L'optimisation des états de surface constitue un enjeu majeur pour les biomatériaux utilisés dans le domaine biomédical. Le titane (Ti) et ses alliages à base de nickel (NiTi) restent à ce jour les biomatériaux métalliques de prédilection dans nos applications cliniques en Odontologie (implants dentaires, instruments endodontiques, et arcs orthodontiques). Le but de nos recherche est d'optimiser les surfaces du Ti et NiTi en les fonctionnalisant par des films multicouches de polyélectrolytes (FMP). Notre travail propose d'étudier différents paramètres devant être impérativement validés avant d'envisager une quelconque application biomédicale in vivo avec ce type de revêtement. Une recherche bibliographique exhastive appuie notre recherche expérimentale. Le premier axe du travail propose de déterminer si des FMP peuvent effectivement s'adsorber chimiquement sur le Ti et le NiTi. qui plus est, une étude biologique est réalisée avec des cellules humaines pour tester la biocompatibilité des ces surfaces fonctionnalisées. La deuxième partie se concentre sur la biocompatibilité de la couche précurseur des FMP à base de polyéthyléneimine (PEI). Les résultats mettent en lumière une certaine cytotoxicité de la PEI envers des ostéoblastes et des fibroblastes gingivaux humain. Pour clore ce travail, nous réalisons des essais de stérilisation afin d'évaluer l'influence d'un tel procédé sur les FMP en terme de caractérisations physico-chimique et biologique des surfaces. La perspective d'une application biomédicale avec les FMP semble prometteuse, notamment en y introduisant des molécules bioactives. Cependant, bien d'autres paramètres sont encore à étudier avant d'envisager une application expérimentale et/ou clinique in vivo. Nous pouvons citer par exemple, le vieillissement des FMP, leur comportement en milieu salivaire ou fluoré, ou encore leur résistance à l'usure. Ces différents éléments rentrent dans les perspectives d'un projet post-doctoral. / Optimization of surface properties is a fundamental priority for biomaterials uses in biomedical applications. Titanium (Ti) and nickel-titanium alloys (NiTi) are the references in terms of metallic biomaterials for clinical applications in Odontology (Dental implants, endodontic instrumentations, and orthodontic arches). The aim of our work is to study the Ti and NiTi surfaces coated with polyelectrolytes multilayers films (PEM). Our work study various parameters needed to be validated before using this functionalized surface treatment for biomedical and clinical applictions in vivo. The first part of this work aims at defining the possibility to chemically adsorb PEM coating on Ti and on NiTi surfaces. Moreover, we have realized a biological study with human cells to test the biocompatibility of functionalized surfaces. In the second part of this thesis, we tested the biocompatibility of the multilayered structure in regards to the precursor base layer of PEM, the polyethyleneimine (PEI). Our reuslts show that the PEI is not cytotoxic towards osteoblasts and human gingival fibroblasts. Finally, we relaized tests of sterilization to evaluate PEM stability in terms of physico-chemical and biological surface characterizations. The development of specific biomedical applications for PEM is an exciting perspective, especially when these firms are functionalized with bioactive molecules. However, many other parameters murst be studied before imagining an experimental or clinical application in vivo. As an example, PEM degradation as well as behaviour in salivary or fluoride solution, still needs to be tested.

Made available in DSpace on 2014-06-11T19:35:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-03-24Bitstream added on 2014-06-13T20:06:15Z : No. of bitstreams: 1 zequetto_mm_dr_araca.pdf: 383469 bytes, checksum: 3fd20e10aa2c413edb650399efcff201 (MD5) / No processo de fundição pela cera perdida, os materiais envolvidos podem apresentar interações entre si e o de tempo despendido para se obter as estruturas metálicas é oneroso. Assim, o objetivo deste trabalho foi avaliar a influência da propriedade física de resistência à compressão de revestimentos fosfatados indicados para altas temperaturas de fundição, utilizando os métodos de aquecimento convencional (MAC) e rápido (MAR), e analisar a rugosidade de superfície e a alteração dimensional do produto final da fundição (a peça metálica) obtido com as ligas metálicas Ni-Cr (Verabond II) e Ni-Cr-Ti (Fit Cast Titanium). Os revestimentos estudados Castorit Super C, Castorit All Speed, Heat Shock e Micro Fine 1700 foram vazados em uma matriz de silicone que permitiu obter amostras com formato cilíndrico (n=200), medindo 10mm de diâmetro e 20mm de comprimento. A resistência (MPa) deles foi determinada à temperatura ambiente (resistência fria) após 15, 30 e 60 minutos de manipulação, e também imediatamente após serem submetidos aos métodos de aquecimento MAC e MAR (resistência de queima), por meio de uma máquina de ensaio universal, em velocidade de 0,05mm/min e carga de 150kgf. Após inclusão, aplicação dos métodos de aquecimento e fundição às amostras (n=120) para rugosidade de superfície (Ra-μm), foram avaliadas por um rugosímetro Mitutoyo Surftest SJ-401 com cut-off de 0,8mm e três repetições em cada amostra. A alteração dimensional foi determinada pela diferença entre os valores dimensionais da cera e da peça fundida (n=60) utilizando-se o software AutoCad2008. Os valores médios obtidos foram submetidos à análise de variância (ANOVA) e ao teste de Tukey (p<0,05), apresentando os valores de resistência à compressão diferentes entre os revestimentos (Heat Shock os valores maiores) e entre os tempos de mensuração em relação... / In the lost wax casting procedure, the involved materials can present interactions among them and the time used to obtain the metallic structures is onerous. Thus, the purpose of this study was to evaluate the influence of the compressive strength physical property of phosphate-bonded investment materials indicated for high casting temperatures, utilizing conventional heating (CHM) and quick heating methods (QHM), and analyze the surface roughness and the dimensional accuracy of the final casting product (the metallic piece) obtained from Ni-Cr (Verabond II) and Ni-Cr-Ti (Fit Cast Titanium) metallic alloys. Castorit Super C, Castorit All Speed, Heat Shock and Micro Fine 1700 investment materials were poured into a silicone matrix in order to obtain cylindrical samples (n=200), measuring 10mm in diameter and 20mm in length. Their strength (MPa) was determined at room temperature (green strength) after 15, 30 and 60 minutes of manipulation, and also immediately after being submitted to the CHM and QHM heating methods (fired strength), by means of an universal testing machine at 0,05mm/min speed and 150kgf load. After investing, applying the heating methods and casting the samples (n=120) for surface roughness (Ra), the samples were evaluated with a Mitutoyo Surftest SJ-400 profilometer with 0,8mm cut-off, three times in each sample. The dimensional accuracy was determined by the difference among the dimensional values of the wax and of the metallic piece (n=60) through the software AutoCad2008. The mean values obtained were submitted to ANOVA and Tukey tests (p <0.05), and the results showed that the values of compressive strength were different among the investment materials (Heat Shock presenting the highest values) and among the analysis times with a direct relation of time and strength increase, but there was no difference between CHM and QHM. Moreover, it was observed no differences... (Complete abstract click electronic access below)

O presente estudo in vitro analisou o efeito de 3 sucos de fruta com baixo pH (suco de cupuaçu, taperebá e laranja), e saliva artificial (controle) sobre materiais restauradores indicados em lesões cervicais não cariosas: resina composta nanoparticulada (Filtek Z350 XT), cimento de ionômero de vidro resino modificado (Vitremer) e um cimento de ionômero de vidro convencional (Fuji II). Os materiais foram avaliados, quantitativamente, quanto à alteração de: peso, rugosidade superficial e microdureza superficial, e qualitativamente, por microscopia eletrônica de varredura (MEV). Foram confeccionados 144 corpos de prova para cada teste quantitativo (n=12) e 45 para o MEV (n=3), de (8mm de diâmetro x 2mm de altura). Os corpos de prova foram preparados, mantidos em saliva artificial por 24 h à 37º C, receberam acabamento em politriz, e em seguida foram realizadas as leituras iniciais. Durante um período de 10 dias consecutivos, os corpos de prova foram submetidos ao desafio erosivo (nos respectivos sucos de frutas) durante 30 minutos três vezes ao dia, totalizando 90 minutos/dia e mantidos em saliva artificial entre os intervalos. Após o período de ciclagem erosiva, foram realizadas as leituras finais. Os resultados obtidos foram submetidos ao teste t, ANOVA e Tukey. As médias de alteração entre os valores de peso finais e iniciais demonstraram diferença significativa (p<0,01) nos materiais estudados e em todos os sucos estudados, com exceção do Vitremer quando imerso no suco de taperebá (p>0,01). As médias de alteração entre os valores de rugosidade superficial final e inicial demonstraram diferença significativa (p<0,01) para todos os materiais estudados em todos os sucos, exceto a Filtek Z350 XT no grupo controle que não apresentou diferença significativa (p>0,01). A comparação entre os valores de microdureza final e inicial demonstrou diferença significativa (p<0,01) na microdureza dos materiais estudados em todos os meios de imersão, inclusive no grupo controle. De um modo geral o suco de taperebá foi o que provocou a maior alteração na superfície dos materiais restauradores quanto ao peso, rugosidade, microdureza e na microscopia eletrônica de varredura. A resina composta Filtek Z350 XT foi o material restaurador que menos sofreu alterações de superfície. Concluiu-se que os sucos das frutas estudados são capazes de alterar os materiais restauradores, sendo que a resina composta foi o material que sofreu menor alteração. / This in vitro study examined the effects of 3 fruit juices with low pH (cupuaçu, taperebá and orange) and artificial saliva (control) upon restorative materials indicated in noncarious cervical lesions: nanoparticle composite resin (Filtek Z350 XT), resin-modified glass ionomer cement (Vitremer) and a glass ionomer cement (Fuji II). The materials were evaluated quantitatively as for alterations in weight, surface roughness and surface microhardness, and qualitatively by scanning electronic microscopy (SEM). 144 specimens were prepared for each quantitative test (n = 12) and 45 for the SEM (n = 3), of (8mm diameter x 2mm height). The specimens were prepared, stored in artificial saliva for 24 hours at 37º C, were finished in a polishing machine, and then the initial readings were performed. During a period of 10 consecutive days, the specimens were subjected to erosive challenge (in the respective juices) for 30 minutes, three times a day, and totaling 90 minutes/day and kept in artificial saliva between intervals. After the erosive cycling period, the final readings were taken. The data were analyzed using t test, ANOVA and Tukey.Test The average alterations between the values of initial and final weight showed significant difference (p < 0.01) in the material studied and all the juices studied, except for Vitremer when immersed in taperebá juice (p > 0.01). The average alterations between the values of initial and final surface roughness showed a significant difference (p < 0.01) for all materials studied in all juices, except for Filtek Z350 XT, in the control group, that showed no significant differences (p > 0.01). The comparison between the values of initial and final microhardness showed a significant difference (p < 0.01) in microhardness of the materials studied in all immersion means, including the control group. In general, taperebá juice was the one that caused the biggest alterations in the surface of restorative materials with respect to weight, roughness, hardness and scanning electronic microscopy. The composite resin Filtek Z350 XT was the restorative material that suffered less surface alterations. It was concluded that the fruit juices studied are capable of altering the restorative materials, and composite resin was the material that has undergone minor changes.

Les effluents industriels issus des activités de textile présentent souvent une importante charge polluante colorante difficilement biodégradable. Des travaux antérieurs ont montré le potentiel des argiles naturelles non traitées à dépolluer ces effluents teinturiers alors qu’ils sont généralement composés de colorants anioniques difficilement adsorbables sur ces supports. Or, les effluents contiennent également d’autres composés chimiques utilisés dans les différentes étapes du procédé de teinture, et qui sont de natures variées (sels, acides, bases, détergents, dérivés enzymatiques, etc…). Il semblerait que ces produits auxiliaires jouent un rôle dans l'adsorption de colorants anioniques sur l'argile non traitée. Cependant, aucune étude connue à ce jour, n'a porté sur l'effet des additifs de teinture dans le processus de décoloration par des absorbants en général, et par les argiles en particulier. Cette étude est la première à s’intéresser au système colorant-additif-argile. Des tests d’adsorption / désorption en batch ont été menés en considérant différents systèmes colorant-additif-argile. Les résultats des tests montrent que les additifs de type enzymatique favorisent l’adsorption de colorant anionique sur l’argile en neutralisant les charges négatives et en renforçant les liaisons argile-colorant. D’autres additifs ont un effet contraire mais n’annulent pas l’effet positif des additifs enzymatiques lorsqu’ils sont mélangés dans l’effluent. Des hypothèses d’interactions mises en jeu lors de l’adsorption de colorant ont été faites en s’aidant des résultats de la spectrométrie infra-rouge et de masse, de la zétamétrie et de la modélisation des isothermes d’adsorption. / Industrial effluents from textile activities often have a high pollution load readily biodegradable. Previous work has shown the potential of natural untreated clays to clean up these dyers effluents although anionic dyes are not easily absorbable on these media. The effluents also contain other chemical compounds used in the different stages of the dyeing process, and which are of various natures (salts, acids, bases, detergents, enzyme derivatives, etc ...). It appears that these auxiliary products play a role in the adsorption of anionic dyes on untreated clay. However, no currently known study has examined the effect of the additives from the dyeing process on the adsorption of dye onto clay. This is the first study to focus on the dye-clay-additive system. Adsorption / desorption batch tests were conducted considering different dye additive-clay systems. The tests’ results show that the enzyme like additives enhance the adsorption of anionic dye on the clay by neutralizing the negative charges and reinforcing clay-dye links. Other additives have the opposite effect, but do not offset the positive effect of enzyme like additives when mixed in the effluent. Assumptions of interactions involved in dye adsorption were made with the help of the results of infrared and mass spectrometry, zetametry and the modeling of adsorption isotherms.

This thesis ventures with the extracellular matrix protein (ECM) fibronectin (FN) as an interface protein in the interaction between cells and materials to design microenvironment for future use in tissue engineering. It is studied the FN adsorption and conformations, cell behaviour to different FN conformation, cell adhesion, reorganisation and remodelling of FN at the material interface, the role of growth factors (GF) and their interactions with components of the extracellular matrix (ECM), the immunology cell response, and the stem cell fate influenced by the extrinsic signals coming from the engineered microenvironments using ECM's proteins. To investigate the FN response, in terms of adsorbed amount and conformation to different chemical properties of the material, model surfaces were used. Self assembled monolayers (SAM) with different percentages of two different chemical groups were used: CH3 and OH. FN adsorption, initial cell adhesion and signalling (focal adhesions, integrin expression and phosphorylation of FAK) is related with the reorganisation and secretion of FN and matrix degradation. It is shown that matrix degradation at the cell material interface depends on surface chemistry in metalloproteinase-dependent way. A direct relationship between FN activity at the cell-material interface and metalloproteinase 9 (MMP9) expression was found, being the product of a sequence of events that include integrin expression, focal adhesion formation, matrix reorganisation and focal adhesion kinase (FAK) phosphorylation. Two different materials with subtle variations in their chemical composition were employed as a drastically different FN conformation: from a globular conformation on PMA (poly (methyl acrylate)) to the formation of a well-interconnected FN network (similar to the FN physiological fibrillar network) triggered by PEA (poly (ethyl acrylate)). The formation of focal adhesions (vinculin), FAK expression and phosphorylation, specific integrin binding, protein and gene expression for ¿5 and ¿v was studied, seeking to correlate cell adhesion with matrix degradation. It is demonstrated that the material-driven FN fibrillogenesis on PEA triggers proteolytic activity: MMP activity is higher as a compensatory mechanism to the inability of cells to reorganise this FN network. Looking into the role of protein-material interactions and stem cell fate, and with the knowledge on PEA, we engineer different synergistic microenvironments to direct cell and stem cell fate. FN has a growth factor (GF) binding domain on its molecule (FNIII12-14) and has been demonstrated to produce a synergistic response when occurs at the same time the recognition of the cell binding domain (FNIII9-10). It is demonstrated that this domain is available on the FN coated PEA, and exploiting these interactions between PEA, FN and GF, it is developed a microenvironment to control cell behaviour and tissue repair. It is studied the BMP2 binding and presentation, the effect of BMP2 presentation on MSC proliferation and differentiation. These systems allow not only enhanced activity of GF compared to soluble administration, but also reduce GF doses, improving safety and cost effectiveness. Finally, the immunological reaction of the microenvironment developed is studied using dendritic cells, beside the conformational structure of ECM protein importance in DC integrin-based activation it is studied, helping to establish the field of adhesion-based modulation of DC as a general mechanism that has previously not been defined. The microenvironment didn't induce any maturation in DC, while different FN conformation shows differences in DC morphology and citokine level production (IL-10 and IL-12). / En esta tesis se estudia la interacción de una proteina de la matriz extracelular, fibronectina (FN) como interfase en la interacción entre células y materiales, para diseñar microambientes con el propósito de ser usados en el futuro en ingeniería tisular. Se estudia la adsorción y conformación de FN y la relación con el diferente comportamiento celular: la adhesión celular, la reorganización y remodelado de la FN en la interfase célula-material, el papel que juegan los factores de crecimiento y sus interacciones con los componentes de la matriz extracelular, la respuesta immunológica y el destino celular de células madre influenciadas por las señales extrínsecas provenientes de microambientes elaborados a partir de proteínas de la matriz extracelular. Con el objetivo de investigar la respuesta a la FN en términos de conformación y cantidad absorbida a diferentes propiedades químicas del material, se usaron materiales modelo: monocapas autoensambladas (self-assembled monolayers, SAM). Las químicas estudiadas fueron CH3 and OH. La adsorption de FN, adhesion y señalización (adhesiones focales, expresión de interinas y fosforilación de quinasas de adhesiones focales (FAK)) se estudiaron en relación a la reorganización y secreción de FN y degradación de la matriz extracelular. Se demuestra que la degradación de la matriz extracelular en la interfase célula-material depende de la química de la superficie, a través de las metaloproteinasas. Se ha descubierto una relación directa entre la actividad de la FN que se encuentra en el material y la expresión de metaloproteinasa 9 (MMP9), a través de la expresión de integrinas, formación de adhesiones focales, reorganización de la matriz extracelular y fosforilación de FAK En el siguiente capítulo se emplean materiales poliméricos con una sutil diferencia en la composición química, provocando una diferencia drástica en la conformación de la FN: se pasa de una conformación globular en PMA (polimetil acrilato) a una conformación en forma de red interconectada en PEA (polietil acrilato). Con el propósito de relacionar la adhesión celular con la degradación de la matriz extracelular, se estudia la formación de adhesiones focales (vinculina), la expresión y fosforilación de FAK, la unión específica de integrinas y la expresión de las integrinas ¿5 and ¿v. Se demuestra que la formación de una red de FN sobre PEA induce la actividad proteolítica: la actividad de las MMPs es mayor, actuando como mecanismo compensatorio a la incapacidad de reorganización de la red de FN. Haciendo uso de la conformación de la FN sobre PEA, se estudiaron las interacciones entre la proteína-material y el destino celular de células madres. La FN posee un dominio de unión de factores de crecimiento (FNIII12-14) y se ha demostrado que se produce una respuesta sinérgica cuando el reconocimiento ocurre junto con el dominio de unión celular (FNIII9-10). En esta tesis se demuestra que el dominio de unión de factores de crecimiento está disponible en la conformación que adquiere sobre PEA y se diseñan microambientes para controlar el comportamiento celular y regeneración de tejido. Se estudia la unión y presentación de BMP2 y su efecto en la diferenciación de células madre mesenquimales. Los microambientes desarrollados, ademas de mejorar la actividad de los factores de crecimiento comparado con la administración soluble, también reduce la cantidad de factores de crecimiento que se tendría que administrar, mejorando la seguridad y efectividad. Finalmente se estudió la reacción inmunológica a los microambientes desarrollados usando células dendríticas, estudiando además la influencia de la estructura de la conformación de las proteínas en la activación de las células dendríticas a través de las integrinas. Los microambientes no indujeron ninguna maduración de células dendríticas, mientras que la conformación de la FN muestra control / En aquesta tesi s'estudia la interacció entre una proteïna de la matriu extracel.lular, fibronectina (FN) com interfase en la interaccio entre cèl·lules i materials, per a dissenyar microambients amb el propòsit d'utilitzar-se al futur en enginyeria tissular. S'estudia l'adsorció i conformació de la FN i la relació amb el diferent comportament cel·lular: l'adhesió cel·lular, la reorganització i remodelat de la FN a la interfase cèl·lula-material, el paper que juguen els factors de creixement i les seus interaccions amb els components de la matriu extracel·lular, la resposta immunològica i el destí cel·lular de cèl·lules mare influenciades pels senyals extrínseques provinents de microambients elaborats a partir de proteïnes de la matriu extracel·lular. Amb l'objectiu d'investigar la respostar a la FN en termes de conformació i quantitat absorbida a diferents propietats químiques del material, s'utilitzaren materials model: monocapes autoacoblades (self-assembled monolayers, SAM). Les químiques estudiades van ser CH3 and OH. L'absorció de FN, adhesió i senyalització (adhesions focals, expressió d'integrines i fosforilació de quinases d'adhesions focals (FAK)) es van estudiar en relació a al reorganització i secreció de la FN i degradació de la matriu extracel·lular. Es demostra que la degradació de la matriu extracelular en la interfase cèl·lula-material depèn de la química de la superficie, a través de les metal·loproteïnases. S'ha descobert una relació directa entra l'activitat de la FN que es troba en el material i l'expressió de metaloproteinasa 9, a través de l'expressió d'integrines, formació d'adhesions focals, reorganització de la matriu extracel·lular i fosforilació de FAK. Al següent capítol es fan servir materials polimèrics amb una subtil diferència en la composició química, provocant una diferència dràstica en la conformació de la FN: es passa d'una conformació globular en PMA (polimetil acrilat) a una conformació en forma de xarxa interconnectada en PEA (polietil acrilat). Amb el propòsit de relacionar l'adhesió cel·lular amb la degradació de la matriu extracel·lular, s'estudia la formació d'adhesions focals (vinculina), l'expressió i fosforilació de FAK, la unió específica d'integrines i l'expressió de les integrines ¿5 and ¿v. Es demostra que la formació d'una xarxa de FN sobre PEA indueix l'activitat proteolítica: l'activitat de les MMPs és més gran, actuant com a mecanisme compensatori a la incapacitat de reorganització de la xarxa de FN. Fent ús de la conformació de la FN sobre PEA, es van estudiar les interaccions entre la proteïna-material i el destí cel·lular de cèl·lules mares. La FN posseeix un domini d'unió de factors de creixement (FNIII12-14) i s'ha demostrat que es produeix una resposta sinèrgica quan el reconeixement ocurreix juntament amb el domini d'unió cel·lular (FNIII9- 10). En aquesta tesi es demostra que el domini d'unió de factors de creixement està disponible a la conformació que adquireix sobre PEA i es dissenyen microambients per controlar el comportament cel·lular i regeneració de teixit. S'estudia la unió i presentació de BMP2 i el seu efecte en la diferenciació de cèl·lules mare mesenquimals. Els microambientes desenvolupats, a més de millorar l'activitat dels factors de creixement comparat amb l'administració soluble, també redueix la quantitat de factors de creixement que s'hauria d'administrar, millorant la seguretat i efectivitat. Finalment es va estudiar la reacció immunològica als microambients desenvolupats usant cèl·lules dendrítiques, estudiant a més la influència de l'estructura de la conformació de les proteïnes en l'activació de les cèl·lules dendrítiques a través de les integrines. Els microambients no van induir cap maduració de cèl·lules dendrítiques, mentre que la conformació de la FN mostra controlar la morfologia de les cèl·lules dendrítiques i / Llopis Hernández, V. (2017). Material-driven fibronectin fibrillogenesis to engineer cell function [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/90412 / TESIS

Die Siliciumauflösung in Flusssäure-Wasserstoffperoxid- und Flusssäure-Ozon-Lösung ist aufgrund der, aus der Oxidation des Siliciums, formal resultierenden Reaktionsprodukte Wasser und Sauerstoff interessant. Der Auflösungsprozess, speziell die Oxidation des Siliciums / Elektronenlochinjektion ins Siliciumvalenzband, wird – verglichen mit anderen Ätzsystemen für Silicium – massiv kinetisch gehemmt. Ätzprozesse auf Basis dieser Mischungen sind hinsichtlich der geringen bzw. moderaten erzielbaren Siliciumabtragsraten (rSi < 0,02 nm s-1 mit Rissaufweitung in Flusssäure-Wasserstoff-peroxid-Lösungen bzw. rSi < 0,61 nm s-1 mit Oberflächenpolitur in Flusssäure-Ozon-Lösungen) wenig effektiv. Eine Erhöhung der Siliciumabtragsraten gelingt prinzipiell durch die Erhöhung der Konzentrationen siliciumoxidierender Spezies in der Silicium / Elektrolyt-Grenzfläche oder durch Zufügen geeigneter grenzflächenaktiver Elektronenüberträgerspezies. In stark sauren Lösungen wird der Elektronentransfer zusätzlich durch stabilisierende Wasserstoffaustauschprozesse inhibiert. Die Mischungen sind zur Reinigung von Siliciumwaferoberflächen oder feinteiligem Silicium geeignet.:1. Motivation und Problemstellung 5 2. Halbleiterrelevante Eigenschaften von Silicium 9 2.1 Siliciumoberflächen 9 2.2 Silicium als Halbleiter 14 2.3 Silicium in Elektrolyt-Lösungen 17 2.3.1 Silicium / Elektrolyt-Kontakt 17 2.3.2 Silicium in Flusssäurelösungen 20 2.4 Oxidation von Siliciumoberflächen in Elektrolytlösungen 23 2.4.1 Elektronentransfer beim Silicium / Elektrolyt-Kontakt 24 2.4.2 Chemische Oxidation von Silicium 27 3. Siliciumätzverfahren 32 4. Nasschemische Siliciumauflösung in wässrigen Flusssäure-haltigen Lösungen 35 4.1 Elektrochemische Siliciumauflösung 37 4.2 Außenstromlose Siliciumauflösung in sauren Lösungen 41 4.2.1 Stromlose elektrochemische Siliciumauflösung 41 4.2.2 Metall-assistierte Siliciumauflösung 44 4.2.3 Chemische Siliciumauflösung 48 4.2.4 Ausgewählte Abtragsraten zur sauren nasschemischen Siliciumbehandlung 49 4.3 Anisotropie-Effekte bei der nasschemischen Siliciumauflösung 51 5. Silicium in Flusssäure-Wasserstoffperoxid-basierten Ätzlösungen 54 5.1 Silicium in wässrigen Flusssäure-Wasserstoffperoxid-Lösungen 54 5.1.1 Reaktivitäten wässriger Flusssäure-Wasserstoffperoxid-Lösungen gegenüber Silicium 55 5.1.2 Formalkinetische Untersuchungen des Ätzprozesses 58 5.1.3 Eigenschaften der Siliciumoberflächen: Morphologie und Bindungssituation 64 5.1.4 Poröses Silicium in wässrigen Flusssäure-Wasserstoffperoxid-Lösungen (außenstromlos) 66 5.2 Stimulierung des Prozesses der Siliciumauflösung in wässrigen Flusssäure-Wasserstoffperoxid-Lösungen 71 5.2.1 Auswirkungen ausgewählter „Verunreinigungen“ der Ätzlösungen 73 5.2.2 Stimulierung durch zusätzliche Oxidationsmittel 74 5.2.3 Stimulierung durch potenzielle Elektronenüberträger 80 5.3 Silicium in Flusssäure-Wasserstoffperoxid-Schwefelsäure-Lösungen 90 5.3.1 Eigenschaften von Flusssäure-Wasserstoffperoxid-Schwefelsäure-Lösungen 90 5.3.2 Reaktivitäten von Flusssäure-Wasserstoffperoxid-Schwefelsäure-Lösungen 94 5.3.3 Eigenschaften der erzeugten Siliciumoberflächen 101 5.4 Silicium in Flusssäure-Wasserstoffperoxid-Salzsäure-Lösungen 106 5.5 Oxidation der Siliciumoberfläche in Wasserstoffperoxid-basierten Lösungen 109 5.6 Schlussfolgerungen zur Siliciumauflösung in Flusssäure-Wasserstoffperoxid-basierten Ätzlösungen 113 5.7 Anwendungspotenziale Flusssäure-Wasserstoffperoxid-basierter Ätzlösungen 116 6. Silicium in wässrigen Flusssäure-Ozon-basierten Ätzlösungen 123 6.1 Silicium in Flusssäure-Ozon-Lösungen 129 6.2 Silicium in Flusssäure-Ozon-Schwefelsäure-Lösungen 137 6.3 Silicium in Ozon-durchleiteten Flusssäure-Salzsäure-Lösungen 141 6.4 Oxidation der Siliciumoberfläche in Ozon-haltigen Lösungen 147 6.5 Schlussfolgerungen zur Siliciumauflösung in Flusssäure-Ozon-basierten Ätzlösungen 152 6.6 Anwendungspotenziale Flusssäure-Ozon-basierter Ätzlösungen 158 7. Zusammenfassung 162 8. Experimenteller Teil 166 8.1 Grundlagen 166 8.2 Chemikalien und Siliciumsubstrate 167 8.3 Charakterisierungsmethoden und Geräte 171 8.4 Konzentrationsbestimmungen in wässrigen Lösungen 174 8.5 Ätzlösungen und Abtragsraten 177 8.6 Daten zu den einzelnen Versuchen 180 8.6.1 Flusssäure-Wasserstoffperoxid-haltige Lösungen 180 8.6.2 Flusssäure-Ozon-haltige Lösungen 191 8.6.3 Daten der XPS-Untersuchungen 198 8.6.4 Reinigung von Siliciumsubstraten 208 9. Anhang 211 A Abkürzungsverzeichnis 211 B Literaturverzeichnis 212 C Tabellen / Literaturvergleichswerte 227 E Sonstiges 233 E.1 Eidesstattliche Erklärung 233 E.2 Publikationen 234 E.4 Danksagung 240

Objetivo: Comparar in vitro la rugosidad superficial de resinas Bulk Fill sometidos a diferentes sistemas de pulido. Materiales y métodos: Noventa especímenes de resinas compuestas: Tetric® N-Ceram Bulk Fill (TNC), Filtek™ Bulk Fill (FB) y Opus Bulk Fill (OBF) fueron divididos en 9 grupos (n=10). Cada grupo fue sometido a un sistema de pulido: Cauchos Politip (CP), Discos Sof-lex™ (DS) y Discos Diamond Pro (DDP). La rugosidad superficial inicial y final fue evaluada mediante un rugosímetro. Los datos fueron analizados mediante estadística descriptiva (media ± d.e) y para la comparación de diferencias de rugosidad inicial y final se utilizó la prueba de Kruskal Wallis (p<0.05). Resultados: La rugosidad superficial inicial (media + d.e, CP/DS/DDP) fue: TNC (1.23± 1.30µm/0.94±0.53µm/0.90±0.57µm); FB (0.53±1.29µm/0.59±0.54µm/0.63±0.26µm) y OBF (0.74±0.50µm/0.96±0.62µm/0.65±0.25µm). La rugosidad final fue: TNC (0.19± 0.04µm/0.32±0.23µm/0.28±0.22µm); FB (0.29±0.17µm/0.22±0.19µm/0.25±0.19µm) y OBF (0.15±0.05µm/0.26±0.24µm/0.20±0.14µm). No se encontraron diferencias estadísticamente significativas entre la rugosidad inicial y la rugosidad final TNC (p=0.479); FB (p=0.163) y OBF (p=0.919). Conclusión: Existe una disminución en los valores de rugosidad superficial de las resinas Bulk Fill evaluadas después de ser sometidas a tres sistemas de pulidos. / Aim: To compare in vitro the surface roughness of Bulk Fill resins using different polishing systems. Materials and methods: Ninety specimens: Tetric® N-Ceram Bulk Fill (TNC), Filtek™ Bulk Fill (FB) and Opus Bulk Fill (OBF) were divided into 9 groups (n=10). Each group was polished using a different polishing system: Politip Polishers (PP), Sof-lex Polishing Discs™ (SPD) and Diamond Pro Sandpaper Disk (DPSD). The initial and final roughness were assessed using a profilometer. The results were analyzed using descriptive statistics (mean ±s.d) and for the comparison of differences in initial and final roughness was analyzed using the Kruskal Wallis test (p<0.05). Results: The initial surface roughness (mean ± s.d, PP/SPD/DPSD) was: TNC (1.23 ±1.30um/0.94±0.53um/0.90±0.57um); FB (0.53±1.29um/0.59±0.54um/0.63±0.26um) and OBF (0.74±0.50um/0.96±0.62um/0.65±0.25um). The final surface roughness was: TNC (0.19±0.04um/0.32±0.23um/0.28±0.22um); FB (0.29±0.17um/0.22±0.19um/0.25±0.19um) and OBF (0.15±0.05um/0.26±0.24um/0.20±0.14um). There were no significant differences between the initial and the final roughness measurements: TNC (p=0.479); FB (p=0.163) and OBF (p=0.919). Conclusion: There is a minor decrease in the surface roughness measurements of the Bulk Fill resins after using three different polishing systems. / Tesis

No / Methods of recycling unplasticized polyvinyl chloride (uPVC) window frame waste were investigated. The quality of untreated granular waste was compared to that of waste treated by a range of contaminant removal processes including melt filtration and dissolution. Processability of each recyclate was evaluated by using a highly instrumented single screw extruder that enabled melt viscosity and process variation to be monitored in real time. Product quality measurements such as mechanical properties and surface defects were made on extruded strip, and the nature of the stabilizers present was determined. The mechanical properties of recyclates were found to be comparable to or better than those of virgin material in all cases and conformed to industry standards for window profile. Contaminant removal stages significantly reduced the amount of large surface defects detected in extrudate. Processability was comparable to that of virgin compounds, but melt viscosity varied among different batches of recyclate, depending on the source and composition of the original PVC formulation.

This work is devoted to understanding the formation of supported lipid bilayers (SLBs) on curved surfaces as a function of lipid properties such as headgroup charge/charge density and alkyl chain length, and nanoparticle properties such as size and surface characteristics. In particular, the formation of SLBs on curved surfaces was studied by varying the size of the underlying substrate SiO2 nanoparticles with size range from 5-100 nm. Curvature-dependent shift in the phase transition behavior of these supported lipid bilayers was observed for the first time. We found that the phase transition temperature, Tm of the SLBs first decreased with decreasing the size of the underlying support, reached a minimum, and then increased when the size of the particles became comparable with the dimensions of the lipid bilayer thickness; the Tm was above that of the multilamellar vesicles (MLVs) of the same lipids. The increase in Tm indicated a stiffening of the supported bilayer, which was confirmed by Raman spectroscopic data. Moreover, Raman data showed better lipid packing and increased lateral order and trans conformation for the SLBs with increasing the curvature of the underlying support and decrease of the gauche kinks for the terminal methyl groups at the center of the bilayer. These results were consistent with a model in which the high free volume and increased outer headgroup spacing of lipids on highly curved surfaces induced interdigitation in the supported lipids. These results also support the symmetric lipid exchange studies of the SLBs as a function of the curvature, which was found to be slower on surfaces with higher curvature. Further, the effect of surface properties on the formation of SLBs was studied by changing the silanol density on the surface of SiO2 via thermal/chemical treatment and monitoring fusion of zwitterionic lipids onto silica (SiO2) nanoparticles. Our findings showed that the formation of SLBs was faster on the surfaces with lower silanol density and concomitantly less bound water compared to surfaces with higher silanol density and more bound water. Since the two SiO2 nanoparticles were similar in other respects, in particular their size and charge (ionization), as determined by zeta potential measurements, differences in electrostatic interactions between the neutral DMPC and SiO2 could not account for the difference. Therefore the slower rate of SLB formation of DMPC onto SiO2 nanoparticles with higher silanol densities and more bound water was attributed to greater hydration repulsion of the more hydrated nanoparticles. Lastly, we have investigated the effect and modulation of the surface charge of vesicles on the formation of SLBs by using different ratios of zwitterionic and cationic DMPC/DMTAP lipids. Through these studies we discovered a procedure by which assemblies of supported lipid bilayer nanoparticles, composed of DMPC/DMTAP (50/50) lipids on SiO2, can be collected and released from bilayer sacks as a function of the phase transition of these lipids. The lipids in these sacks and SLBs could be exchanged by lipids with lower Tm via lipid transfer. / Chemistry

Self-emulsifying systems are mixtures of oils and surfactants, ideally isotropic, sometimes including cosolvents, which emulsify under conditions of gentle agitation, similar to those which would be encountered in the gastrointestinal tract. The process of self-emulsification has remained the center of attraction for most researchers. Controlled hydration of self-emulsifying systems shows formation of an intermediate gel phase which upon rupture forms an emulsion. Current work was undertaken to understand and explore the microstructural properties of intermediate gel phase which are believed to influence the performance (droplet size) of the final formulation. The effect of additives on microstructural properties of intermediate gel phase has also been investigated. Microstructural elucidation of hydrated samples of intermediate regimes was done by using techniques such as small angle X-ray scattering, differential scanning calorimetry and rheology. Samples from intermediate regimes showed formation of local lamellar structure which swelled with hydration. In the present work, the effect of addition of salt form of naproxen (sodium and potassium) and naproxen (base) on microstructural properties of intermediate regimes was investigated. Systems containing naproxen salts formed larger droplets whereas naproxen base formed smaller ones. Microstructural properties of intermediate lamellar structures were well correlated with performance of the final formulation. The current studies indicate that by controlling the properties of intermediate regimes optimized formulations with desired performance can be tailor-made.