Atmospheric formaldehyde (H2CO) is an intermediate product common to the degradation of many volatile organic compounds and therefore it is a central component of the tropospheric chemistry. While the global formaldehyde background is due to methane oxidation, emissions of non-methane volatile organic compounds (NMVOCs) from biogenic, biomass burning and anthropogenic continental sources result in important and localised enhancements of the H2CO concentration. Recent spaceborne nadir sensors provide an opportunity to quantify the abundance of tropospheric formaldehyde at the global scale, and thereby to improve our knowledge of NMVOC emissions. This is essential for a better understanding of the processes that control the production and the evolution of tropospheric ozone, a key actor in air quality and climate change, but also of the hydroxyl radical OH, the main cleansing agent of our troposphere. For this reason, H2CO satellite observations are increasingly used in combination with tropospheric chemistry transport models to constrain NMVOC emission inventories in so-called top-down inversion approaches. Such inverse modelling applications require well characterised satellite data products consistently retrieved over long time periods.<p>This work reports on global observations of formaldehyde columns retrieved from the successive solar backscatter nadir sensors GOME, SCIAMACHY and GOME-2, respectively launched in 1995, 2002 and 2006. The retrieval procedure is based on the differential optical absorption spectroscopy technique (DOAS). Formaldehyde concentrations integrated along the mean atmospheric optical path are derived from the recorded spectra in the UV region, and further converted to vertical columns by means of calculated air mass factors. These are obtained from radiative transfer simulations, accounting for cloud coverage, surface properties and best-guess H2CO profiles, the latter being derived from the IMAGES chemistry transport model. A key task of the thesis has consisted in the optimisation of the H2CO retrieval settings from multiple sensors, taking into account the instrumental specificities of each sounder. As a result of these efforts, a homogeneous dataset of formaldehyde columns covering the period from 1996 to 2010 has been created. This comes with a comprehensive error budget that treats errors related to the spectral fit of the columns as well as those associated to the air mass factor evaluation. The time series of the GOME, SCIAMACHY and GOME-2 H2CO observations is shown to be consistent and stable over time. In addition, GOME-2 brings a significant reduction of the noise on spatiotemporally averaged observations, leading to a better identification of the emission sources. Our dataset is used to study the regional formaldehyde distribution, as well as its seasonal and interannual variations, principally related to temperature changes and fire events, but also to anthropogenic activities. Moreover, building on the quality of our 15-year time series, we present the first analysis of long-term changes in the H2CO columns. Positive trends, in the range of 1.5 to 4% yr-1, are found in Asia, more particularly in Eastern China and India, and are related to the known increase of anthropogenic NMVOC emissions in these regions. Finally, our dataset has been extensively used in several studies, in particular by the BIRA-IASB modelling team to constrain NMVOC emission fluxes. The results demonstrate the high potential of satellite data as top-down constraint for biogenic and biomass burning NMVOC emission inventories, especially in Tropical ecosystems, in Southeastern Asia, and in Southeastern US. <p><p>Le formaldéhyde (H2CO) joue un rôle central dans la chimie de la troposphère en tant que produit intermédiaire commun à la dégradation chimique de la plupart des composés organiques volatils dans l’atmosphère. L’oxydation du méthane est responsable de plus de la moitié de la concentration moyenne globale du formaldéhyde. Sur les continents en revanche, les hydrocarbures non-méthaniques (NMVOCs) émis par la végétation, les feux de biomasse et les activités humaines, augmentent de façon significative et localisée la concentration de H2CO. Les récents senseurs satellitaires à visée nadir offrent la possibilité de quantifier à l’échelle globale l’abondance du formaldéhyde dans la troposphère et de ce fait, d’améliorer notre connaissance des émissions de NMVOCs. Ceci est essentiel à la compréhension des mécanismes contrôlant la production et l’évolution de l’ozone troposphérique, élément clé pour la qualité de l’air et les changements climatiques, mais aussi du composé hydroxyle OH, le principal agent nettoyant de notre troposphère. C’est pourquoi, une méthode de plus en plus répandue pour améliorer les inventaires d’émissions des NMVOCs consiste en l’utilisation d’observations satellitaires de H2CO en combinaison avec un modèle de chimie et de transport troposphérique, dans une approche appelée modélisation inverse. Ce genre d’application demande des produits satellitaires bien caractérisés et dérivés de façon cohérente sur de longues périodes de temps.<p>Le travail présenté dans ce manuscrit porte sur l’inversion des colonnes de formaldéhyde à partir de spectres de la radiation solaire rétrodiffusée par l’atmosphère terrestre, mesurés par les senseurs GOME, SCIAMACHY et GOME-2, lancés successivement en 1995, 2002 et 2006. La méthode d’inversion est basée sur la spectroscopie d’absorption optique différentielle (DOAS). Les concentrations de formaldéhyde intégrées le long du chemin optique moyen dans l’atmosphère sont dérivées à partir des spectres mesurés, et ensuite transformées en colonnes verticales par le biais de facteurs de conversion appelés facteurs de masse d’air. Ces derniers sont calculés à l’aide d’un modèle de transfert radiatif, en tenant compte de la présence de nuages, des propriétés de la surface terrestre et la distribution verticale supposée du formaldéhyde, fournie par le modèle IMAGES. Un des objectifs principaux de la thèse a été d’optimiser les paramètres d’inversion pour H2CO, et ceci pour les trois senseurs, tout en tenant compte des spécificités de chaque instrument. Ces efforts ont conduit à la création d’un jeu de données homogène, couvrant la période de 1996 à 2010. Les colonnes sont fournies avec un bilan d’erreur complet, incluant les erreurs liées à l’inversion des concentrations dans les spectres, ainsi que celles provenant de l’évaluation des facteurs de masse d’air. La série temporelle des observations de GOME, SCIAMACHY et GOME-2 présente une bonne cohérence et stabilité sur toute la période. Nous montrons aussi que la meilleure couverture terrestre de GOME-2 entraîne une réduction significative du bruit sur les observations moyennées, permettant une meilleure identification des sources d’émission. Notre jeu de données est exploité pour étudier la distribution régionale du formaldéhyde, ainsi que ses variations saisonnières et interannuelles, principalement liées aux variations de température et aux feux de végétation, mais aussi aux activités anthropiques. De plus, en s’appuyant sur la qualité de la série temporelle de 15 ans, nous présentons la première analyse des variations à long terme des concentrations de H2CO. Des tendances positives, de l’ordre de 1.5 à 4% par an, sont observées en Asie, en particulier dans l’est de la Chine et en Inde, liées à l’augmentation des émissions anthropiques d’hydrocarbures dans ces régions. Finalement, nos données ont été largement exploitées par le groupe de modélisation de l’IASB pour faire des études de modélisation inverse des émissions de NMVOCs. Les résultats démontrent le haut potentiel des données satellitaires pour contraindre les inventaires d’émissions dues à la végétation et aux feux de biomasse, particulièrement dans les écosystèmes tropicaux, en Asie du sud-est, et dans le sud-est des Etats-Unis. / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

Thesis (PhD (Chemistry and Polymer Science)--University of Stellenbosch, 2009. / The work presented in this dissertation describes the development of self-healing coatings based on thiol-ene chemistry. The approach was to synthesize capsules with thiol and ene compounds separately encapsulated. These capsules were embedded in various coating formulations and upon the formation of a crack with a razor blade, these capsules ruptured. This caused the healing agent to flow into the crack via capillary action and the thiol-ene healing mechanism was initiated. This resulted in recovery of the damaged coating and provided continued protection to the substrate. Pentaerythritol tetrakis(3-mercaptopropionate) (TetraThiol), 1,6-hexanediol diacrylate (DiAcrylate) and 1,6-hexanediol di-(endo, exo-norborn-2-ene-5-carboxylate) (DiNorbornene) are the thiol and ene compounds used in this study. Kinetic experiments indicated that both TetraThiol-DiAcrylate and TetraThiol-DiNorbornene monomer pairs undergo rapid polymerization and form a network within minutes upon exposure to UV radiation and with the addition of a photoinitiator. The TetraThiol-DiNorbornene monomer pair also showed a high rate of polymerization without the addition of a photoinitiator and/or exposure to UV radiation. Styrene-maleic anhydride (SMA) copolymers and chain-extended block copolymers with styrene (P[(Sty-alt-MAh)-b-Sty]) were synthesized via Reversible Addition-Fragmentation chain Transfer (RAFT)- mediated polymerization. These copolymers were used as surfactant in miniemulsification for the synthesis of core-shell particles with TetraThiol as the core material. It appeared that P[(Sty-alt-MAh)-b-Sty] block copolymers, sterically stabilized via the addition of formaldehyde, provide optimal stability to the core-shell particles. DiNorbornene is encapsulated via miniemulsion homopolymerization of styrene and well-defined, stable nanocapsules were obtained. TetraThiol and DiAcrylate microcapsules were synthesized via in-situ polymerization of urea and formaldehyde. Microcapsules with a particle size of one to ten micrometers and with a very smooth surface were obtained. These microcapsules and nanocapsules were embedded in poly(methyl acrylate) (PMA), styrene-acrylate and pure acrylic films and the self-healing ability of these coatings, after introduction of a crack with a razor blade, was assessed.

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Lors de cette étude, différentes recherches ont été effectuées sur l'utilisation de divers matériaux naturels comme source de matière premières pour la fabrication de colles vertes pour l'industrie de panneau. Dans ce contexte, le travail a consisté à : (i) Evaluer le potentiel de différents tannins en provenance de déchets d'écorces et développer des colles à base de tanins avec différents durcisseurs.(ii) Evaluer le potentiel de lignines de différentes origines et développer des colles à base de tannin de mimosa et de lignine. (iii) Développer des colles à base de tannin et de protéine de gluten.(iv) Evaluer les émissions de formaldéhyde et d'autres composés organiques volatiles (COV) à partir de panneaux de particules fabriqués avec les colles naturelles mises au point précédemment.Les techniques d'analyses thermomécaniques, de spectroscopie CP-MAS 13C NMR, de matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF) et de temps de gel ont été utilisées comme méthodes de travail pour l'évaluation et la caractérisation de ces colles. Les essais de cohésion interne pour l'évaluation de la résistance mécanique de la colle selon la norme EN -312 ont également été effectués.En ce qui concerne les émissions de formaldéhyde et des autres COV à partir de panneaux contentant des colles vertes, le recours à des techniques normalisées par chromatographie en phase gazeuse associée à un spectromètre de masse (GC-MS) et par chromatographie en phase liquide (HPLC) ont été privilégiées. / This study deals with some researches carried out about the use of various natural materials as a source of raw material for the manufacturing of green adhesives for the industry of panel. In this context, work consisted in:(i) Evaluation of the potential of various tannins coming from barks wastes and development of adhesives containing tannins and various hardeners.(ii) Evaluation of the lignin potential from various origins and development of adhesives containing tannin from mimosa and lignin.(iii) Development of adhesives containing tannin and gluten protein.(iv) Evaluation of formaldehyde and other volatile organic compounds (VOC) from particleboards manufactures with the natural adhesives previously developed.Thermomechanical analyses, spectroscopy CP-MAS 13C NRM, matrix- assisted laser desorption/ionization mass spectroscometry (MALDI-TOF) and gelling time techniques were performed for evaluation and characterization of these adhesives. Internal bond test for the evaluation of adhesives mechanical resistance according to the standard EN-312 were also carried out.Concerning formaldehyde and other VOC emissions from panels with green adhesives, the recourse to standardized techniques which are gas chromatography associated with a mass spectrometer (GC-MS) and high performance liquid chromatography (HPLC) were privileged.

Considerando a grande quantidade de resíduos sólidos, como a palha e o bagaço de cana, gerados devido às atividades agrícolas, procurou-se desenvolver um projeto que utilize esses resíduos para obtenção de produtos com maior valor agregado, visando atender às expectativas em termos econômicos e ambientais. O bagaço da cana é um resíduo gerado em grandes proporções no Brasil. O Estado de São Paulo instituiu uma lei que proíbe a prática da queimada, para fins de colheita, pelo fato de causar sérios problemas ambientais e danos à saúde da população das cidades produtoras de cana, tornando a palha mais um resíduo em abundância. O bagaço e agora a palha da cana são queimados em caldeiras para a geração de energia nas próprias usinas de açúcar e álcool. Os excedentes deste processo podem ser utilizados para a obtenção de produtos de maior valor agregado, desde polpas celulósicas bem como a produção de ligninas que podem ser utilizadas em resinas para fabricação de aglomerados. Para o uso integral da biomassa lignocelulósica é necessário fazer a separação de seus constituintes majoritários: celulose, hemicelulose e lignina. Neste trabalho, os processos de separação utilizados foram a polpação etanol-água e a técnica de explosão a vapor tendo a palha e o bagaço da cana como materiais de partida. As ligninas obtidas pelo processo etanol-água foram oxidadas em meio ácido sob condições diferentes para determinar as cinéticas da oxidação e as energias de ativação destas ligninas. Ligninas oxidadas apresentam fortes propriedades quelantes e podem ser aplicadas no tratamento de efluentes para remoção de metais pesados. A oxidação foi realizada em meio ácido acético utilizando o sitema catalítico Co/Mn/Br à 50, 80 e 115°C por 5 h. A energia de ativação calculada para as ligninas de bagaço e de palha apresentaram um valor de 23,4 kJ/mol e 34,2 kJ/mol, respectivamente, indicando que a lignina de palha é mais reticulada. O estudo cinético da oxidação foi avaliado por UV-Visível. Espectros de infravermelho de várias amostras de ligninas oxidadas foram submetidas à Analise por Componentes Principais (PCA). Os resultados mostraram suaves modificações na estrutura da lignina após a reação de oxidação. A lignina obtida pela técnica de explosão a vapor foi testada em resinas para fabricação de aglomerados, juntamente com resinas à base de farinha de soja e de tanino. Foram ainda fabricadas resinas utilizando o glioxal em substituição do formaldeído, que é um material tóxico. Lignina glioxilada foi adicionada à resina de farinha de soja glioxilada em substituição das resinas PF ou de isocianato (pMDI), visando uma maior utilização de material natural na resina. As formulações que continham 70 ou 80% de material natural apresentaram resultados dentro dos padrões exigidos. As resinas com 70% de material natural podem ser utilizadas em menor porporção na madeira e também podem ser utilizados tempos de prensagem menores, que são industrialmente significativos. A melhor formulação encontrada foi utilizando farinha de soja pré-cozida glioxilada (SG) com a adição de tanino e pMDI, onde as proporções de material foram SG/T/pMDI 54/16/30 (m/m) . / Considering the large amount of agricultural residues, such as straw and sugarcane bagasse, generated due to agricultural activities, we sought to develop a project that proposes the use of these residues to obtain products with higher value, to acchieve expectations in terms of cost and environment. Bagasse from sugarcane is a by-product generated in large proportions in Brazil. São Paulo State introduced a law which prohibits the practice of burning for harvesting because of causing serious environmental problems and damage to the health of the population of cities close to cane producers, making straw an other abundant residue. Sugarcane bagasse and straw are burned in boilers for generation of energy in sugar and alcohol industries. However, excess of those by-products could be used to obtain products with higher value, as cellulosic pulps with applications in cardboard packing and the application in resins for the manufacture of particleboard. For the integral use of the vegetable biomass it is necessary separate the major components: cellulose, hemicellulose and lignin, and for this purpose ethanol-water pulping and steam explosion process were used, with the sugarcane bagasse and straw. Lignins obtained by ethanol-water pulping were oxidized in acidic medium under different conditions to study kinetics of the oxidation and calculate the activation energies of these lignins. Oxidized lignins presents very strong chelating properties and could be applied in effluents treatments for heavy metals removal. The oxidation of lignins were performed using acetic acid and Co/Mn/Br catalytical system at 50, 80 and 115°C for 5 h. Activation energy (Ea) was calculated for lignins from sugarcane bagasse and straw and presented Ea of 34.4 kJ.mol-1 and 23.3 kJ.mol-1, respectively, indicating higher crosslinked formation for straw. A kinetic study of the oxidation was evaluated by UV/Visible. FTIR spectra of various samples of oxidized lignins were submitted to Principal Component Analysis (PCA). The results showed slight structure modifications in lignins after oxidation reaction. Lignin obtained by the steam explosion process was tested in resins for the manufacture of particleboards, together with resin-based soy flour and tannin. Resins were manufactured to substitute formaldehyde (a toxic material) with glyoxal. Glyoxalated lignins were added to glyoxalated soy flour in place of PF resins or the isocyanate (pMDI), aiming greater use of natural materials in resins. Adhesive resin formulations in which the total content of natural material is either 70 or 80% of the total resin solids content gave good results. The resins comprising 70% by weight of natural material can be used in a much lower proportion on wood chips and can afford pressing times fast enough to be significant under industrial panel pressing conditions. The best formulation of all the ones tried was the one based on glyoxalated precooked soy flour (SG), to which a condensed tannin was added in water solution and pMDI, where the proportions of the components SG/T/pMDI was 54/16/30 by weight.

Em razão do óleo diesel combustível automotivo, conter 2% de biodiesel e por não existir ainda regulamentação de emissões para os aldeídos dos veículos do ciclo Diesel, o presente trabalho teve como objetivo, avaliar as emissões de aldeídos dessa categoria de veículos, utilizando-se o óleo diesel com 2% de biodiesel (B2) e 100% de biodiesel de soja (B100) como combustível. Procurou-se também, avaliar as emissões de aldeídos de um veículo leve do ciclo Otto com e sem o conversor catalítico, a fim de comparar suas emissões com o veiculo do ciclo diesel, uma vez que o programa de controle da poluição do ar por veículos automotores estabeleceu limite de emissão de aldeídos totais, (formaldeído + acetaldeído) para os veículos leves novos do ciclo Otto, movidos a gasolina, etanol hidratado e suas misturas. Os ensaios foram realizados no laboratório de emissão veicular da CETESB em dinamômetro de chassi, seguindo um ciclo de condução urbano padronizado. Os aldeídos foram analisados por cromatografia líquida de alto desempenho. Os ensaios foram realizados com o veículo de marca Citröen modelo JUMPER 2.8 L ano/modelo 2006 para o ciclo Diesel e com o veículo de marca VW modelo FOX 1.6 Flex ano/modelo 2005 com e sem o conversor catalítico para o ciclo Otto. Nos ensaios realizados com o veículo JUMPER, além de medir as emissões de formaldeído e acetaldeído, mediu-se também as emissões de acroleína, propionaldeído, butiraldeído e benzaldeído. Observou-se na emissão, a presença de outras carbonilas e cetonas, tais como: crotonaldeído, metacroleína, 2-butanona, valeraldeído e p-tolualdeído, porém, essas carbonilas não foram quantificadas nesse estudo, em razão de não dispormos de padrões individuais certificados. Os ensaios demonstraram que com o uso do B2, as emissões de formaldeído variaram de 7,6 e 14,9 mg/km; o acetaldeído de 4,5 e 8,9 mg/km; a acroleína de 2,7 e 5,8 mg/km; o pr butiraldeído 0,4 e 0,7 mg/km e o benzaldeído de 0,2 e 0,3 mg/km, enquanto que com o uso do B100 as emissões de formaldeído variaram de 18,8 e 21,1 mg/km; o acetaldeído de 7,5 e 8,3 mg/km; a acroleína de 5,2 e 6,2 mg/km; o propionaldeído de 0,5 e 0,6 mg/km; o butiraldeído de 0,4 mg/km e o benzaldeído de 0,4 mg/km. Verificou-se que com o uso do B2, a emissão média foi de 48% para o formaldeído e 29% para o acetaldeído e representava 77% dos aldeídos totais (17,9 mg/km). Com o uso do B100, a emissão média foi de 57% para o formaldeído e 23% para o acetaldeído e representava 80% dos aldeídos totais (27,9 mg/km). Pode-se, observar nesse trabalho que a emissão média encontrada de 17,9 e 27,9 mg/km de aldeídos totais (formaldeído e acetaldeído) do veículo Diesel em relação à emissão do veículo Otto, não é desprezível, uma vez que o limite de emissão de aldeídos totais para os veículos leves fabricados a partir de 1997 era de 30,0 mg/km e passou a 20,0 mg/km para os veículos fabricados a partir de 2009, portanto, conclui-se que a realização de mais ensaios, inclusive em dinamômetro de motores e com outras categorias de veículos, contribuirá para detalhar o perfil das emissões de aldeídos da frota dos veículos a Diesel e biodiesel, além de determinar fatores de deterioração destes veículos, bem como ajudar no inventário de emissões destes poluentes. / Since of the automotive diesel fuel contains 2% biodiesel and there exists no regulation of emissions of aldehydes of Diesel cycle vehicles, this paper aims to evaluate the emissions of aldehydes of such a category of vehicles, using diesel oil with 2% biodiesel (B2) and 100% soybean biodiesel (B100) as fuel. It also aims to evaluate the emissions of aldehydes from a light Otto cycle vehicle with and without the catalytic converter in order to compare their emissions with the Diesel cycle vehicle, as the control program for air pollution by motor vehicles has set a limit of emissions of total aldehydes (formaldehyde + acetaldehyde) for new light Otto cycle vehicles, powered by gasoline, hydrated ethanol and its mixtures thereof. The tests were conducted in the vehicle emission laboratory of environmental sanitation agency (CETESB) on a chassis dynamometer, following a standard urban driving cycle. The aldehydes were analyzed by high performance liquid chromatography. The tests were conducted in a Citröen JUMPER 2.8 L vehicle model year/model 2006 for the Diesel cycle, a VW FOX 1.6 Flex vehicle model year/model 2005 with and without the catalytic converter for the Otto cycle. In the tests with the Jumper vehicle, the emissions of both formaldehyde and acetaldehyde, and acrolein, propionaldehyde, butyraldehyde and benzaldehyde were measured. It was possible to observe, the presence of carbonyl and other ketones, such as crotonaldehyde, methacrolein, 2-butanone, valeraldehyde and p-tolualdehyde. However these carbonyls were not quantified in this study, as there are no certified individual standards. The tests showed that by using B2, the emissions of formaldehyde ranged from 7.6 to 14.9 mg/km, acetaldehyde from 4.5 to 8.9 mg/km, acrolein from 2.7 to 5.8 mg/km, propionaldehyde from 0.4 to 0.6 mg/km, butyraldehyde from 0.4 to 0.7 mg/km, and benzaldehyde from 0.2 to 0.3 mg/km, while using B100 emissions of formaldehyde ranged from 18.8 to 21.1 mg/km, acetaldehyde from 7.5 to 8.3 mg/km, acrolein from 5.2 to 6.2 mg/km, propionaldehyde from 0.5 to 0.6 mg/km, butyraldehyde of 0.4 mg/km, and benzaldehyde of 0.4 mg/km. It was found that by using B2, the average emissions were 48% for formaldehyde and 29% for acetaldehyde, representing 77% of total aldehydes (17.9 mg/km). Using B100, the average emissions were 57% for formaldehyde and 23% for acetaldehyde, representing 80% of total aldehydes (27.9 mg/km). It was possible to observe in this study that the average emissions of 17.9 and 27.9 mg/km of total aldehydes (formaldehyde and acetaldehyde) of Diesel vehicle emissions in the Otto vehicle, are significant, since the emission limit of total aldehydes for light vehicles manufactured from 1997 was 30.0 mg/km and passed to 20.0 mg/km for vehicles manufactured from 2009. Therefore, it is possible to conclude that performing more tests, including engine dynamometer and other types of vehicles, will detail the profile of the aldehyde emissions from the fleet of vehicles powered by diesel and biodiesel, as well as determine factors for the deterioration of these vehicles and assist in the inventory of emissions of these pollutants.

A solução fixadora a partir do formaldeído permanece ate os dias de hoje como o composto fixador \"padrão ouro\" para trabalho de rotina. Porém, este é classificado como cancerígeno para os seres humanos e , portanto, representa um risco para qualquer pessoa manusear. Assim, a busca por substitutos tem sido motivada, e, mais recentemente, surgiram algumas soluções alternativas com potencial para substituí-lo. A maioria destas soluções alternativas são à base de álcool , e a maior parte delas são apenas para amostras microscópicas. A partir do conhecimento de ácido tânico para estabilizar a elastina e o colágeno, diluído em glutaraldeído, para microscopia eletrônica, bem como para próteses biológicas, emerge a ideia de uma nova solução fixadora alcoólica, contendo ácido tânico como componente principal. Em análises microscópicas coração, cérebro, intestino e rins foram coletados e preservados sendo armazenados em diferentes soluções fixadoras (10 % de formalina v/v, 70 % de álcool e solução alcoólica de ácido tânico), e preparado para procedimentos histológicos de rotina. Adicionalmente, ratos wistar inteiros foram fixados com a solução alcoólica de ácido tânico ou formalina e estudantes de medicina que praticam dissecção há pelo menos 2 anos ou mais, dissecaram estes espécimes durante o curso de dissecação, como uma alternativa para adquirir habilidades básicas de cirurgia e responderam a um questionário detalhado que inferia sobre a qualidade da peça a ser dissecada. A toxicidade do composto foi analisada por ensaio \"in silico\" para o sistema respiratório e a cutis. A análise microscópica mostrou que solução à base de ácido tânico pode ser melhor que os outros fixadores comuns testados diversos parâmetros, e houve diferença entre os tecidos analisados. Entretanto, o resultado microscópico mais importante foi que esta nova solução possui forte capacidade de preservar e estabilizar a elastina e o colágeno, demonstrando resultados melhores em relação aos outros fixadores. Os resultados macroscópicos revelaram também uma superioridade da solução de ácido tânico em diversos parâmetros analisados, como odor, textura e flexibilidade durante dissecção. A toxicidade da solução de ácido tânico para cútis e sistema respiratório foi considerada moderada em relação à formalina que é considerada altamente tóxica. Concluímos que a solução fixadora de ácido tânico é eficaz para macro e para microscopia, é menos tóxica do que o formaldeído e inodora. Portanto, pode ser uma alternativa real para a evitar a utilização de formol, diminuindo os fatores de risco durante a manipulação de cadáveres e tecidos fixados. / The fixative solution from the formaldehyde remains until nowadays as the \"gold standard\" for routine work fixative compounds. Nevertheless, it is classified as carcinogenic to humans and, therefore, represents a risk to anyone handling the solution. Thus, the search for formaldehyde substitutes has been motivated, and more recently, some alternative solutions with potential to replace it have appeared. Most of these alternative solutions are alcohol-based, and most of them are only for microscopic specimens. From the knowledge that tannic acid diluted in glutaraldehyde can stabilize elastin and collagen for electron microscopy as well as for bioprotheses, emerge the idea for a new alcoholic fixative solution, containing tanic acid as the main component. For microscopical analyses heart, brain, intestine and kidneys were collected and preserved in different fixative solutions (10% v/v regular formalin, 70% alcohol and tannic acid alcoholic solution), and prepared for routine histology procedures. Additionally, whole wistar rats were fixed in the tanic acid alcohol-based solution or formalin and medicine students, who practice dissection for at least 2 or more years, dissected the rats during the dissection course, as an alternative to acquire basic surgery skills and answered a detailed questionnaire about the quality of dissected specimen. The toxicity of the compound was analyzed by in silico tests for cutais and respiratory system. The microscopial analysis showed that tannic acid based solution could be better than others common fixatives as tested in several parameters, and there are differences among tissues. Moreover, the most important microscopic result was that this new solution showed a strong capability to preserve and stabilize elastin and collagen, shppwing better results in relation to other analysed fixatives. The macroscopial analyses also showed better results of tannic acid solution for several parameters, as odor, texture and flexibility during dissection. The toxicity of tannic acid solution for skin and respiratory system was considered moderate in relation to formaldehyde, which is considered highly toxic. We conclude that tanic acid solution is efficient to preserve tissues for macroand microscopical studies, is less toxic than formaldehyde and odorless. Therefore, it could be a real alternative to avoid the regular use of formalin, decreasing risk factors to the ones manipulating fixed corpses and tissues.

Les résines phénoliques de type résole présentent des propriétés applicatives et thermiques adaptées à l'élaboration de matériaux composites pour l'industrie aérospatiale. En particulier, ces résines peuvent être polymérisées en plusieurs étapes et présentent des propriétés de charbonnement très élevées. Seulement, ces résines sont principalement synthétisées à partir de formaldéhyde et de phénol. Ces précurseurs sont classés Cancérigène Mutagène Reprotoxique (CMR) respectivement de catégorie 1B et 2 et sont issus de ressources pétrolières. Du fait de cette classification CMR et de la raréfaction des ressources pétrolières, la société SAFRAN-Herakles souhaite substituer le formaldéhyde par des précurseurs non classés CMR et d'origine renouvelable. Les précurseurs aldéhyde aromatiques issus des lignines, 4-hydroxybenzaldéhyde, vanilline et syringaldéhyde, ne sont pas toxiques et peuvent être issus d'une ressource renouvelable abondante et bon marché, les lignines. Néanmoins, nous avons montré que ces trois précurseurs bio-sourcés ne sont pas réactifs en synthèse de résines résole. Nous avons également montré que le formaldéhyde doit être substitué par des précurseurs dialdéhyde aromatiques réactifs pour synthétiser des résines phénoliques avec d'excellentes propriétés de charbonnement. Ainsi, nous avons mis au point deux méthodes de fonctionnalisation pour transformer ces composés aldéhyde aromatiques bio-sourcés en de tels précurseurs dialdéhyde aromatiques réactifs. Les précurseurs obtenus ont ensuite été utilisés en synthèses de résines résole sans formaldéhyde et bio-sourcées. Après caractérisation de ces résines, nous avons enfin identifié des précurseurs donnant accès à des résines résole bio-sourcées avec des propriétés de charbonnement supérieures aux résines formophénoliques actuelles. En résumé, ces nouveaux précurseurs aldéhyde bio-sourcés représentent des alternatives prometteuses à l'usage de formaldéhyde pour la synthèse de résines résole avec des propriétés cibles pour des applications dans l'industrie aéropatiale. / Resol-type phenolic resins present applicative and thermal properties suitable for applications such as composite manufacture in aeropatial industry. Especially, resols can be polymerized stage-wise and present after curing high char yield properties. However, those resins are typically synthesized from formaldehyde and phenol. Those precursors are both classified as Carcinogenic Mutagenic Reprotoxic (CMR), respectively 1B and 2, and are petrobased. Because of this classification and of the fossil feedstock depletion, SAFRAN-Herakles wants to substitute formaldehyde by non-toxic and biobased aldehyde precursors. Aromatic aldehyde precursors such as 4-hydroxybenzaldehyde, vanillin and syringaldehyde are interestingly non-toxic and can be produced from the cheap and abundant lignins. Nevertheless, we have shown that those precursors are not reactive in resol synthesis conditions. Also, we have shown that difunctional and reactive aromatic aldehyde precursors are suitable for the synthesis of high char yield resins. Then, we have designed two functionalization methods to turn the biobased aldehyde precursors into difunctional and reactive ones. Finally, those precursors have been used for the synthesis of biobased resols without formaldehyde. Those new resins can be polymerized stage-wise and present higher char yield properties than the current formophenolic resins. Hence, those new biobased aldehyde precursors represent promising alternatives to formaldehyde for the synthesis of resols with target properties for aerospatial industry applications.

O objetivo deste estudo foi avaliar por meio de análises clínicas, radiográficas e histológicas o efeito do Laser de Baixa Intensidade na resposta pulpar de dentes decíduos humanos após pulpotomia. Vinte molares decíduos inferiores de 16 crianças com idade entre 6 e 9 anos foram criteriosamente selecionados. Os dentes foram randomizadamente divididos nos grupos Formocresol de Buckley diluído a 1/5 (Grupo I - FC), Hidróxido de Cálcio (Grupo II - HC), Laser de Baixa Intensidade + Óxido de Zinco e Eugenol (Grupo III - LBI+OZE) e Laser de Baixa Intensidade + Hidróxido de Cálcio (Grupo IV - LBI+HC), e tratados pela técnica convencional de pulpotomia em uma única sessão. As avaliações clínicas e radiográficas foram realizadas nos períodos de 3 e 6 meses do pós-operatório. Os dentes que se apresentavam em período normal de esfoliação foram extraídos, processados para análise histológica e avaliados por sistema de escores. Os resultados clínicos e radiográficos não mostraram diferença estatisticamente significativa nos grupos estudados (p>0,05). A análise estatística da avaliação histológica revelou diferença estatisticamente significativa para inflamação pulpar entre os Grupos I (FC) e IV (LBI+HC), sendo que o Grupo IV(LBI+HC) apresentou menor grau de inflamação pulpar. Em relação à fibras colágenas, formação de barreira de tecido mineralizado e camada odontoblástica houve diferença entre os Grupos I (FC) e II (HC), e entre os Grupos II (HC) e III (LBI+OZE), sendo que o Grupo II (HC) apresentou fibras colágenas densas, barreira de tecido mineralizado e camada odontoblástica. Os Grupos I (FC) e III (LBI+OZE), e os Grupos I (FC) e IV (LBI+HC), apresentaram diferença estatisticamente significativa para reabsorção interna. O Grupo I (FC) apresentou maior índice de reabsorção interna. Não houve diferença estatisticamente significativa entre os grupos para vitalidade pulpar, quantidade de vasos, calcificação pulpar e tecido de granulação. Com base nos resultados obtidos foi possível constatar que o Laser de Baixa Intensidade com Hidróxido de Cálcio mostrou efeitos clínicos e radiográficos mais satisfatórios, e melhores resultados histológicos em comparação aos demais grupos estudados. Desta forma, sugere-se que o Laser de Baixa Intensidade com hidróxido de Cálcio pode ser considerado uma técnica alternativa para pulpotomia de dentes decíduos humanos. / The aim of this study was to evaluate through clinical, radiographic and histological analyses the effect of Low-Level Laser therapy (LLLT) on pulpal response of human primary teeth after pulpotomy. Twenty mandibular primary molars of 16 children aged between 6 and 9 years were criteriously selected. The teeth were randomly divided into the following groups: Buckleys Formocresol (diluted 1:5) group I (FC), Calcium Hydroxide - group II (CH), Low-Level Laser therapy + Zinc Oxide and Eugenol - group III (LLLT+ZOE), and Low-Level Laser therapy + Calcium Hydroxide - group IV (LLLT+CH), and treated by the conventional pulpotomy technique at a single appointment. The clinical and radiographic evaluations were performed at 3 and 6 post-operative months. The teeth underwent normal exfoliation period were extracted and processed for histological analysis and assessed through a score system. The clinical and radiographic results did not show statistically significant difference among groups (p>0.05). The statistical analysis of the histological assessment revealed statistically significant difference for pulpal inflammation between groups I (FC) and IV (LLLT+CH), with the least degree of pulpal inflammation for group IV (LLLT+CH). Concerning to the collagen fibers, hard tissue barrier and odontoblastic layer, there were differences between groups I (FC) and II (CH), and between groups II (CH) and III (LLLT+ZOE). Group II (CH) showed dense collagen fibers, hard tissue barrier and odontoblastic layer. Groups I (FC) and III (LLLT+ZOE), and groups I (FC) and IV (LLLT+CH), presented statistically significant difference for internal resorption. Group I (FC) displayed the greatest internal resorption rate. There was not statistically significant difference among groups for pulpal vitality, amount of vessels, pulpal calcification and connective tissue. Based on the results obtained, it was possible to know that Low-Level Laser therapy with Calcium Hydroxide exhibited clinical and radiographic effects more satisfactory, and the best histological effects compared with the other groups studied. Therefore, it is suggested that Low-Level Laser therapy with Calcium Hydroxide can be considered as an alternative technique for the pulpotomy of human primary teeth.

A corrosão é um processo eletroquímico espontâneo e, sabendo que diversos metais estão sujeitos a este fenômeno, a sua deterioração é inevitável, o que impõe à comunidade científica desafios para retardar tal efeito. A literatura sobre o tema aponta como uma das ações mais recorrentes para alcançar esse retardo a aplicação superficial de películas poliméricas, dentre as quais destaca-se o desenvolvimento de revestimentos inteligentes. A incorporação na tinta de formadores de filmes encapsulados confere ao revestimento a característica de autorreparação, e a escolha de silanos como agentes reticulantes se destaca positivamente, uma vez que o filme gerado pela molécula apresenta caráter hidrofóbico. Nesse contexto, o objetivo deste estudo é verificar, primeiro, a melhor condição de reticulação do silano na presença de radiação ultravioleta e, segundo, se a adição de microcápsulas de poli(ureia-formaldeído-melamina) contendo metacriloxissilano em uma tinta epóxi base solvente confere a este revestimento proteção contra a corrosão, pelo efeito de autorreparação. Para isso, estudou-se a cinética de polimerização do formador de filme e o seu encapsulamento em microcápsulas de poli(ureia-formaldeído-melamina). Determinada a melhor condição de encapsulamento, corpos de prova de aço carbono foram pintados com a tinta contendo as microcápsulas produzidas. O efeito de autorreparação - desencadeado pela ruptura das microcápsulas ao se provocar um defeito mecânico no revestimento - foi comprovado pelas técnicas de espectroscopia de impedância eletroquímica (EIE), técnica de varredura por eletrodo vibratório (SVET) e por ensaio acelerado de corrosão em câmara de névoa salina. / Corrosion is a spontaneous electrochemical process and, knowing that several metals are subjected to this phenomenon, its deterioration is inevitable, which imposes challenges for scientific community to delay this effect. The literature on this subject points out, as one of the most recurrent actions to achieve this delay, the superficial application of polymer films, which stands out the development of smart coatings with self-healing properties. The incorporation of encapsulated film formers gives to coatings the self-healing ability, and the choice of silanes as film-forming agent stands out positively since the film has a hydrophobic character. In this context, the aims of this study are, firstly, verify the best crosslinking condition of silane induced by UV light and, secondly, investigate whether the addition of poly(urea-formaldehyde-melamine) microcapsules containing methacryloxysilane into the solvent-based epoxy coating brings protection to this coating against corrosion by self-healing effect. For this purpose, the polymerization kinetics of the film former by ultraviolet radiation and their encapsulation in poly(urea-formaldehyde-melamine) microcapsules were studied. Given the best encapsulation condition, carbon steel panels were coated with the self-healing paint. The self-healing effect - triggered by the rupture of the microcapsules caused by an induced mechanical defect in the coating - was demonstrated by techniques as electrochemical impedance spectroscopy (EIS), scanning vibrating electrode technique (SVET) and by accelerated corrosion tests in salt spray chamber.