Under cellulolytic conditions, the white-rot fungus Trametes versicolor produces cellobiose dehydrogenase (CDH), an enzyme with a number of biochemical properties that are potentially relevant to the degradation of lignin and cellulose. To clarify its biochemical properties, CDH was purified from cultures of T. versicolor. Two isoforms of CDH were found: a 97 kDa isoform with both heme and flavin cofactors, and an 81 kDa isoform with a flavin cofactor. Both isoforms of CDH were found to be quite non-specific in their reductive half reactions. The flavin enzyme catalyzed many of the same reactions as the heme/flavin enzyme, but less efficiently. The flavin isoform reduced Fe(III) and Cu(II) only at concentrations well above those found physiologically. Thus the heme/flavin enzyme, but not the flavin enzyme, could be involved in promoting and sustaining the generation of hydroxyl radicals (·OH) by Fenton's chemistry. / To characterize further the structural features of CDH, a genomic clone was isolated and sequenced. CDH was found to consist of 748 amino acids, without its predicted 19 amino acid signal peptide. Consistent with the domain structure of other CDHs, T. versicolor CDH appeared to be divided into an amino terminal heme domain and a carboxy terminal flavin domain, connected by a hydroxyamino acid-rich linker. Within the flavin domain, a putative cellulose-binding domain (CBD) was found by alignment to the hypothesized CBD of P. chrysosporium CDH. The CBD of CDH appeared to be structurally unrelated to other CBDs which have been reported. / A cDNA clone encoding T. versicolor CDH was isolated by RT-PCR. Using this clone, three vectors for the heterologous expression in Aspergillus oryzae of CDH were prepared. These vectors were built by performing in-frame fusions of the cDNA to control sequences from the highly expressed A. oryzae amylase gene. These vectors were transformed into A. oryzae and one strain was isolated which contained the expression construct DNA. / A rapid method for cloning cdh-like genes was developed. Using short stretches of amino acids completely conserved within T. versicolor and P. chrysosporium CDH, PCR primers were designed to amplify a homologous gene from other fungi. The primers were tested using genomic DNA of Pycnoporus cinnabarinus. A 1.8-kb fragment of P. cinnabarinus cdh was thereby amplified and cloned, and its sequence was determined. The three CDHs displayed very high homology at the amino acid level. / Finally, to probe the role of CDH in lignocellulose degradation by T. versicolor, a "knockout" vector was constructed consisting of a phleomycin-resistance cassette inserted into the protein coding sequence of cloned T. versicolor cdh. T. versicolor was transformed with the knockout vector and the transformants were analyzed for their CDH-producing phenotype. Three isolates were found that produced no detectable CDH. Biobleaching and delignification by the CDH(-) strains appeared to be unaffected, suggesting that CDH does not play an important role in these processes.

In 2005 and 2010, high sea surface temperatures caused widespread coral bleaching on Jamaica’s north coast reefs. Three shallow (9m) reef sites were surveyed during each event to quantify the prevalence and intensity of coral bleaching. In October 2005, 29-57% of the colonies surveyed were bleached. By April 2006, 10% of the corals remained pale/partially bleached. Similarly, in October 2010, 23-51% of corals surveyed at the same sites were bleached. By April 2011, 12% of the colonies remained pale/partially bleached. Follow-up surveys revealed low coral mortality following both events, with an overall mean of 4% partial colony mortality across all species and sites observed in April 2006, and 2% in April 2011. Mixed effects models were used to quantify the relationship between colony size and (a) bleaching intensity, and (b) bleaching related mortality among coral species. The bleaching intensity model explained 51% of the variance in the bleaching response observed during the two events. Of this 51%, fixed effects accounted for ~26% of the variance, 17% of which was attributed to species-specific susceptibility to bleaching , 5% to colony size, <1% colony morphology and 4% to the difference in bleaching intensity between the two events. The random factor (site) accounted for the remaining ~25% of the variance. The mortality model explained 16% of the variance in post bleaching mortality with fixed effects, including colony size, morphology and species explaining ~11% of the variance, and the random effect (site) explaining 5%. On average, there was a twofold difference in bleaching intensity between the smallest and the largest size classes. Modelling the relationship between colony level characteristics and site-specific environmental factors on coral species’ susceptibility to thermal stress can shed light on community level responses to future disturbances.

No description available.

Electrochromic films undergo a colour change when small ions and electrons are inserted into them, under the influence of an applied electric field. These films are also known as ion-intercalation electrodes, and may be incorporated into glazing structures more commonly known as 'smart windows'. Smart windows are that which may be used to control the amount of heat and light entering a building and may therefore be used to minimise the energy consumption associated with heating, cooling and lighting. The commercial success of smart windows, requires that they operate reproducibly at temperatures up to approximately 70ºC, for many tens of thousands of colouring and bleaching cycles. An understanding of the underlying kinetic processes over a wide temperature range is therefore needed, in order to determine suitable control strategies and switching conditions capable of fulfilling these requirements. The research detailed in this thesis has involved an investigation into the kinetic behaviour of ion-intercalation electrodes, and simulation of the electrical response as a means of developing a tool for predicting and then optimising electrochromic switching. More specifically, the electrical and optical properties of electrochromic thin films of WO3/TiO2 have been studied over a wide temperature range, appropriate for the operation of electrochromic windows. The magnitude of the voltages required for coloration and bleaching significantly reduces as temperature increases. Some irreversibility was observed at high temperature, as well as a reduction in coloration efficiency. Further investigation revealed that self-bleaching and irreversibility effects were caused by the presence of water, and this problem was exacerbated at high temperature. Post-experiment chemical analysis of a film sample revealed that some trapping of the inserted ions had occurred, however the amount of ions remaining in the film was much smaller than expected. The results suggested that a large quantity of the lithium ions injected into the film were lost to the electrolyte after many cycles, possibly accompanied by some film dissolution. Experimental work carried out in a dry-box showed that films may be cycled reversibly in a very dry environment, and the optical properties were independent of temperature under these conditions. Unfortunately, the conditions which led to reversible cycling and good electrochromic memory, also resulted in very long response times for film bleaching. This result implies that a good electrochromic memory and a fast response are mutually competitive aims. Data from high temperature experiments was simulated with a mathematical model and the mobility of lithium ions inside the electrochromic films was estimated in the process. The estimated diffusion coefficients agreed well with published values, and exhibited an Arrhenius dependence on temperature. Activation energies for diffusion were calculated and the results were very reasonable. Some deviation from ideal Arrhenius behaviour was observed for the estimated diffusion coefficients at high temperature. It is likely that the rate limiting mechanism changes from diffusive motion of ions at low temperature, to charge transfer at high temperature.

Coral reef environments have been degrading steadily over the last few decades. It is generally accepted now that coral reefs are one of the first marine ecosystems to show measurable perturbations driven by global warming. Some of theses perturbations are consequence of extreme stochastic disturbances like hurricanes or extreme thermal anomalies and therefore, can be easily identified using broad indicators like coral cover. These indicators are easy to measure and provide a general description of the system in question. The detection and interpretation of more subtle perturbation in coral communities is more complicated, both logistically and conceptually. However, detecting chronic perturbations at an early stage can increase significantly the success of early mitigating management strategies. This thesis focuses on the development and application of highly sensitive indicators that can detect subtle perturbations in coral communities. It also studies the ecological interpretation of mild perturbations and their effect on the future structure of coral reef environments. The mild thermal disturbance experienced by the Heron Island reef in the south of the Great Barrier Reef during the 2005-2006 summer, and an environmental gradient along the central coast of Venezuela (south Caribbean Sea), were used as models to test the sensitivity of coral reefs to mild disturbances at different organisation levels (organism, population, and community). At the organismal level my results showed that the intensity of bleaching that a colony shows during a mild thermal disturbance is affected by the morphology of the colony as well as the substrates surrounding the colony. Colonies surrounded by sand bleached more than colonies surrounded by dead coral or rubble. I propose that reef specific information on the relative cover of sand, rubble, and dead coral can improve the fine scale accuracy of bleaching predicting models. Studying the same mild thermal disturbance at Heron Island, I showed how demographic parameters of some populations are more sensitive to mild thermal disturbances than coral cover (the most widely used response variable in coral monitoring programs around the world). Furthermore, my results suggest that the response of coral populations to mild thermal disturbance is different in nature and intensity to the respond observed during extreme thermal disturbances. Some taxa like Stylophora pistillata, are highly sensitive to extreme thermal disturbances, and tend to be the first to die under these conditions. In contrast, this taxon was extremely tolerant to the mild thermal disturbance of early 2006 in comparison to other taxa identified previously as more tolerant than S. pistillata. This difference in the response of coral environments to milder more common disturbances can have great influence in the trajectory that coral reefs follow in a rapidly changing world. Finally at a community level, I demonstrated how the power to detect the effect of environmental conditions on coral environments is drastically increased when the coral host-endosymbiotic algae relationship is interpreted holistically. The percentage of the variability of the community structure that can be explained by environmental variables in the central coast of Venezuela is doubled when the unit of selection considered is the holobiont instead of the coral host or the endosymbiont independently. This approach can be crucial for the detection of subtle changes in coral communities as the frequency and intensity of disturbances increase rapidly. The increase in detection power provided by the different approaches developed in this project can both improve our understanding of the structuring role of mild disturbances in coral communities as well as help identify the effect of disturbances in an early stage before the perturbation reaches catastrophic proportions. This early identification of perturbations can be used for the development of adaptive management strategies that can increase the resistance and resilience of coral reefs in the future.

Thesis (Ph.D.) - James Cook University, 2004. / Typescript (photocopy) Bibliography: leaves 110-130.

Thesis (M.S.)--University of Michigan, 1985.

Thesis (M.S.)--University of Michigan, 1985.

Orientador: Clóvis Pagani / Banca: Camillo Anauate Netto / Banca: Wagner de Oliveira / Resumo: 0 objetivo deste estudo foi avaliar a capacidade do flúor de induzir a remineralização do esmalte humano submetido às técnicas de clareamento caseiro e profissional. Sessenta dentes foram divididos em cinco grupos: G1 - controle; G2- peróxido de carbamida a 10%; G3 - peróxido de carbamida a 10% e flúor a 0,05%; G4 - peróxido de hidrogênio a 35%; G5 - peróxido de hidrogênio a 35% e flúor a 0,05%. A microdureza Vickers de todos os corpos-de-prova foi mensurada antes e após o tratamento. Posteriormente foram realizadas análises em Espectrômetro de Absorção Atômica (EAA) e em Microscopia Eletrônica de Varredura (MEV). Os dados foram submetidos à análise estatística de variância e testes de Dunnett e Tukey. Os resultados evidenciaram redução significante da microdureza do esmalte clareado e o peróxido de carbamida promoveu redução significativamente maior do que o peróxido de hidrogênio. Dentes expostos ao flúor apresentaram menor redução da microdureza, sendo que essa diferença não foi significante nos dentes clareados com peróxido de carbamida e significante nos dentes clareados com peróxido de hidrogênio. Por meio da análise em EAA, observou-se que os grupos que não foram expostos ao flúor perderam mais cálcio do que os seus correspondentes que foram remineralizados. Ao MEV apresentaram-se alterações na morfologia da supertfcie do esmalte nos dentes clareados, sendo que estas não estavam distribuídas uniformemente em toda a superfície. Concluiu-se que a fluorterapia é um método adequado para minimizar a redução da microdureza após o clareamento caseiro ou de consultório / Abstract: The aim of this study was to evaluate the ability of fluoride to induce remineralizatian of the human dental enamel subjected to nightguard vital bleaching and professional bleaching. Sixty teeth were divided into five groups: control; 10% peroxide carbamide; 10% peroxide carbamide and 0.05% fluoride; 35% hydrogen peroxide; 35% hydrogen peroxide and 0.05% fluoride. The Vickers microhardness of all specimens was measured before and after treatment. Complementary analysis comprised Atomic Absorption Spectrometry (AAE) and Scanning Electron Microscopy (SEM). Data were subjected to statistical analysis of variance (ANOVA), Dunnett's and Tukey's tests. The results revealed that there is significant reduction of enamel microhardness when subjected to the bleaching agents, compared to the control group. Carbamide peroxide promoted reduction of microhardness statistically bigger than hydrogen peroxide. The specimens that were exposed to fluoride showed a statistically significant smaller reduction of microhardness, compared with those not treated with fluoride. This difference was non-significant in teeth treated with carbamide peroxide and significant in teeth treated with hydrogen peroxide. Analysis by AAE .displayed that the groups not exposed to fluoride lost more calcium than their correspondents with remineralization. The SEM findings revealed morphologic changes in the enamel surface of bleached teeth, though these were not uniform through the entire surface. It was concluded that fluortherapy is an adequate method to minimize reduction of microhardness after nightguard or in-office vital bleaching / Mestre

Submitted by CARLA CAROLINE DE OLIVEIRA DUQUE null (carlacoduque@hotmail.com) on 2016-05-19T21:24:16Z No. of bitstreams: 1 Carla corr final 19.05.26 Repositorio Unesp.pdf: 6964321 bytes, checksum: 22480753de2d82fb176b13a6a33d913e (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-05-23T20:16:17Z (GMT) No. of bitstreams: 1 duque_cco_me_arafo.pdf: 6964321 bytes, checksum: 22480753de2d82fb176b13a6a33d913e (MD5) / Made available in DSpace on 2016-05-23T20:16:17Z (GMT). No. of bitstreams: 1 duque_cco_me_arafo.pdf: 6964321 bytes, checksum: 22480753de2d82fb176b13a6a33d913e (MD5) Previous issue date: 2016-03-23 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Tem sido demonstrado que a susceptibilidade do complexo dentino-pulpar aos efeitos adversos do clareamento dental apresenta uma relação direta com a espessura de esmalte/dentina do substrato dental. Desta forma, o objetivo do presente estudo foi avaliar o efeito estético e biológico de um gel clareador contendo 10% de peróxido de hidrogênio (H2O2) aplicado por diferentes períodos sobre a superfície de discos simulando a espessura de incisivos inferiores (ICI) e pré-molares superiores (PMS). Discos de esmalte/dentina, provenientes de incisivos bovinos, com 2,3 e 4,0 mm de espessura foram adaptados a câmaras pulpares artificiais e distribuídos nos Grupos ICI e PMS, respectivamente. O gel clareador com 10% de H2O2 foi aplicado na superfície de esmalte por 3x15, 1x15 ou 1x5 minutos. Como controle positivo, um gel com 35% de H2O2 aplicado por 3x15 minutos (protocolo tradicional) foi empregado. Nenhum tratamento foi realizado na superfície de esmalte no grupo controle negativo. O meio de cultura em contato com a dentina imediatamente após o clareamento (extrato) foi coletado e aplicado por 1 hora sobre células pulpares humanas. A viabilidade e morfologia celular foram avaliados imediatamente após exposição aos extratos (T1), bem como 72 horas pós-tratamento (T2). O estresse oxidativo e a quantificação do H2O2 nos extratos também foram analisados em T1. A atividade de ALP (atividade de fosfatase alcalina) e deposição de nódulos de mineralização (NM) foram avaliados em períodos de 14 e 21 dias pós-clareamento, respectivamente. De forma a avaliar a eficácia estética dos protocolos testados nas diferentes condições experimentais, mensurou-se ainda a alteração de cor (ΔE) durante seis sessões clareadoras. De uma forma geral, observou-se que todos os protocolos experimentais com gel a 10% de H2O2 promoveram diminuição dos efeitos deletérios promovidos pelo protocolo tradicional. O protocolo 10% 3x15 causou redução significativa na viabilidade celular em relação ao controle negativo no período T1, em ambos os Grupos ICI e PMS, sendo que as células expostas a este protocolo no Grupo ICI não demonstraram capacidade proliferativa em T2. As alterações morfológicas, a intensidade do estresse oxidativo e a redução nos marcadores fenotípicos (ALP e NM) também foram mais intensos para este protocolo nos Grupos ICI e PMS. Para os protocolos 10% 1x15 ou 1x5 minutos, ausência de redução significante na viabilidade celular foi observada, independente da espessura. No entanto, estresse oxidativo significativo foi observado nas células do Grupo ICI. Estes protocolos promoveram redução na atividade de ALP, a qual foi proporcional ao tempo de contato e espessura do substrato dental; entretanto não se observou redução na deposição de NM aos 21 dias. Valores de ΔE similares ao protocolo tradicional foram observados para os protocolos 10% 3x15 e 10% 1x15 no Grupo ICI após 4 e 6 sessões, respectivamente. Para o Grupo PMS, este parâmetro foi atingido apenas para o protocolo 10% 3x15 após 6 sessões clareadoras. Concluiu-se que a espessura do substrato dental influenciou significativamente na citotoxicidade trans-amelodentinária do gel com 10% de H2O2. A aplicação deste gel por períodos de 45 ou 15 minutos sobre discos simulando a espessura de incisivos inferiores minimizou significativamente a toxicidade celular e promoveu clareamento tão efetivo quanto o protocolo tradicionalmente empregado. / The susceptibility of pulp-dentin complex to the adverse effects of tooth bleaching therapies has a direct relationship with the thickness of dental substrate. Therefore, the aim of this study was to assess the biologic and esthetic effect of a 10% hydrogen peroxide (H2O2) bleaching gel applied for different periods onto enamel/dentin discs simulating the thickness of low incisors (LI) and upper pre-molars (PM). Enamel/dentin discs from bovine incisors measuring 2.3 and 4.0 mm were adapted to artificial pulp chambers and distributed into the IC Group (low incisors) and PM Group (upper premolars), respectively. The enamel surface was bleached with a 10% H2O2 gel for 3x15, 1x15 or 1x5 minutes. The 35% H2O2 gel applied for 3x15 minutes was used as positive control (traditional therapy) and no treatment was performed on negative control group. The culture medium immediately after bleaching (extract) was applied for 1 hour on human dental pulp cells. Cell viability and morphology were evaluated immediately after bleaching (T1) and 72 h thereafter (T2). Oxidative stress and the amount of H2O2 in culture medium were also quantified at T1. The ALP activity and mineralized nodule (MN) deposition were assessed 14 and 21 days after bleaching, respectively. The color change (ΔE) of enamel was analyzed throughout six bleaching sessions. Overall, the experimental protocols with the 10% H2O2 gel minimized significantly the negative effects of traditional therapy to cultured pulp cells. The protocol 10% 3x15 promoted significant cell viability reduction in comparison with negative control at T1, in both, IC and PM Groups; however, the cells of IC Group did not feature proliferative capability at T2. The morphologic alterations, oxidative stress intensity and reduction on phenotype markers (ALP and NM) expression were also more intense on IC Group for this bleaching protocol. Regarding the protocols 10% 1x15 and 1x5, no significant cell viability reduction related to negative control was observed regardless of the thickness of dental substrate. Nevertheless, significant oxidative stress was observed on cells from IC Group. These protocols caused significant reduction of ALP activity in comparison to negative control, which intensity being proportional to enamel/dentin thickness; however, no reduction on NM was detected at 21 days post-bleaching. Similar ΔE values as positive control were found for the 10% 3x15 and 1x15 protocol on IC Group after 4 and 6 sessions, respectively. For PM Group, this feature was reached out after 6 bleaching sessions for the 10% 3x15 protocol. It was concluded that the enamel/dentin thickness of dental substrate played a significant role on the trans-enamel and trans-dentinal cytotoxicity of a 10% H2O2 bleaching gel on human dental pulp cells in vitro. Application of gel during 45 or 15 minutes onto thin dental substrate minimizes significantly the cell toxicity in comparison to high concentrated gels (35%) associated with similar esthetic outcome by increasing the number of bleaching sessions. / FAPESP: 2014/07229-6 / CNPq: 442336/2014-4