Thesis--Wisconsin. / Includes bibliographical references (leaves 72-79).

Thesis (M.S. in environmental engineering)--Washington State University, May 2006. / Includes bibliographical references (p. 12-13).

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references (leaves 114-120). Also available in electronic version.

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Made available in DSpace on 2014-10-09T12:28:07Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:37Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:28:07Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:37Z (GMT). No. of bitstreams: 0 / Neste trabalho foram estudadas as propriedades espectroscópicas do íon európio trivalente complexado à componentes da família das tetraciclinas, a clorotetraciclina, oxitetraciclina e metaciclina, em presença de peróxido de hidrogênio e peróxido de uréia. Para isso foram obtidos os parâmetros ópticos de absorção, emissão, tempo de vida e construídas curvas de calibração para os espectros de luminescência. Realizaram-se experimentos com compostos inorgânicos juntamente com os complexos a fim de verificar a interferência dos mesmos. Também foram realizados estudos para determinação de glicose utilizando os complexos európiotetraciclinas como biossensor. Os resultados mostram que os complexos európiotetraciclinas apresentam um espectro de emissão bem definido na região do visível e, na presença de peróxido de hidrogênio ou peróxido de uréia, há um aumento sensível na luminescência e tempo de decaimento. Assim, os complexos európiotetraciclinas estudados podem ser utilizados como biossensores para determinação dos peróxidos de hidrogênio e uréia, sendo um método realizado em temperatura ambiente, direto e de baixo custo. Um método indireto para determinação de glicose foi estudado através da adição da enzima glicose oxidase aos complexos európiotetraciclinas na presença de glicose no qual há como produto o peróxido de hidrogênio. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Orientadores: Giselle Maria Marchi, Carlos Alberto de Souza Costa / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-13T06:19:18Z (GMT). No. of bitstreams: 1 Lima_AdrianoFonsecade_M.pdf: 16947758 bytes, checksum: c368a477af40a0e63ffe78a57bea6537 (MD5) Previous issue date: 2009 / Resumo: Os objetivos do presente trabalho foram: a) avaliar os efeitos citotóxicos diretos e transdentinário de diferentes concentrações de peróxido de carbamida (PC) sobre as células de linhagem odontoblástica MDPC-23; b) avaliar o efeito protetor (antioxidante) do ascorbato de sódio (AS) sobre estas células expostas a agentes clareadores, na forma direta e transdentinária; c) avaliar o montante de peróxido de hidrogênio (H2O2) liberado por agentes clareadores a base de PC 10% e 16% que se difunde através de discos de dentina com 0,5mm de espessura. No Experimento 1, células odontoblásticas foram cultivadas em wells e incubadas por 48 horas. O gel clareador foi solubilizado em meio de cultura (DMEM) originando diferentes extratos, e a quantidade (µg/mL) de H2O2 liberado em cada extrato foi mensurada através da técnica de leucocristais violeta/enzima horseradish peroxidase (LCV/HRP). Os seguintes grupos foram estabelecidos (n=10): G1-DMEM sem gel clareador (controle); G2-0,0001% PC (0,025µg/ml de H2O2); G3-0,001% PC (0,43µg/ml de H2O2); G4-0,01% PC (2,21µg/ml de H2O2); e G5-0,1% PC (29.74µg/ml de H2O2). As células foram expostas por 60 minutos aos diferentes extratos, e então realizada a análise da viabilidade celular (Teste de MTT). Somente os grupos 2 e 3 não apresentaram diferença estatística quando comparados ao controle (G1) (p>0,05). Os maiores efeitos citotóxicos foram observados para G4 e G5, sendo que G5 foi estatisticamente diferente que G4, apresentando-se mais tóxico às células. No experimento 2, células MDPC-23 foram cultivadas e incubadas por 48h. O PC e o AS foram solubilizados em meio de cultura (DMEM), para obtenção dos extratos experimentais. Os seguintes grupos foram estabelecidos: G1-DMEM sem gel clareador (controle); G2- 0,25mM de AS; G3-0,5mM de AS; G4-0,25mM de AS + 0,01% de PC; e G5-0,5mM de AS + 0,01% PC e G6-0,01% de PC. As células foram expostas por 60 minutos aos diferentes extratos, e depois foi realizado o teste de MTT. O grupo 6 apresentou a maior citotoxicidade quando comparado com os demais grupos, enquanto que o AS produziu uma diminuição dos efeitos citotóxicos do agente clareador, demonstrando uma proteção frente aos componentes deste produto. No Experimento 3, discos de dentina (0,5mm de espessura) obtidos de terceiros molares humanos foram fixados em uma câmara pulpar artificial (CPA). As células odontoblásticas foram semeadas na superfície pulpar dos discos, e os seguintes grupos foram estabelecidos: Grupo 1 - Sem tratamento (Controle); Grupo 2 - Antioxidante 10% (AS)/6h; Grupo 3- Peróxido de Carbamida (PC) 10% /6h; Grupo 4- AS10%/6h+PC10%/6h; Grupo 5- PC16% /6h; Grupo 6- AS10%/6h+PC16%/6hs. Após os tratamentos, foi realizado o teste de MTT. A difusão de H2O2 somente para os grupos 3 e 5 foi mensurada através da técnica de LCV/HRP. Todos os grupos foram estatisticamente semelhantes, exceto o G6. O PC 16% apresentou a maior difusão transdentinária. Pode-se concluir que o PC apresenta efeitos citopáticos para as células odontoblásticas MDPC-23, na forma direta ou transdentinária e que esta citotoxicidade é dose-dependente. O ascorbato de sódio possui a capacidade de reduzir os efeitos citotóxicos do peróxido de carbamida, sobre estas mesmas células em cultura. / Abstract: The aims of this present study were: a) to evaluate the direct and transdentinal cytotoxic effects of carbamide peroxide (CP) bleaching gel at different concentrations on odontoblast-like cells MDPC-23; b) to evaluate the protective effect (antioxidizing) of sodium ascorbate (SA) on these cells expose to bleaching agents, on direct and transdentinal mode; c) to evaluate the amount of hydrogen peroxide (H2O2) released by bleaching agents based to CP 10% and 16%, that diffuses through dentin discs with 0.5mm thickness. In Experiment 1, odontoblastic cells were seeded in wells and incubated for 48 hours. The bleaching gel was diluted in DMEM culture medium originating different extracts, and the amount (µg/mL) of H2O2 released from each extract was measured by the leukocrystal violet/horseradish peroxidase enzyme (LCV/HRP) assay. The following groups were established (n=10): G1-DMEM without bleaching gel (control); G2-0.0001% CP (0.025 µg/mL H2O2); G3-0.001% CP (0.43 µg/mL H2O2); G4-0.01% CP (2.21 µg/mL H2O2); and G5-0.1% CP (29.74 µg/mL H2O2). MDPC-23 cells were exposed to the bleaching gel extracts for 60 minutes and then performed the cell viability analysis (MTT assay). Only G2 and G3 were not significantly different from control group (G1) (p>0.05). The most severe cytotoxic effects were observed in G4 and G5, and G5 was statistically different to G4, presenting more toxic to the cells. In Experiment 2, MDPC-23 cells were seeded in wells and incubated for 48 hours. CP and SA were dissolved in culture medium (DMEM) in order to obtain the experimental extracts. The following groups were established: G1-no treatment (control); G2-0,25mM SA; G3-0,5mM SA; G4-0,25mM SA + 0,01% CP; e G5-0,5mM SA + 0,01% CP e G6-0,01% CP. The cells were expose to different extracts for 60 min, and then was performed the MTT assay and. Group 6 presented higher cytotoxicity than the other groups, while the SA decreased the cytotoxic effects caused by CP, demonstrating its protective effect against the toxic components of this dental product. In Experiment 3, dentin discs (0.5mm thick) obtained from human third molars were fixed in an artificial pulp chamber (APC). The odontoblastic cells were seeded on pulp surface of the discs, and the following groups were established: Group 1 - No treatment (Control); Group 2 - Antioxidizing 10% (SA)/6h; Group 3- Carbamide Peroxide (CP) 10%/6h; Group 4- SA10%/6h+CP10%/6h; Group 5- CP16%/6h; Group 6- SA10%/6h+CP16%/6hs. After the treatments, MTT assay was performed. The H2O2 diffusion only to the groups 3 and 5 was measured by the LCV/HRP assay. All groups were statistically similar, except G6. The CP 16% presented the higher transdentinal diffusion. It can be conclude that CP presents citotoxic effects to the odontoblastic-like cells MDPC-23, in direct and transdentinal mode and this citotoxicity is dose-dependent. The sodium ascorbate was able to reduce the cytotoxic effects the concentration of 0.1% of PC caused the most intense cytopathic effects of carbamide peroxide on the same cells in culture. / Mestrado / Dentística / Mestre em Clínica Odontológica

Abstract Information about interactions among metals, hydrogen peroxide and chelating agents is needed to develop environmental technology and the operating efficiency of modern elemental chlorine free and total chlorine free bleaching processes. The work presented here focused on the properties of metal chelates and corrosion of titanium in an alkaline hydrogen peroxide solution. A comparative study between three rapid analysis methods, ICP-AES, XRF and ISE, was performed in pulp matrix and error sources of ISE were investigated in detail. Sensitive and selective GC methods for chelating agents ADA and NTA in water matrices were developed. Decomposition of ADA (percentage of residual 71) was observed already at the hydrogen peroxide anion level of 400 mg/l in which DTPA was more persistent (percentage of residual 94). EDTA was stable even in the hydrogen peroxide anion level of 1200 mg/l, in which its percentage of residual was 94. DTPA, EDTA and ADA were more soluble in the presence of iron and manganese than in the absence of these metals. The chelation of iron appeared to be thermodynamically limited in hydrogen peroxide bleaching conditions. Unalloyed (Grade 2) and alloyed (Grade 5) titanium corroded at the hydrogen peroxide anion level of 200 mg/l. The presence of calcium and silica inhibitors and further iron and manganese enhanced the critical hydrogen peroxide anion levels. Grade 5 was inferior to Grade 2. During rapid uniform corrosion, the potential of unalloyed titanium was under 200 mV (SHE) and lower than that of platinum. Over 90% of manganese and many other metals could be leached into aqueous phase for ICP-AES analysis using chelation or acid hydrolysis. An XRF method for manganese, iron and copper in pulp including little or no sample treatment was developed. Measuring temperature differences and atmospheric carbon dioxide were observed to be notable error sources of the ISE technique.

Simultaneous electrosynthesis of alkaline hydrogen peroxide and sodium chlorate in the same cell was investigated. The alkaline hydrogen peroxide was obtained by the electroreduction of oxygen in NaOH on a fixed carbon bed while the chlorate was obtained by the reaction of anodic electrogenerated hypochlorite and hypochlorous acid in an external reactor. An anion membrane, protected on the anode side with an asbestos diaphragm was used as the separator between the two chambers of the cell. The effects of superficial current density (1.2 - 2.4 kA m⁻²), sodium hydroxide concentration (0.5 - 2.0 M) and catholyte flow (0.1 x 10⁻⁶ - 0.5 x 10⁻⁶ m³ s⁻¹) on the chlorate and peroxide current efficiencies were measured. The effect of peroxy to hydroxy mole ratio on the chlorate current efficiency was measured too. The cell was operated at fixed anolyte flow of 2.0 x 10⁻⁶ m³ s⁻¹, inlet and outlet temperatures of 27/33°C (anode side), 20/29°C (cathode side), cell voltages of 3.0 - 4.2 V (current density of 1.2 - 2.4 kA -m⁻²) and a fixed temperature of 70°C in the anolyte tank. Depending on the conditions, alkaline peroxide solution and sodium chlorate were cogenerated at peroxide current efficiency between 20% and 86%, chlorate current efficiency between 51.0% and 80.6% and peroxide concentration ranging from 0.069 M to 0.80 M. The cogeneration of the two chemicals was carried out at both concentrated (2.4 - 2.8 M) and dilute (0 - 0.5 M) chlorate solutions. A relative improvement on the current efficiencies at concentrated chlorate was observed. A chloride balance indicated negligible chloride loss to the catholyte. The results are interpreted in terms of the electrochemical and chemical kinetics and the hydrodynamics of the cell . / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

Due to the toxicity and prevalence of BTEX contaminants (benzene, toluene, ethylbenzene, and xylenes) at hazardous waste sites, approaches for their remediation are of interest, especially those that particularly address benzene, which is often the limiting factor for achieving regulatory cleanup at these contaminated sites. In situ chemical oxidation (ISCO) is a viable technology for BTEX destruction, and hydrogen peroxide and sodium persulfate are two oxidants of interest for BTEX treatment.Laboratory studies were conducted to compare BTEX contaminant destruction and oxidant persistence for these two oxidants and for varied methods of oxidant activation/propagation. Additionally, studies were performed to compare contaminant destruction and oxidant persistence in laboratory contaminant spike systems vs. field site contaminant systems. Finally, contaminant destruction and oxidant persistence in field porous media with varied characteristics were evaluated. Contaminant and oxidant concentrations were measured at multiple time points over a three-week reaction period in each oxidant and oxidant activation/propagation system.Under the comparable conditions evaluated here, sodium persulfate systems demonstrated greater BTEX contaminant destruction and greater oxidant persistence than hydrogen peroxide systems. FeSO4 and citric acid activation of sodium persulfate resulted in greater BTEX destruction and greater oxidant persistence than pH adjustment or hydrogen peroxide activation in both laboratory contaminant spike systems and field gas condensate systems. Additionally, results indicate that the response of the contaminant(s) and oxidant (extent and rate of depletion) are both contaminant-and porous media type-dependent.