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Teaching Signal Analysis to Electrical Engineering Students
Paulo J. S. G. Ferreira; Ana M. P. Tomé; Francisco VazThe techniques of harmonic analysis play a crucial role in Electrical engineering practice today. Any teacherknows that conveying these techniques is usually far from being an easy task. As for students, they do not exactly regard the subject as the simplest part of their curricula. One of the difficulties faced by the teacher concerns the number of concepts and tools that need to be taught. They include classi...
Spectroscopic characterization of schiff base-copper complexes immobilized in s...
Dias,Patrícia M.; Kinouti,Lilian; Constantino,Vera R. L.; Ferreira,Ana M. D. C.; Gonçalves,Marcos B.; Nascimento,Rafael R. do; Petrilli,Helena M.Herein, the immobilization of some Schiff base-copper(II) complexes in smectite clays is described as a strategy for the heterogenization of homogeneous catalysts. The obtained materials were characterized by spectroscopic techniques, mostly UV/Vis, EPR, XANES and luminescence spectroscopy. SWy-2 and synthetic Laponite clays were used for the immobilization of two different complexes that have previously shown ...
Interactions of di-imine copper(II) complexes with albumin: competitive equilib...
Azzellini,M. Amélia A.; Abbott,Mariana P.; Machado,Alessandra; Miranda,M. Terêsa M.; Garcia,Leone C.; Caramori,Giovanni F.; Gonçalves,Marcos B.Interactions of some diimine copper(II) complexes with bovine serum albumin (BSA) were investigated by spectroscopic techniques in order to compare the stability of the complexes and their capability of causing oxidative damage to the protein. The tri- and tetradentate imine ligands employed in this work contain pyridine, pyrazine or imidazole moieties, which are ubiquitous in biological systems. The relative t...
Distribution of collagen types I, III, and IV in gastric tissue of marmosets (C...
Mello,Marcela F.V. de; Pissinatti,Alcides; Ferreira,Ana M.R.Extracellular matrix (ECM) components such as fibrillar collagens play a fundamental role in wound repair and have also been studied in association with the gastric ulcer healing process in gastroenterology. Nevertheless, there have been no studies in the literature to date regarding the description and characterization of ECM components, neither in normal nor in injured gastric tissue of primate species. The o...
Histological biomarkers in liver and gills of juvenile Solea senegalensis exposed
Costa, Pedro M.; Diniz, Mário S.; Caeiro, Sandra; Lobo, Jorge; Martins, Marta; Ferreira, Ana M.; Caetano, Miguel; Vale, Carlos; DelValls, ÁngelYoung juvenile Solea senegalensis were exposed to three sediments with distinct contamination profiles collected from a Portuguese estuary subjected to anthropogenic sources of contamination (the Sado estuary, western Portugal). Sedimentswere surveyed formetals (cadmium, chromium, copper, nickel, lead and zinc), ametalloid (arsenic) and organic contaminants (polycyclic aromatic hydrocarbons, polychlorinated bip...
Biochemical endpoints on juvenile Solea senegalensis exposed
Costa, Pedro M.; Caeiro, Sandra; Diniz, Mário S.; Lobo, Jorge; Martins, Marta; Ferreira, Ana M.; Caetano, Miguel; Vale, Carlos; DelValls, ÁngelJuvenile Solea senegalensis were exposed to fresh sediments from three stations of the Sado estuary (Portugal) in 28-day laboratory assays. Sediments revealed distinct levels of total organic matter, fine fraction, redox potential, trace elements (arsenic, cadmium, chromium, copper, nickel, lead and zinc) and organic contaminants (polycyclic aromatic hydrocarbons, polychlorinated biphenyls and a pesticide: dich...
Synthesis and characterization of the thermal and the solvatochromic properties...
Raposo, M. Manuela M.; Ferreira, Ana M. P. F.; Amaro, Mariana; Belsley, M.; Moura, João C. V. P.A series of heterocyclic azo dyes was synthesized by diazotation of several substituted anilines and coupling with 5-N,N-dialkylamino-2,2´-bithiophenes to give 4-phenylazo-5-N,N-dialkylamino-2,2´-bithiophenes 4-7. This reaction contrasts with the behavior of 5-alkoxy-2,2´-bithiophenes towards aryldiazonium salts which gave 5-phenylazo-5-alkoxy-2,2´-bithiophenes. The thermal stability of the derivatives was eval...
5-Arylazo-2,2´-bithiophenes : a novel promising series of NLO chromophores
Raposo, M. Manuela M.; Ferreira, Ana M. P. F.; Belsley, M.; Gomes, E. Matos; Moura, João C. V. P.The synthesis of 5-arylazo- substituted bithiophenes and their UV-visible, solvatochromic and nonlinear optical properties (NLO) are described. In agreement with the solvatochromic data and also with the second-order molecular NLO characterization, the new donor-acceptor systems could find application as suitable solvatochromic probes and also as new NLO materials.
5´-alkoxy-2,2´-bithiophene azo dyes : a novel promising series of NLO chromophores
Raposo, M. Manuela M.; Ferreira, Ana M. P. F.; Belsley, M.; Moura, João C. V. P.A series of bithienyl azo dyes has been prepared from their corresponding coupling components, 5-alkoxy-2,2´-bithiophenes. The solvatochromic behavior of the compounds was investigated. The hyperpolarizabilities β of derivatives 3-5 were measured using hyper-Rayleigh scattering and thermogravimetric analysis (TGA) was used to evaluate their thermal stability. The experimental results indicate that, good nonlin...
Equilibria and catalytic properties of a chloro-bridged Diimine copper(II) comp...
Alves,Wendel A.; Almeida-Filho,Saulo A. de; Santos,Regina H. de Almeida; Paduan-Filho,Armando; Ferreira,Ana M. da CostaSome new copper(II) complexes with a tridentate imine ligand, bimpy (or 2-(benzimidazolyl)methylene-2-amino-1-ethylpyridine), were prepared, and had their catalytic activity in the N,N,N',N'-tetramethyl- p-phenylenediamine (TMPD) oxidation compared. Mononuclear species, [Cu(bimpy)(H2O)2](NO3 )2, (1) and [Cu(bimpy)Cl2]·H2O, (2), as well as the dinuclear species containing chloro-bridges, [Cu2(bimpy)2Cl2]X...
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