Este trabalho objetivou o estudo de rotas de formação de metabólitos secundários utilizando precursores isotopicamente marcados com 13C. Os experimentos de crescimento com adição de [1-13C]acetato, [1,2-13C2]acetato e [U-13C315N1]-L-cisteína para o fungo do ambiente marinho Penicillium sp. DRF2 mostrou que as ciclotiocurvularinas são provenientes da rota de formação de policetídeos e pela incorporação de L-cisteína, depois da transformação desta em 3-mercaptopiruvato. Os resultados sugerem que a formação das ciclotiocurvularinas provém de um processo de detoxificação da α,β-desidrocurvularina. O estudo do metabolismo secundário de Aspergillus sp. DLM3-8, também do ambiente marinho, mostrou que o seu perfil metabólico produzido em experimentos de crescimento sob diferentes condições é constante. Os experimentos de incorporação de precursores isotopicamente marcados com 13C na naftoquinonaimina, produzida por Aspergillus sp. DLM3-8 foram inconclusivos, indicando que outras abordagens experimentais devem ser realizadas para se investigar a biossíntese deste metabólito. / This investigation aimed investigated the formation routes of secondary metabolites using 13C-labelled precursors. Feeding experiments with [1-13C]acetate, [1,2-13C2]acetate and [U-13C315N1]-L-cysteine within the growth medium of the marine-derived fungi Penicillium sp. DRF2 showed that cyclothiocurvularins are derived from polyketides and from the incorporation of a L-cysteine residue, after its transformation into 3-mercaptopyruvate. The results suggest that the formation of cyclothiocurvularins is derived from a detoxification process ofα,β-dehydrocurvularin. Investigation of the secondary metabolism of a marine-derived Aspergillus sp. DLM3-8 indicated a stable metabolic profile under a variety of growth conditions. Feeding experiments with 13C-labelled precursors for the biosynthesis investigation of naphthoquinoneimine were inconclusive, indicating that other methodologies should be envisaged in order to investigate the biosynthesis of this metabolite.

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The effect of HZSM-5 catalyst and NaOH pretreatment on the product distribution and bio oil properties from pyrolysis of cellulose, hemicellulose and lignin model compounds was investigated at 450 °C. NaOH pretreated and untreated cellulose was pyrolyzed on sand and the HZSM-5 catalysts; VPISU001 HZSM-5, BASF HZSM-5, and Sud-Chemie HZSM-5. The pyrolysis of cellulose on BASF and Sud-Chemie HZSM-5 catalysts increased the yields of the organic liquid fraction, total liquid and char while decreasing the gas yields. However the catalyst decreased the organic and char yields while increasing the water yields but there was no change in gas yields. The NaOH treatment caused a decrease in the organic and total oil yields relative to the control but the char yield increased. The change in gas yields was not significant. The characterization of the oils using FTIR and ¹³C−nmr showed that, the VPISU001 HZSM-5 with and without NaOH pretreatment caused elimination of the levoglucosan fraction while increasing the aromatic fraction. The NaOH pretreated cellulose pyrolyzed on sand reduced the levoglucosan groups while increasing the aromatic fraction of the bio oil. In the hemicellulose studies, birchwood xylan and NaOH treated xylan samples were pyrolyzed on sand and VPISU001 HZSM-5 catalyst. The organic liquid yields were very low and ranged from 3.3 wt% to 7.2 wt%, the water yields ranged from 17.8-25.7 wt%, the char yield were 17.8-25 wt% and gas yield were 40.9-49.6 wt%. The HZSM-5 catalysts increased the water and gas yields and produced the lowest char yield. NaOH pretreatment produced the lowest water yield while the char yield was the highest. The combined effect of NaOH pretreatment and HZSM-5 produced the lowest organic yield and highest char yield. The FTIR and ¹³C-nmr analyses of the organic liquids showed that the HZSM-5 catalyst promoted the formation of aromatic products, while the NaOH pretreatment promoted the formation of aliphatic hydrocarbons. The combined effect of NaOH pretreatment and HZSM-5 catalyst seem to promote the formation of anhydrosugars. The main gases evolved were CO, CO₂ and low molecular weight hydrocarbons. The HZSM-5 catalyst promoted CO formation while NaOH pretreatment promoted CO₂. The HZSM-5 catalyst produced the highest yield of low molecular weight hydrocarbon gases. The lignin and model compounds studies involved using low molecular weight kraft lignin, guaiacol, and syringol which were pyrolyzed on sand and VPISU001 HZSM-5 catalyst at 450 °C. The kraft lignin pyrolysis produced low liquid and gas yields and high char yields. The HZSM-5 catalysts increased the water yield and decreased the organic liquid yield. NaOH pretreatment increased the char yield and decreased the liquid products. NaOH and the HZSM-5 catalyst together decreased the char and increased the gas yields. The ¹³C-nmr and FTIR analysis showed that NaOH pretreatment promoted the formation of mainly guaiacol while the HZSM-5 catalyst formed different aromatic components. NaOH pretreatment promoted the formation of more CO₂ than CO whilst HZSM-5 catalyst promoted the formation of more CO than CO₂. Methane formation was enhanced by NaOH pretreatment. Other hydrocarbon gases were however enhanced by the HZSM-5 catalysts. Pyrolysis of the model compounds on the HSZM-5 catalyst showed an increase in pyrolytic water. The HZSM-5 catalyst promoted demethylation in syringol pyrolysis as compared to guaiacol. / Master of Science

The effects of adding a biodegradable litter amendment (AmmoSoak), developed from steam exploded corncobs, to poultry litter prior to pyrolysis on the product yields and qualities were investigated. Mixtures of litter and AmmoSoak were pyrolyzed in a bench-scale fluidized bed reactor. The objective of the second phase was to start-up a pilot-scale fluidized bed reactor unit. The poultry litter had a lower higher heating value (HHV), higher moisture, ash, nitrogen, sulfur, and chlorine contents than AmmoSoak. Analysis of the poultry litter indicated a mixture of volatiles, hemicelluloses, cellulose, lignin, ash, and proteins. AmmoSoak had a simpler composition than the litter; mainly hemicelluloses, cellulose, and lignin. Bench-scale studies indicated that adding AmmoSoak affected the yields and characteristics of the products. Addition of Ammosoak increased the bio-oil and syngas yields and decreased char yields. Adding AmmoSoak to the feed decreased the pH, water contents, initial viscosity, and the rate at which the viscosity increased with time, while densities and HHVs increased. The addition of Ammosoak to poultry litter also increased the carbon and oxygen contents of the boi-oils while nitrogen, hydrogen, sulfur, chlorine and ash contents decreased. A pilot-scale fluidized bed reactor was designed, constructed, installed and investigated for the pyrolysis of poultry litter. Fluidization and thermal equilibrium of the reactor were successfully demonstrated. The reactor was heated by combustion of propane. To ensure complete combustion, the combustion water was collected and compared to the stoichiometric yield. Complete combustion was achieved. Bio-oil yields on the pilot scale were lower than those obtained on the bench-scale pyrolysis unit. The water soluble fractions of the bio-oils were rich in oxygen. Water insoluble fractions were rich in carbon and ash. / Master of Science

No / In contrast with artefactual studies of long-distance trade and exchange in South Asia during the Prehistoric and Early Historic periods (Ardika et al . 1993; Gogte 1997; Krishnan and Coningham 1997; Tomber 2000; Gupta et al . 2001; Ford et al . 2005), few scientifically orientated analyses have focused on artefacts from the region¿s Historic period. During excavations at the ancient city of Anuradhapura, Sri Lanka, a number of buff ware ceramics with a putative organic coating on the interior were recovered (Coningham 2006). Dated stylistically to between the third and ninth centuries AD , analysis of the coatings using gas chromatography¿mass spectrometry (GC¿MS) and stable isotope analysis (carbon and deuterium) confirmed that the coatings are bitumen¿an organic product associated with petroleum deposits. There are no known bitumen sources in Sri Lanka, and biomarker distributions and isotopic signatures suggest that the majority of the samples appear to have come from a single bitumen source near Susa in Iran. The relationship between the bitumen coatings and the vessels is discussed, and it is suggested that the coatings were used to seal permeable ceramic containers to allow them to transport liquid commodities. This study enhances our knowledge of networks of trade and exchange between Sri Lanka and western Asia during Historic times.

Since the development of the ruthenium containing precatalysts Grubbs 1 (1) and Grubbs 2 (2), there was an increase in the development of new precatalysts. The NMR characterization could not cope with this. The NMR characterization mainly consists of 1H, 31P, COSY and rarely 13C. Due to the high natural abundance of 1H and 31P (99.98% and 100%), these experiments could be carried out quickly and easily. The only change that had to be made was to the spectral width, to accommodate the carbene signal (Ru=CH) between δ 20.02 and δ 17.32 ppm. The lack of 13C characterization is attributed to the low natural abundance of these nuclei that is only 1.10% and the lack of published parameters. Furthermore, the broad spectral width of 300 ppm increases the difficulty because the number of scans has to be increased to increase the sensitivity of the spectra and obtain useful data. In this study the precatalyst 1 was used to learn the NMR technique as well as to acquire the NMR parameters. 2 and two other commercial Grubbs-type precatalysts 3 and 4 underwent NMR characterization so that acquired values could be compared with the literature. Six other non-commercial Grubbs-type precatalysts 5-10 were synthesized and characterized. Due to the instability of the precatalysts and taking into account the duration of these experiments, the characterization was done over three steps. The first step was to do the following experiments: 1H, COSY, HSQC and HMBC, which took four hours. The next step was the DEPT135 experiment of three hours, and finally the 13C experiment of seven hours. The maximum amount of information could be obtained in this way. The combined NMR parameters for this study was obtained and used to characterize the Grubbs-type precatalysts 5-10 partially. Due to the large amount of overlapping peaks in the aromatic and alkane areas the resolution was not sufficient for full characterization. / MSc (Chemistry), North-West University, Potchefstroom Campus, 2014

Since the development of the ruthenium containing precatalysts Grubbs 1 (1) and Grubbs 2 (2), there was an increase in the development of new precatalysts. The NMR characterization could not cope with this. The NMR characterization mainly consists of 1H, 31P, COSY and rarely 13C. Due to the high natural abundance of 1H and 31P (99.98% and 100%), these experiments could be carried out quickly and easily. The only change that had to be made was to the spectral width, to accommodate the carbene signal (Ru=CH) between δ 20.02 and δ 17.32 ppm. The lack of 13C characterization is attributed to the low natural abundance of these nuclei that is only 1.10% and the lack of published parameters. Furthermore, the broad spectral width of 300 ppm increases the difficulty because the number of scans has to be increased to increase the sensitivity of the spectra and obtain useful data. In this study the precatalyst 1 was used to learn the NMR technique as well as to acquire the NMR parameters. 2 and two other commercial Grubbs-type precatalysts 3 and 4 underwent NMR characterization so that acquired values could be compared with the literature. Six other non-commercial Grubbs-type precatalysts 5-10 were synthesized and characterized. Due to the instability of the precatalysts and taking into account the duration of these experiments, the characterization was done over three steps. The first step was to do the following experiments: 1H, COSY, HSQC and HMBC, which took four hours. The next step was the DEPT135 experiment of three hours, and finally the 13C experiment of seven hours. The maximum amount of information could be obtained in this way. The combined NMR parameters for this study was obtained and used to characterize the Grubbs-type precatalysts 5-10 partially. Due to the large amount of overlapping peaks in the aromatic and alkane areas the resolution was not sufficient for full characterization. / MSc (Chemistry), North-West University, Potchefstroom Campus, 2014

A partir de la fin des années 1960, la fermeture des milieux consécutive à la déprise agricole a favorisé la recrudescence des grands feux, et au plan local, a augmenté la fréquence des incendies. Les objectifs de la thèse étaient d'évaluer les effets des incendies récurrents sur la capacité de résilience des propriétés microbiennes des sols, d'identifier les principaux facteurs impliqués dans la résilience microbienne et d'évaluer l'efficacité d'apports de composts pour favoriser la restauration de la qualité chimique et microbiologique des sols. Les dynamiques de retour à court et long terme des activités de minéralisation du C et du N, des activité enzymatiques et de la diversité catabolique des communautés microbiennes, ainsi que leur stabilité à des stress hydriques supplémentaires, ont été évaluées sous des régimes d'incendie fréquents et peu fréquents. La matière organique (MO) a été caractérisée par les techniques IRTF et RMN CPMAS du 13C. Les effets d'un apport de composts de boues d'épuration urbaines et de déchets verts sur la qualité des sols ont été étudiés in-situ sur des sols fréquemment incendiés en croisant 3 niveaux de maturité (3 semaines, 3 mois et 9 mois) et 3 temps depuis le dernier feu (10 mois, 5 ans et 18 ans). Les résultats ont montré que les incendies répétés accélèrent le retour après le feu de la nitrification nette et des profils cataboliques mais affectent durablement la plupart des autres fonctions microbiennes. L'activité respiratoire des sols récemment incendiés s'est avérée plus résistante aux stress hydriques mais également moins résiliente lorsque les feux sont récurrents. Les résultats démontrent le rôle limitant de l'évolution de la MO, en particulier de son degré d'aromaticité, sur la dynamique de retour des fonctions microbiennes après les feux et leur résilience aux stress. L'apport des composts sur les sols fréquemment incendiés est une solution efficace pour restaurer la qualité des sols mais nécessite de sélectionner une maturité adaptée à l'histoire contemporaine d'incendie.

A ocorrência de solos com horizonte A húmico (Ah) hiperdesenvolvido ainda é pouco entendida. Nos Latossolos com esse horizonte (Lh) ele freqüentemente é muito espesso, com baixa saturação por bases e cor escura advinda do relativamente grande acúmulo de matéria orgânica até profundidades superiores a 100 cm. Exceto para a região Sul, tais atributos estão em desconformidade com as atuais condições de clima e vegetação em que esses Lh se encontram. Objetivou-se definir variáveis ambientais que teriam influenciado na gênese desse horizonte em Latossolos, investigando-se dados de morfologia, textura, geoquímica, geomorfologia e evidências de paleoambientes. Realizou-se primeiro um estudo bibliográfico das principais características dos Lh no Brasil, em um conjunto de 39 perfis. Destes, 11 variáveis, representando atributos ambientais, químicos e granulométricos do solo foram submetidas a análises estatísticas multivariadas, para agrupá-los segundo similaridades. Três grupos foram definidos: G1 - Latossolos Brunos e Vermelhos em superfícies de cimeira da região Sul, com os mais altos teores de carbono orgânico e de Fe2O3, Ah menos espesso e mineralogia mais oxídica que os demais; G2- Latossolos Vermelho-Amarelos e Amarelos em antigas superfícies geomorfológicas da região Sudeste, associados à vegetação e clima de altitude, com valores intermediários de carbono e de mineralogia; G3 - Latossolos Vermelho-Amarelos e Amarelos com Ah mais espessos, encontrados nos níveis mais elevados de superfícies intermediárias (Depressão Periférica Paulista e Tabuleiros do Nordeste),com os menores teores de carbono e mineralogia caulinítica. Baseados nesses agrupamentos amostraram-se 30 pedons para fins de caracterização detalhada: análise total de Zr e Ti para identificar descontinuidades e técnicas isotópicas (13C,14C) aliadas a análises de fitólitos para inferir paleoambientes. Para esta análise procedimentos de extração de fitólitos foram adaptados. Nas regiões Sudeste e Nordeste o Ah teria se formado sob vegetação menos densa que a atual, como indicado pelos fitólitos e valor 13C que indicou mistura de plantas de ciclo C3 e C4 (~-22), que revelaram predomínio de plantas C3 e, na região Sul, vegetação mais aberta com predomínio de plantas C4 (~-16), indicando clima mais seco entre o Holoceno inferior e médio. A partir das datações 14C e dos valores 13C inferiu-se um empobrecimento isotópico (~-25) no Holoceno superior, sugerindo expansão da vegetação de floresta para todas as regiões, associada à clima mais úmido e quente, semelhante ao atual, nas regiões Sudeste e Nordeste e mais úmido e frio, na região Sul. Esses resultados indicaram que vegetação e climas pretéritos, associados aos materiais de origem e estabilidade do relevo, têm participação importante na geografia e nos processos de formação do material de origem e dos horizontes Ah. As relações Ti/Zr indicaram descontinuidades litológicas, fato que sugere a ação de processos de coluvionamento no espessamento dos Ah que, com isso, podem ser considerados como poligenéticos. O Ah constitui um importante registro das variações climáticas ocorridas durante o Quaternário sendo considerado como um paleossolo relictual. A integração da análise isotópica, de fitólitos, análise total de Zr e Ti, com a morfologia e análises de rotina foram bastante úteis para esclarecer a origem dos Ah desses Lh. / Thick humic A horizons (umbric epipedons) may be found in several Brazilian Latosols (well drained Oxisols - Lh). This dark colored horizon (Ah) is frequently more than 1m thick and has a large stock of soil organic matter (SOM) and differ from nearby Latosols without an Ah and on younger surfaces and do not conform with present climate and vegetation. Several hypothesis about their genesis had been raised but without a good pedogenetic understanding. This thesis aims to define environmental variables responsible for their formation. Several pedons were examined through their morphology and landscape position, and their soil materials were studied by geochemistry methods and paleoenviromental evidence by C isotope and phytolith assemblages. First, a bibliographic survey was performed to choose a set of 39 profiles were chosen to be studied on a data set where 11 noted chemical and granulometric attributes and one environmental variable were submitted to multivariate statistic analysis in order to group then according to similarities. Three groups were defined: G1 - Brown and Red Latosols from summit surfaces of the Brazilian Southern uplands (with the highest clay, organic carbon and iron oxide values, but with thinner epipedons than the others groups). G2 - Yellow-Red and Yellow Latosols, predominantly found in summit positions, remnant ancient geomorphic surfaces from the Southeast region and associated with the vegetation adapted to high altitudinal tropical climate. G3 - Red Yellow and Yellow Latosols from the Brazilian Southeastern piedmont upland surfaces and Northeastern coastal tablelands (with the thickest umbric epipedons, loamy to clayey textures, lower carbon contents, and a kaolinitic mineralogy). From this analysis 30 Lh representative pedons were field sampled to be characterized, including total Zr and Ti contents, stable carbon isotopes (13C, 14C) and phytolith analysis, in order to better understand paleo-environmental conditions they were subjected. For the phytolith extraction laboratory procedure were adapted in order to better separate and clean then from oxidic coatings. The SOM isotope data and phytolith assemblages indicated that these Ah were formed under a less dense vegetation than the present one: a probably mixture of C3 and C4 (~-22) plants, with more contribution of the C3 in the Southeast and Northeast regions, a more open (~-16, grassy), vegetation (with contribution of C4 plants) in the middle to medium Holocene indicating the presence of a drier climate in the Southern region. From the Late Holocene a more 13C depleted values (~-25) was observed, suggesting the expansion of the tropical and subtropical forests in this region, probably associate to a humid and warm climate in the Southeast and Northeast regions, and humid and cold in the Southern region. The combination of climate and vegetation late, parent material, and stability relief have played a major role in the geographic and formation of the parent material and pedogenetic horizons of these Lh, and thus they should be considered as polygenetic soils. The humic horizons constitute an important register of Holocene climate change and that they should be considered as relic paleosoils.