Detection of Change in Fluorescence Between Reactive Cyan and the Yellow Fluorophores Usinga-SiC:H Multilayer Transducers

Optical colour sensors based on multilayered a-SiC:H heterostructures can act as voltage controlled optical filters in the visible range. In this article we investigate the application of these structures for Fluorescence Resonance Energy Transfer (FRET) detection, The characteristics of a-SiC:H multilayered structure are studied both theoretically and experimentally in several wavelengths corresponding to different fluorophores. The tunable optical p-i'(a-SiC:H)-n/p-i(a-Si:H)-n heterostructures were produced by PECVD and tested for a proper fine tuning in the violet, cyan and yellow wavelengths. The devices were characterized through transmittance and spectral response measurements, under different electrical bias and frequencies. Violet, cyan and yellow signals were applied in simultaneous and results have shown that they can be recovered under suitable applied bias. A theoretical analysis supported by numerical simulation is presented.

Detection of Change in Fluorescence Between Reactive Cyan and the Yellow Fluorophores Using a-SiC:H Multilayer Transducers

The transducer consists of a semiconductor device based on two stacked -i-n heterostructures that were designed to detect the emissions of the fluorescence resonance energy transfer between fluorophores in the cyan (470 nm) and yellow (588 nm) range of the spectrum. This research represents a preliminary study on the use of such wavelength-sensitive devices as photodetectors for this kind of application. The device was characterized through optoelectronic measurements concerning spectral response measurements under different electrical and optical biasing conditions. To simulate the fluorescence resonance energy transfer (FRET) pairs, a chromatic time-dependent combination of cyan and yellow wavelengths was applied to the device. The generated photocurrent was measured under reverse and forward bias to read out the output photocurrent signal. A different wavelength-biasing light was also superimposed. Results show that under reverse bias, the photocurrent signal presents four separate levels, each one assigned to the different wavelength combinations of the FRET pairs. If a blue background is superimposed, the yellow channel is enhanced and the cyan suppressed, while under red irradiation, the opposite behavior occurs. So, under suitable biasing light, the transducer is able to detect separately the cyan and yellow fluorescence pairs. An electrical model, supported by a numerical simulation, supports the transduction mechanism of the device.

Use of quantitative structure-property relationships to study the solvation process of 18-crown-6

Solution enthalpies of 18-crown-6 have been obtained for a set of 14 protic and aprotic solvents at 298.15 K. The complementary use of Solomonov's methodology and a QSPR-based approach allowed the identification of the most significant solvent descriptors that model the interaction enthalpy contribution of the solution process (Delta H-int(A/S)). Results were compared with data previously obtained for 1,4-dioxane. Although the interaction enthalpies of 18-crown-6 correlate well with those of 1,4-dioxane, the magnitude of the most relevant parameters, pi* and beta, is almost three times higher for 18-crown-6. This is rationalized in terms of the impact of the solute's volume in the solution processes of both compounds. (C) 2015 Elsevier B.V. All rights reserved.

Influence of the crushing process of recycled aggregates on concrete properties

This work intends to evaluate the (mechanical and durability) performance of concrete made with coarse recycled concrete aggregates (CRCA) obtained using two crushing processes: primary crushing (PC) and primary plus secondary crushing (PSC). This analysis intends to select the most efficient production process of recycled aggregates (RA). The RA used here resulted from precast products (P), with strength classes of 20 MPa, 45 MPa and 65 MPa, and from laboratory-made concrete (L) with the same compressive strengths. The evaluation of concrete was made with the following tests: compressive strength; splitting tensile strength; modulus of elasticity; carbona-tion resistance; chloride penetration resistance; capillary water absorption; and water absorption by immersion. These findings contribute to a solid and innovative basis that allows the precasting industry to use without restrictions the waste it generates. © (2015) Trans Tech Publications, Switzerland.

O crédito concedido às empresas: antes e no decorrer da crise mundial. Análise e gestão do risco de crédito

O tema do trabalho de investigação é a análise do risco de crédito às empresas antes e durante a actual crise financeira, bem como a sua gestão. A gestão de risco de crédito das instituições financeiras tem-se transformado cada vez mais numa peça chave para toda a actividade bancária, tendo ainda mais significado no mundo actual, em constante mudança e globalização. A concessão de crédito às empresas tornou-se numa tarefa cada vez mais árdua, para as instituições financeiras devido ao risco de crédito. A presente dissertação foi desenvolvida visando os objectivos de efectuar uma avaliação na concessão de crédito a empresas durante a crise, com ênfase na gestão do risco de crédito, bem como na utilização do Acordo de Basileia II. Para atingir os objectivos traçados a metodologia utilizada foi o inquérito por questionário a colaboradores da Caixa Geral de Depósitos (CGD). O questionário foi efectuado, de forma a captar quer os desenvolvimentos passados, como recentes, bem como a evolução esperada. Relativamente à evolução passada, as perguntas respeitam aos anos anteriores à crise, enquanto as perguntas prospectivas se referem aos anos seguintes. O trabalho desenvolvido permitiu-nos concluir que as instituições financeiras mundiais, desde o início da recessão, têm restringido ao máximo a concessão de crédito às empresas. Muitas instituições têm-no feito através da exigência de mais garantias, aumento do spread, bem como a diminuição de maturidades. Todas estas situações geram um ciclo vicioso, na medida em que as empresas que se vêem confrontadas na restrição do acesso ao crédito, não têm condições para sobreviver, gerando assim várias falências.

Gestão em farmácia - Implementação de um sistema de distribuição de medicamentos Pyxis®: um estudo de caso de dois hospitais centrais

Mestrado em Intervenção Sócio-Organizacional na Saúde - Área de especialização: Políticas de Administração e Gestão em Saúde