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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Remo??o de Chumbo, B?rio e Zinco de um Efluente Aquoso via flota??o por ar disperso / Removal of Lead, Barium and Zinc Aqueous Effluent by dispersed air flotation

Cruz, Samantha Grisol da 02 February 2011 (has links)
Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2016-10-04T12:51:42Z No. of bitstreams: 1 2011 - Samantha Grisol da Cruz.pdf: 738384 bytes, checksum: 51b03e05eacc0b118f5eef0fd1f9c373 (MD5) / Made available in DSpace on 2016-10-04T12:51:42Z (GMT). No. of bitstreams: 1 2011 - Samantha Grisol da Cruz.pdf: 738384 bytes, checksum: 51b03e05eacc0b118f5eef0fd1f9c373 (MD5) Previous issue date: 2011-02-02 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq / Environmental pollution caused by heavy metals from different economic activities, including the oil wells drilling has been one source of soil contamination by lead, barium and zinc. These metals compose substances such as barita and galena, which are used to density control of drilling fluid. The soil remediation frequently uses EDTA (1.0 M) as extractor agent, which generates a large amount of concentrated liquid metals. The metals present in this aqueous solution are present at low concentrations (between 10-7 and 10-4 mols.dm-3), which can?t be removed by traditional methods. Alternatively, flotation treatment is a technique that has a viable capacity to handle large volumes of effluent in relatively small areas and accepts combinations with other techniques such as coagulation. This study aimed to verify the removal efficiency of Pb, Zn and Ba present in a synthesized solution, which simulates the effluent generated by contaminated soil washing, by dispersed air flotation. The experiments were conducted at bench scale and have been investigated the influence of the parameters involved in the process, such as pH, flotation time, column height and bubble size. All the study was done by colloid flotation using ferric chloride as coagulant and sodium dodecyl sulfate as the collector of a stoichiometric ratio of three sodium dodecyl sulfate to one of metal. The results showed that the technique has produced satisfactory results in the removal of lead, barium and zinc reached up to 100% removal of the metal, making it possible to meet criteria and standards for effluent discharge described in the RESOLUTION N?. 357, THE NATIONAL COUNCIL ON THE ENVIRONMENT (CONAMA). / A polui??o ambiental por metais pesados resulta de diferentes atividades econ?micas, entre elas, a perfura??o de po?os de petr?leo tem sido uma das fontes de contamina??o do solo por Chumbo, B?rio e Zinco. Estes metais s?o provenientes de subst?ncias como a barita e a galena que s?o utilizadas para o controle da densidade de fluido de perfura??o. Para remedia??o deste solo ? feito uma lavagem com EDTA (1,0M), de onde ser? gerado um volume de l?quido concentrado dos metais antes presentes no solo. Os metais presentes nesta solu??o aquosa encontram-se em concentra??es reduzidas (entre 10-7 e 10-4 mol.dm-3), o que dificulta resultados satisfat?rios ao utilizar m?todos tradicionais. Como alternativa de tratamento a flota??o ? uma t?cnica que possui uma capacidade vi?vel de tratar grandes volumes de efluentes em ?reas relativamente pequenas e que aceita combina??es com outras t?cnicas, como a coagula??o. O presente trabalho teve por objetivo verificar a efici?ncia de remo??o dos metais Pb, Ba e Zn presentes em uma solu??o sintetizada, que simula o efluente gerado na lavagem do solo contaminado, via flota??o por ar disperso. Os experimentos foram realizados em escala de bancada e nestes foram investigados a influ?ncia dos par?metros envolvidos no processo. Tais como: pH, tempo de flota??o, Altura da coluna e tamanho de bolha. Todo o estudo foi feito por flota??o de col?ides, usando o cloreto f?rrico como agente coagulante e o dodecil sulfato de s?dio como coletor a uma raz?o estequiom?trica de tr?s de dodecil sulfato de s?dio para um de metal. Os resultados obtidos mostraram que a t?cnica produziu resultados satisfat?rios na remo??o de chumbo, b?rio e zinco atingido at? 100% de remo??o do metal, sendo assim poss?vel atender aos crit?rios e padr?es de lan?amento de efluentes descritos na RESOLU??O NO. 357, DO CONSELHO NACIONAL DO MEIO AMBIENTE (CONAMA).
22

Estudo da forma??o dos complexos coacervados obtidos a partir de prote?nas globulares / Study of formation of complex coacervates obtained from globular proteins.

Santos, Monique Barreto 29 February 2016 (has links)
Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2016-10-17T10:53:24Z No. of bitstreams: 1 2016 - Monique Barreto Santos.pdf: 2356049 bytes, checksum: 8a379b47682a5e067746503ee59b6d27 (MD5) / Made available in DSpace on 2016-10-17T10:53:24Z (GMT). No. of bitstreams: 1 2016 - Monique Barreto Santos.pdf: 2356049 bytes, checksum: 8a379b47682a5e067746503ee59b6d27 (MD5) Previous issue date: 2016-02-29 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq / Proteins are biopolymers of high nutritional and functional significance has been widely used as food ingredients. The interaction between two different proteins oppositely charged, and can give rise to complex coacervate currently used as an ingredient in food technology or as a microencapsulating agent. The formation of complex coacervates between Lysozyme and Ovalbumin and between Bovine serum albumin (BSA) and Lysozyme has been investigated as a function of pH, mass ratio of total and concentration of NaCl. For both interactions studied, complexing latched in a wide pH range which corresponds to the interval between the pI of proteins. Among Ovalbumin and Lysozyme interaction was more intense in the ratio r = 1 at pH 7.5 and BSA and Lysozyme most complex formation has occurred on the ratio r = 0.5 and pH 9.0. Changes in the ionic strength by adding NaCl negatively affected the interaction between Lysozyme and BSA already at a concentration of 0.01 mol / L and 0.03 mol / L abolished the interaction between Lysozyme and Ovalbumin. Through Potential - zeta can be seen that the formation of insoluble complexes was highest near the pI for all studied reasons, indicating that the interaction is given by neutralization of opposite charges. The Infrared spectra suggested that electrostatic interactions led interactions however, hydrogen bonds also had a hand in the coacervation process for the proteins under study. The micrographs showed that the insoluble complexes showed spherical structure and particle size showed the formation of structures with an average size around 2 ?m, much larger than the observable size for the isolated proteins. The isothermal titration calorimetry showed that the interaction between Lysozyme and Ovalbumin was exothermic and was performed in two steps, the first and second entropy directed enthalpy driven. The differential scanning calorimetry suggested the presence of a single point of denaturation, that the interaction between Lysozyme and BSA led to a new biopolymer with denaturation temperature 67 ? C differs from isolated proteins. These studies suggested that complex coacervates formed between Ovalbumin / Lysozyme and BSA / Lysozyme could be used as the encapsulating bioactive agent or as food ingredients in order to add nutritional value. / Prote?nas s?o biopol?meros de grande import?ncia nutricional e funcional tendo sido amplamente utilizadas como ingredientes alimentares. A intera??o entre duas prote?nas diferentes e opostamente carregadas pode dar origem aos complexo coacervado, atualmente utilizados como ingrediente na tecnologia de alimentos ou como agente de microencapsula??o. A forma??o de complexos coacervados entre Ovalbumina e Lisozima e entre Albumina s?rica bovina (BSA) e Lisozima foi investigada em fun??o do pH, raz?o de massa total e concentra??o de NaCl. Para as duas intera??es estudadas, a complexa??o acorreu em uma ampla faixa de pH, que corresponde ao intervalo entre os pI das prote?nas. Entre Ovalbumina e Lisozima a intera??o foi mais intensa na raz?o r=1 em pH 7,5 e para BSA e Lisozima a maior forma??o de complexos ocorreu na raz?o r=0,5 e pH 9,0. Altera??es na for?a i?nica por adi??o de NaCl influenciaram negativamente a intera??o entre Albumina BSA e Lisozima j? na concentra??o de 0,01 mol/L e a 0,03 mol/L suprimiu a intera??o entre Ovalbumina e Lisozima. Por meio do Potencial - zeta pode-se verificar que a forma??o de complexos insol?veis foi m?xima pr?ximo ao pI para todas as raz?es estudadas, indicando que a intera??o se deu por neutraliza??o de cargas opostas. Os espectros no infravermelho sugeriram que intera??es eletrost?ticas conduziram as intera??es no entanto, liga??es de hidrog?nio tamb?m tiveram participa??o no processo de coacerva??o para as prote?nas em estudo. As micrografias revelaram que os complexos insol?veis apresentavam estrutura esf?rica e o tamanho de part?cula demonstrou a forma??o de estruturas com tamanho m?dio em torno de 2 ?m, as quais s?o bem maiores do que o tamanho obervado para as prote?nas isoladas. A calorimetria de titula??o isot?rmica demonstrou que a intera??o entre Ovalbumina e Lisozima foi exot?rmica, a qual ocorreu em duas etapas, a primeira entropicamente dirigida e a segunda entalpicamente dirigida. A calorimetria diferencial de varredura sugeriu, pela presen?a de um ?nico ponto de desnatura??o, que a intera??o entre BSA e Lisozima deu origem a um novo biopol?mero com temperatura de desnatura??o a 67?C, diferente das prote?nas isoladas. Estes estudos sugeriram que complexos coacervados formados entre Ovalbumina / Lisozima e BSA / Lisozima poderiam ser utilizados como agente encapsulante de bioativos ou como ingredientes alimentares com o objetivo de agregar valor nutricional.
23

Produtividade prim?ria bruta na Amaz?nia legal:rela??o com vari?veis meteorol?gicas e valida??o do produto mod17A2 / Gross primary productivity in Amazonia: relationship with meteorological variables and validation mod17A2 product

Almeida, Catherine Torres de 17 February 2016 (has links)
Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2016-10-18T10:23:51Z No. of bitstreams: 1 2016 - Catherine Torres de Almeida.pdf: 4011870 bytes, checksum: 95ec0ec572d24a8a7285ec3bb17fac37 (MD5) / Made available in DSpace on 2016-10-18T10:23:51Z (GMT). No. of bitstreams: 1 2016 - Catherine Torres de Almeida.pdf: 4011870 bytes, checksum: 95ec0ec572d24a8a7285ec3bb17fac37 (MD5) Previous issue date: 2016-02-17 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / The Gross Primary Productivity (GPP) is the rate at the atmospheric CO2 is converted by photosynthetic activity in organic substances and is a measure of the total carbon fixed by the ecosystem. In the context of climate change, the focus for the fixation of carbon by forest ecosystems is the basis to mitigate emissions of anthropogenic CO2. There are several methods for the quantification of carbon stored in the vegetation, using data obtained by micrometeorological towers or by remote sensing. Among these methods, stands out the eddy covariance technique, that is much used to quantify the CO2 flux in many forest ecosystems. However, this technique has a high cost, limited operation and covers a small extent. Accordingly, the methods that employ remote sensing have the advantage of providing terrestrial primary productivity estimates for large areas where the methods at the field level are not feasible. This work has as main objective to evaluate the dynamics of the GPP in the Brazilian Legal Amazon over land use and land cover and weather variables. For understanding the relationship of the eddy covariance GPP with meteorological data, rainfall data from TRMM 3B43 product and environmental variables of flux towers were used. Data from TRMM satellite were validated with data from seven conventional weather stations of Amazonas state. The comparison was based on the Average Error (AE), Root Mean Square Error (RMSE), linear correlation coefficient (r) and Wilmott agreement index (d). We also used the Spearman correlation coefficient and a regression tree model to assess the relationship between flux tower GPP and environmental variables. To evaluate GPP estimates from two versions of the MOD17A2 product, derived from MODIS sensor data, these have been validated with surface data from seven LBA flux towers, of which four are in forest cover, one in transition forest and two in disturbed areas. The statistical analyzes were performed with R software, version 3.1.0. The results of the validation of TRMM 3B43 were positive, with high linear correlation (r = 0.83), high level of agreement (d = 0.85) and an adequate RMSE (59.77 mm), showing that this product can be used as an alternative source of quality data. Regarding the influence of the land use and land cover in GPP, it was found that the disturbed areas had lower productivity compared to the conserved areas and had their water balance affected, presenting higher values of the Bowen ratio. The GPP seasonality was predominantly related to radiation at the top of the atmosphere in forest areas of the equatorial Amazon. In areas more distant of the Ecuador, the GPP was influenced by radiation at the top of the atmosphere and also by rainfall and VPD, indicating limitation both by radiation and by water availability. MOD17A2 had no satisfactory agreement between in estimating GPP compared to the method of eddy covariance, underestimating productivity for most locations studied. The seasonality derived from the MODIS algorithm was only similar to the seasonality of GPP by eddy covariance method for non-equatorial locations. The areas in Equatorial Amazon exhibit distinct MOD17A2 GPP seasonal pattern of that verified by data from the micrometeorological towers. Given this, it is necessary to improve the MOD17A2 algorithm to enable it to estimate GPP depending on the different vegetation responses to drought and radiation. This improved understanding may help to produce better estimates of GPP in Amazon and the use of remote sensing in conjunction with the surface data can contribute to generate an overview of GPP in this biome. / A Produtividade Prim?ria Bruta (PPB) ? a taxa na qual o CO2 atmosf?rico ? convertido pela atividade fotossint?tica em subst?ncias org?nicas e ? uma medida do total de carbono fixado pelo ecossistema. No contexto das mudan?as clim?ticas, o enfoque para a fixa??o de carbono pelos ecossistemas florestais ? a base para mitigar as emiss?es de CO2 antropog?nico. Existem diversos m?todos destinados ? quantifica??o do carbono estocado na vegeta??o, que utilizam dados obtidos por meio de torres micrometeorol?gicas de fluxo ou atrav?s de sensoriamento remoto. Dentre esses m?todos, se destaca a t?cnica de covari?ncia de v?rtices turbulentos, por ser muito empregada para quantificar o fluxo de CO2 em diversos ecossistemas florestais. Por?m, esta t?cnica possui um custo alto, operacionalidade restrita e abrange uma pequena extens?o. Nesse sentido, os m?todos que empregam o sensoriamento remoto t?m a vantagem de fornecer estimativas de produtividade prim?ria terrestre para grandes ?reas, onde os m?todos ao n?vel do terreno n?o s?o vi?veis. Este trabalho tem como objetivo geral avaliar a din?mica da PPB na Amaz?nia Legal brasileira em rela??o ao uso e cobertura do solo e ?s vari?veis meteorol?gicas. Para compreender a rela??o da PPB obtida pelo m?todo de covari?ncia de v?rtices turbulentos com dados meteorol?gicos, foram utilizados dados de chuva do produto 3B43 do sat?lite TRMM e vari?veis ambientais das torres de fluxo. Os dados do sat?lite TRMM foram validados com dados de sete esta??es meteorol?gicas convencionais do estado do Amazonas. A compara??o foi baseada no Erro M?dio (EM), Raiz do Erro M?dio Quadr?tico (REMQ), coeficiente de correla??o linear (r) e ?ndice de concord?ncia de Wilmott (d). Tamb?m utilizou-se o coeficiente de correla??o de Spearman e um modelo de ?rvore de regress?o para avaliar a rela??o entre a PPB da torre de fluxo e as vari?veis ambientais. Para avaliar as estimativas de PPB de duas vers?es do produto MOD17A2, derivadas de dados do sensor MODIS, estas foram validadas com dados de superf?cie de sete torres de fluxo do Projeto LBA, das quais quatro se encontram em cobertura florestal, uma em floresta de transi??o e duas em ?reas antropizadas. As an?lises estat?sticas foram realizadas no software R, vers?o 3.1.0. Os resultados da valida??o do produto 3B43 do TRMM foram positivos, com alta correla??o linear (r = 0,83), alto ?ndice de concord?ncia (d = 0,85) e REMQ satisfat?rio (59,77 mm), mostrando que este produto pode ser utilizado como uma fonte alternativa de dados de qualidade. Em rela??o ? influ?ncia do uso e da cobertura do solo na PPB, verificou-se que as ?reas antropizadas apresentaram menor produtividade em rela??o ?s ?reas conservadas e tiveram seu balan?o h?drico afetado, pois apresentaram altos valores da raz?o de Bowen. A sazonalidade da PPB foi predominantemente relacionada ? radia??o no topo da atmosfera nas ?reas de floresta da Amaz?nia equatorial. Nas ?reas mais distantes do Equador, a PPB foi influenciada pela radia??o no topo da atmosfera e tamb?m pela chuva e VPD, indicando limita??o tanto pela radia??o quanto pela disponibilidade de ?gua. O MOD17A2 n?o apresentou boa estimativa de PPB comparado ao m?todo de v?rtices turbulentos, subestimando a produtividade para a maioria das localidades estudadas. A sazonalidade da PPB deste algoritmo somente foi similar ? sazonalidade da PPB pelo m?todo de v?rtices turbulentos para as localidades n?o-equatoriais. As ?reas na Amaz?nia Equatorial apresentaram padr?o sazonal da PPB do MOD17A2 distinto do verificado pelos dados das torres micrometeorol?gicas. Diante disto, ? necess?rio melhorar o algoritmo MOD17A2 para que este possa estimar PPB em fun??o das diferentes respostas da vegeta??o ? seca e ? radia??o. Esse melhor entendimento poder? contribuir para produzir melhores estimativas da PPB para a Amaz?nia e o uso do sensoriamento remoto em conjunto com os dados de superf?cie pode contribuir para gerar uma vis?o geral da PPB nesse bioma.
24

Estudo da degrada??o de misturas polim?ricas ? base de PEBD, amido, quitosana e fibra de coco em diferentes ambientes aquosos / Study of the Degradation of polymer mixtures based on LDPE , starch, chitosan and coconut fiber in different aqueous environments

Azevedo, Laryssa Cristina Medina 23 January 2016 (has links)
Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2016-10-19T15:59:43Z No. of bitstreams: 1 2016 - Laryssa Cristina Medina Azevedo.pdf: 3869837 bytes, checksum: 508d4054394209403e14c50fc5d2bc4b (MD5) / Made available in DSpace on 2016-10-19T15:59:43Z (GMT). No. of bitstreams: 1 2016 - Laryssa Cristina Medina Azevedo.pdf: 3869837 bytes, checksum: 508d4054394209403e14c50fc5d2bc4b (MD5) Previous issue date: 2016-01-23 / Water quality is related to the anthropogenic impact on water resources and their availability, and this quality is regulated by the National Environmental Council - CONAMA, through resolutions 357 of 2005 and 396 of 2008, from the boundaries quality standards of water bodies. The materials of organic origin, including natural polymers have an inherent tendency to degradation. The presence of oxidizable or hydrolysable groups in the chains of these polymers, in addition to hydrophobicity and hydrophilicity characteristics and degree of conformational flexibility of the chain are factors that contribute to the biodegradation of the polymer. Water pollution by hydrocarbons, including biodegradable polymers, can be an environment conducive to the presence of potentially degrading microorganisms from a variety of recalcitrant molecules released in the middle. The combination of different types of environmental effects can cause slow or fast decay, which depends on the predominant factor or degrading agent (photochemical, thermal, chemical, hydrolysis, oxidation, biodegradation). This work was carried out an investigation into the quality of water facilities (river water - RW distilled water - DW and water with nutrients - NW) after the biodegradation of polymeric blends and composites containing low density polyethylene (LDPE), thermoplastic starch (TPS), chitosan (Ch) Coconut fiber (CF). The samples were subjected to biodegradation test water in these media for a period of fifty-two days. After the test period may be seen that mixtures of TPS/Ch and TPS/CF undergone the process of biodegradation, confirmed the almost complete loss of their mass, increased conductivity, in spite of the turbidity values and the consumed oxygen concentration, decrease in the last days of rehearsal. As expected mixtures containing LDPE (LDPE/TPS, LDPE/TPS/Ch and LDPE/TPS/CF) showed less weight loss, and lower turbidity and O2 consumption in the chemical degradation of organic matter. Comparing the results of different means water, as expected, the results conductivity and pH of the river water (RW) were higher than the values found for the water with nutrients (NW) and distilled water (DW). The turbidity values and concentration of O2 consumed in the COD for the different blends containing LDPE as shown depended on the diffusion of water in the various polymeric materials and consequently influence the first stage of biodegradation, i.e., water penetration into the material surface attack of the chemical bonds of the amorphous phase and converting long chain of biodegradable polymers into smaller pieces and eventually into soluble fragments / A qualidade da ?gua est? relacionada com o impacto antropog?nico sobre os recursos h?dricos e sua disponibilidade, e essa qualidade ? regulamentada pelo Conselho Nacional do Meio Ambiente ? CONAMA, atrav?s das resolu??es 357 de 2005 e 396 de 2008, a partir do quadro dos limites dos padr?es de qualidade dos corpos h?dricos. Os materiais de origem org?nica, incluindo pol?meros naturais t?m uma tend?ncia inerente para degrada??o. A presen?a de grupos oxid?veis ou hidrolis?veis nas cadeias desses pol?meros, al?m das caracter?sticas de hidrofilicidade e hidrofobicidade e o grau de flexibilidade conformacional da cadeia s?o fatores que contribuem para a biodegrada??o do pol?mero. A polui??o das ?guas por hidrocarbonetos, incluindo pol?meros biodegrad?veis, pode ser um ambiente prop?cio ? presen?a de microrganismos potencialmente degradadores de uma variedade de mol?culas recalcitrantes liberadas no meio. A combina??o de diferentes tipos de efeitos ambientais pode causar deteriora??o r?pida ou lenta, a qual depende do fator predominante ou do agente degradante (fotoqu?mica, t?rmica, qu?mica, hidr?lise, oxida??o, biodegrada??o). Neste trabalho foi realizada uma investiga??o da qualidade de meios h?dricos (?gua de rio ? AR, ?gua destilada ? AD e ?gua com nutrientes ? AN) ap?s o ensaio de biodegrada??o de blendas e comp?sitos polim?ricos contendo polietileno de baixa densidade (PEBD), amido termopl?stico (TPS), quitosana (Q) e fibra de coco (FC). As amostras foram submetidas ao ensaio de biodegrada??o nestes meios h?dricos pelo per?odo de cinquenta e dois dias. Ap?s o per?odo de ensaio pode-se verificar que as misturas de TPS/Q e TPS/FC sofreram o processo de biodegrada??o, confirmado pela quase total perda de suas massas, aumento da condutividade, apesar dos valores de turbidez e da concentra??o de oxig?nio consumido, diminu?rem nos ?ltimos dias de ensaio. Como esperado as misturas contendo PEBD (PEBD/TPS, PEBD/TPS/Q e PEBD/TPS/FC) apresentaram menor perda de massa, al?m de menor turbidez e consumo de O2 na degrada??o qu?mica da mat?ria org?nica. Comparando os resultados dos diferentes meios h?dricos, como j? era esperado, os resultados valores de condutividade e pH da ?gua de rio (AR) foram maiores do que os valores encontrados para a ?gua com nutrientes (AN) e ?gua destilada (AD). Os valores de turbidez e DQO, para as diferentes misturas contendo PEBD, como mostrado, dependeram da difus?o da ?gua nos diferentes materiais polim?ricos e consequentemente influenciaram na primeira fase da biodegrada??o, isto ?, penetra??o da ?gua na superf?cie do material, ataque das liga??es qu?micas da fase amorfa e convers?o das longas cadeias doe pol?meros biodegrad?veis em partes menores, e, eventualmente, em fragmentos sol?veis
25

O uso de programas computacionais e materiais manipul?veis no processo de ensino e aprendizagem da geometria plana e espacial de alunos do ensino t?cnico em Agropecu?ria do Col?gio Agr?cola de Floriano ? PI / The use of computer programs and manipulatives in the teaching and learning of plane geometry and spatial students of technical education in the College of Agriculture Agricultural Floriano - PI

Santos, Ricardo de Castro Ribeiro 28 November 2011 (has links)
Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2016-10-21T10:07:56Z No. of bitstreams: 1 2011 - Ricardo de Castro Ribeiro Santos.pdf: 16661166 bytes, checksum: 3e9cbd7372714129f6015ce926f4eaf5 (MD5) / Made available in DSpace on 2016-10-21T10:07:56Z (GMT). No. of bitstreams: 1 2011 - Ricardo de Castro Ribeiro Santos.pdf: 16661166 bytes, checksum: 3e9cbd7372714129f6015ce926f4eaf5 (MD5) Previous issue date: 2011-11-28 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / The present work aims to verify whether or not the change in the level of learning geometry of the thirty-seven students of the third year of Technical Education in Agriculture Concurrent with high school (EMTA-3), enrolled in 2009, after use software as a tool of Cabri Geometry II Plus, 3D calques and Poly, and the use of geometric solids used in the production process of the agribusiness in the CAF - Floriano Agricultural College. The choice of subject Geometry, from the content associated with the menu in Agribusiness, was motivated by the difficulties that students of different levels, present in the subject, with the proposal to deploy a new way of working that will serve as a model to only theoretical classes. Thus, in Agribusiness are many ways that space can be analyzed mathematically. However, it is the following questions: How can we do this? Use of the software will provide some benefit in this context? Can the student understand the relationship between high school and technical education? To answer these questions the students were subjected to six steps, including: Step 1: application of a test at time zero (t0), Step 2: twelve lectures, 3rd and 5th steps: twenty-two classes in computer lab , Step 4: Meeting in agribusiness (all morning) and Step 6: application of a test in a time (t1). After application of the test t0 observed that more than half of the subjects had lower scores than the 50%, whereas the t1 test, applied after the intervention methodology, this figure exceeded for more than half of the subjects, 50%. With this, we realize that the end of the project, students were more motivated about teaching mathematics, associating it with the use of software and awakening to the contextualization and interdisciplinarity, and the interconnection of technical education in high school will be stronger regarding the participation of the student, making focus the importance of mathematics in everyday life. It was concluded that the analysis of planar and spatial forms by the students became more consistent, showing that the use of solid and software proved to be an effective tool in the process of teaching and learning of geometry, enabling the interconnection of different areas / O presente trabalho tem por objetivo verificar a mudan?a ou n?o do n?vel de aprendizado de geometria dos trinta e sete alunos do terceiro ano do Ensino T?cnico em Agropecu?ria Concomitante com o Ensino M?dio (EMTA-3), matriculados no ano de 2009, ap?s o uso como ferramenta dos softwares Cabri Geometry II Plus, Calques 3D e Poly, bem como o uso dos S?lidos Geom?tricos usados no processo de produ??o da agroind?stria no CAF ? Col?gio Agr?cola de Floriano. A escolha do tema Geometria, dentre os conte?dos associados ? ementa na Agroind?stria, foi motivada pela constata??o das dificuldades que os alunos, de diferentes n?veis, apresentam em rela??o ao assunto, com a proposta de implantar um novo m?todo de trabalho que servir? como modelo ?s aulas apenas te?ricas. Dessa forma, na Agroind?stria encontram-se v?rias formas espaciais que podem ser analisadas matematicamente. Contudo, faz-se os seguintes questionamentos: De que forma podemos fazer isso? O uso de softwares ir? apresentar algum benef?cio dentro deste contexto? Poder? o aluno compreender a rela??o entre o Ensino M?dio e o Ensino T?cnico? Para responder a estas perguntas os alunos foram submetidos a seis etapas, dentre elas: 1? etapa: aplica??o de um teste no tempo zero (t0), 2? etapa: doze aulas expositivas, 3? e 5? etapas: vinte e duas aulas no laborat?rio de inform?tica, 4? etapa: encontro na agroind?stria (manh? toda) e 6? etapa: aplica??o de um teste no tempo um (t1). Ap?s a aplica??o do teste t0 observou-se que mais da metade dos sujeitos da pesquisa apresentaram ?ndice de acertos inferior a 50%; j? no teste t1, aplicado ap?s as interven??es metodol?gicas, esse ?ndice ultrapassou, para mais da metade dos sujeitos, os 50%. Com isso, percebemos que ao final do projeto, os alunos se mostraram mais motivados quanto ao ensino da matem?tica, associando-a ao uso de softwares e despertando para a contextualiza??o e a interdisciplinaridade, assim a interliga??o do ensino t?cnico com o ensino m?dio ficar? mais s?lida em rela??o ? participa??o do aluno, fazendo com que enfoque a import?ncia da matem?tica no cotidiano. P?de-se concluir que a an?lise das formas planas e espaciais por parte dos alunos se tornou mais consistente, comprovando que o uso de s?lidos e softwares se mostrou com uma ferramenta eficaz no processo de ensino aprendizagem da geometria, possibilitando a interliga??o das diversas ?reas.
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Estudo de misturas de cereais integrais processadas por extrus?o termoplastica / Study of whole grain mixes processed by extrusion thermoplastic

Toledo, Vanessa Coelho da Silva 15 April 2015 (has links)
Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2017-01-06T10:45:53Z No. of bitstreams: 1 2015 - Vanessa Coelho da Silva Toledo.pdf: 4854286 bytes, checksum: 0bbdd5bc8b7aac66121fe8a0873e3abc (MD5) / Made available in DSpace on 2017-01-06T10:45:53Z (GMT). No. of bitstreams: 1 2015 - Vanessa Coelho da Silva Toledo.pdf: 4854286 bytes, checksum: 0bbdd5bc8b7aac66121fe8a0873e3abc (MD5) Previous issue date: 2015-04-15 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / The extrusion technology enables energy-efficient, with minimal waste and continuously, the processing of cereals. This technology has been used to generate low nutritional and caloric value products, low in dietary fiber, high fat and sugars. The use of raw materials based on whole grain rice, maize and sorghum for the production of products ready for consumption, besides being an excellent source of fiber, it is a good alternative for patients celiac and / or gluten restriction. The objective of this work was to study the effect of the mixture of whole grains (rice, maize and sorghum), submitted to the thermoplastic extrusion process. These mixtures were processed on a single screw lab extruder in the following conditions, which were held constant: Moisture mixtures of 14%, screw rotational speed of 200 rpm, tempera-ture of the heating zones of the extruder (feeding zone until the output of the matrix): 1st Zone - 50 ? C, 2nd - and 3rd 100 - 130, the vertical feeder screw rotation of 15 rpm at (-5 kg / hr). As experimental design, various fractions of whole grain flours were used (corn, rice, sor-ghum). Treatment 1 (T1) consisted of 70% corn; 15% rice, and 15% sorghum; T2: (15%; 70%; 15%); T3: (15%; 15%; 70%); T4: (42.5%; 42.5%; 15%); T5: (42.5%; 15%; 42.5%); T6: (15%; 42.5%; 42.5%); T10: (33.3%; 33.3%; 33.3%); T7 and T10 central points. The whole grain flour for each of the cereals were analyzed for their proximate composition and particle size distribution. The response variables during the extrusion process were: feed rate of mix-tures and specific mechanical energy (EME); bulk density; Expansion indices (radial, longitu-dinal and volume); characterization by images; instrumental texture; paste viscosity; absorp-tion index (WAI) and water solubility (ISA). Variations between treatments were mainly at-tributed to their composition, in particular the dietary fiber content of each sample. It was ob-served that increasing fiber content in the mixture led to the reduction in radial expansion of extruded, as expected. Mixtures with more brown rice content (T2 and T4 treatments) were those who had higher radial expansion, which was attributed to lower this fiber content in rice flour, as expected. The best result was shown EME the treatment with higher corn meal con-tent and sorghum (T5). The instrumental texture analysis also highlighted the crispness (high-er Nsr) treatments more rice portion (T2 and T4). Treatment with higher fraction of corn (T1), achieved the highest paste viscosity. But the T2 treatment, also pointed to present low value for ISA. The treatment of central point (T8) has the greatest value. It could be obtained from mixtures of T2 and T4, more crispness product, expansion and better distribution of the inter-nal air cells; It is therefore recommended treatment for producing extruded. / A tecnologia de extrus?o permite com efici?ncia energ?tica, com m?nima de res?duos e, de forma cont?nua, o processamento de cereais. Este tecnologia tem sido usada para gerar produtos de baixo valor nutricional e cal?ricos, com baixo teor de fibra alimentar, altos teores de gorduras e a??cares. A utiliza??o de mat?rias primas ? base de gr?os integrais de arroz, milho e sorgo, para a elabora??o de produtos para pronto consumo, al?m de ser excelente fonte de fibras, se faz uma boa alternativa para doentes cel?acos e/ou com restri??o a gl?ten. O objetivo deste trabalho foi estudar o efeito da mistura dos cereais integrais (arroz, milho e sorgo), submetidos ao processo de extrus?o termopl?stica. Tais misturas foram processadas em um extrusor de laborat?rio de rosca simples nas seguintes condi??es, as quais foram mantidas constantes: umidade das misturas a 14%, velocidade de rota??o do parafuso a 200 rpm, temperatura das zonas de aquecimento do extrusor (da zona de alimenta??o at? a sa?da da matriz): 1? zona ? 50?C, 2? - 100 e 3? - 130, alimentador vertical helicoidal na rota??o de 15 rpm (~5 kg/h). Como delineamento experimental, foram utilizadas fra??es variadas das farinhas dos cereais integrais (milho, arroz, sorgo). O Tratamento 1 (T1) foi composto de 70% de milho; 15% de arroz e 15% de sorgo; T2: (15%; 70%; 15%); T3: (15%; 15%; 70%); T4: (42,5%; 42,5%; 15%); T5: (42,5%; 15%; 42,5%); T6: (15%; 42,5%; 42,5%); T10: (33,3%; 33,3%; 33,3%); sendo T7 a T10 pontos centrais. As farinhas integrais de cada um dos cereais foram analisadas quanto a sua composi??o centesimal e distribui??o granulom?trica. As vari?veis respostas durante o processamento de extrus?o foram: vaz?o de alimenta??o das misturas e energia mec?nica espec?fica (EME); densidade aparente; ?ndices de expans?o (radial, longitudinal e volum?trico); caracteriza??o por imagens; textura instrumental; viscosidade de pasta; ?ndices de absor??o (IAA) e solubilidade em ?gua (ISA). As varia??es entre os tratamentos foram principalmente atribu?das ? composi??o centesimal, em particular, o teor de fibra alimentar de cada amostra. Observou-se que o aumento do teor de fibra na mistura, levou ? redu??o da expans?o radial dos extrudados, como esperado. As misturas com maior teor de arroz integral (Tratamentos T2 e T4) foram aquelas que apresentaram maior expans?o radial, o que foi atribu?do ao menor teor de fibra presente na farinha de arroz, como esperado. O maior resultado de EME foi evidenciado no tratamento com maior teor de farinha de milho e de sorgo (T5). A an?lise de textura instrumental tamb?m destacou a croc?ncia (maior Nsr) dos tratamentos com maior por??o de arroz (T2 e T4). O tratamento com maior fra??o de milho (T1), alcan?ou a maior viscosidade de pasta. J? o tratamento T2, se destacou tamb?m por apresentar baixo valor para ISA. O tratamento do ponto central (T8) foi o de maior valor. Foi poss?vel obter a partir das misturas dos tratamentos T2 e T4, produtos de maior croc?ncia, expans?o e melhor distribui??o interna das c?lulas ar; sendo, portanto, os tratamentos recomendados para produ??o de extrudados.
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O uso do geoGebra como ferramenta auxiliar na compreens?o de resultados de geometria pouco explorados no ensino b?sico / The use of geoGebra as auxiliary tool in understanding results of geometry underexplored in basic school

Ferreira, Cassio Marins 28 August 2015 (has links)
Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2017-01-25T10:55:06Z No. of bitstreams: 1 2015 - Cassio Marins Ferreira.pdf: 2336646 bytes, checksum: ec3b1734c73a206999579144e063ab1f (MD5) / Made available in DSpace on 2017-01-25T10:55:06Z (GMT). No. of bitstreams: 1 2015 - Cassio Marins Ferreira.pdf: 2336646 bytes, checksum: ec3b1734c73a206999579144e063ab1f (MD5) Previous issue date: 2015-08-28 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / This work intends to present the Dynamic Geometry software GeoGebra to elementary school students. It uses the GeoGebra as a tool for building a step by step procedure to convince students of the veracity of results that have simple statements, but not trivial proofs. The following theorems were worked: Morley's Theorem, Hipparchus Theorem, Stewart's Theorem, Menelaus Theorem and 9-Point Circle Theorem. Demonstrations are held strictly in the traditional way, and in parallel it is used the GeoGebra software, thus giving a playful view of the statements. It is understood that this approach will be more attractive, enabling a better understanding of the theorems by students. The work culminates with the application of a motivational test to a class of basic education after a class in which they worked the 9-Point Circle using GeoGebra / Este trabalho tem a inten??o de apresentar o softwarede Geometria Din?micaGeoGebra ao aluno do Ensino B?sico. Utiliza-se o GeoGebra como ferramenta para a constru??o din?mica de um passo-a-passo para convencer os alunos da veracidade de resultados que possuem enunciados simples, mas demonstra??es n?o triviais. Foram trabalhados os seguintes teoremas: Teorema de Morley, Teorema de Hiparco, Teorema de Stewart, Teorema de Menelau e Teorema do C?rculo de 9 Pontos. As demonstra??es s?o realizadas rigorosamente, da forma tradicional, e em paralelo ? feito o uso do softwareGeoGebra, dando assim uma vis?o l?dica das demonstra??es. Entende-se que esta abordagem ser? mais atrativa, possibilitando uma melhor compreens?o dos teoremas pelos alunos. O trabalho culmina com a aplica??o de um teste motivacional a uma turma do Ensino B?sico ap?s uma aula em que se trabalhou o Teorema do C?rculo dos 9 Pontos utilizando-se o GeoGebra
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Complexos de Copper II com ligantes derivados de tiazol e tioimidazol: s?ntese e avalia??o da atividade citot?xica / Complexes of Copper II with binders derived from thiazole and thioimidazole: synthesis and evaluation of cytotoxic activity

Hottes, Emanoel 07 April 2016 (has links)
Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2017-03-17T12:18:44Z No. of bitstreams: 1 2016 - Emanoel Hottes.pdf: 4033048 bytes, checksum: fe0f804a0e5a67c894370834c0964ff8 (MD5) / Made available in DSpace on 2017-03-17T12:18:44Z (GMT). No. of bitstreams: 1 2016 - Emanoel Hottes.pdf: 4033048 bytes, checksum: fe0f804a0e5a67c894370834c0964ff8 (MD5) Previous issue date: 2016-04-07 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq / CuII complexes containing thiazole and thioimidazole derivatives have been synthesized and characterized. The ligands (E)-2-(2-benzylidenehydrazinyl)-4-phenylthiazole (L1), (E)-2-(2-(4-chlorobenzylidene)hydrazinyl)-4-phenylthiazole (L2), (E)-2-(2-(4-methoxybenzylidene)hydrazinyl)-4-phenylthiazole (L3), (E)-4-phenyl-2-(2-(pyridin-2-ylmethylene)hydrazinyl)thiazole (L4), (E)-5-phenyl-1-(pyridin-2-ylmethyleneamino)-1H-imidazole-2(3H)-thione (L5) and (E)-1-(2-hydroxybenzylideneamino)-5-phenyl-1H-imidazole-2(3H)-thione (L6), reported in the literature, have been obtained in collaboration with Laboratory LaDMol-QM from UFRRJ. For these ligands, it is been performed qualitative calculations and molecular modeling by the semi empiric method PM6 for geometry optimization and estimate the relative energies of the frontier orbitals and conformers. The crystalline structure of the ligand L2 was determined by X-ray diffraction analysis. The CuII complexes have been obtained from the reactions of the ligands with CuCl2 in different stoichiometries. The proposed structures of the complexes have been formulated based on elemental analysis of CHN, electronic paramagnetic resonance (EPR) and electronic (UV-Vis) and vibrational (FTIR) spectroscopy. The results of EPR point to the occurrence of more than one CuII nucleus in all reaction products. For complexes CuL1-CuL3 with potentially bidentate ligands it has been proposed coordination from sulfur or nitrogen from thiazole ring and nitrogen from azomethine, with possible octahedral and/or square planar geometries. For CuL4-CuL6 with potentially tridentate ligands it is been proposed coordination from sulfur as well as nitrogen atoms. For CuL6, there is also a possibility of coordination through the oxygen atom, with a CuII possibly pentacoordinate.. Studies with yeast have shown that amongst the compounds, L1 has had the best activity in the inhibition of the cell growth. It was possible to observe that all compounds decrease the cell survival during the period of incubation. The studies of lipid peroxidation have shown that the complexes were more toxic than the ligands and the complex CuL3 has shown better toxicity when compared to the other compounds and the control. / Complexos de CuII com ligantes derivados de tiazol e tioimidazol, foram sintetizados e caracterizados. Os ligantes (E)-2-(2-benzilidenohidrazinil)-4-feniltiazol (L1), (E)-2-(2-(4-clorobenzilideno)hidrazinil)-4-feniltiazol (L2), (E)-2-(2-(4-metoxibenzilideno)hidrazinil)-4-feniltiazol (L3), (E)-4-fenil-2-(2-(piridin-2-il-metileno)hidrazinil)tiazol (L4), (E)-5-fenil-1-((piridin-2-il-metileno)amino)-1H-imidazol-2(3H)-tiona (L5) e (E)-1-((2-hidroxibenzilideno)amino)-5-fenil-1H-imidazol-2(3H)-tione (L6), j? reportados na literatura, foram obtidos e caracterizados em parceria com o Laborat?rio LaDMol-QM da UFRRJ. Para estes ligantes foram realizados c?lculos qualitativos de modelagem molecular pelo m?todo semi-emp?rico PM6 para otimiza??o de geometria e estimativas de energias relativas de orbitais de fronteira e de conf?rmeros. A estrutura cristalina do ligante L2 foi determinada por difra??o de raios-X de monocristal. Os complexos de CuII foram obtidos a partir de rea??o dos ligantes com CuCl2 em diferentes estequiometrias. As propostas para os complexos foram formuladas com base nos dados de an?lise elementar de CHN, resson?ncia paramagn?tica eletr?nica (EPR) e espectroscopias eletr?nica (UV-vis) e vibracional (FTIR). Os resultados de EPR apontam para a ocorr?ncia de mais de um n?cleo de CuII em todos os produtos. Para os complexos CuL1-CuL3 com ligantes potencialmente bidentados (L1-L3) foi proposta complexa??o tanto pelo ?tomo de enxofre (anel tiazol) como tamb?m pelos ?tomos de nitrog?nio (azometino), com possibilidades de geometrias octa?dricas e tamb?m quadradas. J? os complexos CuL4-CuL6, com ligantes potencialmente tridentados (L4-L6), foi proposta complexa??o tanto pelo ?tomo de enxofre do anel tiazol como tamb?m pelos ?tomos de nitrog?nio do azometino e do anel pirid?nico. No caso de CuL6 ainda h? possibilidade de coordena??o atrav?s do ?tomo de oxig?nio, com CuII possivelmente pentacoordenado.. Testes realizados em leveduras mostraram que dentre os compostos, o L1 foi o que apresentou melhor desempenho na inibi??o do crescimento das c?lulas. No caso do teste de viabilidade foi poss?vel observar que todos os compostos diminuem a sobrevida celular no per?odo de incuba??o. Por meio da an?lise de peroxida??o lip?dica foi poss?vel verificar que os complexos foram mais t?xicos do que os ligantes e que o CuL3 foi o que apresentou maior toxidez quando comparado com os demais complexos e com o controle
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Caracteriza??o da pr?polis verde brasileira: subst?ncias fen?licas, atividade biol?gica e an?lise quimiom?trica / Characterization of brazilian green propolis: phenolics compounds, biological activity and chemometric analysis

SALGUEIRO, Fernanda Barbosa 23 September 2016 (has links)
Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq / Propolis is a resinous material collected by bees from different parts of plants. Both its composition as its biological properties are dependent on factors such as climate, soil, vegetation and species of collecting bees. Propolis has great potential for therapeutic use due to its chemical composition and pharmacological properties. Herein it was determined the contents of phenolic compounds, antioxidant capacity and chemical composition (assessed by HPLC-PAD) of twelve green propolis samples from beekeepers and sixteen commercial propolis extracs from different regions of Southeast Brazil. The antioxidant abilities of the extracts were qualitatively determined through the total phenolic contents using the Folin?Ciocalteau method. Total flavonoids were assessed by the method of complexation with aluminium chloride. The quantitative antioxidant activiti of propolis extracts were determined both by trapping the organic radicals DPPH and ABTS.+ as well by the iron reduction method (FRAP). High pressure liquid chromatography allowed the identification and quantification of chlorogenic acid, caffeic acid, ferulic acid, para-coumaric acid, rosmarinic acid, vanillin, hesperidin, naringenin, pinobanksin, kaempferol, 4-hydroxy-3,5-diprenyl cinnamic acid (Artepillin-C), kampheride and pinostrobin. Artepillin C, a well known chemical marker of propolis, was present in all propolis extracts analyzed. We highlight that the presence of rosmarinic acid in propolis samples from Rio de Janeiro was reported for the first time in this work. The discrimination between green propolis in natura and commercial green propolis extracts was performed using PCA (Principal Component Analysis) statistical method. The antioxidant capacity in vivo of propolis extracts were evaluated using Saccharomyces cerevisiae as biological system model, assessing important parameters as stress tolerance and lipid peroxidation rate. The antifungal activity of ethanol extracts of propolis in natura were tested against the phytopathogenic fungus Fusarium oxysporium. / A pr?polis ? um material resinoso coletado pelas abelhas de diferentes partes das plantas, sua composi??o e as suas propriedades biol?gicas dependem do clima, solo, vegeta??o e da esp?cie da abelha. A pr?polis tem grande potencial de aplica??o terap?utica, devido ? sua composi??o e propriedades farmacol?gicas. Nesse trabalho foi determinado o teor de subst?ncias fen?licas, a capacidade antioxidante e composi??o qu?mica por CLAE-DAD de doze amostras de pr?polis verde, adquiridas de apicultores, e dezesseis extratos de pr?polis comerciais, provenientes de diferentes regi?es do Sudeste do Brasil. A capacidade antioxidante dos extratos foi avaliada qualitativamente atrav?s do teor de fen?licos totais, pelo m?todo de Folin?Ciocalteau, e flavonoides pelo m?todo de complexa??o com cloreto de alum?nio. A quantifica??o do potencial antioxidante foi realizada pela captura dos radicais org?nicos DPPH e ABTS.+, al?m do m?todo de redu??o do ?on f?rrico (FRAP). An?lises por cromatografia l?quida de alta efici?ncia permitiram a identifica??o e quantifica??o de ?cido clorog?nico, ?cido cafeico, ?cido fer?lico, ?cido para-cum?rico, ?cido rosmar?nico, ?cido 3,5-diprenil-4-hidroxicin?mico (Artepillin C), vanilina, hesperidina, naringenina, pinobanksina, canferol, canferide e pinostrobina. Em todos os extratos de pr?polis analisados foi identificado o Artepillin C, marcador qu?mico para pr?polis verde. Destacamos que neste trabalho foi reportada pela primeira vez a presen?a de ?cido rosmar?nico em pr?polis do Rio de Janeiro. M?todos quimiom?tricos de an?lise explorat?ria, utilizando ?nalise por Componentes Principais foram utilizados para discriminar extratos de pr?polis verde in natura daqueles extratos comerciais. O potencial antioxidante in vivo dos extratos etan?licos de pr?polis foram avaliados utilizando cepas controles de Saccharomyces cerevisiae como modelo de sistema biol?gico e foram avaliados toler?ncia ao estresse e proxida??o lip?dica. A atividade antif?ngica dos extratos etan?licos de pr?polis in natura foram avaliados, e inibiram o crescimento in vitro do fungo fitopat?geno Fusarium oxysporum.
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Estudo te?rico das rea??es de SN2 em fase gasosa: RCI+OH??ROH+CI? (R = Metil, Etil, n-Propil, i-Propil, n- Butil, s-Butil e t-Butil) / Theoretical Study of the Gas-Phase SN2 Reactions: RCl + OH- ROH + Cl- (R=Methyl, Ethyl, n-Propyl, i-Propyl, n-Butyl, s-Butyl e t-Butyl).

Souza, Ana Carolina Bello de 03 October 2012 (has links)
Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2017-04-24T14:13:26Z No. of bitstreams: 1 2012 - Ana Carolina Bello de Souza.pdf: 1911170 bytes, checksum: 62c70571aeb2100b8313dc1ef44eac2b (MD5) / Made available in DSpace on 2017-04-24T14:13:26Z (GMT). No. of bitstreams: 1 2012 - Ana Carolina Bello de Souza.pdf: 1911170 bytes, checksum: 62c70571aeb2100b8313dc1ef44eac2b (MD5) Previous issue date: 2012-10-03 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / In this work, the theoretical study of the gas-phase bimolecular nucleophilic substitution reaction, CH3Cl + OH- CH3OH + Cl-, is introduced, aiming the description of the potential energy surface, the calculation of rate constants and the investigation of the effect of increasing the side chain (changing the CH3 radical in the reaction cited above by the radicals ethyl, n-propyl, i-propyl, n-butyl, s-butyl e t-butyl). The theoretical calculations have been first performed at the MP2/6-31+G(d) level for the geometry optimizations and vibrational frequencies calculations. Single point calculations at the CCSD(T)/6-31+G(d) level have also been performed in order to improve the total energies for the stationary points. However, the relative energies of these stationary points at both MP2 and CCSD(T) level shown close results, so that the single point calculations at the CCSD(T) level have not been proved strictly necessary and have therefore not been performed for all the points along the potential energy surface. The minimum energy path has been described by the intrinsic reaction coordinate method, calculated at the MP2/6-31+G(d) by performing sequential geometry optimizations starting from the saddle point. The calculated enthalpy difference at 298K for the reaction has been determined as -49.5 kcal/mol, in good agreement with the literature value: -50.5 kcal/mol. The calculated rate constant has been obtained as 1.41 x 10-9 cm3.molecule-1.s-1, at 298,15K, in excellent agreement with the experimental data: 1.3 ? 1.6 x 10-9 cm3.molecule-1.s-1.Moreover, the rate constants show non-Arrhenius behavior, decreasing as the temperature increases, which is consistent with the experimental expectation. In this way, the performance of the variational transition state theory for this reaction can be considered satisfactory. By increasing the side chain of the reactant, other reaction channels have been observed: the bimolecular elimination E2 channel and the attack of the nucleophile from the same plane of the exit group (the front-SN2).For these reactions of the alkyl chlorides on n carbon atoms (1 < n ? 4), the B3LYP/6-31+G(d,p) level has been adopted for geometry optimizations and vibrational frequencies. Then, single point calculations at the CCSD(T)/6-31+G(d,p)//B3LYP/6- 31+G(d,p) level have been performed. A comparison of the reaction channels, back- SN2 and E2, shows that the E2 channel is kinetically favored, whereas the SN2 products are thermodynamically more stable. As expected, high values for the potential height have been observed for the front-SN2, being these channels disfavored in all cases. In general, the energy of the saddle points in respect to the isolated reactants slightly depend upon the size of the side chain. / Este trabalho trata do estudo te?rico das rea??es de substitui??o nucleof?lica de segunda ordem, CH3Cl + OH- CH3OH + Cl-, em fase gasosa, visando estudar a superf?cie de energia potencial, obter as constantes de velocidade e ainda verificando o efeito do aumento da cadeia lateral (trocando o radical CH3 na rea??o descrita acima por radicais etil, n-propil, i-propil, n-butil, s-butil e t-butil). Primeiramente, c?lculos te?ricos para otimiza??es de geometria e frequ?ncia foram realizados em n?vel MP2/6-31+G(d) para a rea??o CH3Cl + OH- CH3OH + Cl- e, em seguida, c?lculos single-point em n?vel CCSD(T)/6-31+G(d) foram realizados para corrigir os valores da energia eletr?nica dos pontos estacion?rios obtidos no caminho de rea??o. Entretanto, os valores obtidos para as energias relativas em n?veis MP2 e CCSD(T) foram muito pr?ximos, n?o sendo estritamente necess?rio refinar,atrav?s de c?lculos single-point em n?vel CCSD(T)/6- 31+G(d),os valores de energia de todos os pontos obtidos na superf?cie de energia potencial. O caminho de rea??o menor energia foi descrito pela coordenada de rea??o intr?nseca, calculada por otimiza??es de geometrias de uma sequ?ncia de configura??es ao redor do ponto de sela em n?vel MP2/6-31+G(d). A diferen?a de entalpia a 298K calculada para a rea??o foi de -49,5 kcal/mol, em bom acordo com o dado da literatura, -50,5 kcal/mol. A constante de velocidade da rea??o obtida foi de 1,41 x 10-9 cm3.mol?cula-1.s-1, a 298,15K, em excelente acordo com o dado experimental: 1,3 ? 1,6 x 10-9 cm3.mol?cula-1.s-1. Al?m disso, as constantes de velocidade globais apresentam comportamento n?o-Arrhenius, diminuindo conforme a temperatura aumenta, em um perfil consistente com a observa??o experimental. Dessa forma, a aplica??o da teoria de estado de transi??o se mostra satisfat?ria para essa rea??o. A partir do aumento da cadeia lateral, outros canais de rea??o foram observados, em prov?vel competi??o ? substitui??o nucleof?lica de ordem 2: a elimina??o de segunda ordem, E2. O ataque do nucle?filo pela frente da cadeia tamb?m foi obtido e investigado. Para as rea??es dos cloretos de alquila com cadeia lateral de n carbonos (1 < n ? 4), o n?vel B3LYP/6- 31+G(d,p) foi adotado para c?lculos de otimiza??es e frequ?ncias. Posteriormente, c?lculos em n?vel CCSD(T)/6-31+G(d,p)//B3LYP/6-31+G(d,p) foram realizados. Comparando os canais de rea??o de substitui??o nucleof?lica back e de elimina??o, o canal cineticamente favorecido foi o de elimina??o, por?m os produtos termodinamicamente mais est?veis s?o os de substitui??o nucleof?lica. Como esperado, observa-se uma barreira de potencial muito alta para as rea??es substitui??o pela frente, sendo esses canais desfavorecidos em todos os casos.Em geral, a diferen?a de energia dos pontos de sela em rela??o aos reagentes isolados mostra pequena depend?ncia com o aumento da cadeia lateral linear

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