Les travaux concernent la mise au point et l'étude de microcapsules de composés naturels réticulés pour des applications en cosmétologie. / The study deals with the development of microcapsules from reticulated natural products, for cosmetological applications.

Made available in DSpace on 2014-06-11T19:25:27Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-11-24Bitstream added on 2014-06-13T20:53:20Z : No. of bitstreams: 1 matos_fc_me_arafcf.pdf: 1148382 bytes, checksum: acb5e1bbfbec2e34aa0311d72ae2a142 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Universidade Estadual Paulista (UNESP) / Os polissacarídeos naturais vêm sendo extensamente usados no desenvolvimento de formas farmacêuticas sólidas para liberação prolongada de fármacos, fato demonstrado na literatura por inúmeros estudos de utilização de polissacarídeos como quitosana, pectina, sulfato de condroitina, ciclodextrinas, dextranas, inulina, amilose e galactomananas de goma de guar e de alfarroba. Neste trabalho, os polímeros de galactomananas de flamboyant (Delonix regia) e de Carolina (Adenanthera pavonina), que são vegetais pertencentes à família Leguminosae, foram estudados após serem reticuladas por reação com trimetafosfato de sódio, um agente reticulante adequado para o uso farmacêutico e alimentício e avaliou-se os diferentes graus de reticulação das gomas em função da variação do tempo de reação (30 min. a 4 horas) e da concentração de base no meio reacional( 2% e 4%). As técnicas analíticas empregadas mostraram-se úteis na avaliação do grau de reticulação das amostras, exceto a espectroscopia na região do infravermelho, que não permitiu estabelecer diferenças entre as estruturas obtidas com diferentes graus de reticulação. A técnica da reologia apresentou-se como uma ferramenta importante na análise dos polímeros. Através das análises de viscoelasticidade foi possível observar mudanças significativas no comportamento viscoelástico dos polímeros reticulados quando comparados aos polímeros não-reticulados, oriundos do flamboyant ou da carolina. Para todos os tempos de reticulação, o módulo G’ apresentou valores maiores para os polímeros reticulados em comparação aos polímeros não reticulados, para todos os tempos de reticulação. A análise do grau de intumescimento das partículas aliada à reologia mostrou ser útil para a caracterização dos polímeros, permitindo observar que os produtos reticulados de ambas as origens tiveram sua capacidade... / The natural polysaccharides have been extensively used in the development of solid dosage forms for sustained release of drugs, a fact demonstrated by countless studies in the literature about the use of polysaccharides such as chitosan, pectin, chondroitin sulphate, cyclodextrins, dextran, syrup, starch and gum galactomannans of guar and carob. In this work, the polymers of galactomannans of Flamboyant (Delonix regia) and Carolina (Adenanthera pavonina), which are plants belonging to the family Leguminosae, were studied after a cross-linked reaction with sodium trimetaphosphate, which is a cross-linked agent suitable for pharmaceutical and food use. Then, from this study, the different cross-linked degrees of gum depending on the variation of the reaction time (30 minutes to 4 hours) and the concentration of base in the middle reaction (2% and 4%) were analyzed. The analytical techniques employed have proved useful in assessing the cross-linked degree of the samples, except in the infrared spectroscopy, which failed to establish differences between the structures obtained with different degrees of cross-linkage action. The rheology technique presented itself as an important tool in the analysis of polymers. Through the viscoelasticity analysis it was possible to see significant changes in the viscoelastic behavior of cross-linked polymers when compared to non-cross-linked polymers, from the Flamboyant or the Carolina. For all times of reticulation, the module G had higher values for the cross-linked polymers when compared to non-cross-linked polymers, for all times of cross-linkage actions. The analysis of the degree of swelling of the particles combined with rheology has shown to be useful for the characterization of polymers, enabling the observation that the cross-linked products of both origins had their ability to absorb water increased significantly in relation to non-cross-linked... (Complete abstract click electronic access below)

Because of a continuous increase in the demand for electricity in South Africa the country’s largest electricity utility (Eskom) has been under strain to provide electricity. An expansion programme to generate more electricity has caused a continuous increase in utility costs. Steep electricity tariff increases have forced large electricity consumers, such as the mining industry, to focus on energy efficiency and demand side management (DSM). More recently, large industrial action has affected the marginality of the mining industry in such a way that mining groups were forced to cut down on production cost and even sell mining shafts. A solution has to be found to improve the marginality of these mines. DSM intervention on mine water reticulation systems has shown great promise in the past and has been implemented on many South African mines with great success. Many mines with smaller systems have not been optimised because the priority of DSM intervention was to achieve the largest saving; therefore, larger systems enjoyed priority over smaller systems. This only added to the increased financial pressure on already marginal mines. In this study the operation of a mine water reticulation system will be studied to identify the most efficient DSM interventions to implement. DSM intervention on dewatering-, refrigeration- and water distribution systems will be investigated to get a better understanding of the functions of these operations. Previous project data will be analysed to create tools that would assist in the decision-making process for DSM intervention regarding saving potential, cost benefit and cost implication. This data would ultimately assist in determining a project’s payback period that is used to prioritise DSM intervention applications. A mining group will be analysed to identify possible DSM intervention potential. The systems will be investigated and the best strategy for DSM intervention will be selected. This study will conclude that it is financially feasible to implement DSM interventions on marginal mines’ dewatering systems. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2014

Because of a continuous increase in the demand for electricity in South Africa the country’s largest electricity utility (Eskom) has been under strain to provide electricity. An expansion programme to generate more electricity has caused a continuous increase in utility costs. Steep electricity tariff increases have forced large electricity consumers, such as the mining industry, to focus on energy efficiency and demand side management (DSM). More recently, large industrial action has affected the marginality of the mining industry in such a way that mining groups were forced to cut down on production cost and even sell mining shafts. A solution has to be found to improve the marginality of these mines. DSM intervention on mine water reticulation systems has shown great promise in the past and has been implemented on many South African mines with great success. Many mines with smaller systems have not been optimised because the priority of DSM intervention was to achieve the largest saving; therefore, larger systems enjoyed priority over smaller systems. This only added to the increased financial pressure on already marginal mines. In this study the operation of a mine water reticulation system will be studied to identify the most efficient DSM interventions to implement. DSM intervention on dewatering-, refrigeration- and water distribution systems will be investigated to get a better understanding of the functions of these operations. Previous project data will be analysed to create tools that would assist in the decision-making process for DSM intervention regarding saving potential, cost benefit and cost implication. This data would ultimately assist in determining a project’s payback period that is used to prioritise DSM intervention applications. A mining group will be analysed to identify possible DSM intervention potential. The systems will be investigated and the best strategy for DSM intervention will be selected. This study will conclude that it is financially feasible to implement DSM interventions on marginal mines’ dewatering systems. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2014

RSAT (Reticulation Sag And Tension) software is a tool available for use as part of the medium voltage Eskom Distribution standard. This software is scrutinised for its usability and for errors such that it can be revised to improve the usability of the tool. The type of software being studied is used to ensure optimum design performance and reduce the probability of a conductor failure on distribution lines. The algorithms for calculating tension, sag and clearance values take into account research into optimum design tensions. This ensures low bending forces due to conductor vibration. An algorithm for creep is designed based on common life expectancy of line conductors. The design methodology and algorithms were then put into software form as RSAT. Review and alterations include the changing of compiler, user interface, data storage mechanisms and the inclusion of options allowing the addition of new data.

Les synapses sont des structures fortement compartimentées remplies de complexes de protéines intéragissant entre elles. La fente synaptique reliant les compartiments pré- et post-synaptiques est une zone adhésive de 20 nm d'épaisseur, contenant des protéines d'adhésion et des récepteurs neurotransmetteurs. Les progrès dans l'imagerie à haute résolution offrent une vision améliorée de l'organisation dynamique des protéines synaptiques. Cependant, une évaluation quantitative de la concentration et du niveau d'oligomérisation de ces complexes reste difficile. Ceci est en partie dû au fait que les méthodes traditionnelles d'identification des récepteurs s'appuient sur des anticorps, dont la taille relativement grande (~ 15 nm) peut conduire à un empêchement stérique et un biais de localisation, alors que leur divalence provoque une réticulation des protéines. Ici, nous avons étudié l'impact de la valence de la sonde et des récepteurs sur la diffusion et l'organisation de 3 protéines synaptiques : Neurexin1β, neuroligine1 et la sous-unité du récepteur kainate GluK2. Nous avons utilisé une technique de single molecule pull down pour caractériser la composition de la sous-unité de ces protéines en observant des protéines possédant un tag GFP immobilisées sur un subtrat en utilisant une illumination TIRF. La neurexin1β présente essentiellement un step de photoblanchiment, tandis que la neuroligine1 présente principalement 2 steps, et GluK2 montre plusieurs steps, confirmant que ces protéines se rassemblent respectivement en monomères, dimères et tétramères. Ensuite, nous avons utilisé le FRAP pour surveiller la diffusion membranaire des 3 protéines marquées avec des sondes de valence différente. Nous avons étiqueté des protéines recombinantes portant un marqueur N-terminal biotinylé avec une streptavidine monovalente, divalente ou tétravalente (ou avec un anticorps anti-biotine), tous conjugués aux mêmes fluorophore organiques. Nous avons également utilisé une technique de STORM pour caractériser le niveau d'agrégation des 3 protéines en réponse aux différentes sondes. Nous montrons des effets drastiques en fonction de la nature de la protéine utilisée et de la valence de la sonde, suggérant que la diffusion est ralentie par l'agrégation des récepteurs, mettant ainsi en évidence les enjeux cruciaux dans les stratégies d'étiquetage, en particulier dans des espaces confinés tels que les synapses / Synapses are highly compartmentalized structures packed with interacting protein complexes. The synaptic cleft bridging pre- and post-synaptic compartments is an adhesive zone ~20 nm thick, containing adhesion proteins and neurotransmitter receptors. Progress in super-resolution imaging offers an improved view of the dynamical organization of synaptic proteins. However, a quantitative assessment of the concentration and oligomerization level of those complexes remains difficult. This is in part because traditional ways to label receptors rely on antibodies, whose relatively large size (~15 nm) may lead to steric hindrance and localization bias, while their divalence causes protein cross-linking. Here, we studied the impact of probe and receptor valence on the diffusion and organization of 3 synaptic proteins: neurexin1β, neuroligin1, and the GluK2 kainate receptor subunit. We used single molecule pull-down to characterize the subunit composition of those proteins, by observing immobilized GFP-tagged proteins under TIRF illumination. Neurexin1β shows essentially 1 photo-bleaching step, while neuroligin1 exhibits mostly 2 steps, and GluK2 shows multiple steps, confirming that those proteins assemble into monomers, dimers, and tetramers, respectively. Then, we used FRAP to monitor the surface diffusion of the 3 proteins labeled with probes of different valence. We labeled recombinant proteins carrying a biotinylated N-terminal tag with monomeric, dimeric, or tetrameric streptavidin (or with biotin antibody), all conjugated to the same organic dyes. We also used STORM to characterize the aggregation level of the 3 proteins in response to the different probes. We show drastic effects depending on the nature of the protein used and the probe valence, suggesting that diffusion is slowed down by receptor aggregation, thereby highlighting the crucial issues at stake in labelling strategies, especially in confined spaces such as synapses.

Les protéines sont impliquées dans de nombreux processus biologiques. Il est nécessaire pour comprendre en détail leur fonction et leur mode d'action afin d'obtenir des informations sur leur structure et sur leurs interactions éventuelles avec leurs partenaires. Le travail réalisé durant cette thèse a consisté à développer deux méthodes innovantes utilisant la spectrométrie de masse pour étudier la structure des protéines et à appliquer ces méthodes à une problématique biologique. Nous avons optimisé une méthode associant les échanges H/D et la spectrométrie de masse sur une protéine modèle, la protéine PBP-2X. L'utilisation combinée de trois protéases nous a permis d'obtenir un meilleur recouvrement de séquence de la protéine étudiée et une plus grande résolution spatiale dans la localisation des zones d'intérêt. Une méthode associant la réticulation chimique et la spectrométrie de masse a été mise au point sur une protéine modèle : le cytochrome c. Les contraintes de distances ainsi obtenues vont intervenir dans une démarche bioinformatique visant à déterminer la famille de repliement d'une protéine de structure inconnue. Enfin, ces deux méthodes ont été appliquées avec succès sur des protéines du système de sécrétion de type III de Pseudomonas aeruginosa : PcrV et PcrG. Nos résultats expérimentaux sur PcrV corrèlent à la structure modélisée de PcrV et la protéine PcrG est globalement peu structurée. L'interaction PcrV-PcrG a été caractérisée, elle met en jeu les domaines « coiled-coil » de chacune des deux protéines. La formation du complexe induit un changement de la conformation de PcrV qui pourrait avoir pour conséquence la stabilisation de PcrG.

Lead (Pb) is a known toxicant that affects young children. It is believed that old water reticulation systems are prone to lead leaching from the walls of lead pipes and fixtures where water is conveyed to households. Many households in Christchurch city particularly in the Northwestern and Central parts of the city contain old water reticulation systems thereby, putting children at considerable health risks. The purpose of this dissertation is to identify the hazards of lead exposure that comes from old water reticulation system of Northwest (NW) Christchurch water supply to households, characterize the health risks due to such contamination and, finally, to suggest possible ways to minimize the hazards. This is accomplished by conducting a systematic review of literature on the exposure patterns of lead from reticulation systems and a literature review of the possible dose response patterns of health effects of lead contamination from old water reticulation systems on children. Thus, this dissertation involves a literature based risk assessment of lead contamination of drinking water supply in the Northwest Christchurch Zone and particularly, its effects on young children. The selection process of the research studies is based on whether they offer accurate and suitable information on the risk of adverse mental function in infants and young children due to environmental lead exposure; whether the studies have been peer reviewed by qualified scientists; whether the results are confirmed by other studies; and involves only human subjects. Future research may consider whether lead levels in drinking water are seasonal; whether these values are significant to health or, the possible role of the government in tightening product controls when monitoring the availability and health risk of high lead drinking water supply plumbing products available in the New Zealand market.

Some of the largest and deepest mines in the world are situated in South Africa. Underground temperatures and humidity can be controlled by means of complex chilled water reticulation system. A cascade pumping system is used to pump the used water from the underground levels back to the surface. The dewatering process is energy intensive. Large volumes of water are used during the general mine drilling periods (06:00 to 12:00). During blasting periods (15:00 to 18:00) a minimum amount of personnel are underground, yet large volumes of water are still sent underground due to a lack of control. Reducing the water sent underground, will reduce the amount of water pumped back to the surface; resulting in significant energy savings. Water flow and pressure can be managed by installing control valves at appropriate positions throughout the water reticulation system. Selecting a control valve is typically governed by constraints such as cavitation, water hammer, flashing, safety ratings and control range. A basic set of calculations can be used to determine whether a valve conforms to a specific scenario. However, scenarios calculated by engineers are not indicative of all applied system scenarios. When control valves are installed, to optimise the operation of a system, it affects the system’s characteristics. Sampled system data will therefore no longer provide adequate readings to help with selecting the correct control valve. An analytical control valve selection method has been developed and implemented. The case study shows the results and practical implications of applying this method in the mining industry. Implementing the analytical valve selection method is shown to be viable, realising electrical energy cost savings for the mine by reducing power requirements from Eskom. Analytical control valve selection for mine water reticulation systems / Thesis (MIng (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2013.

Some of the largest and deepest mines in the world are situated in South Africa. Underground temperatures and humidity can be controlled by means of complex chilled water reticulation system. A cascade pumping system is used to pump the used water from the underground levels back to the surface. The dewatering process is energy intensive. Large volumes of water are used during the general mine drilling periods (06:00 to 12:00). During blasting periods (15:00 to 18:00) a minimum amount of personnel are underground, yet large volumes of water are still sent underground due to a lack of control. Reducing the water sent underground, will reduce the amount of water pumped back to the surface; resulting in significant energy savings. Water flow and pressure can be managed by installing control valves at appropriate positions throughout the water reticulation system. Selecting a control valve is typically governed by constraints such as cavitation, water hammer, flashing, safety ratings and control range. A basic set of calculations can be used to determine whether a valve conforms to a specific scenario. However, scenarios calculated by engineers are not indicative of all applied system scenarios. When control valves are installed, to optimise the operation of a system, it affects the system’s characteristics. Sampled system data will therefore no longer provide adequate readings to help with selecting the correct control valve. An analytical control valve selection method has been developed and implemented. The case study shows the results and practical implications of applying this method in the mining industry. Implementing the analytical valve selection method is shown to be viable, realising electrical energy cost savings for the mine by reducing power requirements from Eskom. Analytical control valve selection for mine water reticulation systems / Thesis (MIng (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2013.