Relevant bibliographies by topics / Colonisation de la cellulose / Dissertations / Theses

Dissertations / Theses on the topic 'Colonisation de la cellulose'

To see the other types of publications on this topic, follow the link: Colonisation de la cellulose.
Author: Grafiati
Published: 29 June 2023

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 dissertations / theses for your research on the topic 'Colonisation de la cellulose.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.

1

Géhin, Annick. "Étude de la cellulolyse et de la colonisation de la cellulose par clostridium cellulolyticum ATCC 35319." Nancy 1, 1995. http://www.theses.fr/1995NAN10013.

Full text
Abstract:
L’étude de clostridium cellulolyticum cultivé en dialyse a mis en évidence l'effet inhibiteur des produits du métabolisme sur la croissance de la bactérie ainsi que sur la dégradation de la cellulose. Les études de croissance de clostridium cellulolyticum sur la cellulose a permis de proposer un modèle de colonisation de ce type de substrat. Ce processus consisterait en 4 étapes: adhésion a un site spécifique, colonisation du site, relargage de bactéries carencées en carbone du a la saturation du site d'adhésion, et réadhésion des bactéries a un nouveau site. L’étude de la carence carbonée sur la viabilité et la sporulation de clostridium cellulolyticum a montré que l'état cellulaire des bactéries influait sur le devenir des cellules bactériennes. Ainsi, des cellules carencées en milieu de phase exponentielle de croissance restent viables une longue période puis sporulent. De plus, une corrélation existe entre l'aptitude des bactéries à survivre à une carence et leur capacité à induire une activité protéolytique. Les essais réalisés sur l'adhésion des spores ont mis en évidence qu'elles adhèrent à 90% sur la cellulose et que leur adhésion contrairement à celle des cellules végétatives n'est pas spécifique. De ce fait, la dernière étape du processus de la colonisation d'un substrat cellulosique ne serait pas uniquement la réadhésion des bactéries à un nouveau site mais pourrait consister en une sporulation des bactéries suivie de leur adhésion ou en une mort des cellules bactériennes. Les études de l'effet de la tunicamycine sur le complexe cellulasique de clostridium cellulolyticum ont mis en exergue le rôle primordial d'une protéine de 135 kDa dans l'activité avicelase et dans l'adhésion des cellules à la cellulose
APA, Harvard, Vancouver, ISO, and other styles
2

Gelhaye, Éric. "Étude de l'adhésion et de la colonisation de la cellulose par les clostridia cellulolytiques mésophiles." Nancy 1, 1993. http://www.theses.fr/1993NAN10147.

Full text
Abstract:
L'adhésion des clostridia cellulolytiques mésophiles à la cellulose est un phénomène complexe, mettant en jeu des interactions spécifiques bactérie-cellulose et des interactions bactérie-bactérie qui permettent la formation d'agrégats cellulaires. L'étude de la croissance de clostridium cellulolyticum et de clostridium c401 a permis de proposer un modèle résumant le processus de colonisation de la cellulose par ces micro-organismes. Celui-ci comprendrait 4 étapes: 1) adhésion à un site spécifique; 2) colonisation de la cellulose; 3) relargage de bactéries carencées en carbone du à la saturation du site d'adhésion; 4) réadhésion des bactéries à un nouveau site. L'étude de la régulation par le cellobiose de la colonisation de la cellulose par clostridium c401 a montré que cet effecteur peut intervenir à différents niveaux, notamment sur l'adhésion cellulaire et sur la synthèse des activités cellulasiques
APA, Harvard, Vancouver, ISO, and other styles
3

Ferdinand, Pierre-Henri. "Adhérence et colonisation des fibres de cellulose par la bactérie cellulolytique Clostridium cellulolyticum. : étude du rôle des protéines CipC et HycP." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4729.

Full text
Abstract:
Clostridium cellulolyticum est une bactérie anaérobie stricte et cellulolytique qui produit des complexes multienzymatiques (cellulosomes) très performants pour la dégradation des polysaccharides de la paroi végétale. C. cellulolyticum adhère à la cellulose et ce phénomène intervient dès les premiers stades de croissance. Pour de nombreuses bactéries cellulolytiques, les cellulosomes semblent impliqués dans le processus d'adhérence et alors que les mécanismes moléculaires mis en jeu pour l'adhérence à la cellulose sont connus ou proposés, celui ou ceux de C. cellulolyticum sont inconnus.Mon projet de thèse a consisté à étudier l'adhérence et la colonisation des fibres de cellulose par C. cellulolyticum et d'identifier le ou les facteurs moléculaires impliqués dans l'adhérence. J'ai ainsi mis en œuvre deux stratégies distinctes. D'une part, une approche par mutagénèse aléatoire qui a permis d'isoler deux clones à l'adhérence diminuée et d'autre part, une approche par mutagénèse ciblée visant à inactiver des gènes candidats, susceptibles d'intervenir dans l'adhérence.J'ai aussi étudié la colonisation des fibres de cellulose par C. cellulolyticum et observé que les cellules adhèrent avec une haute spécificité et affinité à la cellulose. La colonisation des fibres se ferait en mono-couche cellulaire et par successions d'événements d'adhésion-relarguage-réadhésion. Un mutant d'inactivation de CipC, la protéine d'échafaudage des cellulosomes, a mis en évidence l'implication de cette protéine dans l'adhérence, mais aussi que l'adhérence à la cellulose pourrait être multifactorielle. Enfin, j'ai étudié le rôle de HycP, une protéine à CBM3 dont la fonction est inconnue
Clostridium cellulolyticum is a strict anaerobe, cellulolytic bacteria. It produces multienzymatic complexes, called cellulosomes, which are able to efficiently degrade the plant cell wall polysaccharides. Cellulolytic bacteria, including C. cellulolyticum do binds to cellulose since early growth stage. For most of the studied cellulolytic bacteria, adherence to cellulose seems to be mediated by their cellulosomes. However, molecular factors involved in C. cellulolyticum adherence to cellulose remain unknown.My Ph.D. aimed to implement different but complementary strategies to study adhesion and colonization of cellulose fibers by C. cellulolyticum and to identify the molecular mechanism(s) by which the bacteria bind to cellulose. In order to identify some proteins encoding genes involved in adhesion, I firstly developed random mutagenesis and isolated two adhesion deficient mutants. I also used a targeted mutagenesis tool to inactivate some candidate genes.My studies highlight C. cellulolyticum adheres with both high specificity and affinity to cellulose. Colonization of cellulose fibers by C. cellulolyticum forms a mono-layer of segregated cells on cellulose surface and may occur through cycles of adhesion-release-re-adhesion to substrate. Inactivation of the CipC encoding gene led to a short decrease of the mutant strain's adherence level. This result suggests some other proteins may be involved in C. cellulolyticum adhesion to cellulose. Finally, I studied HycP, a produced and secreted CBM3 encoding protein of unknown function. HycP is a unique protein among databases and may have a phagic origin
APA, Harvard, Vancouver, ISO, and other styles
4

Badalato, Nelly. "Structure de déchets lignocellulosiques : effets sur la colonisation, les communautés microbienne et les performances de méthanisation, caractérisés par des approches fonctionnelles et haut-débit." Electronic Thesis or Diss., Paris, AgroParisTech, 2014. http://www.theses.fr/2014AGPT0002.

Full text
Abstract:
La méthanisation des composés lignocellulosiques présente un fort intérêt en raison de leur haut potentiel énergétique et de leur abondance, notamment dans les ordures ménagères résiduelles. Toutefois, leur complexité de structure et de composition rend ces matériaux difficilement dégradables en conditions anaérobies et l’utilisation de prétraitements est généralement requise afin d’améliorer leurs rendements de biodégradation. Outre l’effet de ces prétraitements sur la biodégradation de ces composés, la colonisation des lignocelluloses par les micro-organismes cellulolytiques est une étape clé pour l’efficacité de sa dégradation. Dans ce cadre, le travail de thèse a pour objectifs de mieux comprendre le déterminisme de la colonisation de déchets, d’établir le lien entre la colonisation des déchets lignocellulosiques et l'efficacité de leur dégradation et enfin de caractériser plus finement les mécanismes et interactions mises en jeu au sein de la biomasse. Afin de répondre à ces questions, une approche transversale a été développée, combinant des modèles de cultures de souches pures et des systèmes de méthanisation en laboratoire par des communautés complexes. Des approches intégratives ont été appliquées à l’étude de ces systèmes, couplant des analyses haut-débit (métagénomique/(méta)protéomique), un suivi physico-chimique de la biodégradation et des caractérisations physico-chimiques des composés lignocellulosiques étudiés. L’ensemble des résultats met en évidence le rôle des propriétés chimiques, micro-et macro¬structurales des composés lignocellulosiques dans leur récalcitrance, leur performances de dégradation et la réponse du compartiment microbien. La réalisation de la première étude de protéomique totale et quantitative sur la souche pure cellulolytique Clostridium cellulolyticum, modèle des Clostridia cellulolytiques mésophiles, a permis de mettre en évidence que la vitesse maximale de biodégradation du mouchoir en papier est supérieure à celle du coton et que cette dégradation est associée à un profil métabolique particulier, à une colonisation plus rapide et plus étendue et à une modulation quantitative du système cellulasique. D’autre part, une étude sur un système plus réaliste pour l’étude de la méthanisation des déchets lignocellulosiques a confirmé la bonne concordance entre ce système et le système modèle utilisé et a également permis de mettre en évidence les effets substrats sur la structure des communautés microbienne avec la dominance de la classe Bacteroidia en présence de mouchoir en papier et la forte proportion de la classe Spirochaetes en présence de coton. Enfin l’étude des effets de broyages très fins de la paille de blé et du carton plat ont mis en évidence les limites de ces prétraitements sur les performances de leur dégradation, avec l’effet positif modéré du broyage fin de la paille. Ils ont également montré la sensibilité des communautés microbiennes aux changements de surface du substrat, qui se manifeste par l'émergence de communautés parfois différentes en fonction du prétraitement mécanique appliqué. En conclusion, ce travail a permis de traiter sous un angle nouveau les questions liées à la récalcitrance des déchets lignocellulosiques en abordant à la fois les aspects structuraux, écologiques et fonctionnels. Ces résultats alimentent le corps de connaissances fondamentales sur les bioprocédés. Ils confirment que les matériaux lignocellulosiques sont particuliers parmi les déchets non-dangereux et qu’une exploitation plus large de leur potentiel énergétique nécessiterait la mise en œuvre de procédés spécifiquement adaptés
Lignocellulosic materials have a high energy potential and are abundant, especially in municipal solid waste and their methanization is a promising waste-to-energy bioprocess. However, owing to their highly complex and heterogeneous structure, they are recalcitrant to anaerobic conditions and the use of pre-treatments is usually required to improve their biodegradation yields. Besides, lignocellulose colonization by cellulolytic microorganisms is a key step for an efficient biodegradation. In this context, the PhD work aimed to better understand the factors affecting waste colonization, to establish the link between lignocellulosic waste colonization and its biodegradation efficiency and to characterize more precisely the mechanisms and interactions within the biomass. A transversal approach was developed, combining cultures of model pure strains and lab-scale methanization microcosms with a complex biomass. Integrated approaches were applied to these studies, combining high-throughput analyses (metagenomics/(meta) proteomics), physico-chemical monitoring of bioconversion and finally physico-chemical characterization of substrates. The main results highlight the important role of lignocellulosic materials chemical and micro-and macro -structural features for their recalcitrance, their biodegradation efficiency and the response of the microbial compartment. The first global quantitative proteomic study on the cellulolytic model Clostridium cellulolyticum was conducted. Results showed an increased biodegradation rate of the facial tissue compared to cotton. This enhanced biodegradation was associated to a particular metabolic profile, a faster and more extensive colonization and finally a quantitative modulation of the cellulasic system. On the other hand, study of lignocellulosic waste methanization confirmed the good agreement between this more realistic system and the above-described model system. It also provided new information about the effects of substrate on microbial community structure. Noticeably, Bacteroidia members predominated in the presence of tissue and a high proportion of Spirochaetes members was observed in the presence of cotton. Finally, study of the effects of wheat straw and cardboard dry grinding revealed the limitations of these pretreatments on biodegradation efficiency. Main key points were a moderate positive effect of wheat straw fine grinding, and the sensitivity of the microbial communities to substrate surface characteristics, as evidenced by the emergence of different microbial communities according to the applied mechanical pretreatment. In conclusion, this work brings new perspectives to the study of lignocellulosic waste recalcitrance by addressing both the structural, functional and ecological aspects. These results contribute to the core fundamental knowledge on bioprocesses. They confirm that the lignocellulosic materials are specific among non-hazardous waste and require the implementation of adapted specific processes
APA, Harvard, Vancouver, ISO, and other styles
5

Favre-Bonté, Sabine. "Facteurs de pathogenicite bacteriens impliques dans la colonisation du tube digestif par klebsiella pneumoniae." Clermont-Ferrand 1, 1998. http://www.theses.fr/1998CLF1PP04.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Ehlinger, Frédéric. "Fermenteurs a cellules fixees en fermentation methanique : facteurs intervenant dans la colonisation du support, caracterisation des biofilms." Toulouse, INSA, 1988. http://www.theses.fr/1988ISAT0015.

Full text
Abstract:
Etude de l'adherence initiale d'une biomasse methanogene sur un support, en flacons agites, en faisant varier les facteurs du milieu (ph, rapport carbone-azote, calcium exopolymere) afin d'optimiser l'adherence de cette biomasse
APA, Harvard, Vancouver, ISO, and other styles
7

Ehlinger, Frédéric. "Fermenteurs à cellules fixées en fermentation méthanique facteurs intervenant dans la colonisation du support : caractérisation des biofilms /." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb376134530.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Savagner, Pierre. "Etude des mécanismes invasifs de colonisation de l'ébauche thymique par des précurseurs hématopoïétiques chez l'embryon d'oiseau." Paris 6, 1986. http://www.theses.fr/1986PA066530.

Full text
Abstract:
Au cours de l'embryogenèse, l'ébauche thymique est colonisée par des cellules hématopoïétique précurseurs. Leur activation par un peptide et, un contact direct avec la fibronectine et la laminine présentes dans l'environnement thymique ou la membrane basale amniotique parait requise dans cette migration.
APA, Harvard, Vancouver, ISO, and other styles
9

Boulahrouf, Abderrahmane. "La microflore responsable de la degradation des polyosides parietaux dans le gros intestin de la souris et du lapin : etude ecologique, facteurs de la colonisation, effets de la concentration en cellulose du regime, caracterisation des especes et activites in vitro." Clermont-Ferrand 2, 1988. http://www.theses.fr/1988CLF21114.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Boulahrouf, Abderrahmane. "La Microflore responsable de la dégradation des polyosides pariétaux dans la gros intestin de la souris et du lapin étude écologique, facteurs de la colonisation, effets de la concentration en cellulose du régime, caractérisations des espèces et activités in vitro /." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37612194h.

Full text
APA, Harvard, Vancouver, ISO, and other styles
11

Cervin, Nicholas. "Porous Cellulose Materials from Nano Fibrillated Cellulose." Licentiate thesis, KTH, Fiberteknologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-104196.

Full text
Abstract:
In the first part of this work a novel type of low-density, sponge-like material for the separation of mixtures of oil and water has been prepared by vapour deposition of hydrophobic silanes on ultra-porous nanocellulose aerogels. To achieve this, a highly porous (> 99 %) nanocellulose aerogel with high structural flexibility and robustness is first formed by freeze-drying an aqueous dispersion of the nanocellulose. The density, pore size distribution and wetting properties of the aerogel can be tuned by selecting the concentration of the nanocellulose dispersion before freeze-drying. The hydrophobic light-weight aerogels are almost instantly filled with the oil phase when they selectively absorb oil from water, with a capacity to absorb up to 45 times their own weight. The oil can also be drained from the aerogel and the aerogel can then be subjected to a second absorption cycle.In the second part of the work a novel, lightweight and strong porous cellulose material has been prepared by drying aqueous foams stabilized with surface-modified NanoFibrillated Cellulose (NFC). Confocal microscopy and high-speed video imaging show that the long-term stability of the wet foams can be attributed to the octylamine-coated, rod-shaped NFC nanoparticles residing at the air-liquid interface which prevent the air bubbles from collapsing or coalescing. Careful removal of the water yields a porous cellulose-based material with a porosity of 98 % and a density of 30 mg cm-3. These porous cellulose materials have a higher Young’s modulus than other cellulose materials made by freeze drying and a compressive energy absorption of 56 kJ m-3 at 80 % strain. Measurements with an autoporosimeter reveal that most pores are in the range of 300 to 500 μm.

QC 20121107

APA, Harvard, Vancouver, ISO, and other styles
12

Schult, Tove. "Properties of acid sulfite cellulose for cellulose derivatives." Doctoral thesis, Norwegian University of Science and Technology, Department of Chemical Engineering, 2000. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1508.

Full text
APA, Harvard, Vancouver, ISO, and other styles
13

Bellahsene, Tarik Pinon Pierre. "La colonisation en Algérie." Saint-Denis : Université de Paris 8, 2008. http://www.bu.univ-paris8.fr/web/collections/theses/BellahseneThese1.pdf.

Full text
Abstract:
Reproduction de : Thèse de doctorat : Architecture : Paris 8 : 2006.
Titre provenant de l'écran-titre. Le complément de titre connaît plusieurs variantes. Le complément de titre retenu est celui de la thèse imprimée et non celui indiqué sur l'écran-titre : "les cas des centres en Kabylie du Djurdjura, 1857-1899, une illustration de la plaine vers la montagne". Bibliogr. [20] p. en fin du tome I. Notes bibliogr. Lexique.
APA, Harvard, Vancouver, ISO, and other styles
14

Lane, J. M. "Solid state NMR studies of cellulose and cellulose acetate." Thesis, University of East Anglia, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374690.

Full text
APA, Harvard, Vancouver, ISO, and other styles
15

Yang, Han. "Investigation and characterization of oxidized cellulose and cellulose nanofiber films." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=106551.

Full text
Abstract:
Over the last two decades, a large amount of research has focused on natural cellulose fibers, since they are "green" and renewable raw materials. Recently, nanomaterials science has attracted wide attention due to the large surface area and unique properties of nanoparticles. Cellulose certainly is becoming an important material in nanomaterials science, with the increasing demand of environmentally friendly materials.In this work, a novel method of preparing cellulose nanofibers (CNF) is being presented. This method contains up to three oxidation steps: periodate, chlorite and TEMPO (2,2,6,6-tetramethylpiperidinyl-1-oxyl) oxidation. The first two oxidation steps are investigated in the first part of this work. Cellulose pulp was oxidized to various extents by a two step-oxidation with sodium periodate, followed by sodium chlorite. The oxidized products can be separated into three different fractions. The mass ratio and charge content of each fraction were determined. The morphology, size distribution and crystallinity index of each fraction were measured by AFM, DLS and XRD, respectively. In the second part of this work, CNF were prepared and modified under various conditions, including (1) the introduction of various amounts of aldehyde groups onto CNF by periodate oxidation; (2) the carboxyl groups in sodium form on CNF were converted to acid form by treated with an acid type ion-exchange resin; (3) CNF were cross-linked in two different ways by employing adipic dihydrazide (ADH) as cross-linker and water-soluble 1-ethyl-3-[3-(dimethylaminopropyl)] carbodiimide (EDC) as carboxyl-activating agent. Films were fabricated with these modified CNF suspensions by vacuum filtration. The optical, mechanical and thermo-stability properties of these films were investigated by UV-visible spectrometry, tensile test and thermogravimetric analysis (TGA). Water vapor transmission rates (WVTR) and water contact angle (WCA) of these films were also studied.
Au cours des deux dernières décennies, une grande quantité de recherches ont portées sur les fibres de cellulose naturels, car ils sont «verts» et de matières premières renouvelables. Récemment, la science des nanomatériaux a attiré l'attention en raison de la gamme grande surface et les propriétés uniques des nanoparticules. La cellulose est en train de devenir un matériau important dans la science des nanomatériaux, à la demande croissante de matériaux écologiques. Dans ce travail, un nouveau procédé de préparation de cellulose nanofibres (CNF) est présenté. Cette méthode contient un maximum de trois étapes d'oxydation: oxydations au periodate, au chlorite et au TEMPO (2,2,6,6-tétraméthylpipéridinyle-1-oxyle). Les deux premières étapes d'oxydation sont étudiées dans la première partie de ce travail. La pâte de cellulose a été oxydée à des degrés divers par un à deux étapes d'oxydation au periodate de sodium, suivi par le chlorite de sodium. Les produits oxydés peuvent être séparés en trois fractions différentes. Le ratio de la masse et le contenu de charge de chaque fraction ont été déterminés. La morphologie, la distribution de la taille et l'indice de cristallinité de chaque fraction ont été mesurés par l'AFM, DLS et XRD, respectivement. Dans la seconde partie de ce travail, des CNF ont été préparés et modifiés dans diverses conditions, y compris (1) l'introduction de diverses quantités de groupes aldéhyde sur les CNF par oxydation au periodate, (2) les groupes carboxyle sous forme de sodium sur les CNF ont été convertis à leur forme acide par traitement avec un type d'acide résine échangeuse d'ions; (3) ces CNF ont été réticulés de deux manières différentes en employant dihydrazide adipique (ADH) en tant que cross-linker et soluble dans l'eau 1-éthyl-3-[3- (diméthylaminopropyl)] carbodiimide (EDC) comme agent activateur de carboxyle. Les films ont été fabriqués avec ces suspensions de CNF modifiés par filtration sous vide. Les propriétés optiques, mécaniques et la thermo-stabilité de ces films ont été étudiées par spectrométrie UV-visible, essai de traction et de l'analyse thermogravimétrique (TGA). Les taux de transmission de vapeur d'eau (WVTR) et l'angle de contact de l'eau (WCA) de ces films ont également été étudiés.
APA, Harvard, Vancouver, ISO, and other styles
16

Déry, Steve. "La colonisation agricole au Vietnam." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0016/NQ48535.pdf.

Full text
APA, Harvard, Vancouver, ISO, and other styles
17

Inglis, Timothy J. J. "Colonisation of the ventilated airway." Thesis, University of Southampton, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259486.

Full text
APA, Harvard, Vancouver, ISO, and other styles
18

El-Turabi, Mohammed El Hassan. "The reactions of cellulose and modified cellulose with amide/formaldehyde resins." Thesis, University of Leeds, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329190.

Full text
APA, Harvard, Vancouver, ISO, and other styles
19

Arca, Hale Cigdem. "Cellulose Esters and Cellulose Ether Esters for Oral Drug Delivery Systems." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/82920.

Full text
Abstract:
Amorphous solid dispersion (ASD) is a popular method to increase drug solubility and consequently poor drug bioavailability. Cellulose ω-carboxyesters were designed and synthesized specifically for ASD preparations in Edgar lab that can meet the ASD expectations such as high Tg, recrystallization prevention and pH-triggered release due to the free -COOH groups. Rifampicin (Rif), Ritonavir (Rit), Efavirenz (Efa), Etravirine (Etra) and Quercetin (Que) cellulose ester ASDs were investigated in order to increase drug solubility, prevent release at low pH and controlled release of the drug at small intestine pH that can improve drug bioavailability, decrease needed drug content and medication price to make it affordable in third world countries, and extent pill efficiency period to improve patient quality of life and adherence to the treatment schedule. The studies were compared with cellulose based commercial polymers to prove the impact of the investigation and potential for the application. Furthermore, the in vitro results obtained were further supported by in vivo studies to prove the significant increase in bioavailability and show the extended release. The need of new cellulose derivatives for ASD applications extended the research area, the design and synthesis of a new class of polymers, alkyl cellulose ω-carboxyesters for ASD formulations investigated and the efficiency of the polymers were summarized to show that they have the anticipated properties. The polymers were synthesized by the reaction of commercial cellulose alkyl ethers with benzyl ester protected, monofunctional hydrocarbon chain acid chlorides, followed by removal of protecting group using palladium hydroxide catalyzed hydrogenolysis to form the alkyl cellulose wcarboxyalkanoate. Having been tested for ASD preparation, it was proven that the polymers were efficient in maintaining the drug in amorphous solid state, release the drug at neutral pH and prevent the recrystallization for hours, as predicted.
Ph. D.
APA, Harvard, Vancouver, ISO, and other styles
20

Pichon, Denis. "Analyse d'images en biotechnologie : quantification de la morphologie de micro-organismes filamenteux au cours de fermentation et suivi de croissance de cellules animales sur microporteurs." Vandoeuvre-les-Nancy, INPL, 1993. http://www.theses.fr/1993INPL146N.

Full text
Abstract:
Les procédés biotechnologiques mettant en œuvre les micro-organismes ou les cellules en général ont souvent recours à l'observation microscopique pour acquérir des informations concernant la morphologie ou le nombre de cellules. C'est notamment le cas des micro-organismes filamenteux dont la morphologie est très complexe et des cellules animales qui croissent sur des microporteurs. Un moyen sur de quantifier les observations microscopiques est l'analyse quantitative d'images. Nous avons utilisé l'analyse d'images pour caractériser les différentes populations morphologiques de micro-organismes filamenteux. Un critère permettant de déterminer leur degré d'enchevêtrement a été mis au point. Deux grandes familles morphologiques sont reconnues: les pelotes et les mycelia libres appelés non-pelotes. Une classification basée sur le critère d'enchevêtrement des non-pelotes permet d'obtenir trois classes d'individus: les filaments, les entrecroisements et les enchevêtrements. Nous avons réalisé le suivi de l'évolution des différentes formes citées ci-dessus au cours de fermentations de streptomyces ambofaciens produisant ou non un antibiotique: la spiramycine. Nous avons remarqué que la phase de production de ce produit est contemporaine de modifications morphologiques certaines. D'autre part, l'analyse d'images a permis de quantifier le processus de colonisation de microporteurs servant de support à la croissance de cellules animales en culture en réacteurs agités. Nous avons montré que les microporteurs de taille moyenne (163 et 183 um) étaient les plus représentatifs de la croissance globale. L'analyse d'images est un outil performant qui a montré ses possibilités dans ces deux applications. Des extensions pour son application en ligne sont proposées
APA, Harvard, Vancouver, ISO, and other styles
21

Poncelet, Marc. "Sciences sociales, colonisation et développement : une histoire sociale du siècle d'africanisme belge." Lille 1, 1995. http://www.theses.fr/1995LIL12005.

Full text
Abstract:
Le champ belge des etudes en developpement est l'heritier direct des sciences coloniales, institution savante tres specifique du royaume, institution nee de et autour de l'unique colonie : le congo. Colonie capitaliste par excellence, celui-ci fut investi d'emblee du schema du developpement. C'est autour de ce dernier que s'organiserent les infrastructures savantes propres a l'outre mer, que s'accumula le patrimoine africaniste. Mettre ces connaissances en perspective ainsi que les aleas de leur legitimite et leur perilleuse reconversion requiert principalement l'explication sociologique des procedures etablies et socialisees de production d'une "science congolaise en metropole" selon des axes disciplinaires, ideologiques et institutionnels
The belgian development studies are rightful heir to colonial social sciences. This scientific institution is born and grow up with the lonely colony : the belgian congo. Capitalist in the higher sense of the word, congo has been immediately perceived under development scheme. Throughout this concept was built scholar institutions specially dedicated to aversea and the african scientific patrimony. An outlook of the knowledge, of his legitimacy process, of this perilous redeployment need a sociological explanation of established and socialized proceedings and dealings of production of congolese science in the mother country following the greatest kinds of instituted knowledge, ideologies and scholar institutions
APA, Harvard, Vancouver, ISO, and other styles
22

Richards, Luke. "Pneumococcal colonisation models of the nasopharynx : the role of virulence factors and host immunity during colonisation." Thesis, University of Leicester, 2011. http://hdl.handle.net/2381/9411.

Full text
Abstract:
The human nasopharynx is the most important ecological niche for Streptococcus pneumoniae and the establishment of nasopharyngeal carriage is an essential pre-requisite to invasive pneumococcal disease. Virulence factors which mediate long term carriage and the immunogenicity of individual bacterial components are of interest to the development of vaccines which currently fall short of protecting against >90 known serotypes of pneumococci. This thesis contains a long term mouse model of nasopharyngeal carriage conducted in outbred mice, using both wild type and attenuated isogenic mutant pneumococcal strains. Whilst serotype-2 (D39) and serotype-3 (A66) pneumococci were carried asymptomatically in the nasopharynx for at least 21 days, mutants that lacked neuraminidases, PspA and pneumolysin were cleared from the nasopharynx <14 days. Both the carriage of WT-D39 and the clearance of the pneumolysin negative (PlnA-) were associated with the generation of serum IgM anti-capsular antibody, and IgG anti-PspA, which correlated to bacterial numbers in the nasopharynx. Carriage also stimulated anti-capsular IgA in the cervical lymph nodes, and a local macrophage cellular response. Using attenuated carriage it was possible to model the effects of subsequent exposure to pneumococci, in the form of future carriage events and invasive disease. Prior colonisation significantly shortened the duration of carriage from >28 days to <14 days within the same serotype however, both the polysaccharide capsule and conserved protein antigens contribute to protection. Colonisation could also protect mice from a normally fatal invasive challenge with both D39 and A66. Immune sera alone from previously colonised mice was able to delay onset of fatal pneumonia, however the presence of both PspA and capsule antigens were not indispensible to the protection in this instance. Taken together, the results in this thesis support existing data about the immunogenicity of capsule and conserved proteins which may inform the creation of novel and more efficacious pneumococcal vaccines.
APA, Harvard, Vancouver, ISO, and other styles
23

Picard, Aleth. "Villes et colonisation : Algérie : 1830-1870." Université Paris-Est Créteil Val de Marne (UPEC), 1987. http://www.theses.fr/1987PA120062.

Full text
Abstract:
La colonisation de l'algerie par la france au debut du xixeme siecle se traduit, quant a l'amenagement du territoire, par des travaux de transformation des villes existantes et par la fondation de centres de colonisation et de villages agricoles. Le reseau de villes, mis en oeuvre par les ingenieurs du genie (service responsable de l'ensemble des travaux civils et militaires), constitue un corpus d'une vingtaine de villes. Ce travail presente une analyse annee par annee des projets a partir des archives du genie de vincennes. La lecture des plans et des apostilles des ingenieurs militaires nous renseigne tant sur les methodes de travail de ce corps que sur la conception de la ville au xixeme siecle et le fait colonial lui meme. Ces realisations, quoique tres differentes, prefigurent deja les travaux haussmanniens de paris et des principales villes de france et les interventions, bien plus tardives, sur les villes des protectorats et des colonies francaises du debut du xxeme siecle
French colonisation in algeria at the begining of the ninetheenth century resulted, as far as national developpement is concerned, in convention works of existing towns and in the creation of settlements and agricultural villages. The towns network, set up by the military engineerin (service responsable for all the civil and military works) consists in an about twenty towns corpus. This work presents a project's analysis year after year based on vincennes military engineering archives. Plans and apostils reading of military engineers provides information on this body's working methods as well as on the urban design ine the ninetheenth century and on colonial matter. Although they are quite different, these projects announce already haussmann's works in paris and in the main french towns as welle as the operations made much later on french protectorates and colonies at the begining of twentieth century
APA, Harvard, Vancouver, ISO, and other styles
24

Lara, Oruno Denis. "Caraïbes en construction : espace, colonisation, résistance." Nice, 1991. http://www.theses.fr/1991NICE2011.

Full text
Abstract:
Histoire des Caraïbes. Espace insulaire et continental. Préhistoire et protohistoire. Conquêtes et rupture. Résistance des Karibs. Pillage, traite négrière et système esclavagiste. Destruction du système colonial à partir de 1791 (Saint-Domingue). Abolition de l'esclavage dans les colonies britanniques et françaises. Lutte armée à Cuba (1895-1898). Économie et dépendance au XXe siècle. Dictatures. L'espace de Marcus Garvey. Les Caraïbes en guerre. La révolution cubaine. Fédération des West Indies. Black power. Crise économique et endettement. Les amérindiens. L'engrenage du sous-développement. La mer en héritages
History of the Caribbean. Islands and continental space. Prehistory and protohistory. Conquest and breaks. Karib resistance. Robbery, slave trade and slave system. Destruction of the colonial system since 1791 (Santo Domingo). Abolition of slavery in the british and french colonies. Armed struggle in Cuba (1895-1898). Economics and dependance during the XXth century. Dictatures. Marcus Garvey's area. The Caribbean in the IId world war. The cuban revolution. Federation of the West Indies. Black power. Economic crisis. Amerindians. Under-development. The legacy of the sea
APA, Harvard, Vancouver, ISO, and other styles
25

Wong, En En Hazel. "Host epithelial responses to Neisserial colonisation." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/6045.

Full text
Abstract:
Neisseria meningitidis is a bacterium that colonises the human nasopharyngeal mucosal surface. Occasionally, it can migrate from the nasopharynx to cause potentially lifethreatening meningitis and septicaemia. In contrast, closely related bacteria such as Neisseria lactamica, colonise the nasopharynx but do not cause invasive disease. Interaction differences between N. meningitidis and N. lactamica with the human host at the colonisation stage are poorly defined. I hypothesise that early interactions of N. meningitidis and N. lactamica with respiratory epithelial cells are associated with differential host cell responses, and that these may be capable of altering the outcome of the interaction. Experiments were undertaken to describe the interactions of N. meningitidis and N. lactamica with a human bronchial epithelial cell line. Association and invasion studies indicated a similar extent of association and invasion of N. meningitidis and N. lactamica. Human epithelial gene expression profiles in response to N. meningitidis and N. lactamica were determined using a genome wide microarray platform. Comparison of live and dead bacteria enabled the identification of host responses specifically to live Neisseria while comparison of the N. meningitidis capand pilE- mutants allowed the identification of host responses to non-capsule and pili factors, such as secreted proteins. Selected genes were further verified at the transcript and protein level. Host metabolic and energy production processes were associated with both neisserial species, suggesting that both N. meningitidis and N. lactamica utilise host resources for energy. In contrast, the data indicated that while N. meningitidis down-regulates host defence genes, N. lactamica initiates a proinflammatory response, suggesting specific colonisation processes that may lead to different clinical outcomes. Treatment of the epithelial cells with neisserial secreted proteins showed that they may be directing some of these differential responses, suggesting novel mechanisms for modulation of the host response.
APA, Harvard, Vancouver, ISO, and other styles
26

D'Amour, Roger. "Modèle réactionnel de la dépolymérisation hydrolytique de la cellulose en cellulose microcristalline." Mémoire, Université de Sherbrooke, 2001. http://savoirs.usherbrooke.ca/handle/11143/1152.

Full text
Abstract:
Cette étude s'inscrit dans une vision globale de valorisation de la biomasse. Concrètement, le Groupe de Recherche sur les Technologies et Procédés de Conversion du département de génie chimique de l'Université de Sherbrooke mise sur la conversion d'hydrates de carbone en sucres fermentescibles aux fins de production de bio éthanol. Ce mémoire est axé sur la conversion de la cellulose en ses unités constitutives, soient les micro cristallites et puis le monomère de glucose. Les mécanismes moyennant lesquels la cellulose se transforme progressivement englobent des transformations structurelles suivant des cinétiques complexes caractéristiques de systèmes non-homogènes. Lors de l'hydrolyse, la cellulose subit une dépolymérisation progressive entraînant l'élimination des zones amorphes et l'obtention des cristallites (ou micro cristallites) constitutifs. Ces derniers sont très compacts et extrêmement résistants à la solvatation et la pénétration d'eau, étape incontournable pour effectuer l'hydrolyse. Des essais de gonflement de la cellulose par des solvants (acétone, éthylène glycol), ainsi que par cisaillement, n'ont pas réussi, dans les conditions de travail utilisées, à déstructurer les cristallites. Ce mémoire présente une modélisation de type phénoménologique pour la dépolymérisation. Développée à partir de considérations structurelles, la modélisation est basée sur un paramètre de sévérité qui introduit la température, le temps et l'action catalytique. La concordance entre les résultats expérimentaux obtenus dans différents réacteurs permet de conclure que la dépolymérisation de la cellulose pourra désormais être couplée avec une nouvelle approche issue de ces travaux.
APA, Harvard, Vancouver, ISO, and other styles
27

D'Amour, Roger. "Modèle réactionnel de la dépolymérisation hydrolytique de la cellulose en cellulose microcristalline." Sherbrooke : Université de Sherbrooke, 2001.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
28

Fischer, Martin. "Polymeranaloge Carbanilierung von Cellulose." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2004. http://nbn-resolving.de/urn:nbn:de:swb:14-1106412216968-39405.

Full text
Abstract:
Characterization of cellulose by its molecular weight distribution is afforded after polymeranalogeous dissolution. Additionally, a molecular dispersion of the polymer is a prerequisite. Common processes are dissolution of cellulose in dimethylacetamide-lithiumchloride, nitration and carbanilation. Degradation of the polysaccharide chains can occur in each of the mentioned processes. It is shown that degradation in pyridine occurs via beta-elimination at carbonyl groups along the cellulose chains. Carbanilierung in DMSO is much more pronounced. It comprises oxidation along the Pfitzner-Moffatt-mechanism and subsequent beta-elimination at the thus formed carbonyl-groups. This was elucidated with model systems and by investigation of the carbanilation in different media. Carbonyl groups of cellulose are masked through reaction with phenylisocyanate. This was shown with model. Therefore, the determination of carbonyl groups in cellulose-tricarbanilates is not possible. The separation of low-molecular weight byproducts was optimised. The influence of pretreatment and preactivation of cellulose-samples on the completeness of the conversion was studied. A standard protocol for the carbanilation of cellulose is provided
Cellulose wird u.a. durch ihre Molmassenverteilung charakterisiert, deren Ermittlung ein polymeranaloges Verfahren zur molekulardispersen Auflösung des Polymers erfordert. Hierfür sind die Direktlösung, die Nitrierung und die Carbanilierung in Gebrauch. Bei allen Prozessen kann es zum Abbau der Polysaccharidketten kommen, wobei diesen Prozessen wenig Beachtung geschenkt wurde. In der Arbeit wird gezeigt, daß der Abbau bei der Carbanilierung in Pyridin durch Beta-Eliminierung an vorhandenen Carbonylgruppen erfolgt. Die Carbanilierung in DMSO fällt stets stärker aus als bei Einsatz von Pyridin und umfasst die Prozesse Oxidation nach dem Pfitzner-Moffatt-Mechanismus und anschließende Beta-Eliminierung an den neu gebildeten Carbonylgruppen. Dies wird durch Untersuchungen an Modellsystemen und am Polymer herausgearbeitet. Carbonylgruppen an Cellulose werden durch die Umsetzung mit Phenylisocyanat maskiert, was an Modellverbindungen gezeigt wurde (Bildung von Endioldicarbanilaten und carbanilierten Halbacetalen). Ihre Bestimmung in Cellulosecarbanilaten ist daher nicht möglich. Die Abtrennung von niedermolekularen Nebenprodukten der Umsetzung wurde optimiert. Der Einfluss der Vorbehandlung und Voraktivierung von Celluloseproben auf die Vollständigkeit der Umsetzung wurde eingehend untersucht. Es wird ein Standardverfahren zur Carbanilierung von Cellulose angegeben
APA, Harvard, Vancouver, ISO, and other styles
29

Helle, Steve. "Biosurfactants & cellulose hydrolysis." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61308.

Full text
Abstract:
The action of many antimicrobial agents is dependent on their ability to interact with biological membranes. A group of polypeptide antibiotics was found to have surface activite properties. One of them, gramicidinS, produced a minimum in the surface tension curve, which was attributed to instabilities in the intra-molecular hydrogen bonds. Biosurfactants were found to have a great effect on the two phase hydrolysis of cellulose by cellulase. Seven times as much sugar was produced by the hydrolysis of Sigmacell 100 when the biosurfactant sophorolipid was present. The surfactant affects the adsorption of cellulase onto cellulose, and prevents the cellulase from binding irreversibly to the cellulose and becoming inactive.
APA, Harvard, Vancouver, ISO, and other styles
30

Symington, Mark C. "Cellulose based composite materials." Thesis, University of Strathclyde, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501684.

Full text
Abstract:
Natural fibre composites are a fast growing research area, with many observable research branches. In this thesis, studies into natural fibre composites are undertaken. This includes work into the base fibre mechanical properties, pre-processing techniques and the influence of alkalisation and silanation, both common fibre processing methods used to improve interfacial properties. The effects of these pre-processing techniques were also evaluated using Fourier transform infrared spectroscopy (FT-IR). It was observed that the processing had shown definite signs of altering the surface functional groups. For the studies into the base fibre strengths, it was found that natural fibres are highly variable. with the testing complicated by difficulties in measuring cross sectional areas. It was also found that natural fibres are sensitive to moisture, which affects their mechanical properties somewhat, although no conclusive trends were derived.
APA, Harvard, Vancouver, ISO, and other styles
31

Gandhi, U. P. "Diffusion in cellulose derivatives." Thesis, Cardiff University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376555.

Full text
APA, Harvard, Vancouver, ISO, and other styles
32

Mao, Rui. "Mechanics of cellulose nanopapers." Thesis, Queen Mary, University of London, 2017. http://qmro.qmul.ac.uk/xmlui/handle/123456789/24706.

Full text
Abstract:
Cellulose nanopaper is a fibrous network composed of cellulose nanofibres connected by hydrogen bonds, which shows pronounced mechanical and physical properties. This thesis investigates the mechanics of cellulose nanopaper from various aspects. First, the fracture properties of cellulose nanopaper were investigated using experimental and modelling approaches. It was found that the fracture strength of notched nanopaper is insensitive to notch length. Cohesive zone models were used to describe the fracture behaviour of notched cellulose nanopaper. Fracture energy was extracted from the cohesive zone models and divided into an energy component consumed by damage in materials and a component related to pull-out and bridging of nanofibres between cracked surfaces which is not facilitated by short nanofibres in nanopaper. Strain mapping revealed a small region of highly localized strain ahead of the notch tip with multiple stress concentration sites which are indicative of a stress delocalization mechanism. Secondly the inelastic deformation mechanisms of cellulose nanopaper were investigated. Results indicate that the inelastic deformation of cellulose nanopaper does not originate from fibre slippage and shearing as often suggested in literature but originates from inelastic deformation in amorphous regions in the cellulose nanofibres itself. It is proposed that this mechanism is associated with segmental motion of cellulose molecules facilitated by the breakage of hydrogen bonds within these amorphous regions. Thirdly, the effect of preparation methods on the mechanical properties of cellulose nanopaper was investigated. The influence of processing parameters such as compaction pressure and temperature was investigated and the mechanical properties of these nanopapers were compared with nanopaper prepared by a suspension casting method. Finally, a micromechanical fibrous network model was used to investigate the parameters that determine the elastic modulus of cellulose nanopaper. The effect of fibre size, waviness and modulus, inter-fibre bond density as well as network density on elastic modulus was investigated.
APA, Harvard, Vancouver, ISO, and other styles
33

Joubert, Fanny. "Chemically modified hydroxyethyl cellulose." Thesis, Durham University, 2014. http://etheses.dur.ac.uk/11122/.

Full text
Abstract:
Synthetic, man-made polymers are produced from petroleum, however this activity may well decrease as a function of time because of the non-renewability of the oil. This will result in the decreased production of synthetic polymers with consequent problems to our everyday life because of their ubiquity (food, furniture, containers, electronics…). An alternative could be the use of biopolymers such as cellulose, starch, proteins, amylose and chitin which are extracted from renewable sources. Cellulose is the most abundant biopolymer on earth and is principally found in the cell walls of plants. Cellulose presents interesting properties such as a high thermal stability and high strength, however the principal drawback is its insolubility in both organic and aqueous solvents limiting considerably its use in industry. Chemical modification of the hydroxyl groups of cellulose overcomes some of this problem. In fact, hydroxyethyl cellulose (HEC), where the hydroxyl groups have been modified with ethylene oxide, shows good solubility in aqueous solvents (dimethyl sulfoxide, water) due to the interruption of the cellulose H-bonding networks. Although the chemical modification of cellulose has improved considerably the physical properties of cellulose, the derivatives are usually not competitive against synthetic polymers. Due to its solubility and the presence of the three hydroxyl groups, HEC was chosen as a substrate for chemical modification, with the aim of mimicking the properties of synthetic polymers. The synthetic polymer of reference in our work was poly(N-vinylpyrrolidone) (PVP) because of its solubility in organic and aqueous solvents and sorption properties. The introduction of lactam groups onto HEC could produce a material with properties similar to PVP and this was the goal of our work. Three methods for modifying HEC with lactam groups are reported. The first was the functionalization of HEC with 1-(hydroxymethyl)-2-pyrrolidone (HMP) with degrees of functionalization up to ~0.9 on the primary alcohol functionality of HEC. The functionalized HECs showed markedly different properties to unfunctionalized HEC, such as increased the thermal stability and reduced viscosity. The two others methods led to the preparation of well-defined HEC-g-PVPs using a “grafting from” strategy combined with Atom Transfer Radical Polymerisation (ATRP) and “grafting to” combined with Reversible Addition-Fragmentation Chain-Transfer (RAFT) polymerisation. The ATRP of N-vinylpyrrolidone (NVP) from a prior-synthesised macro-initiator, Br-HEC, did not work efficiently; however, RAFT polymerisation of NVP using an alkyne-terminated xanthate as transfer agent produced an 80% monomer conversion with a 1.4 ƉM. The alkyne-terminated PVP was coupled successfully to partially 15N-labelled N3-HEC and the copper-catalyzed azide-alkyne cycloaddition (CuAAC) was confirmed by 15N NMR spectroscopy. The versatility of the method was demonstrated using poly(N-isopropyl acrylamide) (PNIPAAM) which was synthesised using an alkyne-terminated trithiocarbonate as transfer agent with a 90% monomer conversion and a 1.2 ƉM. Subsequently, this straightforward method was used to prepare anti-microbial graft-copolymers of HEC from an ionic liquid (IL) monomer, 1-(11-acryloyloxyundecyl)-3-methylimidazolium bromide which was polymerised in high monomer conversion (70-80%) with some evidence of control over molecular weight distribution (ƉM =1.5). The influence of the chain length of the grafts on the antibacterial effects was minor with a 20 and 39 µg/mL minimum inhibition concentration (MIC) for E. coli and for S. aureus respectively. The MICs were comparable to those measured for ampicillin, which is known as an antibiotic, indicating the strong effect of our HEC-g-P(IL) on bacteria.
APA, Harvard, Vancouver, ISO, and other styles
34

Wilsby, Astrid. "Insight in cellulose degradation." Thesis, KTH, Fiber- och polymerteknologi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-302670.

Full text
Abstract:
I strävan efter att minska textilindustrins omfattande miljöpåverkan utvecklas nya metoder för textilåtervinning. Idag återvinns bomullstyg av Renewcell på deras anläggning i Kristinehamn. Den återvunna produkten, Circulose®, är en dissolvingmassa som kan användas för att spinna nya viskosfibrer som man i sin tur kan använda för att göra nya kläder. Föreliggande arbete är en förstudie om möjligheten att optimera Renewcellls återvinningsprocess. Arbetet inkluderar en optimering av massaprocessen vilket resulterar i en mer effektiv process som minskar förbrukningen av processkemikalier.
To reduce the extensive environmental impact of the textile industry, new methods for textile recycling are being developed. Today, cotton-based fabric is recycled by Renewcell at their facility in Kristinehamn. The recycled product, Circulose®, is a dissolving pulp that can be used to spin new viscose fibers, which in turn can be used to make new clothes. The present work is a feasibility study on the possibility of optimizing Renewcell's recycling process. The work includes an optimization of the pulp process, which results in a more efficient process with a reduced consumption of process chemicals.
APA, Harvard, Vancouver, ISO, and other styles
35

de, Mourgues Marius. "Composite Cellulose Nanofibrils Filaments." Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-277919.

Full text
Abstract:
Biodegradable polymers are emerging as a new solution to satisfy the increasing demand of greenenvironmentally friendly material. At the same time, the interest for lighter and stronger structures never stops growing. In this paper, we report the production steps to achieve cellulose nanofibrils (CNF) composite filaments via a new green synthesis route known as wet spinning. This new technique avoids the traditional harmful viscose process and produces biodegradable CNF filaments with interesting mechanical properties. This approach is then applied to produce never seen before composite CNF filaments using a three-layered head extruder. In order to obtain conductive filaments, PEDOT/PPS is successfully mixed with CNF to produce in-situ composite filaments. Scanning electron microscopy (SEM), atomic force measurements and tensile tests are employed to characterize the properties of the filaments.
Biologiskt nedbrytbara polymerer börjar framträda som en lösning för det ökade behovet avmiljövänliga material. Samtidigt så växer intresset för lättare och starkare strukturer. I denna rapport tar vi upp produktionsstegen för att uppnå nanofibril komposit cellulosa fibrer (CNF), med hjälp av en ny grön polymerisation mest känd som ”wet spinning”. Med denna nya teknik så behövs inte dem traditionella miljöfarliga viskosprocesserna och man producerar biologiskt nedbrytbara CNF filaments med intressanta mekaniska egenskaper. Denna metod appliceras sen för att producera en komposit som aldrig setts innan. CNF fibrer som består av tre lager ”head-extruder”. För att få fibrer med ledningsförmåga så mixas PEDOT/PPS med CNF för att producera ”in-situ komposit fibrer”. Svepelektronmikroskop (SEM), atomkraftsmikroskopi och töjningstester används för att karaktärisera egenskaperna av fibrerna.
APA, Harvard, Vancouver, ISO, and other styles
36

Pillai, Karthik. "Bio-inspired Cellulose Nanocomposites." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/28575.

Full text
Abstract:
Natural composites like wood are scale-integrated structures that range from molecular to the macroscopic scale. Inspired by this design, layer-by-layer (LbL) deposition technique was used to create lignocellulosic composites from isolated wood polymers namely cellulose and lignin, with a lamellar architecture. In the first phase of the study, adsorption of alkali lignin onto cationic surfaces was investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D). Complete coverage of the cationic surface with alkali lignin occured at low solution concentration; large affinity coefficients were calculated for this system at differing pH levels. Adsorption studies with organosolv lignin in an organic solvent, and spectroscopic analysis of mixtures of cationic polymer with alkali lignin revealed a non-covalent interaction. The work demonstrated how noncovalent interactions could be exploited to molecular organize thin polyphenolic biopolymers on cationic surfaces. The second phase of the study examined the adsorption steps during the LbL assembly process to create novel lignocellulosic composites. LbL assembly was carried out using oxidized nanocellulose (NC) and lignin, along with a cationic polymer poly(diallyldimethylammonium chloride) (PDDA). QCM-D was used to follow the sequential adsorption process of the three different polymers. Two viscoelastic models, namely Johannsmann and Voigt, were respectively used to calculate the areal mass and thickness of the adsorbed layers. Atomic force microscopy studies showed a complete coverage of the surface with lignin in all the disposition cycles, however, surface coverage with NC was seen to increase with the number of layers. Free-standing composite films were obtained when the LbL process was carried out for 250 deposition cycles (500 bilayers) on a cellulose acetate substrate, following the dissolution of the substrate in acetone. Scanning electron microscopy of the cryo-fractured cross-sections showed a lamellar structure, and the thickness per adsorption cycle was estimated to be 17 nm. The third phase of the study investigated the effect of LbL ordering of the polymers versus a cast film composed of a blended mixture of the polymers, using dynamic mechanical analysis. A tan ï ¤ peak was observed in the 30 â 40 ºC region for both films, which was observed in the neat NC film. Heating of the samples under a compressive force produced opposite effects in the films, as the LbL films exhibited swelling, whereas the cast films showed densification. The apparent activation energy of this transition (65 â 80 kJ mol-1) in cast films, calculated based on the Arrhenius equation was found to be coincident to those reported for the ï ¢ transition of amorphous cellulose. The peak was seen to disappear in case of LbL films in the second heat, whereas it was recurring in case of cast films of the blended mixture, and neat NC films. Altogether, the together the work details a novel path to integrate an organized lignin and cellulose molecular structure, albeit modified from their native form, into a three-dimensional composite material.
Ph. D.
APA, Harvard, Vancouver, ISO, and other styles
37

Liang, Jiarong. "Cellulose oxalates in biocomposites." Thesis, KTH, Fiber- och polymerteknologi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-297506.

Full text
Abstract:
Under de senaste åren, på grund av överanvändningen av icke förnybara resurser har den ekologiska miljön på jorden påverkats allvarligt. I takt med detta ökade oron bland människor om att resurserna skulle ta slut. Därför är det nödvändigt att utveckla och använda mer miljövänliga förnybara resurser. Ett av dessa alternativ är cellulosabaserat material, vilket är ett utmärkt val. Vanligtvis består cellulosabaserat material av ett förstärkande material (cellulosafiber) och en matris (polymer eller metall). Dock bör kompatibiliteten mellan cellulosamaterialet och polymermatrisen ses över, eftersom generellt är kompatibiliteten mellan de låg. I detta projekt studerades olika metoder för att förbättra kompatibiliteten mellan cellulosamaterialet och polymermatrisen. Två cellulosamaterial (mikrokristallin cellulosa (MCC) och cellulosaoxalat (COX)) behandlades med olika modifieringsmetoder för att förbättra kompatibiliteten och gränssnittsinteraktionen mellan materialen. För att modifiera MCC och COX användes bland annat kulmalning, vatten som dispergeringsmedel, förestring av cellulosafibrerna med oljesyra under olika reaktionstider (6, 18, respektive 48 timmar), samt att tillsätta ett kompatibiliseringsmedel, maleinsyraanhydrid-ympad polypropylen (MAPP), i olika halter (1% respektive 2%). För att framställa kompositproverna användes extrudering och formsprutning. Dragprovning genomfördes för att testa de mekaniska egenskaperna hos proverna. Ytterligare karakteriseringsanalyser som utfördes på de olika cellulosapulvren var kontaktvinkeln (CA), svepelektronmikroskopi (SEM), infrarödspektroskopi (FTIR), och röntgendiffraktion (XRD). Resultatet från dragprovningen visade att COX-proverna med 1% MAPP som kompatibilisator gav den högsta draghållfastheten och Youngs modul av alla kompositproverna som producerades i detta exjobb. Användningen av MAPP som kompatibiliseringsmedel visade ett bättre resultat än de andra undersökta metoderna för att förbättra kompatibiliteten mellan den hydrofila ytan på MCC/COX och den hydrofoba ytan på polymermatrisen. Att använda MAPP som kompatibilisator bör prioriteras vid tillverkningen av kompositmaterial.
In recent years, with the excessive use of non-renewable resources on the earth, the ecological environment has been seriously affected. At the same time, humans began to worry about running out of resources. Therefore, it is necessary to develop environmentally friendly renewable resources. Cellulose-based material is an excellent choice. Commonly, cellulose-based material consists of reinforcement (cellulose fiber) and matrix (polymer or metal). However, the compatibility between cellulosic material and polymer matrix should be considered. In general, the compatibility between them is poor. In this project, several methods to improve the compatibility between the cellulose material and polymer matrix were studied. Two cellulosic materials (microcrystalline cellulose (MCC) and cellulose oxalate (COX)) were treated with different modification methods to improve the compatibility and interfacial interaction between the cellulosic material and polymer matrix. Ball milling, using water as a dispersing agent, using oleic acid to esterify cellulose fiber for different reaction times (6 h, 18 h, and 48 h), and using different concentrations (1% and 2%) of maleic anhydride grafted polypropylene (MAPP) as compatibilizers were applied to improve the compatibility between cellulose fiber and polymer matrix.  To produce the composite specimens, extrusion and injection molding were utilized. Tensile testing was done to test the mechanical properties of the specimens. Contact angle (CA), scanning electron microscope (SEM), Fourier Infrared Spectrometer (FTIR), X-ray diffraction (XRD) were also performed on the various cellulose powders as characterization methods. According to the result of tensile testing, COX samples with 1% MAPP as compatibilizer, showed the highest tensile strength and Young’s modulus of all the composite samples produced in this master thesis. Using MAPP as a compatibilizer shows a better result than using other methods to improve the compatibility between hydrophilic MCC/COX surface and hydrophobic PP matrix. The use of MAPP as a compatibilizer should be prioritized when producing composite materials.
APA, Harvard, Vancouver, ISO, and other styles
38

Inman, Sharon. "Cellulose bilayer tablet interfaces." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/11775.

Full text
APA, Harvard, Vancouver, ISO, and other styles
39

Fugelstad, Johanna. "Cellulose Biosynthesis in Oomycetes." Licentiate thesis, Stockholm : KTH Biotechnology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9282.

Full text
APA, Harvard, Vancouver, ISO, and other styles
40

Feng, Xianhua Pelton Robert H. "Polyvinylamine carboxymethyl cellulose complexes." *McMaster only, 2006.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
41

Steele, David Fraser. "Amine/microcrystalline cellulose interactions." Thesis, University of Bath, 2002. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275882.

Full text
APA, Harvard, Vancouver, ISO, and other styles
42

Blell, Rebecca. "Microfibrillated cellulose based nanomaterials." Thesis, Strasbourg, 2012. http://www.theses.fr/2012STRAE023.

Full text
Abstract:
La cellulose étant l'un des biopolymères les plus abondants, elle est employée dans ce travail de thèse sous sa forme nano-fibrille (2 à 5nm de diamètre et plusieurs microns de long) pour préparer des nanomatériaux durables. Les microfibrilles de cellulose (MFC) chargées positivement ou négativement sont assemblées en couches minces dans ces nanomatériaux par la méthode « Layer by Layer » (LbL) par trempage, pulvérisation ou spin assisté. Les différences entre ces films LbL à base de MFC et les films LbL à base de polymères standards sont discutées brièvement et sont reliées à la forme nanofibrillaire de la cellulose. Les MFC réagissent comme des nano-objets anisotropes et rigides. Les films LbL de MFC sont ensuite intégrés à des membranes de séparation, entre la couche polymérique de séparation et le support poreux, pour améliorer le débit à travers ces membranes. Ces films minces sont également déposés sur des aérogels de cellulose pour améliorer la stabilité de ces aérogels en milieu aqueux. Dans les deux applications, les résultats était encouragent et montre une validation de principe
Cellulose, one of the most abundant biopolymers, is used in this PhD work in its nanofibrillated form, 2-5 nm in diameter and microns long, to prepare sustainable nanomaterials. Both positively and negatively charged microfibrillated celluloses (MFC) are assembled in these nanomaterials using the versatile Layer by Layer (LbL) assembly methods: dipping, spray assisted-deposition and spin-assisted deposition. A brief comparison between the MFC based LbL assembled films and the standard polymeric LbL films is carried out. Thedifferences between the two species are related to the fibrillar form of cellulose. MFC behaves like rigid anisotropic nano-objects. MFC LbL assembled films are then integrated in separation membranes between active polymeric separation layers and a mechanically stable porous support to improve the flux through these membranes. MFC LbL assembled films are also coated on cellulosic aerogels to improve the wet stability of these aerogels. In both cases, results were encouraging and showed a proof of concept
APA, Harvard, Vancouver, ISO, and other styles
43

Oliveira, Marcelo Miranda de. "Nanostructure variability of cellulose from plants and the impact on cellulose nanocrystals production." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/18/18158/tde-07112018-101553/.

Full text
Abstract:
This work investigates the compositional and nanostructural variability of celluloses isolated from plants and the impact of the variability in the production of cellulose nanocrystals. A variable set of cellulose isolated from plants were generated starting with a range of feedstocks (coconut fiber, sisal fiber, eucalyptus sawdust, pine sawdust, sugarcane rind and sugarcane pith), applying a range of cellulose isolation processes (acetossolv, liquid hot water, alkaline, and liquid hot water + alkaline) and adding commercial cellulose (eucalyptus kraft pulp, dissolving pulp, and microcrystalline cellulose) as reference materials. The nanostructural characteristics were evaluated by calorimetric thermoporometry, X-ray diffraction, and moisture sorption isotherms. Composition was evaluated by standard wet chemical analysis and insights on functional groups were obtained by infrared spectroscopy. The cellulose nanocrystals were produced by acid hydrolysis with sulfuric acid and characterized by atomic force microscopy and X-ray diffraction. The measured parameters of the isolated celluloses were spread, showing we could achieve a highly diverse set of substrates. Significant correlations between measured variables across the sample set, indicating possible unforeseen multivariate relations among cellulose features. For example, we could show that cellulose monolayer hydration is determined by both hemicelluloses content (compositional parameter) as well as cellulose crystal width (structural parameter). Cellulose nanocrystals were successfully produced, although in some cases such as for the acetossolv pulps the acid conditions were too aggressive and oxidized the substrates. Finally, some quantitative correlations were seen between the parameters of cellulose substrates and the resulting cellulose nanocrystals. These results supply the first hints about how the nanostructural variability of isolated cellulose can influence the cellulose nanocrystals produced from them.
Este trabalho investiga a variabilidade composicional e nanoestrutural de celuloses isoladas de plantas e o seu impacto na variabilidade na produção de nanocristais de celulose. Um conjunto variável de celuloses isoladas de plantas foi gerado a partir de uma série de matérias-primas (fibra de coco, sisal, serragem de eucalipto, serragem de pinheiro, casca de cana e miolo de cana), aplicando uma série de processos de isolamento de celulose (hidrotérmico, alcalino, hidrotérmico + alcalino e acetosolve) e adicionando celuloses comerciais (polpa kraft de eucalipto, polpa para dissolução e celulose microcristalina) como materiais de referência. As características nanoestruturais foram avaliadas por termoporometria calorimétrica, difração de raios X e isotermas de sorção de umidade. A composição foi avaliada por análise química húmida padrão e os conhecimentos sobre grupos funcionais foram obtidos por espectroscopia de infravermelhos. Os nanocristais de celulose foram produzidos por hidrólise ácida com ácido sulfúrico e caracterizados por microscopia de força atômica e difração de raios-X. Os parâmetros medidos das celuloses isoladas foram distribuídos, demonstrando que poderíamos alcançar um conjunto altamente diversificado de substratos. Correlações significativas entre as variáveis medidas foram observadas em todo o conjunto amostral, indicando possíveis relações multivariadas imprevistas entre as características da celulose. Por exemplo, poderíamos demonstrar que a monocamada de hidratação de celulose é determinada tanto pelo conteúdo de hemiceluloses (parâmetro de composição) quanto pela largura do cristal de celulose (parâmetro estrutural). Os nanocristais de celulose foram produzidos com sucesso, embora em alguns casos, como nas polpas acetosolve, as condições ácidas fossem muito agressivas e oxidassem os substratos. Finalmente, algumas correlações quantitativas foram observadas entre os parâmetros dos substratos de celulose e os nanocristais de celulose resultantes. Estes resultados fornecem as primeiras dicas sobre como a variabilidade nanoestrutural da celulose isolada pode influenciar os nanocristais de celulose produzidos a partir deles.
APA, Harvard, Vancouver, ISO, and other styles
44

Saïdi, Hédi. "Société, économie et colonisation d'une région en Tunisie pendant la colonisation française : Dar Elbey de 1880 à 1919." Paris 8, 2003. http://www.theses.fr/2003PA08A003.

Full text
APA, Harvard, Vancouver, ISO, and other styles
45

Sanford, Jane. "Shipping sheep : a zooarchaeology of Greek colonisation." Thesis, University of Cambridge, 2012. https://www.repository.cam.ac.uk/handle/1810/244937.

Full text
Abstract:
This PhD thesis (totaling approximately 55,000 words) argues for the value of biometric studies of domesticates as a means by which to examine controversial questions in archaeological research. Taking the Greek colonisation of southern Italy and the Adriatic coast of Croatia as case studies faunal material was examined from Greece and both of these areas to determine what data domesticates could provide as to the scale and process of Greek colonisation in these regions. Distinct varieties of sheep and cattle were identified from Greece through bone measurements. These Greek livestock could then be traced to colonies in Italy, although not necessarily in Croatia. It was argued from the scale of evidence for domesticate translocation it Italy that a substantial majority of settlement in these colonies came from settlement relocation of families or groups from Greece, but that some indigenous or “other” variety livestock were included in the domesticate makeup of each colony site. Some provisional data from Archaic and later indigenous sites from Italy suggested that Greek livestock varieties were traded throughout the colonial landscape. Data from Croatia was less clear, as no conclusive evidence for Greek livestock translocation to colonies could be found. Likewise, no evidence was found of trade in Greek livestock varieties with indigenous settlements.
APA, Harvard, Vancouver, ISO, and other styles
46

Akers, D. E. "Colonisation of sugar beet by Myzus persicae." Thesis, University of East Anglia, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235344.

Full text
APA, Harvard, Vancouver, ISO, and other styles
47

Twomey, Anne Law Faculty of Law UNSW. "The de-colonisation of the Australian states." Awarded by:University of New South Wales, 2006. http://handle.unsw.edu.au/1959.4/35217.

Full text
APA, Harvard, Vancouver, ISO, and other styles
48

Demay, Aline. "Tourisme et colonisation en Indochine (1898-1939)." Thèse, Paris 1, 2011. http://hdl.handle.net/1866/10096.

Full text
Abstract:
Comment le tourisme s’est-il développé dans un territoire en pleine expansion coloniale ? Comment tourisme et colonisation se sont-ils conjugués ? Quel lien peut-on établir entre ces deux dynamiques ? C’est ce à quoi cette thèse tente de répondre en démontrant l’instrumentalisation du tourisme par les politiques coloniales. Elle se divise en sept chapitres abordant successivement le transfert des pratiques touristiques de l’Europe à l’Indochine, leurs implantations, leurs intégrations aux politiques de mise en valeur des années 1920, les conséquences spatiales de leurs implantations (construction de voies de communication et d’hébergements hôteliers) et la communication instaurée par l’Etat pour promouvoir l’Indochine comme une destination touristique auprès des Indochinois comme des touristes étrangers.
How did tourism develop in a rapidly expanding colonial territory? How were tourism and colonization combined? What links were established between these two processes? These are the questions that this thesis addresses by demonstrating the exploitation of tourism by colonial policies. This thesis is divided into seven chapters dealing successively with the transfer of European tourism practices to Indochina, their location, their integration into the politics of territorial development in the 1920s, the spatial consequences of their implementation (construction of roads and hotel accommodation), and the attempts of the State to promote Indochina as a touristic destination for both Indochinese and foreign tourists alike.
APA, Harvard, Vancouver, ISO, and other styles
49

Dawson, Helen Sarah. "Island colonisation and abandonment in Mediterranean prehistory." Thesis, University College London (University of London), 2005. http://discovery.ucl.ac.uk/1383657/.

Full text
Abstract:
This thesis studies the colonisation and abandonment of Mediterranean islands in prehistory by placing them within a comparative framework. The geographical scope is pan-Mediterranean and chronologically it encompasses prehistory from the time when the earliest-known human records are found on a few islands to the time when most Mediterranean islands had been colonised (approximately from the end of the Pleistocene to the end of the Iron Age). By questioning established geographical boundaries and chronological restrictions and by incorporating recent theoretical advances in island archaeology, this thesis provides alternative explanations to colonisation paradigms prevalent in the 1980s and 1990s, expanding these to include considerations of abandonment and recolonisation. After investigating leading theoretical approachesto colonisation and abandonment, the study reviews the bulk of available publications on Mediterranean islandbased projects from the past ten years, and presents a series of revised colonisation and abandonment dates and models for the islands. At a broader level') these new data indicate the need for clearer distinctions between different types of island-human interaction (e. g. visitation, utilisation, occupation, establishment, abandonment, and re-colonisation). The thesis therefore also analyses - through a series of case studies - how human activity on islands varied spatially and temporally and potential reasons behind different colonisation and abandonment processes. The resulting observations are placed against the backdrop of the changing palaeogeography of the prehistoric Mediterranean, by taking into account changes in sea levels and in the islands' environments, and contextualised within the broader scheme of reference of Mediterranean prehistory.
APA, Harvard, Vancouver, ISO, and other styles
50

Cohen, J. M. "Colonisation-induced protection against Streptococcus pneumoniae disease." Thesis, University College London (University of London), 2011. http://discovery.ucl.ac.uk/1124359/.

Full text
Abstract:
Streptococus pneumoniae is an important human pathogen, yet in most individuals it establishes only transient nasopharyngeal colonisation without causing disease. Using murine models, this thesis explores the hypothesis that colonisation induces acquired immune responses which protect against subsequent pneumonia. Colonisation models with wild-type (WT) and mutant S. pneumoniae were established in outbred CD1 mice. Mutants lacked either capsule or lipoproteins, or were auxotrophs unable to replicate in vivo. WT colonisation protected against subsequent pneumonia. Mutants were cleared more rapidly than WT, were not immunogenic and did not protect. When the auxotroph was supplemented, colonisation, immunogenicity and protection were improved, suggesting duration of a colonisation event is an important factor in determining immunogenicity. This may be one factor explaining the poor immunogenicity of the other mutants. The mechanism by which previous colonisation protected against subsequent lethal pneumonia was then defined in a series of studies in inbred CBA/Ca mice. Colonisation induced both mucosal and systemic antibody responses to bacterial surface antigens but not capsule. There was also evidence of more robust cytokine production during subsequent pneumonia, including systemic and mucosal IL-17 responses dependant on the presence of CD4-cells. Protection was primarily against systemic invasion following pneumonia. Passive transfer studies and experiments using genetically modified mice demonstrated that systemic antibody was both necessary and sufficient to protect, and in vitro and in vivo models showed this to be via opsonophagocytosis and bloodstream clearance of bacteria. Antigenic protein targets of protective serum were defined using Western blotting and multiplex bead immunoassay techniques. Overall this thesis demonstrates that nasopharyngeal colonisation can protect against lethal pneumonia in mice via opsonophagocytic antibody against surface proteins thus preventing bacteraemia.
APA, Harvard, Vancouver, ISO, and other styles
You might also be interested in the bibliographies on the topic 'Colonisation de la cellulose' for other source types:
Journal articles Books
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography