Cette thèse propose deux applications originales du contrôle de la température dans des microsystèmes, abordant des problématiques d'hydrodynamique et de matière molle.Dans une première partie, nous nous intéressons au contrôle du drainage de mousses 2D en confinement micrométrique par effet Marangoni. Pour ce faire, nous appliquons un gradient de température constant à une mousse bidimensionnelle confinée dans une cellule de Hele-Shaw, et observons que l'effet thermocapillaire induit génère un écoulement surfacique capable de contre-balancer le drainage gravitaire naturel. L'équation de conservation de la masse permet de définir des temps caractéristiques inhérents à chacun de ces effets, aboutissant au contrôle du drainage dans notre système modèle.Dans une seconde partie, nous développons une méthode polyvalente pour la microfluidique digitale, basée sur l'effet thermomécanique. Cet effet consiste à chauffer localement un matériau déformable (i.e. du PDMS), dont la dilatation est mise à profit pour réaliser toutes les opérations élémentaires de microfluidique digitale, telles que la génération de gouttes, leur mise en mouvement, piégeage, stockage, tri, brisure ... notre méthode étant opérationnelle pour des gouttes d'eau dans l'huile ou d'huile dans l'eau. / This thesis offers two original applications involving temperature control in microsystems, dealing with hydrodynamics and soft matter. The first part focuses on the drainage control of 2D microfoams by Marangoni effect. To this end, we apply a constant temperature gradient throughout a 2D foam confined in a Hele-Shaw cell, and observe that the induced thermocapillary stress is strong enough to counterbalance and even overcome the natural effect of gravity drainage. The mass conservation in the cell leads to the definition of characteristic drainage times inherent to each effect at play, paving the way to the accurate control of the drainage dynamics in our model system.In a second part, we develop a versatile technology for digital microfluidics, based on thermomechanical effect. This effect consists in locally heating a deformable material (i.e. PDMS), which dilation is used to perform all the elementary operations encountered in digital microfluidics, such as droplet generation, motion, storage, sorting, splitting ... our technology being effective for both oil-in-water and water-in-oil droplets.

La fabrication fromagère a depuis longtemps réalisé sa révolution technologique avec la disparition progressive des techniques fermières et l'avènement des pratiques industrielles. Les cuves de cuivre ont été délaissées au profit du tout inox et l'utilisation du lait pasteurisé a augmenté. Néanmoins une part non négligeable des micro-organismes d'affinage provident encore d'un ensemencement spontané par le lait, l'environnement ou le matériel de fabrication. Cette flore naturelle est en grande partie à l'origine : (i) de la richesse et de la diversité organoleptiques des produits traditionnels, (ii) des différences observées entre un fromage industriel fabriqué avec du lait pasteurisé réensemencé avec un levain standard et un fromage " Apellation d'Origine Contrôlée au lait cru " de qualité. Compte tenu de l'évolution des pratiques de fabrication (renforcement des règles d'hygiène réduisant les sources naturelles d'ensemencement traitement du lait par pasteurisation ou microfiltration ; exigence de reproductibilité en utilisant des souches spécifiques présélectionnées), l'utilisation de flores d'affinage sous forme de ferments à additionner au lait doit être de plus en plus envisagée. Le secteur " artisanal " a un grand besoin de recherche et de développement (R&D) afin de conserver ses fabrications traditionnelles, comme les A.O.C qui représentent plus de 10% de la production fromagère en valeur. Les professionnels du fromage souhaitent identifier les souches les plus appropriées à chacun de leurs produits, afin de garantir leur typicité et une reproductibilité de fabrication. Les fromages à pâte molle et croûte lavée comme le Munter et l'Epoisses possèdent une croûte, appelée morge, allant du beige au brun, en passant par le jaune et le rouge-orangé. C'est cette couleur, en plus du caractère organoleptique particulier, que les fromagers cherchent à typer et à reproduire par l'utilisation des souches pigmentées. On a longtemps pensé que cette pigmentation était due uniquement au " ferment du rouge ", Brevibacterium linens. Mais des études récentes ont mis en évidence le rôle non négligeable d'autres bactéries sur la pigmentation de ces fromages, en particulier les corynébactéries et les microcoques. La recherche et la sélection de bactéries pigmentées sauvages par des méthodes simple à mettre en œuvre, la connaissance des mécanismes microbiologiques et moléculaires de la synthèse de pigments et de la coloration des fromages, permettraient de développer des cocktails de souches spécifiques à chaque production fromagère. La première phase du projet consistera en l'isolement de plusieurs centaines de souches sur des fromages issus de terroirs suivants : Epoisses, Reblochon, Munster, Livarot. Ensuite, pour chaque A.O.C., 25 souches d'Arthrobacter correspondant à des teintes variables seront caractérisées d'un point de vue pigmentation :- aspect, teinte sur milieu gélosés,- cinétiques de production en milieu solide et en milieu liquide,- cultures en masse, méthodes d'extraction des pigments,- quantité de pigments produite (production volumique mg/L de milieu) (production spécifique mg/g MS),- valeurs spectrocolorimétriques (L a*b*C*h),- profil HPLC,- HPLC-MS,- RMN des pigments purifies. Les facteurs influençant la production de pigments (substrats ; cultures mixtes-levures désacidifiantes / bactéries ; lumière…) seront étudiés, en portant l'accent sur des milieux de type fromage, voire des caillés modèles. / Smear-ripened soft cheeses, characterized by their orange-red color on rind, are dairy products widely consumed in Europe. The surface color is due essentially to carotenoids, in combination with other pigments, produced by the cheese microflora during ripening. Arthrobacter sp. is one of the major microorganisms occurred on the surface of cheeses, particularly in smear-ripened cheeses, where it is assumed to be responsible for yellow pigmentation of the cheese rind because of its characteristic overall color and its involvement at the different stages of cheese ripening. Pigment-producing microorganisms are commonly found in the nature. Nowadays, pigment-producing microorganisms have been increasing of interest in many scientific disciplines and applications have broadened in the industry because of their biotechnological advantages. As the present trend entirely the world is shifting toward the use of eco and biodegradable products, the requirement for natural ingredients, especially natural colorants, is increasing day by day. The first part of this thesis highlights the crucial role of microorganisms as potential sources of natural pigment production by reviewing a large number of research works related to pigments biosynthesized by microorganisms which were published over the past 10 years by private companies or academic laboratories, with an emphasis on pigments providing for the application in foods. Since the genus Arthrobacter is a group of metabolically versatile bacteria which widely distributed in nature, some parts of this thesis include the review presenting the possibility to produce pigmented Arthrobacter sp. biomasses as novel sources of food colorants; furthermore, the beneficial aspects of Arthrobacter sp. and their promising significances in the dairy industry are also addressed. Considering the significance of Arthrobacter sp. in smear-ripened cheeses, the economically important dairy products, the aim of research described in this thesis is to investigate the implication of this bacterium, particularly Arthrobacter arilaitensis, in the coloration of these cheeses in several aspects covering (i) diversity of pigment production among strains, (ii) kinetic of pigment synthesis, (iii) identification of chemical characteristic of pigments, (iv) colorimetric characterization of pigmentation, and (v) influences of environment i.e. light, pH, NaCl and deacidifying yeasts on the production and the color development of pigments. Among 14 strains of Arthrobacter arilaitensis studied, two groups depending on their ability of carotenoid production could be divided, carotenoid-producing and non-pigmented strains. A growth-associated pigmentation probably applied to indicate the kinetic of carotenoid synthesis by these strains. The diversity of pigment concentration among the carotenoid-producing strains was low, related to the characteristics of pigmentation determined by quantitative spectrocolorimetry. The HPLC-PDA-APCI-MS analysis of extracted pigments of a representative strains revealed 8 different carotenoids showing C50 decaprenoxanthin as the major accumulated carotenoids. Changes in the color development of A.arilaitensis strains under the influences of physical, chemical and biological factors were obtained through spectrocolorymetry. Three groups depending on a coloration behavior affected by light were illustrated e.g. positively sensitive, negatively sensitive and not sensitive to light. The acidic pH and high concentration of salt showed the efficiency inhibited effect on pigmentation of a representative strain of carotenoid-producing A. arilaitensis. In combination of pH and NaCl, deacidifying yeasts were obviously related to the pigment production of A. arilaitensis. The highest average value of color saturation were observed on the studied media deacidified by Debaryomyces hansenii at pH 7.0, displaying intense yellow.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-07-13T14:23:21Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Dissertação de Mestrado Augusto - Versão Final - 05.07.16.pdf: 2539433 bytes, checksum: 5317f34435773775b8fcf0c7526d78d5 (MD5) / Made available in DSpace on 2017-07-13T14:23:21Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Dissertação de Mestrado Augusto - Versão Final - 05.07.16.pdf: 2539433 bytes, checksum: 5317f34435773775b8fcf0c7526d78d5 (MD5) Previous issue date: 2016-05-27 / O pantoprazol é, atualmente, um dos medicamentos mais utilizados para tratamento das doenças gástricas por seu mecanismo de ação conhecido e eficácia comprovada na inibição da secreção de ácido no lúmen estomacal, contudo o tratamento prolongado e os efeitos causados pelas gastropatias exigem tratamentos específicos e mais abrangentes. O material Vegetal Schinus terebinthifolius Raddi, conhecida como Aroeira, já é utilizada popularmente em feridas cutâneas pelos seus efeitos cicatrizantes e anti-inflamatórios, possui vários estudos comprovando sua eficácia na diminuição das lesões promovidas pelas doenças gástricas. Sabendo-se da existência das formulações Associação em Dose Fixa (ADF), que integram em uma mesma fórmula farmacêutica um insumo farmacêutico sintético e um insumo farmacêutico fitoterápico, o objetivo deste trabalho foi elaborar um forma farmacêutica sólida ADF utilizando doses terapêuticas do pantoprazol e do extrato da Aroeira. Para isto, foi realizada a obtenção do granulado seco de aroeira pela metodologia de secagem por convecção. Assim, os ativos foram misturados a excipientes e transformados em comprimidos, por compressão direta. Os comprimidos obtidos foram submetidos a controle físico-químico e foram realizados testes de doseamento, dissolução e estabilidade acelerada que avaliaram as condições da formulação. Como esperado a dissolução demonstrou liberação do pantoprazol em meio básico e degradação em meio ácido, levando a necessidade de utilização do fármaco em formato de grânulos gastroresistentes. Já os testes de estabilidade realizados nos tempos 0, 3 e 6 meses atestou no curto período a manutenção das características básicas de liberação e teor dos comprimidos que foram mantidos durante o estudo em câmara climática de zona IV. Foi possível, desta forma, estabelecer os parâmetros básicos para o desenvolvimento desta formulação ADF contribuindo para a descoberta de alternativas terapêuticas aos tratamentos convencionais. / Pantoprazole is today one of the most used drugs for the treatment of gastric diseases because its known mechanism of action and proven effectiveness in inhibiting acid secretion in the stomach lumen, but prolonged treatment and the effects caused by gastropathy require specific treatments and more extensive. Schinus terebinthifolius Raddi plant, known as Aroeira, is already commonly used in skin healing by its anti-inflammatory effects, having several studies showing efficacy in reducing gastric lesions promoted by the disease. Knowing the existence of the formulations Association-Dose-Fixed (ADF), which are part of the same pharmaceutical form, a synthetic active ingredient and an active herbal principle, the objective of this study was to develop a solid dosage form ADF using therapeutic doses of pantoprazole and the Aroeira extract. For to obtain the dry granulated were used the method for drying by convection, where the active excipients were mixed and tableted by direct compression. The tablets obtained were subjected to physic-chemical control and tests to determinate their concentrations, their accelerated stability and their dissolution quality who served to evaluate the conditions of the formulation. The obtained values maintained their therapeutic range described in the literature. As expected the dissolution demonstrated release of pantoprazole in basic medium and degradation in acid medium that leads to the need to use the drug in gastroresistant granules format. Since the stability testing at 0, 3 and 6 months attested short period maintaining the basic characteristics of release and content of the tablets that were maintained during the study in climate zone IV camera. It was thus possible to establish the basic parameters for the development of this formulation ADF contributing to the discovery of therapeutic alternatives to conventional treatments.

The main aim of this study was to isolate and characterise antifungal and antibacterial compounds from leaf extracts of Combretum molle which belonging to the Combretaceae family. C. molle is one of the commonly used medicinal plants in southern Africa for numerous ailments. Three animal fungal pathogens, namely, Candida albicans, Cryptococcus neoformans, Aspergillus fumigatus and five plant fungal pathogens, namely, Aspergillus niger, Aspergillus parasiticus, Fusarium oxysporum, Penicillium janthinellum, Rhizoctonia solani and four nosocomial bacteria Staphylococcus aureus, Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa were used as test microorganisms for bioactive compounds in leaf extracts of C.molle. Experiments for phytochemical analysis were done using different C. molle leaf extracts which were made using acetone, methanol, ethanol, ethyl acetate, chloroform, butanol and hexane as extractants. Thin Layer Chromatography (TLC) fingerprints of different leaf extracts were developed in three mobile phase systems, EMW, CEF and BEA and detected with vanillin-sulphuric acid spraying agent. The different extracts of C. molle showed the presence of many different compounds with distinct retardation factors (Rf), separated according to their polarities. Bioautography was carried out to determine the number of active compounds and their Rf values. The TLC plates were developed in three mobile systems, each sprayed with either fungal or bacterial strains. In BEA bioautograms of A. fumigatus, clear zones of inhibition were observed at Rf values of 0.12, 0.23, and 0.40. In EMW bioautogram of C. albicans, clear zones of inhibition were observed at Rf value of 0.73, 0.81, 0.87. C. neoformans had weak growth inhibition. Most of the fungal and bacterial strains tested in the bioautography displayed susceptibility to the active compounds, with P. janthinellum and P. aeruginosa showing exceptional sensitivity. The minimum inhibitory concentrations (MIC) values ranged from 0.02 to 2.5 mg/ml against the tested pathogens. The acetone and ethyl acetate extracts had the best inhibitory activity against P. janthinellum with an MIC value of 0.02 mg/ml. The acetone extract of C. molle gave the highest total activity (775 ml/g) against P. janthinellum. C. albicans was the most resistant pathogen with an average MIC value of 0.56 mg/ml compared with the other tested strains. Extracts were active against both Gram-positive and Gram-negative strains. P. aeruginosa extracts had the highest average MIC value (0.24 mg/ml) among the tested bacterial strains. In general, there was good overall inhibitory activity by different extracts of C. molle. Bioassay-guided fractionation of DCM extract of the leaves of C. molle yielded 32 fractions. Further fractionation led to the isolation of five compounds (C1, C2, C3, C4 and C5). Compound C1 was selected for structure elucidation due a larger quantity isolated and higher antimicrobial activity compared with the other isolated compounds. Nuclear magnetic resonance (NMR) spectroscopy and mass spectroscopy (MS) was used to show that compound C1 was taraxerol, belonging to the taraxerane group. Antimicrobial activity of the isolated compound against P. janthinellum had an MIC value of 0.08 ug/ml. Although the compound taraxerol have been discovered in other plant species, it is reported for the first time from C. molle in the study. The results illustrate that crude extracts and compound taraxerol from C. molle can be used as either an antibacterial or antifungal, and warrants further investigation. / Dissertation (MSc)--University of Pretoria, 2017. / Paraclinical Sciences / MSc / Unrestricted

El presente estudio de prefactibilidad y su respectivo desarrollo tiene como objetivo principal evaluar la viabilidad comercial, técnica, legal y económica para la implementación de una planta de producción, en la región Apurímac, que realice la fabricación, distribución y comercialización de repelentes a base de molle. El producto a comercializar será 75 gramos de repelente a base de molle mezclado con alcohol de 70º, bajo la marca “Moskybye”. La presentación de este producto será en empaques color ámbar en forma de spray con una capacidad de 150 ml. En cuanto al mercado meta, este será la ciudad de Lima Metropolitana, así como las regiones de Piura, Tumbes y la Amazonía Peruana. Por otro lado, el precio de venta del repelente será constante a lo largo de los años del proyecto y tendrá un valor de S/ 4,37. Además, se estima un nivel de ventas para el primer año del proyecto de 967 232 unidades, el cual se irá incrementando para los siguientes años. Finalmente, los canales de distribución por los que se comercializará el producto serán farmacias, tiendas naturistas, mercados tradicionales, tienda virtual de la propia empresa, entre otros. Adicionalmente, se definió la localización en la provincia de Antabamba, en la región Apurímac, y el tamaño del local de 1 500 m2 para cubrir las áreas productivas y administrativas. Además, la capacidad de la planta será de 1 200 000 unidades anuales para todos los años del proyecto. Es importante señalar que, dentro del proceso productivo, no se identificaron aspectos ambientales significativos, lo cual muestra sostenibilidad ambiental, siendo esto uno de las principales características que diferencia a la marca de la competencia. Finalmente, se determinó que, para llevar a cabo el proyecto, se requiere una inversión inicial de S/ 1 424 238, la cual será cubierta, en un 59% por capital propio y lo faltante se financiará por intermedio de entidades bancarias. Por otro lado, el resultado de este estudio señala que el proyecto genera un VANE de S/ 294 916,01 y un VANF de S/ 258 580,76, con una TIRE de 29% anual, mayor al WACC (19,61% anual), y una TIRF de 43% anual, mayor al COK (27,62% anual). Es importante destacar que, con los indicadores mostrados anteriormente, se concluye que el proyecto es viable.

Uno de los principales problemas que afecta la ganadería a nivel mundial está relacionado con la presencia de parásitos externos. Los ectoparásitos afectan la productividad pecuaria al disminuir la producción de carne y leche; además son transmisores de agentes patógenos. La principal parasitosis del ganado bovino es la garrapata Boophilus microplus. La agricultura se ve afectada por insectos tales como Spodoptera littoralis y Epilachna paenulata. Los acaricidas e insecticidas químicos constituyen mecanismos de control contra estas plagas; sin embargo, el uso de estos compuestos ha originado problemas de contaminación y quimioresistencia. Los productos naturales representan una alternativa interesante y prometedora para el control integrado de plagas; además, son una vía amigable con el medio ambiente y con los productos derivados de estas actividades. Esta investigación evaluó la actividad deterrente y acaricida de extractos de variedades de quinuas amargas y tarwi; así como de aceites esenciales de molle y muña. La actividad acaricida fue confrontada frente al pesticida sintético amitraz. Después de la obtención de extractos de quinua se estudió la composición proteica de las harinas desaponificadas mediante electroforesis, generando conocimiento de su valor nutricional. Se caracterizaron químicamente los extractos y aceites esenciales empleados en los bioensayos. Sobre E. paunulata resultaron activos los extractos de quinua variedad Markjo y tarwi, y los aceites esenciales de molle y muña; siendo los tres últimos los que mostraron mayor actividad. Ningún extracto mostró actividad sobre S. littoralis. Todas las especies mostraron actividad sobre B. microplus; siendo el aceite esencial de muña y la quinua Markjo los que mostraron alta bioactividad. Casi todas las muestras resultaron ser menos activas que el acaricida químico amitraz; sin embargo, la muña y la quinua Markjo mostraron valores cercanos al amitraz. Las harinas de quinua desaponificadas mostraron similares perfiles polipétidicos; encontrándose bandas con pesos moleculares entre 7,6 y 61,7 kDa. Se identificaron las proteínas Globulina 11S y Albúmina 2S en todas las variedades de quinuas estudiadas. La variedad Markjo presentó el mayor número de especies polipeptídicas y el mayor contenido de proteína soluble.

A nanotecnologia é uma ciência interdisciplinar onde se desenvolve nanomateriais para uso em diversas áreas como a farmácia, cosmética e agroindústria. Um de seus objetivos é aprimorar propriedades de ativos para novas aplicações, por exemplo, através de sistemas para liberação controlada através do uso de biomaterias. Dentre estes biomateriais destaca-se o poliácido lático (PLA) que é constantemente aplicado como matriz polimérica de várias nanoestruturas para o encapsulamento de ativos. Na área cosmética, ativos como os óleos essenciais são de grande interesse. O óleo essencial de pimenta rosa (Schinus molle L.) é composto por terpenos que apresentam, entre outras, atividade antioxidante e inseticida. No presente trabalho desenvolvemos um novo sistema de nanopartículas de PLA em solução aquosa, para liberação controlada do óleo essencial Schinus molle L. visando a utilização cosmética. As nanopartículas de PLA foram avaliadas quanto a estabilidade através da técnica de espalhamento dinâmico de luz (DLS). A formação foi estudada através do uso de difração de raios X (XRD) e espectroscopia vibracional (FTIR). A morfologia foi observada por microscopia eletrônica de varredura (SEM) comparando-se alguns dos resultados obtidos por DLS. Os resultados obtidos mostraram que o sistema é estável por aproximadamente 100 dias quanto ao tamanho, polidispersão e carga de superfície, mesmo com a variação de pH da solução em relação ao tempo. A estabilidade do nanossistema foi atribuída ao tensoativo dodecil sulfato de sódio (SDS), além da própria semicristalinidade e alta massa molar do PLA. Os componentes do sistema apresentaram interações químicas comprovadas por FTIR. O estudo por SEM mostrou que as nanopartículas obtidas têm aparência esférica, com a matriz polimérica contínua e com vários tamanhos constituindo assim um sistema polidisperso, como observadas também por DLS. A eficiência de encapsulação de 83% avaliada por calorimetria exploratória diferencial (DSC) e a liberação do ativo analisada por gravimetria mostraram-se satisfatórias. O sistema de nanopartículas obtido é estável e, por tanto, com potencial adequado para aplicação em produtos cosméticos. / Nanotechnology is an interdisciplinary science through which nanomaterials are developed for use in areas, such as pharmaceutical, cosmetology and agribusiness. One of its objectives is the improvement in the properties of active compounds for new applications by, for example, systems that use biomaterials for controlled release. Lactic polyacid (PLA), one of such biomaterials, has been constantly applied as a polymer matrix of various nanostructures for the encapsulation of active compounds. In cosmetics, active compounds, as essential oils are of great interest. The essential oil of pimenta rosa (Schinus molle L.) is composed of terpenes, which display antioxidant and insecticide activities. This dissertation addresses the development of a new system of PLA nanoparticles in an aqueous solution for the controlled release of essential oil Shinus molle L. to be applied to cosmetology. The stability of PLA nanoparticles was evaluated by dynamic light scattering (DLS). The formation of the system was studied by X-ray diffraction (XRD) and vibrational spectroscopy (FTIR) and its morphology and polydispersivity were verified by scanning electron microscopy (SEM), comparing some of the results obtained by DLS. The results show that the system is stable for approximately 100 days regarding size, polydispersion and surface charge, even when the pH of the solution varies over time. Stability was assigned to surfactant sodium dodecyl sulfate (SDS), PLA\'s semi crystallinity and high molecular weight. The chemical interactions of the system\'s components were evidenced by FTIR. SEM revealed spherical nanoparticles with a continuous polymeric matrix and polydispersivity, also observed by DLS. Satisfactory results were provided by the 83% of encapsulation efficiency calculated by differential scanning calorimetry (DSC) and the drug release analyzed by gravimetric technique. The nanoparticle system obtained is stable and, therefore, suitable for application to cosmetics.

A nanotecnologia é uma ciência interdisciplinar onde se desenvolve nanomateriais para uso em diversas áreas como a farmácia, cosmética e agroindústria. Um de seus objetivos é aprimorar propriedades de ativos para novas aplicações, por exemplo, através de sistemas para liberação controlada através do uso de biomaterias. Dentre estes biomateriais destaca-se o poliácido lático (PLA) que é constantemente aplicado como matriz polimérica de várias nanoestruturas para o encapsulamento de ativos. Na área cosmética, ativos como os óleos essenciais são de grande interesse. O óleo essencial de pimenta rosa (Schinus molle L.) é composto por terpenos que apresentam, entre outras, atividade antioxidante e inseticida. No presente trabalho desenvolvemos um novo sistema de nanopartículas de PLA em solução aquosa, para liberação controlada do óleo essencial Schinus molle L. visando a utilização cosmética. As nanopartículas de PLA foram avaliadas quanto a estabilidade através da técnica de espalhamento dinâmico de luz (DLS). A formação foi estudada através do uso de difração de raios X (XRD) e espectroscopia vibracional (FTIR). A morfologia foi observada por microscopia eletrônica de varredura (SEM) comparando-se alguns dos resultados obtidos por DLS. Os resultados obtidos mostraram que o sistema é estável por aproximadamente 100 dias quanto ao tamanho, polidispersão e carga de superfície, mesmo com a variação de pH da solução em relação ao tempo. A estabilidade do nanossistema foi atribuída ao tensoativo dodecil sulfato de sódio (SDS), além da própria semicristalinidade e alta massa molar do PLA. Os componentes do sistema apresentaram interações químicas comprovadas por FTIR. O estudo por SEM mostrou que as nanopartículas obtidas têm aparência esférica, com a matriz polimérica contínua e com vários tamanhos constituindo assim um sistema polidisperso, como observadas também por DLS. A eficiência de encapsulação de 83% avaliada por calorimetria exploratória diferencial (DSC) e a liberação do ativo analisada por gravimetria mostraram-se satisfatórias. O sistema de nanopartículas obtido é estável e, por tanto, com potencial adequado para aplicação em produtos cosméticos. / Nanotechnology is an interdisciplinary science through which nanomaterials are developed for use in areas, such as pharmaceutical, cosmetology and agribusiness. One of its objectives is the improvement in the properties of active compounds for new applications by, for example, systems that use biomaterials for controlled release. Lactic polyacid (PLA), one of such biomaterials, has been constantly applied as a polymer matrix of various nanostructures for the encapsulation of active compounds. In cosmetics, active compounds, as essential oils are of great interest. The essential oil of pimenta rosa (Schinus molle L.) is composed of terpenes, which display antioxidant and insecticide activities. This dissertation addresses the development of a new system of PLA nanoparticles in an aqueous solution for the controlled release of essential oil Shinus molle L. to be applied to cosmetology. The stability of PLA nanoparticles was evaluated by dynamic light scattering (DLS). The formation of the system was studied by X-ray diffraction (XRD) and vibrational spectroscopy (FTIR) and its morphology and polydispersivity were verified by scanning electron microscopy (SEM), comparing some of the results obtained by DLS. The results show that the system is stable for approximately 100 days regarding size, polydispersion and surface charge, even when the pH of the solution varies over time. Stability was assigned to surfactant sodium dodecyl sulfate (SDS), PLA\'s semi crystallinity and high molecular weight. The chemical interactions of the system\'s components were evidenced by FTIR. SEM revealed spherical nanoparticles with a continuous polymeric matrix and polydispersivity, also observed by DLS. Satisfactory results were provided by the 83% of encapsulation efficiency calculated by differential scanning calorimetry (DSC) and the drug release analyzed by gravimetric technique. The nanoparticle system obtained is stable and, therefore, suitable for application to cosmetics.

Thesis (PhD (Conservation Ecology and Entomology))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Natural and semi-natural ecosystems and human communities worldwide are under siege from a growing number of destructive invasive alien species. Alien species are those whose presence in an area is due to intentional or accidental introduction as a result of human activities. Some alien species become invasive, and some cause tremendous destruction to the ecosystem and their stability, but we do not yet understand fully the many factors that determine the levels of invasiveness in alien species. However, management of alien plants requires a detailed understanding of the factors that make them invasive in their new habitat. The aim of this study was to explore in detail the processes and potential for invasion of Schinus molle (Peruvian pepper tree) into semiarid savanna in South Africa and to examine the potential for this species to invade further in these ecosystems, and in other South African biomes. In this thesis I explored the patterns and processes of invasion of S. molle in semiarid savanna using small-scale experiments to investigate physical and ecological barriers to invasion that prevent or accelerate the invasion of this species. I examined factors such as pollination; seed production; seed dispersal; seed predation and viability, all known to contribute to invasiveness. I highlighted the critical role of microsite conditions (temperature, humidity, water availability) in facilitating S. molle seedling establishment in semi-arid savanna and demonstrated that microsite type characteristics need to be considered for management and monitoring of the species in South Africa. I demonstrated the ability of S. molle to out-compete indigenous woody plants for light and other resources and also showed that disturbance of natural ecosystems was not a prerequisite for invasion, although human activities such as tree planting have played a major role in disseminating this species in South Africa. Predicting the future distribution of invasive species is very important for the management and conservation of natural ecosystems, and for the development of policy. For this reason, I also assessed the present and potential future spatial distribution of S. molle in South Africa by using bioclimatic models and a simulation-based spread model. I produced accurate profiles of environmental conditions (both biophysical and those related to human activities) that characterize the planted and naturalized ranges of this species in South Africa, by linking species determinants, potential habitat suitability and likely spread dynamics under different scenarios of management and climate change. All those components provided insights on the dynamics of invasions by fleshy-fruited woody alien plants in general, and on S. molle invasions in South Africa in particular. I developed a conceptual model that described S. molle population dynamics leading to an understanding of the processes leading to the invasive spread of this species in South Africa. This work also emphasized the need for policy review concerning the invasive status of S. molle in South Africa, and recommendations are made for future research. / AFRIKAANSE OPSOMMING: Die natuurlike and half-natuurlike ekosisteme sowel as menslike gemeenskappe wereldwyd word bedreig deur ‘n groeiende hoeveelheid indringerplantspesies. Indringerplantspesies (daardie spesies wie se teenwoordigheid toegeskryf kan word aan opsetlike of toevallige inbringing deur menslike toedoen) is ‘n bedreiging nie net vanweë die massiewe verwoesting van die ekosisteme en ekosisteemstabilitiet nie, maar ook omdat ons nog nie ten volle verstaan hoe hulle van skaars in hul natuurlike omgewing tot dominant in hul nuwe habitat gaan nie. Bestuur van indringer plante vereis ’n begrip van biologise en ekologiese faktore wat lei tot hulle indringing in die nuwe habitat. Die primêre doel van hierdie studie was om in detail uit te vind wat die prosessesse en potensiaal is vir die indringing van S. molle (die Peruviaanse peper boom) in droë savanna en om indringingspatrone in droë savanna met huidige en potensieële toekomstige patrone in ander Suid-Afrikaanse biome te vergelyk. In hierdie tesis ondersoek ek die patrone en prosesse wat verband hou met die indringing van S. molle in droë savanna deur gebruik te maak van kleinskaalse eksperimente om fisiese en ekologise hindenisse te ondersoek wat indringing van S. molle in Suid-Afrika voorkom of versnel. Dit sluit faktore in wat bekend is om by te dra tot indringing van plant spesies, soos bestuiwing, saadproduksie, saadpredasie en kiemkragtigheid. Ek het die kritieke rol beklemtoon van mikroomgewingskondisies (temperatuur, humiditeit, waterbeskikbaarheid) in die fasilitering van S. molle saailingvestiging in droë savanna en het gedemonstreer dat die tipe mikroomgewingskarakteristieke in ag geneem moet word by betuur en monitering van die verspreiding van S. molle in Suid-Afrika. Ek het die vermoë van S. molle om inheemse plante te uitkompeteer gedemonstreer, en het gewys dat versteuring van natuurlike ekosisteme nie ’n voorvereiste vir S. molle indringing was nie, hoewel menslike aktiwiteite soos boomaanplantings ’n groot rol speel deur by te dra tot indringing van hierdie spesie in Suid-Afrika. Voorspelling van toekomstige verspreiding van indringerspesies is baie belangrik vir die bestuur en bewaring van natuurlike ekosisteme, sowel as vir ontwikkeling van wetgewing. Daarom is die huidige en potensiele toekomstige ruimtelike verspreiding van S. molle in Suid-Afrika bereken deur inkorporering van bioklimaatsmodelle en simulering gebasseer op ’n verspreidingsmodel. Ek het derhalwe akkurate profiele van omgewingstoestande (beide fisiese en daardie wat verband hou met menslike aktiwiteite) wat die aangeplante en natuurlike omvang van die spesie in Suid-Afrika kenmerk geproduseer deur spesiedeterminante, potensieële geskiktheid van habitatte en moontlike verspeidingsdinamika onder verskillende bestuursscenarios en kimaatsverandering te koppel. Al hierdie komponente verskaf insig in die dinamika van die indringing van houtagtige plante met vlesige vrugte oor die algemeen en S. molle in besonder in Suid- Afrika. Hierdie werk beklemtoon ook die behoefte vir hersiening van beleidsrigtings wat betrekking het op die indringerstatus van S. molle in Suid-Afrika en maak aanbevelings vir toekomstige navorsing.

Ce manuscrit est consacré à l'étude de la morphologie et des propriétés physiques de deux fluides complexes : les ferrofluides et les mousses liquides. Dans un premier temps, nous abordons la structuration dans un système formé d'un ferrofluide et l'influence d'un champ magnétique sur le motif adopté. Ensuite, nous étudions les propriétés de mousses liquides magnétiques, en particulier la façon dont elles peuvent être pilotées par un champ magnétique. Puis nous considérons des expériences permettant d'étudier localement la rhéologie de fluides complexes. Enfin, nous étudions la mécanique des mousses liquide à l'échelle de le bulle : vibration d'un film de savon et élasticité d'une jonction entre films de savon.