Lakes Magadi (Kenya) and Manyara (Tanzania) occupy closed basins in the southern Gregory Rift valley. Water in these lakes is presently shallow and saline, testifying to the dominance of evaporation (E) over precipitation (P). Past changes in the P: E ratio, and hence in palaeoclimate, can be reconstructed from evidence of the former extent of these lakes. Lake-level fluctuations engender marked variation in water chemistry, and consequently on the composition of the limnological biota. One approach is to examine the sedimentary record of diatoms (unicellular algae), which are excellent indicators of water chemistry and relative water depth, and whose modem distribution is sufficiently well known to allow the quantitative reconstruction of chemical parameters. Diatom analysis of 116 samples from a series of radiometrically dated (14C and U/Ib) sediment cores has revealed significant changes amongst the diatom assemblages during the Late Quaternary. Conductivity and pH have been estimated from the fossil samples by transfer functions (Gasse unpublished, Gasse 1986b). However, the interpretation of fossil diatom assemblages is often problematical in hypersaline environments. Difficulties arise as a result of the operation of taphonomic and diagenetic processes which can severely alter the composition of the diatom assemblagesfr om the ambient population at the time of deposition. Probably the most important factor responsible for assemblage diagenesis in saline lakes is silica dissolution, and this is explored further by a series of laboratory experiments. Results indicate that silica dissolution acts differentially between species, by removing the smaller, more delicate taxa first, and causing the relative enrichment of large robust forms in the fossil samples. A similar dissolution gradient may be reflected in modem samples studied near hot springs at Magadi. Differential dissolution is potentially an important source of error in palaeoenvironmental reconstructions, but, with the outcome of these experiments, it has been possible to assess the extent to which the dissolution process may have shaped the diatom records from Magadi and Manyara. The bulk of the palaeolimnological evidence is focussed upon two periods, 30,000-20,000 BP and 12,700-9,500 BP. The earlier period is most clearly dated in the core from Manyara, where the diatom record suggests the development of an intermediate level lake between c. 27,500 BP and c. 26,000 BP. This is a more complete representation of the same lake phase found in earlier studies from Manyara by Holdship (1976) based on diatoms, and by Casanova (1986a) on stromatolites 20M above the present lake. This time interval may also be represented by the central portion of the Magadi cores NF1 and NF2 but here dating is more problematical. The period 12,700-9,500 BP was one of major lacustrine transgression across Africa although the fine-structure of this event is less well known. Cores NF1 and NF2 from Magadi provide a detailed register of this phase indicating a major highstand from c. 12,700-11,000 BP when the lake became deep enough to stratify and deposit laminated couplets. At c. 11,000 BP the diatoms show that salinity increased greatly from fresh-oligosaline to meso-hypersaline which was probably a consequence of lake level falling.

Carbocyanine dyes are organic compounds containing chains of conjugated methine groups with electron-donating and electron-withdrawing substituents at the terminal heterocycles of the general formula [R1-(CH)n-R2]+X-. The synthetic methodology and optical properties of carbocyanines will be discussed. This thesis consists of two parts: (A) synthesis and optical properties of novel carbocyanine dyes substituted with various amines and the synthesis of unsymmetrical carbocyanine dyes containing monofunctional groups for bioconjugation. (B) synthesis of heptamethine carbocyanine dyes to be used for image-guided surgery. In part A, the synthesis of carbocyanine dyes functionalized with various amines and studies of their optical properties with respect to absorbance, fluorescence, quantum yield and extinction coefficient will be presented. These property studies will aid in designing efficient dyes for future biomedical applications. Part A will also include a one pot synthesis of unsymmetrical carbocyanine dyes functionalized with mono carboxylic acid chains, useful for biomolecule (i.e. proteins, amino acids, etc.) conjugation. Part B will describe the synthesis of novel carbocyanine dyes to be used for cancer image-guided surgery. Cancers are thus far incurable diseases, i.e. there are no drugs currently available to cure cancer; however, by designing a dye to visualize tumor cells will greatly increase the efficiency of cancer removal and hopefully increase the survival rate of cancer patients. The dyes reported in this thesis are superior to commercially available dyes used to visualize and identify various tumors invisible to the naked eye of surgeons with regards to biodistribution and clearance through kidney filtration.

This Diploma Thesis presents results obtained by solution of two partial projects: a) Preparation of monomers from renewable sources using metathesis and tandem hydrogenation catalyzed with ruthenium compounds - project solved during my Erasmus stay at the Université de Rennes 1 in France; b) Preparation and properties of ,-bis(tpy)quarterthiophene oligomers carrying ionic side groups as oligomonomers for polyelectrolyte conjugated dynamers - project solved at the Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University in Prague. Project a): Self-metathesis of 1,2-epoxyhex-5-ene (but-3-enyloxirane) and its cross-metathesis with methyl acrylate and acrylonitrile catalyzed with ruthenium compounds as well as tandem design of these metatheses and consecutive hydrogenation of their products by gaseous hydrogen have been optimized. The following influences have been studied and tuned: (i) type of the catalyst (Grubbs, Hoveyda, Zhan) and its concentration and method of dosing, (ii) concentration of reactants and additives, (iii) type of solvent, and (iv) reaction temperature. Reactions were monitored by the GC, GC and MS methods and the products were characterized by the NMR method. Methyl 6,7-epoxyheptanoate (methyl 5-oxiranylpentanoate) obtained by the tandem...

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-03-23T22:05:09Z No. of bitstreams: 1 VALDETE CAMPOS SILVA - DISSERTAÇÃO PPGEQ 2015..pdf: 1742009 bytes, checksum: d14a2b9103828a1effe17c04bc86fe09 (MD5) / Made available in DSpace on 2018-03-23T22:05:09Z (GMT). No. of bitstreams: 1 VALDETE CAMPOS SILVA - DISSERTAÇÃO PPGEQ 2015..pdf: 1742009 bytes, checksum: d14a2b9103828a1effe17c04bc86fe09 (MD5) Previous issue date: 2015-04-13 / Capes / As águas oleosas provenientes de descartes de algumas indústrias representam um sério problema para o ecossistema marinho e terrestre, sendo necessário um tratamento prévio para reutilização ou descarte dessas águas. O uso de materiais adsorventes vem sendo bastante estudado pelo fato de minimizar os problemas causadores no sistema ambiental. A busca por materiais de baixos custos, alta capacidade de remoção e fácil disponibilidade são fatores importantes para a sua escolha. Sendo assim, este trabalho teve como objetivo a avaliação da capacidade de remoção de óleo utilizando argila vermiculita modificada com sal quaternário de amônio e cera de carnaúba líquida em soluções emulsionadas óleo/água. Para tal finalidade, o planejamento fatorial 2² com três pontos centrais foi realizado para determinar as condições dos ensaios de banho finito. Para o processo de expansão a argila vermiculita in natura foi aferida, antes e depois da expansão, em uma proveta graduada. Foi levada ao forno mufla frio até atingir as temperaturas de 700, 800, e 900 ºC e, após atingir estas temperaturas permaneceu por mais 15 minutos no forno. A argila vermiculita expandida foi modificada com o sal quaternário de amônio CTABr e a cera de carnaúba líquida durante 2 minutos, sob agitação constante. Após as modificações, foram preparadas as emulsões óleo/água nas concentrações de 50, 75 e 100 ppm, utilizando o cloreto de sódio, óleo lubrificante Petrobras e água deionizada, sob agitação mecânica por 20 minutos. Para o banho finito, foram utilizadas as amostras da argila modificada, água deionizada, e as emulsões óleo/água, seguindo o planejamento fatorial 2². Após todos os procedimentos, as emulsões óleo/água e as amostras do banho finito, foram avaliadas através do analisador de óleo Horiba OCMA-350. Por meio do tratamento térmico, verificou-se que o processo de expansão das lamelas da vermiculita foi favorecido a temperatura de 700 oC. Nos difratogramas ficou evidenciado a intercalação do sal quaternário de amônio devido aumento da distância interlamelar do pico característico da argila vermiculita expandida. Com os espectros de infravermelhos observou-se a ausência da água adsorvida, ocasionada pelo processo de expansão, e a intercalação do material orgânico. A partir das micrografias verificou-se que a intercalação do sal quaternário de amônio e a cera de carnaúba gerou o preenchimento dos espaços vazios entre as camadas decorrentes da argila expandida que resultaram em aglomerados mais compactos. A argila vermiculita modificada com sal quaternário de amônio apresentou maior potencial na capacidade de remoção, nos tempos de 1h e 3h, e concentração de 100 ppm, em relação à argila modificada com cera de carnaúba. Para a argila vermiculita modificada com sal quaternário de amônio os ensaios 1 (50 ppm/1 hora) e 2 (100 ppm /1 hora) tiveram a melhor porcentagem de remoção de óleo, com 89,72% e 90,80%, respectivamente, e para a argila vermiculita modificada com cera de carnaúba os ensaios 2 (100 ppm/1 hora) e 4 (100 ppm/3 horas) tiveram a melhor remoção de óleo, com 84,21% e 86,90%, respectivamente. / Oily water from discharges of some industries represent a serious problem for the marine and terrestrial ecosystem, requiring pretreatment for reuse or disposal of these waters. The use of adsorbent materials has been widely studied because of minimizing the problems causing the environmental system. The search for low-cost materials, high capacity removal and easy availability are important factors in their choice. Thus, this study aimed to evaluate the oil removal capacity using vermiculite modified clay with quaternary ammonium salt and wax liquid carnauba in emulsified oil / water solutions. For this purpose, the factorial design 2² with three central points was conducted to determine the conditions of finite bath trials. For the process of expansion in nature vermiculite clay was measured before and after expansion, in a graduated cylinder. It was brought to the cold muffle furnace until it reaches temperatures of 700, 800, and 900 ° C and, after reached these temperatures remained for 15 more minutes in the oven. The expanded vermiculite clay was modified with the quaternary ammonium salt, the liquid CTABr and carnauba wax, for 2 minutes under constant stirring. After the modifications, the oil/water emulsions were prepared at concentrations of 50, 75 and 100 ppm, using sodium chloride, Petrobrás lubricating oil and deionized water, under mechanical stirring for 20 minutes. For the finite bath, the samples modified clay, the deionized water, and the oil/water emulsions were used, according to the 2² factorial design. Após todos os procedimentos, as emulsões óleo/água e as amostras do banho finito, foram avaliadas através do analisador de óleo Horiba OCMA-350. Through the heat treatment, it was found that the process of expansion of the vermiculite lamellae was favored of 700 ° C temperature. In diffractogram, was evidence the intercalation of quaternary ammonium salt, due to increased interlayer distance from the characteristic peak of the expanded vermiculite clay. With the infrared spectra, were observe the absence of adsorbed water, caused by the expansion process, and intercalation of the organic material. From the micrographs it was found that the intercalation of quaternary ammonium salt and carnauba wax generated filled the voids between layers of the resulting expanded clay which have resulted in more compact aggregation. The vermiculite modified clay with quaternary ammonium salt has the greatest potential removability, the times of 1h and 3h, and 100 ppm concentration, in relation to the clay modified with carnauba wax. For the vermiculite modified clay with quaternary ammonium salt, the tests 1 (50 ppm / 1 hour) and 2 (100 ppm / 1 hour) had the best percentage of oil removal, with 89.72% and 90.80%, respectively, and vermiculite modified

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-06-14T20:08:14Z No. of bitstreams: 1 TATIARA GOMES DE ALMEIDA – DISSERTAÇÃO (PPG-CEMat) 2015.pdf: 3847734 bytes, checksum: 33a29fced4bd93aef9e1714ea5787ad1 (MD5) / Made available in DSpace on 2018-06-14T20:08:14Z (GMT). No. of bitstreams: 1 TATIARA GOMES DE ALMEIDA – DISSERTAÇÃO (PPG-CEMat) 2015.pdf: 3847734 bytes, checksum: 33a29fced4bd93aef9e1714ea5787ad1 (MD5) Previous issue date: 2015-02-12 / Capes / O efeito da incorporação, purificação e organofilização de uma carga mineral nanoparticulada (argila bentonítica), nas propriedades mecânicas, térmicas e morfológicas de sistemas PHB poli(3-hidroxibutirato)/bentonita com concentrações de argila variando de 1 a 3% em massa foi avaliado. As argilas bentoníticas nas suas formas natural, purificada por ultrassom e organofílica com sal Cetremide, foram caracterizadas por FTIR e DRX antes de serem incorporadas ao PHB. As composições obtidas foram caracterizadas por difração de raios X (DRX), calorimetria exploratória diferencial (DSC), análise dinâmico-mecânica (DMA), microscopia eletrônica de varredura (MEV) e propriedades mecânicas. Os resultados mostraram que a purificação e organofilização da argila foram eficientes. A incorporação da argila organofílica ao PHB provocou um aumento no módulo de elasticidade e armazenamento. As resistências à tração e ao impacto diminuíram com a adição das nanocargas. As propriedades mecânicas dos compósitos foram significativamente afetadas pela exposição prolongada a temperaturas elevadas. Os resultados obtidos sugerem que a incorporação da argila organofílica ao PHB acelera o processo de degradação térmica da matriz. / The influence of addition, purification and organophilization of a nanoparticulate mineral filler (bentonite clay) on the mechanical, thermal and morphological properties of PHB (polyhydroxybutyrate)/bentonite with concentrations ranging from 1 to 3% w/w was investigated. Pristine, purificed (sonication) and organophilic (Cetremide) bentonite clays, were characterized by FTIR and XRD before being incorporated into the PHB. The compositions were characterized with X-ray diffraction (XRD), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), scanning electron microscopy (SEM) and mechanical properties. Results showed that the purification and organophilization clay were effective. The incorporation of the organoclay to PHB caused an increase in tensile and storage modulus, while tensile and impact strength decreased with clay addition. Mechanical properties were significantly affected by prolonged exposure to elevated temperatures. Results suggest that the incorporation of the organoclay to PHB accelerates the thermal degradation of the polymer.