Navegando por Palavras-chave "Eletroquímica"
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- ItemSomente MetadadadosConselhos Tutelares E Articulação Política(Universidade Federal de São Paulo (UNIFESP), 2017-12-11) Angulo, Kathleen Ferreira [UNIFESP]; Vazquez, Daniel Arias [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)The creation of the Child Care Councils in Brazil was established in 1990 along with the Child and Adolescent Statute (ECA). Capturing the promises of redemocratization, social participation and the demand for rights, the Councils were thought and designed as community bodies with representatives elected from time to time, being responsible for assignments ranging from the care of children and adolescents violated in their rights to the search for the prevention of violation, such as advising the local government in the development of the budget proposal for plans and programs related to the rights of children and adolescents. The literature on the subject is produced within several areas of knowledge - with a predominance of the health area - and little worked by the Social Sciences, especially regarding the relation of the Child Care Councils with the public policies. In general, the researches highlight the importance of this instrument for guaranteeing the rights of children and youth, but note that: i. the Child Care Councils do not have adequate infrastructure for the execution of the work, whether it is related to the places of care or related to the poor formation of the counselors and their low remuneration; ii. the Child Care Councils do not have their role understood neither by society nor by the public sector, which creates a series of constraints and difficulties to the daily work; iii. the Child Care Councils have distanced themselves from the ECA proposal, since they still reproduce the "minorist" ideology and have approached the Judiciary to the detriment of the rapprochement with local communities and social movements. In order to understand the role of the Child Care Councils in the elaboration of public policies and the factors for a Council to act for this purpose, this study studied five Child Care Councils of the city of Guarulhos (SP) during the year 2017. The results point that, given the fragility of the relationship with the channels of the municipal service network, the lack of training that the counselors receive, and the poor regulation of public policy for children and adolescents, counselors carry out their work by mobilizing their personal repertoires, giving space to a unadjusted and with a high degree of discretion. To reach the results, the research was based on semi-structured interviews, which made possible the analysis of the social networks (ARS) of the counselors.
- ItemAcesso aberto (Open Access)Desenvolvimento de sensores baseados em nanotubos de carbono para a determinação de hormônios em água do mar(Universidade Federal de São Paulo, 2017-12-06) Okina, Renato Hisashi [UNIFESP]; Oliveira, Lucia Codognoto de [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)This work aimed de development of a glassy carbon sensor modified with multi-walled carbon nanotubes for determination of estrone, estriol and 17 α ethinylestradiol in seawater. Using the cyclic voltammetry technique it was possible to observe that the three hormones in study showed voltamograms typical of irreversible process in BR buffer 0.1 mol L-1, pH 7.0. The oxidation potential peak were 0.59 V, 0.57V e 0.56 V, for estrone, estriol and 17-α-ethinylestradiol, respectively. Also in cyclic voltammetry the study of pH of the medium and sweep velocity effect in the oxidation process for the three hormones were made, the results showed that the oxidation process is proton dependent and controlled by adsorption. The electrode modification method with successive addictions of carbon nanotubes showed efficiency for a better electrode surface cover, increasing the peak signal intensity of the three hormones and a bigger surface passivation resistance. The square wave voltyammetry parameters were optimized to the analytical method development, square wave amplitude, frequency and scan increment were optimized. After the parameters optimization the analytical curves were obtained for the three hormones, the results presented linearity in the concentration range 1.0x10-6 mol L-1 to 9.0x10-6 mol L-1 for estrone and estriol, and 1.0x10-6 mol L-1 to 4.5 x 10-6 mol L-1 for 17-α-ethinylestradiol. The recovery test for estrone in seawater sample showed the value of 74% for spiked sample at the concentration of 1.0 x 10-6, indicating the applicability of the developed methodology to quantify estrone directly in sea water.
- ItemAcesso aberto (Open Access)Determinação electromagnetically e estudo eletroquímico de bentazon e fenamifós utilizando eletrodos de diamante(Universidade Federal de São Paulo, 2017-03-17) Lima, Thays de Souza [UNIFESP]; Oliveira, Lucia Codognoto de [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)This study aimed to develop an electroanalytical methodology for determination of bentazon (BTZ) and fenamiphos (FNP) and also the electrochemical study these pesticides by exhaustive electrolysis. The BTZ presented a single oxidation peak in +1.01 V vs Ag / AgCl, and theFNP presented a single oxidation peak at + 1.18 V vs Ag / AgCl, both with irreversible process characteristics and controlled by diffusion. To develop the methodology for quantification of pesticides has used square-wave voltammetry (SWV). The analytical curves were obtained in concentration range of 9.90x10-6 mol L-1 to 9.09x10-5 mol L-1. For the BTZ the detection limits (LOD) and quantification (LOQ) values were 3.00x10-6 mol L-1 and 9.90x10-6 mol L-1, respectively. For the FNP, the LOD and LOQ values were 1.50x10-6 mol L-1 and 4.98x10-6 mol L-1, respectively. The performance of the developed method was evaluated by recovery studies in natural water samples and showed recovery percentages of 98.0% and 109.2% for BTZ and FNP, respectively. Was also developed a method for the simultaneous and selective determination of BTZ and FNP, the best results were obtained using square wave voltammetry and chemometric methods with of a 33 factorial full design. With selected parameters an analytical curve was constructed in the concentration range of 9.90x10-6 mol L-1 to 9.09x10-5 mol L-1 for the mixture of BTZ and FNP. For BTZ the values of LOD and LOQ were 3.80 x 10-7 mol L-1 and 1.27 x 10-6 mol L-1, respectively. For FNP the LOD and LOQ values were 3.00 x10-6 mol L-1 and 9.90x10-6 mol L-1, respectively. The study of destructive oxidation on the boron-doped diamond (BDD) electrodes for pesticides was realized using electrolysis at controlled potential. The electrolysis monitoring with the square wave voltammetry techniques, absorption spectrometry in the UV- Visible, total organic carbon (TOC) analyzes, and liquid chromatography with mass detector (LC-MS). An initial concentration of the pesticides decay of the electrolysis course. The percentages initial decreasing around 50.7 % for BTZ and 55.0 % for FNP.
- ItemAcesso aberto (Open Access)Determinação eletroanalítica do flavonoide glicosilado canferitrina em infusos de Bauhinia forficata utilizando eletrodos de diamante(Universidade Federal de São Paulo, 2021-12-02) Simião, Carolina Godinho [UNIFESP]; Oliveira, Lucia Codognoto de [UNIFESP]; Veiga, Thiago Andre Moura [UNIFESP]; http://lattes.cnpq.br/8190975614526360; http://lattes.cnpq.br/3696430664952773; http://lattes.cnpq.br/2707677614299443Neste trabalho foi estudado o comportamento eletroquímico do flavonoide glicosilado canferitrina e desenvolvida uma metodologia eletroanalítica para sua determinação em infusos de Bauhinia forficata, utilizando eletrodo de diamante dopado com boro (BDD). O estudo do comportamento eletroquímico do flavonoide em voltametria cíclica, apresentou dois picos de oxidação, um em 0,80 V vs Ag/AgCl, e outro em torno de 1,0 V vs Ag/AgCl, com característica de um processo irreversível. O estudo de influência do pH do meio mostrou ser o pH 7,0 o mais adequado para o trabalho, uma vez que apresentou maior intensidade de corrente de pico. A análise da variação da velocidade de varredura mostrou que a corrente de pico varia linearmente com a raiz quadrada da velocidade de varredura, indicando que o processo é controlado por difusão (pico 1 em 0,80 V). Os estudos com a voltametria de onda quadrada (técnica selecionada para o desenvolvimento da metodologia) tiveram como parâmetros otimizados f = 100 s-1, a=90 mV e ΔEs = 8 mV. Após a otimização dos parâmetros, foi construída a curva analítica para a canferitrina no intervalo de concentração de 3,4 x10-6 mol L-1 a 5,8 x10-5 mol L-1 com linearidade de 0,99, os limites de detecção e quantificação foram de 3,6 x10-6 mol L-1 e 1,2x10-5 mol L-1, respectivamente. Em paralelo foram realizados testes com eletrodo de grafite de lapiseira, onde o perfil voltamétrico da canferitrina foi similar ao observado com o eletrodo de BDD. Os limites de detecção e quantificação obtidos foram de 1,1x10-5 e 3,6x10-5, respectivamente. No entanto, o eletrodo de BDD foi o selecionado para a quantificação da canferitrina em Bauhinia forficata, pois apresentou melhor repetibilidade dos resultados. Foi encontrada uma concentração de 20 mg L-1 de canferitrina em 2 g de amostra de folhas secas de pata-de-vaca. Por fim foi realizado testes com outros dois flavonoides (crisina e apeginina) para comparar e propor um mecanismo de oxidação para a canferitrina. Os estudos eletroquímicos permitiram a determinação da canferitrina em infusos de Bauhinia forficata e também propor um mecanismo de oxidação para este composto sobre o eletrodo de BDD.
- ItemAcesso aberto (Open Access)Efeito da adição de líquidos iônicos em um copolímero elastomérico para preparação de eletrólitos sólidos para baterias de íon lítio(Universidade Federal de São Paulo, 2016-06-10) Silva Filho, Sinval Braz da [UNIFESP]; Camilo, Fernanda Ferraz [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)The search for solid electrolytes for electrochemical devices (batteries, full cells) is object of intense research due to their benefits in comparison with the liquids, mainly due to the processability aspects, handling and leak elimination. Although studies involving solid polymeric electrolytes have 0been reported, the research for materials that combine good mechanical strength, elasticity, chemical and thermal stabilities and ionic conductivity is still emerging. In this context, the first part of this dissertation focuses on the preparation and characterization of solid polymeric electrolytes constituted by a commercial elastomer known as PEBAX-2533, containing 80% of polyether blocks (PE) and 20% of polyamide blocks (PA), modified with three different ionic liquids (EMImTf2N, EMImFAP, EMImTCB). In the next step, a lithium salt, LiTf2N, was added to PEBAX-2533 films containing 10% of the cited ionic liquids in order to produce solid polymer electrolytes for lithium ion batteries. PEBAX-2533 films containing more than 25% of the ionic liquids exhibited droplets on the surface of the film, indicating phase segregation. This was not observed for films containing 10% of the salt and therefore only these electrolytes were used in the further studies. The results showed that using this percentage, the ions of the ionic liquids are accommodated in the voids present in the amorphous regions of the elastomer. These films showed ionic conductivity around 10-6 Scm-1 at 25 ° C. When the lithium salt, LiTf2N, was added to these electrolytes of PEBAX-2533 and ionic liquids, the conductivity decreased due to the formation of aggregates of lithium cation and the anions of the ionic liquids, which have a low mobility, and therefore do not contribute for ionic conductivity. In addition, it was verified that the lithium clusters and ?free? Li+ also occupy the empty spaces on the elastomer and free Li+ establishes permanent ion-dipole interactions with the PE blocks. The electrolyte comprised of PEBAX-2533, ionic liquids and LiTf2N showed thermal stability up to 200 °C. With the addition of poly (ethylene oxide) (PEO) to PEBAX-2533 films containing 10% of EMImTf2N and LiTf2N at 40 °C, it was obtained an electrolyte with conductivity of 9.2 x 10-5 Scm-1.
- ItemAcesso aberto (Open Access)Estudos voltamétrico e espectroscópico da interação dos íons metálicos cobre e chumbo com o pesticida paration metílico(Universidade Federal de São Paulo, 2017-12-07) Cardoso, Daisy Alves [UNIFESP]; Oliveira, Lucia Codognoto de [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)The objective of this work was to analyze the interaction between the pesticide methyl parathion molecule and the copper and lead metal ions that may be present in soil and water. Initially, electrochemical studies were performed using cyclic voltammetry with a carbon electrode reused from the zinc cell for characterization of the species. Methyl parathion (PM) in 0.4 mol L-1 BR buffer had a cathode peak at approximately -0.57 V, corresponding to the reduction of the nitro group to hydroxylamine. This process was followed by a couple of peaks at -0.02 V and -0.04 V, corresponding to reversible oxidation of the hydroxylamine. In buffer BR 0.4 mol L-1 the copper metal ion showed a cathode peak at -0.09 V and an anode peak at -0.14 V corresponding to the reduction / oxidation of the copper ion and the lead ion in 0.1 mol L-1 KNO3 had a cathode peak at -0.65 V and an anode peak at - 0.44 V corresponding to the reduction / oxidation of the lead ion. Both presented a process controlled by the diffusion of the species on the surface of the electrode. The evaluation of the formation of the complex was performed by cyclic voltammetry and anodic redissolution voltammetry by differential pulse at pH 6.0. The studies of the evaluation of the interaction between PM and Cu(II) did not present satisfactory evidence on the formation of a new species in solution. A new peak at -0.60 V corresponding to the formation of a new species in solution with 1:2 stoichiometry (Pb: PM) was observed for the PM-Pb(II) studies. The stability constant for this new species was calculated (log K'=7.6) from the Langmuir linearization method. Comparative studies using UV-Vis indicated the formation of a new species in solution with increased absorbance of the band of the PM ligand in alkaline medium when in the presence of lead. In the interaction between the PM and Cu (II) by differential the changes in the peak potentials appear in close potential interval hindering an adequate definition of the formation of a new species in solution, already in the interaction between the PM and the Pb (II) was evidenced the formation of a new peak. The studies by voltammetry presented more satisfactory results compared to the technique by UV-Vis.
- ItemAcesso aberto (Open Access)Síntese e caracterização de complexos de Cu2+, Pd2+ e Ru2+ com fenantrolinas modificadas(Universidade Federal de São Paulo, 2021-12-16) Barbosa, Renan Santini [UNIFESP]; Bagatin, Izilda Aparecida [UNIFESP]; http://lattes.cnpq.br/1306989214227206; http://lattes.cnpq.br/5257210429363735O trabalho se baseou na modificação do ligante de partida 1,10-fenantrolina uma vez que é um ligante diimínicos por conta das ligações C=N existentes, sendo estas o sítio coordenante que foram abordados para a coordenação dos metais. As modificações feitas neste trabalho foram para criar moléculas com potenciais propriedades luminescentes e eletroquímicas bem como adicionar novos sítios a partir da funcionalização das posições 5 e 6 da fenantrolina. Essas funcionalizações tiveram grupos adicionados à molécula inicial, desde carbonilas, representados pelo ligante 5,6-diona-1,10-fenantrolina, o qual apresenta sinais de RMN de 1H em (ppm, 300 MHz, CDCl3) 9,14 ppm (dd, 2H, 4J = 1,63Hz; 3J = 4,64Hz), 8,52 ppm (dd, 2H,4J = 1,87Hz; 3J = 7,81Hz) e 7,6 ppm (dd, 2H,3J = 7,9Hz) e sinais de RMN de 1H em (ppm, 300 MHz, dmso-d6) 9,00 ppm (dd, 2H, 4J = 1,83Hz; 3J = 4,58Hz), 8,40 ppm (dd, 2H,4J = 1,61Hz; 3J = 7,7Hz) e 7,69 ppm (dd, 2H,3J = 7,8Hz, possuindo uma característica quasi-reversível na análise de voltametria cíclica; até grupos diaminas, sendo estes com uma característica irreversível em sua análise voltamétrica, mostrando assim que diferentes modificações do ligante base podem nos mostrar resultados totalmente diferentes de suas propriedades. As caracterizações no FTIR dos ligantes também foram feitas e pode-se observar para o ligante 5,6-diona-1,10-fenantrolina as seguintes frequências: 1413 cm-1 (C-N), 1555 cm-1 (CC), 1580 cm-1 (CN), 1686 cm-1 (CO) e 3065 cm-1 (ar C-H). Através do comportamento espectroeletroquímico e com o uso da equação de Nernst foi possível determinar quantos elétrons estavam envolvidos em cada processo e, pela análise simultânea do espectro de UV-Vis, também inferir onde ocorre a oxidação ou redução na molécula.