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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.
161

Complexions Which Forms The Sightings Of A Trace : A brief history of The Hollow Earth and some reflections on the project and exhibition called Almost through the theory of a whole

Berglund, Karl-Erik Birt January 2022 (has links)
This essay describes part of the process behind the exhibition Almost through the theory of a whole. This includes a short historical background of the subject matter (The hollow earth theory) and certain theoretical frameworks and perspectives that has been used in the process. These theories include Michel Serres theory of noise and C. G. Jungs theory of synchronicity.  Further the essay looks at conspiracy theory, artifitial intelligence and art making thorugh these theories.
162

Utveckling av en kontinuerlig process som renar vatten från läkemedel med hjälp av biopolymertäckta celler / Development of a continuous process for the removal of pharmaceuticals in wastewater using biopolymer covered Escherichia coli

Lindroos, Magnus January 2015 (has links)
No description available.
163

Process Modeling of CO2 Capture through Membranes

Da Conceicao Acosta, Marcos January 2021 (has links)
No description available.
164

Les structures en creux du site mésolithique d'Auneau "le Parc du Château" (Eure-et-Loir) : nouveau bilan et implications concernant le mode de vie des dernières populations de chasseurs-collecteurs en Europe / The Mesolithic pits at "Le Parc de Château" in Auneau (Eure-et-Loir - France) : a new report and its relationship with the latest European hunter-gatherer way of life

Verjux, Christian 30 January 2015 (has links)
Ce travail s'appuie sur un nouveau bilan concernant les 70 structures en creux mésolithiques du site du « Parc du Château » à Auneau (Eure-et-Loir), datées entre 8 000 et 5 500 ans avant J.-C. Leurs fonctions variées — sépultures, dépôts intentionnels de restes animaux, foyers en fosse, calages de poteau, extraction, stockage, dépotoirs — évoquent des installations d'une certaine durée. Une enquête étendue à une bonne partie de l'Europe permet de recenser plus d'une centaine d'autres sites mésolithiques livrant des structures analogues, parfois en grand nombre. Il en ressort une image très éloignée de la vision traditionnelle de ces sociétés (cf. chasseurs-collecteurs très mobiles aux campements temporaires sommairement aménagés). Deux types de structures retiennent particulièrement l'attention : les fosses destinées au stockage alimentaire enterré (cf. silos) laissent envisager une consommation différée de fruits à coque (noisettes, glands) permettant de s'affranchir des cycles saisonniers ; les fosses-dépotoirs attestent, quant à elles, une gestion des déchets évoquant des installations durables. On en déduit que le développement de stratégies de subsistance adaptées à un riche environnement post-glaciaire a pu favoriser la sédentarisation de certains groupes de chasseurs-collecteurs stockeurs dès le Mésolithique moyen — bien avant donc les premiers contacts avec les populations néolithiques. L'apparition des premiers cimetières en Europe constitue un autre indice très évocateur d'une restriction de la mobilité, également perceptible à travers certains impacts anthropiques sur le milieu et divers types d'équipement (outillage lourd, vannerie, pirogues, pêcheries). / Our research leans on new analysis about the Mesolithic pits discovered during the excavation at "le Parc du Château" in Auneau (Eure-et-Loir; France). These 70 pits date between 8.000 and 5.500 cal. BC. Their various functions — i.e. graves, faunal hoards, pit-hearths, post-holes, extraction, storage, rubbish dumps — evocate long duration settlements. A European survey links to record more than 100 sites With such features, sometimes very numerous. These new data provide an original pattern, quite different from the traditional models of very mobile hunter-gatherer and short time encampment. Two kinds of features seem to be especially significant: food storage pits (similar to silos) may have allowed a delayed consumption of nuts (hazelnut or acorn) providing the bulk of food during the season of scarcity; rubbish pits indicate waste management linked to long term dwellings. From our point of view new subsistence strategies related with rich post-glacial environmental resources may allow some storing hunter-gatherer groups to adopt a sedentary way of life Since the middle Mesolithic — i.e. several millennia before the first interactions with Neolithic populations. The emergence of actual cemeteries in Euro e at the same period reveals also decreasing mobility evidence likewise some anthropogenic impacts on the environment and various equipment such as heavy lithic tools, basketry, pirogue, fishery, and so on.
165

Characterization and Physicochemical Modifications of Polymer Hollow Fiber Membranes for Biomedical and Bioprocessing Applications

Madsen, Benjamin R. 01 May 2010 (has links)
Hollow fiber membranes (HFMs) formed through phase inversion methods exhibit specific physicochemical characteristics and generally favorable surface and mechanical properties, supporting their use in diverse applications including ultrafiltration, dialysis, cell culture, bioreactors, and tissue engineering. Characterization of, and modifications to, such membranes are important steps in achieving desired characteristics for specific applications. HFMs subject to gas, irradiation, and chemical sterilization techniques were characterized based on several analytical techniques. It was revealed that these common sterilization techniques can cause inadvertent changes to HFM properties. While these changes may cause detrimental effects to HFMs used in filtration, the methods of sterilization are also presented as a facile means of tuning properties toward specific applications. Modifications to HFM surface chemistries were also sought as a method of adsorbing bacterial lipopolysaccharide (LPS) from solutions used in hemodialysis treatments and bioprocessing applications. It was found that additives such as polyvinylpyrrolidone (PVP), polyethyleneglycol (PEG), and poly-L-lysine (PLL) can facilitate adsorption capacities of HFMs toward LPS. Additionally, chemical changes are presented as a means of preferentially adsorbing LPS to specific locations on the HFM surface.
166

Design, Fabrication and Applications of Organic-Inorganic Hybrid Systems

Agrawal, Mukesh 19 September 2008 (has links)
A simple and facile way to the fabrication of nano to micro scale organic-inorganic hybrid particles was demonstrated. A well known “template-assisted approach” was chosen for the preparation of these hybrid particles, in which the inorganic material of interest is templated against the template particles. A series of colloidal template particles including, polystyrene, poly (vinylcaprolactam) and poly (N-isopropylacrylamide) was used for the deposition of a variety of metal oxides/hydroxide nanoparticles. A classical surfactant free co-polymerization process was employed for the synthesis of these template particles. To facilitate the deposition of inorganic nanoparticles in subsequent steps, these colloidal particles were functionalized with the suitable functional groups. For this purpose, polystyrene particles were synthesized in the presence of acetoacetoxyethylmethacrylate (AAEM) co-monomer. Similarly, poly (vinylcaprolactam) and poly (N-isopropylacrylamide) particles were functionalized by adding AAEM and acrylic acid co-monomers, respectively, during their synthesis. It is thought that an effective interaction between these functionalities of employed template and metal oxide/hydroxide precursors is the driving force for the fabrication of organic-inorganic hybrid particles. A number of metal oxide/hydroxide nanoparticles including ZnO, TiO2, Ta2O5 and In(OH)3 were deposited on the surface of polystyrene colloidal particles. A systematic variation in the employed reaction conditions allowed a modulation in size, shape, morphology, shell thickness and inorganic contents of resulting hybrid particles. Similar effect of the employed Indium isopropoxide concentration on the morphology of PS-In(OH)3 hybrid particles was observed. In the case of PS-TiO2 and PS-Ta2O5 only core-shell morphology was observed. However, suitable surface chemistry and careful selection of reaction parameters allowed the deposition of as much thick as 130 nm TiO2/Ta2O5 shell on the polystyrene core. In addition, a controlled manipulation of the shell thickness with the employed concentration of inorganic salt was observed. Polystyrene colloidal particles coated with a high refractive index material such as TiO2, were employed as building blocks for the fabrication of self assembled colloidal crystals. The variation in particle size and TiO2 content of employed building blocks allowed the manipulation in stop band position and band width of resulting photonic structures. Furthermore, PS-ZnO hybrid particles with raspberry-like morphology were exploited as carrier for ZnO nanoparticles into a host polymer matrix to achieve a nanocomposite material. In addition, fabrication of a series of closed, intact and mechanically robust hollow spheres, composed of pure and mixed metal oxides was demonstrated. The removal of polystyrene core from PS-TiO2 and PS-Ta2O5 hybrid particles by chemical or thermal treatment resulted into the hollow TiO2 and Ta2O5 spheres, respectively. Templating of PVCL colloidal particles against ZnO nanoparticles was shown and variation in physical properties of the resulting hybrid microgels as a function of the loaded amount of ZnO nanoparticles was demonstrated. PVCL-ZnO hybrid microgels showed the temperature sensitivity of the template particles and the UV-absorbing property of the loaded ZnO nanoparticles. It was demonstrated that these hybrid materials can effectively be used in the preparation of a transparent UV-shielding material. In addition, the deposition of preformed and functionalized quantum dots (CdTe) on the surface of PNIPAm microgel particles was explored and a manipulation in the fluorescent properties of loaded quantum dots as a result of temperature induced swelling and deswelling of microgel template was investigated. It was found that the fluorescence of deposited quantum dots can be switched to “ON” or “OFF” by changing the temperature of the surrounding media. These hybrid particles are envisioned to be used in the fabrication of temperature nanosensors.
167

Electrically conductive hollow fiber membrane development: addressing the scalability challenges and performance limits of conductive membrane fabrication

Larocque, Melissa January 2020 (has links)
Electrically conductive membranes (ECMs) are of significant research interest for their ability to mitigate fouling, enhance separation capacity, and induce electrochemical degradation of contaminants. Most ECM development has been in flat sheet format suitable for laboratory studies; in industrial applications, formats such as hollow fiber (HF) are preferred for their high packing density. While ECMs in HF format are emerging in research, these techniques typically employ the same methods proven for flat sheet, often involving direct deposition of conductive material onto a support membrane with no further investigation into how the deposition process affects ECM properties. This is a significant challenge for long (~1 m) HF membranes where coating uniformity is essential to ensure consistent performance. The goal of this project was to fabricate conductive HF membranes, ensuring uniform performance along the fiber. In this work, we have developed a “crossflow deposition” technique to deposit a uniform layer of single walled/ double walled carbon nanotubes (SW/DWCNTs) onto the interior surface of commercial polyether sulfone HF membranes. In a design-of-experiments model, feed pressure and crossflow velocity were shown to directly impact composite membrane conductivity and permeability. The highest permeability (~2900 LMH/bar) and conductivity (~670 S/m) were both achieved at the high pressure (0.2 bar) and high crossflow velocity (1.06 cm/s) condition. An inverse relationship was identified between conductivity and permeability for 29 different HF membranes coated under various flow and particle loading conditions. Similar trends were evident in ECM literature when comparing 80 membranes across 38 papers, covering various conductive materials, separation types, configurations, and applications. Metallic-based ECMs outperformed graphitic nanomaterial or conductive polymer-based ECMs with conductivities three orders of magnitude higher. This review also revealed a wide variation in performance testing with 35 unique pollutants in 63 total tests, indicating a need for standardization to accurately compare ECMs and a need for testing with more realistic feed sources. Finally, electrochemical degradation of methyl orange using the CNT-coated HF membranes was evaluated in batch and continuous removal experiments. Although no significant MO removal was detected in either configuration, these modules can be used for further optimization in terms of targeted conductivity, contact time, and electrochemical parameters such as applied voltage. This work highlights the existence of a conductivity/ permeability trade-off in ECM development and how manipulation of flow parameters during deposition can impact this trade-off in HF membrane development. / Thesis / Master of Applied Science (MASc) / Membrane separation technologies are a common purification strategy in many fields due to their simplicity and low energy requirements. Membranes operate by rejecting particles from feed water based on their chemical or physical properties such as size or charge. Long-term membrane operations are limited by fouling, incurring large operating costs for frequent cleaning cycles and downtime. Furthermore, traditional membrane separations only physically remove particles, presenting a risk for contaminant re-introduction into the environment. Electrically conductive membranes are an emerging strategy for addressing these concerns due to their demonstrated antifouling, enhanced selectivity, and redox capabilities. To date, these membranes have almost exclusively been developed as flat sheets with limited research into other membrane formats. Hollow fiber membranes resemble thin tubes ~1 mm in diameter and up to ~1 m in length where filtration occurs through the tubular wall of the fiber; the small diameter allows for hundreds of fibers to pack into an individual module, thus maximizing throughput. In this thesis, several issues with hollow fiber conductive membrane fabrication are addressed to ensure consistent performance along the length of the fiber. A key trade-off between membrane surface conductivity and throughput was found to exist universally in the conductive membrane field. This knowledge can be used to select fabrication methods and parameters to target certain performance ranges.
168

Design of Hollow Reinforced Concrete Columns in the Tubed Mega Frame : Dimensionering av ihåliga armerade betongpelare i ”Tubed Mega Frame”

Tönseth, David, Welchermill, Kristian January 2014 (has links)
A new concept for the structural system for tall buildings, called the “Tubed Mega Frame”, has been developed by Tyréns AB. The structure consists of several hollow reinforced concrete columns at the perimeter of the building and at certain levels, the columns are tied together with perimeter walls. Together they carry all the vertical and lateral loads. A purpose of the new concept is to eliminate the core in the center of the building which allows utilizing more floor spacing compared with other skyscrapers. This kind of structure has never been examined before and thus never been designed for such a large building. In this thesis the vertical hollow concrete columns are designed according to the American concrete design code, ACI 318. A literature study on reinforced concrete columns has been investigated, where the goal was to identify the most critical design aspects for columns in high rise structures, especially utilizing high strength concrete. Since this kind of structure never has been designed before, an evaluation of the ACI 318 has been performed to check if it is possible to design the hollow reinforced columns in the Tubed Mega Frame according to this design code. The loads and forces used for the design were extracted from a global finite element model in ETABS of a concept prototype of 800 meter. The design process consisted of design calculations according to the ACI 318, a buckling analysis in SAP2000 and a non-linear FE-analysis in ATENA. For the buckling analysis in SAP2000 the lower region of the building was isolated between two main perimeter walls. The model was modified several times to analyze how sensitive the structure was to buckling, with regard to different wall thicknesses, cracked cross-sections, openings in the columns and the dependency of intermediate perimeter walls. The non-linear analysis in ATENA focused on a single hollow column between two perimeter walls in the lower regions of the building. Two models were created, one with a full wall thickness and one with a reduced wall thickness where the ultimate capacity and failure behavior of the columns were investigated. The ultimate capacity of the sections designed by hand calculations and analyzed in ATENA were found to be brittle failure modes. To achieve a more ductile failure, an alternative reinforcement geometry with confining reinforcement has been proposed. The results from the design shows that the structure is redundant against buckling, even with reduced bending stiffness and without intermediate perimeter walls. From the analysis in ATENA, the results demonstrated that the columns are capable of carrying all the ultimate loads even if the wall thickness is reduced by 50%, and that it is possible to use the ACI 318 to design the reinforced concrete columns. However, an unexpected brittle failure occurred in the flanges of the column corners in the tensile region were shear lag may affect the behavior and caused the premature failure. A deductive conclusion has been drawn which states that proper confinement will be critical to achieve a ductile failure behavior even in the tensile region, which will require further studies in order to fully understand the behavior. Even though the results show that it was possible to reduce the cross-sectional thickness of the columns, more studies have to be performed to evaluate if the global structure fulfills the requirements with the decrease in column wall thickness. / Ett nytt strukturellt koncept för skyskrapor har utvecklats av Tyréns AB, "Tubed Mega Frame", där strukturen består av flera ihåliga armerade betongpelare i utkanten som hålls samman med omslutande tvärväggar, och tillsammans bär de alla vertikala och laterala laster. Denna typ av konstruktion har aldrig analyserats eller utformats tidigare. I detta examensarbete är de vertikala ihåliga betongpelarna dimensionerade enligt den amerikanske byggnormen, ACI 318 och de kritiska aspekterna med att utforma ett höghus i höghållfast betong med ihåliga pelare undersökts. Eftersom denna typ av konstruktion aldrig tidigare utformats, har en utvärdering av ACI 318 genomförts för att kontrollera om det är möjligt att dimensionera de ihåliga vertikala pelarna i Tubed Mega Frame enligt denna norm. De laster och krafter som används för dimensioneringen extraherades ur en global finit elementmodell för en konceptbyggnad på 800 meter i ETABS. Den dimensionerande processen bestod av dimensioneringsberäkningar enligt ACI 318, en knäckningsanalys i SAP2000 och en icke-linjär FEM-analys i ATENA. För knäckningsanalysen i SAP2000 isolerades en sektion i den nedre regionen av byggnaden, mellan två omslutande tvärväggar. Modellen ändrades flera gånger för att analysera hur känslig konstruktionen var med hänsyn till knäckning, och de ändringar som gjordes var: minskning av väggtjocklekar, reducering för spruckna tvärsnitt, öppningar i pelarna samt de omslutande mellanliggande tvärväggarnas inverkan på knäckningen av konstruktionen. Den icke-linjära analysen i ATENA fokuserade på en pelare mellan två omslutande tvärväggar i den lägre regionen av byggnaden. Två modeller skapades, en med en full väggtjocklek och en med en reducerad väggtjocklek för att analysera brottbeteendet och verifiera den handberäknade kapaciteten enligt ACI 318. De brottmoder som påträffades för tvärsnittsverifikationen i ATENA var spröda och karakteriserades med krossning av betongen, och för att uppnå ett mer segt brott härleddes en alternativ armeringsgeometri med sammanhållande armeringsbyglar i de mest kritiska regionerna av pelarna. Resultaten visade att konstruktionen är robust mot knäckning, även med minskad böjstyvhet och utan mellanliggande omslutande tvärväggar. Av analysen i ATENA visade resultaten att pelarna är kapabla att bära alla de kritiska lasterna även om väggtjockleken reduceras med 50 % och att det är möjligt att använda ACI 318 som norm för dimensionering av pelarna i Tubed Mega Frame. Dock inträffade ett oväntat sprött brott i den dragna flänsen i nedre regionen av pelaren, framförallt koncentrerat till hörnen. Anledningen till det spröda brottet har utvärderats och analyserats där hypotesen är att flänsskjuvning i kombination med höga spänningskoncentrationerna i hörnen orsakar det lokala brottbeteendet i flänsen. Slutsatsen som baseras på hypotesen är att sammanhållande armeringsbyglar skulle vara avgörande för att uppnå ett segt brottbeteende även för den dragna flänsen. Även om resultaten visade att det var möjligt att reducera tvärsnittstjockleken för pelarna, krävs mer studier för att utvärdera om den globala konstruktionen uppfyller kraven för en minskning av pelarnas väggtjocklekar.
169

Examination of an Abandoned Underground Lake in the Scott Hollow Drainage Basin, Southeast West Virginia

Addo, James Nii Kamuah 09 June 2009 (has links)
No description available.
170

On-Chip Atomic Spectroscopy

Conkey, Donald B. 16 March 2007 (has links) (PDF)
This thesis presents the integration of atomic vapor cells with anti-resonant reflecting optical waveguides (ARROWs) fabricated on silicon chips. These potentially provide a compact platform for a number of optical applications, including the study of quantum coherence effects such as electromagnetically induced transparency and single-photon nonlinearities, as well as frequency stabilization standards. The use of hollow waveguides allows for light propagation in low index (vapor) media with compact mode areas. ARROWs make particularly attractive waveguides for this purpose because they can be interfaced with solid core waveguides, microfabricated on a planar substrate, and are effectively single mode. ARROW fabrication utilizes an acid-removed sacrificial core surrounded by alternating plasma deposited dielectric layers, which act as Fabry-Perot reflectors. To demonstrate the effectiveness of the ARROW as a vapor cell, a platform consisting of solid and hollow core waveguides integrated with rubidium vapor cells was developed. A variety of sealing techniques were tested for vapor cell integration with the ARROW chip and for compatibility with rubidium. Rubidium was used because it is of particular interest for studying quantum coherence effects. Liquefied rubidium was transferred from a bulk supply into an on-chip vapor cell in an anaerobic atmosphere glovebox. Optical absorption measurements confirmed the presence of rubidium vapor within the hollow waveguide platform. Further analysis of the measurements revealed high optical density of rubidium atoms in the hollow core. Saturated absorption spectroscopy measurements verified that the on-chip integrated vapor cell was suitable for common precision spectroscopy applications.

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