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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.
31

O caos a?reo brasileiro: percep??es sobre o setor atrav?s da ?tica de executivos carioca / The brazilian aviation chaos: perceptions about the sector through the eyes of the Rio de Janeiro executives

GALINDO, Fl?via Luzia Oliveira da Cunha 05 December 2008 (has links)
Made available in DSpace on 2016-04-28T20:19:22Z (GMT). No. of bitstreams: 1 2008 - Flavia Luzia Oliveira da Cunha Galindo.pdf: 834918 bytes, checksum: 0d750029bb9ddb8854de320dde189f55 (MD5) Previous issue date: 2008-12-05 / Regarding the studies about the behavior of the consumer and crisis management reflects the numerous contributions of social sciences and humanities. The connection of these two areas of understandings was possible through the observation of experiences the consumers lived through, during the recent Brazilian aviation crisis, which made it possible to understand the inconstant trust of the executives after the crisis. The dissertation contextualizes how the executives from Rio de Janeiro think and act, compounding an extremely singular vision regarding their perceptions after the Brazilian aviation crisis. To support the field work expost facto, the theoretical reference includes authors linked to the marketing of services, consumer behavior, consumption and citizenship, trust and crisis management. From the economic and business point of view, the organizations understand the relevance of the study regarding trust when confirmed that the consumers want to trust their suppliers and have the expectation that the products, goods and services be unswerving to the ideas and aspirations that are developed in their lives. The elements of trust are classified into: i) factors linked to the authors decision to trust and support the singular mixture of personality, culture and experience; ii) situational factors that have to do with the aspects of specific situations and relationships between the parties. The work demanded: i) exploratory field work, ii) data collection from secondary sources (print and electronic media), iii) official information divulged by the institutions involved, iv) interviews with time sensitive users of a hypothetical deduction character with a qualitative approach, necessary to attract the perspective subjects in the investigation ex-post facto. The Contents Analysis method allowed to understand the world of the significant of the actions and human relations in their overall situation. In exploring a critical situation such as the one faced by the Brazilian aerial blackout , the work witnessed how the aviation crisis, complex and long-lasting, weakened institutions and the consumers belief was greatly affected. / Os estudos sobre o comportamento do consumidor e o gerenciamento de crises refletem as m?ltiplas contribui??es das ci?ncias sociais e humanas. A uni?o destas duas ?reas do conhecimento foi poss?vel atrav?s da observa??o das experi?ncias vividas pelos consumidores na recente crise a?rea brasileira, que permitiu compreender a vari?vel confian?a dos executivos ap?s a mesma. A disserta??o contextualizou o modo como os executivos do Rio de Janeiro pensam e agem, compondo uma vis?o muito singular sobre as suas percep??es ap?s a crise a?rea brasileira. Para ancorar a pesquisa de campo ex-post facto, o referencial te?rico conta com autores ligados ao marketing de servi?os, comportamento do consumidor, consumo e cidadania, confian?a e gerenciamento de crise. Do ponto de vista econ?mico e empresarial, as organiza??es compreendem a relev?ncia do estudo sobre confian?a quando afirmam que os consumidores querem confiar em seus fornecedores, e t?m a expectativa de que os produtos, bens e servi?os sejam fi?is aos ideais e aspira??es que desenvolvem em suas vidas (Roberts, 2005). Os elementos da confian?a se distribuem em: i) fatores ligados ao autor da decis?o de confiar e se ancoram na mistura singular de personalidade, cultura e experi?ncia; ii) fatores situacionais que tem a ver com os aspectos da situa??o espec?fica e do relacionamento entre as partes (Hurley, 2006). O trabalho demandou: i) pesquisa de campo explorat?ria, ii) coleta de dados em fonte secund?ria (m?dia impressa e eletr?nica), iii) informa??es oficiais divulgadas pelas institui??es envolvidas, iv) entrevistas com usu?rios time sensitive de car?ter hipot?ticodedutivo (Foddy, 1993), com abordagem qualitativa, necess?ria para captar a perspectiva dos sujeitos em uma investiga??o ex-post facto (Gil, 1996). O m?todo de An?lise de Conte?do (Bardin, 1977) possibilitou compreender o mundo de significados das a??es e rela??es humanas no seu contexto. Ao explorar uma situa??o cr?tica como a enfrentada pelo apag?o a?reo brasileiro, o trabalho evidenciou como a crise a?rea, complexa e de longa dura??o, fragilizou institui??es e afetou a credibilidade de consumidores intensivos.
32

O antagonismo com acetamida em experimentos com ovinos, caprinos e coelhos indica monofluoroacetato como princ?pio t?xico de Pseudocalymma elegans / Antagonism of acetamid in experiments with sheep, goats and rabbits indicates that monofluoroacetate is the toxic principle of Pseudocalymma elegans

Helayel, Michel Jos? Sales Abdalla 16 March 2011 (has links)
Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2016-09-19T11:49:34Z No. of bitstreams: 1 2011 - Michel Jos? Sales A. Helayel.pdf: 11350186 bytes, checksum: ab1a4bf6f150ee6e971e58207f995bff (MD5) / Made available in DSpace on 2016-09-19T11:49:34Z (GMT). No. of bitstreams: 1 2011 - Michel Jos? Sales A. Helayel.pdf: 11350186 bytes, checksum: ab1a4bf6f150ee6e971e58207f995bff (MD5) Previous issue date: 2011-03-16 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / This study aimed to evaluate the protective effect of acetamid in experimental poisoning by Pseudocalymma elegans in sheep, goats and rabbits, in order to prove indirectly that monofluoroacetate (MF) is responsible for the clinical signs and death of animals that ingested the plant. Experiments were performed to determine for sheep and goats the lethal dose of P. elegans collected in Rio Bonito, RJ, in different seasons, and to adjust the dose of acetamid to be administered. In the first experiment, four animals received 1.0g/kg of fresh P. elegans, and two others were pretreated with 2.0g/kg of acetamid. None of the animals showed clinical signs or died. Possibly, the plant could be less toxic, since it was collected at the end of the rainy season. In the second experiment, two sheep and two goats received 0.67 and 1.0g/kg of the dried plant, after pretreatment with 2.0 and 3.0g/kg of acetamid, respectively. All animals died, as the administered doses of P. elegans were very high. In the third experiment, two sheep and two goats received 0.333g/kg of dried P. elegans after previous administration of 2.0g/kg of acetamid; a week later, the protocol above was repeated, but without the antidote. In experiments with rabbits, doses of 0.5 and 1.0g/kg of dried P. elegans were given after administration of 3.0g/kg of acetamid; seven days later, the same protocol was repeated, except the administration of acetamide. This procedure, when acetamid was administered before, prevented the appearance of clinical signs and death of sheep, goats and rabbits. But the animals not treated with acetamid showed symptoms of poisoning and died. Clinically, the sheep and goats had tachycardia, engorged jugular vein, positive venous pulse, lateral recumbence, and muscle tremors. In the "dramatic phase?, the animals fell into lateral position, stretched the limbs, were paddling and died within minutes. The rabbits showed apathy, muscle tremors, vocalization and lateral decumbence minutes before death. At postmortem examination, the sheep and goats had engorged jugular veins and atria, dilated Vena cava cranialis and caudalis, as well as pulmonary edema, hepatic congestion and edema of the gallbladder subserosa. In rabbits, the main macroscopic alterations were dilated atria, engorged Vena cava cranialis and caudalis, and congested liver and diaphragm vessels. Histopathology revealed, in two sheep and one goat, vacuolar-hydropic degeneration of the distal convoluted kidney tubules, together with caryopicnosis. In the rabbits, the liver showed severe congestion with numerous shock corpuscles. The experimental results show indirectly that MF is to be held responsible for death of the animals that ingested P. elegans; since "acetate donor" compounds, such as acetamid, are capable to reduce the competitive inhibition of MF for the same active site (Coenzyme A) which prevents the formation of fluorocitrate, its active metabolite, formed in the body through the socalled "lethal synthesis". / O presente trabalho teve como objetivo avaliar o efeito protetor da acetamida nas intoxica??es experimentais por Pseudocalymma elegans (Bignoniaceae) em ovinos, caprinos e coelhos, com a finalidade de comprovar indiretamente que o monofluoroacetato ? respons?vel pela sintomatologia e morte dos animais que ingerem essa planta. Foram realizados experimentos para determinar a dose letal da planta coletada em Rio Bonito, RJ, em diferentes ?pocas do ano para ovinos e caprinos e ajustar a dose de acetamida a ser administrada. No primeiro experimento, dois ovinos e dois caprinos receberam 1,0 g/kg de P. elegans fresca e um animal de cada esp?cie foi tratado previamente com 2,0 g/kg de acetamida. Nenhum animal apresentou altera??es cl?nicas ou morreu. Ao que tudo indica a planta poderia estar menos t?xica, j? que foi coletada no fim da esta??o das ?guas. No segundo experimento, dois ovinos e dois caprinos receberam 0,67 e 1,0 g/kg da planta dessecada, ap?s tratamento pr?vio, com 2,0 e 3,0 g/kg de acetamida, respectivamente. Todos os animais morreram, pois administramos doses muito altas de P. elegans. No terceiro experimento, dois ovinos e dois caprinos receberam, 0,333 g/kg de P. elegans dessecada, ap?s administra??o pr?via de 2,0 g/kg de acetamida. Uma semana depois, o protocolo acima foi repetido, por?m sem o ant?doto. Nos experimentos com coelhos, foram administradas doses de 0,5 e 1,0 g/kg de P. elegans dessecada ap?s a administra??o de 3,0 g/kg de acetamida. Sete dias depois, o mesmo protocolo foi repetido, com exce??o da administra??o de acetamida. Esta, quando administrada previamente, evitou o aparecimento dos sinais cl?nicos e a morte dos ovinos, caprinos e coelhos, j? os animais n?o tratados com acetamida apresentaram sintomatologia e morreram. Clinicamente, os ovinos e caprinos manifestaram taquicardia, jugulares ingurgitadas, pulso venoso positivo, dec?bito esternal e tremores musculares. Na ?fase dram?tica?, os animais ca?am em dec?bito lateral, esticavam os membros, faziam movimentos de pedalagem e morriam em poucos minutos. Nos coelhos observaram-se apatia, tremores musculares, dec?bito lateral e vocaliza??o minutos antes da morte. A avalia??o macrosc?pica revelou, nos ovinos e caprinos, jugulares ingurgitadas, aur?culas, veia cava caudal e cranial dilatadas, al?m de edema pulmonar, congest?o hep?tica e edema na subserosa da ves?cula biliar. Nos coelhos as principais altera??es observadas foram aur?culas dilatadas, veia cava caudal e cranial ingurgitadas, f?gado e vasos do diafragma congestos. O exame histopatol?gico revelou, em dois ovinos e um caprino, degenera??o hidr?pico-vacuolar dos t?bulos urin?feros contornados distais associada ? cariopicnose. Nos coelhos havia congest?o hep?tica acentuada com numerosos corp?sculos de choque. Nossos resultados comprovam, de forma indireta, que o MF ? respons?vel pela morte dos animais que ingerem essa planta, uma vez que compostos ?doadores de acetato? como a acetamida, s?o capazes de reduzir a inibi??o competitiva do MF pelo mesmo s?tio ativo (Coenzima A), o que impede a forma??o do fluorocitrato, seu metab?lito ativo, formado no organismo por meio da denominada ?s?ntese letal?.
33

A influ?ncia do pediatra e suas interven??es no sucesso do aleitamento materno exclusivo em pacientes submetidos ? cesariana eletiva

Silveira, Carolina Menna Barreto 29 August 2016 (has links)
Submitted by Setor de Tratamento da Informa??o - BC/PUCRS (tede2@pucrs.br) on 2016-11-09T10:23:59Z No. of bitstreams: 1 DIS_CAROLINA_MENNA_BARRETO_SILVEIRA_PARCIAL.pdf: 882195 bytes, checksum: 4e9eed2bd20f440884bd27fcba9fbdfd (MD5) / Made available in DSpace on 2016-11-09T10:23:59Z (GMT). No. of bitstreams: 1 DIS_CAROLINA_MENNA_BARRETO_SILVEIRA_PARCIAL.pdf: 882195 bytes, checksum: 4e9eed2bd20f440884bd27fcba9fbdfd (MD5) Previous issue date: 2016-08-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Recent data from scientific literature show low exclusive breastfeeding (EBF) rates in the world, and diversity in the factors that influence it. However, the number of studies about the power of pediatricians and their interventions on duration of EBF is still limited. Objective: To determine the influence of the pediatrician and their interventions on the success of EBF at 3 and 6 months of age in full-term newborns (FNT), undergoing elective cesarean delivery. Methods: A cohort study in a private hospital in Brazil. Questionnaires to mothers at discharge, at 7 days, 3 and 6 months of life were applied. At the day of discharge, the contact was in person, while the following steps was by phone calling. To evaluate the association between categorical variables, chi-squared tests or Fisher's exact were used. Results: The final sample consisted of 907 mother-baby pairs, assisted by 32 pediatricians. The influence of the pediatrician was significant in EBF at 3 months of age (p=0.001). The prevalence of complement in the first prescription varied significantly among pediatricians (31.6% to 100%, p <0.001) and was negatively associated with the EBF at 3 months (p=0.003). When comparing the prevalence of the use of bottles and pacifiers at the first 7 days of life, among the pediatricians, there was a significant difference (p=0.005). The use of pacifiers at 7 days and 3 months was negatively associated with the EBF at 3 months (p<0.001). FNTs who used a bottle at 7 days showed lower prevalence of EBF until sixth month of life. Conclusion: This study provides evidences about the influence of the pediatrician in the prevalence and duration of exclusive breastfeeding at third month of life. This reinforces the need to improve their knowledge, attitudes and practices on breastfeeding. / Dados recentes da literatura cient?fica mostram baixas taxas de aleitamento materno exclusivo (AME) no Brasil e no mundo, al?m de uma grande diversidade nos fatores que o influenciam. Contudo, o n?mero de estudos sobre o poder de atua??o do pediatra e suas interven??es na dura??o do AME ainda ? limitado. Objetivo: Verificar a influ?ncia do pediatra e suas interven??es no sucesso do AME aos tr?s e seis meses de vida, em rec?m-nascidos (RNs) a termo, submetidos ? cesariana eletiva. Me?todos: Estudo de coorte, em um hospital privado do Brasil. Foram aplicados question?rios ?s m?es na alta, aos 7 dias, 3 e 6 meses de vida. No dia da alta, o contato foi presencial, enquanto nas etapas seguintes foi telef?nico. Para avaliar a associa??o entre as vari?veis categ?ricas, foram utilizados os testes qui-quadrado de Pearson ou Exato de Fisher. Resultados: A amostra final foi composta por 907 duplas m?es-beb?s, assistidas por 32 pediatras. A influ?ncia do pediatra foi significativa no AME aos 3 meses de vida do beb? (p=0,001). A preval?ncia de complemento na 1? prescri??o variou significativamente entre os pediatras (de 31,6% a 100%; p<0,001) e esteve associada negativamente com o AME aos 3 meses (p=0,003). Quando comparadas as preval?ncias de uso de mamadeira e chupeta aos 7 dias, entre os pediatras, houve diferen?a significativa (p=0,005). O uso de chupeta aos 7 dias e 3 meses associou-se ao insucesso do AME no 3? m?s de vida (p<0,001). RNs que utilizaram mamadeira aos 7 dias apresentaram preval?ncias de AME mais baixas at? o 6? m?s de vida. Conclus?o: Este estudo fornece evid?ncias sobre a influ?ncia do pediatra e suas interven??es na preval?ncia e dura??o do AME no terceiro m?s de vida. Isso refor?a a necessidade de aprimorar seus conhecimentos, atitudes e pr?ticas sobre a amamenta??o.
34

Nascimento por parto ces?reo e risco de excesso de peso aos seis anos de idade: resultados de uma coorte

Gomes, Daiene Rosa 24 March 2014 (has links)
Submitted by Ricardo Cedraz Duque Moliterno (ricardo.moliterno@uefs.br) on 2015-08-04T21:49:38Z No. of bitstreams: 1 DAIENE-ROSA-GOMES-Disserta??o-VERS?O-FINAL.pdf: 966973 bytes, checksum: 1e27e5956e56ed34c52950b749b981c0 (MD5) / Made available in DSpace on 2015-08-04T21:49:38Z (GMT). No. of bitstreams: 1 DAIENE-ROSA-GOMES-Disserta??o-VERS?O-FINAL.pdf: 966973 bytes, checksum: 1e27e5956e56ed34c52950b749b981c0 (MD5) Previous issue date: 2014-03-24 / Background: Obesity in children is a public health problem of great magnitude. In recent decades, there has been increasing rates of caesarean sections and obesity, and might have a possible causal relationship between the two events. Objective: To assess the association between cesarean section delivery and overweight at six years of age in a city in northeastern Brazil. Methods: This is a birth cohort conducted with 672 children followed in home visits until the sixth year of age. The outcome variable was overweight obtained by body mass index by age and the main independent variable was cesarean delivery. Were evaluated as covariates: gender; birth weight (<2500g, ?2500g); duration of breastfeeding (<12 months ?12 months); calories intake at 72 months (<1935 kcal, ?1935 kcal); physical activity at school; means of transport to go to school; maternal excessive weight gain during pregnancy; family income (?1 minimum wage, ? 2 minimum wages); maternal schooling; maternal overweight and maternal work. The association of caesarean delivery and overweight was estimated by logistic regression analysis, with the significance level of 5% and its respective 95% confidence interval. Results: Overweight was present in 36.6% of children born by cesarean section compared with 20.2% of those born by vaginal delivery. The association between overweight and cesarean delivery remained statistically significant after adjusting for confounders (OR = 1.96, 95% CI 1.61; 3.22). Conclusion: The results support the assumption that the birth by cesarean delivery is associated with an increased risk of overweight in childhood. Pregnant women should be warned about the increased risk of being overweight for those children born by cesarean delivery. / INTRUDU??O: Recentemente, o tipo de parto ganhou aten??o como potencial fator de risco para a obesidade na inf?ncia. Acredita-se que diferen?as na composi??o da microbiota intestinal das crian?as nascidas por parto ces?reo e vaginal contribui para o incremento da obesidade, pressuposto questionado por alguns pesquisadores. OBJETIVO: Avaliar a associa??o entre o nascimento por parto ces?reo e o excesso de peso aos seis anos de idade, na cidade de Feira de Santana, Bahia. M?TODOS: Trata-se de uma coorte de nascidos vivos. Foram acompanhados 672 crian?as, em visitas domiciliares, at? o sexto ano. A vari?vel desfecho foi o excesso de peso obtido pelo IMC/idade e a vari?vel independente principal o parto ces?reo. Foram avaliadas como co-vari?veis: sexo; peso ao nascer (<2500g, ?2500g); dura??o do aleitamento materno (<12 meses, ?12 meses); consumo alimentar aos 72 meses (<1935 kcal, ?1935 kcal); atividade f?sica na escola; meio de transporte para ir ? escola; ganho excessivo de peso durante a gesta??o; renda familiar (?1 sal?rio m?nimo, ? 2 sal?rios m?nimos); escolaridade materna; excesso de peso materno e trabalho fora do lar. A an?lise utilizada foi a regress?o log?stica, considerando o n?vel de signific?ncia de 5% e o intervalo de confian?a de 95%. RESULTADOS: O excesso de peso esteve presente em 36.6% das crian?as nascidas por parto ces?reo em compara??o com 20.2% daquelas nascidas por parto vaginal. A associa??o entre excesso de peso e parto ces?reo manteve-se estatisticamente significante ap?s o ajuste pelas vari?veis confundidoras (OR=1.96; IC 95% 1.61, 3.22). CONCLUS?O: Os resultados refor?am o pressuposto de que o nascimento por parto ces?reo est? associado a um aumento de risco de excesso de peso na inf?ncia. As gestantes devem ser alertadas quanto ao maior risco de excesso de peso para aquelas crian?as nascidas por cesariana.
35

Programaci��n Binivel aplicada a la distribuci��n centralizada de recursos

Olivares Aguila, Jessica 12 May 2011 (has links)
En esta tesis se estudia el Problema de Distribuci��n de Recursos en un Sistema de Gobierno Centralizado y se modela como un problema de programaci��n binivel. En la funci��n objetivo del nivel superior se minimiza la insatisfacci��n entre los estados y en la funci��n objetivo del nivel inferior se maximizan los beneficios de cada estado. Para encontrar soluciones factibles para este problema se propone un algoritmo que es una adaptaci��n del m��todo Nelder-Mead, que permite obtener resultados similares a los resultados reportados previamente en la literatura. Adicionalmente, se propone una adaptaci��n del m��todo de Hook-Jeeves restringido con una penalizaci��n de barrera que permite obtener los mejores resultados entre todos los m��todos. Adem��s, se implementa una heur��stica de B��squeda Dispersa con la que se obtiene buenos resultados. Se contempla un estudio computacional, para comparar los tres m��todos en tres instancias de diferentes tama��os. / Palabras Claves: Distribuci��n de recursos, Programaci��n Binivel, Nelder-Mead, Hooke-Jeeves, B��squeda Dispersa. �� .
36

T��cnicas de programaci��n Binivel para el dise��o de redes

Vital Soto, Alejandro 12 May 2012 (has links)
En esta tesis se estudia el Problema de Dise��o de Redes Continuo (CNDP por sus siglas en ingl��s) y se modela como un problema de programaci��n matem��tica binivel. El nivel superior se define como la suma total de los tiempos de viaje y costos de inversi��n de los incrementos de capacidad de las conexiones de la red, mientras que el nivel inferior se enfoca en el equilibrio de flujo de los usuarios que se modela como un problema de minimizaci��n. Se utilizan tres t��cnicas que no usan derivadas para obtener soluciones factibles del problema: 1) el m��todo de Nelder-Mead adaptado al CNDP, 2) un Metaheur��stico de B��squeda dispersa (BD), 3) el uso del algoritmo de Nelder-Mead en BD como un m��todo de mejora de soluciones. Los m��todos propuestos obtienen resultados que igualan a los que se encuentran en la literatura, aunque el m��todo de BD con Nelder-Mead mejora resultados previamente reportados para dos instancias de prueba del problema. / Palabras claves: CNDP, Programaci��n Binivel, Nelder-Mead, B��squeda Dispersa.
37

Gamma Active Constraints in Convex Semi-Infinite Programming

Zetina Villamor, Carlos Armando 08 December 2011 (has links)
This thesis studies the problem of extending the concept of γ-active constraints to Convex Semi-Inαnite Programming. To achieve this goal, extensive knowledge of topology, convex analysis, real analysis and optimization is needed. We base ourselves on the deαnition and results shown in previous publications and present two approaches to extend this deαnition to the case of Convex Semi-Inαnite Programming. We also provide a comparison of the two approaches, where we state their limitations and advantages. / Key Words: Semi-Inαnite Programming, Extended Active Constraints, Convex Program-ming, Optimality Conditions.
38

An Introduction to Application of Statistical Methods in Modeling the Climate Change

Mohammadipour Gishani, Azadeh January 2012 (has links)
There are many unsolved questions about the future of climate, and most of them are due to lack of knowledgeabout the complex system of atmosphere, but still there are models that produce relatively realistic projectionsof the future although there are uncertainties in the presentation of them, and that's where statistical methodscould be of help. Here a short introduction is given to the projection of future climate with GCM ensembles andthe uncertainties about them, the emerging probabilistic approach, as well as the REA (Reliability EnsembleAverage) method for measuring the reliability of the model projections. In order to have an impression of theresults of the GCM ensemble results and their uncertainties the results of the weather forecast over a time periodof one year in three dierent cities of Sweden is studied as well.
39

Pardavimų modelis elektroninėje parduotuvėje / The model of Sales in the Web

Muralis, Laisvūnas 22 June 2005 (has links)
This work focuses on the analysis of Internet info and literature about e-commerce systems, shops, supply chain systems and enterprise resource planing systems and create the framework of sales in the web with ready to use elements, database, based on REA semantic model for Internet supply chain collaboration. The research material leads to the conclusion that REA model is the best model for Internet commerce and Lithuanian Internet trading systems are not fully ready for competition on the Internet market. However, the work suggests the solution for the problems detected in LT websites, which deal with Internet sales.
40

S?ntese, caracteriza??o e estudo da associa??o em meio aquoso de copol?meros responsivos de carboximetilcelulose-g-Jeffamine?

Marques, N?via do Nascimento 17 February 2016 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-08-25T20:20:12Z No. of bitstreams: 1 NiviaDoNascimentoMarques_TESE.pdf: 5195117 bytes, checksum: 8d7d4debf09d19f1c68476d90c92aa9f (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-08-25T21:40:38Z (GMT) No. of bitstreams: 1 NiviaDoNascimentoMarques_TESE.pdf: 5195117 bytes, checksum: 8d7d4debf09d19f1c68476d90c92aa9f (MD5) / Made available in DSpace on 2016-08-25T21:40:38Z (GMT). No. of bitstreams: 1 NiviaDoNascimentoMarques_TESE.pdf: 5195117 bytes, checksum: 8d7d4debf09d19f1c68476d90c92aa9f (MD5) Previous issue date: 2016-02-17 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Esta tese apresenta a s?ntese, caracteriza??o e o comportamento associativo em meio aquoso de novos copol?meros responsivos graftizados, tendo a carboximetilcelulose (CMC) como cadeia principal hidrossol?vel e as Jeffamine? M-2070 e Jeffamine? M-600 (poli?teraminas comerciais) como enxertos termorresponsivos. A s?ntese foi feita em meio aquoso, por meio do uso da 1-(3-(dimetilamino)propil)-3-etil-carbodiimida e da N-hidroxisuccinimida como ativadores da rea??o entre os grupos carboxilato do polissacar?deo e o grupamento amino das poli?teraminas. A rea??o de graftiza??o foi confirmada por infravermelho e o grau de substitui??o por RMN 1H. A massa molar das poli?teraminas utilizadas foi determinada por RMN 1H, enquanto que a massa molar da CMC e dos copol?meros foi determinada por espalhamento de luz est?tico. O comportamento t?rmico do estado s?lido foi avaliado por an?lise termogravim?trica. O efeito da adi??o de sal na associa??o dos copol?meros foi avaliado em diferentes meios aquosos (?gua Milli-Q, NaCl 0,5M, K2CO3 0,5M e em ?gua do mar sint?tica) atrav?s das t?cnicas de UV-vis, reologia e espalhamento de luz din?mico. Nenhum dos copol?meros exibiu turva??o em ?gua Milli-Q quando aquecidos de 25 at? 95 ?C, a 5g/L, provavelmente em fun??o do aumento da hidrofilicidade dos enxertos pela rea??o com a CMC, e tamb?m atrav?s do afastamento entre os enxertos promovidos pela repuls?o eletrost?tica entre os grupos carboxilato do polissacar?deo. Entretanto, os copol?meros apresentaram turva??o na presen?a de sais, devido ao efeito ?salting out?, sendo que a menor temperatura de turva??o foi observada em K2CO3 0,5M, o que foi atribu?do ? maior for?a i?nica do K2CO3 0,5M em ?gua, combinado com a habilidade do CO32- de diminuir as intera??es pol?mero-solvente. As cadeias dos copol?meros apresentaram maior raio hidrodin?mico do que a CMC e as associa??es dependeram do solvente e da composi??o do copol?mero. A viscosidade dos copol?meros no meio aquoso variou em fun??o da adi??o de sais ao meio, temperatura e composi??o polim?rica, sendo observado comportamento termoviscosificante em K2CO3 0,5M quando temperatura foi elevada de 25 para 60 ?C. Este comportamento pode ser atribu?do ?s associa??es intermoleculares quando a temperatura est? acima da temperatura de turva??o do pol?mero. / This thesis presents the synthesis, characterization and study of the associative behaviour in aqueous media of new responsive graft copolymers, based on carboxymethylcellulose as the water-soluble backbone and Jeffamine? M-2070 e Jeffamine? M-600 (commercial polyetheramines) as the thermoresponsive grafts with high cloud point temperatures in water. The synthesis was performed on aqueous medium, by using 1-ethyl-3- (3-(dimethylamino)-propyl)carbodiimide hydrochloride and N-hydroxysuccinimide as activators of the reaction between carboxylategroupsfrom carboxymethylcellulose and amino groups from polyetheramines. The grafting reaction was confirmed by infrared spectroscopy and the grafting percentage by 1H NMR. The molar mass of the polyetheramines was determined by 1H NMR, whereas the molar mass of CMC and graft copolymers was determined by static light scattering. The salt effect on the association behaviour of the copolymers was evaluated in different aqueous media (Milli-Q water, 0.5M NaCl, 0.5M K2CO3 and synthetic sea water), at different temperatures, through UV-vis, rheology and dynamic light scattering. None of the copolymers solutions, at 5 g/L, turned turbid in Milli-Q water when heated from 25 to 95 ?C, probably because of the increase in hydrophibicity promoted by CMC backbone. However, they became turbid in the presence of salts, due to the salting out effect, where the lowest cloud point was observed in 0.5M K2CO3, which was attributed to the highest ionic strength in water, combined to the ability of CO3 2- to decrease polymer-solvents interactions. The hydrodynamic radius and apparent viscosity of the copolymers in aqueous medium changed as a function of salts dissolved in the medium, temperature and copolymer composition. Thermothickening behaviour was observed in 0.5M K2CO3 when the temperature was raised from 25 to 60?C. This performance can be attributed to intermolecular associations as a physical network, since the temperature is above the cloud point of the copolymers in this solvent.

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