No description available.

Functional nanoparticles have garnered considerable attention due to their intriguing physical properties at the nanoscale for a broad range of applications, such as photocatalysis, capacitive energy storage, thermoelectric power generation, solar energy harvesting, flexible and transparent electronics, drug delivery, biomolecular electronics, and analytic chemistry, etc. Successful synthesis of nanoparticles and precise control over their shapes are critical to achieving desired functions. In the first part of my thesis, an effective synthetic route to plain nanoparticles is briefly introduced. Based on this general route, the synthesis of solid iron oxide nanoparticles and a slightly modified synthetic method of solid silica nanoparticles are presented in detail. In the second part of my thesis, simulation of optical absorption spectra and plasmonic near-field maps of gold nanoparticle and gold/titanium oxide nanoparticle are explored, and the effectiveness of simulation in predicting, optimizing, and guiding experimental design is emphasized.

Le lien entre les éléments volatils CO₂-H₂O et la fusion mantellique a depuis maintenant longtemps été illuminé par l’expérimentation. Une large base de données expérimentales existe et souligne l’effet primordial de ces éléments sur l’abaissement des températures de fusion de la péridotite ainsi que sur la composition des liquides magmatiques produits comme une fonction des conditions P – T – fo₂ – composition du système. Néanmoins, la diversité et la complexité de cette base de données peuvent compliquer sa compréhension globale. Dans cette étude, une analyse détaillée de la composition des liquides magmatiques riches en CO₂ et H₂O est réalisée, soulignant notamment une transition non-linéaire et plus ou moins abrupte entre des liquides carbonatitiques et des liquides silicatés. Un modèle thermodynamique est élaboré afin de calculer l’activité de SiO₂ dans les liquides magmatiques riches en CO₂-H₂O (aSiO₂(l)) et coexistant avec un assemblage péridotitique, depuis des termes carbonatitiques jusqu’à des termes basaltiques. L’application de ce modèle dans des conditions de ride océanique prédit la stabilisation des liquides carbonatitiques au démarrage de la fusion redox (liée à la transition graphite/diamant- carbonates) jusqu’à environ 100 km de profondeur, avant d’évoluer plus ou moins abruptement vers des liquides silicatés riche en CO₂. Au niveau des cratons, les kimberlites de Groupe I sont stabilisés en base de lithosphère (~250 km de profondeur), et peuvent être formés à partir d’un plume mantellique. L’épaisseur de cette lithosphère empêche la remontée du plume et la formation des OIB. Afin de décrire plus pleinement les propriétés thermodynamiques du liquide magmatique, un modèle plus complexe (système CMAS-CO₂) est en construction, dont la méthodologie est modifiée par rapport au précédent modèle calculant aSiO₂(l) ; un effort tout particulier est ici mené afin de mieux considérer les incertitudes expérimentales et thermodynamiques. / The link between volatiles (CO₂-H₂O) and mantle melting has so far been illuminated by experiments. A large experimental database exists and emphasizes the importance of volatiles on lowering solidus temperatures of peridotite and modifying the melt composition as a function of P – T – fo₂ – bulk composition. Nevertheless, the diversity and the complexity of this experimental database may complicate its global understanding. In this study, an analysis of CO₂-H₂O-rich melt composition is done, emphasizing the non-linear and more or less abrupt character of the transition between carbonate-rich melts and silicate-rich melts. A thermodynamic model is accomplished to calculate the silica activity in CO₂-H₂O-rich melts coexisting with peridotite assemblage and covering carbonatitic to basaltic terms. Along an oceanic ridge adiabat, the model predicts that carbonatitic melts can be stabilized at the onset of “redox melting” (transition between graphite/diamond-carbonates) to about 100 km depth, before abruptly evolving towards carbonated silicate melts. In cratons, Group I kimberlites are stabilized at the base of the lithosphere (about 250 km depth), and can originate from a mantle plume. The thickness of the lithosphere prevents the plume ascent and the production of OIB. In the aim of describing the melt thermodynamic properties more precisely, a more complex model (system CMAS-CO₂) is under construction, with a modified methodology relative to the previous model of silica activity; a specific effort is here conducted in order to better consider experimental and thermodynamic uncertainties.

We have developed continuous random network (CRN) model based Metropolis Monte Carlo simulation tools which are capable of predicting the structural properties of amorphous semiconductor and oxide materials as well as their interface. To bolster the reliability of the CRN model, we have developed force fields based on gradient corrected density functional theory (DFT) calculations. Our in-house CRN-MMC tools have been massively parallelized, which allows us to create fairly large model structures within a reasonable computational time. Using the integrated CRN-MMC tools, we have elucidated the complex growth and structure of self-interstitial and vacancy clusters in silicon and the effect of strain on the structure and stability of the defect clusters. Our work for vacancy clusters suggests that small vacancy defects exclusively favor fourfold-coordination thermodynamically with no significant kinetic limitation rather than void-like structure formation, which has widely been adapted to explain the behavior and properties of vacancy defects. Our results also highlight the identification of stable high-symmetry fourfold-coordinated V₁₂ and V₃₂ clusters that could be expected to exist to a large extent in a vacancy rich region although its direct characterization appears impractical at present. Our work for self-interstitial clusters provides the first theoretical support for earlier experiments which suggest a shape transition from compact to elongated structures around n = 10. When the cluster size is smaller than 10, the stable I₄ and I₈ compact clusters are found to inhibit the formation of elongated defects, whereas the newly discovered fourfold-coordinated I₁₂ state is found to serve as an effective nucleation center for large extended defects. Our CRN-MMC approach also enabled us to elucidate the underlying mechanisms of synthesis and manipulation of Si rich insulators as well as the fundamental understanding of the relationship between the atomic structure and properties. We developed a valence force field based on a modified Keating model for the structure and energetics of amorphous Si rich oxide materials. In particular, our work emphasizes the importance of correctly describing the wide Si-O-Si angle distribution. Our work also suggests that the relative rigidity between Si and SiO₂ matrices is critical in determination of the Si/SiO₂ interface structure. The present potential model coupled with the CRN-MMC method can be used to create structural models (free of coordination defects) for complex a-SiO[subscript x]-based materials, which will further allow thorough studies of the properties of these materials. / text

This study proposes a polarization-independent liquid-crystal Fresnel lens using the twisted nematic liquid crystal (TN-LC). At the high voltage state, the TN-LC behaves as an optically anisotropic material which makes the proposed LC Fresnel lens possess a polarization-insensitive characteristic. Two kinds of LC Fresnel lens, photoresist type and patterned electrodes type, are prepared in our experiment. Experimental results reveal that the photoresist type has a high diffraction efficiency and a good polarization-independent characteristic. However, its diffraction efficiency cannot be switched off. Contrarily, the patterned electrode type has the characteristics of the switch-off and good polarization-independent with a moderate diffraction efficiency

No description available.

The purpose of this study was to conduct a qualitative examination which explored the Social Innovation Orientation (SIO) of Corporate Social Responsibility (CSR) practitioners as part of a broader contribution towards developing an augmenting and or an alternative mechanism to address the challenges faced by CSR practitioners and companies in fulfilling societal expectations in developing countries. The study sought to answer the question: In what ways are CSR practitioners building an SIO? The study also aimed to answer questions on whether any profound change or challenge was posed by CSR practitioners to the current systems through basic routines, authority flows, beliefs and resources (Westley and Antadze, 2010). The status of CSR advancement by companies was also explored. These questions were answered in the context of a developing country, more specifically South Africa. In order to set a relevant contextual background, the literature review covered two main broad variables, CSR and social innovation, as well as a detailed description of an SIO through four facets, namely: social experimentation, collaboration and inclusivity, scale mind-set, and institutional impact. The sample comprised CSR practitioners who met the sampling criteria. Information was gathered from these CSR practitioners using a semi-structured interview protocol. An analysis of the data gathered led to the description of the patterns which emerged, which presented across a continuum both narratively and graphically those CSR practitioners who were making the strides on the SIO continuum and those that were not. The study found that even with the CSR practitioners' strong desire to be viewed as delivering results, they needed to manage the expectations of stakeholders, particularly within their own companies, regarding what success was and what it was not. It was discovered that being more deliberate contributes to the building of an SIO. Through a focus on not repeating past mistakes while still working together with stakeholders in a manner which is proactive instead of defensive, CSR practitioners could be building an SIO. The results showed that fostering a participatory and inclusive environment from an early stage was beneficial in the development of an SIO. Another discovery was that the size of an intervention was of less importance than the significance of its potential impact. Practical contributions are proposed for companies and CSR practitioners as a result of this research, some of which are: a support approach to existing mechanisms, a component to be used in recruitment and performance appraisal, and a view to understanding social innovation and what it can mean for the company-centric perspective. Overall, the study revealed that CSR practitioners are building an SIO. Social experimentation, and collaboration and inclusivity were found to be more prevalent than the scale mind-set and institutional impact. SIOs were not void of the latter elements. These two elements should not be discarded. Whilst the SIO elements have been positioned as non-linear, it was revealed that some categorical features and linearity did exist.

Made available in DSpace on 2016-04-04T18:33:07Z (GMT). No. of bitstreams: 1 Jose Aguiar Nobre.pdf: 983069 bytes, checksum: 3514d8014410469a99ee32a0d5564066 (MD5) Previous issue date: 2012-02-01 / Reflecting on the issue of quality democratic and public education from the pedagogical thinking of Anisio Teixeira, let us to understand that to reach of effective education is necessary teachers' education and the favorable conditions for the development of his educational work. The formal question of this thesis is: what are the challenges from the pedagogical thinking of Teixeira, for the implementation of educations democratic, public and quality with? The methodology of work limited to the field of philosophy of education, fostered by literature review led us to understand, with Teixeira, the school is the place by excellence of conquest and defense of basic rights of citizens. The procedure adopted for the survey consisted of two phases: (i) analysis of thesis and dissertations in the CAPES Thesis database, 2006 to 2010 and (ii) reading and abstract of works by expertise in the thought and work of Anisio Teixeira and John Dewey. The theoretical approach consisted in the pragmatism of John Dewey. We reflect on the concept of democracy Teixeira understood not only as a form of government, but as a new social organization, which seeks to give all individuals equal opportunities and equal responsibilities for the free expansion of its values. We discussed about the need for constant evaluation of the potential available in the users of public school for their participation in democratic management, measuring the obstacles to ensure that they do not end up stifling the potential of the community. We also discussed about the real need of education for the realization of empowerment leading to social democratization, measuring the obstacles to ensure that they don?t end up stifling the potential of the community. We also analyze the real need for effective educations leading to the emancipation of social democratization. The results achieved with the research in response to the question raised, highlighted five challenges for effective democratic and public education quality. And therefore we see that a democratic society depends directly on education to be effective. Democracy can not exist without quality education for all citizens, since the transformation is required for all and not just on part of society. / Refletir sobre a quest?o da educa??o democr?tica e p?blica de qualidade a partir do pensamento pol?tico pedag?gico de An?sio Teixeira, neste trabalho, nos levou a entender que a forma??o do educador e as condi??es favor?veis ao desenvolvimento do seu trabalho educativo constituem requisitos essenciais para a efetiva??o dessa educa??o. A pergunta formal desta disserta??o foi assim formulada: quais os desafios, a partir do pensamento pol?tico pedag?gico de An?sio Teixeira, para a efetiva??o da educa??o democr?tica e p?blica de qualidade no Brasil atual? O m?todo do trabalho, circunscrito ao campo da filosofia da educa??o, fomentado por meio da revis?o bibliogr?fica nos levou a compreender, com An?sio Teixeira, que a escola ? o lugar por excel?ncia de conquista e defesa dos direitos essenciais do cidad?o. Os procedimentos adotados para a pesquisa consistiram em duas fases: (i) an?lise de teses e disserta??o no Banco de Teses da CAPES, de 2006 a 2010 e (ii) leitura e fichamentos de obras de autores especialistas no pensamento de An?sio Teixeira e a obra de John Dewey. O referencial te?rico adotado consistiu no pragmatismo de John Dewey. Refletimos sobre a concep??o de democracia de An?sio Teixeira entendendo-a n?o somente como uma forma de governo, mas como uma nova organiza??o social, em que se busca oferecer a todos os indiv?duos iguais oportunidades e iguais responsabilidades para a expans?o livre dos seus valores. Discutimos acerca da necessidade de constante avalia??o sobre as potencialidades dispon?veis na comunidade dos usu?rios da escola p?blica para a sua participa??o na gest?o democr?tica, medindo os obst?culos a fim de que esses n?o acabem por sufocar as potencialidades da comunidade. Analisamos tamb?m sobre a real necessidade da educa??o para a efetiva??o da emancipa??o que conduz ? democratiza??o social. Os resultados alcan?ados com a pesquisa, em resposta ? pergunta levantada, evidenciaram cinco desafios para a efetiva??o da educa??o democr?tica e p?blica de qualidade. E, sendo assim vimos que a sociedade democr?tica depende diretamente da educa??o para se efetivar. N?o podendo a democracia existir sem a educa??o de qualidade para todos os cidad?os, uma vez que a transforma??o se exige para todos e n?o para uma parte da sociedade apenas.

The thermomechanical properties of monolayer graphene and the interfacial interactions between graphene and an SiO₂ substrate are investigated in this dissertation using a multiscale approach. The temperature dependent mechanical behavior of graphene with thermal fluctuations is studied by statistical mechanics analysis under harmonic approximation, which is then compared to molecular dynamics simulations. It is found that the amplitude of thermal fluctuation depends nonlinearly on the graphene size due to anharmonic interactions between bending and stretching modes, but a small positive pre-strain could suppress fluctuation amplitude considerably and results in very different scaling behavior. The thermal expansion of graphene depends on two competing effects: positive expansion due to in-plane modes and negative expansion due to out-of-plane fluctuations. The in-plane stress-strain relation of graphene becomes nonlinear even at infinitesimal strain due to the entropic contribution. Consequently, the modulus of graphene depends on strain non-monotonically, with strain stiffening followed by intrinsic softening. Moreover, it is found that the thermomechnical behavior of graphene is dependent on its interactions with environment such as supporting substrate. The interfacial interactions between graphene and SiO₂ substrate is investigated in terms of three perspectives. Firstly, the interaction mechanisms between graphene and SiO₂ substrate are studied by density functional theory (DFT). The dispersion interaction is found to be the predominant mechanism, and the interaction strength is strongly influenced by changes of SiO₂ surface structures due to surface reactions with water. The adhesion energy is reduced when the reconstructed SiO₂ surface is hydroxylated, and further reduced when covered by a monolayer of adsorbed water molecules. Next, we study the interfacial interactions between graphene and a wet substrate that is covered by a liquid-like water film. During the separation of graphene from the wet substrate, MD simulations show evolution of the water from a continuous film to discrete islands. The water bridging effects are further described by continuum models. Finally, a continuum model is developed to predict how the surface roughness may affect the adhesion between graphene membranes and their substrate. / text

Submitted by Sara Ribeiro (sara.ribeiro@ucb.br) on 2018-04-13T17:29:05Z No. of bitstreams: 1 JoaoBatistadaSilvaDissertacao2017.pdf: 1985015 bytes, checksum: 05122c8ab94bfe518cb37e6b3ea40bf0 (MD5) / Approved for entry into archive by Sara Ribeiro (sara.ribeiro@ucb.br) on 2018-04-13T17:29:20Z (GMT) No. of bitstreams: 1 JoaoBatistadaSilvaDissertacao2017.pdf: 1985015 bytes, checksum: 05122c8ab94bfe518cb37e6b3ea40bf0 (MD5) / Made available in DSpace on 2018-04-13T17:29:21Z (GMT). No. of bitstreams: 1 JoaoBatistadaSilvaDissertacao2017.pdf: 1985015 bytes, checksum: 05122c8ab94bfe518cb37e6b3ea40bf0 (MD5) Previous issue date: 2017-12-15 / This dissertation focuses on scientific morality as a means of overcoming traditional morality featured on the work ???A brief introduction to philosophy of education: the progressive school or the transformation of school??? by An??sio Teixeira. The philosophical view presented in Teixeira???s work was heavily influenced by two works of John Dewey: Experience and education and Democracy and education: introduction to the philosophy of education. Based on these two references, more directly on the first one, in which Dewey developed the theory of experience, Teixeira approached the issue of traditional versus scientific morality. Teixeira???s claims that the traditional morality, which prevailed in his context and that had in the catholic church its most vocal supporters, did not assure that the school, as a medium of education, could cater to a society that had been undergoing fast transformations. This morality, Teixeira argued, harbored in its entirety rigid and authoritarian principles that did not contribute for an optimal individual development once blind obedience, inaction, the respect to books, and professors were unquestionable rules. Therefore, in a society in which, due to scientific progress, had been going through continuous changes in its social tapestry and, above all, with a visible democratic tendency, called for schools to adopt in its pedagogical practice the scientific morality that embraced the advances stemming from the experimental morality. Teixeira argument on the relevance of scientific lied on the fact that it would contribute for a democratic education due to the sheer fact that it would grant the individual freedom of expression of his personality. It would also allow the individual to make his own choices and bear its inherent responsibilities in a way permitted him to be capable of self-government becoming his own master and a promoter of social welfare. / Esta pesquisa tem como objeto a moral cient??fica como supera????o da moral tradicional na obra Pequena introdu????o ?? filosofia da educa????o: a escola progressiva ou transforma????o da escola de An??sio Teixeira. A proposta filos??fica apresentada nesta obra de An??sio sofreu fortes influ??ncias de duas obras de John Dewey, quais sejam: Experi??ncia e educa????o e Democracia e educa????o: introdu????o ?? filosofia da educa????o. A partir destas duas refer??ncias, mais diretamente da primeira, na qual Dewey desenvolve a teoria da experi??ncia, foi que An??sio abordou o problema da moral tradicional versus a moral cient??fica. Compreende An??sio Teixeira que a moral tradicional que prevalecia no seu contexto e que tinha como defensores mais not??rios a Igreja cat??lica, n??o contribu??a para que a escola, enquanto meio de educa????o, pudesse atender a uma sociedade que vinha passando por c??leres transforma????es, j?? que esta moral tinha em seu conjunto preceitos r??gidos e autorit??rios que n??o contribu??am para a boa forma????o do indiv??duo, uma vez que a obedi??ncia e a passividade, o respeito aos livros e aos mestres eram ditames incontest??veis. Portanto, em uma sociedade que, em virtude dos avan??os cient??ficos, vinha sofrendo uma cont??nua mudan??a nos seus arranjos sociais e, sobretudo, com uma expressiva tend??ncia democr??tica, fazia-se necess??rio que a escola adotasse em seu fazer pedag??gico a moral cient??fica que incorporava tais avan??os advindos do m??todo experimental. O argumento de An??sio Teixeira sobre a relev??ncia da moral cient??fica esteia-se no fato de que esta contribuiria para uma educa????o democr??tica pelo simples fato de permitir ao indiv??duo a liberdade de express??o de sua personalidade, bem como de fazer as suas pr??prias escolhas e de assumir as suas reponsabilidades de maneira que ele fosse capaz de se autogovernar, tornar-se senhor de si mesmo e visar o bem social.