Dissertations / Theses on the topic 'BCB polymer'

Semiconductor wafer bonding has been a subject of interestfor many years and a wide variety of wafer bonding techniqueshave been reported in literature. In adhesive wafer bondingorganic and inorganic adhesives are used as intermediatebonding material. The main advantages of adhesive wafer bondingare the relatively low bonding temperatures, the lack of needfor an electric voltage or current, the compatibility withstandard CMOS wafers and the ability to join practically anykind of wafer materials. Adhesive wafer bonding requires nospecial wafer surface treatmentssuch as planarisation.Structures and particles at the wafer surfaces can be toleratedand compensated for some extent by the adhesive material.Adhesive wafer bonding is a comparably simple, robust andlowcost bonding process. In this thesis, adhesive wafer bondingtechniques with different polymer adhesives have beendeveloped. The relevant bonding parameters needed to achievehigh quality and high yield wafer bonds have been investigated.A selective adhesive wafer bonding process has also beendeveloped that allows localised bonding on lithographicallydefined wafer areas.

Adhesive wafer bonding has been utilised in variousapplication areas. A novel CMOS compatible film, device andmembrane transfer bonding technique has been developed. Thistechnique allows the integration of standard CMOS circuits withthin film transducers that can consist of practically any typeof crystalline or noncrystalline high performance material(e.g. monocrystalline silicon, gallium arsenide,indium-phosphide, etc.). The transferred transducers or filmscan be thinner than 0.3 µm. The feature sizes of thetransferred transducers can be below 1.5 µm and theelectrical via contacts between the transducers and the newsubstrate wafer can be as small as 3x3 µm2. Teststructures for temperature coefficient of resistancemeasurements of semiconductor materials have been fabricatedusing device transfer bonding. Arrays of polycrystallinesilicon bolometers for use in uncooled infrared focal planearrays have been fabricated using membrane transfer bonding.The bolometers consist of free-hanging membrane structures thatare thermally isolated from the substrate wafer. Thepolycrystalline silicon bolometers are fabricated on asacrificial substrate wafer. Subsequently, they are transferredand integrated on a new substrate wafer using membrane transferbonding. With the same membrane transfer bonding technique,arrays of torsional monocrystalline silicon micromirrors havebeen fabricated. The mirrors have a size of 16x16 µm2 anda thickness of 0.34 µm. The advantages of micromirrorsmade of monocrystalline silicon are their flatness, uniformityand mechanical stability. Selective adhesive wafer bonding hasbeen used to fabricate very shallow cavities that can beutilised in packaging and component protection applications. Anew concept is proposed that allows hermetic sealing ofcavities fabricated using adhesive wafer bonding. Furthermore,microfluidic devices, channels and passive valves for use inmicro total analysis systems are presented.

Adhesive wafer bonding is a generic CMOS compatible bondingtechnique that can be used for fabrication and integration ofvarious microsystems such as infrared focal plane arrays,spatial light modulators, microoptical systems, laser systems,MEMS, RF-MEMS and stacking of active electronic films forthree-dimensional high-density integration of electroniccircuits. Adhesive wafer bonding can also be used forfabrication of microcavities in packaging applications, forwafer-level stacking of integrated circuit chips (e.g. memorychips) and for fabrication of microfluidic systems.

Les travaux menés dans le cadre de cette thèse proposent de tirer profit des nouvelles technologies disponibles pour répondre aux besoins de la montée en fréquence et de la miniaturisation des systèmes de communication tout en améliorant le niveau des performances. Les études se sont axées vers la conception d'une structure à mélangeur de réjection de fréquence image permettant de relâcher les contraintes sur les structures critiques de filtrage amont. L'intégration des parties actives et passives de ce système, a ainsi été menée avec comme objectifs de tirer au maximum partie des potentialités de chaque technologie, de proposer des solutions techniques pour palier aux inconvénients de chaque technologie, et d'optimiser l'architecture globale en partitionnant le système suivant les contraintes technologiques et/ou techniques. La première partie des travaux a ainsi porté sur le développement en bande K d'une nouvelle topologie de mélangeur à base de transistors à hétérojonction Si-SiGe à linéarité améliorée. Se basant sur une compréhension des phénomènes intrinsèques du circuit, des topologies modifiées ont de plus été proposés afin de repousser l'ensemble des performances atteignables sur cette technologie. La seconde partie des travaux concerne la conception de coupleurs passifs, toujours en bande K, avec pour objectif la miniaturisation maximale de ces fonctions. Une méthodologie de conception a, dans ce cadre, été développée et validée par une intégration sur une technologie spécifiquement développée au LAAS-CNRS et compatible avec une future intégration avec les circuits actifs. Nous avons ainsi obtenu des performances optimales (à l'état de l'art) avec un gain d'intégration d'un facteur 2. Enfin, en amont et en aval de ces travaux, une étude sur l'architecture globale du système de mélangeur à réjection de fréquence image a été conduite, et sans cesse raffinée, afin de partitionner les contraintes de performances entre les différents blocs et de vérifier l'obte ntion des performances.

In this work new fluorinated and non-fluorinated mono- and bifunctional trithiocarbonates of the structure Z-C(=S)-S-R and Z-C(=S)-S-R-S-C(=S)-Z were synthesized for the use as chain transfer agents (CTAs) in the RAFT-process. All newly synthesized CTAs were tested for their efficiency to moderate the free radical polymerization process by polymerizing styrene (M3). Besides characterization of the homopolymers by GPC measurements, end- group analysis of the synthesized block copolymers via 1H-, 19F-NMR, and in some cases also UV-vis spectroscopy, were performed attaching suitable fluorinated moieties to the Z- and/or R-groups of the CTAs. Symmetric triblock copolymers of type BAB and non-symmetric fluorine end- capped polymers were accessible using the RAFT process in just two or one polymerization step. In particular, the RAFT-process enabled the controlled polymerization of hydrophilic monomers such as N-isopropylacrylamide (NIPAM) (M1) as well as N-acryloylpyrrolidine (NAP) (M2) for the A-blocks and of the hydrophobic monomers styrene (M3), 2-fluorostyrene (M4), 3-fluorostyrene (M5), 4-fluorostyrene (M6) and 2,3,4,5,6-pentafluorostyrene (M7) for the B-blocks. The properties of the BAB-triblock copolymers were investigated in dilute, concentrated and highly concentrated aqueous solutions using DLS, turbidimetry, 1H- and 19F-NMR, rheology, determination of the CMC, foam height- and surface tension measurements and microscopy. Furthermore, their ability to stabilize emulsions and microemulsions and the wetting behaviour of their aqueous solutions on different substrates was investigated. The behaviour of the fluorine end-functionalized polymers to form micelles was studied applying DLS measurements in diluted organic solution. All investigated BAB-triblock copolymers were able to form micelles and show surface activity at room temperature in dilute aqueous solution. The aqueous solutions displayed moderate foam formation. With different types and concentrations of oils, the formation of emulsions could be detected using a light microscope. A boosting effect in microemulsions could not be found adding BAB-triblock copolymers. At elevated polymer concentrations, the formation of hydrogels was proved applying rheology measurements.
Im Rahmen dieser Arbeit wurden neue fluorierte und unfluorierte mono- und bifunktionelle Trithiocarbonate der Typen Z-C(=S)-S-R und Z-C(=S)-S-R-S-C(=S)-Z zur Anwendung als CTAs (chain- transfer agents) im RAFT-Polymerisationsverfahren hergestellt. Alle CTAs wurden erfolgreich auf ihre Effizienz zur Steuerung des radikalischen Polymerisationsverfahrens hin durch Polymerisation von Styrol (M3) getestet. Neben GPC-Messungen wurden Endgruppenanalysen der synthetisierten Blockcopolymere mittels 1H-, 19F-NMR und in manchen Fällen auch UV-Vis Spektroskopie durchgeführt. Dazu wurden die Z- und/oder R-Gruppen der CTAs mit geeigneten fluorierten Gruppen versehen. Durch Anwendung des RAFT Verfahrens konnten symmetrische Triblockcopolymere vom Typ BAB bzw. mit einer Fluoralkylgruppe endgecappte unsymmetrische Polymere in nur zwei bzw. einem Polymerisationsschritt hergestellt werden. Das RAFT- Polymerisationsverfahren ermöglicht sowohl die Polymerisation hydrophiler Monomere wie N-Isopropylacrylamid (NIPAM) (M1) oder N-Acryloylpyrrolidin (NAP) (M2) für die A-Blöcke als auch der hydropoben Monomere Styrol (M3), 2-Fluorostyrol (M4), 3-Fluorostyrol (M5), 4- Fluorostyrol (M6) und 2,3,4,5,6- Pentafluorostyrol (M7) für die B-Blöcke. Die Eigenschaften der Blockcopolymere in verdünnten, konzentrierten und hochkonzentrierten wässrigen Lösungen wurden mittels DLS, Trübungsphotometrie, 1H- und 19F-NMR, Rheologie, CMC- sowie Schaumhöhen- und Oberflächenspannungsmessungen und Lichtmikroskopie untersucht. Weiterhin wurden ihre Eigenschaften als Emulgatoren und in Mikroemulsion untersucht. Das Micellbildungsverhalten der hydrophob endfunktionalisierten Polymere wurde mittels DLS Messungen in verdünnter organischer Lösung untersucht. Alle untersuchten BAB-Triblöcke bildeten Micellen und zeigten Oberflächenaktivität bei Raumtemperatur in verdünnter, wässriger Lösung. Weiterhin zeigen die wässrigen Lösungen der Polymere mäßige Schaumbildung. Mit verschiedenen Öltypen und Ölkonzentrationen wurden Emulsionen bzw. Mikroemulsionen gebildet. In Mikroemulsion wurde durch Zugabe von BAB-Triblockopolymeren kein Boosting-Effekt erzielt werden. Bei Untersuchung höherer Polymerkonzentrationen wurde die Bildung von Hydrogelen mittels rheologischer Messungen nachgewiesen. Verschiedene Substrate konnten benetzt werden. Die hydrophob endgecappten Polymere bilden in verdünnter organischer Lösung Micellen, die mittels DLS untersucht wurden, und zeigen somit Tensidverhalten in nichtwässriger Lösung.

Hydrophobic drugs that are P-gp substrates (BCS Class IV) such as paclitaxel, CUDC-101 etc. pose a serious challenge for oral drug delivery. Polymeric amphiphiles such as N-palmitoyl-N-monomethyl-N,N-dimethyl-N,N,N-trimethyl-6-O-glycolchitosan (GCPQ) are capable of enhancing the bioavailability of hydrophobic drugs by forming nanoparticles. The general hypothesis is that the physicochemical properties of the polymer will affect the colloidal stability, encapsulation efficiency and absorption of hydrophobic drugs. The main aims of the project are as follows: a) to examine the feasibility of using GCPQ with different characteristics, for the oral and subcutaneous delivery of CUDC-101 and b) to examine the effect of N-(2-phenoxyacetamide)-6-O-glycolchitosan (GCPh) on the P-gp efflux of paclitaxel. GCPh, a new polymeric amphiphile was synthesized by conjugating glycol chitosan to phenoxy acetic acid. Paclitaxel and CUDC-101 were encapsulated with GCPh and GCPQ of different molecular weights and hydrophobicity. The in vivo oral drug absorption profile for paclitaxel-GCPh nanoparticles and paclitaxel-Taxol® nanoparticles were determined in mice with and without verapamil, a P-gp inhibitor. In another study, the oral and subcutaneous drug absorption profile for CUDC-101 – GCPQ nanoparticles were conducted in mice and rat models respectively. Results indicated that GCPh improved the oral absorption of paclitaxel by improving the dissolution and promoting particle uptake through enterocytes. Experiments with Taxol® suggested that it is possible to saturate the P-gp pumps by improving the drug’s dissolution. Oral absorption of CUDC-101 was poor due to the drug’s extremely poor water solubility. The subcutaneous absorption of CUDC-101 – GCPQ nanoparticles were excellent. The colloidal stability and absorption of these nanoparticles can be improved by increasing polymer concentration and its hydrophobicity. These nanoparticles also prolonged the life span of human A431 tumour bearing mice by 28 days (p < 0.001). To conclude, the new polymeric amphiphile (GCPh), capable of improving the oral absorption of BCS Class IV P-gp substrates was developed. A new strategy to nullify the P-gp efflux was developed. A clinically relevant subcutaneous dosage form for CUDC-101 was also successfully developed.

Raman spectroscopy has been used to monitor the deformation of natural cellulose whisker polymer nanocomposites. Cotton and tunicate whiskers were used as reinforcements in polymer matrices. Raman spectra from the nanocomposites highlight an intense band located at the 1095 cm-1 position. This band is reported to shift towards a lower wavenumber under the application of tensile deformation. On the other hand, the compressive deformation of the composite gives rise to an increase in the position of this Raman band. The shifts correspond to the direct deformation of the molecular backbone of cellulose, which is dominated by a C-O stretching mode. The Raman band located at 1095 cm-1 is shown to shift non-linearly before it reaches a plateau due to the breakdown of the whisker-matrix interface. The initial shift rate is associated with the stiffness of the cellulose whiskers. The stiffnesses of single whiskers of cotton and tunicate are found to be 58 and 155 GPa respectively, assuming two dimensional (2D) in-plane distribution of whiskers. Cyclic deformation tests of the composites provide an insight into understanding the behaviour of the whisker-polymer matrix interface under tension and compression. It is found that residual compressive stress occurs during each cycle of the deformation. The level of disruption at the whisker-matrix interface is determined by estimating the energy dissipation, which is proportional to the hysteresis area. Local orientation is also observed in the nanocomposites produced by solution casting and subsequent melt pressing. Dark regions of the composites viewed under a polarised optical microscopy are found to represent areas in which the cellulose whiskers form a randomly oriented whisker network. A shift rate for the Raman band initially located at 1095 cm-1 obtained in the dark regions of 12.2 vol% tunicate whisker poly(vinyl acetate) nanocomposites is found to be -0.5±0.07 cm-1%-1, which is lower than -1.2±0.04 cm-1%-1 from the bright regions. Exposure to water and temperature during the deformation of the nanocomposites results in significant changes in stress transfer between the whiskers and the matrix. It is shown that the interface can be 'switched-off' for the poly(vinyl acetate)/whisker system in the presence of water and also at temperature above the glass transition.

Carbon fibre reinforced polymer, or CFRP composite materials, play an increasingly important role in modern manufacturing. They are widely used in aerospace, and their use is currently spreading to other industries where high strength-to-weight ratios are required. However, machining of composites is still a challenging task and often hampered by poor quality. Despite the extensive research that was conducted on the machining of composite materials over the last few years, mechanical drilling still suffers from delamination, fibre pull-out and poor surface finish, whereas laser cutting produces microstructured defects and a taper problem. This thesis reports on the drilling of CFRP composites by demonstrating the possibility of drilling small diameter holes (i.e. 8mm) into 25.4mm thick carbon fibre reinforced polymer composites (CFRPs) using mechanical drilling and laser drilling as stand-alone processes and as a sequential combination. The research involved four main phases of experimental testing. The first part of Phase 1 involved!preliminary experiments of drilling thick CFRP to identify the most suitable drilling strategy. Three mechanical drilling strategies conducted in the same parameter by using a 2-flute uncoated WC twist drill that was assessed with respect to feasibility of drilling thick CFRP. The results showed that the single-step strategy was the most feasible strategy to drill thick CFRP compared to 2- and 4-peck drilling strategies. The second part of Phase 1 concerned the influence of speed-feed combinations on hole quality by utilising three twist drills with different materials and geometries in both an uncoated and coated condition. The results indicated that a significant increase in peel-up delamination was found with increasing feed rate. In contrast, using a constant feed rate but increasing the spindle speed seemed to reduce peel-up delamination. Furthermore, the hole entry for 2-flute uncoated WC drill bits was an uncommon study finding because most of the previous researchers experienced more damages at the hole exit and their investigation focused on the hole exit only. Currently, implementation of laser technology in cutting and drilling composites is becoming popular as an alternative solution. Various experiments were conducted with the goal of identifying the effects of machining parameters on key output measures (i.e. heat affected zone (HAZ), hole depth and other damages) in drilling of 25.4 mm thick CFRP by using a fibre laser. Phase 2 involved a number of machining parameters selected to identify the potential of a fibre laser in drilling thick CFRP composites (i.e. laser power, scanning speed, focal point plane position (FPP), assisted-gas type and gas pressure). The results proved that a fibre laser could penetrate thick CFRP to a 22mm depth only. Moreover, the spiral trepanning strategy was able to penetrate 80% out of the total thickness of the CFRP in continuous wave (CW) mode, whereas the modulated laser beam (i.e. laser pulse mode) can penetrate 67% only. This result was a major recorded breakthrough because previous research attempts cut up to 5mm only. Laser power proved to be the most influential factor for hole depth in laser drilling of thick CFRP when the spiral trepanning strategy was applied. Machining trials were conducted in Phase 3 by using a 16kW fibre laser in modulated pulsed laser mode. In this phase, laser power of more than 1kW was attempted to cut the whole thickness of CFRP composites in CW mode, but it was unsuccessful. However, a new parameter was discovered (i.e. the cooling time between passes in modulated pulsed mode), which proved a considerable reduction of HAZ when the higher cooling time was imposed. Finally, phase 4 involved the experiments of sequential laser-mechanical drilling. A 1kW fibre laser was selected as a pre-drilling or initial step and followed by mechanical drilling as the final step. The sequential drilling method successfully reduced thrust force and torque for mechanical drilling by an overall average of 61%, resulting in high productivity and decreasing the thermal and mechanical stresses in the cutting tool and, in turn, promoting higher tool life. The highest delamination factor (Fda) ratio was experienced by the sequential laser 8mm – mechanical 8mm for both tools (i.e. 2- and 3-flute uncoated tungsten carbide) and laser pre-drilling strategies (i.e. single- and double-side). Thus, a novel laser-mechanical sequential drilling technique was developed, evaluated and tested in the drilling of thick CFRP composites; this is the first time ever in drilling thick CFRP (i.e. 25.4mm).

This thesis is part of the wearable electronic field, and in particular of the Organic BioElecteonic Sensors that have the in-situ real-time monitoring of the health and performance status of the subject as the main goals. With this purpose, textile-based wearable sensors for continuous and simultaneous detection of [Cl–] and pH level have been developed. PEDOT:PSS is the intrinsic conductive polymer used to make the commercial yarns conductive. The coated threads have been functionalized with Ag/AgCl NPs and BTB to make them able to detect [Cl–] and pH level, respectively. The developed sensors end up to be easy-to-make, reproducible with excellent sensitivity and stability both in single and multiple configurations without any interference. The results achieved in this work allow future improvements to develop a new textile-based device that can be easily integrated into clothing, allowing worn it in dealy life.

La découverte des nanotubes de carbone (NTCs) par S. Iijima en 1990 a permis d'explorer un nouveau monde à l'échelle nanométrique. Les études sur la synthèse des NTCs durant le début de cette décennie ont apporté une reproductibilité des formes allotropiques de carbone. Les propriétés mécaniques et électriques exceptionnelles des NTCs ont éveillé l'esprit des scientifiques afin de concevoir des systèmes touchant le domaine de la nanotechnologie. Dans ce contexte, mes travaux de recherches ont visé à étudier les potentialités des nanotubes de carbone dans le domaine des hyperfréquences. Deux types d'applications peuvent être distinguées : l'élaboration de matériau nano-composite mais aussi la miniaturisation des composants électromécaniques (NEMS). L'application la plus immédiate des NTCs consiste à les utiliser comme additif dans des polymères, thermoplastiques, thermodurcissables ou élastomères, afin d'en modifier les propriétés. L'utilisation des matériaux composites à base de nanotubes de carbone apparaît comme une voie prometteuse dans le domaine des nanotechnologies grâce à leurs propriétés structurales et électroniques très particulières. Pour élargir le domaine d'application des NTCs, nous avons étudié un nouveau matériau composite à base d'un polymère (BenzoCycloButène ''BCB'') et de nanotubes de carbone double parois (DNTCs) pour une utilisation aux fréquences micro-ondes. Nous rapportons ici une étude des propriétés micro-ondes de composites BCB/DNTCs en fonction de la concentration massique de nanotubes. Nous présentons, dans un premier temps, les méthodes d'homogénéisation et de fabrication du composite, puis nous traitons l'élaboration de structures de test adaptées à des mesures µondes et millimétriques. Après caractérisation, nous donnons le comportement spectral et la modélisation pour les pertes linéiques ainsi que e* (permittivité effective complexe). Cette étude a permis de montrer qu'il est possible de configurer les performances électriques d'un matériau composite en fonction du % de NTCs incorporés. .
The discovery of carbon nanotubes (NTCs) by S. Iijima in 1990 allowed to explore a new world at the nanoscale. At the beginning of this decade, studies have provided a reproducibility of carbon nanotubes. Carbon nanotubes have shown exceptional stiffness, strength and remarkable thermal and electrical properties, which make them ideal candidates for the development of multifunctional materials systems. My research presents two possible uses of carbon nanotubes (CNTs) for microwave applications, exploiting their exceptional electrical and mechanical properties. The first one consist in utilizing their metallic or semiconducting properties to modify the electrical behavior of polymer (BCB) doped with carbon nanotubes. The second one aims to extend the concept of passive and reconfigurable micrometer components (MEMS)at the nanoscale to develop Nano-Electro-Mechanics Systems (NEMS). The first study consisted of an electromagnetic characterisation of polymer BenzoCycloButen (BCB) composites containing dispersed CNTs at microwave frequencies (40MHz - 40GHz) using coplanar waveguides (CPW). A new nano-composite material based on carbon nanotubes and BCB polymer is studied for shielding and electromagnetic wave absorption. For the first time to our knowledge, methods of homogenization and composite fabrication are presented, next test structures to measure microwave parameters are developed. After characterization, linear attenuation "a", complex permittivity "e*", conductivity "s" and power absorption "PA" are extracted and compared to simulation results obtained using the electromagnetic field simulator "HFSS". The electrical parameters of nano-composites are modified by DWCNTs concentration. The percolation threshold is obtained with only 0. 075wt. % of DWCNTs in BCB and the nano-composites showed 5dB of PA at 30GHz. The resulting engineerable composite gives RF-designer one more degree of freedom to to develop and optimize microwave components. .

Dans l’optique d’améliorer le traitement des cancer du sein triple négatif (CSTN), les objectifs de ces travaux de thèse sont : 1) d’optimiser la formulation d’un nanovecteur de siRNA fonctionnalisé par un peptide membranotrope (CS-MSN) pour augmenter son efficacité de transfection et pour avoir des caractéristiques compatibles avec une administration par voie systémique, ii) étudier ses voies d’internalisation et son trafic et devenir intracellulaire et iii) valider son efficacité sur un modèle cellulaire de CSTN. L’optimisation de la formulation des CS-MSN a abouti à un nanovecteur d’une taille d’environ 170 nm avec une charge de surface légèrement positive. Les CS-MSN ont montré une capacité à protéger les siRNA contre la dégradation en présence du sérum sans toxicité remarquable sur les cellules. L’entrée des CS-MSN dans les cellules est augmentée par la présence du peptide membranotrope gH625 à leur surface et elle implique une voie d’endocytose médiée par les clathrines et par les cavéoles. Les CS-MSN ont montré une capacité à échapper à la dégradation par les vésicules endo-lysosomales, cet échappement étant facilité par la présence du peptide gH625. Cet échappement endosomal résulte en une inhibition de 73 % de l’expression de la protéine GFP et une réduction significative de l’ARNm et de la protéine Bcl-xL
In order to improve the treatment of triple negative breast cancer (TNBC), the objectives of this work are: 1) to optimize the formulation of a siRNA nanovector (CS-MSN) functionalized by a cell penetrating peptide to increase its transfection efficiency and to obtain features compatible with a systemic administration, ii) to investigate its internalization mechanisms and pathways and its intracellular trafficking and iii) to validate its efficiency on a TNBC cell model. The optimization of CS-MSN formulation resulted in a nanovector with a size of about 170 nm with a slightly positive surface charge. CS-MSN showed an ability to protect siRNA against degradation in the presence of serum without remarkable cell toxicity. The entry of CS-MSN in cells is enhanced by the presence of the membranotropic peptide gH625 on their surface and involves a clathrin- and caveolae-mediated endocytosis pathway. CS-MSN showed an ability to escape degradation in endo-lysosomal vesicles, facilitated by the gH625 peptide. This endosomal escape results in 73% of inhibition of the GFP protein expression and a significant reduction of Bcl-xL mRNA and protein

Dissertação de mestrado em Construção e Reabilitação Sustentáveis
As crescentes necessidades de otimização na área da engenharia civil, tanto no que se refere à velocidade e logística das construções quanto nos aspectos da qualidade e durabilidade dos edifícios, combinadas ao elevado impacto dos materiais estruturais tradicionais nas dimensões econômica, social e ambiental da sustentabilidade, tornam necessário o estudo de elementos construtivos alternativos. Entre as soluções, estão os polímeros reforçados com fibras (FRP), materiais que, devido às suas características superiores em relação aos convencionais, apresentam várias aplicações potenciais, especificamente os varões compósitos entrançados (BCR) reforçadas com fibras de vidro e/ou carbono que possuem, quando comparadas ao aço, elevado desempenho mecânico, leveza e reduzidos consumos energéticos de produção. Apesar dos avanços, ainda há insuficiente conhecimento a respeito da longevidade destes varões no interior do concreto empregado em elementos estruturais. Deste modo, este trabalho objetiva a avaliação da influência da camada externa na durabilidade de varões compósitos entrançados para tal fim. Para tanto, foram produzidas quatro amostras com reforço constante de fibras de vidro e carbono, com diferentes matrizes epoxídicas termoendurecíveis (tipo 1 e tipo 2) e dois tipos de fibras (poliéster e acrílico), as quais foram submetidas a condições e ambientes agressivos, designadamente, soluções alcalina em temperatura elevada e de cloretos e exposição a raios UV e humidade. Foram ainda desenvolvidas verificações acerca das propriedades físicas, químicas e mecânicas dos provetes, através de análise microscópica, verificação da variação de massa e de diferença de cor, da realização de espectroscopia infravermelho e ensaio de tração. Ao fim dos ensaios, constatou-se que a configuração de matriz formada por fibra acrílica impregnada com resina tipo 2 é a que apresenta melhores resultados e que os BCR mostraram, de modo geral, bom comportamento ao fim dos 80 dias de ciclo, apresentando adequadas propriedades após a exposição aos ambientes deletérios.
Increasing optimization needs in the civil engineering area, both in terms of speed and logistics buildings as in aspects of quality and durability of buildings, combined with the high impact of traditional structural materials in the economic, social and environmental dimensions of sustainability, the study of alternative construction elements become necessary. Among the solutions are polymers reinforced with fibers (FRP) materials which, due to their superior characteristics compared to conventional, present a em umber of potential applications, specifically braided composite rods (BCR) reinforced with glass fibers and / or carbon have compared to steel, high mechanical performance, light weight and reduced energy production consumption. Despite advances, there is still insufficient knowledge about the longevity of these men inside the concrete used in structural elements. Thus, this study aims the evaluation of the influence of the outer layer in the durability of the FRP composites for this purpose. To this end, four samples were produced using continuous reinforcement glass fibers and carbon and matrices composed of two types of fibers (polyester and acrylic) and two types of epoxy thermosetting resins (type 1 and type 2), which were subject to conditions and harsh environments, in particular, alkaline solutions at elevated temperature and chlorides and exposure to UV rays and humidity. They were also carried out checks on the physical, chemical and mechanical properties of samples by means of microscopic analysis, scanning mass variation and color difference, performing infrared spectroscopy and tensile test. At the end of the tests, it was observed that the matrix configuration formed by acrylic fiber impregnated with type 2 resin is that best results and that BCR showed generally good performance at the end of the 80 day cycle, with appropriate properties after exposure to deleterious environments.

博士
臺北醫學大學
藥學系(博士班)
98
Corneal epithelial damages cause stromal keratocyte apoptosis and excessive keratocyte apoptosis is associated with the pathologic mechanisms of corneal changes seen in corneal disorders. Scraping of corneal epithelium (debridement), an epithelial damage, yields keratocyte apoptosis including DNA fragmentation and cellular morphological changes in the anterior stroma underlying the injured epithelium. In the study, activation of caspase-3 and reduction of bcl-xL were detected in cornea after corneal epithelial debridement except for DNA fragmentation and cellular morphological changes. We delivered the plasmid encoding an anti-apoptotic gene, Bcl-xL (pCMV-bcl-xL-eGFP) with polymeric micelle (PM) via eye drop to epithelial debridement cornea. After six doses of eye drop within 48 hr, mRNA of bcl-xL was significantly increased at 48 hr (2.2-fold, P&lt; 0.05) and mRNA of eGFP was detected at 48 hr (4571.7 ± 1194.5 copies/ug total RNA). The bcl-xL-eGFP fusion protein was detected in wounded cornea. Furthermore, both DNA fragmentation and caspase-3 activity were significantly decreased (61% at 48 hr, P&lt; 0.05) in epithelial debridement cornea with eye drop of pCMV-bcl-xL-eGFP/PM. Thus, eye drop of pCMV-bcl-xL-eGFP/PM reduced apoptosis for corneal epithelial damage.

Dissertação de mestrado integrado em Engenharia Civil
Os varões compósitos entrançados (Braided Composite Rods) – BCR – são compostos por materiais compósitos de matriz polimérica reforçados com fibras em que o núcleo de reforço é revestido por uma camada externa entrançada e integram-se no grupo dos materiais compósitos poliméricos reforçados com fibras, ou materiais FRP (Fiber Reinforced Polymer). Na presente dissertação, pretendeu-se estudar a durabilidade de varões em material compósito (BCR) para perceber se são adequados para aplicação na construção civil. O estudo da durabilidade elaborado nesta dissertação consistiu, mais específicamente, em quantificar a degradação das propriedades químicas, físicas e mecânicas através da análise de provetes submetidos a vários agentes agressivos. Consideraram-se alguns agentes agressivos mais comuns em aplicações na Engenharia Civil, meio alcalino, cloretos, radiação UV e humidade. A análise da degradação das propriedades químicas, físicas e mecânicas foi realizada através de ensaios de tração, FTIR, microscópio digital e variação de massa. A amostras estudadas variavam na sua constítuição as fibras do núcleo e a matriz, sendo esta sempre uma resina epóxida, no entanto, a camada externa entrançada manteve-se sempre a mesma, poliéster. Os resultados obtidos indicaram que, em geral, a amostra que apresenta melhores resultados, é a constituída por um núcleo de fibras de vidro com fibras de basalto e matriz resina epóxida CR144.
Braided Composite Rods – BCR – are made of composite materials with a polymeric matrix reinforced with fibers, where the reinforcement core is coated with an external braided layer and are included in the group of fibre reinforced polymer materials, also known as FRP materials. The main goal of the present dissertation was to study the durability of composite rods (BCR) in order to understand if it is suitable for civil construction. More specifically, this study aims to quantify the chemical, physical and also mechanical degradation, through the analysis of samples which were exposed to several aggressive environments. Some of the most frequent aggressive environments , for civil engineering applications, were chosen, such as alkali, chlorides, UV radiation and moisture. The analysiys of the chemical, physical and mechanical degradation was carried out trough tensile tests, FTIR, digital microscope and weight variation. The core fibers and matrix of the studied samples were variable, however the matrix was always an epoxide resin and the external braided layer was constant, was always polyester. The results of this study have shown that, in general, the sample with better results, is the one with glass and basalt combined fiber core and epoxide resin CR144 as a matrix.