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Search Results: 1 - 10 of 330645 matches for " Rold?o R. U.; "
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Pervapora??o: uma técnica de separa??o contínua n?o-cromatográfica
Mattos, Ivanildo Luiz de;Queiroz, Roldo R. U.;
Química Nova , 1998, DOI: 10.1590/S0100-40421998000200016
Abstract: a brief discussion of the non-chromatographic continuous separation techniques is presented emphasizing the pervaporation process. it makes interesting choices for implementing various preliminary operations of the analytical process in order to accommodate the raw sample to the measuring instrument. discussions include the perceived advantages and disadvantages, the underlying principles of pervaporation process, the flexible module and fields of application.
Pervapora o: uma técnica de separa o contínua n o-cromatográfica
Mattos Ivanildo Luiz de,Queiroz Roldo R. U.
Química Nova , 1998,
Abstract: A brief discussion of the non-chromatographic continuous separation techniques is presented emphasizing the pervaporation process. It makes interesting choices for implementing various preliminary operations of the analytical process in order to accommodate the raw sample to the measuring instrument. Discussions include the perceived advantages and disadvantages, the underlying principles of pervaporation process, the flexible module and fields of application.
Spectrophotometric Determination of Manganese in Steels by On-Line Electrochemical Oxidation
Saint?Pierre, Tatiana. D.;Queiróz, Roldo R.U. de;Souza, Ivan G. de;Gomes Neto, José A.;
Journal of the Brazilian Chemical Society , 1998, DOI: 10.1590/S0103-50531998000200005
Abstract: the aim of this work is to propose a flow spectrophotometric procedure for manganese determination in steel based on electrochemical oxidation of mn(ii) to mn(vii) at a pt electrode surface by means of the catalytic effect of ag(i). the on-line oxidation step was obtained by injecting sample and electrolyte solution directly into an electrolytic cell. after electrolysis, the injectate was homogenized by bubbling air. the permanganate ions produced were passed through the spectrophotometer where absorbance was monitored at 545 nm. effects of direct current, silver concentration, timing, flow rates, concentration and composition of support electrolyte were investigated. direct current and silver content manifested themselves as the most relevant parameters. for determination of manganese in the 5.00 - 150 mg l-1 range (r = 0,9998) and 60 s electrolysis time, the sample throughput was 20 h-1. accuracy was assessed by analyzing ten steel standard reference materials. results are precise (r.s.d. < 3%) and in agreement with certified values of reference materials and with standard methods at 95% confidence level.
High current ¢ € “density anodic electrodissolution in flow ¢ € “injection systems for the determination of aluminium, copper and zinc in non ¢ € “ferroalloys by flame atomic absorption spectrometry
José Anchieta Gomes Neto,Ivan Gon?alves Souza,Roldo R. U. de Queiróz,César Augusto Giacomozzi
Journal of Analytical Methods in Chemistry , 1999, DOI: 10.1155/s1463924699000036
Abstract: An automatic procedure with a high current-density anodic electrodissolution unit (HDAE) is proposed for the determination of aluminium, copper and zinc in non-ferroalloys by flame atomic absorption spectrometry, based on the direct solid analysis. It consists of solenoid valve-based commutation in a flow-injection system for on-line sample electro-dissolution and calibration with one multi-element standard, an electrolytic cell equipped with two electrodes (a silver needle acts as cathode, and sample as anode), and an intelligent unit. The latter is assembled in a PC-compatible microcomputer for instrument control, and for data acquisition and processing. General management of the process is achieved by use of software written in Pascal. Electrolyte compositions, flow rates, commutation times, applied current and electrolysis time were investigated. A 0.5 mol l-1 HN03 solution was elected as electrolyte and 300 A/cm2 as the continuous current pulse.
Sistema automático para análise direta de ligas metálicas por eletrodissolu??o anódica e espectrometria de absor??o at?mica
Silva, José Bento B.;Giacomelli, Maria B. O.;Lehmkuhl, Arilson;Curtius, Adilson J.;Queiróz, Roldo R. U.;Souza, Ivan G. de;
Química Nova , 1999, DOI: 10.1590/S0100-40421999000100004
Abstract: an automatic system for the direct determination of lead and tin by atomic absorption spectrometry is described. the on-line treatment of the metallic samples was obtained by anodic electrodissolution in a flow injection system. lead was determined by flame atomic absorption spectrometry (faas) and tin by graphite furnace atomic absorption spectrometry (gfaas). a computer program managed the current source and the solenoid valves that direct the fluids. good linear correlations between absorbance and current intensity for lead and tin were observed. results were in agreement with the certified values. precision was always better than 5%. the recommended procedure allows the direct determination of 60 or 30 elements/h using faas or gfaas, respectively.
Fun??o docente: natureza e constru??o do conhecimento profissional
Roldo, Maria do Céu;
Revista Brasileira de Educa??o , 2007, DOI: 10.1590/S1413-24782007000100008
Abstract: in this paper, the specificity of teaching as a social function is under analysis. the author examines the evolution of the very concept of teaching and the plurality of possible meanings that have been associated with it, as well as their implications in teachers professional development as a group throughout its historic evolution.the nature of the specific knowledge required to teach will be also discussed, supported by existing theorizations on teaching professional knowledge. a set of distinctive descriptors of such knowledge is proposed and discussed. the whole perspective of this discussion is based on the reinforcement and valuing of the dimension of analysis and theorization of teaching activity by teachers themselves, assumed as enhancing the development of the social recognition of teachers as professionals.
A Forma o de Professores como Objecto de Pesquisa - contributos para a constru o do campo de estudo a partir de pesquisas portuguesas. Teacher training as a subject of research – contributions for teacher development
Roldo, Maria do Céu
Revista Eletr?nica de Educa??o , 2007,
Abstract: O objectivo desta comunica o constitui-se como um contributo para a clarifica o e defini o do campo de pesquisa próprio que a forma o de professores deverá configurar, partindo de duas linhas de análise:- a conceptualiza o do campo, através da articula o de conceitos-chave que o delimitam no plano teórico;- a análise de investiga o produzida em Portugal nas últimas décadas conotada com o campo da forma o, e identifica o de áreas nucleares e áreas adjacentes que nela se têm enquadrado.Estas duas linhas - conceptual e documental - ser o analisadas numa perspectiva de teoria situada, na medida em que se procura interpretar quer as zonas de convergência, quer as zonas de difus o, evidenciadas na investiga o existente no campo da forma o em Portugal, por um lado (1) à luz das condicionantes históricas, ideológicas e contextuais do sistema educativo português e (2) por outro, em rela o com as representa es sociais dominantes sobre a profiss o docente e consequente concep o da forma o a ela associada. Convocam-se para o efeito revis es de investiga o realizadas em Portugal na última década que apontam, entre outros aspectos, para uma considerável dispers o conceptual do campo; para a sua segmenta o em tipologias relacionadas com a temporalidade da forma o; que ilustram a sua dependência face a dimens es normativas acerca dos sistemas de forma o; e que evidenciam a escassez do espa o e valor atribuído à forma o no desempenho profissional docente.The aim of this work is to clarify and define the research area which teacher training should follow. There are two areas of research:- Conceptualizing the area, using key concepts which define the theoretical plan;- Analysing the investigation produced in Portugal over the last decades suggesting the training area and identifying central areas, as well as adjacent areas in which it could fit. These two areas of research – conceptual and documental – will be analysed in a perspective of theory in so far as whether convergence zones or diffusion zones are interpreted, based on evidence in the existing investigation in the field of training in Portugal. On one hand (1), in light of ideological and historical conditions and contextualized in the Portuguese Education system and (2) on the other hand in relation to the social dominating representations concerning the teaching profession and consequent concept of training which is associated to it. Over the last decade in Portugal, investigations carried out have shown, among other aspects, a considerable conceptual dispersion; its segmentation in typologi
Fun o docente: natureza e constru o do conhecimento profissional
Maria do Céu Roldo
Revista Brasileira de Educa??o , 2007,
Abstract: Función docente: naturaleza y construcción del conocimiento profesional Se analiza la especificidad de la función de ense ar en cuanto caracterizadora de la actividad del profesor y se examina la evolución y la pluralidad de sentidos asociados al concepto de ense ar y sus implicaciones en el desenvolvimiento profesional de los docentes a lo largo de la evolución histórica de la actividad. En un segundo momento, se analiza también la naturaleza del conocimiento específico necesario al desempe o de la función de ense ar, procurando dar cuenta de las teorizaciones que existen a respecto de ese conocimiento, proponiendo y discutiendo un conjunto de caracterizadores distintivos de ese saber que la autora designa como generadores de especificidad. La propuesta del trabajo se sitúa en el cuadro de una valorización de la dimensión analítica y teorizadora de la acción de ense ar por parte del profesor, en el sentido de desenvolvimientos futuros de la docencia que puedan reforzar la afirmación social de la profesionalidad de los docentes.
A FUN O CURRICULAR DA ESCOLA E O PAPEL DOS PROFESSORES: POLíTICAS, DISCURSO E PRáTICAS DE CONTEXTUALIZA O E DIFERENCIA O CURRICULAR
Maria do Céu Roldo
Nuances : Estudos sobre Educa??o , 2011,
Abstract: As políticas curriculares desde o último quartel do século XX têm vindo a acentuar a reorienta o dos loci de decis o curricular em resultado da complexidade dos contextos e popula es que a universalidade da escolariza o trouxe para o interior da escola nas sociedades democráticas, acentuando as press es quer no sentido da contextualiza o e diferencia o quer no refor o de um núcleo curricular comum corporizado nos chamados currículos nacionais. Nesta comunica o, procura-se examinar este processo a dois níveis: no plano macro-político, pela interpreta o teórica dos diferentes formatos adoptados por países com histórias diferentes na articula o destes dois planos de decis o curricular – o Estado e a escola – e respectivas implica es para as práticas curriculares reais; no plano praxiológico, com base em revis es de investiga o portuguesa sobre as práticas de ensino no interior desta muta o política, assinalam-se as contradi es discurso/ac o docente e políticas das escolas, bem como as quest es associadas às culturas profissionais e organizacionais que podem explicar parte das contradi es identificadas. Discutem-se ainda algumas implica es e quest es resultantes da análise desenvolvida.
PROFISSIONALIDADE DOCENTE EM ANáLISE - ESPECIFICIDADES DOS ENSINOS SUPERIOR E N O SUPERIOR
Maria do Céu Roldo
Nuances : Estudos sobre Educa??o , 2012,
Abstract: Neste artigo s o examinados os descritores do conceito de profissionalidade e as suas particularidades quando aplicados à actividade docente. A análise desenvolvida fundamenta-se nos caracterizadores de profissionalidade mais consensuais na literatura do campo teórico da sociologia das profiss es. Os factores histórico-sociais que subjazem à representa o da actividade docente, dentro e fora da comunidade dos seus praticantes, s o confrontados com as práticas de ensino no que se refere a poder, saber próprio, clareza da fun o social desempenhada e sentido de comunidade profissional. Na análise desenvolvida, examinam-se e procuram explicar-se as diferen as observáveis, no quadro de representa o social da docência, entre docentes de ensino superior e n o superior.
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