Submitted by MARCIA ROVADOSCHI (marciar@unifra.br) on 2018-08-16T13:45:47Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_NaraMariaBeckMartins.pdf: 7512915 bytes, checksum: 196398dd32ccc4f1db2d9fd1d3a831d4 (MD5) / Made available in DSpace on 2018-08-16T13:45:47Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_NaraMariaBeckMartins.pdf: 7512915 bytes, checksum: 196398dd32ccc4f1db2d9fd1d3a831d4 (MD5) Previous issue date: 2011-03-31 / Carbon nanotubes (CNT) belong to a new group of materials which have special properties and have been the focus of many studies in the biomedical area. Researches on toxicity are important to evaluate the possibility of using them in organic beings. In that context, we analyzed the histological changes of multi-walled carbon nanotubes (MWCNT) in mice, after oral exposure. To this end, female mice were orally exposed to 100 μL of MWCNT/day, suspended in a PBS/Tween 80® solution, at a concentration of 5 mg/mL, for 7 days. A group of mice was sacrificed on the 7th day and another on the 30th day. Liver, spleen, heart, lungs, kidneys and brain were collected and fixed in formaldehyde 10% for histological analysis (v/v). MWCNT accumulation in the organs was detected, deeper in mice from the second group. Inflammation in the liver was also observed in mice that were sacrificed on the 30th day. These inflammatory disturbances can be related to the direct action of MWCNT in organism. The data analysis suggests that oral exposure to a 0,5 mg/day dose of MWCNT causes accumulation of the material in organs and time-dependent hepatic inflammatory signals. / Nanotubos de carbono (NC) pertencem a uma nova classe de materiais que apresentam características especiais e estão sendo foco de muitas pesquisas para uso na área biomédica. Estudos de toxicidade são importantes para avaliar a possibilidade do uso em organismos vivos. Neste contexto, foram analisadas as alterações histológicas provocadas pela administração oral de nanotubos de carbono de paredes múltiplas (NCPM) em camundongos. Para tanto, camundongos fêmeas foram expostos oralmente a 100μL NCPM/dia suspensos em solução de PBS/Tween 80® na concentração de 5 mg/mL, durante 7 dias. Um grupo foi sacrificado no 7º dia e outro grupo no 30º dia. Fígado, baço, coração, pulmões, rins e cérebro foram coletados e fixados em formol 10% (v/v) para análise histológica. Observou-se deposição de NCPM nos órgãos, mais acentuadas no grupo sacrificado no 30º dia e sinais de inflamação no fígado neste grupo. Estas alterações inflamatórias podem estar relacionadas com a ação direta dos NCPM no organismo. Estes dados permitem concluir que a exposição por via oral a NCPM na dose de 0,5mg/dia causam deposição do material nos órgãos e sinais inflamatórios hepáticos dependentes do tempo.

Orientador: Vitor Baranauskas, Walkyria Mara Gonçalves Volpini / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-23T06:56:53Z (GMT). No. of bitstreams: 1 Camilo_DanielaFranchiPereiradaSilva_M.pdf: 7402339 bytes, checksum: 4a71443f20b4e716e5328394cdea307b (MD5) Previous issue date: 2013 / Resumo: Os nanotubos de carbono (NTC) têm sido utilizados em larga escala com finalidades industriais e avaliados, por sua estrutura e propriedades, como ferramenta para aplicação biomédica. Tanto a manipulação humana direta na produção industrial como a perspectiva do uso em medicina suscitaram amplas pesquisas para avaliar seu risco na saúde humana e o impacto ambiental. O presente trabalho teve como objetivo determinar os efeitos em longo prazo da administração sistêmica de nanotubos de parede múltipla (MWNTC) não funcionalizados na evolução do diabetes autoimune espontâneo do camundongo "Non Obese Diabetic" (NOD). O protocolo consistiu do tratamento de fêmeas NOD/Uni, de 6 semanas de vida, com uma única injeção intraperitoneal de MWNTC (100 ?g/animal) ou do veículo Pluronic (grupo controle) e do estudo longitudinal de parâmetros clínicos, histológicos e de resposta imunológica, até 24 semanas após administração. Os dados histológicos demonstraram que o MWNTC não funcionalizado foi absorvido da cavidade peritoneal e permaneceu retido em células fagocitárias de linfonodos peri-pancreáticos, baço e fígado, onde causou uma resposta inflamatória granulomatosa, e também em parede de ductos pancreáticos, tendo confirmada sua identificação estrutural in situ, dentro de fagolisossomos de macrófago e no epitélio ductal, por microscopia eletrônica de transmissão (HRTEM). Apesar de não ter havido diferenças na frequência de desenvolvimento do diabetes clínico ou das características morfológicas da insulite pancreática, as fêmeas NOD tratadas com MWNTC apresentaram flutuação média de glicemias significativamente maior em relação ao grupo controle, até o final do estudo (p<0,0001; Wilcoxon), com tendência a antecipação do aparecimento do diabetes clínico. Neste estudo, foi analisado um perfil de citocinas pró e anti-inflamatórias previamente avaliadas no laboratório, em fase aguda após a exposição à MWNTC. Foi focada a expressão evolutiva destas citocinas em linfonodos peri-pancreáticos, sítio de ativação de células T auto-reativas contra antígenos da célula ? pancreática. O MWNTC induziu uma resposta Th1 mais acentuada nos animais tratados, entre a 14ª e a 20ª semana de vida (momento de insulite extensa), com aumento da expressão de INF? e aumento da relação INF?/TGF? e INF?/IL10. Esta relação permanece elevada na 30ª semana de vida das fêmeas NOD tratadas, com reduzida expressão de TGF?. Nossos dados compreendem um dos mais longos seguimentos in vivo após administração sistêmica de MWNTC, demonstrando que o MWNTC não funcionalizado pode ser transportado e retido no sistema reticulo-endotelial e persistir no corpo por longo tempo, como detectado, neste estudo, em células fagocitárias de linfonodos regionais peri-pancreáticos de animais tratados, mesmo 6 meses após sua administração. Os nanotubos comerciais utilizados em diversos campos da tecnologia moderna são partículas não modificadas. Mesmo compreendendo a necessidade de se modificar a nanoestrutura para vislumbrar sua aplicação em medicina, relevância deve ser dada para o risco da exposição humana e ambiental ocorrendo neste momento. Uma resposta inflamatória crônica, com aumento da relação entre citocinas pró/antiinflamatórias, pode ser associada à maior gravidade de doenças autoimunes em organismos suscetíveis / Abstract: Carbon nanotubes (CNT) have been used in large scale for industrial purposes and evaluated for its structure and properties as a tool for biomedical application. Both the direct human manipulation in industrial production as the prospect of use in medicine attracted extensive research to assess their risk to human health and environmental impact. This study aims to determine the long-term effects of systemic administration of multi-wall carbon nanotubes (MWCNT) not functionalized in the evolution of spontaneous autoimmune diabetes in "Non Obese Diabetic" mice (NOD). The protocol consisted of the treatment of 6 weeks female NOD/Uni, with a single intraperitoneal injection of MWCNT (100 ?g/animal) or vehicle Pluronic (control group) with longitudinal study of clinical and histological parameters and immunological response until 24 weeks after administration. The histologic data demonstrated that non-functionalized MWCNT was absorbed from the peritoneal cavity and was retained on phagocytic cells of peripancreatic lymph nodes, spleen and liver, where it caused a granulomatous inflammatory response, and also in the wall of the pancreatic ducts, and their structural identification in situ was confirmed within macrophage phagolysosomes and ductal epithelium by transmission electron microscopy (HRTEM). Although there were no differences in the frequency of development of overt diabetes or morphological characteristics of pancreatic insulitis, MWCNT treated NOD females had average blood glucose fluctuation significantly higher than control group until the end of the study (p<0,0001; Wilcoxon), with a tendency to anticipate the onset of clinical diabetes. In this study we analyzed a profile of previously evaluated pro-inflammatory and antiinflammatory in the acute phase after exposure to MWCNT. We focused on the evolutive expression of these cytokines in peri-pancreatic lymph nodes, site of activation of T cells reactive against pancreatic ? cell antigens. MWCNT induced a stronger Th1 response in treated animals, between the 14th and 20th weeks of life (time of extensive insulitis), with increased expression of IFN? and increased ratio of INF?/TGF? and INF?/IL10. This ratio remains high at treated NOD females aged 30 weeks, with reduced expression of TGF?. Our data comprise one of the longest in vivo follow-up after systemic administration of MWCNT, demonstrating that nonfunctionalized MWCNT can be transported and retained in the reticulo-endothelial system and persist in the body for long time, as detected in this study, in phagocytic cells of peri-pancreatic regional lymph nodes, even six months after its administration. The nanotubes used in various commercial fields of modern technology are unmodified. Even comprising the need to modify the nanostructure to effective its application in medicine, importance should be given to the risk of human and environmental exposure occurring at this time. A chronic inflammatory response, with an increased ratio of pro/anti-inflammatory cytokines may be associated with greater severity of autoimmune diseases in susceptible organisms / Mestrado / Eletrônica, Microeletrônica e Optoeletrônica / Mestra em Engenharia Elétrica

Three systems of electrospun composite membranes with piezoelectric polymer polyvinylidene fluoride (PVDF) as matrix incorporating: 1) Carbon based fillers: carbon nanotube (CNT) and graphene oxide (GO); 2) Ceramic based fillers-barium titanate (BT), zinc oxide (ZnO) and nanoclays (halloysite and bentonite); 3) Cellulosic fillers: microcrystalline cellulose (MCC) and nanocrystalline cellulose (NCC) at different loadings were prepared by electrospinning process. Influence of filler type and loading on total PVDF crystallinity (Xc), relative fraction of β phase (piezoelectric phase) in total crystalline PVDF (Fβ), volume fraction of β phase in the samples (vβ) and piezoelectric coefficient d33 were characterised and analysed. Correlation between vβ and piezoelectric performance (d33) will be focused by this work. A common situation was observed for the composites-d33 increased while vβ is reduced by the fillers, so it can be concluded that d33 of the composites is not totally up to their vβ, there are other factors that need to be taken into account. For example, for carbon based filler like CNT, it increased electric conductivity of sample during and after electrospinning process, making it easier for charges produced by β crystals from inside of sample to be transferred to surfaces of the sample, and possibly promoting orientation of β crystals in d33 direction, therefore enhanced d33 of the composites though β phase formation was significantly hindered by inclusion of CNT; For piezoelectric ceramic fillers like BT and ZnO, a possible combined piezoelectricity from filler and β phase PVDF might enhanced d33 though less β phase was formed; And for non-piezoelectric and non-conductive fillers, enhancement in orientation of β crystals might play a major role in promotion of d33. Keywords: electrospinning; polyvinylidene fluoride (PVDF); nanocomposites; piezoelectric coefficient d33; energy harvesting.

La photonique silicium est reconnue comme la technologie à même de répondre aux nouveaux défis des interconnexions optiques. Néanmoins, la photonique silicium doit faire face à d'importants défis. En effet, le Si ne peux pas émettre ou détecter de la lumière dans la plage de longueurs d'onde des télécom (1,3 µm à 1,5 µm). Par conséquent, les sources et les détecteurs sont mis en œuvre avec du Ge et des matériaux III-V. Cette approche multi-matériaux complique la fabrication des dispositifs et augmente le coût final du circuit. Cependant, les nanomatériaux ont été identifiés comme alternative pour la mise en œuvre d’émetteurs-récepteurs moins chers et plus petits.Cette thèse est dédiée à l'étude et au développement de dispositifs optiques et optoélectroniques sur la plateforme photonique silicium basés sur l’utilisation de nanotubes de carbone mono paroi (SWCNT). L’objectif principal est de démontrer les blocs fonctionnels de base qui ouvriront la voie à une nouvelle technologie photonique dans laquelle les propietés actives proviennent des nanotubes de carbone.Les nanotubes de carbone ont été étudiés comme matériaux pour la nanoélectronique avec la démonstration de transistors ultra-compacts à hautes performances. De plus, les SWCNTs semi-conducteurs (s-SWCNTs) sont également des matériaux très intéressants pour la photonique. Les s-SWCNTs présentent une bande interdite directe qui peut être ajustée dans la gamme de longueurs d'onde du proche infrarouge en choisissant le bon diamètre. Les s-SWCNT présentent une photoluminescence et une électroluminescence, pouvant être exploitées pour la mise en œuvre de sources de lumière. Ils présentent également diverses bandes d’absorption pour la réalisation de photodétecteurs. Ces propriétés font que les nanotubes de carbone sont des candidats très prometteurs pour le développement de dispositifs optoélectroniques pour la photonique.Le premier objectif de la thèse était l'optimisation des solutions de nanotubes de carbone. Une technique de tri par ultra-centrifugation assistée par polymère a été optimisée, donnant des solutions de haute pureté en s-SWCNT. Sur cette base, plusieurs solutions de s-SWCNTs ont été élaborées pour obtenir des SWCNTs émettant dans les longueurs d'onde comprise entre 1µm et 1,6µm.Le deuxième objectif était d’étudier l'interaction des s-SWCNT avec des guides d'onde silicium et des résonateurs optiques. Plusieurs géométries ont été étudiées dans le but de maximiser l'interaction des s-SWCNT avec le mode optique en exploitant la composante transverse du champ électrique. D'autre part, une approche alternative a été proposée et démontrée en utilisant la composante longitudinale du champ électrique. En utilisant la composante longitudinale, une amélioration de la photoluminescence, un seuil d’émission avec la puissance de pompe ainsi qu’un rétrécissement de la largeur spectrale des résonances dans les microdisques ont été observés. Ces résultats sont un premier pas très prometteur vers la démonstration d’un laser intégré à base de SWNTs.Le troisième objectif était d'étudier les dispositifs optoélectroniques à base de s-SWCNTs. Plus spécifiquement, une diode électroluminescente (DEL) et un photodétecteur ont été développés, permettant la démonstration du premier lien optoélectronique sur puce basé sur les s-SWCNT.Le dernier objectif de la thèse était d'explorer le potentiel de s-SWCNT pour l’optique non linéaire. Il a été démontré expérimentalement, qu’en choisissant la chiralité des s-SWCNTs, le signe du coefficient Kerr pouvait être soit positif ou négatif. Cette capacité unique ouvre un nouveau degré de liberté pour contrôler les effets non linéaires sur puce, permettant de compenser ou d'améliorer les effets non linéaires pour des applications variées. / Silicon photonics is widely recognized as an enabling technology for next generation optical interconnects. Nevertheless, silicon photonics has to address some important challenges. Si cannot provide efficient light emission or detection in telecommunication wavelength range (1.3μm-1.5μm). Thus sources and detectors are implemented with Ge and III-V compounds. This multi-material approach complicates device fabrication, offsetting the low-cost of Si photonics. Nanomaterials are a promising alternative route for the implementation of faster, cheaper, and smaller transceivers for datacom applications.This thesis is dedicated to the development of active silicon photonics devices based on single wall carbon nanotubes (SWCNTs). The main goal is to implement the basic building blocks that will pave the route towards a new Si photonics technology where all active devices are implemented with the same technological process based on a low-cost carbon-based material, i.e. SWCNT.Indeed, carbon nanotubes are an interesting solution for nanoelectronics, where they provide high-performance transistors. Semiconducting SWCNT exhibit a direct bandgap that can be tuned all along the near infrared wavelength range just by choosing the right tube diameter. s-SWCNTs provide room-temperature photo- and electro- luminescence and have been demonstrated to yield intrinsic gain, making them an appealing material for the implementation of sources. SWCNTs also present various absorption bands, allowing the realization of photodetectors.The first objective of this thesis was the optimization of the purity of s-SWCNT solutions. A polymer-sorting technique has been developed and optimized, yielding high-purity s-SWCNT solutions. Based on this technique, several solutions have been obtained yielding emission between 1µm and 1.6µm wavelengths.The second objective was the demonstration of efficient interaction of s-SWCNT with silicon photonics structures. Different geometries have been theoretically and experimentally studied, aiming at maximizing the interaction of s-SWCNT with optical modes, exploiting the electric field component transversal to light propagation. An alternative approach to maximize the interaction of s-SWCNT and the longitudinal electric field component of waveguide modes was proposed. Both, a power emission threshold and a linewidth narrowing were observed in several micro disk resonators. These results are a very promising first step to go towards the demonstration of an integrated laser based on CNTs.The third objective was to study optoelectronic SWCNT devices. More specifically, on-chip light emitting diode (LED) and photodetector have been developed, allowing the demonstration of the first optoelectronic link based on s-SWCNT. s-SWCNT-based LED and photodetector were integrated onto a silicon nitride waveguide connecting them and forming an optical link. First photodetectors exhibited a responsivity of 0.1 mA/W, while the complete link yielded photocurrents of 1 nA/V.The last objective of the thesis was to explore the nonlinear properties of s-SWCNT integrated on silicon nitride waveguides. Here, it has been experimentally shown, for the first time, that by choosing the proper s-SWCNT chirality, the sign of the nonlinear Kerr coefficient of hybrid waveguide can be positive or negative. This unique tuning capability opens a new degree of freedom to control nonlinear effects on chip, enabling to compensate or enhancing nonlinear effects for different applications.

A wrinkling approach was used to study the mechanics of hybrid nanotube/nanocrystal coatings adhering to soft polymer (PDMS) substrates. We focused on three thicknesses: 10 nm, 30 nm, and 40 nm. The approach we used is the Strain-Induced Elastic Buckling Instability for Mechanical Measurements (SIEBIFMM) technique, which allows measurement of the SWCNT film mechanics by the buckling wavelength and the film thickness by inducing a compressive stress in the films at different strains; 2%, 4%, 6%, 8%, 10%, and 12%. In this thesis, dip-coating method with colloidal nanocrystals was used to enhance the rigidity of the carbon nanotube films by filling the pores of the nanotube network. Our results show an almost two-fold enhancement in the Young modulus of a thin SWCNT film related to the presence of a thin interpenetrating over-layer of the semiconductor nanocrystal.

Analytic and computational micromechanics techniques based on the composite cylinders method and the finite element method, respectively, have been used to determine the effective coefficient of thermal expansion (CTE) of carbon nanotube-epoxy nanocomposites containing aligned nanotubes. Both techniques have been used in a parametric study of the influence of interphase stiffness and interphase CTE on the effective CTE of the nanocomposites.  For both the axial and transverse CTE of aligned nanotube nanocomposites with and without interphase regions, the computational and analytic micromechanics techniques were shown to give similar results.  The Mori-Tanka method has been used to account for the effect of randomly oriented fibers.   Analytic and computational micromechanics techniques have also been used to assess the effects of clustering and clustering with interphase on the effective CTE components.  Clustering is observed to have a minimal impact on the effective axial CTE of the nanocomposite and a 3-10%.  However, there is a combined effect with clustering and one of the interphase layers. / Master of Science

Nanofluids consist of nanometer-sized particles or fibers in colloidal suspension within a host fluid. They have been studied extensively since their creation due to their often times anomalous and unique thermal transport characteristics. They have also proven to be quite valuable in terms of the scientific knowledge gained from their study and their nearly unlimited industrial and commercial applications. This research has expanded the science of nanofluids into a previously unexplored field, that of cryogenic nanofluids. Cryogenic nanofluids are similar to traditional nanofluids in that they utilize nanometer-sized inclusion particles; however, they use cryogenic fluids as their host liquids. Cryogenic nanofluids are of great interest due to the fact that they combine the extreme temperatures inherent to cryogenics with the customizable thermal transport properties of nanofluids, thus creating the potential for next generation cryogenic fluids with enhanced thermophysical properties. This research demonstrates that by combining liquid oxygen (LOX) with Multi-Walled Carbon Nanotube (MWCNT) inclusion particles, effective thermal conductivity enhancements of greater than 30% are possible with nanoparticle volume fractions below 0.1%. Three distinct cryogenic nanofluids were created for the purposes of this research, each of which varied by inclusion particle type. The MWCNT's used in this research varied in a number of physical characteristics, the most obvious of which are length and diameter. Lengths vary from 0.5 to 90 microns and diameters from 8 to 40 nanometers. The effective thermal conductivity of the various cryogenic nanofluids created for this research were experimentally determined by a custom made Transient Hot Wire (THW) system, and compared to each other and to more traditional nanofluids as they vary by type and particle volume fraction. This work also details the extensive theoretical, experimental, and numerical aspects of this research, including a rather detailed literature review of many of the salient sciences involved in the study of cryogenic nanofluids. Finally, a selection of the leading theories, models, and predictive equations is presented along with a review of some of the potential future work in the newly budding field of cryogenic nanofluids.

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Rate limited chemical reactions can be enhanced by improving the mass transport of the suspended analyte to the catalytic (or electrocatalytic) surface. While many attempts have been made to enhance this mass transport, these approaches are limited to utilizing only two enhancement methods – increasing available catalytic surface area, and increasing the flow of analyte in solution. Flow through high aspect ratio microstructures, however, would provide additional mass transport enhancement via boundary layer confinement. Platinum functionalized carbon nanotube microarray membranes (Pt-CNT-MMs) offer enhanced mass transport via all three methods, and were fabricated for demonstration in a H2O2 sample system, for which propulsion and chemical sensing applications were investigated. Propulsion testing of Pt-CNT-MM samples demonstrated thrust typically required for MUV propulsion, while achieving high H2O2 fuel utilization. Also, the proposed approach minimizes component exposure to the environment and is comprised of a simple, static architecture relative to other micro-propulsion systems. Moreover, it was shown that additional thrust is attainable by further enhancing the introductory rate of the H2O2 fuel to the Pt-CNT-MMs, which would effectively increase the locomotive capability of this propulsion system. Pt-CNT-MMs used for chemical sensing of H2O2 likewise demonstrated favorable performance. Initial studies revealed that the molar flux achieved for a Pt-CNT-MM sample in a through-flow environment (50 [µL s-1]) was approximately a ten-fold increase over that achieved in a stirred environment (150 [rpm]). This ten-fold increase in molar flux can be attributed to both an increase in exposed electrocatalytic surface area, as well as increase in boundary layer confinement. Furthermore, comparison of sensed molar flux to calculated molar flux for through-flow conditions revealed that Pt-CNT-MMs can achieve near-complete H2O2 oxidation within the flowrate range studied. Additionally, chronoamperometric testing of a Pt-CNT-MM sample demonstrated a sensitivity toward H2O2 of 9.18 [mA mM-1 cm-2], over one hundred times that of the GluOx/Pt-SWCNT/PAA structures referenced herein (0.0724 [mA mM-1 cm-2]).1 These findings suggest that mass transport enhancement, achieved by Pt-CNT-MMs applied in through-flow environments, heightens the performance achieved in rate-limited chemical reactions. Specifically, Pt-CNT-MMs demonstrate high fuel utilization in H2O2 based propulsion applications, as well as offer a highly sensitive preliminary structures for non-invasive glucose sensing.