Grazing incidence pumping (GRIP) is a scheme to produce x-ray lasers and extreme ultraviolet lithography is a means of lithographic production which requires soft x-rays with a bandwidth of 2% centred at 13,5 nm. In this work firstly a grazing incidence pumping of Ni-like Mo and Ne-like Ti x-ray laser media were simulated by using EHYBRID and a post-processor code coupled to it. The required atomic data were obtained from the Cowan code. Besides, the timing issue needed for amplification purpose in a Ti:Sapphire laser system has been described theoretically. Afterwards, in order to produce soft x-ray lasers for extreme ultraviolet lithographic applications, emission of soft x-rays in the 2% bandwidth centred at 13.5 nm emitted from Sn XII and Sn XIII ions were simulated by using the EHYBRID code for a laser operating at 1064 nm with 1 J of pulse energy and 6 ns of pulse duration. The intensity range that has been investigated is between 1-5 x 1012 W/cm2. Ion fractions of tin ions and line intensities corresponding to different electron temperatures were calculated by using the collisional radiative code NeF.

An almost universal instability in high pressure plasmas is the Neoclassical Tearing Mode (NTM). NTMs are driven by local perturbations in the current density and result in magnetic island like deformations of the magnetic topology. They can be stabilized by compensating the current perturbations with local electron cyclotron resonance heating (ECRH) or with non-inductive current drive (ECCD). The modified Rutherford equation describes the nonlinear evolution of tearing modes as determined by various contributions to the local current density pertubation. An extensive investigation of the two terms representing the stabilizing effects from ECRH and ECCD have been made resulting in accurate description of both terms. The results of this model can now be compared to the experimental observations. For this purpose, an extensive data set exists from the past experiments on tearing mode stabilization by ECRH and ECCD on TEXTOR. The properly benchmarked model can then be used to predict the effectiveness of ECRH and ECCD for NTM stabilization on International Thermonuclear Experimental Reactor (ITER). In addition, a number of predictions on the effects of ECRH and ECCD on the growth of the NTM have been made on the basis of crude approximations to the ECRH and ECCD tems in the modified Rutherford equation. These predictions can now be checked against the more accurate expressions obtained.

In this study numerical modelling of a moderate pressure DC glow discharge plasma is car- ried out in 1D and 2D geometry. The governing equations include continuity equations for the plasma species (electrons, positive ions and metastable atoms), the electron energy equation (EEE), Poisson equation for the electric

Aim of this thesis is to investigate the optimum working parameters of a helium-neon laser. Partial pressure ratios, total pressures of the gases and voltage-current characteristics were studied. The analysis of the results includes the minor factors (impurity, volume, etc.) and their effects to main parameters (laser power, voltage, current). Tables, which were formed by measured optical parameters as wavelength and power, converted to graphs and from these graphs optimal working conditions for the laser are obtained.

Large areas of northern peatlands have been drained and afforested in the second half of the 20th century with significant impacts on important ecosystem services, including loss of biodiversity and potential changes in C storage. A considerable effort is currently invested into restoring original peatland function and ecosystem services, with an increasing area of newly restored peatland areas over recent years. However, the effect of restoration on the greenhouse gas (GHG) budget is unknown. This study is the first quantification of CO2, CH4 and N2O fluxes from forest-to-bog restoration sites spanning 0 to 17 years in age. Further, the impact of afforestation on peat decomposition is measured in situ, and the impact of afforestation on the biochemical composition of the peat in relation to CO2 and CH4 fluxes is investigated. Results show that forest-to-bog restoration is successful from a GHG perspective, since all three major GHG fluxes of the restoration sites are changing along the chronosequence towards the fluxes from near pristine bog sites. The peat decomposition rate under the forest plantations is a big part of the total soil respiration at 126.8 ± 14.7 g C m-2 y-1 (44% of total soil CO2 efflux) and our results indicate a slowing down of peat decomposition towards the near pristine bog. CH4 fluxes increase with restoration age, whilst all sites remain a small sink for N2O. I observed changes in peat quality and nutrient availability in the pore water under forests. Different CO2 fluxes between vegetation-free peat cores from different sites for the same temperature and water level show that these differences in peat quality and nutrient availability shape the biogeochemical processes in the peatlands. However only small differences in CH4 fluxes between sites were evident, suggesting that on its own (and in absence of biotic interactions under field conditions), forestry effects on CH4 flux are limited.

This study is made to understand the opportunities and challenges SMEs have to adopt GHG calculation tools. Adoption of GHG calculation tools are common by large organizations and have proven as a consequence to lower their GHG emissions, motivate their employees and establish sustainability goals. Even thou a large amount of large organizations have adopted GHG calculation tools, this is very rare in SMEs. Using the theoretical framework called Rogers diffusion of innovation theory and a survey, the factors behind why or why not SMEs have adopted GHG calculation tools were studied. The results showed that only 9% of SMEs have adopted GHG calculation tools and the reason for this is lack of resources, competence and data. The analysis showed that the characteristics of an organization that affects this the most are leadership, education and regulations. In order to overcome the challenges, organizations should prioritize to have a leadership that motivates employees to engage in sustainability actions. Organizations should enable skill development in the field of sustainability to increase the competence. This would enable more organization to adopt GHG calculation tools and most likely lower their GHG emissions.

Ammonium Nitrate-Fuel Oil (ANFO) is the explosive generally used in the mining industry to blast ore from the rock face. The use and detonation of ANFO explosives in an underground mine is an intrinsically hazardous process. The by-products formed during blasting have been well studied over the years and modern mining techniques and methods have evolved to mitigate the inherent blasting and gas emission risks. However, there is insufficient research and quantitative data on mine workers’ respiratory exposure to blasting gasses under realistic underground conditions. Aim: The objective of this study was to determine whether blasting gasses such as nitric oxide (NO), nitrogen dioxide (NO2) and ammonia (NH3) pose an inhalation health risk to underground mine workers cleaning at the blasting panels approximately three hours after the detonation of ANFO explosives. Scraper Winch Operators’ (SWOs) respiratory exposure to selected blasting gasses was simultaneously sampled by means of active and passive sampling methodologies. Method: Personal exposures to NO, NO2 and NH3 were measured and analysed in accordance with NIOSH methods 6014 and 6015. Along with the active air samplers, respiratory exposure to NO2 and NH3 were measured by means of radial symmetry diffusive samplers (Aquaria® RING). Measurements were taken over an 8-hour period, where this was not applicable; results were time weighed to an average 8-hour exposure concentration in order to compare the Scraper Winch Operators’ (SWOs) respiratory exposure to the Occupational Exposure Limits (OELs) contained in the Regulations of the Mine Health and Safety Act (No. 29 of 1996). Results: The active air sampling results indicated that the SWOs’ respiratory exposure to NO, NO2 and NH3 complied with their respective OELs contained in the Regulations of the Mine Health and Safety Act (No. 29 of 1996). However, one of the SWOs had an exposure which exceeded the action level (50% of OEL) at which level the implementation of control measures are recommended to reduce the SWO’s exposure. Based on the results of the Wilcoxon matched pairs test, statistical significant differences were observed between the exposure results of the two sampling methodologies for NO2 (p = 0.00078) and NH3 (p = 0.044), with the passive diffusive sampling technique under sampling when compared to the active sampling method. This was also confirmed by a Spearman rank order correlation which indicated a poor relationship between the two sampling methods for NO2 (r = -0.323) and NH3 (r = 0.090). Environmental conditions (i.e. temperature and humidity), as presented in an underground mine, may have been a major factor for the variation between the two sampling methods, mostly affecting the passive samplers. Conclusion: It was established that engineering and administrative control measures implemented at the underground mine were effective to control SWOs’ respiratory exposure to NO, NO2 and NH3 below their respective OELs. An acute health risk pertaining the inhalation of blasting gasses was, therefore, not presented to mine workers cleaning at the blasting panels approximately three hours after the detonation of ANFO explosives. However, long-term exposure to blasting gasses at low concentrations may present SWOs with a health risk if such exposures are not adequately controlled or mitigated. The dilution and production of blasting gasses also varied from one blasting level to another. Geological formation, explosive charge-up and loading practices, the amount of water vapour inside the stopes and ventilation parameters are among the factors that may have affected the amount of blasting gasses produced underground. In addition, a drop in the carbon monoxide levels as indicated by the mine’s central gas monitoring system would not necessarily mean a lowering in other blasting gas concentrations (i.e. elevated ammonia gas concentrations as identified in the present study). The personal exposure levels between the active and passive sampling measurements also differed considerably. This may be ascribed to the impact underground mining conditions and processes had on the sampling media as well the complexities involved when sampling blasting gasses in general. / MSc (Occupational Hygiene), North-West University, Potchefstroom Campus, 2014

Ammonium Nitrate-Fuel Oil (ANFO) is the explosive generally used in the mining industry to blast ore from the rock face. The use and detonation of ANFO explosives in an underground mine is an intrinsically hazardous process. The by-products formed during blasting have been well studied over the years and modern mining techniques and methods have evolved to mitigate the inherent blasting and gas emission risks. However, there is insufficient research and quantitative data on mine workers’ respiratory exposure to blasting gasses under realistic underground conditions. Aim: The objective of this study was to determine whether blasting gasses such as nitric oxide (NO), nitrogen dioxide (NO2) and ammonia (NH3) pose an inhalation health risk to underground mine workers cleaning at the blasting panels approximately three hours after the detonation of ANFO explosives. Scraper Winch Operators’ (SWOs) respiratory exposure to selected blasting gasses was simultaneously sampled by means of active and passive sampling methodologies. Method: Personal exposures to NO, NO2 and NH3 were measured and analysed in accordance with NIOSH methods 6014 and 6015. Along with the active air samplers, respiratory exposure to NO2 and NH3 were measured by means of radial symmetry diffusive samplers (Aquaria® RING). Measurements were taken over an 8-hour period, where this was not applicable; results were time weighed to an average 8-hour exposure concentration in order to compare the Scraper Winch Operators’ (SWOs) respiratory exposure to the Occupational Exposure Limits (OELs) contained in the Regulations of the Mine Health and Safety Act (No. 29 of 1996). Results: The active air sampling results indicated that the SWOs’ respiratory exposure to NO, NO2 and NH3 complied with their respective OELs contained in the Regulations of the Mine Health and Safety Act (No. 29 of 1996). However, one of the SWOs had an exposure which exceeded the action level (50% of OEL) at which level the implementation of control measures are recommended to reduce the SWO’s exposure. Based on the results of the Wilcoxon matched pairs test, statistical significant differences were observed between the exposure results of the two sampling methodologies for NO2 (p = 0.00078) and NH3 (p = 0.044), with the passive diffusive sampling technique under sampling when compared to the active sampling method. This was also confirmed by a Spearman rank order correlation which indicated a poor relationship between the two sampling methods for NO2 (r = -0.323) and NH3 (r = 0.090). Environmental conditions (i.e. temperature and humidity), as presented in an underground mine, may have been a major factor for the variation between the two sampling methods, mostly affecting the passive samplers. Conclusion: It was established that engineering and administrative control measures implemented at the underground mine were effective to control SWOs’ respiratory exposure to NO, NO2 and NH3 below their respective OELs. An acute health risk pertaining the inhalation of blasting gasses was, therefore, not presented to mine workers cleaning at the blasting panels approximately three hours after the detonation of ANFO explosives. However, long-term exposure to blasting gasses at low concentrations may present SWOs with a health risk if such exposures are not adequately controlled or mitigated. The dilution and production of blasting gasses also varied from one blasting level to another. Geological formation, explosive charge-up and loading practices, the amount of water vapour inside the stopes and ventilation parameters are among the factors that may have affected the amount of blasting gasses produced underground. In addition, a drop in the carbon monoxide levels as indicated by the mine’s central gas monitoring system would not necessarily mean a lowering in other blasting gas concentrations (i.e. elevated ammonia gas concentrations as identified in the present study). The personal exposure levels between the active and passive sampling measurements also differed considerably. This may be ascribed to the impact underground mining conditions and processes had on the sampling media as well the complexities involved when sampling blasting gasses in general. / MSc (Occupational Hygiene), North-West University, Potchefstroom Campus, 2014

Greenhouse gasses, such as carbon dioxide and methane absorb and emit heat radiation, which contribute to global warming. Human activities such as increased emissions through burning of fossil fuels and deforestation drive this climate threat. International treaties such as the Paris agreement, enables stakeholders to mitigate effects of climate impact and create new sustainable markets. Various carbon offset projects on the voluntary market are an attempt to neutralize climate impact. In this report we identify five main project types for carbon offsets: i) forestry and land use, ii) renewable energy and energy effectivization, iii) transport, iv) waste handling and v) household devices. These project types are evaluated against UNs 17 sustainable development goals. The results show a net positive impact on goal 13, Climate action, for all project types, which is congruent with the focus on carbon offsetting. The results also show that impact varies depending on how the project is deigned. Climate offsetting has enabled multiple stakeholders to contribute to climate change mitigation. Despite many global benefits, carbon offsets have been subject to criticism in cases where the concept is not used as intended. There are currently no clear guidelines as to when focus for companies should shift from internal reduction to external reduction through offsetting. Validation of carbon offsets is another problematic aspect, as there is no one standard for the market to secure the quality of projects.

Manguezais são ambientes costeiros que proveem diversos recursos para ecossistemas adjacentes devido à alta produtividade decorrente da decomposição de matéria orgânica e principalmente da constante ciclagem de carbono, realizada pelas comunidades microbianas presentes nos sedimentos. Desde a década de 70, com o aumento da liberação de gases pela queima de combustíveis fósseis, diversas anormalidades, como o aumento da temperatura e acidificação dos oceanos, têm sido observadas. Com base na hipótese de que as mudanças climáticas provocam alterações na diversidade microbiana associada à decomposição da matéria orgânica em sedimentos de manguezais, estimulando a liberação de Gases do Efeito Estufa (GEE), o presente estudo teve como objetivo avaliar a dinâmica da diversidade microbiana sob alteração das condições climáticas durante o processo de decomposição, correlacionando-a com a emissão de GEE. Microcosmos destrutivos contendo material orgânico proveniente das principais espécies vegetais encontradas nos manguezais do Estado de São Paulo (Rhizophora mangle, Laguncularia racemosa e Avicennia schaueriana) foram incubados em condições simulando as mudanças climáticas (aumento de temperatura e pH). Amostragens do material em decomposição (para sequenciamento da região 16S rRNA e quantificação do gene mcrA) e de gases foram coletadas durante 45 dias. As variações no tempo resultaram em impactos significativos no aumento da α diversidade e na composição da comunidade, inicialmente com maior abundância de Gammaproteobacteria para todas as espécies vegetais independente das variações nas condições climáticas. Análises do tipo PCoA evidenciaram o processo de sucessão em decorrência do tempo na β diversidade, indicando o aumento da incidência de Deltaproteobacteria ao final do processo. As emissões de GEE variaram em função da fonte de material orgânico e observou-se relação entre a emissão de metano (CH4) e a presença do gene mcrA em duas das espécies vegetais estudadas, admitindo-se que o aumento na população de Deltaproteobacteria tenha controlado sua emissão. Apesar da quantidade de estudos relacionados à decomposição de matéria orgânica, à diversidade microbiana e à emissão de gases em manguezais, poucos apresentam uma abordagem como a proposta pelo presente trabalho, que busca compreender melhor a relação entre os três processos, relacionando-os a um quarto evento, as alterações climáticas, que são um problema imanente da atualidade. / Mangrove are coastal environments that provide resources for adjacent ecosystems due to its high productivity that comes from decay of organic matter and carbon cycling, made by microbial communities in sediments. Since the increase of gas release due to fossil fuel burning in the 1970\', many abnormalities have been observed such as temperature and acidification increase. Base on the hypothesis that climate change modifies microbial diversity associate to decay of organic matter in mangrove sediments, changing the emission of Greenhouse Gases (GHG) rate, the goal of this research is to evaluate the dynamics of microbial diversity under the climate change conditions during de decay process, correlating with the emission of GHG. Destructive microcosms containing organic matter from the main plant species found in mangroves throughout the State of São Paulo, Brazil (Rhizophora mangle, Laguncularia racemosa e Avicennia schaueriana) were incubate simulating climate changes (increase in temperature and pH). Sampling of decaying material (for sequencing of 16S rRNA region and quantification of the mcrA gene) and of gasses were collected for 45 days. The variation in time resulted in important increases of α diversity impacts and in the community composition, initially with greater abundancy of Gammaproteobacteria for all plant species despite of the climate conditions variations. The PCoA analysis bespeak the chronological sequence in β diversity, indicating the increase of Deltaproteobacteria at the end of the process. The GHG emission varied in function of the organic matter source and the relation between methane (CH4) release and the presence of the mcrA gene in two of the plant species studied, if the increase in the Deltaproteobacteria population controlled its emission. Despite the great number of studies about the decay of organic matter and emission of gases in mangroves, few present an approach like this work, which aims to understand the relation between these three processes and the climate changes, a pressing problem nowadays.