Th. doct.-ing.--Phys.-chim. des matér.--Toulouse--I.N.P., 1979. N°: 76.

Th.--Sci. phys.--Lille 1, 1978. N°: 425.

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O cobalto é um dos principais componentes das ligas metálicas fundidas amplamente utilizadas na odontologia. Ele é considerado o constituinte de 45 a 70% de inúmeros trabalhos protéticos. Há evidência de elementos metálicos causarem toxicidade sistêmica e local. Este trabalho teve como objetivo, avaliar os efeitos do cobalto no epitélio juncional, epitélio adamantino, epitélio da gengiva inserida e ligamento periodontal do 1° molar superior do rato, durante a lactação. Para tal, foram utilizados ratos com 1 dia de vida pós-natal, cujas mães receberam 300mg de cloreto de cobalto por litro de água destilada no bebedouro (grupo tratado -T) e ratos cujas mães não receberam CoCl2 (grupo controle - C), durante toda a lactação. Ao final de 21dias, os filhotes foram sacrificados com sobredosagem anestésica. As cabeças foram separadas e fixadas em solução de alfac (álcool 80%- 85ml, formalina 10ml e ácido acético 5ml) incluídas em parafina e os cortes frontais seriados foram corados com hematoxilina e eosina. Os cortes foram focalizados ao microscópio de luz (100X), munido de uma câmara clara. Os núcleos das células dos tecidos estudados foram projetados sobre o papel com aumento final de 1000X e 50 núcleos de cada estrutura foram contornados com lápis preto para posterior medição do diâmetros maior (D) e menor (d). Uma vez determinados os diâmetros, foram estimados os seguintes parâmetros cariométricos: diâmetro geométrico médio, relação entre D/d, perímetro, área, volume, relação entre volume e área, excentricidade, coeficiente de forma e índice de contorno. Neste trabalho também foi utilizada uma grade impressa sobre papel. As imagens obtidas foram desenhadas sobre a grade. A grade pode ser usada tanto para contar pontos sobre uma determinada estrutura histológica bem como para contar intersecções entre duas estruturas contíguas, bastando para isso, no primeiro caso, considerar o número de pontos que caem sobre a estrutura em estudo, ou, no segundo caso, o número de vezes em que as superfícies vizinhas cortam a linha curva. Com a finalidade de se avaliar o volume citoplasmático, o volume celular, a relação núcleo/citoplasma, a densidade numérica celular, a relação superfície externa/camada basal, a espessura das camadas epiteliais e a densidade de superfície, foi utilizada ora a contagem de pontos ora o número de intersecções e aplicados às equações estereológicas apropriadas para cada uma dessas variáveis. Todos os dados colhidos foram submetidos à estatística não paramétrica - Teste de Wilcoxon-Mann-Whitney. Os núcleos dos tecidos estudados mostraram valores diminuídos, após cariometria, para os diâmetros maior, menor e médio; volume, área, perímetro e relação volume/área. Estereologicamente foi possível observar, no epitélio juncional, epitélio adamantino e no epitélio da gengiva inserida, células menos volumosas com citoplasma mais escasso levando a um maior número de células por mm3 de tecido. O ligamento periodontal também se apresentou desorganizado e com fibras de menor tamanho. Neste estudo, o cobalto ocasionou um quadro de hipotrofia epitelial, indicando uma ação direta nos epitélios juncional e adamantino, epitélio da gengiva inserida bem como no ligamento periodontal. / Cobalt is one of the main components of cast metal alloys broadly used in dentistry. It is the constituent of 45 to 70% of numerous prosthetic works. There is evidence that metal elements cause systemic and local toxicity. The purpose of the present study is to evaluate cobalt effects on the junctional epithelium, adamantine epithelium, inserted gum epithelium, and periodontal ligament of the superior first molar in rats, during lactation. To do this, 1-day old rats were used, whose mothers received 300mg of cobalt chloride per liter of distilled in the drinker (treated group T) and rats whose mothers did not receive CoCl2 (control group C), during lactation. After 21 days, the rat pups were killed with an anesthetic overdose. The heads were separated and fixed in an alfac solution (80% alcohol-85ml, formaline-10ml, and acetic acid-5ml), embedded in paraffin and stained with hematoxylin and eosin. The cuts were viewed under a light microscope (100X) with a clear chamber. The nucleus of the studied tissue cells were projected on paper with a final increase of 100X. Fifty nuclei from each structure were outlined with a black pencil so that the greater (D) and smaller (d) diameters could be measured. After determining the diameters, the following cariometric parameters were established: mean geometric diameter, D/d relation, perimeter, area, volume, volume/area relation, eccentricity, form coefficient, and contour index. This study also used a grid printed on paper. The images obtained were drawn over the grid, which was used to count points over a certain histological structure as well as to count intersections between two contiguous structures. All that was needed, in the first case, was to consider the number of points located over the studied structure, or, in the second case, the number of times that neighboring surfaces cut the curve line. With the aim to evaluate the cytoplasmic volume, cellular volume, cytoplasm/nucleus relation, cellular numeric density, external surface/basal layer relation, the thickness of epithelial layers, and surface density, point counting was used at times and, at others, the number of intersections was considered and applied to the appropriate stereological equations for each variable. All the collected data were subjected to non-parametric statistics Wilcoxon-Mann-Whitney Test. The nuclei of the studied tissues showed reduced values after cariometry for: greater, smaller, and mean diameter; volume; area; perimeter; and volume/area relation. Stereologically, it was observed, in the junctional epithelium, adamantine epithelium, and in the inserted gum epithelium, cells with less volume and with scarce cytoplasm, which caused a greater number of cells per mm3 of tissue. The periodontal ligament was also disorganized and with smaller fibers. In this study, cobalt caused epithelial hypertrophy symptoms, indicating a direct action on the junctional and adamantine epithelium, inserted gum epithelium, as well as on the periodontal ligament.

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The use of rare and expensive noble metals in the chemical industry as organometallic catalysts has grown exponentially in the past few decades due to their high activity, selectivity and their ability to catalyze a wide range of reactions. With this growth in use has also come a proportional growth in concern as these toxic metals inevitably leach into the environment and their negative effects on public health and our ecosystems are becoming better understood. First-row transition metal catalysts provide both environmental and economic benefits as alternatives to these noble metals due to their lower toxicity and cheaper costs. The two-electron chemistry that makes the noble metals so attractive however, is more challenging to accomplish with first-row transition metals. Intelligently designing the ligand scaffold which surrounds the metal can mitigate or even eliminate some of the shortfalls of these first-row metals. Some key features that should be considered when designing a ligand are: 1) a strong chelating ability so the ligand can stay attached to the metal, 2) incorporation of strong donors to favour low-spin complexes, 3) inclusion of hemilabile groups to allow for substrate activation and metal stabilization throughout various oxidation states, 4) redox activity to be able to donate or accept electrons, and 5) inclusion of Lewis base functionalities which are able to assist the substrate activation. Ligands which incorporate these features are known as bifunctional ligands as they can accomplish more than one function in the catalytic cycle. Developing first-row transition metal complexes containing these ligands may enable these species to replicate the reactivity and selectivity generally associated with the precious metals. Being able to replace the noble metals used in industry with these catalysts would have tremendous environmental and economic benefits. The objective of this thesis is to advance the field of bifunctional catalysis by examining the behaviour of two sterically svelte, tridentate SNS ligands containing hard nitrogen and soft sulphur donors when bonded to cobalt. Previous work with iron provides a template of the ligand behaviour to which cobalt can be compared, allowing us to contrast the effects exerted by the different metals. After an introduction to bifunctional catalysis in Chapter 1, Chapter 2 describes the reactivity of the amido ligand, SMeNHSMe, with precursors ranging from Co(I) to Co(III), all of which yielded the 19e- pseudooctahedral cobalt(II) bis-amido complex, Co(SMeN-SMe)2 characterized by 1H NMR spectroscopy, single-crystal X-ray crystallography and cyclic voltammetry. Although this complex has a similar structure as the Fe analogue, the cobalt bis-amido complex did not exhibit the same hemilabile behaviour that allowed for simple ligand substitution of one of the thioether groups. Instead it reacted reversibly with 2,2’-bipyridine while 1,2-bis(dimethylphosphino)ethane (DMPE) and 2,6-dimethylphenyl isocyanide both triggered additional redox chemistry accompanied by the loss of protonated SMeNHSMe. In contrast, protonation gave the cobalt(II) amido-amine cation, [Co(SMeNSMe)(SMeNHSMe)](NTf2), which allowed for substitution of the protonated ligand by acetonitrile, triphenylphosphine and 2,2’-bipyridine based on 1H NMR evidence. The ability of Co(SMeNSMe)2 to act as a precatalyst for ammonia-borane dehydrogenation was also probed, revealing that it was unstable under these conditions. Addition of one equivalent of DMPE per cobalt, however, resulted in better activity with a preference for linear aminoborane oligomers using ammonia-borane and, surprisingly, to a change in selectivity to prefer cyclic products when moving to methylamine-borane. Chapter 3 delves into the chemistry of the thiolate ligand, SMeNHS, which formed a new 18e- cobalt(III) pseudooctahedral complex, Co(S-NC-)(SMe)(DEPE), from oxidative addition of the Caryl-SMe bond. Scaling up this reaction resulted instead in formation of an imine-coupled [Co(N2S2)]- anion which was characterized by 1H NMR/EPR spectroscopy, single-crystal X-ray diffraction, cyclic voltammetry and DFT studies. The latter revealed an interesting electronic structure with two electrons delocalized in the ligand, demonstrating the non-innocent nature of the N2S2 ligand. While the analogous iron complex proved to be an effective pre-catalyst for the hydroboration of aldehydes with selectivity against ketones, this behaviour was not observed with [Co(N2S2)]- which gave a slower rate and less selectivity. The knowledge acquired from this thesis work has advanced the field of bifunctional catalysis by extending the application of these two SNS ligands from iron to cobalt, revealing unpredictable differences in reactivity between the metals. By comparing the behaviour of these ligands with iron and cobalt, we gain a better understanding of the chemistry that is accessible by these ligands and the applications for which they may be used. This increased knowledge contributes to our long-term goal of replacing expensive and toxic noble metals with more benign first-row transition metals, improving the sustainability of the chemical industry.

Made available in DSpace on 2015-07-13T12:10:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-02-27. Added 1 bitstream(s) on 2015-07-13T12:25:31Z : No. of bitstreams: 1 000774014.pdf: 12821095 bytes, checksum: 285ff82ff157f6e1d186ff370d96e92a (MD5) / Este trabalho aborda a deposição de cobalto sobre zinco utilizando a técnica de deslocamento galvânico. Inicialmente foi feito um estudo detalhado do zinco nas diversas condições em que foram depositados os filmes de cobalto. Os filmes de cobalto foram sintetizados em banhos de cloreto e sulfato com e sem glicina em pH 3 e 5 e analisados por SEM, MO, EDXS, XDR e VSM. Durante o processo de deposição foi monitorado o potencial em circuito aberto e adicionalmente foram realizadas medições de espectroscopia de impedância eletroquímica com a finalidade de elucidar os possíveis processos que ocorrem durante a deposição. Os filmes de cobalto obtidos mostram que a adição de glicina resulta numa deposição mais homogênea e sem a formação de produtos secundários como Zn5(OH)8Cl2.2H2O e Zn4(SO4)(OH)6.4H2O. A adição da glicina ainda revela uma maior evolução de hidrogênio no sistema, possivelmente relacionada à desprotonação do íon glicinato. O estudo eletroquímico do processo de deposição através de medições de potencial em circuito aberto revela maior estabilidade de potencial com a utilização de glicina no banho. O monitoramento da deposição de cobalto utilizando EIS mostra que os íons Co2+ facilitam o processo de dissolução de Zn. Com o aumento da concentração de glicina e do tempo de deposição aumenta os valores de capacitância da dupla camada elétrica e diminui a resistência à transferência de carga, sugerindo que ambas variáveis induzem o crescimento da área do eletrodo. As medidas das propriedades magnéticas mostram uma maior deposição de material metálico magnético em pH 3 em cloreto e sem a utilização de glicina, sendo que com a adição da mesma foi observado maior quantidade de cobalto metálico depositado em pH 5. Já em sulfato observa-se maior deposição de cobalto metálico na presença e ausência de glicina ambos em pH 5. / This work comprises the cobalt deposition onto zinc by using the galvanic displacement technique. The cobalt films were prepared from chloride and sulfate baths with and without glycine, and at pH 3 and 5. The deposits were characterized by: SEM, OM, EDXS, XRD and VSM. During the deposition process, it was monitored the open circuit potential and subsequently were conducted electrochemical impedance spectroscopy (EIS) measurements in order to elucidate the possible processes that may occur during the galvanic deposition. The results showed that the glycine addition leads to a more homogeneous deposition and no byproducts, such as Zn5(OH)8Cl2.2H2O and Zn4(SO4)(OH)6.4H2O, are formed. Furthermore, the glycine addition to the bath revealed a higher hydrogen evolution during the deposition process, possibly related to the deprotonation of glycinate ion. The electrochemical study of the galvanic displacement process by measuring the open circuit potential revealed a higher potential stability when glycine was employed in the bath. The monitoring of cobalt deposition by EIS showed that the Co2+ ions facilitate the process of Zn dissolution. By increasing the glycine concentration and the deposition time, the capacitance values, related to the double electric layer, increase and the charge transfer resistance decreases, suggesting that both parameters induce an increase in the electrode area. The magnetic properties of the Co deposits, extracted from the VSM measurements, exhibited the highest saturation magnetization for the deposit obtained from chloride bath at pH 3 without the glycine addition, indicating the presence of a higher amount of metallic Co in this condition. In the case of the sulfate bath, the highest saturation magnetization was reached for the deposits obtained at pH 5 in the presence of glycine.

Made available in DSpace on 2014-11-10T11:09:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-02-27Bitstream added on 2014-11-10T11:57:26Z : No. of bitstreams: 1 000774014.pdf: 12821095 bytes, checksum: 285ff82ff157f6e1d186ff370d96e92a (MD5) Bitstreams deleted on 2015-02-04T11:39:29Z: 000774014_20150625.pdf,Bitstream added on 2015-02-04T11:40:14Z : No. of bitstreams: 1 000774014_20150625.pdf: 1019373 bytes, checksum: 653cd9b6f404483574e7bea6de40de53 (MD5) Bitstreams deleted on 2015-04-13T18:26:29Z: 000774014_20150625.pdf,Bitstream added on 2015-04-13T18:27:07Z : No. of bitstreams: 1 000774014_20150625.pdf: 1019373 bytes, checksum: 653cd9b6f404483574e7bea6de40de53 (MD5) / Este trabalho aborda a deposição de cobalto sobre zinco utilizando a técnica de deslocamento galvânico. Inicialmente foi feito um estudo detalhado do zinco nas diversas condições em que foram depositados os filmes de cobalto. Os filmes de cobalto foram sintetizados em banhos de cloreto e sulfato com e sem glicina em pH 3 e 5 e analisados por SEM, MO, EDXS, XDR e VSM. Durante o processo de deposição foi monitorado o potencial em circuito aberto e adicionalmente foram realizadas medições de espectroscopia de impedância eletroquímica com a finalidade de elucidar os possíveis processos que ocorrem durante a deposição. Os filmes de cobalto obtidos mostram que a adição de glicina resulta numa deposição mais homogênea e sem a formação de produtos secundários como Zn5(OH)8Cl2.2H2O e Zn4(SO4)(OH)6.4H2O. A adição da glicina ainda revela uma maior evolução de hidrogênio no sistema, possivelmente relacionada à desprotonação do íon glicinato. O estudo eletroquímico do processo de deposição através de medições de potencial em circuito aberto revela maior estabilidade de potencial com a utilização de glicina no banho. O monitoramento da deposição de cobalto utilizando EIS mostra que os íons Co2+ facilitam o processo de dissolução de Zn. Com o aumento da concentração de glicina e do tempo de deposição aumenta os valores de capacitância da dupla camada elétrica e diminui a resistência à transferência de carga, sugerindo que ambas variáveis induzem o crescimento da área do eletrodo. As medidas das propriedades magnéticas mostram uma maior deposição de material metálico magnético em pH 3 em cloreto e sem a utilização de glicina, sendo que com a adição da mesma foi observado maior quantidade de cobalto metálico depositado em pH 5. Já em sulfato observa-se maior deposição de cobalto metálico na presença e ausência de glicina ambos em pH 5. / This work comprises the cobalt deposition onto zinc by using the galvanic displacement technique. The cobalt films were prepared from chloride and sulfate baths with and without glycine, and at pH 3 and 5. The deposits were characterized by: SEM, OM, EDXS, XRD and VSM. During the deposition process, it was monitored the open circuit potential and subsequently were conducted electrochemical impedance spectroscopy (EIS) measurements in order to elucidate the possible processes that may occur during the galvanic deposition. The results showed that the glycine addition leads to a more homogeneous deposition and no byproducts, such as Zn5(OH)8Cl2.2H2O and Zn4(SO4)(OH)6.4H2O, are formed. Furthermore, the glycine addition to the bath revealed a higher hydrogen evolution during the deposition process, possibly related to the deprotonation of glycinate ion. The electrochemical study of the galvanic displacement process by measuring the open circuit potential revealed a higher potential stability when glycine was employed in the bath. The monitoring of cobalt deposition by EIS showed that the Co2+ ions facilitate the process of Zn dissolution. By increasing the glycine concentration and the deposition time, the capacitance values, related to the double electric layer, increase and the charge transfer resistance decreases, suggesting that both parameters induce an increase in the electrode area. The magnetic properties of the Co deposits, extracted from the VSM measurements, exhibited the highest saturation magnetization for the deposit obtained from chloride bath at pH 3 without the glycine addition, indicating the presence of a higher amount of metallic Co in this condition. In the case of the sulfate bath, the highest saturation magnetization was reached for the deposits obtained at pH 5 in the presence of glycine.

abstract: We report the synthesis of novel boronic acid-containing metal-organic frameworks (MOFs), which was synthesized via solvothermal synthesis of cobalt nitride with 3,5-Dicarboxyphenylboronic acid (3,5-DCPBC). Powder X-ray diffraction and BET surface area analysis have been used to verify the successful synthesis of this microporous material. We have also made the attempts of using zinc nitride and copper nitride as metal sources to synthesize the boronic acid-containing MOFs. However, the attempts were not successful. The possible reason is the existence of copper and zinc ions catalyzed the decomposition of 3,5-Dicarboxyphenylboronic acid, forming isophthalic acid. The ended product has been proved to be isophthalic acid crystals by the single crystal X-ray diffraction. The effects of solvents, reaction temperature, and added bases were investigated. The addition of triethylamine has been shown to tremendously improve the sample crystallinity by facilitating ligand deprotonation / Dissertation/Thesis / Masters Thesis Chemical Engineering 2014

Orientador: Yukio Kobayashi / Banca: Gilberto de Magalh B. Gonçalves / Banca: Rodolfo Libardi / Resumo: A indústria busca uma melhor otimização e performance de seus equipamentos, há muito notou-se a importância da contenção do desgaste para o aumento de vida útil dos componentes de máquinas. Em condições operacionais onde há o desgaste por abrasão, comumente faz-se o endurecimento da camada superficial ou a aplicação de uma liga mais nobre e de dureza mais elevada, visando conter este desgaste. A técnica também é chamada de revestimento. Entender melhor os parâmetros que influenciam nos resultados da aplicação destes revestimentos torna-se importante possibilitando menores perdas e uma maior economia, pois busca-se como alvo trabalhar com a melhor performance do revestimento. Objetivou-se neste trabalho o estudo das ligas a base de Cobalto que são aplicadas cada vez mais rotineiramente nas indústrias petroquímicas, onde os componentes e órgãos de máquinas estão expostos a condições severas de desgaste por abrasão e corrosão além da severidade dos trabalhos a altas temperaturas e pressão. Relacionando o desgaste, as ligas a base de Cobalto possuem uma posição destacada e a liga é conhecida comercialmente como "Stellite 6". Em alguns trabalhos é chamada também de liga coringa por sua versatilidade e destaque em especial. Neste trabalho procurou-se variar as velocidades de resfriamento em cinco patamares, analisou-se a influência da diluição na micro-dureza e os efeitos da variação da velocidade de resfriamento no mecanismo de endurecimento. A aplicação do revestimento ocorreu em três camadas através do processo TIG. Verificamos ainda a interferência da diluição na dureza em cada camada de revestimento. A terceira e última camada foi a que apresentou maior dureza devido à menor diluição com o metal base principalmente no corpo de prova que possuía à menor velocidade de resfriamento devido ao tempo para a formação de precipitados e carbonetos na liga metálica / Abstract: The industry searchs a better optimization and performance of their equipment, long noted the importance of containment to increase the wear life of components of machines. In operating conditions where there is wear by abrasion, usually it is the hardening of the surface layer or the application of a more noble alloy and high hardness, wear it to contain. The technique also called hardfacing. Better understand the parameters that influence the results of applying these coatings becomes important because it enables lower losses and greater economy as it seeks to target work with the best performance of the coating. The objective of this research is complements the study of cobalt-based alloys that are applied more routinely in petrochemical industries, where the component units and machines are exposed to severe conditions of wear by abrasion and corrosion than the severity of the work at high temperatures and pressure. Relating the wear, the cobalt-based alloys have a prominent position and the league is known commercially as "Stellite 6". Some work is also called the league wildcard for its versatility and highlight in particular. In this work we have tried to vary the speed of cooling in five steps, looked up the influence of dilution on micro hardness and the effects of variation in the rate of cooling in the hardening mechanism. The application of the coating occurred in three layers using the TIG process. We note also the interference of dilution in hardness in each layer of coating. The third and final layer was the one with higher hardness due to less dilution with the base metal mainly in the body of evidence that had the lowest rate of cooling due to the time for the formation of precipitates and carbides in the metal / Mestre