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Sensores e actuadores baseados em polímeros piezoeléctricos
Castro, H. F.Dissertação de Mestrado em Electrónica Industrial, área de Especialização em Automação e Robótica. ; Há cerca de 100 anos, Jacques e Pierre Curie confirmaram a existência do efeito piezoeléctrico em cristais de quartzo. Nos últimos 50 anos os sensores piezoeléctricos provaram ser uma ferramenta versátil na medida de vários processos. Actualmente, são usados na determinação de pressão, aceleração, deformações o...
Separation of the pyro- and piezoelectric response of electroactive polymers fo...
Castro, H. F.; Lanceros-Méndez, S.; Rocha, J. G.One of the main problems for the use of ferroelectric materials for sensor applications, especially for tactile sensors, is the separation of the pyro- and piezoelectric responseproduced by temperature and pressure changes, respectively. We present two different approaches to achieve this goal. The first approach is based on the study of the signal in the frequency domain and uses a signal processing to separat...
Immobilization and catalytic properties of lipase on chitosan for hydrolysis an...
Pereira,E.B.; Zanin,G.M.; Castro,H.F.The objective of this study was to evaluate the immobilization of lipase on a chitosan support by physical adsorption, aiming at its application in hydrolytic and synthetic reactions. Two types of chitosan (flakes and porous) were used for immobilizing lipase from a microbial source (Candida rugosa) and animal cells (porcine pancreas). The best results for recovery of total activity after immobilization were ob...
Evaluation of inorganic matrixes as supports for immobilization of microbial li...
Castro,H.F.; Silva,M.L.C.P.; Silva,G.L.J.PCandida rugosa was immobilized by physical adsorption on several inorganic supports using hexane as coupling medium. The enzymatic activities of the different derivatives were determined by both hydrolysis of olive oil and esterification of n-butanol with butyric acid. The results were compared to previous data obtained by using a controlled porous silica matrix. The goal was to contribute in searching inexpens...
Influence of substrate partition coefficient on the performance of lipase catal...
Castro,H.F.; Oliveira,P.C.; Pereira,E.B.The enzymatic synthesis of selected low molecular weight esters such as acetate esters by direct esterification using acetic acid as acyl donor usually display low yields. The acetic acid changes the polarity of the reaction medium, which in this turn modifies the partitioning of water between the solid phase (enzyme preparation) and the liquid phase (substrate), resulting in its accumulation on the enzyme soli...
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