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Made available in DSpace on 2014-06-11T19:27:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-06-29Bitstream added on 2014-06-13T20:35:16Z : No. of bitstreams: 1 oishi_ss_me_guara.pdf: 1972224 bytes, checksum: 3c999656c713b895ba43f4e61fdba9fd (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Em função da crescente importância do material carbono vítreo em áreas estratégicas, devido às suas características intrínsecas, tais como menor massa específica e bons valores de condutividades térmica e elétrica, tem se observado vários estudos na busca de novos precursores poliméricos, assim como no ajuste mais sistemático de seu processamento. Nesse sentido, este trabalho tem como objetivo o estabelecimento de rotas de síntese de resinas furfurílica e fenol-furfurílica e suas dopagens com partículas de cobre, visando o processamento de eletrodos de carbono vítreo reticulado (CVR). Neste contexto foram sintetizadas diferentes formulações de resinas furfurílica e fenol-furfurílica a partir da variação dos monômeros – álcool furfurílico, fenol e formaldeído, respectivamente. A confirmação do sucesso das sínteses foi realizada por análises de espectroscopia de infravermelho com transformada de Fourier, cromatografia gasosa, análises térmicas por calorimetria exploratória diferencial e medidas dos teores de carbono fixo, que mostram resultados entre 27 e 45% em carbono. Em seguida, estas amostras foram dopadas com um colóide contendo as partículas de cobre. As resinas, com e sem dopagem, foram catalisadas, impregnadas em espumas de poliuretano (PU) e carbonizadas, obtendo-se assim, o CVR. Análises por microscopias óptica e eletrônica de varredura mostram a homogeneidade na impregnação das espumas de PU e a textura uniforme das amostras de CVR. Os resultados de resistência à compressão apresentam os melhores valores para o CVR resultante da carbonização com a resina furfurílica ácida (0,55 MPa). / Due to the growing importance of glassy carbon material in strategic areas, due to its intrinsic characteristics, such as lower density and good thermal and electrical conductivities values, has been observed several studies looking for new polymeric precursors and tighter processing parameters. In this way, this study aims on the establishment of synthesis routes of furfuryl and phenol-furfuryl alcohol resins and their doping with cupper particles, in order to produce reticulated glassy carbon (RGC) electrodes. Inside of this context were synthesized different formulations of furfuryl and phenol-furfuryl alcohol resins by the monomers variation – furfuryl alcohol, phenol and formaldehyde, respectively. The success confirmation of the synthesis has been done by using FT-IR spectroscopy, gas chromatography, thermal analyses by differential scanning calorimetry (DSC) and carbon yield content measurements that present results between 27 and 45% of carbon. After this, the specimens were doped with a colloid contend the copper particles. The doped and non doped resins were catalyzed, impregnated in polyuretane (PU) foams and carbonized, in order to obtain the reticulated glassy carbon. Optical and Scanning Electron Microscopy analysis show the homogeneity of PU foams impregnation and uniform texture of RGC specimens. Compression results present the best values for RGC resulting from the carbonization with furfuryl alcohol acid resin (0,55 MPa).

Yes / Peri-implantitis remains the major impediment to the long-term use of dental implants. With increasing concern over the growth in antibiotic resistance, there is considerable interest in the preparation of antimicrobial dental implant coatings that also induce osseointegration. One such potential coating material is fluorapatite (FA). The aim of this study was to relate the antibacterial effectiveness of FA coatings against pathogens implicated in peri-implantitis to the physicochemical properties of the coating. Ordered and disordered FA coatings were produced on the under and upper surfaces of stainless steel (SS) discs, respectively, using a hydrothermal method. Surface charge, surface roughness, wettability, and fluoride release were measured for each coating. Surface chemistry was assessed using X-ray photoelectron spectroscopy and FA crystallinity using X-ray diffraction. Antibacterial activity against periodontopathogens was assessed in vitro using viable counts, confocal microscopy, and scanning electron microscopy (SEM). SEM showed that the hydrothermal method produced FA coatings that were predominately aligned perpendicular to the SS substrate or disordered FA coatings consisting of randomly aligned rodlike crystals. Both FA coatings significantly reduced the growth of all examined bacterial strains in comparison to the control. The FA coatings, especially the disordered ones, presented significantly lower charge, greater roughness, and higher area when compared to the control, enhancing bacteria−material interactions and therefore bacterial deactivation by fluoride ions. The ordered FA layer reduced not only bacterial viability but adhesion too. The ordered FA crystals produced as a potential novel implant coating showed significant antibacterial activity against bacteria implicated in peri-implantitis, which could be explained by a detailed understanding of their physicochemical properties. / This work was partially funded through WELMEC, a Centre of Excellence in Medical Engineering funded by the Wellcome Trust and EPSRC, under grant number WT 088908/Z/09/Z.

The reformulation of pressurized metered dose inhalers (MDIs) with hydrofluoroalkanes (HFAs) from chlorofluorocarbons (CFCs) has given rise to many solubility challenges. Compounds and excipients previously used in CFCs were observed to have significantly different solubility values in HFA-134a. In this investigation, the solubility values of solid organic solutes were determined in pure HFA-134a and HFA-134a with cosolvent (0 - 20% w/w ethanol). The solubilities of solid solutes in HFA-134a were also compared with those in 2H,3H-decafluoropentane (DFP) in order to assess the suitability of DFP as a liquid model propellant. The experimental set of solutes display diverse physico-chemical properties and yielded solubility values that ranged over four orders of magnitude. The experimental solubilities were compared to calculated values obtained from ideal solubility and regular solution theory models. While the theoretical models did not offer absolute solubility estimations, a clear correlation with the ideal solubility (melting point) was noted. Further consideration utilizing multiple linear regression models afforded correlations based on molecular properties. Regression models, containing melting point and logP (or molar volume) resulted in promising correlations in both pure HFA-134a and HFA-134a/cosolvent systems where the average absolute errors ranged from 0.49 to 0.82 log units, (average factor errors of 3.09 and 6.61, respectively). In general, a linear relationship was observed between log mole fraction solubility in HFA-134a and fraction ethanol. The effect on solubilization ranged from 1.3 to 99.4 times when 20% w/w ethanol was introduced, relative to pure HFA-134a. DFP appears to be a promising liquid model for pure HFA-134a for pre-formulation calculations. A two parameter equation were found to be significant in pure HFA-134a where the average absolute error (AAE) value was 0.61 log units (average factor errors of 4.07).

Lecithin:cholesterol acyltransferase (LCAT) was isolated from hog plasma and basic physicochemical properties and functionally important regions were investigated. Approximately one milligram of the enzyme was purified to apparent homogeneity with approximately a 20,000-fold increase in specific activity. In the plasma, hog LCAT was found to associate with high-density lipoproteins (HDL) probably through hydrophobic interactions with apolipoprotein A-I. HDL was the preferred lipoprotein substrate of the enzyme as its macromolecular substrate. The enzyme was found to contain 4 free sulfhydryl groups; at least one of these appeared to be essential for catalytic activity. The enzyme had a tendency to aggregate at high concentrations. More than half of the tryptophan and none of the tyrosine residues of the enzyme were shown to be exposed to the aqueous environment based on fluorescence and absorbance studies, respectively.

Foram avaliadas algumas propriedades físico-químicas, como o pH, liberação de íons cálcio, tempo de presa, solubilidade e radiopacidade de 3 cimentos a base do agregado de trióxido mineral, clínquer do cimento Portland e um epóxico experimental. Foram avaliados os cimentos MTA Angelus branco, MTA Bio, cimentos experimentais, MTA fotopolimerizável e Sealepox RP e o Clínquer de cimento Portland acrescido de 20% de óxido de bismuto e 5% de sulfato de cálcio. Para as avaliações do pH e da liberação de íons cálcio foram utilizados tubos de polietileno com 1,0 mm de diâmetro interno e 10,0 mm de comprimento, com apenas uma das extremidades aberta. Esses tubos foram preenchidos com os cimentos e imediatamente imersos em tubos de ensaio contendo 10 mL de água deionizada, onde permaneceram durante todo o período experimental. Realizaram-se avaliações nos períodos de 3, 24, 72 e 168 horas, sempre se renovando a água deionizada ao final de cada período. Os ensaios de tempo de presa, solubilidade e radiopacidade, foram realizados conforme a norma #57 da ADA. Em relação ao tempo de presa, também foi utilizada a agulha de Gilmore de 453,6 g, para a presa final, conforme recomenda a norma #C266-03 da ASTM. Os resultados demonstraram que todos os cimentos apresentaram pH alcalino e liberaram íons cálcio em todos os períodos, com tendência de redução nos períodos finais. Quanto aos tempos de presa, os cimentos MTA Angelus branco e o cimento experimental MTA Bio apresentaram os menores tempos. Já o Clínquer apresentou valores intermediários, e o Sealepox RP, apresentou os tempos mais longos. O cimento MTA fotopolimerizável, por suas características próprias, não foi submetido a esse teste. Em relação ao ensaio de solubilidade, o cimento que mais se aproximou das recomendações da ADA, foi o Sealepox RP, com valores próximos a 1%, enquanto que os cimentos MTA Angelus branco, MTA Bio e o Clínquer acrescido ao radiopacificador e sulfato de cálcio apresentaram valores maiores. O MTA fotopolimerizável apresentou valores menores. Em relação à radiopacidade, a maioria dos cimentos estudados apresentou valores superiores à da dentina, com resultados semelhantes entre si, com exceção do MTA fotopolimerizável, que apresentou valor próximo ao da dentina. / Some properties had been evaluated physicochemical, such as pH, release of calcium ions, setting time, solubility and radiopacity of 3 retrograde filling the base of the aggregate of mineral trioxide, to clínquer of the Portland cement and an experimental epoxy sealer. Experimental cements MTA white Angelus, MTA Bio, light-curing MTA and Sealepox RP and the Clínquer of cement Portland increased of 20% of bismuth oxide and 5% of calcium sulphate had been evaluated. For the evaluations of pH and the release of calcium ions had been used polyethylene pipes with 1,0 mm of internal diameter and 10,0 mm of length, with only one of the extremities open. These pipes had been filled with cements and immediately immersed in pipes of 10 assay I contend mL of distilled water, where they had remained all during the experimental period. Evaluations in the periods of 3, 24, 72 and 168 hours, always if renewing the distilled water to the end of each period. The assays of setting time, solubility and radiopacity, had been carried through in agreement the norm #57 of the ADA. In relation to the setting time, also g was used the needle of Gilmore of 453,6, for the final canine tooth, as it recommends to the norm #C266-03 of the ASTM. The results had demonstrated that all the cements had presented pH alkaline and had liberated calcium ions in all the periods, with trend of reduction in the final periods. How much to the setting time, cements MTA white Angelus and experimental cement MTA Bio had presented the lesser times. Already the Clínquer presented intermediate values, and Sealepox RP, presented the times longest. Light-curing cement MTA, by its proper characteristics, was not submitted to this test. In relation to the solubility assay, the cement that more was come close to the recommendations of the ADA, was Sealepox RP, with next values 1%, whereas cements MTA white Angelus, MTA Bio and the Clínquer increased to the bismuth oxide and calcium sulphate had presented bigger values. The light-curing MTA presented less resulted . In relation to the radiopacity, the majority of studied cements presented more values to the one of the dentine, with similar results between itself, exception of the light-curing MTA, that presented value next to the one to the dentine.

This study is to evaluate the effect of curing and casting methods on the physicochemical properties of polymeric coating systems. Aqueous-dispersion-based and organic-solvent-based Kollicoat® SR30D (poly(vinyl acetate)) and Kollicoat® MAE100P (poly(methacrylic acid-ethyl acrylate)) free films or film-coated pellets were used to evaluate the physicochemical properties resulting from different solvents and different curing treatments. Diffusion coefficients of water in organic-solvent-based films were lower than those in aqueous-dispersion-based films. Increases in curing temperature and curing time decreased the diffusion coefficient. Regardless of preparation method, the tensile strengths of films increased with an increase in curing temperature and curing time. Changes in elongation percentage of the films were dependent on the polymer and curing. The tensile strengths of aqueous-dispersion-based SR30D films are lower compared to those of organic-solvent-based SR30D films. However, the “core-shell” structure is preserved in the aqueous-dispersion-based MAE100P film and formed a rigid frame, which greatly increased the mechanical properties of the films. Therefore, the tensile strength of aqueous-dispersion-based MAE100P films is greater than in the case of organic-solvent-based films. In swelling studies, water uptake and weight loss for all of the films increased with an increase in incubation time. The water uptake and weight loss of SR30D films cast from water were higher than those of organic-solvent-based films. However, contradictory results were observed for MAE100P films due to the core-shell structure in the aqueous-dispersion-based MAE100P films. An increase in curing time and temperature increased the Tg of SR30D films. Curing treatments led to a second glass transition temperature for MAE100P films, which may result from microphase separation. Curing decreased acetaminophen release from pellets coated with an aqueous-dispersion-based SR30D film. Curing effects are also dependent on the coating formulation and coating parameters. The drug release rate from organic-solvent-based film-coated pellets was slower in comparison to pellets coated with aqueous-dispersion-based films. Acetaminophen release in 0.1 N HCl from aqueous-dispersion-based MAE100P coated pellets was reduced after the curing treatment. Curing has no effect on drug release for acetaminophen-containing pellets coated with organic-solvent-based SR30D or MAE100P films. The ionization of surface carboxylic-acid groups on MAE100P polymer particles alters the properties of polymer films by increasing ionic aggregates and solubilizing the polymer chains. Increased ionic aggregates improve the mechanical properties of films. However, solubilizing polymer chains will change the film formation mechanism from a dispersion-based film to a solution-based film. Therefore, tensile strength was decreased with an increase in ionization degree. The drug release rates were continuously increased when the degree of ionization of surface acid groups increased. Overall, curing and casting methods have significant effects on the physicochemical properties of SR30D and MAE100P films and on the drug release behavior from film-coated, drug-loaded pellets. The core-shell structure in aqueous-dispersion-based MAE100P films also greatly changed the properties of this film or coat.

The biodegradability and physicochemical properties of unsubstituted and methylated polycyclic aromatic hydrocarbons (PAHs) were investigated. The focus was on the development of models expressing the influence of molecular structure and properties on observed behavior. Linear free energy relationships (LFERs) were developed for the estimation of aqueous solubilities, octanol/water partition coefficients, and vapor pressures as functions of chromatographic retention time. LFERs were tested in the estimation of physicochemical properties for twenty methylated naphthalenes containing up to four methyl substituents. It was determined that LFERs can accurately estimate physicochemical properties for methylated naphthalenes. Twenty unsubstituted and methylated PAHs containing up to four aromatic rings were biodegraded individually by Sphingomonas paucimobilis strain EPA505, and Monod-type kinetic coefficients were estimated for each PAH using the integral method. Estimated extant kinetic parameters included the maximal specific biodegradation rate, the affinity coefficient, and the inhibition coefficient. The generic Andrews model adequately simulated kinetic data. The ability of PAHs to serve as sole energy and carbon sources was also evaluated. Quantitative structure-biodegradability relationships (QSBRs) were developed based on the estimates of the kinetic and growth parameters. A genetic algorithm was used for QSBR development. Statistical analysis and validation demonstrated the predictive value of the QSBRs. Spatial and topological molecular descriptors were essential in explaining biodegradability. Mechanistic interpretation of the kinetic data and the QSBRs provided evidence that simple or facilitated diffusion through the cell membranes is the rate-determining step in PAH biodegradation by strain EPA505. A kinetic experiment was conducted to investigate biodegradation of PAH mixtures by strain EPA505. The investigation focused on 2-methylphenanthrene, fluoranthene, and pyrene, and their mixtures. Integrated material balance equations describing different interaction types were fitted to the depletion data and evaluated on a statistical and probabilistic basis. Mixture degradation was most adequately described by a pure competitive interaction model with mutual substrate exclusivity, a fully predictive model utilizing parameters estimated in the sole-PAH experiments only. The models developed in this research provide insight into how molecular structure and properties influence physicochemical properties and biodegradability of PAHs. The models have considerable predictive value and could reduce the need for laboratory testing.

The overarching goal of this research was to investigate the differences in the physicochemical and functional properties of protein isolates produced from seven different faba bean genotypes (CDC Fatima, Taboar, SSNS-1, FB9-4, FB18-20, Snowbird and CDC Snowdrop) grown at different locations in Canada (Saskatchewan, Alberta and Manitoba) in 2011 and 2012. The protein isolates were prepared by alkaline extraction (pH 9.5) followed by isoelectric precipitation at pH 4.5. The isolates had an average protein content of ~94% and average protein and isolate yields of ~77% and ~25%, respectively. The physicochemical properties assessed in this study included surface charge/zeta potential (ZP), surface hydrophobicity (SH), and surface and interfacial tension (ST and IT). The functional properties tested included foaming capacity (FC) and foam stability (FS), emulsion capacity (EC) and creaming stability (CS), emulsion activity index (EAI) and emulsion stability index (ESI), oil holding capacity (OHC), and protein solubility. The findings indicated that all physicochemical properties for all isolates were independent of genotype. Overall, an average ZP of + 22.1 mV, SH of 47.2 arbitrary units, and ST and IT of 65.0 mN/m and 10.7 mN/m, respectively, were observed. However, with the exception of ZP considerable differences were observed due to the effect of environment. The ratio of the major globulin protein fractions [legumin:vicilin (L/V)] was found to shift during processing, from 3.8 (range: 3.4-4.6) in the flour to 4.5 (range 4.0-4.9) in the isolates. The L/V ratio for faba bean flour and isolate samples was also found to be independent of genotype. For all genotypes, with the exception of the zero-tannin varieties (Snowbird and CDC Snowdrop), the L/V ratio was affected by the environment. Similar to the physicochemical properties, all functional attributes were found to be independent of genotype. However, environmental effects were observed for all functional properties with the exception of EAI and ESI. Average values for FC of 162.0%, for FS of 65.0%, for EC of 184.0 g/g, for CS of 94.0%, for OHC of 5.7 g/g, for EAI of 13.0 m2/g, for ESI of 10.7 min and for solubility of 81.0% were reported. Zeta potential was observed to be positively correlated with CS (r = 0.46; p<0.05) and FS (r = 0.54; p<0.01), whereas SH and L/V ratio were not. The L/V ratio in the isolate, however, was correlated positively with SH (r = 0.40; p<0.05) and negatively with ZP (r = -0.39; p<0.05). Moreover, the solubility of faba bean isolates was found to be positively correlated with ZP (r = 0.44; p<0.05) and negatively correlated with both IT (r = -0.38; p<0.05) and OHC (r = -0.38; p<0.05). The functional properties of some commercial protein isolates (soy, pea, whey, egg and wheat) were evaluated for comparative purposes. The OHC of the faba bean isolate was found to be higher than that of any of the commercial isolates. With the exception of CS (soy and pea) and FC (egg), all of the emulsifying (EC, EAI and ESI) and foaming (FC and FS) properties of the faba bean protein isolates were comparable to those of soy, pea and egg isolates. In contrast, values for most of the other functional properties were greater for faba bean isolates than for the pea and wheat isolates, but lower than for the whey isolate. For example, the solubility of the protein isolates was observed to decrease in the following order: whey (89.0%) = egg (88.1%) > faba bean (81.0%) > soybean (30.5%) > pea (20.1%) > wheat (10.7%).

The UPPER (Unified Physicochemical Property Estimation Relationships) model uses additive and non-additive parameters to estimate 21 biologically and environmentally important physicochemical properties of organic compounds. Thermodynamically sound relationships are used to predict boiling and melting points, aqueous and octanol solubilities, vapor pressure and the air-octanol, air-water and octanol-water partition coefficients. These properties determine the distribution and fate of organic compounds in biological and environmental systems. The model has been validated on a data set of 2000 hydrocarbons and polyhalogenated hydrocarbons, provides a simple and accurate method to predict the properties studied.