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Orientador: Carlile Campos Lavor / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matemática, Estatística e Computação Científica / Made available in DSpace on 2018-08-18T10:25:36Z (GMT). No. of bitstreams: 1 Fidalgo_FelipeDelfiniCaetano_M.pdf: 1387888 bytes, checksum: 10eea772ac455d900f31182f86cad9d0 (MD5) Previous issue date: 2011 / Resumo: Neste trabalho, analisamos dois algoritmos da literatura para o "Molecular Distance Geometry Problem" (MDGP) e propomos um novo algoritmo que mantém a qualidade das soluções obtidas pelos dois anteriores e apresenta ganhos em termos de eficiência computacional. O MDGP consiste em determinar as posições dos átomos de uma molécula, no espaço tridimensional, a partir de um conjunto de distâncias entre eles. Quando todas as distâncias são conhecidas, o problema pode ser resolvido em tempo polinomial. Caso contrário, é um problema NP-difícil / Abstract: In this work, we analyse two algorithms from the bibliography to solve the so-called "Molecular Distance Geometry Problem" (MDGP). Then, we propose a new algorithm that keeps the quality on the solutions obtained by both the previous ones and shows gains regarding computacional efficiency. The MDGP consists on the determination of positions of atoms in a molecule, on the tridimensional space, from a set containing distances among them. When all the distances are known, the problem might be solved in polynomial time. Otherwise, it is an NP-hard problem / Mestrado / Matemática da Computação / Mestre em Matemática Aplicada

<p> The involvement of d orbitals in the coordination of sulphur in three simple sulphur compounds ls Investigated using an ab initio approach. Comparison of minimal and extended basis set results for molecular properties such as dipole moment, molecular geometry, and force constants provides a means of establishing the importance of d orbitals In sulphur compounds and probably other second row compounds. Excited states of sulphur dioxide and ozone are studied in the hope of elucidating the respective spectra on a theoretical basis. These investigations also provide initial data for the parametrization of the semi-empirical CNDO approach for second row atoms. </p> / Thesis / Master of Science (MSc)

Abstract The indirect spin-spin coupling is a molecular internuclear interaction, which is observable by utilizing NMR spectroscopy. This coupling, denoted J, is a second-order tensorial property that consists of rank-0, 1, and 2 components. The present thesis deals with the experimental determination of the rank-0 and rank-2 components of J tensors for different pairs of interacting nuclei by utilizing liquid crystal NMR (LC NMR) method. The experimental information of the rank-2 component of the J tensor appears as Janiso, a combination of tensor elements. In LC NMR, Janiso is manifested as a contribution to the experimental anisotropic coupling (Dexp ) that contains also the corresponding internuclear dipolar coupling, D. The dipolar coupling is defined by the molecular geometry and average orientation, and affected by the molecular motions. Therefore, the molecular geometry and orientation have to be determined together with the studied Janiso couplings. The contributions to D couplings arising from the molecular vibrations and solvent-induced deformation of the molecular geometry are taken into account in the analysis of the experimental data; the contributions are presented briefly in this thesis. The LC NMR experiments are performed for C6H6, HCONH2, C2H2, C2H4, C2H6, 1,4-C6H4F2, CH3F, CH2F2, CHF3, and CSiH6 molecules, and some important aspects of the liquid crystal NMR method are discussed. The obtained information of J tensors is compared with the theoretical ab initio MCSCF results. Finally, the systematics of the J tensors in different structural surroundings is found and the significance of the indirect contribution to the corresponding Dexp coupling is discussed.

The knowledge of physicochemical properties of organic compounds becomes increasingly important. In this study, we developed UPPER (Unified Physical Property Estimation Relationships), a comprehensive model for the estimation of 20 physicochemical properties of organic compounds. UPPER is a system of thermodynamically sound relationships that relate the various phase-transition properties to one another, which includes transition heats, transition entropies, transition temperatures, molar volume, vapor pressure, solubilities and partition coefficients in different solvents and etc. UPPER integrates group contributions with the molecular geometric factors that affect transition entropies. All of the predictions are directly based on molecular structure. As a result, the proposed model provides a simple and accurate prediction of the properties studied. UPPER is designed to predict industrially, environmentally and pharmaceutically relevant physicochemical properties of organic compounds. It also can be an aid for the efficient design and synthesis of compounds with optimal physicochemical properties.

This thesis combines work in the areas of mass spectrometric reaction monitoring and chemical education. In the first part of this thesis, real-time mechanistic analysis using electrospray ionization mass spectrometry is reported. In Chapter 1, an introduction to the mass spectrometric instrumentation and methodologies used in this research is provided. In Chapter 2, the real-time mechanistic analysis of the Hiyama cross-coupling reaction using electrospray ionization mass spectrometry is reported, in particular, the fluoride-mediated rearrangement of phenylfluorosilanes that was found to occur even before catalyst addition. Combining Ph3SiF with a fluoride ion source under typical Hiyama cross-coupling conditions causes rapid formation of the expected [Ph3SiF2]–; however, ESI-MS analysis reveals that phenyl-fluoride exchange occurs concomitantly, also producing substantial quantities of [PhnSiF5–n]– (n = 0-2). The exchange process is verified using 19F NMR spectroscopy. This observation may have implications for Hiyama reaction protocols, which use transmetallation from triaryldifluorosilicates as a key step in cross-coupling. Optimization of the methodology used for real-time analysis by ESI-MS to reduce observed contamination from leaching of rubber septa additives is also discussed. In the second part of this thesis, the development and application of two different approaches for generating molecular models for the teaching molecular geometry and VSEPR theory in first year chemistry is reported. Chapter 4 details a method for the application of handheld 3D printing pens for producing models from ABS plastic. In Chapter 5, the development of laser-cut acrylic model kits is detailed, as well as the design and results of a quantitative study aimed at assessing their effectiveness for improving representational competence and comprehension of molecular geometry. / Graduate

An abstract is not provided. / Thesis / Master of Science (MSc)

This study had as a principal aim, to investigate the use of different technologies in teaching Molecular Geometry and fundamentally, identify if the software ChemSketch® empowers or opposes the elaboration of more adequate models of chemical structures. To subsidize this study, it was needed to appeal to the quality research which resulted in a study of case. The study of the case was the procedure method which was adopted, aiming a 2nd high school class of 28 students, in a private school in the state of Minas Gerais. The students had the opportunity to deal with different situations while being taught chemistry with the use of technologies, and also to assess the aspects related to learning chemistry. The date was collected through questionnaires; recording of audio and video activities and the elaboration of a planning of the chemistry activities which involved the technology of blackboard and chalk, the technology of using isopor Balls and Sticks and the software ChemSketch®. The analyses were made following 2 perspectives: the evolution of the students due to the use of each of the technologies and the observations and registrations made in the learning environments. Regarding the analyses of the questionnaires, and the observations and registrations in the learning environments it was possible to realize that the development of the activities in a balanced way among the technologies supports the learning to students, due to the fact that it built the structures in a more adequate way. Although the software provided a better view of the molecules structures, the students did not come to a satisfactory performance, which suggests that in the use of the computer, the teacher performs a fundamental role. / Este estudo teve como objetivo investigar a utilização de diferentes tecnologias no ensino de Geometria Molecular e, fundamentalmente, identificar se o software ChemSketch® potencia ou desfavorece a elaboração de modelos mais adequados de estruturas químicas. Para subsidiar este trabalho, recorreu-se à pesquisa qualitativa, que se consolidou em um estudo de caso. O estudo de caso foi o método de procedimento adotado, voltado para uma turma de 28 alunos da 2ª série do Ensino Médio, de uma escola particular, do estado de Minas Gerais. Os alunos tiveram oportunidade de vivenciar diferentes situações de ensino de Química, com tecnologias, e também de avaliar sobre seus aspectos relacionados à aprendizagem em Química. Os dados foram coletados por meio de questionários; gravações, em áudio e vídeo das atividades; elaboração de um planejamento das atividades de Química, envolvendo as tecnologias: quadro e giz, bolas de isopor e varetas e o software ChemSketch®. As análises foram feitas segundo duas perspectivas: (i) avaliação dos alunos a respeito da utilização de tais tecnologias e (ii) observações e registros realizados nos ambientes de aprendizagem. A partir dessas análises, é possível perceber que o desenvolvimento das atividades de forma combinada entre tecnologias favorece a aprendizagem para os educandos, visto que, desse modo, eles constroem as estruturas de forma mais adequada. Embora o software proporcionasse uma visualização melhor das estruturas das moléculas, os alunos não obtiveram um desempenho satisfatório, o que sugere que, na utilização do computador, o professor desempenha um papel fundamental. / Mestre em Química

Submitted by Maria Bernadete Dos Santos (mariabpds@id.uff.br) on 2017-10-10T15:24:01Z No. of bitstreams: 3 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação Ana Paula Medeiros.pdf: 1550631 bytes, checksum: c2c0de6ab5e7ff2729db59698506250d (MD5) Produto Ana Paula Medeiros.pdf: 429625 bytes, checksum: 68103f66bcbc45cf18db01326bb82852 (MD5) / Approved for entry into archive by Biblioteca Central do Valonguinho Biblioteca Central do Valonguinho (bcv@ndc.uff.br) on 2017-10-27T19:43:25Z (GMT) No. of bitstreams: 3 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação Ana Paula Medeiros.pdf: 1550631 bytes, checksum: c2c0de6ab5e7ff2729db59698506250d (MD5) Produto Ana Paula Medeiros.pdf: 429625 bytes, checksum: 68103f66bcbc45cf18db01326bb82852 (MD5) / Made available in DSpace on 2017-10-27T19:43:25Z (GMT). No. of bitstreams: 3 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação Ana Paula Medeiros.pdf: 1550631 bytes, checksum: c2c0de6ab5e7ff2729db59698506250d (MD5) Produto Ana Paula Medeiros.pdf: 429625 bytes, checksum: 68103f66bcbc45cf18db01326bb82852 (MD5) / Esse trabalho apresenta uma sequência didática sobre Geometria Molecular, elaborada após análise de uma diagnose aplicada, levando-se em consideração a opinião dos participantes envolvidos nesta pesquisa. Utilizou-se a Teoria Cognitiva de David Ausubel e as Obras de Paulo Freire, para fundamentar a pesquisa. A sequência foi desenvolvida em duas turmas de 1ºsérie do Ensino Médio no município de Belford-Roxo, buscou-se envolver os alunos através de uma pesquisa bibliográfica sobre “A importância e tipos de Geometria Molecular”, assim como a elaboração de modelos com materiais alternativos, juntamente com uma ficha contendo informações sobre a molécula. Para reforçar a construção do conhecimento, foram elaborados e utilizados dois jogos didáticos, um Dominó Geométrico e um Cara-Cara Geométrico. Ambos abordaram o assunto estudado em sala de aula durante o 4º bimestre. Posteriormente ao processo envolvendo o lúdico, os alunos participaram de uma avaliação escrita. Após todo desenvolvimento do processo de ensino-aprendizagem, os discentes responderam a um questionário, onde puderam expor suas opiniões sobre as atividades desenvolvidas, permitindo ao docente analisar o processo ensino- aprendizagem e os benefícios do uso de atividades lúdicas associado a teoria para abordagem do conteúdo de geometria molecular. Após análise e reflexão docente, foi obtido a versão final da sequência didática, envolvendo atividades lúdicas para o processo de ensino-aprendizagem de geometria molecular no Ensino Médio. Configurando-se como produto final dessa Dissertação, podendo contribuir no processo de ensino-aprendizagem de Química à medida que permite a construção do conhecimento em conjunto professor-alunos. / This paper presents a didactic sequence of molecular geometry, drawn up after analysis of an applied diagnosis, taking into account the opinion of the participants involved in this research. We used the Cognitive Theory of David Ausubel and the works of Paulo Freire to support the research.The sequence was developed in two groups of the freshman year of high school in Belford-Roxo city. It was sought to engage students through a literature search about "The importance and types of molecular geometry” as well as the development of models with alternative materials along with a form containing information about the molecule.In the consolidation of knowledge, two educational games were used: a Geometrical Domino and Geometrical Guess Who. Both addressed the subject studied in class during the 4th quarter. As soon as the process involving the recreational activities was finished, students participated in a written assessment.After the whole development of the teaching-learning process, the students answered a questionnaire where they could express their opinions on the activities evolved, allowing the teacher to analyze the teaching-learning process and the benefits of using recreational activities associated with theory to the content of molecular geometry approach.After analysis and teaching reflection, It was obtained the final version of the didactic sequence involving recreational activities for the process of teaching and learning of molecular geometry in high school. Configured as the final productofthiswork, it cancontribute in Chemistryteaching-learningprocess as it allowstheconstructionofknowledge in teacher-studentsinteraction.

Made available in DSpace on 2016-03-15T19:39:52Z (GMT). No. of bitstreams: 1 Jose Ricardo Lemes de Almeida.pdf: 10266228 bytes, checksum: 65b1cb994ef14d0ca73bd5cbfa547e03 (MD5) Previous issue date: 2011-02-07 / One of the difficulties in teaching Chemistry is establishing relationships between representations of the microscopic and the macroscopic levels while exploring a concept. Earlier studies have shown that the use of computer or physical visualization tools result in a more efficient learning of these concepts. It is believed that part of the positive effect is related to training visual-spatial abilities. Based on these studies, this research sought to investigate the impact of an educational intervention on the accomplishments of tasks that measure visual-spatial abilities. A group of 56 students paired by gender was divided randomly into two groups. One of the groups received an educational intervention using a kit for building a tetrahedron; the other group received a list of exercises of molecular geometry. To evaluate the effects of the proposed intervention, students were asked to take part of two mental rotation tests of three dimensional images after each intervention. In one of them, the stimuli were images of molecules, and in the other they were solid three dimensional objects; the images appeared at different rotations on a computer screen. The task was to say the name of the molecules and, in the case of the objects, compare them to other objects that had not been rotated. The tests were applied using equipment that registers eye movements (Tobii® 1750). The analysis was based on response time, right answers, wrong answers, and strategies of eye movement to follow stimuli. The main results showed a larger number of right answers in the group that used the kit, both in the test with images of molecules and in the test of geometric objects. These results lead us to believe that the kit was effective for the visualization of molecules, becoming an important teaching tool in Chemistry. Besides, the effect of the kit in tests of three dimensional objects pointed out to the positive impact that this strategy had on the visual-spatial abilities in general. / Uma das dificuldades encontradas no ensino da Química é o estabelecimento de relações entre representações do nível microscópico e as do macroscópico na exploração de um conceito. Estudos anteriores mostraram que a utilização de ferramentas de visualização computacional ou física resulta em aprendizado mais efetivo de conceitos. Acredita-se que parte do efeito positivo deva estar relacionada a um treinamento de habilidades visoespaciais. Para verificar essa hipótese, um grupo de 56 alunos pareados por gênero foi dividido aleatoriamente em dois grupos. Um dos grupos recebeu intervenção educacional com o kit de montagem física de um tetraedro; o outro recebeu uma lista de exercícios de geometria molecular. Para a avaliação dos efeitos das intervenções propostas, após essas intervenções os alunos realizaram testes de rotação mental de figuras tridimensionais. Em um deles, os estímulos eram figuras de moléculas e, no outro, eram objetos sólidos tridimensionais; as figuras apareciam rotacionadas em uma tela de computador. A tarefa era dizer o nome das moléculas e, no caso dos objetos, compará-los com outros objetos não rotacionados. Os testes foram realizados em equipamento de registro dos movimentos oculares (Tobii® 1750). Foram analisados o tempo de resposta, o número de acertos e erros, e as estratégias visuais de rastreio dos estímulos. Os resultados sinalizaram que o uso do kit foi efetivo para melhor visualização de moléculas, o que o caracterizou como importante ferramenta no ensino-aprendizagem de Química. Além disso, o efeito do kit em testes de figuras tridimensionais apontou para o impacto positivo que esta estratégia teve nas habilidades visoespaciais de forma geral.