Nucleophilic addition of Nitrones to Electron deficient acetylenes and related studies

Nitrones or azomethine-N-oxides are important precursors for the synthesis of several heterocyclic systems. They belong to the allyl anion type 1,3-dipoles and possess unique structural features which make them extraordinarily useful synthons. They behave as 1,3-dipoles in 1,3-dipolar cycloaddition reactions and as electrophiles in reactions with organometallic reagents. These are the two basic reactions given by nitrones. Nitrones also act as ‘spin traps’ in which they react with short-lived radicals to furnish stable nitroxide radicals which can be detected and identified by electron paramagnetic resonance (EPR) spectroscopy. Recently SmI2 catalysed reductive cross-coupling reactions of nitrones have gained significant interest in which the reactions are initiated by single electron transfer (SET) to nitrones. Apart from these reactions, nitrones are also known to participate in reactions which are initiated by the nucleophilic attack of nitrone-oxygen. In our group, we have also explored the nucleophilic character of nitrones through various reactions. The results obtained enabled us to develop a novel two-step one-pot strategy for quinolines and indoles - the heterocycles renowned for their pharmacological applications, from nitrones and electron deficient acetylenes. Using dibenzoylacetylene and phenylbenzoylacetylene as dipolarophiles, we could introduce a desired functional group at a predetermined position of the quinolines or indoles to be synthesised. In this context, the thesis entitled “NUCLEOPHILIC ADDITION OF NITRONES TO ELECTRON DEFICIENT ACETYLENES AND RELATED STUDIES” portrays our attempt to expand the scope of our x novel synthetic protocol using ester functionalised acetylenes: dimethyl acetylenedicarboxylate (DMAD) and methyl propiolate. The thesis is organised in to five chapters. The first chapter briefly describes the different classes of reactions that nitrone functionality can tolerate. The research problem is defined at the end of this chapter. The second chapter describes the synthesis of different nitrones used for the present study. The optimisation and expansion of scope of the novel strategy towards quinoline synthesis is discussed in the third chapter. The fourth chapter portrays the synthesis of indole-3-carboxylates using the novel strategy. In the fifth chapter, the reaction of N-(2,6-dimethylphenyl) and N-(2,4,6-trimethylphenyl)nitrones are discussed. Here we also discuss the mechanistic reinvestigation of Baldwin’s proposal in the isoxazoline-oxazoline rearrangement. The major outcome of the work is given at the end of the thesis. The structural formulae, schemes, tables and figures are numbered chapter-wise since each chapter of the thesis is organized as an independent unit. All new compounds (except two compounds reported in fourth chapter) are fully characterised on the basis of spectral and analytical data and single crystal X-ray analysis on representative examples. Relevant references are included at the end of individual chapters.

Maternal history of early adversity and child emotional development : investigating intervening factors

L’objectif de cette thèse était de contribuer à l’avancement des connaissances quant aux circonstances permettant une transmission intergénérationnelle du risque émanant de l’adversité maternelle et aux mécanismes sous-tendant cette transmission, dans quatre articles empiriques. Le premier visait à explorer la relation entre un historique d’adversité maternelle, la sécurité d’attachement mère-enfant et le tempérament de l’enfant. Les mères ont complété une entrevue semi-structurée portant sur leurs représentations d’attachement avec leurs parents, à 6 mois, et ont évalué le tempérament de leur enfant à 2 ans. La sécurité d’attachement fut également évaluée à 2 ans. Les résultats ont démontré que les enfants dont les mères rapportaient des niveaux supérieurs d’adversité présentaient de moins bons niveaux d’activité comportementale, uniquement lorsqu’ils avaient un attachement sécurisant avec leur mère. Ces résultats suggèrent une transmission intergénérationnelle des effets d’un historique d’adversité maternelle sur le tempérament des enfants. Le deuxième article visait à investiguer si le transporteur de sérotonine (5-HTTLPR) module la transmission de risque intergénérationnelle de l’adversité maternelle sur le tempérament des enfants. L’historique d’adversité maternelle fut évalué en combinant deux mesures auto-rapportées. Les mères ont également évalué le tempérament de leur enfant à 18 et à 36 mois. Le génotype des enfants fut extrait à 36 mois. Les résultats ont révélé un effet d’interaction entre l’adversité maternelle et le génotype de l’enfant sur le tempérament, suggérant une transmission intergénérationnelle des effets de l’adversité maternelle sur le fonctionnement émotionnel des enfants. Le troisième article visait à explorer la relation entre les difficultés d’adaptation psychosociale des mères, la sensibilité maternelle et les symptômes intériorisés de leurs enfants. Les mères ont complété plusieurs questionnaires desquels un score composite de difficultés d’adaptation psychosociale fut extrait. La sensibilité maternelle fut observée à 12 mois. Les symptômes intériorisés des enfants furent évalués par les deux parents à 2 et à 3 ans. Les résultats ont démontré qu’une augmentation des difficultés maternelles d’adaptation psychosociale étaient associée à davantage de symptômes intériorisés chez les enfants, mais seulement chez ceux dont les mères étaient moins sensibles. Ces résultats ont été observés par les mères à 2 ans et par les deux parents à 3 ans. Ces résultats suggèrent que les enfants peuvent être différemment affectés par l’adaptation émotionnelle de leur mère tout en mettant l’emphase sur le rôle protecteur de la sensibilité maternelle. Le quatrième article visait à investiguer les rôles médiateurs de la dépression et de la sensibilité maternelle dans la relation entre un historique d’adversité maternelle et le tempérament de l’enfant. L’historique d’adversité maternelle fut évalué en combinant deux mesures auto-rapportées. Les mères ont également rapporté leurs symptômes dépressifs à 6 mois. La sensibilité maternelle fut évaluée de façon concomitante. Les mères ont évalué le tempérament de leur enfant à 36 mois. Les résultats ont révélé une transmission intergénérationnelle des effets d’un historique d’adversité maternelle à la génération suivante suivant une médiation séquentielle passant d’abord par la dépression maternelle et ensuite par la sensibilité maternelle. Finalement, les résultats des quatre articles ont été intégrés dans la conclusion générale.

Public Perceptions of the Midwest's Pavements - Executive Summary: Iowa

This report summarizes Iowa results of a five year, Pooled Fund study involving the Wisconsin, Iowa, and Minnesota Departments of Transportation (DOTs) designed to 1) assess the public's perceptions of the DOTs' pavement improvement strategies and 2) develop customer-based thresholds of satisfaction with pavements on rural two lane highways in each state as related to the DOTs' physical indices, such as pavement ride and condition. The primary objective was to seek systematic customer input to improve the DOTs' pavement improvement policies by 1) determining how drivers perceive the DOTs' pavements in terms of comfort and convenience but also in terms of other tradeoffs the DOTs had not previously considered, 2) determining relationships between perceptions and measured pavement condition thresholds (including a general level of tolerance of winter ride conditions in two of the states), and 3) identifying important attributes and issues that may not have been considered in the past. Secondary objectives were 1) to provide a tool for systematic customer input in the future and 2) to provide information which can help structure public information programs. A University of Wisconsin-Extension survey lab conducted the surveys under the direction of a multi-disciplinary team from Marquette University. Approximately 4500 drivers in the 3 states participated in the 3 phases of the project. Researchers conducted 6 focus groups in each state, approximately 400 statewide telephone interviews in each state and 700-800 targeted telephone interviews in each state. Approximately 400 winter ride interviews were conducted in Wisconsin and Minnesota. A summary of the method for each survey is included. In Phase I, focus groups were conducted with drivers to get an initial indication of what the driving public believes in regards to pavements and to frame issues for inclusion in the more representative statewide surveys of drivers conducted in Phase II. Phase II interviews gathered information about improvement policy tradeoff issues and about preliminary thresholds of improvement in terms of physical pavement indices. In Phase III, a two step recruitment and post-drive interview procedure yielded thresholds of ride and condition index summarized for each state. Results show that, in general, the driving public wants longer lasting pavements and are willing to pay for them. They want to minimize construction delay, improve entire sections of highway at one time but they dislike detours, and prefer construction under traffic even if it stretches out construction time. Satisfaction with pavements does not correlate directly to a high degree with physical pavement indices, but was found instead to be a complex, multi-faceted phenomenon. A psychological model was applied to explain satisfaction to a respectable degree for the social sciences. Results also indicate a high degree of trust in the 3 DOTs which is enhanced when the public is asked for input on specific highway segments. Conclusions and recommendations include a 3-step methodology for other state studies.

Novel inhibitors of the tRNA-dependent amidotransferase of "Helicobacter pylori": Peptides generated by phage display and dipeptide-like compounds

Cette thèse présente la découverte de nouveaux inhibiteurs de l’amidotransférase ARNt-dépendante (AdT), et résume les connaissances récentes sur la biosynthèse du Gln-ARNtGln et de l’Asn-ARNtAsn par la voie indirecte chez la bactérie Helicobacter pylori. Dans le cytoplasme des eucaryotes, vingt acides aminés sont liés à leur ARNt correspondant par vingt aminoacyl-ARNt synthétases (aaRSs). Ces enzymes sont très spécifiques, et leur fonction est importante pour le décodage correct du code génétique. Cependant, la plupart des bactéries, dont H. pylori, sont dépourvues d’asparaginyl-ARNt synthétase et/ou de glutaminyl-ARNt synthétase. Pour former le Gln-ARNtGln, H. pylori utilise une GluRS noncanonique nommée GluRS2 qui glutamyle spécifiquement l’ARNtGln ; ensuite, une AdT trimérique, la GatCAB corrige le Glu-ARNtGln mésapparié en le transamidant pour former le Gln-ARNtGln, qui lira correctement les codons glutamine pendant la biosynthèse des protéines sur les ribosomes. La formation de l’Asn-ARNtAsn est similaire à celle du Gln-ARNtGln, et utilise la même GatCAB et une AspRS non-discriminatrice. Depuis des années 2000, la GatCAB est considérée comme une cible prometteuse pour le développement de nouveaux antibiotiques, puisqu’elle est absente du cytoplasme de l’être humain, et qu’elle est encodée dans le génome de plusieurs bactéries pathogènes. Dans le chapitre 3, nous présentons la découverte par la technique du « phage display » de peptides cycliques riches en tryptophane et en proline, et qui inhibent l’activité de la GatCAB de H. pylori. Les peptides P10 (CMPVWKPDC) et P9 (CSAHNWPNC) inhibent cette enzyme de façon compétitive par rapport au substrat Glu-ARNtGln. Leur constante d’inhibition (Ki) est 126 μM pour P10, et 392 μM pour P9. Des modèles moléculaires ont montré qu’ils lient le site actif de la réaction de transmidation catalysée par la GatCAB, grâce à la formation d’une interaction π-π entre le résidu Trp de ces peptides et le résidu Tyr81 de la sous-unité GatB, comme fait le A76 3’-terminal de l’ARNt. Dans une autre étude concernant des petits composés contenant un groupe sulfone, et qui mimiquent l’intermédiaire de la réaction de transamidation, nous avons identifié des composés qui inhibent la GatCAB de H. pylori de façon compétitive par rapport au substrat Glu-ARNtGln. Cinq fois plus petits que les peptides cycliques mentionnés plus haut, ces composés inhibent l’activité de la GatCAB avec des Ki de 139 μM pour le composé 7, et de 214 μM pour le composé 4. Ces inhibiteurs de GatCAB pourraient être utiles pour des études mécanistiques, et pourraient être des molécules de base pour le développement de nouvelles classes d’antibiotiques contre des infections causées par H. pylori.

The effect of alcohol consumption on household income in Ireland

This paper presents a study of the effects of alcohol consumption on household income in Ireland using the Slán National Health and Lifestyle Survey 2007 dataset, accounting for endogeneity and selection bias. Drinkers are categorised into one of four categories based on the recommended weekly drinking levels by the Irish Health Promotion Unit; those who never drank, non-drinkers, moderate and heavy drinkers. A multinomial logit OLS Two Step Estimate is used to explain individual's choice of drinking status and to correct for selection bias which would result in the selection into a particular category of drinking being endogenous. Endogeneity which may arise through the simultaneity of drinking status and income either due to the reverse causation between the two variables, income affecting alcohol consumption or alcohol consumption affecting income, or due to unobserved heterogeneity, is addressed. This paper finds that the household income of drinkers is higher than that of non-drinkers and of those who never drank. There is very little difference between the household income of moderate and heavy drinkers, with heavy drinkers earning slightly more. Weekly household income for those who never drank is €454.20, non-drinkers is €506.26, compared with €683.36 per week for moderate drinkers and €694.18 for heavy drinkers.

Conception mécaniste-empirique des chaussées non revêtues

Dans le contexte où les routes non revêtues sont susceptibles de subir des charges importantes, une méthode rigoureuse pour la conception de ces chaussées basée sur des principes mécanistes-empiriques et sur le comportement mécanique des sols support est souhaitable. La conception mécaniste combinée à des lois d’endommagement permet l’optimisation des structures de chaussées non revêtues ainsi que la réduction des coûts de construction et d’entretien. Le but de ce projet est donc la mise au point d’une méthode de conception mécaniste-empirique adaptée aux chaussées non revêtues. Il a été question tout d’abord de mettre au point un code de calcul pour la détermination des contraintes et des déformations dans la chaussée. Ensuite, des lois d’endommagement empiriques pour les chaussées non revêtues ont été développées. Enfin, les méthodes de calcul ont permis la création d’abaques de conception. Le développement du code de calcul a consisté en une modélisation de la chaussée par un système élastique multi-couches. La modélisation a été faite en utilisant la transformation d’Odemark et les équations de Boussinesq pour le calcul des déformations sous la charge. L’élaboration des fonctions de transfert empiriques adaptées aux chaussées non revêtues a également été effectuée. Le développement des fonctions de transfert s’est fait en deux étapes. Tout d’abord, l’établissement de valeurs seuil d’orniérage considérant des niveaux jugés raisonnables de conditions fonctionnelle et structurale de la chaussée. Ensuite, le développement de critères de déformation admissible en associant les déformations théoriques calculées à l’aide du code de calcul à l’endommagement observé sur plusieurs routes en service. Les essais ont eu lieu sur des chaussées typiques reconstituées en laboratoire et soumises à un chargement répété par simulateur de charge. Les chaussées ont été instrumentées pour mesurer la déformation au sommet du sol d’infrastructure et les taux d’endommagements ont été mesurés au cours des essais.

Chitosan scaffold as an alternative adsorbent for the removal of hazardous food dyes from aqueous solutions

Hypothesis: The dye adsorption with chitosan is considered an eco-friendly alternative technology in relation to the existing water treatment technologies. However, the application of chitosan for dyes removal is limited, due to its low surface area and porosity. Then we prepared a chitosan scaffold with a megaporous structure as an alternative adsorbent to remove food dyes from solutions. Experiments: The chitosan scaffold was characterized by infrared spectroscopy, scanning electron microscopy and structural characteristics. The potential of chitosan scaffold to remove five food dyes from solutions was investigated by equilibrium isotherms and thermodynamic study. The scaffold–dyes interactions were elucidated, and desorption studies were carried out. Findings: The chitosan scaffold presented pore sizes from 50 to 200 lm, porosity of 92.2 ± 1.2% and specific surface area of 1135 ± 2 m2 g 1. The two-step Langmuir model was suitable to represent the equilibrium data. The adsorption was spontaneous, favorable, exothermic and enthalpy-controlled process. Electrostatic interactions occurred between chitosan scaffold and dyes. Desorption was possible with NaOH solution (0.10 mol L 1). The chitosan megaporous scaffold showed good structural characteristics and high adsorption capacities (788–3316 mg g 1).

A Stationless Bikeshare Proof of Concept for College Campuses

Bikeshares promote healthy lifestyles and sustainability among commuters, casual riders, and tourists. However, the central pillar of modern systems, the bike station, cannot be easily integrated into a compact college campus. Fixed stations lack the flexibility to meet the needs of college students who make quick, short-distance trips. Additionally, the necessary cost of implementing and maintaining each station prohibits increasing the number of stations for user convenience. Therefore, the team developed a stationless bikeshare based on a smartlock permanently attached to bicycles in the system. The smartlock system design incorporates several innovative approaches to provide usability, security, and reliability that overcome the limitations of a station centered design. A focus group discussion allowed the team to receive feedback on the early lock, system, and website designs, identify improvements and craft a pleasant user experience. The team designed a unique, two-step lock system that is intuitive to operate while mitigating user error. To ensure security, user access is limited through near field ii communications (NFC) technology connected to a mechatronic release system. The said system relied on a NFC module and a servo working through an Arduino microcontroller coded in the Arduino IDE. To track rentals and maintain the system, each bike is fitted with an XBee module to communicate with a scalable ZigBee mesh network. The network allows for bidirectional, real-time communication with a Meteor.js web application, which enables user and administrator functions through an intuitive user interface available on mobile and desktop. The development of an independent smartlock to replace bike stations is essential to meet the needs of the modern college student. With the goal of creating a bikeshare that better serves college students, Team BIKES has laid the framework for a system that is affordable, easily adaptable, and implementable on any university expressing an interest in bringing a bikeshare to its campus.

Self-Assembled InAs/GaAs Quantum Dot Solar Cells

Our work focuses on experimental and theoretical studies aimed at establishing a fundamental understanding of the principal electrical and optical processes governing the operation of quantum dot solar cells (QDSC) and their feasibility for the realization of intermediate band solar cell (IBSC). Uniform performance QD solar cells with high conversion efficiency have been fabricated using carefully calibrated process recipes as the basis of all reliable experimental characterization. The origin for the enhancement of the short circuit current density (Jsc) in QD solar cells was carefully investigated. External quantum efficiency (EQE) measurements were performed as a measure of the below bandgap distribution of transition states. In this work, we found that the incorporation of self-assembled quantum dots (QDs) interrupts the lattice periodicity and introduce a greatly broadened tailing density of states extending from the bandedge towards mid-gap. A below-bandgap density of states (DOS) model with an extended Urbach tail has been developed. In particular, the below-bandgap photocurrent generation has been attributed to transitions via confined energy states and background continuum tailing states. Photoluminescence measurement is used to measure the energy level of the lowest available state and the coupling effect between QD states and background tailing states because it results from a non-equilibrium process. A basic I-V measurement reveals a degradation of the open circuit voltage (Voc) of QD solar cells, which is related to a one sub-bandgap photon absorption process followed by a direct collection of the generated carriers by the external circuit. We have proposed a modified Shockley-Queisser (SQ) model that predicts the degradation of Voc compared with a reference bulk device. Whenever an energy state within the forbidden gap can facilitate additional absorption, it can facilitate recombination as well. If the recombination is non-radiative, it is detrimental to solar cell performance. We have also investigated the QD trapping effects as deep level energy states. Without an efficient carrier extraction pathway, the QDs can indeed function as mobile carriers traps. Since hole energy levels are mostly connected with hole collection under room temperature, the trapping effect is more severe for electrons. We have tried to electron-dope the QDs to exert a repulsive Coulomb force to help improve the carrier collection efficiency. We have experimentally observed a 30% improvement of Jsc for 4e/dot devices compared with 0e/dot devices. Electron-doping helps with better carrier collection efficiency, however, we have also measured a smaller transition probability from valance band to QD states as a direct manifestation of the Pauli Exclusion Principle. The non-linear performance is of particular interest. With the availability of laser with on-resonance and off-resonance excitation energy, we have explored the photocurrent enhancement by a sequential two-photon absorption (2PA) process via the intermediate states. For the first time, we are able to distinguish the nonlinearity effect by 1PA and 2PA process. The observed 2PA current under off-resonant and on-resonant excitation comes from a two-step transition via the tailing states instead of the QD states. However, given the existence of an extended Urbach tail and the small number of photons available for the intermediate states to conduction band transition, the experimental results suggest that with the current material system, the intensity requirement for an observable enhancement of photocurrent via a 2PA process is much higher than what is available from concentrated sun light. In order to realize the IBSC model, a matching transition strength needs to be achieved between valance band to QD states and QD states to conduction band. However, we have experimentally shown that only a negligible amount of signal can be observed at cryogenic temperature via the transition from QD states to conduction band under a broadband IR source excitation. Based on the understanding we have achieved, we found that the existence of the extended tailing density of states together with the large mismatch of the transition strength from VB to QD and from QD to CB, has systematically put into question the feasibility of the IBSC model with QDs.

Cryopreservation of avocado (Persea Americana Mill.) using somatic embryos

Avocado genetic resources are currently maintained in the form of field repositories at great cost and risk of natural disasters, pest and diseases. Cryopreservation offers a necessary, complimentary method that is safe, cost-effective and long-term. However, long-term maintenance and regeneration of plantlets from avocado somatic embryos has been a major barrier in the development of new avocado cultivars. In this study, two protocols for vitrification-based cryopreservation of avocado somatic embryos were investigated. Globular somatic embryos of two avocado cultivars were tested, revealing cultivar-dependent differences in desiccation tolerance and subsequent freezing resistance, possibly attributed to their size and culture age. A two-step regeneration system, involving an intermediate liquid phase step between subcultures in solid medium, significantly enhanced shoot development from somatic embryo tissue. This work will add considerable value towards cryopreservation of avocado somatic embryos for germplasm conservation and the generation of new and improved avocado cultivars.

Spliceosomal small nuclear ribonucleoprotein particle trafficking and maturation in the nuclear compartment

We show for the first time that upon injection into the cytoplasm of the oocyte, fluorescein-labeled spliceosomal snRNAs, in the context of functional snRNPs, are targeted to elongating pre-mRNAs. This finding presents us with a novel assay with which to dissect the mechanism by which snRNPs are targeted to nascent pre-mRNA transcripts. Two critical advantages offered by this system are immediately evident. First, it allows us to investigate the mechanisms employed to recruit snRNPs as it actually transpires within the realm of the cell nucleus. Second, it allows a genome-wide analysis of snRNP recruitment to nascent transcripts, and, hence, the conclusions drawn from these studies do not depend on the sequence of any particular promoter or pre-mRNA. Indeed, it is with this assay that we have stumbled upon a most unanticipated discovery: Contrary to the current paradigm, the co-transcriptional recruitment of splicing snRNPs to nascent transcripts is not contingent on their role in splicing in vivo. Based on these and other data, we have constructed a two-step recruitment-loading model wherein snRNPs are first recruited to pre-mRNA transcripts and only then loaded directly onto cis-acting sequences on nascent pre-mRNA. While conducting studies on snRNP trafficking, a new discovery was made. We found that the lampbrush chromosomes could be visualized by light microscopy in vivo, and that these chromosomes have an architecture that is identical with those in formaldehyde treated nuclear spread preparations. Importantly, we now have the first system with which we can examine the dynamic interactions of macromolecules with specific RNA polymerase II transcriptional units in the live nucleus.

Desenvolvimento de um novo processo para a produção de biodiesel etílico de mamona

No presente trabalho estudou-se a produção de ésteres etílicos de ácido graxo de Ricinus communis L. através da tranesterificação alcalina do óleo de mamona com etanol. Esta metodologia foi adotada para determinar as melhores condições para a produção de biodiesel a partir de óleo de mamona usando o mínimo de operações unitárias com benefícios do ponto de vista econômico e de produção de efluentes. Para a obtenção dos ésteres etílicos através do processo de transesterificação (etapa 1) utilizou-se como catalisador 1% de NaOH com etanol em uma razão molar de 6:1 seguido da adição de ácido sulfúrico. Após, a reação de esterificação (etapa 2) dos ácidos graxos contidos no biodiesel foi realizada visando reduzir o índice de acidez da amostra, ficando em torno de 2 mg de KOH/g. A quebra in situ dos sabões (provenientes da reação paralela de saponificação do triglicerídeo) pela adição de ácido sulfúrico ao meio reacional foi bem sucedida melhorando a separação dos FAEEs do glicerol. O processo em duas etapas transesterificação/esterificação apresentou boa conversão para os ésteres etílicos, diminuindo o índice de acidez e atingindo as especificações para glicerina total e livre. O biodiesel proveniente do óleo de mamona foi composto de 90,6% ácido ricinoléico (C18:1, OH), 3,2% ácido oléico (C18:1), 4,5% ácido linoléico (C18:2), 0,7% ácido esteárico (C18:0), 1,0% ácido palmítico (C16:0), triacilgliceróis (TGs, 0%), diacilgliceróis (DGs, 0,37%) monoacilgliceróis (MGs, 0,46%) e glicerol livre (0,25%) após o processo em duas etapas transesterificação/esterificação. O processo em duas etapas foi muito importante para determinar a integralidade da reação no rendimento do produto. Os resultados demonstram que o procedimento desenvolvido para a produção de FAEEs em escala de laboratório pode ser escalonado para uma planta piloto.

Otimização dos sistemas biológicos e melhorias nos tratamentos da ETARI da Refinaria de Matosinhos

A Refinaria de Matosinhos é um dos complexos industriais da Galp Energia. A sua estação de tratamento de águas residuais industriais (ETARI) – designada internamente por Unidade 7000 – é composta por quatro tratamentos: o pré-tratamento, o tratamento físico-químico, o tratamento biológico e o pós-tratamento. Dada a interligação existente, é fundamental a otimização de cada um dos tratamentos. Este trabalho teve como objetivos a identificação dos problemas e/ou possibilidades de melhoria do pré-tratamento, tratamento físico-químico e pós-tratamento e principalmente a otimização do tratamento biológico da ETARI. No pré-tratamento verificou-se que a separação de óleos e lamas não era eficaz uma vez que se formam emulsões destas duas fases. Como solução, sugeriu-se a adição de agentes desemulsionantes, que se revelou economicamente inviável. Assim, sugeriu-se como alternativa o recurso a técnicas de tratamento da emulsão gerada, tais como a extração com solvente, centrifugação, ultrassons e micro-ondas. No tratamento físico-químico constatou-se que o controlo da unidade de saturação de ar na água era feito com base na análise visual dos operadores, o que pode conduzir a condições de operação afastadas das ótimas para este tratamento. Assim, sugeriu-se a realização de um estudo de otimização desta unidade com vista à determinação da razão ar/sólidos ótima para este efluente. Para além disto, constatou-se, ainda, que os consumos de coagulante aumentaram cerca de -- % no último ano, pelo que foi sugerido o estudo da viabilidade do processo de eletrocoagulação como substituto do sistema de coagulação existente. No pós-tratamento identificou-se o processo de lavagem dos filtros como sendo a etapa com possibilidade de ser otimizada. Através de um estudo preliminar concluiu-se que a lavagem contínua de um filtro por cada turno melhorava o desempenho dos mesmos. Constatou-se, ainda, que a introdução de ar comprimido na água de lavagem promove uma maior remoção de detritos do leito de areia, no entanto esta prática parece influenciar negativamente o desempenho dos filtros. No caso do tratamento biológico, identificaram-se problemas ao nível do tempo de retenção hidráulico do tratamento biológico II, que apresentou elevada variabilidade. Apesar de identificado concluiu-se que este problema era de difícil solução. Verificou-se, também, que o oxigénio dissolvido não era monitorizado, pelo que se sugeriu a instalação de uma sonda de oxigénio dissolvido numa zona de baixa turbulência do tanque de arejamento. Concluiu-se que o oxigénio era distribuído de forma homogénea por todo o tanque de arejamento e tentou-se identificar quais os fatores que influenciariam este parâmetro, no entanto, dada a elevada variabilidade do efluente e das condições de tratamento, tal não foi possível. Constatou-se, também, que o doseamento de fosfato para o tratamento biológico II era pouco eficiente já Otimização dos sistemas biológicos e melhorias nos tratamentos da ETARI da Refinaria de Matosinhos que em -- % dos dias se verificaram níveis baixos de fosfato no licor misto (< - mg/L). Foi, por isso, proposta a alteração do atual sistema de doseamento por gravidade para um sistema de bomba doseadora. Para além disso verificou-se que os consumos deste nutriente aumentaram significativamente no último ano (cerca de --%), situação que se constatou estar relacionada com um aumento da população microbiana para este período. Foi possível relacionar-se o aparecimento frequente de lamas à superfície dos decantadores secundários com incrementos repentinos de condutividade, pelo que se sugeriu o armazenamento do efluente nas bacias de tempestade, nestas situações. Verificou-se que a remoção de azoto era praticamente ineficaz uma vez que a conversão de azoto amoniacal em nitratos foi muito baixa. Assim, sugeriu-se o recurso à técnica de bio-augmentação ou a transformação do sistema de lamas ativadas num sistema bietápico. Por fim, constatou-se que a temperatura do efluente à entrada da ETARI apresenta valores bastante elevados para o tratamento biológico (aproximadamente de --º C) pelo que se sugeriu a instalação de uma sonda de temperatura no tanque de arejamento de modo a controlar de forma mais eficaz a temperatura do licor misto. Ainda no que diz respeito ao tratamento biológico, foi possível desenvolver-se um conjunto de ferramentas que visaram o funcionamento otimizado deste tratamento. Nesse sentido, foram apresentadas várias sugestões de melhoria: a utilização do índice volumétrico de lamas como indicador da qualidade das lamas em alternativa à percentagem de lamas; foi desenvolvido um conjunto de fluxogramas para a orientação dos operadores de exterior na resolução de problemas; foi criada uma “janela de operação” que pretende ser um guia de apoio à operação; foi ainda proposta a monitorização frequente da idade das lamas e da razão alimento/microrganismo.

Microfluidic Encapsulation of Pickering Oil Microdroplets into Alginate Microgels for Lipophilic Compound Delivery

Alginate microgels are widely used as delivery systems in food, cosmetics, and pharmaceutical industries for encapsulation and sustained release of hydrophilic compounds and cells. However, the encapsulation of lipophilic molecules inside these microgels remains a great challenge because of the complex oil-core matrix required. The present study describes an original two-step approach allowing the easy encapsulation of several oil microdroplets within alginate microgels. In the first step, stable oil microdroplets were formed by preparing an oil-in-water (O/W) Pickering emulsion. To stabilize this emulsion, we used two solid particles, namely the cotton cellulose nanocrystals (CNC) and calcium carbonate (CaCO3). It was observed that the surface of the oil microdroplets formed was totally covered by a CNC layer, whereas CaCO3 particles were adsorbed onto the cellulose layer. This solid CNC shell efficiently stabilized the oil microdroplets, preventing them from undesired coalescence. In the second step, oil microdroplets resulting from the Pickering emulsion were encapsulated within alginate microgels using microfluidics. Precisely, the outermost layer of oil microdroplets composed of CaCO3 particles was used to initiate alginate gelation inside the microfluidic device, following the internal gelation mode. The released Ca2+ ions induced the gel formation through physical cross-linking with alginate molecules. This innovative and easy to carry out two-step approach was successfully developed to fabricate monodisperse alginate microgels of 85 pm in diameter containing around 12 oil microdroplets of 15 mu m in diameter. These new oil-core alginate microgels represent an attractive system for encapsulation of lipophilic compounds such as vitamins, aroma compounds or anticancer drugs that could be applied in various domains including food, cosmetics, and medical applications.

Síntese de ß-cetoésteres graxos a partir do ácido de Meldrum usando DCC e DMAP

Neste trabalho desenvolveu-se a síntese de -cetoésteres, a partir da acilação do ácido de Meldrum usando diferentes ácidos graxos, com cadeias saturadas e insaturadas. Inicialmente, foi realizado o experimento utilizando o ácido palmítico (1e) como modelo para obtenção de cloreto de ácido graxo, usando ácido de Meldrum e piridina como catalisador. Porém, após um longo tempo de reação, o -cetoéster palmítico (4e) foi obtido com baixo rendimento, não ultrapassando os 20%. Posteriormente, os experimentos foram realizados utilizando o ácidos graxos 1e, ácido de Meldrum (2), DCC, DMAP, e piridina à temperatura ambiente sob a atmosfera de nitrogênio. No entanto, o protocolo utilizado resultou no β-cetoéster 4e com rendimentos moderados. Em seguida examinou-se o efeito da adição do ácido de Meldrum após a adição dos ácido graxos e DCC. Neste caso, após a adição do DCC aos ácido graxos 1a-j foi observada a formação imediata das O-aciluréias graxas. A seguir a adição de 2,0 equiv de ácido de Meldrum (2) em diclorometano, revelou a formação dos respectivos enol graxos 3a-j. Posteriormente, os β- cetoésteres 4a-j foram obtidos a partir da reação do enol com o metanol. Este protocolo modificado proporcionou o aumento nos rendimentos (74 a 84%) dos β-cetoéster 4a-j. Após, o β-cetoéster 4k foi sintetizado em 75% utilizando o ácido de Meldrum (2) e ácido ricinoléico (1k), obtido a partir do biodiesel de mamona, à temperatura ambiente e sob a atmosfera de nitrogênio. Portanto, foi desenvolvido um método simples para obter β-cetoésteres graxos, a partir do ácido de Meldrum com cadeias graxas diversificadas utilizando DCC e DMAP. Além disso, o presente trabalho relata pela primeira vez a síntese de novos β-cetoésteres graxos derivados dos ácidos oléico, elaídico, ricinoléico, linoléico e linolênico.