FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior / The aim of this work was to study the electrochemical behavior of antifungal ketoconazole on polished Silver Solid Amalgam Electrode (p-AgSAE).The study began with the evaluation of the best electrolyte for ketoconazole (KC) electrochemical reduction and the BrittonâRobinson buffer solution at pH 12 was selected as the best support electrolyte. In the following, with a constant ketoconazole concentration (1.0x10-5 mol L-1) the square wave voltammetric parameters were optimized for the p-AgSAE. The best experimental responses were achieved with 100 s-1 frequency, 25 mV of amplitude and 2 mV of scan increment. The results showed that ketoconazole is reduced in a quasi-reversible process, with one reduction peak at -1.50 V vs. Ag/AgCl/Cl- reference system. After optimized the SWV parameters, the analytical studies were developed in accord to ANVISA for validation the methodology. Linearity range, detection and quantification limits, precision, robustness and accuracy were evaluated. An analytical curve was constructed, that presented a linear region to 4.97x10-7 a 4.30x10-6 mol L-1 with a correlation coefficient to 0.9989. The detection limits for the concentration range were determined as 63.4 μg L-1 while the quantification limits were to 211.5 μg L-1. Studies of accuracy of the methodology were made in different formulations: tablet, cream and shampoo. The values obtained were to 100.8% for the electrolyte, 91% for the tablet, 104% for the cream and 103% for the shampoo. The Relative Standard Deviation (RSD) for the accuracy was less than 5.0%. Quantum chemical calculations were also made with the aim of studying the electronic characteristics of the molecule, and predicting which region of the molecule occurs a electrochemical reduction. It was investigated the distribution of charge on the molecule and the molecular orbital (HOMO and LUMO), which are possible sites of oxidation and reduction, respectively. The LUMO was located on the imidazole ring. In the sequence of the mechanistic elucidation, it was made an exhaustive electrolysis (E = -1,8V during six hours) with monitoring by UV-Vis, being used in the studies that identify the products, the technique of nuclear magnetic resonance espectroscopy, NMR H1. In accord to the study, the reduction of KC occur between the C-N bond on the imidazole ring. / No presente trabalho foi investigado o comportamento eletroquÃmico do antifÃngico Cetoconazol (CTZ) sobre o Eletrodo SÃlido de AmÃlgama de Prata (p-AgSAE). A otimizaÃÃo das condiÃÃes de reduÃÃo foi obtida por voltametria de onda quadrada (VOQ), onde foram analisadas as condiÃÃes mais adequadas para a realizaÃÃo dos experimentos. O meio de trabalho escolhido foi TampÃo BR 0,04 mol L-1. Foi avaliada a influÃncia do pH, onde o valor escolhido para estudar a reduÃÃo do analito foi 12. Os parÃmetros da VOQ otimizados foram frequÃncia (100 s-1), amplitude (25 mV) e incremento de potencial (2 mV). De acordo com os resultados, foi observado que o CTZ sofre um processo de reduÃÃo em -1,5 V vs. Ag/AgCl/Cl-. A concentraÃÃo de CTZ utilizada nos estudos de otimizaÃÃo foi de 1,0x10-5 mol L-1. ApÃs estabelecimento dos parÃmetros experimentais, foram estudadas as figuras de mÃrito especificadas pela ANVISA para validaÃÃo de mÃtodos analÃticos na anÃlise de fÃrmacos. Assim, foram avaliados regiÃo de linearidade (4,97x10-7 a 4,30x10-6 mol L-1 com R = 0,9993), limites de detecÃÃo(1,19x10-7 mol L-1 - 63,4 μg L-1) e de quantificaÃÃo (3,98x10-7 mol L-1 - 211,5 μg L-1), precisÃo e robustez. Os estudos de exatidÃo da metodologia foram feitos em diferentes produtos comerciais: comprimido, creme e xampu. Para fins de comparaÃÃo e avaliaÃÃo de possÃvel influÃncia do meio eletroquÃmico na resposta, foi feito o estudo de exatidÃo utilizando curvas de recuperaÃÃo para o eletrÃlito de suporte, onde o valor da taxa de exatidÃo foi de 100,1%. Assim, os valores das taxas de exatidÃo para as amostras foram de 91% para a amostra de comprimido, 104% para a amostra de creme e 103% para a amostra de xampu. Os valores de RSD para as amostras foram inferiores a 5%. CÃlculos quÃmico-quÃnticos tambÃm foram feitos com o objetivo de estudar as caracterÃsticas eletrÃnicas da molÃcula, e prever qual regiÃo tem maior probabilidade de sofrer a reduÃÃo. De fato, foram investigadas as distribuiÃÃes de carga na molÃcula, bem como os orbitais de fronteira (HOMO e LUMO), que sÃo possÃveis sÃtios de oxidaÃÃo e reduÃÃo, respectivamente. O LUMO foi localizado sobre o anel imidazÃlico. Na sequÃncia da elucidaÃÃo mecanÃstica, foi feita uma eletrÃlise exaustiva (E = -1,8V durante seis horas) com acompanhamento por espectroscopia UVVis, sendo utilizada nos estudos de identificaÃÃo do produto a tÃcnica de espectroscopia de ressonÃncia magnÃtica nuclear, RMN H1. Com base neste estudo, foi constatado que o CTZ sofreu uma reduÃÃo na dupla ligaÃÃo entre C-N do anel imidazÃlico da molÃcula de CTZ.

Οι κατανεμημένοι αλγόριθμοι δρομολόγησης για switches βασισμένα σε κελιά (=πακέτα σταθερού μεγέθους - π.χ. ΑΤΜ) που χρησιμοποιούν την αρχιτεκτονική Virtual Output Queueing έχουν οδηγήσει στη κατασκευή δρομολογητών υψηλών επιδόσεων. Στην παρούσα διπλωματική παρουσιάζουμε μια νέα ιδέα για την κατασκευή τέτοιων αλγορίθμων που λέγεται "αμοιβαία προτεραιότητα". Οι αλγόριθμοι της οικογένειας αυτής, που λέγεται οικογένεια "MPE", πετυχαίνουν βέλτιστη εγγύηση εξυπηρέτησης για κάθε ουρά εισόδου (καθυστέρηση το πολύ N κύκλων για switch ΝχΝ). Επίσης όσον αφορά τη μέση καθυστέρηση των πακέτων , ξεπερνούν σε απόδοση όλους τους γνωστούς αλγορίθμους. Οι βελτιώσεις που επιτυγχάνονται είναι αρκετά σημαντικές (π.χ. μέχρι και 78% μικρότερη καθυστέρηση πακέτων σε σύγκριση με τον καλύτερο υπάρχοντα αλγόριθμο, για μια επανάληψη). / Distributed scheduling algorithms for cell-based (e.g. ATM) Virtual Output Queuing (VOQ) switches have led to high performance schedulers. In this thesis we introduce a new concept in making such algorithms called "mutual priority" . Algorithms of this family , called "MPE" , achieve optimal service guarantee (N in a NxN switch) and lead to packet delays that outperform all existing algorithms. The improvements achieved are quite significant (i.e. up to 78% less packet delay compared to the best existing algorithm for a single iteration).