Ce travail est consacré à l'étude, par des techniques originales de diffusion dynamique de la lumière, de la dynamique lente de deux systèmes colloïdaux modèles. On a utilisée une technique de Corrélation Résolue dans le Temps (TRC) et des simulations numériques pour sonder, sur une grande plage de concentrations et sur sept décades en temps de relaxation, la dynamique d'un système de sphères dures colloïdales approchant de la transition vitreuse. A faible fraction volumique les temps de relaxation peuvent être représentés par une loi de puissance critique comme prévu par la Théorie de Couplage des Modes (MCT). A des concentrations élevées le temps de relaxation augmente selon une inattendue loi exponentielle critique avec une fraction volumique critique supérieure à celle prévue par MCT. L'étude des fluctuations de la dynamique confirme la présence d'un régime de dynamique activée: ce scénario est le même que l'on retrouve pour les systèmes vitreux moléculaires. Le deuxième sujet étudié est le comportement d'une suspension de colloïdes attractifs soumis à la contrainte gravitationnelle. Initialement, des agrégats de particules sédimentent en formant un gel sur le fond de la cellule. Les techniques spéciales employées nous ont permis de mesurer l'évolution des profils de concentration, des profils de vitesse et la dynamique locale dans la phase gel: la sédimentation peut être complètement décrite par le taux de déformation locale qui permet aussi une remise à l'échelle de la dynamique locale. Le rôle de la friction aux parois des cellules a été sondé par des expériences de polarimétrie et par la résolution numérique d'un modèle poroélastique pour la sédimentation du gel. / We investigated, using original light scattering techniques, the slow dynamics of two different model colloidal systems. We used a Time Resolved Correlation (TRC) technique and numerical simulations to study the dynamics of systems of colloidal hard spheres over a broad range of densities and seven decades in relaxation time. At low volume fraction the equilibrium relaxation time is described by the algebraic divergence predicted by mode-coupling theory (MCT). At higher density the relaxation time increases with an unexpected critical exponential form, whose the critical volume fraction is much larger then the MCT singularity. The fluctuations of the dynamics confirm the presence of an activated regime, as founded in molecular glass formers close to the glass transition. The second research subject concerns the behaviour of suspensions of attractive colloidal particles under gravitational stress. Initially, clusters fall forming a gelled deposit at the cell bottom. Our apparatus allows us to follow over time the concentration profile, the velocity profile and the local dynamics in the gel phase: the settling may be fully described by the local strain rate and dynamics exhibits remarkable scaling properties when time is normalized by strain rate. The role of the solid friction at the cell walls has been investigated by polarimetry experie nces and solving numerically a poroelastic model of gel sedimentation.

Les ressources renouvelables sont considérées comme des alternatives durables, et parfois moins chères, aux matières premières d'origine pétrochimique. Dans cette thèse, on a utilisé du tanin provenant d’écorces de Mimosa comme précurseur de matériaux carbonés. La synthèse de ces nouveaux matériaux carbonés comprend un processus en deux étapes: la première étape est un traitement hydrothermal à des températures modérées, de 180 à 200°C, ce qui permet l'enrichissement en carbone ainsi que la fixation des hétéroatomes et la production de différentes morphologies: microsphères ou gels. La deuxième étape est une carbonisation à une température plus élevée, à savoir 900°C, ce qui permet d'augmenter la surface spécifique, la porosité ainsi que la conductivité électrique. La préparation d’un carbone poreux présentant des mésopores parfaitement définis en taille et dans leur organisation a été réalisée en associant le tanin, précurseur de carbone, à un tensio-actif structurant de la porosité, le copolymère Pluronic F127. Ces nouveaux matériaux carbonés ont été testés comme des électrodes de supercondensateur / Renewable resources are considered as sustainable, and sometimes cheaper, alternatives to substitute raw materials of petrochemical origin. We used tannins extracted from Mimosa barks. Tannin is an attractive precursor to synthesize new organic porous materials due to the presence of highly reactive phenolic molecules. The synthesis of these new carbon materials from tannin comprises a two-step process: the first step is a hydrothermal carbonization at moderate temperatures, 180-200°C, which allows obtaining a hydrochar, richer in carbon, and fixing other heteroatoms. These hydrochars present different morphologies as powder or gel. The second step is a carbonization at higher temperature (900°C), which allows increasing surface area (SBET), porosity as well as improving conductivity. The preparation of a porous carbon presenting mesopores perfectly defined in size and in their organization was realized by associating tannin, as carbon precursor, with a surfactant for porosity templating, the copolymer Pluronic F127. These new carbon materials were tested as electrodes of supercapacitor

Certains composés à conversion de spin, en particulier une famille de composés unidimensionnels de type [FeII(triazole)3]A2 ont été proposés comme potentiels matériaux moléculaires pour le stockage de l'information ou comme composants de systèmes optiques. Leurs propriétés couplées de conversion de spin thermique et thermochromisme ont permis de développer des prototypes utilisant ces matériaux sans aboutir à une application industrielle. Un des principaux problèmes étant la mise en forme de ces systèmes magnéto-optiques, nous nous sommes orientés vers l'élaboration de nouveaux matériaux hybrides. En fonctionnalisant les groupements triazoles de composés [MII(triazole)3]A2, nous avons obtenu des matériaux possédant des propriétés de cristaux liquides ou de gélifiant de solvants. Dans le cadre de cette thèse, nous nous sommes intéressés aux propriétés physico-chimiques de ces cristaux liquides et de ces gels magnétiques.

The purpose of this project was to fabricate biodegradable ophthalmic inserts for controlled delivery of pilocarpine and evaluate them by both in-vitro and in-vivo studies. Emphasis was placed on the use of an inexpensive material as a drug carrier and on the ease of fabrication of the device. Based on these criteria, absorbable gelatin was selected to fabricate a matrix system. Absorbable gelatin can be obtained by either thermal treatment or chemical crosslinking of gelatin. In the first part of this project, we fabricated an insert using Gelfoamᴿ, an absorbable gelatin sponge obtained by thermal treatment. A prolonged in-vitro release of pilocarpine from the device was achieved through pharmaceutical modification by embedding a retardant in the pores. The devices impregnated with polyethylene glycol monostearate (PMS) and cetyl esters wax (CEW) were found to be most effective. The in-vivo evaluation of the devices indicated that pharmaceutical modification of Gelfoamᴿ is an effective means of improving the biological activity of pilocarpine without altering the biodegradability of the biopolymer backbone. The CEW device produces a substantial improvement in drug bioavailability and an increase in the duration of biological effect over that from the two commercial formulations, the eyedrop and the gel. In the second part of the project, we fabricated absorbable gelatin inserts through chemical crosslinking of gelatin. The effect of selected fabrication variables on profiles of the in-vitro release of pilocarpine and the dynamic water uptake by the crosslinked gelatin devices was investigated. These results were further substantiated by the measurement of the degree of crosslinking of gelatin. The in-vivo study indicated that the modification of the structure of gelatin by crosslinking is another simple and effective way of improving bioavailability and extending the duration of effect of pilocarpine incorporated in the biopolymeric device. In addition, altering the degree of crosslinking of gelatin allows a variation of the biodegradation time of the polymer.

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

A fibroína da seda (SF) é uma proteína fibrosa, com caráter hidrofóbico, produzida pelo bicho-da-seda (Bombyx mori L.), cuja produção e armazenamento ocorre em glândulas especializadas antes do processo de fiação em fibras. Recentemente, soluções de fibroína de seda regenerada (RSF) têm sido utilizadas para formar diferentes materiais tais como géis, membranas, filmes e esponjas, para aplicações médicas (Medicina Regenerativa) e em sistemas de liberação de fármacos. Neste trabalho, procuramos estudar o comportamento da solução RSF 2% com adição de 0,25, 0,5 e 1% de PVA (polímero sintético e hidrofílico) por meio de ensaios de reologia dos géis obtidos (SF:PVA), e caracterização das membranas obtidas por meio da secagem em moldes dos géis. Os ensaios de reologia mostraram uma inversão de módulos, com transição de caráter elástico (G\') para viscoso (G\") para SF1 a 3%, entre 230 e 900% de deformação (\'gama\'); transição de caráter viscoso para elástico para as blendas SF:PVA 0,5 e 1% em ensaio de frequência (\'ômega\'). Com o aumento de temperatura, todas as blendas mantiveram seus comportamentos elástico (SF:PVA 0,25%) e viscoso (SF:PVA 0,5 e 1%) até 49 - 51°C, com transição líquido-gel; o aumento dos módulos G\' e G\"com o resfriamento das amostras ocorreu em todas as blendas. As membranas obtidas das blendas SF:PVA tiveram maior absorção de tampão fosfato salino (PBS) após 5 min de ensaio, no qual a blenda SF:PVA apresentou maiores valores de absorção. A caracterização das membranas por FT-IR ATR e DRX mostrou que ocorreu uma transição de conformação aleatória e hélice \'alfa\' para folha \'beta\', para todas as membranas, indicando que a adição do PVA nas blendas promoveu transições silk I para silk II. Deslocamentos de modo vibracional de 1.637/cm (amida I) para 1.616/cm (amida I) com modo centrado em 1.512/cm (amida II) foram vistos em todas as blendas no FT-IR ATR, e difratogramas apresentaram picos característicos às estruturas silk I (2\'teta\' = 10,12º, 2\'teta\' = 12,2° e 2\'teta\' = 28,2º) e silk II (2\'teta\' = 20 - 21 °1). TGA e DSC mostraram uma interação entre as cadeias de RSF c PVA, pela presença de uma temperatura única ele transição vítrea (Tg) entre RSF e PVA. Imagens AFM das blendas mostraram a presença de estruturas nanofibrilares, em formato de ilhas compactas e ramos, confirmando a transição da fase amorfa de SF 2% para hélice \'alfa\' e folha \'beta\', com a adição do PVA. / Silk fibroin (SF) is a fibrous hydrophobic protein produced by silkworms (Bombyx mori L.), which production and storage occur into specialized glands previously fiber formation. Lately, regenerated silk fibroin (RSF) solutions have been used to produce different materials such as gels, membranes, films and sponges, for medical applications and drug delivery systems. In this study, the RSF with 0.25, 0.5 anel 1% PVA (synthetic and hydrophilic polymer) blends were characterized by rheological tests of the gels (SF:PVA), also membranes produced by casting process were characterized as well. Rheological tests showed moduli inversion with elastic to viscous behavior transition for SF 1 to 3%, between 230 anel 900% of strain (\'gama\'); a transition fram viscous to elastic behavior to SF:PVA 0.5 to 1% blends into frequency sweep tests was observed. With the temperature increment, all blends have kept their viscous anel elastic behavior until 49 - 51°C, and a liquid-gel transition occurred in the SF:PVA 0.5 and 1% blends, as well as all moduli have increased with the cooling stage of the samples. All membranes had the highest buffer absorption after 5 min of test, in which SF:PVA 0.5% blend presented high absorption values. FT-IR spectra and XRD diffractograms showed a transition from random and \'alfa\'-helix to \'beta\'-sheet, for all blends, indicating that PVA addition promotes silk I to silk II transition. Modal shifts were observed from 1.637/cm (amide I) to 1.616/cm (amide I) with a central mode in 1.512/cm (amide II) in all blends in the FT-IR ATR spectra. XRD diffractograms showed characteristic peaks of silk I structures (2\'teta\' = 10,12°, 2\'teta\' = 12,2° e 2\'teta\' = 28,2°) and silk II structures (2\'teta\' = 20 - 21 °1). TGA and DSC studies showed the possibility of interaction between SF and PVA chains by acquirement of mobility at once, at an intermediate temperature between SF anel PVA glass transition (Tg). AFM images exhibited different phases for all membranes, with the presence of nanofibers, wires, rods and branch islands, suggesting the formation of more organized structures, such as and \'alfa\'-helix and \'beta\'-sheet, with PVA addition.

Dai, Zhuojun. / Thesis Ph.D. Chinese University of Hong Kong 2014. / Includes bibliographical references. / Abstracts also in Chinese. / Title from PDF title page (viewed on 15, September, 2016).

>Magister Scientiae - MSc / Liposomes as a drug carrier in the pharmaceutical industry has gained currency since its discovery in 1965 by Bangham A. D. Liposomes have been shown to improve bioavailability as they can be delivered to target sites and possess sustained release properties which could be used to mitigate certain weaknesses associated with current diclofenac sodium eye drops. Diclofenac sodium (DNa) eye drop is a sterile Nonsteroidal Anti-inflammatory Drug (NSAID) with diclofenac sodium as its active ingredient. It is indicated for the lessening of ocular pain, prevention of miosis in eye operations, easing of postoperative inflammation and cystoids macular edema. The residence time of eye drops after application has been found to be 1-2 minutes as a result of continuous production of tears diluting the active ingredient, draining the eye drops into the nasolacrimal path, and eliminating it during blinking. As a result of the active ingredient not residing at the target site for the required duration, more frequent administration and medication is required and the risk of non-compliance is increased. Given the aforementioned potential of liposomes to redress the above weaknesses of current eye drops (dosage form) available for diclofenac sodium ophthalmic application, this study sought to encapsulate diclofenac sodium into liposomes for ophthalmic application. The main components of liposomes (cholesterol and phosphotidylcholine) and incubation time were set as the independent variables while percentage encapsulation, polydispersity index (PDI) and drug release profile constituted the dependent variable. Using analysis of variance (ANOVA) and t-test statistics, the interaction between the independent variables and their effect on the dependent variables were tested.

<p>Sporedni proizvodi dobijeni u procesu mlevenja žitarica, p&scaron;enične i ovsene mekinje, hidrotermički su tretirane u cilju dobijanja gelova, koji se, kao zamenjivači masti, mogu koristiti u formulacijama prehrambenih proizvoda. Optimizacija procesnih parametara (koncentracija mekinja, vreme homogenizacije i temperatura homogenizacije) proizvodnje gelova vr&scaron;ena je primenom postupka odzivne funkcije (RSM). Gelovi od p&scaron;eničnih i ovsenih mekinja, koji su pripremljeni po prethodno utvrđenim optimalnim parametrima (za p&scaron;enične mekinje: 22,0% koncentracija mekinja, vreme homogenizacije od 11,7 min i temperatura homogenizacije od 83,2&deg;C; za ovsene mekinje: 22,0% koncentracija mekinja, vreme homogenizacije od 10,0 min i temperatura homogenizacije od 95,0&deg;C), su, dalje, kao zamenjivači masti, bili inkorporirani u formulaciju keksa na različitim nivoima supstitucije masti (30%, 40% i 50%).<br />Fizičke, teksturne i senzorske karakteristike keksa sa zamenjivačima masti ispitane su u poređenju sa kontrolnim (punomasnim) keksom, te je nivo zamene od 30% izabran kao najpogodniji u smislu sniženja sadržaja masti, sa jedne strane, i ostvarenja željenih karakteristika, sa druge strane.<br />S obzirom da su proizvedeni zamenjivači masti na bazi mekinja nutritivno vredni i bogati funkcionalnim komponentama, ustanovljeno je da je dodatak ova dva funkcionalana zamenjivača masti na nivou od 30% doprineo pobolj&scaron;anju nutritivnih i funkcionalnih svojstava keksa u pogledu povećanog sadržaja prehrambenih vlakana i minerala, povoljnijeg odnosa PUFA/SFA, kao i porasta sadržaja antioksidativno delotvornih komponenti.</p> / <p>Wheat and oat brans, by-products of grain processing, were processed by hydrothermal treatments into the form of gels for partial replacement of fat in food products.<br />Response surface methodology (RSM) approach was applied to examine the effects and to optimize process parameters (bran concentration, homogenization time and homogenization temperature).<br />Wheat and oat bran gels prepared according to the previously determined optimal parameters (for wheat bran: 22.0% bran concentration, homogenization time of 11.7 min and homogenization temperature of 83.2 &deg;C; for oat bran: 22.0 % bran concentration, homogenization time of 10.0 min and homogenization temperature of 95.0 &deg;C) were further incorporated as fat substitutes into the cookie formulation at different levels of substitution (30%, 40% and 50%).<br />The physical, texture and sensory properties of cookies with fat replacers were examined in comparison with the control (full fat) cookies, and the fat replacement level of 30% was chosen as the most suitable in terms of reducing the fat, on the one hand, and achieving the desired mentioned characteristics, on the other.<br />Knowing that the produced fat replacers are nutritionally valuable and rich in functional components, it has been found that the addition of these two functional fat replacers at the level of 30% contributed to the improvement of the nutritional properties of cookies in terms of higher content of dietary fibers, minerals and more favourable ratio of PUFA/SFA, as well as higher content of antioxidant components.</p>

Syneresis is an integral part of cheese manufacture. The rate and extent of syneresis affect the properties of cheese. There are many factors that affect syneresis, but measured results vary because of inaccuracies in measuring techniques. To better control syneresis, an accurate mathematical description must be developed. Current mathematical models describing syneresis are limited because of inherent error in measuring techniques used to develop them. Developing an accurate model requires an accurate way to measure syneresis. The curd becomes a particle in a whey suspension when the coagulum is cut. The most effective technique to measure particle size, without interference, is with light. Approximations to rigorous Maxwellian theory render useable results for a variety of particle sizes. Assumptions of Fraunhofer diffraction theory relate absorption to the cross sectional area of a particle that is much larger than the wavelength of light being used. By applying diffraction theory to the curd-whey system, this researcher designed a new apparatus to permit measurement of large particle systems. The apparatus was tested, and calibrated, with polyacrylic beads. Then the syneresis of curd was measured with this appaatus. The apparatus was designed to measure particles in suspension. Until some syneresis takes place, curd does not satisfy this condition. Theoretical assumptions require a monolayer of scattering centers. The sample container must be thin enough to preclude stacking of the particles. This presents a unique problem with curd. If the coagulum is cut in the sample cell, it adheres to the front and back surfaces and does not synerese. The curd must be coagulated and cut externally and transferred to the sample cell with a large amount of whey. This measurement technique has other limitations that may be overcome with commercially available accessories.