Made available in DSpace on 2014-07-29T15:01:52Z (GMT). No. of bitstreams: 1 dissertacao_Ana Elisa.pdf: 1011464 bytes, checksum: 0fe4be232b2f56c521e72d6557985d3c (MD5) Previous issue date: 2010-02-09 / The developmental impulse of the present time has caused a continuous degradation of the environment, which increases the need of monitoring the contaminant levels launched in the natural water courses and industrial effluents. In this context, it is crucial to develop new methodologies of determination and quantification of various types of pollutants, with rapidity, selectivity and sensitivity, characteristics which were found in the chemically modified electrodes (CMEs). Many industrial processes are polluting the sources of water resources, such as the petrochemical industries and paper and cellulose industries. From those, sulfide is frequently set free causing serious demages due to its high toxicity, even in low concentrations, which suggests methods of detention of sulfide of high sensitivity, reduced time and low cost. Some analytical methodologies for the detention of sulfide are based on the reaction with methylene blue, which has recognized mediating electron capacity. Accordingly, the development and characterization of CMEs, modified with silica-niobium-methylene blue possess promising characteristics and great potential of use in these analyses. Studies of the voltametric behavior of CMEs had been carried through with different concentrations of SNAM. Beyond the effect of the paste composition, also the effect of the type of electrolyte support and of the pH had been investigated. The CMEs had been studied by cyclic voltammetry, linear voltammetry and chronoamperometry technique, presenting good reply to the ion sulfide in the linear response range between 7.59 x 10¬6 and 6,34 x 10¬5 moI L¬ 1, with correlation coefficient (r) of 0, 9979, detection limit of 2,03 x 10-6mol L-1 and quantification limit of 6,77 x 10¬6 moI L¬ 1. The results gotten in this work has allowed to conclude that the carbon paste modified with SNAM presents a good analytical performance for analysis of sulfide in samples of environmental interest / O impulso desenvolvimentista da atualidade tem provocado a necessidade de se monitorar continuamente o teor de contaminantes lançados nos cursos de águas naturais e efluentes industriais. Neste contexto, é essencial o desenvolvimento de novas metodologias de determinação e quantificação de diversos tipos de poluentes, com rapidez, seletividade e sensibilidade, características estas, encontradas nos eletrodos quimicamente modificados (EQM). Vários processos industriais são fontes poluidoras dos recursos hídricos, tais como indústrias petroquímicas, de papel e celulose. O sulfeto é frequentemente liberado por essas indústrias e causa sérios danos devido a sua alta toxicidade mesmo em baixas concentrações, o que sugere métodos de detecção de sulfeto de alta sensibilidade, tempo reduzido e baixo custo. Várias metodologias analíticas para detecção de sulfeto se baseiam na reação com azul de metileno, que por sua vez possui reconhecida capacidade mediadora de elétrons. Nesse sentido o desenvolvimento e caracterização de EQM modificado com sílica-nióbio-azul de metileno, possui características promissoras e grande potencial de utilização nessas análises. Foram realizados estudos do comportamento voltamétrico de EQMs de pasta de carbono modificados com diferentes concentrações de SNAM. Foram investigados além do efeito da composição da pasta, efeitos do tipo de eletrólito suporte e do pH. O EQM foi estudado por voltametria cíclica, voltametria linear e cronoamperometria, apresentando boa resposta ao íon sulfeto nas faixas lineares de concentração de 7.59 x 10-6 a 6.34 x 10-5 mol L-1, com coeficientes de correlação (r) de 0,9979, limite de detecção de 2,03 x 10-6mol L-1 e limite de quantificação de 6,77 x 10-6 mol L-1. Os resultados obtidos neste trabalho permitiram concluir que a pasta de carbono modificada com SNAM apresenta um bom desempenho analítico para análise de sulfeto, garantindo boa sensibilidade, o que pode tornar-se uma alternativa vantajosa para determinação de sulfeto em amostras de interesse ambiental

O presente trabalho descreve o preparo, a caracterização e o uso de eletrodo modificado com polímero de azul de metileno (PMB) imobilizado sobre a superfície de eletrodo de carbono vítreo (GCE-PMB) na análise do herbicida glifosato. O método utilizado para a preparação dos filmes do PMB foi a eletropolimerização. Os filmes preparados por este método apresentam características diferenciadas tais como robustez, estabilidade e propriedade redox satisfatória. As condições experimentais otimizadas foram a velocidade de varredura (50 mV s-1), o intervalo de potencial (-0,4 a +1,2 V), o número de ciclos (30) e o pH da solução do eletrólito suporte (pH 8). A solução de eletrólito suporte foi preparada a partir das soluções de tampão fosfato (0,05 mol L-1) e NaNO3 (0,1 mol L-1), pH 8. A mesma foi utilizada no preparo da solução de azul de metileno (MB) (0,25 x 10-3 mol L-1), no pré-tratamento do eletrodo de carbono vítreo (GC) por voltametria cíclica (CV) e no preparo de soluções para os estudos iniciais com o GCE-PMB. O pré-tratamento da superfície do eletrodo de GC foi realizado aplicando + 0,9 V por 240 s seguido de várias varreduras cíclicas de -0,4 a +1,0 V com velocidade de varredura de 50 mV s-1 até obter um perfil estável do voltamograma do eletrodo. Após o preparo do GCE-PMB, a atividade eletrocatalítica do eletrodo foi investigada para o Ácido Ascórbico (AA) e a L-Cisteína (L-Cys) por CV de -0,4 a +0,6. Foi observado aumento da corrente de pico e diminuição do sobrepotencial em relação ao eletrodo de GC. Nos estudos na presença do glifosato, o GCE-PMB apresentou resposta eletroquímica direta, por voltametria cíclica, para o glifosato (1,0 x 10-3 mol L-1) em solução de KCl 0,1 mol L-1 (pH 5,3) de -0,4 a +0,6 V e velocidade de varredura 50 mV s-1. A resposta voltamétrica apresentou picos anódico e catódico em 0,2 e 0, respectivamente. Para os estudos realizados por meio da técnica de voltametria de onda quadrada (SWV), os parâmetros freqüência, amplitude e incremento de varredura foram otimizados. A partir desses estudos foi possível obter informações relevantes sobre a interação do GCE-PMB com o glifosato. Os resultados mostraram que é possível observar a eletroatividade do herbicida glifosato sobre uma superfície eletródica sem a presença de metais como agentes complexantes. / This work describes the preparation, characterization and the use of the modified electrode with methylene blue polymer (PMB) immobilized onto the surface of glassy carbon electrode (GCE-PMB) in the analysis of the herbicide glyphosate. Concerning the methodology aspects, the method used for the preparation of the films PMB was the electropolymerization. The films prepared by this method present a differentiated characteristic such as robustness, stability and good redox properties. The optimized experimental conditions are the scan rate (50 mV s-1), the potential range (-0.4 to +1.2 V), the number of cycles (30) and the pH of the supporting electrolyte (pH 8). The supporting electrolyte solution was prepared from phosphate buffer solutions (0.05 mol L-1) and NaNO3 (0.1 mol L-1), pH 8. The same solution was used to prepare the solution of methylene blue (MB) (0.25 x 10-3 mol L-1), the pretreatment of the GC electrode by cyclic voltammetry (CV). It was also utilized in preparing solutions for the initial studies with GCE-PMB. The pre-treatment of the electrode surface of GC was performed, considering 0.9 V during 240 s, followed by several cyclic scans from -0.4 to 1.0 V (with scan rate of 50 mV s-1) until a stable profile of the voltammogram. After preparing the GCE-PMB, electrocatalytic activity it was investigated for Ascorbic Acid (AA) and L-Cysteine (L-Cys) by CV from -0.4 to +0.6 V. It was observed increase in peak current and decrease the overpotential comparing to glassy carbon electrodes. The GCE-PMB presented direct electrochemical response, for glyphosate (1 x 10-3 mol L-1) in KCl 0.1 mol L-1 (pH 5.3) from -0.4 to +0.6 V and scan rate 50 mV s-1. The voltammetric response showed anodic and cathodic peaks in 0.2 and 0, respectively. Using the square wave voltammetry (SWV), the parameters frequency, amplitude and scan increment were optimized. It was possible to find relevant information about the interaction between GCE-PMB and glyphosate. These results showed that is possible observe the electroactivity of glyphosate on a modified electrodic surface in absence of metals or complexing agents.

O objetivo do presente estudo foi avaliar o efeito da Terapia Fotodinâmica Antimicrobiana (aPDT) com a utilização de azul de metileno a 0,01%, combinado ao laser de diodo, na viabilidade e na produção de polissacarídeos, de biofilmes de S. mutans. Biofilmes de cepas de S. mutans UA159 foram cultivados em discos de resina acrílica e expostos oito vezes por dia, durante 1 min, à solução de sacarose a 10%. Após 48 horas da formação do biofilme, as amostras foram distribuídas aleatoriamente em relação aos tratamentos (n=4): aplicação de solução salina a 0,9% (controle negativo), aplicação de 0,12% de digluconato de clorexidina (controle positivo), ou aplicação da terapia fotodinâmica antimicrobiana. Para aplicação da terapia fotodinâmica antimicrobiana, foi utilizado azul de metileno a 0,01%, combinado ao laser de diodo com comprimento de onda de 660 nm. Foram usados os seguintes parâmetros: área da secção transversal do feixe de laser 0,028 cm&sup2;, potência de 100 mW, energia de 9J, densidade de energia de 320J/cm&sup2;, durante 90s. Os tratamentos foram realizados duas vezes ao dia. Após 120 h, os biofilmes de S. mutans formados sobre cada disco de resina acrílica foram coletados, de modo a determinar o número de bactérias viáveis e a concentração do polissacarídeo extracelular insolúvel (PECI) e do polissacarídeo intracelular (PIC). A análise variância um critério (ANOVA) e o teste de Tukey revelaram que as contagens das bactérias nos biofilmes formados foram significativamente diferentes entre os tratamentos. A aPDT mostrou inibição do crescimento do biofilme, quando comparado ao grupo do NaCl (p<0,05). A concentração de PECI e PIC foi maior no biofilme exposto ao NaCl do que a encontrada nos outros grupos (p<0,05) e não foi observada diferença significativa entre os grupos digluconato de clorexidina e aPDT (p>0,05). De acordo com as condições experimentais do presente estudo, sugere-se que o tratamento realizado duas vezes ao dia com aPDT utilizando-se azul de metileno a 0,01%, combinado ao laser de diodo (&lambda; = 660 nm; 320 J/cm&sup2;; 100 mW; 90s; 9J), diminui a viabilidade do biofilme e afeta sua organização estrutural. / The aim of this study was to evaluate the effect of Antimicrobial Photodynamic Therapy (aPDT) using methylene blue 0.01% combined with diode laser on biofilm viability and polysaccharides produced by Streptococcus mutans. S. mutans UA 159 biofilms were grown on acrylic resin discs and exposed eight times/day for 1 min in a 10% sucrose solution. After the biofilms were allowed to grow for 48 h, they were treated two times/day according to the treatments (n=4): 0.9% saline solution (negative control), 0.12% chlorhexidine digluconato (positive control) or Antimicrobial Photodynamic Therapy (aPDT). For the application of Antimicrobial Photodynamic Therapy has been used methylene blue 0.01% in combination with the diode laser with 660 nm wavelength. The parameters adopted were: spot size of 0.028 cm&sup2;, fixed output power of 100 mW, energy density of 320 J/cm&sup2;, time exposure of 90 s and energy of 9 J. Treatments were performed twice daily. After 120 h of growth, the biofilm formed on each disc was collected to determine the number of viable bacteria, and concentration of the insoluble exopolysaccharide (IEPS) and intracellular polysaccharide (IPS). The analysis of variance one-way (ANOVA) and Tukey test revealed that the counts of bacteria in the biofilms formed differ significantly among the treatments and aPDT showed biofilm inhibition when compared to NaCl group (p<0.05). The concentration of IEPS and IPS was higher in biofilm exposed to NaCl than that found in the other groups (p<0.05) and no significant difference was observed among CHX and aPDT groups (p>0.05). According to experimental conditions of the present work, the results suggest that a twice-daily treatment with aPDT using methylene blue 0.01% in combination with the diode laser (&lambda;=660 nm, 320 J/cm&sup2;, 100 mW, 90 s; 9J) decreases biofilm viability and affects its structural organization.

Avaliar os efeitos da terapia fotodinâmica sobre as funções motoras do sistema nervoso e a dura-máter utilizando os fotossensibilizadores ftalocianina de cloro-alumínio e azul de metileno. Materiais e Métodos: Foram utilizados 56 ratos machos da raça Wistar, divididos em dois grupos. Um grupo foi submetido ao tratamento com terapia fotodinâmica (PDT) e o outro como grupo controle, nos quais foram utilizados os fotosensibilizadores sem a sua foto ativação. Os fotossensibilizadores foram aplicados sobre a dura-máter, após a realização de laminectomia, ao nível da T10. Os métodos de avaliação empregados foram a escala de avaliação funcional de Basso, Beattie e Bresnahan (BBB) e o estudo da dura-máter por meio da microscopia de luz. Resultados: Não foram observadas alterações nas atividades motoras dos animais submetidos à PDT, em relação ao grupo controle. As avaliações histológica e histopatológica não mostraram diferenças entre o grupo dos fotosensibilizadores ativados e o grupo controle, com relação ao processo inflamatório e à necrose tecidual. Conclusão: A PDT em conjunto com os fármacos fotossensibilizantes, ftalocianina de cloro-alumínio e azul de metileno não induziu efeitos neurotóxicos clínicos e/ou alterações histológicas sobre a dura-máter dos animais estudados. / To determine the effects of photodynamic therapy on motor functional activity and the dura mater using the photosensitizers aluminum chloride phthalocyanine and methylene blue. Material and Methods: Fifty-six male Wistar rats were divided into two groups, one submitted to photodynamic therapy (PDT) and the other submitted to the photosensitizers without their photoactivation (control). The photosensitizers were applied to the dura mater after laminectomy at the T10 level. The methods used for assessment were the Basso, Beattie and Bresnahan (BBB) functional evaluation scale and study of the dura mater by light microscopy. Results: No changes in motor activity were observed in the animals submitted to PDT compared to control. Histological and pathological evaluation did not show differences between the group exposed to activated photosensitizers and the control group regarding the inflammatory process and tissue necrosis. Conclusion: The joint use of PDT with the photosensitizing pharmaceuticals aluminum chloride phthalocyanin and methylene blue did not induce any clinical neurotoxic effects or histological changes in the dura mater of the animals studied.

Submitted by Geandra Rodrigues (geandrar@gmail.com) on 2018-05-04T14:16:02Z No. of bitstreams: 0 / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-05-07T15:15:23Z (GMT) No. of bitstreams: 0 / Made available in DSpace on 2018-05-07T15:15:24Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-02-18 / A Laserterapia de Baixa Potência (Low Level Laser Therapy – LLLT) apresenta-se como uma terapia não invasiva reconhecida por acelerar processos reparativos tanto de tecidos moles quanto de tecidos duros devido aos seus efeitos biomoduladores nas células e nos tecidos. Quando há associação de uma fonte de luz de comprimento de onda conhecido a um corante fotossensível de baixa toxicidade, temos a, também conhecida, Terapia Fotodinâmica (Photodynamic Therapy - PDT) que, ainda pouco se sabe sobre sua ação no processo de consolidação óssea. O objetivo deste trabalho foi avaliar o processo de reparo ósseo em ratos submetidos à LLLT associada ou não ao azul de metileno a 0,01%, utilizando-se para isso a avaliação radiográfica e histológica. Defeitos ósseos foram realizados e distribuídos em quatro grupos: não tratados (Grupo controle); preenchidos por azul de metileno e não tratados (Grupo azul de metileno); tratados com laser 660nm (Grupo LLLT); preenchidos por azul de metileno e tratados com laser 660nm (Grupo LLLT + PDT). As radiografias foram realizadas nos dias 0, 7 e 14. Metade dos animais, irradiados ou não, foram eutanasiados após sete dias e a outra metade após 14 dias, sendo os fêmures removidos para análise histológica. Os resultados sugerem que, radiograficamente não houve consolidação óssea em nenhum dos grupos tratados, porém os defeitos ósseos do grupo LLLT + PDT apresentaram maior grau de radiopacidade; histologicamente houve maior aumento da área de neoformação óssea nos grupos LLLT e LLLT + PDT, com destaque para este último em ambos os períodos avaliados. Podemos desta forma, concluir que além da associação da PDT à LLLT ter sido eficaz, a combinação das duas técnicas promoveu indução da osteogênese de maneira precoce. / Low Level Laser Therapy (LLLT) is a recognized noninvasive therapy for accelerating repair processes of both soft and hard tissues due to their biomodulating effects on cells and tissues. When there is an association of a light source of known wavelength with a low toxicity photosensitive dye, we also have the known Photodynamic Therapy (PDT), which is still little known about its action in the process of bone healing. The objective of this work was to evaluate the bone repair process in rats submitted to LLLT, associated or not with 0.01% methylene blue, using radiographic and histological evaluation. Bone defects were performed and distributed in five groups: untreated (control group); filled with methylene blue and untreated (methylene blue group); treated with laser 660nm (LLLT Group); filled with methylene blue and treated with laser 660nm (LLLT + PDT Group). Radiographs were performed on days 0, 7 and 14. Half of the animals, irradiated or not, were euthanized after seven days and the other half after 14 days, and the femurs were removed for histological analysis. The results suggest that radiographically there was no bone consolidation in any of the treated groups, but the bone defects of the LLLT + PDT group presented a higher degree of radiopacity; histologically, there was a greater increase in the area of bone neoformation in the LLLT and LLLT + PDT groups, especially in the two evaluated periods. We can therefore conclude that besides the association of PDT with LLLT was effective, the combination of the two techniques promoted the induction of osteogenesis in an early manner.

M.Sc. (Chemistry) / Please refer to full text to view abstract

Ph.D. / This study comprises the preparation and characterization of new carbene complexes of iron, molybdenum, gold, copper and silver from azolyl and thienyl precursors. In addition, the syntheses of aminoacyl chelate and metallacyclic iron compounds as well as unique 6-membered dimeric and 18-membered trimeric thienyl gold compounds are reported. Furthermore, di(vinyl)carbene complexes, which are not yet known for gold and which are very rare for most other metals, are also described. In contrast to most other carbene complexes that result from precursors in which the heteroatom is situated a or y to the coordinated carbon atom, the new amino(organo)-, organo(thio)- and di(organo) carbene complexes are unique in that they have been prepared from azolyl or thienyl precursors in which the nucleophilic heteroatom is located outside the coordinated ring system and is separated from the coordinated carbon by several bonds. The complex [CpFe(CO)2C1] reacts with lithiated pyrazole, (thienyl)oxazoline or (thienyl)pyridine to form precursor pyrazolyl and thienyl iron(II) compounds which upon alkylation or protonation with CF3SO3Me or CF3SO3H afford amino(organo)-, organo(thio)- or heterometallacyclic alkoxy(amino)- and hydroxy(amino)carbene complexes as well as compounds which show pyridinium character. The heterometallacyclic complexes incorporate unusual ferropyridine or ferropyrole rings. ' 3C-{'}I} NAIR data of the above compounds show that the coordinated carbons of the azolyl and thienyl ligands are significantly affected upon carbene formation, although an X-ray crystallographic investigation indicates that carbene formation has little if any effect on bond distances in the azolyl ligand when it becomes a coordinated azolinylidene. The molecular structures of the pyrazolyl complex [CpFe(C0) 2{C=CHCH=NNPh}], the pyrazolinylidene complex [CPFe(C0) 2{CCHHNHI4P11}1[CF3S03], the 2-(2'-oxazolinyl)thien- 5-ylidene complex [CpFe(C0)2{CCHHC(1\1HCMe2CH26)}1[CF3S03] and the heterometallacyclic complex [CpFe(C0){CC(=&CMe 2CH2(5)SCH---9-1)] indicate small variations in iron-carbon distances of 1.981(2), 1.969(5), 1.99(1) and 1.959(7) A. Four equivalents of 2-(4',5'-dihydro-4',4'-dimethy1-2'-oxazolinyl)thien-3-yllithium reacts with the acetate [Mo2(O2CMe)4] to form the stable, neutral, quadruply bonded dimolybdenum complex [Mo2{C=C(6=NCMe2CH26)SCH2CH2} 2(02CMe)2], while 4-methylthiazoly1 lithium reacts with the same acetate to form the unstable, thiazolyl molybdate [Mo 2{6=NCMe—Cfg} 8]4". Reaction of [AuCI(tht)] (tetrahydrothiophene) with 2-(4',5'-dihydro-4',4'-dimethy1-2'-oxazoliny1)- thien-3-yllithium or 2-(4',5'-dihydro-4',4'-dimethy1-2'-oxazolinyl)thien-5-yllithium afforded dimeric and trimeric thienyl oligomers of gold(I). The molecular structure of the six-membered dimeric compound [Au{C=C(=NCMe 2CH2O)SCH=CH}li shows a Au...Au separation of 2.8450(6)A, while such interactions are absent in the trimeric compound [Au{C=C(C=NCMe2CH2O)SCH=CH}] 3 . Protonation of the former compound as well as the stable monomers obtained from [Au(tht)C 6F5] or [Au(Cl)PPh 3J afforded unique di(vinyl)carbene as well as imine complexes. Reaction of 2-(2'-pyridyl)thien-5-yllithium with [Au(COPPh 3] and subsequent alkylation yields an organo(thio)carbene compound. Finally, a series of cationic copper(I) bis(carbene) complexes were formed upon sequential treatment of copper(I) trifluoromethanesulfonate with thiazolyl- or pyrazolyllithium and CF3SO3Me. A similar reaction with 4-methylthiazol-2-yllithium and silver triflate produced the first amino(thio)carbene complex of silver.

M.Sc. / Please refer to full text to view abstract.

Philosophiae Doctor - PhD / The aim of this study was to design and build an electrohydraulic discharge reactor in such a way that the synthetic immobilized TiO2 nanophotocatalytic components could be integrated, for the production of active species such as OH radicals, ozone and hydrogen peroxide, as a cocktail to clean drinking water without the addition of chemicals. The research objectives include: • To design and construct the different AOP prototypes based on various electrode configurations and compare their operation. • To optimize the discharge parameters and conditions of the best AOP system. • To determine the effectiveness of the best prototype for the degradation of methylene blue as model pollutant. • To compare the designed AOP system with the Sodis method for the disinfection of contaminated river water. • To prepare supported TiO2 nanoparticles via electro spinning, followed by combustion and study the effect on the morphology of TiO2 nanoparticles. • To determine the stability and robustness of composite nano-crystalline TiO2 photocatalysts by sonication • To determine the enhanced effect of combining the composite TiO2 in the AOP system on degradation of methylene blue under the same conditions. • To detect the active species promoting disinfection.

The present study involves the use of main group organometallics: organostannanes and organolithiums as precursors to chromium Fischer carbene complexes. Fischer carbenes are well stabilized by the π‐donor substituents such as alkoxy and amino groups and low oxidation state metals such as Group 6 (Chromium, Molybdenum or Tungsten). Carbenes are an important intermediate in the synthesis of a range of compounds through cyclopropanations, insertions, coupling and photochemical reactions. Synthesis and successful characterisation of three α‐alkoxystannanes was achieved via nucleophilic addition of tributylstannyllithium to the respective aldehydes, followed by an immediate MOM protection of the resulting alcohol. Six α‐aminostanannes were synthesised, consisting of N‐BOC, N‐acetyl and N‐ethyl derivatives of pyrrolidine and piperidine, via α‐lithiation and subsequent tinlithium transmetallation in the presence of TMEDA. The ¹³C NMR analysis highlighted an interesting phenomenon of tin‐carbon coupling that revealed unique structural information of both types of stannanes. DFT analysis was completed on the series of stannanes; a predicted frequency analysis was obtained which complemented the experimental Infra‐red data in elucidation of the compounds. The α‐alkoxy and α‐aminostannanes provided stable precursors to the organolithiums required for the synthesis of the novel Fischer chromium carbenes. The organolithiums were obtained via tinlithium exchange at low temperatures, followed by the addition of chromium hexacarbonyl to form the acylpentacarbonyl‐chromate salt. Alkylation of this intermediate using a Meerwein salt, Me₃OBF₄, gave rise to the novel Fischer chromium carbene complexes. Fischer chromium carbenes derived from the two isomeric butyl and isobutyl stannanes and the two N‐ethyl α‐aminostannanes were successfully synthesised. The difficulty encountered in the purification of the Fischer carbene complexes hindered the full characterisation, due to the presence of a by‐product, tetrabutyltin.