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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.
361

Synthesis of AcGGM Polysaccharide Hydrogels

Maleki, Laleh January 2016 (has links)
Lignocellulosic biomass is believed to serve a prominent role in tomorrow’s sustainable energy and material development. Among the polysaccharide fractions of lignocellulosic biomass, the potential of hemicelluloses as a valuable material resource is increasingly recognized. Thanks to their hydrophilic structure, hemicelluloses are suitable substrates for hydrogel design. The work summarized in this thesis aims to develop feasible strategies for the conversion of O-acetyl galactoglucomannan (AcGGM), an ample hemicellulose in softwood, into hydrogels. Within this framework, four synthetic pathways targeting the formation of crosslinked hydrogel networks from pure or unrefined AcGGM fractions were developed.   Aqueous AcGGM-rich and lignin-containing side-stream process liquors of forest industry, known as softwood hydrolysates (SWHs) were formulated into highly swellable hydrogels by: i) allyl-functionalization of AcGGM chains of crude SWH to obtain a viable precursor for hydrogel synthesis via free-radical crosslinking, ii) directly incorporating unmodified SWH fractions into semi-interpenetrating polymer networks (semi-IPNs). SWH hydrogels and semi-IPNs were characterized with appreciable maximum swelling ratios of Qeq = 170 and Qeq = 225, respectively.   Rapid crosslinking of AcGGM through thiol-click chemistry was addressed by first imparting thiol functionality onto pure AcGGM chains in a one-pot procedure. The thiolated AcGGM proved to be a suitable substrate for the synthesis of hemicellulose hydrogels via thiol-ene and thiol Michael addition reactions. Finally, sequential full IPNs were developed by subjecting single network hydrogels of pure AcGGM to a second network formation. IPNs obtained through either free radical crosslinking or thiol-ene crosslinking exhibited higher shear storage moduli than their single network counterparts. / <p>QC 20161102</p>
362

Optimalizace metod pro studium časných fází životního cyklu myšího polyomaviru / Optimization of methods for analysis of early steps of mouse polymavirus life cycle

Soukup, Jakub January 2015 (has links)
Mouse polyomavirus is a type species of Polyomaviridae family and serves as model for studying viral infection of human pathogenic polyomaviruses. Minor proteins of viral capsid have been found to be necessary for effective initiation of infection. In order to study their role in the early steps of infection we utilized the novel Cre-LoxP system for production of the viral mutant lacking both minor proteins. Virus produced this way was compared with virus produced by standard method and we found that both systems facilitate production of mutant virus with the comparable quality and quantity. The mutant virus contained reduced amount of viral DNA and formed virions with impaired stability. For further studies of intracellular virion trafficking we prepared virions with genomes modified by thymidine analogues 5- bromo-2'-deoxyuridine (BrdU) and 5-Ethynyl-2'-deoxyuridine (EdU) and optimized the methods for analogue detection. The viral genome become accessible for detection 4 hours post infection. For ultramicroscopic analysis of translocation of virus to the nucleus we used freeze substitution. All this methods will be utilized for detailed study of distinct steps in viral infection. Key words: Mouse polyomavirus, minor proteins,...
363

Élaboration de copolymères amphiphiles à base de poly (3-hydroxyalcanoate)s / Design of poly (3-hydroxyalkanoates)-based amphiphilic copolymers

Babinot, Julien 12 December 2012 (has links)
Les poly (3-hydroxyalcanoates) (PHAs) sont des polyesters aliphatiques produits et accumulés par des bactéries en tant que réserve de carbone et d'énergie. Ils sont constitués d'unités β-hydroxyesters et possèdent des chaînes latérales de longueur variable, pouvant être fonctionnalisées. Ils possèdent des propriétés de biodégradabilité et de biocompatibilité; ceci leur confère de vastes possibilités d'utilisation dans le domaine biomédical, notamment pour la mise au point de systèmes de libération contrôlée de principes actifs. Dans cette optique, nous nous sommes intéressés à la synthèse de copolymères amphiphiles de différentes architectures à base de PHAs, ainsi qu'à l'étude de leurs propriétés d'auto-association en milieu aqueux. Une méthode simple et efficace permettant le greffage d'oligomères de poly (éthylène glycol) (PEG) a tout d'abord été mise au point grâce à l'utilisation de la chimie « click ». Une série de copolymères diblocs bien définis PHA-b-PEG a ainsi pu être synthétisée par cycloaddition de Huisgen catalysée par le cuivre (CuAAC). Les copolymères diblocs à base de PHAs à moyennes chaînes latérales (PHA-mcl) ont montré leur capacité à s'auto-associer en milieu aqueux et à former des micelles monodisperses présentant une concentration micellaire critique très faible. Par la suite des copolymères de type greffés PHOU-g-PEG ont été synthétisés par addition thiol-ène. Les analyses par cryo microscopie électronique à transmission (cryo-TEM) ont montré que dans ce cas les copolymères s'auto-associaient en structures vésiculaires, ou polymersomes. Enfin, la synthèse de copolymères amphiphiles greffés porteurs de chaînes perfluorées PHOU-g-(F;PEG) a permis l'obtention de structures auto-associées plus complexes. Le cryo-TEM a en effet révélé la formation de micelles multicompartimentées, c'est à dire possédant un coeur présentant une séparation de phase entre les domaines hydrophobes et les domaines fluorés. Des tests biologiques préliminaires ont montré la cytocompatibilité de ces micelles / Poly (3-hydroxyalkanoates) are natural aliphatic polyesters produced and accumulated by many bacteria as carbon and energy supply. They consist of β-hydroxy ester units, with pendant side chains of different lengths that can be functionalized. Thanks to their biodegradability and biocompatibility, they are promising polymers for biomedical applications, especially for controlled drug delivery systems. In this context, we aimed to synthesize PHA-based amphiphilic copolymers with different molecular architectures, and to study their self-assembly in water. First, a simple and straightforward method using click chemistry has been used to graft poly(ethylene glycol) (PEG) oligomers. A series of well-defined diblock copolymers PHA-b-PEG has thus been synthesized using copper-catalyzed azide-alkyne cycloaddition (CuAAC). Medium chain length PHA-based diblock copolymers have shown their ability to self-assemble into stable micelles having very low critical micelle concentrations. Afterwards, amphiphilic graft copolymers PHOU-g-PEG have been synthesized using thiol-ene addition. In this case, cryo-electron microscopy (cryo-TEM) analysis revealed that graft copolymers self-assembled into vesicular morphologies, i.e. in polymersomes. Finally, the synthesis of amphiphilic graft copolymers bearing perfluorinated chains PHOU-g-(F;PEG) was performed. After aqueous self-assembly, cryo-TEM shown the formation of multicompartment micelles, i.e. with a core displaying segregated hydrophobic and fluorophilic domains. Moreover, these multicompartment micelles have shown their cytocompatibility
364

Avtalstolkning i det digitala samhället med fokus på konsumentförhållanden

Karlsson, Linnea, Banda, Aleksandra January 2019 (has links)
I det digitala samhället pågår en ständig utveckling, och konsumenter ingår mer och mer avtal på internet. Lagen (1915:218) om avtal och andra rättshandlingar på förmögenhetsrättens område, (fortsättningsvis, avtalslagen eller AvtL) tilkom för mer än 100 år sedan. Det traditionella sättet att ingå avtal mellan avtalsparterna är i pappersform genom att ena parten lämnar ett anbud som följer av en accept av motparten. Idag har utvecklingen gått framåt och det är idag vanligare att konsumenter ingår avtal på internet genom att acceptera avtalsvillkor som är utformade som standardavtal. Anledningen till det är att standardiserade avtal gör det möjligt för näringsidkaren att nå ut till en större kundkrets och således inte behöver upprätta individuella avtal i varje avtalsförhållande. Det är därför förmånligt att tillämpa standardavtal mellan näringsidkare och konsument. Konsumenter accepterar och ingår dagligen avtal på internet genom att godkänna avtalsvillkor eller användarvillkor för att få tillgång till en hemsida, det sker främst genom clickwrap-avtal.1 En konsument kan även bli bunden av ett avtal utan att acceptera avtalsvillkor genom, s.k browsewrap-avtal. 2Det är vanligt att konsumenter godkänner villkor på internet utan vetskap om att de har ingått ett avtal. Konsumenter binder sig till avtal på internet genom ett enkelt knapptryck eller genom att enbart besöka hemsidan. Om villkoren som konsumenter accepterar anses oskäliga finns det möjlighet att tillämpa det tvingande ogiltighetsreglerna i avtalslagen för att jämka eller ogiltighetsförklara hela eller delar av avtalet. I uppsatsen analyseras frågan i vilka fall en konsument anses juridisk bunden av ett avtal på internet samt hur domstolen bör gå tillväga vid tolkning av elektroniska avtal med hjälp av avtalsrättsliga tolkningsprinciper. Slutligen analyseras vilka ogiltighetsgrunder i avtalslagen som kan tillämpas på elektroniska avtal som bedöms oskäliga. För att undersöka vilka avtal eller avtalsvillkor som kan bedömas oskäliga gentemot konsumenten tillämpas även lagen om avtal och andra rättshandlingar på förmögenhetsrättens område (1915:218) (AVLK) samt lagen (2005:59) om distansavtal och avtal utanför affärslokaler (distansavtalslagen eller DAvtL). Uppsatsen avslutas med en slutsats kring våra egna reflektioner på området där vi kommer fram till att det inte finns ett entydigt svar kring vilka avtalsrättsliga bestämmelser och principer som är tillämpbara på elektroniska avtal. Det har lett till att dagens digitala samhälle har skapat ett behov av en förnyad avtalslag som är mer anpassad för avtal som ingås på internet.
365

Life cycle analysis as a tool for CO2 mitigation in the building sector

Östling, Ida January 2018 (has links)
After the Paris agreement 2015 the Energy Commission in Sweden proposed a goal for Sweden of net zero greenhouse gas emissions by 2045. The focus in this report has been on how buildings in Sweden could reduce their greenhouse gas emissions. Year 2017 the government gave a task for Boverket in Sweden (National Board of Housing, Building and Planning) to investigate the possibility to introduce a climate declaration on buildings. The idea is a life cycle analysis (LCA) should be performed on the building in order to get a building permit. An LCA include all CO2 emissions emitted from resources used for raw material extraction, production of materials, construction site operations, user phase and also the demolition and disposal in the end of life of the building. The first draft from Boverket was published in February 2018 where they recommended a simple declaration. They recommended in the beginning to only include a few components in the declaration, and to only include the production phase. The major interest in this report have been to gain more understanding on how to perform LCAs and also how the LCA result could be used to decrease CO2 emissions. A case study was made on a residential building project called Mården, in Umeå Sweden. The first part in this thesis was to determine the phase in the buildings life cycle with the largest potential for decreasing CO2 emissions. When the LCA was performed on case study building Mården it was difficult to use exact data, since only 20 % of the construction products where declared in an environmental product declaration (EPD). Therefore the other 80 % where approximated with similar products declared in an EPD, or with generic data (general data for a type of product). An EPD is an LCA on a single product and could therefore give exact information on CO2 emissions for a specific product. However, several improvements where implemented in the buildings life cycle and where compared with this reference case. The result from the LCA showed the energy use in the user phase emitted the largest amount of CO2 emissions, and therefore also where the phase with the largest potential for reducing CO2 emissions. When the Swedish district heating mix where replaced with an energy source with 50 % less CO2 emissions, the emissions for the whole life cycle could be decreased with 20 %. Smaller improvements such as more environmental friendlier concrete, shorter transport distance between manufacturer and construction site or less water usage resulted in a decrease by 1.6-7 %. It was though shown these smaller improvement could result in a large decrease of CO2 emissions if more buildings also would improve the same thing. 2.4 million tons of CO2 emissions could for example be reduced in Sweden if 50 % of Sweden’s all new building projects would improve their choice of concrete. To make sure buildings could reduce their CO2 emissions there is important LCAs are performed before the building is constructed, to make sure all phases in the life cycle can be improved. If an LCA will be performed when the building is constructed, it is only possible to improve a few parts in the user phase, since the other phases already have passed. The second part in this thesis was to compare the different LCA softwares; (i) One Click LCA (needs license, from Finland), (ii) e-tool (free, from Australia) and (iii) BM (free, from Sweden). When more exact data were tried to be used in e-tool and One Click LCA the results were similar for the CO2 emissions from the production phase. E-tool only resulted in 6 % higher CO2 emissions in the production phase than One Click LCA. The LCA in the eventual future climate declaration will probably be performed with generic data, since in an early stage the contractors will not have detailed information on their construction products. An LCA was thus performed in each software with generic data, and the result differed a lot. The CO2 emissions from the production phase resulted in 36 % and 23 % less CO2 emissions in BM and e-tool than in One Click LCA. If several softwares will be allowed in this eventual climate declaration, the judgment could be difficult since different generic data is used in each sofware. The generic data were also different for one type of product in a single software, where the CO2 emission could differ with as much as 50 % between two types of generic data for one type of products. This leads to a difficulty when choosing generic data since there will be lack of information on the construction products at the time when this eventual climate declaration should be performed. A main focus for the future development should be on evaluating a standard database that could be used in EU. If a future law will be implemented it could be valuable to declare detailed rules on how to perform the LCA. Since depending on who will perform the LCA different results could occur due to different data used or assumptions on things like products, boundaries or used resource. However, this master thesis has shown there is possible to use the LCA methodology to find solutions for decreasing the CO2 emissions for buildings.
366

A influência do número de habitantes de uma cidade na propensão à seleção e compra de produtos pela internet

Silva, Guilherme Ferrari da January 2016 (has links)
A Internet vem transformando a maneira como as pessoas compram e buscam por informações sobre produtos. Para locais onde as ofertas físicas apresentam algum tipo de restrição, os canais online podem trazer mudanças ainda mais significativas, já que oferecem aos consumidores um sortimento virtualmente ilimitado. O objetivo deste trabalho foi o de analisar a influência do número de habitantes de uma cidade em relação à predisposição à seleção e compra de produtos de uma empresa que administra campanhas de divulgação pela Internet para venda por atacado. As cidades foram divididas em três grupos conforme o número de habitantes e as principais métricas de performance das campanhas online foram comparadas entre os grupos através de análises de estatísticas descritivas, ANOVA e testes post hoc. Os grupos apresentaram diferenças estatisticamente significativas entre si em todas as etapas do processo de busca e compra. A principal diferença encontrada foi no momento em que os usuários preencheram cadastros no site, demonstrando interesse nos produtos. Nesta etapa, os consumidores de municípios de menor porte se cadastraram proporcionalmente mais do que o dobro dos de cidades de porte intermediário e mais de três vezes em relação ao grupo das maiores, o que impactou diretamente no custo por venda realizada e nas taxas absolutas de vendas. / The Internet has been changing the way people buy and search for new products. In places where the assortment in brick-and-mortar stores is restricted, online channels may represent a significant change in the landscape, due to the fact that they carry virtually unlimited offers. The aim of this study is to analyze the influence of the number of inhabitants of a city on their likelihood of selecting and purchasing products from a company which runs online marketing campaigns for resellers. The cities were divided in three groups according to the population size. In addition, the main metrics for online campaigns were compared among groups through descriptive statistics, ANOVAs and pot hoc tests. There was a statistically significant difference among the groups in all steps of the search and purchase process. The main difference was found when the users fill in the forms in the website, demonstrating interest in the product. In this stage, customers from smaller cities showed a registering rate which was more than twice as much higher than the medium-sized cities group and more than three times the amount of the larger cities group, which led to a direct impact on the cost-per-sale and absolute sales rates.
367

Matching Pursuit Algorithm Applied to the Evaluation of Click-evoked Otoacoustic Emissions Recorded with Linear and Nonlinear Protocols

Jedzejczak, W. W., Smurzynski, Jacek, Kochanek, Krzysztof, Skarzynski, Henryk 08 June 2009 (has links)
Typically, click-evoked otoacoustic emissions (CEOAEs) are analyzed using fast Fourier transform which has greatly limited time-frequency (t-f) resolution. The purpose of the present study was to process CEOAEs recorded using linear and non-linear presentation modes by applying the Matching Pursuit (MP) method of adaptive approximation which provides a high t-f resolution. The data were recorded in 26 normal-hearing subjects using the ILO96 system with clicks presented at 78-82 dB pSPL. In the non-linear mode, a series of four clicks was delivered with three at the same level and polarity and the fourth three times greater in amplitude and inverted in polarity, whereas in the linear mode all stimuli were presented at the same level and polarity. The responses consisting of 512 data points were stored in two buffers. For each subject, 520 responses were recorded separately for off-line MP analyses. The MP method allowed decomposition of signals into waveforms of defined frequency, latency, time span, and amplitude and also identified patterns of resonance modes that were characteristic for CEOAEs recorded in each individual ear. The overall CEOAE levels were higher by 4 dB for the linear mode than those for the nonlinear method, in agreement with studies reported previously. In general, t-f properties of CEOAEs recorded with linear and non-linear protocols were similar with the exception of the 0-6-ms post-stimulus time window and the frequency range below 2.2 kHz. This part of the signal was contaminated by a stimulus artifact in the linear mode. The reproducibility factor grew faster with an increase of the number of averaged responses for the linear protocol than for the non-linear method. The results suggest that main differences between CEOAEs measured with the two methods are related to stimulus artifacts occurring at the beginning of the recording time-window in the linear mode.
368

COPOLYMÈRES À BLOCS « HYBRIDES » À BASE DE XYLOGLUCANE ET DE POLYMÈRE VINYLIQUE EN COMBINANT MODIFICATION CHIMIO-ENZYMATIQUE ET POLYMÉRISATION RADICALAIRE CONTRÔLÉE

Lohmann, Jérôme 11 June 2009 (has links) (PDF)
Le xyloglucane issu de la graine de tamarin (XG) est un polysaccharide provenant de la biomasse. Son association à un bloc vinylique dans une architecture de copolymères à blocs « hybrides » naturels/synthétique permet d'envisager des applications de par leur auto-assemblage en solution aqueuse. Afin d'obtenir de tels copolymères à blocs, deux stratégies de synthèse sont proposées, basées sur la modification chimio-enzymatique du xyloglucane et la polymérisation radicalaire contrôlée MADIX de monomères vinyliques : acrylamide (Am), acétate de vinyle (AcV), N-vinyl-2-pyrrolidone (NVP). La stratégie « starting from » consiste en la polymérisation radicalaire contrôlée MADIX d'un monomère vinylique à partir de l'oligosaccharide du xyloglucane modifié par une ou plusieurs fonctions polymérisantes. La stratégie « coupling onto » consiste en un couplage par « chimie click » entre un polymère vinylique issu de la polymérisation radicalaire contrôlée MADIX à partir d'un agent de transfert de chaîne porteur d'une fonction azoture, et l'oligosaccharide modifié par une fonction alcyne. Ainsi, quatre familles de copolymères à blocs « hybrides » ont été obtenus (XG-b-PAm, PAm-b-XG-b-PAm, XG-b-PAcV, XG-b-PNVP). Une étude physico-chimique en solution préliminaire des copolymères XG-b-PAcV et XG-b-PNVP a également été réalisée indiquant la formation de polymersomes.
369

Functionalization of poly(epsilon-caprolactone) and its macromolecular engineering

Riva, Raphael 20 April 2007 (has links)
Macromolecular engineering is one of the most powerful tools to control the molecular parameters, including architecture of polymers, and to improve their performances or to impart them new properties. This contribution aims at reporting on a novel strategy for the macromolecular engineering of poly-ε-caprolactone (PCL) which is based on the use of functional ε-caprolactone, the α-chloro-ε-caprolactone (αClεCL). Indeed, αClεCL is a precursor of polymers and copolymers with εCL that bear pendant activated chlorides well suited to grafting from reaction. These (co)polyesters have been used as macroinitiators for the Atom Transfer Radical Polymerization (ATRP) of methyl methacrylate leading to the corresponding graft copolymer. They have also been involved in an Atom Transfer Radical Addition (ATRA) reaction with a series of olefins bearing different functional groups (hydroxyl, carboxylic acid and epoxy group) in order to functionalize the polyester backbone without deleterious degradation. ATRA of PEO chains with an unsaturation end groups has also been carried out in order to prepare PCL-g-PEO of different compositions to be used as stabilizers of polyester nanoparticles. Combination of ring-opening polymerization of ε-caprolactone and the copper-catalyzed Huisgens [3+2] cycloaddition is a novel strategy for going a step further in the macromolecular engineering of poly-ε-caprolactone (PCL). This click reaction is very well-suited to the chemical modification of aliphatic polyesters because, its implementation under very mild conditions prevents chain degradation from occurring. Indeed, alkynes were cycloadded onto azide containing PCL at low temperature (35°C) in an organic solvent (DMF or THF). Originally, α-chloro-ε-caprolactone and ε-caprolactone were randomly copolymerized in toluene at room temperature followed by reaction of the activated chlorides with sodium azide. In order to make a wide range of functional aliphatic polyesters available, poly(α-azide-ε-caprolactone-co-ε-caprolactone) copolyesters were reacted with a series of alkynes substituted by a functional group, e.g., hydroxyl, acrylate and quaternary ammonium salts, This strategy turned out to be efficient to synthesize for instance hydrophilic, photo-cross-linkable and hydrosoluble PCL. Moreover, a variety of graft copolymers were prepared by both the grafting from and the grafting onto techniques. Indeed, an ATRP initiator was attached onto PCL followed by polymerization of vinyl monomers, whereas alkyne endcapped PEO was cycloadded onto azide-containing PCL with formation of amphiphilic PCL-g-PEO copolymers. Last but not least, the click chemistry was very instrumental in imparting an antimicrobial activity to PCL or for the preparation of new functionalized caprolactones.
370

Synthèse de copolymères thermosensibles par polymérisation radicalaire contrôlée RAFT : caractérisation et étude de leur interaction avec des protéines

Ho, The Hien 19 September 2012 (has links) (PDF)
Ce travail de thèse porte sur la synthèse de (co)polymères thermosensibles présentant une fonctionnalité azlactone par polymérisation radicalaire contrôlée RAFT pour l'ancrage de biomolécules. Trois stratégies différentes ont été étudiées. La première stratégie a consisté en la synthèse d'un nouvel agent de transfert permettant d'obtenir des polymères thermosensibles à fonctionnalité azlactone en position . La seconde approche a permis d'introduire la fonctionnalité azlactone en position ω de copolymères thermosensibles via la combinaison de la polymérisation RAFT et de l'addition de Michaël " thiol-ène ". La dernière stratégie a conduit à des copolymères thermosensibles à fonctionnalité azlactone en position latérale par copolymérisation RAFT de la 2-vinyl-4,4-diméthylazlactone avec d'autres monomères. Enfin, la réactivité de ces copolymères thermosensibles pour l'ancrage d'une protéine modèle (lysozyme) a été mise en évidence.

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