No presente trabalho foram estudados alguns aspectos não lineares da catálise da oxidação de etileno glicol (EG) sob platina em meio alcalino (KOH). A dinâmica do sistema foi investigada através de voltametria cíclica, séries temporais de corrente e potencial e por espectroscopia de impedância eletroquímica. (EIE). Os resultados da EIE revelaram a presença de uma região de resistência diferencial negativa escondida nas proximidades o pico principal obtido na voltametria cíclica. De modo geral o sistema se mostrou apto a oscilar tanto sob regime potenciostático quanto galvanostático e por longos períodos de tempo apresentando uma miríade de estados dinâmicos que incluem oscilações harmônicas, de baixa e alta amplitudes, períodos 2, 3, 4 e modos mistos, além da duplicação de período na transição para o caos. A concentração tanto de EG como de KOH tiveram caráter essencial nos padrões temporais observados. A complexidade dos períodos aumenta com o aumento da concentração de EG resultando em 90% do tempo em que o sistema passa oscilando devotado às oscilações caóticas quando a concentração de EG é de 1,6 M. O aumento da densidade de corrente produz um efeito contrário nos padrões, ou seja, quanto mais alta é a corrente mais simples são os períodos. A influência de alguns produtos de oxidação parcial do EG foi estudada em diferentes condições. Os resultados das mudanças de morfologia das oscilações são racionalizados em termos das eventuais conexões com os intermediários de reação formados durante o processo de oxidação que, por sua vez, dependem da concentração do álcool e da densidade de corrente. / In the present work were studied some nonlinear aspects of the catalytic oxidation of ethylene glycol (EG) on platinum electrodes in alkaline media (KOH). The system\'s dynamics was investigated by means of cyclic voltammetry, current and potential time series, and electrochemical impedance spectroscopy (EIS). The EIS results reveal the presence of a hidden negative differential resistance around the main voltammetric peak. Overall, the system was able to oscillate for several periods, displaying a myriad of dynamic states which includes harmonic, small and large amplitude, periods 2, 3, and 4, and mixed-mode oscillations, as well as period doubling transition to chaos. The concentration of both EG and KOH were found to play an essential role in the temporal patterns observed. The complexity of the periods increase with EG concentration resulting in 90% of the oscillating time devoted to chaotic patters when EG concentration is 1.6 M. The increment of the current density produces an opposite behavior of the patters: the higher the applied current the simpler the oscillatory dynamics. The influence of some products of partial EG oxidation was studied under different conditions and compared. The results of the changes in the oscillatory morphology are rationalized in terms of its eventual connection with reaction intermediates formed during the oxidation process that, in turn, depends on the alcohol concentration and on the current density.

A large portion of an airport property is occupied by runways and taxiways, which must be kept in excellent condition to ensure the safety of the airplanes, and the people on board. Any free objects on the airfield can cause damage to aircraft and are a possible danger to both the airplanes and the passengers. However, deterioration of the concrete airfield can be a major hazard and the presence of de-icing and anti-icing fluids may accelerate degradation. The focus of this project was the evaluation and assessment of aircraft de-icing and anti-icing fluids on the deterioration of airfield concrete. These fluids are used to remove and prevent snow and ice formation on aircraft by lowering the freezing temperature of water. The primary component in both fluids is ethylene glycol, while additives, which are proprietary and unknown, are mixed in to control various properties. Very little research has been done regarding the effect of the de-icer and anti-icers on the concrete deterioration. The aim of this study was to gain a better understanding of its influence on the deterioration of airfield concrete through a series of mechanical and electro-chemical tests, as well as microscopic and elemental analysis. Based on the comparative experiments and analyses performed using water, ethylene glycol, de-icer, and anti-icer, it appears that de-icing fluids do not prematurely cause concrete deterioration. In addition, experimental procedures in this study utilized the de-icing fluids as a concentrate, which are unrealistic conditions on an airfield, where dilution occurs from the addition of water and the presence of snow and ice. There was precipitate formation in all cases of cement paste exposure to de-icing fluid, however, which indicates that reactions are occurring and should be investigated further to determine the long term effects on concrete. With respect to the scope of this study, it was determined that the use of de-icers and anti-icers cause no significant detrimental effects on concrete mechanical properties and durability.

A large portion of an airport property is occupied by runways and taxiways, which must be kept in excellent condition to ensure the safety of the airplanes, and the people on board. Any free objects on the airfield can cause damage to aircraft and are a possible danger to both the airplanes and the passengers. However, deterioration of the concrete airfield can be a major hazard and the presence of de-icing and anti-icing fluids may accelerate degradation. The focus of this project was the evaluation and assessment of aircraft de-icing and anti-icing fluids on the deterioration of airfield concrete. These fluids are used to remove and prevent snow and ice formation on aircraft by lowering the freezing temperature of water. The primary component in both fluids is ethylene glycol, while additives, which are proprietary and unknown, are mixed in to control various properties. Very little research has been done regarding the effect of the de-icer and anti-icers on the concrete deterioration. The aim of this study was to gain a better understanding of its influence on the deterioration of airfield concrete through a series of mechanical and electro-chemical tests, as well as microscopic and elemental analysis. Based on the comparative experiments and analyses performed using water, ethylene glycol, de-icer, and anti-icer, it appears that de-icing fluids do not prematurely cause concrete deterioration. In addition, experimental procedures in this study utilized the de-icing fluids as a concentrate, which are unrealistic conditions on an airfield, where dilution occurs from the addition of water and the presence of snow and ice. There was precipitate formation in all cases of cement paste exposure to de-icing fluid, however, which indicates that reactions are occurring and should be investigated further to determine the long term effects on concrete. With respect to the scope of this study, it was determined that the use of de-icers and anti-icers cause no significant detrimental effects on concrete mechanical properties and durability.

Oligo(ethylene glycol) groups have been used as substituents in poly(p-phenyleneethynylene)s (PPEs) to provide solubility, and to boost quantum yield. Properties such as water-solubility and increased quantum yield in aqueous solution make these conjugated systems promising for biosensory applications. In this thesis, a PPE containing a branched ethylene glycol side chain is synthesized as part of a polymer array for glycan biosensing. I also report that the same side chain can be put to use in a red-emissive polymer to lend water solubility. Another monomeric unit, containing ethylene glycol chains, is incorporated into a PPE to create an ampiphilic polymer. The versatility of these polymers allows them to be used for a variety of purposes, some of which will be described herein.

Analogous to the extracellular matrix (ECM) of natural tissues, properties of a tissue engineering scaffold direct cell behavior and thus regenerated tissue properties. These include both physical properties (e.g. morphology and modulus) and chemical properties (e.g. hydrophobicity, hydration and bioactivity). Notably, recent studies suggest that scaffold properties (e.g. modulus) may be as potent as growth factors in terms of directing stem cell fate. Thus, 3D scaffolds possessing specific properties modified for optimal cell regeneration have the potential to regenerate native-like tissues. Photopolymerizable poly(ethylene glycol) diacrylate (PEG-DA)-based hydrogels are frequently used as scaffolds for tissue engineering. They are ideal for controlled studies of cell-material interactions due to their poor protein adsorption in the absence of adhesive ligands thereby making them “biological blank slates”. However, their range of physical and chemical properties is limited. Thus, hydrogel scaffolds which maintain the benefits of PEG-DA but possess a broader set of tunable properties would allow the establishment of predictive relationships between scaffold properties, cell behavior and regenerated tissue properties. Towards this goal, this work describes a series of unique hybrid inorganic-organic hydrogel scaffolds prepared using different solvents and also in the form of continuous gradients. Properties relevant to tissue regeneration were investigated including: swelling, morphology, modulus, degradation rates, bioactivity, cytocompatibility, and protein adhesion. These scaffolds were based on the incorporation of hydrophobic, bioactive and osteoinductive methacrylated star polydimethylsiloxane (PDMSstar-MA) [“inorganic component”] into hydrophilic PEG-DA [“organic component”]. The following parameters were varied: molecular weight (Mn) of PEG-DA (Mn = 3k & 6k g/mol) and PDMSstar-MA (Mn = 1.8k, 7k, 14k), ratio of PDMSstar-MA to PEG-DA (0:100 to 20:80), total macromer concentration (5 to 20 wt%) and utilizing either water or dichloromethane (DCM) fabrication solvent. The use of DCM produced solvent induced phase separation (SIPS) resulting in scaffolds with macroporous morphologies, enhanced modulus and a more homogenous distribution of the PDMSstar-MA component throughout. These hybrid hydrogel scaffolds were prepared in the form of continuous gradients such that a single scaffold contains spatially varied chemical and physical properties. Thus, cell-material interaction studies may be conducted more rapidly at different “zones” defined along the gradient. These gradients are also expected to benefit the regeneration of the osteochondral interface, an interfacial tissue that gradually transitions in tissue type. The final aspect of this work was focused on enhancing the osteogenic potential of PDMS via functionalization with amine and phosphonate. Both amine and phosphonate moieties have demonstrated bioactivity. Thus, it was expected that these properties will be enhanced for amine and phosphonate functionalized PDMS. The subsequent incorporation of these PDMS-based macromers into the previously described PEG-DA scaffold system is expected to be valuable for osteochondral tissue regeneration.

Current synthetic vascular grafts have high failure rates in small-diameter (<6 mm) applications due to inadequate cell-material interactions and poor matching of arterial biomechanical properties. To address this, we have developed a multilayer vascular graft design with a non-thrombogenic inner layer that promotes endothelial cell (EC) interactions and a reinforcing layer with tunable biomechanical properties. The blood-contacting layer of the graft is based on a Streptococcal collagen-like protein (Scl2-1). Scl2-1 has the triple helical structure of collagen, but it is a non-thrombogenic protein that can be modified to have selective cell adhesion. For this application, Scl2-2 has been modified from Scl2-1 to contain integrin binding sites that promote EC adhesion. We have developed the methodology to incorporate Scl2 proteins into a poly(ethylene glycol) (PEG) hydrogel matrix. PEG-Scl2 hydrogels facilitate optimization of both bioactivity and substrate modulus to offer unique control over graft endothelialization. However, scaffold properties that promote endothelialization may not be consistent with the mechanical properties necessary to withstand physiological loading. To address this issue, we have reinforced PEG-Scl2-2 hydrogels with an electrospun polyurethane mesh. This multilayer vascular graft design decouples requisite mechanical properties from endothelialization processes and permits optimization of both design goals. We have confirmed the thromboresistance of PEG-Scl2-2 hydrogels in a series of whole blood tests in vitro as well as in a porcine carotid artery model. Additionally, we have shown that the electrospun mesh biomechanical properties can be tuned over a wide range to achieve comparable properties to current autologous grafts. Traditional acrylate-derivatized PEG (PEGDA) hydrogels were replaced with PEG diacrylamide hydrogels with similar properties to increase biostability for long-term implantation. These findings indicate that this multilayer design shows promise for vascular graft applications. As vascular graft endothelialization can significantly improve success rates, the ability to alter cell-material interactions through manipulations in PEG-Scl2-2 hydrogel properties was studied extensively. By reducing Scl2-2 functionalization density and utilizing a biostable PEG functionalization linker, Acrylamide-PEG-I, significantly improved initial EC adhesion was achieved that was maintained over 6 weeks of swelling in vitro. Additionally, increases in Scl2-2 concentration and in hydrogel modulus provided increased EC interactions. It was found that PEG-Scl2-2 hydrogels promoted enhanced EC proliferation over 1 week compared to PEG-collagen gels. In summary, we have developed a vascular graft with a biostable, non-thrombogenic intimal layer that promotes EC adhesion and migration while providing biomechanical properties comparable to current autologous grafts. This design demonstrates great potential as an off-the-shelf graft for small diameter arterial prostheses that improves upon current clinically available options.

Nowadays, cancer treatment and tissue regeneration have attracted large amount of attention. Single Wall Carbon Nanotubes (SWNT) possess large surface area and outstanding optical and electrical performance, making it a promising component in cancer therapy and tissue reengineering systems. In this study, four disease treating systems based on SWNT are developed. They are pH-sensitive poly(ethylene glycol)-doxorubicin(PEG-DOX)@SWNT drug release system, temperature sensitive SWNT hydrogel, SWNT based biocompatible magnetic hydrogel and biocompatible SWNT-gelatin-F127-cysteamine hydrogel for tissue engineering. The successfully synthesized target compounds are characterized by FTIR. The in vitro release of drugs from the drug release systems is evaluated upon changes of pH values and the laser scanning. The effect of cancer treatment systems on specific kind of cells are examined by confocal laser scanning microscopy (CLSM). The results indicate that all of the four systems show great potential in the biomedical applications especially in disease therapy applications.

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 103-112).

Submitted by Natália Baraldi Cunha null (nataliabcunha@gmail.com) on 2016-09-07T13:56:55Z No. of bitstreams: 1 Tese final Natália Baraldi Cunha.pdf: 2266420 bytes, checksum: dcf97228e8c74e2d108a5822a0bca60d (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-09-09T20:21:52Z (GMT) No. of bitstreams: 1 cunha_nb_dr_bot.pdf: 2266420 bytes, checksum: dcf97228e8c74e2d108a5822a0bca60d (MD5) / Made available in DSpace on 2016-09-09T20:21:52Z (GMT). No. of bitstreams: 1 cunha_nb_dr_bot.pdf: 2266420 bytes, checksum: dcf97228e8c74e2d108a5822a0bca60d (MD5) Previous issue date: 2016-07-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Introduction: The calcium oxalate is the major metabolic component involved in the formation of renal calculus. Therefore, different pharmacological approaches have been or are being proposed for the treatment of nephrolithiasis by calcium oxalate. Among them, the pyridoxine, a component of vitamin B6, has been suggested as a potential therapeutic agent that can minimize the effects of hyperoxaluria. However, the results are controversial. Objective: To evaluate the effects of pyridoxine (vitamin B6) on the urinary excretion of oxalate and its possible impact on renal disorders caused by nephrocalcinosis induced from an experimental model of hyperoxaluria in rats. Methods: It was used 60 Sprague Dawley male rats and were randomized into four groups: Group 1 [(G1: n = 15) clinical control]; Group 2 [G2: Ethylene glycol (EG) 0.5% + Vitamin D3 (VD3), n = 15], which hyperoxaluria was induced by the administration of EG diluted in water and offered in association with VD3 (Cholecalciferol) at a dose of 0.5 uM; Group 3 [G3: 0.5% EG + VD3 + pyridoxine (VB6); n = 15], which the animals received the same drugs offered to the G2 plus VB6 at a dose of 180mg / kg body weight / day; Group 4 (G4, n = 15) which the animals are supplemented only with the same dose of VB6 in G3. All animals were euthanized after 28 days of intervention and submitted a metabolic study on the urine of 24 hours; histopathological / morphometric analysis of oxidative stress in renal parenchymal and spectroscopic measurement of calcium. Results: Among the urinary parameters evaluated, there was significant reduction in the citrate in G2 compared to the control group- G1 (781.9 and 2414.4mg / L, respectively), while the oxalate was significantly increased in G2 and G3 compared to G1 (7.79, 8.94 and 2.96mg / L, respectively). The urinary calcium was significantly lower in the induced groups (G3: 0.9, G2: 1.5 and G1: 2.25mg / dL). Histomorphometric analysis revealed that only the animals of G2 and G3 developed nephrocalcinosis without, however, no substantially differences from each other in the counting of intratubular crystals were found. Similarly, considering the histopathologic analysis, only the induced animals (G2 and G3) exhibited atrophy, stromal extravasation and inflammatory infiltrate in the renal parenchyma in a similar pattern between the two groups. Regarding to the analysis of oxidative stress, an increase of lipid hydroperoxide levels associated with reduced superoxide dismutase activity and glutathione peroxidase in the G2. In the other groups, the enzyme pattern remained relatively stable compared to the control, except for catalase activity, which activity proved to be increased in all groups. In the other groups, the enzyme pattern remained relatively stable compared to the control (G1), except for the catalase activity, in which activity increased in all groups. As expected, the quantification of calcium in the renal parenchyma was significantly higher in G2 and G3 as compared to groups without induction. Conclusion: Pyridoxine was not able to produce a significant effect in the treatment and / or prevention of urinary disorders, as well as morphological, inflammatory and functional renal tissue in rats with secondary hyperoxaluria obtained from the administration of inducing agents. / Introdução: O oxalato de cálcio (OxCa) é o principal componente metabólico envolvido na formação dos cálculos renais. Por esta razão, diferentes abordagens farmacológicas foram ou estão sendo propostas para o tratamento da nefrolitíase por OxCa. Dentre elas, a piridoxina, um componente da vitamina B6, tem sido sugerida como potencial agente terapêutico capaz de atenuar os efeitos da hiperoxalúria, porém com resultados ainda controversos. Objetivo: Avaliar os efeitos da piridoxina (Vitamina B6) sobre a excreção urinária de oxalato e seu eventual impacto nas alterações renais causadas pela nefrocalcinose induzida a partir de um modelo experimental de hiperoxaluria em ratos. Métodos: Foram utilizados 60 ratos machos da raça Sprague-Dawley, randomicamente distribuídos em quatro grupos: GRUPO 1 (G1: n=15) controle clínico; GRUPO 2 [G2: Etilenoglicol (EG) a 0,5%+vitamina D3 (VD3), n=15] no qual a hiperoxalúria foi induzida a partir da administração de EG diluído em água e ofertado em associação com a VD3 (Colecalciferol) na dose de 0,5 μM; GRUPO 3 [G3: EG 0,5%+VD3+Piridoxina(VB6); n=15] onde os animais receberam as mesmas drogas ofertadas ao G2 acrescido da VB6 na dose de 180mg/kg peso/dia; GRUPO 4 (G4, n=15) animais suplementados apenas com a VB6 na mesma dose do G3. Todos os animais foram eutanasiados após 28 dias de intervenção e submetidos a estudo metabólico na urina de 24 horas; análise histopatológica/morfométrica, análise do estresse oxidativo no parênquima renal, bem como dosagem espectroscópica do cálcio. Resultados: Dentre os parâmetros urinários avaliados, observou-se significativa redução do citrato no G2 em relação ao controle (781,9, e 2414,4mg/L, respectivamente), enquanto que o oxalato mostrou-se significativamente aumentado nos G2 e G3 quando comparado ao G1 (7,79; 8,94 e 2,96mg/L, respectivamente). O cálcio urinário foi significativamente menor nos grupos induzidos (G3:0,9, G2:1,5 e G1: 2,25mg/dL). A análise histomorfométrica revelou que apenas os animais dos G2 e G3 desenvolveram nefrocalcinose sem, no entanto, apresentar diferença significativa entre si na contagem dos cristais intratubulares. Da mesma forma, considerando-se a análise histopatológica, apenas os animais induzidos (G2 e G3) exibiram atrofia, extravasamento estromal e infiltrado inflamatório no parênquima renal, em um padrão bastante semelhante entre os dois grupos. Com relação à análise do estresse oxidativo, houve aumento dos níveis do hidroperoxido de lipídeo associado à redução da atividade da superoxido dismutase e glutationa peroxidase no G2. Nos demais grupos, o padrão enzimático manteve-se relativamente estável em relação ao controle, com exceção da atividade da catalase, cuja atividade revelou-se aumentada em todos os grupos estudados. Como esperado, a quantificação do cálcio no parênquima renal foi significativamente maior em G2 e G3 quando comparado aos grupos sem indução. Conclusão: A piridoxina não foi capaz de produzir um efeito significativo no tratamento e/ou na prevenção das alterações urinárias, bem como morfológicas, inflamatórias e funcionais do parênquima renal de ratos com hiperoxalúria secundária obtida a partir da administração de agentes indutores.

Orientador: Paulo Roberto Kawano / Resumo: Introduction: The calcium oxalate is the major metabolic component involved in the formation of renal calculus. Therefore, different pharmacological approaches have been or are being proposed for the treatment of nephrolithiasis by calcium oxalate. Among them, the pyridoxine, a component of vitamin B6, has been suggested as a potential therapeutic agent that can minimize the effects of hyperoxaluria. However, the results are controversial. Objective: To evaluate the effects of pyridoxine (vitamin B6) on the urinary excretion of oxalate and its possible impact on renal disorders caused by nephrocalcinosis induced from an experimental model of hyperoxaluria in rats. Methods: It was used 60 Sprague Dawley male rats and were randomized into four groups: Group 1 [(G1: n = 15) clinical control]; Group 2 [G2: Ethylene glycol (EG) 0.5% + Vitamin D3 (VD3), n = 15], which hyperoxaluria was induced by the administration of EG diluted in water and offered in association with VD3 (Cholecalciferol) at a dose of 0.5 uM; Group 3 [G3: 0.5% EG + VD3 + pyridoxine (VB6); n = 15], which the animals received the same drugs offered to the G2 plus VB6 at a dose of 180mg / kg body weight / day; Group 4 (G4, n = 15) which the animals are supplemented only with the same dose of VB6 in G3. All animals were euthanized after 28 days of intervention and submitted a metabolic study on the urine of 24 hours; histopathological / morphometric analysis of oxidative stress in renal parenchymal and spectroscopic... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Introdução: O oxalato de cálcio (OxCa) é o principal componente metabólico envolvido na formação dos cálculos renais. Por esta razão, diferentes abordagens farmacológicas foram ou estão sendo propostas para o tratamento da nefrolitíase por OxCa. Dentre elas, a piridoxina, um componente da vitamina B6, tem sido sugerida como potencial agente terapêutico capaz de atenuar os efeitos da hiperoxalúria, porém com resultados ainda controversos. Objetivo: Avaliar os efeitos da piridoxina (Vitamina B6) sobre a excreção urinária de oxalato e seu eventual impacto nas alterações renais causadas pela nefrocalcinose induzida a partir de um modelo experimental de hiperoxaluria em ratos. Métodos: Foram utilizados 60 ratos machos da raça Sprague-Dawley, randomicamente distribuídos em quatro grupos: GRUPO 1 (G1: n=15) controle clínico; GRUPO 2 [G2: Etilenoglicol (EG) a 0,5%+vitamina D3 (VD3), n=15] no qual a hiperoxalúria foi induzida a partir da administração de EG diluído em água e ofertado em associação com a VD3 (Colecalciferol) na dose de 0,5 μM; GRUPO 3 [G3: EG 0,5%+VD3+Piridoxina(VB6); n=15] onde os animais receberam as mesmas drogas ofertadas ao G2 acrescido da VB6 na dose de 180mg/kg peso/dia; GRUPO 4 (G4, n=15) animais suplementados apenas com a VB6 na mesma dose do G3. Todos os animais foram eutanasiados após 28 dias de intervenção e submetidos a estudo metabólico na urina de 24 horas; análise histopatológica/morfométrica, análise do estresse oxidativo no parênquima renal, bem com... (Complete abstract click electronic access below) / Doutor