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Buildings fulfilling all requirements related to energy, economy and environment are necessary to be designed by interdisciplinary teams with efficient transfer of information and good knowledge base. IDES EDU is a project co-funded by the Intelligent Energy Europe program in which 15 European universities make a concerted effort to develop and implement balanced master and postgraduate courses on Sustainable Energy Design providing skills and knowledge that exceed the requirements of the EPBD. The resulting courses focus on different aspects of sustainable building design from the perspective of architecture, building construction and building technologies.

Buildings fulfilling all requirements related to energy, economy and environment are necessary to be designed by interdisciplinary teams with efficient transfer of information and good knowledge base. IDES EDU is a project co-funded by the Intelligent Energy Europe program in which 15 European universities make a concerted effort to develop and implement balanced master and postgraduate courses on Sustainable Energy Design providing skills and knowledge that exceed the requirements of the EPBD. The resulting courses focus on different aspects of sustainable building design from the perspective of architecture, building construction and building technologies.

We present here a two-dimensional numerical simulation of a hydrogenated amorphous silicon p - i - n solar cell non-uniformly illuminated through the p-layer. This simulation is used to show the effect of the presence of dark regions in the illuminated surface on the electrical behaviour of the device. The continuity equations for holes and electrons together with Poisson's equation, implemented with a recombination mechanism reflecting the amorphous structure of the material, are solved using standard numerical techniques over a rectangular domain. The results obtained reveal the appearance of a lateral component of the electric field and current density vectors inside the structure. The effect of such components is a lateral carrier flow of electrons inside the intrinsic layer and of holes inside the p-layer, resulting in leakage of the transverse current collected at the contacts and an increase in the series resistance.

The behavior of tandem pin heterojunctions based on a-SiC:H alloys is investigated under different optical and electrical bias conditions. The devices are optimized to act as optically selective wavelength filters. Depending on the device configuration (optical gaps, thickness, sequence of cells in the stack structure) and on the applied voltage (positive or negative) and optical bias (wavelength, intensity, frequency) it is possible to combine the wavelength discrimination function with the self amplification of the signal. This wavelength nonlinearity allows the amplification or the rejection of a weak signal-impulse. The device works as an active tunable optical filter for wavelength selection and can be used as an add/drop multiplexer (ADM) which enables data to enter and leave an optical network bit stream without having to demultiplex the stream. Results show that, even under weak transient input signals, the background wavelength controls the output signal. This nonlinearity, due to the transient asymmetrical light penetration of the input channels across the device together with the modification on the electrical field profile due to the optical bias, allows tuning an input channel without demultiplexing the stream. This high optical nonlinearity makes the optimized devices attractive for the amplification of all optical signals. Transfer characteristics effects due to changes in steady state light, control d.c. voltage and applied light pulses are presented. Based on the experimental results and device configuration an optoelectronic model is developed. The transfer characteristics effects due to changes in steady state light, dc control voltage or applied light pulses are simulated and compared with the experimental data. A good agreement was achieved (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

This work was supported by the Portuguese National Strategic Reference Framework, QREN, under project 1600/A2P2/2008. A Blumlein line is a particular Pulse Forming Line, PFL, configuration that allows the generation of high-voltage sub-microsecond square pulses, with the same voltage amplitude as the dc charging voltage, into a matching load. By stacking n Blumlein lines one can multiply in theory by n the input dc voltage charging amplitude. In order to understand the operating behavior of this electromagnetic system and to further optimize its operation it is fundamental to theoretically model it, that is to calculate the voltage amplitudes at each circuit point and the time instant that happens. In order to do this, one needs to define the reflection and transmission coefficients where impedance discontinuity occurs. The experimental results of a fast solid-state switch, which discharges a three stage Blumlein stack, will be compared with theoretical ones. publishersversion published

Renal replacement therapies (RRT) for patients with end-stage renal failure represent a high burden on European countries' healthcare budget. Our purpose was to report and compare the costs of RRT by hemodialysis (HD) or peritoneal dialysis (PD) and renal transplantation (RT) after introduction of a bundled payment system of dialysis. We analyzed average annual cost of RT in a public national health system hospital - surgical/anesthesiologist team and material, induction and maintenance immunosuppression therapy, hospital stay, diagnostic examinations (DE), and post-transplant office visits (including DE). Incentives paid to hospitals performing RT were included. Annual cost of HD or PD was estimated by bundled payment established in a recently revised law - 537.25 €/wk. Total first year cost or RT is 61 658.14 € and from the second year forth 543.86 €/month. Dialysis costs 28 033.71 €/yr. Break-even point for cost is at 32 months, and from there on, RT is less expensive. Strategies aimed at increasing RT are needed as it confers better survival than RRT by dialysis with lower costs to Portuguese health system.

MONTENEGRO, M.A. Efeito do extrato do bagaço do pendúculo de caju (Anacardium occidentale L.) contra Streptococcus mutans. 2012. 71 f. Dissertação. (MESTRADO EM BIOTECNOLOGIA) - Campus de Sobral, Universidade Federal do Ceará, Sobral, 2012. The Anacardium occidentale L, popularly known as cashew tree, occupies an important place among the fruit trees due to the increasing commercialization of its main products. In northeastern Brazil, its cultivation is one of the main agricultural activities in the region. Concentrating in the states of Ceará, Piauí and Rio Grande do Norte, it is used in folk medicine for various therapeutic purposes, including as an antimicrobial. The cashew apple bagasse is obtained after extracting the juice, being a major source of waste of agribusiness. The aim of this study was to evaluate the antimicrobial and antibiofilm potential of the hydroalcoholic extract of the cashew apple pomace (ECAP) against the Streptococcus mutans. It was determined the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and the preventive assay for biofilm formation through biomass quantification. The Streptococcus mutans strain UA159 was used for this intention. The antimicrobial assay results showed that the ECAP was considered bactericidal (250μg.mL) and was considered bactericidal at the concentration of 1000μg.mL. Inhibition in the biomass was observed at the minimum concentration of 250μg.mL. Thus, it was concluded that the EPAC shows antimicrobial and antibiofilm activity against Streptococcus mutans. These results demonstrate the potential of the ECAP as a possible biotechnological product in the field of dentistry. O Anacardium occidentale L., conhecido popularmente como cajueiro, ocupa um lugar importante entre as plantas frutíferas devido à crescente comercialização dos seus principais produtos. No nordeste brasileiro, seu cultivo é uma das principais atividades agropecuárias da região. Concentrando-se nos estados do Ceará, Piauí e Rio Grande do Norte, é utilizado na medicina tradicional para diversos fins terapêuticos, inclusive, como antimicrobiano. O bagaço do caju é obtido após a extração do suco, sendo uma importante fonte de resíduos da agroindústria. O objetivo do presente trabalho foi avaliar o potencial antimicrobiano e antibiofilme do extrato hidroalcoólico do bagaço do pedúnculo do caju (EBPC) frente a bactéria Streptococcus mutans. No presente estudo, determinou-se a Concentração Inibitória Mínima (CIM), Concentração Bactericida Mínima (CBM) e avaliou-se a inibição da formação de biofilme através da quantificação da biomassa. Para isso, utilizou-se a cepa de S. mutans. Os resultados dos ensaios antimicrobianos mostraram que o EBPC teve ação bacteriostática (CIM = 250 μg.mL-1) e bactericida (CBM = 1000 μg.mL-1). Observou-se inibição da biomassa na concentração mínima de 250 μg.mL-1. Deste modo, concluiu-se que o EBPC apresentou atividade antimicrobiana e antibiofilme frente ao S. mutans. Estes resultados demonstraram o potencial do EBPC como um possível produto biotecnológico na área da odontologia.

Submitted by Isabel Gomes (itg@lisboa.ucp.pt) on 2013-06-17T15:26:47Z No. of bitstreams: 1 Elvira Manuela Almeida Santos.pdf: 2731862 bytes, checksum: 0d98f251b36e6e512e5cb98931b931a2 (MD5) Approved for entry into archive by Isabel Gomes (itg@lisboa.ucp.pt) on 2013-06-17T15:27:12Z (GMT) No. of bitstreams: 1 Elvira Manuela Almeida Santos.pdf: 2731862 bytes, checksum: 0d98f251b36e6e512e5cb98931b931a2 (MD5) Made available in DSpace on 2013-06-17T15:27:12Z (GMT). No. of bitstreams: 1 Elvira Manuela Almeida Santos.pdf: 2731862 bytes, checksum: 0d98f251b36e6e512e5cb98931b931a2 (MD5) Previous issue date: 2012-10-10

This letter reports a near-ultraviolet/visible/near-infrared n+-n-i-δi-p photodiode with an absorber comprising a nanocrystalline silicon n layer and a hydrogenated amorphous silicon i layer. Device modeling reveals that the dominant source of reverse dark current is deep defect states in the n layer, and its magnitude is controlled by the i layer thickness. The photodiode with the 900/400 nm thick n-i layers exhibits a reverse dark current density of 3nA/cm2 at −1 V. Donor concentration and diffusion length of holes in the n layer are estimated from the capacitance-voltage characteristics and from the bias dependence of long-wavelength response, respectively.

This article reports on the structural, electronic, and optical properties of boron-doped hydrogenated nanocrystalline silicon (nc-Si:H) thin films. The films were deposited by plasma-enhanced chemical vapour deposition (PECVD) at a substrate temperature of 150 °C. Crystalline volume fraction and dark conductivity of the films were determined as a function of trimethylboron-to-silane flow ratio. Optical constants of doped and undoped nc-Si:H were obtained from transmission and reflection spectra. By employing p + nc-Si:H as a window layer combined with a p ′ a-SiC buffer layer, a-Si:H-based p – p ′– i – n solar cells on ZnO:Al-coated glass substrates were fabricated. Device characteristics were obtained from current–voltage and spectral-response measurements.

This paper reports results on the use of a pi’n/pin a-SiC:H heterostructure as an active band-pass filter transfer function whose operation depends on the wavelength of the trigger light, on the applied voltage and on the wavelength of the additional optical bias.Results show that the device combines the demultiplexing operation with the simultaneous photodetection and self amplification of the signal. Experimental and simulated results show that the output signal has a strong nonlinear dependence on the light absorption profile. The device, modeled by a simple circuit with variable capacitors and interconnected phototransistors through a resistor, is a current-controlled device. It uses a changing capacitance to control the power delivered to the load acting as a state variable filter circuit. It combines the properties of active high-pass and low-pass filter sections into a capacitive active band-pass filter.

Submitted by Cristina Afonso (cac@lisboa.ucp.pt) on 2012-10-16T15:34:29Z No. of bitstreams: 1 Tese Cd 25_10-2011.pdf: 2584151 bytes, checksum: d3eae6c98293b60eeef755822fd7206d (MD5) Approved for entry into archive by Cristina Afonso (cac@lisboa.ucp.pt) on 2012-10-16T15:34:38Z (GMT) No. of bitstreams: 1 Tese Cd 25_10-2011.pdf: 2584151 bytes, checksum: d3eae6c98293b60eeef755822fd7206d (MD5) Made available in DSpace on 2012-10-16T15:34:38Z (GMT). No. of bitstreams: 1 Tese Cd 25_10-2011.pdf: 2584151 bytes, checksum: d3eae6c98293b60eeef755822fd7206d (MD5) Previous issue date: 2011

The optimal immunosuppressive therapy in kidney transplantation remains controversial. Since 1990, we included, in our department, anti-T-Lymphocyte globulin Fresenius® (ATG-F) in a sequential immunosuppressive therapy in pediatric recipients of deceased donor kidneys. We analysed retrospectively the complications and long-term outcomes.Ninety eight kidney transplants were performed in 91 children and adolescents between November 1990 and October 2009, using deceased donor source grafts. In 86.8% of the recipients ATG-F was used as antibody induction and in 12.2% of the recipients no ATG-F induction was used.Overall graft survival rates at 1, 5, 10 and 15 years were 91.8%, 86.1%, 75.9% and 61.9% respectively. In the ATG-F group the graft survival at 1, 5, 10 and 15 years was 93%, 89.1%, 79%, 62.4% and in group without ATG-F it was 83.3%, 66.7%, 55.6% at 1, 5, 10 years respectively (p=0.27). The overall incidence of infection was 1.6/patient in the first year post-transplantation and almost all were of mild or moderate intensity. A papillary thyroid carcinoma was diagnosed in one patient and no lymphoid malignancies were observed during the observational period. All patients were alive at the end of follow-up, except one who died of cardiovascular disease, 7 months after graft loss.These results indicate that ATG-F induction in pediatric kidney transplantation using deceased donor kidneys is associated with good graft and patient survival rates, and with low levels of complications.

Tese de doutoramento em Engenharia Química, apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra The main purpose of this work is the preparation and development of several controlled drug delivery systems built with natural polymers and suitable for different applications, like for colon-specific drug delivery or for the localized and prolonged delivery of drugs. With this objective, three potential controlled drug delivery systems, based on natural polymers, were prepared and characterized. In the first investigated system, the natural occurring polyester poly(3-hydroxybutyrate-co-3-hydroxyvalerate), PHBV, was processed in microparticles loaded with the hydrophobic drug flurbiprofen, by means of an oil-in-water emulsion/extraction solvent evaporation method, using chloroform as the organic phase and polyvinyl alcohol (PVA) as the emulsion stabilizer. A central composite experimental design was employed to evaluate the effect of two process variables – the polymer concentration in the organic phase and the surfactant concentration in the aqueous phase - on some of the final microparticles properties, specifically the encapsulation efficiency of the drug, the mean particle size, the width of the particles size distribution, and the required time for the in vitro release of 50% of the encapsulated drug (t50%). The statistical analysis of the implemented experimental design revealed that the two investigated variables had a significant and opposite effect on the encapsulation efficiency of the drug. Also, it was found that the microparticles mean particle size increased with increasing concentrations of PHBV in organic phase and that the concentration of the surfactant in the aqueous phase played a critical role in the aggregation degree of the microparticles. It was concluded that a minimum PVA concentration was required to stabilize the oil-in-water emulsion and, in this way, obtain non-aggregated particles. The in vitro flurbiprofen release profiles from PHBV microparticles were very similar for all the prepared formulations, showing that more than 90% of the drug was released in the first eight hours of the essay. The time for the in vitro release of 50% of the encapsulated drug, t50%, was not significantly influenced by any of the two investigated variables. The comparison between the release profiles of flurbiprofen from the PHBV microparticles and the dissolution profile of the pure drug lead to the conclusion that the drug was essentially dispersed at the surface of the microparticles, rather than effectively entrapped in the polymeric matrix. Although the investigated formulations didn’t led to an effective immobilization of the flurbiprofen in the PHBV microparticles, this objective can be achieve with further investigation, namely by the manipulation of the drug/polymer mass ratio used in the microparticles preparation, among other variables. With the flurbiprofen effectively immobilized in the microparticles, it will be possible to then optimize the drug release profile in order to obtain a controlled and prolonged release of the immobilized flurbiprofen, suitable for the use of the microparticles as localized and prolonged drug delivery systems. In the second investigated system, the polysaccharide pectin was chemically modified by introducing, in its structure, vinylic or methacrylic terminal functional groups. The functionalized pectin derivatives, alone or together with the macromer poly(ethylene glycol) diacrylate (PEGDA), were transformed in chemical hydrogels by UV-induced free radical reticulation. In vitro drug release studies were used to evaluate the behavior of the produced hydrogels as controlled drug delivery systems. For this purpose, two low molecular weight hydrophilic drugs (gentamicin sulphate and sodium flurbiprofen), and two model proteins (bovine serum albumin (BSA) and lysosyme), were incorporate in the hydrogels during their formation and subsequently released in vitro. It was concluded that the extension of the chemical modification of pectin, which was carried out in a heterogeneous environment, was limited/controlled by the accessibility of the OH groups of the polysaccharide, which, in turn, was directly controlled by the swelling degree of the polysaccharide particles in the reaction solvent. The two low molecular weight hydrophilic drugs were rapidly liberated from the hydrogels. The release profiles revealed that, in approximately four hours, the entire incorporated drug was released. On the other hand, the in vitro release studies of the model proteins revealed an incomplete release of the incorporated proteins, probably because a fraction of protein was physical adsorbed in to polymeric matrix and/or covalently bounded to it. The presence of pectinolytic enzymes in the release medium result in a higher fraction of BSA released from the hydrogels, supposedly due to the enzymatic degradation of the tridimensional network structure of the polymer matrix. The results obtained with this work show that the produced hydrogels are suitable to be use as colon-specific drug delivery systems, especially of proteins. In the third and last investigated system, sponges of pectin and chitosan, prepared by the freeze-drying of the insoluble polyelectrolyte complexes (PECs) formed between the two polysaccharides, were produced and characterized. Three pectin/chitosan PECs sponges were prepared, using different initial proportions of the two polysaccharides. The three sponges, independently of the used proportions, had very similar compositions, being composed mainly from pectin (74 to 78%, mass percentage). The sponges were submersed in aqueous solutions, either at pH 2 or pH 7.4, and the weight loss was record during six weeks. The results revealed a continuous weight loss, attributed to the gradual liberation of polymers chains, as a consequence of the progressive loss of the ionic interactions established, during PECs formation, between the COO- groups of pectin and the NH3+ groups of chitosan. The composition analysis of the sponges during dissolution time, and their FTIR spectra, revealed that, at pH 2, the weight loss of the sponges was caused, equally, by the loss of pectin and chitosan. On the other hand, it was concluded that, at pH 7.4, the weight loss of the sponges was mainly due to the loss of pectin. A preliminary evaluation of the sponges as controlled drug delivery systems was made, by the incorporation of BSA in the sponges followed by the in vitro release, at pH 2 and pH 7.4. The in vitro release profiles obtained suggest that the released of the protein from the sponges is controlled by the strong interactions established between the protein molecules and the polymeric matrix. This preliminary study indicates that the produced PECs matrixes can be use to immobilized proteins and built colon-specific delivery systems of this type of biomacromolecules. In the three works presented in this Thesis it was possible to obtained significant conclusions that can be used in the future as basis for the continuation of the development of the different controlled drug delivery systems proposed in this work. Este trabalho tem como principal objectivo a preparação de sistemas de libertação controlada com base em polímeros de origem natural e com o potencial de serem utilizados em diversas aplicações como a entrega específica de fármacos no cólon ou a libertação prolongada e localizada de fármacos. Para isto desenvolveram-se e caracterizaram-se três potenciais sistemas de libertação controlada de moléculas bioactivas, preparados com diferentes polímeros de origem natural. O primeiro sistema estudado envolveu a utilização do poliéster de origem natural poli(3-hidroxibutirato-co-3-hidroxivalerato), PHBV, o qual foi investigado enquanto matriz para a imobilização do antiflamatório não esteróide flurbiprofeno em micropartículas preparadas pelo método da extracção/evaporação do solvente numa emulsão óleo/água, utilizando o clorofórmio como fase orgânica e o álcool polivinílico (PVA) como surfactante. Um desenho composto central de experiências foi implementado de forma a investigar o efeito de duas variáveis envolvidas no processo de preparação das micropartículas – a concentração do polímero na fase orgânica e a concentração do surfactante na fase aquosa - sobre algumas das propriedades finais dessas mesmas micropartículas, nomeadamente a eficiência de encapsulação do fármaco, o tamanho médio e a distribuição de tamanhos das micropartículas, e o tempo correspondente à libertação in vitro de 50% do fármaco encapsulado. Concluiu-se que as duas variáveis investigadas afectavam, significativamente e de forma oposta, a eficiência de encapsulação do fármaco. Igualmente, verificou-se que o tamanho médio das partículas era afectado positivamente pelo aumento da concentração do polímero na fase orgânica. A concentração do surfactante revelou ser um factor crítico no grau de agregação das micropartículas obtidas, tendo-se concluído que existe um limite mínimo requerido de concentração de surfactante para estabilizar a emulsão óleo/água e, consequentemente, obter micropartículas não agregadas. Os perfis de libertação in vitro do fármaco, a partir de micropartículas produzidas em diferentes condições experimentais, revelaram que mais de 90% do fármaco era libertado nas primeiras oito horas de ensaio. A análise estatística dos valores de t50% (tempo correspondente à libertação in vitro de 50% do fármaco encapsulado) revelou que nenhuma das duas variáveis experimentais investigadas influenciava significativamente este parâmetro. A comparação dos perfis de libertação in vitro do fármaco a partir de micropartículas e o perfil de dissolução do fármaco puro conduziu à conclusão de que o fármaco se encontra essencialmente disperso à superfície das micropartículas e não, como seria desejável num sistema de libertação controlada, efectivamente aprisionado na matriz polimérica. Embora, com as formulações investigadas, não se tenha obtido um sistema de libertação do furbiprofeno com a capacidade de libertar este de forma controlada ao longo de um período de tempo significativo (de semanas ou meses), a investigação e optimização de outras variáveis experimentais, nomeadamente a razão mássica fármaco/polímero utilizada na produção das micropartículas, poderá conduzir a um sistema de libertação capaz de libertar o flurbiprofeno da forma referida anteriormente, e que poderá ser utilizado na libertação controlada e localizada deste. No segundo sistema investigado o polissacarídeo pectina foi quimicamente modificado através da introdução na sua estrutura de grupos terminais vinílicos ou metacrílicos. Os derivados de pectina assim obtidos, por si só ou em conjunto com o macrómero poli(etileno glicol) diacrilato (PEGDA), foram utilizados na formação de hidrogéis químicos preparados por fotoreticulação. A actuação destes hidrogéis enquanto sistemas de libertação controlada foi investigada através de estudos de libertação in vitro de dois fármacos hidrofílicos de baixo peso molecular (sulfato de gentamicina e flurbiprofeno sódico) e de duas proteínas modelo (albumina de soro bovino (BSA) e lisozima). Todos os compostos bioactivo acima referidos foram imobilizados no hidrogel durante a sua formação. Relativamente à modificação química da pectina, a qual se processou em meio heterogéneo, conclui-se que a extensão da modificação química era limitada/controlada pela acessibilidade dos grupos hidroxilo do polissacarídeo, encontrando-se essa acessibilidade directamente relacionada com a capacidade de inchaço das partículas do polissacarídeo no solvente reaccional. No caso dos fármacos hidrofílicos de baixo peso molecular imobilizados nos hidrogéis preparados, verificou-se que estes se libertavam rapidamente, sendo a libertação total atingida, no máximo, passado quatro horas de ensaio. A libertação das proteínas modelo, a partir dos hidrogéis, revelou-se incompleta devido, provavelmente, à ligação covalente e/ou adsorção física de uma fracção da proteína à matriz polimérica. Constatou-se ainda que a presença de enzimas pectinolíticas no meio de libertação conduzia a uma maior quantidade de BSA libertada, supostamente devido à degradação por via enzimática da estrutura tridimensional do hidrogel. Os resultados obtidos neste trabalho indicam que os hidrogéis produzidos poderão ser utilizados enquanto sistemas de libertação específica no cólon, em particular na libertação de protéinas. Por fim, o terceiro sistema estudado envolveu a preparação e caracterização de esponjas de pectina e quitosano, as quais foram obtidas a partir da liofilização dos complexos polielectrolíticos (PECs) formados, em meio aquoso, entre os dois polissacarídeos. Foram produzidas três esponjas de PECs de pectina/quitosano utilizando diferentes proporções iniciais dos dois polissacarídeos. Independentemente das proporções utilizadas, os resultados da análise elemental revelaram que a composição das três esponjas era muito semelhante, sendo estas constituídas maioritariamente por pectina (entre 74 e 78%, percentagem mássica). Estudos da variação do peso das esponjas, realizados ao longo de seis semanas, revelaram que as esponjas perdiam massa de forma contínua, quando mergulhadas em soluções aquosas a pH 2 ou pH 7.4. Esta perda de massa foi atribuída à libertação gradual das cadeias dos dois polissacarídeos, causada pela quebra progressiva das ligações iónicas estabelecidas durante a formação dos PECs entre os grupos COO- da pectina e os grupos NH3+ do quitosano. A análise da composição das esponjas ao longo do tempo de dissolução, e o registo dos espectros de FTIR, revelou que, nas esponjas mergulhadas a pH 2, a perda de massa resultava tanto da perda de pectina como de quitosano, enquanto, a pH 7.4, a perda de massa podia ser maioritariamente atribuída à dissolução das cadeias de pectina. Este comportamento distinto pode ser atribuído aos diferentes estados de ionização/protonação dos dois polissacarídeos nos dois meios aquosos. Uma avaliação preliminar destas esponjas, enquanto sistemas de libertação controlada de proteínas, foi feita, através de um estudo de libertação in vitro de libertação da proteína BSA. Os resultados sugerem que a libertação de proteínas a partir deste tipo de material será controlada pelas fortes interacções físicas estabelecidas entre as proteínas e a matriz polimérica. Este resultado sugere que as matrizes de PECs desenvolvidas apresentam o potencial para serem utilizadas na preparação de sistemas de libertação específica de protéinas no cólon. Em cada um dos três trabalhos desenvolvidos e apresentados nesta Tese foi possível obter conclusões significativas, que poderão ser utilizadas como bases sólidas para a continuação do trabalho de desenvolvimento dos diferentes sistemas de libertação propostos. Instituto de Investigação Interdisciplinar da Universidade de Coimbra, Bolsa de Doutoramento III/BIO/35/2005.

Submitted by Fátima Piedade (piedade.fatima@gmail.com) on 2011-11-24T18:11:46Z No. of bitstreams: 1 Wavelength Selective a-SiC - H p-i-n-p-i-n Heterostructure for Fluorescent Proteins Detection_rep.pdf: 52887 bytes, checksum: 2b26c64aa83ba603c1220692a0bfed57 (MD5) Made available in DSpace on 2011-11-24T18:11:46Z (GMT). No. of bitstreams: 1 Wavelength Selective a-SiC - H p-i-n-p-i-n Heterostructure for Fluorescent Proteins Detection_rep.pdf: 52887 bytes, checksum: 2b26c64aa83ba603c1220692a0bfed57 (MD5) Previous issue date: 2010-06

Submitted by Fátima Piedade (piedade.fatima@gmail.com) on 2011-11-24T18:17:02Z No. of bitstreams: 1 Field Effect and Light-Assisted a-Si - H Sensors for Detection of Ions in Solution_rep.pdf: 52993 bytes, checksum: accd7a6d586e5c27f860ae174e223a38 (MD5) Made available in DSpace on 2011-11-24T18:17:02Z (GMT). No. of bitstreams: 1 Field Effect and Light-Assisted a-Si - H Sensors for Detection of Ions in Solution_rep.pdf: 52993 bytes, checksum: accd7a6d586e5c27f860ae174e223a38 (MD5) Previous issue date: 2010-06

We report a field-effect phototransistor with a channel comprising a thin nanocrystalline silicon transport layer and a thicker hydrogenated amorphous silicon absorption layer. The semiconductor and dielectric layers were deposited by radio-frequency plasma enhanced chemical vapor deposition. The phototransistor with channel length of 24 microns and photosensitive area of 1.4 mm2 shows an off-current of about 1 pA, and high photoconductive gain in the subthreshold region. Measurements of the quantum efficiency at different incident light intensities and biasing conditions, along with spectral-response characteristics, and threshold voltage stability characterization demonstrate the feasibility of the phototransistor for low light level detection.

Tese de mestrado integrado. Engenharia Civil (Especialização em Construções). Faculdade de Engenharia. Universidade do Porto. 2010

Dissertação de Mestrado em Medicina Veterinária O coelho-bravo desempenha um papel preponderante nos ecossistemas mediterrânicos, por constituir a presa principal de um amplo espectro de predadores, alguns dos quais em vias de extinção (Lynx pardinus, Aquila adalberti). Apresenta, ainda, um valor económico e social extremamente importante, sendo do ponto de vista cinegético, a espécie de caça menor mais procurada pelos caçadores. O destino das peças caçadas é, muitas vezes, o auto-consumo, contudo é possível a comercialização de caça ou carne de caça para consumo, desde que sujeitas às regras determinadas pelo Regulamento (CE) 853/2004 e pelo Regulamento (CE) 854/2004. Contudo, os referidos Regulamentos não se aplicam, quando o caçador fornece pequenas quantidades de caça ou carne de caça selvagem directamente ao consumidor final, ou ao comércio a retalho local que fornece directamente o consumidor final. No caso do coelho-bravo, é possível a venda de 10 animais por dia, sem que estes sejam sujeitos a qualquer inspecção sanitária, nem a qualquer exame inicial das peças de caça. Neste trabalho foi efectuada uma avaliação higio-sanitária de peças de coelho-bravo caçados em duas zonas de caça municipais do concelho de Vila Nova de Paiva, tendo em vista a identificação de situações/alterações que pudessem estar associadas a uma depreciação da qualidade da carne e do perfil sanitário das peças caçadas. Os resultados demonstraram uma ocorrência de conspurcação interna, originada pelo rebentamento das vísceras gastrointestinais, em 43,9% dos animais amostrados; o tempo médio de 5h24m entre a caçada e a evisceração da peça e uma temperatura muscular profunda, determinada após a evisceração, sempre superior a 16ºC. Estes dados evidenciam a possível depreciação higiénica do produto final, com eventuais consequências nefastas para a saúde, dada a possibilidade de existirem microrganismos com potencial zoonótico. A análise anatomopatológica permitiu detectar uma situação compatível com pasteurelose e a análise parasitológica revelou que 92,68% dos animais amostrados se encontravam parasitados, salientando-se a presença de cisticercos, forma larvar da Taenia pisiformis, em 34,15% dos animais. Este estudo permite salientar a importância da realização de uma avaliação higio-sanitária das peças da caça destinadas a consumo humano, devendo esta ser efectuada por alguém que conheça todas as situações que podem constituir um risco para o consumidor e desta forma tomar correctas decisões quanto ao destino da caça. Torna-se ainda importante adoptar medidas de conservação, preparação e confecção da carne adequadas e sensibilizar os caçadores para a importância de todas estas situações, tendo em vista uma maior segurança do consumidor.

In this paper we present results on the use of a multilayered a-SiC:H heterostructure as a wavelength-division demultiplexing device (WDM) for the visible light spectrum. The WDM device is a glass/ITO/a-SiC:H (p-i-n)/ a-SiC:H(-p) /Si:H(-i)/SiC:H (-n)/ITO heterostructure in which the generated photocurrent at different values of the applied bias can be assigned to the different optical signals.The device was characterized through spectral response measurements, under different electrical bias. Demonstration of the device functionality for WDM applications was done with three different input channels covering wavelengths within the visible range. The recovery of the input channels is explained using the photocurrent spectral dependence on the applied voltage. The influence of the optical power density was also analysed.An electrical model, supported by a numerical simulation explains the device operation. Short range optical communications constitute the major application field, however other applications are also foreseen.

Results on the use of a double a-SiC:H p-i-n heterostructure for signal multiplexing and demultiplexing applications in the visible range are presented. Pulsed monochromatic beams together (multiplexing mode), or a single polychromatic beam (demultiplexing mode) impinge on the device and are absorbed, accordingly to their wavelength. Red, green and blue pulsed input channels are transmitted together, each one with a specific transmission rate. The combined optical signal is analyzed by reading out, under different applied voltages, the generated photocurrent. Results show that in the multiplexing mode the output signal is balanced by the wavelength and transmission rate of each input channel, keeping the memory of the incoming optical carriers. In the demultiplexing mode the photocurrent is controlled by the applied voltage allowing regaining the transmitted information. A physical model supported by a numerical simulation gives insight into the device operation.

Monografia apresentada à Universidade Fernando Pessoa para obtenção do grau Licenciada em Enfermagem O presente trabalho académico tem como tema “Conhecimentos dos pais das crianças dos 3 aos 5 anos face à importância da lavagem dos dentes, num Jardim de Infância na Maia”. Este trabalho surge com o intuito de dar importância e avaliar os conhecimentos dos pais sobre esta temática, visto os dados relativos à saúde oral dos portugueses serem muito escassos, e pelo facto de esta ser de extrema importância na idade infantil. Segundo Araújo (professorasdesesperadas.blogspot.com) é urgente investir na saúde oral em Portugal. “Não podemos somente em tratar dentes. É preciso investir na criação de uma cultura forte de saúde oral, um trabalho que começa nas escolas/infantários”. No surgimento de uma problemática, é necessário formular questões capazes de orientar a investigação, no sentido da obtenção de resultados capazes de a responder. Para tal, este estudo é norteado pelas seguintes questões: “Quais os conhecimentos dos pais das crianças dos 3 aos 5 anos face à importância da lavagem dos dentes, num Jardim de Infância na Maia?” e “Qual a prática da lavagem dos dentes das crianças dos 3 aos 5 anos, no Jardim de Infância na Maia?”. Pela natureza do estudo que se pretende efectuar, a estratégia versa a metodologia de investigação descritiva e transversal, inserida no paradigma quantitativo. Para dar resposta às questões que guiam a investigação a população escolhida foi de 38 pais de crianças com idades compreendidas entre os 3 e os 5 anos, aos quais foi aplicado o instrumento de colheita de dados, o questionário. De um modo geral, pelos resultados deste estudo, podemos concluir que os pais das crianças em estudo, na sua maioria, e em termos de senso comum, conhecem a importância da lavagem dos dentes, e qual a prática desta a seguir.

Mestrado em Gestão de Operações O presente trabalho tem como objectivo principal testar uma metodologia de selecção de fornecedores no contexto de uma compra não repetitiva, numa unidade industrial. A selecção de fornecedores é considerada actualmente estratégica para as empresas que estão inseridas em ambientes cada vez mais dinâmicos e exigentes. Ao longo desta dissertação são analisados e comparados vários modelos de selecção de fornecedores, e verificada a sua aplicabilidade ao caso de estudo apresentado. Este estudo contribui para um melhor conhecimento dos métodos de selecção de fornecedores, bem como da importância da selecção dos mesmos nas organizações industriais. ABSTRACT: The present work has as main objective to test an application of a model of a supplier selection for a not repetitive purchase, in an industrial unit. The supplier selection is considered currently a strategic issue for the companies who are inserted in more dynamic and demanding environments each time. Throughout this thesis there are analyzed and compared some models of supplier selection, and verified its applicability to the presented case study. This study it contributes for one better knowledge of the methods of supplier selection as well as, of its importance in industrial organizations.

Tese de Doutoramento em Ciências da Literatura - Ramo do Conhecimento de Literatura Francesa, Le vaste domaine de la littérature des écrivains de la «deuxieme génération» de I'Holocauste est intimement marqué par la recherche des moyens d'expression de l'absence et du manque de tout ce qui a disparu. Robelt Bober, Raymond Federman, Patrick Modiano et Georges Perec engagent leur pratique littéraire dans un travail profond sur les modes d'écriture qui semblent être le seul moyen de parvenir à la résolution de la problématique de l' «indicible» qui obsede la plupart des auteurs de cette génération. Notre étude portera sur Quoi de neuf sur la guerre ? de Robert Bober, La voix dans le cabinet de débarras de Raymond Federman, Dora Bruder de Patrick Modiano et Récits d'Ellis Island de Georges Perec et Robert Bober. La Shoah et les traces qu'elle a laissées dans le monde d'aujourd'hui résonnent dans toutes ces reuvres tout en s'insérant dans un univers de la discrétion que nous considérons une «écriture en creux», c'est-à-dire une écriture marquée par la fragmentation, par l'obliquÍté et qui raconte sans raconter explicitement. Elle emploie des mécanismes et des structures qui révelent des points communs au sein de ce groupe d'auteurs, malgré les différences d'écritures et d'expériences personnelles. L'«écriture en creux» les réunit et devient la meilleure manifestation du travail de transmission et de recherche de la mémoire qui est le leur. L'Holocauste les a marqués d'une manÍere indélébile et a laissé, d'tm côté, le besoin de l'expression du manque de sens de tout ce qui est arrivé, de l'autre, celui de la quête d'un sens à la vie elle-même. Le corpus d'reuvres choisi est analysé selon des approches narratologique et thématique qUI mettent en lumiere les caractéristiques de cette forme particuliere d' écriture. L' approche narratologique nous permet une étude méticuleuse des procédés structurels mis en place par ces écrivains pour organiser une stratégie du fragmentaire et de l'incomplétude permettant de décrire le vi de sur lequel doit se, construire la vie apres le drame de la guerre. L'approche thématique aborde des contenus essentiels : le traitement de I'Histoire et une écriture autobiographique, ni tout à fait vraie ni tout à fait imaginaire. Des liens, à la fois étroits et problématiques se tissent alors entre Histoire collective et écriture de soi, brouillant les frontieres entre réalité et fiction et faisant apparaitre davantage le travail de quête de la mémoire que la mémoire elle-même. Ces reuvres constituent ainsi, non seulement une forme différente d'écrire sur la Shoah, mais encore une réflexion et une recherche de renouvellement au niveau des moyens d'expression et des gemes littéraires traditionnels., O vasto campo da literatura da «segunda geração» do Holocausto está intimamente marcado pela busca de meios que possam expressar a ausência e o vazio deixados por tudo aquilo que desapareceu. Robert Bober, Raymond Federman, Patrick Modiano e Georges Perec desenvolvem a sua prática literária num profundo trabalho sobre os modos de escrita que parecem ser a maneira de resolver a problemática do, Prodep

This work intends to create an orientation line for professionals of the construction sector, in a way to guarantee the Indoor Air Quality (IAQ) inside the buildings in Portugal. "Guidelines for the Sustainability" is being prepared and in it, the indoor air quality is considered as one of the most relevant parameters to be characterized. In an evident and didactic way, a guide will be published for architects, engineers and users, with some strategies to be applied in different project phases, from the design phase, through the utilization and up until the demolition phase., (undefined), info:eu-repo/semantics/publishedVersion

A large area colour imager optically addressed is presented. The colour imager consists of a thin wide band gap p-i-n a-SiC:H filtering element deposited on the top of a thick large area a-SiC:H(-p)/a-Si:H(-i)/a-SiC:H(-n) image sensor, which reveals itself an intrinsic colour filter. In order to tune the external applied voltage for full colour discrimination the photocurrent generated by a modulated red light is measured under different optical and electrical bias. Results reveal that the integrated device behaves itself as an imager and a filter giving information not only on the position where the optical image is absorbed but also on it wavelength and intensity. The amplitude and sign of the image signals are electrically tuneable. In a wide range of incident fluxes and under reverse bias, the red and blue image signals are opposite in sign and the green signal is suppressed allowing blue and red colour recognition. The green information is obtained under forward bias, where the blue signal goes down to zero and the red and green remain constant. Combining the information obtained at this two applied voltages a RGB colour image picture can be acquired without the need of the usual colour filters or pixel architecture. A numerical simulation supports the colour filter analysis.

A partir do momento em que o poder local e os Municípios assumem um papel cada vez mais preponderante na afirmação dos princípios da descentralização, democracia, participação e cidadania, o Assistente Social surge-nos como peça fundamental à concretização desses princípios tendo em vista alcançar uma sociedade mais justa, igualitária e a realização da plena cidadania. É partindo desta ideia basilar e tomando como objectivo geral compreender o nível de desenvolvimento do Serviço Social nos Municípios do distrito de Viseu, que esboçamos um retrato da profissão nesta área de intervenção no espaço geográfico referenciado. Os resultados que apresentamos surgem na sequência da informação obtida pela administração de questionários a todos os Assistentes Sociais a desempenharem funções nos Municípios do referido distrito. A partir destes dados foi possível constatar que a profissão de Assistente Social se institucionaliza em 1977, começa a expandir-se a partir de 1980 com o alargamento das políticas sociais e sob a influência dos fundos comunitários e culmina em 2000 com a integração da maioria das Assistentes Sociais que, têm vindo a alcançar um maior espaço e significado de intervenção na organização municipal e maior reconhecimento social. E se há aspectos da prática profissional que carecem ainda de alguns progressos e conquistas, nomeadamente nas questões que se prendem com a relação do poder político com o poder técnico, a sua inserção em estruturas orgânicas pouco especializadas e o facto de se defrontarem ainda com a falta de recursos a vários níveis, assinale-se como positivo, o facto de a maioria dos municípios terem já as suas competências regulamentadas e o poder político estar mais consciente da realidade social no âmbito de cada concelho. Também, ao nível do exercício profissional aspectos há que, atestam os largos passos dados pelos Assistentes Sociais com vista à sua afirmação. O desempenho de funções de coordenação, o seu envolvimento em projectos de investigação, a sua participação na planificação e orçamentalização das actividades, a autonomia para a elaboração de propostas, tomada de decisões e a definição de funções e prioridades de resposta as dar às situações. Ainda, a adopção de diversas estratégias de poder por forma a cumprir os seus objectivos profissionais e agir prioritariamente de acordo com os interesses colectivos da população utente, tendo em vista a melhoria da sua qualidade de vida e o seu empowerment são reflexos das conquistas e legitimações dos Assistentes Sociais nos municípios do distrito de Viseu.

ZnO:Al/p (SiC:H)/i (Si:H)/n (SiC:H) large area image and colour sensor are analysed. Carrier transport and collection efficiency are investigated from dark and illuminated current–voltage ( I – V ) dependence and spectral response measurements under different optical and electrical bias conditions. Results show that the carrier collection depends on the optical bias and on the applied voltage. By changing the electrical bias around the open circuit voltage it is possible to filter the absorption at a given wavelength and so to tune the spectral sensitivity of the device. Transport and optical modelling give insight into the internal physical process and explain the bias control of the spectral response and the image and colour sensing properties of the devices.

This work presents preliminary results in the study of a novel structure for a laser scanned photodiode (LSP) type of image sensor. In order to increase the signal output, a stacked p–i–n–p–i–n structure with an intermediate light-blocking layer is used. The image and the scanning beam are incident through opposite sides of the sensor and their absorption is kept in separate junctions by an intermediate light-blocking layer. As in the usual LSP structure the scanning beam-induced photocurrent is dependent on the local illumination conditions of the image. The main difference between the two structures arises from the fact that in this new structure the image and the scanner have different optical paths leading to an increase in the photocurrent when the scanning beam is incident on a region illuminated on the image side of the sensor, while a decreasing in the photocurrent was observed in the single junction LSP. The results show that the structure can be successfully used as an image sensor even though some optimization is needed to enhance the performance of the device.

We discuss the operation of a new type of optical sensor (MISCam) based on a metal–insulator–semiconductor (MIS) structure. The operation principle relies on light-induced changes of the band bending and barrier height at the interface between semiconductor and insulator. An image is obtained from the quenching of the ac signal in analogy to the principle of the laser-scanned photodiode (LSP). Lateral resolution depends on the semiconductor material chosen. We have characterised the MIS structures by C – V , I – V , and spectral response measurements testing different types of insulators like a-Si 3 N 4 , SiO 2 , and AlN. The presence of slow interface charges allows for image memory. Colour sensors can be realised by controlling sign and magnitude of the electric fields in the base and the interface region.

In this paper we demonstrate an add/drop filter based on SiC technology. Tailoring of the channel bandwidth and wavelength is experimentally demonstrated. The concept is extended to implement a 1 by 4 wavelength division multiplexer with channel separation in the visible range. The device consists of a p-i'(a-SiC:H)-n/p-i(a-Si:H)-n heterostructure. Several monochromatic pulsed lights, separately or in a polychromatic mixture illuminated the device. Independent tuning of each channel is performed by steady state violet bias superimposed either from the front and back sides. Results show that, front background enhances the light-to-dark sensitivity of the long and medium wavelength channels and quench strongly the others. Back violet background has the opposite behaviour. This nonlinearity provides the possibility for selective removal or addition of wavelengths. An optoelectronic model is presented and explains the light filtering properties of the add/drop filter, under different optical bias conditions.

A study of an image detector based on µc-Si:H p-i-n structures is presented. The photodetector has a TCO/µc-p-i-n Si:H configuration with two coplanar metallic contacts and a transverse one.We used a strong spatially fixed light pattern with different intensities to simulate the images and a weak moving light beam to sweep the device in the lateral direction, for its recognition. The sensor surface was scanned row by row and a signal processing procedure was applied to the data after each sweep. It was found that the induced transverse and lateral photovoltages are sensitive to the position and intensity of the image. Through a readout analysis it was possible to recognise, in a continuous way, the image position and relative intensity. The image resolution as a function of the pattern width and intensity is also analysedA small signal circuit modelling and a simulation consistent with the experimental data are presented and explained. Preliminary tests show that the detector can be used as a two-dimensional image sensor.

The behaviour of a inicrocrystalline p-i-n junction locally illuminated with monochromatic radiation (incident power of 50 mW/cm2) is analysed by means of numerical experiences. The model used for the two-dimensional analysis of the transport properties of a μc-Si:H p-i-n photo-detector is based on the simultaneous solution of the continuity equations for holes and electrons together with the Poisson's equation. The solution is found on a rectangular domain, taking into account the dimension perpendicular to the junction plane and one on the parallel plane. The lateral effects occurring wimin the structure, due to the non-uniformity of the illumination, are outlined. The results we present show that the potential profile has a linear variation from the illuminated to the dark neutral region. The lateral components of the electric field and of the current density vectors reveal to be mainly localised inside the doped layers.

This paper reports on optical filters based on a-SiC:H tandem pin/pin heterostructures. The spectral sensitivity is analyzed. Steady state optical bias with different wavelengths are applied from each front and back sides and the photocurrent is measured. Results show that it is possible to control the sensitivity of the device and to tune a specific wavelength range by combining radiations with complementary light penetration depths. The transfer characteristics effects due to changes in the front and back optical bias wavelength are discussed. Depending on the wavelength of the external background and irradiation side, the device acts either as a short-or a long-pass band filter or as a band-stop filter. The output waveform presents a nonlinear amplitude-dependent response to the wavelengths of the input channels.

Osteopontin is an Arg-Gly-Asp-containing acidic phosphoprotein recently shown to be upregulated in vascular smooth muscle during rat arterial neointima formation and in human atherosclerotic plaques. Functional studies showed that osteopontin promoted adhesion of both cultured aortic endothelial cells and aortic smooth muscle cells. Adhesion of vascular cells to osteopontin was dose dependent and half maximal when solutions containing 7 and 30 nmol/L osteopontin were used to coat wells for endothelial and smooth muscle cells, respectively. Smooth muscle cells adherent to osteopontin were spread after 60 minutes, whereas endothelial cells remained round, although flattened, at this time point but were spread at 90 minutes. Cell spreading on osteopontin was accompanied by the formation of focal adhesion plaques. A newly developed anti-osteopontin antibody completely inhibited adhesion of both cell types to osteopontin but not to fibronectin or vitronectin. In addition, the peptide GRGDSP blocked adhesion to osteopontin, suggesting that integrins mediate Arg-Gly-Asp-dependent adhesion. Indeed, an antibody against the alpha v beta 3 integrin neutralized adhesion of both endothelium and smooth muscle cells to osteopontin by approximately 50%, demonstrating that alpha v beta 3 is one osteopontin receptor on vascular cells. Osteopontin also promoted the migration of smooth muscle cells in a Boyden-type chamber, with half-maximal effects observed at 77 nmol/L osteopontin. Checkerboard analysis demonstrated that this stimulus was chemotactic in nature. Our findings suggest that osteopontin may be functionally important as an adhesive and chemotactic molecule for vascular cells, particularly when levels of osteopontin are dramatically increased, as is the case after arterial angioplasty and in atherosclerotic plaques.

This work presents experimental data concerning the role of the oxygen partial pressure used during the preparation process, on the structure, composition and optoelectronic properties of wide band gap doped microcrystalline silicon oxycarbide films produced by a TCDDC system [1].

In an earlier report, we used differential cloning to identify genes that might be critical in controlling arterial neointima formation (Giachelli, C., N. Bae, D. Lombardi, M. Majesky, and S. Schwartz. 1991. Biochem. Biophys. Res. Commun. 177:867-873). In this study, we sequenced the complete cDNA and conclusively identified one of these genes, 2B7, as rat osteopontin. Using immunochemistry and in situ hybridization, we found that medial smooth muscle cells (SMC) in uninjured arteries contained very low levels of osteopontin protein and mRNA. Injury to either the adult rat aorta or carotid artery using a balloon catheter initiated a qualitatively similar time-dependent increase in both osteopontin protein and mRNA in arterial SMC. Expression was transient and highly localized to neointimal SMC during the proliferative and migratory phases of arterial injury, suggesting a possible role for osteopontin in these processes. In vitro, basic fibroblast growth factor (bFGF), transforming growth factor-beta (TGF-beta), and angiotensin II (AII), all proteins implicated in the rat arterial injury response, elevated osteopontin expression in confluent vascular SMC. Finally, we found that osteopontin was a novel component of the human atherosclerotic plaque found most strikingly associated with calcified deposits. These data implicate osteopontin as a potentially important mediator of arterial neointima formation as well as dystrophic calcification that often accompanies this process.

PIN solar cells were light soaked up to 60 hours. The cell characteristics, the optoelectronic properties and the microstructure parameter (R=I2100/I2100+I2000) as well as the hydrogen content (CH) and density of states (g(Ef)) of the active i-layer were monitored throughout the entire light induced degradation process and compared with the correspondents μτ product (for both carriers) inferred through steady photoconductivity and FST measurements.Data show a strong correlation between the decrease of μτ product for electron and the increase of the fraction of hydrogen bonded on internal surfaces (R increases from 0.1 to 0.4) suggesting structural changes during the light induced defects' formation. For holes, the μτ product remains approximately constant and only dependent on the initial hydrogen content. As g(Ef) increases, μτ presents an asymmetrical decrease showing that electrons are more sensitive to defects' growth than holes.We also observe that the rate of degradation is faster for samples having the lowest defect densities, R and CH, showing that the amount of degradation is not a simple function of the photon exposure (Gt product) but also depends on the material microstructure.

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This article reports on a-Si:H-based low-leakage blue-enhanced photodiodes for dual-screen x-ray imaging detectors. Doped nanocrystalline silicon was incorporated in both the n- and p-type regions to reduce absorption losses for light incoming from the top and bottom screens. The photodiode exhibits a dark current density of 900 pA/cm2 and an external quantum efficiency up to 90% at a reverse bias of 5 V. In the case of illumination through the tailored p-layer, the quantum efficiency of 60% at a 400 nm wavelength is almost double that for the conventional a-Si:H n-i-p photodiode.