Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2018-03-02T23:17:21Z No. of bitstreams: 1 NivaldoFreireDeAndradeNeto_DISSERT.pdf: 3043754 bytes, checksum: 81f701dde4d2487b0d56ee58677070b6 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2018-03-13T18:18:43Z (GMT) No. of bitstreams: 1 NivaldoFreireDeAndradeNeto_DISSERT.pdf: 3043754 bytes, checksum: 81f701dde4d2487b0d56ee58677070b6 (MD5) / Made available in DSpace on 2018-03-13T18:18:44Z (GMT). No. of bitstreams: 1 NivaldoFreireDeAndradeNeto_DISSERT.pdf: 3043754 bytes, checksum: 81f701dde4d2487b0d56ee58677070b6 (MD5) Previous issue date: 2017-06-16 / O crescimento das atividades industriais vem proporcionando um aumento na gera??o de efluentes, que fez com que ?rg?os governamentais relacionados ao meio ambiente propusessem a cria??o de marcos regulat?rios para limitar a gera??o de efluentes. Os efluentes gerados pelas ind?strias t?xteis s?o de dif?cil degrada??o por m?todos tradicionais de tratamento. Os processos oxidativos avan?ados (POAs) s?o uma alternativa eficiente para a degrada??o de poluentes org?nicos, como corantes (azul de metileno). Neste trabalho, part?culas de cloreto de prata (AgCl) impregnadas com ?xido de cobre (CuO) foram sintetizadas via m?todo sonoqu?mico. Foram preparadas composi??es molares de 1:1 e 2:1 de AgCl/CuO, respectivamente. Tais composi??es passaram por tr?s rotas de obten??o distintas. Para a caracteriza??o das part?culas, utilizou-se as t?cnicas de difra??o de raios-X (DRX), microscopia eletr?nica de varredura com emiss?o de campo (MEV-FEG), e espectroscopia UV-vis?vel (UV-vis). Para verificar a aplicabilidade do composto foram realizados nas amostras de AgCl/CuO testes fotocatal?ticos para degrada??o do corante azul de metileno e a atividade antimicrobiana frente ?s bact?rias Escherichia coli e Staphylococcus aureus. Os resultados da difra??o de raios-X confirmaram a forma??o de AgCl e CuO em todas as amostras, n?o havendo ind?cios de dopagem para nenhuma rota utilizada. Os resultados da atividade fotocatal?tica indicam que o aumento da propor??o molar de AgCl (1:1 para 2:1) acelera a degrada??o do azul de metileno em m?dia em 25%. / The growth of industrial activities has led to an increase in the generation of effluents, which led environmental agencies to propose the creation of regulatory frameworks to limit the generation of effluents. The effluents generated by the textile industries are difficult to be degraded by traditional methods of treatment. Advanced oxidative processes (POAs) are an efficient alternative for the degradation of organic pollutants such as dyes (methylene blue). In this work, silver chloride particles (AgCl) impregnated with copper oxide (CuO) were synthesized via method sonochemistry. AgCl/CuO 1:1 and 2:1 molar compositions, respectively, were prepared. Such compositions went through three distinct procurement routes. To characterize the particles, X-ray diffraction (XRD), scanning electron microscopy with field emission (SEM-FEG), and UV-visible (UV-vis) spectroscopy were performed. To verify the applicability of the compound were carried out in the samples of AgCl/CuO photocatalytic tests for degradation of the methylene blue dye and the antimicrobial activity against the bacteria Escherichia coli and Staphylococcus aureus. The results of X-ray diffraction confirmed the formation of AgCl and CuO in all samples, with no evidence of doping for any route used. The results of the photocatalytic activity indicate that increasing the molar ratio of AgCl (1:1 to 2:1) accelerates the degradation of methylene blue on average by 25%.

Electroanalysis offers cheap and selective analysis of interesting solutions. However, one of the most common drawbacks is the accessibility for electrochemical sensing. By using high-pressure microfluidics with an integrated three-electrode system, new possibilities open for increased accessibility. Therefore, there is a need to fabricate sustainable reference surfaces into highly pressure tolerant microchannels. In this thesis, Ag/AgCl reference surfaces were in-situ fabricated in high-pressure microfluidic chips. This was performed by electroplating Ag on thin film Pt in microchannels and then chlorinating the silver into Ag/AgCl. Electroanalysis of ferrocyanide was carried out in a microfluidic chip using one of the in-situ fabricated Ag/AgCl references. The half-wave potential showed to be around +251 mV and the electrochemical water window was measured to 1400 mV with a range between -300 mV and +1100 mV. The obtained values show to be comparable to reference data of similar experiments performed elsewhere. For some applications of electrochemistry, a catalysis surface is beneficial. Nanoporous Pt black has proved to generate high catalytic performance in electrochemistry. Therefore, attempts have been carried out to fabricate Pt black onto Pt thin films, with the vision to succeed with such fabrication within microfluidic channels. To summarize, this project work has showed a possibility to in-situ fabricate Ag/AgCl reference surfaces. The project has also showed how to use such surfaces as reference electrodes for electroanalysis in high-pressure microfluidic chips. Lastly, new challenges and ideas to fabricate catalysis surfaces on thin film electrodes in flow channels have been presented. By this thesis, one more step has been taken to increase the accessibility for electroanalysis.

Melanoma skin cancer is the abnormal growth of the melanocytes – the pigmented cells located in the epidermis. The current gold standard diagnostic technique for determining whether a lesion is cancerous involves subjectively examining suspicious lesions and performing an invasive biopsy to confirm melanoma. This method may neglect some lesions or cause scarring from biopsies that turn out to be benign. Thus, impedance-based detection using a multi-electrode device was investigated as a noninvasive technique to diagnose melanoma skin cancer. The multi-electrode device was designed with 8 equally spaced Ag/AgCl electrodes surrounding one central electrode at a 5 mm radius. The electrodes were held in place by a vice-like mechanism using three circular Delrin sections. The electrodes were interfaced to an 8:1 multiplexer and National Instruments Educational Laboratory Virtual Instrumentation Suite (ELVIS) for measurement control and impedance analysis. The ELVIS system, multiplexer, and electrode device were validated for accuracy with various values of resistors and capacitors. Raw and cooked chicken thigh meat and skin were tested to evaluate the capabilities of the electrode device to discern different tissue types and tissue moisture contents by impedance measurements. EpidermTM and Melanoma tissue-engineered skin analogues, provided by MatTek Corporation, were tested to mimic the in situ disease state. The electrode device was found to produce reliable measurements for known electrical components with resistances between 10 ohms and 100 k-ohms and capacitances between 10 nF and 10 uF. The measurements from the chicken tissues and tissue-engineered skin constructs – excluding cooked chicken skin data – fell within the reliable range of the electrode device and were thus considered reliable as well. All analyses concluded that a statistical difference between the impedances of raw meat and raw skin, cooked meat and raw meat, and EpidermTM and Melanoma existed. Therefore, the hypothesis that a multi-electrode device could differentiate between melanoma and healthy skin tissues based on impedance measurements was satisfied.

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