Submitted by LUHANA SANTOS GONZALES GARCIA null (luhanagarcia@gmail.com) on 2018-02-21T14:29:52Z No. of bitstreams: 1 Tese Luhana Garcia 2018.pdf: 3564229 bytes, checksum: 01cd5d31429809862bb89d390b0412ab (MD5) / Approved for entry into archive by Claudio Hideo Matsumoto null (claudio@foa.unesp.br) on 2018-02-21T17:58:18Z (GMT) No. of bitstreams: 1 garcia_lsg_dr_araca.int.pdf: 3564229 bytes, checksum: 01cd5d31429809862bb89d390b0412ab (MD5) / Made available in DSpace on 2018-02-21T17:58:18Z (GMT). No. of bitstreams: 1 garcia_lsg_dr_araca.int.pdf: 3564229 bytes, checksum: 01cd5d31429809862bb89d390b0412ab (MD5) Previous issue date: 2018-02-02 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O objetivo geral deste estudo foi avaliar o efeito de um dentifrício fluoretado convencional (1100 ppm F), contendo nanopartículas de hexametafosfato de sódio (HMPnano) sobre a remineralização de lesões artificiais de cárie e desmineralização do esmalte in situ e biofilme. O estudo de remineralização, foi duplo-cego cruzado, realizado em quatro fases de três dias cada. Voluntários (n=12) usaram dispositivos palatinos contendo quatro blocos de esmalte bovino com lesões artificiais de cárie. A seguir foram distribuídos aleatoriamente nos seguintes grupos de tratamento: sem F/HMP/HMPnano (Placebo); 1100 ppm F (1100F); 1100F associado a 0,5% HMP microparticulado e nanoparticulado (1100F/HMP; 1100F/HMPnano). Os voluntários foram instruídos a escovar seus dentes naturais com os dispositivos palatinos na boca durante 1 min (3x/dia), de modo que os blocos foram tratados com slurry de dentifrícios. Após cada fase, determinou-se a porcentagem de recuperação de dureza de superfície (%SHR), recuperação integrada de dureza de subsuperfície (ΔIHR), recuperação mineral integrada (ΔIMR) e concentração de fluoreto (F) no esmalte. Os resultados foram submetidos a análise de variância de medidas repetidas seguido pelo teste Student-Newman-Keuls (p < 0,001). A superfície do esmalte tornou-se 68% mais remineralizada quando tratada com 1100F/HMPnano em comparação com 1100F (p < 0,001). O tratamento com 1100F/HMP e 1100F/HMPnano promoveu um aumento em ~ 23% e ~ 87% da ΔIHR quando comparado ao 1100F (p < 0,001). Além disso, ΔIMR foi de ~ 75% e ~ 33% maior para 1100F/HMPnano quando comparado a 1100F e 1100F/HMP, respectivamente (p < 0,001). O estudo de desmineralização foi duplo-cego cruzado, e consistiu em quatro fases (7 dias cada). Voluntários (n=12) usaram aparelhos palatinos contendo quatro blocos de esmaltes bovinos. O desafio cariogênico foi realizado pela solução de sacarose a 30% (6x/dia). Os tratamentos com os dentífricios (3x/dia) foram os seguintes: sem F/ HMP/HMPnano (Placebo); 1100 ppm F (1100F); 1100F associado a 0,5% HMP microparticulado e nanoparticulado (1100F/HMP; 1100F/HMPnano). Após sete dias determinou-se a porcentagem de perda de dureza de superfície (%SH), perda integrada de dureza subsuperfície (ΔKHN), cálcio (Ca), fósforo (P) e fluoreto (F) no esmalte. Além disso, no biofilme formado sobre os blocos analisou-se as concentrações de polissacarídeos extracelulares (EPS), F, Ca, P. Os resultados foram submetidos a análise de variância de medidas repetidas seguido pelo teste Student-Newman-Keuls (p < 0,001). Resultados: 1100F/HMPnano promoveu menor %SH e ΔKHN quando comparado aos demais grupos (p < 0,001). A adição de HMPnano a 1100F não aumentou a absorção de F e P no esmalte, mas aumentou significativamente as concentrações de Ca (p < 0,001). O grupo 1100F/HMPnano apresentou valores mais baixos de concentração de EPS quando comparado com 1100F (~ 70%) (p < 0,001). Todos os grupos foram supersaturados em relação a hidroxiapatita (HA). Somente, o grupo 1100F/HMPnano foi supersaturado em relação ao fluoreto de cálcio (CaF2) (p < 0,05). As atividades iônicas de íon fluoreto de cálcio (CaF+) e fluoreto de hidrogênio neutro (HF0) para o grupo 1100F/HMPnano foram significativamente maiores quando comparadas aos demais grupos (p < 0,001). Conclui-se que a adição de HMPnano a um dentifrício convencional promoveu um efeito remineralizador significantemente maior em lesões artificiais de cárie e demonstrou um maior efeito protetor contra a desmineralização e variáveis do biofilme in situ. / The aim of this study was to evaluate the effect of a conventional fluoride toothpaste (1100 ppm F) containing nano-sizeds of sodium hexametaphosphate (HMPnano) on the remineralization of artificial caries lesions and enamel demineralization and biofilm in situ. The remineralization study was double-blinded crossed, performed in 4 phases of 3 days each. Volunteers (n = 12) used palatal devices containing four blocks of bovine enamel with artificial lesions of caries. They were then randomly assigned to the following treatment groups: without F/ HMP/HMPnano (Placebo); 1100 ppm F (1100F); 1100F associated with 0.5% HMP microparticulate and nano-sized (1100F/HMP; 1100F/ HMPnano). The volunteers were instructed to brush their natural teeth with the palatine devices in the mouth for 1 min (3x/day), so that the blocks were treated with slurry of toothpastes. After each phase, the percentage of surface hardness recovery (%SHR), integrated recovery of subsurface hardness (ΔIHR), integrated mineral recovery (ΔIMR) and fluoride (F) concentration in the enamel were determined. The results were subjected to analysis of variance of repeated measures followed by Student-Newman-Keuls test (p < 0.001). The enamel surface became 68% more remineralized when treated with 1100F/ HMPnano compared to 1100F (p < 0.001). Treatment with 1100F/HMP and 1100F/ HMPnano promoted an increase in ~ 23% and ~ 87% of ΔIHR when compared to 1100F (p < 0.001). In addition, ΔIMR was ~ 75% and ~ 33% higher for 1100F/HMPnano when compared to 1100F and 1100F/HMP, respectively (p < 0.001). The study of demineralization was double-blinded crossed, and consisted of four phases (7 days each). Volunteers (n = 12) used palatal appliances containing four blocks of bovine enamel. The cariogenic challenge was accomplished by the solution of sucrose 30% (6x/day). Treatments with the toothpaste (3x/day) were as follows: without F/HMP/HMPnano (Placebo); 1100 ppm F (1100F); 1100F associated with 0.5% HMP microparticulate and nano-sized (1100F/HMP; 1100F/HMPnano). After 7 days the percentage of surface hardness loss (%SH), integrated loss of subsurface hardness (ΔKHN), calcium (Ca), phosphorus (P) and fluoride (F) in the enamel were determined. The results were submitted to analysis of variance of repeated measurements followed by the Student-Newman-Keuls test (p < 0.001). The results were analyzed using the Student-Newman-Keuls test (p < 0.001). Results: 1100F/HMPnano promoted lower %SH and ΔKHN when compared to the other groups (p < 0.001). Addition of HMPnano to 1100F did not increase the absorption of enamel F, but significantly increased enamel Ca concentrations (p < 0.001). The 1100F/HMPnano group had lower values of EPS concentration when compared to 1100F (~ 70%) (p < 0.001). All groups were supersaturated with respect to hydroxyapatite (HA). Only, the 1100F/HMPnano group was supersaturated relative to calcium fluoride (CaF2) (p < 0.05). The ionic activities of calcium fluoride ion (CaF+) and neutral hydrogen fluoride (HF0) for the 1100F/HMPnano group were significantly higher when compared to the other groups (p < 0.001). It was concluded that the addition of HMPnano to a conventional toothpaste promoted a significantly greater remineralizing effect on artificial caries lesions and demonstrated a greater protective effect against demineralization and biofilm in situ. / 16/03148-7

Com o aumento do uso do método de síntese por combustão em solução para obtenção de pós cerâmicos, há uma crescente percepção da necessidade de se entender as características únicas deste processo. Esta tese apresenta uma investigação baseada na obtenção de diferentes pós nanoestruturados: Al2O3-α (alumina), Cr2O3 (crômia), Fe2O3-α (hematita), Fe3O4 (magnetita), NiO (bunsenita) e CoO, Co3O4 (óxidos de cobalto), como opção para futuras aplicações. Estes foram caracterizados via ATD, BET, DRX, MET, MEV, VSM, XPS e FTIR. O foco particular deste trabalho é o estudo da razão combustível-oxidante e sua influência nas características dos materiais resultantes. Outros parâmetros de combustão foram identificados e também devidamente avaliados, tais como: tipo de chama, temperatura, gases gerados e composição química dos reagentes precursores. O cálculo termodinâmico da reação de combustão em solução mostrou que, quando a razão combustível-oxidante aumenta, obtêm-se uma elevação da temperatura de chama adiabática e da quantidade de gás produzida, definindo características do particulado como morfologia, tamanho de cristalito, área superficial e nível de agregação. A formação dos óxidos e metais seguiu um comportamento termodinâmico esperado, conforme energia livre de Gibbs. Menores tamanhos de cristalito foram obtidos sempre na condição deficiente em combustível para todos os sistemas estudados. Já a temperatura foi o principal parâmetro de reação que governou a taxa de crescimento e concorreu com a geração de gases para a formação dos cristalitos em certas condições redutoras. Os resultados deste trabalho melhoraram significativamente o entendimento do efeito da razão combustível-oxidante no comportamento das características físicas dos pós. Esta correlação foi avaliada com intuito de fornecer base de conhecimento para possível aplicação desta tecnologia na otimização ou desenvolvimento de novos sistemas de pós. / With the increasing use of solution combustion synthesis method for powder obtaining, there is a growing realization of the need to understand the unique characteristics of this process. This thesis presents the novel investigation of this technique specifically based upon some nanostructured powders such as α - Al2O3 (alumina), Cr2O3 (eskolite), α - Fe2O3 (hematite), Fe3O4 (magnetite), NiO (bunsenite), and CoO, Co3O4 (cobalt oxides) as a core option for future applications. These were characterized via DTA, BET, XRD, TEM, SEM, VSM, XPS, and FTIR. The particular focus of this work is based on the study of the fuel-to-oxidant ratio influence to the characteristics of the resulting materials. Other combustion parameters were identified and also proper appraised as flame type, temperature, gas generation, and chemical composition of precursor reagents. The thermodynamic calculation of the combustion reaction shows that as fuel-tooxidant ratio increases the amount of gas produced, and adiabatic flame temperature also increases. Powder characteristics as morphology, crystallite size, surface area and aggregation degree are mainly governed by the flame temperature, and generation of gases. The oxide and metals formation followed a thermodynamic behavior as expected, conform to Gibbs free energy. Lower crystallite sizes were always obtained by fuel-lean condition for all studied systems. The temperature was the main reaction parameter controlling the growth rate, while it competed with generation of gases to form crystallites under certain reducing conditions. The outcomes of this work have significantly improved the understanding of the fuelto- oxidant ratio effects on the behavior of the physical characteristics of powders. This correlation has been drawn in order to provide a knowledge basis for possible application of this technology to optimize or develop new powder systems.

La synthèse d'acide polyamique (APA) comportant des blocs élastomères de type oligo-oxyéthylène et -oxypropylène et des polyimides correspondants (PEI) a été étudiée et leurs propriétés de perméation gazeuse déterminées pour He, N2, O2, H2, CH4 et CO2. Il a été montré que la présence de la phase élastomère augmentait de façon très importante les coefficients de perméabilité au gaz comparativement aux polyimides aromatiques conventionnels. La perméabilité du CO2, augmentée de façon préférentielle par rapport celles de tous les autres gaz, conduit à des sélectivités idéales tout à fait remarquables, en particulier vis-à-vis de N2 (≈40). L’incorporation de nanoparticules de silice dans les PEI (de 1 à 15% en masse) a été effectuée lors de l’étape de cyclo-déshydratation de l'APA, soit par ajout de silice hydrophobes (16 nm) ou hydrophiles (12 nm), soit par méthode Sol-Gel à partir de précurseurs alcoxysilanes (TMOS et TEOS). L'influence des charges SiO2 sur les propriétés de perméation gazeuse a été étudiée par la méthode du temps de retard (time-lag) essentiellement sur la série préparée avec des particules préformées. On a observé que les nano-charges de silice ne semblent pas interférer dans le processus de cyclisation et que les propriétés mécaniques sont renforcées ; la perméabilité aux gaz varie surtout selon la quantité de charges incorporées mais aucune augmentation spectaculaire de perméabilité n’a pu être observée. On peut en déduire que, vraisemblablement, c’est la phase élastomère qui est le lieu d’incorporation des particules de SiO2. Ces résultats montrent l’intérêt des membranes PEI et PEI/SiO2 dans des applications industrielles de séparation de gaz, notamment pour la séparation de mélanges CO2/N2 / The synthesis of polyamic acids (PAA) with oligo-oxyethylene and -oxypropylene rubbery blocks and the related polyimides (PEI) has been studied and their gas permeation properties determined for He, N2, O2, H2, CH4 and CO2. It was shown that the rubbery phase dramatically increased the gas permeability coefficients compared to conventional aromatic polyimides. The permeability of CO2 is preferentially increased in comparison to all other gases, leading to remarkable ideal selectivities, especially for the N2 mixture (≈40). The incorporation of silica nanoparticles in PEI (from 1 to 15 wt%) was carried out during the cyclo-dehydration of the PAA by adding fumed hydrophobic (16 nm) or hydrophilic (12 nm) silica, or by Sol-Gel approach using alkoxysilane precursors (TMOS and TEOS). The effect of SiO2-fillers on the properties of gas permeation has been studied by the time-lag method mainly on the series prepared with fumed silica. It was observed that nano-particles of silica do not seem to disturb the PAA cyclization process and that the mechanical properties are improved; the gas permeability varies essentially depending on the amount of fillers incorporated but no spectacular increase in permeability could be shown due to the nano-particles amounts. Apparently, it can be deduced that it is the rubbery phase which accommodates the SiO2 particles. These results showed the value of PEI and PEI/SiO2 membranes in industrial applications of gas separation, especially for the separation of CO2/N2 mixtures

Ce travail a concerné l'étude de la fonctionnalisation métallique et du contrôle morphologique de nanoparticules de silice mésoporeuse appelées MSN. La voie de fonctionnalisation par synthèse directe a été privilégiée et a consisté en une encapsulation des précurseurs métalliques dans la phase porogène. L'insertion de cuivre, palladium, platine, argent or et de bimétalliques Cu/Pd et Pd/Pt a été réalisée. Il résulte de cette approche une localisation des nanoparticules métalliques dans les pores et d'une grande accessibilité des fonctionnalités à l'origine des excellentes performances catalytiques mesurées. Ces performances et le recyclage du catalyseur Cu@MSN ont été démontrés pour des réactions de Huisgen et de Sonogashira. Il a également été étudié l'adsorption de l'iode moléculaire en phase gaz sur des MSN fonctionnalisées par des nanoparticules d'argent avec d'excellentes capacités de rétention. / The objective of this thesis was to develop efficient synthesis routes to prepare mesoporous silica-based nano-sized particles, designated as MSN, with controllable morphology and derivatised with selected transition metals. One-pot preparation and surface functionalisation procedures based on the insertion of the metal-phase precursor into the porogen aggregates were thoroughly optimised leading to silica particles containing such single metals as copper, palladium, platinum, silver or gold, as well as a two-metal phase of copper and palladium or that of palladium and platinum. It was demonstrated that the highly dispersed metal phase was localised on the pore surface and therefore it was readily accessible to the target chemicals on which to base the catalytic performance of the resulting materials. Among others, the remarkable catalytic performance of the Cu@MSN material in Huisgen and Sonogashira reactions and its propensity to undergo efficient recycling were proven through laboratory-scale testing. Experimental study of the selective adsorption of iodine vapour onto MSN supports functionalised with silver nanoparticles indicated an excellent retention capacity of such materials.

Made available in DSpace on 2014-12-17T14:07:05Z (GMT). No. of bitstreams: 1 MarcioWDM_TESE.pdf: 5811012 bytes, checksum: feda974076398f5c8fbcb84ae56af460 (MD5) Previous issue date: 2010-09-17 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Metal substrates were coated by thermal spraying plasma torch, they were positioned at a distance of 4 and 5 cm from the nozzle exit of the plasma jet. The starting materials were used for deposition of tantalum oxide powder and aluminium. These two materials were mixed and ground into high-energy mill, then immersed in the torch for the production of alumina coating infused with particles of tantalum with nano and micrometric size. The spraying equipment used is a plasma torch arc not transferred, which operating in the range of 250 A and 80 V, was able to produce enough heat to ignite aluminothermic between Ta2O5 and aluminum. Upon reaching the plasma jet, the mixing powders react with the heat of the blaze, which provides sufficient energy for melting aluminum particles. This energy is transferred through mechanisms of self-propagating to the oxide, beginning a reduction reaction, which then hits on the surface of the substrate and forms a coating on which a composite is formed by a junction metal - ceramic (Ta +Al2O3). The phases and quantification of each were obtained respectively by X-ray diffraction and the Rietveld method. Morphology by scanning electron microscopy and chemical analysis by energy dispersive spectroscopy EDS. It was also performed measurements of the substrate roughness, Vickers microhardness measurements in sprays and determination of the electron temperature of the plasma jet by optical emission spectroscopy EEO. The results confirmed the expectation generated around the end product of spraying the mixture Ta2O5 + Al, both in the formation of nano-sized particles and in their final form. The electron excitation temperature was consistent with the purpose of work, in addition, the thermodynamic temperature was efficient for the reduction process of Ta2O5. The electron excitation temperature showed values of 3000, 4500 and 8000 K for flows10, 20 and 30 l / min respectively, these values were taken at the nozzle exit of the plasma jet. The thermodynamic temperature around 1200 ? C, was effective in the reduction process of Ta2O5 / Substratos met?licos de a?o inox 416 foram revestidos por aspers?o t?rmica em tocha de plasma. Eles foram posicionados a uma dist?ncia de 4 e 5 cm em rela??o ao bocal de sa?da do jato de plasma. Os materiais de partida utilizados para as deposi??es foram p?s de ?xido de t?ntalo e alum?nio. Esses dois p?s foram misturados e mo?dos em moinho de alta energia, em seguida, imersos na tocha para produ??o de revestimento de alumina impregnada com part?culas de t?ntalo com tamanho nano e microm?tricos. O equipamento de aspers?o utilizado foi uma tocha de plasma de arco n?o transferido que opera na faixa de 250 A e 30 V. Ao atingirem o jato de plasma, os p?s da mistura aquecem at? a temperatura de igni??o da rea??o aluminot?rmica. O calor gerado fornece energia suficiente para a fus?o do produto da rea??o. Esse produto fundido ao chocar-se na superf?cie do substrato forma um revestimento composto por uma jun??o metal cer?mica (Ta + Al2O3). A identifica??o das fases e sua quantifica??o foram obtidas respectivamente por difra??o de raios X e pelo m?todo de Rietveld. Para determina??o da morfologia e composi??o das part?culas foram utilizados microscopia eletr?nica de varredura e an?lise qu?mica por espectroscopia de energia dispersiva EDS, respectivamente. Tamb?m foram executadas medidas de rugosidades no substrato, medi??es de microdureza Vickers nas aspers?es e determina??o da temperatura eletr?nica do jato de plasma por espectroscopia de emiss?o ?tica EEO. Os resultados obtidos confirmaram a expectativa gerada em torno do produto final da aspers?o da mistura Ta2O5 + Al, tanto na forma??o de part?culas nanom?tricas de t?ntalo quanto no formato final delas. A temperatura de excita??o dos el?trons apresentou valores de 3000, 4500 e 8000 K para fluxos de 10, 20 e 30 l/min respectivamente, esses valores foram tomados na sa?da do bocal do jato de plasma. A temperatura termodin?mica, em torno de 1200 ?C mostrou-se eficiente para o processo de redu??o do Ta2O5