Global ETD Search

51	Application d’une stratégie de lutte intégrée contre le parasite Varroa destructor dans les colonies d’abeilles mellifères du Québec Giovenazzo, Pierre 04 1900 (has links) Le parasite Varroa destructor provoque depuis plus de 30 ans la perte de nombreuses colonies à travers le monde. L’utilisation d’acaricides de synthèse s’est avérée inefficace au Canada et ailleurs dans le monde à la suite de la sélection de varroas résistants. Dans ce contexte, il est devenu impératif de trouver de nouveaux moyens pour contrôler cette peste apicole. Ce travail original de recherche a pour but de déterminer les paramètres fondamentaux d’une lutte intégrée contre la varroase fondée sur l’utilisation périodique de différents pesticides organiques (l’acide oxalique, l’acide formique et le thymol) associée à des seuils d’interventions. Les seuils d’intervention ont été déterminés à l’aide de régressions linéaires entre les taux de parasitisme par V. destructor et la formance zootechnique des colonies d’abeilles mellifères (production de miel et force des colonies). Un total de 154 colonies d’abeilles du Centre de recherche en sciences animales de Deschambault (CRSAD) ont été suivies de septembre 2005 à septembre 2006. Les seuils calculés et proposés à la suite de cette recherche sont de 2 varroas par jour (chute naturelle) au début mai, 10 varroas par jour à la fin juillet et de 9 varroas par jour au début septembre. L’efficacité des traitements organiques avec l’acide oxalique (AO), l’acide formique (AF) et le thymol a été vérifiée en mai (avant la première miellée) en juillet (entre deux miellées), en septembre (après la miellée et pendant le nourrissage des colonies) et en novembre (avant l’hivernage). L’acide oxalique a été appliqué en utilisant la méthode d’égouttement (4% d’AO p/v dans un sirop de sucrose 1 :1 p/v). L’acide formique a été appliquée sous forme de MiteAwayII™ (tampon commercial imbibé d’AF 65% v/v placé sur le dessus des cadres à couvain), Mitewipe (tampons Dri-Loc™ 10/15cm imbibés de 35 mL d’AF 65% v/v placés sur le dessus des cadres à couvain) ou Flash (AF 65% coulé directement sur le plateau inférieur d’une colonie, 2 mL par cadre avec abeilles). Le thymol a été appliqué sous forme d’Apiguard™ (gélose contenant 25% de thymol p/v placée sur le dessus des cadres à couvain). Les essais d’efficacité ont été réalisés de 2006 à 2008 sur un total de 170 colonies (98 appartenant au CRSAD et 72 appartenant au privé). Les résultats montrent que les traitements de printemps testés ont une faible efficacité pour le contrôle des varroas qui sont en pleine croissance durant cette période. Un traitement avec l’AF à la mi-été permet de réduire les taux de parasites sous le seuil en septembre mais il y a risque de contaminer la récolte de miel avec des résidus d’AF. Les traitements en septembre avec le MiteAwayII™ suivis par un traitement à l’acide oxalique en novembre (5 mL par égouttement entre chaque cadre avec abeilles, 4% d’AO p/v dans un sirop de sucrose 1 :1 p/v) sont les plus efficaces : ils réduisent les niveaux de varroase sous le seuil de 2 varroas par jour au printemps. Nos résultats montrent également que les traitements réalisés tôt en septembre sont plus efficaces et produisent des colonies plus fortes au printemps comparativement à un traitement réalisé un mois plus tard en octobre. En conclusion, ce travail de recherche démontre qu’il est possible de contenir le développement de la varroase dans les ruchers au Québec en utilisant une méthode de lutte intégrée basée sur une combinaison d’applications d’acaricides organiques associée à des seuils d’intervention. / For nearly 30 years, Varroa destructor has been responsible for the loss of many honey bee colonies around the world. The continued use of synthetic acaricides has resulted in their reduced efficacy against this pest in Canada and in other countries because of the selection of resistant mite populations. With this situation still present, it has become of utmost importance to develop efficient methods to control this apicultural pest. The major goal of this original work is to determine the fundamental parameters underlying the use of an integrated pest management (IPM) strategy against the varroa mite. The IPM strategy developed in this research is based on the periodic use of organic pesticides (oxalic acid, formic acid and thymol) and treatment threshold. Treatment thresholds were determined from linear regressions between the varroa mite levels and the zootechnical performances (honey production and colony strength) of honey bee colonies. A total of 154 honey bee colonies from the livestock of the “Centre de recherche en sciences animales de Deschambault” (CRSAD) were monitored from September 2005 to September 2006. Based on our findings, we propose economic treatment thresholds for three periods in the year: early May, late July and early September that are respectively 2, 10 and 9 varroa mites per day. Efficacy of the various organic treatments: formic acid (FA), oxalic acid (OA) and thymol was evaluated in May (before the first honey flow), in July between two honey flows, in September (after the honey flow and before the fall feeding of colonies) and in November (before wintering). OA was applied using the trickling method (4% OA w/v in a sucrose syrup 1:1 w/v). FA was applied using MiteAwayII™ (pads imbedded with FA 65% v/v placed on top of brood frames), Mitewipe (Dri-Loc™ pads 10/15cm imbedded with 35 mL FA 65% v/v placed on top of brood frames), Flash (FA 65% poured directly on the bottom board of colonies, 2 mL per frame with bees). Thymol was applied using Apiguard™ (gel with 25% de thymol w/v placed on top of the brood frames). Efficacy trials were realised from 2006 to 2008 on a total of 170 colonies (98 from the CRSAD and 72 owned by a commercial beekeeper). Results show that treatments applied in spring give low efficacy on reducing varroa mite populations that are in full growth at this time because of large amounts of brood available for mite reproduction. Application of a FA treatment in mid-summer offers the opportunity to reduce mite populations at the 11 mites per day September threshold but FA summer application is accompanied by a risk of incorporating residues in the harvested honey. Application of MiteAwayII™ in September followed by an oxalic acid treatment in November (trickling method 4% OA w/v in a sucrose syrup 1 :1 w/v, 5 mL between frames with bees) gave the best efficacy results: varroa mite levels are reduced below the 2 mites per day spring threshold. Our results also show that an early September management strategy of colonies for winter preparation (varroa treatment and fall feeding) gives greater varroa control, higher colony winter survival and stronger colonies in spring when compared to a later treatment in October. In conclusion, this work shows that varroa mite control in honey bee colonies in Québec is possible by using an integrated pest management strategy based on the application of a combination of organic acaricides in association with treatment thresholds. Varroa destructor Apis mellifera Seuil d’intervention Pesticide organique Acide formique Acide oxalique Thymol Treatment thresholds Organic pesticide Formic acid Oxalic acid
52	Vliv změny vstupních parametrů na výrobu nanoporézní keramiky / Impact of input parameters variation on fabrication of nanoporous alumina Hriczo, Filip January 2010 (has links) This thesis examines and tests acids and conditions, which make the production of nanoporous ceramic at the thin aluminium layer the most effective and provide the highest quality. This paper describes the production of nanoporous structures with pore size 15-400 nm, depending on the electrolyte. Creating a regular hexagonal structure by electrochemical oxidation is dependent on many parameters that affect the regularity of structure and parameters of the ceramics produced. They were investigated primarily by changes in temperature and input voltage. All results were examined by SEM analysis.
53	Estudio espectroelectroquímico de los equilibrios ácido-base de especies adsorbidas sobre electrodos metálicos con superficies monocristalinas bien definidas Berná Galiano, Antonio 22 December 2014 (has links) No description available. Pt single crystal electrodes Hydroxyl adsorption Anion specific adsorption Acetate adsorption Gold thin film electrodes Gold single crystal electrodes In situ infrared spectroscopy IRRAS ATR-SEIRAS CO2 adsorption Pd/Pt(111) electrodes Oxalic acid adsorption Malonic acid adsorption Succinic acid adsorption Química Física
54	An Analysis of Microstructure and Corrosion Resistance in Underwater Friction Stir Welded 304L Stainless Steel Clark, Tad Dee 30 June 2005 (has links) (PDF) An effective procedure and parameter window was developed for underwater friction stir welding (UWFSW) 304L stainless steel with a PCBN tool. UWFSW produced statistically significant: increases in yield strengths, decreases in percent elongation. The ultimate tensile strength was found to be significantly higher at certain parameters. Although sigma was identified in the UWFSWs, a significant reduction of sigma was found in UWFSWs compared to ambient FSWs. The degree of sensitization in UWFSWs was evaluated using double loop EPR testing and oxalic acid electro-etched metallography. Results were compared to base metal, ambient FSW, and arc welds. Upper and lower sensitization localization bands were identified in the UWFSWs. Although higher sensitization levels were present in UWFSWs compared to the arc weld, ambient FSW, and heat treated base metals, the UWFSWs were found less susceptible to corrosion than arc welds due to the subsurface location of the sensitization bands. A SCC analysis of UWFSWs relative to base metal and arc weldments was performed. U-bends were exposed to two 3.5% NaCl cyclic immersion experiments at 21 °C and 63 °C for 1000 hours each. A tertiary test was conducted in a 25% NaCl boiling solution. The UWFSW u-bends were no more susceptible to SCC than base metal in the cyclic immersion tests. In the boiling NaCl test, the SCC of the UWFSWs showed significant improvement over the SCC of arc welds. Arc u-bends cracked entirely within the weld bead and HAZ, while SCC in the UWFSWs showed no cracking localization. friction stir weld FSW underwater friction stir weld UWFSW stainless steel stir zone 304L austenite austenitic procedure process window welding parameters corrosion intergranular stress corrosion cracking SCC u-bend sensitization PCBN double loop EPR current ratio potentiostat electrochemical reactivation sampling area quantification tensile strength ductility elongation statistical significance microstructure optical microscopy oxidation surface finish base metal sigma Murakami oxalic acid electro-etch arc weld comparison cyclic immersion test boiling NaCl test subsurface location residual stress improvement superiority ASTM standard HAZ heat affected zone Mechanical Engineering
55	Electron Transfer and Other Reactions Using Atomic Metal Anions Butson, Jeffery M. 04 February 2014 (has links) The atomic metal anions Rb-, Cs-, Cu-, Ag- and Fe- have been generated in the gas phase and reacted with various neutral reactants in a triple quadrupole mass spectrometer. The metal anions were formed via electrospray ionization of the metal-oxalate solutions and form in gas phase between the capillary and the first quadrupole. Neutral gas phase reactants investigated include NO, NO2, SO2, C6F5OH, C6F5NH2, C6F6, E-octafluoro-butene and 1,2,3/1,2,4/1,3,5 trifluoro-benzene. When possible, CBS-4M methods were used to suggest the lowest energy products based on relative energy. Observed reactions of atomic metal anions with the aforementioned neutral species include electron transfer and dissociative electron transfer to the neutral gas phase reactants. In addition, hydrogen abstraction and fluorine abstraction forming a neutral metal hydride or fluoride as well as the formation of multiply substituted metal-oxide/fluoride anions was also observed. Metal-complex anions observed from the gas phase reactions include CuF-,CuF2-,CuO-,CuO2-, FeO-, FeO2-, FeO3-, FeF-, FeF2-, FeF3-, CsF- and CsF2-. Metal Anion Metal Anion Atomic Atomic Metal Anion Atomic Metals Atomic Metal Anions Anions Metals Mass Spectrometer Triple Quadrupole Rb Cs Fe Cu Ag Cs- Rb- Fe- Cu- Ag- pentafluoroaniline pentafluorophenol nitrogen dioxide sulfur dioxide nitrogen oxide nitrogen monoxide oxygen oxalic oxalic acid gas phase electrospray ionization electrospray ionization electro-spray ionization electro-spray hexafluorobenzene 1,2,3-trifluorobenzene 1,2,4-trifluorobenzene 1,3,5-trifluorobenzene fluorine E-octafluoro-butene octafluoro-butene octafluoro butene CBS-4M abstraction hydrogen abstraction fluorine abstraction hydride fluoride metal hydride metal fluoride caesium fluoride rubidium fluoride iron fluride copper fluoride rubidium caesium iron copper silver iron anion copper anion rubidium anion caesium anion silver anion cesium cesium anion atomic caesium anion atomic cesium anion atomic rubidium anion atomic iron anion atomic copper anion atomic silver anion 1,2,3 trifluorobenzene 1,2,4 trifluorobenzene 1,3,5 trifluorobenzene copper fluoride anion iron fluoride anion copper difluoride copper difluoride anion iron difluoride iron difluoride anion iron trifluoride iron trifluoride anion cesium fluoride cesium fluoride anion caesium difluoride anion caesium difluoride cesium difluoride cesium difluoride anion caesium fluoride anion nitrogen monoxide anion sulfur dioxide anion nitrogen dioxide anion copper oxide copper oxide anion copper dioxide copper dioxide anion iron oxide iron oxide anion iron dioxide iron dioxide anion iron trioxide iron trioxide anion electron transfer
56	Electron Transfer and Other Reactions Using Atomic Metal Anions Butson, Jeffery M. January 2014 (has links) The atomic metal anions Rb-, Cs-, Cu-, Ag- and Fe- have been generated in the gas phase and reacted with various neutral reactants in a triple quadrupole mass spectrometer. The metal anions were formed via electrospray ionization of the metal-oxalate solutions and form in gas phase between the capillary and the first quadrupole. Neutral gas phase reactants investigated include NO, NO2, SO2, C6F5OH, C6F5NH2, C6F6, E-octafluoro-butene and 1,2,3/1,2,4/1,3,5 trifluoro-benzene. When possible, CBS-4M methods were used to suggest the lowest energy products based on relative energy. Observed reactions of atomic metal anions with the aforementioned neutral species include electron transfer and dissociative electron transfer to the neutral gas phase reactants. In addition, hydrogen abstraction and fluorine abstraction forming a neutral metal hydride or fluoride as well as the formation of multiply substituted metal-oxide/fluoride anions was also observed. Metal-complex anions observed from the gas phase reactions include CuF-,CuF2-,CuO-,CuO2-, FeO-, FeO2-, FeO3-, FeF-, FeF2-, FeF3-, CsF- and CsF2-. Metal Anion Metal Anion Atomic Atomic Metal Anion Atomic Metals Atomic Metal Anions Anions Metals Mass Spectrometer Triple Quadrupole Rb Cs Fe Cu Ag Cs- Rb- Fe- Cu- Ag- pentafluoroaniline pentafluorophenol nitrogen dioxide sulfur dioxide nitrogen oxide nitrogen monoxide oxygen oxalic oxalic acid gas phase electrospray ionization electrospray ionization electro-spray ionization electro-spray hexafluorobenzene 1,2,3-trifluorobenzene 1,2,4-trifluorobenzene 1,3,5-trifluorobenzene fluorine E-octafluoro-butene octafluoro-butene octafluoro butene CBS-4M abstraction hydrogen abstraction fluorine abstraction hydride fluoride metal hydride metal fluoride caesium fluoride rubidium fluoride iron fluride copper fluoride rubidium caesium iron copper silver iron anion copper anion rubidium anion caesium anion silver anion cesium cesium anion atomic caesium anion atomic cesium anion atomic rubidium anion atomic iron anion atomic copper anion atomic silver anion 1,2,3 trifluorobenzene 1,2,4 trifluorobenzene 1,3,5 trifluorobenzene copper fluoride anion iron fluoride anion copper difluoride copper difluoride anion iron difluoride iron difluoride anion iron trifluoride iron trifluoride anion cesium fluoride cesium fluoride anion caesium difluoride anion caesium difluoride cesium difluoride cesium difluoride anion caesium fluoride anion nitrogen monoxide anion sulfur dioxide anion nitrogen dioxide anion copper oxide copper oxide anion copper dioxide copper dioxide anion iron oxide iron oxide anion iron dioxide iron dioxide anion iron trioxide iron trioxide anion electron transfer

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