We consider single-source single-sink (ss-ss) multi-hop relay networks, with slow-fading links and single-antenna half-duplex relay nodes. While two-hop cooperative relay networks have been studied in great detail in terms of the diversity-multiplexing tradeoff (DMT), few results are available for more general networks. In this paper, we identify two families of networks that are multi-hop generalizations of the two-hop network: K-Parallel-Path (KPP) networks and layered networks. KPP networks can be viewed as the union of K node-disjoint parallel relaying paths, each of length greater than one. KPP networks are then generalized to KPP(I) networks, which permit interference between paths and to KPP(D) networks, which possess a direct link from source to sink. We characterize the DMT of these families of networks completely for K > 3. Layered networks are networks comprising of layers of relays with edges existing only between adjacent layers, with more than one relay in each layer. We prove that a linear DMT between the maximum diversity dmax and the maximum multiplexing gain of 1 is achievable for single-antenna fully-connected layered networks. This is shown to be equal to the optimal DMT if the number of relaying layers is less than 4. For multiple-antenna KPP and layered networks, we provide an achievable DMT, which is significantly better than known lower bounds for half duplex networks. For arbitrary multi-terminal wireless networks with multiple source-sink pairs, the maximum achievable diversity is shown to be equal to the min-cut between the corresponding source and the sink, irrespective of whether the network has half-duplex or full-duplex relays. For arbitrary ss-ss single-antenna directed acyclic networks with full-duplex relays, we prove that a linear tradeoff between maximum diversity and maximum multiplexing gain is achievable. Along the way, we derive the optimal DMT of a generalized parallel channel and derive lower bounds for the DMT of triangular channel matrices, which are useful in DMT computation of various protocols. All protocols in this paper are explicit and use only amplify-and-forward (AF) relaying. We also construct codes with short block-lengths based on cyclic division algebras that achieve the optimal DMT for all the proposed schemes. Two key implications of the results in the paper are that the half-duplex constraint does not entail any rate loss for a large class of cooperative networks and that simple AF protocols are often sufficient to attain the optimal DMT.

No description available.

Cooperative wireless communication has received significant attention during recent years due to several reasons. First, since the received power decreases rapidly with distance, the idea of multi-hopping is becoming of particular importance. In multi-hopped communication, the source exploits some intermediate nodes as relays. Then the source sends its message via those relays to the destination. Second, relays can emulate some kind of distributed transmit antennas to form spatial diversity and combat multi-path fading effect of the wireless channel. Parallel Relay Channel is an information theoretical model for a communication system whereby a sender aims to communicate to a receiver with the help of relay nodes. It represents the simplest model for a multi–hop wireless network and a full understanding of the limits of communication over such a channel can potentially shed light on the design of more efficient wireless networks. However, the capacity of the relay channel has been established only for few special cases and little progress has been made toward solving the general case since the early 1980s. In this dissertation, motivated by practical constraints, we study the information theoretical limits of the half-duplex Gaussian Parallel Relay channel , as well as, the transmission strategies for the parallel relay channel with bandwidth mismatch between the first and the second hops. Chapter 2 investigates the problem of communication for a network composed of two half-duplex parallel relays with additive white Gaussian noise (AWGN). There is no direct link between the source and the destination. However, the relays can communicate with each other through the channel between them. Two protocols, i.e., \emph{Simultaneous} and \emph{Successive} relaying, associated with two possible relay scheduling are proposed. The simultaneous relaying protocol is based on \emph{Broadcast-multiaccess with Common Message (BCM)} scheme. For the successive relaying protocol: (i) a \emph{Non-Cooperative} scheme based on the \emph{Dirty Paper Coding (DPC)}, and (ii) a \emph{Cooperative} scheme based on the \emph{Block Markov Encoding (BME)} are considered. The composite scheme of employing BME in \emph{at most} one relay and DPC in \emph{at least} another one is shown to achieve at least the same rate when compared to the \emph{Cooperative} and \emph{Non-Cooperative} schemes. A \emph{``Simultaneous-Successive Relaying based on Dirty paper coding scheme" (SSRD)} is also proposed. The optimum scheduling of the relays and hence the capacity of the half-duplex Gaussian parallel relay channel in the low and high signal-to-noise ratio (SNR) scenarios is derived. In the low SNR scenario, it is revealed that under certain conditions for the channel coefficients, the ratio of the achievable rate of the simultaneous relaying based on BCM to the cut-set bound tends to be 1. On the other hand, as SNR goes to infinity, it is proved that successive relaying, based on the DPC, asymptotically achieves the capacity of the network. Schein and Gallager introduced the Gaussian parallel relay channel in 2000. They proposed the Amplify-and-Forward (AF) and the Decode-and-Forward (DF) strategies for this channel. For a long time, the best known achievable rate for this channel was based on the AF and DF with time sharing (AF-DF). Recently, a Rematch-and-Forward (RF) scheme for the scenario in which different amounts of bandwidth can be assigned to the first and second hops were proposed. In chapter 3, we propose a \emph{Combined Amplify-and-Decode Forward (CADF)} scheme for the Gaussian parallel relay channel. We prove that the CADF scheme always gives a better achievable rate compared to the RF scheme, when there is a bandwidth mismatch between the first hop and the second hop. Furthermore, for the equal bandwidth case (Schein's setup), we show that the time sharing between the CADF and the DF schemes (CADF-DF) leads to a better achievable rate compared to the time sharing between the RF and the DF schemes (RF-DF) as well as the AF-DF.

A significant focus of nucleic acids research is on the reactivity of electrophilic species with DNA to form addition products (adducts). Phenols are known to be able to form adducts at the C8 site of deoxyguanosine (dG). This dissertation studies the oxygen (O)-linked class of phenolic dG adducts for their hydrolytic stability as well as their structural impact on the DNA duplex. To determine the effect of C8 O-linked phenolic dG adducts on glycosidic bond stability spectrophotometric determination of hydrolysis kinetics was performed. The kinetics establish the adducts to be less stable than native dG in acid, but surprisingly stable under physiological conditions. Then to assess the modified duplex structure, a C8 O-linked phenolic dG adduct was incorporated into a DNA duplex. Thermal melting analysis establish the adduct as having a destabilizing effect on the regularly paired duplex and the conformational analysis suggests the phenolic lesion to be weakly mutagenic. / NSERC

Les aciers inoxydables duplex présentent une microstructure biphasée dans laquelle se mêlent austénite et ferrite. Leurs caractéristiques mécaniques élevées ainsi que leur bonne tenue en corrosion en font des candidats sérieux pour remplacer les aciers inoxydables austénitiques. Malheureusement, la faible forgeabilité de ces alliages rend la fabrication de tôles particulièrement critique. En effet, le phénomène de " crique de rive " est fréquemment rencontré au cours des étapes du laminage à chaud. Par conséquent, cela nécessite des opérations supplémentaires comme le découpage des rives, ce qui aboutit à une augmentation des coûts de production. Les différents facteurs influençant la ductilité à chaud de ces aciers sont passés en revue afin d'identifier " les zones d'ombres ". La synthèse bibliographique révèle deux zones d'ombres : d'une part, le manque d'un essai de ductilité à chaud permettant de discriminer différentes microstructures en terme de résistance à la propagation de fissure à haute température ; et d'autre part l'absence de données quantitatives concernant la partition de la déformation entre la ferrite et l'austénite lors des étapes de mise en forme à chaud. La méthode du travail essentiel de rupture a été appliquée à hautes températures. Il a été démontré que ce concept est fiable et discriminant pour quantifier la résistance à la propagation de fissure à haute température. Cette méthode permet également de générer un paramètre physique pertinent pour optimiser les microstructures par rapport à un mode de mise en forme donné. La technique conventionnelle de micro-grilles a été adaptée de manière à cartographier à haute température les déformations à l'échelle de la microstructure. Cette technique fournit en plus des résultats qualitatifs concernant les mécanismes de déformations, des données quantitatives à propos de la partition de la déformation entre la ferrite et l'austénite. Ces données peuvent être utilisées afin de valider les modèles qui prédisent le comportement à chaud des aciers duplex pendant les premières étapes du laminage à chaud. Les deux outils développés au cours de cette étude permettent de proposer des solutions pour éviter le phénomène de " crique de rives ".

We prospectively evaluated 30 consecutive patients with echo-enhanced transcranial color-coded duplexsonography (TCCD) and correlative transfemoral digital subtraction angiography to assess the diagnostic efficacy of echo-enhanced TCCD for evaluation of collateral pathways through the circle of Willis in patients with limited acoustic bone windows and critical symptomatic carotid disease. Echo-enhanced TCCD detected collateral blood flow through the anterior communicating artery in 16 of 18 patients (sensitivity 89%, 95% CI 65–99%) and was false positive in one out of 12 patients without collateral flow (specificity 92%, 95% CI 59–100%). For the posterior communicating artery, sensitivity was 11/14 (79%, 95% CI 49–95%) and specificity was 15/16 (94%, 95% CI 70–100%). Echo-enhanced TCCD enables to study collateral blood flow through the communicating arteries of the circle of Willis with high sensitivity and specificity in patients with obstructions of the internal carotid artery and limited acoustic bone windows. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-10-25T22:17:10Z No. of bitstreams: 1 RamiroGomesDeFreitasNeto_DISSERT.pdf: 12806337 bytes, checksum: 668374ace783d763449c01ccfb9e135c (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-12-16T17:50:31Z (GMT) No. of bitstreams: 1 RamiroGomesDeFreitasNeto_DISSERT.pdf: 12806337 bytes, checksum: 668374ace783d763449c01ccfb9e135c (MD5) / Made available in DSpace on 2016-12-16T17:50:31Z (GMT). No. of bitstreams: 1 RamiroGomesDeFreitasNeto_DISSERT.pdf: 12806337 bytes, checksum: 668374ace783d763449c01ccfb9e135c (MD5) Previous issue date: 2016-04-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Os a?os inoxid?veis duplex s?o a?os altamente ligados caracterizados por uma estrutura bif?sica de ferrita-austenita obtida atrav?s de processos de conforma??o a quente ou tratamentos t?rmicos adequados ap?s os processos de conforma??o a frio. A presen?a de fra??es volum?tricas pr?ximas de ferrita e austenita na estrutura dos a?os duplex promove uma boa combina??o entre as propriedades de resist?ncia mec?nica e resist?ncia a corros?o. Uma das classes dos a?os duplex que vem se desenvolvendo nos ?ltimos anos ? o Lean duplex, que apresentam teores mais baixos de Cr, Ni e Mo, o que os torna mais baratos em compara??o com os austen?ticos. Para compensar a redu??o de Ni e Mo, elementos como Mn e N s?o adicionados em maior quantidade para proporcionar uma boa resist?ncia ? corros?o e conferir a estabilidade da austenita no a?o. Nos ?ltimos anos o n?mero de trabalhos relacionados ao a?o Lean duplex cresceu bastante devido ao interesse em se conhecer, desenvolver e aplicar cada vez mais essa classe de a?os. Uma das aplica??es que est? em alta ? a soldagem por difus?o no estado superpl?stico, e os a?os inox duplex possuem o comportamento superpl?stico, que exige microestruturas com gr?os pequenos e baixas taxas de deforma??o. Sendo assim, um estudo de recristaliza??o do a?o inoxid?vel Lean duplex 2101 como m?todo de refino de gr?o ? proposto para este trabalho. Diferentes lamina??es a frio, sendo elas 70, 80 e 90% de redu??o, foram empregadas no material para fornecer potencial termodin?mico para a recristaliza??o nos tratamentos t?rmicos em tr?s temperaturas, 900?C, 1000?C e 1100?C por tempos de 20 minutos, 1 e 2 horas. T?cnicas de microscopia ?ptica, eletr?nica de varredura, EDS, medidas magn?ticas, difra??o de raios-X, EBSD e microdureza foram empregadas para a caracteriza??o. Os resultados de medidas magn?ticas e microscopia ?tica indicam que h? acentuada ocorr?ncia de transforma??o induzida por deforma??o da austenita para martensita CCC, al?m de ind?cios da ocorr?ncia de outros mecanismos de deforma??o como macla??o mec?nica e deslizamento de discord?ncias, bem como ind?cios de zonas de austenita n?o transformada, aparentemente isenta de encruamento, conforme indicado pelos valores de microdureza, mesmo para redu??es de 90% na lamina??o a frio; aparentemente houve precipita??es de fases indesejadas tanto na ferrita quanto na austenita durante os tratamentos t?rmicos e aparente recristaliza??o total das amostras laminadas p?s tratamento t?rmico mesmo para os tempos mais curtos. Nas amostras analisadas por EBSD foram observados ind?cios de refino do gr?o austen?tico e uma tend?ncia de crescimento secund?rio da ferrita. Nas amostras recristalizadas identificou-se que para temperaturas e tempos de tratamento mais baixo as fra??es de ferrita se mostraram levemente maiores, enquanto que para temperaturas e tempos de tratamentos maiores as fra??es de austenita foram maiores. / Duplex Stainless Steel are an alloy based on Fe-Cr-Ni system characterized by biphasic structure of austenite-ferrite obtained through different thermomechanical cycles and they show good combination between mechanical (high tension strength and good tenacity) and corrosion resistance properties (stress corrosion cracking and pitting corrosion), besides good soldability. One of the Duplex Stainless Steel grades that is being developed in the last years is the Lean Duplex (LDSS) which have low addition of Cr, Ni, Mo and, for this, they are cheaper than austenitic and standard duplex stainless steel. To compensate the reduction of Ni and Mo, elements like Mn and N are added in larger quantities to give good corrosion resistance and ensure the stability of austenite. A possibility for application for LDSS is the manufacturing of components that are subjected corrosion conditions lesser severe for petrochemical industries, manufactured by diffusion bonding, taking advantage of superplastic behavior that these steels have since refined grains structure is present and low deformation rate are applied. Therefore, in this work was made a study of recrystallization of LDSS 2101, previously work hardened, as a method to refine grain. The material was subjected to different reduction degree by cold rolling (70, 80 and 90%), different heat treatments of recrystallization annealing in three temperatures (900, 1000 and 1100?C) and different times (20 min, 1 and 2 hours). The techniques of optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy, magnetic saturation measures, X-ray diffraction, Electron Backscattered Diffraction (EBSD) and Vickers micro hardness were employed in the microstructure characterization. The results of magnetic measures and optical microscopy show a sharp occurrence of strain induced martensite BCC (??) on austenite, besides evidences of occurrence of other deformations mechanisms such as deformation twins and dislocation glide, as well evidences of non-transformed austenite without work hardening, according to the hardness values, even for 90% reduction. Evidences of deleterious phases precipitation, as seen in SEM, were not confirmed by X-ray diffraction, which confirms the system thermodynamic simulation, which indicates phase precipitation such as ? and nitrides in temperature smaller than those used in this work. Preliminary analysis of EBSD samples indicates that recrystallization were not complete for 900?C and 20 minutes, as well a refined austenite grain structure and a trend for secondary recrystallization for ferrite. Optical microscopy also shows a trend to increase austenite over ferrite when temperature and time of recrystallization increased.

Submitted by Lucelia Lucena (lucelia.lucena@ufpe.br) on 2015-03-09T19:50:50Z No. of bitstreams: 2 DISSERTAÇÃO Marcos Graciano Santos.pdf: 3653832 bytes, checksum: 63b7958428e143779e52059edac458d4 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) / Made available in DSpace on 2015-03-09T19:50:50Z (GMT). No. of bitstreams: 2 DISSERTAÇÃO Marcos Graciano Santos.pdf: 3653832 bytes, checksum: 63b7958428e143779e52059edac458d4 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Previous issue date: 2014-08-11 / Atualmente, mais de 200 milhões de usuários utilizam as redes 3G/LTE (Long Term Evolution). Com este aumento crescente de usuários com acesso sem fio, muitas pesquisas se concentram no esforço de desenvolvimento de soluções que permitam atender às demandas de redes com alta disponibilidade e altas taxas de transmissão sem considerar, em geral, as limitações de bateria dos dispositivos. Como requisito do LTE Advanced (especificações para a Quarta Geração de comunicações móveis) incluem-se os Serviços de Proximidade, comunicação denominada de dispositivo a dispositivo (D2D, do inglês: device-to-device) para atender ao desenvolvimento de novas demandas de serviços, como jogos e vídeos on-line ou transferência de conteúdos, aplicações que, a cada dia, requerem maiores consumos de energia. Neste trabalho, realizamos medições que avaliam o consumo da comunicação dispositivo-estação base e propomos primeiramente um algoritmo de identificação de pares de dispositivos e definição de limiares de referência, diferentemente de outros trabalhos, com base nas características de consumo dos dispositivos, que viabilize comunicação direta D2D energeticamente mais eficiente que a comunicação convencional via estação rádio base. Em seguida, para cenários de grande aglomeração de pessoas, uma alternativa de serviço de disponibilização de conteúdos ou transferência de arquivos através de um novo padrão de alocação de recursos, utilizando o modo duplex por divisão no tempo (TDD – Time Duplex Division). Foram considerados cinco modelos de propagação distintos para comparação do desempenho, tomando como base uma situação real num parque do Recife considerando a transmissão de um vídeo em alta definição. Por fim, tratamos a questão da segurança com uma criptografia específica entre os dispositivos próximos. Os resultados são avaliados via simulação utilizando-se o Matlab, demonstrando a eficácia da solução com reduções de até 43% no consumo de energia da bateria do dispositivo.

Chronic venous disease (CVD) of the lower extremities is a high prevalence disease in general population and is associated with great morbidity. Patients with body overweight are more likely to present themselves with more severally symptoms and are challenging for conventional surgical treatment. The advent of ultrasound guided foam sclerotherapy has broaden the possibility of treatment for these patients. The association of long-term elastic compression after the procedures continues to show conflicting results. Objectives: This study aims to evaluate the changes in the therapeutic response of foam sclerotherapy when using the long-term elastic compression in overweight patients. Method: In this randomized trial the lower limbs were randomly allocated to use or not elastic compression after insufficient venous treatment and submitted to one or two sessions of ultrasound guided sclerotherapy. The evaluations were performed after 3 weeks and 3 months considering as primary outcome the occlusion of the treated venous segment and as secondary outcome the absence of blood reflux in the segment. Results: 131 lower’s limbs were treated: 70 submitted to long-term elastic compression and 62 not. There was no statistic difference between the group’s characteristics. A total of 187 sessions of foam sclerotherapy, being 131 primary interventions and 56 reinterventions, were performed on the entire sample. The number of sessions was greater in the group submitted to long-term elastic compression (p = 0,64). The average foam volume used were slightly higher in the group without long-term elastic compression (p=0,27). The assessment of the primary and secondary outcome showed no difference in the therapeutic response between the groups after 3 weeks and 3 months evaluating the safenofemoral junction (p = 0,47 and p = 0,99) and saphenous magna vein (p = 0,59 and p = 0,26). For the tributaries the success rates were higher after 3 months for the patients submitted to long-term elastic compression (p = 0,0018). Conclusion: The long-term elastic compression did not interfere in the therapeutic response in patients with body overweight in the main venous trunks. The long-term elastic compression had higher success rates in the tributaries. In addition, the elastic compression seems to be associated to a lower foam volume for treatment. / A doença venosa crônica dos membros inferiores (DVC) apresenta alta prevalência na população geral e acompanha-se de elevada morbidade. Pacientes com excesso de peso tendem a apresentar quadros clínicos mais graves e são um desafio ao tratamento cirúrgico convencional. O advento da escleroterapia com espuma guiada por ultrassom (EEE) ampliou a possibilidade de tratamento destes pacientes. A associação da compressão elástica prolongada após intervenções apresenta resultados controversos na literatura. Objetivo: O presente trabalho pretende avaliar as taxas de sucesso terapêutico da EEE quando da utilização da compressão elástica prolongada em pacientes com excesso de peso. Método: Neste ensaio clínico randomizado os membros inferiores foram alocados randomicamente para uso ou não de meia elástica compressiva após tratamento das veias insuficientes. Foram realizadas uma ou duas sessões de escleroterapia guiada por ultrassonografia. As avaliações foram realizadas decorridas 3 semanas e 3 meses do tratamento, considerando para desfecho primário a oclusão do trajeto venoso tratado e para desfecho secundário a ausência de refluxo no segmento. Resultados: Foram tratados 131 membros inferiores: 69 submetidos a compressão elástica prolongada e 62 não. Os grupos foram avaliados quanto à distribuição de suas características de base não havendo diferenças estatisticamente significativas entre eles. Um total de 187 sessões de ecoescleroterapia com espuma, sendo 131 primeiras intervenções e 56 reintervenções, foram realizadas em toda a amostra. O número de sessões foi maior no grupo submetido à compressão elástica prolongada (p= 0,64). O volume médio de espuma aplicada foi discretamente maior no grupo sem compressão elástica prolongada (p=0,27). Na avaliação dos desfechos primário e secundário não houve diferença na resposta terapêutica entre os grupos em 3 semanas e em 3 meses na avaliação da junção safenofemoral (p= 0,47 e p=0,99) e da veia safena magna (p= 0,79 e p=0,87). Para as tributárias as taxas de sucesso foram maiores em 3 meses nos pacientes submetidos a compressão elástica prolongada (p=0,0018). Conclusão: Não houve interferência da compressão elástica prolongada na resposta terapêutica da ecoescleroterapia em pacientes com excesso de peso nos principais troncos venosos. Para as tributárias, a compressão elástica obteve maiores taxas de sucesso. A compressão elástica pode estar associada a um menor volume de espuma necessário para tratamento.

As ligas de alumínio vêm sendo amplamente usadas nas indústrias aeronáuticas e automobilísticas por suas propriedades mecânicas superiores às do metal puro. Entretanto, como as propriedades de corrosão dessas ligas variam, sendo piores do que as do alumínio puro, surge a necessidade de estudos de diferentes métodos de proteção contra a corrosão. O uso de coberturas protetoras é uma alternativa para diminuir os processos corrosivos e, desta maneira, aumentar a vida útil desses materiais. Das coberturas de conversão existentes, as mais usadas ainda são à base de cromo, porém o cromo tem se mostrado danoso ao meio ambiente e à saúde humana. Por outro lado, as coberturas de conversão à base de óxidos de cério, ambientalmente mais corretas e menos nocivas, já têm sido usadas com sucesso para este propósito. Ademais, partindo do consenso sobre o bom desempenho da polianilina (PAni) em proteger metais oxidáveis contra a corrosão, inclusive o alumínio e suas ligas, o presente estudo propõe o desenvolvimento de proteção anticorrosiva de ligas de alumínio pela combinação de camadas de conversão à base de óxidos de cério associada com camadas de PAni nas ligas de alumínio das séries AA1xxx e AA6xxx. A combinação de camadas duplex surge como uma alternativa promissora por: (i) possibilitar a formação de pontos de ancoragem sobre a superfície, promovidos pelas camadas de conversão à base de óxidos de cério, para a posterior deposição de PAni; (ii) ampliar o uso das camadas de conversão à base de óxidos de cério isoladamente ou combinadas com PAni e (iii) promover o melhor sinergismo na proteção contra a corrosão das ligas de alumínio e de outros materiais pela associação e maior interação desses sistemas. / Aluminium alloys have been widely used in automobile and aircraft industries for their superior mechanical properties to the pure metal. However, as the corrosion properties of these alloys vary, being worse than those of pure aluminium, there is a need for studies of different methods of corrosion protection. The use of protective coverings appears as an alternative to reduce the corrosion process and thereby increase the useful life of these materials. Conversion of existing coverage, the most used are still based on chrome, but chrome has proven harmful to the environment and human health. Furthermore, coverage of cerium-based conversion, more environmentally friendly and healthy, have already been successfully used for this purpose. Furthermore, based on the consensus on the proper performance of polyaniline (PAni) to protect oxidizable metals against corrosion, including aluminium and its alloys, this study proposes the development of corrosion protection of aluminium alloys by combining layers of cerium conversion associated with layers of polyaniline on aluminium alloys AA1xxx and AA6xxx series. The combination of double layers arises as a promising alternative, which may: (i) facilitating formation of anchor points on the surface, driven by layers of cerium conversion, for the subsequent deposition of PAni (ii) expand the use of cerium conversion coatings alone or combined with PAni and (iii) promote synergy in protection against corrosion of aluminium alloys and other materials by the association and greater interaction of these systems.