Academic literature on the topic 'Surface active agents – Analysis'
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Journal articles on the topic "Surface active agents – Analysis"
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Matsumoto, Kozo, Shin Tsuge, and Yukio Hirata. "Analysis of non-ionic surface active agents by supercritical fluid chromatography/mass spectrometry." Journal of the Mass Spectrometry Society of Japan 35, no. 1 (1987): 15–22. http://dx.doi.org/10.5702/massspec.35.15.
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Tubtimsri, Sukannika, and Yotsanan Weerapol. "Development of Nifedipine Amorphous Solid Dispersion Composed of Surface-Active Agents." Key Engineering Materials 901 (October 8, 2021): 35–39. http://dx.doi.org/10.4028/www.scientific.net/kem.901.35.
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The amorphous solid dispersions (ASDs) containing amino methacrylate copolymer and surface-active agents were prepared to improve the nifedipine (NDP) dissolution. The different types of surface-active agent i.e., polysorbates 80, sodium lauryl sulfate (SLS) and polyethylene glycol (PEG) 400 were used. In order to evaluate the ASDs formulation,powder X-ray diffractometry and thermal analysis to characterize NDP crystallinity in ASDs and the dissolution study of NDP have been performed to compare the dissolution profiles. The ASDs were kept for 6 months to investigate the stability. In the X-ray diffraction pattern, no peak was observed in all samples of ASDs. No peak was found in sample of all ASDs from the thermograms. These results suggest that the drug may be molecularly dispersed in matrix of amino methacrylate copolymer. The drug dissolution at 120 min, from ASDs without surface-active agent and NDP powder were 58.31% and 17.95%, respectively. The dissolved NDP from ASDs composed of SLS, polysorbate 80 and PEG400 were 96.25%, 88.86% and 75.32%, respectively. These results may occur due to the reduction of surface tension, the addition of the low amount of high efficiency of surface-active agent e.g., SLS (compared with PEG400 and polysorbate 80) provided the higher NDP dissolution. The content analysis of NDP in selected ASDs was studied at the end of 3 and 6 months, the NDP content remained unchanged after storage.
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Matysik, J., H. Kroszka, and A. Persona. "Analysis of Cationic Surface Active Agents Using DME and Its Relevance to Their Adsorption." Adsorption Science & Technology 4, no. 1-2 (March 1987): 53–57. http://dx.doi.org/10.1177/0263617487004001-205.
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The paper describes an application of dropping mercury electrode (DME) for analytical determination of certain cationic surface active agents and their mixtures and presents obtained thermodynamical data of adsorption of investigated substances.
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Thakur, Rachna, Sandya Devi S. Patil, Anil Kush, and K. Madhu. "SEM Analysis of Residual Dentin Surface in Primary Teeth Using Different Chemomechanical Caries Removal Agents." Journal of Clinical Pediatric Dentistry 41, no. 4 (January 1, 2017): 289–93. http://dx.doi.org/10.17796/1053-4628-41.4.289.
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Background: The purpose of this in vitro study was to analyze the residual dentinal surfaces following caries removal using two chemomechanical methods (Papacarie Duo and Carie Care), by scanning electron microscopy (SEM). Study design: Twenty extracted primary molars with active occlusal carious lesions were randomly assigned two groups depending on the CMCR agent used for the caries excavation – Group 1 – with Papacarie Duo and Group – 2 with Carie Care. After the caries excavation, the specimens were subjected to SEM analysis. Results: Though both the agents showed the minimal smear layer with the patent dentinal tubules, Carie care showed patent dentinal tubules with a clearly exposed peritubular and intertubular collagen network. Conclusion: Carie Care treated surface exhibited better surface morphology of residual dentin.
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Kurochkin, I., I. Ryzhikov, A. Sarychev, K. Afanasiev, I. Budashov, M. Sedova, I. Boginskaya, S. Amitonov, and A. Lagarkov. "New SERS-active junction based on cerium dioxide facet dielectric films for biosensing." Advanced Electromagnetics 3, no. 1 (October 23, 2014): 57. http://dx.doi.org/10.7716/aem.v3i1.266.
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Further enhance of the Raman scattering is the priority for the development of the modern molecular diagnostic methods. Expected increasing in detection sensitivity of the biological and chemical agents provides substantial progress in such areas as: proteomics (discovery of new disease markers), pharmacokinetics of drugs, analysis of toxins and infections agents, drug analysis, food safety, and environmental safety.In this paper we investigated the possibility of the facet structures, based on cerium dioxide to further enhance the SERS signal. During the studies a new metamaterial was developed. The metamaterial is based on the facet cerium dioxide films and plasmonic nanoparticles that are immobilized on its surface. The new metamaterial provides additional SERS signal amplification factor of 211. Thus developed material offers the prospect of increasing the sensitivity and selectivity of biochemical and immunological analysis.
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Shang Guan, Chang Cheng, Xing Long Zhou, Dong Yang Sun, and Peng Xiang Zhang. "Study on Flotation of Refractory Phosphorite at Normal Temperature." Applied Mechanics and Materials 522-524 (February 2014): 1488–92. http://dx.doi.org/10.4028/www.scientific.net/amm.522-524.1488.
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This article unfolded experiments of three kinds of normal temperature collector applying to a refractory phosphorite.The results showed that CC-1(the collector self-prepared) had higher collecting capacity,selecting feature than other collectors.Meanwhile,analysis of the action mechanism of surface active agents to increase effect and dissolving in CC-1 had been made.
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Gutierrez, Tony, Gordon Morris, Dave Ellis, Barbara Mulloy, and Michael D. Aitken. "Production and characterisation of a marine Halomonas surface-active exopolymer." Applied Microbiology and Biotechnology 104, no. 3 (December 7, 2019): 1063–76. http://dx.doi.org/10.1007/s00253-019-10270-x.
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AbstractDuring screening for novel emulsifiers and surfactants, a marine gammaproteobacterium, Halomonas sp. MCTG39a, was isolated and selected for its production of an extracellular emulsifying agent, P39a. This polymer was produced by the new isolate during growth in a modified Zobell’s 2216 medium amended with 1% glucose, and was extractable by cold ethanol precipitation. Chemical, chromatographic and nuclear magnetic resonance spectroscopic analysis confirmed P39a to be a high-molecular-weight (~ 261,000 g/mol) glycoprotein composed of carbohydrate (17.2%) and protein (36.4%). The polymer exhibited high emulsifying activities against a range of oil substrates that included straight-chain aliphatics, mono- and alkyl- aromatics and cycloparaffins. In general, higher emulsification values were measured under low (0.1 M PBS) compared to high (synthetic seawater) ionic strength conditions, indicating that low ionic strength is more favourable for emulsification by the P39a polymer. However, as observed with other bacterial emulsifying agents, the polymer emulsified some aromatic hydrocarbon species, as well as refined and crude oils, more effectively under high ionic strength conditions, which we posit could be due to steric adsorption to these substrates as may be conferred by the protein fraction of the polymer. Furthermore, the polymer effected a positive influence on the degradation of phenanthrene by other marine bacteria, such as the specialist PAH-degrader Polycyclovorans algicola. Collectively, based on the ability of this Halomonas high-molecular-weight glycoprotein to emulsify a range of pure hydrocarbon species, as well as refined and crude oils, it shows promise for the bioremediation of contaminated sites.
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Dzevochko, O., M. Podustov, and A. Dzevochko. "SYSTEM ANALYSIS OF THE SULFATION PROCESS IN THE PRODUCTION OF SURFACTANT SUBSTANCES." Integrated Technologies and Energy Saving, no. 4 (December 12, 2022): 23–38. http://dx.doi.org/10.20998/2078-5364.2022.4.03.
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Data on the use of surface-active substances in various areas of Ukrainian industry are given. The rapid development of the production of surface-active substances is shown. The main stages of the production of surface-active substances are given. It is shown that the sulfation stage is the main one, at which high quality indicators of the obtained products are achieved.
The main disadvantages and advantages of sulfating agents in the technology of surface-active substances (surfactants) are given. The characteristics of the equipment and technological schemes of the sulfation process of organic substances are given.
It is claimed that the use of tubular film absorbers with a downward flow of phases is currently the most promising for use in industrial conditions.
Convective diffusion equations for the simplified models of Lewis – Whitman, Levich, Higby, Dankverts are given.
It is proposed to present the process of sulfation in a tubular film absorber with the following stages: the process of mass transfer of gaseous sulfur trioxide to the surface of the interface, the process of absorption of sulfur trioxide by an organic substance with the passage of an exothermic chemical reaction, the process of heat exchange between the liquid phase and the gaseous air flow, the process of heat exchange between the liquid phase and the flow of cooling water. The equation for calculating the mass transfer coefficient is given, which allows obtaining data close to Gutierrez's experimental data. The passage of successive chemical reactions during the absorption of sulfur trioxide by organic raw materials is shown. Kinetic equations and methods of calculating the degree of sulfation and color of the obtained products are given. Basic equations for calculating heat transfer coefficients and heat transfer coefficients are given.
The results of mathematical modeling of the sulfation process in a tubular film absorber are given.
The possibility of achieving high quality indicators of the obtained product is shown: the degree of sulfation is 97,9 %, the color is 1 unit on the iodine scale.
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Cheng, Chien Min, Kai Huang Chen, Yuan Tai Hsieh, and Fuh Cheng Jong. "The Preparation of Flexible Substrate Using BaTiO3/Polymer Composites for Application in High Frequency Devices." Key Engineering Materials 512-515 (June 2012): 1142–45. http://dx.doi.org/10.4028/www.scientific.net/kem.512-515.1142.
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BaTiO3/ which has good dielectric properties, they were widely used in ceramic capacitors, thermistors, etc. In this study, BaTiO3/ ceramics prepared by sol-gel powder, then mixed in the organic polymer polyether imide (PEI) and dispersant (surface active agents) and silane coupling agent (Silane Coupling Agent) of the composite material on flexible substrates, And analysis of its properties and electrical properties. Increase by a ceramic powder, to explore the impact of the substrate. In the physical analysis is used XRD, SEM to measure the intensity of crystalline phase and surface uniformity of the electrical measurement using HP4294 measuring dielectric constant and dielectric loss.
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Казаков, Алексей Васильевич, Роман Александрович Емельянов, Дмитрий Викторович Бухтояров, and Денис Владимирович Полтавец. "ANALYSIS OF MODERN TECHNOLOGIES FOR EXTINGUISHING ACTIVE METALS." Pozharnaia bezopasnost`, no. 4(109) (December 16, 2022): 29–35. http://dx.doi.org/10.37657/vniipo.pb.2022.109.4.002.
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Проведен анализ огнетушащих составов, применяемых для тушения активных металлов (пожары класса D). Отмечено, что основные современные средства обеспечения пожаротушения представляют собой галогенсодержащие соли (фториды или хлориды щелочных и щелочно-земельных металлов), препятствующие доступу кислорода без ингибирующего эффекта по отношению к самому горящему металлу. При этом данные солевые композиции не лишены недостатков из-за их высокой гигроскопичности (содержания кристаллизационной воды), что усложняет тушение. Ввиду последнего разработка более эффективных огнетушащих составов для тушения активных металлов является достаточно актуальной и перспективной. Ignition of active metals and their alloys often results in significant material damage. This determines the relevance for development of means to eliminate the possibility of ignition of metals and their alloys in zones of their most likely occurrence - during their melting and refining in metallurgical processes, in the technological processes of their processing and manufacturing of products by enterprises of various industries. For these purposes it is necessary to equip both consumers and special fire departments with highly effective means to ensure fire safety. Burning of active metals is characterized by a very rapid development of the oxidation reaction in the air due to their high reactivity. At the same time, for example, in a D1 class fire (burning of light metals except alkaline), the upper temperature threshold can reach 3000 °C. Alkaline and alkaline-earth metals are able to sustain combustion with limited air oxygen or contact with nitrogen or oxygen-containing substances. Extinguishing metals and their compounds differs from extinguishing fires of other classes. The main extinguishing agent used at protection facilities is a special purpose extinguishing powder. Class D fire extinguishing with a special purpose extinguishing powder consists in creating a protective layer on the burning surface. The use of calming nozzles practically prevents the formation of the air suspension when applying a fire extinguishing agent to burning area. Thus, the principle of extinguishing metals with powder extinguishing agents is to isolate and interrupt the chain reaction of burning. Despite the sufficient effectiveness of the powder compositions used, there was also identified a number of significant drawbacks in the work: a large consumption of extinguishing agent, the difficulty of supplying extinguishing agent to the hearth due to high temperature, the high cost of special extinguishing powders of a new generation, etc. As a matter of fact, it is concluded that the search for more effective means of extinguishing fires of metals and their alloys is relevant and promising, with the absence of these shortcomings.
Dissertations / Theses on the topic "Surface active agents – Analysis"
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Staggemeier, Bethany Ann. "Dynamic surface tension detection : novel applications to continuous flow analysis and interfacial analysis /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/11584.
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Choi, Pik Kwan. "Development and application of surfactant-mediated methods for the extraction and analysis of biological and herbal materials." HKBU Institutional Repository, 2002. http://repository.hkbu.edu.hk/etd_ra/427.
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Cheng, Ka Yu. "Effects of surfactants and organic amendments on phytoremediation of polycyclic aromatic hydrocarbons (PAHs) contaminated soil." HKBU Institutional Repository, 2005. http://repository.hkbu.edu.hk/etd_ra/630.
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Olson, Nels A. "Development of an analyzer for surface active species in flow injection and liquid chromatography environments /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/8547.
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Rajatanavin, Pajaree, and pajaree@sympatico ca. "Solid-stabilised foams produced using a mixed surfactant system." Swinburne University of Technology, 2005. http://adt.lib.swin.edu.au./public/adt-VSWT20060504.153041.
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Studies involving solids-stabilised foams have been limited and few have focused on the benefits of complex systems such as those involving mixtures of more than one surfactant. Little is known about the effectiveness of using mixed surfactant systems as foam stabilisers at the bulk level. The purpose of this project was to gain further understanding and insight into foam stability, on a bulk scale, in the absence, and in the presence, of solid colloidal particles, and for systems involving single or mixed surfactants.
Foams were produced using sodium dodecyl sulphate (SDS), dodecanoic acid (DA), or a mixture of both surfactants at varying molar ratios. The surface tension at a given concentration, the limiting surface tension (at high concentrations), the critical micelle concentration, foamability and foam stability were all significantly affected by the molar ratio of SDS to DA. The initial pH of mixed surfactant solutions played a role in the shift of surface tension and CMC. The higher pH values, the lower surface activity, therefore resulted in higher surface tension. At a given pH, however, the mixed surfactant solutions with higher molar ratio of SDS to DA appeared to have lower CMC.
The foam stabilising ability of colloidal dispersions of four hydrous metal oxides, namely hydrous iron oxide (formed by hydrolysis of Fe(III) solutions and referred to as HFO), hydrous zinc oxide (formed by hydrolysis of Zn(II) solutions and referred to as HZO), hydrous chromium oxide (formed by hydrolysis of Cr(III) solutions and referred to as HCO), and hydrous nickel oxide (formed by hydrolysis of Ni(II) solutions and referred to as HNO) were studied at varying concentrations. Generally foam stability increased as the solid concentration increased. Foams stabilised by HNO were found to be the most stable. Foams stabilised by HFO were found to be unstable regardless of the solid concentration. It is believed that the instability of such foams is primarily due to the large aggregated size of HFO flocs. The aggregate size of hydrous metal oxides was influenced by the concentration of NaOH used to hydrolyse the metal ion solution, and by sonication treatment immediately following solid formation. However, the final pH of the colloidal dispersions did not significantly change the aggregate size.
Solids stabilised foams are believed to be highly dependent on the state of hydrophobicity of the solids used, and this is in turn controlled by adjustment of the pH dependent surface charge and potential. Electrophoretic mobility is a commonly used tool to probe the potential near the surface and was used in this thesis to determine the affect of surfactant adsorption (particularly from solutions containing mixtures of SDS and DA) on surface properties of the solids. The electrophoretic mobility of all hydrous metal oxide aggregates decreased as the concentration of SDS/DA increased. Specific adsorption was evident in all cases and resulted in charge reversal for most cases. Electrophoretic mobility data for surfactant adsorption, as a function of total surfactant concentration, was consistent with a three-stage model of surfactant adsorption involving (1) electrostatic adsorption, (2) cooperative adsorption and (3) surface saturation. The influence of surfactant adsorption on electrophoretic mobility was found to be consistent with models requiring the stabilising solids to be in a controlled state of flocculation, where the zeta potential (as probed by electrophoretic mobility) must be sufficiently high to prevent total flocculation of the solid and thus collapse of the foam, but sufficiently low that the solids have some degree of hydrophobicity such that they prefer to be only partially wetted (and thus reside at the air/water interface).
The total percentage adsorption of SDS/DA surfactant mixtures on both hydrous iron oxide and hydrous nickel oxide was found to be independent of time. However, the proportion of adsorption due to SDS and DA was dependent on time. Moreover, the initial and final ratio of SDS to DA adsorption did not reflect their ratio in solution. SDS adsorbed, initially, to a greater extent that would be predicted from its solution concentration, but this trend was reversed after a period of time.
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Desbrosses, Mickaël. "Contribution de la Spectrométrie de Masse d’Ions Secondaires à Temps de Vol au développement de textiles industriels fonctionnels impliquant des agents actifs cosmétiques." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1117.
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La Spectrométrie de Masse d'Ions Secondaires à Temps de Vol (ToF-SIMS) permet la caractérisation de l'extrême surface à haute sensibilité via la détection d'ions secondaires atomiques et moléculaires. Ces travaux ont visé à étudier son application pour l'analyse de textiles industriels auxquels ont été conférées des propriétés dermatologiques (cosmétotextiles). Trois démarches analytiques adaptées aux spécificités des agents actifs et des technologies utilisées ont été présentées. Elles ont nécessité un développement particulier des méthodes employées (étude préliminaire, calibration, traitement et interprétation des données) et de tenir compte des possibilités et des limites de la technique ou de l'appareillage utilisé dans le contexte particulier de l'analyse des fibres textiles (topographie, effet de charge localisé, contaminations, formulations complexes, ségrégation et concentration de certains constituants des traitements en extrême surface).Dans la première démarche, la cartographie chimique ToF-SIMS a été utilisée avec succès pour illustrer l'existence d'un gradient de concentration en agent actif près de l'extrême surface de matrices polyamides. La capacité à identifier les signatures caractéristiques des agents actifs et valider leur présence en surface des échantillons textiles a pu être confirmée dans la majorité des cas. Cependant l'utilisation de signatures différentes de celles de l'agent actif a été nécessaire pour valider la présence de traitement dans le cas des textiles traités par co-précipitation. Enfin, un protocole de décapage doux a été testé pour faire face au problème particulier du recouvrement des textiles industriels par des apprêts siliconésTime-of-Flight Secondary Ion Mass spectrometry (ToF-SIMS) allows the characterization of the outermost surface with high sensitivity by mass detection of atomic and molecular secondary ions. The objective of this work was to study its application in the context of the analysis of industrial textiles on which dermatological properties are given (cosmetotextiles). Three analytical approaches based on the specific properties of the active agents and technologies are presented. They required peculiar developments of methods (preliminary study, calibration, data processing and interpretation ...) and to consider the possibilities and limitations of the technique or the equipment in the particular context of these textile fibers analysis (topography, localized charge effect, contamination, complex formulations, segregation and concentration of some components from the treatments at the outermost surface ...).In the first approach, ToF-SIMS chemical mapping was used to successfully illustrate an active agent concentration gradient close to the outermost surface of polyamide matrices. The ability to identify the characteristic signatures of active agents and to validate their presence at the surface of textile samples was confirmed in most cases. However, signatures different from those from the active agent were needed to validate the treatment in the case of textiles treated by co-precipitation. Finally, a gentle sputtering protocol was tested to address the particular issue of industrial textiles covered with silicone based textile finishing
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Auberlet, Delle-Vedove Agnès. "Synthèse et étude structurale de n-benzoyl-n'-phenylurees, insecticides, en vue d'établir une relation entre la structure, la rétention dans des adsorbants modèles et le mode de dégradation. Suivi de recherches sur l'enseignement expérimental de la formulation : étude d'une famille de tensioactifs." Angers, 1995. http://www.theses.fr/1995ANGE0002.
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Dans une première partie, cinq n-benzoyl-n'-phenylurees sont synthétisées, en vue de modéliser leurs interactions avec l’environnement : rétention dans les sols, dégradation. Ces molécules sont des insecticides rémanents agissant par inhibition de la biosynthèse de la chitine. L'analyse d'extraits d'adsorbants modèles traites avec ces molécules est effectuée par chromatographie liquide haute pression en phase inverse. L'étude structurale de ces molécules est réalisée par la combinaison de diverses techniques spectroscopiques : spectrométrie de masse, spectroscopie de rayons X, RMN du proton, du carbone 13, de l'azote 15, spectroscopies U. V. Et infra-rouge, ainsi que par chromatographie sur couche mince, mécanique moléculaire et calcul semi-empirique am1. D'une part nous en déduisons une relation entre la coplaneite du groupe urée et du groupe 4- chlorophényle et la rétention sur adsorbants. D'autre part les indices de liaison, la fragmentation de masse et les études conformationnelle permettent d'interpréter la dégradation du composé, '- difluoré en urée et acide benzoïque tandis que dans les mêmes conditions le composé, '- dichlore est dégradé en benzamide et aniline substituées. Dans une seconde partie, nous présentons un projet didactique d'enseignement expérimental de la formulation, portant sur une famille de tensio-actifs utilisés dans les préparations phytosanitaires : détermination de la concentration micellaire critique, de la H. L. B. , de la température de trouble.
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Wahlgren, Marie. "Adsorption of proteins and interactions with surfactants at the solid/liquid interface." [Lund : Dept. of Food Technology, Lund University], 1992. http://books.google.com/books?id=zfxqAAAAMAAJ.
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Mobbs, Tamara Leah. "Effects of four soil surfactants on four soil-water properties in sand and silt loam." Pullman, Wash. : Washington State University, 2010. http://www.dissertations.wsu.edu/Thesis/Spring2010/t_mobbs_050110.pdf.
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Thesis (M.S. in biological and agricultural engineering)--Washington State University, May 2010.Title from PDF title page (viewed on June 23, 2010). "Department of Biological Systems Engineering." Includes bibliographical references (p. 16-22).
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Mendoza, Alvaro. "The synthesis and characterization of novel surfactants." Laramie, Wyo. : University of Wyoming, 2006. http://proquest.umi.com/pqdweb?did=1296090131&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
Full textBooks on the topic "Surface active agents – Analysis"
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Schmitt, Thomas M. Analysis of surfactants. New York: M. Dekker, 1992.
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Analysis of surfactants. 2nd ed. New York: Marcel Dekker, 2001.
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C, Cullum D., ed. Introduction to surfactant analysis. London: Blackie Academic & Professional, 1994.
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1937-, Cross John, ed. Nonionic surfactants: Chemical analysis. New York: M. Dekker, 1987.
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Hummel, Dieter O. Handbook of surfactant analysis: Chemical, physico-chemical, and physical methods. New York: John Wiley, 1999.
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P, Knepper T., Barceló Damià, and Voogt Pim de, eds. Analysis and fate of surfactants in the aquatic environment. Amsterdam: Elsevier, 2003.
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1937-, Cross John, ed. Anionic surfactants: Analytical chemistry. 2nd ed. New York: Marcel Dekker, 1998.
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Voelkel, Adam. Badania polarności niejonowych związków powierzchniowo czynnych metodą chromatografii gazowej. Poznań: Politechnika Poznańska, 1989.
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1949-, Hinze Willie L., Armstrong Daniel W. 1949-, American Chemical Society. Division of Analytical Chemistry., American Chemical Society Meeting, and Symposium on Use of Ordered Media in Chemical Separations (1986 : New York, N.Y.), eds. Ordered media in chemical separations. Washington, DC: The Society, 1987.
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L, Křivánková, and Boček P, eds. Capillary zone electrophoresis. Weinheim: VCH, 1993.
Find full textBook chapters on the topic "Surface active agents – Analysis"
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Paulus, Wilfried. "Surface Active Agents." In Microbicides for the Protection of Materials, 375–400. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-2118-7_18.
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Gooch, Jan W. "Surface-Active Agents." In Encyclopedic Dictionary of Polymers, 715. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_11429.
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Moroi, Yoshikiyo. "Surface-Active Agents." In Micelles, 7–24. Boston, MA: Springer US, 1992. http://dx.doi.org/10.1007/978-1-4899-0700-4_2.
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Paulus, Wilfried. "Surface active agents." In Directory of Microbicides for the Protection of Materials, 707–33. Dordrecht: Springer Netherlands, 2004. http://dx.doi.org/10.1007/1-4020-2818-0_41.
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Albert, Adrien. "Surface chemistry.The modifiction of membranes by surface-active agents." In Selective Toxicity, 590–610. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-009-4846-4_14.
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Jacobasch, H. J. "Adsorption Behaviour Of Surface Active Agents And Electrokinetic Phenomena." In Surfactants in Solution, 381–96. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4613-0839-3_29.
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Sharma, Deepansh. "Screening of Biosurfactants." In Biosurfactants: Greener Surface Active Agents for Sustainable Future, 37–77. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-2705-7_2.
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Sharma, Deepansh. "Industrial Applications of Biosurfactants." In Biosurfactants: Greener Surface Active Agents for Sustainable Future, 115–43. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-2705-7_4.
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Sharma, Deepansh. "Commercial Production, Optimization, and Purification." In Biosurfactants: Greener Surface Active Agents for Sustainable Future, 79–113. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-2705-7_3.
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Sharma, Deepansh. "Role of Biosurfactants in Agriculture and Soil Reclamation." In Biosurfactants: Greener Surface Active Agents for Sustainable Future, 145–74. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-2705-7_5.
Full textConference papers on the topic "Surface active agents – Analysis"
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Ma, Qisheng, Wenjie Xia, Yongchun Tang, Mohamed Haroun, Md Motiur Rahman, Muhammad Gibrata, Lamia Rouis, et al. "Novel Nano and Bio-Based Surfactant Formulation for Hybrid Enhanced Oil Recovery Technologies." In SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/206288-ms.
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Abstract This investigation presents laboratory and field deployment results that demonstrate the potential candidacy utilizing Nano and bio-technologies to create superior chemicals for novel applications to increase oil recovery from both onshore and offshore reservoirs. Nano-technology is gaining momentum as a tool to improve performance in multiple industries, and has shown significant potential to enhance hydrocarbon production. The laboratory analysis and specifically designed coreflood results indicate there are beneficial interactions at liquid-nano solid interface that increase oil mobility. This will increase the surface activity of chemical surfactants and thereby make them the dominant agents to mobilize and recover oil from oil-bearing reservoirs. Advances in biotechnology offer another rich resource of knowledge for surface active materials that are renewable and more environmental-friendly. In addition, our studies also demonstrate that bio-surfactants are well-suited to provide superior performances in enhancing oil recovery. Nano-particles and biosurfactants may be included with synthetic surfactants to create novel and more efficient surface active agents for enhanced oil recovery. These formulations can promote better flow back of the injected stimulation fluids and additional mobilization to extract more oil from the matrix and micro-fractures. Laboratory experiments demonstrate that the specialized surfactant formulations created, interact with mixed or oil-wet low permeability formations to produce additional oil. Furthermore, this investigation also compares the total production on a candidate field with respect to typical water flood and the novel formulated surfactant approach. For each surfactant treatment, the overall designed injected fluid volume is 1500 m3 (~ 396,000 gallons) with 4 gpt (gallon per thousand unit) of surfactant concentration. Results indicate improved oil production with longer exposure time of the key surfactants within the reservoir. Enhanced surface wetting and super-low interfacial tension (IFT) at lower chemical concentrations are recognized to be the main mechanisms. The novel surfactant also shows stronger sustainability and endurance in keeping rock surface wettability over traditional surfactant system up to 5 times for an 8 PV wash. Furthermore, this can assist to identify and initiate the optimization of the identified mechanisms for potential applications within other compatible reservoirs. A number of successful field applications of EOR with special formulated nano and bio-based surfactant formulation are discussed in this paper. This unique study bridges the gap between the field realized results and lab optimization to enhance feasibility as a function of time and cost.
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Dapper, Maik, Hermann-Josef Wagner, and Marco K. Koch. "Assessment of Film Drop Release From Liquid Pools by an Empirical Correlation Approach." In 16th International Conference on Nuclear Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/icone16-48239.
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The present work deals with the topic of wet resuspension, particularly with regard to the basics of film drop release from bubbles and its impact on the aerosol source term as well as with the development of an empirical correlation approach adapted to the containment code system COCOSYS at low atmosphere motion. Film drops are discharged from the lamella of a bubble during the disruption process, while the bubble is resting at the fluid surface. Besides the description of the bubble disruption process, factors which have an influence on the mass and size distribution of the drops released from the bubble lamella are discussed. To analyse the distribution of the film drops of different bubble sizes, measured film drop distributions of several bubble diameters were collected from the literature. The analysis shows that with the presence of surfactants (surface-active agents) a log-normal count distribution can be used for the approximation of the drop distribution. By the evaporation of the liquid of the released film drops the solved and/or suspended materials remain as particles. In dependence of their size the drops or particles are airborne or fall back onto the liquid pool surface. The remaining airborne drops/particles are able to contribute in the late phase of a severe accident to the source term, if they are radioactive.
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Azuokwu, Augustine Azubike, Yakubu Yerima, and Rowland Ugochukwu Azike. "Production and Performance Evaluation of Biodetergents as an Alternative to Conventional Drilling Detergent." In SPE Nigeria Annual International Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/207167-ms.
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Abstract Drilling detergents are among the chemical compounds that are increasingly being used in many varieties of drilling fluids. They are aqueous blend of surface-active agents that reduces the surface tension of water-based drilling fluids, reduces the sticking tendency of water-sensitive shale cuttings and aid cuttings removal; leading to cleaner hole, faster penetration rates and lower drilling pressure. Due to the increase in environmental issues associated with the disposal of drilling detergent presently used, drilling companies are exploring options of using environmentally friendly, degradable and renewable drilling detergents. In this study, biodetergents were produced from non-edible seed oils (Ricinus communis oil and Azadirachta Indica oil). The biodetergents and a commercial drilling detergent used in the Niger Delta field were analysed for a number of standard properties required for good drilling detergents. Drilling muds formulated with these detergents were also analysed for a number of standard mud properties. Physicochemical properties analyses showed that biodetergents met the required specification of good drilling detergents. The physicochemical properties of the biodetergents were also comparable to that of commercial drilling detergent. BOD values obtained showed that the biodetergents could easily be broken or biodegraded than the commercial drilling detergent. Toxicity test on Penaeus Monodon showed that biodetergents are more environmentally friendly than the commercial drilling detergent. Drilling mud properties analyses further showed that synthesized biodetergents can be used as an alternative to conventional drilling detergent.
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Tucureanu, Vasilica, Marian Popescu, Cosmin Romanitan, Iuliana Mihalache, Bianca Tincu, Marioara Avram, and Alina Matei. "Interaction of oxide nanoparticles with surface-active agents." In Advanced Topics in Optoelectronics, Microelectronics and Nanotechnologies IX, edited by Ionica Cristea, Marian Vladescu, and Razvan D. Tamas. SPIE, 2018. http://dx.doi.org/10.1117/12.2323589.
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Obeyesekere, Nihal U., and Jonathan J. Wylde. "Development of New Corrosion Inhibitors Using Robotics with High Throughput Experimentation Methods." In Abu Dhabi International Petroleum Exhibition & Conference. SPE, 2021. http://dx.doi.org/10.2118/207336-ms.
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Abstract Critical micelle concentration (CMC) is a known indicator for surfactants such as corrosion inhibitors ability to partition from two phase systems such as oil and water. Most corrosion inhibitors are surface active and at critical micelle concentration, the chemical is partitioned to water, physadsorb on metallic surfaces and form a physical barrier between steel and water. This protective barrier thus prevents corrosion from taking place on the metal surface When the applied chemical concentration is equal or higher than the CMC, the chemical is available in aqueous phase, thus preventing corrosion. Therefore, it was suggested that CMC can be used as an indicator of optimal chemical dose for corrosion control1. The lower the CMC of a corrosion inhibitor product, the better is this chemical for corrosion control as the availability of the chemical in the aqueous phase increase and therefore, can achieve corrosion control with less amount of chemical. In this work, this physical property (CMC) was used as an indicator to differentiate corrosion inhibitor performance. The corrosion inhibitor formulations were built out by using combinatorial chemical methods and the arrays of chemical formulations were screened by utilizing high throughput robotics 2-4, using CMC as the selection guide. To validate the concept, several known corrosion inhibitor formulas were selected to optimize their efficacy. Each formula contained several active ingredients and a solvent package. These raw materials were blended in random but in a control, manner using combinatorial methodologies. Instead of rapidly blending a large number of formulations using robotics, the design of control (DOE) methods were utilized to constrain the number of blends. Once the formulations were generated by DOE method, using Design Expert software that can effectively explore a desired space. The development of an equally robust prescreening analysis was also developed. This was done by using the measurements of CMC with a high-throughput screening methodology. After formulation of a vast array of formulation by using Design Expert software, the products were screened for by CMC using automated surface tension workstation. Several formulations with lower CMC than the reference products were selected. The selected corrosion inhibitor formulations were identified and blended in larger scales. The efficacy of these products was tested by classical laboratory testing methods such as rotating cylinder electrode (RCE) and rotating cage autoclave (RCA) to determine their performance as anti-corrosion agents. These tests were performed against the original reference corrosion inhibitor. The testing indicated that several corrosion inhibitor formulations outperform the original blend thus validating the proof of concept.
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Aurelio, Mario, Kristine Joy Taguibao, Edmundo Vargas, Maria Visitacion Palattao, Rolando Reyes, Carl Nohay, Roy Anthony Luna, and Alfonso Singayan. "Geological Criteria for Site Selection of an LILW Radioactive Waste Repository in the Philippines." In ASME 2013 15th International Conference on Environmental Remediation and Radioactive Waste Management. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icem2013-96127.
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In the selection of sites for disposal facilities involving low- and intermediate-level radioactive waste (LILW), International Atomic Energy Agency (IAEA) recommendations require that “the region in which the site is located shall be such that significant tectonic and surface processes are not expected to occur with an intensity that would compromise the required isolation capability of the repository”. Evaluating the appropriateness of a site therefore requires a deep understanding of the geological and tectonic setting of the area. The Philippines sits in a tectonically active region frequented by earthquakes and volcanic activity. Its highly variable morphology coupled with its location along the typhoon corridor in the west Pacific region subjects the country to surface processes often manifested in the form of landslides. The Philippine LILW near surface repository project site is located on the north eastern sector of the Island of Luzon in northern Philippines. This island is surrounded by active subduction trenches; to the east by the East Luzon Trough and to the west by the Manila Trench. The island is also traversed by several branches of the Philippine Fault System. The Philippine LILW repository project is located more than 100 km away from any of these major active fault systems. In the near field, the project site is located less than 10 km from a minor fault (Dummon River Fault) and more than 40 km away from a volcanic edifice (Mt. Caguas). This paper presents an analysis of the potential hazards that these active tectonic features may pose to the project site. The assessment of such geologic hazards is imperative in the characterization of the site and a crucial input in the design and safety assessment of the repository.
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E. L., Terechova, Wang Guowen, Xu Xiaochen, and Yang Fenglin. "Conditions of surface-active agents in wastewaters from laundries of railway enterprises." In The International Conference on Remote Sensing,Environment and Transportation Engineering. Paris, France: Atlantis Press, 2013. http://dx.doi.org/10.2991/rsete.2013.149.
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Cortés-Medellín, Germán. "Active surface segmentation analysis of CCAT." In SPIE Astronomical Telescopes + Instrumentation, edited by Larry M. Stepp. SPIE, 2006. http://dx.doi.org/10.1117/12.670312.
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Radulescu, Victorita. "New Solution With Syntheses Inhibitors for the Chemical Cleaning of Organic Pollutants From the Water Supply System Of Generators." In ASME 2021 Power Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/power2021-64314.
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Abstract In thermal power plants, during the boilers functioning, heterogeneous deposits of substances must often be removed in order to prolong their operation and avoid their deterioration. The nature, type and quantity of deposits depend on the characteristics of the water supply systems and the chemical operating regime. For boilers with high deposits of copper and iron, the utilization of mineral acids for chemical cleaning is not quite effective, because their surfaces may be covered with a metal copper film. Organic impurities in the water supply affect the operation of steam generators, increasing electrical conductivity and lowering the pH. The heterogeneous composition of the deposits is unevenly distributed in the combustion system, making its cleaning a complex problem. For efficient chemical cleaning, the agents must have a minimal corrosive action on the metal surfaces, ensuring only the dissolution of the compounds on the surface of the boilers. To prevent corrosion of metals, inhibitors are introduced to diminish the reactions on the metal surface or at least to delay the kinetics of the reaction. This paper analyzes the implications of organic pollutants in the corrosion phenomena and chemical processes where they are involved. As an example, the power plant Borzesti affiliated to the Petrochemical Platform, Bacau County, Romania is presented. The adopted solution uses as an inhibitor, a synthesis between amino alcohol and a thiazole, in the presence of water. This inhibitor has been tested in the laboratory on different steels used in energy pipes, in different areas of the thermal circuits in the boiler, as pure steel or with different alloys. The methods used to reduce the effects of corrosion are briefly presented. Four classes of organic substances with properties of corrosion inhibitors in the organic acid environment were analyzed. The experimental results obtained, associated with a comparative analysis of corrosion rates, for different concentrations of inhibitors for a time interval of 4 hours are mentioned. In the second stage, the inhibitor behavior was analyzed for 6h and 8h. Corrosion rates are estimated by measuring the weight loss of the tested probes. Finally, the most suitable types of inhibitors, adapted at different metal compositions are presented, with a result in the cleaning of more than 98% of the surface of the boilers.
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Kiselov, Georgij, Vladimir Jemeljanov, and Janis Ievinsh. "Assessment of Improving the Efficiency of Fire Extinguishing by Using Surface Active Agents." In Civil engineering '17 : 6th International Scientific Conference "Research for Environment and Civil Engineering Development 17”. Latvia University of Life Sciences and Technologies, 2018. http://dx.doi.org/10.22616/ce.2017.014.
Full textReports on the topic "Surface active agents – Analysis"
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López-Valverde, Nansi, Javier Aragoneses, Antonio López-Valverde, Cinthia Rodríguez, and Juan Manuel Aragoneses. Role in the osseointegration of titanium dental implants, of bioactive surfaces based on biomolecules: A systematic review and meta-analysis of in vivo studies. INPLASY - International Platform of Registered Systematic Review and Meta-analysis Protocols, June 2022. http://dx.doi.org/10.37766/inplasy2022.6.0076.
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Review question / Objective: Does the bioactive surface of titanium dental implants, based on biomolecules, influence osseointegration?. The aim of our study was to evaluate the role and efficacy of bioactive surfaces in osseointegration. Our review study limited the research interest to titanium dental implants coated with a biomolecule, i.e., an organic molecule produced by a living organism. Condition being studied: In recent years, much attention has been paid to topographical modifications of dental implant surfaces, as well as to their coating with biologically active substances.a bioactive surface is one capable of achieving faster and higher quality osseointegration, shortening waiting times and solving situations of poor bone quality. Molecules that can be applied for bioactive purposes include bioceramics, ions and biomolecules. Collagen and bone morphogenetic protein have been suggested as bone stimulating agents. Biofunctionalization of the implant surface with a biomimetic active peptide has also been shown to result in a significant increase in bone-to-implant ratios and an increase in peri-implant bone density.
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Chung, Myung, Li Dong, Rong Fu, Lance Liotta, Aarthi Narayanan, Emanuel Petricoin, Mark Ross, et al. Rapid Detection of Biological and Chemical Threat Agents Using Physical Chemistry, Active Detection, and Computational Analysis. Office of Scientific and Technical Information (OSTI), January 2007. http://dx.doi.org/10.2172/1049503.
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McClure, Michael A., Yitzhak Spiegel, David M. Bird, R. Salomon, and R. H. C. Curtis. Functional Analysis of Root-Knot Nematode Surface Coat Proteins to Develop Rational Targets for Plantibodies. United States Department of Agriculture, October 2001. http://dx.doi.org/10.32747/2001.7575284.bard.
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The goal of this research was to provide a better understanding of the interface between root-knot nematodes, Meloidogyne spp., and their host in order to develop rational targets for plantibodies and other novel methods of nematode control directed against the nematode surface coat (SC). Specific objectives were: 1. To produce additional monoclonal SC antibodies for use in Objectives 2, 3, and 4 and as candidates for development of plantibodies. 2. To determine the production and distribution of SC proteins during the infection process. 3. To use biochemical and immunological methods to perturbate the root-knot nematode SC in order to identify SC components that will serve as targets for rationally designed plantibodies. 4. To develop SC-mutant nematodes as additional tools for defining the role of the SC during infection. The external cuticular layer of nematodes is the epicuticle. In many nematodes, it is covered by a fuzzy material termed "surface coat" (SC). Since the SC is the outermost layer, it may playa role in the interaction between the nematode and its surroundings during all life stages in soil and during pathogenesis. The SC is composed mainly of proteins, carbohydrates (which can be part of glycoproteins), and lipids. SC proteins and glycoproteins have been labeled and extracted from preparasitic second-stage juveniles and adult females of Meloidogyne and specific antibodies have been raised against surface antigens. Antibodies can be used to gain more information about surface function and to isolate genes encoding for surface antigens. Characterization of surface antigens and their roles in different life-stages may be an important step towards the development of alternative control. Nevertheless, the role of the plant- parasitic nematode's surface in plant-nematode interaction is still not understood. Carbohydrates or carbohydrate-recognition domains (CROs) on the nematode surface may interact with CROs or carbohydrate molecules, on root surfaces or exudates, or be active after the nematode has penetrated into the root. Surface antigens undoubtedly play an important role in interactions with microorganisms that adhere to the nematodes. Polyclonal (PC) and monoclonal (MC) antibodies raised against Meloidogyne javanica, M. incognita and other plant-parasitic nematodes, were used to characterize the surface coat and secreted-excreted products of M. javanica and M. incognita. Some of the MC and PC antibodies raised against M. incognita showed cross-reactivity with the surface coat of M. javanica. Further characterization, in planta, of the epitopes recognized by the antibodies, showed that they were present in the parasitic juvenile stages and that the surface coat is shed during root penetration by the nematode and its migration between root cells. At the molecular level, we have followed two lines of experimentation. The first has been to identify genes encoding surface coat (SC) molecules, and we have isolated and characterized a small family of mucin genes from M. incognita. Our second approach has been to study host genes that respond to the nematode, and in particular, to the SC. Our previous work has identified a large suite of genes expressed in Lycopersicon esculentum giant cells, including the partial cDNA clone DB#131, which encodes a serine/threonine protein kinase. Isolation and predicted translation of the mature cDNA revealed a frame shift mutation in the translated region of nematode sensitive plants. By using primers homologous to conserved region of DB#131 we have identified the orthologues from three (nematode-resistant) Lycopersicon peruvianum strains and found that these plants lacked the mutation.
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Cytryn, Eddie, Mark R. Liles, and Omer Frenkel. Mining multidrug-resistant desert soil bacteria for biocontrol activity and biologically-active compounds. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7598174.bard.
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Control of agro-associated pathogens is becoming increasingly difficult due to increased resistance and mounting restrictions on chemical pesticides and antibiotics. Likewise, in veterinary and human environments, there is increasing resistance of pathogens to currently available antibiotics requiring discovery of novel antibiotic compounds. These drawbacks necessitate discovery and application of microorganisms that can be used as biocontrol agents (BCAs) and the isolation of novel biologically-active compounds. This highly-synergistic one year project implemented an innovative pipeline aimed at detecting BCAs and associated biologically-active compounds, which included: (A) isolation of multidrug-resistant desert soil bacteria and root-associated bacteria from medicinal plants; (B) invitro screening of bacterial isolates against known plant, animal and human pathogens; (C) nextgeneration sequencing of isolates that displayed antagonistic activity against at least one of the model pathogens and (D) in-planta screening of promising BCAs in a model bean-Sclerotiumrolfsii system. The BCA genome data were examined for presence of: i) secondary metabolite encoding genes potentially linked to the anti-pathogenic activity of the isolates; and ii) rhizosphere competence-associated genes, associated with the capacity of microorganisms to successfully inhabit plant roots, and a prerequisite for the success of a soil amended BCA. Altogether, 56 phylogenetically-diverse isolates with bioactivity against bacterial, oomycete and fungal plant pathogens were identified. These strains were sent to Auburn University where bioassays against a panel of animal and human pathogens (including multi-drug resistant pathogenic strains such as A. baumannii 3806) were conducted. Nineteen isolates that showed substantial antagonistic activity against at least one of the screened pathogens were sequenced, assembled and subjected to bioinformatics analyses aimed at identifying secondary metabolite-encoding and rhizosphere competence-associated genes. The genome size of the bacteria ranged from 3.77 to 9.85 Mbp. All of the genomes were characterized by a plethora of secondary metabolite encoding genes including non-ribosomal peptide synthase, polyketidesynthases, lantipeptides, bacteriocins, terpenes and siderophores. While some of these genes were highly similar to documented genes, many were unique and therefore may encode for novel antagonistic compounds. Comparative genomic analysis of root-associated isolates with similar strains not isolated from root environments revealed genes encoding for several rhizospherecompetence- associated traits including urea utilization, chitin degradation, plant cell polymerdegradation, biofilm formation, mechanisms for iron, phosphorus and sulfur acquisition and antibiotic resistance. Our labs are currently writing a continuation of this feasibility study that proposes a unique pipeline for the detection of BCAs and biopesticides that can be used against phytopathogens. It will combine i) metabolomic screening of strains from our collection that contain unique secondary metabolite-encoding genes, in order to isolate novel antimicrobial compounds; ii) model plant-based experiments to assess the antagonistic capacities of selected BCAs toward selected phytopathogens; and iii) an innovative next-generation-sequencing based method to monitor the relative abundance and distribution of selected BCAs in field experiments in order to assess their persistence in natural agro-environments. We believe that this integrated approach will enable development of novel strains and compounds that can be used in large-scale operations.
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Russell, H. A. J., and S. K. Frey. Canada One Water: integrated groundwater-surface-water-climate modelling for climate change adaptation. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/329092.
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Canada 1 Water is a 3-year governmental multi-department-private-sector-academic collaboration to model the groundwater-surface-water of Canada coupled with historic climate and climate scenario input. To address this challenge continental Canada has been allocated to one of 6 large watershed basins of approximately two million km2. The model domains are based on natural watershed boundaries and include approximately 1 million km2 of the United States. In year one (2020-2021) data assembly and validation of some 20 datasets (layers) is the focus of work along with conceptual model development. To support analysis of the entire water balance the modelling framework consists of three distinct components and modelling software. Land Surface modelling with the Community Land Model will support information needed for both the regional climate modelling using the Weather Research & Forecasting model (WRF), and input to HydroGeoSphere for groundwater-surface-water modelling. The inclusion of the transboundary watersheds will provide a first time assessment of water resources in this critical international domain. Modelling is also being integrated with Remote Sensing datasets, notably the Gravity Recovery and Climate Experiment (GRACE). GRACE supports regional scale watershed analysis of total water flux. GRACE along with terrestrial time-series data will serve provide validation datasets for model results to ensure that the final project outputs are representative and reliable. The project has an active engagement and collaborative effort underway to try and maximize the long-term benefit of the framework. Much of the supporting model datasets will be published under open access licence to support broad usage and integration.
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Droby, Samir, Joseph W. Eckert, Shulamit Manulis, and Rajesh K. Mehra. Ecology, Population Dynamics and Genetic Diversity of Epiphytic Yeast Antagonists of Postharvest Diseases of Fruits. United States Department of Agriculture, October 1994. http://dx.doi.org/10.32747/1994.7568777.bard.
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One of the emerging technologies is the use of microbial agents for the control of postharvest diseases of fruits and vegetables. A number of antagonistic microorganisms have been discovered which have the potential to effectively control postharvest diseases. Some of this technology has been patented and commercial products such as AspireTM (Ecogen Corporatin, Langhorne, PA, USA), Biosave 10TM and Biosave 11TM (Ecoscience Inc., Worchester, MA, USA) have been registered for commercial use. The principal investigator of this project was involved in developing the yeast-based biofungicide-AspireTM and testing its efficacy under commercial conditions. This research project was initiated to fill the gap between the knowledge available on development and commercial implementation of yeast biocontrol agents and basic understanding of various aspects related to introducing yeast antagonists to fruit surfaces, along with verification of population genetics. The main objectives of this study were: Study ecology, population dynamics and genetic diversity of the yeast antagonists Candida guilliermondii, C. oleophila, and Debaryomyces hansenii, and study the effect of preharvest application of the yeast antagonist C. oleophila naturally occurring epiphytic microbial population and on the development of postharvest diseases of citrus fruit during storage. Our findings, which were detailed in several publications, have shown that an epiphytic yeast population of grapefruit able to grow under high osmotic conditions and a wide range of temperatures was isolated and characterized for its biocontrol activity against green mold decay caused by Penicillium digitatum. Techniques based on random amplified polymorphic DNA (RAPD) and arbitrary primed polymerase chain reaction (ap-PCR), as well as homologies between sequences of the rDNA internal transcribed spacers (ITS) and 5.8S gene, were used to characterize the composition of the yeast population and to determine the genetic relationship among predominant yeast species. Epiphytic yeasts exhibiting the highest biocontrol activity against P. digitatum on grapefruit were identified as Candida guilliermondii, C. oleophila, C. sake, and Debaryomyces hansenii, while C. guilliermondii was the most predominant species. RAPD and ap-PCR analysis of the osmotolerant yeast population showed two different, major groups. The sequences of the ITS regions and the 5.8S gene of the yeast isolates, previously identified as belonging to different species, were found to be identical. Following the need to develop a genetically marked strain of the yeast C. oleophila, to be used in population dynamics studies, a transformation system for the yeast was developed. Histidine auxotrophy of C. oloephila produced using ethyl methanesulfonate were transformed with plasmids containing HIS3, HIS4 and HIS5 genes from Saccharomyces cerevisiae. In one mutant histidin auxotrophy was complemented by the HIS5 gene of S. cerevisiae is functionally homologous to the HIS5 gene in V. oleophila. Southern blot analysis showed that the plasmid containing the S. cerevisiae HIS5 gene was integrated at a different location every C. oleophila HIS+ transformant. There were no detectable physiological differences between C. oleophila strain I-182 and the transformants. The biological control ability of C. oleophila was not affected by the transformation. A genetically marked (with b-glucuronidase gene) transformant of C. oleophila colonized wounds on orange fruits and its population increased under field conditions. Effect of preharvest application of the yeast C. oleophila on population dynamics of epiphytic microbial population on wounded and unwounded grapefruit surface in the orchard and after harvest was also studied. In addition, the effect of preharvest application of the yeast C. oleophila on the development of postharvest decay was evaluated. Population studies conducted in the orchard showed that in control, non-treated fruit, colonization of wounded and unwounded grapefruit surface by naturally occurring filamentous fungi did not vary throughout the incubation period on the tree. On the other hand, colonization of intact and wounded fruit surface by naturally occurring yeasts was different. Yeasts colonized wounded surface rapidly and increased in numbers to about two orders of magnitude as compared to unwounded surface. On fruit treated with the yeast and kept on the tree, a different picture of fungal and yeast population had emerged. The detected fungal population on the yeast-treated intact surface was dramatically reduced and in treated wounds no fungi was detected. Yeast population on intact surface was relatively high immediately after the application of AspireTM and decreased to than 70% of that detected initially. In wounds, yeast population increased from 2.5 x 104 to about 4x106 after 72 hours of incubation at 20oC. Results of tests conducted to evaluate the effect of preharvest application of AspireTM on the development of postharvest decay indicated the validity of the approach.
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Droby, Samir, Michael Wisniewski, Ron Porat, and Dumitru Macarisin. Role of Reactive Oxygen Species (ROS) in Tritrophic Interactions in Postharvest Biocontrol Systems. United States Department of Agriculture, December 2012. http://dx.doi.org/10.32747/2012.7594390.bard.
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To elucidate the role of ROS in the tri-trophic interactions in postharvest biocontrol systems a detailed molecular and biochemical investigation was undertaken. The application of the yeast biocontrol agent Metschnikowia fructicola, microarray analysis was performed on grapefruit surface wounds using an Affymetrix Citrus GeneChip. the data indicated that 1007 putative unigenes showed significant expression changes following wounding and yeast application relative to wounded controls. The expression of the genes encoding Respiratory burst oxidase (Rbo), mitogen-activated protein kinase (MAPK) and mitogen-activated protein kinase kinase (MAPKK), G-proteins, chitinase (CHI), phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS) and 4-coumarate-CoA ligase (4CL). In contrast, three genes, peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT), were down-regulated in grapefruit peel tissue treated with yeast cells. The yeast antagonists, Metschnikowia fructicola (strain 277) and Candida oleophila (strain 182) generate relatively high levels of super oxide anion (O2−) following its interaction with wounded fruit surface. Using laser scanning confocal microscopy we observed that the application of M. fructicola and C. oleophila into citrus and apple fruit wounds correlated with an increase in H2O2 accumulation in host tissue. The present data, together with our earlier discovery of the importance of H₂O₂ production in the defense response of citrus flavedo to postharvest pathogens, indicate that the yeast-induced oxidative response in fruit exocarp may be associated with the ability of specific yeast species to serve as biocontrol agents for the management of postharvest diseases. Effect of ROS on yeast cells was also studied. Pretreatment of the yeast, Candida oleophila, with 5 mM H₂O₂ for 30 min (sublethal) increased yeast tolerance to subsequent lethal levels of oxidative stress (50 mM H₂O₂), high temperature (40 °C), and low pH (pH 4). Suppression subtractive hybridization analysis was used to identify genes expressed in yeast in response to sublethal oxidative stress. Transcript levels were confirmed using semi quantitative reverse transcription-PCR. Seven antioxidant genes were up regulated. Pretreatment of the yeast antagonist Candida oleophila with glycine betaine (GB) increases oxidative stress tolerance in the microenvironment of apple wounds. ROS production is greater when yeast antagonists used as biocontrol agents are applied in the wounds. Compared to untreated control yeast cells, GB-treated cells recovered from the oxidative stress environment of apple wounds exhibited less accumulation of ROS and lower levels of oxidative damage to cellular proteins and lipids. Additionally, GB-treated yeast exhibited greater biocontrol activity against Penicillium expansum and Botrytis cinerea, and faster growth in wounds of apple fruits compared to untreated yeast. The expression of major antioxidant genes, including peroxisomal catalase, peroxiredoxin TSA1, and glutathione peroxidase was elevated in the yeast by GB treatment. A mild heat shock (HS) pretreatment (30 min at 40 1C) improved the tolerance of M. fructicola to subsequent high temperature (45 1C, 20–30 min) and oxidative stress (0.4 mol-¹) hydrogen peroxide, 20–60 min). HS-treated yeast cells showed less accumulation of reactive oxygen species (ROS) than non-treated cells in response to both stresses. Additionally, HS-treated yeast exhibited significantly greater (P≥0.0001) biocontrol activity against Penicillium expansum and a significantly faster (Po0.0001) growth rate in wounds of apple fruits stored at 25 1C compared with the performance of untreated yeast cells. Transcription of a trehalose-6-phosphate synthase gene (TPS1) was up regulated in response to HS and trehalose content also increased.
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Altstein, Miriam, and Ronald J. Nachman. Rational Design of Insect Control Agent Prototypes Based on Pyrokinin/PBAN Neuropeptide Antagonists. United States Department of Agriculture, August 2013. http://dx.doi.org/10.32747/2013.7593398.bard.
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The general objective of this study was to develop rationally designed mimetic antagonists (and agonists) of the PK/PBAN Np class with enhanced bio-stability and bioavailability as prototypes for effective and environmentally friendly pest insect management agents. The PK/PBAN family is a multifunctional group of Nps that mediates key functions in insects (sex pheromone biosynthesis, cuticular melanization, myotropic activity, diapause and pupal development) and is, therefore, of high scientific and applied interest. The objectives of the current study were: (i) to identify an antagonist biophores (ii) to develop an arsenal of amphiphilic topically active PK/PBAN antagonists with an array of different time-release profiles based on the previously developed prototype analog; (iii) to develop rationally designed non-peptide SMLs based on the antagonist biophore determined in (i) and evaluate them in cloned receptor microplate binding assays and by pheromonotropic, melanotropic and pupariation in vivo assays. (iv) to clone PK/PBAN receptors (PK/PBAN-Rs) for further understanding of receptor-ligand interactions; (v) to develop microplate binding assays for screening the above SMLs. In the course of the granting period A series of amphiphilic PK/PBAN analogs based on a linear lead antagonist from the previous BARD grant was synthesized that incorporated a diverse array of hydrophobic groups (HR-Suc-A[dF]PRLa). Others were synthesized via the attachment of polyethylene glycol (PEG) polymers. A hydrophobic, biostablePK/PBAN/DH analog DH-2Abf-K prevented the onset of the protective state of diapause in H. zea pupae [EC50=7 pmol/larva] following injection into the preceding larval stage. It effectively induces the crop pest to commit a form of ‘ecological suicide’. Evaluation of a set of amphiphilic PK analogs with a diverse array of hydrophobic groups of the formula HR-Suc-FTPRLa led to the identification of analog T-63 (HR=Decyl) that increased the extent of diapause termination by a factor of 70% when applied topically to newly emerged pupae. Another biostablePK analog PK-Oic-1 featured anti-feedant and aphicidal properties that matched the potency of some commercial aphicides. Native PK showed no significant activity. The aphicidal effects were blocked by a new PEGylated PK antagonist analog PK-dF-PEG4, suggesting that the activity is mediated by a PK/PBAN receptor and therefore indicative of a novel and selective mode-of-action. Using a novel transPro mimetic motif (dihydroimidazole; ‘Jones’) developed in previous BARD-sponsored work, the first antagonist for the diapause hormone (DH), DH-Jo, was developed and shown to block over 50% of H. zea pupal diapause termination activity of native DH. This novel antagonist development strategy may be applicable to other invertebrate and vertebrate hormones that feature a transPro in the active core. The research identifies a critical component of the antagonist biophore for this PK/PBAN receptor subtype, i.e. a trans-oriented Pro. Additional work led to the molecular cloning and functional characterization of the DH receptor from H. zea, allowing for the discovery of three other DH antagonist analogs: Drosophila ETH, a β-AA analog, and a dF analog. The receptor experiments identified an agonist (DH-2Abf-dA) with a maximal response greater than native DH. ‘Deconvolution’ of a rationally-designed nonpeptide heterocyclic combinatorial library with a cyclic bis-guanidino (BG) scaffold led to discovery of several members that elicited activity in a pupariation acceleration assay, and one that also showed activity in an H. zea diapause termination assay, eliciting a maximal response of 90%. Molecular cloning and functional characterization of a CAP2b antidiuretic receptor from the kissing bug (R. prolixus) as well as the first CAP2b and PK receptors from a tick was also achieved. Notably, the PK/PBAN-like receptor from the cattle fever tick is unique among known PK/PBAN and CAP2b receptors in that it can interact with both ligand types, providing further evidence for an evolutionary relationship between these two NP families. In the course of the granting period we also managed to clone the PK/PBAN-R of H. peltigera, to express it and the S. littoralis-R Sf-9 cells and to evaluate their interaction with a variety of PK/PBAN ligands. In addition, three functional microplate assays in a HTS format have been developed: a cell-membrane competitive ligand binding assay; a Ca flux assay and a whole cell cAMP ELISA. The Ca flux assay has been used for receptor characterization due to its extremely high sensitivity. Computer homology studies were carried out to predict both receptor’s SAR and based on this analysis 8 mutants have been generated. The bioavailability of small linear antagonistic peptides has been evaluated and was found to be highly effective as sex pheromone biosynthesis inhibitors. The activity of 11 new amphiphilic analogs has also been evaluated. Unfortunately, due to a problem with the Heliothis moth colony we were unable to select those with pheromonotropic antagonistic activity and further check their bioavailability. Six peptides exhibited some melanotropic antagonistic activity but due to the low inhibitory effect the peptides were not further tested for bioavailability in S. littoralis larvae. Despite the fact that no new antagonistic peptides were discovered in the course of this granting period the results contribute to a better understanding of the interaction of the PK/PBAN family of Nps with their receptors, provided several HT assays for screening of libraries of various origin for presence of PK/PBAN-Ragonists and antagonists and provided important practical information for the further design of new, peptide-based insecticide prototypes aimed at the disruption of key neuroendocrine physiological functions in pest insects.
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Gordon, Dalia, Ke Dong, and Michael Gurevitz. Unexpected Specificity of a Sea Anemone Small Toxin for Insect Na-channels and its Synergic Effects with Various Insecticidal Ligands: A New Model to Mimic. United States Department of Agriculture, November 2010. http://dx.doi.org/10.32747/2010.7697114.bard.
Full textAbstract:
Motivated by the high risks to the environment and human health imposed by the current overuse of chemical insecticides we offer an alternative approach for the design of highly active insect-selective compounds that will be based on the ability of natural toxins to differentiate between insect and mammalian targets. We wish to unravel the interacting surfaces of insect selective toxins with their receptor sites on voltage-gated sodium channels. In this proposal we put forward two recent observations that may expedite the development of a new generation of insect killers that mimic the highly selective insecticidal toxins: (i) A small (27aa) highly insecticidal sea anemone toxin, Av3, whose toxicity to mammals is negligible; (ii) The prominent positive cooperativity between distinct channel ligands, such as the strong enhancement of pyrethroids effects by anti-insect selective scorpion depressant toxins. We possess a repertoire of insecticidal toxins and sodium channel subtypes all available in recombinant form for mutagenesis followed by analysis of various pharmacological, electrophysiological, and structural methods. Our recent success to express Av3 provides for the first time a selective toxin for receptor site-3 on insect sodium channels. In parallel, our recent success to determine the structures and bioactive surfaces of insecticidal site-3 and site-4 toxins establishes a suitable system for elucidation of toxin-receptor interacting faces. This is corroborated by our recent identification of channel residues involved with these two receptor sites. Our specific aims in this proposal are to (i) Determine the bioactive surface of Av3 toward insect Na-channels; (ii) Identify channel residues involved in binding or activity of the insecticidal toxins Av3 and LqhaIT, which differ substantially in their potency on mammals; (iii) Illuminate channel residues involved in recognition by the anti-insect depressant toxins; (iv) Determine the face of interaction of both site-3 (Av3) and site-4 (LqhIT2) toxins with insect sodium channels using thermodynamic mutant cycle analysis; and, (v) Examine whether Av3, LqhIT2, pyrethroids, and indoxacarb (belongs to a new generation of insecticides), enhance allosterically the action of one another on the fruit fly and cockroach paraNa-channels and on their kdr and super-kdr mutants. This research establishes the grounds for rational design of novel anti-insect peptidomimetics with minimal impact on human health, and offers a new approach in insect pest control, whereby a combination of allosterically interacting compounds increases insecticidal action and reduces risks of resistance buildup.
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Glazer, Itamar, Alice Churchill, Galina Gindin, and Michael Samish. Genomic and Organismal Studies to Elucidate the Mechanisms of Infectivity of Entomopathogenic Fungi to Ticks. United States Department of Agriculture, January 2013. http://dx.doi.org/10.32747/2013.7593382.bard.
Full textAbstract:
The overall goal of this research was to elucidate the factors affecting early development of Metarhizium spp. (previously named M. anisopliae) on ticks or tick cuticle extracts and the molecular basis of these early infection processes. The original objectives were: 1. Characterize the pre-penetration events (adhesion, germination and appressorium formation) of spores of M. anisopliae strains with high or low virulence during tick infection. 2. Create GFP-expressing strains of M. anisopliae tick pathogens having high and low virulence to compare their progress of infection by microscopy. 3. Use microarray analyses, primarily with existing M. anisopliae EST sequences in GenBank, to identify and characterize fungal genes whose expression is regulated in response to host cuticle extracts. Objective 3 was later modified (as approved by BARD) to use RNAseq to characterize the early stages of fungal gene expression during infection of intact host cuticles. This new method provides a massively larger and more informative dataset and allows us to take advantage of a) recently published genomes of Metarhizium robertsii and M. acridum for RNAseq data analysis, and b) newly developed and highly efficient cDNA sequencing technologies that are relatively low cost and, therefore, allow deep sequencing of multiple transcriptome samples. We examined pre-penetration and penetration events that differentiate high and low virulence strains of Metarhizium spp., focusing on spore adhesion, germination, appressorium formation, and penetration of tick integuments. Initiation of fungal infection was compared on susceptible and resistant tick species at different tick developmental stages. In vitro studies comparing the effects of protein and fatty acid profiles from tick cuticle extracts demonstrated that resistant tick cuticles contain higher concentrations of specific lipids that inhibit fungal development than do susceptible tick cuticles, suggesting one mechanism of Ixodidae resistance to fungal entomopathogens (Objective 1). We used molecular markers to determine that the three M. anisopliae strains from Israel that we studied actually were three distinct species. M. brunneum is highly virulent against the tick Rhipicephalus annulatus, M. pingshaense and M. robertsii are intermediate in virulence, and M. majus is of low virulence. We transformed all four Metarhizium species to express GFP and used them in pathogenicity assays against diverse tick species. Key findings were that a) resistant ticks inhibit Metarhizium infection prior to hemocoel invasion by reducing fungal viability on the cuticle surface (Objective 2), as was supported by the in vitro studies of Objective 1, and b) Metarhizium kills susceptible ticks after cuticle penetration but prior to hemocoel colonization. Transcriptome studies of the most virulent species, M. brunneum, are in progress and include analyses of ungerminated conidia and conidia germination and development on a low nutrient medium or on susceptible R. annulatus exoskeleton (Objective 3). We anticipate these studies will contribute to identifying fungal genetic factors that increase virulence and speed of kill and may help reveal tick chemistries that could be included in biocontrol formulations to increase efficacy. Methodologies developed to screen tick cuticle extracts for ability to support conidia germination and development may help in the selection of wild fungi with increased virulence against resistant ticks. The overall knowledge gained should contribute not only to the improvement of tick control but also to the control of other blood-sucking arthropods and related plant pests. Use of bio-based agents for controlling arthropods will contribute to a healthier, more sustainable environment and serve a growing number of organic food farmers.