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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Purification, detection and biological effects of cyanobacterial toxins

McElhiney, Jacqueline January 1999 (has links)
The aesthetic beauty of a landscape is a very subjective issue: every person has their own opinions and their own idea of what beauty is. However, all people have a common evolutionary history, and, according to the Biophilia hypothesis, a genetic predisposition to liking certain types of landscapes. It is possible that this common inheritance allows us to attempt to model scenic preference for natural landscapes. The ideal type of model for such predictions is the psychophysical preference model, integrating psychological responses to landscapes with objective measurements of quantitative and qualitative landscape variables. Such models commonly predict two thirds of the variance in the predications of the general public for natural landscapes. In order to create such a model three sets of data were required: landscape photographs (surrogates of the actual landscape), landscape preference data and landscape component variable measurements. The Internet was used to run a questionnaire survey; a novel, yet flexible, environmentally friendly and simple method of data gathering, resulting in one hundred and eighty responses. A geographic information system was used to digitise ninety landscape photographs and measure their landforms (based on elevation) in terms of areas and perimeters, their colours and proxies for their complexity and coherence. Landscape preference models were created by running multiple linear regressions using normalised preference data and the landscape component variables, including mathematical transformations of these variables. The eight models created predicted over sixty percent of variance in the responses and had moderate to high correlations with a second set of landscape preference data. A common base to the models were the variables of complexity, water and mountain landform, in particular the presence or absence of water and mountains was noted as being significant in determining landscape scenic preference. In order to fully establish the utility of these models, they were further tested against: changes in weather and season; the addition of cultural structures; different photographers; alternate film types; different focal lengths; and composition. Results showed that weather and season were not significant in determining landscape preference; cultural structures increased preferences for landscapes; and photographs taken by different people did not produce consistent results from the predictive models. It was also found that film type was not significant and that changes in focal length altered preferences for landscapes.
2

Potential and limits of Raman spectroscopy for carotenoid detection in microorganisms: implications for astrobiology

Jehlička, J., Edwards, Howell G.M., Osterrothova, K., Novotna, J., Nedbalova, L., Kopecky, J., Nemec, I., Oren, A. 13 December 2014 (has links)
No / In this paper, it is demonstrated how Raman spectroscopy can be used to detect different carotenoids as possible biomarkers in various groups of microorganisms. The question which arose from previous studies concerns the level of unambiguity of discriminating carotenoids using common Raman microspectrometers. A series of laboratory-grown microorganisms of different taxonomic affiliation was investigated, such as halophilic heterotrophic bacteria, cyanobacteria, the anoxygenic phototrophs, the non-halophilic heterotrophs as well as eukaryotes (Ochrophyta, Rhodophyta and Chlorophyta). The data presented show that Raman spectroscopy is a suitable tool to assess the presence of carotenoids of these organisms in cultures. Comparison is made with the high-performance liquid chromatography approach of analysing pigments in extracts. Direct measurements on cultures provide fast and reliable identification of the pigments. Some of the carotenoids studied are proposed as tracers for halophiles, in contrast with others which can be considered as biomarkers of other genera. The limits of application of Raman spectroscopy are discussed for a few cases where the current Raman spectroscopic approach does not allow discriminating structurally very similar carotenoids. The database reported can be used for applications in geobiology and exobiology for the detection of pigment signals in natural settings.
3

Filtros ecológicos: um estudo da remoção de produtos farmacêuticos e de cuidados pessoais e do efeito da contaminação no biofilme / Ecological filters: a study of the removal of pharmaceuticals and personal care compounds and the effect of the contamination in the biofilm

Pompei, Caroline Moço Erba 12 August 2016 (has links)
A contaminação do ambiente aquático e até mesmo da água de consumo por produtos farmacêuticos e de cuidados pessoais (PFCPs) é resultado das atividades antrópicas. Entre as tecnologias de tratamento de água, a filtração ecológica (modernização do termo filtro lento de areia) é atraente por ser um método natural de tratamento, de baixo custo e eficiência na remoção de patógenos e pode ser utilizada não só em grande escala, mas também domiciliar. O objetivo desta pesquisa foi avaliar a aplicabilidade dos filtros ecológicos abastecidos com água do Reservatório do Lobo, e a eficiência em remover produtos farmacêuticos e de cuidados pessoais. Além disso, foi avaliado o efeito da contaminação nas comunidades de algas e cianobactérias e de bactérias, presentes no biofilme dos filtros ecológicos. Os filtros ecológicos apresentaram boa remoção de coliformes fecais e Escherichia coli. Os PFCPs alvos deste estudo foram encontrados na água do Reservatório do Lobo em concentração da ordem de &#956g L-1. Os produtos de cuidados pessoais, metilparabeno e benzofenona-3,estiveram presentes em todas as amostras de água coletadas e foram os compostos encontrados em maior concentração no reservatório. Dois produtos de degradação dos compostos originais diclofenaco e benzofenona-3 foram identificados na água do reservatório. A porcentagem média global de remoção dos PFCPs pelos filtros ecológicos foi de 81,09% de paracetamol, 91,07% de diclofenaco, 97,33% de naproxeno, 99,57% de ibuprofeno, 70,81% de metilparabeno e 71,69% de benzofenona-3. Foi observado efeito da contaminação na comunidade de algas e cianobactérias. Aulacoseiragranulata, Chroococcus minutus, Dolichospermum planctonicum e Microcystis aeruginosa foram as espécies de algas e cianobactérias consideradas como descritoras em comum para todas as contaminações e tempos de coleta. Lepocincles sp. foi a espécie que mais contribuiu em biovolume durante o período experimental. A ocorrência, abundância e frequência destas espécies indicam uma possível tolerância das mesmas aos PFCPs. O desempenho dos filtros ecológicos de uso doméstico não foi afetado pela presença de 2 μg L-1 de PFCPs na água afluente. As espécies Bacillus anthracis e Exiquobacterium sp. foram resistentes aos compostos aplicados no filtro 2. A concentração de biomassa nos filtros aumentou significativamente com o tempo de operação e foi expressa em uma função exponencial de crescimento, mas não houve diferença significativa entre o filtro controle e o contaminado. / The contamination of the aquatic environment and even the water consumption with pharmaceutical and personal care products (PPCPs) is a result of human activities. Among the water treatment technologies, the ecological filtration (modern name for slow sand filter) is attractive because it is a natural treatment method, low cost and efficiency in removing pathogens and can be used not only in large scale, but also household. The objective of this research was to evaluate the applicability of ecological filters supplied with water from the Lobo Reservoir, and the efficiency in remove pharmaceuticals and personal care products. Furthermore, it was evaluated the effect of contamination in the communities of algae and cyanobacteria and bacteria, in the biofilm of the ecological filters. The ecological filters showed good removal of total coliforms and E. coli. The PPCPs aims of this study were found in the water from the Lobo Reservoir in order of &#956g L-1 of concentration. The personal care products, methylparaben and benzophenone-3, were present in all water samples, and the compounds were found at higher concentration in the reservoir. Two degradation products of the original compounds diclofenac and benzophenone-3 were identified in the water from reservoir. The overall average percentage of removal of PPCPs by ecological filters was 81,09% of paracetamol, 91,07% of diclofenac, 97,33% of naproxen, 99,57% of ibuprofen, 70,81% of methylparaben and 71,69% of benzophenone-3. It was observed an effect caused by contamination in the community of algae and cyanobacteria. Aulacoseira granulata, Chroococcus minutus, Dolichospermum planctonicum and Microcystis aeruginosa were the species of algae and cyanobacteria considered as descriptors in common for all contamination and collection times. Lepocincles sp. was the specie that most contributed in biovolume during the period. The occurrence, abundance and frequency of these species indicate a possible tolerance thereof to PPCPs. The performance of household ecological filters was not affected by the presence of 2 &#956g L-1 of PPCPs in affluent water. The species of bacteria Bacillus anthracis and Exiquobacterium sp. were resistant for the compound applied to the filter 2. The filter biomass concentration increased significantly with filter time and was summarised by an exponential growth function in both filters, but there was no substantial difference between the filter control and contaminated.
4

Filtros ecológicos: um estudo da remoção de produtos farmacêuticos e de cuidados pessoais e do efeito da contaminação no biofilme / Ecological filters: a study of the removal of pharmaceuticals and personal care compounds and the effect of the contamination in the biofilm

Caroline Moço Erba Pompei 12 August 2016 (has links)
A contaminação do ambiente aquático e até mesmo da água de consumo por produtos farmacêuticos e de cuidados pessoais (PFCPs) é resultado das atividades antrópicas. Entre as tecnologias de tratamento de água, a filtração ecológica (modernização do termo filtro lento de areia) é atraente por ser um método natural de tratamento, de baixo custo e eficiência na remoção de patógenos e pode ser utilizada não só em grande escala, mas também domiciliar. O objetivo desta pesquisa foi avaliar a aplicabilidade dos filtros ecológicos abastecidos com água do Reservatório do Lobo, e a eficiência em remover produtos farmacêuticos e de cuidados pessoais. Além disso, foi avaliado o efeito da contaminação nas comunidades de algas e cianobactérias e de bactérias, presentes no biofilme dos filtros ecológicos. Os filtros ecológicos apresentaram boa remoção de coliformes fecais e Escherichia coli. Os PFCPs alvos deste estudo foram encontrados na água do Reservatório do Lobo em concentração da ordem de &#956g L-1. Os produtos de cuidados pessoais, metilparabeno e benzofenona-3,estiveram presentes em todas as amostras de água coletadas e foram os compostos encontrados em maior concentração no reservatório. Dois produtos de degradação dos compostos originais diclofenaco e benzofenona-3 foram identificados na água do reservatório. A porcentagem média global de remoção dos PFCPs pelos filtros ecológicos foi de 81,09% de paracetamol, 91,07% de diclofenaco, 97,33% de naproxeno, 99,57% de ibuprofeno, 70,81% de metilparabeno e 71,69% de benzofenona-3. Foi observado efeito da contaminação na comunidade de algas e cianobactérias. Aulacoseiragranulata, Chroococcus minutus, Dolichospermum planctonicum e Microcystis aeruginosa foram as espécies de algas e cianobactérias consideradas como descritoras em comum para todas as contaminações e tempos de coleta. Lepocincles sp. foi a espécie que mais contribuiu em biovolume durante o período experimental. A ocorrência, abundância e frequência destas espécies indicam uma possível tolerância das mesmas aos PFCPs. O desempenho dos filtros ecológicos de uso doméstico não foi afetado pela presença de 2 μg L-1 de PFCPs na água afluente. As espécies Bacillus anthracis e Exiquobacterium sp. foram resistentes aos compostos aplicados no filtro 2. A concentração de biomassa nos filtros aumentou significativamente com o tempo de operação e foi expressa em uma função exponencial de crescimento, mas não houve diferença significativa entre o filtro controle e o contaminado. / The contamination of the aquatic environment and even the water consumption with pharmaceutical and personal care products (PPCPs) is a result of human activities. Among the water treatment technologies, the ecological filtration (modern name for slow sand filter) is attractive because it is a natural treatment method, low cost and efficiency in removing pathogens and can be used not only in large scale, but also household. The objective of this research was to evaluate the applicability of ecological filters supplied with water from the Lobo Reservoir, and the efficiency in remove pharmaceuticals and personal care products. Furthermore, it was evaluated the effect of contamination in the communities of algae and cyanobacteria and bacteria, in the biofilm of the ecological filters. The ecological filters showed good removal of total coliforms and E. coli. The PPCPs aims of this study were found in the water from the Lobo Reservoir in order of &#956g L-1 of concentration. The personal care products, methylparaben and benzophenone-3, were present in all water samples, and the compounds were found at higher concentration in the reservoir. Two degradation products of the original compounds diclofenac and benzophenone-3 were identified in the water from reservoir. The overall average percentage of removal of PPCPs by ecological filters was 81,09% of paracetamol, 91,07% of diclofenac, 97,33% of naproxen, 99,57% of ibuprofen, 70,81% of methylparaben and 71,69% of benzophenone-3. It was observed an effect caused by contamination in the community of algae and cyanobacteria. Aulacoseira granulata, Chroococcus minutus, Dolichospermum planctonicum and Microcystis aeruginosa were the species of algae and cyanobacteria considered as descriptors in common for all contamination and collection times. Lepocincles sp. was the specie that most contributed in biovolume during the period. The occurrence, abundance and frequency of these species indicate a possible tolerance thereof to PPCPs. The performance of household ecological filters was not affected by the presence of 2 &#956g L-1 of PPCPs in affluent water. The species of bacteria Bacillus anthracis and Exiquobacterium sp. were resistant for the compound applied to the filter 2. The filter biomass concentration increased significantly with filter time and was summarised by an exponential growth function in both filters, but there was no substantial difference between the filter control and contaminated.
5

Characterisation of engineered nanoparticles and their interaction with natural biological and non-biological material

Taylor, Cameron S. January 2014 (has links)
Form, mobility, toxicity and the eventual fate of engineered nanomaterials in environmental ecosystems are currently not well defined and are needed to improve risk assessment and legislation. The present study subjected uncoated zinc oxide (ZnO) nanoparticles (30nm and 200nm) and coated silver (Ag) nanoparticles (Paraffin: 3-8nm and citrate/PVP: 50nm) to different ionic strength media and different types of algal/bacterial extracellular-polymeric species (EPS) at long (6 months) and short (2 weeks) timescales. Changes in particle size distribution and stability were examined using a multi-method approach. Sample concentration and sample polydispersity are important factors when selecting techniques. Uncoated ZnO nanoparticles aggregated heavily in water at high concentrations (1000mg/L). However silver nanoparticles (1-10mg/L) remained stable at all ionic strengths and EPS in this study due to the steric component of their coatings. Nano-toxicological experiments involving cyanobacteria S.leopoliensis and green algae C.reinhardtii showed size-dependent toxicity from coated nanosilver particles. Smaller nanoparticles (3-8nm) showed greater dissolution over 72h and greater toxicity to both species than 50nm particles indicating silver ions are an important toxicity mechanism. Nanoparticle coatings were likely important in controlling dissolution levels. Cell viability and production of reactive oxygen species (ROS) were shown to be important mechanisms of toxicity to phycological species. Species specific effects were noted for both silver nanoparticles. EPS from S.leopoliensis were noted to remove ionic silver from suspension and different types of C.reinhardtii EPS were produced when particles underwent different levels of toxic stress indicating that EPS could both affect particle toxicity and be affected by it. This work has demonstrated that coated nanoparticles could remain stable under various ionic strengths and with exposure to algal organic matter for timescales up to 6 months. This could result in adverse effects to aquatic organisms were they to reach environmental systems and is of concern to nanomaterial risk assessors.

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