The present thesis aims to evaluate the use of antioxidant enzyme activities (AEA) of biofilm communities as biomarkers of metal pollution (mainly Zn) in fluvial ecosystems. In order to test AEA as biomarkers of metal pollution as well as their responses to environmental variables, several ecotoxicological experiments have been performed. A zoom from field studies (with high ecological realism) to microcosm experiments (under controlled conditions) has been done to fill the gap between both approaches and understand AEA responses under a multiple-stress (environmental and metallic) scenario. The field studies were carried out in the Riera d’Osor, a tributary of the Ter, located in the region of La Selva (Girona province) / L’objectiu d’aquesta tesi és avaluar l’ús de les activitats enzimàtiques antioxidants (AEA) dels biofilms com a biomarcadors de contaminació metàl·lica (principalment per zinc (Zn)) en els ecosistemes fluvials. Per tal d’estudiar la resposta de les AEA a la contaminació metàl•lica, així com també la resposta a altres canvis ambientals (situacions d’estrès múltiple), s’han realitzat diversos experiments ecotoxicològics fent un zoom des d’estudis de camp (amb un elevat realisme ecològic) fins a un estudi de laboratori utilitzant microcosmos (amb condicions controlades). Els estudis de camp s’han dut a terme a la riera d’Osor, afluent del Ter, situada a la comarca de la Selva (província de Girona)

Potato is an important source of energy to most micronutrient malnourished affected population in South Africa. Improvements through bio-fortification can therefore enhance access to essential micronutrients. The study was aimed at determining the level of variability of iron and zinc concentration among 20 potato genotypes as a preliminary step for future breeding program. The materials were evaluated using inductively coupled plasma optical emission spectrometry. Statistical analysis indicated significant (P<0.001) variation of Fe and Zn among the genotypes. The average concentration ranges from 34.67 to 76.67 mg kg-1 and 12.88 to 66.1 mg kg-1 for iron and zinc respectively. The best performing genotypes were cultivar Mnandi, Hertha, Buffelspoort and breeding lines-N105-1, 00-S100-33 and 03-627-50. Iron concentration was positively correlated with Zinc concentration. The study showed that enough variability of Fe and Zn concentration exist among the evaluated genotypes, which can be exploited for use in potato bio-fortification breeding programme. / Agriculture, Animal Health and Human Ecology / M.Sc. (Agriculture)

Made available in DSpace on 2017-07-10T18:08:20Z (GMT). No. of bitstreams: 1 Andreine Aline Roos.pdf: 2960540 bytes, checksum: 99bd1c80529add7a7c94dc586e17b240 (MD5) Previous issue date: 2013-02-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Environmental contamination is a serious problem in today's society and for years aroused the interest of researchers. The pollutants with pharmacological activity are worrying the scientific community by increasing detection of these aquatic environments at concentrations ranging from µ L-1 to ng L-1, which are resistant to conventional treatments used in sewage treatment plants. Thus, it becomes necessary to investigate more effective treatments to minimize environmental contamination. The Advanced Oxidation Processes have attracted interest as promising treatments for removal of organic pollutants, among which stands out the heterogeneous photocatalysis whose the main drawback is the difficulty of separating the catalyst from solution degraded. To try to solve the problem, this work proposes the use of cellulose acetate/TiO2 composite and zinc metal plate coated with ZnO as catalysts for photodegradation of sulfamethoxazole. The composite was prepared by phase inversion of a solution of cellulose acetate and titanium tert-butyl orthotitanate that resulted in a composite with around 4% (in mass %) if TiO2.This composite proved not to be efficient in the degradation of sulfametoxazol in the presence of hydrogen peroxide under both, sunlight or artificial radiation. For this reason the continuity of the work occurred only with zinc plate coated with ZnO obtained by hydrothermal method. The 22 factorial experimental design, with triplicate on central point showed that the model was valid, and that the process was favored with increasing amounts of H2O2 at acidic pH. The equilibrium time for the photodegradation of sulfametoxazol using a plate Zn/ZnO was 120 minutes with removal of 95%, under artificial radiation, obeying the rate law of peudo-first order. The COD and nitrate concentration indicated that there was a small mineralization of the pollutant, despite the high removal, showing that there was probably the formation of intermediate species. Furthermore, the Zn/ZnO showed a catalytic efficiency almost unchanged up to 10 repetitions of photodegradation. However, at the end of the process the zinc concentration in the sample was above the allowed degraded by environmental agencies, necessitating the use of a post-treatment for removal of zinc or use of sulfametoxazol solution with pH closer to neutrality to avoid dissolution of the metal catalyst. / A contaminação ambiental é um grave problema da sociedade atual e há anos desperta o interesse dos pesquisadores. Os poluentes com atividade farmacológica vêm preocupando a comunidade científica pela crescente detecção dos mesmos em ambientes aquáticos, em concentrações que variam de µg L-1 a ng L-1, os quais são resistentes aos tratamentos convencionais empregados nas estações de tratamento de esgoto. Dessa forma, torna-se necessário a investigação de tratamentos mais eficientes para minimizar a contaminação ambiental. Os Processos Oxidativos Avançados vêm despertando interesse como tratamentos promissores para remoção de poluentes orgânicos, dentre os quais destaca-se a fotocatálise heterogênea, cujo principal empecilho é a dificuldade de separação do catalisador da solução degradada. Para tentar solucionar o problema, o trabalho propõe a utilização de catalisadores diferenciados como, compósito acetato de celulose/TiO2 e uma placa de zinco metálico recoberto com ZnO para a fotodegradação do princípio ativo sulfametoxazol. Contudo, o compósito acetato de celulose/ TiO2 não apresentou a eficiência similar ao TiO2 como era esperado, e assim optou-se por prosseguir os estudos de fotocatálise heterogênea utilizando a placa de zinco recoberta com ZnO como catalisador. O planejamento experimental fatorial, 22 com triplicata no ponto central, mostrou que o modelo utilizado foi válido, e que o processo é favorecido com quantidades maiores de H2O2 em pH ácido. O tempo de equilíbrio para a fotodegradação do sulfametoxazol utilizando a placa de Zn recoberta com ZnO foi de 120 minutos com remoções de 95%, sob radiação artificial, seguindo uma lei de velocidade de pseudo-primeira ordem. A determinação de DQO e da concentração de nitrato indicaram que houve uma pequena mineralização do poluente, apesar da elevada remoção, mostrando que provavelmente houve a formação de espécies intermediárias. Além disso, a placa de zinco recoberta com ZnO apresentou uma eficiência catalítica praticamente inalterada em até 10 repetições de fotodegradação. No entanto, ao final do processo a concentração de zinco na amostra degradada estava acima da permitida pelos órgãos ambientais, sendo necessário a utilização de um pós-tratamento para a remoção do zinco ou a utilização de solução de sulfametoxazol com pH mais próximo da neutralidade para evitar a dissolução do metal do catalisador.

Aim of the present work was to explore the possibility of improving strength of cast Mg by alloying additions, viz., Si and Zn+Al. All the alloys were produced by squeeze casting technique using squeeze pressure of 12MPa and their microstructure, tensile and corrosion properties were studied. Mg-Si system was chosen because the intermetallic compound Mg2Si possesses many desirable properties, such as, low density, high hardness, high melting point. Hence, there is scope for improving the strength of Mg by dispersion of primary Mg2Si particles. Addition of Si to Mg resulted in the formation of �-Mg, particles of primary Mg2Si and eutectic as microstructural constituents. The morphology of primary Mg2Si changed from polyhedral shaped particles to dendrites as Si content was increased from 3.57 to 5.5 wt%. Volume fraction of primary Mg2Si increased with increase in Si content. Particle size of primary Mg2Si also increased with increase in silicon content but at the same time it was found to be dependent on melt temperature, i.e., a lower particle size was obtained at higher melt temperatures. Addition of Al and Sr was made to Mg-2Si alloy in order to further increase the strength by solid solution strengthening and refinement/modification of primary Mg2Si particles/eutectic. Addition of 1.2 wt% Al to Mg-2Si alloy resulted in irregular type of morphology of Mg2Si particles and increased particle size. Addition of 0.2 wt% SrtoMg-2Si-1.2Al alloy resulted in slight refinement of primary Mg2Si particles and modification of eutectic. Addition of 0.4 wt% Sr resulted in both refinement and restoration of morphology of Mg2Si particles from irregular to polyhedral shape. This was accompanied by destruction of eutectic, and rods containing Mg, Si, Al and Sr were observed. The addition of 1.33 wt%Si to Mg resulted in improvement in 0.2%PS by about 80 MPa,UTS by about 40MPa and these values did not change much till the addition of 3.57 wt% Si. A drop in the strength values was observed at Si content of 5.5 wt%,where transition in morphology of primary Mg2Si occurred from polyhedral to dendrite. Addition of Si resulted in reduction in % elongation by about 2%. The addition of Al and Sr did not change the tensile properties of binary Mg-2Si alloy much. It was concluded that the volume fraction and size of primary Mg2Siparticles obtained with Si addition up to 3.57 wt% did not contribute much to strength and the strengthening mainly came from the eutectic present in the matrix. As Si content was increased to 5.5 wt% in order to increase the volume fraction of primary Mg2Si particles, the morphology of Mg2Si changed to dendritic type resulting in reduction in strength. Thus, the maximum increase in strength is achieved at near eutectic composition,i.e.,intheMg-1.33Sialloy,andfurtherincreaseinstrengthdoesnotseem to be feasible with this alloy system. The ductility of all the Mg-Si based alloys was also low, i.e, 0.5% elongation to fracture or less. Regarding the corrosion behaviour, the addition of Si to Mg deteriorated the corrosion resistance and the addition of Al and Sr further worsened it. Since further improvement in tensile properties did not seem feasible with Mg-Si alloy system, the focus was shifted to Mg-Zn-Al alloy system. There is scope for improvement in strength in Mg-Zn-Al alloy system by solid solution strengthening, grain refinement and precipitation hardening. It was observed that the addition of Zn and Al resulted in microstructure containing α-Mg grains and secondary phase at the grain boundary. XRD analysis showed the secondary phase to be Al5Mg11Zn4 but EDS analysis did not match with this composition. Therefore, the nature of this phase remains uncertain. Addition of 6 wt% Zn and 1 wt% Al resulted in improvement in strength as well as ductility: 0.2%PS improved by about 70 MPa, UTS by about 100 MPa and % elongation by about 7%. Addition of small amounts of Caresultedinrefinementofmicrostructurecausingimprovementinstrengthwithout much decrease in % elongation. Increase in Al content from 1 to 4 wt% resulted in increase in 0.2%PS but UTS slightly decreased, as % elongation reduced. Alloys subjected to T6 heat treatment showed improvement in strength but slight reduction in % elongation. ZA64 alloy in T6 condition gave 130 MPa 0.2%PS, 225 MPa UTS and 4.9% elongation, which are much higher tensile properties as compared Mg-Si alloys. All the three mechanisms mentioned above contribute to the strengthening. There is scope for further improvement in strength by employing a more suitable heat treatment. Regarding corrosion behaviour, addition of 6 wt% Zn and 1 wt% of Al to Mg did not deteriorate its corrosion resistance much. Addition of small amounts of Ca was found to be beneficial for corrosion resistance, whereas an increase in Al content lowered the corrosion resistance. Heat treatment also reduced the corrosion resistance.

Orientadora: Profa. Dra. Giselle Cerchiaro / Tese (doutorado) - Universidade Federal do ABC, Programa de Pós-Graduação em Biossistemas, Santo André, 2018. / Em doencas neurodegenerativas amiloidais o estresse oxidativo tem um papel importante juntamente com a proteina ¿À-amiloide (A¿À), associada a formacao de placas senis na Doenca de Alzheimer. Tais condicoes demonstraram desbalanco de metais, como cobre e zinco, tanto na concentracao celular e quanto nos processos antioxidantes. A Cu,Zn-Superoxido Dismutase (SOD1), em condicoes neurodegenerativas, pode demonstrar alteracoes estruturais e funcionais, tendo menor afinidade pelo cobre e pelo zinco. Diante destas condicoes, o objetivo principal desta tese foi em condicoes oxidativa (H2O2) e neurodegenerativa (A¿À1-42) avaliar os danos a biomoleculas, concentracao metais e a influencia da enzima SOD1 em linhagens de celulas neuronais (NSC-34 e mHippoE2). Diferentes respostas quanto a sensibilidade das linhagens neuronais foi observada durante as condicoes oxidativas e neurodegenerativa. Quanto os danos ao DNA a linhagem NSC-34 demonstrou maior sensibilidade a condicao oxidativa, com aumento de danos ao DNA, lesoes oxidativas em bases nitrogenadas que indicaram a presenca de lesoes tipo 8-oxo-G, corroborando com anormalidades nucleares e inibicao do processo de divisao celular. Nesta mesma linhagem quantidades aumentadas de Cu foram observadas, juntamente com a presenca da enzima SOD1 a nivel citoplasmatico e nuclear na condicao oxidativa (H2O2), alem de resultados significantes para danos permanentes ao DNA (anormalidades nucleares e quebras cromossomicas). A linhagem mHippoE2 apresentou aumentos significativos mediante a condicao oxidativa e neurodegenerativa, como oxidacao de proteinas e lipidios, demonstrando tambem alteracoes morfologicas citoplasmaticas. O tratamento com A¿À1-42 demonstrou aumento de danos ao DNA, lesoes oxidativas 8-oxo-G e tambem em bases purinicas. Podemos observar nesta mesma linhagem a forte influencia do Zn na condicao neurodegenerativa, atividade da SOD1 em ambas condicoes e tambem danos permanentes ao DNA mediante condicao neurodegenerativa. Dentre os resultados obtidos salientamos a relevancia dos achados na condicao neurodegenerativa ocasionada pelo peptideo A¿À1-42 nos ensaios para avaliacao genotoxica e mutagenica. Tal condicao demonstrou a presenca de danos importantes a bases nitrogenadas, tanto purinicas quando pirimidinicas, apontando tambem para possiveis efeitos mutagenicos detectados pelos eventos de quebras cromossomicas associados as anormalidades nucleares, bem como a presenca da enzima SOD1 no nucleo das celulas. / In neurodegenerative diseases, oxidative stress plays an important role associated with â-amyloid protein (Aâ), associated with the formation of amyloid plaques in Alzheimer's Disease (AD). In AD condition it has been demonstrated an imbalance of essential metals, such as copper and zinc, their cellular concentration and antioxidant processes alterations. The antioxidant enzyme Cu, Zn-Superoxide Dismutase (SOD1), under neurodegenerative conditions has structural and functional changes, such as lower affinity for copper and zinc. According to these conditions, the main objective of this thesis was to investigate how the oxidative (H2O2) and neurodegenerative (Aâ1-42) conditions cause biomolecules damage, metal alteration and SOD1 location in neuronal cell lines (NSC-34 and mHippoE2). Different responses in neuronal cell lines were observed during the conditions evaluated. For DNA damage, the NSC-34 cells demonstrated greater sensitivity to the oxidative condition, with increased DNA damage, oxidative lesions on nitrogenized bases indicating the presence of 8-oxo-G type lesions. In this same cell line we observed an increase of Cu amount, together with the presence of the SOD1 enzyme at the cytoplasmic and nuclear level in the oxidative condition (H2O2). The mHippoE2 cell line presented increased protein oxidation through the oxidative and neurodegenerative condition. Treatment with Aâ1-42 demonstrated increased DNA damage in this cell, 8-oxo-G oxidative lesions and also purine bases. We observed, in this same cell line, the strong influence of Zn on the neurodegenerative condition, SOD1 activity in both conditions and it was observed permanent damages to DNA in the neurodegenerative condition. Among the results, we highlight the relevance of the findings in the neurodegenerative condition caused by the Aâ1-42 peptide in the genotoxic and mutagenic evaluation trials. This condition demonstrated the presence of important damages to nitrogenated bases, both purine and pyrimidine, also pointing to possible mutagenic effects detected by the events of chromosomal breaks associated with nuclear abnormalities, as well as the translocation of the SOD1 enzyme to nuclei.

Subject of this diploma thesis is analysis of selected heavy metals in soils which are exposed to long-time cause of contaminants from metallurgical industry in localities Třinec and Ostrava. For assessment of the contamination, indexes for evaluation of soils were chosen. Those indexes are focusing mainly on rate of enrichment of the soils by selected heavy metals and resulting ecological and possibly health risk for human organism. Within every location, 26 samples were extracted, while every sample extract location, were selected to map the level of pollution around metallurgical plants in the most complex way. The analysis of the samples was done by techniques F-AAS and AMA 254 and established metals were mercury, lead, copper, chrome, nickel, manganese and zinc.

Die vorliegende Arbeit beschäftigt sich im ersten Teil mit einer Methodenentwicklung zur korrosionsfreien Ermittlung der elektromotorischen Kraft von zinkbasierten intermetallischen Verbindungen bei Raumtemperatur. Die durchgeführten Messungen bezüglich der elektrochemischen Potentiale von Verbindungen der binären intermetallischen Phasen Cu5Zn8, ZnPd und ZnPt mit jeweils verschiedenen elementaren Zusammensetzungen dienen als Basis zur Ermittlung der jeweiligen intrinsischen Aktivitäten der Einzelkomponente Zink. Messungen an der Referenzphase Cu5Zn8 wurden dabei zur Verifizierung der entwickelten Messmethodik durchgeführt. Die Untersuchungen an ZnPd- und ZnPt-Verbindungen liefern erstmalig thermodynamische Daten dieser Phasen bei Raumtemperatur. Der zweite Teil dieser Arbeit beschäftigt sich mit der katalytischen Untersuchung von intermetallischen äquimolaren ZnPd-Elektroden hinsichtlich der elektrolytischen Wasserstoffentwicklung. Die durchgeführten Experimente legen den Schluss nahe, dass die katalytische Aktivität der intermetallischen Elektroden durch eine gezielte anodische Vorbehandlung signifikant gesteigert werden kann. Ex situ Charakterisierungen geben Grund zu der Annahme, dass die gesteigerte katalytische Aktivität durch die simultane Präsenz von oxidischer und metallischer beziehungsweise intermetallischer Spezies hervorgerufen wird.

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Globale Megatrends erfordern immer flexiblere analytische Messmethoden und Assays. Insbesondere im Umwelt-, Agrar-, Lebensmittel- und Gesundheitssektor sind chemische Assays hier eine geeignete Wahl. Eine Vielzahl solcher Assays steht in akademischen und industriellen Bereichen zur Verfügung. Die Anpassung an neue Verbindungen hingegen ist oft schwierig zu realisieren, da der einzelne Test meist für einen spezifischen Analyten konzipiert ist. Eine modulare, analytische Plattform für die Entwicklung chemischer Assays ist daher sehr wünschenswert. Ein solches System sollte die Möglichkeit einer schnellen und flexiblen Implementierung verschiedener Erkennungstypen für neue Analyten und die Möglichkeit einer Multiparameter-(Multiplex-)Bestimmung in einem robusten und portablen Auslesegerät beinhalten. Einzelpartikel-basierte, chemische Assays haben sich hier als geeignete Lösung erwiesen. In dieser Arbeit stelle ich Polystyrol-Kern-Silikat-Schale-Partikel als modulare, hybride Plattform für die flexible Konfiguration von Einzelpartikel-basierten chemischen Assays vor. Zunächst wurde ein Verfahren entwickelt, das den Zugang zu verschiedenen-Partikelarchitekturen ermöglicht. Diese Partikel wurden für den DNA-Nachweis bis in den fmol-Bereich getestet (Kapitel 2). Ein neues Werkzeug zur Bestimmung der Rauheit der Partikel aus elektronenmikroskopischen Bildern wurde entwickelt und auf das breite Spektrum der im Projekt hergestellten SiO2@PS-Partikel angewendet (Kapitel 3). Damit soll die Grundlage zur Vergleichbarkeit zwischen zukünftigen Partikelcharakterisierungen geschaffen werden. Schließlich wurde ein Multiplex-Assay mit farbstoffkodierten, Protein-abweisenden Partikeln entwickelt, um kleine Moleküle durch immunochemische Reaktionen in einem waschfreien Verfahren nachzuweisen (Kapitel 4). Letzteres verdeutlicht, dass eine hohe analytische Leistung mit neuem Potenzial an flexibler Funktionalität durch die Verwendung hybrider SiO2@PS-Partikel kombiniert werden kann. / Global megatrends such as demographic change, personalization, climate change or urbanization demand for increasingly flexible and mobile analytical measurement methods and assays. Especially in the environmental, agricultural, food and health sectors, chemical assays are a suitable choice. A large variety of such assays is available in the academic and industry area. However, their modification to measure new compounds is time-consuming and laborious, because they are typically designed to detect a specific single analyte. A modular platform for chemical assay development is thus highly desirable. Such a system should include the possibility for fast, easy and flexible implementation of various recognition types towards emerging analytes and the possibility for multi-parameter (multiplexed) detection in a potentially portable fashion. Single particle-based assays have proven to be an adequate solution here. In this work, I present hybrid polystyrene core-silica shell (SiO2@PS) particles as new spherical substrates for the flexible configuration of single particle-based chemical assays. First, a procedure to control the surface topology of the beads was developed, giving access to smooth, raspberry-like or multilayer-like CS structures. These particles were used for DNA detection down to the fmol-level (Chapter 2). A new tool to extract the roughness of the particles from electron microscopy images was developed next and applied to the wide range of CS beads prepared throughout the project (Chapter 3). This general protocol provides the basis for the comparability of future CS particle characterization. Finally, a multiplex assay with dye-encoded beads with non-fouling surfaces was developed to detect small molecules via immunochemical reactions in a wash-free procedure (Chapter 4). The latter ultimately proves that hybrid CS particles can combine high analytical performance and unmatched potential for flexible functionality. / Suspension Array Technology

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