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Auto-pulsação em Lasers de Semicondutor por Bloqueio de Modos e por Injecção

This article describes two techniques for operating a semiconductor laser in a pulsed regime, namely the mode locking and injection locking mechanisms. For each one we present the operational principle, the theory and simulation results. We also describe the self Q-switching mechanism in multi-sections DFB lasers. ; Este artigo descreve duas técnicas de operar um laser de s...

Auto-pulsação em Lasers de Semicondutor por Comutação do Ganho e do Factor de Q...

This article describes two techniques for operating a semiconductor laser in a pulsed regime, namely the gain switching and Q-switching mechanisms. For each one we present the operational principle, the theory and simulation results. ; Este artigo descreve duas técnicas de operar um laser de semicondutor em regime pulsado, nomeadamente o mecanismo de comutação...

Técnicas de Extracção Óptica de Relógio

With the increasing traffic and consequent demand for higher bitrates, optical telecommunications networks include new systems operating exclusively in the optical domain, thus avoiding the optical to electrical conversion. Modules implementing the procedure of alloptical clock recovery are of extreme importance because the produced signal has all the synchronisation information&nb...

Estabilidade de amostras de soro para o doseamento de vitamina B12 e de ácido f...

Effect of the acid environment on the electrochemical behaviour of 1045 steel r...

External corrosion is one of the most common causes of oilwell casing failure. Hostile environments can be due to acidizing treatments. Although it is common to add corrosion inhibitors and oxygen scavengers in acidic solutions to control external casing corrosion, their real efficiency is unknown yet. Therefore, it is important to establish how aggressive to steel are the different hostile environments to help...

Corrosion behaviour of titanium in the presence of Streptococcus mutans

Objective The main aim of this in vitro study was to evaluate the influence of Streptococcus mutans on the corrosion of titanium. Methods S. mutans biofilms were formed on commercially pure titanium (CP-Ti) square samples (10 mm × 10 mm × 1 mm) using a culture medium enriched with sucrose. Open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) measurements were used to evaluate the cor...

Flow systems, design and optimization

Special session: Flow systems, design and optimization 8th International Conference on Diffusion in Solids and Liquids, 25-29 June, 2012, Istanbul

Infeção do trato urinário - agentes etiológicos e padrão de resistência local

RESUMO Introdução: A infeção urinária é uma patologia comum em idade pediátrica. A antibioterapia deve ser iniciada empiricamente antes do isolamento do agente causal e os fármacos utilizados devem ter em conta os microrganismos e o padrão de resistência local. Objetivos: Identificação dos agentes etiológicos de infeção urinária e os seus padrões de resistência antibiótica no nosso hospital. Material e Métodos:...

Atypical haemolytic-uraemic syndrome caused by factor H mutation: case report a...

Atypical haemolytic uraemic syndrome is causedby alternative complement pathway dysregulation. It has recently been recognised that most cases are due to genetic factors and a growing list of mutations has been described. Atypical haemolytic uraemic syndrome is associated with a dismal prognosis, a relapsing course, high acute mortality and frequent progression to end-stage renal disease. We describe a five-ye...

Simultaneous degradation by corrosion and wear of titanium in artificial saliva...

Article in press ; The degradation of titanium-based oral rehabilitation systems can occur by corrosion and wear processes taking place simultaneously (tribocorrosion) and influenced by the presence of fluorides. In this study, the tribocorrosion behavior of titanium in artificial saliva solutions containing fluorides is investigated. Before sliding tests were started up, electrochemical measurements such as o...