This thesis focuses on transport properties and durability of liquid crystalline polymers (LCP)and fibre reinforced plastics (FRP) with regard to application in industrial process equipment.In the first part of the study the possibility of using a thermotropic LCP of type Vectra A950as lining material for FRP process equipment was investigated. Its performance wascompared to that of a fluorinated ethylene propylene copolymer (FEP) with respect tochemical and permeation resistance. Transport property and chemical resistance data wereestablished for different types of LCP film (compression molded, uniaxially and biaxiallyoriented film) exposed to selected chemicals chosen to represent typical industrial processenvironments. Annealing of the LCP, which may reduce the disclination density and henceimprove the barrier properties, induced a crystallinity increase, but did not significantlyimprove the barrier and chemical resistance properties. Different surface treatments toincrease the bonding between the LCP and FRP were explored. The conclusion was that LCPhas potential to serve as lining material for FRP in contact with water, organic solvents andnon-oxidizing acid environments, although certain issues, such as jointing techniques, stillhave to be evaluated. The second part of the study focused on transport and long-termproperties of commercial thermoset and FRP materials for industrial process equipment inaqueous environments (50 – 95 °C, water activity 0.78 – 1, exposure time ≤ 1000 days). Thewater transport properties in different thermosets were related to their chemical structureusing the solubility parameter concept. The transport of water in the thermosets with differentchemical structures could be predicted from the water activity, regardless of the actual type ofionic or non-ionic solute in the solution. An empirical relationship, independent of boththermoset chemistry and temperature, was established to describe the water concentration inthe thermoset as a function of water activity and the water concentration in pure water. Inlong-term, the water concentration in the thermosets increased with exposure time. Thisseemed to be primarily related to stress relaxation processes induced by water absorption andcertain leaching effects. The effects of hydrolysis seemed to be small. The glass fibrereinforcement may to various extents affect the water transport properties by capillarydiffusion and additional absorption around fibre bundles. The extent of such processesseemed to depend on temperature, water activity and the type of thermoset and reinforcement.The present work may be a useful contribution to an increased understanding of water effectsand durability of FRP process equipment. However, open questions still remain for a morecomprehensive durability analysis. / QC20100629

<p>The first part of this thesis is concerned with thestructure-property relationships in nonionic surfactantsystems. The main aim was to investigate how the surfactantstructure influences the adsorption at interfaces andinteractions between surfactant coated interfaces.Particularly, the effect of the structure of the surfactantheadgroups was investigated. These were sugar-based headgroupwith varying size and flexibility and poly(ethylene oxide)based headgroups with or without an additional amide or estergroup. The hydrophobic part of the surfactant consisted mostlyof straight alkyl chains, except for one type of poly(ethyleneoxide) based surfactant with a dehydroabietic hydrophobe.</p><p>The main technique that was used is the surface forcetechnique, with which the forces acting between two adsorbedsurfactant layers on hydrophilic or hydrophobic surfaces can bemeasured. These forces are important for e.g. the stability ofdispersions. The hydrophilic surfaces employed were glass andmica, whereas the hydrophobic surfaces were silanized glass andhydrophobized mica. The adsorption behavior on hydrophilicsurfaces is highly dependent on the type of headgroup andsurface, whereas similar results were obtained on the two typesof hydrophobic surfaces. To better understand how the surfaceforces are affected by the surfactant structure, measurementsof adsorbed amount and theoretical mean-field latticecalculations were carried out. The results show that the sugarsurfactant layers and poly(ethylene oxide) surfactant layersgive rise to very different surface forces, but that the forcesare more similar within each group. The structure-propertyrelationships for many other physical properties have beenstudied as well. These include equilibrium and dynamicadsorption at the liquid-vapor interface, micelle size, micelledynamics, and wetting.</p><p>The second part in this thesis is about the aggregationbetween cationic polyelectrolytes and an anionic surfactant.The surface force technique was used to study the adsorption ofa low charged cationic polyelectrolyte on mica, and theaggregation between the adsorbed polyelectrolyte with theanionic surfactant. The aggregation in bulk was studied withturbidimetry, small angle neutron scattering (SANS), and smallangle x-ray scattering (SAXS). An internal hexagonal aggregatestructure was found for some of the bulk aggregates.</p><p><b>Keywords:</b>nonionic surfactant, sugar surfactant,poly(ethylene oxide), amide, ester, polyelectrolyte, SDS,hydrophobic surface, glass surface, mica, adsorption,aggregation, micelle size, surface forces, wetting, dynamicsurface tension, NMR, TRFQ, SANS, SAXS, mean-field latticecalculations.</p>

No description available.

Although α-keto carbocations have been demonstrated to be viable intermediates in solvolysis reactions, their applications in synthesis are scarce. These species can be considered to be equivalent to “reversed polarity” enolates and, as such, could be useful for the asymmetric formation of carbon-carbon and carbon-heteroatom bonds. In principle, facial selectivity in additions to α-keto carbocations may be induced using easily removed ester, amide, or imide chiral auxiliaries. Efforts to achieve such diastereoselective SN1 reactions of α-keto carbocations are described herein.

Although α-keto carbocations have been demonstrated to be viable intermediates in solvolysis reactions, their applications in synthesis are scarce. These species can be considered to be equivalent to “reversed polarity” enolates and, as such, could be useful for the asymmetric formation of carbon-carbon and carbon-heteroatom bonds. In principle, facial selectivity in additions to α-keto carbocations may be induced using easily removed ester, amide, or imide chiral auxiliaries. Efforts to achieve such diastereoselective SN1 reactions of α-keto carbocations are described herein.

Membrane transport processes underlie many purification technologies. The efficiency of a membrane separation process depends upon material throughput (flux), and the degree to which the membrane discriminates amongst species in the feed stock (selectivity). In a supported liquid membrane, flux may be enhanced by carrier molecules, which act as catalysts of translocation. Carrier molecules also confer selectivity, via differential molecular recognition of the substances in the feed stock. The effect of electrical potential on the flux and selectivity of carrier-containing supported liquid membranes is not well documented. We elected to study the effect of electrical potential on supported liquid membranes containing valinomycin, a potassium ionophore, and a calixarene ester, a sodium ionophore. In these systems, the open circuit membrane potential could be made positive or negative by the choice of anion. With both of these carriers, we observed that selectivity for potassium or sodium salts was dependent on the open circuit membrane potential. To confirm that electrical potential was responsible for the observed selectivity variance, we applied a potential across the membrane using a potentiostat. The applied potential created conditions for carrier-mediated electrodialysis, where oxidation and reduction reactions on either side of the membrane act as the driving force for transmembrane flux of charged species. In chronoamperometry experiments, we found that selectivity for potassium or sodium ion was dependent on the applied electrical potential. Subject to some constraints, selectivity and flux could be controlled by the application of positive or negative electrical potentials. Linear sweep voltammetry experiments allowed for the rapid prediction of the potential that must be applied to achieve optimal selectivity. We also found that membrane potential measurements, as well as the magnitude of current that flows in chronoamperometry experiments, could be interpreted to predict Eisenman and Hofmeister sequences. These results are novel, and await a convincing theoretical justification. The results also suggest that a separation technology could be developed around the idea of modulating selectivity with electrical potential. In this regard, carrier-mediated electrodialysis may be suitable for the sequestration of toxic or radioactive heavy metals, and a large number of carrier molecules for metal ions are currently known. The technique may also be suitable for separating organic molecules, such as high-value chiral pharmaceuticals. Supported liquid membranes are a useful research tool, but industrial applications may require a more stable membrane architecture. / Graduate

The FT-Raman techniques were developed to quantify reactions that follow on mixing aqueous solutions of bis-(1,3-diaminopropane)diaquacobalt( III) ion ([Co(tn)2(0H)(H20)]2+) and p-nitrophenylphosphate (PNPP). For the development and validation of the kinetic modelling technique, the well-studied inversion of sucrose was utilized. Rate constants and concentrations could be estimated using calibration solutions and modelling methods. It was found that the results obtained are comparable to literature values. Hence this technique could be further used for the [Co(tn)2(0H)(H20)]2+ assisted hydrolysis of PNPP. It was found that rate constants where the pH is maintained at 7.30 give results which differ from those where the pH is started at 7.30 and allowed to change during the reaction. The average rate constant for 2:1 ([Co(tn)2(0H)(H20)]2+:PNPP reactions was found to be approximately 3 x 104 times the unassisted PNPP hydrolysis rate. / Chemistry / M. Sc. (Chemistry)

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Phenolic compouds and their derivatives constitute a leading family of natural compounds. Caffeic acid (CA) and caffeic acid phenethyl ester (CAPE) are the important members of phenolic compound, sharing several biological applications; antioxidant, neuroprotective, anti-inflammatory, antiproliferative, antibacterial, antiviral, antiatherosclerotic and anticancer properties. In spite of these, literature reportes some of its pro-oxidants activity depending on cellular environment. These pathophysiolocal properties increased the interest to evaluate the effect of CA and CAPE on the enzyme evolved in the purines salvage and the acetylcholine hydrolyzing enzyme the acetylcholineterase (AChE); in both PNS and CNS, since the essential constituent of our dietary items. Previously, our research group has reported that phenolic compound altered the activities of these enzymes. The AChE rapidly hydrolyzes the acetylcholine in neuronal and non neuronal tissues, mediating several neurodegenerative diseases. Beside the ACh, ATP (as co-neurotramittors) and adenosine are important signaling molecules, communicating cells in both PNS and CNS. In the extracellular signalling pathways; the adenine nucleotides, their derivative and the coupling of these molecules with specific receptor have a crucial role in nervous, vascular and immune systems. Once released, these molecules are hydrolyzed by a cascade of enzymes including ectonucleoside triphosphate diphosphohydrolase (NTPDase; E.C. 3.6.1.5, CD39), 5 -nucleotidase (E.C 3.1.3.5, CD73), ectonucleotide pyrophosphatase/phosphodiesterase (E-NPP), modulating crucially the signaling pathways in the normal functioning of nervous, vascular and immune systems. Next, adenosine deaminase (ADA) and xanthin oxidase (XO) degrade the adenosine and xanthine respectively which further control the functioning mechanisms in cellular events. Found in the neuronal and non neuronal (in both PNS and CNS) the AChE, NTPDase, 5'-nucleotidase, E-NPP, and ADA regulate several events including neurotransmission, inflammation, and thrombogenic process. We hypothesized to evaluate first the in vitro effects of CA on AChE activity in peripheral and central cholinergic system of rats. The results showed that CA significantly modulated the cholinergic system in vitro. By modulating the cholinergic system in vitro, apparently CA (e.g. phenolic structure) has proper role in neurotransmission. Therefore we hypothesizes to evaluate the in vivo effects of CA on AChE, NTPDase, E-NPP, 5'-nucleotidase, platelets aggregation and (ADA) in different tissues/cell from rats. The animals were treated during 30 days and killed after behavioral test. The results showed that caffeic acid increased significantly the AChE activity in hippocampus, hyphothalmus, pon and lymphocytes while that in cortex, cerebellum and striatum the AChE was inhibited. CA improves step-down latencies in the inhibitory avoidance. Investigating the in vivo effects of CA in purinergic system, caffecid acid increased the ATP and AMP hydrolysis in synaptosomes. However, in the synaptosomes no alterations were observed in the ADA activity in the groups evaluated in this study. CA increased the ATP and AMP hydrolysis, while the ADP hydrolysis was decreased in platelets. In the present findings caffeic acid decreased the platelets aggregation induced by ADP agonist. Treatment with CA also increased the NTPDase and ADA activities in lymphocytes of rats. Considering the dual function of caffeic acid in vitro and in vivo, the present study was extended to CAPE followed by acute treatment model (ip) in order to elucidate the effect of another phenolic structure on the same parameters. In this line the animals were treated (ip) with CAPE and killed after 40 minutes. In platelets, the results showed that the effect of CAPE increased the NTPDase, E-NPP, 5 -nucleotidase activities, while ADA activities did not change significantly. In synaptosomes CAPE significantly inhibited the NTPDase, and 5 -nucleotidase activity. CAPE induced no significant changes in ADA in synaptosomes but reduced XO in whole brain. Finaly we investigated the activity of AChE in cortex, cerebellum, striatum, hippocampus, hyphotalamus, pon, lymphocytes and muscules of rats treated with CAPE. The results showed that CAPE significantly decreased the AChE activity in cortex cerebellum and striatum. CAPE significantly increased the AChE activity in hippocampus hypothalamus, pons, muscle and lymphocytes. In cholinergic system our results clearly demonstrating that both compound with dual functions.These findings demonstrated that the AChE activities and the cascade of ecto-enzymes was alter in different tissues after treatment with CA and CAPE in rats, suggesting that these compound should be considered a potentially therapeutic agent in immune, vascular and neurological disorders related with the cholinergic purinergic system. / Os compostos fenólicos e seus derivados constituem uma importante família de compostos naturais. O ácido cafeico (AC) e o éster fenetil do ácido cafeico (CAPE) são membros importantes dessa família e compartilham algumas aplicações biológicas, tais como: antioxidante, neuroprotetor, antiinflamatório, antiproliferativo, antibacteriano, antiviral, antiaterosclerótico e anticancerígeno. Entretanto, a literatura relata algumas atividades pró-oxidantes, dependendo do ambiente celular. Devido a estas propriedades patofisiológicas, aumentou o interesse com o objetivo de avaliar o efeito de CA e CAPE sob as atividades das enzimas purinérgicas e da acetilcolinesterase (AChE), tanto no Sistema Nervoso Periférico (SNP) como no Sistema Nervoso Central (SNC). Previamente, nosso grupo de pesquisa relatou que o composto fenólico tem a capacidade de alterar as atividades dessas enzimas. A AChE rapidamente hidrolisa a acetilcolina (ACh) em tecidos neuronais e não neuronais, mediando algumas doenças neurodegenerativas. Ao lado da ACh, o ATP (como coneurotransmissor) e adenosina são importantes moléculas sinalizadoras, comunicando as células em ambos os SNP e do SNC. Nas vias de sinalização extracelulares, os nucleotídeos de adenina e seus derivados podem ser acoplados a receptores específicos e desse modo ter um papel crucial no sistema nervoso, sistema vascular e imune. Uma vez liberadas, estas moléculas são hidrolisadas por uma cascata de enzimas incluindo a ectonucleosídeo trifosfato difosfoidrolase (NTPDase; EC 3.6.1.5, CD39), 5'- nucleotidase (EC 3.1.3.5, CD73), ectonucleotideo pirofosfatase/fosfodiesterase (E-NPP), modulando definitivamente as vias de sinalização do funcionamento normal do sistema nervoso, sistema vascular e imune. Além disso, a adenosina deaminase (ADA) e a xantina oxidase (XO) degradam a adenosina e a xantina, respectivamente, as quais controlam o funcionamento de mecanismos em eventos celulares. As enzimas encontradas em tecidos neuronais e não neuronais como a AChE, a NTPDase, a 5'-nucleotidase, a E-NPP e a ADA regulam eventos celulares incluindo a neurotransmissão, inflamação e processos trombogênicos. Com essas informações, nós introduzimos a hipótese de avaliar primeiramente os efeitos in vitro de CA na atividade da AChE periférica e no sistema central colinérgico de ratos. Os resultados demonstraram que o CA modula significativamente o sistema colinérgico no estudo in vitro. Essa modulação demonstra aparentemente que o CA (estrutura fenólica) possui propriedades de ação que altera a neurotransmissão. Portanto, a hipótese de se avaliar os efeitos in vivo de CA na atividade da AChE, NTPDase, E-NPP, 5'-nucleotidase, ADA e da agregação de plaquetas em diferentes tecidos de ratos tornou-se evidente. Para esse estudo, os animais foram tratados durante 30 dias e sacrificados após o teste comportamental. Os resultados do experimento demonstraram que o CA aumentou significativamente a atividade da AChE em hipocampo, hipotálamo, ponte e nos linfócitos, enquanto que no córtex cerebral, cerebelo e estriado a AChE foi inibida. No teste comportamental o CA teve evolução de melhora na latência de passos da esquiva inibitória. A investigação dos efeitos in vivo do CA no sistema purinérgico demonstrou aumento na hidrólise de ATP e AMP em sinaptossomas. Entretanto, não foram observadas alterações significativas na atividade da ADA em sinaptossomas dos grupos avaliados neste estudo. Em plaquetas, o CA aumentou significativamente a hidrólise de ATP e AMP, enquanto que a hidrólise de ADP foi diminuída nesse tecido. No presente estudo o CA reduziu significativamente a agregação de plaquetas induzida pelo agonista ADP. Além disso, o tratamento com CA aumentou significativamente as atividades da NTPDase e da ADA em linfócitos de ratos. Considerando a dupla função de CA, in vitro e in vivo, o presente estudo foi estendido para CAPE seguindo o modelo de tratamento agudo pela via intraperitoneal (ip) com o objetivo de elucidar o efeito de uma segunda estrutura fenólica sobre os mesmos parâmetros. Nesta linha de pesquisa, os animais foram tratados ip com CAPE e eutanasiados após 40 minutos. Em plaquetas, os resultados demonstraram que o CAPE aumentou significativamente a atividade da NTPDase, E-NPP e 5'-nucleotidase, enquanto que a atividade da ADA não foi alterada significativamente. Em sinaptossomas, o CAPE inibiu significativamente a atividade da NTPDase e da 5'-nucleotidase. O CAPE não induziu alterações significativas na atividade da ADA em sinaptossomas, mas reduziu significativamente a atividade da XO em todo o cérebro. Finalmente, nós investigamos a atividade da AChE no córtex cerebral, cerebelo, estriado, hipocampo, hipotálamo, ponte, linfócitos e músculos de ratos tratados com CAPE. Os resultados demonstraram que CAPE diminuiu significativamente a atividade da AChE em córtex cerebral, cerebelo e estriado. O CAPE aumentou significativamente a atividade da AChE em hipotálamo, hipocampo, ponte, músculo e linfócitos. No sistema colinérgico, nossos resultados demonstram claramente que ambos os compostos possuem dupla função. Estes resultados demonstram que as atividades da AChE e da cascata das ecto-enzimas foram alteradas em diferentes tecidos após o tratamento com CA ou CAPE em ratos, sugerindo que estes compostos devem ser considerados agentes com potencial terapêutico em doenças imunes, vasculares e neurológicas relacionadas com o sistema colinérgico e purinérgico.

Vegetable oil methyl esters obtained by transesterification of vegetable oils are considered to be suitable alternative fuels for diesel engines. However, higher viscosity, surface tension and boiling temperatures of biodiesels may adversely affect spray characteristics as compared to those of diesel. Thus, spray characteristics of Jatropha Methyl Ester (JME) are studied by comparing them to those of diesel in a high-pressure chamber with optical access to simulate the actual in-cylinder conditions. Also, the effect of inner-nozzle cavitation on JME and diesel sprays is studied by utilizing two nozzles, one with sharp entry-radius and the other with larger entry-radius. Finally, spray characteristics of surrogate fuels such as n-dodecane and n-hexadecane are also studied. The first part of the work concerning precise measurements of inner-nozzle geometry revealed that one of the nozzles has a hole diameter of 190-µm and entry-radius of around 70-µm, while the other has a hole diameter of 208-µm and entry-radius of around 10-µm. Injection rate-shape and coefficient of discharge for JME and diesel flow through the two nozzles were then measured. It was observed that while the coefficients of discharge (Cd) are almost identical for JME and diesel, the nozzle with entry radius of 10-µm exhibited around 20% lower Cd than that of the entry-radius of 70-µm. This observation coupled with insight from complementary CFD simulations of inner-nozzle flow showed that the lower Cd of the nozzle with entry-radius of 10-µm could be attributed to inner-nozzle cavitation. The second part of the work involved measurement of non-evaporating spray characteristics including spray-tip penetration, spray-cone angle and droplet size measurement under realistic operating conditions using techniques such as Shadowgraphy and Particle/Droplet Imaging Analysis (PDIA). The non-evaporating spray of the fuels are studied by injecting them using a common-rail fuel injection system into the high-pressure chamber maintained at room temperature. Experimental results show that JME is associated with a slightly faster spray-tip penetration and narrow spray-cone angle indicating inferior spray atomization which is confirmed by around 5% larger droplet sizes. Slower spray-tip penetration, wider spray-cone angle and around 5% smaller droplet sizes are observed for the spray from the cavitating nozzle. Thus, the inner nozzle cavitation is observed to improve the atomization of diesel and JME sprays. The differences in spray characteristics of JME and diesel reduce as the injection pressure increases. The spray-tip penetrations of both surrogates are observed to almost match that of diesel. The third part of the work involved measurements of evaporating spray liquid length, vapour penetration and spread angle for JME, diesel and surrogates at conditions of 50 bar chamber pressure and 900 K temperature. It is observed that the JME exhibits around 16% longer liquid length than that of diesel. The liquid length of n-dodecane is significantly lower than that of diesel and liquid length of n-hexadecane is around 20% higher than that of n-dodecane mimicking the trend of JME and diesel. The liquid length of n-hexadecane is very close to that of diesel at all the three test conditions. Interestingly, the vapour penetration and spread angle for all the fuels is observed to be almost identical. As the cold spray and evaporating spray characteristics of n-hexadecane match well with those of diesel, n-hexadecane can be chosen as a pure component surrogate for diesel. Finally, an analytical model for predicting the spray vapour penetration is assessed with the experimentally-observed trends of penetration and spray spread angle. The model indicated that the effect of fuel density variation is compensated by the corresponding variation in injection velocity for a given injection pressure to result in a similar vapour penetration. Overall, the present work, in addition to studying the effect of fuel physical properties and cavitation on sprays, has generated a comprehensive experimental database on non-evaporating and evaporating sprays of biodiesel, diesel, and pure component surrogates, which would aid significantly in validation of CFD simulations.

Regeneration, a spontaneous response of bones in response to injuries, infections and fractures, is severely compromised in certain clinical circumstances. Unfortunately, several shortcomings are associated with the current treatment of bone grafting method such as donor shortage and immune response for allografts and donor morbidity for autografts. Thus, the development of clinical alternates is essential. One promising adjunct method is bone tissue engineering that includes the implantation of a scaffold containing the cells with the supplementation of suitable growth factors. Among the various classes of materials, biodegradable polymers are commonly preferred because their use does not necessitate a secondary surgery for their removal after the intended use. Commercially available polymers such as poly (lactic- co- glycolic acid) and polycaprolactone are expensive and degrade slowly. This motivates the development of novel synthetic biodegradable polymers that are affordable and can be tuned to tailor for specific biomedical applications. The primary aim of this thesis is to synthesize effective biodegradable polymers for drug delivery and bone tissue engineering. The properties of these polymers such as modulus, hydrophobicity and crosslinking etc. were tailored based on the variations in chemical bonds, chain lengths and the molar stoichiometric ratios of the monomers for specific clinical applications. Based on the above variations, degradation and release kinetics were tuned. The cytocompatibilty properties for these polymers were studied and suitable mineralization studies were conducted to determine their potential for bone regeneration.