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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.
191

EFEITO DE CICLOS DE POLIMERIZAÇÃO EM MICRO-ONDAS SOBRE PROPRIEDADES FÍSICAS, QUÍMICA E BIOLÓGICA DE RESINAS ACRÍLICAS PARA BASE DE PRÓTESE / Effect of microwave polymerization cycles on physical, chemical and biological properties of denture base acrylic resins

Figuerôa, Rosana Marques Silva 12 February 2016 (has links)
Made available in DSpace on 2017-07-24T19:22:01Z (GMT). No. of bitstreams: 1 Rosana Marques Silva Figueroa.pdf: 3807885 bytes, checksum: 3650be97bf0d582c6f9fac01fcff5ea1 (MD5) Previous issue date: 2016-02-12 / Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Paraná / The aim of this study was to determine a microwave polymerization cycle that resulted in adequate physicomechanical and biological properties for the denture base acrylic resins polymerized in water bath (Vipi Cril-VC, VIPI®) or processed by microwave energy (Vipi Wave-VW, VIPI®). The evaluated polymerization cycles were: 1) WB (water bath) = (65ºC during 90 min + boiling during 90 min), recommended cycle for the VC resin; 2) M630/25 = 10 min at 270 W + 5 min at 0 W + 10 min at 360 W, recommended cycle for VW resin; 3) M650/5 = 5 min at 650 W; 4) M550/3 = 3 min at 550 W. The following properties were evaluated: degree of conversion (n=6), cytotoxicity (n=9), porosity (n=10), water sorption and solubility (n=10), and surface roughness and color stability (n=5) after immersion in potential colorant beverages and simulated toothbrushing. Data were submitted to analysis of variance ANOVA-2 way followed by Bonferroni’s test for degree of conversion and color stability, ANOVA-2 way for porosity and cytotoxicity, ANOVA-2 way followed by HSD Tukey’s test for water sorption and solubility, and ANOVA-3 way followed by Bonferroni’s test for surface roughness (α=0.05). For VC resin, there was no significant difference among the groups for degree of conversion. For VW resin, the lowest degree of conversion values appeared in the M630/25 and M650/5 cycles (P<0.05). Degree of conversion values ranged from 66.9 to 85.9%. There was no difference between the materials and experimental groups for cytotoxicity and all conditions resulted in non-cytotoxic effects. Porosity mean values below 1.52% with no significant difference among groups for both materials were observed. Resins showed water sorption and solubility values without a significant difference. The highest water sorption (2.43%) and solubility (0.13%) values were obtained for WB and M550/3, respectively (P<0.05). After immersion in coffee, M550/3 and WB groups of VC resin showed the highest and the lowest roughness values, respectively (P<0.05). There was also an increase in roughness of M550/3 group after immersion in wine (P<0.05). For VW resin, M650/5 group presented rougher surface after immersion in coffee (P<0.05). There was no difference in color among cycles for VW resin and VC resin showed more changes (P<0.05). All medium values were classified as acceptable, exception for VW resin (M630/25 group) which presented NBS=4.88 after immersion in wine. Vipi Cril conventional resin can be polymerized in microwave without impairment to the evaluated properties. According to the obtained results, the better experimental condition was the microwave polymerization at 650 W for 5 min for Vipi Cril. / O objetivo deste estudo foi determinar um ciclo de polimerização em micro-ondas que resultasse em propriedades físico-químicas e biológicas satisfatórias para resinas acrílicas termopolimerizáveis para base de prótese processadas em banho de água (Vipi Cril-VC, VIPI®) ou por energia de micro-ondas (Vipi Wave-VW, VIPI®). Os ciclos de polimerização avaliados foram: 1) BA (banho de água) = (65ºC por 90 min + 90 min em ebulição), ciclo recomendado para a resina VC; 2) M630/25 = 10 min a 270 W + 5 min a 0 W + 10 min a 360 W, ciclo recomendado para a resina VW; 3) M650/5 = 5 min a 650 W; 4) M550/3 = 3 min a 550 W. Foram avaliadas as seguintes propriedades: grau de conversão (n=6), citotoxicidade (n=9), porosidade (n=10), sorção de água e solubilidade (n=10) e rugosidade de superfície e estabilidade de cor (n=5) após imersão em líquidos potencialmente corantes e escovação simulada. Os resultados obtidos foram submetidos à análise de variância ANOVA-2 fatores seguida pelo teste de Bonferroni para grau de conversão e estabilidade de cor, ANOVA-2 fatores para porosidade e citotoxicidade, ANOVA-2 fatores seguida pelo teste de Tukey HSD para sorção de água e solubilidade e ANOVA-3 fatores seguida pelo teste de Bonferroni para rugosidade de superfície (α=0,05). Não houve diferença significante entre os grupos para os resultados de grau de conversão da resina VC. Para a resina VW, os valores mais baixos de grau de conversão foram obtidos nos ciclos M630/25 e M650/5 (P<0,05). Os valores médios de grau de conversão foram entre 66,9% e 85,9%. Não houve diferença entre os materiais e os grupos experimentais para os resultados de citotoxicidade e todas as condições resultaram em efeitos não citotóxicos. Foram observados valores médios de porosidade inferiores a 1,52%, sem diferença significante entre os grupos para ambos os materiais. As resinas apresentaram valores de sorção de água e solubilidade sem diferença estatisticamente significante entre elas. Os valores mais altos de sorção de água (2,43%) e de solubilidade (0,13%) foram obtidos nos grupos BA e M550/3, respectivamente (P<0,05). Com a imersão em café, os grupos M550/3 e BA da resina VC apresentaram os maiores e os menores valores de rugosidade de superfície, respectivamente (P<0,05). Também houve aumento da rugosidade do grupo M550/3 após imersão no vinho tinto (P<0,05). Para a resina VW, o grupo M650/5 demonstrou superfície mais rugosa após imersão em café (P<0,05). Não houve diferença de cor entre os ciclos para a resina VW e a resina VC apresentou mais alterações (P<0,05). Todos os valores médios de estabilidade de cor foram classificados como aceitáveis, exceto para a resina VW (grupo M630/25) que apresentou NBS=4,88 após imersão em vinho tinto. A resina Vipi Cril formulada para polimerização convencional pôde ser polimerizada em micro-ondas sem prejuízo às suas propriedades avaliadas. De acordo com os resultados obtidos, a melhor condição experimental foi a polimerização da resina Vipi Cril em micro-ondas a 650 W por 5 min.
192

Preparação e caracterização de microesferas poliméricas à base de metacrilato de glicidila e divinilbenzeno com propriedades magnéticas / Preparation and characterization of polymeric microspheres based on glycidyl methacrylate and divinylbenzene with magnetic properties

Carla do Nascimento Queiroz 31 March 2011 (has links)
Nesta Dissertação, foram sintetizadas microesferas poliméricas com propriedades magnéticas à base de metacrilato de glicidila e divinilbenzeno pela técnica de polimerização em suspensão. O material utilizado para conferir as propriedades magnéticas ao copolímero foi magnetita sintetizada no laboratório. Foram estudados os efeitos da modificação da magnetita com ácido oleico, da velocidade de agitação, do teor de agente reticulante, do teor de material magnético adicionado e do teor de agente de suspensão sobre as características das partículas poliméricas obtidas. As microesferas foram caracterizadas quanto ao seu aspecto morfológico, à estabilidade térmica, à incorporação de material magnético e quanto às suas propriedades magnéticas. A quantidade de partículas de ferro incorporadas foi afetada pela velocidade de agitação durante a síntese, pelo teor de material magnético adicionado, pela fase de dispersão do material magnético e pelo teor de monômeros no copolímero. A estabilidade térmica dos copolímeros foi afetada, principalmente, pelo teor de material magnético incorporado e pelo teor de monômeros, levando em consideração resinas com a mesma quantidade de material magnético adicionado. A magnetização de saturação para as microesferas foi afetada pelo teor de material magnético incorporado. A modificação da superfície da magnetita com ácido oleico foi considerada importante para a incorporação do material magnético na matriz do copolímero.Partículas poliméricas magnéticas com comportamento superparamagnéticos foram obtidas com morfologia esférica e magnetização de saturação de 7,11 (emu/g), utilizando razão molar de monômeros de 50/50 %, 1 % de PVA, 20 % de magnetita modificada com ácido oleico adicionada à fase orgânica e velocidade de agitação mecânica de 500 rpm / In this dissertation, polymeric microspheres with magnetic properties based on glycidyl methacrylate and divinylbenzene were synthesized by suspension polymerization technique. In order to obtain magnetic properties, magnetite particles modified by oleic acid were synthesized in laboratory. The effects of stirring rate, concentration of crosslink, the concentration of magnetite added and the concentration of stabilizer on the particles properties were studied. The magnetic microspheres were characterized according their morphology, thermal stability, incorporation of magnetite and their magnetic properties. The incorporate of iron particles content was mainly affected by stirring rate during the synthesis, by the content of magnetic material added, by the dispersion phase of magnetic material and by the monomers content in the copolymer. The thermal stability of copolymers was mainly affected by the content of magnetic material incorporated and by the monomers content, taking in account the resins with the same content of magnetic material added. The saturation magnetization for the microspheres was effected by the content of magnetic material incorporated. The modification with oleic acid was considered important to the incorporation of the magnetic material in the copolymer matrix.Magnetic polymeric particles with superparamagnetic behavior have been obtained with spherical morphology and saturation magnetization of 7.11 (emu/g). It was used monomers molar ratio of 50/50 %, 1% PVA, 20 % magnetite particles modified by oleic acid dispersion on organic phase and stirring rate of 500 rpm during the synthesis
193

Organopolymérisations du méthacrylate de méthyle induites par les carbène N-hétérocycliques et par des paires de Lewis organiques / Organopolymerizations of methyl methacrylate directly induced by N-heterocyclic carbenes and by metal-free Lewis pairs

Nzahou Ottou, Winnie 18 December 2014 (has links)
Deux carbènes N-hétérocycliques (NHCs) de type imidazol-2-ylidène ont été étudiés en tant qu’amorceurs organiques pour la polymérisation directe de monomères vinyliques de type (méth)acrylates d’alkyle, principalement le méthacrylate de méthyle(MMA), en l’absence tout autre activateur. Une différence de réactivité a été mise en évidence en fonction des substituants du carbène et de la nature du substrat. Des études théoriques ont permis de rationaliser les résultats expérimentaux par l’influence des effets électroniques et stériques intervenant au cours des réactions mises en jeu. Un NHC en particulier a été ensuite utilisé comme véritable catalyseur de la polymérisation du MMA en présence d’alcools comme amorceurs. En utilisant des macroamorceurs hydroxylés de type poly(oxyde d’éthylène), des copolymères amphiphiles ontété ainsi synthétisés. Des études théoriques ont encore une fois permis d’identifier les mécanismes réactionnels de cette polymérisation. Enfin, des paires de Lewis composées d’un acide à base de silicium et d’une base de typeNHC ou phosphine trialkyle(aryle) ont été ensuite utilisées comme système d’activation de polymérisation du MMA. Ce type de polymérisation est basé sur une activation duale du monomère par effet coopératif de la base et de l’acide. / The reactivity of imidazol-ylidene N-heterocyclic carbenes (NHCs) as direct initiators for the polymerization of miscellaneous (meth)acrylic monomers, mainly methylmethacrylate (MMA), has been screened in the absence of any other co-activator.Different reactivities have been observed according to the structure of the NHC and thenature of the substrate. Computational studies allowed rationalizing steric and electroniceffects involved in these reactions.The use of a peculiar NHCs as catalyst for the polymerization of MMA using alcohols as initiators has then been investigated. This simple and efficient method also allows achieving amphiphilic block copolymers by using hydroxylated poly(ethylene oxide)s asmacro-initiators. Combined computational and experimental investigations have provided insights into the mechanism of polymerization.Various Lewis pairs including a silicon-based compound as acid and NHC or a trialkyl(aryl)phosphine as base, have been investigated to trigger an efficient polymerization of MMA.In this case, the polymerization is expected to proceed via a cooperative/dual activation mechanism.
194

Terminierungskinetik radikalischer Homo- und Copolymerisationen bis zu hohen Monomerumsätzen / Termination kinetics of free-radical homo- and copolymerisations up to high degrees of monomer conversion

Feldermann, Achim 03 July 2003 (has links)
No description available.
195

Kinetische und thermodynamische Untersuchungen der Hochdruck-Copolymerisation von Ethen mit (Meth)Acrylsäureestern / Kinetic and thermodynamic Studies of the High-Pressure Copolymerization of Ethene and (Meth)acrylic acidesters

Latz, Henning 29 April 2004 (has links)
No description available.
196

Kinetik von Atom-Transfer Radikalischen Polymerisationen bis zu hohen Drücken / Kinetics of Atom-Transfer Radical Polymerization up to High Pressure

Morick, Joachim 26 September 2012 (has links)
No description available.
197

Linear block copolymers of L–lactide and 2–dimethylaminoethyl methacrylate : synthesis and properties

Kryuchkov, Maksym 02 1900 (has links)
Les copolymères séquencés amphiphiles sont très prometteurs pour des applications de technologie de pointe en raison de leur capacité à s'auto-assembler dans des structures bien organisées à l'échelle du micro– et du nanométre, et de leur sensibilité à des stimulations de différentes natures. La formation des nanomotifs bien ordonnés dans les films et/ou en masse fournit un substitut à la nanolithographie et est utile pour le design et l'ingénierie de nanomembranes et de matériaux nanoporeux. L'auto–assemblage dans des solvants sélectifs, en incluant la sensibilité au pH et à la température, peut être ajusté pour correspondre aux besoins de différentes applications biomédicales, telles que l’encapsulation et/ou relargage de médicaments, l'ingénierie de tissus, etc. Dans ce contexte, des copolymères séquencés de type L–lactide (LLA) et méthacrylate 2–diméthylaminoéthyl (DMAEMA) sont d’un grand intérêt. Comme le contrôle sur l'auto–assemblage des copolymères séquencés est permis au niveau moléculaire, il est très important de préparer des copolymères bien définis avec des longueurs de bloc prévisibles et de faible polydispersité. Ainsi, une partie de cette étude a été consacrée au développement de procédures synthétiques optimales et à la caractérisation détaillée de copolymères di– et triblocs de LLA et de PDMAEMA. Un outil simple pour déterminer la présence d'homo–PLLA résiduel a été développée; cela a permis de déterminer et d'expliquer plusieurs voies de synthèse indésirables. La dernière inclut la participation possible de l'amorceur bifonctionnel utilisé, et nous avons alors proposé un système alternatif d'amorceur bifonctionnel/catalyseur. La racémisation du LLA par les unités amine de (P)DMAEMA a été observée pendant la polymérisation, limitant ainsi l'utilisation première du bloc PDMAEMA pour la préparation des copolymères PLLA–b–PDMAEMA. Les études thermiques et de cristallisation, en incluant les copolymères séquencés partiellement quaternisés, ont révélé un retard significatif de la vitesse de cristallisation, en présence du bloc de PDMAEMA. Nous avons constaté que les blocs sont miscibles pour de faibles masses molaires et que la miscibilité partielle est maintenue après quaternisation. Selon la longueur et le taux de quaternisation du bloc PDMAEMA, la cristallisation du PLLA a été étudiée dans un environnement restreint et confiné, faiblement ou fortement. La torsion des lamelles cristallines observée pour certains copolymères biséquencés a été accentuée dans les copolymères triséquencés, où la formation de sphérolites annelés a été observée dans toutes les conditions thermiques utilisées. / Multi–functional amphiphilic block copolymers have much promise for various high technology applications thanks to the controlled stimuli–responsive self–assembly into well–organized structures on the micro– and nanometer scales. The formation of well–ordered nanopatterns in films and/or in bulk provides a competitive substitute to nanolithography and is useful in the design and engineering of nanomembranes and nanoporous materials. Solution self–assembly in selective solvents, including pH and temperature sensitivity, can be tuned to match the needs of different biomedical applications, such as drug encapsulation/delivery, tissue engineering, etc. In this context, block copolymers of L–lactide (LLA) and 2–dimethylaminoethyl methacrylate (DMAEMA) are of great interest. Since the control over self–assembly of block copolymer systems is enabled on a molecular level, it is of great importance to prepare well–defined block copolymers with predictable block lengths and low polydispersity. Thus, a major part of the research in this study was devoted to developing optimal synthetic procedures with detailed characterization of linear di– and triblock copolymers of LLA and PDMAEMA. A simple tool to determine homo–PLLA impurity was developed, which helped to determine and explain several undesired routes. The latter includes possible involvement of the bifunctional initiator used, and an alternative bifunctional initiator/catalyst system was proposed. Racemization of LLA by (P)DMAEMA moieties was observed during LLA polymerization thus limiting the utilization of PDMAEMA–first approach for the preparation of PLLA–b–PDMAEMA. Thermal and crystallization studies, including on quaternized block copolymers, revealed a significant retardation effect of the PDMAEMA block on the crystallization kinetics. The blocks were found to be miscible in the melt at low molecular weights, and maintained partial miscibility after quaternization. Depending on the length and the quaternization degree of PDMAEMA, PLLA crystallization was studied in a templated, soft or hard confinement environment. Crystalline lamellae twisting observed in certain diblock copolymers was facilitated in triblock copolymers, where the formation of banded spherulites was observed in all thermal conditions used. / Part of the research described in this thesis is conducted in collaboration with Centre d' étude et de Recherche sur les Macromolécules (CERM), Université de Liège, Sart-Tilman, Belgium
198

Preparação e caracterização de microesferas poliméricas à base de metacrilato de glicidila e divinilbenzeno com propriedades magnéticas / Preparation and characterization of polymeric microspheres based on glycidyl methacrylate and divinylbenzene with magnetic properties

Carla do Nascimento Queiroz 31 March 2011 (has links)
Nesta Dissertação, foram sintetizadas microesferas poliméricas com propriedades magnéticas à base de metacrilato de glicidila e divinilbenzeno pela técnica de polimerização em suspensão. O material utilizado para conferir as propriedades magnéticas ao copolímero foi magnetita sintetizada no laboratório. Foram estudados os efeitos da modificação da magnetita com ácido oleico, da velocidade de agitação, do teor de agente reticulante, do teor de material magnético adicionado e do teor de agente de suspensão sobre as características das partículas poliméricas obtidas. As microesferas foram caracterizadas quanto ao seu aspecto morfológico, à estabilidade térmica, à incorporação de material magnético e quanto às suas propriedades magnéticas. A quantidade de partículas de ferro incorporadas foi afetada pela velocidade de agitação durante a síntese, pelo teor de material magnético adicionado, pela fase de dispersão do material magnético e pelo teor de monômeros no copolímero. A estabilidade térmica dos copolímeros foi afetada, principalmente, pelo teor de material magnético incorporado e pelo teor de monômeros, levando em consideração resinas com a mesma quantidade de material magnético adicionado. A magnetização de saturação para as microesferas foi afetada pelo teor de material magnético incorporado. A modificação da superfície da magnetita com ácido oleico foi considerada importante para a incorporação do material magnético na matriz do copolímero.Partículas poliméricas magnéticas com comportamento superparamagnéticos foram obtidas com morfologia esférica e magnetização de saturação de 7,11 (emu/g), utilizando razão molar de monômeros de 50/50 %, 1 % de PVA, 20 % de magnetita modificada com ácido oleico adicionada à fase orgânica e velocidade de agitação mecânica de 500 rpm / In this dissertation, polymeric microspheres with magnetic properties based on glycidyl methacrylate and divinylbenzene were synthesized by suspension polymerization technique. In order to obtain magnetic properties, magnetite particles modified by oleic acid were synthesized in laboratory. The effects of stirring rate, concentration of crosslink, the concentration of magnetite added and the concentration of stabilizer on the particles properties were studied. The magnetic microspheres were characterized according their morphology, thermal stability, incorporation of magnetite and their magnetic properties. The incorporate of iron particles content was mainly affected by stirring rate during the synthesis, by the content of magnetic material added, by the dispersion phase of magnetic material and by the monomers content in the copolymer. The thermal stability of copolymers was mainly affected by the content of magnetic material incorporated and by the monomers content, taking in account the resins with the same content of magnetic material added. The saturation magnetization for the microspheres was effected by the content of magnetic material incorporated. The modification with oleic acid was considered important to the incorporation of the magnetic material in the copolymer matrix.Magnetic polymeric particles with superparamagnetic behavior have been obtained with spherical morphology and saturation magnetization of 7.11 (emu/g). It was used monomers molar ratio of 50/50 %, 1% PVA, 20 % magnetite particles modified by oleic acid dispersion on organic phase and stirring rate of 500 rpm during the synthesis
199

Síntese e caracterização de materiais híbridos siloxano-PMMA dopados com íons Eu(III)

Santos, Simei Tarse Sobrinho 28 March 2014 (has links)
In this work siloxane-polymethyl methacrylate (PMMA) hybrid materials were synthesized and doped with Eu (III) from solid europium chloride, solid europium (III) nitrate, europium chloride (III) in alcoholic solution and 3-aminopyrazine-2-carboxylate of lanthanum and europium complex. The hybrid was prepared from methyl methacrylate (MMA) and 3-methacryloxy-propyl-trimethoxysilane (MPTS), using benzoyl peroxide (BPO) as polymerization initiator. The use of the sol-gel method by acid catalysis allowed to obtain pure solid materials and doped with europium different sources with amorphous characteristics, as evidenced by the X-ray diffraction powderdata. The insertion of the europium complex in the polycrystalline matrix did not changethe structural characteristics of the samples. It was observed that the materials doped with europium in solution, showed greater adsorbed amounts of solvents and structural features that changethe spectroscopic properties. The samples containing solid salts showed similar structural features. It was observed that the average life time of the radioactive emissions increase with the heat treatment, indicating that the temperature reduces the number of suppressor luminescence groups in the coordinationenvironment oflanthanides ion and the character non monoexponentialof the decay is indicative of the presence different coordination environments. In the 29Si NMR measurementsfor samples containing alcoholic solution of europium chloride are observed monomer (RSi(OSi)(OH)2), diimeric(R-Si(OSi)2(OH)) and fully condensed (RSi(OSi)3)species,having a polycondensationdegree up to 78% . The materialsdoped with europium complex show strong luminescence, except tosamples treated at 200 ° C, which is indicative of thermal degradation of the coordination complex. It was observed that presence of solvent changedthermal stability, different heat treatments and europium sources exerted strong influence on the coordination environment of the Eu (III) ions in the organic -inorganic hybrid materials. / Neste trabalho materiais híbridos Siloxano-Polimetacrilato de metila (PMMA) foram sintetizados e dopados com íons Eu(III) provenientes de cloreto e nitrato de európio (III) sólidos, cloreto de európio (III) em solução alcoólica e complexo 3-aminopirazina-2-Carboxílato de lantânio e európio. O hibrido foi preparado a partir dometacrilato de metila (MMA) e do 3-metacriloxi-propil-trimetoxisilano (MPTS), utilizando-se como agente inicializador de polimerização o peróxido de benzoila (BPO). A utilização dametodologia de síntese sol-gel por catálise ácida possibilitou a obtenção de materiais sólidos puros e dopados com diferentes fontes de európio, com características amorfas, como ficou evidente pelos dados de difração de raios X de pó. A inserção de complexo de európiopolicristalino na matriz não alterou as características estruturais da amostra.Observou-se que os materiais que foram dopados com európio em solução, apresentaram maior quantidade de solventes adsorvidos e características estruturais que alteraram as suas propriedades espectroscópicas. As amostras dopadas com sais sólidos apresentaram características estruturais semelhantes. Observou-se que os tempos de vida médios das emissões radiativas aumentam com o tratamento térmico, o que indica que o tratamentoreduz o número de grupos supressores de luminescência no ambiente de coordenação do íon lantanídeo e o caráter não monoexponencial do decaimento é indicativo da presença de diferentes ambientes de coordenação. Pelo RMN do 29Si para as amostras dopadas com solução alcoólica de cloreto de európio são observadas espécies monoméricas(R-Si(OSi)(OH)2), diméricas(R-Si(OSi)2(OH)) e totalmente condensadas(R-Si(OSi)3) com um grau de policondensação de até 78%. Os materiais dopados com o complexo apresentam forte luminescência, exceto as amostras tratadas a 200°C, o que é indicativo da degradação térmica do complexo de coordenação. Observou-se que a presença de solvente alterou a estabilidade térmica das amostras, e que a diferentes tratamentos térmicos e a dopagem com diferentes fontes de európio influenciaram sensivelmente o ambiente de coordenação dos íons Eu(III) nos materiais híbridos orgânico-inorgânicos.
200

Inibição da metaloproteinase 2 por dois monômeros amplamente utilizados na formulação de adesivos dentinários / Inhibition of metalloproteinase 2 by two monomers thoroughly used on the dentin bonding formulation.

Carvalho, Rodrigo Varella de 30 January 2009 (has links)
Made available in DSpace on 2014-08-20T14:30:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-01-30 / The aim of this study was to evaluate the effect of different concentrations of 2-hydroxyethyl methacrylate (HEMA) triethyleneglycol dimethacrylate (TEGDMA) on the inhibition of matrix metalloproteinase 2 (MMP-2). Mouse gingival explants were cultured overnight in DMEM and the expression of secreted enzymes was analyzed by gelatin zymography in buffers containing 5 mM CaCl2 (Tris-CaCl2) in 50 mM Tris-HCl buffer with the addition of HEMA and TEGDMA at different concentrations (0.62, 1.25, 2.5 or 5.0% (v/v)). The gelatinolytic proteinase present in the conditioned media was characterized as matrix metalloproteinase by means of specific chemical inhibition with 0.5 mM of EDTA and 0.5 mM of NEM. The matrix metalloproteinases present in the conditioned media were characterized as MMP-2 by immunoprecipitation.The eletrophoretic bands were scanned and the transmittance values were analyzed with ImageJ software. Data was plotted and submitted to linear regression to investigate MMP-2 inhibition as a function of HEMA and TEGDMA concentration. Three major bands were detected in the zymographic assays. Those bands were characterized as MMP-2. Zymogene (72 kDa), intermediate (66 kDa) and active forms of MMP-2 (62 kDa) were inhibited by HEMA and TEGDMA in a dose-dependent way. These findings suggest that HEMA and TEGDMA could inhibit MMP-2 expression even at small concentrations. / O objetivo do presente estudo foi avaliar o efeito de diferentes concentrações de 2-hidroxietil metacrilato (HEMA) e trietilenoglicol dimetacrilato (TEGDMA) na inibição da metaloproteinase da matriz 2 (MMP-2). Tecidos gengivais de ratos foram incubados em DMEM e a expressão das enzimas secretadas foi analisada por zimografia em tampões de incubação contendo 5 mM de CaCl2 (Tris-CaCl2) em 50 mM de Tris-HCl com a adição de diferentes concentrações de HEMA e TEGDMA (0,62; 1,25; 2,5 e 5%) em volume. Para caracterizar as enzimas como MMPs foi realizado ensaio de inibição química específica com 0,5 mM de EDTA (um conhecido inibidor de MMPs) e 0,5 de NEM (um conhecido inibidor de proteinases serinas).Para caracterizar as enzimas como MMP-2 foi realizado o ensaio de imunoprecipitação. As bandas produzidas no gel foram escaneadas e os valores de transmitância foram analizados com o auxílio do programa ImageJ. Os resultados foram submetidos a regressão linear em função da concentração de HEMA e TEGDMA. Três bandas foram identificadas após a zimografia. Essas bandas foram caracterizadas como MMP-2. O zimogênio (72 kDa), a forma intermediária (66 kDa) e a forma ativa da MMP-2 (62 kDa) foram inibidas pelo HEMA e pelo TEGDMA de forma dose-dependente. Nossos resultados sugerem que o HEMA e o TEGDMA podem inibir a expressão da MMP-2 mesmo em pequenas concentrações.

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