Ce travail de thèse est consacré à l’étude des propriétés magnéto-optiques de nanoparticules (NP) magnétiques de ferrite de cobalt (CoFe2O4) sous forme liquide et lorsqu’elles sont bloquées dans une matrice de silice produite par voie sol-gel. Cette dernière dispersion constitue un matériau composite à activité magnéto-optique obtenu par un procédé basse température qui le rend totalement compatible avec les technologies d’intégration. A plus long terme, ce matériau pourra contribuer à l’intégration de composants non-réciproques. L’objectif de ce travail est d’une part l’identification du type de NP qui maximise la rotation Faraday et le facteur de mérite (rapport de la rotation Faraday à l’absorption) dans le but d’améliorer la qualité magnéto-optique du matériau composite. Et d’autre part, il s’agit d’améliorer la compréhension des phénomènes physiques liés aux effets magnéto-optiques de ces nanoparticules et le lien avec leurs caractéristiques physiques. L’étude est menée sur des NP magnétiques synthétisées et dispersées en phase aqueuse au laboratoire PHENIX (UMR CNRS 8234). Les mesures optiques et magnéto-optiques réalisées au laboratoire Hubert Curien (UMR CNRS 5516) ont été complétées par des mesures magnétiques XMCD au synchrotron SOLEIL. L’étude des différentes nanoparticules magnétiques a révélé que l’utilisation d’une petite taille de NP permet de multiplier par deux le facteur de mérite du matériau pour une longueur d’onde de 1,5 µm, soit une division par deux des pertes pour les composants magnéto-optiques visés. L’analyse du comportement spectral de l’effet Faraday illustre l’influence de la distribution cationique des ions Co2+ et Fe3+ dans la structure cristalline. Couplée aux mesures XMCD, l’analyse montre le besoin d’une localisation de l’ion Co2+ en site tétraédrique dans la structure spinelle pour maximiser l’effet Faraday à 1,5µm, et obtenir une anisotropie uniaxe qui permette une pré-orientation aisée des NP lors de la gélification / This work is dedicated to the study of the magneto-optical properties of cobalt ferrite (CoFe2O4) nanoparticles (NP) dispersed in liquid as ferrofluid, or blocked in a solid silica matrix realized with a sol-gel method. This last dispersion is a magneto-optical composite material, obtained with a low temperature process which insures its compatibility with photonic integration technologies, to produce, in the future, integrated non-reciprocal devices. The aim of the study is, on one hand, to identify which kind of NP can improve the Faraday effect and the merit factor (ratio between the Faraday effect and the absorption) of the composite material. On the other hand, the aim is to give a better understanding of the link between the magneto-optical properties and the physical characteristics of the NP. The study has been led on NP synthetized and dispersed as ferrofluid in PHENIX laboratory (UMR CNRS 8234). Optical and magneto-optical measurements were made in Hubert Curien laboratory (UMR CNRS 5516) and completed by XMCD analysis in Synchroton SOLEIL. Results show that it is necessary to use a small size of NP (5 nm) to maximize the merit factor at a wavelength of 1,5 µm. The spectral analysis of the Faraday effect shows the influence of the cationic distribution of Co2+ et Fe3+ in the spinelle structure. Coupled to XMCD results, this analysis shows that it is necessary to maximize the quantity of Co2+ in tetraedric sites to maximize the Faraday effect at 1,5 µm and to obtain an uniaxial anisotropy which allows to orientate the NP during the gelification of the sol-gel matrix

Medidas de transmitância em óculos de sol fazem parte de alguns dos testes propostos pela norma NBR15111, porém, observou-se que não há no país um sistema preciso para medidas de transmitância que não seja com o uso de espectrofotômetros e pessoas qualificadas para utilizar o equipamento, aplicar as funções de ponderação e fornecer laudos técnicos sobre a lente testada. Assim, o trabalho propõe métodos que utilize componentes simples e resulte na construção de um equipamento que possa fornecer a informação sobre as transmitâncias dos filtros de óculos de sol de forma automática, de acordo com a NBR15111. Foi feita a espectrofotometria de 45 lentes de óculos de uso geral, e calculadas suas respectivas transmitâncias (luminosa, ultravioleta, semafórica), como amostras de comparação com as metodologias testadas. Os testes incluíram lâmpadas e LEDs como fontes de emissão para a região do espectro visível e lâmpadas fluorescentes para a região ultravioleta, além de sensores específicos para cada região espectral, e eletrônica de controle e aquisição dos sinais. Foram usadas ferramentas de análise estatística, como erro RMS, coeficiente de aderência (GFC) e análise de Bland-Altman. Aproximadamente 62% dos óculos testados foram reprovados para a direção no trânsito e nenhum foi reprovado para a proteção UV. Os métodos RMS e GFC apontaram combinações entre fonte e sensor que conseguem fazer a ponderação com os menores desvios-padrão das medidas espectrométricas. O sistema para teste UV mostrou melhoria significativa em relação aos desenvolvidos anteriormente, com um desvio padrão de 4,45 pontos percentuais e o sistema para testes na região visível utilizou o sensor TCS, no qual a regressão polinomial mostrou melhores resultados que as redes neurais artificiais, com os menores limites de concordância para as transmitâncias. Um número maior de amostras pode melhorar os métodos para que se obtenha uma aproximação ideal para todos os óculos de sol. Uma montagem com LEDs se apresenta como uma alternativa interessante quanto ao custo, tamanho e baixo consumo para medidores de transmitância portáteis. Desenvolveu-se um sistema com módulos para teste UV, Visível e Semafórico, para uso público no campus da USP de São Carlos, proporcionando conscientização e extensão dos estudos em relação aos óculos solares, contribuindo efetivamente com a população brasileira. / Transmittance measurements in sunglasses are a part of the standard tests proposed by NBR15111, however, it was observed that there is no accurate system for measuring transmittance different than using spectrophotometers and skilled practitioner to manage the equipment, apply the weighting functions and provide technical reports on the lens tested. Therefore, this study proposes methodologies using simple components and that can result a device that can provide information about sunglass filters automatically, according to NBR15111. Spectrophotometry was calculated in 45 lenses of sunglasses for general use, and their respective transmittance (visible, ultraviolet, traffic light), used as samples for testing the methodologies. The tests included lamps and LEDs as light sources for the visible region spectrum and fluorescent lamps for ultraviolet region, specific sensors for each spectral region, and electronic for control and signal acquisition. Statistical analysis tools were used, such as RMS error, goodness-of-fit coefficient (GFC) and the Bland - Altman analysis. Approximately 62% of the tested lenses failed in the test for signal light recognition and none has failed for UV protection. The RMS and GFC methods indicated combinations between source and sensor that calculated transmittance with the lowest standard deviations of the spectrometric measurements. The system for testing UV showed improvement compared to other previously equipment, with a standard deviation of 4.45 and the system for testing the visible region used the TCS sensor, in which the polynomial regression showed better results than artificial neural networks. A larger number of samples can improve the methods in order to obtain an optimal calibration that includes all sunglasses. LEDs seem to be a good alternative in terms of cost, size and low power consumption for portable transmittance meters. We developed a system with modules for testing UV, Visible and Traffic Light transmittance for public use on the USP São Carlos campus, providing awareness and extent of studies about the sunglasses, in order to contribute more effectively to the Brazilian population.

A radiação ultravioleta pode tanto ser um benefício, como um malefício para o olho humano. Os benefícios são quando é utilizada em procedimentos oftalmológicos para a correção da visão, como nas cirurgias foto-refrativas - UVC - 193 nm; ou para, entre outros tratamentos, impedir a progressão de patologias, como é o caso do crosslinking do colágeno corneano, para ceratocones em estágios inicias que utiliza UVA - 370 nm. Os malefícios são os já amplamente conhecidos pela comunidade científica e populacional, sobre a incidência excessiva de radiação UV nos olhos, causando danos severos ao olho humano. Entretanto, a córnea tem uma proteção natural contra os raios UVA e UVB. Neste trabalho, estudou-se os dois procedimentos oftalmológicos citados a fim de investigar possíveis danos ao olho humano, como a perda da proteção natural da córnea pós cirurgia foto-refrativa, que retira lamelas da córnea; e a quantidade de radiação que adentra o olho humano, durante o crosslinking do colágeno corneano, que utiliza Riboflavina como sintetizador e bloqueador da radiação UVA. Um sistema portátil foi desenvolvido para avaliação da proteção UV e seus danos para o primeiro caso. O protótipo consiste de um sistema de duplo feixe e analisa a transmitância do tecido corneano na faixa de 300-400 nm, e apresenta um fator de correlação r2>0,98. As medidas com remoção de tecido indicaram a importância das camadas da córnea, e a remoção do estroma apresentou uma perda significativa da proteção natural UV, com aumento de 8,2-10,1 pontos percentuais. Já para o crosslinking, que utiliza a combinação riboflavina e UVA, com irradiância de 3 mw/\'CM POT.2\' por 30 minutos foi feito o monitoramento da transmitância UVA durante o tratamento. Foi realizado o protocolo do procedimento atual, ou seja, uma gota de Riboflavina 0,1%, 400mOsm, foi instilada na córnea desepitelizada, a cada 5 minutos (total de 12 gotas). A irradiação UV (365 ± 5 nm, 3 mW/\'CM POT.2\') foi realizada após 30 min de instalação por uma adicional de mais 30 min. A transmitância média da córnea desepitelizada sem Riboflavina foi de 61,6%; após a 1ª instilação de Riboflavina a transmitância foi de 44,9%; após a 6ª gota 22,4%; após a 7ª gota (início da irradiação), 19,5%; após a 8ª gota, 17,3%; após a 9ª, 15,8%; após a 10ª; 14,5%; após a 11ª; 13,5%; e após a 12ª instilação, 12,6%. A transmitância média em termos de energia durante os 30 min de irradiação apresentou uma variação de 0,590 até 0,380 mW/\'CM POT.2\', valores além do limite atualmente aceito para endotélio de córneas de coelhos, que apresenta um nível de segurança citotóxico de 0,36 mW/\'CM POT.2\'. / Ultraviolet radiation can either be a benefit as an harm to the human eye. The benefits are when used in ophthalmic procedures for vision correction, as in the photorefractive surgery - UVC - 193 nm; or to, among other treatments, preventing the progression of diseases, such as the corneal collagen crosslinking, for keratoconus in the early stages - that uses UVA - 370 nm. The harm effects are already widely known by the scientific community and general population, about excessive incidence of UV radiation in the eye, that can cause severe damage to the human eye. However, the cornea has a natural UVA and UVB protection. In this work, we studied the two ophthalmic procedures cited in order to investigate possible damage to the human eye, as the loss of cornea UV natural protection after photorefractive surgery, which removes corneal lamella; and the amount of radiation that penetrates the human eye during the corneal collagen crosslinking, that uses Riboflavin as a synthesizer and UVA radiation blocking. A portable system was developed to evaluate the UV protection and the UV damage for the first case. The prototype consists of a double beam system that analyzes the corneal tissue transmittance in the 300-400 nm range, and presents a correlation factor r2>0.98. Measurements with tissue removal showed the importance of each corneal layer, specially the stroma removal that shows a significant loss of natural UV protection, with an increase of 8.2 to 10.1 percentage points. As for the crosslinking, using riboflavin and UVA irradiance combination, with 3 mw/\'CM POT.2\' for 30 minutes, was performed a monitoring of UVA transmittance during treatment. Current procedure protocol was performed, i.e., one drop of riboflavin 0.1%, 400mOsm, was applied on the naked cornea, every 5 minutes (total of 12 drops). The UV irradiation (365 ± 5 nm, 3 mW/\'CM POT.2\') was performed after 30 min of instillation for an additional 30 min. The average transmittance of the desepithelized cornea without Riboflavin is 61.6%; after the 1st drop of Riboflavin, transmittance is 44.9%; after 6th drop 22.4%; after 7th drop (irradiation starts), 19.5%; after 8th drop; 17.3%; after 9th drop, 15.8%; after 10h drop, 14.5%; after 11th drop, 13.6%; after 12th drop, 12.6%. The average transmittance in terms of energy during the 30 min irradiation procedure fluctuated from 0.590 to 0.380 mW/\'CM POT.2\', beyond the currently accepted rabbit corneal endothelium safety limit for cytotoxic level of 0.360 mW/\'CM POT.2\'.

Este trabalho estuda a propagação da luz no esmalte e dentina humanos, através da transmitância direta e absorbância no intervalo de comprimento de onda de 200 a 3200nm, e através da transmitância total no intervalo de onda de 380 a 760nm. Foram utilizadas secções de 30 molares humanos íntegros, que foram seccionados nos sentidos VL (vestíbulo – Lingual), MD (mésio distal) e OC (ocluso cervical). As espessuras utilizadas foram de 0,5mm e 0,25mm. Foram agrupados 5 dentes para cada sentido para cada espessura. Esmalte e dentina estavam presentes de maneira simultânea na mesma amostra. A absorbância foi calculada, a partir dos espectros de transmitância direta, aplicando-se a Lei e Beer-Lambert. Os espectros de transmitância total foram obtidos no espectro visível, e comparados, em média, com os espectros de transmitância direta no mesmo intervalo, para obter a energia difusa das amostras. Os espectros UV (Ultravioleta), VIS (Visível) e IV (Infravermelho), foram tratados separadamente para cada tecido e espessura. No infravermelho foram identificados os picos de transmitância e absorbância para ambos os tecidos. Os valores de transmitância e absorbância para cada faixa espectral foram tratados pela ANOVA, e os grupos comparados pelo teste de intervalo de confiança (95%). Os resultados mostraram que, as propriedades ópticas do esmalte e dentina diferem no que diz respeito as 3 faixas espectrais testadas. Os resultados também mostram que as propriedades ópticas são dependentes da espessura e do sentido de seccionamento dos dentes. A pesar das diferenças apresentadas entre os espectros, as curvas espectrais mostraram um padrão semelhante para todas as amostras de dentina e de esmalte, independente da espessura. Este comportamento possibilitou a identificação de picos comuns nos espectros estudados. / This research studies the propagation of light in the human enamel and dentine, through direct transmittance and absorbance in the 200 to 3200nm wavelength interval, and through total transmittance in the 380 to 760nm wavelength interval. The study employed sections of 30 human integral molars, which were sectioned in the VL directions (vestibule – Lingual), MD (mesio distal), and OC (occlusion cervical). The thicknesses used were from 0.5mm to 0.25mm. Five teeth were grouped in each direction for each thickness. Enamel and dentine were simultaneously present in the same sample. Absorbance was calculated from the direct transmittance specters, applying the Beer-Lambert Law. Total transmittance specters were obtained in the visible specter, and compared, on average, with the Total transmittance specters in the same interval, to obtain the diffuse energy of the samples. UV (Ultraviolet), VIS (Visible), and IV (Infrared) specters, were treated separately for each tissue and thickness. In infrared, the transmittance and absorbance peaks were identified for both tissues. The transmittance and absorbance spectral range were treated by ANOVA, and the groups compared by the confidence interval test (95%). The results showed that the optical properties of the enamel and dentine differ with regard to the three tested spectral ranges. The results also showed that the optical properties are dependent on the thickness and the direction of the sectioning of the teeth. Despite the differences found between the specters, the special curves showed a similar pattern for all samples of dentine and enamel, independently of the thickness. This behavior allowed the identification of common peaks in the specters under study.

O objetivo desta pesquisa foi avaliar a transmitância de diferentes tipos e cores de cerâmicas e seus efeitos no grau de conversão (GC) de dois tipos de cimentos resinosos com modo de polimerização dual. Foram confeccionadas 60 pastilhas com a cerâmica IPS e.max (Ivoclar Vivadent, Schaan, Liechtenstein) e divididas em 3 grupos: LT, MO e Z, com 20 pastilhas cada um. Nos grupos LT e MO, as pastilhas foram confeccionadas com a cerâmica de dissilicato de lítio de baixa translucidez (LT - low transluscency) e de média opacidade (MO - medium opacity), respectivamente. No grupo Z, as pastilhas foram confeccionadas em zircônia. Cada grupo foi subdividido em 5 subgrupos (n=4), de acordo com a cor da cerâmica: A2; A3,5; B2; C2; D3. No grupo LT, as pastilhas foram prensadas nas cores anteriormente citadas e, nos grupos MO e Z, as pastilhas foram, inicialmente, confeccionadas para simular infraestruturas e, posteriormente, receberem aplicação de cerâmica de revestimento IPS e.max Ceram (Ivoclar Vivadent, Schaan, Liechtenstein) nas mesmas cores. O espectrofotômetro UV 1800 Shimadzu foi utilizado para medir a transmitância de cada espécime de cerâmica (2,0 mm de espessura). Para medir o GC, espécimes dos cimentos resinosos Variolink II (Ivoclar Vivadent, Schaan, Liechtenstein) e Rely X U200 (3M ESPE, St. Paul, MN, USA), com espessura de 100 μm, foram fotopolimerizados sob os discos de cerâmica por 40 s. Espécimes dos cimentos fotoativados sem a interposição da cerâmica foram usados como grupo controle. A polimerização dos cimentos foi avaliada através da espectrometria no infravermelho com transformada de Fourier (FTIR) empregando o método de reflexão atenuada total (ATR) imediatamente após a fotopolimerização. Os resultados foram submetidos aos testes ANOVA a 1 critério e Teste de Tukey (α=5%). Os valores de transmitância foram inferiores a 1%, sendo que as do grupo LT apresentaram, em geral, os maiores valores de transmitância, seguidos dos grupos MO e Z. O GC do cimento Variolink II não sofreu influência da interposição da pastilha de cerâmica. Para o cimento Rely X U200, a interposição de alguns tipos/cores de cerâmica (LT A3,5; MO A2; MO A3,5 e Z A3,5) diminuíram o GC em relação ao grupo controle. Concluiu-se que os valores de transmitância e GC foram influenciados pelos tipos/cores de cerâmica. Entretanto, somente o grupo formado pela cerâmica de dissilicato de lítio LT, usando o Rely X U200, apresentou correlação negativa entre transmitância e GC. / The aim of the present study was to evaluate the transmittance of different ceramic types and shades and their effects on the degree of conversion (DC) of two dual-cure resin cements. Sixty discs were fabricated with IPS e.max ceramic (Ivoclar Vivadent, Schaan, Liechtenstein) and divided into three groups (n= 20 in each group): LT, MO and Z. For LT and MO groups discs were fabricated with low translucency (LT) and medium opacity (MO) lithium disilicate ceramic, respectively. Discs from Z group were manufactured of zirconia. Each group was divided into five subgroups (n = 4), according to the ceramic shade: A2; A3,5; B2; C2; D3. In the LT group, specimens were heat-pressed in shades cited above and in the MO and Z groups, the discs were initially fabricated as core materials and then veneered with veneer ceramic (IPS e.max Ceram, Ivoclar Vivadent, Schaan, Liechtenstein) in the same shades. A spectrophotometer UV-1800 Shimadzu was used to determine the transmittance percentage of each ceramic specimen (2.0-mm-thick). For DC measurements, the resin cements (Variolink II - Ivoclar Vivadent, Schaan, Liechtenstein and Rely X U200 - 3M ESPE, St. Paul, MN, USA) specimens (thickness: 100 μm) were photocured under the ceramic discs (2.0-mm-thick) for 40 s. Specimens photocured without the ceramics discs were used as control group. ATR/FTIR spectrometry was used to evaluated the extent of polymerization for all cement specimens immediately after photocuring. The results were submitted to one-way ANOVA and Tukey test (α=5%). The transmittance percentage was less than 1% and the LT group had the highest transmittance values, followed by MO and Z groups. The %DC of Variolink II cement was not influenced by the ceramic disc interposition. For Rely X U200 cement, the interposition of some ceramics types/shades (LT A3,5, MO A2, MO A3,5 and Z A3,5) significantly decreased the %DC compared to control group. It was concluded that the transmittance values and %DC were influenced by the ceramics types/shades. However, only the LT group, using the Rely X U200, showed a negative correlation between transmittance and %DC.

A radiação ultravioleta pode tanto ser um benefício, como um malefício para o olho humano. Os benefícios são quando é utilizada em procedimentos oftalmológicos para a correção da visão, como nas cirurgias foto-refrativas - UVC - 193 nm; ou para, entre outros tratamentos, impedir a progressão de patologias, como é o caso do crosslinking do colágeno corneano, para ceratocones em estágios inicias que utiliza UVA - 370 nm. Os malefícios são os já amplamente conhecidos pela comunidade científica e populacional, sobre a incidência excessiva de radiação UV nos olhos, causando danos severos ao olho humano. Entretanto, a córnea tem uma proteção natural contra os raios UVA e UVB. Neste trabalho, estudou-se os dois procedimentos oftalmológicos citados a fim de investigar possíveis danos ao olho humano, como a perda da proteção natural da córnea pós cirurgia foto-refrativa, que retira lamelas da córnea; e a quantidade de radiação que adentra o olho humano, durante o crosslinking do colágeno corneano, que utiliza Riboflavina como sintetizador e bloqueador da radiação UVA. Um sistema portátil foi desenvolvido para avaliação da proteção UV e seus danos para o primeiro caso. O protótipo consiste de um sistema de duplo feixe e analisa a transmitância do tecido corneano na faixa de 300-400 nm, e apresenta um fator de correlação r2>0,98. As medidas com remoção de tecido indicaram a importância das camadas da córnea, e a remoção do estroma apresentou uma perda significativa da proteção natural UV, com aumento de 8,2-10,1 pontos percentuais. Já para o crosslinking, que utiliza a combinação riboflavina e UVA, com irradiância de 3 mw/\'CM POT.2\' por 30 minutos foi feito o monitoramento da transmitância UVA durante o tratamento. Foi realizado o protocolo do procedimento atual, ou seja, uma gota de Riboflavina 0,1%, 400mOsm, foi instilada na córnea desepitelizada, a cada 5 minutos (total de 12 gotas). A irradiação UV (365 ± 5 nm, 3 mW/\'CM POT.2\') foi realizada após 30 min de instalação por uma adicional de mais 30 min. A transmitância média da córnea desepitelizada sem Riboflavina foi de 61,6%; após a 1ª instilação de Riboflavina a transmitância foi de 44,9%; após a 6ª gota 22,4%; após a 7ª gota (início da irradiação), 19,5%; após a 8ª gota, 17,3%; após a 9ª, 15,8%; após a 10ª; 14,5%; após a 11ª; 13,5%; e após a 12ª instilação, 12,6%. A transmitância média em termos de energia durante os 30 min de irradiação apresentou uma variação de 0,590 até 0,380 mW/\'CM POT.2\', valores além do limite atualmente aceito para endotélio de córneas de coelhos, que apresenta um nível de segurança citotóxico de 0,36 mW/\'CM POT.2\'. / Ultraviolet radiation can either be a benefit as an harm to the human eye. The benefits are when used in ophthalmic procedures for vision correction, as in the photorefractive surgery - UVC - 193 nm; or to, among other treatments, preventing the progression of diseases, such as the corneal collagen crosslinking, for keratoconus in the early stages - that uses UVA - 370 nm. The harm effects are already widely known by the scientific community and general population, about excessive incidence of UV radiation in the eye, that can cause severe damage to the human eye. However, the cornea has a natural UVA and UVB protection. In this work, we studied the two ophthalmic procedures cited in order to investigate possible damage to the human eye, as the loss of cornea UV natural protection after photorefractive surgery, which removes corneal lamella; and the amount of radiation that penetrates the human eye during the corneal collagen crosslinking, that uses Riboflavin as a synthesizer and UVA radiation blocking. A portable system was developed to evaluate the UV protection and the UV damage for the first case. The prototype consists of a double beam system that analyzes the corneal tissue transmittance in the 300-400 nm range, and presents a correlation factor r2>0.98. Measurements with tissue removal showed the importance of each corneal layer, specially the stroma removal that shows a significant loss of natural UV protection, with an increase of 8.2 to 10.1 percentage points. As for the crosslinking, using riboflavin and UVA irradiance combination, with 3 mw/\'CM POT.2\' for 30 minutes, was performed a monitoring of UVA transmittance during treatment. Current procedure protocol was performed, i.e., one drop of riboflavin 0.1%, 400mOsm, was applied on the naked cornea, every 5 minutes (total of 12 drops). The UV irradiation (365 ± 5 nm, 3 mW/\'CM POT.2\') was performed after 30 min of instillation for an additional 30 min. The average transmittance of the desepithelized cornea without Riboflavin is 61.6%; after the 1st drop of Riboflavin, transmittance is 44.9%; after 6th drop 22.4%; after 7th drop (irradiation starts), 19.5%; after 8th drop; 17.3%; after 9th drop, 15.8%; after 10h drop, 14.5%; after 11th drop, 13.6%; after 12th drop, 12.6%. The average transmittance in terms of energy during the 30 min irradiation procedure fluctuated from 0.590 to 0.380 mW/\'CM POT.2\', beyond the currently accepted rabbit corneal endothelium safety limit for cytotoxic level of 0.360 mW/\'CM POT.2\'.

Cornea is the transparent outermost layer of the eye. It is a thin (500 &micro / m) multilayer tissue which performes around 75% of the total refraction in the eye. It also protects the inner layers against any type of damage. Since it is avascular, the three cellular layers of cornea always need transport of nutrients and other materials in and out of the tissue via diffusion. Any change in shape, transparency or thickness of cornea, or physical damages and infections, may cause serious defects. The conventional methods are satisfactory in the treatment of mild injuries but severe cases require the substitution of the tissue with an equivalent. Keratoprosthesis and donor corneas that are used as replacements do not completely meet requirements. Tissue engineering can be an alternative method for preparing a biocompatible and stable cornea equivalent. The ability to choose from a variety of materials and the ability to incorporate bioactive agents allow the researchers to tailor make the construct. The structure needs to be seeded with the patient&rsquo / s own cells and cultured in vitro to yield an optimal corneal replacement. In this study a novel, split thickness cornea replacement is proposed to substitute the two upper cellular layers (epithelium and stroma) of the native cornea. The design includes a chondroitin sulfate impregnated collagen type I (isolated from rat tail) foam (CSXLF) produced by lyophilization carrying electrospun fibers of the same polymer collected directly on top of the foam, forming the bilayer structure (Fo-Fi). The fiber layer was intended to separate the epithelium and the stroma of the reconstructed cornea yet to allow material transfer in between. The foam layer (bottom) was crosslinked by N-ethyl-N-[3-dimethylaminopropyl] carbodiimide (EDC), and N-hydroxy succinimide and after fiber deposition the bilayer was further stabilized with physical crosslinking (DHT method). The physical characterization of the foam showed that their pore sizes (10-200 &micro / m) and porosities (around 70%) were well within the desired range for typical tissue engineering applications. The cell free wet thicknesses of both single and bilayer constructs were close to that of the native stroma and light transmittance through these scaffolds was quite high (around 82% in the 500-700 nm range). The scaffolds were also tested for their stability and shown to be suitable for in vitro testing. In vitro studies were performed using retinal pigment epithelial cells (RPE, D407 cell line) and isolated human corneal keratocytes (HK) to reconstruct the epithelium and the stroma, respectively. Three types of constructs were prepared / only HK seeded Fo-Fi constructs, RPE-HK seeded CSXLFs, and RPE-HK seeded Fo-Fi constructs. All were shown to support cell attachment and promoted cell proliferation as was shown by the cells that covered the inner and outer spaces of the scaffolds. The fiber layer prevented the mixing of the two cell types, without hindering material exchange between them. Moreover, when co-cultured for 14 days, the keratocytes started to deposit collagen type I, a specific marker of these cells. In contrast, ECM deposition could not be observed in the single type cell seeded samples. The co-cultured bilayer construct was tested for suturability at the end of 31 days of in vitro incubation and it was shown that it could be successfully sutured without any major tears. Under the light of these results it was concluded that both the single layer and the bilayer constructs show promise for use as split thickness cornea replacements.

In this study, the characteristics of LPD-NiO, and lithium-doped LPD-NiO filmson glass substrate were investigated. In our experiment, we do some measurement about physical, chemical, electrical and optical properties for LPD-NiO and lithium-doped LPD-NiO films and discussed with them. The NiO film thickness was characterized by field emission scanning electron microscopy (FE-SEM), structure was characterized by X-ray diffraction (XRD), chemical properties were characterized by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). Electrical properties were characterized by four-point probe, and optical properties were characterized by a reflecting spectrograph. The thermal annealing was used to improve the characteristics of LPD-NiO and lithium-doped LPD-NiO films in nitrogen, air and nitrous oxide ambient. For lithium doping, the lithium chloride was used as the doping solution and the electrical characteristics were enhanced. After thermal annealing in air at 400 oC, the resistivity of NiO films is 7.5 ¡Ñ 10-1 ohm-cm and can be lowed to 7.2 ¡Ñ 10-3 ohm-cm with lithium doping.

Optical Wireless Communication systems use lasers offering larger bandwidth, which facilitates higher data rates, comparing with radio communication systems. However, its performance is limited by atmospheric conditions, and is a function of wavelength. The objective of this study is the determination of the wavelength interval(s) at which the atmospheric transmittance is relatively high and has relatively low dependence on variations in temperature, relative humidity, wind speed and atmospheric pressure under the conditions such as path altitude of 10 meters, path geometry of horizontal to the Earth&rsquo / s surface and clean (includes no fog, rain or snow etc.) over sea surface atmosphere. The path length is taken to be 15 km. Alanya was assignated as geographical region and the required information about the atmospheric constituents and meteorological parameters was collected. Then, the variations in atmospheric transmittance due to the periodically measured meteorological parameters were calculated (for summer and winter seasons). Finally, individually calculated effects of these parameters on atmospheric transmittance are assembled in order to determine the desired wavelength interval(s). As a result, the most suitable wavelength interval was determined to be about between 3.99 &micro / m and 4.02 &micro / m. In addition, dependencies of atmospheric pressure, temperature, relative humidity, and wind speed on atmospheric transmittance have been established for both winter and summer seasons. Atmospheric transmittance is found to be inversely proportional to temperature, relative humidity and wind speed. The effect of pressure is relatively small comparing with other parameters.

Different kinds of nanoparticles are widely used in optoelectronic and photovoltaic applications to harvest light to increase efficiency of devices. ETS-10, which is a synthetic microporous material consisting of &ndash / Ti-O-Ti-O-Ti- wires that run in the crystal in a and b directions, has been of interest in such applications due to its unique properties. In the current study, the synthesis conditions of ETS-10 were investigated in order to obtain pure ETS-10 crystals with the desired morphology. For this purpose, ETS-10 crystals were synthesized using different molar compositions. The effects of several synthesis parameters on the obtained products were investigated. Furthermore, ETS-10 thin films were prepared on ITO glass substrates using secondary growth of ETS-10 for the first time. The orientation of the -Ti-O-Ti-O-Ti- wires inside ETS-10 were explored by preparing several ETS-10 films on the ITO glass substrates using secondary growth of ETS-10 multilayers with a partial a(b)-out-of-plane preferred crystal orientation. This orientation can be desirable for the advanced applications of ETS-10 films. Afterwards, silver nanoparticle modified ETS-10 crystals were prepared and characterized in detail to understand the interaction of silver nanoparticles with the synthesized ETS-10 crystals. For this purpose, ETS-10 in the as-prepared and silver nanoparticle containing forms have been characterized using, XRD, ICP-OES, SEM, HR-TEM, N2 Adsorption, XPS, and UV/VIS spectroscopy. In order to investigate the optical properties of the silver modified ETS-10, transmittance-reflectance measurements were carried out. In general, it is believed that all steps necessary for the preparation of ETS-10 films and preliminary steps for investigating ETS-10 for future photovoltaic applications were determined.