As abordagens à aprendizagem de estudantes da Universidade do Algarve

No presente capítulo abordamos a forma como alguns estudantes do Ensino Superior aprendem, partindo das estratégias que operacionalizam as suas motivações para o estudo e para a aprendizagem. Ao concebermos o estudante do Ensino Superior como pertencente a um grupo específico em desenvolvimento, importa, primeiro que tudo, compreender quem é esse estudante, para depois partirmos para a análise das diferentes abordagens à aprendizagem utilizadas pelos estudantes universitários. Neste sentido, começamos com algumas reflexões sobre o conceito de jovem adulto, para depois analisarmos, com base no modelo de avaliação da aprendizagem de John Biggs, as diferentes abordagens à aprendizagem utilizadas por um grupo de estudantes da Universidade do Algarve.

A resolução de problemas, o raciocínio e a comunicação matemática no 1º ciclo do ensino básico

A comunicação aborda o caso dum professor do 1.º ciclo do ensino básico (Francisco) inserido numa investigação mais ampla em que se pretendeu estudar as concepções e práticas dos professores do 1.º ciclo do ensino básico relativamente à resolução de problemas, raciocínio e comunicação matemática. O estudo segue uma metodologia de investigação de natureza interpretativa e abordagem qualitativa na modalidade de estudo de caso. Francisco apresenta algumas preocupações de carácter metodológico relativamente ao ensino e aprendizagem da Matemática defendendo a importância do papel do professor em assegurar o acompanhamento do trabalho dos alunos de forma a compreender o problema. As situações propostas pelo Francisco na sala de aula assumem características problemáticas embora revele sentir algumas dificuldades na sua exploração. Para o Francisco, raciocínio e técnicas, estão a par, não privilegia mais uma do que outra. Reconhece que não tem insistido para que os seus alunos falem e escrevam sobre Matemática embora se preocupe em desenvolver uma boa comunicação na sala de aula.

A criação literária e o Algarve, no Algarve ou do Algarve? Reflexões sobre literatura regional(ista)

Em resultado da conversa informal que foi o Quintas de Cultura – Criar Letras, foi-me sugerido que desenvolvesse algumas reflexões das quais resultou este trabalho, que intitulei, inicialmente, «A criação literária e o Algarve». Porém, várias questões se foram levantando e, no final, o título alongou-se para «no Algarve ou do Algarve», em forma de interrogação. O verbete «Algarve», da autoria de David Mourão-Ferreira,n’ O Dicionário de Literatura, serviu de ponto de partida para ajudar a equacionar a problemática: «Para uma estimativa geográfica da literatura portuguesa foi assaz tardia, embora muito característica, a contribuição do Algarve, quer como berço de grandes escritores, quer como tema, tópico ou motivo de obras significativas» (Coelho, 1987, p. 37).

Enterprise architecture model: an approach proposition. A case study of information systems in the hospitality industry

This paper discusses the role of enterprise architecture representation, in the context of ERP (Enterprise Resource Planning) information systems, as an instrument for an organization to reflect on itself and develop its business strategies and respective alignment with Information Systems. The paper proposes a representation model of enterprise architecture, as a tool for recommending good practices, and it emerges from a case study undertaken in the context of and investigation on advantages and limitations of ERP systems in the hospitality industry. The proposed approach is also inspired on other academic or market propositions suitable for the objectives of the investigation. It consists on a set of items representing the steps that must be taken by top managers and IS managers.

Comparison of AGNES (absence of gradients and Nernstian equilibrium stripping) and SSCP (scanned stripping chronopotentiometry) for trace metal speciation analysis

The free metal ion concentrations obtained by SSCP (stripping chronopotentiometry at scanned deposition potential) and by AGNES (absence of gradients and Nernstian equilibrium stripping) techniques have been compared and the usefulness of the combination of both techniques in the same electrochemical cell for trace metal speciation analysis is assessed. The free metal ion concentrations and the stability constants obtained for lead(II) and cadmium(II) complexation by pyridinedicarboxylic acid, by 40 nm radius carboxylated latex nanospheres and by a humic acid extracted from an ombrotrophic peat bog were determined. Whenever possible, the free metal ion concentrations were compared with the theoretical predictions of the code MEDUSA and with the free metal ion concentrations estimated from ion selective electrodes (ISE). SSCP values were in agreement with the ones obtained by AGNES, and both of them agreed reasonably with the ISE values and the theoretical predictions. For the lead(II)-humic acid, it was not possible to obtain the stability constants by SSCP due to the heterogeneity effect. However, using AGNES it is possible to obtain, for these heterogeneous systems, the free bulk metal concentration, which allows us to retrieve the stability constant at bulk conditions.

Application of permeation liquid membrane and scanned stripping chronopotentiometry to metal speciation analysis of colloidal complexes

The potential of permeation liquid membrane (PLM) to obtain dynamic metal speciation information for colloidal complexes is evaluated by measurements of lead(II) and copper(II) complexation by carboxyl modified latex nanospheres of different radii (15, 35, 40 and 65 nm). The results are compared with those obtained by a well characterized technique: stripping chronopotentiometry at scanned deposition potential (SSCP). Under the PLM conditions employed, and for large particles or macromolecular ligands, membrane diffusion is the rate-limiting step. That is, the flux is proportional to the free metal ion concentration with only a small contribution from labile complexes. In the absence of ligand aggregation in the PLM channels, good agreement was obtained between the stability constants determined by PLM and SSCP for both metals.

Metal speciation dynamics in colloidal ligand dispersions. Part 3: Lability features of steady-state systems

A lability criterion is developed for dynamic metal binding by colloidal ligands with convective diffusion as the dominant mode of mass transport. Scanned stripping chronopotentiometric measurements of Pb(II) and Cd(II) binding by carboxylated latex core-shell particles were in good agreement with the predicted values. The dynamic features of metal ion binding by these particles illustrate that the conventional approach of assuming a smeared-out homogeneous ligand distribution overestimates the lability of a colloidal ligand system. Due to the nature of the spatial distribution of the binding sites, the change in lability of a metal species with changing ligand concentration depends on whether the ligand concentration is varied via manipulation of the pH (degree of protonation) or via the particle concentration. In the former case the local ligand density varies, whereas in the latter case it is constant. This feature provides a useful diagnostic tool for the presence of geometrically constrained binding sites.

Metal speciation dynamics in colloidal ligand dispersions. Part 2: electrochemical lability

We investigate the dynamic nature of metal speciation in colloidal dispersions using a recently proposed theory [J.P. Pinheiro, M. Minor, H.P. Van Leeuwen, Langmuir, 21 (2005) 8635] for complexing ligands that are situated on the surface of the particles. The new approach effectively modifies the finite rates of association/dissociation of the colloidal metal complexes, thus invoking consideration of the two basic dynamic criteria: the association/dissociation kinetics of the volume complexation reaction (the ‘‘dynamic’’ criterion), and the interfacial flux of free metal to a macroscopic surface due to dissociation of complex species (the ‘‘lability’’ criterion). We demonstrate that the conventional approach for homogeneous systems that assume a smeared-out ligand distribution, overestimates both the dynamics and the lability of metal complexes when applied to colloidal ligands. It is also shown that the increase of lability with increasing particle radius, as expected for a homogeneous solution, is moderated for spherical microelectrodes and practically eliminated for planar electrodes.

Measurement of Donnan potentials in gels by in situ microelectrode voltammetry

This work describes the electrochemical methodology for the determination of the Donnan potential from diffusion-limited steady-state voltammograms of acrylamide gels. The technique is based upon the measurement of gel–sol systems that have reached Donnan equilibrium and contain Cd2+ as a probe ion. Au-amalgam microelectrodes are used to measure the Cd concentration in the gel phase relative to the solution phase, thus permitting comparison of the Cd voltammograms obtained in both phases. This approach yields two independent measures of the Donnan potential resulting from (i) the potential shift relative to the reference electrode, and (ii) the enhancement of the Cd2+ wave. Two suites of acrylamide gels containing 0.2% and 0.5% Na-acrylate were studied as a function of ionic strength by varying [NaNO3] and maintaining a constant concentration of the electroactive probe ion, [Cd2+] = 1 · 10 5 mol/L in the equilibrating solutions. Independent model predictions of the Donnan potential as a function of ionic strength that consider the effects of differential swelling on the charge density, the influence of a mixed electrolyte on the potential developed in the gel at the limit of low ionic strength and the effects of incomplete dissociation of the carboxylic functional groups were in agreement with the Donnan potentials independently measured by the twofold steady-state voltammetric approach.

Electrochemical methodology to study labile trace metal/natural organic matter complexation at low concentration levels in natural waters

A new electrochemical methodology to study labile trace metal/natural organic matter complexation at low concentration levels in natural waters is presented. This methodology consists of three steps: (i) an estimation of the complex diffusion coefficient (DML), (ii) determination at low pH of the total metal concentration initially present in the sample, (iii) a metal titration at the desired pH. The free and bound metal concentrations are determined for each point of the titration and modeled with the non-ideal competitive adsorption (NICA-Donnan) model in order to obtain the binding parameters. In this methodology, it is recommended to determine the hydrodynamic transport parameter, α, for each set of hydrodynamic conditions used in the voltammetric measurements. The methodology was tested using two fractions of natural organic matter (NOM) isolated from the Loire river, namely the hydrophobic organic matter (HPO) and the transphilic organic matter (TPI), and a well characterized fulvic acid (Laurentian fulvic acid, LFA). The complex diffusion coefficients obtained at pH 5 were 0.4 ± 0.2 for Pb and Cu/HPO, 1.8 ± 0.2 for Pb/TPI and (0.612 ± 0.009) × 10−10 m2 s−1 for Pb/LFA. NICA-Donnan parameters for lead binding were obtained for the HPO and TPI fractions. The new lead/LFA results were successfully predicted using parameters derived in our previous work.

Determining carrier mobility with a metal–insulator–semiconductor structure

The electron and hole mobility of nickel-bis(dithiolene) (NiDT) are determined in a metal– insulator–semiconductor (MIS)structure using admittance spectroscopy. The relaxation times found in the admittance spectra are attributed to the diffusion time of carriers to reach the insulator interface and via Einstein’s relation this yields the mobility values. In this way, an electron mobility of 1:9 104 cm2=Vs and a hole mobility of 3:9 106 cm2=Vs were found. It is argued that the low mobility is caused by an amphoteric mid-gap trap level. The activation energy for electrons and holes from these traps is found to be 0.46 eV and 0.40 eV, respectively.

Interaction between water and nutrient deficiencies in helianthus annuus

The physiological response of plants to water deficits are known to vary according to the conditions of application of drought stress and the rate of development of leaf water deficits. At the whole plant level the effect of the water shess is usually perceived as a decrease in photosynthesis and growth, and is associated with alterations in C and N metabolism (McDonald and Davies, 1996). The decrease in water potential affects transpiration and hence xylem transport of nitrate or reduced N into growing regions. The response of the photo-synthetic apparatus either to water stress or rehydration seems to be dependent "on leaf age (O'Neill, 1983; Wolfe et al., 1988). Degradation of both thylakoid and stromal N-containing compounds can occur in response to water stress, recovery from which may pequire more than a week (Chaves, 1991).

SIEM à beira ria

Nos dias 4 e 5 de Setembro de 2010 realizou-se em Aveiro o XXI Seminário de Investigação em Educação Matemática. Ao contrário do que era habitual, o seminário decorreu nos dias seguintes ao ProfMat. O número de inscritos rondou os 150, incluindo participantes portugueses, espanhóis e brasileiros, que se distribuíram por 6 simpósios, com os seguintes temas: Conhecimento e práticas profissionais de professores de Matemática; Comunicação matemática; Resolução de problemas e raciocínio matemático; Formação e desenvolvimento profissional de professores; Aprendizagem da Matemática; e Questões históricas e culturais no ensino-aprendizagem da Matemática.

Evolução da qualidade da aguardente de medronho na região

A aguardente de medronho pela sua importância histórica, cultural e económica, para a região, tem sido objeto de vários estudos, desde o início da década de 90 do século XX. A fermentação é a tarefa mais sensível da produção de aguardente de medronho, porque precisa de usar medronhos em bom estado de maturação e decorrer sempre em recipientes fechados, apenas com saída para libertação do gás formado (dióxido de carbono – CO2). A destilação deve ser em alambique de cobre ou contendo cobre, mas as condutas e ou serpentinas devem ser de aço inox porque o cobre nessas condições é difícil de higienizar. A recolha e conservação do destilado deve ser feito em inox, vidro ou madeira e nunca em plástico, uma vez que o plástico deixa resíduos perigosos para a saúde (ftalatos e/ou estireno). Os resultados das aguardentes analisadas desde 2009 apresentam-se, em média, de acordo com as exigências da atual legislação. Deve-se contudo continuar a melhorar para conquistar mercados mais exigentes.

Pomegranate liquor preparation and analysis

The pomegranate (Punica granatum L.) liquor has been produced for several centuries in the south of Portugal, mainly in the mountain areas. The “Assaria” variety is the preferred cultivar due to its organoleptic properties and high arils to peel ratio. Wild pomegranates are also widely distributed but, despite the health benefits that have been associated to the fruits, they continue to be unappreciated for consumption. Liquor preparation is a very good alternative for wild pomegranate fruits. We prepared pomegranate liquors by following a maceration procedure using the arils or juice of Assaria and wild pomegranate fruits. Strawberry tree (Arbutus unedo L.) fruit spirits were used to prepare the liquors. At the end of the maceration time 5 day as minimum sugar syrup was added. The maturation period was three months or longer. The obtained liquors showed a very attractive pink colour. The colour and the total polyphenol, as well as the anthocyanin and ellagitannin profiles, were measured at the end of the maceration and maturation times. Wild pomegranates gave rise liquors with more intense pink colour and higher polyphenol contents than the prepared using Assaria fruits. The anthocyanin and ellagitannin profiles also indicated higher contents of polyphenols for liquors prepared using wild pomegranate fruits. When juice is used instead of complete arils during the maceration period punicalin is not present and the consequently total polyphenols is low. The main anthocyanins identified in the liquors were delphinidin-3,5-diglucoside, cyaniding-3,5-diglucoside, delphinidin–3-glucoside, cyaniding–3-glucoside, pelargonidin–3–glucoside; the main ellagitannins were punicalagin and punicalin.