A new preparative route to the only neutral chromium (V) oxide fluoride, chromium oxide trifluoride, has been accomplished by the reaction of xenon difluoride with chromyl fluoride at high temperature. The chromium oxide trifluoride is produced as crystals which are suitable for single crystal studies. In reactions of chromium oxide trifluoride with alkali and alkaline metal fluorides in anhydrous hydrogen fluoride, new chromium(V) oxide fluoride salts were obtained; these salts were not of high purity due to unknown problems. An attempt to prepare chromium oxide tetrafluoride by the reaction of xenon difluoride with chromyl fluoride in anhydrous hydrogen fluoride failed to produce the desired product.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1963. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Adverse tissue reactions to hip prostheses containing CoCr alloys have been widely reported, particularly for implants utilising a metal-on-metal bearing surface or, more recently, a modular taper junction and have been termed Adverse Response to Metal Debris (ARMD). Histological assessments of synovial tissues from patients at revision operation often demonstrate an extensive accumulation of macrophages and abundant tissue necrosis or fibrosis. The inflammatory response starts with the recruitment of immune cells and requires the egress of macrophages from the inflamed site for resolution of the reaction. Metal particles have previously been shown to affect cell migration but the effects of cobalt and chromium on macrophages' motility remain largely unknown. In vitro and in vivo macrophage migration during exposure to cobalt and chromium ions and nanoparticles were examined in this thesis. Cobalt, but not chromium, was found to significantly reduced macrophage motility (>50%). This was found to involve an increase in both cell spreading and the formation of intracellular podosome-type adhesion structures, as well as enhanced cell adhesion to the extracellular matrix (ECM). The formation of podosomes was also associated with the production and activation of matrix metalloproteinase-9 (MMP9) and enhanced ECM degradation. These effects were driven by the down-regulation of RhoA signalling through the generation of reactive oxygen species (ROS). The effect of the Co2+ and Cr3+ metal ions on tissue remodelling and pseudotumour formation which can lead to pain, swelling, limited range of joint movement and extensive tissue lesions, was explored using a multiscale approach. Both 2D and 3D in vitro culture systems were deplored to examine the effects of these ions on human fibroblast activation and mechanobiology. It was observed that Co2+ induced a fibrotic response characterised by cytoskeletal remodelling and enhanced collagen matrix contraction. This was associated with an increase in cell stiffness (~45%) and contractile forces (~80%) measured by atomic force microscopy and traction force microscopy, respectively. These effects were also triggered by the generation of ROS. Moreover, this fibrotic response was enhanced in the presence of macrophages, which increased the prevalence of α-SMA positive fibroblasts and collagen synthesis. These events were verified in vivo by examining the synovial fibroblasts and tissues from hips of patients with metal-on-metal hip implants and patients undergoing primary hip replacement. The findings revealed that fibroblasts isolated from patients undergoing MoM revision THA were more biomechanically active than the control group. Moreover, synovial tissues from patients undergoing MoM revision THA displayed evidence of extensive tissue remodelling and fibrosis. These findings revealed that cobalt leads to adverse tissue reactions via inducing macrophage retention, fibroblast-mediated matrix remodelling and modulating the interplay between macrophage and fibroblast. These distinctive effects can help us understand the pathogenesis of ARMD and the cellular response to cobalt-based alloys, which will inform biocompatibility test protocols and future implant designs.

Tez (Yüksek Lisans) - Süleyman Demirel Üniversitesi, Fen Bilimleri Enstitüsü, Kimya Anabilim Dalı, 2007. / Bibliyografya var.

Made available in DSpace on 2014-10-09T12:51:56Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:55Z (GMT). No. of bitstreams: 0 / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:51:56Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:55Z (GMT). No. of bitstreams: 0 / Atualmente são muito discutidos temas que abordam a preservação do meio ambiente, para o desenvolvimento de tecnologias de produção que não a agridam, gerando resíduos menos tóxicos e em menor quantidade. Resíduos poluentes contendo metais como o crômio, têm sido lançados nos solos e rios, degradando a água utilizada para o consumo humano. Não diferentes são os problemas decorrentes de atividades nucleares, as quais geram rejeitos nas instalações e laboratórios de pesquisa. Embora estes rejeitos não sejam lançados no meio ambiente, muitas vezes encontram-se armazenados em laboratório inadequadamente, o que pode resultar em graves acidentes. Na intenção de solucionar estes problemas, existem várias técnicas para o tratamento de rejeitos, entre elas a troca iônica eletroquímica (EIX – electrochemical ion exchange). A EIX é um processo avançado que une as vantagens da troca iônica convencional com o fato de usar como reagente o elétron, reduzindo consideravelmente o volume da solução a ser tratada. Esta técnica consiste na elaboração de um eletrodo, no qual o trocador iônico é incorporado fisicamente em uma estrutura do eletrodo com um aglutinante. Optou-se neste trabalho pela resina catiônica Amberlite CG-50 para o tratamento dos rejeitos contendo íons crômio e o trocador catiônico inorgânico fosfato de zircônio para os íons césio, pois apresentam boa estabilidade química em meio oxidante e perante radiação ionizante. A quantidade de carvão, de grafita e aglutinante para a formulação do eletrodo mais eficiente também foi estudada. Após a escolha dos melhores eletrodos, verificaram-se retenções para o Cr e para o Cs da ordem de 99,3% e 99,8%, respectivamente. A eluição completa tanto do íon crômio quanto do íon césio, sem nenhuma adição de reagentes, revelou-se uma das principais vantagens deste processo, o que torna possível a reutilização do eletrodo sem perda de sua capacidade. Com base nos resultados apresentou-se um processo contínuo de tratamento de rejeitos utilizando-se uma célula eletrolítica de fluxo (CELFLUX) de alta capacidade de retenção para o íon Cr e Cs. A alta eficiência desta célula tanto na retenção quanto na eluição, levando a uma redução importante no volume do rejeito e, até mesmo, possibilitando a reutilização dos íons separados, torna o processo altamente viável para o emprego industrial. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP