Os processos oxidativos avançados (POA) são uma alternativa para complementar os processos clássicos de tratamento de efluentes que podem não ser eficientes para remoção de alguns tipos de poluentes como, por exemplo, os poluentes emergentes. Os POA se baseiam na geração de espécies altamente reativas (radicais hidroxila), a partir de peróxido de hidrogênio (H2O2), que oxidam os poluentes. O H2O2 pode ser eletrogerado in situ pela reação de redução de oxigênio (RRO) no meio reacional. O uso de eletrodos de difusão gasosa (EDG) altamente porosos proporciona o suprimento de oxigênio na interface eletrodo/solução podendo aumentar a velocidade da RRO. O uso de modificadores como quinonas e azocompostos imobilizados à matriz de carbono dos EDG podem aumentar a geração de H2O2. Portanto, os modificadores orgânicos Sudan Red 7B (SR7B), metil-p-benzoquinona (MPB), ácido antraflávico (AA) e antraquinona-2-ácido carboxílico (A2CA) foram adicionados em diferentes teores ao carbono Printex L6 (CP) e microcamadas porosas destes materiais foram estudados por voltametria cíclica e de varredura linear em eletrodo de disco-anel rotatório (RRDE). Os materiais contendo 0,5% de SR7B e 5,0% de MPB levaram a aumento na eficiência de geração de H2O2 para 86,2 e 85,5%, respectivamente, em relação ao CP puro que levou a 82,8%. EDG de CP modificados com 0,5% de SR7B foram construídos com telas metálicas em sua faces externas e a aplicação de densidades de corrente de 75, 100 e 150 mA cm-2 levou a uma maior eletrogeração de H2O2. Em densidades de corrente de 75 mA cm-2, o EDG modificado gerou 1020,1 mg L-1 de H2O2 com consumo energético de 118,0 kWh kg-1 de H2O2, constante cinética aparente de 37,3 mg L-1 min-1 e eficiência de corrente de 17,9%, enquanto o EDG de CP puro gerou menor concentração de H2O2; 717, 3 mg L-1, com maior consumo energético; 168,5 kWh kg-1, menor constante cinética aparente; 21,4 mg L-1 min-1, e menor eficiência de corrente; 12,6%. Portanto, o EDG modificado poderia ser empregado em sistemas que precisem de altas gerações de H2O2. / The advanced oxidation processes (AOP) are an alternative to the classical processes of treatment of effluents that may not be effective for the removal of some types of pollutants such as emerging pollutants. The AOP are based on the highly reactive species (hydroxyl radicals) from hydrogen peroxide (H2O2), which oxidize pollutants. H2O2 can be electrogenerated in situ by the oxygen reduction reaction (ORR) in the reaction medium. The use of highly porous gas diffusion electrodes (GDE) provides the supply of oxygen at the electrode/solution interface, which can increase the RRO speed. The use of modifiers such as quinones and azocompounds immobilized on the carbon matrix of GDE may increase H2O2 generation. Therefore, the organic modifiers Sudan Red 7B (SR7B), methyl-p-benzoquinone (MPB), anthraflavic acid (AA) and anthraquinone-2-carboxylic acid (A2CA) were added in different contents to carbon Printex L6 (CP) and microporous layers of these materials were studied by cyclic voltammetry and linear sweep voltammetry on a rotating ring- disc electrode (RRDE). Materials with 0.5% of SR7B and 5.0% of MPB increased the current efficiency for electrogeneration of H2O2 to 86.2 and 85.5%, respectively, in relation to pure CP that leaded to 82.8%. GDE of CP modified with 0.5% of SR7B were constructed with metallic screens on their outer faces and an application of current densities of 75, 100 and 150 mA cm-2 led to a greater electrogeneration of H2O2. At current densities of 75 mA cm-2, the modified GDE generated 1020.1 mg L-1 of H2O2 with energy consumption of 118.0 kWh kg-1 of H2O2, apparent kinetic constant of 37.3 mg L-1 min-1 and current efficiency of 17.9%, while GDE of pure CP generated lower H2O2 concentration; 717, 3 mg L-1, with higher energy consumption; 168.5 kWh kg-1, lower apparent kinetic constant; 21.4 mg L-1 min-1, and lower current efficiency; 12.6%. Therefore, the modified GDE could be applied in systems that require high generations of H2O2.

A determinação direta de arsênio total em águas por espectrometria de absorção atômica com filamentos de tungstênio (150 W) modificados quimicamente com irídio ou ródio, representa uma alternativa para a atomização eletrotérmica de arsênio, que foi avaliada na presente dissertação. A utilização do revestimento com Ir como modificador químico proporcionou um aumento da massa característica de arsênio de 3,5 vezes. As medidas foram feitas com altura de observação selecionada para proporcionar a melhor razão sinal/ruído sem diminuir a sensibilidade do sinal analítico. Avaliaram-se dois programas de aquecimento: com temperatura de secagem constante (com diminuição gradativa da tensão aplicada) e com temperatura de secagem variável (com tensão aplicada de maneira constante). Não houve diferença na sensibilidade entre os dois programas estudados, indicando que a modificação química leva à formação de um precursor atômico com estabilidade térmica elevada. De fato, utilizando-se a modificação química permanente com 1000 müg Ir, e adotando-se programa de aquecimento com temperatura de secagem variável, a temperatura máxima de pirólise foi de aproximadamente 1700 °C ( temperatura de atomização de 2700 °C). Avaliou-se o comportamento eletrotérmico do As na presença dos concomitantes Na, K, Ca e Mg em 0,1% v/v HNO3. Interferências mais severas foram observadas na presença de cálcio acima de 10 \'mü\'g l-1, e acima de 100 \'mü\'g l-1 para os demais concomitantes. As interferências podem estar relacionadas com o elevado gradiente de temperatura entre a superfície do filamento e a fase gasosa do volume de observação, ou mesmo devido à formação de compostos refratários, particularmente para Ca e Mg, na fase condensada, ou seja, na superfície do atomizador. O emprego do método das médias móveis no tratamento dos sinais transientes gerados na atomização do arsênio também foi avaliada. Com o filamento posicionado na altura de observação 2 mm, foram utilizados os fatores 0, 3, 5, 7 e 9, observando-se melhora considerável nos limites de detecção instrumental e do método,utilizando-se média móvel com fator 7. Nestas condições, e depositando-se 20 \'mü\'l de amostra sobre o filamento, o limite de detecção foi de 3,2 \'mü\'g l-1 As e a massa característica de 37,0 pg As. A exatidão foi avaliada analisando-se diferentes amostras de águas provenientes da região do Quadrilátero Ferrífero do Estado de Minas Gerais, por espectrometria de fluorescência atômica com geração de hidretos e por espectrometria de absorção atômica com o filamento de tungstênio modificado com Ir. A comparação dos resultados mostrou que o método proposto pode ser utilizado para o controle de qualidade de águas desta região. Aproximadamente 150 queimas podem ser feitas com um único filamento de tungstênio / The direct determination of arsenic in waters by atomic absorption spectrometry with 150 W tungsten coils, treated with Ir or Rh, was evaluated as a possible alternative for the eletrothermal atomization of As. The use of iridium as a permanent chemical modifier did improve the characteristic mass of arsenic by 3.5 fold. Measurements were made by choosing an appropriate observation height in order to get the best signal to noise ratio. Two heating programs were tested, either by keeping the applied voltage constant or by using an inverted voltage ramp during the drying step. There were no significant differences in the sensitivities between both heating programs, indicating that the permanent modification lead to the formation of an atomic precursor of high thermal stability. Indeed, with the permanent chemical modification with 1000 \'mü\'g Ir, the maximum pyrolysis temperature was approximately 1700 °C (atomization temperature 2700 °C), allowing a heating program with temperature variation during the drying step. Method selectivity was carried out by evaluating the eletrothermal behavior of As in the presence of up to 1000 \'mü\'g l-1 Na, K, Ca and/or Mg in 0,1% v/v HNO3. The most serious interferences were observed with Ca in concentrations higher than 10 \'mü\'g l-1 and when the concentrations were higher than 100 \'mü\'g l-1 for Na, K or Mg, which can be attributed either to the gradient of temperature between the surface of the atomizer and the observation volume or to the formation of refractory compounds in the condensed phase, particularly with Ca and Mg. The absorbance transient signals treatment by the method of moving averages up to factor 9 was also evaluated, with a remarkable improvement in the instrumental and method detection limits. With the center of the observation volume 2 mm above the tungsten coil surface, and a moving average of factor 7, the limit of detection was 3,2 \'müg\' l-1 As and the characteristic mass 37,0 pg As. Accuracy was evaluate by analysing water samples collected in a contaminated area from the Quadrilátero Ferrífero, Minas Gerais State, by hydride generation atomic fluorescence spectrometry and by tungsten coil eletrothermal atomic absorption spectrometry. Results showed that the proposed method fits for the purpose of CONAMA 357 regulation for drinking water quality in the aforementioned contaminated area. Approximately 150 firings can be done with a single tungsten coil atomizer by using 20 \'mü\'l sample volume

Os processos oxidativos avançados (POA) são uma alternativa para complementar os processos clássicos de tratamento de efluentes que podem não ser eficientes para remoção de alguns tipos de poluentes como, por exemplo, os poluentes emergentes. Os POA se baseiam na geração de espécies altamente reativas (radicais hidroxila), a partir de peróxido de hidrogênio (H2O2), que oxidam os poluentes. O H2O2 pode ser eletrogerado in situ pela reação de redução de oxigênio (RRO) no meio reacional. O uso de eletrodos de difusão gasosa (EDG) altamente porosos proporciona o suprimento de oxigênio na interface eletrodo/solução podendo aumentar a velocidade da RRO. O uso de modificadores como quinonas e azocompostos imobilizados à matriz de carbono dos EDG podem aumentar a geração de H2O2. Portanto, os modificadores orgânicos Sudan Red 7B (SR7B), metil-p-benzoquinona (MPB), ácido antraflávico (AA) e antraquinona-2-ácido carboxílico (A2CA) foram adicionados em diferentes teores ao carbono Printex L6 (CP) e microcamadas porosas destes materiais foram estudados por voltametria cíclica e de varredura linear em eletrodo de disco-anel rotatório (RRDE). Os materiais contendo 0,5% de SR7B e 5,0% de MPB levaram a aumento na eficiência de geração de H2O2 para 86,2 e 85,5%, respectivamente, em relação ao CP puro que levou a 82,8%. EDG de CP modificados com 0,5% de SR7B foram construídos com telas metálicas em sua faces externas e a aplicação de densidades de corrente de 75, 100 e 150 mA cm-2 levou a uma maior eletrogeração de H2O2. Em densidades de corrente de 75 mA cm-2, o EDG modificado gerou 1020,1 mg L-1 de H2O2 com consumo energético de 118,0 kWh kg-1 de H2O2, constante cinética aparente de 37,3 mg L-1 min-1 e eficiência de corrente de 17,9%, enquanto o EDG de CP puro gerou menor concentração de H2O2; 717, 3 mg L-1, com maior consumo energético; 168,5 kWh kg-1, menor constante cinética aparente; 21,4 mg L-1 min-1, e menor eficiência de corrente; 12,6%. Portanto, o EDG modificado poderia ser empregado em sistemas que precisem de altas gerações de H2O2. / The advanced oxidation processes (AOP) are an alternative to the classical processes of treatment of effluents that may not be effective for the removal of some types of pollutants such as emerging pollutants. The AOP are based on the highly reactive species (hydroxyl radicals) from hydrogen peroxide (H2O2), which oxidize pollutants. H2O2 can be electrogenerated in situ by the oxygen reduction reaction (ORR) in the reaction medium. The use of highly porous gas diffusion electrodes (GDE) provides the supply of oxygen at the electrode/solution interface, which can increase the RRO speed. The use of modifiers such as quinones and azocompounds immobilized on the carbon matrix of GDE may increase H2O2 generation. Therefore, the organic modifiers Sudan Red 7B (SR7B), methyl-p-benzoquinone (MPB), anthraflavic acid (AA) and anthraquinone-2-carboxylic acid (A2CA) were added in different contents to carbon Printex L6 (CP) and microporous layers of these materials were studied by cyclic voltammetry and linear sweep voltammetry on a rotating ring- disc electrode (RRDE). Materials with 0.5% of SR7B and 5.0% of MPB increased the current efficiency for electrogeneration of H2O2 to 86.2 and 85.5%, respectively, in relation to pure CP that leaded to 82.8%. GDE of CP modified with 0.5% of SR7B were constructed with metallic screens on their outer faces and an application of current densities of 75, 100 and 150 mA cm-2 led to a greater electrogeneration of H2O2. At current densities of 75 mA cm-2, the modified GDE generated 1020.1 mg L-1 of H2O2 with energy consumption of 118.0 kWh kg-1 of H2O2, apparent kinetic constant of 37.3 mg L-1 min-1 and current efficiency of 17.9%, while GDE of pure CP generated lower H2O2 concentration; 717, 3 mg L-1, with higher energy consumption; 168.5 kWh kg-1, lower apparent kinetic constant; 21.4 mg L-1 min-1, and lower current efficiency; 12.6%. Therefore, the modified GDE could be applied in systems that require high generations of H2O2.

The interferon (IFN) response is a crucial component of cellular innate immunity, vital for controlling virus infections. Dysregulation of the IFN response however can lead to serious medical conditions including autoimmune disorders. Modulators of IFN induction and signalling could be used to treat these diseases and as tools to further understand the IFN response and viral infections. We have developed cell-based assays to identify modulators of IFN induction and signalling, based on A549 cell lines where a GFP gene is under the control of the IFN-β promoter (A549/pr(IFN-β).GFP) and the ISRE containing MxA promoter (A549/pr(ISRE).GFP) respectively. The assays were optimized, miniaturized and validated as suitable for HTS by achieving Z' Factor scores >0.6. A diversity screen of 15,667 compounds using the IFN induction reporter assay identified 2 hit compounds (StA-IFN-1 and StA-IFN-4) that were validated as specifically inhibiting IFNβ induction. Characterisation of these molecules demonstrated that StA-IFN-4 potently acts at, or upstream, of IRF3 phosphorylation. We successfully expanded this HTS platform to target viral interferon antagonists acting upon IFN-signalling. An additional assay was developed where the A549/pr(ISRE).GFP.RBV-P reporter cell line constitutively expresses the Rabies virus phosphoprotein. A compound inhibiting viral protein function will restore GFP expression. The assay was successfully optimized for HTS and used in an in-house screen. We further expanded this assay by placing the expression of RBV-P under the control of an inducible promoter. This demonstrates a convenient approach for assay development and potentiates the targeting of a variety of viral IFN antagonists for the identification of compounds with the potential to develop a novel class of antiviral drugs.

Increasing environmental awareness has driven a lot of research to look into various environmentally friendly lubricants which can replace more conventional mineral oil based lubricants. This is true in particular for marine and hydropower applications where the risk of lubricant leakage can be damaging to the local environment. Glycerol is an organic compound produced as a byproduct when producing Biodiesel. It is environmentally friendly and has been used by the pharmaceutical and food industries for a long time. Recent research has shown that glycerol has very good tribological properties and can be used as a lubricant in some applications. However, its high viscosity and high static friction are disadvantageous and needs improvement. The purpose of this study is to investigate possible surface active environmentally adapted additives in glycerol and water solutions. 14 additives have been selected for testing and were tested in a pin-on-disc start-stop friction test to see their effect on the static and dynamic friction coefficients. From these 14 additives two were selected due to their superior performance and were further studied. The effect of concentration of water and additive in glycerol was also investigated using the same test conditions. A phosphor based additive has been found to be the best performing.

Les cellules stromales mésenchymateuses (CSM) sont des cellules dotées de nombreuses propriétés dont les plus importantes sont leur rôle de soutien de l’hématopoïèse, leur potentiel de différenciation multilignée et leurs pouvoirs immunomodulateurs. Grâce à ces propriétés et à leur facilité d’obtention et d’amplification ex vivo, les CSM sont des candidats prometteurs pour diverses applications thérapeutiques. Au cours de ce travail, nous avons caractérisé ces pouvoirs immunomodulateurs et étudié les mécanismes sous-jacents.<p><p>Nous avons dans un premier temps, évalué la capacité des CSM de la MO à moduler la prolifération des lymphocytes T purifiés à partir de sang périphérique (SP) ou de sang de cordon ombilical (SCO). Quel que soit le stimulus utilisé pour les activer, les lymphocytes T du SP ou du SCO sont modulés par les CSM d’une manière dose dépendante. Le profil d’inhibition des lymphocytes T du SP ou du SCO par les CSM est différent et vraisemblablement lié à leur composition cellulaire (rapport T naïfs vs mémoires).<p><p>Dans le but de comprendre les mécanismes impliqués dans l’immunomodulation et l’influence de l’environnement sur les CSM, nous nous sommes intéressés à l’expression des molécules d’adhésion et de la galectine 1 ainsi qu’à leurs rôles dans l’immunomodulation. Lors des co-cultures avec les lymphocytes T, il y a augmentation de l’expression du CD54, du CD58 et de la sécrétion de la galectine 1 alors qu’en présence d’un environnement inflammatoire ou infectieux, celles-ci sont différemment modulées. Nous avons ensuite pu démontrer que l’inhibition de la réponse lymphocytaire par les CSM impliquait notamment la galectine 1 comme facteur immunorégulateur.<p><p>Le troisième volet de cette thèse, s’est intéressé à l’étude et à la comparaison du pouvoir immunomodulateur des CSM issues du tissu adipeux et la gelée de Wharton, considérés comme des sources potentiellement alternatives à la MO. L’immunomodulation exercée sur les réponses immunes est indépendante de l’origine des CSM. Les CSM du tissu adipeux et de la gelée de Wharton inhibent l’activation des lymphocytes mise en évidence par l’expression du CD38. La réponse allogénique ou mitogénique des lymphocytes est réduite en présence de CSM et les sous populations (CD4+ et CD8+) sont affectées de la même manière par ces effets suppresseurs. Ces effets sont dépendants des concentrations en CSM et sont vraisemblablement liés à l’expression de la PGE2 et du LIF. Durant les co-cultures, les Tregs sont expansés et cela indépendamment des concentrations en CSM. <p><p>En résumé, nous avons caractérisé le pouvoir immunomodulateur des CSM issues de trois sources différentes à savoir la moelle osseuse, la gelée de Wharton et le tissu adipeux. Comme le mettent en évidence nos observations, ce pouvoir est clairement dépendant de la concentration en CSM utilisée et est fortement sensible à l’environnement auquel les CSM sont exposées. Sur le plan mécanistique, nous avons démontré la participation de la galectine 1, de la PGE2 et du LIF aux fonctions immunosuppressives des CSM. Nous rapportons également la capacité des CSM à promouvoir l’expansion des Tregs aussi bien au sein d’une population lymphocytaire que fraîchement purifiés. Nos travaux soulignent l’importance et l’avantage de l’utilisation des CSM issues de ces nouvelles sources dans le cadre des thérapies immunes.<p> / Doctorat en Sciences biomédicales et pharmaceutiques / info:eu-repo/semantics/nonPublished

Posttranslational modification (PTM) of proteins is essential to maintain homeostasis and viability in all eukaryotic cells. Hence, besides the sequence and 3D folding of a polypeptide, modification by multiple types of PTMs, ranging from small molecular groups to entire protein modules, adds another layer of complexity to protein function and regulation. The ubiquitin-like modifiers (UBLs) are such a group of evolutionary conserved protein modifiers, which by covalently conjugating to target proteins can modulate the subcellular localization and activity of their targets. One example of such a UBL, is the Ubiquitin related modifier 1 (Urm1). Since its discovery in 2000, Urm1 has been depicted as a dual function protein, which besides acting as a PTM, in addition functions as a sulfur carrier during the thio-modification of a specific group of tRNAs. Due to this dual capacity, Urm1 is considered as the evolutionary ancestor of the entire UBL family. At present, it is well established that Urm1, with help of its dedicated E1 enzyme Uba4/MOCS3, conjugates to multiple target proteins (urmylation) and that Urm1 thus plays important roles in viability and the response against oxidative stress. The aim of this thesis has been to, for the first time, investigate the role of Urm1 and Uba4 in a multicellular organism, utilising a multidisciplinary approach that integrates Drosophila genetics with classical biochemical assays and proteomics. In Paper I, we first characterized the Drosophila orthologues of Urm1 (CG33276) and Uba4 (CG13090), verified that they interact physically as well as genetically, and that they together can induce urmylation in the fly. By subsequently generating an Urm1 null Drosophila mutant (Urm1n123), we established that Urm1 is essential for viability and that flies lacking Urm1 are resistant to oxidative stress. Providing a molecular explanation for this phenotype, we demonstrated an involvement of Urm1 in the regulation of JNK signaling, including the transcription of the cytoprotective genes Jafrac1 and gstD1. Besides the resistance to oxidative stress, we have moreover (Manuscript IV) made an in-depth investigation of another phenotype displayed by Urm1n123 mutants, an overgrowth of third instar larval neuromuscular junctions (NMJs), a phenotype which is shared also with mutants lacking Uba4 (Uba4n29). To increase the understanding of Urm1 in the fly, we next employed a proteomics-based approach to identify candidate Urm1 target proteins (Paper II). Using this strategy, we identified 79 Urm1-interacting proteins during three different stages of fly development. Of these, six was biochemically confirmed to interact covalently with Urm1, whereas one was found to be associated with Urm1 by non-covalent means. In Manuscript III, we additionally identified the virally encoded oncogene Tax as a target of Urm1, both in Drosophila tissues and mammalian cell lines. In this study, we established a strong correlation between Tax urmylation and subcellular localization, and that Urm1 promoted a cytoplasmic accumulation and enhanced signalling activity of Tax, with implications for a potential role of Urm1 in Tax-induced oncogenesis. Taken together, this thesis provides a basic understanding of the potential roles and targets of Urm1 in a multicellular organism. The four studies included cover different aspects of Urm1 function and clearly points towards a highly dynamic role of protein urmylation in fly development, as well as in adult life.

Syftet med detta examensarbete var att utveckla ett hållbart ersättningsmaterial till akrylnitrilbutadienstyren plast (ABS), genom att applicera principerna för grön kemi och teknik. ABS är en icke-nedbrytbar plast som till exempel används i slagtåliga produkter för hyttinteriörer. Att utveckla ett nytt material baserat på en kravspecifikation med en specifik produkt i åtanke är av stor betydelse då en initial teoretiska utvärdering kan ge resultat som driver ytterligare innovation och säkerställer en god överensstämmelse med förväntningarna på produkten. Baserat på den genomförda litteraturutvärderingen och kravspecifikationen för produkten valdes polylaktid (PLA) som matrismaterial och blandades med nanofibrer av lignocellulosa (LCNF) och naturgummi (NR), där maleinsyraanhydrid (MA) användes som kompatibilisator. Denna modifieringsstrategi syftade till att förbättra PLAs styrka och minska dess sprödhet. Flera olika parametrar undersöktes, vilka inkluderar olika torkningsmetoder för LCNF:en och olika metoder för MA tillsats före bearbetningen av blandningen. Termisk analys av blandningarna visade att tillsatsen av LCHF och NR inte påverkar nedbrytningstemperaturen för PLA-matrisen i någon större utsträckning, men att kristalliniteten påverkades av dem och de olika behandlingsmetoderna. Styvheten hos de PLA-baserade materialen var likvärdig ABS, medan elasticitet var generellt likvärdig PLA och där tillsatsen av naturgummi förbättrade materialens deformationskapacitet. SEM bilder indikerade att de tre komponenterna var kompatibiliserade, då fibrösa strukturer och sammanflätade nätverk av LCNF och NR i PLA-matrisen kunde observeras. SEM bilderna visade också att NR agglomererade då stora agglomerat och porösa strukturer uppstod, vilket understryker vikten av att optimera framtida blandningsstrategier. En livscykelbedömning (LCA), enligt en vagga-till-graven metod, förväntas visa lägre koldioxidutsläpp för det föreslagna alternativet jämfört med ABS tack vare tillämpningen av principerna för grön kemi vid produktutformningen. Detta bekräftar den ursprungliga hypotesen om en ökad miljövänligheten hos PLA-baserade ersättningsmaterial jämfört med ABS. / This thesis aims to develop sustainable replacement for Acrylonitrile Butadiene Styrene (ABS) in high-impact applications within construction equipment’s Cab interior. Adhering to the principles of Green Chemistry and Engineering, the study focused on developing and accessing an environmentally friendly substitute for ABS, a commonly used non-biodegradable plastic. Investigating novel materials with a tailored requirements list is vital in materials science and engineering. Theoretical approaches can yield results which drive further innovation, ensuring comprehensive alignment with application expectations through a holistic approach to address critical factors. Following this guideline, the chosen alternative was Polylactide (PLA), fortified with a blend of lignocellulose nanofibers (LCNFs) and natural rubber (NR) at a 10 wt.% concentration, with the addition of Maleic Anhydride (MA) as a compatibilizer. This modification strategy aimed to enhance PLA's strength and reduce its brittleness. The investigation encompassed various parameters, including different LCNF drying methods and variations in additive treatment before melt-mixing with PLA. The outcomes from thermal analysis indicated that the inclusion of reinforcements does not significantly affect the degradation temperature of the PLA matrix. Crystallinity, on the other hand, was found to be influenced by the presence of lignocellulose reinforcements and natural rubber, with intriguing nuances emerging from the interplay of these components and different treatment methods. PLA-based alternatives performed similarly to low grade ABS and had similar stiffness levels. In terms of elasticity, most materials behaved similarly to neat PLA, but the addition of natural rubber enhanced their deformation capacity. Successful compatibilization between lignocellulose reinforcements, natural rubber, and PLA was assumed from the observed fibrous structures and interwoven networks within the PLA matrix. Additionally, the presence of aggregates and porous structures highlighted the challenges posed by rubber agglomeration. Finally, the observation of larger agglomerates beyond typical interphase sizes raised concerns about brittle behavior, emphasizing the need for optimizing blend toughening strategies. The input for a Life Cycle Assessment (LCA), following a cradle-to-gate approach, is anticipated to show lower carbon emissions for the proposed alternative in comparison to ABS due to the principles of Green Engineering applied in the product design, denoting the environmental viability of the PLA-based substitute.

[pt] Dentre os aditivos empregados nas formulações de óleos lubrificantes, cabe destacar os de natureza polimérica, utilizados como melhoradores de viscosidade. Atualmente, testes complexos e de alto custo são empregados para avaliação de novos componentes nos óleos lubrificantes. Portanto, análises preliminares para estudo e caracterização de aditivos são de extrema relevância. Este trabalho tem como objetivo caracterizar diferentes polímeros, utilizados como modificadores de viscosidade, empregando métodos de análise térmica e reológica, e ainda avaliar o impacto destes aditivos em bases lubrificantes. Os resultados encontrados permitem avaliar o comportamento das borrachas poliméricas frente à degradação térmica, influenciada pelo processo de polimerização e estrutura química, e frente ao seu comportamento reológico mostrando ser uma metodologia eficiente para diferenciação destes materiais. As bases lubrificantes avaliadas mostraram um comportamento de fluido newtoniano clássico e quando os polímeros modificadores foram adicionados, em determinadas concentrações, observou-se uma alteração deste comportamento de fluido. As análises e técnicas empregadas permitiram avaliar o impacto no comportamento reológico dos óleos básicos bem como das soluções preparadas com diferentes concentrações de polímeros. Foi possível concluir que os aditivos poliméricos empregados em bases lubrificantes são capazes de alterar o comportamento térmico e reológico das bases lubrificantes estudadas. As metodologias empregadas se mostraram eficientes para avaliação preliminar destes polímeros e das bases lubrificantes contendo estes aditivos. / [en] The most important additives used in lubricant formulas are polymeric in nature, which play an important role in the performance of the fluid and act as a viscosity modifier. Due to the fact that lubricants with lower viscosities are higher in demand, the viscosity modifier function has become increasingly important and differential in lubricant formulas. In order to develop new components of technology for lubricants, complex tests, which are high in cost, are necessary. Therefore, preliminary analyses of new studies and the characterization of new data are extremely relevant and important for the customization of the process and timing. The intention is to characterize polymers available on the market as viscosity modifiers using thermal and rheological methodologies, as well as to have a better understanding of the influence of these additives on base oils used in lubricants. The results showed the polymers behaviors on thermal degradation, which are influenced by the polymerization process as well as chemical structure. Rheological analyses demonstrated to be an efficient methodology for the differentiation of these materials. Base oil study results showed the Newtonian fluid behavior and this was modified when substantial amount of polymers were added. The rheological and thermal behaviors of base oils as well as solutions with polymers in different treatment rates were realized by the analyses and techniques executed. For the preliminary evaluations of polymer additives and base oils with them, the methodologies used in this study proved to be efficient.

[pt] No presente trabalho é proposto o desenvolvimento de um método analítico para determinação de S por espectrometria de absorção molecular de alta resolução com fonte contínua e forno de grafite (HR-CS GF MAS). As amostras foram preparadas por dissolução ácida e os padrões de calibração, assemelhados à matriz da amostra dissolvida, contendo sulfato, tioureia ou L-cisteína foram estudados em função de suas diferentes estabilidades térmicas. A técnica de HR-CS GF MAS é uma alternativa interessante para determinação de S, pois apresenta alta resolução espectral que minimiza interferências espectrais, pelo uso de um monocromador de alta resolução que permite a separação das linhas de absorção molecular do analito e da matriz, pelo uso do forno de grafite como fonte de atomização, que permite a separação da matriz e do analito antes da etapa de medida do sinal analítico. Com isso, este trabalho tem por objetivo desenvolver um método analítico para determinação de S em amostras de cabelo por HR-CS GF MAS, a fim de avaliar os níveis deste elemento no organismo e compará-los com os resultados obtidos por ICP OES. As condições escolhidas para temperatura de pirólise e de vaporização foram 1000 graus C e 2400 graus C, respectivamente, utilizando 800 microgramas de W, como modificador permanente, e 15 microgramas e 10 microgramas, respectivamente, de uma mistura de Pd(mais)Mg, como modificador em solução. O valor determinado para a concentração de S no material certificado de referência NCS DC73347a (cabelo humano) está de acordo com o descrito em seu certificado, bem como as concentrações de S determinadas em 14 amostras de cabelo, que estão em concordância com as determinadas por ICP-OES de acordo com teste t-pareado (95 por cento de confiança), o que comprova a boa exatidão do método proposto. / [en] In the presented work it is proposed the development of an analytical method for sulfur determination by high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS). The samples were prepared by acid dissolution and the calibration standards containing sulfate, thiourea, L-cysteine were studied as a function of their different thermal stabilities and its capability for matrix matching. The HR-CS GF MAS technique is an interesting alternative for sulfur determination, since its capability to perform an interference-free analysis due to its high resolution monochromator that allows to overcome the spectral overlapping and by the use of the graphite furnace as atomizer which minimizes the matrix effects before the analytical measurement. The aim of this work is to develop an analytical method for sulfur determination in hair samples by HR-CS GF MAS, in order to evaluate the levels of this element in the human body and to compare them with the results obtained by ICP OES. The chosen conditions for pyrolysis and vaporization temperatures were 1000 C degrees and 2400 C degrees, respectively, using 800 micrograms of W as permanent modifier combined with 15 micrograms and 10 micrograms, respectively, of Pd(plus)Mg mixture as modifier in solution. The value determined for S concentration in the certified reference material NSC DC73347a (human hair) was in agreement with those reported in its certificate, as well as sulfur concentrations determined in 14 hair samples, which are in agreement with those determined by ICP-OES according to the t-paired test (95 percent level of confidence), which proves the good accuracy of the proposed method.