2015
Autores
Queiros, C; Leite, A; Couto, MGM; Cunha Silva, L; Barone, G; de Castro, B; Rangel, M; Silva, AMN; Silva, AMG;
Publicação
CHEMISTRY-A EUROPEAN JOURNAL
Abstract
The two new fluorescent ligands RosCat1 and RosCat2 contain catechol receptors connected to rosamine platforms through an amide linkage and were synthesized by using microwave-assisted coupling reactions of carboxyl- or amine-substituted rosamines with the corresponding catechol units and subsequent deprotection. RosCat1 possesses a reverse amide, whereas RosCat2 has the usual oriented amide bond (HNCO vs. CONH, respectively). The ligands were characterized by means of NMR spectroscopy, mass-spectrometry, and DFT calculations and X-ray crystallography studies for RosCat1. The influence of the amide linkage on the photophysical properties of the fluorescent ligands was assessed in different solvents and showed a higher fluorescence quantum yield for RosCat1. The coordination chemistry of these ligands with a Fe-III center has been rationalized by mass-spectrometric analysis and semiempirical calculations. Octahedral Fe-III complexes were obtained by the chelation of three RosCat1 or RosCat2 ligands. Interestingly, the unconventional amide connectivity in RosCat1 imposes the formation of an eight-membered ring on the chelate complex through a salicylate-type mode of coordination.
2015
Autores
Queiros, C; Leite, A; Silva, AMG; Gameiro, P; de Castro, B; Rangel, M;
Publicação
POLYHEDRON
Abstract
We report the synthesis and physicochemical properties of a new tripodal hexadentate chelator (catTHC) synthesized by reaction of a flexible tripodal backbone with three bidentate catechol units. To improve the efficiency of the amide coupling reaction, classical conditions using two pairs of coupling reactants were tested, and a significant reduction in reaction time was achieved by using microwave irradiation with the reactants DCC/HOBt. Subsequent removal of the benzyl protecting groups using BCI3 in dichloromethane provided the final chelator in good yield. The acid-base properties of catTHC in aqueous solution and the affinity of the ligand towards iron(III) were investigated at variable pH and in the presence of iron(III) using spectroscopic methods. The hexadentate ligand forms a 1:1 complex with iron(III) whose stability constant was determined by competition with EDTA. The values obtained for the stability constant and pFe(3+) are log beta(110) = 36.70 and pFe(3+) = 26.7.
2014
Autores
Hussain, B; Kianpour, I; Tavares, VG; Mendonca, HS; Miskovic, G; Radosavljevic, G; Petrovic, VV;
Publicação
2014 IEEE INTERNATIONAL CONFERENCE ON WIRELESS FOR SPACE AND EXTREME ENVIRONMENTS (WISEE)
Abstract
This paper presents a planar antenna using low temperature co-fired ceramics (LTCC) substrate for extreme environment applications. An ultra wideband (UWB) elliptical patch antenna was designed and fabricated using an LTCC Ceramtec GC substrate to demonstrate the capabilities of the technology for wideband applications. The simulated results were further validated experimentally. The fabricated antenna provides a peak gain of 5dB over a bandwidth of 4 GHz (3 GHz 7 GHz) with return loss better than -10dB. The radiation pattern is omni-directional in the horizontal plane (theta=90 degrees) over the whole frequency range.
2014
Autores
Kianpour, I; Hussain, B; Tavares, VG; Duarte, C; Mendonca, H; Principe, J;
Publicação
2014 IEEE INTERNATIONAL CONFERENCE ON ULTRA-WIDEBAND (ICUWB)
Abstract
The integrate-and-fire model of a biological neuron is an amplitude to time encoding in the spacing between action potentials (spikes). In principle, this encoding can be used to modulate signals in an Impulse Radio Ultra Wide-Band (IRUWB) transmitter suitable for Wireless Sensor Networks (WSN). This paper presents a system level study on power efficiency using MATLAB/ Simulink to evaluate the required energy for an IR-UWB Transmitter using integrate-and-fire encoding technique. Also, a simple but clear comparison with common systems utilizing Nyquist rate Analog-to-Digital Converters (ADC) is presented. This study has been carried out on a band-limited random Gaussian signal and the results show that IR-IF transmitter consumes roughly seven times less energy than a digital UWB transmitter; moreover, in the proposed architecture the need for power hungry ADC is relaxed.
2014
Autores
Matos, JS; Alves, JC; Mendonca, HS; Araujo, AJ;
Publicação
Proceedings of the 2014 29th Conference on Design of Circuits and Integrated Systems, DCIS 2014
Abstract
The paper presents the approach followed at the Faculty of Engineering of the University of Porto, to introduce design automation tools and structured design techniques in the first course on digital system design of our Integrated Master in Electrical and Computer Engineering. Digital Systems Laboratory is an introductory course on digital design, with the classical task of teaching Boolean algebra and combinational and sequential circuit design, using gates, flip-flops and medium complexity components/function blocks like counters and shift-registers. The need to cope with new curriculum requirements and modern digital design demands, motivated an extensive reformulation of the course contents and organization, leading to the introduction of the use of hardware description languages and synthesis tools, in order to implement small systems, of increasingly complex nature, on an FPGA platform. At the same time its coverage was extended to include low-level processor architecture issues, and to teach assembly programming for the MIPS processor. The paper describes how this reformulation was carried out. It presents the course contents and timeline, and discusses the main choices that were made. The paper also describes the laboratory experiments that were developed and discusses some of the challenges and results obtained so far. © 2014 IEEE.
2014
Autores
Sousa, A; Mouraz, A;
Publicação
INTERNATIONAL JOURNAL OF ENGINEERING EDUCATION
Abstract
The so called 'Soft Skills' (SSs) are the set of non-technical skills that enable a given individual to interact effectively and harmoniously with other people. These skills are also interesting for the promotion of deep knowledge and to foster academic success. The case study analyses the very special 'Projeto FEUP' course that promotes SSs across all engineering programmes in the Faculty of Engineering of the University of Porto (FEUP), in Portugal. This is done right after the arrival of students at the institution by means of producing several communicational items over an adequate technical work. The study involved 781 students. The presented results hint that Soft Skills are, in fact, improved after half-semester but this is not the sole product of the mentioned course.
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