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M.Sc. (Chemistry) / Please refer to full text to view abstract

Electron irradiation may be a useful method for treating inorganic cosmetic powders such as talc for undesirable microorganisms if it can be established that no loss of quality or efficacy results as a consequence of the technique. A commercial electron accelerator was used to prepare bulk samples by exposure to electron irradiation under different conditions. A morphological characterisation of the control talc was carried out using microscopy techniques and focused on the particle size, shape and surface features of individual particles. Asperity dimensions vs. Roughness values were compared. Assessment of the bulk properties of the powders as a function of absorbed dose showed no serious impact on the quality or efficacy of the powder for cosmetic applications. The particle size and the level of dust expelled during impact were maintained. Changes to the surface chemistry of the irradiated powders were apparent from an increase in pH and water retention with increasing dose. Improvements to the fragrance retention occurred for both irradiated powders tested. Importantly a satisfactory microorganism level was achieved with the lowest absorbed dose level tested i.e. 5 kGy. Analysis of the crystallography did not show the development of a new phase. Mechanical testing using a slip-peel tester found an increase in the stick-slip behaviour occurred for the powder exposed to the highest absorbed dose only. Atomic force microscopy (AFM) testing of the lift-off force showed an increase in adhesion with increasing dose. Surface roughness increased with dose, while no change in elastic properties was found using nanoindentation suggesting the differentiating factor is due to surface features. Microstructural analysis used the transmission electron microscope (TEM). Voids were observed, which decrease in size, yet increase in number with increasing voltage. Prior to void development a loss of crystalinity is seen using electron diffraction. Explorative data analysis using factor analysis and Independent Component Analysis was performed on the void development data to discover the controlling mechanisms. Two distinct normally distributed populations were identified, each driven by 2-3 critical mechanisms. The distinct behaviour differences of the mechanisms may be utilised for characterisation of more complex properties of crystal microstructures.

Electron irradiation may be a useful method for treating inorganic cosmetic powders such as talc for undesirable microorganisms if it can be established that no loss of quality or efficacy results as a consequence of the technique. A commercial electron accelerator was used to prepare bulk samples by exposure to electron irradiation under different conditions. A morphological characterisation of the control talc was carried out using microscopy techniques and focused on the particle size, shape and surface features of individual particles. Asperity dimensions vs. Roughness values were compared. Assessment of the bulk properties of the powders as a function of absorbed dose showed no serious impact on the quality or efficacy of the powder for cosmetic applications. The particle size and the level of dust expelled during impact were maintained. Changes to the surface chemistry of the irradiated powders were apparent from an increase in pH and water retention with increasing dose. Improvements to the fragrance retention occurred for both irradiated powders tested. Importantly a satisfactory microorganism level was achieved with the lowest absorbed dose level tested i.e. 5 kGy. Analysis of the crystallography did not show the development of a new phase. Mechanical testing using a slip-peel tester found an increase in the stick-slip behaviour occurred for the powder exposed to the highest absorbed dose only. Atomic force microscopy (AFM) testing of the lift-off force showed an increase in adhesion with increasing dose. Surface roughness increased with dose, while no change in elastic properties was found using nanoindentation suggesting the differentiating factor is due to surface features. Microstructural analysis used the transmission electron microscope (TEM). Voids were observed, which decrease in size, yet increase in number with increasing voltage. Prior to void development a loss of crystalinity is seen using electron diffraction. Explorative data analysis using factor analysis and Independent Component Analysis was performed on the void development data to discover the controlling mechanisms. Two distinct normally distributed populations were identified, each driven by 2-3 critical mechanisms. The distinct behaviour differences of the mechanisms may be utilised for characterisation of more complex properties of crystal microstructures.

Th. doct.-ing--Génie géol. et minier--Nancy--I.N.P.L., 1980.

Made available in DSpace on 2014-06-12T15:08:13Z (GMT). No. of bitstreams: 2 arquivo271_1.pdf: 5494023 bytes, checksum: 1c6f69b922951a894bed654d0afd321c (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2010 / Universidade Federal de Pernambuco / A finalidade dessa investigação foi analisar a sustentabilidade do destino turístico de Fernando de Noronha com base na abordagem do ciclo de vida dos destinos turísticos e dimensões da sustentabilidade. O arcabouço teórico consultado foi guiado pela discussão acerca do turismo e seus aportes conceituais, as limitações e potencialidades do modelo teórico Tourism Areas Life Cycle (TALC) além do debate teórica sobre a sustentabilidade e sua dimensões e a análise da sustentabilidade de uma localidade o que serviu de base para proposta de adaptação do TALC às dimensões da sustentabilidade. O estudo se caracteriza como um estudo de caso qualitativo tendo sido realizado no Arquipélago de Fernando de Noronha atual distrito administrativo do Estado de Pernambuco, região Nordeste do Brasil. Para coleta de dados foram realizadas entrevistas semi-estruturadas, análise documental e observação direta. Os principais resultados da pesquisa são: 1) adaptação do TALC às dimensões da sustentabilidade se faz possível uma vez identificada a lacuna existente no modelo teórico sobre a impossibilidade de traçar ações em direção ao desenvolvimento sustentável; 2) Em apenas 44 anos Fernando de Noronha atingiu quatro dos seis estágios do ciclo de vida possíveis e presencia no momento atual um momento de sobreposição dos indicadores das fases de desenvolvimento e consolidação; 3) O arcabouço teórico consultado possibilitou o estabelecimento de 14 indicadores e 43 critérios de análise para avaliação das dimensões da sustentabilidade; e 4) a dimensão política-institucional apresentou o melhor resultado comparado às outras dimensões analisadas. Por fim, a investigação aponta para um retrato positivo acerca da sustentabilidade de Fernando de Noronha, embora tenha que ser considerado os aspectos limitantes do desenvolvimento da atividade turística, conforme exposto nos resultados das seis dimensões da sustentabilidade avaliadas neste trabalho

Ion-exchange equilibria between a 2molal aqueous Mg-Fe chloride solution and synthetic olivines, orthopyroxenes, orthoamphiboles and talcs have been experimentally bracketed between 450° and 800°C and between 1 and 4kb. Additional experiments at lower chloride molalities reveal that the distribution coefficient measured is dependent upon chloride concentration. Thermodynamic modelling of the chloride solution, assuming ideal mixing of Mg and Fe species, qualitatively reproduces this behavior if the Mg and Fe species have contrasting dissociation constants. Internally consistent thermodynamic properties of all four minerals and the 'delta' properties of a hypothetical associated electrolyte solution are calculated through a combination of linear programming and least-squares optimization while simultaneously considering constraints provided by calorimetry, net-transfer equilibria and other ion-exchange data. Adequate correspondence between thermodynamic model and the data cannot be attained without allowing the mixing of Mg and Fe in the chloride solution to be non-ideal. Qualitative constraints on the chloride 'excess' properties allow a preliminary estimate of the solid solution properties to be made. All solid solutions are modelled with a symmetric Margules formulation. The resulting olivine WG function has a value near 7kJ at 400°C and drops asymptotically toward zero at high temperatures. The orthopyroxene WG is approximately zero at 400°C and drops toward -3kJ at high temperatures. A 'microscopic' orthopyroxene solution model is formulated to be simultaneously consistent with this bulk excess free energy and with measured M1-M2 site distributions. The single WG value (0.58kJ) calculated for the anthophyllite solid solution is qualitatively consistent with fractionation of Fe into M4. The talc solid solution cannot be constrained to be different from ideal by the data presented here. At present, ion-exchange experiments with Mg-Fe chloride solutions can only be used to compare mineral properties due to uncertainties in dissociation constants and 'excess' properties for the aqueous solution. The role of such uncertainties in the data analysis indicates that solid solution properties derived from previous aqueous chloride ion-exchange experiments must be considered suspect until the properties of each pertinent aqueous electrolyte solution have been examined. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Reproduction de : Thèse de doctorat : Systèmes automatiques : Toulouse 3 : 2007. / Titre provenant de l'écran-titre. Bibliogr. p. 173-178.

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Thesis (Ph. D.)--University of Michigan, 1936. / "Reprinted from the Journal of the American chemical society, 58 ... (1936)."