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Ru(ii) Diimine Complexes Chromophores For Applications In Photodynamic Therapy: Singlet Oxygen Sensitizers And Substitutionally Photolabile ComplexesJanuary 2015 (has links)
1 / Tingting Feng
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Effect of levosimendan on the contractility of muscle fibers from nemaline myopathy patients with mutations in the nebulin genede Winter, J. M., Joureau, B., Sequeira, V., Clarke, N. F., van der Velden, J., Stienen, G. J., Granzier, H., Beggs, A. H., Ottenheijm, C. A. January 2015 (has links)
BACKGROUND: Nemaline myopathy (NM), the most common non-dystrophic congenital myopathy, is characterized by generalized skeletal muscle weakness, often from birth. To date, no therapy exists that enhances the contractile strength of muscles of NM patients. Mutations in NEB, encoding the giant protein nebulin, are the most common cause of NM. The pathophysiology of muscle weakness in NM patients with NEB mutations (NEB-NM) includes a lower calcium-sensitivity of force generation. We propose that the lower calcium-sensitivity of force generation in NEB-NM offers a therapeutic target. Levosimendan is a calcium sensitizer that is approved for use in humans and has been developed to target cardiac muscle fibers. It exerts its effect through binding to slow skeletal/cardiac troponin C. As slow skeletal/cardiac troponin C is also the dominant troponin C isoform in slow-twitch skeletal muscle fibers, we hypothesized that levosimendan improves slow-twitch muscle fiber strength at submaximal levels of activation in patients with NEB-NM. METHODS: To test whether levosimendan affects force production, permeabilized slow-twitch muscle fibers isolated from biopsies of NEB-NM patients and controls were exposed to levosimendan and the force response was measured. RESULTS: No effect of levosimendan on muscle fiber force in NEB-NM and control skeletal muscle fibers was found, both at a submaximal calcium level using incremental levosimendan concentrations, and at incremental calcium concentrations in the presence of levosimendan. In contrast, levosimendan did significantly increase the calcium-sensitivity of force in human single cardiomyocytes. Protein analysis confirmed that the slow skeletal/cardiac troponin C isoform was present in the skeletal muscle fibers tested. CONCLUSIONS: These findings indicate that levosimendan does not improve the contractility in human skeletal muscle fibers, and do not provide rationale for using levosimendan as a therapeutic to restore muscle weakness in NEB-NM patients. We stress the importance of searching for compounds that improve the calcium-sensitivity of force generation of slow-twitch muscle fibers. Such compounds provide an appealing approach to restore muscle force in patients with NEB-NM, and also in patients with other neuromuscular disorders.
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Towards Increased Photovoltaic Energy Generation Efficiency and Reliability: Quantum-Scale Spectral Sensitizers in Thin-Film Hybrid Devices and Microcracking in Monocrystalline SiHuang, Wei-Jie, Huang, Wei-Jie January 2016 (has links)
The present work focuses on two strategies contributing to the development of high efficiency, cost-effective photovoltaic (PV) technology for renewable energy generation: the design of new materials offering enhanced opto-electronic performance and the investigation of material degradation processes and their role in predicting the long-term reliability of PV modules in the field. The first portion of the present work investigates the integration of a novel CdTe-ZnO nanocomposite material as a spectral sensitizer component within a thin-film, hybrid heterojunction (HJ) PV device structure. Quantum-scale semiconductors have the potential to improve PV device performance through enhanced spectral absorption and photocarrier transport. This is realized via appropriate design of the semiconductor nanophase (providing tunable spectral absorption) and its spatial distribution within an electrically active matrix (providing long-range charge transport). Here, CdTe nanocrystals, embedded in an electrically active ZnO matrix, form a nanocomposite (NC) offering control of both spectral absorption and photocarrier transport behavior through the manipulation of nanophase assembly (ensemble effects). A sequential radio- frequency (RF) magnetron sputter deposition technique affords the control of semiconductor nanophase spatial distribution relative to the HJ plane in a hybrid, ZnO-P3HT test structure. Energy conversion performance (current density-voltage (J-V) and external quantum efficiency (EQE) response) was examined as a function of the location of the CdTe nanophase absorber region using both one dimensional solar cell capacitance simulator (SCAPS) and the experimental examination of analogous P3HT-ZnO based hybrid thin films. Enhancement in simulated EQE over a spectral range consistent with the absorption region of the CdTe nanophase (i.e. 400–475 nm) is confirmed in the experimental studies. Moreover, a trend of decreasing quantum efficiency in this spectral range with increasing separation between the CdTe nanophase region and the heterojunction plane is observed. The results are interpreted in terms of carrier scattering/recombination length mitigating the successful transport of carriers across the junction. The second portion of the research addresses the need for robust PV performance in commercial module as a primary contributor to cost-effective operation in both distributed systems and utility scale generation systems. The understanding of physical and chemical mechanisms resulting in the degradation of materials of construction used in PV modules is needed to understand the contribution of these processes to module integrity and performance loss with time under varied application environments. In this context, the second part of present study addresses microcracking in Si–an established degradation process contributing to PV module power loss. The study isolates microcrack propagation in single-crystal Si, and investigates the effect of local environment (temperature, humidity) on microcrack elongation under applied strains. An investigation of microindenter-induced crack evolution with independent variation of both temperature and vapor density was pursued in PV-grade Si wafers. Under static tensile strain conditions, an increase in sub-critical crack elongation with increasing atmospheric water content was observed. To provide further insight into the potential physical and chemical conditions at the microcrack tip, micro-Raman measurements were performed. Preliminary results confirm a spatial variation in the frequency of the primary Si vibrational resonance within the crack-tip region, associated with local stress state, whose magnitude is influenced by environmental conditions during the period of applied static strain. The experimental effort was paired with molecular dynamics (MD) investigations of microcrack evolution in single-crystal Si to furnish additional insight into mechanical contributions to crack elongation. The MD results demonstrate that crack-tip energetics and associated cracking crystal planes and morphology are intimately related to the crack and applied strain orientations with respect to the principal crystallographic axes. The resulting fracture surface energy and the stress-strain response of the Si under these conditions form the basis for preliminary micro-scale peridynamics (PD) simulations of microcrack development under constant applied strain. These efforts were integrated with the experimental results to further inform the mechanisms contributing to this important degradation mode in Si-based photovoltaics.
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Produção e avaliação da estabilidade de nanocápsulas de bixina em sistemas modelo de fotossensitização e aquecimentoLobato, Kleidson Brito de Sousa January 2013 (has links)
A bixina é o principal pigmento presente nas sementes de urucum, é formada de 25 carbonos (9 duplas ligações), absorve luz na região do UV-visível, apresenta capacidade de desativação de oxigênio singlete e espécies reativas de oxigênio. Entretanto, apresenta baixa solubilidade em água, e assim como outros carotenoides, a bixina é instável na presença de oxigênio singlete e altas temperaturas. De modo a aumentar a estabilidade e solubilidade de alguns compostos, são empregadas técnicas, tais como o encapsulamento, que consiste no recobrimento do composto por um agente encapsulante, produzindo partículas. A maioria dos estudos de encapsulamento de carotenoides se dedica a produção de micropartículas e nanopartículas de β-caroteno e até o momento nenhum estudo se dedicou a produção de nanocápsulas de bixina. As nanocápsulas (BIX-LNC) foram produzidas pela técnica de deposição interfacial do polímero poly-ɛ-caprolactone (PCL). A formulação de nanocápsulas foi caracterizadas em termos dos parâmetros de diâmetro médio, potencial zeta, concentração de bixina, eficiência de encapsulamento, viscosidade, pH e cor. Foi avaliada a estabilidade das nanocápsulas durante armazenamento em temperatura ambiente e durante experimentos de fotossensitização a 5, 15 e 25 °C, utilizando rosa de bengala como sensitizador em condições de saturação com ar e nitrogênio (N2) durante 300 minutos, além de avaliação durante aquecimento a 65, 80 e 95 °C na ausência de luz durante 120 minutos. Ambos os experimentos de sensitização e aquecimento foram realizados em sistema-modelo de Etanol:água (2:8). O tamanho das BIX-LNC estava distribuído em um perfil monomodal, com diâmetro médio (z-average) de 199 ± 1,8 nm, índice de polidispersão de 0,12 ± 0,01, diâmetro (D4,3) de 195 ± 26 nm e span de 1,4 ± 0,1. As BIX-LNC foram obtidas com aproximadamente 100 % de eficiência de encapsulamento e teor de 16.92 ± 0.16 μg/ ml. A suspensão BIX-LNC foi classificada como um fluido newtoniano, com viscosidade de 11,4 ± 0,24 mPas e apresentou pH de 5,89 ± 0,70 e potencial zeta de -14,45 ± 0,92 mV. Durante o armazenamento, as BIX-LNC foram consideradas estáveis por não apresentarem alterações significativas no diâmetro médio e no potencial zeta (p< 0,05). Após 119 dias de armazenamento, o teor residual de bixina foi de 45,7 ± 1,1% em relação ao inicial. A degradação bixina livre e nas BIX-LNC obedeceu durante a fotossensitização e aquecimento a uma cinética de degradação de primeira ordem com um coeficiente médio de correlação R2 acima de 0,99. Durante a fotossensitização, a bixina livre apresentou energia de ativação de 7,09 e 8,96 kcal/mol nas condições de saturação com ar e N2, respectivamente, e a bixina encapsulada (BIX-LNC) apresentou energia de ativação de 11,48 e 16,31 kcal/mol nas condições de saturação com ar e N2, respectivamente. Nos experimentos de aquecimento, a bixina livre e encapsulada (BIX-LNC) apresentaram energia de ativação de 15,06 e 23,81 kcal/mol, respectivamente. O encapsulamento demonstrou ser uma técnica adequada para aumentar a solubilidade aparente da bixina em meios aquosos, comprovado pela eficiência de encapsulamento. Além disso, os resultados dos experimentos demonstraram que o encapsulamento promoveu o aumento da estabilidade da bixina durante fotossensitização e aquecimento em sistema modelo de etanol:água (2:8). / Bixin is the main pigment found in annatto seeds, is formed by 25 carbons (with 9 conjugated double bonds), absorbs light in the UV-visible range and deactivates singlet oxygen and reactive oxygen species. Although, bixin is poor-water soluble and like other carotenoids, is unstable in the presence of singlet oxygen and high temperatures. To provide stability, bioavailability and solubility, are applied some strategies, such as the encapsulation technique, which consists of coating a compound with an encapsulating agent to produce particles. Most studies of encapsulated carotenoids concerned the production of microparticles and nanoparticles of β-carotene, although, up to now, no studies have been published concerning the production of bixin nanocapsules and evaluation of their stability. In the present work, the bixin nanocapsules (BIX-LNC) were produced by the technique of interfacial deposition of the preformed polymer poly-ɛ-caprolactone (PCL). The BIX-LNC formulation was characterized for the parameters of mean diameter, zeta potential, bixin concentration, encapsulation efficiency, viscosity, pH and color. The stability of the BIXLNC was evaluate during 119 days of storage at 25 ± 1 ° C and during photosensitization at 5, 15 and 25 °C using rose bengal as the sensitizer in air- and N2 saturated conditions during 300 minutes, and during heating at 65, 80 e 95 °C in the absence of light during 120 minutes. Both experiments were carried out using a model system of ethanol:water (2:8). The nanocapsules obtained in this study were distributed in a monomodal profile with a mean diameter (z-average) of 199 ± 1.8 nm, a polydispersity index of 0.12 ± 0.01, a volume-weighted mean diameter (D4,3) of 195 ± 27 nm and span value of 1.4 ± 0.1. The BIX-LNC were obtained with an encapsulation efficiency approximately of 100 % and concentration of 16.92 μg bixin/ mL. The BIX-LNC suspension was classified as a Newtonian fluid with viscosity of 11.4 mPas ± 0.24, a pH of 5.89 ± 0.70 and a zeta potential of -14.45 ± 0.92 mV. No significant changes (p <0.05) were observed in the mean diameter and zeta potential during 119 days and in the end of the storage. In the end of the storage, 45.7 ± 1.1% of the initial bixin content was found. The bixin loss in the BIX-LNC during photosensitization and heating followed a first-order kinetic decay with an average coefficient correlation R2 greater than 0.99. During photosensitization the free bixin loss had an activation energy of 7.09 and 8.96kca/mol in air and N2-saturated conditions, respectively, and the encapsulated bixin (BIX-LNC) had an activation energy of 15.06 and 23.81 kcal/mol, respectively in the same conditions. Encapsulation showed to be a suitable technique to increase the apparent solubility of bixin in a aqueous media. Moreover, the experiments showed that encapsulation increased the stability of bixin in an aqueous medium during photosensitization and heating.
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Produção e avaliação da estabilidade de nanocápsulas de bixina em sistemas modelo de fotossensitização e aquecimentoLobato, Kleidson Brito de Sousa January 2013 (has links)
A bixina é o principal pigmento presente nas sementes de urucum, é formada de 25 carbonos (9 duplas ligações), absorve luz na região do UV-visível, apresenta capacidade de desativação de oxigênio singlete e espécies reativas de oxigênio. Entretanto, apresenta baixa solubilidade em água, e assim como outros carotenoides, a bixina é instável na presença de oxigênio singlete e altas temperaturas. De modo a aumentar a estabilidade e solubilidade de alguns compostos, são empregadas técnicas, tais como o encapsulamento, que consiste no recobrimento do composto por um agente encapsulante, produzindo partículas. A maioria dos estudos de encapsulamento de carotenoides se dedica a produção de micropartículas e nanopartículas de β-caroteno e até o momento nenhum estudo se dedicou a produção de nanocápsulas de bixina. As nanocápsulas (BIX-LNC) foram produzidas pela técnica de deposição interfacial do polímero poly-ɛ-caprolactone (PCL). A formulação de nanocápsulas foi caracterizadas em termos dos parâmetros de diâmetro médio, potencial zeta, concentração de bixina, eficiência de encapsulamento, viscosidade, pH e cor. Foi avaliada a estabilidade das nanocápsulas durante armazenamento em temperatura ambiente e durante experimentos de fotossensitização a 5, 15 e 25 °C, utilizando rosa de bengala como sensitizador em condições de saturação com ar e nitrogênio (N2) durante 300 minutos, além de avaliação durante aquecimento a 65, 80 e 95 °C na ausência de luz durante 120 minutos. Ambos os experimentos de sensitização e aquecimento foram realizados em sistema-modelo de Etanol:água (2:8). O tamanho das BIX-LNC estava distribuído em um perfil monomodal, com diâmetro médio (z-average) de 199 ± 1,8 nm, índice de polidispersão de 0,12 ± 0,01, diâmetro (D4,3) de 195 ± 26 nm e span de 1,4 ± 0,1. As BIX-LNC foram obtidas com aproximadamente 100 % de eficiência de encapsulamento e teor de 16.92 ± 0.16 μg/ ml. A suspensão BIX-LNC foi classificada como um fluido newtoniano, com viscosidade de 11,4 ± 0,24 mPas e apresentou pH de 5,89 ± 0,70 e potencial zeta de -14,45 ± 0,92 mV. Durante o armazenamento, as BIX-LNC foram consideradas estáveis por não apresentarem alterações significativas no diâmetro médio e no potencial zeta (p< 0,05). Após 119 dias de armazenamento, o teor residual de bixina foi de 45,7 ± 1,1% em relação ao inicial. A degradação bixina livre e nas BIX-LNC obedeceu durante a fotossensitização e aquecimento a uma cinética de degradação de primeira ordem com um coeficiente médio de correlação R2 acima de 0,99. Durante a fotossensitização, a bixina livre apresentou energia de ativação de 7,09 e 8,96 kcal/mol nas condições de saturação com ar e N2, respectivamente, e a bixina encapsulada (BIX-LNC) apresentou energia de ativação de 11,48 e 16,31 kcal/mol nas condições de saturação com ar e N2, respectivamente. Nos experimentos de aquecimento, a bixina livre e encapsulada (BIX-LNC) apresentaram energia de ativação de 15,06 e 23,81 kcal/mol, respectivamente. O encapsulamento demonstrou ser uma técnica adequada para aumentar a solubilidade aparente da bixina em meios aquosos, comprovado pela eficiência de encapsulamento. Além disso, os resultados dos experimentos demonstraram que o encapsulamento promoveu o aumento da estabilidade da bixina durante fotossensitização e aquecimento em sistema modelo de etanol:água (2:8). / Bixin is the main pigment found in annatto seeds, is formed by 25 carbons (with 9 conjugated double bonds), absorbs light in the UV-visible range and deactivates singlet oxygen and reactive oxygen species. Although, bixin is poor-water soluble and like other carotenoids, is unstable in the presence of singlet oxygen and high temperatures. To provide stability, bioavailability and solubility, are applied some strategies, such as the encapsulation technique, which consists of coating a compound with an encapsulating agent to produce particles. Most studies of encapsulated carotenoids concerned the production of microparticles and nanoparticles of β-carotene, although, up to now, no studies have been published concerning the production of bixin nanocapsules and evaluation of their stability. In the present work, the bixin nanocapsules (BIX-LNC) were produced by the technique of interfacial deposition of the preformed polymer poly-ɛ-caprolactone (PCL). The BIX-LNC formulation was characterized for the parameters of mean diameter, zeta potential, bixin concentration, encapsulation efficiency, viscosity, pH and color. The stability of the BIXLNC was evaluate during 119 days of storage at 25 ± 1 ° C and during photosensitization at 5, 15 and 25 °C using rose bengal as the sensitizer in air- and N2 saturated conditions during 300 minutes, and during heating at 65, 80 e 95 °C in the absence of light during 120 minutes. Both experiments were carried out using a model system of ethanol:water (2:8). The nanocapsules obtained in this study were distributed in a monomodal profile with a mean diameter (z-average) of 199 ± 1.8 nm, a polydispersity index of 0.12 ± 0.01, a volume-weighted mean diameter (D4,3) of 195 ± 27 nm and span value of 1.4 ± 0.1. The BIX-LNC were obtained with an encapsulation efficiency approximately of 100 % and concentration of 16.92 μg bixin/ mL. The BIX-LNC suspension was classified as a Newtonian fluid with viscosity of 11.4 mPas ± 0.24, a pH of 5.89 ± 0.70 and a zeta potential of -14.45 ± 0.92 mV. No significant changes (p <0.05) were observed in the mean diameter and zeta potential during 119 days and in the end of the storage. In the end of the storage, 45.7 ± 1.1% of the initial bixin content was found. The bixin loss in the BIX-LNC during photosensitization and heating followed a first-order kinetic decay with an average coefficient correlation R2 greater than 0.99. During photosensitization the free bixin loss had an activation energy of 7.09 and 8.96kca/mol in air and N2-saturated conditions, respectively, and the encapsulated bixin (BIX-LNC) had an activation energy of 15.06 and 23.81 kcal/mol, respectively in the same conditions. Encapsulation showed to be a suitable technique to increase the apparent solubility of bixin in a aqueous media. Moreover, the experiments showed that encapsulation increased the stability of bixin in an aqueous medium during photosensitization and heating.
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Produção e avaliação da estabilidade de nanocápsulas de bixina em sistemas modelo de fotossensitização e aquecimentoLobato, Kleidson Brito de Sousa January 2013 (has links)
A bixina é o principal pigmento presente nas sementes de urucum, é formada de 25 carbonos (9 duplas ligações), absorve luz na região do UV-visível, apresenta capacidade de desativação de oxigênio singlete e espécies reativas de oxigênio. Entretanto, apresenta baixa solubilidade em água, e assim como outros carotenoides, a bixina é instável na presença de oxigênio singlete e altas temperaturas. De modo a aumentar a estabilidade e solubilidade de alguns compostos, são empregadas técnicas, tais como o encapsulamento, que consiste no recobrimento do composto por um agente encapsulante, produzindo partículas. A maioria dos estudos de encapsulamento de carotenoides se dedica a produção de micropartículas e nanopartículas de β-caroteno e até o momento nenhum estudo se dedicou a produção de nanocápsulas de bixina. As nanocápsulas (BIX-LNC) foram produzidas pela técnica de deposição interfacial do polímero poly-ɛ-caprolactone (PCL). A formulação de nanocápsulas foi caracterizadas em termos dos parâmetros de diâmetro médio, potencial zeta, concentração de bixina, eficiência de encapsulamento, viscosidade, pH e cor. Foi avaliada a estabilidade das nanocápsulas durante armazenamento em temperatura ambiente e durante experimentos de fotossensitização a 5, 15 e 25 °C, utilizando rosa de bengala como sensitizador em condições de saturação com ar e nitrogênio (N2) durante 300 minutos, além de avaliação durante aquecimento a 65, 80 e 95 °C na ausência de luz durante 120 minutos. Ambos os experimentos de sensitização e aquecimento foram realizados em sistema-modelo de Etanol:água (2:8). O tamanho das BIX-LNC estava distribuído em um perfil monomodal, com diâmetro médio (z-average) de 199 ± 1,8 nm, índice de polidispersão de 0,12 ± 0,01, diâmetro (D4,3) de 195 ± 26 nm e span de 1,4 ± 0,1. As BIX-LNC foram obtidas com aproximadamente 100 % de eficiência de encapsulamento e teor de 16.92 ± 0.16 μg/ ml. A suspensão BIX-LNC foi classificada como um fluido newtoniano, com viscosidade de 11,4 ± 0,24 mPas e apresentou pH de 5,89 ± 0,70 e potencial zeta de -14,45 ± 0,92 mV. Durante o armazenamento, as BIX-LNC foram consideradas estáveis por não apresentarem alterações significativas no diâmetro médio e no potencial zeta (p< 0,05). Após 119 dias de armazenamento, o teor residual de bixina foi de 45,7 ± 1,1% em relação ao inicial. A degradação bixina livre e nas BIX-LNC obedeceu durante a fotossensitização e aquecimento a uma cinética de degradação de primeira ordem com um coeficiente médio de correlação R2 acima de 0,99. Durante a fotossensitização, a bixina livre apresentou energia de ativação de 7,09 e 8,96 kcal/mol nas condições de saturação com ar e N2, respectivamente, e a bixina encapsulada (BIX-LNC) apresentou energia de ativação de 11,48 e 16,31 kcal/mol nas condições de saturação com ar e N2, respectivamente. Nos experimentos de aquecimento, a bixina livre e encapsulada (BIX-LNC) apresentaram energia de ativação de 15,06 e 23,81 kcal/mol, respectivamente. O encapsulamento demonstrou ser uma técnica adequada para aumentar a solubilidade aparente da bixina em meios aquosos, comprovado pela eficiência de encapsulamento. Além disso, os resultados dos experimentos demonstraram que o encapsulamento promoveu o aumento da estabilidade da bixina durante fotossensitização e aquecimento em sistema modelo de etanol:água (2:8). / Bixin is the main pigment found in annatto seeds, is formed by 25 carbons (with 9 conjugated double bonds), absorbs light in the UV-visible range and deactivates singlet oxygen and reactive oxygen species. Although, bixin is poor-water soluble and like other carotenoids, is unstable in the presence of singlet oxygen and high temperatures. To provide stability, bioavailability and solubility, are applied some strategies, such as the encapsulation technique, which consists of coating a compound with an encapsulating agent to produce particles. Most studies of encapsulated carotenoids concerned the production of microparticles and nanoparticles of β-carotene, although, up to now, no studies have been published concerning the production of bixin nanocapsules and evaluation of their stability. In the present work, the bixin nanocapsules (BIX-LNC) were produced by the technique of interfacial deposition of the preformed polymer poly-ɛ-caprolactone (PCL). The BIX-LNC formulation was characterized for the parameters of mean diameter, zeta potential, bixin concentration, encapsulation efficiency, viscosity, pH and color. The stability of the BIXLNC was evaluate during 119 days of storage at 25 ± 1 ° C and during photosensitization at 5, 15 and 25 °C using rose bengal as the sensitizer in air- and N2 saturated conditions during 300 minutes, and during heating at 65, 80 e 95 °C in the absence of light during 120 minutes. Both experiments were carried out using a model system of ethanol:water (2:8). The nanocapsules obtained in this study were distributed in a monomodal profile with a mean diameter (z-average) of 199 ± 1.8 nm, a polydispersity index of 0.12 ± 0.01, a volume-weighted mean diameter (D4,3) of 195 ± 27 nm and span value of 1.4 ± 0.1. The BIX-LNC were obtained with an encapsulation efficiency approximately of 100 % and concentration of 16.92 μg bixin/ mL. The BIX-LNC suspension was classified as a Newtonian fluid with viscosity of 11.4 mPas ± 0.24, a pH of 5.89 ± 0.70 and a zeta potential of -14.45 ± 0.92 mV. No significant changes (p <0.05) were observed in the mean diameter and zeta potential during 119 days and in the end of the storage. In the end of the storage, 45.7 ± 1.1% of the initial bixin content was found. The bixin loss in the BIX-LNC during photosensitization and heating followed a first-order kinetic decay with an average coefficient correlation R2 greater than 0.99. During photosensitization the free bixin loss had an activation energy of 7.09 and 8.96kca/mol in air and N2-saturated conditions, respectively, and the encapsulated bixin (BIX-LNC) had an activation energy of 15.06 and 23.81 kcal/mol, respectively in the same conditions. Encapsulation showed to be a suitable technique to increase the apparent solubility of bixin in a aqueous media. Moreover, the experiments showed that encapsulation increased the stability of bixin in an aqueous medium during photosensitization and heating.
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The Efficacy of Treatment of Symptoms of Polycystic Ovarian Syndrome and Associated Health Risks Using Insulin Sensitizers: A Meta-AnalysisWong, Isabella J 01 January 2023 (has links) (PDF)
Polycystic Ovarian Syndrome (PCOS) is common among women of reproductive age (ages 15-49), and it can put patients at higher risk for diseases such as type II diabetes or coronary heart disease. While the mechanisms behind PCOS are poorly understood, it is diagnosed using two characteristics: hyperandrogenism and anovulation. Once diagnosed, many patients are also tested for insulin resistance (IR). While IR is thought of as a symptom of PCOS, this study will examine the effects of treatment of IR to manage symptoms of PCOS rather than treatment of hyperandrogenism. This meta-analysis used data from studies previously published by searching for them using key words such as "polycystic ovarian syndrome," "insulin resistance," "hyperandrogenism," and "medication." These data were organized by symptoms studied, and coded. Information extracted was the title, author(s), date of publication, sample size, group characteristics, interventions, and outcomes of each study. This meta-analysis found that the use of insulin sensitizers as treatment for PCOS did not have a greater effect on symptom management than traditional PCOS medications, such as oral contraceptives. These results are useful in the search for a comprehensive and effective treatment of PCOS and may be useful in a clinical setting for treatment guidance purposes.
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Top-Contact Lateral Organic Photodetectors for Deep Ultraviolet ApplicationsBorel, Thomas 20 August 2013 (has links)
Organic semiconductors are very attractive for thin film Organic Photodetectors (OPDs) since they possess a number of desirable attributes for optical sensing including high absorption coefficients over visible and ultraviolet wavelengths and compatibility with large-area deposition processes such as ink-jet, screen printing, and solution processing.
OPDs, in general, utilize a vertical device architecture where the photoactive organic semiconductor layers are sandwiched between top and bottom electrodes that provide electrical contact. More recently, an interest in utilizing a lateral device architecture instead of the vertical one, has emerged. In this architecture, the two contacts are positioned on the two sides of the photoactive material with respect to the direction of the incoming signal, separated by a small gap. However, the factors governing lateral OPDs’ photo-response are still not well understood.
In this thesis, we fabricate top-contact lateral OPDs using a thermal evaporation only fabrication process. We study the factors governing both the dark and photo currents of lateral OPDs. The effect of the wide gap between the two electrodes on the current-voltage characteristics is discussed and the role of space charge limited conduction is investigated. The contributions in the photoresponse of light scattering through the active layers as well as the back reflection of light at the metallic contacts are emphasized.
The reproducibility over repeated operation cycles of both dark and photo currents values is explored. Exposure to light of the lateral OPD is found to lead to a significant increase in the dark current. The role of the conductivity enhancement in the channel due to light-induced trap filling is investigated.
External quantum efficiency and detectivity estimates are given for deep ultraviolet lateral (DUV) OPDs. A comparison with vertical DUV OPDs performances is provided.
Finally, the use of a phosphorescent sensitizer doped in the absorbing bottom layer to improve top-contact lateral OPDs efficiency is discussed.
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Efficient Synthesis Of Novel Near Ir Emitting Distyrylboradiazaindacene Sensitizers For Photodynamic TherapyDost, Zeynep 01 July 2006 (has links) (PDF)
Photodynamic therapy (PDT) is a noninvasive method of treating malignant
tumors and age-related macular degeneration. Current practice of PDT is limited to a
few functionalized porphyrins, however these compounds are not considered to be
ideal drugs for use in PDT. Among the limitations, the most prominent is the low
extinction coefficient of porphyrins in the body& / #8217 / s therapeutic window. Therefore,
there is a significant impetus to develop novel and better efficiency sensitizers for
use in PDT.
Boradiazaindacenes (BODIPY dyes or difluoroboradipyrrines) are well known
fluorescent dyes. We discovered novel distyryl-derivatized boradiazaindacene dyes.
These dyes have strong absorptions beyond 650nm. In order to transform these novel
dyes into potential PDT reagents, bromine substituents were placed and then heavy
atom effect was showed. We also demonstrated that on red-light excitation, singlet
oxygen trap 1,3-diphenyl-iso-benzofuran is rapidly degraded.
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Top-Contact Lateral Organic Photodetectors for Deep Ultraviolet ApplicationsBorel, Thomas 20 August 2013 (has links)
Organic semiconductors are very attractive for thin film Organic Photodetectors (OPDs) since they possess a number of desirable attributes for optical sensing including high absorption coefficients over visible and ultraviolet wavelengths and compatibility with large-area deposition processes such as ink-jet, screen printing, and solution processing.
OPDs, in general, utilize a vertical device architecture where the photoactive organic semiconductor layers are sandwiched between top and bottom electrodes that provide electrical contact. More recently, an interest in utilizing a lateral device architecture instead of the vertical one, has emerged. In this architecture, the two contacts are positioned on the two sides of the photoactive material with respect to the direction of the incoming signal, separated by a small gap. However, the factors governing lateral OPDs’ photo-response are still not well understood.
In this thesis, we fabricate top-contact lateral OPDs using a thermal evaporation only fabrication process. We study the factors governing both the dark and photo currents of lateral OPDs. The effect of the wide gap between the two electrodes on the current-voltage characteristics is discussed and the role of space charge limited conduction is investigated. The contributions in the photoresponse of light scattering through the active layers as well as the back reflection of light at the metallic contacts are emphasized.
The reproducibility over repeated operation cycles of both dark and photo currents values is explored. Exposure to light of the lateral OPD is found to lead to a significant increase in the dark current. The role of the conductivity enhancement in the channel due to light-induced trap filling is investigated.
External quantum efficiency and detectivity estimates are given for deep ultraviolet lateral (DUV) OPDs. A comparison with vertical DUV OPDs performances is provided.
Finally, the use of a phosphorescent sensitizer doped in the absorbing bottom layer to improve top-contact lateral OPDs efficiency is discussed.
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