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Increasing environmental awareness over the past decade as well as stringent environmental laws forced all factories to invest in water treatment processes for effluent treatment before discharge or re-use. Most of these effluent treatment processes utilize membranes as the physical. barrier for separation. The membranes used in water applications are expensive and alternative materials and production techniques will increase the viability of membrane separation processes. Experiments conducted on irradiated polyethylene showed that some of its properties were enhanced while others deteriorated. However, the enhanced properties make the polyethylene, in particular ultra-high molecular weight polyethylene, an ideal membrane material. The manufactured membranes were tested in extraction experiments, and satisfactory results were obtained. Permeation studies on the membranes compared favourably with similar studies done on commercially available membranes. An extraction rate of 1.08 g/(m2h) nickel was achieved. A preliminary cost evaluation showed that these membranes can be manufactured at a low cost (R13.45/m2). and can be applied as supported liquid membranes. Future research should focus on methods to decrease the brittleness and stiffness of the membranes. / Thesis (MIng)--PU for CHE, 1999

Increasing environmental awareness over the past decade as well as stringent environmental laws forced all factories to invest in water treatment processes for effluent treatment before discharge or re-use. Most of these effluent treatment processes utilize membranes as the physical. barrier for separation. The membranes used in water applications are expensive and alternative materials and production techniques will increase the viability of membrane separation processes. Experiments conducted on irradiated polyethylene showed that some of its properties were enhanced while others deteriorated. However, the enhanced properties make the polyethylene, in particular ultra-high molecular weight polyethylene, an ideal membrane material. The manufactured membranes were tested in extraction experiments, and satisfactory results were obtained. Permeation studies on the membranes compared favourably with similar studies done on commercially available membranes. An extraction rate of 1.08 g/(m2h) nickel was achieved. A preliminary cost evaluation showed that these membranes can be manufactured at a low cost (R13.45/m2). and can be applied as supported liquid membranes. Future research should focus on methods to decrease the brittleness and stiffness of the membranes. / Thesis (MIng)--PU for CHE, 1999

The G protein-coupled receptor (GPCR) family is composed of hundreds of members and is expressed in eukaryotes. Each GPCR has seven transmembrane domains and is in charge of sensing changes from the environment, transducing signals, and activating a series of biological responses. The signal transduction pathway of the receptor starts from sensing outside signal and then activates G proteins. This signaling requires a tight control for activation without which impaired cellular function leads to pathology. We have used the pheromone alpha-factor receptor (Ste2p) of the yeast Saccharomyces cerevisiae as a model system to understand ligand binding, receptor activation, and G protein interaction. One method we have used to study ligand binding is to incorporate the photo-reactive crosslinker p-benzoyl-L-phenylalanine (Bpa) into Ste2p to capture alpha-factor. This powerful tool requires the incorporation of Bpa, an unnatural amino acid, into Ste2p by a special genetic manipulation designed in the lab of Peter Schulz (Scripps Institute) and adapted by our lab for Ste2p. Another method to study ligand binding that we have adapted for use in our system is to incorporate a chemical crosslinker [3,4-dihydroxylphenylacetyl (DHPA)] into alpha-factor for periodate-mediated crosslinking to Ste2p. The interacting domain between alpha-factor and transmembrane domain 2 to 3 of Ste2p was identified after DOPAC crosslinking, cyanogen bromide digestion and MALDI-TOF mass spectrometry. After ligand binding, signal transduction is mediated by the interaction of activated Ste2p with its G protein (Gpa1p). We studied this interaction by replacing natural residues in the intracellular loop 3 of Ste2p and C-terminal end of Gpa1p with cysteine and then determining disulfide crosslinking between Ste2p and Gpa1p. Some residues were found to be in close proximity and displayed different interacting patterns due to conformational changes of the receptor upon ligand binding. The information we gathered here allows us to understand more about the physical interactions of alpha-factor, Ste2p, and Gpa1p and provides us insights about the initiation and activation of the signal transduction pathway of a peptide ligand receptor.

Thesis (M.S.)--Rutgers University, 2007. / "Graduate Program in Biomedical Engineering." Includes bibliographical references (p. 80-85).

Compostos elastoméricos a base de borracha natural (NR) e copolímero de butadieno-estireno (SBR) utilizados na banda de rodagem de pneus são tradicionalmente reticulados com enxofre. O uso de peróxidos e co-agentes na reticulação desses compostos ainda é um desafio a se superar com relação às propriedades viscoelásticas requeridas, de extrema importância para um bom desempenho e vida útil dos pneus. Neste trabalho foi avaliado o uso de peróxidos sem e com co-agentes na reticulação de compostos NR/SBR com o intuito de avaliar a eficiência destes na manutenção das propriedades relevantes em relação a um composto tradicionalmente usado na confecção de banda de rodagem de pneus. Onze formulações com diferentes sistemas de reticulação foram preparadas, sendo uma de referência. Foram avaliadas propriedades físicas como dureza, densidade, tração, resistência ao rasgamento, resiliência, abrasão e DPC, e o comportamento dos compostos de NR/SBR com relação ao inchamento em tolueno. As propriedades dinâmicomecânicas dos compostos NR/SBR foram analisadas por DMA e RPA. Os compostos NR/SBR contendo somente peróxidos não apresentaram propriedades comparáveis ao composto de referência vulcanizado com enxofre. Os compostos contendo os sistemas peróxidos/co-agentes, BIS F 40 A-Retilink T40 (composto 10) e BIS F 40 A-Retilink TA 70 (composto 11) apresentaram os melhores resultados. O composto 10 e o composto de referência (composto 1) apresentaram valores similares de tan d a 60°C e tan d a 0°C (DMA), os quais estão correlacionados às propriedades de resistência ao rolamento e tração no molhado, respectivamente. Os resultados mostraram a possibilidade de uso de certos sistemas peróxido/co-agente em compostos de NR/SBR, em substituição ao sistema com enxofre, sem perda de propriedades, tendo como vantagem a redução de componentes na formulação, redução de tempo de processamento, e consequentemente custo da produção de bandas de rodagem. / Rubber compounds based on natural rubber (NR) and styrene-butadiene rubber (SBR) used on tire tread are traditionally crosslinked with sulfur. The use of peroxides and co-agents in crosslinking of these compounds is still a challenge to be achieved, considering the required viscoelastic properties which are extremely important for a good tire performance and lifetime. In this work it was evaluated the use of peroxide systems with and without co-agents as crosslinking agents for NR/SBR compounds, with the aim of evaluating the efficiency of maintaining the key properties related to the traditionally used in the manufactory of tire tread. Eleven formulations with different systems were prepared, a one as a reference. Physical properties such as hardness, density, tensile strength, tear, resilience, abrasion and compression set and the behavior of NR/SBR compounds in relation of swelling Toluene were evaluated. The dynamic mechanical properties of the NR/SBR cured compounds were analysed by DMA and RPA. The NR/SBR compounds cured with only peroxide had poorer properties when compared to the reference compound vulcanized with sulfur. On the other hand, the compounds cured with proxide/co-agents, BIS F40 plus Retilink T40 (compound 10) or plus T70A (compound 11) showed better results.The compound 10 and the reference compound (compound 1) showed similar results of tan d 60 °C and tan d 0 °C (DMA), which are correlated to rolling resistance and wet traction, respectively. The results demonstrate the possibility of using a peroxide/co-agent as a cure system in NR/SBR compound instead of a sulfur-cured compound for tire tread applications, without the loss of desirable properties, lower processing times and consequently reducing manufacturing costs.

Master of Science / Department of Chemical Engineering / John R. Schlup / The cross-linking reaction of the polyimide Matrimid 5218 with ethylenediamine (EDA) in methanol was investigated using Fourier transform infrared (FTIR) spectroscopy. Peaks associated with breaking imide bonds and the formation of amide bonds were identified. Using an internal standard peak of 1014 cm⁻¹ allowed for quantitative analysis to be applied. The peak areas, calculated by slice area, were used for absorbance ratio analysis to follow the cross-linking reaction as a function of time. Lastly, the absorbance values for the decreasing peak 1718 cm⁻¹ were used to calculate the order of reaction for the reaction rate of the mechanism.

Ce projet vise à fabriquer une nouvelle génération de membranes polymères hydrophiles à base d’un polymère biosourcé, l’Hydroxypropyl Cellulose (HPC), pour une application dans le traitement des eaux de production. Ces membranes polymères viendront se substituer sur les plateformes offshores aux procédés classiques de traitement en raison de leur compacité, de leur légèreté et de leur aptitude à éliminer efficacement à la fois l’huile et les particules en suspension. Les membranes ont été élaborées via une méthode d’inversion de phase originale par augmentation de la température au-dessus de la température critique (LCST-TIPS process). Deux voies d’élaboration ont été étudiées au cours de la thèse selon le mode de réticulation chimique envisagé, l’une en voie acide et l’autre en voie basique. En voie acide, la réticulation a été effectuée à l’aide du Glutaraldéhyde alors qu’en voie basique, elle a été réalisée via un PEGDE. Le processus d’élaboration a été contrôlé pour maîtriser les cinétiques des phénomènes élémentaires (séparation de phase, évaporation, réticulation chimique). Les membranes ont été caractérisées via un suivi rhéologique, l’analyse de la morphologie membranaire (MEB) et les performances en filtration ont été étudiées in fine. La fabrication des membranes sous forme de fibres creuses a également été initiée aux cours de la thèse. / This project aims to develop a new generation of hydrophilic polymer membranes based on a biosourced polymer, Hydroxypropyl Cellulose (HPC), for application in the treatment of produced water. These polymeric membranes should replace on offshore platforms the conventional treatment processes because of their compactness, their lightness and their ability to effectively remove both oil and suspended particles. The membranes were developed using an original phase inversion method by increasing the temperature above the critical temperature (LCST-TIPS process). Two ways of membrane formation were investigated in this work according to the mode of chemical crosslinking considered, one in acid medium and the other in basic medium. Considering the acid route, the crosslinking was carried out using glutaraldehyde, while for the basic route it was carried out via PEGDE molecule. A fine control of the membrane formation process was conducted in order to control the kinetics of the whole elementary phenomena involved in the membrane morphogenesis (phase separation, solvent evaporation, and chemical crosslinking). The membranes were characterized via rheological monitoring, the analysis of the membrane morphology (SEM) and the filtration performances were investigated. The issue of hollow fibers fabrication has been also addressed during the thesis.

Compostos elastoméricos a base de borracha natural (NR) e copolímero de butadieno-estireno (SBR) utilizados na banda de rodagem de pneus são tradicionalmente reticulados com enxofre. O uso de peróxidos e co-agentes na reticulação desses compostos ainda é um desafio a se superar com relação às propriedades viscoelásticas requeridas, de extrema importância para um bom desempenho e vida útil dos pneus. Neste trabalho foi avaliado o uso de peróxidos sem e com co-agentes na reticulação de compostos NR/SBR com o intuito de avaliar a eficiência destes na manutenção das propriedades relevantes em relação a um composto tradicionalmente usado na confecção de banda de rodagem de pneus. Onze formulações com diferentes sistemas de reticulação foram preparadas, sendo uma de referência. Foram avaliadas propriedades físicas como dureza, densidade, tração, resistência ao rasgamento, resiliência, abrasão e DPC, e o comportamento dos compostos de NR/SBR com relação ao inchamento em tolueno. As propriedades dinâmicomecânicas dos compostos NR/SBR foram analisadas por DMA e RPA. Os compostos NR/SBR contendo somente peróxidos não apresentaram propriedades comparáveis ao composto de referência vulcanizado com enxofre. Os compostos contendo os sistemas peróxidos/co-agentes, BIS F 40 A-Retilink T40 (composto 10) e BIS F 40 A-Retilink TA 70 (composto 11) apresentaram os melhores resultados. O composto 10 e o composto de referência (composto 1) apresentaram valores similares de tan d a 60°C e tan d a 0°C (DMA), os quais estão correlacionados às propriedades de resistência ao rolamento e tração no molhado, respectivamente. Os resultados mostraram a possibilidade de uso de certos sistemas peróxido/co-agente em compostos de NR/SBR, em substituição ao sistema com enxofre, sem perda de propriedades, tendo como vantagem a redução de componentes na formulação, redução de tempo de processamento, e consequentemente custo da produção de bandas de rodagem. / Rubber compounds based on natural rubber (NR) and styrene-butadiene rubber (SBR) used on tire tread are traditionally crosslinked with sulfur. The use of peroxides and co-agents in crosslinking of these compounds is still a challenge to be achieved, considering the required viscoelastic properties which are extremely important for a good tire performance and lifetime. In this work it was evaluated the use of peroxide systems with and without co-agents as crosslinking agents for NR/SBR compounds, with the aim of evaluating the efficiency of maintaining the key properties related to the traditionally used in the manufactory of tire tread. Eleven formulations with different systems were prepared, a one as a reference. Physical properties such as hardness, density, tensile strength, tear, resilience, abrasion and compression set and the behavior of NR/SBR compounds in relation of swelling Toluene were evaluated. The dynamic mechanical properties of the NR/SBR cured compounds were analysed by DMA and RPA. The NR/SBR compounds cured with only peroxide had poorer properties when compared to the reference compound vulcanized with sulfur. On the other hand, the compounds cured with proxide/co-agents, BIS F40 plus Retilink T40 (compound 10) or plus T70A (compound 11) showed better results.The compound 10 and the reference compound (compound 1) showed similar results of tan d 60 °C and tan d 0 °C (DMA), which are correlated to rolling resistance and wet traction, respectively. The results demonstrate the possibility of using a peroxide/co-agent as a cure system in NR/SBR compound instead of a sulfur-cured compound for tire tread applications, without the loss of desirable properties, lower processing times and consequently reducing manufacturing costs.

Compostos elastoméricos a base de borracha natural (NR) e copolímero de butadieno-estireno (SBR) utilizados na banda de rodagem de pneus são tradicionalmente reticulados com enxofre. O uso de peróxidos e co-agentes na reticulação desses compostos ainda é um desafio a se superar com relação às propriedades viscoelásticas requeridas, de extrema importância para um bom desempenho e vida útil dos pneus. Neste trabalho foi avaliado o uso de peróxidos sem e com co-agentes na reticulação de compostos NR/SBR com o intuito de avaliar a eficiência destes na manutenção das propriedades relevantes em relação a um composto tradicionalmente usado na confecção de banda de rodagem de pneus. Onze formulações com diferentes sistemas de reticulação foram preparadas, sendo uma de referência. Foram avaliadas propriedades físicas como dureza, densidade, tração, resistência ao rasgamento, resiliência, abrasão e DPC, e o comportamento dos compostos de NR/SBR com relação ao inchamento em tolueno. As propriedades dinâmicomecânicas dos compostos NR/SBR foram analisadas por DMA e RPA. Os compostos NR/SBR contendo somente peróxidos não apresentaram propriedades comparáveis ao composto de referência vulcanizado com enxofre. Os compostos contendo os sistemas peróxidos/co-agentes, BIS F 40 A-Retilink T40 (composto 10) e BIS F 40 A-Retilink TA 70 (composto 11) apresentaram os melhores resultados. O composto 10 e o composto de referência (composto 1) apresentaram valores similares de tan d a 60°C e tan d a 0°C (DMA), os quais estão correlacionados às propriedades de resistência ao rolamento e tração no molhado, respectivamente. Os resultados mostraram a possibilidade de uso de certos sistemas peróxido/co-agente em compostos de NR/SBR, em substituição ao sistema com enxofre, sem perda de propriedades, tendo como vantagem a redução de componentes na formulação, redução de tempo de processamento, e consequentemente custo da produção de bandas de rodagem. / Rubber compounds based on natural rubber (NR) and styrene-butadiene rubber (SBR) used on tire tread are traditionally crosslinked with sulfur. The use of peroxides and co-agents in crosslinking of these compounds is still a challenge to be achieved, considering the required viscoelastic properties which are extremely important for a good tire performance and lifetime. In this work it was evaluated the use of peroxide systems with and without co-agents as crosslinking agents for NR/SBR compounds, with the aim of evaluating the efficiency of maintaining the key properties related to the traditionally used in the manufactory of tire tread. Eleven formulations with different systems were prepared, a one as a reference. Physical properties such as hardness, density, tensile strength, tear, resilience, abrasion and compression set and the behavior of NR/SBR compounds in relation of swelling Toluene were evaluated. The dynamic mechanical properties of the NR/SBR cured compounds were analysed by DMA and RPA. The NR/SBR compounds cured with only peroxide had poorer properties when compared to the reference compound vulcanized with sulfur. On the other hand, the compounds cured with proxide/co-agents, BIS F40 plus Retilink T40 (compound 10) or plus T70A (compound 11) showed better results.The compound 10 and the reference compound (compound 1) showed similar results of tan d 60 °C and tan d 0 °C (DMA), which are correlated to rolling resistance and wet traction, respectively. The results demonstrate the possibility of using a peroxide/co-agent as a cure system in NR/SBR compound instead of a sulfur-cured compound for tire tread applications, without the loss of desirable properties, lower processing times and consequently reducing manufacturing costs.