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Polpa celulósica, para obtenção de carboximetilcelulose (CMC), foi obtida a partir do bagaço de cana-de-açúcar através de separação do material em fração fibrosa e medula, sua pré-hidrólise, posterior polpação soda/antraquinona e etanol/água. A polpa soda/antraquinona da fração fibra foi submetida ao processo de branqueamento para obter um material rico em celulose de alta pureza. A polpa branqueada da fração fibra foi utilizada na preparação da CMC na forma de sal de sódio e lítio. Para reações de enxertia foram utilizadas amostras de CMC preparadas no laboratório e comerciais usando isocianatos comerciais e sintetizados. Tanto a CMC como a CMC enxertada foram caracterizadas através de análises térmicas (DSC, TGA), espectroscopia no infravermelho (IV), ressonância magnética nuclear de carbono 13 (RMN 13C) e por microscopia eletrônica de varredura (MEV) e Espectroscopia Dispersiva de Raios-X (EDX). A análise detalhada dos espectros de IV e RMN 13C indica a formação de ligações uretanas em diferentes números de onda e deslocamentos químicos dependendo da CMC e isocianato utilizado. Também observa-se uma pequena mudança na linha de base da curva de DSC indicando uma possível transição vítrea da CMC que diminui após a enxertia da CMC com isocianato. Micrografias de MEV mostraram mudanças estruturais com as reações e a análise através de (EDX) um aumento no teor de carbono e diminuição no de oxigênio com as graftizações. Medidas de condutividade demonstraram que a NaCMC graftizada com isocianato de poli(óxido de propileno) apresenta condutividade de 10-5 S/cm a 100oC, comparável com outros eletrólitos sólidos poliméricos / The cellulosic pulp obtained from sugar cane bagasse was used to synthesize carboxymethylcellulose (CMC), the substrate for the grafting reactions with mono and di-isocyanathes. The sugar cane bagasse was separated into fiber and non-fiber fractions that then were submitted to the pre-hydrolyses and pulping reactions (sodium hydroxide/anthraquinone and ethanol/water). After that the sodium hydroxide/anthraquinone pulp of the fiber fraction was bleached to obtain a high purity cellulosic material. This cellulose was used to obtain the sodium and lithium salts of CMC (NaCMC and LiCMC respectively). Then these samples were used for grafting reactions with commercial octadecylisocyanate and hexamethylene-diisocyanate and synthesized monoisocyanate of poly(propylene oxide). All the samples were characterized through thermal analyses (DSC/TGA), infra-red spectroscopy (IR), solid state 13C nuclear magnetic resonance (13C-NMR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The thermal analysis indicate a possible glass transition of CMC at about 65oC that decreases for to about 29oC after the grafting reaction with isocyanate. The micrographs show structural changes occurred during the several reactions confirmed by thermal analysis. The detailed analysis of IR and NMR 13C spectra of grafted samples indicated the formation of urethane bonds. Conductivity measurements of NaCMC grafted with the poly(propylene oxide) isocyanate gave the value of 10-5 S/cm at 100oC that is comparable with other polymeric solid electrolytes.

Polpa celulósica, para obtenção de carboximetilcelulose (CMC), foi obtida a partir do bagaço de cana-de-açúcar através de separação do material em fração fibrosa e medula, sua pré-hidrólise, posterior polpação soda/antraquinona e etanol/água. A polpa soda/antraquinona da fração fibra foi submetida ao processo de branqueamento para obter um material rico em celulose de alta pureza. A polpa branqueada da fração fibra foi utilizada na preparação da CMC na forma de sal de sódio e lítio. Para reações de enxertia foram utilizadas amostras de CMC preparadas no laboratório e comerciais usando isocianatos comerciais e sintetizados. Tanto a CMC como a CMC enxertada foram caracterizadas através de análises térmicas (DSC, TGA), espectroscopia no infravermelho (IV), ressonância magnética nuclear de carbono 13 (RMN 13C) e por microscopia eletrônica de varredura (MEV) e Espectroscopia Dispersiva de Raios-X (EDX). A análise detalhada dos espectros de IV e RMN 13C indica a formação de ligações uretanas em diferentes números de onda e deslocamentos químicos dependendo da CMC e isocianato utilizado. Também observa-se uma pequena mudança na linha de base da curva de DSC indicando uma possível transição vítrea da CMC que diminui após a enxertia da CMC com isocianato. Micrografias de MEV mostraram mudanças estruturais com as reações e a análise através de (EDX) um aumento no teor de carbono e diminuição no de oxigênio com as graftizações. Medidas de condutividade demonstraram que a NaCMC graftizada com isocianato de poli(óxido de propileno) apresenta condutividade de 10-5 S/cm a 100oC, comparável com outros eletrólitos sólidos poliméricos / The cellulosic pulp obtained from sugar cane bagasse was used to synthesize carboxymethylcellulose (CMC), the substrate for the grafting reactions with mono and di-isocyanathes. The sugar cane bagasse was separated into fiber and non-fiber fractions that then were submitted to the pre-hydrolyses and pulping reactions (sodium hydroxide/anthraquinone and ethanol/water). After that the sodium hydroxide/anthraquinone pulp of the fiber fraction was bleached to obtain a high purity cellulosic material. This cellulose was used to obtain the sodium and lithium salts of CMC (NaCMC and LiCMC respectively). Then these samples were used for grafting reactions with commercial octadecylisocyanate and hexamethylene-diisocyanate and synthesized monoisocyanate of poly(propylene oxide). All the samples were characterized through thermal analyses (DSC/TGA), infra-red spectroscopy (IR), solid state 13C nuclear magnetic resonance (13C-NMR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The thermal analysis indicate a possible glass transition of CMC at about 65oC that decreases for to about 29oC after the grafting reaction with isocyanate. The micrographs show structural changes occurred during the several reactions confirmed by thermal analysis. The detailed analysis of IR and NMR 13C spectra of grafted samples indicated the formation of urethane bonds. Conductivity measurements of NaCMC grafted with the poly(propylene oxide) isocyanate gave the value of 10-5 S/cm at 100oC that is comparable with other polymeric solid electrolytes.

Ostracism has been shown to have a variety of negative effects on the target, though the reported nature of these has varied due to differing manipulations of the phenomenon. The experiments reported attempt to characterise the consequences of computer-mediated (CM) ostracism using a range of approaches. Investigation of on-line social behaviour in Internet chat rooms revealed similar patterns of group behaviour, including ostracism, to those reported in face-to-face communication. Fourier analyses revealed periodic structure to the comments made in CM group communication qualitatively similar to that previously reported in dyadic face-to-face communication. Identity changes and ostracism occurrences were also found to be periodic. The power spectra produced by these analyses revealed that comments, identity changes and ostracism typically showed a gradient of 1/f - 11/, a characteristic common to many physical and biological systems but not previously reported in social communication. Further experiments revealed that level of anonymity did not modulate a reduction in comments made by CM ostracised participants. Thus the partial anonymity conferred by CM communication cannot account for the differential effect of ostracism in CM and face-to-face contexts. Experiments on the effect of ostracism upon cognition revealed that ostracised participants reacted significantly slower on a Strop task, but made fewer errors. Performance on a Remote Associates Task was bifurcated whereby those who accurately estimated the extent of their exclusion performed significantly worse than non-ostracised participants. Ostracised participants who under-estimated their exclusion performed similarly to non-ostracised participants. Many of these findings are consistent with a hypothesis that ostracism may be considered a form of (social) pain whose consequences may be mediated by neural substrates that partially overlap with those implicated in responses to physical pain. The findings suggest that a full characterisation of individual and situational differences in ostracism effects may require a combination of techniques, from neuron-imaging to traditional social psychological methodologies.

Autoignition of high pressure methane jets at engine relveant conditions within a shock tube is investigated using Conditional Moment Closure (CMC). The impact of two commonly used approximations applied in previous work is examined, the assumption of homogeneous turbulence in the closure of the micro-mixing term and the assumption of negligible radial variation of terms within the CMC equations. In the present work two formulations of an inhomogeneous mixing model are implemented, both utilizing the β -PDF, but differing in the respective conditional velocity closure that is applied. The common linear model for conditional velocity is considered, in addition to the gradient diffusion model. The validity of cross-stream averaging the CMC equations is examined by comparing results from two-dimensional (axial and radial) solution of the CMC equations with cross-stream averaged results. The CMC equations are presented and all terms requiring closure are discussed. So- lution of the CMC equations is decoupled from the flow field solution using the frozen mixing assumption. Detailed chemical kinetics are implemented. The CMC equations are discretized using finite differences and solved using a fractional step method. To maintain consistency between the mixing model and the mixture fraction variance equation, the scalar dissipation rate from both implementations of the inhomogeneous model are scaled. The autoignition results for five air temperatures are compared with results obtained using homogeneous mixing models and experimental data. The gradient diffusion conditional velocity model is shown to produce diverging be- haviour in low probability regions. The corresponding profiles of conditional scalar dis- sipation rate are negatively impacted with the use of the gradient model, as unphysical behaviour at lean mixtures within the core of the fuel jet is observed. The predictions of ignition delay and location from the Inhomogeneous-Linear model are very close to the homogeneous mixing model results. The Inhomogeneous-Gradient model yields longer ig- nition delays and ignition locations further downstream. This is influenced by the higher scalar dissipation rates at lean mixtures resulting from the divergent behaviour of the gradient conditional velocity model. The ignition delays obtained by solving the CMC equations in two dimensions are in excellent agreement with the cross-stream averaged values, but the ignition locations are predicted closer to the injector.

Autoignition of high pressure methane jets at engine relveant conditions within a shock tube is investigated using Conditional Moment Closure (CMC). The impact of two commonly used approximations applied in previous work is examined, the assumption of homogeneous turbulence in the closure of the micro-mixing term and the assumption of negligible radial variation of terms within the CMC equations. In the present work two formulations of an inhomogeneous mixing model are implemented, both utilizing the β -PDF, but differing in the respective conditional velocity closure that is applied. The common linear model for conditional velocity is considered, in addition to the gradient diffusion model. The validity of cross-stream averaging the CMC equations is examined by comparing results from two-dimensional (axial and radial) solution of the CMC equations with cross-stream averaged results. The CMC equations are presented and all terms requiring closure are discussed. So- lution of the CMC equations is decoupled from the flow field solution using the frozen mixing assumption. Detailed chemical kinetics are implemented. The CMC equations are discretized using finite differences and solved using a fractional step method. To maintain consistency between the mixing model and the mixture fraction variance equation, the scalar dissipation rate from both implementations of the inhomogeneous model are scaled. The autoignition results for five air temperatures are compared with results obtained using homogeneous mixing models and experimental data. The gradient diffusion conditional velocity model is shown to produce diverging be- haviour in low probability regions. The corresponding profiles of conditional scalar dis- sipation rate are negatively impacted with the use of the gradient model, as unphysical behaviour at lean mixtures within the core of the fuel jet is observed. The predictions of ignition delay and location from the Inhomogeneous-Linear model are very close to the homogeneous mixing model results. The Inhomogeneous-Gradient model yields longer ig- nition delays and ignition locations further downstream. This is influenced by the higher scalar dissipation rates at lean mixtures resulting from the divergent behaviour of the gradient conditional velocity model. The ignition delays obtained by solving the CMC equations in two dimensions are in excellent agreement with the cross-stream averaged values, but the ignition locations are predicted closer to the injector.

Processing fluency describes the assessment of how easy a stimulus is to cognitively process, an assessment which can be mistakenly applied to judgments of other aspects of the stimulus. This dissertation introduces a novel approach to understanding the development of impressions from online profiles by incorporating the role of processing fluency in interpersonal judgments based on a social networking profile. 195 participants (155 females) were asked to view the "about me" section of a social networking profile, which had been manipulated according to one of three fluency conditions to be harder or easier to process. Participants completed scales assessing liking, similarity, trust, and compatibility, and their disclosure was measured in an open-response item. Confirming expectations based on the processing fluency literature, each of these variables was increased in the high fluency profile condition. No differences in these variables were found between the low fluency conditions and a control condition, and analysis revealed that the manipulations intended to lower fluency may have been too salient to participants. Broadly, this study shows that processing fluency can influence impression formation from online profiles across a number of meaningful relational variables. Enhancing processing ease may allow online interactants a relational "jump-start," increasing liking, perceptions of similarity, trust, compatibility, and disclosure. These findings hold important implications for the role of processing fluency in computer-mediated communication and for models of online relationship development. / text

Les matériaux composites connaissent un large succès. En effet les Composites à Matrice Céramique (CMC) fonctionnant à haute température ont des performances inégalées en termes de fatigue thermomécanique. La durée de vie des CMC est pourtant limitée en raison de l'apparition précoce de fissures matricielles, ouvrant autant de portes à des environnements agressifs, entraînant un abattement prématuré des propriétés mécaniques. Arriver à retarder la fissuration matricielle devient donc une étape clé pour une future importante utilisation des CMC dans l'aéronautique ou l'aérospatial. Les travaux de cette thèse se sont inscrits dans cette logique, où pour protéger les fibres et l'interphase de l'oxydation et de la corrosion, les propriétés de la matrice céramique ont tenté d'être modifiées par l'incorporation de nanofibres en leur sein et par l'émoussement de leurs macropores résiduels. / Abstract

The purpose of this study was to gain insight into the characteristics of student-teacher interactions between Korean EFL preservice teachers and elementary school students during online exchanges and of the preservice teachers’ overall impressions and perceptions of teaching English to elementary school students and interacting with them online. The participants in this study were 31 Korean preservice elementary school teachers and 10 Korean elementary school students who were learning English as a foreign language. Ten groups with an average of three preservice teachers were paired with one child partner per group and engaged in one-on-one email exchanges, mostly using English, in discussing English books. Data came from multiple sources, including transcripts of the online exchanges between the preservice teachers and the child partner, preservice teachers’ collaborative dialogue scripts, their responses to questionnaires, their group reflection journals, individual final reflection papers, and researcher field notes. These data were analyzed using a combination of inductive and deductive data analysis methods. Through inductive analysis using the constant comparative analysis method (Glaser & Strauss, 1967; Lincoln & Guba, 1985), I derived themes that captured the experience of online interactions and the strategies that the preservice teachers used to maintain the exchange. Through deductive analysis, I identified groups that were more and less successful and described their experiences. Results indicated that the online exchanges with elementary students provided Korean EFL preservice teachers opportunities to practice teaching skills, as well as to develop close personal and social relationships with their child partners. Also, how the preservice teachers approached the exchanges and their specific online “actions” seemed to make a difference in their child partners’ responses, thereby yielding results in which some groups were more successful and others less successful. The preservice teachers reported that their participation in the project was beneficial for them as future elementary teachers of English and that they enjoyed interacting with their child partners online. Finally, the participation in the project appeared to have many benefits for the preservice teachers’ professional development, including newly-gained insights into the benefits of using technology as a valuable instructional tool in their future teaching practices as well as an increase in their confidence in using English to teach English to elementary students. / text