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Search Results: 1 - 10 of 382043 matches for " Adalgisa R. de; "
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Espectroscopia de impedancia eletroquímica aplicada ao estudo das rea??es heterogêneas em anodos dimensionalmente estáveis
Carvalho, Liliane A. de;Andrade, Adalgisa R. de;Bueno, Paulo R.;
Química Nova , 2006, DOI: 10.1590/S0100-40422006000400029
Abstract: this paper discusses different aspects related to the application of electrochemical impedance spectroscopy (eis) in the study of heterogeneous electrochemical reactions occurring on dimensionally stable anodes (dsa?). the most relevant aspects of the semiconductor/electrolyte interface, the application of the eis classical equivalent circuit approach and the ac porous model in dsa are presented. the paper shows that dsa type electrodes can be consistently investigated by using the ac porous model and an analysis is presented showing the advantage of applying this kind of approach to study heterogeneous reactions on dsa electrodes. furthermore, some preliminary results on ti/ru0,3ti(0,7-x)snx o2 based electrodes are presented to exemplify the use of the ac porous model analysis.
Development of plurimetallic electrocatalysts prepared by decomposition of polymeric precursors for EtOH/O2 fuel cell
Palma, Lívia M.;Almeida, Thiago S.;Andrade, Adalgisa R. de;
Journal of the Brazilian Chemical Society , 2012, DOI: 10.1590/S0103-50532012000300024
Abstract: this work aimed to develop plurimetallic electrocatalysts composed of pt, ru, ni, and sn supported on c by decomposition of polymeric precursors (dpp), at a constant metal:carbon ratio of 40:60 wt.%, for application in direct ethanol fuel cell (defc). the obtained nanoparticles were physico-chemically characterized by x-ray diffraction (xrd) and energy dispersive x-ray spectroscopy (edx). xrd results revealed a face-centered cubic crystalline pt with evidence that ni, ru, and sn atoms were incorporated into the pt structure. electrochemical characterization of the nanoparticles was accomplished by cyclic voltammetry (cv) and chronoamperometry (ca) in slightly acidic medium (0.05 mol l-1 h2so4), in the absence and presence of ethanol. addition of sn to ptruni/c catalysts significantly shifted the ethanol and co onset potentials toward lower values, thus increasing the catalytic activity, especially for the quaternary composition pt64sn15ru13ni8/c. electrolysis of ethanol solutions at 0.4 v vs. rhe allowed determination of acetaldehyde and acetic acid as the main reaction products. the presence of ru in alloys promoted formation of acetic acid as the main product of ethanol oxidation. the pt64sn15ru13ni8/c catalyst displayed the best performance for defc.
Electrochemical degradation of reactive dyes at different DSA? compositions
Silva, Rodrigo G. da;Aquino Neto, Sydney;Andrade, Adalgisa R. de;
Journal of the Brazilian Chemical Society , 2011, DOI: 10.1590/S0103-50532011000100017
Abstract: this paper investigates the electrochemical oxidation of the reactive dyes reactive blue 4 (rb-4) and reactive orange 16 (ro-16) on ruo2 dimensionally stable anode (dsa?) electrodes. electrolysis was achieved under galvanostatic control as a function of supporting electrolyte and electrode composition. the electrolyses, performed in either the presence or absence of nacl, were able to promote efficient color removal; moreover, at low chloride concentration (0.01 mol l-1), total color removal was obtained after just 10 min of electrolysis, and a significant increase in total dye combustion was achieved for all the studied anodes in chloride medium (reaching ca. 80% - chemical oxygen demand - cod removal). no significant enhancement in dye color removal or mineralization was observed upon increasing chloride concentration. the influence of oxide composition on dye elimination seems to be significant in both media (with or without chloride), being ti/ru0.30ti0.70o2, the most active material for organic compound oxidation. the oxygen evolution reaction (oer) was shown to be a limiting reaction in both supporting electrolytes; i.e., nacl and na2so4, and its competition with organic compound oxidation remained an obstacle. the adsorbable organo halogens (aox) formation study revealed that there is slight consumption of the undesirable species formed within the first minutes of the electrolysis, being ti/(ruo2)0.70(ta2o5) 0.30 the most environmentally friendly composition. both anode composition and chloride concentration affect the formation of these undesirable compounds.
Investigation of the influence of the anode composition of DSA-type electrodes on the electrocatalytic oxidation of phenol in neutral medium
Alves, Paula D. P.;Spagnol, Magali;Tremiliosi-Filho, Germano;Andrade, Adalgisa R. de;
Journal of the Brazilian Chemical Society , 2004, DOI: 10.1590/S0103-50532004000500003
Abstract: in this paper, phenol oxidation was used as a probe reaction to carry out a systematic investigation of the electrocatalytic activity of dsa-type anodes with nominal compositions equal to ti/ru0.3m0.7o2 and ti/ir0.7m0.3o2 (m = ti and sn) in 1.0 mol l-1 naclo4. under cv conditions, phenol oxidation favors polymerization that completely blocks the electrode activity after few cycles independently of the anode material. the following intrinsic catalytic efficiency was observed under cv conditions: ti/ru0.3ti0.7o2 >> ti/ru0.3sn0.7o2 > ti/ir0.7ti0.3o2 > ti/ir0.7sn0.3o2. however, electrolysis experiments (i = 40/80 ma cm-2) run in laboratory-scale showed that the proper choice of anode material can improve the yields of co2 as final product. hplc and toc techniques were used in order to quantify the electrode efficiency. it is important to emphasize that all anodes presented good ability to oxidize the phenolic portion, and a toc reduction as high as 80% was observed for the ti/ru0.3ti0.7o2 electrode. benzoquinone formed in the beginning of the electrolysis is continuously oxidized as the reaction proceeds. malic, tartaric and malonic acids were also identified as other by-products of phenol oxidation.
Effect of solvent on the preparation and characterization of DSA?-type anodes containing RuO2-TiO2-SnO2
Coteiro, Roberta D.;Teruel, Fernando S.;Ribeiro, Josimar;Andrade, Adalgisa R. de;
Journal of the Brazilian Chemical Society , 2006, DOI: 10.1590/S0103-50532006000400020
Abstract: anodes containing ruthenium, titanium, and tin oxides supported on metallic ti were prepared by thermal decomposition of precursor salts in order to investigate the effect that changing the solvent (from hcl/h2o to isopropanol) would have on the real composition of the mixed oxide electrodes. the precursor solutions and their mixtures were analyzed by uv-vis spectrophotometry. coatings morphology and composition were analyzed by scanning electronic microscopy (sem) and energy dispersive x-ray (edx). determination of the electrochemically active area and electrode stability was performed by voltammetric characterization (1.0 mol l-1 hclo4) and service life (sl) tests, respectively. electrodes prepared from isopropanol showed excellent agreement between the nominal and experimental composition and they presented higher electrochemically active area and better stability when compared to those prepared in the presence of hcl. preparation of the precursor mixture in isopropanol increases ruo2-tio2-sno2 electrodes service life.
Eletroxida??o do etanol em eletrodos de Ti/IrO2
Fidelis, Carlos H.V.;Donate, Paulo M.;Andrade, Adalgisa R. de;
Química Nova , 2001, DOI: 10.1590/S0100-40422001000100009
Abstract: it has been carried out an investigation of ethanol electro-oxidation on ti/iro2 electrodes. the experimental results show a high selectivity towards acetaldehyde formation thus, offering potential advantages in cost and availability of raw material. it has been observed that the electrode is partially blocked by a film formed after the oxidation of the starting material which can be removed by pulse technique between rdo and rdh onset. the mechanism and the selectivity of the product formed is presented.
Eletroxida o do etanol em eletrodos de Ti/IrO2
Fidelis Carlos H.V.,Donate Paulo M.,Andrade Adalgisa R. de
Química Nova , 2001,
Abstract: It has been carried out an investigation of ethanol electro-oxidation on Ti/IrO2 electrodes. The experimental results show a high selectivity towards acetaldehyde formation thus, offering potential advantages in cost and availability of raw material. It has been observed that the electrode is partially blocked by a film formed after the oxidation of the starting material which can be removed by pulse technique between RDO and RDH onset. The mechanism and the selectivity of the product formed is presented.
The oxidation of formaldehyde on high overvoltage DSA type electrodes
Motheo, Artur J.;Gonzalez, Ernesto R.;Tremiliosi-Filho, Germano;Olivi, Paulo;Andrade, Adalgisa R. de;Kokoh, Boniface;Léger, Jean-Michel;Belgsir, El Mustapha;Lamy, Claude;
Journal of the Brazilian Chemical Society , 2000, DOI: 10.1590/S0103-50532000000100004
Abstract: the electrochemical oxidation of formaldehyde is studied on dimensionally stable anodes prepared by thermal decomposition of precursors (the corresponding chlorides). the working electrodes used were: ti/ir0.3ti0.7o2, ti/ru0.3ti0.7o2 and ti/ir0.2ru0.2ti0.6o2. the electrolyses were performed galvanostatically in a filter press cell with 0.5 mol l-1 h2so4 solutions with initial formaldehyde concentration equal to 100 mmol l-1. the concentration of formaldehyde decreases fast with the electrolysis time, with the ternary anode (ir + ru + ti) presenting the best performance for this step. the anode containing only ir, despite presenting the higher superficial charge, is the one with the lowest electrocatalytic activity. for the formic acid oxidation step, the presence of iridium in the anode composition does not promote the process, the anode containing only ruthenium being the most effective for this step.
Capacita??o de agentes comunitários de saúde: experiência de ensino e prática com alunos de Enfermagem
Cardoso, Fátima Aparecida;Cordeiro, Vitória Régia de Negreiros;Lima, Daniele Barreto de;Melo, Bárbara de Caldas;Menezes, Raquel Nobre Barreto de;Moulaz, Ana Luiza Silva de;Sá, Gabrielle Boff de;Souza, Adalgisa Vania Fernandes de;
Revista Brasileira de Enfermagem , 2011, DOI: 10.1590/S0034-71672011000500026
Abstract: this paper aims to report an experience carried out by nursing students from the undergraduate school of health sciences, federal district, during their first year of study. the objective was to implement a training for 22 community health workers, in order to clarify them about their role in community work and to elevate their self esteem. a methodology of problematization and various educational techniques were used. the themes were: duties and rights, responsibilities, communication, ethics, team work, children′s health, care for the elderly and domestic violence. the result was considered positive for both sides: the community workers acquired new knowledge/capabilities and better feeling of self worth and the students were able to integrate theory and practice and become active participants in the learning process.
Atendimento de saúde para pessoas idosas vítimas de violência no município do Rio de Janeiro
Ribeiro,Adalgisa Peixoto; Souza,Edinilsa Ramos de; Valadares,Fabiana Castelo;
Ciência & Saúde Coletiva , 2012, DOI: 10.1590/S1413-81232012000500011
Abstract: the scope of this article is to chart, define and qualify the healthcare provided by the brazilian unified health system (sus) and outsourced services to elderly people in situations of violence in rio de janeiro, based on major policies aimed at this group. this is an exploratory study that triangulated quantitative and qualitative methods. the introduction and implementation of policies is differentiated between the units: they are more thoroughly implemented at the pre-hospital and hospital level and less at rehabilitation level. the challenges involve the professional's ability to identify, attend and report cases of violence; to include the topic in care of the elderly; to give visibility to the specific requirements for elderly women; to instruct and orient families about care, creating strategies to redeem the bonds of affection; to monitor the changes that lead to functional disability and enhance the quality of life of the elderly.
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