Juventude e estilo de vida : cultura de consumo, lazer e midia

Orientador: Jose Mario Ortiz RamosDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Filosofia e Ciencias HumanasResumo: Este trabaJho tem por objetivo fazer uma análise da vida cotidiana da juventude contemporânea, buscando compreender, interpretar e explicar o modo como os múltiplos significados que os jovens atribuem aos compassos sociais que os rodeiam são construídos e usados. Termos como estilo de vida, meios de comunicação e formas de lazer, serão estudados em função do consumo, isso porque veiculam súnbolos e promovem a incorporação de estilos, tornando-se os principais pilares na estruturação da identidade juvenil Tais súnbolos não se restringem a fronteiras geográficas, são mundializados e representam a atual estrutura social. Assim, é nesse cenário de cultura mundializada que os meios de comunicação, o consumo e o lazer disseminam súnbolos culturais e estes são tomados em outros contextos, reelaborados e lançados novamente no espaço virtual da comunicação e da sociabilização humana. Nesse sentido, vivemos numa contínua re-significação da realidadeAbstract: This work has as objective to do an analysis of the contemporary youth's daily life, trying to understand, to interpret and to explain the way as the multiples meanings the youths attribute to the social compasses that they surround are built and used. Expressions as lifestyle, communication means and leisure forms will be studied to the function of the consumption, that because they transmit symbols and they promote the incorporation of styles, becoming the main pillars in the structuring of the juvenile identity. Such symbols do not limit to the geographical borders, they are all over the world and they represent the current social structure. Like this, it is in that scenery of worldwide culture that the communication means, the consumption and the leisure disseminate cultural symbols and these are taken in other contexts, reelaborated and thrown again in the virtual space of the communication and of the human socialization. In that sense, we lived in a continuousMestradoMestre em Sociologi

Análise estrutural dos promotores dos genes de endoglicanase egl1 e egl4 de Humicola grisea var. thermoidea

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Biológicas, Departamento de Biologia Celular, Programa de Pós-Graduação em Biologia Molecular, 2013.A limitação de recursos fósseis e o contínuo crescimento econômico tem aumentado a demanda por fontes alternativas para a produção de biocombustíveis e compostos químicos. A conversão da biomassa vegetal apresenta grande potencial para esse fim, já que representa a maior fonte renovável do planeta. O fungo termofílico Humicola grisea var. thermoidea (Hgvt) é conhecido por produzir uma ampla variedade de enzimas hidrolíticas termoestáveis. Dentre as hidrolases produzidas por esse organismo estão as celulases, xilanases, glicoamilases e trealases. Tais enzimas possuem grande potencial biotecnológico para a conversão de resíduos agroindustriais em produtos de maior valor agregado tais como ração animal, adubo, biocombustíveis, além de extração de óleos vegetais, processamento têxtil, branqueamento e reciclagem de papéis. A caracterização e a compreensão dos mecanismos regulatórios dos genes que codificam enzimas hidrolíticas são de grande importância para o aprimoramento de estratégias de produção dessas enzimas. Diante disso, o presente trabalho teve como objetivo a análise estrutural das regiões 5´ não codificadoras a montante dos genes de endoglicanase 1 (egl1), endoglicanase 4 (egl4) e celobiohidrolase 1.1 (cbh1.1) de Hgvt. As regiões 5´UP foram amplificadas a partir de DNA genômico de Hgvt e clonadas no vetor pGOX, contendo marca de resistência à higromicina B e o cassete de expressão do gene de glicose oxidase (goxA) de Aspergillus niger como repórter visando a posterior caracterização funcional em sistema heterólogo de Aspergillus nidulans. As regiões promotoras de egl1 e egl4 foram inicialmente analisadas in silico quanto à presença de sítios de ligação para os fatores transcricionais PacC, regulador da expressão gênica em resposta ao pH, e CreA, mediador da repressão transcricional por glicose. A fim de se avaliar a interação desses fatores com os promotores foram sintetizadas sondas contendo sítios de ligação para CreA e para PacC. Os domínios de ligação de PacC e CreA foram produzidos em Escherichia coli como proteínas de fusão à glutationa-S-transferase (GST). As proteínas recombinantes e as sondas foram empregadas em ensaios de retardo de mobilidade eletroforética (EMSA). Foi observada a formação de complexos específicos entre DNA e proteína em dois sítios para PacC e em dois sítios para CreA presentes na região promotora de egl1, o que aponta para a participação desses fatores na regulação do gene. Com relação ao gene egl4, não foi observada a interação entre o fator transcricional PacC e a região promotora do gene. Entretanto, houve formação de complexos entre CreA e os sítios presentes na região 5’UP de egl4. Apesar de reconhecerem os sítios consenso na região desse gene, nenhuma das interações mostrou ser específica. Tais dados sugerem que a regulação da expressão de egl4 obedeça a mecanismos distintos aos dos demais genes de celulase de Hgvt estudados até o momento. _______________________________________________________________________________________ ABSTRACTFossil fuels limited supply and the continuous economic growth have shifted the demand for renewable sources for the production of biofuels and other biomaterials. Plant biomass conversion depicts an interesting potential to this goal, since it represents the most abundant and renewable energy source on the planet. The thermophilic fungus Humicola grisea var. thermoidea (Hgvt) is well known for its capability to generate thermostable hydrolytic enzymes, such as cellulases, xylanases, glucoamylases and trehalases. These enzymes have great biotechnological potential to convert bio-based feedstocks into products with a higher added value, for instance: animal feed, fertilizers, biofuels and also for the extraction of vegetable oils, textiles processing (biopolishing and biostoning) and paper recycling. Comprehension and characterization of the regulatory mechanisms of hydrolytic enzyme-encoding genes are of great importance to the optimization of these enzymes production. Therefore, the present work aimed the analysis of the 5’ upstream regions of the Hgvt endoglucanase 1 (egl1), endoglucanase 4 (egl4) and cellobiohydrolase 1.1 (cbh 1.1) genes. These regions were obtained from Hgvt genomic DNA and cloned into the pGOX vector. This cloning vector contains a hygromycin selection marker and an Aspergillus niger glucose oxidase (goxA) expression cassette for posterior functional characterization in the Aspergillus nidulans heterologous system expression. egl1 and egl4 genes promoters were analyzed in silico for the presence of binding sites for the pH-responsive transcriptional factor PacC and for the catabolite repressor transcriptional factor CreA. In order to assess the interaction of these factors with the gene promoters, DNA probes containing CreA or PacC binding sites were utilized. PacC and CreA DNA binding domains were produced in Escherichia coli as a glutathione-S-transferase (GST) fusion protein. The recombinant proteins and DNA probes interaction was investigated by electrophoretic mobility shift assay (EMSA). DNA/protein specific interactions were observed between two PacC and two CreA binding sites situated on egl1 promoter region indicating that this gene expression is regulated by pH and by carbon source. Regarding the egl4 promoter, no interaction was detected with PacC. On the other hand, CreA/DNA complexes were detected for the egl4 5’ upstream region but none of these interactions showed to be specific thus suggesting that this gene is subject to an alternative regulatory mechanism

Arterial stiffness response to acute combined training with different volumes in coronary artery disease and heart failure patients

© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).Resistance training has been shown to acutely increase arterial stiffness (AS), while endurance training appears to decrease AS. However, the findings are from studies in apparently healthy subjects and have limited applicability to patients at low and high cardiovascular risk, for whom combined exercise is recommended. We compared the time course of changes in local and regional indices of AS in response to high-volume combined endurance training (CET) and high-volume combined resistance training (CRT) in patients with coronary artery disease (CAD) and heart failure (HF). We studied 20 men with CAD and HF (10 each) aged 68.3 ± 9.6 years. AS was measured by pulse wave velocity (PWV), and brachial and central blood pressure (BP) were determined after 15 min of rest and 5 and 15 min after the exercise session. All patients completed two sessions on nonconsecutive days. A protocol by time interaction effect was observed for carotid (η2 = 0.21, p = 0.02), aortic (η2 = 0.60, p < 0.001), and femoral (η2 = 0.46, p = 0.01) PWV after CET and CRT, suggesting that PWV decreased after CET and increased after CRT. Decreases in the brachial and central variables of BP across time points were observed in both protocols. CET decreased whereas CRT increased carotid, aortic, and femoral PWV at 15 min after exercise in patients with CAD and HF.info:eu-repo/semantics/publishedVersio

Arterial stiffness following endurance and resistance exercise sessions in older patients with coronary artery disease

© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).Arterial stiffness (AS) is associated with coronary artery disease (CAD). Acute endurance training decreases AS, whereas acute resistance training increases it. However, these results are from studies in apparently healthy adults, and there is no information on the effects of such afterload AS in elderly patients with CAD. We aimed to investigate the effect of acute endurance or resistance training on the time course of changes in the indices of AS in elderly patients with CAD in order to understand how stiffness responds after training. We tested 18 trained men with CAD. AS was measured using central and peripheral pulse wave velocity (PWV) after 15 min of rest and after 5, 15, and 30 min of endurance and resistance training sessions. The endurance session consisted of high-intensity interval walking at 85-90% of maximum heart rate, and the resistance session consisted of 70% of the maximum of one repetition. An interaction effect was found for central and peripheral PWV (p ≤ 0.001; carotid, η2 = 0.72; aortic, η2 = 0.90; femoral, η2 = 0.74), which was due to an increase in PWV after resistance and a decrease in central and peripheral PWV after endurance. This study demonstrates that training mode influences the time course of AS responses to acute exercise in these patients. Acute endurance training decreased AS, whereas resistance training significantly increased it.info:eu-repo/semantics/publishedVersio

Acute and long-term effects of combined exercise training on vascular and autonomic function in patients with coronary artery disease

Introduction: Exercise training is potentially recommended to improve heart rate variability (HRV) and arterial stiffness (AS) in coronary artery disease patients (CADp). Purposes: To analyse the acute and chronic effects of exercise stimuli (acute: A- maximal, B- bouts; chronic: C- training) on cardiac-ANS and AS in CADp. Methods: Participants: A- participants classified according to cardiorespiratory fitness: Untrained CADp as Very Poor-Fit (VPFIT-CAD; n=18); Trained CADp as Poor-Fit (PFIT-CAD; n=18); Trained healthy match individuals as Fair-Fit (FFIT-HY; n=18); B- trained CADp (CAD-t, n=18) and trained healthy individuals (HY-t, n=18); C- trained CADp divided in periodized (n=12) and non-periodized (n=12) groups. Exercise protocol: A- maximal ramp protocol; B- moderate (MOCEB) and high intensity (HICEB) combined exercise bouts; C-. periodized and non-periodized training. Results: A- CADp and healthy peers had similar HRV decrease, and AS increase during recovery. B- HICEB increased aortic- pulse wave velocity (PWV) and decrease high-frequency parameters during recovery in CAD-t; group-effect was found after HICEB on upper limb-PWV; both groups had similar responses after MOCEB on HRV and AS parameters; C- Non-periodized training was more effective to improve peripheral AS; no changes in HRV parameters in both protocols, as well as VO2peak. Conclusion: AS and HRV parameters after maximal effort is not functional level-dependent on either health status-dependent in stable patients; exercise intensity is the major factor for exercise prescription in individuals with and without CAD, determining the thin frontier between acute exercise adaptation and imbalance; non-periodized is superior to periodized training to improve peripheral AS in trained CADp.Introdução: O treino físico é potencialmente recomendado para aprimorar a variabilidade da frequência cardíaca (VFC) e a rigidez arterial (RA) em pacientes com doença arterial coronariana (DACp). Objetivos: Analisar os efeitos agudos e crônicos dos estímulos ao exercício (agudos: A- máximo, B- sessões; C- crônico: treinamento) na VFC e RA no DACp. Métodos: Participantes: A- participantes classificados de acordo com a aptidão cardiorrespiratória: DACp não-treinados como muito baixa (MB-DAC; n=18); DACp treinados como baixa (B-DAC; n=18); Indivíduos saudáveis treinados como razoável (R-SAU; n=18); B- DACp treinados (DAC-t, n=18) e indivíduos saudáveis treinados (SAU-t, n=18); C- DACp treinados dividido em grupos periodizado (n=12) e não-periodizado (n=12). Protocolos de exercício: A- protocolo de rampa máximo; B- sessões de exercícios combinados de moderada (SECMO) e alta intensidade (SECAL); C-. treinamento periódico e não periodizado. Resultados: A- DACp e pares saudáveis apresentaram semelhante diminuição da VFC e aumento da RA durante a recuperação. B- SECAL aumentou a velocidade da onda de pulso (VOP) aórtico e diminuiu os parâmetros de alta-frequência durante a recuperação em DAC-t; o efeito do grupo foi encontrado após SECAL na VOP do membro superior; ambos os grupos tiveram respostas semelhantes após o SECMO nos parâmetros de VFC e RA; C- Treinamento não-periodizado foi mais eficaz para aprimorar a RA periférica; nenhuma alteração encontrada nos parâmetros da VFC em ambos os protocolos, bem como no VO2pico. Conclusão: Os parâmetros RA e VFC após o esforço máximo não dependem do nível funcional e do estado de saúde em pacientes estáveis; a intensidade do exercício é o principal fator para a prescrição do exercício em indivíduos com e sem DAC, o que determina a fina fronteira entre adaptação e desequilíbrio agudo ao exercício; treino não-periodizado é superior ao periodizado para aprimorar a RA periférica em DACp treinados

Contribuicao ao estudo do conhecimento de atendentes de enfermagem de bercario a respeito de suas atribuicoes no aleitamento natural de recem-nascido normal

BV UNIFESP: Teses e dissertaçõe

Thermodynamics Of Micellization Of Homologous Series Of Alkyl Mono And Di-glucosides In Water And In Heavy Water

In this study, isothermal titration calorimetry was used to follow the micellization of two homologous series of alkylglucoside surfactants from heptyl to nonylmonoglucosides and from octyl to dodecyldiglucosides over the temperature range from (15 to 65) °C. These measurements allowed the calculation of the thermodynamic parameters associated with micelle formation, viz.: Gibbs free energy, enthalpy, entropy and heat capacity changes. Moreover, micellization of one of these surfactants, nonylmonoglucoside, was also investigated in heavy water, D2O, at different temperatures for comparison. Overall, these results conformed very well with the behaviour displayed by other surfactants with respect to changes within the homologous series. Use of additivity schemes provided estimates of contributions from the polar head group and the methylene units to these thermodynamic functions. The good agreement between the results for alkylglucosides micellization and literature data for other surfactants confirms that, with respect to the hydrophobic interior, their micelles display similar properties. The same can be said about the temperature dependence for micellization, which follows that of other surfactants. Two specific issues were investigated. First the contributions from one versus two glucoside units in the surfactant chemical structure were assessed, which turned out to be essentially the same because the data for the two families of surfactants could be superimposed within their experimental uncertainty. The second addressed possible differences regarding micelle formation in normal and heavy water. In this respect, data for the micellization of one of these surfactants provided values for the thermodynamic functions in D2O that could be considered only slightly different from those in H2O. © 2014 Elsevier Ltd. All rights reserved.73218223Hill, K., Von Rybinski, W., Stoll, G., (1997) Alkyl Polyglycosides: Technology, Properties and Applications, , Wiley WeinheimBury, C., Browning, R., (1953) Trans. Faraday Soc., 49, p. 209Shinoda, K., Yamanaka, T., Kinoshita, K., (1959) J. Phys. Chem., 63, p. 648Reimer, J., Nilsson, M., Álvarez Chamorro, M., Söderman, O., (2005) J Colloid Interface Sci., 287, p. 326Majhi, P.R., Blume, A., (2001) Langmuir, 17, p. 3844Capalbi, A., Gente, G., La Mesa, C., (2004) Colloids Surf. A, 246, p. 99Tsamaloukas, A.D., Beck, A., Heerklotz, H., (2009) Langmuir, 25, p. 4393Keller, S., Broecker, J., (2013) Langmuir, 29, p. 8502Olofsson, G., Loh, W., (2009) J. Braz. Chem. Soc., 20, p. 577Gill, S.J., Dec, S.F., Olofsson, G., Wadsö, I., (1985) J. Phys. Chem., 89, p. 3758Frank, H.S., Evans, M.W., (1945) J. Chem. Phys., 13, p. 507Tanford, C., (1973) The Hydrophobic Effect: Formation of Micelles and Biological Membranes, , Wiley-Interscience New YorkBastos, M., Briggner, L.-E., Shehatta, I., Wadso, I., (1990) J. Chem. Thermodyn., 22, p. 1181Olofsson, G., Berling, D., Markova, N., Molund, M., (2000) Thermochim. Acta, 347, p. 31Adão, R., Bai, G., Loh, W., Bastos, M., (2012) J. Chem. Thermodyn., 52, p. 57Mujerjee, P., Mysels, K.J., (1979) Pure Appl. Chem., 51, p. 1083Chen, L.J., Lin, S.Y., Huang, C.C., (1998) J. Phys. Chem. B, 102, p. 4350Kresheck, G.C., (2006) J. Colloid Interface Sci., 298, p. 432Liu, L., Guo, Q.-X., (2001) Chem. Rev., 3, p. 673Hummer, G., Garde, S., Garcia, A.E., Pratt, L.R., (2000) Chem. Phys., 258, p. 349Hao, J., Dong, R., (2010) Chem. Rev., 110, p. 4978Chen, L.-J., Sheu, Y.-H., Li, P.J., (2004) J. Phys. Chem. B, 108, p. 19096Shimizu, S., Pires, P.A.R., Loh, W., El Seoud, O.A., (2004) Colloid Polym. Sci., 282, p. 1026Loh, W., Spitzer, M., Sabadini, E., (2002) J. Braz. Chem. Soc., 13, p. 7Loh, W., Spitzer, M., Sabadini, E., (2002) J. Phys. Chem. B, 106, p. 12448Kocherbitov, V., Söderman, O., (2004) Langmuir, 8, p. 3056Gill, S.J., Wadsö, I., (1976) Proc. Natl. Acad. Sci. USA, 73, p. 2955Jolicoeur, C., Philip, P.R., (1834) Can. J. Chem., 1974, p. 52Kresheck, G.C., (1998) J. Phys. Chem. B, 102, p. 6596Ericsson, C., Söderman, O., Garamus, V.M., Bergström, M., Ulvenlund, S., (2004) Langmuir, 20, p. 140

Acute and long-term effects of combined exercise training on vascular and autonomic function in patients with coronary artery disease

Introduction: Exercise training is potentially recommended to improve heart rate variability (HRV) and arterial stiffness (AS) in coronary artery disease patients (CADp). Purposes: To analyse the acute and chronic effects of exercise stimuli (acute: A- maximal, B- bouts; chronic: C- training) on cardiac-ANS and AS in CADp. Methods: Participants: A- participants classified according to cardiorespiratory fitness: Untrained CADp as Very Poor-Fit (VPFIT-CAD; n=18); Trained CADp as Poor-Fit (PFIT-CAD; n=18); Trained healthy match individuals as Fair-Fit (FFIT-HY; n=18); B- trained CADp (CAD-t, n=18) and trained healthy individuals (HY-t, n=18); C- trained CADp divided in periodized (n=12) and non-periodized (n=12) groups. Exercise protocol: A- maximal ramp protocol; B- moderate (MOCEB) and high intensity (HICEB) combined exercise bouts; C-. periodized and non-periodized training. Results: A- CADp and healthy peers had similar HRV decrease, and AS increase during recovery. B- HICEB increased aortic- pulse wave velocity (PWV) and decrease high-frequency parameters during recovery in CAD-t; group-effect was found after HICEB on upper limb-PWV; both groups had similar responses after MOCEB on HRV and AS parameters; C- Non-periodized training was more effective to improve peripheral AS; no changes in HRV parameters in both protocols, as well as VO2peak. Conclusion: AS and HRV parameters after maximal effort is not functional level-dependent on either health status-dependent in stable patients; exercise intensity is the major factor for exercise prescription in individuals with and without CAD, determining the thin frontier between acute exercise adaptation and imbalance; non-periodized is superior to periodized training to improve peripheral AS in trained CADp.Introdução: O treino físico é potencialmente recomendado para aprimorar a variabilidade da frequência cardíaca (VFC) e a rigidez arterial (RA) em pacientes com doença arterial coronariana (DACp). Objetivos: Analisar os efeitos agudos e crônicos dos estímulos ao exercício (agudos: A- máximo, B- sessões; C- crônico: treinamento) na VFC e RA no DACp. Métodos: Participantes: A- participantes classificados de acordo com a aptidão cardiorrespiratória: DACp não-treinados como muito baixa (MB-DAC; n=18); DACp treinados como baixa (B-DAC; n=18); Indivíduos saudáveis treinados como razoável (R-SAU; n=18); B- DACp treinados (DAC-t, n=18) e indivíduos saudáveis treinados (SAU-t, n=18); C- DACp treinados dividido em grupos periodizado (n=12) e não-periodizado (n=12). Protocolos de exercício: A- protocolo de rampa máximo; B- sessões de exercícios combinados de moderada (SECMO) e alta intensidade (SECAL); C-. treinamento periódico e não periodizado. Resultados: A- DACp e pares saudáveis apresentaram semelhante diminuição da VFC e aumento da RA durante a recuperação. B- SECAL aumentou a velocidade da onda de pulso (VOP) aórtico e diminuiu os parâmetros de alta-frequência durante a recuperação em DAC-t; o efeito do grupo foi encontrado após SECAL na VOP do membro superior; ambos os grupos tiveram respostas semelhantes após o SECMO nos parâmetros de VFC e RA; C- Treinamento não-periodizado foi mais eficaz para aprimorar a RA periférica; nenhuma alteração encontrada nos parâmetros da VFC em ambos os protocolos, bem como no VO2pico. Conclusão: Os parâmetros RA e VFC após o esforço máximo não dependem do nível funcional e do estado de saúde em pacientes estáveis; a intensidade do exercício é o principal fator para a prescrição do exercício em indivíduos com e sem DAC, o que determina a fina fronteira entre adaptação e desequilíbrio agudo ao exercício; treino não-periodizado é superior ao periodizado para aprimorar a RA periférica em DACp treinados

Thermodynamics of micellization of alkylglucosides in H2O and D2O

Orientador: Watson LohDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de QuimicaResumo: Alquilglicosídeos (AG) são surfatantes não-iônicos totalmente provenientes de fontes naturais e renováveis, além de serem totalmente biodegradáveis e atóxicos. Neste trabalho estudou-se a termodinâmica de micelização desta classe de surfatantes através das técnicas de calorimetria diferencial de varredura (DSC) e titulação calorimétrica isotérmica (ITC), em função do número de átomos de carbono presentes em sua cadeia hidrofóbica e do número de unidades glicosídicas em sua parte polar. Estas propriedades foram determinadas em H2O e em D2O. Para um mesmo AG, o aumento de temperatura implica em uma energia de Gibbs, DmicG, mais favorável à micelização. Com o aumento de temperatura, a variação de entalpia, DmicH, passa de positiva para negativa e o termo entrópico, TDmicS, perde sua contribuição para a micelização. Quando comparados surfatantes de mesmo número de átomos de carbono na cadeia alquílica, mono e di-glicosídeos apresentam estritamente o mesmo comportamento termodinâmico. Heptilglicosídeo apresentou comportamento distinto dos demais surfatantes estudados, indicando que o ambiente químico no interior de sua micela é diferente. Estudos da micelização nos dois solventes mostraram que a maior energia coesiva de D2O, comparada a H2O, implica numa maior contribuição entrópica ao processo de micelização, mas não altera significativamente a energia de GibbsAbstract: Alkylglucosides (AG) are non-ionic surfactants obtained from natural raw materials, which are also totally biodegradable and non-toxic. This study investigated the thermodynamics of their micellization using the techniques of differential scanning calorimetry (DSC) and isothermal titration calorimetry (ITC), for a series of homologues varying their alkyl chain lengths and number of glucoside units (one or two). Some studies were conducted in D2O too, and compared with the results in H2O. As temperature increases, the micellization process becomes more favorable, as measured by a more negative DmicG. In parallel, the enthalpic contribution, DmicH, changes from positive to negative and the entropic term, TDmicS, reduces it positive value. These trends agree well with those reported for other families of surfactants. When AGs of the with the same alkyl chain length are compared, mono and diglucosides display the same thermodynamic functions for micellization. Only for the heptyl homologue of the monoglucoside family, results are slightly out of the general trend observed for the other AG, possibly due to different micelle structure being formed by this smaller surfactant. Comparison of results obtained in D2O with H2O confirmed that the greater cohesive energy of the former leads to a larger entropic contribution to micellization, but with no significant change in the Gibbs energy valuesMestradoFísico-QuímicaMestre em Químic

Thermodynamics of micellization of homologous series of alkyl mono and di-glucosides in water and in heavy water

n this study, isothermal titration calorimetry was used to follow the micellization of two homologous series of alkylglucoside surfactants from heptyl to nonylmonoglucosides and from octyl to dodecyldiglucosides over the temperature range from (15 to 65) degrees C. These measurements allowed the calculation of the thermodynamic parameters associated with micelle formation, viz.: Gibbs free energy, enthalpy, entropy and heat capacity changes. Moreover, micellization of one of these surfactants, nonylmonoglucoside, was also investigated in heavy water, D2O, at different temperatures for comparison. Overall, these results conformed very well with the behaviour displayed by other surfactants with respect to changes within the homologous series. Use of additivity schemes provided estimates of contributions from the polar head group and the methylene units to these thermodynamic functions. The good agreement between the results for alkylglucosides micellization and literature data for other surfactants confirms that, with respect to the hydrophobic interior, their micelles display similar properties. The same can be said about the temperature dependence for micellization, which follows that of other surfactants. Two specific issues were investigated. First the contributions from one versus two glucoside units in the surfactant chemical structure were assessed, which turned out to be essentially the same because the data for the two families of surfactants could be superimposed within their experimental uncertainty. The second addressed possible differences regarding micelle formation in normal and heavy water. In this respect, data for the micellization of one of these surfactants provided values for the thermodynamic functions in D2O that could be considered only slightly different from those in H2O73218223CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPES