This thesis examines the use of zinc for electroplating and compares its use to other metals. Experiments conducted to gather data indicated circumstances which resulted in optimal results.

Magister Scientiae (Biodiversity and Conservation Biology) / Heavy metal contamination tends to be a problem in inner city agricultural areas and gardens. High levels of certain heavy metals have been found in the soil and vegetables in the Cape Town Metropolitan area. The aim of this project was twofold. Firstly to ascertain whether water (ground or surface) was responsible for the heavy metal problem found in vegetables in the Philippi and Kraaifontein-Joostenbergvlakte farming areas in Cape Town; and secondly to evaluate the efficacy of two possible remediation methods, namely chelation (with EDTA) and precipitation (using phosphate), aimed at tackling the problem. In order to achieve this a water survey and greenhouse experiment were conducted. The water survey involved collecting a number of samples; both from surface dams and boreholes, from the two farming areas. Results showed minimal heavy metals in both, and therefore ruled this out as the source of the heavy metal problem. The greenhouse sand culture experiment tested the effects of the two remediation methods on the growth, development and elemental content of turnip and spinach plants treated with two cadmium and lead concentrations. In summary, Cd reduced growth more than Pb; Cd accumulated in roots and leaves, and Pb in roots. Several treatments, both metal and mitigation enhanced the chlorophyll content. The difference between the EDTA and phosphate mitigation treatments were not significant in the case of cadmium but in the case of lead, high phosphate resulted in increased growth. The large variation of results in this study, and indeed those of the available literature, indicate that the remedial treatments investigated here are not necessarily the most effective and that other treatments should be investigated to control the uptake of either cadmium or lead, as agricultural soils in future become more contaminated with either or both of these heavy metals.

No description available.

Accumulation and toxicity of cadmium, lead and thallium in duckweed (Lemna minor L.) The toxicity and accumulation of lead, cadmium and thallium in the aquatic plant Lemna minor was investigated, using a modification of the Organisation for Economic Co-operation and Development (OECD) standard growth inhibition test. Plants were cultured in modified Swedish Institute Standard (SIS) at pH 6.5±0.5 under 85 µmol m-2 S-1 at 25°C and exposed to a wide range of lead, cadmium, and thallium concentrations from environmentally realistic to very high concentrations (0.001, 0.01,0.1, 1, 10, 100, 1000 and 10 000 µmol L-1) for seven days. Various physico-biochemical endpoints were measured after seven days of exposure. The concentrations of dissolved lead, cadmium, and thallium remaining in the residual solutions, and accumulation of lead, cadmium and thallium in fronds and roots were assessed using Inductively Couple Plasma – Mass Spectroscopy (ICP-MS). Over the exposure duration, lead, cadmium, and thallium concentrations in solution decreased rapidly and chlorosis was observed in fronds exposed to the three highest lead, cadmium, and thallium concentrations. After seven days of exposure, there were significant decreases in the relative growth rate (RGR), relative frond area (RFA), pigment content (chlorophyll a, b and total carotenoid) and activity of photosystem II (Fv/Fm) at concentrations of 0.1, 1, 10, 100, 1000 and 10 000 µmol L-1Pb, 10, 100, 1000 and 10 000 µmol L-1cd, 0.01,0.1, 1, 10, 100, 1000 and 10 000 µmol L-1TI. However, our results suggested that root elongation based on relative growth rate of L. minor will be an optimal and relevant endpoint in compare to other endpoints. As expected, results demonstrated that root elongation was concluded that root length was most predictive of a dose response model compared to the rest of growth endpoints and physiological and biochemical endpoints when assessing toxicity of lead, cadmium and thallium using L. minor. Toxicity testing for the floating macrophytes should include root elongation measurement which alone will be sufficient to meet sensitivity and variability requirements for toxicity testing. Cellular concentrations of lead, cadmium, and thallium were higher in roots than fronds, whereas more lead, cadmium, and thallium was adsorbed to the extracellular matrix of fronds than roots. The bio - concentration factor (BCF; i.e. lead concentration in plant tissue at day seven relative to residual lead concentration in the growth medium at day seven) indicates that L. minor is a good accumulator of lead, cadmium, and thallium particularly at lower concentration, but the physiological data shows that these metals toxic at concentrations that can be encountered in wastewater treatment facilities. The translocation factor (TF) value was found to be less than 1. Though, lead, cadmium and Thallium was mostly stored in roots, only minor amounts of lead, cadmium and thallium were trans located to fronds.

This thesis concerns the synthesis of cadmium based nanoparticles that emitted from 400 to the near infrared (NIR) region. Once synthesised they can be possibly used as biomarkers once encapsulated in microspheres. A brief introduction to the area of nanomaterials is also provided. The focus of this thesis is split into three main categories. Firstly core/shell nanoparticles were synthesised due to their ability to emit over a large range of wavelengths. Alloyed nanoparticles were then synthesised due to their ability of being very good photoemitters. Finally core/shell/shell nanoparticles were synthesised as they had the ability of emitting in the NIR region. This thesis is split into five main chapters. The first chapter is a brief introduction to the field of nanomaterials, analysis techniques and current and possible future applications. Chapters 2, 3, and 4 contain the main research carried out with brief synthetic methods and detailed analysis and characterization. Chapter 5 contains detailed synthetic methods with experimental conditions and specific equipment used for this research.

Quantum dots (QDs) have the potential to produce more than one exciton per incident photon, if the photon energy is greater than twice the band gap energy. This process of multiple exciton generation (MEG) has the potential to lead to a step change in the efficiency of solar panels, by utilising energy commonly wasted as heat in conventional solar cells. A wide range of CdSe/CdTe and CdTe/CdSe quantum dots with and without a CdS shell were synthesised with varying core sizes and shell thicknesses. The excited state dynamics of these samples were studied with transient absorption and photoluminescence studies, with their MEG efficiencies obtained. Record MEG efficiencies were obtained with values reaching 142 ± 9 % achieved. The charge separation afforded by the type-II electronic configuration, allowed the first attractive biexciton interaction for a type-II QD system, with the potential for reducing the creation energy for a second exciton this affords. Efficient surface passivation of QDs was achieved through the reaction of CdCl2 with CdTe QDs, with near unity photoluminescence quantum yields (PLQYs) achieved. The suppression of surface trap states resulted in mono-exponential photoluminescence decay traces, with a resultant increase in exciton lifetime. Further CdCl2 treatment was carried out on CdSe/CdTe quasi-type-II QDs with alternating ‘Cd rich’ and ‘Te rich’ surfaces to elucidate the processes involved in surface treatment. It is shown that Te surface atoms are preferentially etched upon treatment, with the reaction being more aggressive when ‘Te rich’ surfaces are treated. The importance of surface composition is studied with trap states associated with chalcogen dangling bonds more prevalent and hence the increased requirement for their passivation is outlined. Control of the core/shell interface is also shown to be important in reducing trap states and ultimately increasing PLQYs, which is desirable for many optoelectronic applications.

Orientador: Marco Aurélio Zezzi Arruda / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-26T13:29:45Z (GMT). No. of bitstreams: 1 LopesJunior_CiceroAlves_D.pdf: 12621993 bytes, checksum: d178a6c055fde0c86926a36f0e49390c (MD5) Previous issue date: 2014 / Resumo: A busca para melhor entender a participação de elementos químicos no metabolismo de um organismo exige uma abordagem integrada entre as áreas da ciência devido à elevada envolvida complexidade. Esta Tese compreende o estudo realizado integrando as abordagens iônomicas, metalômicas e proteômicas para avaliar possíveis alterações no metabolismo do girassol (Helianthus annuus L.), mediante o desenvolvimento das plantas sob diferentes condições de irrigação com cádmio. Inicialmente, o estudo revelou que o girassol apresenta elevada resistência à contaminação com cádmio, sendo possível inferir, pela primeira vez, que o nível fitotóxico deste elemento para o organismo estudado é ca. 2,3 mg g-1. Um estudo ionômico desenvolvido empregando a técnica de ICP-MS foi realizado para avaliar a distribuição de vários elementos nas diferentes partes das plantas, buscando obter correlações com os processos biológicos exibidos pelas plantas durante o plantio. O estudo mostrou que os girassóis acumulam cádmio preferencialmente nas raízes, no entanto, ca. 65 ± 7% do total captado é translocado para as partes aéreas, fato que resulta na diminuição do transporte de ferro, cobre, magnésio e manganês para as folhas das plantas, sugerindo que há competição entre os elementos. Assim, pôde-se correlacionar a falta de tais nutrientes à clorose foliar exibida pelas plantas do grupo Cd-superior. O emprego da técnica de 2D-DIGE combinada a técnica de nESI-Q-TOF, também apresenta destaque na pesquisa, complementando os dados obtidos no estudo ionômico, por meio da identificação de proteínas nas folhas dos girassóis. As sementes das plantas Cd-tratadas apresentaram teor de cádmio superior ao recomendado pela FAO e OMS (0,1 mg/kg), sendo consideradas impróprias para o consumo humano. O protocolo de digestão in vitro revelou que as maiores concentrações deste elemento estão nas frações bioacessíveis das sementes. Na avaliação dos extratos protéicos das sementes empregando a hifenação SEC-ICP-MS foi identificado que o cádmio interage com moléculas de massa moleculares variando entre 70 a 0,7 kDa. Por fim, o teste de germinação evidenciou que o nível de cádmio acumulado nas sementes interfere no seu desenvolvimento / Abstract: The search for better understand the involvement of chemical elements in the metabolism of an organism requires an integrated approach between the areas of science due to the high complexity involved. This Thesis comprises study integrating ionomic, metallomic and proteomic approaches to evaluate possible changes in the metabolism of sunflower (Helianthus annuus L.), through the development of plants under different irrigation conditions with cadmium. First, the study showed that the sunflower presents high resistance to cadmium contamination, being possible infer, the first time, that the phytotoxic level of this element to the plant especies is ca. 2.3 mg g-1. An ionomic study carried out using an ICP-MS, it was performed to evaluate the distribution of various elements in different plant parts, seeking to obtain correlations with biological processes exhibited by plants during planting. The study showed that cadmium sunflowers accumulate preferentially in roots, but ca. 65 ± 7% of the total absorbed was translocated to the aerial parts, which it has resulted in decreased transport of iron, copper, magnesium and manganese to the leaves, suggesting that there is competition between the elements. Thus, the lack of such nutrients correlated to leaf chlorosis exhibited by plants of Cd-higher group. The application of the technique of 2D-DIGE combined technique nESI-Q-TOF, also features highlighted in the research, supplementing the data obtained in the ionomic study through the identification of proteins in the leaves of sunflowers. The seeds of Cd-treated plants presented higher levels of cadmium than recommended by FAO and WHO (0.1 mg kg-1), being considered unsuitable for diet human. The protocol of in vitro digestion showed that higher concentrations of this element are on bioacessible fractions of the seed. In the assessment of protein extracts of the seeds using the SEC-ICP-MS coupled, it was identified that cadmium interacts with molecules of molecular mass ranging from 70 to 0.7 kDa. Finally, the germination test reaveled that the level of cadmium accumulated in seeds interfere in its development / Doutorado / Quimica Analitica / Doutor em Ciências

Orientador: Jaime Frejlich / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-14T11:06:50Z (GMT). No. of bitstreams: 1 Santos_TatianeOliveirados_D.pdf: 7708751 bytes, checksum: 103a28dbd9feff06d3555a0fc88ad4b7 (MD5) Previous issue date: 2009 / Resumo: Foi realizado o estudo de novos materiais fotorrefrativos através das técnicas Fotocon-dutividade Resolvida por Comprimento de Onda e Speckle-foto-fem. Dentre esses materiais encontram-se titanosillenitas com diferentes dopantes e os materiais fotorrefrativos do grupo II-VI como o telureto de c'admio (CdTe) e telureto de zinco (ZnTe), também dopados, e cujo interesse está no fato de terem uma banda proibida menor que as sillenitas, e serem bem mais rápidos que as sillenitas. O modelo matemático que descreve o efeito foto-fem com um padrão de "speckle" oscilante e de grande amplitude foi desenvolvido, tornando-se o modelo mais completo até hoje existente. O novo modelo prêve o aparecimento de um máximo no sinal de speckle-foto-fem para um determinado valor da amplitude normalizada sobre o tamanho do speckle d , em conformidade com os resultados experimentais. Verificou-se também, que a posição deste máximo depende fortemente da relação entre a condutividade no escuro e fo-tocondutividade (Rd). Através da técnica Fotocondutividade Resolvida por Comprimento de Onda foi estudado as amostras de BTO puro e dopado, CdTe e ZnTe dopados, onde foi possível identificar alguns estados localizados dentro da banda proibida destes materiais. A partir disto, alguns cristais, como o BTO, Cdte:V e CdTe:Ge foram selecionados para os experimentos de medidas de vibrações transversais utilizando a técnica speckle-foto-fem. Os experimentos de speckle-foto-fem foram, pela primeira vez, utilizados para caracterizar materiais fotorrefrativos, a partir da determinação do tempo de resposta e da estimativa da condutividade no escuro. / Abstract: A study of new photorefractive materials was performed through the techniques of wa-velength resolved photoconductivity and Speckle-photo-fem. Among this materials are the titanosillenites with different dopants and the group II-IV Photorefractive materials like the Cadmium telluride (CdTe) and the Zinc telluride (ZnTe), also doped, which are interesting for having a band gap smaller than that of the sillenites, and for being a lot faster than the sillenites. The mathematical model that describes the Photo-emf effect with an oscillating and high amplitude speckle pattern was developed, becoming the most complete model in existence. The new model predicts the presence of a maximum in the signal of speckle-photo-emf for a determined value of the amplitude normalized over the size of the speckle d , in conformity with the experimental results. Was also verified that the position of this maximum is strongly depen-dent on the relation between the dark conductivity and photoconductivity (Rd). Through the technique of wavelength resolved photoconductivity the samples of pure and doped BTO, CdTe and ZnTe were studied and it was possible to identify some localized states inside the band gap of those materials. From that, some crystals like the BTO, CdTe:V and CdTe:Ge were se-lected for the experiments on transversal vibration measurement using the Speckle-photo-emf technique. The speckle-photo-emf experiments were, for the first time, used to characterize photorefractive materials, from the determination of the response time and the estimate of their dark conductivity. / Doutorado / Ótica / Doutora em Ciências

Philosophiae Doctor - PhD / Cape Town includes two vegetable farming areas within the city limits, the Joostenbergvlakte/Kraaifontein area and the Philippi area. Both areas supply produce to local markets and further afield. Sporadically, high levels of cadmium, copper, lead and zinc have been found to occur in some of the soils, irrigation water resources and crops. To find the sources of specifically Cd, Pb and Zn to these agricultural systems, extensive analysis of several heavy metals in inputs such as fertilizers, agrochemicals and supplementary water resources to these farming areas was undertaken. Heavy metal concentrations in soils, irrigation water resources and crops were also determined. Two mitigation techniques that could be used to remediate Cd, Pb and Zn contamination were investigated. The first mitigation method included immobilization of heavy metals as phosphate complexes by using a triple super phosphate fertilizer, while the second method involved mobilisation and thus leaching of heavy metals away from plant roots using EDTA. These mitigation methods were tested in a pot experiment using cabbage as the experimental crop and soil from these areas as growth medium. A survey of common farming practices in these two areas and farmers‟ willingness to use remediation methods was conducted. The results in general indicated that crops from these two areas were fit for human consumption and that raw (unprocessed) cattle manure and chicken manure were the greatest sources of heavy metals in both farming areas. It was found that the use of EDTA led to elevated levels of Cd, Pb and Zn in cabbage, while the use of triple super phosphate at a low concentration contributed to limiting the uptake of Cd, Pb and Zn, but only minimally. Most farmers are willing to apply remediation methods but only when they have been proven necessary. In general, the same farming practices occurred in both areas. Farmers from the Philippi area tended to rely more heavily on subterranean water resources. It became clear that unprocessed manures should be used with caution and that more appropriate heavy metal remediation methods should be sought.

Orientador: Sebastião Roberto Taboga / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-27T10:30:24Z (GMT). No. of bitstreams: 1 Colleta_SimoneJacovaci_M.pdf: 4304217 bytes, checksum: ec5dd4758c1bcc8948cc085490014e3d (MD5) Previous issue date: 2015 / Resumo: A próstata é uma glândula acessória do sistema reprodutor que apresenta desenvolvimento e manutenção regulados por andrógenos e estrógenos. Interferências na ação desses hormônios podem predispor esta glândula a desenvolver doenças como hiperplasia prostática benigna e câncer. O bisfenol A (BPA) e cádmio (Cd) são poluentes ambientais que possuem atividade estereogênica. O BPA e Cd entram no corpo humano, principalmente através da ingestão oral. Assim, o objetivo deste estudo foi avaliar se a exposição ao BPA e ao Cd durante a puberdade pode causar alterações na morfologia, proliferação e morte celular na próstata ventral de gerbilos normais e castrados. Para cumprir estes propósitos foram realizadas técnicas morfológicas, serológicas e immunocitoquímicas (PCNA para detecção de células proliferativas e TUNEL/ caspase-3 para a detecção de células apoptóticas). Os resultados demonstraram que 7 dias depois da exposição ao BPA e Cd, individualmente ou em combinação sob condições androgênicos normais, houve um aumento na altura do epitélio e na espessura da camada muscular lisa (SML). O BPA e Cd individualmente induziram o aumento expressão celular de PCNA e caspase-3. Em associação, o BPA e Cd causam aumento das células imunomarcados por TUNEL. Nos animais castrados, o Cd, individualmente ou em associação com o BPA causou aumento na altura do epitélio, na espessura SML, na área e perímetro nuclear, além da redução no numero de células epiteliais imunomarcadas com PCNA. Além disso, o BPA e Cd combinados, causaram redução das células imunomarcadas por caspase-3. Após 75 dias depois da exposição ao BPA e Cd individualmente ou em combinação, nos animais não castrados, foi observado um aumento na altura epitelial e na espessura da SMC. Todos animais com 120 dias de idade apresentaram focos de lesões intraepitelial prostática (PIN). O BPA promoveu redução da expressão de PCNA nas células do estroma. O Cd, individualmente ou associado com o BPA, causou um aumento das células epiteliais imunomarcadas por PCNA. Além disso, Cd aumentou o numero de células imunomarcadas por TUNEL e diminuiu as células imunomarcadas por caspase-3. Nos animais castrados, a administração BPA e Cd, individualmente ou em combinação, promoveu aumento das células imunomarcadas por TUNEL. Desta forma, podemos concluir que o BPA e o Cd são importantes desreguladores das atividades normais do tecido prostático, alterando os padrões morfológicos, de proliferação e morte celular / Abstract: The prostate is an accessory reproductive system gland presenting the development and maintenance regulated by androgens and estrogens. Interference in the action of these hormones may predispose this gland to develop diseases such as benign prostatic hyperplasia and cancer. The Bisphenol A (BPA) and cadmium (Cd) are environmental pollutants that have estrogenic activity. The BPA and Cd enter in human body, mainly through oral ingestion. Thus, the aim of this study was to evaluate whether exposure to BPA and the Cd during puberty can cause alterations in morphology, proliferation and cell death in normal and castrated gerbils¿ ventral prostate. For this, morphological, serological and immunocitochemical (PCNA for proliferating cells detection and TUNEL/ caspase-3 for apoptotic cells detection) methods were used. The results demonstrated that 7 days after the exposure to BPA and Cd, individually or in combination under androgenic normal conditions, there was an increase in epithelium height and in smooth muscle layer (SML) thickness. The BPA and Cd individually induced increased in PCNA and caspase-3 cellular expression. In association, the BPA and Cd cause increase in TUNEL immunostained cells. In castrated animals, the Cd, individually or in association with the BPA caused an increase in epithelium height, in SML thickness, in area and nuclear perimeter, in addition caused reduction in PCNA immunostained epithelial cells number. In addition, BPA and Cd combined, caused reduction in caspase-3 immunostained cells. Seventy-five days after BPA and Cd exposure, individually or in combination, in non-castrated animals, we observed an increase in epithelial height and the SMC thickness. All animals with 120 days of age had occurrences of lesions prostatic intraepithelial (PIN). The BPA caused a reduction in PCNA stromal cells expression. The Cd, individually or associated with BPA, caused an increase in PCNA immunostained epithelial cells. In addition, Cd increased the number of immunostained cells by TUNEL and decreased the immunostained cells by caspase-3. In castrated animals, the administration BPA and Cd, individually or in combination, increased the immunostained cells by TUNEL. We can conclude that the BPA and Cd are are important agents in endocrine activities changing of normal prostatic tissue patterns, altering the morphological, proliferation and cell death patterns / Mestrado / Histologia / Mestra em Biologia Celular e Estrutural