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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Evaluation of Contaminant Mixing in Rainwater Harvesting First Flush Diverters

Mechell, Justin K. 14 January 2010 (has links)
As the world population increases, the demand increases for quality drinking water. The harvesting of rainwater has the potential to assist in alleviating pressures on current water supplies and storm water drainage systems. Diversion of a portion of the collected water away from storage is a technique used to improve harvested rainwater water quality prior to storage. Six configurations of a downspout first flush diverter were constructed and tested in the laboratory. The configurations of diverters were evaluated for their affinity to allow diverted water in the diverter chamber to interact with the flow of water to storage. Experiments were conducted at flow rates ranging from 0.76 L/min to 113.56 L/min. This range of flow rates adequately represents a wide range of common storm intensity patterns across the United States to which downspout first flush diverters are subjected. The diverter chamber to downspout transition fittings tested on a 10.16 cm diameter diverter chamber, upward and downward oriented sanitary and straight tee, do not have a significant impact on the mean difference in initial and final total dissolved solids concentrations observed at multiple sample ports. No statistical difference was observed when comparing upward and downward oriented sanitary tees used as diverter chambers to downspout transition fittings on 10.16 and 15.24 cm diverter chambers. Utilizing a straight tee as a transition fitting with a floating ball, acting as a barrier between water collected in the diverter chamber of a downspout first flush diverter and the flow passing through the transition fitting, limited diverted water from interacting with the subsequent flow of harvested rainwater. There is not a significant difference between the use of a downspout first flush diverter with diverter chamber diameters of 10.16 and 15.24 cm utilizing upward and downward oriented sanitary tees as downspout to diverter chamber transition fittings. Tests at flow rates less than or equal to 12.11 L/min exhibited limited changes in total dissolved solids concentrations in the downspout first flush diverters with 15.24 cm diameter diverter chambers. Tests at flow rates less than or equal to 1.51 L/min exhibited limited changes in total dissolved solids concentrations in the downspout first flush diverters with 10.16 cm diameter diverter chambers. The diverter chamber drain flow rate and volume impacts the observed differences in initial and final TDS concentrations at all sample ports on the diverter chamber of a downspout first flush diverter regardless of flow rate. The diverter chamber drain flow rate impacts the flow rate of water entering the diverter chamber through the transition fitting.
2

Biocompatibility improvement conferred by the immobilization of a CD31 peptide on endovascular stents / Amélioration de la biocompatbilité apportée par l’immobilisaton d’un peptide du CD31 sur des stents endovasculaires

Rasser, Charlotte 27 November 2017 (has links)
Au cours des dernières décennies, les stents coronaires et les stents déviateurs de flux intracrâniens ont révolutionné le traitement endovasculaire de deux pathologies artérielles différentes : la maladie coronarienne et les anévrismes intracrâniens. Ces deux types d’endoprothèses métalliques ont des mécanismes de fonctionnement différents, mais ils sont tous deux associés à des complications qui découlent de problèmes de biocompatibilité. En particulier, la couverture rapide de ces endoprothèses par des cellules endothéliales présentant un phénotype anti-inflammatoire et anti-thrombotique est cruciale pour leur intégration à l’interface vaisseau/sang. Par conséquent, le développement de solutions visant à améliorer l’endothélialisation et l’intégration de ces deux types de stents dans la paroi vasculaire représenterait un progrès majeur dans leur domaine respectif.Dans ce contexte, cette thèse porte sur l’immobilisation d’une molécule bioactive à la surface de stents coronaires et de stents déviateurs de flux, afin de résoudre leurs problèmes de biocompatibilité. La molécule bioactive utilisée est un peptide synthétique, appelé P8RI, qui promeut les fonctions régulatrices de la glycoprotéine transmembranaire CD31 : l’inhibition de l’activation des plaquettes et des leucocytes, ainsi que l’amélioration de la survie, de la migration et de la fonction de barrière des cellules endothéliales.La première partie de ce travail de thèse a consisté à développer un procédé d’immobilisation du P8RI sur des stents métalliques. Nous avons successivement adopté trois approches : l’immobilisation directe du peptide sur des surfaces d’alliage fonctionnalisées par plasma ; le dépôt chimique en phase vapeur assisté par plasma d’une couche intermédiaire de polymère ; et le dépôt d’une couche de polydopamine par auto-polymérisation, suivi de l’immobilisation d’un bras d’ancrage et de la liaison du P8RI par chimie click sans cuivre.Nous avons ensuite réalisé une évaluation in vitro de la biocompatibilité des surfaces d’alliage ainsi revêtues, en termes de propriétés anti-thrombotiques, anti-inflammatoires et pro-endothélialisation. Les surfaces sur lesquelles le P8RI avait été immobilisé ont montré une tendance à diminuer l’adhésion plaquettaire, à améliorer l’adhérence et la fonction de barrière de cellules endothéliales vasculaires humaines, et à promouvoir un phénotype anti-inflammatoire et anti-thrombotique chez ces dernières. Enfin, nous avons évalué in vivo des stents coronaires et déviateurs de flux recouverts de P8RI. Les stents coronaires ont été implantés dans des artères coronaires de porcs, et les résultats préliminaires ont montré une endothélialisation plus complète et une moindre densité de leucocytes adhérents sur les stents recouverts de P8RI que sur les témoins. Quant aux stents déviateurs de flux recouverts de P8RI, implantés dans un modèle d’anévrisme carotidien induit par incubation d'élastase chez le lapin, ils ont été associés à la formation d’une néointima plus épaisse et mieux organisée que sur les témoins, en particulier au niveau du collet anévrismal, ce qui implique de moindres risques de persistance du flux sanguin et de rupture d’anévrisme. / Over the last decades, coronary stents and intracranial flow diverting stents have revolutionized the endovascular treatment of two different arterial pathologies: coronary artery disease and intracranial aneurysms. The working mechanisms of these metallic endoprostheses are different but both are associated with complications stemming from biocompatibility issues. In particular, the rapid covering by endothelial cells presenting an anti-inflammatory and anti-thrombotic phenotype is key to the integration of the endoprosthesis at the blood/vessel interface. Thus, the development of solutions to improve the endothelialization and the integration of these two types of stents in the vessel wall would represent a major progress in their respective field.In this context, this thesis work deals with the immobilization of a bioactive molecule on coronary stents and flow diverting stents in order to solve their biocompatibility issues. The bioactive molecule that we used is a synthetic peptide, named P8RI, which promotes the regulatory functions of the transmembrane glycoprotein CD31 : the inhibition of platelets and leukocytes activation, as well as the enhancement of endothelial cell survival, migration and barrier function.The first part of this thesis work consisted in the development of a process for the immobilization of P8RI on metallic stents. We adopted three successive approaches: the direct immobilization of the peptide on plasma-functionalized alloy surfaces; the plasma-enhanced chemical vapor deposition of an intermediate polymeric layer; and the deposition of a polydopamine coating by self-polymerization, followed with the immobilization of a linker and the binding of P8RI by copper-free click chemistry.We then carried out an in vitro evaluation of the biocompatibility of the resulting coated alloy surfaces, in terms of anti-thrombotic, anti-inflammatory, and pro-endothelialization properties. The surfaces on which P8RI had been immobilized were shown to exhibit a tendency to decrease platelet adhesion, increase endothelial cell adhesion and barrier function, and promote an anti-inflammatory and anti-thrombotic phenotype in human vascular endothelial cells.Finally, coronary stents and flow diverting stents were evaluated in vivo. Coronary stents were implanted in the coronary arteries of farm pigs, and preliminary results showed a more complete endothelialization and a lesser density of adherent leukocytes on ‘P8RI-coated’ stents than on the controls. ‘P8RI-coated’ flow diverting stents were implanted in a rabbit elastase-induced carotid aneurysm model. Compared with the controls, they were associated with the formation of a thicker and better organized neointima, in particular on the stent struts in front of the aneurysm neck, which implies lesser risks of persistence of blood flow and aneurysm rupture.
3

Avledningseffektivitet och passagetid för atlantlaxsmolt (Salmo salar) med låglutande avledare / Diversion efficiency and passage time for Atlantic salmon smolt (Salmo salar) with low-slope diverters

Virmaja, Tommy January 2021 (has links)
Vattenkraften har en negativ miljöpåverkan på flera sätt, inte minst genom fragmentering av vattendrag. Därför är det viktigt att studera åtgärder som potentiellt minskar vattenkraftens inverkan. Här undersöktes experimentellt avledningseffektivitet och tidsåtgång för nedströmsvandrande atlantlaxsmolt hos låglutande avledare i en strömränna. Smolten startade uppströms om anläggningen och registrerades ifall de besökte flyktöppningarna i passagelösningen för nedströmsmigrerande fisk. Inom båda huvudtyperna, α- och β-avledare, testades tre olika avledare vardera där α-avledarna bestod av galler med spaltvidderna 15, 18 och 30mm. β-avledarna innefattade två galler med spaltvidderna 15 och 30 mm samt ett kevlarnät med entumsmaskor. Resultaten visade att hos α-avledare hade spaltvidden hos gallret betydelse för effektiviteten mellan största och minsta gallret. Mellan β-avledarna med 15 och 30 mm spaltvidd hade spaltvidden ingen betydelse varken för avledningseffektivitet eller tid till passage. Däremot var entumsnätet mindre effektivt. Resultaten indikerade att β-avledare var generellt mer effektiva än α-avledare med högre avledningseffektivitet, möjligen på grund av olikheter i konstruktionerna av flyktöppningarna i anslutning till avledarna. Resultatet pekar också på att β-galler kan ge upphov till en beteenderespons hos smolten som inte registrerades hos α-galler. / Hydropower has a negative environmental impact in several ways, not least through fragmentation of watercourses. This makes it important to study measures that potentially reduce the impact of hydropower. Here, diversion efficiency (passage) and time spent migrating by Atlantic salmon smolts was tested experimentally in a flume equipped with low-slope diverters, simulating passage of a hydropower plant. The smolt were released upstream of the facility and were registered if they visited the entrance to the flume’s passage solution for downstream migrating fish. In both main types, α- and β-diverters, three different diverters were tested each, where the α-diverters consisted of bar racks with gap widths of 15, 18 and 30mm. The β-diverters included two bar racks with gap widths of 15 and 30 mm and a kevlar net with 25 mm meshes. The results showed that in α-diverters, the gap width of the racks was important for the efficiency between the largest and smallest gap widths. Between the β-diverters with 15- and 30 mm gap width, the gap width had no significance either for efficiency or time to passage. However, the one-inch net was less efficient. The results indicated that β-racks were generally more efficient than α-racks with higher diverting efficiency, possibly due to differences in the constructions of the escape openings adjacent to the diverters. The result also suggests that β-racks may give rise to behavioral responses in the smolt that was not registered in α-racks.
4

Avledning av öringsmolt (<em>Salmo trutta</em>) från turbinintag / Diversion of trout smolts (<em>Salmo trutta)</em> from turbine intakes

Engqvist, Thérèse January 2009 (has links)
<p>Vattenkraftstationer, med dammar och turbiner, utgör hinder för nedströmsvandrande smolt. Syftet med denna studie var att undersöka turbindödligheten för öringsmolt (<em>Salmo trutta)</em> vid två kraftstationer, de befintliga ytlänsarnas avledningseffekt och om effekten kunde förstärkas genom mörkläggning i form av övertäckning av kraftkanalen med en presenning vid turbinintaget. Utöver detta var avsikten även att undersöka om det fanns något samband mellan smoltgrad och smoltens förmåga att förflytta sig mot havet. I Emån i Småland fångades 46 öringsmolt som radiomärktes och sattes ut vid två kraftstationer och pejlades dagligen i sex veckor. Det var en större dödlighet vid den övre stationen än vid den nedre. Ytlänsen vid den nedre stationen hade en klart avledande effekt, men inte ytlänsen vid den övre stationen. Samtliga smolt som valde passage via isutskovet, gjorde det när kraftkanalen vid turbinintaget var övertäckt med presenning (d.v.s. ljusintensiteten minskades kraftigt). Det gick inte att påvisa någon skillnad mellan låg och hög smoltgrad eller tidig och sen utsättning för fördröjning vid den ena kraftstationen, inte heller för förflyttning efter de två kraftstationerna.</p> / <p>Hydropower plants, with dams and turbines, form obstacles to smolts migrating downstream. The purpose of this study was to investigate turbine-induced mortality of brown trout (<em>Salmo trutta</em>) smolts at two power plants, guidance efficiency of existing diverters and whether the effect was enhanced by reducing light levels at the turbine intake by covering the power plant channel with an opaque tarpaulin. Furthermore, the aim was to investigate whether there was a relationship between smolt status and the smolts’ ability to move towards the sea. In the River Emån in Småland 46 trout smolts were caught, radio-tagged, released at two power plants and tracked daily for six weeks. There was a higher mortality at the upper power plant than at the lower one. The diverter at the lower power plant had a statistically significant guiding effect, but the diverter at the upper power plant did not. All of the smolts that chose passage through the trash gate did so when the power channel was covered with tarpaulin (i.e. light levels were greatly reduced). There was no evidence that smolt status or release date would affect passage times at the upper station, nor did smolt status affect swimming speeds downstream of the two power stations.</p> / Cost-Benefit Analysis of River Regulation
5

Avledning av öringsmolt (Salmo trutta) från turbinintag / Diversion of trout smolts (Salmo trutta) from turbine intakes

Engqvist, Thérèse January 2009 (has links)
Vattenkraftstationer, med dammar och turbiner, utgör hinder för nedströmsvandrande smolt. Syftet med denna studie var att undersöka turbindödligheten för öringsmolt (Salmo trutta) vid två kraftstationer, de befintliga ytlänsarnas avledningseffekt och om effekten kunde förstärkas genom mörkläggning i form av övertäckning av kraftkanalen med en presenning vid turbinintaget. Utöver detta var avsikten även att undersöka om det fanns något samband mellan smoltgrad och smoltens förmåga att förflytta sig mot havet. I Emån i Småland fångades 46 öringsmolt som radiomärktes och sattes ut vid två kraftstationer och pejlades dagligen i sex veckor. Det var en större dödlighet vid den övre stationen än vid den nedre. Ytlänsen vid den nedre stationen hade en klart avledande effekt, men inte ytlänsen vid den övre stationen. Samtliga smolt som valde passage via isutskovet, gjorde det när kraftkanalen vid turbinintaget var övertäckt med presenning (d.v.s. ljusintensiteten minskades kraftigt). Det gick inte att påvisa någon skillnad mellan låg och hög smoltgrad eller tidig och sen utsättning för fördröjning vid den ena kraftstationen, inte heller för förflyttning efter de två kraftstationerna. / Hydropower plants, with dams and turbines, form obstacles to smolts migrating downstream. The purpose of this study was to investigate turbine-induced mortality of brown trout (Salmo trutta) smolts at two power plants, guidance efficiency of existing diverters and whether the effect was enhanced by reducing light levels at the turbine intake by covering the power plant channel with an opaque tarpaulin. Furthermore, the aim was to investigate whether there was a relationship between smolt status and the smolts’ ability to move towards the sea. In the River Emån in Småland 46 trout smolts were caught, radio-tagged, released at two power plants and tracked daily for six weeks. There was a higher mortality at the upper power plant than at the lower one. The diverter at the lower power plant had a statistically significant guiding effect, but the diverter at the upper power plant did not. All of the smolts that chose passage through the trash gate did so when the power channel was covered with tarpaulin (i.e. light levels were greatly reduced). There was no evidence that smolt status or release date would affect passage times at the upper station, nor did smolt status affect swimming speeds downstream of the two power stations. / Cost-Benefit Analysis of River Regulation

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