determining stress in in-service structural steel members.

  3. Reviewing Grasha Teaching Methods among Faculty Members of Shiraz Medical School

    Directory of Open Access Journals (Sweden)

    Mitra Amini

    2012-12-01

    Full Text Available Introduction: Teaching and training are the basic responsibly of a faculty member. One of the fundamental problems of education in the universities is not having a criterion to identify the effective teaching styles. The aim of this study was to determine Grasha teaching method among the faculty Members in Shiraz Medical School. Methods: this descriptive, cross- sectional study was done on 100 faculty members who were selected by census sampling method. Data collection method was Grasha questionnaire which contains 40 questions in 5 sections. Data were analyzed by SPSS 18. Results: All questionnaires were completed. The age range was from 32 to 65 and the mean age was 46. 57% were male. There were 27 PhD, 35 specialists and 38 subspecialists. The highest average score belonged to “Expert” method (2/66±0/55 and the lowest to “Personal” (2± 0/76. 96% of the academic staffs were inclined to “Expert“ method and %97, %83, %78, %80 to “Formal", “Personal", “Delegator“ and “Facilitating“ methods, respectively. There was no significant difference between male and female, but in “Expert” method, the average of females was superior. %77 was under 50 years and %23 over 50. There was no significant difference between elder and younger academic members. No significant difference was found in terms of university degree. Conclusion: This study suggested academic members are inclined to use "Expert” and Delegator methods. Therefore, it is necessary for the academic members to choose a method which creates intellectual excitement among the students through the clarity of teaching content and understanding among individuals that increase the efficiency of their methods.

  4. 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.

  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

    redistribution of hydrophobic organic compounds that caused water repellency. The addition of PAM further reduced in all of the cases. The application of PAM could be an effective method for mitigation of water repellency in burnt soils.

  6. 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.

  7. Fatigue Reliability Assessment of Steel Member Using Probabilistic Stress-Life Method

    Directory of Open Access Journals (Sweden)

    Dae-Hung Kang

    2012-01-01

    Full Text Available The fatigue reliability of a steel member in a bridge is estimated by using the probabilistic stress-life method. The stress history of a member is defined as the loading block when a truck passes over a bridge, and the stress range frequency distribution of the stress history is obtained by a stress range frequency analysis. A probabilistic method is applied to the stress range frequency distribution, and the parameters of the probability distribution for the stress range frequency distribution are used in a numerical simulation. To obtain the probability of failure of a member under a loading block, Monte Carlo simulation is performed in conjunction with Miner's rule, the modified Miner's rule, and Haibach's rule for fatigue damage evaluation. Through these analyses procedures, we obtain an evaluation method for fatigue reliability that can predict the block number of the failure load and residual fatigue life.

  8. [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

  9. 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.

  10. 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.

  11. Multimodal Optimization by Covariance Matrix Self-Adaptation Evolution Strategy with Repelling Subpopulations.

    Science.gov (United States)

    Ahrari, Ali; Deb, Kalyanmoy; Preuss, Mike

    2017-01-01

    During the recent decades, many niching methods have been proposed and empirically verified on some available test problems. They often rely on some particular assumptions associated with the distribution, shape, and size of the basins, which can seldom be made in practical optimization problems. This study utilizes several existing concepts and techniques, such as taboo points, normalized Mahalanobis distance, and the Ursem's hill-valley function in order to develop a new tool for multimodal optimization, which does not make any of these assumptions. In the proposed method, several subpopulations explore the search space in parallel. Offspring of a subpopulation are forced to maintain a sufficient distance to the center of fitter subpopulations and the previously identified basins, which are marked as taboo points. The taboo points repel the subpopulation to prevent convergence to the same basin. A strategy to update the repelling power of the taboo points is proposed to address the challenge of basins of dissimilar size. The local shape of a basin is also approximated by the distribution of the subpopulation members converging to that basin. The proposed niching strategy is incorporated into the covariance matrix self-adaptation evolution strategy (CMSA-ES), a potent global optimization method. The resultant method, called the covariance matrix self-adaptation with repelling subpopulations (RS-CMSA), is assessed and compared to several state-of-the-art niching methods on a standard test suite for multimodal optimization. An organized procedure for parameter setting is followed which assumes a rough estimation of the desired/expected number of minima available. Performance sensitivity to the accuracy of this estimation is also studied by introducing the concept of robust mean peak ratio. Based on the numerical results using the available and the introduced performance measures, RS-CMSA emerges as the most successful method when robustness and efficiency are

  12. A low-cost repellent for malaria vectors in the Americas: results of two field trials in Guatemala and Peru

    Directory of Open Access Journals (Sweden)

    Sihuincha Moisés

    2007-08-01

    Full Text Available Abstract Background The cost of mosquito repellents in Latin America has discouraged their wider use among the poor. To address this problem, a low-cost repellent was developed that reduces the level of expensive repellent actives by combining them with inexpensive fixatives that appear to slow repellent evaporation. The chosen actives were a mixture of para-menthane-diol (PMD and lemongrass oil (LG. Methods To test the efficacy of the repellent, field trials were staged in Guatemala and Peru. Repellent efficacy was determined by human-landing catches on volunteers who wore the experimental repellents, control, or 15% DEET. The studies were conducted using a balanced Latin Square design with volunteers, treatments, and locations rotated each night. Results In Guatemala, collections were performed for two hours, commencing three hours after repellent application. The repellent provided >98% protection for five hours after application, with a biting pressure of >100 landings per person/hour. The 15% DEET control provided lower protection at 92% (p 46 landings per person/hour. The 20% DEET control provided significantly lower protection at 64% (p Conclusion In both locations, the PMD/LG repellent provided excellent protection up to six hours after application against a wide range of disease vectors including Anopheles darlingi. The addition of fixatives to the repellent extended its longevity while enhancing efficacy and significantly reducing its cost to malaria-endemic communities.

  13. 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...

  14. A Simplified Method for Analyzing Truss Structure Due to Removal of Members

    Institute of Scientific and Technical Information of China (English)

    周岱; 周笠人; 刘红玉

    2003-01-01

    Based on relating equation group, a simplified method was presented in terms of the matrix displacement method, which can be conveniently used to study the re-distribution of the internal forces and displacement of truss structures due to the removal of members. Such removal is treated as though adding a load case to the original truss, and the re-distribution can be calculated without modifying the original global stiffness matrix. The computational efficiency of the presented method is faster by square times than that of the matrix displacement method.The results from the two methods are identical.

  15. 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

  16. A METHOD FOR MEASURING THE SENSITIVITY OF BUILDING STRUCTURAL MEMBERS TO FIRE DECAY PHASES

    Directory of Open Access Journals (Sweden)

    Thomas Gernay

    2016-10-01

    Full Text Available Firefighters face a major threat when intervening in a building during a fire: the possibility of structural collapse during the cooling phase of the fire, or soon thereafter. At present, this threat is amplified by the fact that the behaviour of structures after the time of peak gas temperature is not well understood, and is not taken into account in the design. This work presents an analysis of the behaviour of different structural members under natural fires, and develops a method for characterizing their sensitivity to fire decay phases. Thermo-mechanical numerical simulations based on the non-linear finite element method are conducted using the parametric fire model of the Eurocode to represent natural fires. The results show that, for all the members (a column, a beam and materials (reinforced concrete, steel and timber that are studied here, structural failure during or after the cooling phase of a fire is a possible event. The major factors that promote delayed structural failure are thermal inertia and the constituting material of the member. A method, based on a new indicator, is proposed for quantifying the propensity to delayed failure for structural members under natural fire. This work enhances the understanding of the behaviour of structures under natural fires, and has important implications for the safety of fire brigades and of people responsible for making a building inspection after a fire.

  17. Rapid microbiochemical method for presumptive identification of gastroenteritis-associated members of the family Enterobacteriaceae.

    Science.gov (United States)

    Yong, D C; Thompson, J S; Prytula, A

    1985-06-01

    A method for rapid screening of isolates of pathogenic members of the family Enterobacteriaceae is described. Flow charts are used in conjunction with triple sugar iron agar, o-nitrophenyl-beta-D-galactopyranoside-phenylalanine-motility sulfate screening media, oxidase test, and six rapid biochemical tests, namely, lysine decarboxylase, urease, indole, esculin hydrolysis, malonate, and xylose. This scheme is used to provide an inexpensive but rapid presumptive identification of Salmonella, Shigella, Edwardsiella, Aeromonas, Plesiomonas, Vibrio, and Yersinia isolates from stool cultures.

  18. Rapid microbiochemical method for presumptive identification of gastroenteritis-associated members of the family Enterobacteriaceae.

    OpenAIRE

    Yong, D C; Thompson, J. S.; Prytula, A

    1985-01-01

    A method for rapid screening of isolates of pathogenic members of the family Enterobacteriaceae is described. Flow charts are used in conjunction with triple sugar iron agar, o-nitrophenyl-beta-D-galactopyranoside-phenylalanine-motility sulfate screening media, oxidase test, and six rapid biochemical tests, namely, lysine decarboxylase, urease, indole, esculin hydrolysis, malonate, and xylose. This scheme is used to provide an inexpensive but rapid presumptive identification of Salmonella, Sh...

  19. 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.

  20. 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.

  1. 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.

  2. Evaluation of Repellency Effect of Essential Oils of Satureja khuzestanica (Carvacrol, Myrtus communis (Myrtle, Lavendula officinalis and Salvia sclarea using Standard WHO Repellency Tests.

    Directory of Open Access Journals (Sweden)

    Mohammad Hassan Kayedi

    2014-06-01

    Full Text Available Using special lotions and repellent sprays on skin is one of the effective methods to prevent Arthropods biting which was verified in this study.Essential oils of four plants (Satureja khuzestanica, Salvia sclarea, Lavendula officinalis and Myrtus communis were separately extracted by Clevenger used hydro distillation method. Then separated solutions with 10%, 20% and 40% concentrations of essential oils of plants in 99.6 % ethanol were prepared. WHO guidelines for efficacy testing of mosquito repellents for human skin were used on different concentrations of essential oils of plants, traditional repellents (DEET, 50% and 33% as positive control, and ethanol 99.6% and naked hands as negative controls.In negative control groups, the number of bits were comparable (P= 0.42 and had decreasing time trends (naked hands P= 0.011, ethanol P< 0.001. In all time points, minimum bites were observed in traditional repellents and it was significantly less than the other groups (P< 0.001. The time trend in the number of bites in the other groups was positive and showed minimum number of bites in time zero in all groups. We also found that the concentration of repellents had association with the number of bites. The maximum and minimum numbers of bites were observed with 10% and 40% concentrations respectively in all groups.Essential oils of Salvia sclarea, Lavendula officinalis and Myrtus communis have repellency effect, even with 10% concentration of essential oils.

  3. 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,...

  4. 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...

  5. 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

  6. Physicians, Primary Caregivers and Topical Repellent: All Under-Utilised Resources in Stopping Dengue Virus Transmission in Affected Households.

    Directory of Open Access Journals (Sweden)

    Nguyet Minh Nguyen

    2016-05-01

    Full Text Available Primary health care facilities frequently manage dengue cases on an ambulatory basis for the duration of the patient's illness. There is a great opportunity for specific messaging, aimed to reduce dengue virus (DENV transmission in and around the home, to be directly targeted toward this high-risk ambulatory patient group, as part of an integrated approach to dengue management. The extent however, to which physicians understand, and can themselves effectively communicate strategies to stop focal DENV transmission around an ambulatory dengue case is unknown; the matter of patient comprehension and recollection then ensues. In addition, the effectiveness of N,N-diethyl-3-methylbenzamide (DEET-based insect repellent in protecting dengue patients from Aedes aegypti mosquitoes' bites has not been investigated.A knowledge, attitude and practice (KAP survey, focusing on the mechanisms of DENV transmission and prevention, was performed using semi-structured questionnaires. This survey was targeted towards the patients and family members providing supportive care, and physicians routinely involved in dengue patient management in Southern Vietnam. An additional clinical observational study was conducted to measure the efficacy of a widely-used 13% DEET-based insect repellent to repel Ae. aegypti mosquitoes from the forearms of dengue cases and matched healthy controls.Among both the physician (n = 50 and patient (n = 49 groups there were several respondents lacking a coherent understanding of DENV transmission, leading to some inappropriate attitudes and inadequate acute preventive practices in the household. The application of insect repellent to protect patients and their relatives from mosquito bites was frequently recommended by majority of physicians (78% participating in the survey. Nevertheless, our tested topical application of 13% DEET conferred only ~1hr median protection time from Ae. aegypti landing. This is notably shorter than that

  7. Biomimetic ultra-bubble-repellent surfaces based on a self-organized honeycomb film.

    Science.gov (United States)

    Kamei, Jun; Saito, Yuta; Yabu, Hiroshi

    2014-12-02

    The adhesion of bubbles underwater remains the greatest cause of malfunctions in applications such as microfluidics, medical devices and heat exchangers. There is therefore an emerging need for ultra-bubble-repellent surfaces. Inspired by fish scales, which show high bubble repellency due to their hydrophilic nature and surface microstructures, we propose a novel method for preparing ultra-bubble-repellent surfaces by the hydrophilic treatment of self-organized microstructures. When in contact with air bubbles underwater, the artificial hydrophilic microstructured surfaces had a higher contact angle and a lower adhesion force than a flat surface. The mechanism leading to these properties is also investigated. Our method for the fabrication of ultra-bubble-repellent, hydrophilic, microstructured surfaces is simple and cost-effective, opening the way for its application in artificial devices, such as the inner surfaces of tubes, medical devices, and heat exchangers.

  8. Application of classification methods in assessment of NATO member countries' economic, security and political risks

    Science.gov (United States)

    Odehnal, Jakub

    2013-10-01

    The aim of this paper is to attempt possible quantification of determinants of military expenditure and their application to current NATO member countries. To analyse the economic, security and political risks of NATO member countries, author employ multivariate statistical techniques which take into consideration the multivariate properties of the data sets used as input variables. Classification of countries based on cluster analysis has made it possible to identify disparities between NATO member countries, and thus to describe diverse economic or security environment affecting the amount of military expenditure as a percentage of the respective countries' gross domestic product.

  9. 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.

  10. 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.

  11. Laboratory evaluation of aromatic essential oils from thirteen plant species as candidate repellents against Leptotrombidium chiggers (Acari: Trombiculidae), the vector of scrub typhus.

    Science.gov (United States)

    Eamsobhana, Praphathip; Yoolek, Adisak; Kongkaew, Wittaya; Lerdthusnee, Kriangkrai; Khlaimanee, Nittaya; Parsartvit, Anchana; Malainual, Nat; Yong, Hoi-Sen

    2009-03-01

    Scrub typhus, a rickettsial disease transmitted by several species of Leptotrombidium chiggers (larvae), is endemic in many areas of Asia. The disease is best prevented by the use of personal protective measures, including repellents. In this study commercially produced aromatic, essential oils of 13 plant species and ethanol (control) were tested in the laboratory for repellency against host-seeking chiggers of Leptotrombidium imphalum Vercammen-Grandjean and Langston (Acari: Trombiculidae). A rapid, simple and economic in vitro test method was used by exposing the chigger for up to 5 min. Repellency was based on relative percentages of chiggers attracted to test and control substances. Four of the 13 essential oils showed promise as effective repellent against L. imphalum chiggers. Syzygium aromaticum (clove) oil exhibited 100% repellency at 5% concentration (dilution with absolute ethanol), whereas Melaleuca alternifolia (tea tree) oil exhibited 100% repellency at 40% concentration. Undiluted oils of Zingiber cassamunar (plai) and Eucalyptus globules (blue gum) exhibited 100% repellency. Of the remaining nine essential oils, only 100% Pelargonium graveolens (geranium) exhibited >50% repellency (viz. 57%). Styrax torkinensis (benzoin) oil did not exhibit any repellency. These findings show that several aromatic, essential oils of plants may be useful as chigger repellent for the prevention of scrub typhus. Syzygium aromaticum oil may be safer and more economical to prevent chigger attacks than commercially available synthetic chemicals, such as DEET that may have harmful side effects.

  12. 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.

  13. 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.

  14. 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.

  15. Identification of repellent odorants to the body louse, Pediculus humanus corporis, in clove essential oil.

    Science.gov (United States)

    Iwamatsu, Takuma; Miyamoto, Daisuke; Mitsuno, Hidefumi; Yoshioka, Yoshiaki; Fujii, Takeshi; Sakurai, Takeshi; Ishikawa, Yukio; Kanzaki, Ryohei

    2016-04-01

    The control of body lice is an important issue for human health and welfare because lice act as vectors of disease such as typhus, relapsing fever, and trench fever. Body lice exhibit avoidance behavior to some essential oils, including clove essential oil. Therefore, odorants containing clove essential oil components may potentially be useful in the development of repellents to body lice. However, such odorants that induce avoidance behavior in body lice have not yet been identified from clove essential oil. Here, we established an analysis method to evaluate the avoidance behavior of body lice to specific odorants. The behavioral analysis of the body lice in response to clove essential oil and its constituents revealed that eugenol, a major component of clove essential oil, has strong repellent effect on body lice, whereas the other components failed to induce obvious avoidance behavior. A comparison of the repellent effects of eugenol with those of other structurally related odorants revealed possible moieties that are important for the avoidance effects to body lice. The repellent effect of eugenol to body lice was enhanced by combining it with the other major component of clove essential oil, β-caryophyllene. We conclude that a synthetic blend of eugenol and β-caryophyllene is the most effective repellent to body lice. This finding will be valuable as the potential use of eugenol as body lice repellent.

  16. 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.

  17. Destructive Behaviors among Members of the Black Community with a Special Focus on Males: Causes and Methods of Intervention.

    Science.gov (United States)

    Kirk, Alton R.

    1986-01-01

    Discusses the relationship between stress, depression, homicide, and suicide within the psychosocial context of an ethnic minority group; examines the relationship between mental health and destructive behavior among Blacks; and suggests some possible methods of intervention as well as prevention of destructive behaviors among members of the Black…

  18. 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.

  19. 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.

  20. 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

  1. 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

    formed at a fuel load of 300 g. Pine needle litter formed the most severe soil water repellency and fresh pine needle formed the thickest water repellent layer, whilst broad-leaf litter did only cause water repellency on the surface of the sand. The soil evaporation rate was measured by a gravitational method at an isothermal condition. Undisturbed soil columns were sealed after adding 50 ml of tap water through the bottom. After twelve hours of stabilization, the columns were opened and covered with filter paper. The rate of soil evaporation through the soil surface was measured by the hourly weight change at 45° C. The initial 65 hours' evaporation rate was analyzed, while the slope of cumulative evaporation over time maintained its linearity. It was found that as the thickness of the water repellent layer increased, the evaporation rate tended to decrease. These two variables showed a good correlation (Pearson's correlation coefficient =-0.8916, p=0.0170) and a large coefficient of determination (R2=0.795) in the linear regression. This suggests that a layer of water repellent soil can affect water evaporation rate and that the rate is negatively correlated with the thickness of the repellent layer.

  2. 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

  3. Millennial Dental Hygiene Students' Learning Preferences Compared to Non-Millennial Faculty Members' Teaching Methods: A National Study.

    Science.gov (United States)

    Turner, April M; Prihoda, Thomas J; English, Dana K; Chismark, Aubreé; Jacks, Mary E

    2016-09-01

    The aim of this study was to compare the learning preferences of millennial dental hygiene students (born between 1982 and 2002) in the U.S. with the teaching methods used by their non-millennial instructors. Cross-sectional surveys were developed with 21-item, five-point Likert scales to examine students' preferences for and faculty use of lecture, collaborative activities, technology, independent work, and group discussion. Surveys were emailed to U.S. dental hygiene program directors in September 2015. The respondents totaled 800 students and 343 faculty members-approximately 5% of all dental hygiene students and 6.8% of all dental hygiene faculty members in the U.S. The results showed that the responding faculty members (88.7%) used case studies more than the students (61.2%) preferred and that the students (71.4%) preferred games when learning more than the faculty members (57.2%) used them (pmillennial dental hygiene students in this study were consistent with previous research on millennial traits. This study found areas of disagreement between students and faculty members on the use of case studies, study guides, and group work. Although these students stated they preferred lecture over group work, trends in education stress using active learning over lecture.

  4. Evaluation of catmint oil and hydrogenated catmint oil as repellents for the flour beetles, Tribolium castaneum and Tribolium confusum.

    Science.gov (United States)

    Arthur, Frank H; Fontenot, Emily A; Campbell, James F

    2011-01-01

    Catmint oil and hydrogenated catmint oil were evaluated as repellents for adult Tribolium casteneum (Herbst) (Coleoptera: Tenebrionidae), the red flour beetle, and T. confusum (DuVal), the confused flour beetle, using both a traditional method of visual assessment of distribution and a video recording method to determine movement patterns of individual insects. Visual assessments of distribution using groups of adults showed that the hydrogenated catmint oil was more effective than the pure catmint oil, but there was no significant difference between species. However, when repellency was measured using single insects and the visual recording system, both oils were significantly more repellent to T. castaneum than T. confusum at the concentrations evaluated in the study. Avoidance movement and change in direction when T. castaneum encountered the repellent were observed. Results indicate that repellents may be more accurately assessed using single insects rather than groups of individuals, and simple visual observations of distribution may be less sensitive in measuring repellent efficacy. Procedures for utilizing a video system are described as models for future evaluations of repellents for stored-product beetles.

  5. Field evaluation of commercial off-the-shelf spatial repellents against the Asian tiger mosquito, Aedes Albopictus (Skuse), and the potential for use during deployment.

    Science.gov (United States)

    Lloyd, Aaron M; Farooq, Muhammed; Diclaro, Joseph W; Kline, Daniel L; Estep, Alden S

    2013-01-01

    The Testing and Evaluation Department of the US Navy Entomology Center of Excellence (NECE), Naval Air Station, Jacksonville, Florida, is dedicated to the evaluation of novel equipment and vector control techniques to provide guidance on effective protection measures against human pathogens transmitted by blood-feeding arthropods. Personal protective measures (PPM), to include repellents, are part of a series of techniques that contribute toward reducing human-vector contact for globally and domestically deployed military forces. However, improper PPM use and limited availability has created vulnerabilities, causing troops to purchase spatial repellent products that are not approved by the Department of Defense. In order to ensure the most effective products are available, NECE has evaluated the spatial repellency response of Aedes albopictus (Skuse) to 4 commercial off-the-shelf (COTS) spatial repellents to provide technical guidance on proper use and effectiveness. The COTS products evaluated ThermaCELL, OFF! Clip On, Lentek Bite Shield, and Bug Button Mosquito Eliminator. A Biogents Sentinel (BGS) trap was placed in 5 locations with a spatial repellent device suspended at the level of the BGS trap opening over 4 of them (the fifth was control). Each trap catch was collected every 12 hours, at which time the spatial repellent device was rotated to the next position. Using this method, each spatial repellent device and control was rotated across each of the 5 locations a total of 6 times. Spatial repellent efficiency was evaluated by comparing the total number of mosquitoes collected in the BGS traps during a 12-hour period. The number of adult mosquitoes repelled by the ThermaCell spatial repellent was significantly more than other spatial repellents with the exception of OFF!. These data indicate that COTS products using repellent insecticide rather than botanicals are more effective at deterring Ae. albopictus from biting a host.

  6. DEET mosquito repellent provides personal protection against malaria: a household randomized trial in an Afghan refugee camp in Pakistan

    National Research Council Canada - National Science Library

    Rowland, Mark; Downey, Gerald; Rab, Abdur; Freeman, Tim; Mohammad, Nasir; Rehman, Hamid; Durrani, Naeem; Reyburn, Hugh; Curtis, Chris; Lines, Jo; Fayaz, Mohammad

    2004-01-01

    Synthetic repellents based on di‐ethyl 3‐methyl benzamide (DEET) are a popular method of obtaining protection from mosquitoes and yet clear evidence for a protective effect against malaria has hitherto never been convincingly demonstrated...

  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. 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.

  10. 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...

  11. 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.

  12. Optimization of pyrethroid and repellent on fabrics against Stegomyia albopicta (=Aedes albopictus) using a microencapsulation technique.

    Science.gov (United States)

    Yao, T-T; Wang, L-K; Cheng, J-L; Hu, Y-Z; Zhao, J-H; Zhu, G-N

    2015-03-01

    A new approach employing a combination of pyrethroid and repellent is proposed to improve the protective efficacy of conventional pyrethroid-treated fabrics against mosquito vectors. In this context, the insecticidal and repellent efficacies of commonly used pyrethroids and repellents were evaluated by cone tests and arm-in-cage tests against Stegomyia albopicta (=Aedes albopictus) (Diptera: Culicidae). At concentrations of LD50 (estimated for pyrethroid) or ED50 (estimated for repellent), respectively, the knock-down effects of the pyrethroids or repellents were further compared. The results obtained indicated that deltamethrin and DEET were relatively more effective and thus these were selected for further study. Synergistic interaction was observed between deltamethrin and DEET at the ratios of 5 : 1, 2 : 1, 1 : 1 and 1 : 2 (but not 1 : 5). An optimal mixing ratio of 7 : 5 was then microencapsulated and adhered to fabrics using a fixing agent. Fabrics impregnated by microencapsulated mixtures gained extended washing durability compared with those treated with a conventional dipping method. Results indicated that this approach represents a promising method for the future impregnation of bednet, curtain and combat uniform materials.

  13. Evaluation of a direct fluorescent antibody staining method for rapid identification of members of the bacteroides fragilis group.

    Science.gov (United States)

    DeGirolami, P C; Mepani, C P

    1981-07-01

    A direct fluorescent antibody test kit (Fluorotec-F, Pfizer Inc., New York, New York) designed for rapid identification of members of the Bacteroides fragilis group (BFG) was evaluated. Tested were 228 clinical specimens (144 direct smears of clinical material, 14 smears of positive blood cultures, and 70 smears of colonies isolated from clinical material) and 49 reference strains of anaerobic bacteria, including 23 members of the BFG. Fluorotec-F detected 68 of 69 (98.5%) members of the BFG, including 55 B. fragilis, 12 B. thetaiotaomicron, and two B. ovatus, identified by cultural methods in all clinical specimens. Three specimens that yielded B. uniformis also fluoresced. Three specimens fluoresced but failed to yield members of the BFG or B. uniformis on culture. Of the 49 reference strains tested, all strains of B. fragilis, B. thetaiotaomicron, nd B. uniformis tested were detected by Fluorotec-F, but only five of a total of 14B. vulgatus, B. distasonis, and B. ovatus tested fluoresced. Of the 25 reference strains of anaerobic bacteria not belonging to the BFG, none fluoresced except for two strains of B. eggerthii. Direct fluorescent antibody staining of smears of clinical specimens suitable for anaerobic culture is a valuable tool for rapid detection of B. fragilis infections.

  14. 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

  15. 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

  16. 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...

  17. Methods and Teaching Strategies Used by Teacher Education Faculty Members in one State University in the Philippines

    Directory of Open Access Journals (Sweden)

    Amado C. Ramos

    2015-12-01

    Full Text Available Institutions of higher learning across the nation are responding to political, economic, social and technological pressures to be more responsive to students' needs and more concerned about how well students are prepared to assume future societal roles. This study aimed to determine the methods and teaching strategies used by the PSU – CTE faculty members of Bayambang Campus, Bayambang, Pangasinan during the first semester of the school year 2013-2014. The descriptivecorrelational method of research was employed in this study where it involved the collection of pertinent data in order to answer questions concerning the current status of the subject of the study. Majority of the faculty members are females, they are master’s degree holders, have a permanent position with an academic rank of instructor, and most of the faculty members are graduate of SUCs. They also have high attitude toward teaching; generally, the faculty members perceived themselves to be often in using teaching approaches and teaching methods; and sometimes in using teaching techniques/styles, instructional support activities, and non-formal activities; and no significant relationships exist between the faculty members’ profile variables and their level of pedagogical approaches in teaching approaches, teaching methods, teaching techniques/styles, non-formal activities and instructional support activities. Teachers should be encouraged to pursue/finish higher education, likewise they should be motivated to conduct research studies like action researches as part of their functions, particularly along their area of specialization. Teachers should be encouraged to explore and view other effective teaching strategies and find more ways to entice other students challenge themselves to create their own strategies to use in the field and to become more global in perspective. The use computer technology can be an effective teaching strategy, especially when students are given

  18. Methods and Teaching Strategies Used by Teacher Education Faculty Members in one State University in the Philippines

    OpenAIRE

    Amado C. Ramos

    2015-01-01

    Institutions of higher learning across the nation are responding to political, economic, social and technological pressures to be more responsive to students' needs and more concerned about how well students are prepared to assume future societal roles. This study aimed to determine the methods and teaching strategies used by the PSU – CTE faculty members of Bayambang Campus, Bayambang, Pangasinan during the first semester of the school year 2013-2014. The descriptivecorrelational...

  19. 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.

  20. Efficacy of Some Wearable Devices Compared with Spray-On Insect Repellents for the Yellow Fever Mosquito, Aedes aegypti (L.) (Diptera: Culicidae).

    Science.gov (United States)

    Rodriguez, Stacy D; Chung, Hae-Na; Gonzales, Kristina K; Vulcan, Julia; Li, Yiyi; Ahumada, Jorge A; Romero, Hector M; De La Torre, Mario; Shu, Fangjun; Hansen, Immo A

    2017-01-01

    The current Zika health crisis in the Americas has created an intense interest in mosquito control methods and products. Mosquito vectors of Zika are of the genus Aedes, mainly the yellow fever mosquito, Aedes aegypti. L. The use of repellents to alter mosquito host seeking behavior is an effective method for the prevention of mosquito-borne diseases. A large number of different spray-on repellents and wearable repellent devices are commercially available. The efficacies of many repellents are unknown. This study focuses on the efficacy of eleven different repellents in reducing the number of Ae. aegypti female mosquitoes attracted to human bait. We performed attraction-inhibition assays using a taxis cage in a wind tunnel setting. One person was placed upwind of the taxis cage and the mosquito movement towards or away from the person was recorded. The person was treated with various spray-on repellents or equipped with different mosquito repellent devices. We found that the spray-on repellents containing N,N-Diethyl-meta-toluamide and p-menthane-3,8-diol had the highest efficacy in repelling mosquitoes compared to repellents with other ingredients. From the five wearable devices that we tested, only the one that releases Metofluthrin significantly reduced the numbers of attracted mosquitoes. The citronella candle had no effect. We conclude that many of the products that we tested that were marketed as repellents do not reduce mosquito attraction to humans. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America.

  1. 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...

  2. Repellency Effect of Myrtle Essential Oil and DEET against Phlebotomus papatasi, under Labo-ratory Conditions

    Directory of Open Access Journals (Sweden)

    MR Yaghoobi-Ershadi

    2006-07-01

    Full Text Available Zoonotic cutaneous leishmaniasis (ZCL is an increasing and important public health problem in Iran. The use of repellents is recommended as one of the important means of personal protection against vectors of ZCL. This paper reports the repellency effect of the plant Myrtle, Myrtus communis (Myrtaceae, essential oil for protection against 3-7-day-old unfed females of the sandfly, Phlebotomus papatasi Scopoli for the first time in Iran. The tests were carried out under laboratory conditions, using dose-response testing procedure on white rabbits and the results were compared with commonly used repellent, diethyl-3-methylbenzamid (DEET. The modified Wirtz method using K & D apparatus was employed. Effective Dose (EDs values were estimated from the probit regression line. ED50 was measured as 0.1140 and 0.0006 mg/cm2 for Myrtle essential oil and DEET, respectively. The laboratory tests showed that both Myrtle essential oil and DEET had repellency effects against P.papatasi. In addition, the insecticidal action of Myrtle oil was also observed. We concluded that the two repellents could be used as a mean of personal protection against sand flies.

  3. Acaricidal and repellent activities of essential oil of Eucalyptus globulus against Dermanyssus gallinae (Acari: Mesostigmata

    Directory of Open Access Journals (Sweden)

    Dehghani-Samani Amir

    2015-07-01

    Full Text Available Introduction: By considering an increase in drug resistance against red mites, finding the nonchemical herbal acaricide against Dermanyssus gallinae (De Geer (Acari: Mesostigmata is necessary to kill them and to reduce the chemical resistance against chemical acaricides in this specie. Dermanyssus gallinae is a potential vector of the causal agent of several viral diseases such as Equine encephalitis and St. Louis encephalitis. It can be a vector of bacteria such as Salmonella spp., Mycobacterium spp. and Erysipelothrix rhusiopathiae. It is also known to cause itching dermatosis in humans. In this study acaricidal and repellent activities of essential oil of Eucalyptus globulus against Dermanyssus gallinae were studied. Methods: After extracting the essential oil, different concentrations of the plant extract were prepared. Then, acaricidal effect of different concentrations was tested on poultry red mite, Dermanyssus gallinae, by dropping 3-4 drops of essential oil on mites. Repellent activity of essential oil was tested by Y-tube olfactometer bioassay. After the test, total number of killed and repellent mites reported. Results: Concentration of 1:2 or 50% had more acaricidal effect on mites. Also essential oil of Eucalyptus globulus had repellent activity against red mites. Conclusion: This study showed that essential oil of Eucalyptus globulus had acaricidal and repellent activities against red mites. Hence it might be used as a herbal acaricide against it to kill and to reduce the chemical resistance in this specie.

  4. 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.

  5. 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...

  6. 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

  7. 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...

  8. 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...

  9. 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...

  10. 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

  11. Evaluation of catmint oil and hydrogenated catmint oil as repellents for Tribolium castaneum and Tribolium confusum

    Science.gov (United States)

    Catmint oil and hydrogenated catmint oil were evaluated as repellents for adult Tribolium casteneum (Herbst), the red flour beetle, and T. confusum (Jacqueline DuVal), the confused flour beetle, using both a traditional method of visual assessment of distribution and a video recording method to dete...

  12. 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.

  13. 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...

  14. Insecticidal and repellent activity of Siparuna guianensis Aubl. (Negramina against Aedes aegypti and Culex quinquefasciatus.

    Directory of Open Access Journals (Sweden)

    Raimundo Wagner Souza Aguiar

    Full Text Available This study investigated the toxic effects of essential oils isolated from Siparuna guianensis against Aedes aegypti, Culex quinquefasciatus (eggs, larvae, pupae, and adult and Aedes albopictus (C6/36 cells. The oviposition-deterring activity, egg viability, and repellence activity in the presence of different essential oils concentrations were determined. The essential oils showed high toxicity to all developmental stages of A. aegypti and C. quinquefasciatus. Furthermore, the oils also showed high repellent activity towards the adult stage of mosquitoes (0.025 to 0.550 μg/cm2 skin conferred 100% repellence up to 120 min and in contact with cultured insect cells (C6/36 induced death possibly by necrosis. The results presented in this work show the potential of S. guianensis essential oils for the development of an alternative and effective method for the natural control of mosquitoes in homes and urban areas.

  15. Insecticidal and repellent activity of Siparuna guianensis Aubl. (Negramina) against Aedes aegypti and Culex quinquefasciatus.

    Science.gov (United States)

    Aguiar, Raimundo Wagner Souza; dos Santos, Suetonio Fernandes; da Silva Morgado, Fabricio; Ascencio, Sergio Donizeti; de Mendonça Lopes, Magnólia; Viana, Kelvinson Fernandes; Didonet, Julcemar; Ribeiro, Bergmann Morais

    2015-01-01

    This study investigated the toxic effects of essential oils isolated from Siparuna guianensis against Aedes aegypti, Culex quinquefasciatus (eggs, larvae, pupae, and adult) and Aedes albopictus (C6/36) cells. The oviposition-deterring activity, egg viability, and repellence activity in the presence of different essential oils concentrations were determined. The essential oils showed high toxicity to all developmental stages of A. aegypti and C. quinquefasciatus. Furthermore, the oils also showed high repellent activity towards the adult stage of mosquitoes (0.025 to 0.550 μg/cm2 skin conferred 100% repellence up to 120 min) and in contact with cultured insect cells (C6/36) induced death possibly by necrosis. The results presented in this work show the potential of S. guianensis essential oils for the development of an alternative and effective method for the natural control of mosquitoes in homes and urban areas.

  16. 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.

  17. Study of the comprehension of the scientific method by members of a university health research laboratory.

    Science.gov (United States)

    Burlamaque-Neto, A C; Santos, G R; Lisbôa, L M; Goldim, J R; Machado, C L B; Matte, U; Giugliani, R

    2012-02-01

    In Brazil, scientific research is carried out mainly at universities, where professors coordinate research projects with the active participation of undergraduate and graduate students. However, there is no formal program for the teaching/learning of the scientific method. The objective of the present study was to evaluate the comprehension of the scientific method by students of health sciences who participate in scientific projects in an academic research laboratory. An observational descriptive cross-sectional study was conducted using Edgar Morin complexity as theoretical reference. In a semi-structured interview, students were asked to solve an abstract logical puzzle - TanGram. The collected data were analyzed using the hermeneutic-dialectic analysis method proposed by Minayo and discussed in terms of the theoretical reference of complexity. The students' concept of the scientific method is limited to participation in projects, stressing the execution of practical procedures as opposed to scientific thinking. The solving of the TanGram puzzle revealed that the students had difficulties in understanding questions and activities focused on subjects and their processes. Objective answers, even when dealing with personal issues, were also reflected on the students' opinions about the characteristics of a successful researcher. Students' difficulties concerning these issues may affect their scientific performance and result in poorly designed experiments. This is a preliminary study that should be extended to other centers of scientific research.

  18. Study of the comprehension of the scientific method by members of a university health research laboratory

    Directory of Open Access Journals (Sweden)

    A.C. Burlamaque-Neto

    2012-02-01

    Full Text Available In Brazil, scientific research is carried out mainly at universities, where professors coordinate research projects with the active participation of undergraduate and graduate students. However, there is no formal program for the teaching/learning of the scientific method. The objective of the present study was to evaluate the comprehension of the scientific method by students of health sciences who participate in scientific projects in an academic research laboratory. An observational descriptive cross-sectional study was conducted using Edgar Morin complexity as theoretical reference. In a semi-structured interview, students were asked to solve an abstract logical puzzle - TanGram. The collected data were analyzed using the hermeneutic-dialectic analysis method proposed by Minayo and discussed in terms of the theoretical reference of complexity. The students’ concept of the scientific method is limited to participation in projects, stressing the execution of practical procedures as opposed to scientific thinking. The solving of the TanGram puzzle revealed that the students had difficulties in understanding questions and activities focused on subjects and their processes. Objective answers, even when dealing with personal issues, were also reflected on the students’ opinions about the characteristics of a successful researcher. Students’ difficulties concerning these issues may affect their scientific performance and result in poorly designed experiments. This is a preliminary study that should be extended to other centers of scientific research.

  19. 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

    accounts for the effects of gravity and lateral expansion. According to Pekárová et al. (2015), the combination of all the ethanol and water sorptivities was used to calculate an aggregated repellency index, RIa, that accounts for the influence of spatial variability. Alternatively, the plot of the water cumulative infiltration vs. square root of time, exhibiting a clear "hockey-stick-like" shape, was used to estimate a single-test repellency index, RI∗, that overcomes the limitations of the traditional approach given that information on both the hydrophobic and the wettable states of soil are gathered from a unique infiltration test. The mean RI values were affected by the technique used to estimate Sw and Se. In particular, the choice of a fixed time interval lead to overestimation of RI up to a factor of 3.2 as compared with the other techniques. The RIa yielded unbiased estimations of the mean RI values and also allowed to quantify the variability of SWR within a given area. A statistically significant relationship was found between RI∗ and RI but also between RI∗ and the water retention cessation time, that is the time hydrophobic turns into wettable soil, thus indicating that RI∗ is potentially able detect both the degree and the persistence of SWR. Pekárová P., Pekár J., Lichner Ľ. 2015. A new method for estimating soil water repellency index. Biologia, 70(11):1450-1455.

  20. 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

  1. The repellent and persistent toxic effects of essential oils against the poultry red mite, Dermanyssus gallinae.

    Science.gov (United States)

    Nechita, I S; Poirel, M T; Cozma, V; Zenner, L

    2015-12-15

    The economic impact of the poultry red mite, Dermanyssus gallinae, the lack of new acaricides, the occurrence of resistance and tighter legislation have all led to the need to find new ways to control this pest. One promising alternative method of control focuses on employing repellent and/or toxic effects of selected plant essential oils against D. gallinae. Ten essential oils (basil, thyme, coriander, eucalyptus, lavender, lemon, fir tree, oregano, mint, and juniper) were tested for the persistence of toxic and repellent effects. In filter-paper toxicity bioassays against D. gallinae, the best results were observed for lavender (more than 97% mortality after 48 and 72 h) and thyme (84% at 72 h) at a dose of 0.12 mg/cm(2). In addition, two oils showed significant persistent toxic effects 15 and 30 days post application to filter papers. Thyme was the most effective (100% mortality at 72 h), followed by lavender (nearly 80% mortality after 72 h). Out of the ten oils tested for their repellent effect, thyme was the strongest, with nearly 80% of the tested area avoided by mites; oregano caused a 60% avoidance and lavender exhibited an effect close to 40%. All other oils exhibited a repellent effect of less than 30%. None of the experiments showed a repellent effect for HM (commercial alimentary oil) or negative controls. We found that the thyme and lavender essential oils exhibited promising results when tested in vitro for toxic and repellent effects against D. gallinae; thus, we suggest that future experiments focus on in vivo tests using these oils in farm units.

  2. 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.

  3. Evaluation of repellents efficacy against Anopheles gambiae s.s.; an anthropophilic malaria vector

    Directory of Open Access Journals (Sweden)

    Gerald Katunzi

    2015-03-01

    Full Text Available Reduction of human-vector contact is of epidemiological importance in malaria control. Repellents can be used to complement the existing intervention tools against malaria vectors. Thus, evaluation of efficacy of additional mosquito repellents and /or attractants is of great significance for personal protection tools against malaria vectors. This study evaluated the repellence efficacy of menthol-propylene-glycol-carbonate (MR08 and Lemon grass (LG against Anopheles gambiae. Experiments were performed in a room which was 7.8 meters by 3.9 meters in dimension. Three experimental set ups were performed, i comparison of 10 hours worn sock and unworn sock;  ii comparison of  10 hours worn sock treated with MR08 against worn sock alone, and iii comparison of  10 hours worn sock treated with LG against worn sock alone. CDC miniature light traps were used to evaluate the recovery of released mosquitoes using both repellents and attractants. After initial trials, a concentration of 500 ppm was selected for all repellents. Among 1800 mosquitoes released into the experimental room, 1230 were recovered by CDC light traps while the remaining 570 were found within the experimental room. Among those collected by light traps, 1185 were collected by traps with worn sock alone. A worn sock treated with either MR08 or Lemon grass significantly repelled An.gambiae compared to worn sock alone. The findings of this study demonstrate that MR08 and lemon grass have inhibition efficiency against mosquito stings but further field evaluations are required for observed findings against wild populations of An.gambiae at lower Moshi using slow release method.

  4. 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.

  5. Explosive welding method for manufacturing ITER-grade 316L(N)/CuCrZr hollow structural member

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Rui, E-mail: mr9980@163.com [PLA University of Science and Technology, Nanjing 210007 (China); Wang, Yaohua [PLA University of Science and Technology, Nanjing 210007 (China); Wu, Jihong [Southwestern Institute of Physics, Chengdu 610041 (China); Duan, Mianjun [PLA University of Science and Technology, Nanjing 210007 (China)

    2014-12-15

    Highlights: • Develop a new explosive welding method to fabricate the cooling channel of FW. • Utilize effective energy model to accurately calculate optimal welding parameters. • Provide an efficient way for manufacturing high-ductility hollow structural member. - Abstract: In this study, a new explosive welding method provided an effective way for manufacturing ITER-grade 316L(N)/CuCrZr hollow structural member. The welding parameters (stand-off distance and explosion rate) were calculated respectively using equivalent frontal collision wave model and effective energy model. The welded samples were subject to two step heat treatment cycles (solution annealing and aging). Optical microscopy (OM) and scanning electron microscopy (SEM) were utilized to analyze the microstructure of bonding interface. The mechanical properties of the welded samples were evaluated through microhardness test and tensile test. Moreover, the sealing property of the welded specimens was measured through helium leak test. Microstructural analysis showed that the welded sample using effective energy model had an ideal wavy interface. The results of microhardness test revealed an increase in hardness for both sides near to the bonding interface. And the hardening phenomenon of interface region disappeared after the solution annealing. SEM observation indicated that the samples with the post heat treatments exhibited a ductile fracture with dimple features after tensile test. After the specimens undergo aging strengthening, there was an obvious increase in the strength for all specimens. The helium leak test results have proven that the welded specimens are soundness.

  6. '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

  7. Prospects for repellent in pest control: current developments and future challenges

    Science.gov (United States)

    The overall interest for environmentally safe pest control methods and the increased frequency of insecticide resistance in pest populations have stimulated research on insect repellents in the recent decades in medical and agricultural entomology. However, there remains a great deal of work to be ...

  8. Bioconjugation of protein-repellent zwitterionic polymer brushes grafted from silicon nitride

    NARCIS (Netherlands)

    Nguyen, A.T.; Baggerman, J.; Paulusse, J.M.J.; Zuilhof, H.; Rijn, van C.J.M.

    2012-01-01

    A new method for attaching antibodies to protein-repellent zwitterionic polymer brushes aimed at recognizing microorganisms while preventing the nonspecific adsorption of proteins is presented. The poly(sulfobetaine methacrylate) (SBMA) brushes were grafted from α-bromo isobutyryl initiator-function

  9. Bioconjugation of Protein-Repellent Zwitterionic Polymer Brushes Grafted from Silicone Nitride

    NARCIS (Netherlands)

    Nguyen, A.T.; Baggerman, J.; Paulusse, J.M.J.; Zuilhof, H.; Rijn, van C.J.M.

    2012-01-01

    A new method for attaching antibodies to protein-repellent zwitterionic polymer brushes aimed at recognizing microorganisms while preventing the nonspecific adsorption of proteins is presented. The poly(sulfobetaine methacrylate) (SBMA) brushes were grafted from a-bromo isobutyryl initiator-function

  10. A new in vitro bioassay system for discovery and quantitative evaluation of mosquito repellents

    Science.gov (United States)

    Mosquitoes are vectors of many pathogens that cause human diseases. Although prevention and control of immature stages is the best method to control mosquitoes, repellents play a significant role in reducing the risk of these diseases by preventing mosquito bites. The In vitro K & D bioassay system ...

  11. 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.

  12. 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...

  13. 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.

  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. 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.

  16. 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...

  17. 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

  18. 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%...

  19. 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.

  20. A novel protein-repellent dental composite containing 2-methacryloyloxyethyl phosphorylcholine.

    Science.gov (United States)

    Zhang, Ning; Chen, Chen; Melo, Mary As; Bai, Yu-Xing; Cheng, Lei; Xu, Hockin Hk

    2015-06-26

    Secondary caries due to biofilm acids is a primary cause of dental composite restoration failure. To date, there have been no reports of dental composites that can repel protein adsorption and inhibit bacteria attachment. The objectives of this study were to develop a protein-repellent dental composite by incorporating 2-methacryloyloxyethyl phosphorylcholine (MPC) and to investigate for the first time the effects of MPC mass fraction on protein adsorption, bacteria attachment, biofilm growth, and mechanical properties. Composites were synthesized with 0 (control), 0.75%, 1.5%, 2.25%, 3%, 4.5% and 6% of MPC by mass. A commercial composite was also tested as a control. Mechanical properties were measured in three-point flexure. Protein adsorption onto the composite was determined by the microbicinchoninic acid method. A human saliva microcosm biofilm model was used. Early attachment at 4 h, biofilm at 2 days, live/dead staining and colony-forming units (CFUs) of biofilms grown on the composites were investigated. Composites with MPC of up to 3% had mechanical properties similar to those without MPC and those of the commercial control, whereas 4.5% and 6% MPC decreased the mechanical properties (Prepellent composites could help to repel bacteria attachment and plaque build-up to reduce secondary caries. The protein-repellent method might be applicable to other dental materials.

  1. LATERAL BUCKLING ANALYSIS OF THIN-WALLED MEMBERS BY FINITE MEMBER ELEMENT METHOD%横向荷载作用下薄壁杆件稳定分析的有限杆元法

    Institute of Scientific and Technical Information of China (English)

    吴秀水; 辛克贵; 姜美兰

    2001-01-01

    根据位移变分原理,本文提出薄壁杆件稳定分析的有限杆元法。分析中考虑了杆壁中面剪应变的影响,能很好地描述剪力滞后现象。本方法采用线性函数作为横截面翘曲位移的插值函数,适用于任意横截面形状和任意边界条件的薄壁杆件。本文讨论了横向荷载作用下具有不同边界条件的工字型薄壁梁的屈曲荷载。数值算例结果表明了本方法灵活、有效、且有很好的精度。%Based on the principle of minimum potential energy, a generalmethod, called finite member element method, is developed for buckling analysis of thin-walled members with shear lag in the present paper. A linear function is used to express the warping displacements along the cross section of the thin-walled member. The present method is applicable to thin-walled members of any cross section with any boundary conditions. In order to evaluate this method, the critical loads of I-beams subjected to various loading conditions and different boundary conditions are studied. Numerical examples show that the present method is efficient and versatile. It offers more reliable and accurate results as compared to the classical theory of thin-walled members.

  2. Fresh, dried or smoked? repellent properties of volatiles emitted from ethnomedicinal plant leaves against malaria and yellow fever vectors in Ethiopia

    Directory of Open Access Journals (Sweden)

    Dube Fitsum

    2011-12-01

    Full Text Available Abstract Background In the search for plant-based mosquito repellents, volatile emanations were investigated from five plant species, Corymbia citriodora, Ocimum suave, Ocimum lamiifolium, Olea europaea and Ostostegia integrifolia, traditionally used in Ethiopia as protection against mosquitoes. Methods The behaviour of two mosquitoes, the malaria vector Anopheles arabiensis and the arbovirus vector Aedes aegypti, was assessed towards volatiles collected from the headspace of fresh and dried leaves, and the smoke from burning the dried leaves in a two-choice landing bioassay and in the background of human odour. Results Volatile extracts from the smoke of burning dried leaves were found to be more repellent than those from fresh leaves, which in turn were more repellent to mosquitoes than volatiles from dried leaves. Of all smoke and fresh volatile extracts, those from Co. citriodora (52-76% and Oc. suave (58-68% were found to be the most repellent, Os. integrifolia (29-56% to be intermediate while Ol. europaea (23-40% and Os. integrifolia (19-37% were the least repellent. One volatile present in each of the fresh leaf extracts of Co. citriodora, Oc. suave and Os. integrifolia was ß-ocimene. The levels of ß-ocimene reflected the mosquito repellent activity of these three fresh leaf extracts. Female host-seeking mosquitoes responded dose-dependently to ß-ocimene, both physiologically and behaviourally, with a maximal behavioural repulsion at 14% ß-ocimene. ß-ocimene (14% repels mosquitoes in our 6-minute landing assays comparable to the synthetic insect repellent N,N-diethyl-m-toluamide (10% DEET. Conclusions Volatiles in the smoke of burning as well as fresh leaves of Co. citriodora and Oc. suave have significant repellent properties against host seeking An. arabiensis and Ae. aegypti mosquitoes. ß-ocimene, present in the fresh leaf headspace of Co. citriodora, Oc. suave and Os. integrifolia, is a significantly effective volatile mosquito

  3. Simplified method for the frequency analysis of offshore structures with inclined members; Methode simplifiee pour l`analyse dynamique en frequence des structures offshore a membres inclines

    Energy Technology Data Exchange (ETDEWEB)

    Genatios, C.; Lafuente, M.; Garces, F. [Universidad Central de Venezuela, IMME, Caracas (Venezuela); Ferrante, A. [Universidade Federal do Rio de Janeiro, COPPE (Brazil)

    1998-12-01

    This paper presents a simplified procedure for the deterministic dynamic analysis of offshore structures with inclined members in the frequency domain. This simplified procedure requires the linearization of the velocity term of the Morison formula. A direct time integration method is implemented in the time domain, in order to verify the efficiency of the frequency domain procedure and the consequences of the involved simplifications. Three typical structures: a caisson, a steel jacket and a reinforced concrete lacustrine structure, are analyzed. Linearization of the velocity term, leads to more conservative results with a maximal error of 15 % for the three analyzed structures. (authors) 19 refs.

  4. Repellent activity of some essential oils against Simulium species in India.

    Science.gov (United States)

    Hazarika, S; Dhiman, Sunil; Rabha, Bipul; Bhola, R K; Singh, Lokendera

    2012-01-01

    Use of repellents seems to be most reliable method of personal protection against annoyance and infections associated with haematophagous insects. We have investigated the biting activity of Simulium and tested the repellency of five essential oils extracted from Homalomena aromatica Schott (Alismatales: Araceae), Pogostemon heyneanus Bentham (Lamiales: Lamiaceae), Citrus aurantifolia Swingle (Sapindales: Rutaceae), Vitex negundo L. (Lamiales: Lamiaceae), and Ageratum conzoides L. (Asterales: Asteraceae) on the human volunteers against Simulium (blackflies) in three locations of Arunachal Pradesh, India. Blackflies preferred biting legs (> 79%) as compared to hand and face with profound biting activity during 1000-1100 h (> 23%) and 1500 - 1600 h (> 28%). The essential oil extracted from Homalomena aromatica, Vitex negundo and Ageratum conizoides provided > 2 h protection at 5% concentration and > 5 h protection at 10% concentration in all the three testing locations. The repellency of Homalomena aromatica, Vitex negundo and Ageratum conizoides essential oils after 6 h application was > 50% at 5% concentration and > 90% at 10% concentration. The study provides evidence for the potential of these essential oils in developing new repellents against blackflies.

  5. Larvicidal and mosquito repellent activities of Pine (Pinus longifolia, Family: Pinaceae oil

    Directory of Open Access Journals (Sweden)

    M.A. Ansari, P.K. Mittal, R.K. Razdan & U. Sreehari

    2005-09-01

    Full Text Available Background & objectives: Various plant-based products are safe and biodegradable alternatives tosynthetic chemicals for use against mosquitoes. Oil of Pinus longifolia is traditionally used forprotection against mosquitoes in some rural areas but there is no documented report of its use againstmosquitoes. The present study was undertaken to scientifically evaluate the activity of Pine oilagainst mosquitoes.Methods: The oil was procured from the market and its contents were chemically analysed. Larvicidalactivity of oil was tested in laboratory bioassays, while repellent action was studied during wholenight bait collections in field by direct application on the skin and after its impregnation on mats.Results: Results showed varying degree of larvicidal activity of Pine oil against mosquitoes with LC50values ranging between 82 and 112 ppm. The Pine oil had strong repellent action against mosquitoesas it provided 100% protection against Anopheles culicifacies for 11 h and 97% protection againstCulex quinquefasciatus for nine hours respectively. Electrically heated mats prepared from Pine oilprovided, 94 and 88% protection against An. culicifacies and Cx. quinquefasciatus for 10 and sevenhours respectively.Interpretaion & conclusion: Pine oil is effective against mosquito larvae at very higher doses whichare not of any practical utility. However, Pine oil showed strong repellent action against An. culicifacies(malaria vector and Cx. quinquefasciatus (pest mosquito. Thus its use could be popularised asmosquito repellent.

  6. 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.

  7. A novel protein-repellent dental composite containing 2-methacryloyloxyethyl phosphorylcholine

    Institute of Scientific and Technical Information of China (English)

    Ning Zhang; Chen Chen; Mary AS Melo; Yu-Xing Bai; Lei Cheng; Hockin HK Xu

    2015-01-01

    Secondary caries due to biofilm acids is a primary cause of dental composite restoration failure. To date, there have been no reports of dental composites that can repel protein adsorption and inhibit bacteria attachment. The objectives of this study were to develop a protein-repellent dental composite by incorporating 2-methacryloyloxyethyl phosphorylcholine (MPC) and to investigate for the first time the effects of MPC mass fraction on protein adsorption, bacteria attachment, biofilm growth, and mechanical properties. Composites were synthesized with 0 (control), 0.75%, 1.5%, 2.25%, 3%, 4.5%and 6%of MPC by mass. A commercial composite was also tested as a control. Mechanical properties were measured in three-point flexure. Protein adsorption onto the composite was determined by the microbicinchoninic acid method. A human saliva microcosm biofilm model was used. Early attachment at 4 h, biofilm at 2 days, live/dead staining and colony-forming units (CFUs) of biofilms grown on the composites were investigated. Composites with MPC of up to 3%had mechanical properties similar to those without MPC and those of the commercial control, whereas 4.5%and 6%MPC decreased the mechanical properties (P,0.05). Increasing MPC from 0 to 3%reduced the protein adsorption on composites (P,0.05). The composite with 3%MPC had protein adsorption that was 1/12 that of the control (P,0.05). Oral bacteria early attachment and biofilm growth were also greatly reduced on the composite with 3%MPC, compared to the control (P,0.05). In conclusion, incorporation of MPC into composites at 3%greatly reduced protein adsorption, bacteria attachment and biofilm CFUs, without compromising mechanical properties. Protein-repellent composites could help to repel bacteria attachment and plaque build-up to reduce secondary caries. The protein-repellent method might be applicable to other dental materials.

  8. 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.

  9. Laboratory evaluation of traditionally used plant-based insect repellent against the malaria vector Anopheles arabiensis Patton (Diptera: Culicidae).

    Science.gov (United States)

    Karunamoorthi, Kaliyaperumal; Ilango, Kandan; Murugan, Kadarkarai

    2010-04-01

    A laboratory study was carried out to evaluate the repellent efficacy of a methanol-leaf extract of Ethiopian traditionally used insect repellent plant viz., Lomi sar [vernacular name (local native language, Amharic); Cymbopogon citratus (DC) Stapf. (Poaceae)] against Anopheles arabiensis at four different concentrations viz., 1.0, 1.5, 2.0, and 2.5 mg/cm(2). The percentage protection in relation to the dose method was performed. C. citratus extract has shown various degrees of repellency impact against A. arabiensis. It provided the maximum total percentage protection of 78.83% at 2.5 mg/cm(2) and followed 68.06% at 2.0 mg/cm(2) for 12 h. All four tested concentrations of C. citratus extract offered significant protection and Student's t test results shows statistically significant (p value = 0.001) [1.0 mg/cm(2) (t = 22.89; df = 4); 1.5 mg/cm(2) (t = 24.03; df = 4); 2.0 mg/cm(2) (t = 36.92; df = 4); 2.5 mg/cm(2) (t = 22.31; df = 4)] difference between treated and control groups. The result suggests that it could serve as a potent insect repellent against vectors of disease. Globally, C. citratus is renowned for its therapeutic values. Above and beyond, due to its user- as well as environmental-friendly nature, it should be promoted among the marginalized populations in order to reduce man-vector contact. In addition, this appropriate strategy affords the opportunity to minimize chemical repellent usage and the risks associated with adverse side effects. At the end of the day, traditionally used plant-based insect repellents could be viable safer alternative sources for chemical insect repellents.

  10. Can topical insect repellents reduce malaria? A cluster-randomised controlled trial of the insect repellent N,N-diethyl-m-toluamide (DEET in Lao PDR.

    Directory of Open Access Journals (Sweden)

    Vanessa Chen-Hussey

    Full Text Available BACKGROUND: Mosquito vectors of malaria in Southeast Asia readily feed outdoors making malaria control through indoor insecticides such as long-lasting insecticidal nets (LLINs and indoor residual spraying more difficult. Topical insect repellents may be able to protect users from outdoor biting, thereby providing additional protection above the current best practice of LLINs. METHODS AND FINDINGS: A double blind, household randomised, placebo-controlled trial of insect repellent to reduce malaria was carried out in southern Lao PDR to determine whether the use of repellent and long-lasting insecticidal nets (LLINs could reduce malaria more than LLINs alone. A total of 1,597 households, including 7,979 participants, were recruited in June 2009 and April 2010. Equal group allocation, stratified by village, was used to randomise 795 households to a 15% DEET lotion and the remainder were given a placebo lotion. Participants, field staff and data analysts were blinded to the group assignment until data analysis had been completed. All households received new LLINs. Participants were asked to apply their lotion to exposed skin every evening and sleep under the LLINs each night. Plasmodium falciparum and P. vivax cases were actively identified by monthly rapid diagnostic tests. Intention to treat analysis found no effect from the use of repellent on malaria incidence (hazard ratio: 1.00, 95% CI: 0.99-1.01, p = 0.868. A higher socio-economic score was found to significantly decrease malaria risk (hazard ratio: 0.72, 95% CI: 0.58-0.90, p = 0.004. Women were also found to have a reduced risk of infection (hazard ratio: 0.59, 95% CI: 0.37-0.92, p = 0.020. According to protocol analysis which excluded participants using the lotions less than 90% of the time found similar results with no effect from the use of repellent. CONCLUSIONS: This randomised controlled trial suggests that topical repellents are not a suitable intervention in addition to

  11. 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.

  12. 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...

  13. 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

  14. 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.

  15. 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.

  16. 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

  17. 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

  18. 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

  19. Buckling analysis of thin-walled members using the spline finite member element method%薄壁杆件稳定分析的样条有限杆元法

    Institute of Scientific and Technical Information of China (English)

    辛克贵; 姜美兰

    2001-01-01

    根据势能驻值原理,提出在横向荷载作用下薄壁杆件稳定分析的样条有限杆元法。方法采用转换B3样条函数模拟杆件横截面的翘曲位移场,并考虑了杆壁中面上剪切变形的影响,能很好地描述剪力滞后现象。适用于任意横截面形状和任意边界条件的薄壁杆件,为高层建筑和桥梁结构的稳定分析提供了可靠而有效的分析方法。文中讨论了横向荷载作用下具有不同边界条件的工字型薄壁梁的屈曲分析。数值算例的结果表明了方法的灵活性、精确性和有效性。%The displacement variational principle was used to develop thespline finite member element method for buckling analysis of thin-walled members with shear lag effect. A transformed B3 spline function was used to simulate the warping displacements along the cross section of the thin-walled members. The proposed method is applicable to thin-walled members of any cross section with any boundary condition. The method was evaluated by studying the elastic modes of I-beams subjected to various loading conditions and different boundary conditions. The versatility, accuracy and efficiency of the proposed method compares well with classical theory.

  20. 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.

  1. 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

  2. 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

  3. 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.

  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. Preliminary study on mosquito repellent and mosquitocidal activities of Ocimum gratissimum (L. grown in eastern Nigeria

    Directory of Open Access Journals (Sweden)

    Evangeline T. Oparaocha

    2010-03-01

    Full Text Available Background & objectives: The study examined the mosquito-repellent and mosquitocidal activitiesof the volatile oil of Ocimum gratissimum at three different locations (World Bank Estate, Ihitteand Umuekunne in Imo State, eastern Nigeria, with the purpose of sourcing for mosquito repellentthat is cheap, abundant, environment and user-friendly.Methods: Four different lotions; 20% (v/v and 30% (v/v concentrations each of the extractedvolatile oil in two natural oil bases (olive and palm kernel were made and six volunteered humanbaits were used to evaluate the mosquito repellent and mosquitocidal activities of the stock materialsat the three different centres from September to November 2008.Results: Topical application of each of the four different lotions significantly (p <0.05 reduced thebiting rate of mosquitoes in all the three locations tested. The 30% (v/v concentration in olive oilbase exhibiting highest average percentage repellencies of 97.2, 95.7 and 96.3% at World BankEstate, Ihitte and Umuekunne centres respectively while the 20% (v/v concentration in palmkernel oil base had the least repellency of 36.3, 41.6 and 36.3%, respectively. The other twoformulations had values ranging from 67.8 to 80% in the three locations. The 30% (v/vconcentration in both olive and palm kernel oil bases afforded all night protection against mosquitobites in all the centres, and demonstrated fast knockdown and paralyzing effect on few mosquitoesat the urban centre (World Bank Estate.Interpretation & conclusion: The study confirms that O. gratissimum grown in eastern Nigeriahas mosquito-repellent and mosquitocidal potentials and the formulations could be used to reducehuman-mosquito contacts and hence mosquito-borne diseases and irritations caused by their bites.

  6. Evaluation of herbal essential oil as repellents against Aedes aegypti (L.) and Anopheles dirus Peyton & Harrion

    Institute of Scientific and Technical Information of China (English)

    Duangkamon Sritabutra; Mayura Soonwera; Sirirat Waltanachanobon; Supaporn Poungjai

    2011-01-01

    Objective: To investigate the repellent activity of herbal essential oils from garlic (Allium sativum), clove (Syzygium aromaticum), lemon grass (Cybopogon citratus), citronella grass (Cymbopogon nardus), peppermint (Mentha piperita), eucalyptus (Eucalyptus globulus), orange (Citrus sinensis) and sweet basil (Ocimum basilicum) and their combinations against Aedes aegypti (Ae. aegypti) (L.) and Anopheles dirus (An. dirus) Peyton & Harrion under laboratory conditions.Methods:In laboratory condition, 0.1 mL of each essential oil was applied to 3-10 cm of exposed area on a volunteer’s forearm. The test was carried out every 30 min until fewer than two mosquitoes bit or land during the 3 min study period and then the repellency test was stopped.Results:Essential oil from lemon grass exhibited protection against biting from two mosquito species, for Ae. aegypti [(98.66±11.56) min protection time and 0.97% biting rate] and for An. dirus [(98.00±15.28) min protection time and 0.80% biting rate]. The combinations from eucalyptus oil and sweet basil oil were effective as repellents and feeding deterrents against Ae. aegypti [(98.87±10.28) min protection time and 0.90% biting rate] and An. dirus [(210±10.70) min protection time and 0.93% biting rate]. All herbal repellents exhibited the period of protection time against Ae. aegypti which was lower than 120 min. Conlussions: It can be concluded that oils of lemon grass and combination from eucalyptus-sweet basil are the most effective in repellent activity.

  7. Development of surfaces repelling negatively buoyant solid particles

    Science.gov (United States)

    Semmler, Carina; Alexeev, Alexander

    2011-03-01

    Using a hybrid computational method that integrates the lattice Boltzmann model for fluid dynamics and the lattice spring model for solids, we examine the motion of negatively buoyant solid microparticles in shear flow near a solid wall decorated with regularly distributed rigid posts. The posts are arranged in a square pattern and tilted relative to the flow direction. We show that when rigid posts are tilted against flow, secondary flows emerge that prevent the deposition of suspended particles on the solid surface. We probe the effect of post geometry on the development of secondary flows and identify the optimal post architecture in terms of the mass of levitated solid particles. Our results are useful for designing anti-fouling surfaces that repel colloidal particles carried by fluid.

  8. 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.

  9. 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.

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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.

  15. Prevalence and determinants of the use of self-tests by members of the public: a mixed methods study

    Directory of Open Access Journals (Sweden)

    Wilson Sue

    2006-07-01

    Full Text Available Abstract Background Self-tests can be used by members of the public to diagnose conditions without involving a doctor, nurse or other health professional. As technologies to design and manufacture diagnostic tests have developed, a range of self-tests have become available to the public to buy over-the-counter and via the Internet. This study aims to describe how many people have used self-tests and identify factors associated with their use. Methods A postal questionnaire will elicit basic information, including sociodemographic characteristics, and whether the person has used or would use specified self-tests. Consent will be sought to recontact people who want to participate further in the study, and interviews and focus groups will be used to develop hypotheses about factors associated with self-test use. These hypotheses will be tested in a case-control study. An in-depth questionnaire will be developed incorporating the identified factors. This will be sent to: people who have used a self-test (cases; people who have not used a self-test but would use one in the future (controls; and people who have not used and would not use a self-test (controls. Logistic regression analysis will be used to establish which factors are associated with self-test use. Discussion Self-tests do have potential benefits, for example privacy and convenience, but also potential harms, for example delay seeking treatment after a true negative result when the symptoms are actually due to another condition. It is anticipated that the outcomes from this study will include recommendations about how to improve the appropriate use of self-tests and existing health services, as well as information to prepare health professionals for patients who have used self-tests.

  16. 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.

  17. Identifying the effective concentration for spatial repellency of the dengue vector Aedes aegypti

    Directory of Open Access Journals (Sweden)

    Achee Nicole

    2012-12-01

    Full Text Available Abstract Background Current efforts are underway to quantify the chemical concentration in a treated air space that elicits a spatial repellent (deterrent response in a vector population. Such information will facilitate identifying the optimum active ingredient (AI dosage and intervention coverage important for the development of spatial repellent tools – one of several novel strategies being evaluated for vector-borne disease control. This study reports initial findings from air sampling experiments conducted under field conditions to describe the relationship between air concentrations of repellent AIs and deterrent behavior in the dengue vector, Aedes aegypti. Methods Air samples were taken inside and outdoors of experimental huts located in Pu Tuey Village, Kanchanaburi Province, Thailand in conjunction with mosquito behavioral evaluations. A mark-release-recapture study design using interception traps was used to measure deterrency of Ae. aegypti against 0.00625% metofluthrin coils and DDT-treated fabric (2g/m2 within separate experimental trials. Sentinel mosquito cohorts were positioned adjacent to air sampling locations to monitor knock down responses to AI within the treated air space. Air samples were analyzed using two techniques: the U.S. Environmental Protection Agency (USEPA Compendium Method TO-10A and thermal desorption (TD. Results Both the USEPA TO-10A and TD air sampling methods were able to detect and quantify volatized AIs under field conditions. Air samples indicated concentrations of both repellent chemicals below thresholds required for toxic responses (mortality in mosquitoes. These concentrations elicited up to a 58% and 70% reduction in Ae. aegypti entry (i.e., deterrency into treated experimental huts using metofluthrin coils and DDT-treated fabric, respectively. Minimal knock down was observed in sentinel mosquito cohorts positioned adjacent to air sampling locations during both chemical evaluations. Conclusions

  18. 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...

  19. 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.

  20. 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.

  1. 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.

  2. Identifying the effective concentration for spatial repellency of the dengue vector Aedes aegypti.

    Science.gov (United States)

    Achee, Nicole; Masuoka, Penny; Smith, Philip; Martin, Nicholas; Chareonviryiphap, Theeraphap; Polsomboon, Suppaluck; Hendarto, Joko; Grieco, John

    2012-12-28

    Current efforts are underway to quantify the chemical concentration in a treated air space that elicits a spatial repellent (deterrent) response in a vector population. Such information will facilitate identifying the optimum active ingredient (AI) dosage and intervention coverage important for the development of spatial repellent tools--one of several novel strategies being evaluated for vector-borne disease control. This study reports initial findings from air sampling experiments conducted under field conditions to describe the relationship between air concentrations of repellent AIs and deterrent behavior in the dengue vector, Aedes aegypti. Air samples were taken inside and outdoors of experimental huts located in Pu Tuey Village, Kanchanaburi Province, Thailand in conjunction with mosquito behavioral evaluations. A mark-release-recapture study design using interception traps was used to measure deterrency of Ae. aegypti against 0.00625% metofluthrin coils and DDT-treated fabric (2g/m2) within separate experimental trials. Sentinel mosquito cohorts were positioned adjacent to air sampling locations to monitor knock down responses to AI within the treated air space. Air samples were analyzed using two techniques: the U.S. Environmental Protection Agency (USEPA) Compendium Method TO-10A and thermal desorption (TD). Both the USEPA TO-10A and TD air sampling methods were able to detect and quantify volatized AIs under field conditions. Air samples indicated concentrations of both repellent chemicals below thresholds required for toxic responses (mortality) in mosquitoes. These concentrations elicited up to a 58% and 70% reduction in Ae. aegypti entry (i.e., deterrency) into treated experimental huts using metofluthrin coils and DDT-treated fabric, respectively. Minimal knock down was observed in sentinel mosquito cohorts positioned adjacent to air sampling locations during both chemical evaluations. This study is the first to describe two air sampling

  3. 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.

  4. 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

  5. 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.

  6. 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

  7. 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....

  8. Repellent activity of desiccant dusts and conidia of the entomopathogenic fungus Beauveria bassiana when tested against poultry red mites (Dermanyssus gallinae) in laboratory experiments.

    Science.gov (United States)

    Kilpinen, Ole; Steenberg, Tove

    2016-11-01

    Desiccant dusts and entomopathogenic fungi have previously been found to hold potential against the poultry red mite, which is an important pest in egg production and notoriously difficult to control. Both control agents may cause repellence in other arthropods and potentially also influence control levels adversely when used against the poultry red mite. Five desiccant dust products with good efficacy against the poultry red mite Dermanyssus gallinae caused avoidance behavior in mites when tested in bioassays. The repellent activity was correlated with efficacy, which was found to depend on both dose and relative humidity (RH). However, one desiccant dust was significantly less repellent compared to other dusts with similar levels of efficacy. Further, dry conidia of the fungus Beauveria bassiana were also shown to be repellent to poultry red mites, both when applied on its own and when admixed with a low dose of the desiccant dust Diamol. The pick-up of desiccant dust particles and fungus conidia from treated surfaces by mites did not differ depending on RH, whereas the overall efficacy of the two control agents were significantly higher at 75 than at 85 % RH. In addition, the combined effect of the two substances was synergistic when tested in a bioassay where mites could choose whether to cross a treated surface. This is the first time a member of Acari has been shown to be repelled by desiccant dusts and by conidia of an entomopathogenic fungus.

  9. 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 ...

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Prevention of infectious tick-borne diseases in humans: Comparative studies of the repellency of different dodecanoic acid-formulations against Ixodes ricinus ticks (Acari: Ixodidae

    Directory of Open Access Journals (Sweden)

    Dautel Hans

    2008-04-01

    Full Text Available Abstract Background Ticks of the species Ixodes ricinus are the main vectors of Lyme Borreliosis and Tick-borne Encephalitis – two rapidly emerging diseases in Europe. Repellents provide a practical means of protection against tick bites and can therefore minimize the transmission of tick-borne diseases. We developed and tested seven different dodecanoic acid (DDA-formulations for their efficacy in repelling host-seeking nymphs of I. ricinus by laboratory screening. The ultimately selected formulation was then used for comparative investigations of commercially available tick repellents in humans. Methods Laboratory screening tests were performed using the Moving-object (MO bioassay. All test formulations contained 10% of the naturally occurring active substance DDA and differed only in terms of the quantitative and qualitative composition of inactive ingredients and fragrances. The test procedure used in the human bioassays is a modification of an assay described by the U.S. Environmental Protection Agency and recommended for regulatory affairs. Repellency was computed using the equation: R = 100 - NR/N × 100, where NR is the number of non-repelled ticks, and N is the respective number of control ticks. All investigations were conducted in a controlled laboratory environment offering standardized test conditions. Results All test formulations strongly repelled nymphs of I. ricinus (100-81% protection as shown by the MO-bioassay. The majority of ticks dropped off the treated surface of the heated rotating drum that served as the attractant (1 mg/cm2 repellent applied. The 10% DDA-based formulation, that produced the best results in laboratory screening, was as effective as the coconut oil-based reference product. The mean protection time of both preparations was generally similar and averaged 8 hours. Repellency investigations in humans showed that the most effective 10% DDA-based formulation (~1.67 mg/cm2 applied strongly avoided the

  16. Repellent activity of herbal essential oils against Aedes aegypti (Linn. and Culex quinquefasciatus (Say.

    Directory of Open Access Journals (Sweden)

    Duangkamon Sritabutra

    2013-08-01

    Full Text Available Objective: To determine the mosquito repellent activity of herbal essential oils against female Aedes aegypti and Culex quinquefasciatus. Methods: On a volunteer’s forearm, 0.1 mL of each essential oil was applied to 3 cm伊10 cm of exposed skin. The protection time was recorded for 3 min after every 30 min. Results: Essential oil from clove oil in olive oil and in coconut oil gave the longest lasting period of 76.50 min and 96.00 min respectively against Aedes aegypti. The citronella grass oil in olive oil, citronella grass oil in coconut oil and lemongrass oil in coconut oil exhibited protection against Culex quinquefasciatus at 165.00, 105.00, and 112.50 min respectively. Conclusions: The results clearly indicated that clove, citronella and lemongrass oil were the most promising for repellency against mosquito species. These oils could be used to develop a new formulation to control mosquitoes.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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

  3. Use of chemosensory cues as repellents for sea lamprey: Potential directions for population management

    Science.gov (United States)

    Imre, I.; Brown, G.E.; Bergstedt, R.A.; McDonald, R.

    2010-01-01

    Sea lamprey invaded the Great Lakes in the early 20th century and caused an abrupt decline in the population densities of several native fish species. The integrated management of this invasive species is composed of chemical (lampricide) applications, low-head barrier dams, adult trapping and sterile male release. Recently, there has been an increased emphasis on the development of control methods alternative to lampricide applications. We propose as an alternative-control method the use of chemosensory cues as repellents for sea lamprey population management. Based on the available evidence at this time, we suggest that injury-released chemical alarm cues show promise as repellents for sea lamprey and further research should be directed at determining whether sea lamprey show an avoidance response to these types of chemosensory cues. From a management perspective, these chemosensory cues could be used to restrict sea lamprey access to spawning grounds. Repellents could also be used together with attractants like sex pheromones to manipulate sea lamprey behavior, similar to the "push-pull" strategies utilized with insect pests. ?? 2010 Elsevier B.V.

  4. 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.

  5. 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.

  6. The impact of individual ability, favorable team member scores, and student perception of course importance on student preference of team-based learning and grading methods.

    Science.gov (United States)

    Su, Allan Yen-Lun

    2007-01-01

    This study explores the impact of individual ability and favorable team member scores on student preference of team-based learning and grading methods, and examines the moderating effects of student perception of course importance on student preference of team-based learning and grading methods. The author also investigates the relationship between student perception of course importance and their responses to social loafing. Results indicate that individual ability on the preference of team-based learning was affected by the three levels of favorable team member scores. For students with a low level of individual ability, the preference for team-based learning was significant among students with each of three levels of favorable team member scores (p team-based learning and grading methods was not significant (p > .05). The findings also reveal a negative correlation between student perception of course importance and their responses to social loafing (p team member scores in the team selection process to promote student attitude toward team-based learning.

  7. 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

  8. 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.

  9. 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

    , and not affected by fire during last 50 years. A meteorological station was installed to register rainfalls. Every month, during one complete hydrological year, water repellency was measured using the Water Drop Penetration Time (WDPT) technique. The method was applied on soil covered by Cistus monspeliensis shrub and on bare soil. Bare soil was covered by annual plants during the rainy season. The procedure was applied on smoothed horizontal soil surfaces of in situ undisturbed soils after removal of litter and organic material carefully. A total of 192 experiments were carried out under shrub and on bare soil respectively. Following a widely used classification, water repellency was classified in: WDPTs≤5 s wettable soil, 5-60 s as slight, 60-600 s as strong, 600-3600 s as severe, and >3600 s as extreme water repellency. Likewise, soil water content was also sampled monthly by means of the gravimetric method coinciding with the WDPT test. The results showed a higher water repellency under Cistus monspeliensis than under bare soil in general. There was a direct relation between the temporal variability of rainfall and soil water content and water repellency. This influence was more evident in the case of the soil under Cistus monspeliensis due to it is a vegetal specie that secretes organic substances triggering hydrophobity in soils. Nevertheless, the water repellency could become severe in bare soil when soil water content was lesser than 0.05 cm3 cm-3. Summary, the results indicated that rainfalls and thus soil water content became controlling factors of water repellency at the study site constituting runoff factors all of them.

  10. 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.

  11. 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.

  12. 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

  13. Plant products used as mosquito repellents in Guinea Bissau, West Africa.

    Science.gov (United States)

    Pålsson, K; Jaenson, T G

    1999-01-15

    By standardized interviews of people in 23 rural villages, in the Oio region of Guinea Bissau, we collected data on which plant species and plant derived products or methods people use to reduce mosquito biting activity. The following plants were used to reduce numbers of mosquitoes indoors at night: fresh or smouldering Hyptis suaveolens Poit. (Lamiaceae), smoke of the bark of Daniellia oliveri Rolfe (Caesalpiniaceae), smoke of the infructescence of Elaeis guineensis Jacq. (Arecaceae), smoke of the seed capsules of Parkia biglobosa (Jacq.) Benth. (Mimosaceae), smoke of the leaves of Azadirachta indica A.Juss. (Meliaceae) and Eucalyptus sp. (Myrtaceae), fresh Ocimum canum Sims (Lamiaceae), and fresh Senna occidentalis (L.) Link (Caesalpiniaceae). In two field experiments we estimated the 'repellent activity' of certain of these plants and compared their efficacies with those of two commercially available mosquito repellents, i.e. 'positive' controls. In the first experiment we tested: smouldering H. suaveolens (85.4% repellency); fresh H. suaveolens (73.2%); burning of the bark of D. oliveri (74.7%); and smoke of the leaves of Eucalyptus (72.2%). In the second experiment we tested: smouldering H. suaveolens (83.6% repellency); fresh H. suaveolens (66.5%); burning of the bark of D. oliveri (77.9%); smoke of the leaves of A. indica (76.0%); smoke of the infructescence of E. guineensis (69.0%); fresh O. canum (63.6%); and fresh S. occidentalis; (29.4%). All the products tested, except S. occidentalis were significantly more effective than the negative control.

  14. 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.

  15. Insecticidal and repellence activity of the essential oil of Pogostemon cablin against urban ants species.

    Science.gov (United States)

    Albuquerque, Elânia L D; Lima, Janaína K A; Souza, Felipe H O; Silva, Indira M A; Santos, Abraão A; Araújo, Ana Paula A; Blank, Arie F; Lima, Rafaely N; Alves, Péricles B; Bacci, Leandro

    2013-09-01

    Ants are highly abundant in neotropical regions, with certain species adapted to the urban environment, where they can cause damage to human health. The main method for controlling ants consists of using organosynthetic insecticides, which are potentially toxic to the environment. Essential plant oils are considered a viable alternative to the use of conventional insecticides. In this study, we analyze the bioinsecticidal activity and repellence of patchouli essential oil (Pogostemon cablin) against three species of urban ants: Camponotus melanoticus, Camponotus novograndensis, and Dorymyrmex thoracicus. The chemical composition of the essential oil was analyzed by GC-MS and GC-FID. The major compounds were patchoulol (36.6%) followed by α-bulnesene (13.95%), and α-guaiene (11.96%). Toxicity and repellency bioassays were performed using the essential oil over the ants, and mortality evaluations were performed at 4, 24, and 48 h after performing the bioassays. Mortality percentage of the ants on 7 μg/mg was on average 84%. The essential oil of P. cablin displayed toxicity against all three species of urban ants, with the lowest LD₅₀ being observed for D. thoracicus (2.02 μg oil/mg insect) after 48 h of exposure compared to C. melanoticus (2.34 μg oil/mg insect) and C. novogranadensis (2.95 μg oil/mg insect). The essential oil of P. cablin was strongly repellent to the three species of ants in all concentrations tested (0.01% and 1% v/v). Considering the potential toxicity and repellency of the P. cablin essential oil to the urban ants, future studies could investigate the practical application of this oil to control of this insects. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. 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.

  17. 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.

  18. 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.

  19. Extreme Wetting-Resistant Multiscale Nano-/Microstructured Surfaces for Viscoelastic Liquid Repellence

    Directory of Open Access Journals (Sweden)

    Aoythip Chunglok

    2016-01-01

    Full Text Available We demonstrate exceptional wetting-resistant surfaces capable of repelling low surface tension, non-Newtonian, and highly viscoelastic liquids. Theoretical analysis and experimental result confirm that a higher level of multiscale roughness topography composed of at least three structural length scales, ranging from nanometer to supermicron sizes, is crucial for the reduction of liquid-solid adhesion hysteresis. With Cassie-Baxter nonwetting state satisfied at all roughness length scales, the surface has been proven to effectively repel even highly adhesive liquid. Practically, this high-level hierarchical structure can be achieved through fractal-like structures of silica aggregates induced by siloxane oligomer interparticle bridges. The induced aggregation and surface functionalization of the silica particles can be performed simultaneously within a single reaction step, by utilizing trifunctional fluoroalkylsilane precursors that largely form a disordered fluoroalkylsiloxane grafting layer under the presence of sufficient native moisture preadsorbed at the silica surface. Spray-coating deposition of a particle surface layer on a precoated primer layer ensures facile processability and scalability of the fabrication method. The resulting low-surface-energy multiscale roughness exhibits outstanding liquid repellent properties, generating equivalent lotus effect for highly viscous and adhesive natural latex concentrate, with apparent contact angles greater than 160°, and very small roll-off angles of less than 3°.

  20. A method of identifying and isolating a unique member of a multigene family: application to a trypanosome surface antigen gene.

    Science.gov (United States)

    Ruef, B J; Hecht, J H; Manning, J E

    1991-04-25

    A chimeric oligonucleotide was constructed using DNA sequences from two distal regions of a cDNA which encodes a major surface antigen (TSA-1) of Trypanosoma cruzi. Conditions were found that allowed the chimeric oligonucleotide to hybridize only to a 5.4 kb EcoRI fragment in a Southern blot of total genomic DNA. The 5.4 kb EcoRI genomic DNA fragment has previously been shown to be located at a telomeric site, thus the studies described here directly demonstrate that the TSA-1 gene is telomeric in location. It is also shown that the chimeric oligonucleotide can be used to selectively identify recombinant lambda phage which harbor the TSA-1 gene using standard library screening procedures. Since these studies demonstrate that a chimeric oligonucleotide can be used to identify in both Southern blots and library screens a single member among the more than sixty members of the TSA-1 gene family, it seems likely that chimeric oligonucleotides may be of general use in studies involving repetitive DNA sequence families.

  1. Comparative mosquito repellency of essential oils against Aedes aegypti (Linn.), Anopheles dirus (Peyton and Harrison) and Culex quinquefasciatus (Say)

    Institute of Scientific and Technical Information of China (English)

    Siriporn Phasomkusolsil; Mayura Soonwera

    2011-01-01

    Objective: To assess the repellency to female Aedes aegypti (Ae. aegypti), Anopheles dirus (An. dirus) and Culex quinquefasciatus (Cx. quinquefasciatus) of seven essential oils using two treatment methods. Methods: Topical applications of three dose concentrations (0.02, 0.10 and 0.21 mg/cm2) were made on the forearms of volunteers. Dose-response study and protection time study were employed in the experiment. Results: In the dose-response test, Cymbopogon citratus (C. citratus), Cymbopogon nardus (C. nardus), Syzygium aromaticum (S. aromaticum) and Ocimum basilicum (O. basilicum) exhibited a high repellency against Ae. aegypti with ED50 at < 0.045 mg/cm2, whereas C. citratus, C. nardus and S. aromaticum showed repellency against An. dirus with ED50 at <0.068 mg/cm2. Furthermore, the essential oils of C. citratus, C. nardus, S. aromaticum, O.basilicum and Cananga odorata gave strong effective dose (ED 50) values at <0.003 mg/cm2 when tested against Cx. quinquefasciatus. For testing by arm in cage method, at 0.21 mg/cm2, protection time of C. citratus gave the longest lasting period against three mosquito species, 72 min for Ae. aegypti, 132 min for An. dirus and 84 min for Cx. quinquefasciatus. In addition, the two essential oils exhibited moderate repellency against Ae. aegypti, An. dirus and Cx. quinquefasciatus, at 60, 90 and 78 min with C. nardus, and 54, 96 and 72 min with S. aromaticum, respectively. Conclusions: The percentage repellency increased when the concentration of essential oils increased. In contrast, biting rates decreased when the concentration of essential oils increased.C. citratus exhibited high efficiency for the protection time and the percentage of biting deterrent against all of 3 mosquito species.

  2. 蟑螂驱避剂的研究现状%The research status of cockroach repellent

    Institute of Scientific and Technical Information of China (English)

    林雅红; 肖义军

    2016-01-01

    蟑螂是一类常见的病媒昆虫,目前主要采取化学杀虫剂的办法来防治,但存在污染环境和抗药性问题,在某些场合还存在不适合使用杀虫剂的问题。采用驱避剂驱赶昆虫来防治蟑螂是一种值得探索的方法。驱避剂是一类能引起害虫产生忌避作用的化学物质,驱避剂的使用历史悠久。文中就近年来蟑螂驱避剂的研究现状进行综述。%Cockroaches are a class of common insect vectors. At present, chemical pesticides is a mainly measure to combat with cockroaches, but environmental pollution and resistance are the problems that difficult to solve. Some occasions there is a problem for the use of pesticides which is not allowed. Driven by the use of insect repellents to control cockroaches is a method worth explor-ing. Repellents are a class chemical substances that can cause pest shelter, and the use of repellent has a long history. This paper summarizes recent research on the status of the cockroach repellent.

  3. Larvicidal and repellent activity of tetradecanoic acid againstAedes aegypti (Linn.) andCulex quinquefasciatus (Say.) (Diptera:Culicidae)

    Institute of Scientific and Technical Information of China (English)

    Sivakumar R; Jebanesan A; Govindarajan M; Rajasekar P

    2011-01-01

    Objective:To investigate the larvicidal and repellent efficacy of tetradecanoic acid against Aedes aegypti (Ae. aegypti) L. andCulex quinquefasciatus (Cx. quinquefasciatus) Say (Diptera: Culicidae).Methods: Larvicidal efficacy of tetradecanoic acid was tested at various concentrations against the early third instar larvae of Ae. aegypti andCx. quinquefasciatus. The repellent activity was determined against two mosquito species at three concentrations viz.,1.0,2.5 and5.0 ppm under the laboratory conditions.Results: The tetradecanoic acid was found to be more effective againstCx. quinquefasciatus thanAe. aegypti larvae. TheLC50values were14.08 ppm and25.10 ppm, respectively. Tetradecanoic acid showed lesser repellency againstAe. aegypti andCx. quinquefasciatus. The highest repellency was observed in higher concentration of5.0 mg/cm2provided100% protection up to60 and 90 min againstAe. aegypti andCx. quinquefasciatusrespectively.Conclusions: From the results it can be concluded the tetradecanoic acid is a potential for controlling Cx. quinquefasciatus andAe. aegypti mosquitoes.

  4. Encapsulation of Citronellal from Citronella Oil using β-Cyclodextrin and Its Application as Mosquito (Aedes aegypti) Repellent

    Science.gov (United States)

    Pujiastuti, A.; Cahyono, E.; Sumarni, W.

    2017-04-01

    Mosquito (Aedes aegypti) is a threat to human health due to its capability to spread dengue fever. Citronellal in citronella oil is one ofnatural active compound that has repellent activity. Essential oil is a sensitive material whichiseasy to degrade. Encapsulation is coating technology use to avoid essential oil from degradation problems. β-Cyclodextrin is frequently used as acoating material in encapsulation. The aims of this study wereto prepare the citronellal encapsulation and to evaluate its control-released and repellency. In this study, encapsulated citronellal was prepared using 83.65% citronellal and encapsulation were prepared with the theemulsion-based method and dried using freeze-dryer. The best-controlled release was performed in citronellal encapsulate with a weight ratio of 1:1 (citronellal : β-Cyclodextrin). The morphology of encapsulated citronellal was analyzed using SEM. SEM result showed it has three dimensions random shape and agglomerate in some part with thebrighter spot. Citronellal encapsulate showed the highest repellent effect at 84,67% for 5 minutes in mosquito repellency test although it has lower result compared with citronellal inliquid form.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. Family members' experiences of autopsy

    NARCIS (Netherlands)

    Oppewal, F; Meyboom-de Jong, B

    2001-01-01

    Background. The experiences of family members will teach us how to handle an autopsy, the ultimate quality assessment tool. Objective. The aim of this study was to determine surviving family members' experience of autopsy. Method. Seven GPs were asked to approach surviving family members of autopsie

  11. Family members' experiences of autopsy

    NARCIS (Netherlands)

    Oppewal, F; Meyboom-de Jong, B

    Background. The experiences of family members will teach us how to handle an autopsy, the ultimate quality assessment tool. Objective. The aim of this study was to determine surviving family members' experience of autopsy. Method. Seven GPs were asked to approach surviving family members of

  12. 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...

  13. 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.

  14. A Novel in vitro Bioassay to Explore the Repellent Effects of Compounds Against Mosquito Aedes aegypti (Diptera: Culicidae).

    Science.gov (United States)

    Rehman, Junaid U; Tabanca, Nurhayat; Khan, Ikhlas A

    2016-01-01

    Mosquitoes are vectors for many pathogens resulting in many deaths of humans. Repellents play an important role in reducing mosquito bites and the spread of mosquito-borne diseases. Currently, Klun & Debboun (K & D) and human-arm-based bioassay systems are used to identify repellent properties of compounds, extracts, and essential oils. Risks involved with human-arm-based systems are allergic reactions and limited replicates. We are reporting an in vitro bioassay method “NCNPR repellent bioassay (NCNPR-RB)” that can closely simulate the results of the cloth patch bioassay system used to determine repellency against mosquitoes. The NCNPRRB method uses heat to attract mosquito and edible collagen sheets as an alternate to human skin. Multiple plant compounds with documented repellency were tested. DEET (N,N-diethyl-3-methylbenzamide) was used as a positive control. Treatments were prepared in EtOH and applied in dosages ranging from 0.011–1.5mg/cm2 to a 20-cm2 collagen sheet. The number of mosquitoes commencing to bite per probe was recorded visually for 1 min. The minimum effective dosage (mg/cm2) of compounds: DEET (0.021), carvacrol (0.011), thymol (0.013), undecanoic acid (0.023), thymol methyl ether (0.269), and 2-nonanone (>0.375 mg/cm2) determined in NCNPRRB were similar to those reported in literature using a cloth patch bioassay system. The NCNPR-RB can be used to screen compounds with reasonable reproducibility of the data at a faster rate than the cloth patch bioassay, which involves the use of human subjects.

  15. 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.

  16. 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...

  17. 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...

  18. 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.

  19. 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

  20. 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

  1. 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

  2. Larvicidal and repellent properties of some essential oils against Culex tritaeniorhynchus Giles and Anopheles subpictus Grassi (Diptera: Culicidae).

    Science.gov (United States)

    Govindarajan, Marimuthu

    2011-02-01

    To investigate the larvicidal and repellent properties of essential oils from various parts of four plant species Cymbopogan citrates, Cinnamomum zeylanicum, Rosmarinus officinalis and Zingiber officinale against Culex tritaeniorhynchus (Cx. tritaeniorhynchus) and Anopheles subpictus (An. subpictus). Essential oils were obtained by hydro-distillation method. The mosquitoes were reared in the vector control laboratory and twenty five late third instar larvae of Cx. tritaeniorhynchus and An. subpictus were exposed to based on the wide range and narrow range test, essential oil tested at various concentrations ranging from 25 to 250 ppm. The larval mortality was observed after 24 h under the laboratory conditions. The repellent efficacy was determined against two mosquito species at three concentrations viz., 1.0, 2.5 and 5.0 mg/cm(2) under laboratory conditions. Results showed all the four plant essential oil produced significant larval mortality against two mosquito species. However, the highest larvicidal activity was observed in the essential oil from Zingiber officinale against Cx. tritaeniorhynchus and An. subpictus with the LC(50) and LC(90) values as 98.83, 57.98 ppm and 186.55, 104.23 ppm, respectively. All the four essential oil shows significant repellency against Cx. tritaeniorhynchus than An. subpictus. Among four essential oil tested the highest repellency was observed in Zingiber officinale, a higher concentration of 5.0 mg/cm(2) provided 100% protection up to 150 and 180 min against Cx. tritaeniorhynchus and An. subpictus, respectively. In this work, it can be concluded that four essential oils which were distilled from Cymbopogan citrates, Cinnamomum zeylanicum, Rosmarinus officinalis and Zingiber officinale showed promising larvicidal and repellent agent against Cx. tritaeniorhynchus and An. subpictus. Copyright © 2011 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

  3. Synergy between repellents and non-pyrethroid insecticides strongly extends the efficacy of treated nets against Anopheles gambiae

    Directory of Open Access Journals (Sweden)

    N'Guessan Raphaël

    2007-03-01

    Full Text Available Abstract Background To manage the kdr pyrethroid-resistance in Anopheline malaria vectors, new compounds or new strategies are urgently needed. Recently, mixing repellents (DEET and a non-pyrethroid insecticide (propoxur was shown to be as effective as deltamethrin, a standard pyrethroid, under laboratory conditions, because of a strong synergy between the two compounds. In the present study, the interactions between two repellents (DEET and KBR 3023 and a non-pyrethroid insecticide (pyrimiphos methyl or PM on netting were investigated. The residual efficacy and the inhibition of blood feeding conferred by these mixtures were assessed against Anopheles gambiae mosquitoes. Methods DEET and KBR 3023 were mixed with pyrimiphos methyl (PM, a organophosphate (OP insecticide. The performance of mono- and bi-impregnated nets against adult mosquitoes was assessed using a miniaturized, experimental hut system (laboratory tunnel tests that allows expression of behavioural responses to insecticide, particularly the mortality and blood feeding effects. Results Both mixtures (PM+DEET and PM+KBR3023 induced 95% mortality for more than two months compared with less than one week for each compound used alone, then reflecting a strong synergy between the repellents and PM. A similar trend was observed with the blood feeding rates, which were significantly lower for the mixtures than for each component alone. Conclusion Synergistic interactions between organophosphates and repellents may be of great interest for vector control as they may contribute to increase the residual life of impregnated materials and improve the control of pyrethroid-resistance mosquitoes. These results prompt the need to evaluate the efficacy of repellent/non-pyrethroid insecticide mixtures against field populations of An. gambiae showing high level of resistance to Ops and pyrethroids.

  4. Larvicidal and repellent properties of Adansonia digitata against medically important human malarial vector mosquito Anopheles stephensi (Diptera: Culicidae

    Directory of Open Access Journals (Sweden)

    K. Krishnappa , K. Elumalai , S. Dhanasekaran & J. Gokulakrishnan

    2012-06-01

    Full Text Available Background & objectives: Development of plant-based alternative compounds for mosquito control has gainedimportance now-a-days, in view of increasing resistance in mosquito vectors to existing insecticides. The larvicidaland repellent activities of benzene, chloroform, hexane and methanol leaf extracts of Indian medicinal plant,Adansonia digitata were investigated against malarial vector, Anopheles stephensi.Methods: In all, 25 III instar larvae of An. stephensi were exposed to various concentrations (30–180 mg/l in thelaboratory by using the standard protocol described by WHO (2005. The larvae were exposed for 24 h andmortalities were subjected to log-probit analysis. Repellent activity of crude leaf extract at the dosages of 2, 4and 6 mg/cm2 was evaluated in a net cage (45 × 30 × 45 cm containing 100 blood starved female mosquitoes ofAn. stephensi using the protocol of WHO (1996.Results: Preliminary phytochemical analysis of A. digitata showed the presence of triterpenoids and saponins.The LC50 and LC90 values of hexane, benzene, chloroform, and methanol extracts of A. digitata against An.stephensi larvae in 24 h were 111.32, 97.13, 88.55, 78.18 and 178.63, 176.19, 168.14, 155.42 mg/l, respectively.The repellent activity of methanol extract was found to be most effective and at higher concentration of 6mg/cm2 benzene, chloroform hexane and methanol extracts provided 100% protection up to 150, 180, 120 and210 min against An. stephensi, respectively.Conclusion: The preliminary study indicated that A. digitata showed larvicidal and repellent activities againstAn. stephensi and could be used for controlling mosquitoes. Further studies are indicated to purify the activecompounds from these plants for developing larvicide and repellents.

  5. 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

    . However, differences in evaporation rates were not significant between samples with different WR levels of persistence nor between samples with different initial water content. Our preliminary results indicated that soil WR is a mechanism which clearly contributes to the conservation of moisture in depth, making more sense of the hypothesis of a possible ecological strategy for plants. Keywords: Soil water repellency, hydrophobicity. References: Doerr, S.H., Shakesby, R.A., Walsh, R.P.D., 2000. Soil water repellency: its causes, characteristics and hydro-geomorphological significance. Earth-Sci. Rev. 51, 33-65. Robinson D.A., Lebron I., Ryel R.J., Jones S.B., 2010. Soil Water Repellency: A Method of Soil Moisture Sequestration in Pinyon-Juniper Woodland Soil Science Society of America Journal 74 (2), 624-634. Rodriguez-Iturbe, I., 2000. Ecohydrology: a hydrologic perspective of climate-soil-vegetation dynamics. Water Resour. Res., 36 (1), 3-9.

  6. "Stand by Me": A Mixed Methods Study of a Collegiate Marching Band Members' Intragroup Beliefs throughout a Performance Season

    Science.gov (United States)

    Matthews, Wendy K.

    2017-01-01

    The purpose of this mixed methods study was to investigate intragroup beliefs regarding participation in a National Collegiate Athletic Association (NCAA) Division II marching band throughout the university's American football season. Fifty-three undergraduates from an urban midwestern university elected one of two options: (1) focus group only or…

  7. 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

  8. Faculty Members' Perceived Experiences and Impact of Cyberbullying from Students at a Canadian University: A Mixed Methods Study

    OpenAIRE

    Blizard, Lida Marie

    2014-01-01

    This mixed methods study was conducted at a Canadian University in 2012, using an online survey and individual interviews to explore faculty members’ perceived experiences of having aggressive, intimidating, defaming, or threatening message(s) sent to them or about them by students via electronic media. Limited empirical research on this issue within the context of higher education led the researcher to draw from literature on workplace bullying, academic bullying, and K-12 sector cyberbullyi...

  9. Repellent effect of two kinds of phytochemicals on mouse%2种植物素对小鼠的驱避作用研究

    Institute of Scientific and Technical Information of China (English)

    钟平生; 谢彩玉; 张颂声; 郭国汉

    2011-01-01

    目的 研究2种植物素辣椒素和肉桂酰胺对小鼠的驱避效果.方法采用驱避率评价其驱避效果.结果辣椒素和肉桂酰胺均有很强的驱避效果,且随着作用时间的增长,驱避效果越强.投喂第1天,小鼠对1%、3%和5%辣椒素毒饵均有取食,驱避率分别为99.74%、98.66%、99.18%;第2天,小鼠仅取食少许5%辣椒素毒饵,驱避率为99.79%;第3~5天驱避率均达到100%;而8%辣椒素毒饵在5d内对小鼠的驱避率均达100%.肉桂酰胺各浓度毒饵在投喂第1天,小鼠均有取食,其中30%肉桂酰胺的驱避作用最强,驱避率为99.09%;第2天驱避率达100%的有25%和30%肉桂酰胺;在第3~5天中,除第3天5%肉桂酰胺外,其余处理的驱避率均达100%.结论在实际防鼠工作中,考虑到成本和驱避效果,可推荐使用1%辣椒素与8%肉桂酰胺.%Objective To study the repellent effect of two kinds of phytochemicals on mouse. Methods Assessing their repellent effect by the repellent rate. Results Capsaicinoids and cinnamide had strong repellent effects, and with the time growth, repellent rate got stronger. On the first day fed by 1% ,3% and 5% capsaicinoids, the repellent rate were 99.74% , 98.66% , 99. 18%. On the second day, the repellent rate on mouse fed by a little 5% capsaicinoids bait was 99.79% , and from the 3th to 5th day, the repellent rate had all grew to 100%. And the repellent rate to the mouse fed by 8% capsaicinoids bait always reached 100% in 5 days. On the first day fed by all kinds concentration of cinnamide, each group mouse had been fed by little bait, of which 30% cinnamide had the highest repellent rate( 99.09% ). On the second day, the repellent rate of 25% and 30% cinnamide all reached 100%. From the 3th to 5th day, except to the treat of 5% cinnamide on the third day, repellent rate of the others was 100%. Conclusion In practical rat proof, considering the costs and repellent effects, it is

  10. 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

  11. 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.

  12. 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

  13. 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...

  14. 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...

  15. 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,

  16. 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

  17. 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

  18. 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.

  19. 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.

  20. 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...

  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. 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.

  3. 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.

  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. 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.

  6. 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.

  7. Arsenic absorption by members of the Brassicacea family, analysed by neutron activation, k{sub 0}-method - preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Uemura, George; Matos, Ludmila Vieira da Silva; Silva, Maria Aparecida da; Ferreira, Alexandre Santos Martorano; Menezes, Maria Angela de Barros Correia [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN-CNEN/MG), Belo Horizonte, MG (Brazil)], e-mail: george@cdtn.br, e-mail: menezes@cdtn.br

    2009-07-01

    Natural arsenic contamination is a cause for concern in many countries of the world including Argentina, Bangladesh, Chile, China, India, Mexico, Thailand and the United States of America and also in Brazil, specially in the Iron Quadrangle area, where mining activities has been contributing to aggravate natural contamination. Brassicacea is a plant family with edible species (arugula, cabbage, cauliflower, cress, kale, mustard, radish), ornamental ones (alysssum, field pennycress, ornamental cabbages and kales) and some species are known as metal and metalloid accumulators (Indian mustard, field pennycress), like chromium, nickel, and arsenic. The present work aimed at studying other taxa of the Brassicaceae family to verify their capability in absorbing arsenic, under controlled conditions, for possible utilisation in remediation activities. The analytical method chosen was neutron activation analysis, k{sub 0} method, a routine technique at CDTN, and also very appropriate for arsenic studies. To avoid possible interference from solid substrates, like sand or vermiculite, attempts were carried out to keep the specimens in 1/4 Murashige and Skoog basal salt solution (M and S). Growth was stumped, plants withered and perished, showing that modifications in M and S had to be done. The addition of nickel and silicon allowed normal growth of the plant specimens, for periods longer than usually achieved (more than two months); yielding samples large enough for further studies with other techniques, like ICP-MS, and other targets, like speciation studies. The results of arsenic absorption are presented here and the need of nickel and silicon in the composition of M and S is discussed. (author)

  8. 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.

  9. 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.

  10. Direct functionalization of pristine single-walled carbon nanotubes by diazonium-based method with various five-membered S- or N- heteroaromatic amines

    Energy Technology Data Exchange (ETDEWEB)

    Leinonen, Heli; Lajunen, Marja, E-mail: marja.lajunen@oulu.fi [University of Oulu, Department of Chemistry (Finland)

    2012-09-15

    Reactivity of five-membered, variously substituted, heteroaromatic diazonium salts was studied toward pristine single-walled carbon nanotubes (SWCNTs), prepared by high-pressure CO conversion (HiPCO) method. Average size range of individual HiPCO SWCNTs was 0.8-1.2 nm (diameter) and 100-1,000 nm (length). Functionalizations were performed by a one-pot diazotization-dediazotization method with methyl-2-aminothiophene-3-carboxylate, 2-aminothiophene-3-carbonitrile, 2-aminoimidazole sulfate, or 3-aminopyrazole in acetic acid using sodium nitrite at room temperature or by heating. According to Raman and Fourier transform infrared spectroscopy, all used heterocyclic diazonium salts formed a covalent bond with SWCNTs and yielded new kinds of five-membered heterocycle-functionalized SWCNTs. Methyl-2-thiophenyl-3-carboxylate-functionalized SWCNTs formed a highly soluble, stable dispersion in tetrahydrofuran (THF), 3-pyrazoyl-functionalized SWCNTs in ethanol, and 2-imidazoyl- or 2-thiophenyl-3-carbonitrile-functionalized SWCNTs in ethanol and THF. The thermogravimetric analysis as well as energy-filtered transmission electron microscopy imaging of the products confirmed the successful functionalization of SWCNTs.

  11. Larvicidal and repellent properties of Adansonia digitata against medically important human malarial vector mosquito Anopheles stephensi (Diptera: Culicidae)

    OpenAIRE

    K. Krishnappa , K. Elumalai , S. Dhanasekaran & J. Gokulakrishnan

    2012-01-01

    Background & objectives: Development of plant-based alternative compounds for mosquito control has gainedimportance now-a-days, in view of increasing resistance in mosquito vectors to existing insecticides. The larvicidaland repellent activities of benzene, chloroform, hexane and methanol leaf extracts of Indian medicinal plant,Adansonia digitata were investigated against malarial vector, Anopheles stephensi.Methods: In all, 25 III instar larvae of An. stephensi were exposed to various concen...

  12. Screening for adulticidal activity against Anopheles arabiensis in ten plants used as mosquito repellent in South Africa

    OpenAIRE

    Mavundza, Edison J; Maharaj, Rajendra; Chukwujekwu, Jude C; Finnie, Jeffrey F.; Staden, Johannes Van

    2014-01-01

    Background Due to the development of resistance to synthetic insecticides, adverse effects to human health, non-target organisms and the environment, there is an urgent need to develop new insecticides, which are effective, safe, biodegrable and target-specific. This study was undertaken to evaluate the adulticidal activity of 10 plants used traditionally as mosquito repellents in South Africa. Methods The dried plant materials were extracted with dichloromethane (DCM) and ethanol (EtOH). The...

  13. Ethnobotanical knowledge on botanical repellents employed in the African region against mosquito vectors - A review.

    Science.gov (United States)

    Pavela, Roman; Benelli, Giovanni

    2016-08-01

    Mosquitoes (Diptera: Culicidae) represent a huge threat for millions of humans and animals worldwide, since they act as vectors for important parasites and pathogens, including malaria, filariasis and important arboviruses, such as dengue, West Nile and Zika virus. No vaccines or other specific treatments are available against the arboviruses transmitted by mosquitoes, and avoidance of mosquito bites remains the best strategy. African regions are usually hit most whose inhabitants are poor, and the use of repellent plants is the only efficient protection against vectors they have. Ethnobotanical knowledge of such plants and their use is usually passed on orally from one generation to another. However, it is also important to preserve this information in a written form, as well. Ethnobotanical research projects carried out in the regions of today's Ethiopia, South Africa, Nigeria, Kenya, and Tanzania indicate that the native inhabitants of the African study regions traditionally use 64 plant species, belonging to 30 families. Aromatic plants (i.e., Citrus spp., Eucalyptus spp., Lantana camara, Ocimum spp. and Lippia javanica) the most commonly used in all the study regions. Native people know three major methods of using repellent plants: (i) production of repellent smoke from burning plants, (ii) hanging plants inside the house or sprinkling leaves on the floor, (iii) the use of plant oils, juices from crushed fresh parts of the plants, or various prepared extracts applied on uncovered body parts. Overall, this review covers studies conducted only in a limited part of the African continent, highlighting the importance to undertake further research efforts to preserve the unique knowledge and traditions of the native tribes.

  14. High-throughput Identification of Bacteria Repellent Polymers for Medical Devices.

    Science.gov (United States)

    Venkateswaran, Seshasailam; Gwynne, Peter J; Wu, Mei; Hardman, Ailsa; Lilienkampf, Annamaria; Pernagallo, Salvatore; Blakely, Garry; Swann, David G; Bradley, Mark; Gallagher, Maurice P

    2016-11-05

    Medical devices are often associated with hospital-acquired infections, which place enormous strain on patients and the healthcare system as well as contributing to antimicrobial resistance. One possible avenue for the reduction of device-associated infections is the identification of bacteria-repellent polymer coatings for these devices, which would prevent bacterial binding at the initial attachment step. A method for the identification of such repellent polymers, based on the parallel screening of hundreds of polymers using a microarray, is described here. This high-throughput method resulted in the identification of a range of promising polymers that resisted binding of various clinically relevant bacterial species individually and also as multi-species communities. One polymer, PA13 (poly(methylmethacrylate-co-dimethylacrylamide)), demonstrated significant reduction in attachment of a number of hospital isolates when coated onto two commercially available central venous catheters. The method described could be applied to identify polymers for a wide range of applications in which modification of bacterial attachment is important.

  15. DEET, Active Substance Of Repellent That Effective And Safe For Travelers

    Directory of Open Access Journals (Sweden)

    Made Ika Lestari

    2013-10-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE Increased flow of tourism to the tropics and the changing patterns of vector-borne diseases require increased protection against insects. To prevent transmission of the disease is done several ways that increase self-protection by using mosquito repellent can protect travelers while outdoor activities. One option is active formula mosquito repellent DEET. The purpose of this paper is to determine the best dosage forms for travelers DEET., To determine the effectiveness and safety of DEET and to know the workings of the active ingredient DEET. The method of writing is the literature search through medical journals and articles. From the search was obtained, the most appropriate anti-mosquito travelers to use while on the move outdoors in the dosage form is DEET lotion applied to the skin as the most secure and durable because it does not easily evaporate. Mosquito repellent containing DEET has been proven effective and safe for use in adults, children, and pregnant women, but should still follow the instructions. The workings of the mosquito repellent DEET mosquito dispel is manipulating 1-Octen-3-ol used by mosquitoes to detect human presence. So ORN (olfactory receptor neurons in the mosquitoes can not respond anymore to the maximum, so that people avoid the bites nyamuk. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New

  16. Tick repellents and acaricides of botanical origin: a green roadmap to control tick-borne diseases?

    Science.gov (United States)

    Benelli, Giovanni; Pavela, Roman; Canale, Angelo; Mehlhorn, Heinz

    2016-07-01

    Arthropods are dangerous vectors of agents of deadly diseases, which may hit as epidemics or pandemics in the increasing world population of humans and animals. Among them, ticks transmit more pathogen species than any other group of blood-feeding arthropods worldwide. Thus, the effective and eco-friendly control of tick vectors in a constantly changing environment is a crucial challenge. A number of novel routes have been attempted to prevent and control tick-borne diseases, including the development of (i) vaccines against viruses vectored by ticks; (ii) pheromone-based control tools, with special reference to the "lure and kill" techniques; (iii) biological control programmes relying on ticks' natural enemies and pathogens; and (iv) the integrated pest management practices aimed at reducing tick interactions with livestock. However, the extensive employment of acaricides and tick repellents still remains the two most effective and ready-to-use strategies. Unfortunately, the first one is limited by the rapid development of resistance in ticks, as well as by serious environmental concerns. On the other hand, the exploitation of plants as sources of effective tick repellents is often promising. Here, we reviewed current knowledge concerning the effectiveness of plant extracts as acaricides or repellents against tick vectors of public health importance, with special reference to Ixodes ricinus, Ixodes persulcatus, Amblyomma cajennense, Haemaphysalis bispinosa, Haemaphysalis longicornis, Hyalomma anatolicum, Hyalomma marginatum rufipes, Rhipicephalus appendiculatus, Rhipicephalus (Boophilus) microplus, Rhipicephalus pulchellus, Rhipicephalus sanguineus and Rhipicephalus turanicus. Eighty-three plant species from 35 botanical families were selected. The most frequent botanical families exploited as sources of acaricides and repellents against ticks were Asteraceae (15 % of the selected studies), Fabaceae (9 %), Lamiaceae (10 %), Meliaceae (5 %), Solanaceae (6

  17. 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.

  18. 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

  19. Larvicidal, adulticidal, repellency and smoke toxic efficacy of Ficus krishnae against Anopheles stephensi Liston and Culex vishnui group mosquitoes

    Directory of Open Access Journals (Sweden)

    Koyel Mallick Haldar

    2014-02-01

    Full Text Available Objective: To establish the plant Ficus krishnae as potential antimosquito agent. Methods: Larvicidal and adulticidal efficacy of ethyl acetate and methanol extracts of leaves of Ficus krishnae were evaluated against 3rd instar larvae and adults of Anopheles stephensi and Culex vishnui group mosquito for 24 h. Smoke toxicity test along with test for repellency on adult forms of the two mosquitoes were performed by the methanol extract. Results: The mortality rate varies in a dose dependent characteristic. The tests for larvicidal and adulticidal activity with both the solvent extracts showed significant efficiencies against the mosquitoes studied. The outcome of smoke toxicity test and repellency test were impressive. Conclusion: The study reveals that the solvent extracts of Ficus krishnae could be an effective natural alternative to get control over the mosquito population.

  20. 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°.

  1. Modulation of the behavioral and electrical responses to the repellent DEET elicited by the pre-exposure to the same compound in Blattella germanica.

    Science.gov (United States)

    Sfara, Valeria; Mougabure-Cueto, Gastón A; González-Audino, Paola A

    2016-01-01

    Insects under different stimuli from the environment modify behavioural responses due to changes in the sensitivity of neurons at the peripheral and/or at the central level of the nervous system. This phenomenon is called neuronal plasticity, and sensory adaptation is an example of it. An insect repellent is a chemical that produces oriented movements of the insects away from its source. In this work we studied the modulation of the behavioural and electrical response to the repellent N, N-diethyl-3-methylbenzamide (DEET) in males of the German cockroach B. germanica produced by previous exposure to the same repellent. Methods. We determined repellency using a circular arena, one half of which was treated with DEET. The time spent by insects in each half of the arena was measured, and a repellency coefficient (RC) was calculated. The RCs of pre-exposed and non-pre-exposed insects were compared. To determine a possible role of nitric oxide in the modulation of the response to DEET after pre-exposure, the nitric oxide donor S-nitroso-acetyl-cysteine (SNAC) was applied on cockroaches' antennae. The electrical activity of the cockroaches' antennae in response to DEET was recorded using electroantennogram (EAG) technique. The response to DEET was recorded also after a long stimulation with the same repellent, and after topical application of SNAC and dbcGMP (a cGMP analogue) on the antennae. Results. We found that previous exposure of B. germanica males to the repellent DEET produced an increase of the repellency at the behavioural level, measured as RC. A possible role of nitric oxide (NO) in the transduction pathway of this phenomenon is suggested, since treatment of the cockroaches with the NO donor SNAC also produced an increase of the repellency elicited by DEET. On the other hand, the response of the cockroaches' antennae exposed to DEET was determined electrophysiologically. The electrical activity in response to DEET decreased when the insects' antennae were

  2. Modulation of the behavioral and electrical responses to the repellent DEET elicited by the pre-exposure to the same compound in Blattella germanica

    Directory of Open Access Journals (Sweden)

    Valeria Sfara

    2016-06-01

    Full Text Available Insects under different stimuli from the environment modify behavioural responses due to changes in the sensitivity of neurons at the peripheral and/or at the central level of the nervous system. This phenomenon is called neuronal plasticity, and sensory adaptation is an example of it. An insect repellent is a chemical that produces oriented movements of the insects away from its source. In this work we studied the modulation of the behavioural and electrical response to the repellent N, N-diethyl-3-methylbenzamide (DEET in males of the German cockroach B. germanica produced by previous exposure to the same repellent. Methods. We determined repellency using a circular arena, one half of which was treated with DEET. The time spent by insects in each half of the arena was measured, and a repellency coefficient (RC was calculated. The RCs of pre-exposed and non-pre-exposed insects were compared. To determine a possible role of nitric oxide in the modulation of the response to DEET after pre-exposure, the nitric oxide donor S-nitroso-acetyl-cysteine (SNAC was applied on cockroaches’ antennae. The electrical activity of the cockroaches’ antennae in response to DEET was recorded using electroantennogram (EAG technique. The response to DEET was recorded also after a long stimulation with the same repellent, and after topical application of SNAC and dbcGMP (a cGMP analogue on the antennae. Results. We found that previous exposure of B. germanica males to the repellent DEET produced an increase of the repellency at the behavioural level, measured as RC. A possible role of nitric oxide (NO in the transduction pathway of this phenomenon is suggested, since treatment of the cockroaches with the NO donor SNAC also produced an increase of the repellency elicited by DEET. On the other hand, the response of the cockroaches’ antennae exposed to DEET was determined electrophysiologically. The electrical activity in response to DEET decreased when the

  3. Comparative repellency effect of three plant extracts on Paederus beetles(Coleoptera: Staphylinidae), the cause of linear dermatitis in Iran

    Institute of Scientific and Technical Information of China (English)

    Dariush Gaffari; Maryam Hakimi Parizi; Abbas Aghaei Afshar; Siavosh Tirgari

    2016-01-01

    Objective: To investigate the repellent effect of neem, juniper and eucalyptus extracts as a form of protection against Paederus beetles, which are a cause of linear dermatitis in Iran.Methods: After collecting and extracting plant samples, the extracts were tested on Paederus beetles in three concentrations(2.5%, 5.0% and 10.0%) with direct method under laboratory conditions. The data were analyzed using SPSS software(version 20).Results: The results indicated that there was a significant difference between neem with juniper and eucalyptus at the 2.5% and 5.0% concentrations(P < 0.05), whereas there was a significant difference between all three extracts at the 10.0% concentration(P < 0.05).Conclusions: This is the first report on the repellent effect of these three plant extracts on Paederus beetles. Neem oil appeared to have the largest effect on Paederus spp. and juniper essential oil exhibited the second highest repellency, followed by eucalyptus.

  4. 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.

  5. Control of tungiasis through intermittent application of a plant-based repellent: an intervention study in a resource-poor community in Brazil.

    Directory of Open Access Journals (Sweden)

    John Buckendahl

    Full Text Available BACKGROUND: Tungiasis, an ectoparasitosis caused by the female sand flea Tunga penetrans, is an important health problem in many impoverished communities in the tropics. Sand flea disease is associated with a broad spectrum of clinical pathology and severe sequels are frequent. Treatment options are limited. METHODOLOGY/PRINCIPAL FINDINGS: We assessed the effectiveness of the intermittent application of the plant-based repellent Zanzarin to reduce infestation intensity and tungiasis-associated morbidity in a resource-poor community in Brazil, characterized by a very high attack rate. The study population was randomized into three cohorts. Initially, during a period of four weeks, the repellent was applied twice daily to the feet of all cohort members. This reduced the number of embedded sandfleas to 0 in 98% of the participants. Thereafter members of cohort A applied the repellent every second week twice daily for one week, members of cohort B every fourth week for one week, and members of cohort C served as controls. Infestation intensity and tungiasis-associated morbidity were monitored during five months. The intermittent application of Zanzarin for one week every second week significantly reduced infestation intensity from a median 4 lesions (IQR 1-9 during the whole transmission season. In contrast, in cohort B (application of the repellent every fourth week the infestation intensity remained twice as high (median 8 lesions, IQR 9-16; p = 0.0035, and in the control cohort C 3.5 times as high (median 14 lesions; IQR 7-26; p = 0.004 during the transmission season. Tungiasis-related acute pathology remained very low in cohort A (median severity score 2; IQR 1-4 as compared to cohort B (median severity score 5; IQR 3-7; p<0.001, and control cohort C (median severity score 6.5; IQR 4-8; p<0.001. CONCLUSIONS/SIGNIFICANCE: Our study shows that in a setting with intense transmission, tungiasis-associated morbidity can be minimized through

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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 significant reduction in DEET-elicited protection against ZIKV-infected yellow fever mosquitoes from old and recent laboratory colonies. The reduction in protection is more likely associated with aging than the virus infection and could be compensated by applying a 5x higher dose of DEET. A substantial protection against ZIKV-infected and old noninfected mosquitoes was achieved with 5% DEET, which corresponds approximately to a 30% dose in the conventional arm-in-cage assays. PMID:28205633

  15. 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.

  16. Fumigant and repellent properties of sesquiterpene-rich essential oil from Teucrium polium subsp. capitatum (L.)

    Institute of Scientific and Technical Information of China (English)

    Abbas Khani; Monireh Heydarian

    2014-01-01

    Objective:To test fumigant and repellent properties of sesquiterpene-rich essential oil from Teucrium polium subsp.capitatum(L.).Methods:The fumigant toxicity test was performed at(27±1)℃,(65±5)% relative humidity, and under darkness condition and24 h exposure time.The chemical composition of the isolated oils was examined by gas chromatography-mass spectrometry.Results:The major compounds wereα-cadinol(46.2%), caryophyllene oxide(25.9%), α muurolol epi(8.1%), cadalene(3.7%) and longiverbenone(2.9%).In all cases, considerable differences in mortality of insect to essential oil vapor were observed in different concentrations and exposure times.Callosobruchus maculatus(C. maculates)(LC50=148.9 μL/L air) was more susceptible to the tested plant product thanTeucrium castaneum(T. castaneum) (LC50=360.2 μL/L air) based onLC50 values.In the present investigation, the concentration of3 μL /mL acetone showed60% and52% repellency againstT. casteneumandC. maculatus adults, respectively.Conclusions:The results suggests that sesquiterpene-rich essential oils from the tested plant could be used as a potential control agent for stored-product insects.

  17. 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.

  18. On the analysis of effectiveness in mass application of mosquito repellent for dengue disease prevention

    Science.gov (United States)

    Aldila, D.; Soewono, E.; Nuraini, N.

    2012-05-01

    Dengue disease has been known as one of dangerous vector-borne diseases and become serious threat in many tropical countries. With no vaccine and antiviral available until nowadays, and frequent appearance of extraordinary dengue outbreaks, many governments are forced to declare national problem for dengue. At this moment, the only method available to prevent dengue disease transmission is to combat the disease-carrying mosquitoes as well as to reduce the contact between human and mosquitoes. The fast growing dengue transmission in many countries in recent years indicates that the mosquito control programs are far from successful. The use of mosquito repellent is one possible instrument which could be used as an effective mass treatment to prevent the dengue outbreak during endemic period. Here in this paper a Susceptible-Infectious-Recovered (S-I-R) dengue transmission model with repellent mass treatment is being applied to portions of children and adult compartments. Analysis of the basic reproductive ratio (Ro) of the model is done. It is shown, with reasonable choices of portions of treated children and adults, in combination with reduction of mosquito population, the basic reproductive ratio can be significantly reduced and occurrence of endemic can be avoided. Numerical simulations are shown for various treatment scenarios.

  19. 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.

  20. 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.

  1. Snap-Back Repellers and Chaos in Time-delayed Chua's Circuit

    Institute of Scientific and Technical Information of China (English)

    Yu Chang

    2005-01-01

    The chaotic behavior of one-dimensional, 2-segment and 3-segment piecewise-linear maps is examined by using the concept of snap-back repellers introduced by Marotto and the parameters conditions of existence for snap-back repeller are obtained. Simulation results are presented to show the snap-back repeller,some periodic points and attracting interval cycles with chaotic intervals.

  2. 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.

  3. Field Evaluation of Four Spatial Repellent Devices Against Arkansas Rice-Land Mosquitoes

    Science.gov (United States)

    2014-03-01

    FIELD EVALUATION OF FOUR SPATIAL REPELLENT DEVICES AGAINST ARKANSAS RICE-LAND MOSQUITOES DAVID A. DAME,1 MAX V. MEISCH,2 CAROLYN N. LEWIS,2 DANIEL L... mosquitoes to locate a host. There are many commercially available spatial repellent products currently on the market. These products include...a large rice growing area where late-spring and summer agricultural irriga- tion generates dense mosquito populations. Spatial repellent devices

  4. Multi-function oxidases are responsible for the synergistic interactions occurring between repellents and insecticides in mosquitoes

    Directory of Open Access Journals (Sweden)

    Duchon Stéphane

    2009-04-01

    Full Text Available Abstract Background With the spread of pyrethroid resistance in mosquitoes, the combination of an insecticide (carbamate or organophosphate with a repellent (DEET is considered as a promising alternative strategy for the treatment of mosquito nets and other relevant materials. The efficacy of these mixtures comes from the fact that they reproduce pyrethroid features and that positive interactions occur between insecticides and repellent. To better understand the mechanisms involved and assess the impact of detoxifying enzymes (oxidases and esterases in these interactions, bioassays were carried out in the laboratory against the main dengue vector Aedes aegypti. Methods Topical applications of DEET and propoxur (carbamate, used alone or as a mixture, were carried out on female mosquitoes, using inhibitors of the two main detoxification pathways in the insect. PBO, an inhibitor of multi-function oxidases, and DEF, an inhibitor of esterases, were applied one hour prior to the main treatment. Results Results showed that synergism between DEET and propoxur disappeared in the presence of PBO but not with DEF. This suggests that oxidases, contrary to esterases, play a key role in the interactions occurring between DEET and cholinesterase inhibitors in mosquitoes. Conclusion These findings are of great interest for the implementation of "combination nets" in the field. They support the need to combine insecticide with repellent to overcome insecticide resistance in mosquitoes of public health importance.

  5. Repellent properties of Cardiospermum halicacabum Linn. (Family:Sapindaceae) plant leaf extracts against three important vector mosquitoes

    Institute of Scientific and Technical Information of China (English)

    M Govindarajan; R Sivakumar

    2012-01-01

    Objective: To determine repellent activity of hexane, ethyl acetate, benzene, chloroform and methanol extract of Cardiospermum halicacabum (C. halicacabum) against Culex quinquefasciatus (Cx. quinquefasciatus), Aedes aegypti (Ae. aegypti) and Anopheles stephensi (An. stephensi).Methods:Evaluation was carried out in a net cage (45 cm×30 cm×25 cm) containing 100 blood starved female mosquitoes of three mosquito species and were assayed in the laboratory condition by using the protocol of WHO 2005; The plant leaf crude extracts of C. halicacabum was applied at 1.0, 2.5, and 5.0 mg/cm2 separately in the exposed area of the fore arm. Only ethanol served as control. Results: In this observation, the plant crude extracts gave protection against mosquito bites without any allergic reaction to the test person, and also, the repellent activity was dependent on the strength of the plant extracts. The tested plant crude extracts had exerted promising repellent against all the three mosquitoes. Conclusions: From the results it can be concluded the crude extract of C. halicacabum was potential for controlling Cx. quinquefasciatus,Ae. aegypti and An. stephensi mosquitoes.

  6. Selective protein immobilization onto gold nanoparticles deposited under vacuum on a protein-repellent self-assembled monolayer.

    Science.gov (United States)

    Peissker, Tobias; Deschaume, Olivier; Rand, Danielle R; Boyen, Hans-Gerd; Conard, Thierry; Van Bael, Margriet J; Bartic, Carmen

    2013-12-10

    The immobilization of proteins on flat substrates plays an important role for a wide spectrum of applications in the fields of biology, medicine, and biochemistry, among others. An essential prerequisite for the use of proteins (e.g., in biosensors) is the conservation of their biological activity. Losses in activity upon protein immobilization can largely be attributed to a random attachment of the proteins to the surface. In this study, we present an approach for the immobilization of proteins onto a chemically heterogeneous surface, namely a surface consisting of protein-permissive and protein-repellent areas, which allows for significant reduction of random protein attachment. As protein-permissive, i.e., as protein-binding sites, ultra pure metallic nanoparticles are deposited under vacuum onto a protein-repellent PEG-silane polymer layer. Using complementary surface characterization techniques (atomic force microscopy, quartz crystal microbalance, and X-ray photoelectron spectroscopy) we demonstrate that the Au nanoparticles remain accessible for protein attachment without compromising the protein-repellency of the PEG-silane background. Moreover, we show that the amount of immobilized protein can be controlled by tuning the Au nanoparticle coverage. This method shows potential for applications requiring the control of protein immobilization down to the single molecule level.

  7. Mosquito adulticidal and repellent activities of botanical extracts against malarial vector,Anopheles stephensi Liston (Diptera:Culicidae)

    Institute of Scientific and Technical Information of China (English)

    Marimuthu Govindarajan; Rajamohan Sivakumar

    2011-01-01

    Objective:To determine the adulticidal and repellent activities of different solvent leaf extracts ofEclipta alba (E. alba) andAndrographis paniculata (A. paniculata)against malarial vector, Anopheles stephensi (An. stephensi).Methods:Adulticidal efficacy of the crude leaf extracts ofE. alba andA. paniculata with five different solvents like benzene, hexane, ethyl acetate, methanol and chloroform was tested against the five to six day old adult female mosquitoes of An. stephensi. The adult mortality was observed after24 h under the laboratory conditions. The repellent efficacy was determined againstAn. stephensimosquito species at three concentrations viz.,1.0, 2.5 and 5.0 mg/cm2 under laboratory conditions.Results: Among the tested solvents the maximum efficacy was observed in the methanol extract. TheLC50 andLC90 values ofE. alba andA. paniculata against adults ofAn. stephensiwere150.36, 130.19 ppm and285.22, 244.16ppm, respectively. No mortality was observed in controls. Thechi-square values were significant at P<0.05 level. Methanol extract of E. alba andA. paniculata was produce maximum repellency againstAn. stephensi.Conclusions:From the results it can be concluded the crude extract ofE. alba andA. paniculatawas an excellent potential for controllingAn. stephensimosquitoes.

  8. Mosquito repellent potential ofPithecellobium dulce leaf and seed against malaria vectorAnopheles stephensi (Diptera:Culicidae)

    Institute of Scientific and Technical Information of China (English)

    Mohan Rajeswary; Marimuthu Govindarajan

    2016-01-01

    Objective:To determine the repellent properties of hexane, benzene, ethyl acetate, chloroform and methanol extract ofPithecellobium dulce (P. dulce) leaf and seed against Anopheles stephensi(An. stephensi). Methods:Repellent activity assay was carried out in a net cage (45 cmí30 cmí25 cm) containing 100 blood starved female mosquitoes ofAn. stephensi. This assay was carried out in the laboratory conditions according to theWHO 2009 protocol. Plant crude extracts ofP. dulce were applied at 1.0, 2.5, and 5.0 mg/cm2 separately in the exposed fore arm of study subjects. Ethanol was used as the sole control. Results: In this study, the applied plant crude extracts were observed to protect against mosquito bites. There were no allergic reactions experienced by the study subjects. The repellent activity of the extract was dependent on the concentration of the extract. Among the tested solvents, the leaf and seed methanol extract showed the maximum efficacy. The highest concentration of 5.0 mg/cm2 leaf and seed methanol extract ofP. dulceprovided over 180 min and 150 min protection, respectively. Conclusions: Crude extracts ofP. dulceexhibit the potential for controlling malaria vector mosquitoAn. stephensi.

  9. Larvicidal and repellent activities ofSida acuta Burm. F. (Family:Malvaceae) against three important vector mosquitoes

    Institute of Scientific and Technical Information of China (English)

    Marimuthu Govindarajan

    2010-01-01

    Objective:To determine the larvicidal and repellent activities ofSida acuta Burm. F. (Family: Malvaceae)extract against Culex quinquefasciatus, Aedes aegypti and Anopheles stephensi. Methods: Twenty five late III instar larve of three mosquito species were exposed to various concentrations (15-90 mg/L) and were assayed in the laboratory by using the protocol ofWHO 2005; the24 h LC50 values of theSida acuta leaf extract was determined following Probit analysis. The repellent efficacy was determined against three mosquito species at three concentrations viz.,1.0, 2.5 and5.0mg/cm2 under the laboratory conditions.Results:Results showed varying degree of larvicidal activity of crude extract of Sida acuta against three important mosquitoes withLC50values ranging between38 to48 mg/L. The crude extract had strong repellent action against three species of mosquitoes as it provided100%protection againstAnopheles stephensi for 180min followed byAedes aegypti (150 min) andCulex quinquefasciatus (120 min).Conclusions:From the results it can be concluded the crude extract ofSida acuta was an excellent potential for controllingCulex quinquefasciatus, Aedes aegypti andAnopleles stephensi mosquitoes.

  10. Ovicidal and repellent activities of botanical extracts against Culex quinquefasciatus, Aedes aegypti and Anopheles stephensi (Diptera:Culicidae)

    Institute of Scientific and Technical Information of China (English)

    Govindarajan M; Mathivanan T; Elumalai K; Krishnappa K; Anandan A

    2011-01-01

    Objective: To determine the ovicidal and repellent activities of methanol leaf extract ofErvatamia coronaria (E. coronaria) and Caesalpinia pulcherrima (C. pulcherrima) against Culex quinquefasciatus (Cx. quinquefasciatus), Aedes aegypti (Ae. aegypti) and Anopheles stephensi (An. stephensi). Methods: The ovicidal activity was determined against three mosquito species at various concentrations ranging from 50-450 ppm under the laboratory conditions. The hatch rates were assessed 48 h after treatment. The repellent efficacy was determined against three mosquito species at three concentrations viz., 1.0, 2.5 and 5.0 mg/cm2 under the laboratory conditions.Results:The crude extract of E. coronaria exerted zero hatchability (100% mortality) at 250, 200 and 150 ppm for Cx. quinquefasciatus, Ae. aegypti and An. stephensi, respectively. The crude extract of C. pulcherrima exerted zero hatchability (100% mortality) at 375, 300 and 225 ppm for Cx. quinquefasciatus, Ae. aegypti and An. Stephensi, respectively. The methanol extract of E. coronaria found to be more repellenct than C. pulcherrima extract. A higher concentration of 5.0 mg/cm2 provided 100% protection up to 150, 180 and 210 min against Cx. quinquefasciatus, Ae.aegypti and An. stephensi, respectively. The results clearly showed that repellent activity was dose dependent. Conclusions: From the results it can be concluded the crude extracts of E. coronaria and C. pulcherrima are an excellent potential for controlling Cx. quinquefasciatus, Ae. aegypti and An. stephensi mosquitoes.

  11. Mosquito repellent properties of Delonix elata (L. gamble (Family: Fabaceae against filariasis vector, Culex quinquefasciatus Say. (Diptera: Culicidae

    Directory of Open Access Journals (Sweden)

    Marimuthu Govindarajan

    2014-02-01

    Full Text Available Objective: To determine the repellent activity of hexane, ethyl acetate, benzene, chloroform and methanol extract of Delonix elata (D. elata leaf and seed against Culex quinquefasciatus (Cx. quinquefasciatus. Methods: Evaluation was carried out in a net cage (45 cm伊30 cm伊25 cm containing 100 blood starved female mosquitoes of Cx. quinquefasciatus. Repellent activity was carried out in the laboratory conditions according to the WHO 2009 protocol. Plant crude extracts of D. elata were applied at 1.0, 2.5, and 5.0 mg/cm2 separately in the exposed fore arm of study subjects. Ethanol was used as the sole control. Results: In this study, the applied plant crude extracts were observed to protect against mosquito bites. There were no allergic reactions experienced by the study subjects. The repellent activity of the extract was dependent on the strength of the extract. Among the tested solvents, the leaf and seed methanol extract showed the maximum efficacy. The highest concentration of 5.0 mg/cm2 provided over 150 min and 120 min protection, respectively. Conclusions: Crude extracts of D. elata exhibit the potential for controlling Cx. quinquefasciatus, the mosquito vector of filariasis.

  12. Substrate-Independent, Transparent Oil-Repellent Coatings with Self-Healing and Persistent Easy-Sliding Oil Repellency.

    Science.gov (United States)

    Yu, Li; Chen, George Y; Xu, Haolan; Liu, Xiaokong

    2016-01-26

    Herein we report a simple and substrate-independent approach to fabricate transparent oil-repellent coatings, which involves alternate deposition of poly(diallyldimethylammonium) (PDDA) and poly(styrenesulfonate) (PSS) onto substrates, followed by incubation of the coated objects into perfluorooctanoate (PFO) aqueous solutions for 2 min. Various low-surface-tension liquids can easily slide down the coating surfaces on flat substrates at a sliding angle lower than 12° for 10 μL droplets. The coatings are applicable to different substrates including Si, glass, plastic, steel, and wood, and those with complex shapes and large surface areas. They are also applicable to rough substrates with roughness at both micro/nanoscale and macroscopic scales to realize the easy-sliding oil repellency. Incubation of the PDDA/PSS polyelectrolyte multilayers (PEMs) into PFO solutions induces an effective but nondestructive substitution of PFO anions for PSS in the PEMs, which results in a composite coating with PFO anions homogeneously interspersed in both the coating surface and the bulk. Thanks to the as-described "repeating-layer" composition/structure of the coatings, their easy-sliding oil repellency can be self-healed after surface decomposition or well maintained after physical damages, due to the replenishing surface. Therefore, the advantageous characteristics of the as-developed oil-repellent coatings and the simplicity of the preparation protocol make the coatings highly practical for real-world applications. It is believed that the coatings can perform as antismudge coatings that shield against oil-borne contaminants, chemical-shield coatings that protect coated plastics from dissolution by organic solvents, and nonstick coatings (of oil tankers or pipelines) that enable loss-free oil transportation.

  13. The efficacy of repellents against Aedes, Anopheles, Culex and Ixodes spp. - a literature review.

    Science.gov (United States)

    Lupi, Eleonora; Hatz, Christoph; Schlagenhauf, Patricia

    2013-01-01

    Travellers are confronted with a variety of vector-borne threats. Is one type of repellent effective against all biting vectors? The aim of this review is to examine the literature, up to December 31st, 2012, regarding repellent efficacy. We searched PubMed for relevant papers. Repellents of interest were DEET, Icaridin as well as other piperidine-derived products (SS220), Insect Repellent (IR) 3535 (ethyl-butylacetyl-amino-propionat, EBAAP) and plant-derived products, including Citriodora (para-menthane-3,8-diol). As vectors, we considered the mosquito species Anopheles, Aedes and Culex as well as the tick species Ixodes. We selected only studies evaluating the protective efficacy of repellents on human skin. We reviewed a total of 102 publications. Repellents were evaluated regarding complete protection time or as percentage efficacy [%] in a time interval. We found no standardized study for tick bite prevention. Regarding Aedes, DEET at concentration of 20% or more, showed the best efficacy providing up to 10 h protection. Citriodora repellency against this mosquito genus was lower compared to the other products. Also between subspecies a difference could be observed: Ae. aegypti proved more difficult to repel than Ae. Albopictus. Fewer studies have been conducted on mosquito species Anopheles and Culex. The repellency profile against Anopheles species was similar for the four principal repellents of interest, providing on average 4-10 h of protection. Culex mosquitoes are easier to repel and all four repellents provided good protection. Few studies have been conducted on the tick species Ixodes. According to our results, the longest protection against Ixodes scapularis was provided by repellents containing IR3535, while DEET and commercial products containing Icaridin or PMD showed a better response than IR3535 against Ixodes ricinus. Many plant-based repellents provide only short duration protection. Adding vanillin 5% to plant-based repellents and to DEET

  14. Evaluation of biological and chemical insect repellents and their potential adverse effects.

    Science.gov (United States)

    Semmler, Margit; Abdel-Ghaffar, Fathy; Schmidt, Jürgen; Mehlhorn, Heinz

    2014-01-01

    Plant extracts, particularly plant oils, had been used and were still in use as repellents against mosquitoes. Some of them (e.g., lavender, geraniol, and citriodiol) have been notified by the European Commission as active substances to be used in repellents, which are categorized as biocides in product type 19. In the literature, it is known that these substances must be added to repellent products in high concentrations (e.g., 20% and more) in order to reach repellent efficacy. Therefore, the question arose whether they also have repellent effects if they were added as fragrances at low concentrations of 0.25 or 1% to registered active substances in order to obtain a better scent of this product. In the present study, the repellent effects of 0.25 and 1% additions of 15 plant extracts (citronellol, cinerol, citral, menthol, linalyl acetate, Eucalyptus citriodora, Eucalyptus globulus, Cymbopogon nardus, lilac, sandalwood, Vitex agnus castus, rosewood, lavender, geraniol, and paramenthan diol) when exposed on skin to hungry Aedes aegypti mosquitoes. These experiments showed that there was no repellent effect in any of these compounds even when the test was done already 10 min after distributing any of the compounds onto the hands of volunteers. These experiments have proven that these 15 compounds do not produce repellent effects as long as they are used in low concentrations of 0.25 or 1% as fragrances to ameliorate the odor of a notified repellent that is brought onto the skin.

  15. Repellency of Plant Extracts against the Legume Flower Thrips Megalurothrips sjostedti (Thysanoptera: Thripidae

    Directory of Open Access Journals (Sweden)

    Andnet Abtew

    2015-06-01

    Full Text Available Megalurothrips sjostedti Trybom is an important pest of cowpea (Vigna unguiculata L. in Africa. To propose an alternative to chemical control, the repellency of 24 plant extracts was evaluated against adult female thrips of M. sjostedti in the laboratory. Plant extracts in ethanol were separately applied on a filter paper disk in a still air visual cue olfactometer. The results showed highly significant differences in repellency among extract type, concentration and their interactions. We classified the level of repellency into four categories as strong, good, moderate and weak or non- repellent based on hierarchical ascendant classification. We identified Piper nigrum, Cinnamomum zeylanicum, Cinnamomum cassia as strong repellents. Five extracts were classified as good, eight as moderate and the remaining eight extracts were weak or non-repellent. Repellency of the extracts increased with the concentration suggesting that the behavioral response of M. sjostedti was dose-dependent. Mono- and sesquiterpene hydrocarbon compounds from seven highly repellent extracts were identified by gas chromatography-mass spectrometry (GC/MS. The use of repellent extracts could be useful in developing integrated pest management strategies for thrips on legume crops. In this regard, the specific modes of action of the identified compounds need to be investigated to incorporate them into the existing crop protection strategies.

  16. 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.

  17. Field evaluation of deet, Repel Care, and three plant based essential oil repellents against mosquitoes, black flies (Diptera: Simuliidae) and land leeches (Arhynchobdellida: Haemadipsidae) in Thailand.

    Science.gov (United States)

    Tawatsin, Apiwat; Thavara, Usavadee; Chansang, Uruyakorn; Chavalittumrong, Pranee; Boonruad, Thidarat; Wongsinkongman, Prapai; Bansidhi, Jaree; Mulla, Mir S

    2006-06-01

    Diethyl methyl benzamide, or deet, a commercial plant-based repellent (Repel Care), and essential ils from 3 species of plants (finger root rhizomes, guava leaves, and turmeric rhizomes), steam distillated and formulated as insect repellents, were evaluated in the field on human volunteers against hematophagous mosquitoes, black flies, and land leeches in Thailand. Field trials were conducted against wild mosquitoes in Bang Bua Thong District, Nonthaburi Province, and in the Thap Lan National Park Headquarters, Nadee District, Pranchinburi Province; anthroophilic black flies (Diptera: Simuliidae) at the Forestry Fire Control Station in Doi Inthanon National Park, Chomthong district, Chiang Mai Province; and land leeches (Arhynchobdellida: Haemadipsidae) in the Khao Yai National Park, Pak Chong District, Nakhon Ratchasima Province. The 3 experimental plant-based essential oil formulations as well as Repel Care and deet provided complete protection from mosquito landing and biting for up to 9 h (duration of the experiment). Similar results were obtained with the 5 products against black flies, providing 100% protection for 9 h but 96-82% protection after 10 and 11 h posttreatment. The 5 repellent products also provided 100% protection against land leeches for at least 8 h. Thi is the 1st report of repellency of plant-based repellents against black flies and land leeches in Thailand. The identification and availability of inexpensive sources of plant-based oils, i.e., finger root rhizomes, guava leaves, and turmeric rhizomes providing long-lasting repellency against blood-sucking organisms are promising leads into commercial production of relatively safe and effective repellents.

  18. The excito –repellency effect of pyrethroid insecticide-treated bednets on An. stephensi under laboratory condition

    Directory of Open Access Journals (Sweden)

    Hamzeh Ali Pour

    2006-02-01

    Full Text Available Background: The excito-repellency effect due to the application of some insecticides is important in interrupting the malaria transmission cycle. The repellency effect of some insecticides also inhibits the entry of mosquitoes into sprayed houses, which in long-term causes alteration in endophilic and exophilic rates. Methods: In this study, a modified excito-repellency (E-R test box was used. In order to standardize this system, a number of methods and techniques were considered to evaluate the mosquitoes’ reaction to pyrethroid-impregnated nets. A cylindrical guinea – pig holder made up of aluminum mesh was placed within the exposure chamber. Treated and untreated nets covered this holder so that the guinea pig was available to mosquito for bloodfeeding. An exit trap was devised on the rear side of the exposure chamber. Nets were impregnated with lambdacyhalothrin insecticide at the concentrations of 12.5, 25 and 50 mg/m2, deltamethrin at 12.5, 25 and 50 mg/m2 and cyfluthrin at 40, 80 and 100 mg/m2 or unimpregnated in laboratory by standard dipping procedure. The bloodfeeding rate, exit rate, survival rate, mortality rate and recovery rate of mosquitoes were considered. Results: The results obtained using one-way analysis of variance (ANOVA reflects a significant difference in excito-repellency of tested insecticides (p<0.05. The bloodfeeding rate of exposed mosquitoes to nets treated with lambdacyhalothrin, deltamethrin and cyfluthrin at standard dose of 25 mg/m2 were 15%, 5.3%and 9.3% respectively the exit rates were also 18.2%, 11.2% and 19.7%, and it was 98.9 % in the control group. The survival rate of mosquitoes was 63.2%, 34.9% and 67%, respectively. The bloodfeeding and exit rates for control group were 41.3% and 1.4%, respectively. Conclusion: The excito-repellency evaluation revealed that the deltamethrin-impregnated net was more effective on An. stephensi than lambdacyhalothrin and cyfluthrin insecticides, under laboratory

  19. Repellent activity of Eucalyptus and Azadirachta indica seed oil against the filarial mosquito Culex quinquefasciatus Say (Diptera:Culicidae) in India

    Institute of Scientific and Technical Information of China (English)

    Shyamapada Mandal

    2011-01-01

    Objective: To evaluate the repellent activity of Eucalyptus and Azadirachta indica (A. indica) seed oil against filarial mosquito Culex quinquefasciatus (Cx. quinquefasciatus) from Purulia district of the West Bengal state, India. Methods: The repellent activity of Eucalyptus and A. indica seed oils (using coconut oil base) against Cx. quinquefasciatus mosquito were evaluated in indoor conditions. Three concentrations, 0%, 50% and 100% (v/v) of both the agents were considered in the studies. The protection percentage was determined, and the protection time was recorded. Results: The test oils showed excellent repellent action against Cx. quinquefasciatus. The A. indica seed oil provided 90.26% and 88.83% protection, and the Eucalyptus oil 93.37% and 92.04%, at concentrations 50% and 100% (v/v), respectively, with the protection time up to 240 min. There was no bite within 120 min and 180 min, respectively, due to the action of Eucalyptus andA. indica seed oil, and thus 100% protection from the bite of Cx. quinquefasciatus mosquito was achieved. Conclusions: The present study clearly demonstrates the potential of Eucalyptus and A. indica seed oils as topical repellents against Cx. quinquefasciatus, the mosquito vector of filariasis.

  20. 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.

  1. Evaluation of DEET and eight essential oils for repellency against nymphs of the lone star tick, Amblyomma americanum (Acari: Ixodidae)

    Science.gov (United States)

    Eight commercially available essential oils (oregano, clove, thyme, vetiver, sandalwood, cinnamon, cedarwood, and peppermint) were evaluated for repellency against host-seeking nymphs of the lone star tick, Amblyomma americanum. Concentration- repellency response was established using the vertical ...

  2. Larvicidal and repellent properties of some essential oils againstCulex tritaeniorhynchus Giles andAnopheles subpictusGrassi (Diptera:Culicidae)

    Institute of Scientific and Technical Information of China (English)

    Marimuthu Govindarajan

    2011-01-01

    Objective:To investigate the larvicidal and repellent properties of essential oils from various parts of four plant speciesCymbopogan citrates, Cinnamomum zeylanicum, Rosmarinus officinalis andZingiber officinale againstCulex tritaeniorhynchus (Cx. tritaeniorhynchus)and Anopheles subpictus (An. subpictus).Methods: Essential oils were obtained by hydro-distillation method. The mosquitoes were reared in the vector control laboratory and twenty five late third instar larvae ofCx. tritaeniorhynchus andAn. subpictus were exposed to based on the wide range and narrow range test, essential oil tested at various concentrations ranging from25 to 250 ppm. The larval mortality was observed after 24 h under the laboratory conditions. The repellent efficacy was determined against two mosquito species at three concentrations viz., 1.0,2.5 and5.0 mg/cm2 under laboratory conditions.Results:Results showed all the four plant essential oil produced significant larval mortality against two mosquito species. However, the highest larvicidal activity was observed in the essential oil fromZingiber officinale againstCx. tritaeniorhynchus andAn. subpictus with theLC50 andLC90 values as98.83, 57.98 ppm and186.55, 104.23 ppm, respectively. All the four essential oil shows significant repellency againstCx. tritaeniorhynchus thanAn. subpictus. Among four essential oil tested the highest repellency was observed inZingiber officinale, a higher concentration of5.0 mg/cm2 provided100% protection up to150 and180 min againstCx. tritaeniorhynchus andAn. subpictus, respectively.Conclusions:In this work, it can be concluded that four essential oils which were distilled fromCymbopogan citrates, Cinnamomum zeylanicum, Rosmarinus officinalis andZingiber officinale showed promising larvicidal and repellent agent againstCx. tritaeniorhynchus andAn. subpictus.

  3. Pupicidal and repellent activities of Pogostemon cablin essential oil chemical compounds against medically important human vector mosquitoes

    Directory of Open Access Journals (Sweden)

    Gokulakrishnan J

    2013-02-01

    Full Text Available Objective: To determine the repellent and pupicidal activities of Pogostemon cablin (P. cablin chemical compositions were assayed for their toxicity against selected important vector mosquitoes, viz., Aedes aegypti (Ae. aegypti, Anopheles stephensi (An. stephensi and Culex quinquefasciatus (Cx. quinquefasciatus (Diptera: Culicidae. Methods: The plants dry aerial parts were subjected to hydrodistillation using a modified Clevenger-type apparatus. The composition of the essential oil was analyzed by Gas Chromatography (GC and GC mass spectrophotometry. Evaluation was carried out in a net cage (45 cm ×30 cm ×45 cm containing 100 blood starved female mosquitoes and were assayed in the laboratory condition by using the protocol of WHO 2010. The repellent activity of P. cablin chemical compositions at concentration of 2mg/cm2were applied on skin of fore arm in man and exposed against adult female mosquitoes. The pupicidal activity was determined against selected important vector mosquitoes to concentration of 100 mg/L and mortality of each pupa was recorded after 24 h of exposure to the compounds. Results: Chemical constituents of 15 compounds were identified in the oil of P.cablin compounds representing to 98.96%. The major components in essential oil were â-patchoulene, á-guaiene, ã-patchoulene, á-bulnesene and patchouli alcohol. The repellent activity of patchouli alcohol compound was found to be most effective for repellent activity and 2 mg/cm2 concentration provided 100% protection up to 280 min against Ae. aegypti, An. stephensi and Cx. quinquefasciatus, respectively. Similarly, pupae exposed to 100 mg/L concentrations of P. cablin chemical compositions. Among five compounds tested patchouli alcoholwas found to be most effective for pupicidal activity provided 28.44, 26.28 and 25.36 against Ae.aegypti, An.stephensi and Cx. quinquefasciatus, respectively. The percent adult emergence was inversely proportional to the concentration of

  4. 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

  5. Pupicidal and repellent activities of Pogostemon cablin essential oil chemical compounds against medically important human vector mosquitoes

    Science.gov (United States)

    Gokulakrishnan, J; Kuppusamy, Elumalai; Shanmugam, Dhanasekaran; Appavu, Anandan; Kaliyamoorthi, Krishnappa

    2013-01-01

    Objective To determine the repellent and pupicidal activities of Pogostemon cablin (P. cablin) chemical compositions were assayed for their toxicity against selected important vector mosquitoes, viz., Aedes aegypti (Ae. aegypti), Anopheles stephensi (An. stephensi) and Culex quinquefasciatus (Cx. quinquefasciatus) (Diptera: Culicidae). Methods The plants dry aerial parts were subjected to hydrodistillation using a modified Clevenger-type apparatus. The composition of the essential oil was analyzed by Gas Chromatography (GC) and GC mass spectrophotometry. Evaluation was carried out in a net cage (45 cm×30 cm×45 cm) containing 100 blood starved female mosquitoes and were assayed in the laboratory condition by using the protocol of WHO 2010. The repellent activity of P. cablin chemical compositions at concentration of 2mg/cm2were applied on skin of fore arm in man and exposed against adult female mosquitoes. The pupicidal activity was determined against selected important vector mosquitoes to concentration of 100 mg/L and mortality of each pupa was recorded after 24 h of exposure to the compounds. Results Chemical constituents of 15 compounds were identified in the oil of P.cablin compounds representing to 98.96%. The major components in essential oil were â-patchoulene, á-guaiene, ã-patchoulene, á-bulnesene and patchouli alcohol. The repellent activity of patchouli alcohol compound was found to be most effective for repellent activity and 2 mg/cm2 concentration provided 100% protection up to 280 min against Ae. aegypti, An. stephensi and Cx. quinquefasciatus, respectively. Similarly, pupae exposed to 100 mg/L concentrations of P. cablin chemical compositions. Among five compounds tested patchouli alcoholwas found to be most effective for pupicidal activity provided 28.44, 26.28 and 25.36 against Ae.aegypti, An.stephensi and Cx. quinquefasciatus, respectively. The percent adult emergence was inversely proportional to the concentration of compounds and directly

  6. Potential topical natural repellent against Ae. aegypti, Culex sp. and Anopheles sp. mosquitoes

    Directory of Open Access Journals (Sweden)

    Dewi Nur Hodijah

    2014-08-01

    Full Text Available AbstrakLatar belakang:Minyak atsiri daun sirih diketahui mempunyai daya proteksi. Dibuatkan losion berdasarkan pengantar sediaan farmasi yang ditambahkan minyak atsiri daun nilam. Sediaan losion dipilih agar dapat menempel lebih lama di permukaan kulit. Tujuan penelitian ini untuk membandingkan daya proteksi antara losion dengan penambahan minyak nilam dan losion tanpa penambahan minyak nilam dibandingkan daya proteksi dengan DEET. Metode: Penelitian ini merupakan penelitian eksperimental laboratorium. Semua nyamuk uji berasal dari insektarium laboratorium penelitian kesehatan Loka litbang P2B2 Ciamis. Konsentrasi minyak atsiri daun sirih dalam losion adalah 4%; konsentrasi minyak nilam sebagai zat pengikat adalah 0,4%. Formula yang digunakan yaitu formula dasar yang ada pada pengantar sediaan farmasi. Uji repelensi dilakukan dengan menggunakan metoda yang direkomendasikan oleh Komisi pestisida.Hasil: Dihasilkan formulasi losion yang stabil dan masih memenuhi standar formulasi sediaan. Berdasarkan hasil, diperoleh data bahwa DEET dan losion hasil modifikasi memiliki rata-rata daya proteksi di atas 90% selama 6 jam terhadap nyamuk Ae.aegypti dan Culex sp. Kesimpulan: Penambahan minyak nilam pada losion sirih dapat meningkatkan daya proteksi terhadap hinggapan nyamuk Ae. aegypti dan Culex sp. (Health Science Indones 2014;1:44-8Kata kunci:repelen alamiah, minyak atsiri, daun sirih, daun nilam, Ae. aegypti, Culex sp.AbstractBackground: Betel leaf essential oil lotion has been known to have insect repellent properties. A lotion was made based on a pharmaceutical formula from a monograph where patchouli leaf essential oil was added. A lotion preparation was intended to enhance adherence of the formula on the surface of the skin. The purpose of this study was to compare protection percentage of lotion with patchouli oil and without patchouli oil lotion compared to DEET.Methods: This study is an experimental laboratory-based research. All mosquitoes

  7. 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

  8. Odorant receptor modulation: Ternary paradigm for mode of action of insect repellents

    Science.gov (United States)

    The modulation of insect behavior for the purpose of controlling the spread of infectious diseases has been the task of a few insect repellents for which the mechanistic modes of action on odorant receptors (ORs) are unclear. Here, we study the effects of the repellents DEET and IR3535, and a novel ...

  9. 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.

  10. Neurophysiological and behavioral responses of gypsy moth larvae to insect repellents

    Science.gov (United States)

    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 sensi...

  11. 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

  12. 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

  13. 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

  14. 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...

  15. 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 ...

  16. 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

  17. 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)...

  18. 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...

  19. In vitro repellency of DEET against the ticks Rhipicephalus sanguineus sensu lato and Amblyomma sculptum

    Science.gov (United States)

    Rhipicephalus sanguineus sensu lato and Amblyomma sculptum can parasite humans and domestic animals and are vectors of pathogens, including zoonoses. Repellents are an important tool of tick control. This study aimed to compare the efficacy of N,N-diethyl- 3-methylbenzamide (DEET), a standard repell...

  20. Comparative Study of Four Membranes for Evaluation of New Insect/Arthropod Repellents Using Aedes aegypti

    Science.gov (United States)

    2008-01-01

    test system, and (Armed Forces Pest Management Board. 1996) repellent potencial of the 3D pharmacophore- bascd newly designed and synthesized ten...ethyl- hexyl ester) Repellent test system: A modified inz:itro rest system was used to evaluate the potencial membrane altematives as shown in Fig. 1

  1. A Modified Synthesis of the Insect Repellent DEET

    Science.gov (United States)

    Knoess, Peter H.; Neeland, Edward G.

    1998-10-01

    In the preparation of the insect repellent DEET, lab procedures prepare the intermediate m-toluoyl chloride by heating m-toluic acid with thionyl chloride for times ranging from 15 to 45 minutes. The acid chloride is then worked up under Schotten-Baumann conditions to yield DEET. In our students' hands, these procedures gave a darkly colored product which was contaminated with an anhydride by-product. We have shown that the m-toluoyl chloride can be prepared at room temperature in 8 minutes and that the eventual DEET product is obtained in excellent yield without the dark coloration or anhydride by-product.

  2. 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.

  3. Evaluation of Certain Insecticides and Repellents Against Ticks

    Directory of Open Access Journals (Sweden)

    D. Kapoor

    1972-07-01

    Full Text Available The susceptibility of two commonly occurring species of Ixodid ticks viz., the cattle tick, Hyalomma anatolicum anatolicum Koch and the brown dog tick, Rhipicephalus sanguineus Latr to certain newer insecticdes was investigated under controlled environmental conditions. The repellency of diethyl toluamide (Deet to the two species of ticks was also investigated by a specially devised laboratory technique. It was found that based on LC/sub 50/ values, the two species were most susceptible to pyrethrins followed by carbaryl whereas malathion was found least toxic to the ticks.

  4. Physicochemical characterization of fish protein adlayers with bacteria repelling properties

    DEFF Research Database (Denmark)

    Meyer, R. L.; Arpanaei, A.; Pillai, S.;

    2013-01-01

    Materials coated with aqueous fish protein extracts can reduce bacterial adhesion, but the mechanism behind the observed effect is not fully understood. In this study we explore the physicochemical properties of fish muscle protein adlayers on four substrates: gold, stainless steel, polystyrene...... and silicon dioxide. The aims were (i) to determine if the anti-adhesive effect is independent of the underlying substrate chemistry, (ii) to link the physicochemical properties of the adlayer to its ability to repel bacteria, and (iii) to elucidate the mechanism behind this effect. The main proteins on all...

  5. Research on the Repelling Action of Rhizoma Galangae Extracts on Sitophilus Oryzae Ephebic%高良姜提取物对米象成虫的驱避作用研究

    Institute of Scientific and Technical Information of China (English)

    肖雅斌; 石运庆; 于航; 王祺; 刘洋

    2012-01-01

    Rhizoma galangae extracts were obtained using soxhlet extraction method. Control method was adopted to study its repelling action on sitophilus oryzae ephebic. The experiment results show that rhizoma galangae extracts have a strong repelling action on sitophilus oryzae ephebic with a repelling rate of 77% which belongs to Ⅳ level. The ideal repelling time is 36--48 h with a repelling rate of 85%, or of Ⅴ level. In a word, rhizoma galangae is a relatively ideal botanic pesticide.%利用索氏提取法提取高良姜植物提取物后,采用对照方法,探讨其对米象成虫的驱避作用。试验结果表明:高良姜植物提取物对米象成虫的驱避作用较强,驱避率达77%以上,属于Ⅳ级水平;最理想的驱避时间是36—48h,驱避率在85%以上,可达Ⅴ级水平。总体来说,高良姜是相对理想的植物源农药。

  6. 75 FR 47592 - Final Test Guideline; Product Performance of Skin-applied Insect Repellents of Insect and Other...

    Science.gov (United States)

    2010-08-06

    ... AGENCY Final Test Guideline; Product Performance of Skin-applied Insect Repellents of Insect and Other... Product Performance of Skin-applied Insect Repellents of Insect and Other Arthropods Test Guidelines... ``Product Performance of Skin-applied Insect Repellents of Insects and Other Arthropods'' (OPPTS...

  7. Laboratory and semi-field evaluations of two (Transfluthrin) spatial repellent devices against Aedes aegypti (L.) (Diptera: Culicidae)

    Science.gov (United States)

    Two transfluthrin-based spatial repellent products (Raid Dual Action Insect Repellent and Home Freshener and Raid Shield (currently not commercially available), SC Johnson, Racine WI) were evaluated for spatial repellent effects against female Aedes aegypti (L.) mosquitoes underlaboratory (wind tunn...

  8. Use of repellents formulated in Specialized Pheromone and Lure Application Technology (SPLAT®) for effective insect pest management

    Science.gov (United States)

    Agenor Mafra-Neto; Christopher J. Fettig; A. Steven Munson; Lukasz L. Stelinski

    2014-01-01

    Despite the many impediments to commercialization of insect repellents in agriculture and forestry, there are some situations where the use of repellents is desirable and warranted. ISCA Technologies (Riverside, California), together with collaborators from academic, government, and private sectors, is actively developing repellent formulations against several...

  9. 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.

  10. 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.

  11. Olfactory responses of the antennal trichoid sensilla to chemical repellents in the mosquito, Culex quinquefasciatus.

    Science.gov (United States)

    Liu, Feng; Chen, Li; Appel, Arthur G; Liu, Nannan

    2013-11-01

    Insect repellents are widely used to protect against insect bites and thus prevent allergic reaction and the spread of disease. To gain insight into the mosquito's response to chemicals repellents, we investigated the interaction between the olfactory system of the mosquito Culex quinquefasciatus Say and chemical repellents using single sensillum recording. The interactions of 50 repellent chemicals with olfactory receptor neurons were measured in six different types of mosquito sensilla: long sharp trichoid (LST), short sharp trichoid (SST), short blunt trichoid I (SBT-I), short blunt trichoid II (SBT-II), short blunt trichoid-curved (SBT-C), and grooved peg (GP). A single olfactory neuron reacted to the chemical repellents in each of the sensilla except for SBT-I and SBT-II, where two neurons were involved. Other than LST and GP, which showed no or very weak responses to the repellents tested, all the sensilla showed significant excitatory responses to certain types of repellents. Terpene-derived chemicals such as eucalyptol, α-pinene, and camphor, stimulated olfactory receptor neurons in a dose-dependent manner and mosquitoes responded more strongly to terpene-derived chemical repellents than to non-terpene-derived chemicals such as dimethyl phthalate. Mosquitoes also exhibited a similar response to stereoisomers of chemicals such as (-)-β-pinene versus (+)-β-pinene, and (-)-menthone versus (+)-menthone. This study not only demonstrates the effects of chemical repellents on the mosquito olfactory system but also provides important information that will assist those screening new mosquito repellents and designing new mosquito control agents.

  12. 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.;

  13. Plant Secondary Metabolites as Rodent Repellents: a Systematic Review.

    Science.gov (United States)

    Hansen, Sabine C; Stolter, Caroline; Imholt, Christian; Jacob, Jens

    2016-09-01

    The vast number of plant secondary metabolites (PSMs) produced by higher plants has generated many efforts to exploit their potential for pest control. We performed a systematic literature search to retrieve relevant publications, and we evaluated these according to PSM groups to derive information about the potential for developing plant-derived rodent repellents. We screened a total of 54 publications where different compounds or plants were tested regarding rodent behavior/metabolism. In the search for widely applicable products, we recommend multi-species systematic screening of PSMs, especially from the essential oil and terpenoid group, as laboratory experiments have uniformly shown the strongest effects across species. Other groups of compounds might be more suitable for the management of species-specific or sex-specific issues, as the effects of some compounds on particular rodent target species or sex might not be present in non-target species or in both sexes. Although plant metabolites have potential as a tool for ecologically-based rodent management, this review demonstrates inconsistent success across laboratory, enclosure, and field studies, which ultimately has lead to a small number of currently registered PSM-based rodent repellents.

  14. 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.

  15. 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.

  16. 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.

  17. Essential oil based polymeric patch development and evaluating its repellent activity against mosquitoes.

    Science.gov (United States)

    Chattopadhyay, Pronobesh; Dhiman, Sunil; Borah, Somi; Rabha, Bipul; Chaurasia, Aashwin Kumar; Veer, Vijay

    2015-07-01

    Essential oil based insect repellents are environment friendly and provide dependable personal protection against the bites of mosquitoes and other blood-sucking insects. In the present study, optimized mixture of three essential oils was embedded into the ethylcellulose (EC) and polyvinylpyrrolidone (PVP K-30) polymers to develop essential oils based patch type mosquito repellent formulation. The developed formulation was characterized for various physico-chemical properties, oil release efficiency and essential oil-polymer interaction. Repellent activity of the formulation was evaluated against Ae. (S) albopictus mosquitoes and compared with commercially available synthetic insecticide based mosquito repellent cream Odomos(®) in the laboratory. The developed patches were 100% flat and there was no interaction between oil components and the excipients. Patches were smooth, homogenous and provided excellent mosquito repellent activity comparable to Odomos(®) under laboratory condition. Morphological and physico-chemical characterization indicated that the formulation was stable and suitable with the polymeric combination. The patch formulation did not show any inhalation toxicity in experimental Wistar rat. The repellent patches developed and evaluated currently, may provide a suitable, eco-friendly, acceptable and safe alternative to the existing synthetic repellent formulations for achieving protection against mosquitoes.

  18. Potential of eucalyptus oil as repellent against house rat, Rattus rattus.

    Science.gov (United States)

    Singla, Neena; Thind, Ramandeep Kaur; Mahal, Amrit Kaur

    2014-01-01

    Rodent repellents are chemicals which by taste or odour or possibly by both will prevent animal from feeding or gnawing. Such substances may be used in protecting an area from rodent infestation or in protecting packaged food, packing materials, electric cables, and other important vulnerable materials. Mature and healthy house rat, Rattus rattus of both sexes, was exposed to 5, 10, and 20% eucalyptus oil applied as spray in laboratory pens in bichoice tests. Each concentration was applied through three different modes of application, that is, daily, once, and alternatively in a week. Repellent effect of the oil was assessed based on food consumption from treated and untreated sides for four days. In overall, food consumption was significantly (P repellent effect of the oil at all the three concentrations tested. Repellent effect of the oil was, however, not found to differ significantly between the two sexes. Percent repellency in both male and female rats was apparently more with daily application of 5 and 10% eucalyptus oil. Present studies reveal the potential of eucalyptus oil in repelling away R. rattus; however, further studies may be conducted to enhance the persistence of repellent effect for longer period of time.

  19. 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.

  20. 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.

  1. 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.

  2. Repellency of aerosol and cream products containing fennel oil to mosquitoes under laboratory and field conditions.

    Science.gov (United States)

    Kim, Soon-Il; Chang, Kyu-Sik; Yang, Young-Cheol; Kim, Byung-Seok; Ahn, Young-Joon

    2004-11-01

    The repellency of fennel (Foeniculum vulgare Miller)-containing products (5% aerosol and 8% cream) against mosquitoes was compared with those of citronella oil, geranium oil and deet, as well as three commercial repellents, Baby Keeper cream containing IR3535, MeiMei cream containing citronella and geranium oils, and Repellan S aerosol containing 19% N,N-diethyl-m-toluamide (deet) under laboratory and field conditions. In a laboratory study with female Aedes aegypti (L), fennel oil exhibited good repellency in a release-in-cage test and repellency in skin and patch tests of the oil was comparable with those of citronella and geranium oils. In paddy field tests with five human volunteers, 5% and 8% fennel oil-containing aerosol and cream produced 84% and 70% repellency, respectively, at 90 min after exposure, whereas Baby Keeper cream and MeiMei cream gave 71% and 57% repellency at 90 min after exposure, respectively, and Repellan S aerosol gave 89% repellency at 210 min. The species and ratio of mosquitoes collected were the genera Culex (44.1%), Anopheles (42.2%), Aedes (7.8%) and Armigeres (5.9%). Fennel oil-containing products could be useful for protection from humans and domestic animals from vector-borne diseases and nuisance caused by mosquitoes.

  3. From Chemistry to Behavior. Molecular Structure and Bioactivity of Repellents against Ixodes ricinus Ticks.

    Directory of Open Access Journals (Sweden)

    Simone Del Fabbro

    Full Text Available Tick-borne zoonoses are considered as emerging diseases. Tick repellents represent an effective tool for reducing the risk of tick bite and pathogens transmission. Previous work demonstrated the repellent activity of the phenylpropanoid eugenol against Ixodes ricinus; here we investigate the relationship between molecular structure and repellency in a group of substances related to that compound. We report the biological activity of 18 compounds varying for the presence/number of several moieties, including hydroxyl and methoxy groups and carbon side-chain. Each compound was tested at different doses with a bioassay designed to measure repellency against individual tick nymphs. Both vapor pressure and chemical features of the tested compounds appeared to be related to repellency. In particular, the hydroxyl and methoxy groups as well as the side-chain on the benzene ring seem to play a role. These results are discussed in light of available data on chemical perception in ticks. In the course of the study new repellent compounds were identified; the biological activity of some of them (at least as effective as the "gold standard" repellent DEET appears to be very promising from a practical point of view.

  4. Repellent Activity of Apiaceae Plant Essential Oils and their Constituents Against Adult German Cockroaches.

    Science.gov (United States)

    Lee, Hyo-Rim; Kim, Gil-Hah; Choi, Won-Sil; Park, Il-Kwon

    2017-04-01

    We evaluated the repellent activity of 12 Apiaceae plant essential oils and their components against male and female adult German cockroaches, Blattella germanica L., to find new natural repellents. Of all the plant essential oils tested, ajowan (Trachyspermum ammi Sprague) and dill (Anethum graveolens L.) essential oils showed the most potent repellent activity against male and female adult German cockroaches. Repellent activities of chemicals already identified in active oils were also investigated. Of the compounds identified, carvacrol, thymol, and R-(-)-carvone showed >80% repellent activity against male and female adult German cockroaches at 2.5 µg/cm2. S-(+)-Carvone, (+)-dihydrocarvone, and terpinen-4-ol showed >70% repellent activity against male and female adult German cockroaches at 10 µg/cm2. Our results indicated that Apiaceae plant essential oils and their constituents have good potential as natural repellents against adult German cockroaches. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  5. 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,

  6. Efficacy of Thai herbal essential oils as green repellent against mosquito vectors.

    Science.gov (United States)

    Soonwera, Mayura; Phasomkusolsil, Siriporn

    2015-02-01

    Repellency activity of Thai essential oils derived from ylang ylang (Cananga odorata (Lamk.) Hook.f. & Thomson: Annonaceae) and lemongrass (Cymbopogon citratus (DC.) Stapf: Poaceae) were tested against two mosquito vectors, Aedes aegypti (L.) and Culex quinquefasciatus (Say). There were compared with two chemical repellents (DEET 20% w/w; Sketolene Shield(®) and IR3535, ethyl butylacetylaminopropionate 12.5% w/w; Johnson's Baby Clear Lotion Anti-Mosquito(®)). Each herbal repellent was applied in three diluents; coconut oil, soybean oil and olive oil at 0.33 μl/cm(2) on the forearm of volunteers. All herbal repellent exhibited higher repellent activity than IR3535 12.5% w/w, but lower repellent activity than DEET 20% w/w. The C. odorata oil in coconut oil exhibited excellent activity with 98.9% protection from bites of A. aegypti for 88.7±10.4 min. In addition, C. citratus in olive oil showed excellent activity with 98.8% protection from bites of C. quinquefasciatus for 170.0±9.0 min. While, DEET 20% w/w gave protection for 155.0±7.1-182.0±12.2 min and 98.5% protection from bites of two mosquito species. However, all herbal repellent provided lower repellency activity (97.4-98.9% protection for 10.5-88.7 min) against A. aegypti than C. quinquefasciatus (98.3-99.2% protection for 60-170 min). Our data exhibited that C. odorata oil and C. citratus oil are suitable to be used as green repellents for mosquito control, which are safe for humans, domestic animals and environmental friendly.

  7. 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.

  8. 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

    research aims to study SWR and its impact on water economy in relation with soil functioning and plant strategies for water uptake in pristine BW. Results are expected to shed light on the origin and implications of SWR in the area and provide useful information for improving ongoing restoration plans. Materials and methods The study was conducted in natural BW of WA. Soil samples were collected at different soil depths (0-1, 1-10, 20-30 and 40-50 cm). Rationale for sampling depths was based on the different severities of SWR at each layer under field conditions. Soil water repellency was assessed under laboratory conditions in oven-dry samples (48 h, 105 °C) and the chemical organic assemblage of bulked soil subsamples from each layer was analysed by direct analytical pyrolysis (Py-GC/MS). Results and discussion Soil water repellency distributed discontinuously through the soil profile. The first thin layer (0-1 cm) composed of coarse sand and litter, located immediately above Banksia root clusters, showed wettable conditions. In contrast, the relatively well aggregated soil layer where the Banksia cluster root system is located (1-10 cm) was severely water-repellent. The 20-30 and 40-50 cm deep layers rendered wettable or subcritically water-repellent. After Py-GC/MS analysis, major compounds were identified and grouped according to their probable biogenic origin (lignin, polysaccharides, peptides, etc.). Among other soil organic compounds, well resolved bimodal alkane/akene (C8-C31, maxima at C13 and C26) and fatty acids series (short-chained, C5-C9, and long-chained even-numbered C12-C18) were associated to the root cluster soil layer (1-10 cm). Also, a relatively high contribution of fire-derived polycyclic aromatic hydrocarbons (PAHs) was observed (7%), which is consistent with frequent fires occurring in BW. These results point to possible indirect links between organic substances released by roots and soil wettability involving soil microorganisms. Further

  9. Uninvited guests: traditional insect repellents in Estonia used against the clothes moth Tineola bisselliella, human flea Pulex irritons and bedbug Cimex lectularius.

    Science.gov (United States)

    Sõukand, Renata; Kalle, Raivo; Svanberg, Ingvar

    2010-01-01

    Extensive folklore records from pre-modern Estonia give us an excellent opportunity to study a variety of local plant knowledge and plant use among the peasantry in various parts of the country. One important biocultural domain where plant knowledge has been crucial was in the various methods of combating different ectoparasites that cohabited and coexisted with humans and their domestic animals. Some of these methods were widely known (world-wide, Eurasia, Europe, Baltic Rim), while others were more local. Here we discuss ways of reducing clothes moths Tineola bisselliella (Hummel) (Lepidoptera: Tineidae), human fleas Pulex irritons L. (Siphonaptera: Pulicidae) and bedbugs Cimex lectularius L. (Hemiptera: Cimicidae) with the help of plants. Various taxa used as traditional repellents have been identified. The use of plants as repellents and their toxic principles are also discussed from a comparative perspective.

  10. 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

  11. Uji Efek Repellent Nabati Ekstrak Bawang Putih (Allium sativum L.) Terhadap Tikus Putih Jantan Galur Wistar

    OpenAIRE

    Hutagaol, Yanti

    2016-01-01

    Repellent is a substance used as a repellent or insect or other pest deterrent. Repellent is one part of the pesticide.Pesticides are chemical substances used to kill or control pests. In fact, the use of chemical pesticides that are not rational cause negative effects in terms of the environment, especially in terms of human health. Garlic (Allium sativum L.) is a natural substance that has many benefits and rewards. Bulb of garlic (Allium sativum L.) contain substances that are toxic to ins...

  12. Mella (Olax zeylanica Leaves as an Eco-friendly Repellent for Storage Insect Pest Management

    Directory of Open Access Journals (Sweden)

    H. S. D. Fernando

    2013-04-01

    Full Text Available Among the cereals, rice is the most important staple food supplying energy requirements for mostof the worlds’ population. However during storage a loss of about 10-20% rice grains occurs due to storedgrain pests. Repellents are considered as the best source of protection against insect attack upon storedproducts as they have potential for the exclusion of stored product pests from grain, and therebypreventing insect feeding and oviposition on food materials. Various plant materials have been utilizedeffectively through time as safe and ecofriendly insect pest control measures due to their repellentactivity. The aim of the present study was to investigate the potential of powdered leaves and leaf extractsof Olax zeylanica as repellents against the rice weevil, Sitophilus oryzae. All the experiments were carriedout under laboratory conditions using 1-7 day old unsexed adults. Four different doses (1.0g, 3.0g, 5.0gand 7.0g.of powdered leaves were tested for fumigant repellency in a dual-choice bio-assay apparatus.Repellent action of leaf extracts was evaluated by means of an area preference test using methanol,ethanol and n- hexane as solvents. Repellent effect of powdered leaves against the adult rice weevils wasfound to be significantly high (P< 0.05 at all doses. The highest repellent effect was produced by 7.0g ofleaf powder resulting in repellency of 97%, while the lowest dose (1.0g also elicited more than 50%repellency in weevils indicating a very strong repellent action of the powdered leaves. In comparison,methanol extract of leaves produced the highest repellent effect (96% on weevils whereas n-hexaneextract elicited the lowest. Nevertheless, at higher concentrations all three extracts produced more or lesssignificantly similar repellent effect on the weevils. The findings of the present study suggest that certainactive materials of Olax zeylanica leaves have potential to act as a grain protectant and may be exploitedfor the control of

  13. Repellent effect of microencapsulated essential oil in lotion formulation against mosquito bites.

    Science.gov (United States)

    Misni, Norashiqin; Nor, Zurainee Mohamed; Ahmad, Rohani

    2017-01-01

    Many essential oils have been reported as natural sources of insect repellents; however, due to high volatility, they present low repellent effect. Formulation technique by using microencapsulation enables to control the volatility of essential oil and thereby extends the duration of repellency. In this study, the effectiveness of microencapsulated essential oils of Alpinia galanga, Citrus grandis and C. aurantifolia in the lotion formulations were evaluated against mosquito bites. Essential oils and N,N-Diethyl-3-methylbenzamide (DEET) were encapsulated by using interfacial pre- cipitation techniques before incorporation into lotion base to form microencapsulated (ME) formulation. The pure essential oil and DEET were also prepared into lotion base to produce non-encapsulated (NE) formulation. All the prepared formulations were assessed for their repellent activity against Culex quinquefasciatus under laboratory condition. Field evaluations also were conducted in three different study sites in Peninsular Malaysia. In addi- tion, Citriodiol® (Mosiquard®) and citronella-based repellents (KAPS®, MozAway® and BioZ Natural®) were also included for comparison. In laboratory conditions, the ME formulations of the essential oils showed no significant difference with regard to the duration of repellent effect compared to the microencapsulated DEET used at the highest con- centration (20%). It exhibited >98% repellent effect for duration of 4 h (p = 0.06). In the field conditions, these formulations demonstrated comparable repellent effect (100% for a duration of 3 h) to Citriodiol® based repellent (Mosiguard®) (p = 0.07). In both test conditions, the ME formulations of the essential oils presented longer duration of 100% repellent effect (between 1 and 2 h) compared to NE formulations. The findings of the study demonstrate that the application of the microencapsulation technique during the preparation of the formulations significantly increases the duration of the

  14. Odorant Receptor Modulation: Ternary Paradigm for Mode of Action of Insect Repellents

    Science.gov (United States)

    2012-01-01

    Dickens, J.C., 2010. Insect repellents : modulators of mosquito odorant receptor activity. PLoS ONE 5, e12138. Bohbot, J.D., Fu, L., Le, T.C., Chauhan...K.R., Cantrell, C.L., Dickens, J.C., 2011. Multiple activities of insect repellents on odorant receptors in mosquitoes . Med. Vet. Entomol. doi...detectors in Culex quinquefasciatus. Chem. Senses 32, 727e738. Syed, Z., Leal, W.S., 2008. Mosquitoes smell and avoid the insect repellent DEET. Proc

  15. POLY(N-VINYLPYRROLIDONE)-MODIFIED SURFACES REPEL PLASMA PROTEIN ADSORPTION

    Institute of Scientific and Technical Information of China (English)

    Xiao-li Liu; Zhao-qiang Wu; Dan Li; Hong Chen

    2012-01-01

    The present work aimed to study the interaction between plasma proteins and PVP-modified surfaces under more complex protein conditions.In the competitive adsorption of fibrinogen (Fg) and human serum albumin (HSA),the modified surfaces showed preferential adsorption of HSA.In 100% plasma,the amount of Fg adsorbed onto PVP-modified surfaces was as low as 10 ng/cm2,suggesting the excellent protein resistance properties of the modified surfaces.In addition,immunoblots of proteins eluted from the modified surfaces after plasma contact confirmed that PVP-modified surfaces can repel most plasma proteins,especially proteins that play important roles in the process of blood coagulation.

  16. Interacting tilt and kink instabilities in repelling current channels

    CERN Document Server

    Keppens, Rony; Xia, Chun

    2014-01-01

    We present a numerical study in resistive magnetohydrodynamics where the initial equilibrium configuration contains adjacent, oppositely directed, parallel current channels. Since oppositely directed current channels repel, the equilibrium is liable to an ideal magnetohydrodynamic tilt instability. This tilt evolution, previously studied in planar settings, involves two magnetic islands or fluxropes, which on Alfvenic timescales undergo a combined rotation and separation. This in turn leads to the creation of (near) singular current layers, posing severe challenges to numerical approaches. Using our open-source grid-adaptive MPI-AMRVAC software, we revisit the planar evolution case in compressible MHD, as well as its extension to 2.5D and full 3D scenarios. As long as the third dimension remains ignorable, pure tilt evolutions result which are hardly affected by out of plane magnetic field components. In all 2.5D runs, our simulations do show secondary tearing type disruptions throughout the near singular cur...

  17. 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.

  18. 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...

  19. 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

  20. Ovicidal and repellent activities of botanical extracts against Culex quinquefasciatus,Aedes aegypti and Anopheles stephensi(Diptera:Culicidae)

    Institute of Scientific and Technical Information of China (English)

    Govindarajan; M; Mathivanan; T; Elumalai; K; Krishnappa; K; Anandan; A

    2011-01-01

    Objective:To determine the ovicidal and repellent activities of methanol leaf extract of Ervatamia coronaria(E.coronaria) and Caeslpinia pulckerrima(C.pulcherrima) against Culex quinquefasciatus(Cx.quinquefasciatus),Aedes aegypti(Ae.aegypti) and Anopheles stephensi(An. stephensi).Methods:The ovicidal activity was determined against three mosquito species at various concentrations ranging from 50-450 ppm under the laboratory conditions.The hatch rates were assessed 48 h after treatment.The repellent efficacy was determined against three mosquito species at three concentrations viz.,1.0,2.5 and 5.0 mg/cm under the laboratory conditions. Results:The crude extract of E.coronaria exerted zero hatchability(100%mortality) at 250.200 and 150 ppm for Cx.quinqitefasciatus,Ae.aegypti and An.stephensi,respectively.The crude extract of C.pulchenima exerted zero hatchability(100%mortality) at 375.300 and 225 ppm for Cx.quinquefasciatus,Ae.aegypti and An.Stephensi,respectively.The methanol extract of E. coronaria found to be more repellenct than C.pukherrima extract.A higher concentration of 5.0 mg/cm~2 provided 100%protection up to 150.180 and 210 min against Cx.quinquefasciatus,Ae. aegypti and An.stephensi,respectively.The results clearly showed that repellent activity was dose dependent.Conclusions:From the results it can be concluded the crude extracts of E.coronaria and C.pukherrima are an excellent potential for controlling Cx.quinquefasciatus,Ae.aegypti and An.stephensi mosquitoes.

  1. Interacting tilt and kink instabilities in repelling current channels

    Energy Technology Data Exchange (ETDEWEB)

    Keppens, R.; Porth, O.; Xia, C., E-mail: rony.keppens@wis.kuleuven.be [Centre for mathematical Plasma-Astrophysics, Department of Mathematics, KU Leuven, B-3001 Leuven (Belgium)

    2014-11-01

    We present a numerical study in resistive magnetohydrodynamics (MHD) where the initial equilibrium configuration contains adjacent, oppositely directed, parallel current channels. Since oppositely directed current channels repel, the equilibrium is liable to an ideal magnetohydrodynamic tilt instability. This tilt evolution, previously studied in planar settings, involves two magnetic islands or flux ropes, which on Alfvénic timescales undergo a combined rotation and separation. This in turn leads to the creation of (near) singular current layers, posing severe challenges to numerical approaches. Using our open-source grid-adaptive MPI-AMRVAC software, we revisit the planar evolution case in compressible MHD, as well as its extension to two-and-a-half-dimensional (2.5D) and full three-dimensional (3D) scenarios. As long as the third dimension can be ignored, pure tilt evolutions result that are hardly affected by out of plane magnetic field components. In all 2.5D runs, our simulations do show secondary tearing type disruptions throughout the near singular current sheets in the far nonlinear saturation regime. In full 3D runs, both current channels can be liable to additional ideal kink deformations. We discuss the effects of having both tilt and kink instabilities acting simultaneously in the violent, reconnection-dominated evolution. In 3D, both the tilt and the kink instabilities can be stabilized by tension forces. As a concrete space plasma application, we argue that interacting tilt-kink instabilities in repelling current channels provide a novel route to initiate solar coronal mass ejections, distinctly different from the currently favored pure kink or torus instability routes.

  2. Assessment of dermal absorption of DEET-containing insect repellent and oxybenzone-containing sunscreen using human urinary metabolites.

    Science.gov (United States)

    Yiin, Lih-Ming; Tian, Jia-Ni; Hung, Chien-Che

    2015-05-01

    Mutual enhancement of dermal absorption of N,N-diethyl-m-toluamide (DEET) and oxybenzone (OBZ) has been reported recently with DEET and OBZ being active ingredients of insect repellent and sunscreen, respectively. To assess the reported enhancing effect directly, we used human urinary metabolites as biomarkers; besides, we also sought to determine the best way for concurrent use of these two products without extra absorption of either. Four dermal application methods were used: DEET only (S1), OBZ only (S2), DEET on top of OBZ (S3), and OBZ on top of DEET (S4). Among the study methods, there was a significant difference (p = 0.013), which was attributed to the difference between S1 and S4, suggesting that applying OBZ over DEET on the skin lead to significantly higher absorption of DEET. Using both products in reverse order, (S3) did not result in extra DEET absorption significantly. As for OBZ permeation, no significant difference was observed among the methods. In summary, the enhancement of DEET absorption is confirmed for OBZ being applied over DEET on the skin; should concurrent use of both be necessary, applying sunscreen (OBZ) first and then insect repellent (DEET) with a 15-min interval is recommended.

  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. Suicides and suicide attempts among active component members of the U.S. Armed Forces, 2010-2012; methods of self-harm vary by major geographic region of assignment.

    Science.gov (United States)

    Corr, William P

    2014-10-01

    This report analyzed data from the Department of Defense Suicide Event Report program about suicide events (suicide attempts and suicides) among active component service members during 2010-2012. Most attempts (85.2%) and suicides (83.5%) occurred among service members stationed in the U.S. Drugs were identified as the method of self-harm in 54.8% of attempts but in only 3.6% of suicides. Firearms were the leading method of suicide in both the U.S. and combat zones (61.1% and 97.2%, respectively) but accounted for only 5.4% of suicides in those stationed in Europe/Asia. Hanging/asphyxiation (22.9% overall) was the second most common method in suicides. For suicides using firearms, the rates of suicide and the types of firearm used varied according to service members' geographically related access to firearms. Challenges to reducing the frequency of service member suicides by firearms are discussed.

  5. Member end releases in framed structures

    Science.gov (United States)

    Stallings, J. M.

    1993-02-01

    Discontinuities such as internal hinges are commonly encountered in framed structures. A general method of including discontinuities in stiffness method analyses of planar frames by the release of member end forces is developed. Modifications are made to the member stiffness matrix and equivalent joint load vector to account for the released end forces. A FORTRAN algorithm is given that makes the necessary modifications to the member stiffness matrix and equivalent joint load vector for the standard planar frame member. The algorithm allows combinations of up to three member end forces to be released (specified at zero or nonzero values). An algorithm is also given that calculates the unknown member end displacements at the released member end forces. Numerical examples are given to illustrate the uses and capabilities of the algorithms.

  6. ANALYSIS AND APPLIED STUDY OF DYNAMIC CHARACTERISTICS OF CHAOTIC REPELLER IN COMPLICATED SYSTEM

    Institute of Scientific and Technical Information of China (English)

    MA Jun-hai; REN Biao; CHEN Yu-shu

    2005-01-01

    Fractal characters and fractal dimension of time series created by repeller in complicated system were studied and the time series were reconstructed by applying the theory of phase space reconstruction for chaotic time series. The influence of zero-mean treatment, Fourier filter on prediction for time series were studied. The choice of prediction sample affects the relative error and the prediction length which were also under good concern. The results show that the model provided here are practical for the modeling and prediction of time series created by chaotic repellers. Zero-mean treatment has changed prediction result quantitatively for chaotic repeller sample data. But using Fourier filter may decrease the prediction precision. This is theoretical and practical for study on chaotic repeller in complicated system.

  7. 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...

  8. Repellent and Anti-quorum Sensing Activity of Six Aromatic Plants Occurring in Colombia.

    Science.gov (United States)

    Cervantes-Ceballos, Leonor; Caballero-Gallardo, Karina; Olivero-Verbel, Jesus

    2015-10-01

    Essential oils (EOs) are widely used as biopesticides and to control bacterial infections. This study describes the ability of six EOs isolated from plants cultivated in Colombia to perform as repellents against Ulomoides dermestoides and as quorum sensing (QS) inhibitors. EOs from Aloysia triphylla, Cymbopogon nardus, Lippia origanoides, Hyptis suaveolens, Swinglea glutinosa and Eucalyptus globulus were repellents classified as Class IV, IV, IV, III, II, and II, respectively, whereas the commercial repellent IR3535 only reached Class II after 2 h exposure. All EOs presented small, but significant inhibitory properties against the QS system in Escherichia coli (pJBA132) at 25 μg/mL after 4 h exposure. These data suggest evaluated EOs from Colombia are sustainable, promising new sources of natural repellents and could be important as anti-quorum sensing molecules.

  9. Wash resistance and repellent properties of Africa University mosquito blankets against mosquitoes

    Directory of Open Access Journals (Sweden)

    N. Lukwa

    2013-04-01

    Full Text Available The effect of permethrin-treated Africa University (AU mosquito blankets on susceptible female Anopheles gambiae sensu lato mosquitoes was studied under laboratory conditions at Africa University Campus in Mutare, Zimbabwe. Wash resistance (ability to retain an effective dose that kills ≥80% of mosquitoes after a number of washes and repellence (ability to prevent ≥80% of mosquito bites properties were studied. The AU blankets were wash resistant when 100% mortality was recorded up to 20 washes, declining to 90% after 25 washes. Untreated AU blankets did not cause any mortality on mosquitoes. However, mosquito repellence was 96%, 94%, 97.9%, 87%, 85% and 80.7% for treated AU blankets washed 0, 5, 10, 15, 20 and 25 times, respectively. Mosquito repellence was consistently above 80% from 0-25 washes. In conclusion, AU blankets washed 25 times were effective in repelling and killing An. gambiae sl mosquitoes under laboratory conditions.

  10. Repellent Action of Carapa guianensis and Caesalpinia ferrea for flies species of Calliphoridae family

    Directory of Open Access Journals (Sweden)

    Ciciane Pereira Marten Fernandes

    2016-05-01

    Full Text Available ABSTRACT: Myiases occur by the infestation of fly larvae in tissues of live vertebrate animals, resulting in economic loss. Phytotherapy is considered an important alternative in the control of insects, which may reduce the economic impacts . Carapa guianensis is a plant that has been studied as a repellent against mosquitoes and Caesalpinia ferrea is reported in tropical climates, and there are few studies about its repellent action. The present study was designed to evaluate the repellent action of s C. guianensis and C. ferrea plants on flies species of the Calliphoridae family. W.O.T. traps containing deteriorated bovine liver and herbs cream of at concentrations of 20 and 50% were used to catch the flies. It was reported that the creams containing C. ferrea at concentrations of 20 and 50% and C. guianensis at the concentration of 50% have repellent effect against species of Calliphoridae family.

  11. Repellent activity of constituents identified in Foeniculum vulgare fruit against Aedes aegypti (Diptera: Culicidae).

    Science.gov (United States)

    Kim, Do-Hyoung; Kim, Soon-Il; Chang, Kyu-Sik; Ahn, Young-Joon

    2002-11-20

    The repellent activity of materials derived from the methanol extract of fruits from Foeniculum vulgareagainst hungry Aedes aegypti females was examined using skin and patch tests and compared with that of the commercial N,N-diethyl-m-toluamide (deet) and (Z)-9-octadecenoic acid. The biologically active constituents of the Foeniculum fruits were characterized as (+)-fenchone and (E)-9-octadecenoic acid by spectroscopic analyses. Responses varied according to compound, dose, and exposure time. In a skin test with female mosquitoes, at a dose of 0.4 mg/cm(2), (+)-fenchone and (Z)-9-octadecenoic acid exhibited moderate repellent activity at 30 min after treatment, whereas deet provided >1 h of protection against adult mosquitoes at 0.2 mg/cm(2). (Z)-9-Octadecenoic acid was a more potent repellent agent than (E)-9-octadecenoic acid. (+)-Fenchone and (E)-9-octadecenoic acid merit further study as potential mosquito repellent agents or as lead compounds.

  12. 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.

  13. Evaluation of Cardboard Coated with Natural Substances in Combination with Ink on Rat Repellency

    National Research Council Canada - National Science Library

    Sarinee Kalandakanond-Thongsong; Suwaporn Daendee; Boonrit Thongsong; Vivat Chavananikul

    2011-01-01

      An effective repellent for rodent-proof cardboard-container is considered interesting especially in packaging and transport business as rat usually gnaws through the container, resulting in food...

  14. Tetranychus urticae‐triggered responses promote genotype‐dependent conspecific repellence or attractiveness in citrus

    National Research Council Canada - National Science Library

    Agut, Blas; Gamir, Jordi; Jaques, Josep A; Flors, Victor

    2015-01-01

    .... In this study, we observed that the release of T. urticae herbivore‐induced plant volatiles ( HIPV s) from sour orange plants has a marked repellent effect on conspecific mites associated with the production of the terpenes...

  15. Electronic technology of mosquitoes control and repelling%电子驱灭蚊蝇技术的研究

    Institute of Scientific and Technical Information of China (English)

    王钧; 陈明媛

    2013-01-01

      蚊蝇等害虫对人类的健康构成了危害。蚊香、灭蚊剂等传统的驱灭蚊子方法不仅使它们产生了抗药性,而且会造成环境污染[1]。本文通过分析蚊子的生活特性,利用现代电子技术、仿生学和物理技术等非化学方法实现了绿色驱灭蚊子。经实验研究,该方法比传统的方法更加环保、高效。%Pests such as mosquitoes are harm to human's health. Driving and killing mosquitoes by mosquito-repellent incense and anopheline in the traditional ways not only cause their developed resistance, and will cause environmental pollution [1]. Through analysis of the characteristics of mosquitoes, the modern electronic technology, bionics and physical technology, not chemical methods, have been realized controlling and repelling mosquitoes. After experimental research, the idea is better than the traditional method, with more environmental protection, high efficiency.

  16. Bioactivity-Guided Investigation of Geranium Essential Oils as Natural Tick Repellents

    Science.gov (United States)

    2013-03-25

    from amyris essential oil suggested that it had potential as a repellent against Aedes aegypti (L.). While (−)-10-epi-γ- eudesmol has been tested against...M.; Hayes, E. B.; Ertel, S.; Shapiro, E. D. Effectiveness of personal protective measures to prevent Lyme disease. Emerging Infect. Dis. 2008, 14...picaridin. Regul. Toxicol. Pharmacol. 2008, 51, 31−36. (11) Shapiro, R. Prevention of vector transmitted diseases with clove oil insect repellent. J. Pediatr

  17. Phoenix dactylifera L. spathe essential oil: chemical composition and repellent activity against the yellow fever mosquito.

    Science.gov (United States)

    Demirci, Betül; Tsikolia, Maia; Bernier, Ulrich R; Agramonte, Natasha M; Alqasoumi, Saleh I; Al-Yahya, Mohammed A; Al-Rehaily, Adnan J; Yusufoglu, Hasan S; Demirci, Fatih; Başer, K Hüsnü Can; Khan, Ikhlas A; Tabanca, Nurhayat

    2013-12-01

    Date palm, Phoenix dactylifera L. (Arecaceae), grows commonly in the Arabian Peninsula and is traditionally used to treat various diseases. The aim of the present study was to identify chemical composition of the essential oil and to investigate the repellent activity. The essential oil of P. dactylifera was obtained by hydrodistillation from the spathe, a specialized leaf structure that surrounds the pollinating organs of the palm. The oil was subsequently analyzed by GC-FID and GC-MS. The oil showed promising repellent activity against yellow fever mosquito - Aedes aegypti. Sixteen components were characterized, constituting 99% of the oil. The main components were 3,4-dimethoxytoluene (73.5%), 2,4-dimethoxytoluene (9.5%), β-caryophyllene (5.5%), p-cresyl methyl ether (3.8%), and caryophyllene oxide (2.4%). The minimum effective dosage (MED) for repellency for the P. dactylifera oil was 0.051mg/cm(2), which had moderately lower potency compared to reference standard N,N-diethyl-3-methylbenzamide, DEET (0.018mg/cm(2)) in the "cloth patch assay". The five major compounds were individually assayed for repellency to determine to what extent each is responsible for repellency from the oil. 3,4-Dimethoxytoluene and 2,4-dimethoxytoluene showed the best repellent activity with the same MED value of 0.063mg/cm(2), respectively. The results indicate that these two constituents which comprise a large proportion of the P. dactylifera oil (83%) are likely responsible for the observed repellent activity. In this aspect, the P. dactylifera spathe oil is a sustainable, promising new source of natural repellents.

  18. Advancing the science of EPA guidelines for sponsor-financed topical insect repellent efficacy studies.

    Science.gov (United States)

    Young, Linda J; Fisher, Celia B

    2010-02-01

    In 1999, the US Environmental Protection Agency (EPA) published guidelines for product performance testing of skin-applied insect repellents, which provide guidance for topical insect repellent efficacy studies. EPA subsequently uses these sponsor-financed studies in their evaluation of proposed label claims. This paper reviews some of the statistical flaws in the proposed revisions to these guidelines and suggests possible improvements. This review is important because EPA's revisions to the 1999 guidelines do not address these issues.

  19. An Indexed Combinatorial Library: The Synthesis and Testing of Insect Repellents

    Science.gov (United States)

    Miles, William H.; Gelato, Kathy A.; Pompizzi, Kristen M.; Scarbinsky, Aislinn M.; Albrecht, Brian K.; Reynolds, Elaine R.

    2001-04-01

    An indexed combinatorial library of amides was prepared by the reaction of amines and acid chlorides. A simple test for insect repellency using fruit flies (Drosophila melanogaster) allowed the determination of the most repellent sublibraries. The student-generated data were collected and analyzed to determine the most active amide(s) in the library. This experiment illustrates the fundamentals of combinatorial chemistry, a field that has undergone explosive growth in the last decade.

  20. Preliminary Analysis of Several Attractants and Spatial Repellents for the Mosquito, Aedes albopictus using an Olfactometer

    OpenAIRE

    Hao, Huiling; Sun, Jingcheng; Dai, Jianqing

    2012-01-01

    Mosquito attractants and spatial repellents hold great promise in controlling mosquito pests. In assessing the effectiveness of mosquito attractants and repellents, a good olfactometer system, and optimized testing conditions, are essential. In this research, we demonstrated the usefulness of an olfactometer system, and optimized testing conditions for Aedes albopictus (Diptera: Culicidae). We found no significant difference in the biting activity of the insect between 8:00 and 22:00. Further...

  1. 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...

  2. In vivo imaging of C. elegans ASH neurons: cellular response and adaptation to chemical repellents

    OpenAIRE

    Hilliard, Massimo A.; Apicella, Alfonso J.; Kerr, Rex; Suzuki, Hiroshi; Bazzicalupo, Paolo; Schafer, William R

    2004-01-01

    ASH sensory neurons are required in Caenorhabditis elegans for a wide range of avoidance behaviors in response to chemical repellents, high osmotic solutions and nose touch. The ASH neurons are therefore hypothesized to be polymodal nociceptive neurons. To understand the nature of polymodal sensory response and adaptation at the cellular level, we expressed the calcium indicator protein cameleon in ASH and analyzed intracellular Ca2+ responses following stimulation with chemical repellents, o...

  3. 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.

  4. Efficacy comparison of the repellent between laboratories%实验室间的驱避剂药效对比研究

    Institute of Scientific and Technical Information of China (English)

    郑卫青; 柳小青; 马红梅; 陶卉英; 刘仰青; 陈超; 姜志宽

    2011-01-01

    目的 比较不同实验室对同一种蚊虫、同一种驱避剂的药效检测结果.方法 GB/T13917.9-2009农药登记用卫生杀虫剂室内药效试验与评价-驱避剂.结果 甲实验室检测的A、B驱避剂平均有效保护时间分别为5.75 h、4.25 h;乙实验室检测的A、B驱避剂平均有效保护时间分别为5.50 h、4.25 h.结论 实验室间的驱避药效试验结果没有显著性差异,乙实验室可以开展相关产品的药效评价.%Objective To compare the efficacy of repellent tested by two laboratories. Methods According to the method of GB/T13917.9 -2009. Results The average effectively repellent time of repellet A and B tested by No. 1 laboratory were 5.75 and 4. 25 h respectively. The average effectively repellent time of repellet A and B tested by No. 2 laboratory were 5.50 and 4. 25 h respectively. Conclusion There is no statistical difference in the efficacy of repellent tested by two laboratories.

  5. Repellent activity of essential oils against cockroaches (Dictyoptera: Blattidae, Blattellidae, and Blaberidae) in Thailand.

    Science.gov (United States)

    Thavara, Usavadee; Tawatsin, Apiwat; Bhakdeenuan, Payu; Wongsinkongman, Prapai; Boonruad, Thidarat; Bansiddhi, Jaree; Chavalittumrong, Pranee; Komalamisra, Narumon; Siriyasatien, Padet; Mulla, Mir S

    2007-07-01

    Seven commercial essential oils extracted from the plant species Boesenbergia rotunda (L.) Mansf., Citrus hystrix DC., Curcuma longa L., Litsea cubeba (Lour.) Pers., Piper nigrum L., Psidium guajava L. and Zingiber officinale Roscoe, and naphthalene as a control, were evaluated for repellent activity against the three cockroach species Periplaneta americana (L.), Blattella germanica (L.) and Neostylopyga rhombifolia (Stoll) under laboratory conditions. The essential oil derived from Citrus hystrix showed the best repellency over other candidate essential oils and naphthalene. The essential oil of Citrus hystrix exhibited complete repellency (100%) against P. americana and B. germanica, and also showed the highest repellency (among the essential oils tested) of about 87.5% against N. rhombifolia under laboratory conditions. In the field, Citrus hystrix essential oil formulated as a 20% active ingredient in ethanol and some additives provided satisfactory repellency of up to 86% reduction in cockroaches, mostly P. americana and N. rhombifolia with a residual effect lasting a week after treatment. Citrus hystrix essential oil has good potential for being used as a cockroach repellent. Further improvements in efficacy and residual activity may be realized with appropriate formulations.

  6. Repellent activity of plant-derived compounds against Amblyomma cajennense (Acari: Ixodidae) nymphs.

    Science.gov (United States)

    Soares, Sara Fernandes; Borges, Lígia Miranda Ferreira; de Sousa Braga, Raquel; Ferreira, Lorena Lopes; Louly, Carla Cristina Braz; Tresvenzol, Leonice Manrique Faustino; de Paula, José Realino; Ferri, Pedro Henrique

    2010-01-20

    Repellence responses of Amblyomma cajennense nymphs to callicarpenal, intermedeol, Hyptis suaveolens essential oil, extract of Melia azedarach, Cymbopogon nardus, Spiranthera odoratissima, Chenopodium ambrosioides, Ageratum conyzoides, Mentha pulegium, Ruta graveolens, and Memora nodosa were studied. Among these the extract of C. nardus stood out because of the long-lasting repellence, maintaining, in the highest concentration, 35h of protection against 90% of the nymphs. The essential oil of H. suaveolens and the extracts of C. ambrosioides and A. conyzoides showed good repellence index (66%) when applied in high concentrations. However, greater protection could be obtained at higher concentrations but with a shorter repellence time. Callicarpenal, intermedeol, extract of M. Pulegium, and M. nodosa leaves showed moderate repellence in high concentrations. Extracts from M. azedarach, R. graveolens, S. odoratissima, and M. nodosa roots showed little or no repellent effect. These results show that some plant extracts may represent a promising alternative in the control of infestations by A. cajennense. Copyright 2009 Elsevier B.V. All rights reserved.

  7. 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.

  8. Sustained efficacy of the novel topical repellent TT-4302 against mosquitoes and ticks.

    Science.gov (United States)

    Bissinger, B W; Kennedy, M K; Carroll, S P

    2016-03-01

    Mosquitoes and ticks are blood-feeding pests of humans and animals that can vector many important aetiological agents of disease. Previous research demonstrated that TT-4302 (Guardian(®) Wilderness) containing 5% geraniol applied to human subjects gave 5-6 h of repellency against mosquitoes (depending on species) and was repellent to ticks in vitro. This study was conducted to obtain an independent third-party evaluation of TT-4302 against Stegomyia aegypti (= Aedes aegypti) (Diptera: Culicidae) mosquitoes and to test the efficacy of the product in the field against ticks. TT-4302 provided an average of 6.5 h of repellency of ≥ 95% [Weibull mean protection time: 7.4 h, 95% confidence interval (CI) 5.8-11.3 h] for St. aegypti, whereas a 15% DEET formulation provided 4.7 h of repellency (Weibull mean protection time: 5.2 h, 95% CI 3.7-6.9 h). In tick field trials, the efficacy of TT-4302 did not differ significantly from that of a 25% DEET formulation against Amblyomma americanum (Ixodida: Ixodidae). TT-4302 was 81.3% repellent at 2.5 h after application, whereas DEET was 77.2% repellent at the same time-point. Results at 3.5 h after application were 71.4% for TT-4302 and 72.9% for DEET.

  9. Repellent constituents of essential oil of Cymbopogon distans aerial parts against two stored-product insects.

    Science.gov (United States)

    Zhang, Jing Song; Zhao, Na Na; Liu, Qi Zhi; Liu, Zhi Long; Du, Shu Shan; Zhou, Ligang; Deng, Zhi Wei

    2011-09-28

    The screening for bioactive principles from several Chinese medicinal herbs showed that the essential oil of Cymbopogon distans aerial parts possessed strong repellency against the booklouse, Liposcelis bostrychophila , and the red flour beetle, Tribolium castaneum . A total of 36 components of the essential oil were identified by GC and GC-MS. trans-Geraniol (16.54%), (R)-citronellal (15.44%), (+)-citronellol (11.51%), and α-elemol (9.06%) were the main components of the essential oil followed by β-eudesmol (5.71%) and (+)-limonene (5.05%). From the essential oil, four monoterpenes were isolated by bioassay-guided fractionation. The compounds were identified as limonene, citronellol, citronellal, and trans-geraniol. Geraniol and citronellol were strongly repellent against the booklouse, L. bostrychophila, whereas citronellal and limonene exhibited weak repellency against the booklouse. Geraniol and citronellol exhibited comparable repellency against the booklouse relative to the positive control, DEET. Moreover, geraniol and citronellol exhibited stronger repellency against the red flour beetle than DEET, whereas the two other compounds showed the same level of repellency against the red flour beetle compared with DEET.

  10. Repellent Activity of Eight Essential Oils of Chinese Medicinal Herbs t oBlattella germanica L.

    Directory of Open Access Journals (Sweden)

    Zhi Long Liu

    2011-01-01

    Full Text Available Eight e ssential oil s of Chinese medicinal herbs ( Angelica sinensis , Curuma aeruginosa , Cyperus rotundus , Eucalyptus robusta , Illicium verum , Lindera aggregate , Ocimum basilicum , and Zanthoxylum bungeanum w ere obtained by hydrodistillation and the essential oil of Eucalyptus robusta leaves was analyzed by gas chromatography-mass spectrometry (GC-MS. A total of 22 components of the essential oil of E. robusta were identified. The principal compounds in E . robusta essential oil were α- p inene (28.74% and 1,8- c ineole (27.18%, spathulenol (6.63%, globulol (6.53% and ρ - m enth-1-en-8-ol (5.20%. The 8 essential oil s and two main components, α -pinene and 1, 8-cineole of the essential oil of E. robusta were evaluated repellency against nymphs of the German cockroaches . Strong repellency (Class V was obtained for Cyperus rotundus and Eucalyptus robusta essential oils and α- p inene and 1, 8- c ineole . However, Illicium verum essential oil possessed weak (Class I repellency. At a concentration of 5 ppm, all the 8 essential oils and the two compounds showed repellent activity after one hour exposure. At 1 ppm concentration, essential oil of Cyperus rotundus showed strong repellency and Class IV repellency was obtained for essential oil of E. robusta and the two compounds after one hour exposure. However, essential oils of I . verum and Lindera aggregata showed strong attractiveness to the German cockroaches at a concentration of 1 ppm .

  11. Nepetalactones from essential oil of Nepeta cataria represent a stable fly feeding and oviposition repellent.

    Science.gov (United States)

    Zhu, J J; Berkebile, D R; Dunlap, C A; Zhang, A; Boxler, D; Tangtrakulwanich, K; Behle, R W; Baxendale, F; Brewer, G

    2012-06-01

    The stable fly, Stomoxys calcitrans (L.) (Diptera: Muscidae), is one of the most serious pests to livestock. It feeds mainly on cattle and causes significant economic losses in the cattle industry. Standard stable fly control involving insecticides and sanitation is usually costly and often has limited effectiveness. As we continue to evaluate and develop safer fly control strategies, the present study reports on the effectiveness of catnip (Nepeta cataria L.) oil and its constituent compounds, nepetalactones, as stable fly repellents. The essential oil of catnip reduced the feeding of stable flies by >96% in an in vitro bioassay system, compared with other sesquiterpene-rich plant oils (e.g. amyris and sandalwood). Catnip oil demonstrated strong repellency against stable flies relative to other chemicals for repelling biting insects, including isolongifolenone, 2-methylpiperidinyl-3-cyclohexen-1-carboxamide and (1S,2'S)-2-methylpiperidinyl-3-cyclohexen-1-carboxamide. The repellency against stable flies of the most commonly used mosquito repellent, DEET, was relatively low. In field trials, two formulations of catnip oil provided >95% protection and were effective for up to 6 h when tested on cattle. Catnip oil also acted as a strong oviposition repellent and reduced gravid stable fly oviposition by 98%. Published 2011. This article is a U.S. Government work and is in the public domain in the USA.

  12. Defensive Metabolites from Antarctic Invertebrates: Does Energetic Content Interfere with Feeding Repellence?

    Science.gov (United States)

    Núñez-Pons, Laura; Avila, Conxita

    2014-01-01

    Many bioactive products from benthic invertebrates mediating ecological interactions have proved to reduce predation, but their mechanisms of action, and their molecular identities, are usually unknown. It was suggested, yet scarcely investigated, that nutritional quality interferes with defensive metabolites. This means that antifeedants would be less effective when combined with energetically rich prey, and that higher amounts of defensive compounds would be needed for predator avoidance. We evaluated the effects of five types of repellents obtained from Antarctic invertebrates, in combination with diets of different energetic values. The compounds came from soft corals, ascidians and hexactinellid sponges; they included wax esters, alkaloids, a meroterpenoid, a steroid, and the recently described organic acid, glassponsine. Feeding repellency was tested through preference assays by preparing diets (alginate pearls) combining different energetic content and inorganic material. Experimental diets contained various concentrations of each repellent product, and were offered along with control compound-free pearls, to the Antarctic omnivore amphipod Cheirimedon femoratus. Meridianin alkaloids were the most active repellents, and wax esters were the least active when combined with foods of distinct energetic content. Our data show that levels of repellency vary for each compound, and that they perform differently when mixed with distinct assay foods. The natural products that interacted the most with energetic content were those occurring in nature at higher concentrations. The bioactivity of the remaining metabolites tested was found to depend on a threshold concentration, enough to elicit feeding repellence, independently from nutritional quality. PMID:24962273

  13. 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.

  14. 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.

  15. Structural requirements for repellency: norsesquiterpenes and sesquiterpenoid derivatives of nootkatone against the Formosan subterranean termite (Isoptera: Rhinotermitidae).

    Science.gov (United States)

    Zhu, Betty C R; Henderson, Gregg; Sauer, Anne M; Crowe, William; Laine, Roger A

    2010-08-01

    Research has shown that the family of grapefruit flavors called nootkatones have significant repellant and toxic effects to Formosan subterranean termites (Coptotermes formosanus Shiraki). Nineteen synthetic nootkatone derivatives, along with three commercially available nootkatone derivatives, were tested for repellent activity against C. formosanus by a choice assay in a petri dish with a two-step triage procedure. Based on the repellency threshold value, the relationships between structure and activity are discussed. Four derivatives of nootkatone have very high repellency and toxicity to C. formosanus, 9 times the potency of the primary compound nootkatone. Four other compounds have between 2 and 3 times the repellency of nootkatones, and three compounds are equal in their repellency to nootkatone. Copyright (c) 2010 Society of Chemical Industry.

  16. Development of Natural Insect-Repellent Loaded Halloysite Nanotubes and their Application to Food Packaging to Prevent Plodia interpunctella Infestation.

    Science.gov (United States)

    Kim, Jungheon; Park, No-Hyung; Na, Ja Hyun; Han, Jaejoon

    2016-08-01

    The aims of this study were to develop insect-proof halloysite nanotubes (HNTs) and apply the HNTs to a low-density polyethylene (LDPE) film that will prevent Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae), commonly known as Indian mealmoth, from infesting the food. Clove bud oil (CO), an insect repellent, was encapsulated into HNTs with polyethylenimine (PEI) to bring about controlled release of CO. Chemical composition and insecticidal effect of CO were examined. The Fourier transform infrared (FTIR) spectrum of encapsulated CO was confirmed. The surface charges of uncoated HNTs (HNTs/CO) and coated HNTs with PEI by the layer-by-layer (LBL) method (HNTs/CO/LBL) were determined to be -37.23 and 36.33 mV, respectively. HNTs/CO/LBL showed slow, controlled release of CO compared to HNTs/CO. After 30 d, the residual amounts of CO in HNTs/CO and HNTs/CO/LBL were estimated to be 13.43 and 28.66 mg/g, respectively. HNTs/CO/LBL showed the most sustainable repellent effect. HNTs applied to gravure printing ink solution did not affect mechanical, optical, or thermal properties of the developed film. Gravure-printed LDPE film containing HNTs/CO/LBL displayed the greatest preventive effect on insect penetration, indicating its potential for use as insect-resistant food packaging materials.

  17. Repellent Activity of the Essential Oil from the Heartwood of Pilgerodendron uviferum (D. Don) Florin against Aegorhinus superciliosus (Coleoptera: Curculionidae).

    Science.gov (United States)

    Espinoza, Javier; Urzúa, Alejandro; Tampe, Jocelyne; Parra, Leonardo; Quiroz, Andrés

    2016-04-22

    The weevil Aegorhinus superciliosus Guérin (Coleoptera: Curculionidae), which is endemic to Central-Southern Chile and Argentina, is one of the major berry pests in Chile and the most important pest in the La Araucanía Region (38°44'9″S, 72°35'25″W). Due to the poor effectiveness and problems surrounding the implementation of the traditional control methods using organophosphate and carbamate insecticides, new strategies for controlling this pest are needed. In this communication, we evaluated the behavioral responses of male and female A. superciliosus to volatile compounds released from the essential oil (EO) obtained from the heartwood of Pilgerodendron uviferum (D. Don) Florin using olfactometric bioassays. The composition of the EO was analyzed using gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). According to these analyses, δ-cadinol (24.16%), cubenol (22.64%), 15-copaenol (15.46%) and δ-cadinene (10.81%) were the principal components of the EO. The Pilgerodendron uviferum EO, which is almost exclusively composed of sesquiterpenes (99.5%), exhibited a repellent effect against A. superciliosus adults, regardless of the sex or concentration used (56.6 mg/cm³ and 1.58 × 10(-2) mg/cm³). The EO has low volatility and greater persistence than the EOs composed of monoterpenes and is considered a good model in the search for raspberry weevil repellents.

  18. 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.

  19. 香茅精油微胶囊对锦纶织物的驱蚊整理%Mosquito repellent finishing of nylon fabric with microencapsulated citronella oil

    Institute of Scientific and Technical Information of China (English)

    刁水华; 化丹丹; 蒋耀兴; 谢洪德

    2015-01-01

    用复凝聚法制成的香茅精油微胶囊整理锦纶织物,研究了整理织物的驱蚊性;将覆盖整理织物的手置于有蚊虫的环境中来评估其驱蚊效果.与单纯喷洒精油乙醇溶液的织物相比,香茅精油微胶囊整理的织物具有更高和更持久的驱蚊性,并且保持90%驱蚊效果的时间长达3周.通过检测纺织品中剩余的精油量,间接检测出纺织品中精油的释放规律.%Microcapsules containing citronella oil were prepared by complex coacervation method and ap-plied in mosquito repellent finishing of nylon fabric, the mosquito repellent efficiency of the finished fabrics was studied. The repellent activity was assessed by exposure of a human hand covered with the treated fab-ric to mosquitoes environment. Fabrics treated with microencapsulated citronella oil presented a higher and longer lasting protection from mosquitoes compared to the fabrics sprayed with an ethanol solution of the es-sential oil, keeping a repellent effect higher than 90% for three weeks. Citronel a oil released from treated tex-tiles was indirectly monitored by the excess oil content of treated fabric.

  20. Efficacy of Plant-Derived and Synthetic Compounds on Clothing as Repellents Against Ixodes scapularis and Amblyomma americanum (Acari: Ixodidae)

    Science.gov (United States)

    2012-01-01

    efÞcacy of the repellent deet against Aedes aegypti . J. Am. Mosq. Control Assoc. 14: 178Ð182. Robbins, P. J., and M. G. Cherniack. 1986. Review of...VECTOR CONTROL , PEST MANAGEMENT, RESISTANCE, REPELLENTS Efficacy of Plant-Derived and Synthetic Compounds on Clothing as Repellents Against Ixodes...4 Division of Vector-BorneDiseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention

  1. 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...

  2. Laboratory and field evaluation of spatial repellency with metofluthrin-impregnated paper strip against mosquitoes in Lombok Island, Indonesia.

    Science.gov (United States)

    Kawada, Hitoshi; Maekawa, Yoshihide; Tsuda, Yoshio; Takagi, Masahiro

    2004-09-01

    Spatial repellency of a new multilayer paper strip impregnated with metofluthrin, a newly synthesized pyrethroid, was evaluated in the laboratory and in the field at Kerandangan, Lombok Island, Indonesia, with the use of cow- and human-baited double nets. Spatial repellency was observed in both cow- and human-baited collections. Metofluthrin treatment reduced mosquito collection by >80% during the 1st 4 weeks. However, repellency seemed to reduce with the loss of metofluthrin by evaporation within 6 wk after treatment.

  3. 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

  4. 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.

  5. Quantitative structure-activity relationship of botanical sesquiterpenes: spatial and contact repellency to the yellow fever mosquito, Aedes aegypti.

    Science.gov (United States)

    Paluch, Gretchen; Grodnitzky, Justin; Bartholomay, Lyric; Coats, Joel

    2009-08-26

    The plant terpenoids encompass a diversity of structures and have many functional roles in nature, including protection against pest arthropods. Previous studies in this laboratory have identified naturally occurring sesquiterpenes contained in essential oils from two plants, amyris (Amyris balsamifera) and Siam-wood (Fokienia hodginsii), that are significantly repellent to a spectrum of arthropod pests. In efforts to further examine the biological activity of this class of compounds 12 of these plant-derived sesquiterpenes have been isolated, purified, and assayed for spatial and contact repellency against the yellow fever mosquito, Aedes aegypti . These data were used to develop quantitative structure-activity relationships that identified key properties of the sesquiterpene molecule, including electronic and structural parameters that were used to predict optimal repellent activity. There were notable similarities in the models developed for spatial repellency over five time points and for contact repellency. Vapor pressure was an important component of all repellency models. Initial levels of spatial repellency were also related to polarizability of the molecule and lowest unoccupied molecular orbital (LUMO) energy, whereas the equation for late spatial repellency was dependent on other electronic features, including Mulliken population and electrotopological state descriptors. The model identified for contact repellency was the best fit and most significant model in this analysis and showed a relationship with vapor pressure, Mulliken population, and total energy.

  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. Repellence and attraction of Apis mellifera foragers by nectar alkaloids

    Directory of Open Access Journals (Sweden)

    Hroncová Z.

    2016-03-01

    Full Text Available Plant secondary metabolites present naturally in nectar, such as alkaloids, may change the behavioural responses of floral visitors and affect pollination. Some studies have shown that nectar containing low concentrations of these secondary metabolites is preferred by honey bee foragers over pure nectar. However, it remains unclear whether this is caused by dependence or addictive behaviour, a simple taste preference, or by other conditions such as self-medication. In our choice experiment, free-flying bees were presented with artificial flowers holding 20% sucrose containing 0.5−50 μg ml−1 of one of the naturally occurring nectar alkaloids - caffeine, nicotine, senecionine, and gelsemine. Nectar uptake was determined by weighing each flower and comparing the weight to that of the control flower. Our experimental design minimized memorizing and marking; despite this, caffeine was significantly preferred at concentrations 0.5−2 μg ml−1 over control nectar; this preference was not observed for other alkaloids. All of the compounds tested were repellent at concentrations above 5 μg ml−1. We confirmed previous reports that bees exhibit a preference for caffeine, and hypothesize that this is not due only to addictive behaviour but is at least partially mediated by taste preference. We observed no significant preference for nicotine or any other alkaloid.

  8. 氨分子与驱避剂缔合对驱避活性影响的定量计算%Quantitative calculation of the repellency affection of the interaction between repellents and ammonia

    Institute of Scientific and Technical Information of China (English)

    廖圣良; 姜志宽; 宋杰; 王宗德; 陈金珠; 张亮华; 韩招久

    2012-01-01

    Objective To screen significant activity-affecting parameters from structural descriptors of 40 amide repellents and their complexes interacting with ammonia, as well as descriptors of characteristic fragments of complexes. The quantitative structure-activity relationship ( QSAR) model was obtained to analyze the relationship between the structural descriptors and the repellency against Aedes aegypti. Methods Three-dimensional structures of 40 amide repellents and their complexes combined with ammonia by hydrogen bond were built using Gaussian view. Then the structures were optimized using Gaussian 03W, and the QSAR model was gained using Ampac 8.16 and Codessa 2.7.10. Results A statistically QSAR model of four parameters with R2 of 0. 7929 was built. Conclusion The most significant activity-affecting parameters are f-NH3-OCNC-Number of single bonds, M-Min n-n repulsion for a C-C bond, f-NH3-OCNC-Min n-n repulsion for a H-N bond, M-Min total interaction for a C-H bond respectively. The results indicate that interactions between repellents and ammonia greatly affect the repellency.%目的 获得40个酰胺类驱避化合物与氨分子缔合体的各类结构描述符,从包括缔合体结构描述符在内的各类结构参数中筛选显著性参数,建立结构参数与驱避活性的定量构效关系( QSAR)模型,从而分析缔合体对驱避活性的影响.方法 以酰胺类驱避化合物对埃及伊蚊(Aedes aegypti)的驱避时间为活性数据;用Gaussian View构建驱避化合物及其缔合体的三维结构,然后用Gaussian 03W优化其结构,再通过Ampac 8.16和Codessa 2.7.10建立QSAR模型.结果 获得1个R2为0.7929的4参数QSAR模型.结论 对驱避活性产生最显著影响的4个描述符分别是f-NH3-OCNC-Number of single bonds,M-Min n-n repulsion for a C-C bond,f-NH3-OCNC-Min n-n repulsion for a H-N bond,M-Min total interaction for a C-H bond;驱避剂与氨分子的缔合对驱避活性有显著的影响.

  9. Length of tick repellency depends on formulation of the repellent compound (icaridin = Saltidin®): tests on Ixodes persulcatus and Ixodes ricinus placed on hands and clothes.

    Science.gov (United States)

    Abdel-Ghaffar, Fathy; Al-Quraishy, Saleh; Mehlhorn, Heinz

    2015-08-01

    The present study had the aim to test the repellent potential of the compound icaridin = Saltidin® against the tick species Ixodes ricinus and Ixodes persulcatus using different formulations of the compound. Tests were done on backs of impregnated human hands, on impregnated linen cloth and versus impregnated dog hair. It was found that 1. Ixodes persulcatus-the common Eastern European, Russian Ixodes species is significantly sensitive to icaridin = Saltidin® as I. ricinus protecting for the test period of 5 h. This is an important finding, since I. persulcatus is the vector of agents of the severe Eastern meningoencephalitis; 2. that this repellent compound acts similarly on both I. ricinus and I. persulcatus, when sprayed either on naked skin or on cloths; 3. that there are only slight differences in duration of the repellency when using different formulations containing icaridin = Saltidin®; 4. that icaridin = Saltidin® sprayed on dog hair has identical repellent effects like those seen on human skin and cloths; thus, this compound can also be used to protect animals such as dogs, cats, horses; and 5. that the icaridin = Saltidin® did not induce a bad sensation on skin, nor bad smells; furthermore, it was not sticky and did not leave residuals neither on clothes nor on dog's hair.

  10. Rhanterium epapposum Oliv. essential oil: Chemical composition and antimicrobial, insect-repellent and anticholinesterase activities

    Directory of Open Access Journals (Sweden)

    Betul Demirci

    2017-07-01

    Full Text Available The essential oil (EO of the aerial parts of Rhanterium epapposum Oliv. (Asteraceae, was obtained by hydrodistillation. The oil was subsequently analyzed by both GC-FID and GC-MS, simultaneously. Forty-five components representing 99.2% of the oil composition were identified. The most abundant compounds were camphene (38.5%, myrcene (17.5%, limonene (10.1% and α-pinene (8.7%. Referring to the ethnobotanical utilization, an insecticidal assay was performed, where the oil repelled the yellow fever mosquito Aedes aegypti L. at a minimum effective dose (MED of 0.035 ± 0.010 mg/cm2 compared to the positive control DEET (MED of 0.015 ± 0.004 mg/cm2. Additionally, the in vitro antimicrobial activity against a panel of pathogens was determined using a microdilution method. The acetyl- and butyrylcholine esterase inhibitory activities were measured using the colorimetric Ellman method. The bioassay results showed that the oil was rather moderate in antimicrobial and cholinesterase inhibitions when compared to the standard compounds.

  11. 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.

  12. Evaluation of Tribulus terrestris Linn (Zygophyllaceae) acetone extract for larvicidal and repellence activity against mosquito vectors.

    Science.gov (United States)

    Singh, S P; Raghavendra, K; Singh, R K; Mohanty, S S; Dash, A P

    2008-12-01

    Acetone extracts of leaves and seeds from the Tribulus terrestris (Zygophyllaceae) were tested against mature and immature different mosquito vectors under laboratory condition. The extract showed strong larvicidal, properties 100 per cent mortality in the 3rd-instar larvae was observed in the bioassays with An. culicifacies Giles species A, An. stephensi Liston, Culex quinquefasciatus Say and Aedes aegypti Linn, against 200 ppm of the leaf acetone extract and 100 ppm seed acetone extract. The LC50 values of leaf acetone extract estimated for 3rd-instars An. culicifacies species A, An. stephensi, Cx. quinquefasciatus and Ae. aegypti after 24 hour of exposure were 117, 124, 168 and 185 ppm respectively. The LC50 values of seed acetone extract estimated for 3rd-instars An. culicifacies species A, An. stephensi, Cx. quinquefasciatus and Ae. aegypti after 24 hour of exposure were 100, 72, 91 and 91 ppm respectively. It is confirmed from the LC50 values that the seed acetone extract of T. terrestris is more effective compared to leaf extracts. A significant (P<0.004) higher concentration of acetone extract leaf was required to kill equal number of larvae i.e. against acetone extract of seed. The seed acetone extract showed strong repellent activity against adults mosquitoes. Per cent protection obtained against Anopheles culicifacies species A 100% repellency in 1 h, 6 h; Anopheles stephensi 100% repellency in 0 h, 4 h, 6 h; and Culex quinquefasciatus 100% repellency in 0 h, 2 h, 4 h, at 10% concentration respectively. Against Deet- 2.5% An. culicifacies Giles species A has shown 100% repellency in 1 h, 2 h, 6 h, An. stephensi Liston 99% repellency in 4 h, and Culex quinquefasciatus Say has shown 100% repellency in 1 h, 2 h.

  13. 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.

  14. 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.

  15. "Singing in the Tube"--audiovisual assay of plant oil repellent activity against mosquitoes (Culex pipiens).

    Science.gov (United States)

    Adams, Temitope F; Wongchai, Chatchawal; Chaidee, Anchalee; Pfeiffer, Wolfgang

    2016-01-01

    Plant essential oils have been suggested as a promising alternative to the established mosquito repellent DEET (N,N-diethyl-meta-toluamide). Searching for an assay with generally available equipment, we designed a new audiovisual assay of repellent activity against mosquitoes "Singing in the Tube," testing single mosquitoes in Drosophila cultivation tubes. Statistics with regression analysis should compensate for limitations of simple hardware. The assay was established with female Culex pipiens mosquitoes in 60 experiments, 120-h audio recording, and 2580 estimations of the distance between mosquito sitting position and the chemical. Correlations between parameters of sitting position, flight activity pattern, and flight tone spectrum were analyzed. Regression analysis of psycho-acoustic data of audio files (dB[A]) used a squared and modified sinus function determining wing beat frequency WBF ± SD (357 ± 47 Hz). Application of logistic regression defined the repelling velocity constant. The repelling velocity constant showed a decreasing order of efficiency of plant essential oils: rosemary (Rosmarinus officinalis), eucalyptus (Eucalyptus globulus), lavender (Lavandula angustifolia), citronella (Cymbopogon nardus), tea tree (Melaleuca alternifolia), clove (Syzygium aromaticum), lemon (Citrus limon), patchouli (Pogostemon cablin), DEET, cedar wood (Cedrus atlantica). In conclusion, we suggest (1) disease vector control (e.g., impregnation of bed nets) by eight plant essential oils with repelling velocity superior to DEET, (2) simple mosquito repellency testing in Drosophila cultivation tubes, (3) automated approaches and room surveillance by generally available audio equipment (dB[A]: ISO standard 226), and (4) quantification of repellent activity by parameters of the audiovisual assay defined by correlation and regression analyses.

  16. 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.

  17. Repellent Compounds Used for Protection From Ticks and Their Toxicological Evaluation

    Directory of Open Access Journals (Sweden)

    Oral DİNLER

    2010-12-01

    Full Text Available Ticks are vectors of very harmful diseases in humans and animals. Nine arbovirus, two rickettsia, two protozoa and one helminthic diseases are transmitted by ticks in different climatic and geographical zones. Twenty six tick species have been determined in Turkey until now. These tick species transmit tropical theileriosis and babesiosis, which are cause of important economical loses especially in farm animals, and lyme disease and Crimean-Congo Hemorrhagic Fever in humans. The control of ticks is getting more important due to appearance of Crimean-Congo Hemorrhagic Fewer (CCHF in Turkey in recent years. However, the control of ticks is a very difficult and expensive procedure and generally chance of success is very low. The main aims of tick control are acaricidal control of ticks on animals, making different applications for elimination of tick-born diseases in humans and reduction of the contact risk between humans, domestic animals and ticks. The repellent is a common name of the compounds, which are applied on directly skin, clothes and sometimes curtains and nets, and prevent the humans and domestic animals against attacks of harmful organisms such as mosquitoes, flies and ticks. Although repellent compounds are applied for the organisms which annoy and suck blood at outdoor, some products used in indoor areas (houses, offices and animal shelters, such as mosquito nets, coils and thermal vaporised liquid and mat formulations, are also evaluated in this frame. Repellents are very beneficial products for prevent attack by ticks. But, it should be known that these compounds are not completely harmless and sometimes they can cause toxic effects in humans and domestic animals. In this review, definition and history of the repellent compounds, the action mechanisms and features of an ideal repellent, important repellent compounds and their toxicological importance and safety usage principles of repellents were evaluated.

  18. Synergistic insecticidal and repellent effects of combined pyrethroid and repellent-impregnated bed nets using a novel long-lasting polymer-coating multi-layer technique.

    Science.gov (United States)

    Faulde, Michael K; Nehring, Oliver

    2012-08-01

    New and improved strategies for malaria control and prevention are urgently needed. As a contribution to an optimized personal protection strategy, a novel long-lasting insecticide and repellent-treated net (LLIRN) has been designed by binding combinations of permethrin plus N,N-diethyl-m-toluamide (DEET), or insect repellent 3535 (IR3535), and etofenprox plus DEET, onto fibres of bed net fabric employing a new multi-layer polymer-coating technique. Protective repellent efficacy, toxicological effectiveness and residual activity of 12 LLIRN types have been evaluated by laboratory testing against adult Aedes aegypti. The novel multi-layer LLIRN design allowed simultaneous embedding at concentrations up to 5,930 mg/m(2) for DEET, 3,408 mg/m(2) for IR3535, 2,296 mg/m(2) for permethrin and 2,349 mg/m(2) for etofenprox, respectively. IR3535 layers prevented co-binding of additional pyrethroid-containing polymer layers, thus making pyrethroids plus DEET LLIRNs an ideal combination. All LLIRNs revealed synergistic insecticidal effects which, when measured against concentration controls of the isolated compounds, were significant in all LLIRN types designed. DEET in DEET plus permethrin LLIRNs significantly (p repellency of DEET or IR3535 on LLIRNs. Vice versa, DEET and IR3535 increased spatial and excitatory repellency and reduced landing and probing frequency on LLIRNs resulting in strongly enhanced biting protection, even at low concentrations. One hundred percent biting and probing protection of stored LLIRNs was preserved for 83 weeks with the 5,930 mg/m(2) DEET and 2,139 mg/m(2) etofenprox LLIRN, for 72 weeks with the 5,002 mg/m(2) DEET and 2,349 mg/m(2) etofenprox LLIRN, for 63 weeks with the 3,590 mg/m(2) DEET and 1,208 mg/m(2) permethrin LLRN, and for 61 weeks with the 4,711 mg/m(2) DEET and 702 mg/m(2) etofenprox LLIRN. Because 100 % bite protection with up to 75 % quicker contact toxicity of pyrethroids were documented, synergistic toxicological and repellent

  19. 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

  20. Patent literature on mosquito repellent inventions which contain plant essential oils--a review.

    Science.gov (United States)

    Pohlit, Adrian Martin; Lopes, Norberto Peporine; Gama, Renata Antonaci; Tadei, Wanderli Pedro; Neto, Valter Ferreira de Andrade

    2011-04-01

    Bites Bites of mosquitoes belonging to the genera Anopheles Meigen, Aedes Meigen, Culex L. and Haemagogus L. are a general nuisance and are responsible for the transmission of important tropical diseases such as malaria, hemorrhagic dengue and yellow fevers and filariasis (elephantiasis). Plants are traditional sources of mosquito repelling essential oils (EOs), glyceridic oils and repellent and synergistic chemicals. A Chemical Abstracts search on mosquito repellent inventions containing plant-derived EOs revealed 144 active patents mostly from Asia. Chinese, Japanese and Korean language patents and those of India (in English) accounted for roughly 3/4 of all patents. Since 1998 patents on EO-containing mosquito repellent inventions have almost doubled about every 4 years. In general, these patents describe repellent compositions for use in topical agents, cosmetic products, incense, fumigants, indoor and outdoor sprays, fibers, textiles among other applications. 67 EOs and 9 glyceridic oils were individually cited in at least 2 patents. Over 1/2 of all patents named just one EO. Citronella [Cymbopogon nardus (L.) Rendle, C.winterianus Jowitt ex Bor] and eucalyptus (Eucalyptus LʼHér. spp.) EOs were each cited in approximately 1/3 of all patents. Camphor [Cinnamomum camphora (L.) J. Presl], cinnamon (Cinnamomum zeylanicum Blume), clove [Syzygium aromaticum (L.) Merr. & L.M. Perry], geranium (Pelargonium graveolens LʼHér.), lavender (Lavandula angustifolia Mill.), lemon [Citrus × limon (L.) Osbeck], lemongrass [Cymbopogon citratus (DC.) Stapf] and peppermint (Mentha × piperita L.) EOs were each cited in > 10% of patents. Repellent chemicals present in EO compositions or added as pure “natural” ingredients such as geraniol, limonene, p-menthane-3,8-diol, nepetalactone and vanillin were described in approximately 40% of all patents. About 25% of EO-containing inventions included or were made to be used with synthetic insect control agents having mosquito

  1. A QSAR Study of the Repellency of some Terpenoids to the Bedbug Cimex lectularius L.%萜类臭虫(Cimex lectularius L.)驱避化合物的定量构效关系研究

    Institute of Scientific and Technical Information of China (English)

    宋杰; 王宗德; 韩招久; 陈金珠; 姜志宽; 郑卫青; 商士斌

    2012-01-01

    测定了一系列六元环萜类化合物对臭虫(Cimex lectularius L.)的驱避活性,利用Codessa Pro程序计算了这些化合物的结构描述符,再利用Codessa Pro程序中的最优线性回归方法计算了驱避活性与这些化合物结构描述符之间的定量构效关系.所得到的最优定量构效关系计算模型的R2为0.924,模型所包含的4个参数分别是:FNSA3 fractional PNSA、Min n-n repulsion for bond H-C、YZ Shadow/YZ rectangle、Max electrophilic reactivity index for atom C.通过对模型的分析讨论了臭虫化学感受器与驱避剂之间可能存在的相互作用.%The quantitative structure-activity relationship (QSAR) between the repellency against bedbug,Cimex lectularius L.(Hemiptera:Cimicidae) and the molecular structural descriptors of a series of terpenoid compounds with six-member-ring was correlated by best multilinear regression (BMLR) method.The descriptors and the multilinear regression were all calculated by Codessa Pro.The optimum multilinear model with R2 value of 0.924 and 4 descriptors,i.e.the fractional atomic charge weighted partial megative surface area (FNSA3) fractional the atomic charge weighted partial negative charge molecular surface area (PNSA),Min n-n repulsion for bond H-C,YZ Shadow/YZ rectangle and Max electrophilic reactivity index for atom C was validated and presented.The probable interaction between the chemoreceptor of bedbug and the repellent was also discussed according to the optimum model and its descriptors.

  2. 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

  3. 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.

  4. Assessment of the repellent effect of citronella and lemon eucalyptus oil against South African Culicoides species.

    Science.gov (United States)

    Venter, Gert J; Labuschagne, Karien; Boikanyo, Solomon N B; Morey, Liesl

    2014-08-08

    The use of insect repellents to reduce the attack rate of Culicoides species (Diptera:Ceratopogonidae) should form part of an integrated control programme to combat African horse sickness and other diseases transmitted by these blood-feeding midges. In the present study the repellent effects of a commercially available mosquito repellent, a combination of citronella and lemon eucalyptus oils, on Culicoides midges was determined. The number of midges collected with two 220 V Onderstepoort traps fitted with 8 W 23 cm white light tubes and baited with peel-stick patches, each containing 40 mg of active ingredient, was compared with that of two unbaited traps. Two trials were conducted and in each trial the four traps were rotated in two replicates of a 4 x 4 randomised Latin square design. Although more midges were collected in the baited traps, the mean number in the baited and unbaited traps was not significantly different. This mosquito repellent did not influence either the species composition or the physiological groups of Culicoides imicola Kieffer. The higher mean numbers in the baited traps, although not statistically significant, may indicate that this mosquito repellent might even attract Culicoides midges under certain conditions.

  5. Assessment of the repellent effect of citronella and lemon eucalyptus oil against South African Culicoides species

    Directory of Open Access Journals (Sweden)

    Gert J. Venter

    2014-02-01

    Full Text Available The use of insect repellents to reduce the attack rate of Culicoides species (Diptera:Ceratopogonidae should form part of an integrated control programme to combat Africanhorse sickness and other diseases transmitted by these blood-feeding midges. In the presentstudy the repellent effects of a commercially available mosquito repellent, a combinationof citronella and lemon eucalyptus oils, on Culicoides midges was determined. The numberof midges collected with two 220 V Onderstepoort traps fitted with 8 W 23 cm white lighttubes and baited with peel-stick patches, each containing 40 mg of active ingredient, wascompared with that of two unbaited traps. Two trials were conducted and in each trial thefour traps were rotated in two replicates of a 4 x 4 randomised Latin square design. Althoughmore midges were collected in the baited traps, the mean number in the baited and unbaitedtraps was not significantly different. This mosquito repellent did not influence either thespecies composition or the physiological groups of Culicoides imicola Kieffer. The highermean numbers in the baited traps, although not statistically significant, may indicate that thismosquito repellent might even attract Culicoides midges under certain conditions.

  6. Synergistic mosquito-repellent activity of Curcuma longa, Pogostemon heyneanus and Zanthoxylum limonella essential oils.

    Science.gov (United States)

    Das, N G; Dhiman, Sunil; Talukdar, P K; Rabha, Bipul; Goswami, Diganta; Veer, Vijay

    2015-01-01

    Mosquito repellents play an important role in preventing man-mosquito contact. In the present study, we evaluated the synergistic mosquito-repellent activity of Curcuma longa, Pogostemon heyneanus and Zanthoxylum limonella essential oils. The mosquito repellent efficacies of three essential oils were evaluated separately and in combination under laboratory and field conditions. N,N-Diethylphenylacetamide (DEPA) and dimethylphthalate (DMP) were used for comparison of the protection time of the mixture of essential oils. At an optimum concentration of 20%, the essential oils of C. longa, Z. limonella and P. heyneanus provided complete protection times (CPTs) of 96.2, 91.4 and 123.4 min, respectively, against Aedes albopictus mosquitoes in the laboratory. The 1:1:2 mixture of the essential oils provided 329.4 and 391.0 min of CPT in the laboratory and field trials, respectively. The percent increases in CPTs for the essential oil mixture were 30 for DMP and 55 for N,N-diethylphenylacetamide (DEPA). The synergistic repellent activity of the essential oils used in the present study might be useful for developing safer alternatives to synthetic repellents for personal protection against mosquitoes.

  7. 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.

  8. 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.

  9. Repellent effect of santalol from sandalwood oil against Tetranychus urticae (Acari: Tetranychidae).

    Science.gov (United States)

    Roh, Hyun Sik; Park, Kye Chung; Park, Chung Gyoo

    2012-04-01

    Thirty-four essential oils were screened for their repellent activities against the twospotted spider mite, Tetranychus urticae Koch (Acarina: Tetranychidae), at 0.1% concentration level using choice and no-choice laboratory bioassays. Of these, 20 essential oils showed significant repellencies against T. urticae in the choice tests. In subsequent no-choice tests using these 20 essential oils, only sandalwood oil showed significant repellency against T. urticae. Total number of eggs oviposited by T. urticae was significantly lower than controls in the choice tests when the kidney bean leaves were treated with 1 of 14 essential oils. The significant repellency of sandalwood oil against T. urticae lasted at least for 5 h at the 0.1% concentration level. Our GC-MS analysis indicated that the major components of the sandalwood oil were alpha-santalol (45.8%), beta-santalol (20.6%), beta-sinensal (9.4%), and epi-beta-santalol (3.3%). Santanol, a mixture of the two main components in the sandalwood oil, appears to be responsible for the repellency of sandalwood oil against T. urticae.

  10. Repellent Constituents of essential oil from Citrus wilsonii stem barks against Tribolium castaneum.

    Science.gov (United States)

    Wua, Yan; Chenb, Hai-Ping; Wei, Jian-Yu; Yang, Kai; Tian, Zhao-Fu; Li, Xiao-Lan; Wang, Ping-Juan; Wang, Cheng-Fang; Du, Shu-Shan; Cai, Qian

    2014-10-01

    The essential oil obtained from Citrus wilsonii Tanaka stem barks with hydrodistillation was investigated by GC-FID and GC-MS. The main components of the essential oil were identified to be nerol acetate (44.5%), nerol (13.6%), citronellyl propionate (13.5%) and α-terpineol (3.6%). Among them, the four active constituents, predicted with a bioactivity-test, were isolated and identified as nerolacetate, nerol, citronellyl propionate and α-terpineol. It was found that the essential oil of C. wilsonii stem barks possessed strong repellency (86% and 92%, respectively, at 78.6 nL/cm2, after 2 and 4 h treatment) against Tribolium castaneum adults. Repellency of the four active compounds was also determined. Nerolacetate, nerol, citronellyl propionate and α-terpineol were strongly repellent (100%, 100%, 90% and 96%, respectively, at 15.7 nL/cm2, after 2h treatment) against T. castaneum. Nerol exhibited the same level of repellency as the positive control, DEET. The results indicate that the essential oil of C. wilsonii stem barks and its active compounds have the potential to be developed as natural repellents for control of T. castaneum.

  11. Reducing Insects Contaminations through Stored Foodstuffs by Use of Packaging and Repellency Essential Oils

    Directory of Open Access Journals (Sweden)

    Somaye ALLAHVAISI

    2010-12-01

    Full Text Available Protection of stored agricultural products against insects is carried out with chemical insecticides. They have harmful effects for human being, animal and environment. This research carried out on plant essential oils, which are one of the harmless materials and act like contact-fumigant from offering the prospect for using in stored product. They should have the ability to repel the insects. The objective of the present study was to test the properties of Prunus amygdalus L. and Mentha viridis L. for preventing the penetration of pest insects, including: T. castaneum, S. granaries, S. paniceum and R. dominica, to packaged cereals. As foodstuff was packaged by PE polymer and placed into a container 10 g of wheat and flour. The repellent essential oils used in the interior surface of containers. The releasing of insects carried out around the containers to determinate the insect�s penetration percentage with effect of repellents. The highest concentration counted was 1.75 ?l of essential oil per 0.5 ml acetone. The results showed that P. amygdalus had the most repellency effect on T. castaneum that cause 78.52% contamination deduction inside the packaged crop in comparing with control. In addition, M. viridis caused the most repellency on S. granarius (63.81%. The results demonstrated the efficacy of these essential oils for using it in organic food protection. They can prevent the infestation of the stored-product pests to the warehouse.

  12. Mosquito (Diptera: Culicidae) repellency field tests of essential oils from plants traditionally used in Laos.

    Science.gov (United States)

    Vongsombath, Chanda; Pålsson, Katinka; Björk, Lars; Borg-Karlson, Anna-Karin; Jaenson, Thomas G T

    2012-11-01

    Essential oils of Hyptis suaveolens (Lamiaceae), Croton roxburghii (Euphorbiaceae), and Litsea cubeba (Lauraceae) were tested in the field near Vientiane city, Lao PDR, on humans for repellent activity against mosquitoes. Landing mosquitoes were collected and later identified. The most abundant mosquitoes captured belonged to the genera Armigeres, Culex, and Aedes. All the plant oils tested at concentrations of 1.7 microg/cm(2), 3.3 microg/cm(2), and 6.3 microg/cm(2) were significantly more mosquito repellent than the negative control. Croton oil was significantly repellent against mosquitoes of the three genera at the highest (6.3 microg/cm(2)) concentration tested. Litsea oil was significantly repellent against Armigeres at all (1.7 microg/cm(2), 3.3 microg/cm(2), and 6.3 microg/cm(2)) concentrations tested. Hyptis oil was significantly repellent against Armigeres at 3.3 microg/cm(2) and 6.3 microg/cm(2) and against Culex at 1.7 microg/cm(2) and 6.3 microg/cm(2). The oils were analyzed for chemical content of volatiles, mainly terpenes. Main constituents were beta-pinene, sabinene, and 1,8-cineol from oils of the green parts of H. suaveolens; alpha-pinene, beta-pinene, and alpha-phellandrene from fresh bark of C. roxburghii; and alpha-pinene, beta-phellandrene, sabinene, and 1,8-cineol from fresh fruits of L. cubeba.

  13. Plant-Derived Tick Repellents Activate the Honey Bee Ectoparasitic Mite TRPA1

    Directory of Open Access Journals (Sweden)

    Guangda Peng

    2015-07-01

    Full Text Available We have identified and characterized the TRPA1 channel of Varroa destructor (VdTRPA1, a major ectoparasitic mite of honey bee. One of the two VdTRPA1 isoforms, VdTRPA1L, was activated by a variety of plant-derived compounds, including electrophilic compounds, suggesting that chemical activation profiles are mostly shared between arthropod TRPA1 channels. Nevertheless, carvacrol and α-terpineol activated VdTRPA1L but not a honey bee noxious-stimuli-sensitive TRPA, AmHsTRPA, and Drosophila melanogaster TRPA1. Activation of VdTRPA1L in D. melanogaster taste neurons by the above compounds was sufficient to modify the gustatory behaviors. Carvacrol and α-terpineol repelled V. destructor in a laboratory assay, and α-terpineol repressed V. destructor entry for reproduction into the brood cells in hives. Understanding the functions of parasite TRP channels not only gives clues about the evolving molecular and cellular mechanisms of parasitism but also helps in the development of control methods.

  14. 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....

  15. Fresh, dried or smoked? Repellent properties of volatiles emitted from ethnomedicinal plant leaves against malaria and yellow fever vectors in Ethiopia

    National Research Council Canada - National Science Library

    Dube, Fitsum Fikru; Tadesse, Kassahun; Birgersson, Göran; Seyoum, Emiru; Tekie, Habte; Ignell, Rickard; Hill, Sharon R

    2011-01-01

    .... Volatile extracts from the smoke of burning dried leaves were found to be more repellent than those from fresh leaves, which in turn were more repellent to mosquitoes than volatiles from dried leaves...

  16. DEET insect repellent: effects on thermoregulatory sweating and physiological strain.

    Science.gov (United States)

    Kenefick, Robert W; Cheuvront, Samuel N; Ely, Brett R; Palombo, Laura J; Sawka, Michael N

    2011-12-01

    Insect repellents (e.g. N,N-diethyl-m-toluamide or DEET) applied to the skin can potentially interfere with sweat production and evaporation, thus increasing physiological strain during exercise-heat stress. The purpose was to determine the impact of 33% DEET lotion on sweating responses, whole body thermoregulation and thermal sensation during walking exercise in the heat. Nine volunteers (2 females, 7 males; 22.1 ± 4.9 years; 176.4 ± 10.0 cm; 79.9 ± 12.9 kg) completed 5 days of heat acclimation (45°C, 20% rh; 545 watts; 100 min/day) and performed three trials: control (CON); DEET applied to forearm (DEET(LOC), 12 cm(2)); and DEET applied to ~13% body surface area (DEET(WB),). Trials consisted of 30 min walking (645 watts) in 40°C, 20% rh environment. Local sweat rate (SR), onset and skin wettedness were measured in DEET(LOC), and heart rate (HR), rectal temperature (T (re)), skin temperature (T (sk)), RPE, and thermal sensations (TS) were measured during DEET(WB). No differences (p > 0.05) were observed between DEET(LOC) versus CON, respectively, for steady state SR (1.89 ± 0.44 vs. 2.09 ± 0.84 mg/cm(2)/min), SR area under the curve (46.9 ± 11.7 vs. 55.0 ± 20.8 mg/cm(2)), sweating onset, or skin wettedness. There were no differences (p > 0.05) in HR, T (re), T (sk), Physiological Strain Index, RPE or TS between DEET(WB) versus CON. DEET did not impact measures of local forearm sweating and when applied according to military doctrine, did not adversely impact physiological responses during exercise-heat stress. DEET can be safely worn during military, occupational and recreational activities in hot, insect infested environments.

  17. Team Member Training Manual.

    Science.gov (United States)

    1998-07-01

    minutes a "facilitator" obtains one idea from each member in turn and writes that idea on a flip chart . No discussion takes place during this step. 4...Step three is repeated until all ideas are listed on the flip chart . 5. Each idea is discussed. Participants seek clarification and express support

  18. A Pilot Study to Validate a Standardized One-Week Salt Estimation Method Evaluating Salt Intake and Its Sources for Family Members in China

    Directory of Open Access Journals (Sweden)

    Lu Zhang

    2015-01-01

    Full Text Available The objective of this study was to develop a new method named the “one-week salt estimation method” that could estimate an individual’s salt intake and the sources of salt in the diet, and to evaluate this new method with a 24-h urine collection. The new method estimates salt intake from: (1 household cooking by weighing the family salt container and other high-salt condiments or sauces at the beginning and end of a week; (2 processed food according to established China food composition figures; and (3 cafeteria or restaurant meals using the results of previous studies. Consumption of salt additives and major salt contained foods and salt intake related eating habits were collected using a structured simple seven-day questionnaire. In order to validate the method, we studied 37 individuals from 11 families using the new method and 26 of these participants collected seven concurrent 24-h urine samples. The average salt intake for the 26 participants was 15.6 ± 5.5 g/person/day (mean ± standard deviation by the 24-h urine collection and 13.7 ± 6.5 g/person/day by the new method. The difference was 1.8 ± 4.2 g/day/person (p = 0.037. The Pearson correlation coefficient was 0.762 (p < 0.001 and the partial correlation coefficient was 0.771 (p < 0.001 when adjusted for family code. Bland-Altman Plot showed the average of the difference between the two methods was −1.83, with 95% limits of −10.1 to 6.5 g/person/day. The new method showed that 43.7% of salt intake came from household cooking (33.5% from cooking salt, 10.2% from other condiments and sauces, 12.9% from processed food, and 43.4% from eating out. In conclusion, despite its limitations of underestimating salt intake, the “one-week salt estimation method” is easier for people to implement and is likely to provide useful information that highlights the excessively high intake of salt and its sources, and in turn is helpful in guiding dietary salt reduction.

  19. Analysis of Methods of the Management and Education of Student Party Members in Higher Vocational Colleges%高职高专学生党员管理教育方法探究

    Institute of Scientific and Technical Information of China (English)

    徐引红

    2011-01-01

    加强对高职高专学生党员的管理和教育,对于保证党员队伍质量和提高社会应用型人才素质有着重要意义.本文试从当前高职高专学生党建的现状和遇到的挑战着手,在大学生这一特殊群体和高职高专这一学校类型中做对比研究,分析高职高专学生党员管理和教育的方法.%Strengthening the management and education of student Party members in higher vocational colleges has great significance of guaranteeing the quality of Party members and improving the quality of social applications talents.Analysing the current status of the Party building among students in higher vocational colleges and challenges from it, this article makes comparative study in college students and higher vocational colleges, aiming at the methods of management and education of student Party members in higher vocational colleges.

  20. Repellent and mosquitocidal effects of leaf extracts of Clausena anisata against the Aedes aegypti mosquito (Diptera: Culicidae).

    Science.gov (United States)

    Mukandiwa, Lillian; Eloff, Jacobus Nicolaas; Naidoo, Vinny

    2016-06-01

    Mosquitoes are rapidly developing resistance to insecticides that millions of people relied on to protect themselves from the diseases they carry, thereby creating a need to develop new insecticides. Clausena anisata is used traditionally as an insect repellent by various communities in Africa and Asia. For this study, the repellency and adulticidal activities of leaf extracts and compounds isolated from this plant species were evaluated against the yellow fever mosquito, Aedes aegypti. In the topical application assays, using total bites as an indicator, repellency was dose dependent, with the acetone crude extract (15 %) having 93 % repellence and the hexane fraction (7.5 %) 67 % repellence after 3 h. Fractionation resulted in a loss of total repellence. As mosquito-net treating agents, the acetone and hexane extracts of C. anisata, both at 15 %, had average repellences of 46.89 ± 2.95 and 50.13 ± 2.02 %, respectively, 3 h after exposure. The C. anisata acetone extract and its hexane fraction caused mosquito knockdown and eventually death when nebulised into the testing chamber, with an EC50 of 78.9 mg/ml (7.89 %) and 71.6 mg/ml (7.16 %) in the first 15 min after spraying. C. anisata leaf extracts have potential to be included in protection products against mosquitoes due to the repellent and cidal compounds contained therein.

  1. An agent-based model to investigate the roles of attractive and repellent pheromones in ant decision making during foraging.

    Science.gov (United States)

    Robinson, Elva J H; Ratnieks, Francis L W; Holcombe, M

    2008-11-21

    Pharaoh's ants organise their foraging system using three types of trail pheromone. All previous foraging models based on specific ant foraging systems have assumed that only a single attractive pheromone is used. Here we present an agent-based model based on trail choice at a trail bifurcation within the foraging trail network of a Pharaoh's ant colony which includes both attractive (positive) and repellent (negative) trail pheromones. Experiments have previously shown that Pharaoh's ants use both types of pheromone. We investigate how the repellent pheromone affects trail choice and foraging success in our simulated foraging system. We find that both the repellent and attractive pheromones have a role in trail choice, and that the repellent pheromone prevents random fluctuations which could otherwise lead to a positive feedback loop causing the colony to concentrate its foraging on the unrewarding trail. An emergent feature of the model is a high level of variability in the level of repellent pheromone on the unrewarding branch. This is caused by the repellent pheromone exerting negative feedback on its own deposition. We also investigate the dynamic situation where the location of the food is changed after foraging trails are established. We find that the repellent pheromone has a key role in enabling the colony to refocus the foraging effort to the new location. Our results show that having a repellent pheromone is adaptive, as it increases the robustness and flexibility of the colony's overall foraging response.

  2. Repellent activities of some Labiatae plant essential oils against the saltmarsh mosquito Ochlerotatus caspius (Pallas, 1771) (Diptera: Culicidae).

    Science.gov (United States)

    Koc, Samed; Oz, Emre; Cetin, Huseyin

    2012-06-01

    The repellent activities of the essential oils of two Thymus (Thymus sipyleus Boiss. subsp. sipyleus and Thymus revolutus Celak) and two Mentha (Mentha spicata L. subsp. spicata and Mentha longifolia L.) species against Ochlerotatus caspius (Pallas, 1771) (Diptera: Culicidae) are presented. The essential oils were obtained by hydrodistillation of the aerial parts of the plants in flowering period and repellency tests were done with a Y-tube olfactometer. All essential oils showed repellency in varying degrees and exhibited no significant time-dependent repellent activities. When all test oils compared for repellent activities there was no significant activity detected within 15 min exposure period. Mentha essential oils had better activity than Thymus essential oils, producing high repellency (73.8-84.2%) at 30th min on Oc. caspius. Mentha longifolia has the best mosquito repellent activity among the plants tested at the 25th min. Th. sipyleus subsp. sipyleus essential oil produced >85% repellent activity at the 15th min, but the effect decreased noticeably to 63.1% and 68% at 25th and 30th min, respectively.

  3. 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...

  4. Bioassay-guided investigation of two monarda essential oils as repellents of yellow fever mosquito Aedes aegypti

    Science.gov (United States)

    As part of an ongoing research program to identify active mosquito repellents, Monarda bradburiana Beck and M. fistulosa L. essential oils showed potent repellents with minimum effective dosages (MED) of 0.055 ± 0.036 and 0.078 ± 0.027 mg/cm2, respectively, compared to reference standard N,N-diethyl...

  5. Assessing the efficacy of candidate mosquito repellents against the background of an attractive source that mimics a human host

    NARCIS (Netherlands)

    Menger, D.J.; Loon, van J.J.A.; Takken, W.

    2014-01-01

    Mosquito repellents are used around the globe to protect against nuisance biting and disease-transmitting mosquitoes. Recently, there has been renewed interest in the development of repellents as tools to control the transmission of mosquito-borne diseases. We present a new bioassay for the accurate

  6. 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

  7. 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...

  8. 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...

  9. Assessing the efficacy of candidate mosquito repellents against the background of an attractive source that mimics a human host

    NARCIS (Netherlands)

    Menger, D.J.; Loon, van J.J.A.; Takken, W.

    2014-01-01

    Mosquito repellents are used around the globe to protect against nuisance biting and disease-transmitting mosquitoes. Recently, there has been renewed interest in the development of repellents as tools to control the transmission of mosquito-borne diseases. We present a new bioassay for the accurate

  10. The repellent efficacy of eleven essential oils against adult Dermacentor reticulatus ticks.

    Science.gov (United States)

    Štefanidesová, Katarína; Škultéty, Ľudovít; Sparagano, Olivier A E; Špitalská, Eva

    2017-08-01

    Dermacentor reticulatus ticks are among the most important arthropod vectors of zoonotic disease agents in Europe. Eleven essential oils, namely basil (Ocimum basilicum), bergamot (Citrus bergamia), clove bud (Syzygium aromaticum), citronella (Cymbopogon winterianus), creeping thyme (Thymus serpyllum), lavender (Lavandula angustifolia), lemon-scented gum (Corymbia citriodora), marjoram (Origanum majorana), peppermint (Mentha piperita), spearmint (M. spicata), and red thyme (Thymus vulgaris) were tested for repellency against adult D. reticulatus ticks at concentrations of 1 and 3%. Clove bud, creeping thyme and red thyme essential oils were the most efficient - repelling 83, 82 and 68% of ticks when diluted to 3%, respectively. The mixture of creeping thyme and citronella containing 1.5% of each showed higher repellency (91%) than individual essential oils at the concentration of 3%. Copyright © 2017 Elsevier GmbH. All rights reserved.

  11. [Repellent and antifeedant effect of secondary metabolites of non-host plants on Plutella xylostella].

    Science.gov (United States)

    Wei, Hui; Hou, Youming; Yang, Guang; You, Minsheng

    2004-03-01

    Based on the theory of co-evolution between plants and phytophagous insects, the repellent and antifeedant effect of secondary metabolites of non-host plants on diamondback moth(DBM) Plutella xylostella was studied, aimed at finding out the oviposition repellents and antifeedants of insect pests. When the ethanol extracts(Etho Exts) of Bauhinia variegata, Eucalyptus tereticornis, Euphorbia hirta, Duranta repens, Zanthoxylum bungeanum, Magnolia grandiflora, and Nicotiana tabacum were applied respectively, the oviposition repellent rates were all over 80.00%; while after forty-eight hours treatment with the Etho Exts of Euphorbia pulcherrima, Broussonetia papyrifera, Artemisia argyi, Camellia oleifera, Salix babylonica, Euphorbia hirta, Bauhinia variegata, and Setaria viridisa, the antifeedant rates of DBM larvae were all more than 80.00%.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Studies on the Insecticidal and Repellent Properties of the Seed Extract of Tephrosia Purpurea (LINN Pers

    Directory of Open Access Journals (Sweden)

    B. N. Saxena

    1974-04-01

    Full Text Available Laboratory and field trials were conducted to find out the insecticidal and repellent properties of petroleum ether extract of the seeds of Tephrosia purpurea. In laboratory trials contact toxicity of the extract was assessed against land leeches, houseflies, mosquitoes, rice weevil and flour beetle. In field trials, the repellency of the extract was assessed against land leeches, mosquitoes and simulium flies. In laboratory trials, the dosage required for 100 per cent mortality was 0.0005 gm/cm/sup 2/ for land leeches, 0.0157 gm/cm/sup 2/ for flour beetle. In field trials, the extract was found to be repellent against land leeches for 5 hours, mosquitoes for 4 hours and simulium flies for 5 hours.

  17. Insecticidal and insect-repellent activities of essential oils from Verbenaceae and Anacardiaceae against Rhizopertha dominica.

    Science.gov (United States)

    Benzi, Verónica S; Murrayb, Ana P; Ferrero, Adriana A

    2009-09-01

    Essential oils extracted from leaves of Aloysia polystachya and A. citriodora (Verbenaceae) and from leaves and fruits of Schinus molle var. areira (Anacardiaceae) were tested for their repellent and toxic activities against adults of Rhizopertha dominica (Coleoptera: Bostrichidae). Topical application and filter paper assays were employed for contact toxicity studies; filter paper impregnation was also used for fumigant and repellent assays. In topical tests A. polystachya was as effective as S. molle leaves. In the case of repellent assays, A. citriodora was the most effective oil based on the class scale. A. polystachya was the most toxic plant on contact toxicity by filter paper assay (LC50 26.6 mg/cm2). Fumigant toxicity was only evaluated with fruits and leaves of S. molle, and no significant differences were found between them. Published data are included to compare the fumigant toxicity of S. molle with that of A. citridora and A. polystachya.

  18. Determining airborne concentrations of spatial repellent chemicals in mosquito behavior assay systems.

    Directory of Open Access Journals (Sweden)

    Nicholas J Martin

    Full Text Available BACKGROUND: Mosquito behavior assays have been used to evaluate the efficacy of vector control interventions to include spatial repellents (SR. Current analytical methods are not optimized to determine short duration concentrations of SR active ingredients (AI in air spaces during entomological evaluations. The aim of this study was to expand on our previous research to further validate a novel air sampling method to detect and quantitate airborne concentrations of a SR under laboratory and field conditions. METHODOLOGY/PRINCIPAL FINDINGS: A thermal desorption (TD gas chromatography-mass spectrometry (GC-MS method was used to determine the amount of dichlorodiphenyltrichloroethane (DDT in samples of air. During laboratory experiments, 1 L volumes of air were collected over 10 min intervals from a three-chamber mosquito behavior assay system. Significantly higher levels of airborne DDT were measured in the chamber containing textiles treated with DDT compared to chambers free of AI. In the field, 57 samples of air were collected from experimental huts with and without DDT for onsite analysis. Airborne DDT was detected in samples collected from treated huts. The mean DDT air concentrations in these two huts over a period of four days with variable ambient temperature were 0.74 µg/m(3 (n = 17; SD = 0.45 and 1.42 µg/m(3 (n = 30; SD = 0.96. CONCLUSIONS/SIGNIFICANCE: The results from laboratory experiments confirmed that significantly different DDT exposure conditions existed in the three-chamber system establishing a chemical gradient to evaluate mosquito deterrency. The TD GC-MS method addresses a need to measure short-term (<1 h SR concentrations in small volume (<100 L samples of air and should be considered for standard evaluation of airborne AI levels in mosquito behavior assay systems. Future studies include the use of TD GC-MS to measure other semi-volatile vector control compounds.

  19. 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

  20. Preliminary study on mosquito repellent and mosquitocidal activities of Ocimum gratissimum (L.) grown in eastern Nigeria.

    Science.gov (United States)

    Oparaocha, Evangeline T; Iwu, Iraneus; Ahanakuc, J E

    2010-03-01

    The study examined the mosquito-repellent and mosquitocidal activities of the volatile oil of Ocimum gratissimum at three different locations (World Bank Estate, Ihitte and Umuekunne) in Imo State, eastern Nigeria, with the purpose of sourcing for mosquito repellent that is cheap, abundant, environment and user-friendly. Four different lotions; 20% (v/v) and 30% (v/v) concentrations each of the extracted volatile oil in two natural oil bases (olive and palm kernel) were made and six volunteered human baits were used to evaluate the mosquito repellent and mosquitocidal activities of the stock materials at the three different centres from September to November 2008. Topical application of each of the four different lotions significantly (p mosquitoes in all the three locations tested. The 30% (v/v) concentration in olive oil base exhibiting highest average percentage repellencies of 97.2, 95.7 and 96.3% at World Bank Estate, Ihitte and Umuekunne centres respectively while the 20% (v/v) concentration in palm kernel oil base had the least repellency of 36.3, 41.6 and 36.3%, respectively. The other two formulations had values ranging from 67.8 to 80% in the three locations. The 30% (v/v) concentration in both olive and palm kernel oil bases afforded all night protection against mosquito bites in all the centres, and demonstrated fast knockdown and paralyzing effect on few mosquitoes at the urban centre (World Bank Estate). The study confirms that O. gratissimum grown in eastern Nigeria has mosquito-repellent and mosquitocidal potentials and the formulations could be used to reduce human-mosquito contacts and hence mosquito-borne diseases and irritations caused by their bites.

  1. Repellent effect of some household products on fly attraction to cadavers.

    Science.gov (United States)

    Charabidze, Damien; Bourel, Benoit; Hedouin, Valery; Gosset, Didier

    2009-08-10

    The most common task of a forensic entomologist is to determine an accurate minimum post-mortem interval (PMI) using necrophagous fly larvae found on carrion. More often, blowflies (Diptera: Calliphoridae) are the first insects to detect the cadaver and, if the circumstances are favourable, to leave eggs on the body. However, several studies reveal that products such as gas or paint found on the cadaver induce a delay in the colonisation of the body, leading to an under-estimate of the PMI. Six common household products (gas, mosquito citronella repellent, perfume, bleach, hydrochloric acid and soda) were added to dead rats (Rattus norvegicus) in a field (Lille Forensic Institute, France). The presence of necrophagous flies was checked at regular intervals during 1 month. This experiment was repeated at the same period for four consecutive years. Results clearly showed the repellent effect of three of the six tested substances: gas (petroleum spirit), perfume and mosquito citronella repellent, which resulted in a mean delay of several days in the appearance of the first Dipteran species. Experiments were then carried out in controlled conditions in order to confirm previous observations. An olfactometer was specially designed to observe the behaviour of female Calliphora vicina (Diptera: Calliphoridae) in response to mice (Mus musculus) cadaver odour stimuli combined with household products. Dead mouse odour was a strong attractive stimulus for most of the tested individuals. Furthermore, it was noticed that the presence of mosquito citronella repellent, perfume, hydrochloric acid and paradichlorobenzene produced a significant repellent effect on female flies. All these results together confirm the repellent effect of some household products on flies and the necessity for forensic entomologists to consider this hypothesis when estimating the PMI.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Two alternative DNA extraction methods to improve the detection of Mycobacterium-tuberculosis-complex members in cattle and red deer tissue samples.

    Science.gov (United States)

    Fell, Shari; Bröckl, Stephanie; Büttner, Mathias; Rettinger, Anna; Zimmermann, Pia; Straubinger, Reinhard K

    2016-09-15

    Bovine tuberculosis (bTB), which is caused by Mycobacterium bovis and M. caprae, is a notifiable animal disease in Germany. Diagnostic procedure is based on a prescribed protocol that is published in the framework of German bTB legislation. In this protocol small sample volumes are used for DNA extraction followed by real-time PCR analyses. As mycobacteria tend to concentrate in granuloma and the infected tissue in early stages of infection does not necessarily show any visible lesions, it is likely that DNA extraction from only small tissue samples (20-40 mg) of a randomly chosen spot from the organ and following PCR testing may result in false negative results. In this study two DNA extraction methods were developed to process larger sample volumes to increase the detection sensitivity of mycobacterial DNA in animal tissue. The first extraction method is based on magnetic capture, in which specific capture oligonucleotides were utilized. These nucleotides are linked to magnetic particles and capture Mycobacterium-tuberculosis-complex (MTC) DNA released from 10 to 15 g of tissue material. In a second approach remaining sediments from the magnetic capture protocol were further processed with a less complex extraction protocol that can be used in daily routine diagnostics. A total number of 100 tissue samples from 34 cattle (n = 74) and 18 red deer (n = 26) were analyzed with the developed protocols and results were compared to the prescribed protocol. All three extraction methods yield reliable results by the real-time PCR analysis. The use of larger sample volume led to a sensitivity increase of DNA detection which was shown by the decrease of Ct-values. Furthermore five samples which were tested negative or questionable by the official extraction protocol were detected positive by real time PCR when the alternative extraction methods were used. By calculating the kappa index, the three extraction protocols resulted in a moderate (0.52; protocol 1 vs 3

  7. Distillation of Essential Oil from Surian Leaf (Toona sureni (Bl. Merr. as Repellent Cream for Protection Aedes aegypty L. Bites.

    Directory of Open Access Journals (Sweden)

    Susi Endrini

    2011-04-01

    Full Text Available Distillation of Essential Oil from Surian Leaf (Toona sureni (Bl. Merr. as Repellent Cream for Protection Aedesaegypty L. Bites. Isolation of volatile oil of leaf surian (Toona sureni (Bl. Merr. have been done by distillationaqueous vapour method. Distillation result had the chocolate colored and stinging aroma, and rendement was 0.23%.GC-MS analysis shown of some compound of terpenoid (naftalen derivated which correspondence to mass spectrum.One of them is copaene (C15H24, m/z = 204. Cream based of Rajin et al. formula giving stable cream, white colouredand neutral pH. Volatile oil of surian leaf in cream based cause color and aroma cream were changed. Cream stabilityalso was annoyed at oil of atsiri 10%.

  8. Ethnobotanical study of some of mosquito repellent plants in north-eastern Tanzania

    Directory of Open Access Journals (Sweden)

    Tenu Filemoni

    2008-08-01

    Full Text Available Abstract Background The use of plant repellents against nuisance biting insects is common and its potential for malaria vector control requires evaluation in areas with different level of malaria endemicity. The essential oils of Ocimum suave and Ocimum kilimandscharicum were evaluated against malaria vectors in north-eastern Tanzania. Methodology An ethnobotanical study was conducted at Moshi in Kilimanjaro region north-eastern Tanzania, through interviews, to investigate the range of species of plants used as insect repellents. Also, bioassays were used to evaluate the protective potential of selected plants extracts against mosquitoes. Results The plant species mostly used as repellent at night are: fresh or smoke of the leaves of O. suave and O. kilimandscharicum (Lamiaceae, Azadirachta indica (Meliaceae, Eucalyptus globules (Myrtaceae and Lantana camara (Verbenaceae. The most popular repellents were O. kilimandscharicum (OK and O. suave (OS used by 67% out of 120 households interviewed. Bioassay of essential oils of the two Ocimum plants was compared with citronella and DEET to study the repellence and feeding inhibition of untreated and treated arms of volunteers. Using filter papers impregnated with Ocimum extracts, knockdown effects and mortality was investigated on malaria mosquito Anopheles arabiensis and Anopheles gambiae, including a nuisance mosquito, Culex quinquefasciatus. High biting protection (83% to 91% and feeding inhibition (71.2% to 92.5% was observed against three species of mosquitoes. Likewise the extracts of Ocimum plants induced KD90 of longer time in mosquitoes than citronella, a standard botanical repellent. Mortality induced by standard dosage of 30 mg/m2 on filter papers, scored after 24 hours was 47.3% for OK and 57% for OS, compared with 67.7% for citronella. Conclusion The use of whole plants and their products as insect repellents is common among village communities of north-eastern Tanzania and the results

  9. 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

  10. Spatial repellents: from discovery and development to evidence-based validation

    Directory of Open Access Journals (Sweden)

    Achee Nicole L

    2012-05-01

    Full Text Available Abstract International public health workers are challenged by a burden of arthropod-borne disease that remains elevated despite best efforts in control programmes. With this challenge comes the opportunity to develop novel vector control paradigms to guide product development and programme implementation. The role of vector behaviour modification in disease control was first highlighted several decades ago but has received limited attention within the public health community. This paper presents current evidence highlighting the value of sub-lethal agents, specifically spatial repellents, and their use in global health, and identifies the primary challenges towards establishing a clearly defined and recommended role for spatial repellent products in disease control.

  11. 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

  12. Promising Aedes aegypti repellent chemotypes identified through integrated QSAR, virtual screening, synthesis, and bioassay.

    Science.gov (United States)

    Oliferenko, Polina V; Oliferenko, Alexander A; Poda, Gennadiy I; Osolodkin, Dmitry I; Pillai, Girinath G; Bernier, Ulrich R; Tsikolia, Maia; Agramonte, Natasha M; Clark, Gary G; Linthicum, Kenneth J; Katritzky, Alan R

    2013-01-01

    Molecular field topology analysis, scaffold hopping, and molecular docking were used as complementary computational tools for the design of repellents for Aedes aegypti, the insect vector for yellow fever, chikungunya, and dengue fever. A large number of analogues were evaluated by virtual screening with Glide molecular docking software. This produced several dozen hits that were either synthesized or procured from commercial sources. Analysis of these compounds by a repellent bioassay resulted in a few highly active chemicals (in terms of minimum effective dosage) as viable candidates for further hit-to-lead and lead optimization effort.

  13. Preliminary Exploration of a Novel Type High-effi-ciency Mosquito-repellent Compound Essential Oils

    Institute of Scientific and Technical Information of China (English)

    Pei; Jing; Zhou; Yin; Sun; Yizhe; Wang; Tao; Yang; Jingya

    2014-01-01

    The essential oils were extracted from flowers and branches of Cestrum genus plant Telosma cordata(Burm. F.) Merr.,and used for purifying the mosquito-repellent refined oils. The yielded extracts were mixed with single nerve-smoothing or nerve-exciting components from lavender and peppermint or mixed with basal oils(like evening primrose),in order to prepare the novel type compound essential oils conferring mosquito-repellent and air-refreshing actions. The resulted compound was prepared into solid air freshener.

  14. Rodent repellents: Preparation and properties of thiouronium compounds and cyclic imides

    Science.gov (United States)

    Bellack, E.; DeWitt, J.B.

    1954-01-01

    Syntheses and bioassays of cyclic imides and thiouronium compounds were carried out as part of a search for materials capable of preventing rodent damage to packaged commodities. Previous studies had shown that repellent activity was associated with functional groups containing nitrogen and sulfur, and was enhanced by the presence of ionic linkages. Twenty-seven thiouronium compounds and 40 imides, including 1 0 compounds not described previously, were prepared for these tests. Ten imides and 26 thiouronium compounds were repellent under the conditions of test. Information obtained in these studies will be utilized in the development and selection of more effective materials for prevention of rodent damage to foods and other commodities.

  15. Repellent and insecticide activity of Pelargonium x hortorum against Spodoptera littoralis (Boisd.).

    Science.gov (United States)

    Farag, Mohamed; Ahmed, Mohamed H M; Yousef, Heba; El-Badawey, Samy S; Abd El-Ghany, Melegi A; Abdel-Rahman, Adel A H

    2012-01-01

    Insecticide and repellent activity of an acetone extract and oil from fresh leaves of Pelargonium x hortorum (cv. Orangesonne) were evaluated against the 2nd and 4th instar larvae of Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae). The oil showed medium toxicity against the 2nd instar and low toxicity against the 4th instar larvae, while the extract showed high significant toxicity at all concentrations tested against the two instars. On the other hand, both oil and extract exhibited highly significant repellency against the two tested instars. Volatile constituents of the oil were also identified by GC-MS analysis.

  16. Offers for our members

    CERN Multimedia

    Staff Association

    2017-01-01

    Summer is coming, enjoy our offers for the aquatic parcs! Walibi : Tickets "Zone terrestre": 24 € instead of 30 €. Access to Aqualibi: 5 € instead of 6 € on presentation of your SA member ticket. Free for children under 100 cm. Car park free. * * * * * Aquaparc : Day ticket: – Children: 33 CHF instead of 39 CHF – Adults : 33 CHF instead of 49 CHF Bonus! Free for children under 5.

  17. Offers for our members

    CERN Multimedia

    Staff Association

    2017-01-01

    Summer is here, enjoy our offers for the aquatic parcs! Walibi : Tickets "Zone terrestre": 24 € instead of 30 €. Access to Aqualibi: 5 € instead of 6 € on presentation of your SA member ticket. Free for children under 100 cm. Car park free. * * * * * Aquaparc : Day ticket: – Children: 33 CHF instead of 39 CHF – Adults : 33 CHF instead of 49 CHF Bonus! Free for children under 5.

  18. Larvicidal and repellent activity of medicinal plant extracts from Eastern Ghats of South India against malaria and filariasis vectors

    Institute of Scientific and Technical Information of China (English)

    Chinnaperumal Kamaraj; Abdul Abdul Rahuman; Asokan Bagavan; Gandhi Elango; Abdul Abduz Zahir; Thirunavukkarasu Santhoshkumar

    2011-01-01

    Objective:To evaluate the larvicidal and repellent activities of ethyl acetate and methanol extracts ofAcacia concinna (A. concinna),Cassia siamea(C. siamea),Coriandrum sativum (C. sativum),Cuminum cyminum(C. cyminum),Lantana camara (L. camara),Nelumbo nucifera (N. nucifera)Phyllanthus amarus (P. amarus),Piper nigrum (P. nigrum) andTrachyspermum ammi(T. ammi) againstAnopheles stephensi(An. stephensi) andCulex quinquefasciatus (Cx. quinquefasciatus).Methods:The larvicidal activity of medicinal plant extracts were tested against early fourth-instar larvae of malaria and filariasis vectors. The mortality was observed 24 h and48 h after treatment, data were subjected to probit analysis to determine the lethal concentrations (LC50 andLC90) to kill50 and 90per cent of the treated larvae of the tested species. The repellent efficacy was determined against two mosquito species at five concentrations (31.25, 62.50, 125.00, 250.00, and 500.00 ppm) under the laboratory conditions.Results: All plant extracts showed moderate effects after24h and 48h of exposure; however, the highest activity was observed after24h in the leaf methanol extract ofN. nucifera, seed ethyl acetate and methanol extract ofP. nigrumagainst the larvae of An. stephensi(LC50 =34.76, 24.54 and30.20 ppm) and againstCx. quinquefasciatus (LC50= 37.49, 43.94 and57.39ppm), respectively. The toxic effect of leaf methanol extract ofC. siamea, seed methanol extract ofC. cyminum, leaf ethyl acetate extract ofN. nucifera, leaf ethyl acetate and methanol extract ofP. amarusand seed methanol extract ofT. ammiwere showed100% mortality againstAn. stephensi andCx. quinquefasciatus after48 h exposer. The maximum repellent activity was observed at500 ppm in methanol extracts ofN. nucifera, ethyl acetate and methanol extract ofP. nigrum and methanol extract ofT. ammi and the mean complete protection time ranged from30 to150 min with the different extracts tested. Conclusions:These results suggest that the leaf and seed

  19. Repellent and Attractive Effects of α-, β-, and Dihydro-β- Ionone to Generalist and Specialist Herbivores.

    Science.gov (United States)

    Cáceres, L A; Lakshminarayan, S; Yeung, K K-C; McGarvey, B D; Hannoufa, A; Sumarah, M W; Benitez, X; Scott, I M

    2016-02-01

    In plants, the oxidative cleavage of carotenoid substrates produces volatile apocarotenoids, including α-ionone, β-ionone, and dihydro-β-ionone, compounds that are important in herbivore-plant communication. For example, β-ionone is part of an induced defense in canola, Brassica napus, and is released following wounding by herbivores. The objectives of the research were to evaluate whether these volatile compounds would: 1) be released in higher quantities from plants through the over-expression of the carotenoid cleavage dioxygenase1 (CCD1) gene and 2) cause herbivores to be repelled or attracted to over-expressing plants relative to the wild-type. In vivo dynamic headspace collection of volatiles coupled with gas chromatography-mass spectrometry was used to determine volatile organic compounds (VOC) in the headspace of the Arabidopsis thaliana ecotype Columbia-0 (L.) over-expressing the AtCCD1 gene. The analytical method allowed the detection of β-ionone in the Arabidopsis headspace where emission rates ranged between 2 and 5-fold higher compared to the wild type, thus corroborating the in vivo enhancement of gene expression. A two chamber choice test between wild type and AtCCD1 plants revealed that crucifer flea beetle Phyllotreta cruciferae (Goeze) adults were repelled by the AtCCD1 plants with the highest transcription and β-ionone levels. α-Ionone and dihydro-β-ionone were not found in the headspace analysis, but solutions of the three compounds were tested in the concentration range of β-ionone found in the Arabidopsis headspace (0.05 to 0.5 ng/μl) in order to assess their biological activity with crucifer flea beetle, two spotted spider mite Tetranychus urticae (Koch), and silverleaf whiteflies Bemisia tabaci (Gennadius). Choice bioassays demonstrated that β-ionone has a strong repellent effect toward both the flea beetle and the spider mite, and significant oviposition deterrence to whiteflies. In contrast, dihydro-β-ionone had attractant

  20. [Comment on] BOSP members

    Science.gov (United States)

    Richman, Barbara T.

    The new Board on Ocean Science and Policy (BOSP) (Eos, June 7, 1983, p. 402) met for the first time on May 4. John B. Slaughter, former director of the National Science Foundation and now chancellor of the University of Maryland in College Park, is the board's chairman. Other board members are D. James Baker, Jr. (University of Washington, Seattle); Kirk Bryan (Geophysical Fluid Dynamics Laboratory, Princeton University); John P. Craven (University of Hawaii); Charles L. Drake (Dartmouth College); Paul M. Fye (Woods Hole Oceanographic Institution); Edward D. Goldberg (Scripps Institution of Oceanography); G. Ross Heath (Oregon State University); Judith T. Kildow (Massachusetts Institute of Technology); John A. Knauss (University of Rhode Island); James J. McCarthy (Museum of Comparative Zoology, Harvard University); H. William Menard (Scripps Institution of Oceanography); C. Barry Raleigh (Lamont-Doherty Geological Observatory); Roger Revelle (University of California, San Diego); David A. Ross (Woods Hole Oceanographic Institution); Brian J. Rothschild (University of Maryland); William M. Sackett (University of South Florida); John H. Steele (Woods Hole Oceanographic Institution); and Carl Wunsch (MIT). Wallace Broecker (Lamont-Doherty Geological Observatory), an original board member, resigned after the first meeting. Broecker told Eos that combining the science and policy boards resulted in a new board whose mission is too broad. A new board member will be appointed in Broecker's place