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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
361

Avaliação do endotélio corneano de equinos após exposição ao corante azul brilhante 0,05% - estudo in vitro

Andrade, Maria Cristina Caldart de January 2016 (has links)
Os corantes vitais têm sido utilizados em diversas áreas da oftalmologia para melhorar a visibilização de diferentes tecidos. Com o objetivo de avaliar os efeitos imediatos do corante Azul brilhante a 0,05% no endotélio da córnea de equinos, foram utilizadas 38 córneas de 19 cavalos, machos ou fêmeas, de diferentes idades e provenientes de abatedouro comercial licenciado. As córneas foram aleatoriamente divididas em dois grupos. Grupo1: o endotélio da córnea foi exposto a solução salina balanceada por 60 segundos. Grupo 2: o endotélio da córnea foi exposto ao corante Azul brilhante 0,05% (Opht-Blue, Ophthalmos, São Paulo, Brazil) por 60 segundos seguido por lavagem com solução salina balanceada (BSS, Ophthalmos, São Paulo, Brazil). As córneas então foram excisadas com trépano de 8mm e preparadas para avaliação com microscopia óptica (24 córneas) e microscopia eletrônica de varredura (14 córneas). As áreas de dano endotelial foram mensuradas. Devido ao aparecimento de resíduos não normais na utilização de comparação de médias via ANOVA, optou-se pelo modelo linear generalizado e, com 5% de significância, o teste Qui-quadrado demonstrou que o fator tratamento não difere do controle. Conclui-se que o corante Azul brilhante em concentração de 0,05% não provocou danos ao endotélio da córnea de equinos. / Vital dyes have been used in many areas of ophthalmology for improving visualization of different tissues. With the objective of evaluating the immediate effects of 0,05% brilliant blue on corneal endothelium of horses, 38 corneas of 19 horses, both male and female of different ages obtained from a licensed Brazilian commercial slaughterhouse were studied. Corneas were randomly divided into two groups. In group 1, corneal endothelium was perfused with BSS for 60 seconds. In group 2, corneal endothelium was perfused with 0.3 mL of brilliant blue 0.05% (Opht-Blue, Ophthalmos, São Paulo, Brazil) for 60 seconds followed by rinsing with a balanced salt solution (BSS, Ophthalmos, São Paulo, Brazil). The corneas were, subsequently, excised with an 8mm trephine and prepared to analyze posterior endothelial surface using a light microscope (24 corneas) and a scanning electron microscope (14 corneas). Due to non-normal residuals at ANOVA mean comparison, a generalized linear model was utilized at 5% level of significance. Qui-square test stated that treatment and control group were not different statistically. The 0.05 % brilliant blue did not damage equine corneal endothelium.
362

Synthèse et études de matériaux organiques absorbeurs visible-proche infrarouge pour la réalisation de cellules solaires hybrides / Synthesis and studies of visible-near infrared absorbing organic materials for hybrid solar cells

Aumaitre, Cyril 20 October 2017 (has links)
A l’échelle mondiale, la part des énergies renouvelables dans le mix énergétique est de plus en plus importante. Basées sur le principe de la photosynthèse, les cellules solaires à colorant sont une des technologies émergentes viables pour une intégration en bâtiment. Ces cellules hybrides utilisent un oxyde semi-conducteur inorganique dont la surface est recouverte d’un colorant organique. L’absorption de la lumière incidente par ce colorant va provoquer l’injection d’un électron de l’état photo-excité de la molécule dans la bande de conduction de l’oxyde. Un médiateur rédox présent dans l’électrolyte va venir régénérer le colorant oxydé et générer un courant sous illumination. Les colorants déjà décrits dans la littérature présentent déjà des rendements de conversion pouvant atteindre 14 % mais très peu de ces matériaux peuvent absorber jusque dans la gamme proche infrarouge (700-1000 nm). Pourtant l’absorption des photons de cette gamme spectrale pourrait mener à une plus grande densité de courant générée et à de meilleures performances globales. Dans ce contexte, ce travail présente une étude complète de nouveaux colorants absorbeurs panchromatiques capable de collecter des photons jusque dans la gamme proche infrarouge. Pour cela, l’approche « donneur-accepteur » a été utilisée afin d’obtenir les propriétés optoélectroniques désirées. Une première famille à base de dérivés du benzothiadiazole a été développée conduisant à de très bonnes propriétés d’absorption dans la gamme proche infrarouge (absorption jusqu’à 925 nm). Les propriétés optiques, électrochimiques et photovoltaïques de ces matériaux ont été étudiées afin de comprendre les limitations de ces matériaux pour une application en cellules solaires. Suite à cela, une nouvelle famille de colorant à base de dérivés de l’isoindigo a été synthétisée et étudiée par spectroscopie UV-Visible, électrochimie et simulation DFT. Ces composés absorbent fortement dans la gamme UV-visible et proche infrarouge jusqu’à 848 nm. Après avoir optimisé les conditions d’imprégnation et de formulation de l’électrolyte, nous avons atteint un rendement de conversion en dispositif de 5,76%. Des mesures photophysiques nous ont permis d’avoir une compréhension fine des facteurs limitant l’efficacité de conversion de ces colorants. Fort de ce constat, nous avons amélioré la structure d’une des molécules pour atteindre un rendement de 7,0 %. Nous avons aussi de manière prospective testé différents matériaux alternatifs au système TiO2/iode classiquement utilisé. / On a global scale, the share of renewable energies in the energy mix is constantly increasing. Based on the principle of photosynthesis, Dye-Sensitized Solar Cells are an emerging technology for Building Integration Photovoltaic (BIPV). These hybrid cells use an inorganic semiconductor oxide whose surface is covered with an organic dye. The absorption of the incident light by this dye will cause the injection of an electron from the photo-excited state of the molecule into the conduction band of the oxide. A redox mediator present in the electrolyte will regenerate the oxidized dye and generate a current under illumination. The dyes already described in the literature shows efficiencies reaching 14%. On the other hand, very few of these materials can absorb up to the near infrared range (NIR) (700-1000 nm). Thereby, the absorption of the NIR spectral range could lead to a greater photo-generated current density. In this context, this work presents a complete study of new panchromatic dyes extending into the near infrared range. For this study, the "donor-acceptor" approach was used to obtain the desired optoelectronic properties. A first family based on benzothiadiazole derivatives has been developed leading to very good absorption properties in the NIR region (absorption up to 925 nm). The optical, electrochemical and photovoltaic properties of these materials have been studied in order to understand the limitations for solar cell applications. Following this, a new dye family based on isoindigo derivatives was synthesized and studied by UV-Visible spectroscopy, electrochemistry and DFT simulation. These compounds strongly absorbs in the UV-visible and NIR spectral range up to 848 nm. The dyeing bath composition and the electrolyte formulation were optimized in order to obtain a device conversion efficiency of 5.76%. Photophysical measurements have allowed us to have a fine understanding of the limiting factors of these dyes. On the basis of this observation, we improved the structure of one of the dye and witg this new molecule we reached a power conversion efficiency of 7.0% with a UV-Visible and near infrared absorption for the solar cell. In the last part of this work we have also obtained preliminary results employing various alternative materials to the TiO2/iodine system.
363

Integration of liquid crystals with redox electrolytes in dye-sensitised solar cells

Bin Kamarudin, Muhammad Akmal January 2018 (has links)
This thesis examines the electro-optic, electric and electrochemical properties of liquid crystal (LC) materials in self-assembly systems, that is, liquid crystal-polymer electrolyte composites (LC-PEs), LC binary mixtures, and their potential application in dye-sensitised solar cells (DSSCs). The birefringence of LCs causes light modulation, which can be controlled by an applied voltage and electric field. In particular, the LCs are used as one of the components for the electrolyte redox couple which is responsible for charge transfer mechanism in DSSCs. In this work, LC-PEs were developed by dissolving LCs in polymer electrolytes; using a homologous series of cyanobiphenyls in a range of concentrations, alkyl chain lengths and dielectric permittivities. We found that doping the polymer electrolyte with 15% 4'-cyano-4'-pentylbiphenyl (5CB) improved ionic conductivity by up to 13 % compared to pure polymer electrolyte. Materials with positive dielectric permittivity and shorter alkyl chain length have been identified to be compatible with iodide/triiodide (I^-/I_3^-)-based polymer electrolytes. In DSSCs, 15% 5CB and 15% E7 LC-PEs exhibited the best efficiencies of 3.6 % and 4.0 %, respectively. In addition to LC-PEs, the self-assembly properties of smectic phase LCs were also utilised as templates for controlling the polymer structure in polymer electrolytes. A porous polymer network was prepared using various techniques including self-assembly, by applying an electric field and using a polyimide (PI) alignment layer. We found that the electrochemical and photovoltaic properties of these materials strongly correlated to the morphology/structure with the self-assembled structure, thus showing the best photovoltaic performance (5.9 %) even when compared with a reference solar cell (4.97 %). Finally, this thesis explores the interaction of LCs with graphene (Gr) in DSSC device architectures. Gr-based DSSCs were fabricated using different processing conditions, with the result being that Gr improved the performance of the DSSCs. The highest efficiency obtained was 5.48 % compared to the 4.86 % of a reference DSSC. The incorporation of LC-PEs in Gr-based DSSCs improved the performance of DSSCs was observed in devices with low concentrations of LCs due to the Gr inducing planar alignment of LCs. These results suggest a new strategy to improve DSSC efficiency by incorporating LC materials in the polymer electrolyte component. Even though these LCs are highly insulating, their self-assembly and dielectric polarisability help enhance ionic conductivity and optical scattering when doped into polymer electrolytes. This work can be extended in a fundamental way to elucidate the ionic conduction mechanism of LC-based electrolyte systems. Furthermore, it would be interesting if the benefits of using LC-PEs and smectic-templated polymer electrolytes (Sm-Pes) can be translated further in commercial electrochemical energy conversion systems.
364

Introducing Plaster : Exploring Artistic Expressions of Natural Dyed Plaster

Krull Eriksen, Katrine January 2018 (has links)
Introducing Plaster is a degree work in textile design exploring the fusion of natural dyes and plaster, and how this can be applied as a textile design material. The outcome is presented as an experimental investigation, placed in the context of surface and material design. This study derived from a growing interest in how new materials can be implemented into the field of textile design using established textile techniques and methods. Natural dye, texture and flexibility where explored through the method of hands-on-experimentation. The study moved foreword by asking the question: “What happens if?”, and the findings have been analyzed and selected for further development. The final collection consists of five pieces made entirely from plaster, showing another approach to how textile techniques and methods can be developed and adapted to fit materials from another field, for instance: Plaster.
365

About Solving and Dissolving : Investigating the design possibilities of bio plastic

Nitsche, Tanja Marie January 2018 (has links)
Translating the conceptual term of sustainability into materials and exploring bio plastics in order to generate visually and tacitly intriguing objects are the aims for this project. Other designers and previous projects in the field of textile design showed how the material works in a small scale. This project used the material’s design properties to generate groups of object elements. The three main design properties of the material, transparency, biomorph expression and flexibility, and their opposites, opaqueness, geometric expression and stiffness, were combined in different sets which resulted in the used artistic methodology. Therefore, the material properties and earlier established techniques formed the base for finding the overall forms of the installations. The collection and a book about the surface design possibilities for plant based plastic show how the material can be manufactured. The installations focus on the interplay between colour, light and shadow, material texture and pattern in relation to the overall shape of the object. Moulding, laser cutting and the addition of other ingredients like recycled paper, fibres and mica powder influenced the material’s durability, flexibility, transparency and texture. Experiments revealed that the colours change over time and all of them are highly influenced in their intensity and shade by the light source behind the material. This project visualises how all these factors interact and which techniques and tools are required to process the new material. Moreover, it generates new options for a new formal language and terminology for sustainable interior textiles.
366

Improving Evaporation Rate of Mine Wastewater

Khumalo, Londiwe Thandeka Precious January 2018 (has links)
Magister Scientiae - MSc (Biotechnology) / The treatment of mine water at the eMalahleni Water Reclamation Plant (EWRP) results in the production of large volumes of brine. Different brine management methods have been applied to dispose the brine but the evaporation pond method is regarded as the cheaper, most effective and less laborious method for brine disposal. Brine wastewater is pumped into the pond where it evaporates resulting in the mixture of salts. The rate at which evaporation occurs is influenced by many factors such as temperature, salinity, humidity and wind. Due to high salinities in brine the EWRP is currently experiencing a challenge with low evaporation rate. Here, a comparative study was done to determine the efficiency of using a chemical and a biological approach to enhance the evaporation rate of reject brine. The chemical approach involved the addition of various concentrations of methylene blue dye (100 to 300 ppm with 50 ppm increments) to 1L volumes of brine, and measuring the evaporation rate. On the other hand, the biological approach involved the isolation of pigmented halophilic bacteria from eMalahleni brine and Cerebos salt samples. Isolated bacterial strains were characterised based on their morphology, biochemical and salt tolerance characteristics. Furthermore, the strains were identified using 16S rRNA gene sequence analysis. Among the isolated halophilic bacterial strains, EP-3, an Arthobacter agilis isolated from the eMalahleni brine produced a darker pigment compared to the other strains. Therefore, EP-3 was evaluated for its effect on the evaporation of brine using a culture inoculum or the addition pigment extracted from an EP-3 culture. The addition of MB above 100 ppm overcame the effect of salt precipitation and resulted in higher evaporation (41%) rate. Addition of pigmented bacteria or bacterial extracted pigment to the brine respectively resulted in 18% and 24% increase in the evaporation rate.
367

Estudo de adsorção do corante reativo laranja 16 com quitosana e seus derivados / Adsorption of study of reactive Orange 16 dye on chitosan and its derivatives

Silva, Andréa Claudia Oliveira 18 January 2017 (has links)
Removal of dyes in industrial effluents has received attention due to increased awareness and stricter environmental laws. Adsorption is one of the techniques successfully employed for effective removal of color. Research has been directed to the type of adsorbent in use. In this work, we used chitosan and its derivatives by physical and chemical modification. The adsorbents in addition to Chitosan (Q) obtained by modification were chitosan crosslinked with Glutaraldehyde (QG), Chitosan Ball crosslinked with Glutaraldehyde dried Alcohol (EQGA), Chitosan Ball crosslinked with Glutaraldehyde dried Greenhouse (EQGE) Chitosan ball crosslinked with glutaraldehyde dried by lyophilization (EQGL), Chitosan Ball with gold nanoparticles incorporated on silica inserted NaOH crosslinked with Glutaraldehyde dried by lyophilization (EQnAuSiO2 - NaOHGL) and Chitosan Ball with gold nanoparticles incorporated on silica inserted into crosslinked gel with Glutaraldehyde dried by lyophilization (EQnAuSiO2 - gelGL). The materials produced were characterized and important information showing the difference between materials, although they are essentially chitosan. The dye used in this work was the dye Reactive Orange 16 (RO16). The best conditions for the adsorption of the dye were obtained by kinetic tests, and thermodynamic equilibrium. For kinetic assays, the equilibration time was about 200 min for the adsorbents. The removal percentage of RL16 dye was around 83% and 99%, with the exception of EQGA which reached a minimum of 13%. As for the kinetic model, we studied the kinetics of pseudo first order and pseudosegunda order, with all adsorbents framed in the kinetics of pseudosegunda order, futher on the analysis by intraparticular diffusion, confirming the influence of more than onde fator in the adsorption. The Langmuir and Freundlich model were used to fit the experimental data, with the QG materials, EQGA and EQGE adjusted to Langmuir isotherm and Q, EQGL, EQnAuSiO2 - NaOHGL and EQnAuSiO2 - gelGL adjusted to Freundlich isotherm. Regarding the various forms of drying the chitosan beads produced, the method by lyophilization presented better removal of the dye under study, including comparing with pure chitosan and chitosan crosslinked with glutaraldehyde. Thus, by comparing the lyophilized adsorbents observed greater efficiency EQnAuSiO2 - gelGL in the removal of the dye with a maximum adsorption capacity of 5000 mgg-1 at 25 °C. According to the thermodynamic information, the adsorptive process is endothermic for QG, EQGA and EQGE being exotherm to Q EQGL, EQnAuSiO2 - NaOHGL and EQnAuSiO2 - gelGL. The enthalpy are supported by the free energy data indicating spontaneous process for Q, EQGL, EQnAuSiO2 - NaOHGL and EQnAuSiO2 - gelGL, and not spontaneous QG, EQGA and EQGE. The results show that the dry sorbent by lyophilization containing gold nanoparticles with incorporation silica at room temperature are the best conditions, according to the data of this work for the removal of dye RO16 can this be used as an alternative for the treatment of wastewater from textile industry. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A remoção de corantes em efluentes industriais tem recebido enorme atenção, devido ao aumento da conscientização e ao maior rigor das leis ambientais. A adsorção é uma das técnicas empregada com sucesso para remoção efetiva da cor. Pesquisas vêm sendo direcionadas para o tipo de adsorventes em uso. Neste trabalho, utilizou-se quitosana e seus derivados por modificação física e química. Os adsorventes além da quitosana (Q), obtidos por modificação da mesma foram, Quitosana reticulada com Glutaraldeído (QG), Esfera de Quitosana reticulada com Glutaraldeído seca à Álcool (EQGA), Esfera de Quitosana reticulada com Glutaraldeído seca à Estufa (EQGE), Esfera de Quitosana reticulada com Glutaraldeído seca por Liofilização (EQGL), Esfera de Quitosana com nanopartículas de ouro incorporadas em sílica inseridas em NaOH reticulada com Glutaraldeído seca por Liofilização (EQnAuSiO2 – NaOHGL) e Esfera de Quitosana com nanopartículas de ouro incorporadas em sílica inseridas em gel reticulada com Glutaraldeído seca por Liofilização (EQnAuSiO2 – gelGL). Os materiais produzidos foram caracterizados e informações importantes mostram a diferença entre os materiais, apesar de serem essencialmente quitosana. O corante utilizado no presente trabalho foi o corante Reativo Laranja 16 (RL16). As melhores condições para a adsorção deste corante foram obtidas, mediante ensaios cinéticos, de equilíbrio e termodinâmicos. Para os ensaios cinéticos, o tempo de equilíbrio foi em torno de 200 min para os adsorventes. O percentual de remoção do corante RL16 foi em torno de 83% e 99%, com exceção do EQGA que chegou a atingir um mínimo de 13%. Quanto ao modelo cinético, foram estudados a cinética de pseudoprimeira ordem, pseudosegunda ordem, estando todos os adsorventes enquadrados na cinética de pseudosegunda ordem, além da análise por disfusão intrapartícula, confirmando a influência de mais de um fator na adsorção. Os modelos de Langmuir e Freundlich foram utilizados para ajustar os dados experimentais, estando os materiais QG, EQGA e EQGE ajustados para isoterma Langmuir e Q, EQGL, EQnAuSiO2 – NaOHGL e EQnAuSiO2 – gelGL ajustados para isoterma Freundlich. Em relação as diferentes formas de secagem das esferas de quitosana produzidas, o método por liofilização apresentou a melhor remoção do corante em estudo, inclusive comparando com a quitosana pura e a quitosana reticulada com glutaraldeído. Desta forma, ao comparar os adsorventes liofilizados observa-se uma maior eficiência para EQnAuSiO2 – gelGL na remoção do corante, com uma capacidade máxima de adsorção de 5000 mgg-1 a 25 °C. De acordo com as informações termodinâmicas, o processo adsortivo é endotérmico para QG, EQGA e EQGE, sendo exotérmico para Q, EQGL, EQnAuSiO2 – NaOHGL e EQnAuSiO2 – gelGL. As informações de entalpia são corroboradas pelos dados de energia livre indicando processo espontâneo para Q, EQGL, EQnAuSiO2 – NaOHGL e EQnAuSiO2 – gelGL, e não espontâneo para QG, EQGA e EQGE. Os resultados obtidos mostram que o adsorvente seco por liofilização contendo nanopartículas de ouro com incorporação de sílica à temperatura ambiente são as melhores condições, segundo os dados deste trabalho para a remoção do corante RL16 podendo este ser empregado como alternativa para o tratamento dos efluentes aquosos da indústria têxtil.
368

Linfonodo axilar como sentinela nas neoplasias mamárias de cadelas submetidas à mastectomia unilateral total

Bianchi, Simone Passos January 2015 (has links)
O estudo dos tumores de mama que afetam cadelas é de grande importância devido à alta frequência com que surgem na clínica de pequenos animais, sendo a neoplasia mais comum em cadelas. É necessário obter maior conhecimento sobre a circulação linfática na glândula mamária e suas possibilidades de comunicação para que a técnica cirúrgica adequada seja escolhida. O presente estudo teve como objetivo avaliar a importância da retirada do linfonodo axilar com auxílio do corante azul patente em neoplasias mamárias de cadelas. Nesse experimento foram avaliadas 49 cadelas com neoplasia mamária submetidas a mastectomia unilateral total. O corante azul patente 2,5% foi aplicado na região intradérmica periareolar da mama torácica cranial como forma de identificação da drenagem linfática da mama e a localização do linfonodo na região axilar das pacientes. Após sua ressecção, o linfonodo foi submetido a análise histopatológica e imuno-histoquímica para procura de metástase. Como resultado foram encontrados 8 (16,33%) animais com metástase em linfonodo axilar, sendo sete pela histopatologia e um somente pela técnica de imuno-histoquímica usando o anticorpo citoqueratina. Um animal que apresentava nódulo mamário em mama abdominal caudal apresentou metástase em linfonodo axilar, o que sugere que a presença de tumor provoca linfangiogênese, ou seja, neoformação na drenagem linfática perdendo o padrão de drenagem da cadeia mamária já descrito. Esse estudo mostrou que a técnica de coloração de linfonodo axilar foi de fácil execução, facilitou a retirada do linfonodo axilar, sendo indicada sua retirada em mastectomia de cadelas devido à significante presença de célular tumorais no mesmo. / The study of breast tumours affecting dogs is of great importance due to the high frequency in which they occur in clinical small animal, being the most common cancer in dogs. Greater insight must be obtained into the lymphatic circulation in the mammary gland and its communication possibilities for the adequate surgical technique to be chosen. This study aimed to evaluate the importance of the withdrawal of axillary lymph node in breast tumours in bitches with the help of patent blue dye. In this experiment, 49 bitches with mammary tumours undergoing unilateral total mastectomy were evaluated. The 2.5% blue dye was administered intradermally in the periareolar cranial thoracic region of the breast as a means of identifying lymphatic drainage of breast cancer and the location of the lymph node in the axilla of the patient. After resection, the lymph nodes were subjected to histopathologic and immunohistochemical analysis to search for metastasis. We found 8 (16.33%) animals with metastatic axillary lymph node, seven by histopathology and only one by immunohistochemical technique using cytokeratin antibody. One of the animals with caudal abdominal mammary gland tumour was found to have metastasis in the breast axillary lymph, suggesting that the presence of tumour lymphangiogenesis. We found that the axillary lymph node staining technique was easy to perform and facilitated the removal of axillary lymph node. Our results suggest that the removal of the axillary lymph node is indicated in bitches submitted to mastectomy due to the significant presence of metastasis in this ganglion.
369

Advances in hybrid solar cells : from dye-sensitised to perovskite solar cells

Noel, Nakita K. January 2014 (has links)
This thesis presents a study of hybrid solar cells, specifically looking at various methods which can be employed in order to increase the power conversion efficiency of these devices. The experiments and results contained herein also present a very accurate picture of how rapidly the field of hybrid solar cells has progressed within the past three years. Chapters 1 and 2 present the background and motivation for the investigations undertaken, as well as the relevant theory underpinning solar cell operation. Chapter 2 also gives a brief review of the literature pertinent to the main types of devices investigated in this thesis; dye-sensitised solar cells, semiconductor sensitized solar cells and perovskite solar cells. Descriptions of the synthetic procedures, as well as the details of device fabrication and any measurement techniques used are outlined in Chapter 3. The first set of experimental results is presented in Chapter 4. This chapter outlines the synthesis of mesoporous single crystals (MSCs) of anatase TiO<sub>2</sub> as well as an investigation of its electronic properties. Having shown that this material has superior electronic properties to the conventionally used nanoparticle films, they were then integrated into low temperature processed dye-sensitised solar cells and achieved power conversion efficiencies of &GT; 3&percnt;, exhibiting electron transport rates which were orders of magnitude higher than those obtained for the high temperature processed control films. Chapter 5 further investigates the use of MSCs in photovoltaic devices, this time utilising a more strongly absorbing inorganic sensitiser, Sb<sub>2</sub>S<sub>3</sub>. Utilising the readily tunable pore size of MSCs, these Sb<sub>2</sub>S<sub>3</sub> devices showed an increase in voltage and fill factor which can be attributed to a decrease in recombination within these devices. This chapter also presents the use of Sb<sub>2</sub>S<sub>3</sub> in the meso-superstructured configuration. This device architecture showed consistently higher voltages suggesting that in this architecture, charge transport occurs through the absorber and not the mesoporous scaffold. Chapters 6 and 7 focus on the use of hybrid organic-inorganic perovskites in photovoltaic devices. In Chapter 6 the mixed halide, lead-based perovskite, CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3-x</sub>Cl<sub>x</sub> is employed in a planar heterojunction device architecture. The effects of Lewis base passivation on this material are investigated by determining the photoluminescence (PL) lifetimes and quantum efficiencies of treated and untreated films. It is found that passivating films of this material using Lewis bases causes an increase in the PLQE at low fluences as well as increasing the PL lifetime. By globally fitting these results to a model the trap densities are extracted and it is found that using these surface treatments decreases the trap density of the perovskite films. Finally, these treatments are used in complete solar cells resulting in increased power conversion efficiencies and an improvement in the stabilised power output of the devices. Chapter 7 describes the materials synthesis and characterisation of the tin-based perovskite CH<sub>3</sub>NH<sub>3</sub>SnI<sub>3</sub> and presents the first operational, lead-free perovskite solar cell. The work presented in this thesis describes significant advances in the field of hybrid solar cells, specifically with regards to improvements made to the nanostructured electrode, and the development and implementation of more highly absorbing sensitizers. The improvements discussed here will prove to be quite important in the drive towards exploiting solar power as a clean, affordable source of energy.
370

Extração de pigmentos carotenóides da carapaça do camarão e sua utilização em um produto derivado de pescado / Extraction of carotenoid pigments of the carapace of shrimp and their use in a by-product of fish

Pinho, Erotéide Leite de January 2001 (has links)
PINHO, Erotéide Leite de. Extração de pigmentos carotenóides da carapaça do camarão e sua utilização em um produto derivado de pescado. 2001. 48 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Tecnologia de Alimentos, Fortaleza-CE, 2001 / Submitted by Nádja Goes (nmoraissoares@gmail.com) on 2016-06-03T13:54:29Z No. of bitstreams: 1 2001_dis_elpinho.pdf: 379735 bytes, checksum: 56d523219601d0f6243134cbd8534ed3 (MD5) / Approved for entry into archive by Nádja Goes (nmoraissoares@gmail.com) on 2016-06-03T13:55:13Z (GMT) No. of bitstreams: 1 2001_dis_elpinho.pdf: 379735 bytes, checksum: 56d523219601d0f6243134cbd8534ed3 (MD5) / Made available in DSpace on 2016-06-03T13:55:13Z (GMT). No. of bitstreams: 1 2001_dis_elpinho.pdf: 379735 bytes, checksum: 56d523219601d0f6243134cbd8534ed3 (MD5) Previous issue date: 2001 / Waste material in the fish industry including the shells from the crustacean, constitute a very high percentage. These shells are rich in carotenoids pigments, which may have a high pigmentation value when used in foods. It is common in some countries the use of the extracted pigments in feeds.The aim of this experiment was to study the process of carotenoids extraction and to verify its pigmenting potential in a minced fish food product. The solvent extraction technique was used after testing other extraction procedures. Extracted pigments were characterized by spectrophotometry. Pigments were then included in the fish formulation. Fish products were packaged with and without vacuum and storage in the dark at –20ºC for 60 days. The color of the products was measured every 15 days with the CIE system which determines parameters L*, a* and b*. The spectrophotometry study showed products of degradation of astaxanthin in the shell extract. The luminosity (L*) of the color in products packaged under vacuum was lower (p<0.05) with 15 and 45 days of storage than in those stored without vacuum. Vacuum packaged products showed that with 0 days of storage the yellowness component (b*) was higher (p<0.05) in vacuum packaged products than in those stored without vacuum. The reverse occurring with 45 days of storage. After 60 days frozen storage vacuum packaging did not affect the color characteristics of the fish product. / O descarte na indústria de pescado, inclusive o de carapaças de crustáceos, constitui um percentual bastante elevado. Estas cascas são ricas em pigmentos carotenóides, os quais, apresentam um alto valor de pigmentação, sendo corrente em alguns países a extração e posterior utilização dos mesmos em rações. O objetivo deste experimento foi estudar a extração dos pigmentos carotenóides das cascas de camarão e verificar seu potencial de uso como aditivo natural de cor em um produto à base de pescado. Neste estudo foram desenvolvidos testes preliminares para escolha de um método para a extração dos pigmentos optando-se pela extração com solvente. Caracterizou-se ospigmentos extraídos das cascas de camarão e avaliou-se a influência do extrato pigmentado aplicado em um produto à base de pescado, o qual foi embalado à vácuo e sem vácuo e submetido à uma estocagem (-20ºC) durante um período de60 dias. A cor dos produtos foi medida a cada 15 dias no sistema CIE determinando-se os parâmetros de L*, a* e b*. A análise espectrofotométrica do extrato de camarão apresentou produtos de degradação da astaxantina. Os produtos pigmentados com o extrato de camarão e embalados à vácuo apresentaram valores de luminosidade (L*) menores (p < 0,05) que os embalados sem vácuo com 15 e 45 dias de armazenamento. Para o componente de intensidade de cor amarela (b*) os produtos embalados à vácuo apresentaram valores maiores (p<0,05) no início do armazenamento (0 dias) e menores (p<0,05) com 45 dias de armazenamento, em relação àqueles embalados sem vácuo. Contudo, no período de 60 dias de armazenamento não foi observado efeito significativo da embalagem à vácuo sobre as características de cor dos produtos.

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