28 resultados para RU(BPY)(3)(3 )-BASED CHEMILUMINESCENCE DETECTION
em Repositório Científico do Instituto Politécnico de Lisboa - Portugal
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This paper presents an integrated system for vehicle classification. This system aims to classify vehicles using different approaches: 1) based on the height of the first axle and_the number of axles; 2) based on volumetric measurements and; 3) based on features extracted from the captured image of the vehicle. The system uses a laser sensor for measurements and a set of image analysis algorithms to compute some visual features. By combining different classification methods, it is shown that the system improves its accuracy and robustness, enabling its usage in more difficult environments satisfying the proposed requirements established by the Portuguese motorway contractor BRISA.
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An optically addressed read-write sensor based on two stacked p-i-n heterojunctions is analyzed. The device is a two terminal image sensing structure. The charge packets are injected optically into the p-i-n writer and confined at the illuminated regions changing locally the electrical field profile across the p-i-n reader. An optical scanner is used for charge readout. The design allows a continuous readout without the need for pixel-level patterning. The role of light pattern and scanner wavelengths on the readout parameters is analyzed. The optical-to-electrical transfer characteristics show high quantum efficiency, broad spectral response, and reciprocity between light and image signal. A numerical simulation supports the imaging process. A black and white image is acquired with a resolution around 20 mum showing the potentiality of these devices for imaging applications.
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Two fluorescent molecular receptor based conjugated polymers were used in the detection of a nitroaliphatic liquid explosive (nitromethane) and an explosive taggant (2,3-dimethyl-2,3-dinitrobutane) in the vapor phase. Results have shown that thin films of both polymers display remarkably high sensitivity and selectivity toward these analytes. Very fast, reproducible, and reversible responses were found. The unique behavior of these supramolecular host systems is ascribed to cooperativity effects developed between the calix[4] arene hosts and the phenylene ethynylene-carbazolylene main chains. The calix[4]-arene hosts create a plethora of host-guest binding sites along the polymer backbone, either in their bowl-shaped cavities or between the outer walls of the cavity, to direct guests to the area of the transduction centers (main chain) at which favorable photoinduced electron transfer to the guest molecules occurs and leads to the observed fluorescence quenching. The high tridimensional porous nature of the polymers imparted by the bis-calixarene moieties concomitantly allows fast diffusion of guest molecules into the polymer thin films.
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In this paper we present results on the optimization of multilayered a-SiC:H heterostructures that can be used as optical transducers for fluorescent proteins detection using the Fluorescence Resonance Energy Transfer approach. Double structures composed by pin based aSiC:H cells are analyzed. The color discrimination is achieved by ac photocurrent measurement under different externally applied bias. Experimental data on spectral response analysis, current-voltage characteristics and color and transmission rate discrimination are reported. An electrical model, supported by a numerical simulation gives insight into the device operation. Results show that the optimized a-SiC:H heterostructures act as voltage controlled optical filters in the visible spectrum. When the applied voltages are chosen appropriately those optical transducers can detect not only the selective excitation of specimen fluorophores, but also the subsequent weak acceptor fluorescent channel emission.
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Nowadays, most individuals spend about 80% of their time indoor and, consequently, the exposure to the indoor environment becomes more relevant than to the outdoor one. Children spend most of their time at home and at school and evaluations of their indoor environment are important for the time-weighted exposure. Due to their airways still in development, children are a sensitive group with higher risk than adults. Larger impact in health and educational performance of children demand indoor air quality studies of schools. The aim of this study was to assess the children exposure to bioaerosols. A methodology based upon passive sampling was applied to evaluate fungi, bacteria and pollens; its procedures and applicability was optimized. An indoor air study by passive sampling represents an easier and cheaper method when comparing with the use of automatic active samplers. Furthermore, it is possible to achieve important quality information without interfering in the classroom activities. The study was conducted in three schools, representative of different environments in the Lisbon urban area, at three different periods of the year to obtain a seasonal variation, to estimate the variability through the city and to understand the underneath causes. Fungi and bacteria were collected indoor and outdoor of the classrooms to determine the indoor/outdoor ratios and to assess the level of outdoor contamination upon the indoor environment. The children's exposure to pollen grains inside the classrooms was also assessed.
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The devastating impact of the Sumatra tsunami of 26 December 2004, raised the question for scientists of how to forecast a tsunami threat. In 2005, the IOC-UNESCO XXIII assembly decided to implement a global tsunami warning system to cover the regions that were not yet protected, namely the Indian Ocean, the Caribbean and the North East Atlantic, the Mediterranean and connected seas (the NEAM region). Within NEAM, the Gulf of Cadiz is the more sensitive area, with an important record of devastating historical events. The objective of this paper is to present a preliminary design for a reliable tsunami detection network for the Gulf of Cadiz, based on a network of sea-level observatories. The tsunamigenic potential of this region has been revised in order to define the active tectonic structures. Tsunami hydrodynamic modeling and GIS technology have been used to identify the appropriate locations for the minimum number of sea-level stations. Results show that 3 tsunameters are required as the minimum number of stations necessary to assure an acceptable protection to the large coastal population in the Gulf of Cadiz. In addition, 29 tide gauge stations could be necessary to fully assess the effects of a tsunami along the affected coasts of Portugal, Spain and Morocco.
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The spectral response and the photocurrent delivered by entirely microcrystalline p-i-n-Si:H detectors an analysed under different applied bias and light illumination conditions. The spectral response and the internal collection depend not only on the energy range but also on the illumination side. Under [p]- and [n]-side irradiation, the internal collection characteristics have an atypical shape. It is high for applied bias and lower than the open circuit voltage, shows a steep decrease near the open circuit voltage (higher under [n]-side illumination) and levels off for higher voltages. Additionally, the numerical modeling of the VIS/NIR detector, based on the band discontinuities near the grain boundaries and interfaces, complements the study and gives insight into the internal physical process.
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O objetivo desta investigação é compreender como é que alunos do 3.º ano de escolaridade desenvolvem o conceito de área com ênfase em conhecimentos sobre figuras e propriedades geométricas. Para melhor objetivar o estudo, formulei três questões que orientaram a investigação. Pretendo (1) compreender como é que os alunos mobilizam conhecimentos sobre as propriedades das figuras geométricas no estudo da área de uma figura plana? A que estratégias recorrem? Que dificuldades sentem? (2) que compreensão é que os alunos têm sobre o processo de medição? e (3) que ideias e/ou experiências são relevantes no desenvolvimento do conceito de área? Este é um estudo que se insere no paradigma interpretativo e que segue uma abordagem qualitativa, pelo que não visa generalização de resultados, mas uma descrição compreensiva dos processos vivenciados, tendo em conta os contextos pessoais e sociais. Optei por realizar dois Estudos de Caso. Os dados foram recolhidos através de fontes diversificadas, donde se destacam a observação participante e a análise de registos audiovisuais e escritos dos alunos. A análise dos dados teve por referência categorias criadas com base em contributos da literatura de referência. As conclusões desta investigação centram-se numa análise acerca das estratégias a que os alunos em estudo tendencialmente mais recorrem, visando também algumas das suas dificuldades mais relevantes e sobre as quais importa refletir. Destaca-se que ambos os alunos foram capazes de recorrer a raciocínios baseados e não baseados na medida, embora seja evidente uma tendência para raciocínios baseados na medida. É igualmente importante referir que os dois alunos revelaram um bom conhecimento acerca do processo de medição, mesmo quando ele implicava a definição de uma unidade de medida adequada e/ou mudança de unidade. É dado, também, destaque às experiências matemáticas que devem ser proporcionadas aos alunos no sentido do desenvolvimento de um conhecimento amplo e flexível do conceito de área. - Abstract The purpose of this investigation is to understand the development of 3rd year students’ concept of area based on their knowledge of geometrical properties and figures. As means to orientate the present study, the following investigation questions were formulated: 1) how do students use their knowledge about geometrical properties in order to understand geometrical shape’s areas? Which strategies do they use? What do they struggle with? (2) What is their understanding about measurement? And (3) what are the most relevant mathematical reasonings and classroom tasks in the development of the concept of area? This is a study that follows a qualitative approach: it does not intend to be a generalization, but a fully comprehensive description of the witnessed learning processes, bearing in mind the social and personal contexts. As such, two study-cases were developed. The data were collected through various sources, such as direct observation and analysis of audiovisual records or written worksheets. The scrutiny of the generated data was undertaken following criteria based on the literature of reference. The conclusions of this investigation are centered on the most used strategies as well as the students’ difficulties upon which it is important to discuss. It was noticed that the two students were able to use both measurement and non measurement thinking – although, preferably, they tend to use the first one. On the other hand, it is equally demonstrated that the two students have shown good acquaintance about measurement, even if obliged to the establishment of a suitable unit of measurement and/or change of units. At last, it is also referred which mathematical classroom tasks are important to develop a sustained and comprehensive concept of area.
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A biosensor for urea has been developed based on the observation that urea is a powerful active-site inhibitor of amidase, which catalyzes the hydrolysis of amides such as acetamide to produce ammonia and the corresponding organic acid. Cell-free extract from Pseudomonas aeruginosa was the source of amidase (acylamide hydrolase, EC 3.5.1.4) which was immobilized on a polyethersulfone membrane in the presence of glutaraldehyde; anion-selective electrode for ammonium ions was used for biosensor development. Analysis of variance was used for optimization of the biosensorresponse and showed that 30 mu L of cell-free extract containing 7.47 mg protein mL(-1), 2 mu L of glutaraldehyde (5%, v/v) and 10 mu L of gelatin (15%, w/v) exhibited the highest response. Optimization of other parameters showed that pH 7.2 and 30 min incubation time were optimum for incubation ofmembranes in urea. The biosensor exhibited a linear response in the range of 4.0-10.0 mu M urea, a detection limit of 2.0 mu M for urea, a response timeof 20 s, a sensitivity of 58.245 % per mu M urea and a storage stability of over 4 months. It was successfully used for quantification of urea in samples such as wine and milk; recovery experiments were carried out which revealed an average substrate recovery of 94.9%. The urea analogs hydroxyurea, methylurea and thiourea inhibited amidase activity by about 90%, 10% and 0%, respectively, compared with urea inhibition.
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The main purpose of the present study is to determine if the circadian rhythms present in the human bone marrow are likely to influence 3’- deoxy- 3’-[18F] Fluorothymidine (18F-FLT) uptake in the same organ. The 18F-FLT is a Thymidine analogous proliferation agent. The relatively high physiological uptake of this tracer in the bone marrow diminishes the Tumor/Background (T/B) ratio, decreasing the detection accuracy of PET/CT and possibly affecting SUV quantifications.
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Glucose sensing is an issue with great interest in medical and biological applications. One possible approach to glucose detection takes advantage of measuring changes in fluorescence resonance energy transfer (FRET) between a fluorescent donor and an acceptor within a protein which undergoes glucose-induced changes in conformation. This demands the detection of fluorescent signals in the visible spectrum. In this paper we analyzed the emission spectrum obtained from fluorescent labels attached to a protein which changes its conformation in the presence of glucose using a commercial spectrofluorometer. Different glucose nanosensors were used to measure the output spectra with fluorescent signals located at the cyan and yellow bands of the spectrum. A new device is presented based on multilayered a-SiC:H heterostructures to detect identical transient visible signals. The transducer consists of a p-i'(a-SiC:H)-n/p-i(a-Si:H)-n heterostructure optimized for the detection of the fluorescence resonance energy transfer between fluorophores with excitation in the violet (400 nm) and emissions in the cyan (470 nm) and yellow (588 nm) range of the spectrum. Results show that the device photocurrent signal measured under reverse bias and using appropriate steady state optical bias, allows the separate detection of the cyan and yellow fluorescence signals presented.
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This paper presents the characterization of an indoor Wimax radio channel using the Finite-Difference Time-Domain (FDTD) [1] method complemented with the Convolutional Perfect Matched Layer (CPML) technique [2]. An indoor 2D scenario is simulated in the 3.5GHz band (IEEE 802.16d-2004 and IEEE 802.16e-2005 [3]). In this study, we used two complementary techniques in both analysis, technique A and B for fading based on delay spread and technique C and D for fading based on Doppler spread. Both techniques converge to the same result. Simulated results define the channel as flat, slow and without inter-symbolic interference (ISI), making the application of the spatial diversity the most appropriate scheme.
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Red, green and blue optical signals were directed to an a-SiC:H multilayered device, each one with a specific transmission rate. The combined optical signal was analyzed by reading out, under different applied voltages, the generated photocurrent. Results show that when a chromatic time dependent wavelength combination with different transmission rates irradiates the multilayered structure, the device operates as a tunable wavelength filter and can be used in wavelength division multiplexing systems for short range communications. An application to fluorescent proteins detection is presented. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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Relatório Final de Estágio apresentado à Escola Superior de Dança, com vista à obtenção do grau de Mestre emMetodologias do Ensino da Dança.
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Relatório Final de Estágio apresentado à Escola Superior de Dança, com vista à obtenção do grau de Mestre em Ensino de Dança