Theoretical models for the electrokinetics of weakly permeable porous colloidal particles are absent from the literature. The understanding of this topic will be advanced through a systematic analysis of the standard electrokinetic equations, resulting in a theory for the electrophoretic mobility of weakly permeable porous colloidal particles. / The standard electrokinetic equations are employed to model the flux of solvent and ions outside the porous particle. To be consistent with this approach, the flux of solvent and ions in the pores must also be governed by the standard electrokinetic equations. However, in practice, only transport phenomena on the particle scale are observed and it is sufficient for information regarding pore-scale behaviour to be retained purely in the form of averaged quantities. To complete the theoretical description, the standard electrokinetic equations outside the particle must be coupled to particle-scale transport equations inside the particle via boundary conditions at the porous/free-fluid interface. / It has been shown experimentally and theoretically for coupled Stokes and Darcy flows, that the correct interfacial boundary condition for the tangential external flow is given by the Beavers-Joseph-Saffman (BJS) condition. The effect of the BJS boundary condition on the hydrodynamic drag on an oscillating porous particle is investigated. It is found that the particle may be regarded as impermeable with a slip length independent of frequency, and the resulting drag is significantly reduced in comparison with an equivalent impermeable particle that does not exhibit a slip length. / The transport of a general electrolyte solution through a rigid porous body subjected to a static (d.c.) electric field is studied. The pore-scale description is given by the standard electrokinetic equations, including the effects of ion diffusion, electromigration and convection. Homogenization theory is used to derive transport equations that capture the particle-scale behaviour. It is proven that the transport coefficient tensors obey Onsager’s reciprocal relations and the diagonal coefficient tensors are positive definite. / New interfacial boundary conditions are derived using conservation arguments supplemented by Stern-layer theory. When combined with the particle-scale transport equations, these boundary conditions incorporate four principal effects into the standard electrokinetic model: solvent slip and Stern-layer ionic conduction at the interface, and macroscopic ionic conduction together with the electroosmotic flow of solvent through the particle. / The method of matched asymptotic expansions is then used to construct an approximate solution to the aforementioned system, in the thin double-layer limit. An expression for the electrophoretic mobility of a weakly permeable colloidal sphere is produced that consists of a generalization of Smoluchowski’s formula to encompass porous particles, and a next order correction. For the first time, the effects of solvent slip and Stern-layer ionic conduction within the porous/free-fluid interface, in conjunction with macroscopic ionic conduction and electroosmosis through the particle, are exhibited. It is shown that solvent slip at the porous interface is overwhelmingly the dominant effect on the mobility of weakly permeable porous colloidal particles.

Thesis (M.S.)--Rochester Institute of Technology, 2006. / Typescript. Includes bibliographical references (leaves 102-103).

Electrophoretic deposition (EPD) has been used to produce the yttria-stabilized zirconia (YSZ) coatings on metal substrates. Sintering of YSZ with and without doping has been carried out at 1150 °C for 2hrs. The properties of these coatings have been examined in light of thermal barrier applications. For EPD, the green density increases with an initial increase in the HCl concentration and the EPD time. This suggests that particle packing was influenced by a time dependent re-arrangement, in addition to the initial suspension dispersion state. The green density peaks at a electrical conductivity of around 10×10-4 S/m achieved by an 0.5 mM HCl addition for the 20 g/l suspensions with the EPD time of around 8 ~10 minute. For sintered coatings, the HCl concentration had a marked effect on the neck size to grain size ratio of the 8 mol% yttria-stabilized zirconia (8YSZ) coatings. The presence of ZrCl4 and ZrOCl2, and a high concentration of oxygen vacancies at the grain boundaries are believed to promote neck growth in the early stage of sintering at 1150 °C. During sintering of 3 mol% and 8 mol% yttria-stabilized zirconia (3YSZ and 8YSZ) at 1150 ºC for 2hrs, the densification rate substantially increased with a small amount of Fe2O3 addition (0.5 mol%) to the 3YSZ/8YSZ deposits. A more pronounced graingrowth was present in the Fe2O3 doped 8YSZ deposits. The increased Zr4+ diffusion coefficient is mainly responsible to the rapid densification rate of the Fe2O3 doped 3YSZ/8YSZ deposits. A small grain growth observed in the Fe2O3 doped 3YSZ deposits is attributed to the Fe3+ segregation at grain boundary. A small amount of CeO2 doping was found to substantially inhibit the densification rate of the doped 3YSZ deposits with a minor grain growth. Fe2O3 doping reduced the thermal conductivities of 3YSZ/8YSZ. It is found that Rayleigh-type phonon scattering due to the mass difference alone is inadequate to explain the thermal conductivity of Fe2O3 doped YSZ systems. The lattice strain effects due to the ionic radius difference could more effectively reduce thermal conductivity of the Fe2O3-doped 3YSZ. A decrease in the growth rate of the TGO scale with the increasing Fe2O3 additions was observed for the oxidized FeCrAlY metal substrates with the Fe2O3-doped 3YSZ coating, which was found to be attributed to the early formation of the stable and dense α-Al2O3 phase due to the presence of Fe3+ ions.

As propriedades protetoras à corrosão dos polímeros condutores, especialmente da poli(anilina) (PANI), têm sido amplamente explorada. Entretanto, o mecanismo pelo qual esta proteção é efetuada ainda não foi completamente elucidado. Evidências mostram que a habilidade protetora à corrosão da PANI está ligada à formação de um par galvânico entre o polímero e o metal. Neste trabalho, foi feito um estudo sobre a formação de um par galvânico entre a PANI e diferentes substratos metálicos (zinco, ferro, níquel e cobre) em meios ácidos e neutros. Medidas de potencial de circuito aberto mostram que há a possibilidade de formação de um acoplamento galvânico e medidas de corrente galvânica mostram que há uma corrente galvânica fluindo entre todos os pares PANI-metal. Durante este trabalho, foi sintetizada uma suspensão à base de epóxi e PANI, a qual foi eletroforeticamente depositada sobre um eletrodo de ferro. Medidas de potencial de circuito aberto e impedância em uma solução aquosa de ácido sulfúrico mostraram que o revestimento à base de PANI protegeu o substrato metálico em questão através da formação de um par galvânico entre o metal e o polímero. / The corrosion protection properties of conducting polymers, especially poly(aniline) (PANI) ones, have been widely exploited. However, the mechanism by which this protection is made has not been completely cleared yet. Evidences show the ability of PANI\'s corrosion protection is connected to the building of a galvanic couple between the polymer and the metal. In this work, a study about the building of a galvanic couple between PANI and distinct metallic substrates (zinc, iron, nickel and copper) in acid and neutral environment was done. Measurements of open circuit potential showed the possibility of the building of a galvanic coupling and measurements of galvanic current showed the flux of a galvanic current between all the couples PANI-metal. In the course of this work, a suspension based on epoxy and PANI was synthesized and electrophoretically depositated on a iron electrode. Measurements of open circuit potential and impedance in a aqueous sulfuric acid solution showed that the revestiment based on PANI protected the metallic substrate by the building of a galvanic couple between the metal and the polymer.

Submitted by Jonatas Erick Maimoni Campanella null (jemcampanella@gmail.com) on 2018-03-23T19:20:54Z No. of bitstreams: 1 Dissertação FINAL.pdf: 3123007 bytes, checksum: 93be4f3b9e7d1e13ef2550b233a4fa94 (MD5) / Approved for entry into archive by Ana Carolina Gonçalves Bet null (abet@iq.unesp.br) on 2018-03-26T20:34:53Z (GMT) No. of bitstreams: 1 campanella_jem_me_araiq_int.pdf: 3024672 bytes, checksum: 3aeefce6e97b29e1c03b4f8d62b6146c (MD5) / Made available in DSpace on 2018-03-26T20:34:53Z (GMT). No. of bitstreams: 1 campanella_jem_me_araiq_int.pdf: 3024672 bytes, checksum: 3aeefce6e97b29e1c03b4f8d62b6146c (MD5) Previous issue date: 2018-03-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Trabalhos anteriores realizados pelo nosso grupo levaram à identificação da proteína RVB-1 de Neurospora crassa como capaz de se ligar a um fragmento de DNA contendo o motif STRE (Stress Responsive Element). Este elemento de DNA, em Saccharomyces cerevisiae, é descrito estar presente na região promotora de genes responsivos a estresse, incluindo o estresse térmico. Uma busca nos bancos de dados de proteínas mostrou que a RVB-1 apresenta homologia estrutural à proteína RuvBL1 de humanos. Além disso, esta proteína é descrita possuir uma proteína paráloga, RuvBL2 ou Rvb2 de humano e S. cerevisiae, respectivamente, cuja proteína ortóloga em N. crassa foi denominada RVB-2. As proteínas RuvBLs foram encontradas estarem associadas a vários processos celulares, muito provavelmente devido as suas capacidades de formar grandes complexos proteicos e possuírem atividade ATPásica. Neste trabalho, estas proteínas foram parcialmente caracterizadas do ponto de vista funcional, bioquímico e biofísico. Os resultados obtidos por microscopia de fluorescência mostraram que ambas apresentam localização nuclear quando o fungo foi exposto a estresse térmico. A análise da expressão da proteína RVB-V5 mostrou estar aumentada, nessa mesma condição ambiental, quando analisada por Western blot. As duas proteínas foram produzidas na forma recombinante em Escherichia coli, tanto isoladamente quanto juntas, e a análise da expressão mostrou alta estabilidade em solução quando ambas foram produzidas em uma mesma célula de bactéria. Ambas mostraram interagir in vitro por análise de pulldown e o complexo RVB-1/2 mostrou ser formado principalmente por α-hélices através de espectropolarimetria de dicroísmo circular. Análise em gel filtração analítica sugeriu que o complexo apresenta diferentes estruturas oligoméricas, quando analisado na ausência e na presença de ATP. O complexo apresentou atividade ATPásica in vitro, o que fortemente sugere que ambas pertencem à família AAA+. Resultados de retardamento em gel de agarose (EMSA), mostraram que tanto separadamente, como na forma de complexo, essas proteínas são capazes de se ligar a fragmentos de DNA dupla fita independentemente de ATP. / Previous work by our group identified the Neurospora crassa RVB - 1 protein as able of binding to a DNA fragment containing the Stress Responsive Element (STRE). In Saccharomyces cerevisiae, this element is present in the promoter region of genes responsive to stress, including heat stress. RVB - 1 shows structural homology to human RuvBL1 protein, and is described to have a paralog, the RuvBL2 or Rvb2 protein in human and S. cerevisiae , respect ively. The N. crassa orthologous protein was identified and named RVB - 2. The RuvBLs proteins have been found to be associated with diverse cellular processes, most likely due to their ability to form large protein complexes and to have ATPase activity. In this work, these proteins were functional, biochemical and biophysically characterized. The fluorescence microscopy results showed that both proteins present nuclear localization in the fungus exposed to heat stress. Analyses of protein expression by Weste rn blot showed an increased expression of the RVB - 1 - v5 protei n in this same condition . The two proteins were produced in Escherichia coli, and expression analyses showed higher stability in solution when both were produced together. Both proteins showed in vitro interaction by pulldown analysis. The RVB - 1/2 complex has the secondary structure mostly formed by α - helices as analysis by CD. The size - exclusion chromatography suggested that the complex present different oligomeric structures when analyzed in the absence and presence of ATP. They present in vitro ATPase activity, which strongly suggest that both belong to the AAA + family. Electrophoresis Mobility Shift Assay (EMSA) showed that both proteins are able to bind to dsDNA fragments, in an ATP - independently manner.

La production d'eau chaude via des capteurs solaires photothermiques est une technique en expansion qui permettra de limiter l'utilisation des sources conventionnelles d’énergie (combustibles fossiles, nucléaire…). Le cuivre noir (CuO) s’avère être un matériau possédant des propriétés optiques sélectives intéressantes pour cette application. Ainsi, son utilisation au sein d’un absorbeur sous forme d’un matériau « tandem » est une solution envisagée. Le défi que nous avons tenté de relever au cours de ce travail, a été de réaliser ce type de matériau par dépôt électrophorétique (EPD) de nanoparticules de CuO déposé sur un substrat métallique de type wafer de silicium recouvert de platine ou d’or. Ce substrat « modèle » a été utilisé dans un premier temps, car il facilite la mise en œuvre de techniques de caractérisation telles que l’analyse par diffraction X en incidence rasante (GIXRD) ou l’analyse en coupe par microscopie électronique à balayage. Pour ce faire, la stabilisation de la suspension colloïdale de CuO, qui est une condition sine qua non pour la réalisation d’un dépôt électrophorétique, a été étudiée dans un solvant organique tel que l'isopropanol par ajout de Mg(NO3)2, ainsi que dans l’eau en utilisant du polyethylenimine comme dispersant. Ces deux adjuvants agissent comme des agents stabilisants et apportent aux nanoparticules une charge positive ce qui permet la réalisation d'un EPD cathodique. Afin d’optimiser la formulation des suspensions, la stabilité colloïdale en fonction de la teneur en stabilisant a été étudiée avant tout dépôt, par diffusion dynamique de la lumière (DLS) couplée à la vélocimétrie laser à effet Doppler.Différents revêtements contenant du CuO ont été obtenus en faisant varier les paramètres classiques de l’EPD (temps de dépôt, champ électrique, concentration en nanoparticules) pour pouvoir contrôler l'épaisseur finale et la morphologie. Par conséquent, la sélectivité optique et le rendement du tandem résultants peuvent être optimisés en jouant sur l’ensemble de ces paramètres. Des dépôts homogènes ont été obtenus pour [CuO] =5x10-4 g/cm3 pour les deux milieux. Les meilleures conditions sont 50 V.cm-1// 30mn pour la suspension d'IPA et 2 V.cm-1 // 120 mn pour la suspension en milieu aqueux. La composition et l'épaisseur des dépôts sont analysées par GIXRD, et par microscopie électronique (SEM-EDS). Pour les conditions optimisées, les matériaux tandem obtenus à partir de la suspension d'IPA+CuO possèdent une densité de 1.69 g/cm3 avec une grande rugosité. Au contraire, des surfaces homogènes et régulières sont obtenues en milieu aqueux et les dépôts présentent une densité beaucoup plus élevée d’environ 5.7 g/cm3.L’absorptance (α) et l’émittance (ԑ) ont été calculées à partir des spectres de réflectance de l'UV-VIS-NIR et de l’Infrarouge lointain, respectivement. L'efficacité (ƞ) du revêtement tandem obtenu en milieu aqueux est comprise entre 0.8-0.87 tandis qu’elle est seulement de 0.7 dans l’IPA. De plus, la faisabilité de l’EPD sur d’autres substrats métalliques plus conventionnels en vue d’une application (acier, aluminium, cuivre) a été explorée. L'efficacité des dépôts a pu être améliorée par des post-traitements de deux types. D’une part, en pyrolysant à 400°C sous atmosphère inerte le polymère (PEI) incorporé dans le revêtement. Le carbone résiduel obtenu à l’issue de cette pyrolyse a permis d’augmenter l’absorbance. D’autre part, en déposant sur la surface des revêtements une couche de nanoparticules de SiO2 qui joue le rôle de couche anti-réflexion et permet également de protéger la surface. Les deux voies ont été réalisées avec succès et le rendement le plus élevé obtenu pour ces revêtements est de 0.9. / The production of hot water by using efficient photothermal solar collectors is growing in importance to limit the use of fossil fuels. Black copper (CuO) has proved to be one of the viable solar-selective coatings owing to its nearly intrinsic properties. The formation of a tandem absorber based on CuO thin film deposited onto a highly IR reflecting metallic substrate is processed by electrophoretic deposition (EPD).In this way, the stabilization of a CuO colloidal suspension is studied previously by adding Mg(NO3)2 in isopropanol (IPA) or polyethylenimine (PEI) in water suspension. Both acts as positively charging agents and allow the realisation of a cathodic EPD. The colloidal stability as a function of the stabilizing agent content is studied prior to EPD, by dynamic light scattering (DLS) coupled with laser doppler velocimetry.CuO tandem absorbers are obtained by varying different EPD parameters to control the final thickness and also the morphology. Consequently, the optical selectivity of the tandem material is tuned and optimized. The deposition yield is compared relative to the different applied voltage range, deposition time and nanoparticle concentrations. Homogeneous deposits are obtained for [CuO]=5x10-4 g/cm3 from both suspensions. The optimum applied voltage is found to be 50 V.cm-1 for IPA suspension and 2 V.cm-1 for H2O suspension, for deposition times of 30 mins and 120 mins, respectively. The composition and the thickness of the coatings are analysed by Grazing Incidence X-ray diffraction (GIXRD), scanning electron microscopy (SEM) and the density is obtained from energy-dispersive X-ray spectroscopy (EDX). For the previously mentioned optimized conditions, CuO tandem absorbers derived from IPA suspension possess a density of 1.69 g/cm3 with high surface roughness. In contrast, homogeneous and regular surfaces is obtained from water suspensions having a higher density of 5.7 g/cm3.Moreover, absorptance (α) and emittance (ԑ) are calculated from the reflectance spectra of the UV-Vis-NIR and the Fourier transform InfraRed (FTIR) spectroscopy, respectively. α and ԑ were combined to determine the efficiency (ƞ) of the tandem material. Tandems obtained from water suspension has ƞ=0.8 -0.87 while from IPA ƞ=0.7. Besides, the applicability of this EPD is checked by performing other deposit of CuO on metallic substrates of different types.CuO tandems obtained from water suspensions are clearly more prominent to be used as solar selective tandem absorbers due to the high calculated ƞ value reported. The efficiency of such selective tandem absorbers was further enhanced by carbonization (pyrolysis under inert atmosphere) of the polymer (PEI) embedded in the coating. Otherwise, a thin film of SiO2 nanoparticles was deposited at the surface of the selective tandem absorbers to protect them. Both routes were successfully processed and proved to raise ƞ to 0.9.

Magister Scientiae - MSc / Ischemic heart disease is a disease which is characterized by the reduced blood supply to the heart. According to WHO 2013, ischemic heart disease is one of the major causes of death globally. For this reason, it is imperative to search for methods whereby heart cells can be protected from cell death. The upregulation of heat shock proteins (Hsps) is one of the major techniques which can be used to protect the heart cells from Hsps cell death and improve the tolerance to ischemic stresses in various models. The increased expression of Hsps during heat shock pre-conditioning is regulated by heat shock transcription factors (HSFs). HSFs orchestrate the initiation of gene expression by binding to sequence motifs, known as cis-acting regulatory elements (CAREs). Since gene expression is regulated at a transcriptional level, it is expected that functionally related genes (e.g. heat shock response genes) might also be regulated by the same transcription factors (TFs). In this study an in silico approach was performed to identify the promoter sequences of 50 known heat shock responsive genes using Genomatix Software. This software was also used to identify transcription factor binding sites that are statistically over represented in the promoter sequences of these genes. The use of the Electrophoretic Mobility Shift Assay was included to confirm that protein cell lysates of stressed cells contain proteins (TFs) that bind to this sequence (SP1F_KLFS_01). Luciferase promoter reporter assay were also used to iii investigate the transcriptional activity of mutant promoter constructs in which the SP1F_KLFS_01 was mutated. SP1F_KLFS_01 is a ±25 base pair sequence that was identified in the promoter sequences of 19 heat shock responsive genes, including the well-known Hsp70 and Hsp90. This sequence is a potential binding site for two TFs, Specificity Protein-1 and Krueppel like TFs. Consequently, the aim of this study is to identify CAREs that are statistically over-represented in the promoter regions of heat shock response genes. In conclusion, in vitro experiments of this study did not support the findings of the in silico experiments, therefore additional methods should be implemented to expand the investigation for the involvement of cis-acting regulatory elements in the regulation of heat shock proteins in cardiomyocytes, prior to heat shock.

Aeronautical industry is interested in using damage tolerant, high strength and lightweight materials in the manufacture of some structural components that must attend tight requirements. Carbon nanotubes doped multiscale composites are good new generation material candidates to improve aeronautical grade composites. This project includes comprehensive characterization studies of electrophoretic deposition treated carbon nanotubes doped carbon fiber polymer composites with different stacking sequences. For comparison purposes, spray-on treated carbon nanotubes doped carbon fiber composites and non-doped reference composites with different stacking sequence are also studied. The goal of the project is to verify the link between the effects of carbon nanotubes addition, micro-nanostructure and macro material properties. To achieve this goal, several thermal loading damage analyses and investigations on micron and sub-micron scale were performed. In this thesis, the readers will be able to find the necessary theoretical background information, experimental procedure, results and conclusions gained throughout this project. / <p>Validerat; 20120621 (anonymous)</p>

This diploma thesis deals with the preparation of doped piezoceramic materials based on BaTiO3 using electrophoretic deposition. Five rare earth oxides, i.e. Er2O3, Dy2O3, Eu2O3, Tb407 and CeO2, were used as dopants in amounts of 1, 3, and 5 wt. %. The prepared deposits were evaluated in terms of preparation methodology, high temperature dilatometry, X-ray diffraction analysis, relative density, mean grain size, hardness and fractographic analysis. The study of dilatometric curves described the sintering behavior and its changes at different material compositions. X-ray diffraction analysis revealed a tetragonal phase in all samples; the tetragonality of the BaTiO3 crystalline cell decreased with dopant content. By a suitable choice of dopant, it was possible to significantly increase the relative density of sintered samples, their hardness and at the same time prevent the samples from coarsening of the microstructure during heat treatment. A relative density up to 98 %, a mean grain size below 1 m and a hardness of over 10 GPa were achieved. Analysis of the fracture surfaces revealed that the fracture mode was transcrystalline for the most of studied materials; only the samples doped with cerium dioxide had fracture surfaces with both transcrystalline and intercrystalline fracture modes. Based on the obtained results, a suitable composition of the material for the intended use in a layered piezoceramic harvester was identified, which, in addition to the BaTiO3 layers, consists of functionally-protective Al2O3 and ZrO2 layers.

This master‘s thesis deals with study of basic physical, microstructural and mechanical properties of doped piezoceramic materials based on BaTiO3 prepared by electrophoretic deposition. The dopants used were rare earth oxides, i.e. Eu2O3, Er2O3, CeO2, Dy2O3 and Tb4O7 in amounts 1, 3 and 5 wt. %. The influence of dopants and their amount on density, phase composition, mean grain size, hardness, elastic modulus, fracture toughness, and flexural strength was examined. Suitable dopant choice enabled decrease in mean grain size and increase in relative density, hardness, elastic modulus, fracture toughness and flexural strength of sintered specimens. Relative densities up to 99 %, mean grain size below 1 m, hardness up to 13,1 GPa, elastic modulus up to 199 GPa, fracture toughness above 1 MPa·m1/2 and flexural strength above 115 MPa were achieved.