The mobility of arsenic is controlled by the mineral source of arsenic and a host of biogeochemical factors such as pH, oxidation-reduction reactions, precipitation-dissolution reactions, adsorption-desorption processes, and the activity of microorganisms. In this study, sequential extraction and microscopic methods were used to evaluate arsenic partitioning in different phases in sediments and host rock at the Brinton arsenic mine (BAM) site. Results demonstrate spatial variability of arsenic in sediments, although the partitioning of arsenic in different phases was similar in both mine tailing and stream channel sediments. The sequential extraction results demonstrate that between 60 and 80 % of the total arsenic in sediments is associated with iron oxides, and an additional phosphate extraction showed that the majority (80%) of arsenic associated with the oxides is adsorbed. Imaging and analysis by scanning electron microscopy (SEM) and electron microprobe analysis (EMPA) show the presence of three arsenic bearing minerals, arsenopyrite, scorodite and arsenic-rich iron oxides, in both sediment and the host rock. In sediment, the minerals are present as individual grains, but in the host rock, they are present together, often with arsenopyrite at the core, surrounded by scorodite and/or elemental sulfur, which is rimmed by iron oxides. This spatial arrangement illustrates two weathering patterns of arsenopyrite, one that involves oxidation to form scorodite, which further dissolves to form arsenic-rich iron oxides; in this weathering series, sulfur presumably forms dissolved species which migrate away from the mineral. Another pattern, observed in several samples of host rock, involves formation of elemental sulfur in addition to scorodite and iron oxides. Results of this study have implications for arsenic mobility at the Brinton site and other mine sites where arsenic minerals are present. Although arsenopyrite is the main ore mineral, the main reservoir of arsenic in sediments is iron oxides. However, in the end it is the biogeochemical mechanism that releases arsenic from the mineral that will control arsenic mobility. In the case of iron oxides, desorption or reductive dissolution will promote arsenic release, whereas oxidizing conditions are required for arsenopyrite to release arsenic. / Master of Science

From June to November 2007, a microscopic analysis was conducted on the activated sludge from eleven selected wastewater treatment plants (WWTP's) belonging to the City of Cape Town. The primary objective was the identification of the dominant and secondary filamentous organisms. Other important criteria included were the floe character, diversity, filament index (Fl) and identification of the protozoan and metazoan communities. The operational data determined from routine analyses of the sludge, influent and effluent were used to assess the relationship of the filamentous population to wastewater characteristics and to compare this with previous findings. Fl values of >3 and dissolved sludge volume indices (DSVI's) of >150 were chosen as representing the possibility of bulking conditions being present. The five most prevalent dominant filaments were Type 0092, Type 1851, actinomycetes, Microthrix parvicella and Type 021N, being present in 74%, 31%, 22%, 17% and 14% of samples respectively. Type 0092 did not appear to be associated with bulking in any of the WWTP's, although it was often incidentally present as a co-dominant species when bulking conditions existed. All three WWTP's with the Modified Ludzack-Ettinger configuration harboured Type 1851 as the major dominant species, irrespective of whether the plants treated domestic or industrial effluent. Conditions suggestive of bulking were present in two of these WWTP's. Contrary to expectations, Type 1851 was often found as a dominant species where domestic waste was the primary influent. Type 021N and actinomycetes were strongly implicated when bulking occurred. The overgrowth of these filaments appeared to be related to factors such as nutrient deficiency (Type 021N) or the presence of large amounts of low molecular weight substances in the influent. Microthrix parvicella did not cause major bulking problems. There was a strong association between low levels of nitrates/nitrites in the clarifier supernatant and good phosphorous removal, irrespective of the configuration of the WWTP. The converse was also true. / Thesis ((M. Environmental Science))--North-West University, Potchefstroom Campus, 2009.

From June to November 2007, a microscopic analysis was conducted on the activated sludge from eleven selected wastewater treatment plants (WWTP's) belonging to the City of Cape Town. The primary objective was the identification of the dominant and secondary filamentous organisms. Other important criteria included were the floe character, diversity, filament index (Fl) and identification of the protozoan and metazoan communities. The operational data determined from routine analyses of the sludge, influent and effluent were used to assess the relationship of the filamentous population to wastewater characteristics and to compare this with previous findings. Fl values of >3 and dissolved sludge volume indices (DSVI's) of >150 were chosen as representing the possibility of bulking conditions being present. The five most prevalent dominant filaments were Type 0092, Type 1851, actinomycetes, Microthrix parvicella and Type 021N, being present in 74%, 31%, 22%, 17% and 14% of samples respectively. Type 0092 did not appear to be associated with bulking in any of the WWTP's, although it was often incidentally present as a co-dominant species when bulking conditions existed. All three WWTP's with the Modified Ludzack-Ettinger configuration harboured Type 1851 as the major dominant species, irrespective of whether the plants treated domestic or industrial effluent. Conditions suggestive of bulking were present in two of these WWTP's. Contrary to expectations, Type 1851 was often found as a dominant species where domestic waste was the primary influent. Type 021N and actinomycetes were strongly implicated when bulking occurred. The overgrowth of these filaments appeared to be related to factors such as nutrient deficiency (Type 021N) or the presence of large amounts of low molecular weight substances in the influent. Microthrix parvicella did not cause major bulking problems. There was a strong association between low levels of nitrates/nitrites in the clarifier supernatant and good phosphorous removal, irrespective of the configuration of the WWTP. The converse was also true. / Thesis ((M. Environmental Science))--North-West University, Potchefstroom Campus, 2009.

From June to November 2007, a microscopic analysis was conducted on the activated sludge from eleven selected wastewater treatment plants (WWTP's) belonging to the City of Cape Town. The primary objective was the identification of the dominant and secondary filamentous organisms. Other important criteria included were the floe character, diversity, filament index (Fl) and identification of the protozoan and metazoan communities. The operational data determined from routine analyses of the sludge, influent and effluent were used to assess the relationship of the filamentous population to wastewater characteristics and to compare this with previous findings. Fl values of >3 and dissolved sludge volume indices (DSVI's) of >150 were chosen as representing the possibility of bulking conditions being present. The five most prevalent dominant filaments were Type 0092, Type 1851, actinomycetes, Microthrix parvicella and Type 021N, being present in 74%, 31%, 22%, 17% and 14% of samples respectively. Type 0092 did not appear to be associated with bulking in any of the WWTP's, although it was often incidentally present as a co-dominant species when bulking conditions existed. All three WWTP's with the Modified Ludzack-Ettinger configuration harboured Type 1851 as the major dominant species, irrespective of whether the plants treated domestic or industrial effluent. Conditions suggestive of bulking were present in two of these WWTP's. Contrary to expectations, Type 1851 was often found as a dominant species where domestic waste was the primary influent. Type 021N and actinomycetes were strongly implicated when bulking occurred. The overgrowth of these filaments appeared to be related to factors such as nutrient deficiency (Type 021N) or the presence of large amounts of low molecular weight substances in the influent. Microthrix parvicella did not cause major bulking problems. There was a strong association between low levels of nitrates/nitrites in the clarifier supernatant and good phosphorous removal, irrespective of the configuration of the WWTP. The converse was also true. / Thesis ((M. Environmental Science))--North-West University, Potchefstroom Campus, 2009.

This research focuses on a study of the material parameters of horse hoof. The study of the problem with the factors that affect to the fastening of the shoe is not performed. Three different tests are carried out to obtain the behavior of the horn wall of the horse hoof in different ways, under physiological conditions and variation of hydration level. The first one is a tensile test to obtain both the force/displacement relation and the stress/strain relation and the parameters derived from them. The second is a hardness test to determine how the material resists to several kinds of permanent-shape changes when a force is applied.Finally, a microscopic study is performed to analyze the fracture surface after testing the specimens. A meticulous analysis of the results and a broad comparison with several researches are performed. The end of the thesis work suggests future works needed to solve the problem.

O objetivo principal desta tese é a determinação de procedimentos para implantação e avaliação do desempenho de Lombadas Eletrônicas em áreas urbanas, a partir de parâmetros relacionados às variáveis velocidade e acidentes. O procedimento para implantação de Lombadas Eletrônicas prevê a simulação do efeito desse dispositivo na velocidade veicular, através da utilização de modelos de previsão e de uma análise microscópica do tráfego. O procedimento para avaliacão do desempenho de Lombadas Eletrônicas busca determinar se estes dispositivos de controle têm resultados satisfatórios em relação à redução da velocidade veicular e, conseqüentemente, do número e gravidade dos acidentes. Ainda, foi realizado um estudo de caso para a aplicação dos procedimentos propostos para implantação e avaliação do desempenho de Lombadas Eletrônicas, através do qual procura-se mostrar a aplicabilidade desses procedimentos de uma maneira simples e clara. / The main objective of this work is the development of a procedure to implement and to evaluate the performance of Electronic Speed Barriers in urban areas. The procedure for Electronic Speed Barriers implementation includes the simulation of the device influence in vehicular speed, through forecasting models and microscopic traffic simulation analysis. The procedure for the evaluation of Electronic Speed Barriers seeks to determine if this control device has a satisfactory result in reducing vehicular speed, and accidents numbers and seriousness. The proposed procedures are applied to a case study in order to demonstrate their applicability.

O objetivo principal desta tese é a determinação de procedimentos para implantação e avaliação do desempenho de Lombadas Eletrônicas em áreas urbanas, a partir de parâmetros relacionados às variáveis velocidade e acidentes. O procedimento para implantação de Lombadas Eletrônicas prevê a simulação do efeito desse dispositivo na velocidade veicular, através da utilização de modelos de previsão e de uma análise microscópica do tráfego. O procedimento para avaliacão do desempenho de Lombadas Eletrônicas busca determinar se estes dispositivos de controle têm resultados satisfatórios em relação à redução da velocidade veicular e, conseqüentemente, do número e gravidade dos acidentes. Ainda, foi realizado um estudo de caso para a aplicação dos procedimentos propostos para implantação e avaliação do desempenho de Lombadas Eletrônicas, através do qual procura-se mostrar a aplicabilidade desses procedimentos de uma maneira simples e clara. / The main objective of this work is the development of a procedure to implement and to evaluate the performance of Electronic Speed Barriers in urban areas. The procedure for Electronic Speed Barriers implementation includes the simulation of the device influence in vehicular speed, through forecasting models and microscopic traffic simulation analysis. The procedure for the evaluation of Electronic Speed Barriers seeks to determine if this control device has a satisfactory result in reducing vehicular speed, and accidents numbers and seriousness. The proposed procedures are applied to a case study in order to demonstrate their applicability.

O objetivo principal desta tese é a determinação de procedimentos para implantação e avaliação do desempenho de Lombadas Eletrônicas em áreas urbanas, a partir de parâmetros relacionados às variáveis velocidade e acidentes. O procedimento para implantação de Lombadas Eletrônicas prevê a simulação do efeito desse dispositivo na velocidade veicular, através da utilização de modelos de previsão e de uma análise microscópica do tráfego. O procedimento para avaliacão do desempenho de Lombadas Eletrônicas busca determinar se estes dispositivos de controle têm resultados satisfatórios em relação à redução da velocidade veicular e, conseqüentemente, do número e gravidade dos acidentes. Ainda, foi realizado um estudo de caso para a aplicação dos procedimentos propostos para implantação e avaliação do desempenho de Lombadas Eletrônicas, através do qual procura-se mostrar a aplicabilidade desses procedimentos de uma maneira simples e clara. / The main objective of this work is the development of a procedure to implement and to evaluate the performance of Electronic Speed Barriers in urban areas. The procedure for Electronic Speed Barriers implementation includes the simulation of the device influence in vehicular speed, through forecasting models and microscopic traffic simulation analysis. The procedure for the evaluation of Electronic Speed Barriers seeks to determine if this control device has a satisfactory result in reducing vehicular speed, and accidents numbers and seriousness. The proposed procedures are applied to a case study in order to demonstrate their applicability.

<p>Composite materials used in the aviation industry are known to be more complex than their metallic predecessors. This impacts not only the design and manufacturing of composite structures, but also the failure studies when these structures fail and break (as may be the case in an aircraft accident). Additionally, when under combustion, composite materials introduce potential health hazards. At elevated temperatures, the fibers can be released, presenting an inhalation hazard. Similarly, the matrix decomposition results in a series of potentially toxic byproducts. When encountering composite fires at aircraft accident sites, a series of protocols have been delineated by the corresponding agencies. These include wearing personal protective equipment as well as the application of so-called fixant solutions over the burning composites, with the latter being the focus of this study. The purpose of the fixant solutions is to provide a film of protection that – in essence – holds down small fibers and prevents them from becoming airborne. While the use of fixant solutions is necessary to protect the health of individuals in the vicinity of burnt composites, the potential detrimental impact the application thereof has on fractographic evidence should also be considered. Experts in the field have voiced concerns regarding the use of fixants, outlining that these chemicals may wash evidence away, cover up evidence, or interfere with imaging methods needed during the failure analysis. The purpose of the conducted research, thus, was to compare the relative impact of four commonly used fixant solutions – namely water, wetted water, polyacrylic acid (PAA), as well as a mixture of water and floor wax – on fractographic features of failed carbon fiber/epoxy composite specimens. Specifically, fractographic evidence of two forms of damage – impact and tension – were evaluated. With this goal, the methodology included steps to manufacture the specimens of interest, introduce the two forms of damage, burn the specimens, apply fixants, and perform the microscopic analysis via a scanning electron microscope (SEM). The fractographic evidence prior and after the application of fixant was evaluated qualitatively and quantitatively. The results showed that the evaluated fixants did influence the fracture surfaces imaged, and in certain cased obscured evidence of interest. Additionally, differences between the fixants were ascertained for both forms of damage evaluated. The water treatment was found to perform the best, minimizing the disruption of evidence. Nonetheless, while the study did answer the research questions and the different treatments were compared, additional areas of research and factors that should be considered were identified. </p>

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