Efforts to reduce vehicle weight and improve crash performance have resulted in increased application of advanced high strength steels (AHSS) and a recent focus on the weldability of these alloys. Resistance spot welding (RSW) is the primary sheet metal welding process in the manufacture of automotive assemblies. Integration of AHSS into the automotive architecture has brought renewed challenges for achieving acceptable welds. The varying alloying content and processing techniques has further complicated this initiative. The current study examines resistance spot welding of high strength and advance high strength steels including high strength low alloy (HSLA), dual phase (DP) and a ferritic-bainitic steel (590R). The mechanical properties and microstructure of these RSW welded steel alloys are detailed. Furthermore a relationship between chemistries and hardness is produced. The effect of strain rate on the joint strength and failure mode is also an important consideration in the design of welded structures. Current literature, however, does not explain the effects of weld microstructure and there are no comprehensive comparisons of steels. This work details the relationship between the joint microstructure and impact performance of spot welded AHSS. Quasi-static and impact tests were conducted using a universal tensile tester and an instrumented drop tower, respectively. Results for elongation, failure load and energy absorption for each material are presented. Failure modes are detailed by observing weld fracture surfaces. In addition, cross-sections of partially fractured weldments were examined to detail fracture paths during static loading. Correlations between the fracture path and mechanical properties are developed using observed microstructures in the fusion zone and heat-affected-zone. Friction stir spot welding (FSSW) has proven to be a potential candidate for spot welding AHSS. A comparative study of RSW and FSSW on spot welding AHSS has also been completed. The objective of this work is to compare the microstructure and mechanical properties of Zn-coated DP600 AHSS (1.2mm thick) spot welds conducted using both processes. This was accomplished by examining the metallurgical cross-sections and local hardnesses of various spot weld regions. High speed data acquisition was also used to monitor process parameters and attain energy outputs for each process.

Τα κριτήρια σχεδιασμού στις σύγχρονες κατασκευές και κυρίως στην αεροναυπηγική και ναυπηγική βιομηχανία, στοχεύουν στην παραγωγή δομικών στοιχείων με μειωμένο βάρος και χαμηλότερο κόστος, ενώ ταυτόχρονα, απαιτείται να παρουσιάζουν υψηλότερες επιδόσεις και ικανοποιητική δομική ασφάλεια. Οι στόχοι αυτοί έχουν διαμορφώσει μια σχεδιαστική τάση η οποία οδηγεί στην αντικατάσταση των ‘παραδοσιακών’ διαφορικών δομών (differential structures) με ‘σύγχρονες’ ολοκληρωμένες δομές (integral structures). Η τάση αυτή βρίσκει εφαρμογή κατά κύριο λόγο στην αεροναυπηγική, όπου η μείωση του βάρους χωρίς υποβάθμιση της ασφαλούς λειτουργίας αποτελεί βασικό και μόνιμο στόχο. Η αυξημένη παραγωγή δομικών στοιχείων ολοκληρωμένων δομών έχει οδηγήσει σε συνεχή αύξηση της εφαρμογής διεργασιών συνένωσης με έμφαση στις προηγμένες διεργασίες συγκόλλησης. Οι διεργασίας συγκόλλησης οι οποίες, λόγω των πλεονεκτημάτων τους, βρίσκονται στην αιχμή της τεχνολογίας είναι η Συγκόλληση με Τριβή και Ανάμιξη (Friction Stir Welding – FSW) και η Συγκόλληση με Ακτίνα Λέιζερ (Laser Beam Welding – LBW). Η εφαρμογή συγκολλήσεων στην παραγωγή ολοκληρωμένων δομών έχει πολλά τεχνολογικά πλεονεκτήματα έναντι των άλλων τύπων σύνδεσης, ωστόσο, συνοδεύονται από την ανάπτυξη Παραμενουσών Τάσεων και στρεβλώσεων στο τελικό προϊόν, κάτι το οποίο, ανάλογα με την εφαρμογή, μπορεί να προκαλέσει σημαντικά προβλήματα. Συγκεκριμένα, οι στρεβλώσεις επηρεάζουν τη λειτουργικότητα του δομικού στοιχείου, αφού μεταβάλλουν την γεωμετρία του, ενώ οι παραμένουσες τάσεις, αναπροσαρμόζοντας το εσωτερικό εντατικό πεδίο, επιδρούν στη δομική τους ακεραιότητα. Όπως είναι γνωστό με κατάλληλη επιλογή των παραμέτρων της διεργασίας (π.χ. ταχύτητα συγκόλλησης, ισχύς κτλ) μπορεί να επιτευχθεί μείωση των αναπτυσσόμενων παραμενουσών τάσεων και στρεβλώσεων. Επίσης, τα τελευταία χρόνια έχει αποδειχθεί ότι η προσομοίωση μιας διεργασίας συγκόλλησης μπορεί να βοηθήσει σημαντικά στην επιλογή του βέλτιστου συνδυασμού των παραμέτρων της. Για το λόγο αυτό, μεγάλο μέρος της ερευνητικής δραστηριότητας στην περιοχή των προηγμένων διεργασιών συγκόλλησης έχει στραφεί προς την ανάπτυξη αξιόπιστων μεθοδολογιών προσομοίωσης, οι οποίες με δεδομένο (input data) τις παραμέτρους της διεργασίας μπορούν να δώσουν σαν αποτέλεσμα (output data) κρίσιμες απαντήσεις όσον αφορά στις τεχνολογικές ιδιότητες της συγκόλλησης. Βάσει των ανωτέρω, σκοπός της παρούσης διατριβής είναι η ανάπτυξη ολοκληρωμένων μεθόδων θερμομηχανικής προσομοίωσης των προηγμένων διεργασιών συγκόλλησης FSW και LBW με κύριο στόχο την πρόβλεψη των παραμενουσών τάσεων και των στρεβλώσεων καθώς και τη μελέτη της επίδρασης τους στη δομική ακεραιότητα των παραγόμενων δομικών στοιχείων. Ένα από τα σημαντικότερα και ίσως το κρισιμότερο στάδιο κατά την προσομοίωση μιας θερμομηχανικής διεργασίας είναι η εξομοίωση της θερμικής πηγής και ο υπολογισμός του θερμικού φορτίου, γιατί μια εσφαλμένη εκτίμηση του θερμικού φορτίου προκαλεί λανθασμένη πρόβλεψη της θερμοκρασιακής κατανομής και κατά συνέπεια εισάγει σφάλματα στον υπολογισμό των παραμενουσών τάσεων και των στρεβλώσεων. Στη βάση αυτή, τόσο για την περίπτωση της FSW όσο και για την LBW αναπτύχθηκαν μεθοδολογίες για τον προσδιορισμό των θερμικών πηγών τους και συνοδεύτηκαν από θερμικά μοντέλα για την πρόβλεψη του θερμοκρασιακού ιστορικού. Ακολούθως, το θερμοκρασιακό ιστορικό ασκείται υπό τη μορφή εξωτερικού φορτίου σε ένα θερμομηχανικό μοντέλο από όπου υπολογίζονται οι παραμένουσες τάσεις και οι στρεβλώσεις της διεργασίας. Τέλος, η εσωτερική εντατική κατάσταση του συγκολλημένου δομικού στοιχείου συνυπολογίζεται στο εντατικό πεδίο λόγω της φόρτισης λειτουργίας της κατασκευής και γίνεται πρόβλεψη των συντελεστών έντασης τάσης (Stress Intensity Factors - SIFs ) έτσι ώστε να εκτιμηθεί η επίδρασης της συγκόλλησης στη δομική ακεραιότητα. Τόσο το θερμομηχανικό όσο και το θραυστομηχανικό μοντέλο μπορούν να προσαρμοσθούν σε πολλούς διαφορετικούς τύπους σύνδεσης και ρηγμάτωσης, αντίστοιχα. / The design criteria in modern structures aim to the production of components with reduced weight and low cost, as well as, with higher performance and increased safety. The above goals lead to a tendency of replacing traditional differential structures with more modern integral structure, mainly in aeronautic sector where the weight and cost reduction, without decrease of safety, comprises the main target of the current research effort. The production of integral structures requires the adaptation of existing forming processes as well as the development and optimization of advanced welding processes. The most promising welding processes in aeronautics and maritime industries currently are the Friction Stir Welding–FSW and Laser Beam Welding-LBW. Despite of the many technological advantages of FSW and LBW process, their application in the production of integral structures leads to the development of Residual Stress (RS) and distortion fields which can cause significant problems. Specifically, distortions can effect on the components assembly, while, RS affect the structural integrity. However, an appropriate selection of process parameters can significantly reduce the RS and distortions levels. The usual way to optimize process parameters is experimental trial and error approach; recently, process simulation has been proven efficient, too. The present work aims to the development of efficient methodologies for the thermomechanical simulation of FSW and LBW processes in order to predict temperature history, as wells as RS and distortion fields. Consequently, the RS field is used for the determination of the welding effects on the structural integrity of the welded component. Generally, the reliability of a simulation methodology of any thermo-mechanical process, such as welding, is seriously affected by many parameters; two of them are very base, namely, the accurate determination of the heat input introduced to the material (thermal load) and the accurate representation of thermal and mechanical boundary conditions. As the boundary conditions determined by the welder and it is usually easy to transfer in a numerical model, one of the most difficult simulation issues is the appropriate determination of the heat input which will lead to an accurate prediction of the material temperature history. For this reason, one of the main objectives of the present work is to develop methodologies for the accurate thermal load calculation in both FSW and LBW processes. After the validation of the developed methodologies with respect to experimental measurements, the defined heat sources are used in global thermal models in order to predict the temperature histories which, thereinafter, are introduced in the thermo-mechanical models to predict the developed RS and distortion fields. Finally, the structural integrity of the welded component, under the effect of both RS field and service loading is studied; different possible ‘fracture scenarios’ are investigated based on the Stress Intensity Factor concept and the Elastic Fracture Mechanics principles.

O desenvolvimento e utilização de novos materiais, mais leves e com propriedades mecânicas superiores aos atuais, se mostram extremamente importantes devido à redução de peso e consequentemente redução na emissão de gases poluentes que poderiam gerar. As ligas de Fe-Mn-C com elevados teores de Mn (20-30%) representam um desenvolvimento muito recente de aços austeníticos, que, através dos seus mecanismos diferenciados de deformação reúnem elevada resistência mecânica com grande ductilidade. Essa nova classe de materiais estruturais possibilita uma efetiva redução de custos na produção através do reduzido tempo de processamento (sem a necessidade de tratamentos térmicos especiais e de processamentos termomecânicos controlados). A soldagem é, atualmente, o mais importante processo de união de metais usado no setor industrial. Dentro da variada gama de processos de soldagem existentes, a soldagem por fricção e mistura mecânica (SFMM, em inglês: Friction Stir Welding - FSW) se destaca por ser um processo de união no estado sólido que apresenta uma série de vantagens sobre as tecnologias convencionais de soldagem por fusão. Do ponto de vista metalúrgico, uma das suas principais vantagens se manifesta justamente na junção de materiais dissimilares, visto que o grau de mistura de composições e as transformações de fases entre materiais incompatíveis podem ser minimizados. Outra vantagem é que há um refino de grão no cordão de solda comparado com a microestrutura fundida que se forma nos processos convencionais. Este trabalho teve como objetivo produzir em escala laboratorial os aços de alta liga ao manganês com efeito TRIP, avaliar o impacto da velocidade de rotação da ferramenta na soldagem por fricção e mistura mecânica e avaliar a microestrutura e propriedades mecânicas das juntas soldadas. A microestrutura das juntas soldadas caracterizou-se pela presença apenas da zona de mistura e do metal base, além da formação de \'anéis de cebola\' na zona de mistura, esta não mostrou sinais de transformação martensítica induzida por deformação e sofreu recristalização dinâmica para todas as velocidades de rotação investigadas com a formação de grãos refinados e com morfologia equiaxial. Os corpos de tração fraturaram todos nos metais de base, mostrando que as propriedades mecânicas da zona de mistura foram superiores à do metal base e que a variação de aporte térmico alcançada com a velocidade de rotação da ferramenta não comprometeu a qualidade das juntas soldadas. / The development and application of new light materials with superior mechanical properties is extremely important to weight reduction in vehicles and consequently reduction of greenhouse gases emission. The Fe-Mn-C steels with high Mn (20-30%) are a recent development of austenitic steels, which, due to their different mechanisms of deformation, possesses high strength and high ductility as well. In addition, this new type of structural steel allows an effective reduction of manufacturing costs due to its reduced processing time (it does not require special heat treatments and controlled thermo mechanical processing). Welding has been one of the most important processes for joining metals. Among the available welding processes, friction stir welding (FSW) is notable for being a solid state process with great advantages over the conventional welding methods. In the mettalurgical point of view, welding dissimilar materials is a significant advantage of FSW over the other process. The main reason is the reduction of mixture of material and phase transformations between the incompatible materials in the weld. Moreover, grain refinement is another advantage from the process. The present study aimed to produce laboratorial scale high Mn steels with TRIP effect, investigate the impact of tool speed ont the microstructure and mechanical properties of friction stir welded joints. The microstructure of the welded joints exhibited only the stirred zone (SZ) and the base material (BM), besides the presence of ´onion rings´ within the stirred zone. The SZ exhibited no signs of martensite suggesting that dynamic recrystallization have occurred for all the speed tested. Moreover, the grains in the SZ had equiaxial morphology and were significantly refined. The fracture of the tensile specimens occurred in the base material, bringing to light that the welding process was beneficial to the mechanical properties. Furthermore, the variation of heat input achieved with the speed did not compromise the quality of welded joints.

Uma fase polimérica inédita de polidimetilsiloxano/carvão ativado (PDMS-ACB) é proposta como fase extratora para extração por sorção em barras de agitação (SBSE). A barra de PDMS-ACB foi desenvolvida no laboratório usando um molde de teflon simples, demonstrando estabilidade e resistência aos solventes orgânicos. Utilizando uma única barra de PDMS-ACB mais de 150 extrações foram realizadas sem qualquer dano. A barra de SBSE contém aproximadamente 100 µL de revestimento polimérico, 2,36 mm de diâmetro e 2,2 cm de comprimento. A barra PDMS-ACB foi aplicada na extração de seis pesticidas (ametrina, atrazina, bifentrina, carbofurano, metribuzim e tebutiurom), com propriedades predominantemente polares, comumente aplicados em plantações de cana-de-açúcar. A barra PDMS-ACB foi utilizada na determinação de pesticidas em garapa através de cromatografia gasosa hifenada à espectrometria de massa (GC-MS). O planejamento experimental foi empregado na etapa de otimização da extração SBSE, um planejamento fatorial fracionado avaliou a influência dos principais parâmetros envolvidos. Posteriormente, o planejamento composto central (CCD) com conformação estrela foi explorado para otimizar os fatores significativos na extração. Apenas 200 µL de acetato de etila foram utilizados como solvente na dessorção líquida (LD). Para os compostos avaliados, o método apresentou limite de quantificação (LOQ) no intervalo de 0,5 - 40 µg L-1, as recuperações variaram entre 0,18 - 49,50 % e a precisão intra-dia variou de 0,072 - 8,40 %. Concluída a etapa de validação, o método foi aplicado em amostras reais de garapa disponíveis comercialmente em São Carlos-SP. / A novel polydimethylsiloxane/activated carbon (PDMS-ACB) is proposed as new polymeric phases for stir bar sorptive extraction (SBSE). The PDMS-ACB was developed in lab using simple teflon\'s mold, demonstrating remarkable stability and resistance to organic solvents, over 150 extractions without any damage. SBSE bar contained 100 µL of polymeric coating, a diameter of 2.36 mm and a length of 2.2 cm. It was applied to the determination of pesticides (ametryn, atrazine, bifenthrin, carbofuran, metribuzine and tebuthiuron) having predominantly polar properties, applied in sugarcane crops. PDMS-ACB was employed in the determination of pesticides in sugarcane juice using gas chromatography coupled to mass spectrometry (GC-MS). Experimental design was employed in the optimization step, a fractional factorial evaluated the main parameters involved in the extraction procedure. Afterwards, central composite design (CCD) was exploited to optimize the significant factors on the extraction. About 200 µL of ethyl acetate were employed as solvent in the liquid desorption (LD). The method presented limit of quantification (LOQ) from 0.5 to 40 µg L-1, recoveries varied 0.18 - 49.50% and precision intra-day 0.072 - 8.40%. Hence, the method was applied to the analysis of real sugarcane juice samples commercially available in São Carlos-SP.

Submitted by Caroline Periotto (carol@ufscar.br) on 2016-09-26T15:05:24Z No. of bitstreams: 1 DissGTV.pdf: 1872903 bytes, checksum: 8df6b2f211cfc4236fc723147c24d9bf (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-26T20:50:51Z (GMT) No. of bitstreams: 1 DissGTV.pdf: 1872903 bytes, checksum: 8df6b2f211cfc4236fc723147c24d9bf (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-26T20:50:56Z (GMT) No. of bitstreams: 1 DissGTV.pdf: 1872903 bytes, checksum: 8df6b2f211cfc4236fc723147c24d9bf (MD5) / Made available in DSpace on 2016-09-26T20:51:03Z (GMT). No. of bitstreams: 1 DissGTV.pdf: 1872903 bytes, checksum: 8df6b2f211cfc4236fc723147c24d9bf (MD5) Previous issue date: 2015-07-03 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Due to the current growth in the fossil fuels consumption, there is a great concern about the increase in pollutant emissions. In order to reduce these emissions, research indicates that the decrease in vehicle weight can be one of the solutions to reduce these gas emissions. One possible way to reduce the car weight is the replacement of parts that uses high density metals by Magnesium alloys. The major problem with this replacement is the lack of ductility that this material has at room temperature, being necessary to heat the plates before the conformation. This heating process has a high production costs and it is unfeasible to use in the automotive industry today. In view of this problem, this work aims to study this lack of conformity to room temperature using a microstructure modification technique located in the regions of conformation. The technic used was Friction Stir Processing (FSP) at high speed. This processing is similar to Friction Stir Welding (FSW), but without joining materials. The FSP is just a localized microstructural modification. The analysis performed in this study after processing at 1, 7 and 10 m/min show that the microstructure and mechanical properties undergoes various changes at for every processing speed output different. The results showed that the material after processing improves the ductility at room temperature as grain size decreases. / Com o atual crescimento do consumo de combustíveis fosseis, existe uma grande preocupação com o aumento de emissões de gases poluente. Para redução dessas emissões, pesquisas apontam que a diminuição do peso de veículos pode ser uma das soluções para reduzir as emissões de gases poluentes pelo aumento da eficiência energética. Uma forma possível de diminuir o peso de automóveis é pela substituição de partes que utilizam metais com alta densidade por ligas de Magnésio. O grande problema desta substituição é a falta de dutilidade que este material possui a temperatura ambiente, sendo necessário aquecer as chapas antes da conformação. Atualmente este processo de aquecimento gera um alto custo de produção dificultando sua utilização na indústria automotiva. Tendo em vista este problema, o presente trabalho tem como objetivo entender esta dificuldade na conformação a temperatura ambiente e propor uma solução utilizando uma técnica de modificação microestrutural localizada nas regiões de conformação. Esta técnica é o Processamento por Fricção e Mistura (FSP – Friction Stir Processing) à altas velocidade. Este processamento é semelhante ao de Soldagem por Fricção e Mistura (FSW – Friction Stir Welding), mas sem a formação de uma região de união entre materiais. O FSP é apenas uma modificação microestrutural localizada. As análises realizadas neste estudo após o processamento à 1, 7 e 10m/min apontam que a microestrutura e as propriedades mecânicas sofrem variações diferentes a cada velocidade de processamento. Os resultados mostraram que o material obteve uma melhora na dutilidade à temperatura ambiente devido à diminuição do tamanho de grão.

A monitorização terapêutica tem sido descrita como um recurso clínico valioso, na individualização do regime de dosagem, de acordo com a concentração do fármaco em amostras de plasma ou soro. O objetivo da monitorização terapêutica é assegurar a eficácia clínica e minimizar os efeitos adversos dos fármacos prescritos na clínica. A química analítica moderna tem sido direcionada para a simplificação dos métodos através da miniaturização dos sistemas analíticos, minimização do consumo de solvente orgânico e do volume da amostra. Neste contexto, metodologias analíticas utilizando as técnicas de microextração, extração sortiva em barra de agitação (SBSE) e microextração em sorvente empacotado (MEPS), juntamente com a eletroforese capilar em solução não-aquosa (NACE) foram desenvolvidas para fins monitorização terapêutica de antidepressivos inibidores seletivos da recaptação de serotonina (ISRSs: fluoxetina, sertralina, paroxetina e citalopram) em amostras de plasma de pacientes em terapia com ISRSs. Inicialmente foram padronizadas as condições eletroforéticas com detecção espectrofotométrica (UV) para análise simultânea dos ISRSs em amostras de plasma. Dentre as condições avaliadas (diferentes soluções de eletrólitos em meio aquoso e não aquoso, cromatografia eletrocinética micelar e NACE), a técnica NACE-UV foi a única que apresentou resolução dos fármacos adequada. Em seguida, otimizou-se as variáveis inerentes das técnicas de microextração (SBSE e MEPS), visando minimizar o tempo de análise e aumento da sensibilidade analítica. Para o método SBSE/NACE, as variáveis tempo e temperatura de extração, pH da amostra biológica e processo de dessorção foram otimizadas, já para o método MEPS/NACE, as variáveis, pH da amostra biológica, volume da amostra e número dos ciclos aspirar/dispensar foram otimizadas. A validação analítica foi realizada segundo as normas preconizadas pela Agência Nacional de Vigilância Sanitária (ANVISA), com adição de padrão de padrão interno às amostras de plasma enriquecidas com os antidepressivos em diferentes concentrações plasmáticas que contemplam o intervalo terapêutico dos ISRSs. Para avaliar a aplicabilidade das metodologias padronizadas, amostras de plasma de pacientes em terapia com os ISRSs foram analisadas. Os métodos padronizados (SBSE/NACE e MEPS/NACE) foram comparados ao método de referência (LLE/NACE), utilizando a extração líquido-líquido. As técnicas de microextração, quando comparadas à LLE, apresentaram as seguintes vantagens: a reutilização das fases extratoras, procedimentos de extração com reduzido número de etapas, menores volumes de amostras biológicas e de solventes orgânicos. Segundo os parâmetros de validação avaliados, os métodos SBSE/NACE e MEPS/NACE padronizados podem ser empregados nas análises dos antidepressivos (ISRSs) em amostras de plasma, para fins de monitorização terapêutica. / Therapeutic monitoring allows individualization of the dose regimen and has been indicated for the monitoring of well-established therapeutic intervals. In psychiatric disorders, most of the patients require that the plasmatic concentrations to be within a fixed range, so the disorders are kept under control and the adverse effects are acceptable. The aim of the therapeutic monitoring is ensure clinical effectiveness and minimization of adverse effects of drugs prescribed at the clinic. New trends in analytical chemistry have been directed towards simplification and miniaturization of analytical systems, and minimization of organic solvents and sample volume. In this work, analytical methodologies using microextraction techniques, such as stir bar sorptive extraction (SBSE) and microextraction by packed sorbent (MEPS), in conjunction with capillary electrophoresis in a nonaqueous background electrolyte (NACE) were developed for therapeutic drug monitoring of selective serotonin reuptake inhibitors (SSRIs: fluoxetine, sertraline, paroxetine and citalopram) in plasma sample of patients in therapy with SSRIs. First, the optimization of electrophoretic separation of the SSRIs was carried out to obtain simultaneous analysis of all antidepressants. Among the conditions evaluated (different background electrolytes in aqueous and nonaqueous medium, micellar electrokinetic capillary chromatography, and NACE), NACE-UV gave the best results. In the sequence, the optimization of the inherent variables of microextraction techniques (SBSE and MEPS)aiming analyses time minimization and increase of analytical sensibilitywas carried out. For SBSE/NACE methodology development the variables such as time of extraction, temperature of extraction, and matrix pH were optimized. For MEPS/NACE methodology the variables matrix pH and the volume of draw-eject cycles were optimized. Analytical validation was carried out in agreement with the norms of National Health Surveillance Agency (ANVISA) for both of the proposed methods, in different plasmatic concentrations, which completed the therapeutic interval. The developed methods (SBSE/NACE e MEPS/NACE) were compared to the reference method, using liquid-liquid extraction (LLE/NACE). Microextraction techniques, compared to LLE, gave the following advantages: reutilization of the extraction phase, fewer numbers of steps for extraction, reduction of sample volume, and less consumption of organic solvents. According to the evaluated validation parameters, the standardized methods SBSE/NACE and MEPS/NACE can be used in the analyses of antidepressants (SSRIs) in plasma sample for therapeutic drug monitoring purposes.

Neste trabalho, os anticorpos policlonais e monoclonais anti-fluoxetina foram produzidos em coelhos e camundongos, respectivamente, por imunização com o conjugado fluoxetina-soroalbumina bovina. Os anticorpos obtidos foram caracterizados em função da especificidade contra o fármaco por ELISA (enzyme linked immunosorbent assay) e posteriormente, purificados por afinidade em coluna fluoxetina-agarose labmade. Os anticorpos purificados foram imobilizados covalentemente na superfície vítrea das barras SBSE (extração sortiva em barra de agitação) labmade. Após a derivatização das barras com 3-aminopropiltrietoxisilano, dois métodos distintos de acoplamento dos anticorpos às barras SBSE foram avaliados: ativação com glutaraldeído e succinilação seguida de ativação via éster N-hidroxisuccinimida (NHS). A funcionalização das barras SBSE foi comprovada através da imobilização de enzima peroxidase (HRP) em lugar do anticorpo e posterior ensaio enzimático com as barras. Várias barras SBSE com diferentes áreas (1,2; 2,4; e 4,0 cm2) foram preparadas, dentre as quais, as com maior área imunosorvente apresentaram maiores taxas de recuperação do fármaco. A avaliação da morfologia da superfície da barra SBSE imunosorvente foi realizada através de Microscopia Eletrônica de Varredura (MEV). As variáveis do processo SBSE de imunoafinidade foram otimizadas para estabelecer o equilíbrio de sorção antígeno-anticorpo em um menor tempo de análise e obtenção de limite de quantificação compatível com o intervalo terapêutico do fármaco. As capacidades adsortivas das barras imunosorventes foram de 1,2 e 8 microgramas por cm2 para anticorpos policlonais e monoclonais, respectivamente. Os imunosorventes desenvolvidos apresentaram reatividade-cruzada apenas com norfluoxetina (metabólito ativo de fluoxetina). As barras imunosorventes foram reutilizadas aproximadamente 30 vezes, sem perda significativa da eficiência das extrações. Baseados nos parâmetros de validação analítica avaliados, os métodos de SBSE/LC-FD de imunoafinidade desenvolvidos são adequados para a determinação de fluoxetina em amostras de plasma de pacientes em terapia com o fármaco, para fins de monitorização terapêutica. Por conseguinte, esses métodos foram aplicados com êxito para análises de amostras de plasma de pacientes idosos em terapia com Prozac®. Neste trabalho, o método MEPS (microextração em sorvente empacotado)/LC-UV também foi desenvolvido e validado para análise simultânea de sertralina, paroxetina, citalopram, fluoxetina e mirtazapina em amostras de plasma para fins de monitorização terapêutica. As variáveis do processo MEPS foram otimizadas (pH e volume da amostra, força iônica, volume dos ciclos aspirar-dispensar e condições de dessorção) para estabelecer o equilíbrio de sorção em menor tempo de análise e obter sensibilidade analítica adequada para a determinação dos antidepressivos no intervalo terapêutico. O método MEPS/LC-UV desenvolvido permitiu integração da dessorção dos analitos e injeção da amostra no sistema cromatográfico (LC-UV) em uma única etapa, usando a microsseringa de extração MEPS. A fase extratora MEPS, M1 (C8/SCX), foi reutilizada mais de 50 vezes com perda mínima da eficiência da extração, comprovando a robustez do material sorvente. Segundo os parâmetros de validação analítica avaliados, o método MEPS/LC-UV desenvolvido é adequado para a determinação de antidepressivos em amostras de plasma para fins de monitorização terapêutica. / In this work, polyclonal and monoclonal anti-fluoxetine antibodies were developed in rabbits and mice by immunization with fluoxetine-bovine albumin conjugate, respectively. The developed antibodies were characterized on the basis of the specificity against the drug by ELISA (enzyme linked immunosorbent assay) and, subsequently they were purified by labmade fluoxetine-agarose affinity column. The purified antibodies were covalently immobilized onto the glass surface of labmade SBSE (stir bar sorptive extraction) bars. After derivatization of the bars with 3-aminopropyltriethoxysilane, two distinct methods were evaluated for the antibodies coupling to the SBSE bars: activation with glutaraldehyde and succinylation activation via ester N-hydroxysuccinimide (NHS). The functionalization of SBSE bars was confirmed by the immobilization of peroxidase (HRP) instead of the antibody and, subsequent enzymatic assay with the bars. Several SBSE bars with different areas (1.2, 2.4, and 4.0 cm2) were prepared, among of them the largest immunosorbent area showed higher recovery rates of the drug. The evaluation of surface morphology of the SBSE immunosorbent bar was performed using scanning electron microscopy (SEM). The SBSE immunoaffinity variables were optimized to establish sorption equilibrium of antigen-antibody in a short time analysis and to obtain the limit of quantification compatible with the therapeutic range of the drug. The adsorptive capacities of the immunosorbent bars were 1.2 and 8 micrograms per cm2 for polyclonal and monoclonal antibodies, respectively. The developed immunosorbents showed cross-reactivity only with norfluoxetine (active metabolite of fluoxetine). The immunosorbent bars were reused approximately 30 times without significant loss of the extraction efficiency. Based on evaluated analytical validation parameters, the developed immunoaffinity SBSE/LC-FD methods are suitable for the determination of fluoxetine in plasma samples from patients on therapy with the antidepressant for therapeutic drug monitoring. Therefore, these methods were successfully applied for the analysis of plasma samples from elderly patients undergoing therapy with Prozac®. In this work, the method MEPS (microextraction by packed sorbent)/ LC-UV was also developed and validated for the simultaneous analysis of sertraline, paroxetine, citalopram, fluoxetine and mirtazapine in plasma samples for therapeutic drug monitoring. The MEPS process variables were optimized (pH, sample volume, ionic strength, draw-eject cycles volume and desorption conditions) to establish the sorption equilibrium in a short time analysis and to obtain adequate analytical sensitivity for determination of antidepressants within therapeutic range. The developed MEPS/LC-UV method allowed integration of the analytes desorption and sample injection in the chromatographic system (LC-UV) in a single step, using a MEPS extraction microsyringe. The MEPS extraction phase, M1 (C8/SCX) was reused over 50 times with minimum loss of extraction efficiency, proving the robustness of the sorbent material. According to the evaluated analytical validation parameters, the developed MEPS/LC-UV method is suitable for the determination of antidepressants in plasma samples for therapeutic drug monitoring.

A depressão em idosos é uma desordem persistente e recorrente, resultado do stress psicossocial ou efeito de doenças fisiológicas, que podem acarretar a desabilidade do indivíduo, aumento dos sintomas das doenças clínicas, na maior utilização dos serviços de saúde e altas taxas de suicídios.A monitorização terapêutica permite a ndividualização do regime de dosagem, assegurando a eficácia clínica e minimizando os efeitos adversos dos fármacos, prescritos na clínica. Os antidepressivos têm sido monitorados, pois, apresentam intervalos terapêuticos bem estabelecidos, ou seja, a maioria dos pacientes, que apresentam concentrações plasmáticas dentro deste intervalo fixo, tem as desordens psiquiátricas mantidas sob controle e efeitos adversos aceitáveis. Os antidepressivos tricíclicos (ADTs): imipramina, amitriptilina, nortriptilina e desipramina, embora eficazes e ainda muito utilizados, apresentam efeitos adversos, não desejáveis. Os antidepressivos, inibidores seletivos da recaptação de serotonina (SSRIs): citalopram, fluoxetina, paroxetina e sertralina, apresentam eficácia clínica comparável aos clássicos ADTs, mas destituídos dos efeitos adversos associados aos mesmos. Os métodos convencionais, empregados no tratamento de amostras biológicas, para análises de antidepressivos por técnicas cromatográficas, têm sido a extração líquido-líquido e extração em fase sólida. A microextração em fase sólida tem sido empregada em diferentes análises em fluidos biológicos, porém essa técnica apresenta certas limitações como, o número limitado de fases extratoras disponíveis no comércio que sejam adequadas para a análise de compostos não iônicos. A avaliação de novas fases extratoras, mais seletivas, estáveis e de baixo custo tem sido requerida para a análise de fármacos. O interesse no uso de poli(pirrol) (PPY), como fase extratora para SPME, está relacionado às diferentes interações dos fármacos (hidrofóbicas, -, com o grupo funcional polar, troca iônica, ácido-base) aos grupos multifuncionais deste polímero. Sua polimerização pode ser alcançada tanto por oxidação química, quanto por eletrodeposição em meio aquoso ou orgânico. O método eletroquímico apresenta algumas vantagens, tais como: o polímero ou mistura de polimeros podem ser revestidos diretamente em um metal, incorporação de diferentes grupos funcionais, entre outras, a polimerização pode ser eletroquimicamente controlada através da voltametria cíclica. Neste trabalho o poli(pirrol) (PPY) foi eletrodepositado em eletrodo de aço inox e empregado para a microextração em fase sólida dos antidepressivos: paroxetina, fluoxetina, mirtazapina, duloxetina, sertralina e citalopram. As variáveis da eletrodeposição, número de ciclos e contra-íon empregado no processo de eletrodeposição foram otimizadas. Assim como as variáveis SPME: tempo, temperatura, pH e volume de amostra, e tempo e solvente de dessorção; almejando maior sensibilidade para o método SPME-PPY/LC UV proposto. A extração sortiva em barra de agitação (SBSE), técnica recente de preparo de amostras, para a pré-concentração de compostos orgânicos presentes em amostras biológicas, baseia-se na extração estática, através do polímero polidimetilsiloxano (PDMS), no qual ocorre a dissolução (sorção) do analito. Neste trabalho, as técnicas SBSE e cromatografia líquida de alta eficiência com detecção UV (SBSE/LC UV) foram avaliadas para a análise simultânea de antidepressivos em amostras de plasma para fins de monitorização terapêutica. As condições cromatográficas de análise, assim como as variáveis SBSE de extração (tempo, temperatura, força iônica, pH da matriz) e tempo de dessorção, foram otimizadas, visando adequada sensibilidade analítica. A validação analítica foi realizada segundo normas da ANVISA, para ambos os métodos propostos, em diferentes concentrações plasmáticas, as quais contemplam o intervalo terapêutico. Segundo os parâmetros de validação avaliados, os métodos SBSE/LCUV e SPMEPPY/LCUV padronizados poderão ser empregados nas análises dos antidepressivos, para fins de monitorização terapêutica. / Depression in the elderly is a persistent and recurrent disorder resulting from psychosocial stress or physiological effect or disease. This condition can lead to disability, cognitive impairment, enhanced symptoms of medical illnesses, increased use of health care services and, increased of suicide rates. Therapeutic monitoring allows individualization of the dose regimen, ensuring clinical effectiveness and minimizing the adverse effects of drugs, prescribed at the clinic. Antidepressants have been monitored because they present well - established therapeutic intervals; in other words, most of the patients present plasmatic concentrations within this fixed range, so that their psychiatric disorders are kept under control and the adverse effects are acceptable. The tricyclic antidepressants (ADTs) imipramine, amitriptyline, nortryptiline, and desipramine, have adverse effects. The selective serotonin reuptake inhibitors (SSRIs) antidepressants citalopram, fluoxetine, paroxetine, and sertraline, are clinically effectiveness as the classic ADTs, but they do not lead to the adverse effects associated to the latter. The conventional methods employed in the treatment of biological samples for analysis of antidepressants by chromatographic techniques have been the liquid-liquid extraction (LLE) and solid phase extraction (SPE) techniques. Solid-phase microextraction (SPME) has been used in various analyses of biological fluids. However, this technique has limitations such as the small number of comemercially available extracting phases that are appropriate for the analysis of non-ionic compounds. Investigation of new extraction phases that are more selective and stable, as well as inexpensive, has been requested for drug analysis. The interest in the use of poly(pirrole) (PPY) as an extraction phase for SPME is related to the different interactions of the drugs (hydrophobic, - , with the polar functional group, ionic exchange and acid-base) with the multifunctional groups on this polymer. The PPY polymerization can be achieved by chemical oxidation or electropolymerization in aqueous solution or organic solvents. The electrochemical method has advantages such as, the polymer or a mixes of polymers can be directly deposited on a metal wire, different functional groups can be incorporated, polymerization can be electrochemically controlled by cyclic voltammetry. In this work poly(pyrrole) was electropolymerized on stainless steel electrodes and employed for the solid phase microextraction of the antidepressants paroxetine, fluoxetine, mirtazapine, duloxetine, sertraline, and citalopram. The electropolymerization variables, the number of cycles and counterion employed in the process were optimized, as well as the SPME variables, time, temperature, pH, sample volume, and desorption solvent; aiming at a better sensibility for the proposed method SPME-PPY/LC-UV. The stir bar sorptive extraction (SBSE), recently established technique for samples preparation, that targets the pre concentration of organic compounds present in biological samples. It is based on static extraction, through the polymeric polydimethylsiloxane (PDMS), where there is analyte dissolution (sorption). In this work, the SBSE technique and liquid chromatography with UV detector (SBSE/LC-UV) were evaluated for the simultaneous determination of antidepressants in plasma samples for therapeutic monitoring purposes. The cromatographic conditions, the SBSE extraction variables (time, temperature, ionic strength and matrix pH), and the dessorption time were optimized for appropriate analytical sensibility. The analytical validation was accomplished according to the norms of ANVISA for both of the proposed methods, in different plasmatic concentrations, which contemplate the therapeutic interval. According to the evaluated validation parameters, the standardized methods SBSE/LC-UV and SPME-PPY/LC-UV can be used in the analyses of antidepressants for therapeutic drug monitoring purposes.

A monitorização terapêutica permite a individualização do regime de dosagem, assegurando a eficácia clínica e minimizando os efeitos adversos dos fármacos, prescritos na clínica. Os antidepressivos têm sido monitorados, pois, apresentam intervalos terapêuticos bem estabelecidos, ou seja, a maioria dos pacientes, que apresentam concentrações plasmáticas dentro deste intervalo fixo, tem as desordens psiquiátricas mantidas sob controle e efeitos adversos aceitáveis. Os antidepressivos tricíclicos (ADTs): imipramina, amitriptilina, nortriptilina e desipramina, embora eficazes e ainda muito utilizados, apresentam efeitos adversos, não desejáveis. Os antidepressivos, inibidores seletivos da recaptação de serotonina (ISRSs): citalopram e sertralina, apresentam eficácia clínica comparável aos clássicos ADTs, mas destituídos dos efeitos adversos associados aos mesmos. Os métodos convencionais, empregados no tratamento de amostras biológicas, para análises de antidepressivos por técnicas cromatográficas, têm sido a extração líquido-líquido e extração em fase sólida. A extração sortiva em barra de agitação (SBSE), técnica recente de preparo de amostras para a préconcentração de compostos orgânicos presentes em amostras biológicas, baseiase na extração estática, através do polímero polidimetilsiloxano (PDMS), no qual ocorre a dissolução (sorção, partição) do analito. Neste trabalho, as técnicas SBSE e cromatografia líquida de alta eficiência foram avaliadas para a análise simultânea dos antidepressivos em amostras de plasma para fins de monitorização terapêutica. As condições cromatográficas de análise, assim como as variáveis SBSE de extração (tempo, temperatura, força iônica, pH da matriz) e tempo de dessorção, foram otimizadas, visando adequada sensibilidade analítica. A validação analítica foi realizada segundo normas da ANVISA, em diferentes concentrações plasmáticas, as quais contemplam o intervalo terapêutico. O método SBSE/HPLC padronizado apresentou linearidade na faixa de concentração plasmática de 20 a 1000 ng mL-1, precisão interensaio com coeficientes de variação menor que 14% e recuperação relativa de 83 a 110%. Segundo a validação analítica, a metodologia SBSE/HPLC apresentou linearidade, alta sensibilidade, seletividade e precisão analítica adequadas para a análise dos antidepressivos: imipramina, amitriptilina, nortriptilina, desipramina, citalopram e sertralina, em amostra de plasma, para fins de monitorização terapêutica. / Therapeutic drug monitoring allows individualization of drug dosage assuring its clinical efficacy and at the same time minimizing adverse effects of the drugs prescribed in clinics. The antidepressants have been monitored since they present a very well established therapeutic interval. In this sense, most of the patients whose plasmatic concentrations are ranged at that interval present psychiatric disorders under control and drug adverse effects at bearable levels. Despite tricyclic antidepressants (TCAs) such as imipramine, amitriptyline, nortriptyline and desipramine are highly efficient and widely used, they also present undesirable adverse effects. The antidepressants: citalopram and sertraline, which are selective serotonin reuptake inhibitors (SSRIs), present clinical efficacy comparable to the classic TACs, but with no adverse effects associated to the last ones. Liquid-liquid extraction (LLE) and solid phase extraction (SPE) have been usually employed in biological sample pre-treatment for chromatographic analysis. A new technique named sorptive stir bar extraction (SBSE) for sample pre-concentration of organic compounds from biological samples was recently proposed. This technique is based on static extraction through the polymer polidimetilsiloxane (PDMS), in which analyte sorption occurs. In this work, SBSE and HPLC techniques have been evaluated for out antidepressants simultaneous analysis in plasma samples for therapeutic drug monitoring. The chromatographic conditions of analysis, as well as SBSE parameters (time, temperature, ionic strength, matrix pH, desorption time) have been optimized in order to obtain best analytical sensitivity. Analytical validation was carried out according to the norms established by ANVISA, in different plasmatic concentrations, which represent the therapeutic interval. The SBSE/HPLC method developed showed linearity in a concentration plasmatic ranging from 20 to 1000 ng mL-1, inter assay precision with coefficient of the variation lower than 14%, and relative recovery from 83 a 110%. Based on analytical validation, the SBSE/HPLC methodology showed good linearity, high sensitivity, selectivity and suitable repeatability to the analyzed antidepressants: imipramine, amitriptyline, nortriptyline, desipramine, citalopram and sertraline in plasma samples for therapeutic drug monitoring.

The Al-Zn-Mg-Cu (7XXX series) alloys are amongst the strongest aluminum available. However, they are considered unweldable with conventional fusion techniques due to the negative effects that arise with conventional welding, including hydrogen porosity, hot cracking, and stress corrosion cracking. For this reason, friction stir welding has emerged as the preferred technique to weld 7XXX series alloys. Aluminum 7449 is one of the highest strength 7XXX series aluminum alloy. This is due to its higher zinc content, which leads to a higher volume fraction of eta' precipitates. It is typically used in a slight overaged condition since it exhibits better corrosion resistance. In this work, the welds of friction stir welded aluminum 7449 were studied extensively. Specific focus was placed in the heat affected zone (HAZ) and nugget. Thermocouples were used in the heat affected zone for three different depths to obtain thermal profiles as well as cooling/heating profiles. Vicker microhardness testing, transmission electron microscope (TEM), and differential scanning calorimeter (DSC) were used to characterize the welds. Two different tempers of the alloy were used, a low overaged temper and a high overaged temper. A thorough comparison of the two different tempers was done. It was found that highly overaged aluminum 7449 tempers show better properties for friction stir welding. A heat gradient along with a high conducting plate (Cu) used at the bottom of the run, resulted in welds with two separate microstructures in the nugget. Due to the microstructure at the bottom of the nugget, higher strength than the base metal is observed. Furthermore, the effects of natural aging and artificial aging were studied to understand re-precipitation. Large improvements in strength are observed after natural aging throughout the welds, including improvements in the HAZ.