E nesta aula eu utilizasse o Scratch?

A utilização de tecnologias na sala de aula pode trazer ao aluno um maior protagonismo na sua própria aprendizagem, passando de ouvinte atento e passivo do saber do professor para interveniente ativo na construção do seu próprio conhecimento. O Scratch poderá impulsionar este processo, visto que permite que os alunos se envolvam dinamicamente nas tarefas propostas, desenvolvam a sua capacidade criativa e de resolução de problemas, possibilitando abordagens com importantes contributos para a aprendizagem da matemática. Mas afinal o que é o Scratch? O Scratch é um ambiente gráfico de programação inovador, concebido no Massachusetts Institute of Technology (MIT), que torna a programação mais cativante e acessível às crianças, e a todos os que não possuem competências nessa área. A programação em Scratch é efetuada através da criação de sequências de comandos simples, que correspondem a blocos de várias categorias (movimento, controlo, aparência, sensores, som, operações, caneta e variáveis), encaixados e encadeados de forma a produzirem as ações desejadas. Como o Scratch torna fácil a combinação de gráficos, imagens, fotografias, música e som, em criações interativas, é possível criar histórias com cenários variados, conceber um jogo, fazer uma apresentação interativa para as aulas, representar e simular situações problemáticas, construir figuras geométricas, entre muitos outros exemplos. Nesta sessão prática pretende-se “apresentar” o Scratch, explorar algumas tarefas no domínio da matemática e refletir sobre as suas potencialidades educativas.info:eu-repo/semantics/publishedVersio

Computer-assisted independent study in multivariate calculus

Learning mathematics requires students to work in an independent way which is particularly challenging for such an abstract subject. Advancements in technology and, taking the student as the focus of his own learning, led to a change of paradigm in the design and development of educational contents. In this paper we describe the first experience with an interactive feedback and assessment tool (Siacua), based on parameterized math exercises, and explain how we use it to motivate student independent study in a multivariate calculus environment. We have defined an index about the subject, trying to make it consensual enough for being used in other courses about multivariate calculus. Then we have created a concept map, selected some existing parameterized true/false questions from PmatE project and classified them using our concept map, for being reused in our system. For complementing the course we have created about one hundred parameterized multiple choice question templates in system Megua and generated about one thousand instances for using in Siacua. Results based on data collected by this tool and also based on an informal survey are presented. This first experience allows us to conclude our approach has an important impact on student motivation and contributes to the success on learning multivariate calculus

Materiais baseados em La (Mg 0,5 Ti 0,5) O3 para aplicações nas microondas

Doutoramento em Ciência e Engenharia dos MateriaisOs sistemas de telecomunicações foram um dos sectores da indústria electrónica com maiores taxas de desenvolvimento nas últimas duas décadas. De modo a conseguir maior densidade e velocidade de tráfego de comunicações estas deslocaram-se para frequências superiores, as das microondas. A consequente necessidade de componentes para estes sistemas conduziu ao desenvolvimento de novos materiais dieléctricos com aplicações à frequência das microondas, onde é vital o controle das suas propriedades dieléctricas, nomeadamente, da permitividade (εr), das perdas e da variação da sua frequência de ressonância com a temperatura ambiente (τf). Uma forma de ajustar estas propriedades tem sido o recurso à formação de soluções sólidas ou misturas de compostos, de modo a conseguir cumprir os requisitos fundamentais, isto é, elevada εr, perdas dieléctricas diminutas e τf ≈ 0. Com o intuito de compreender os factores que afectam as propriedades dieléctricas à frequência das microondas, foram estudadas as relações entre o processamento, a estrutura e as referidas propriedades de materiais cerâmicos baseados em La(Mg0.5Ti0.5)O3 [LMT]. Este material cerâmico dieléctrico é promissor dado que exibe um factor de qualidade relativamente elevado, Q·fo = 114000 GHz a 7GHz, e εr = 27. No entanto, apresenta um valor elevado para o τf (-81 ppm/K), pelo que é imprescindível proceder ao seu ajuste. A mistura de materiais dieléctricos com valores de τf de sinal oposto tem sido a prática empírica corrente para o ajuste referido, no entanto, é necessário para um desenvolvimento mais eficaz de materiais para estas aplicações conhecer e compreender os mecanismos responsáveis pela variação destas propriedades. Alguns materiais com estrutura perovsquítica têm sido estudados para este tipo de aplicações, precisamente porque exibem um conjunto de características estruturais que podem influenciar as propriedades dieléctricas à frequência das microondas, constituindo-se assim como um excelente meio de estudo dos mecanismos determinantes. Neste trabalho foram usados para formar soluções sólidas de estrutura perovsquítica com o LMT, um grupo de titanatos de alcalino-terrosos (CaTiO3, SrTiO3 e BaTiO3) visando alterar a estrutura e as propriedades dieléctricas do material base. O processamento adequado dos pós condiciona de uma forma dramática as características dieléctricas dos cerâmicos e, assim, recorreu-se a um método de preparação por via química alternativo ao método convencional de mistura de óxidos. A partir dos pós obtidos por esta via, comparativamente à convencional, foi possível preparar cerâmicos densos, monofásicos e com microestruturas homogéneas a temperaturas bastante inferiores. Estes cerâmicos apresentam ainda perdas dieléctricas menores do que as obtidas em materiais preparados pela via convencional. Neste âmbito, foi optimizado o processamento de todas as composições das soluções sólidas [(1-x)LMT-xAT, com A = Ca, Sr e Ba; 0≤x<1], tendo sido atingido o objectivo de conseguir cerâmicos densos (>95%), monofásicos e homogéneos, fundamental quer para os estudos de caracterização dieléctrica quer para as próprias propriedades dieléctricas finais destes materiais. A estrutura cristalina dos materiais perovsquíticos pode influenciar as suas propriedades dieléctricas pelo que, neste trabalho, procedeu-se a um estudo detalhado da estrutura das soluções sólidas referidas anteriormente, recorrendo a técnicas de difracção de raios-X, coadjuvadas por análise de refinamento de Rietveld e de microscopia electrónica de transmissão. O material base [LMT] pertence ao grupo espacial P21/n (a-a-c+) e, a formação de soluções sólidas, com a substituição parcial no sítio A da estrutura perovsquítica, conduziu a uma série de modificações estruturais diferentes para os três catiões (Ca, Sr, Ba) envolvidos. O sistema LMT-CT foi o que apresentou menores alterações tendo-se observado apenas o desaparecimento da ordenação catiónica para x>0.1, pertencendo estes materiais ao grupo espacial Pbnm (a-a-c+). Em relação ao sistema LMT-ST, este exibe diversas alterações estruturais à medida que o teor de ST aumenta [P21/n (a-a-c+, ordenado no sítio B) → Pbnm (a-a-c+) → Imma (a-a-c0) → I4/mcm (a0a0c-)]. Para o sistema LMT-BT observaram-se as variações estruturais mais acentuadas [P21/n (a-a-c+, ordenado no sítio B) → Pbnm (a-a-c+) → I4/mcm (a0a0c-) → Pm3m (a0a0a0)]. Com a finalidade de correlacionar o processamento, a estrutura cristalina com as propriedades dieléctricas dos materiais destes sistemas, estas últimas foram caracterizadas à frequências das microondas (GHz), à frequência rádio (MHz) e, para o estudo dos mecanismos responsáveis, foram complementadas por medidas a frequências superiores (espectroscopia no infravermelho longínquo). As propriedades dieléctricas variam ao longo das soluções sólidas. A variação da εr é monotónica e segue a regra clássica das misturas atingindo-se valores interessantes para as aplicações nas microondas (εr>40). O τf varia de forma semelhante tendo-se conseguido, para os três sistemas, valores nulos para composições próximas de x=0.5. Esta característica varia linearmente com a εr em toda a extensão das soluções sólidas LMT-CT e LMT-ST. Este facto é um forte indício de que a diluição da polarizabilidade iónica é o mecanismo que controla o τf. Para o sistema LMT-BT esta linearidade é interrompida para x>0.5, o que pressupõe que o ajuste do τf é também condicionado pelo aparecimento da rotação dos octaedros de oxigénio. As perdas dieléctricas, descritas frequentemente através do seu inverso, o factor de qualidade dos ressonadores (Q), varia de forma semelhante para os três sistemas. O aumento do teor de AT provoca uma diminuição do Q, que é mais acentuada para x=0.1, apresentando um valor mínimo para x=0.5 embora tecnologicamente interessante. A queda inicial acentuada de Q resulta da diminuição da ordenação catiónica da estrutura sendo o mínimo verificado para x=0.5 relacionado com a presença de ordem a curta distância confirmada por espectroscopia Raman. A espectroscopia no infravermelho longínquo revelou-se útil para avaliar os contributos de carácter intrínseco e extrínseco para a perda dieléctrica. Ainda em relação ao sistema LMT-BT, é de realçar a descoberta da existência de um comportamento relaxor na zona da solução sólida rica em BT. Este é um dado importante tendo em conta tratar-se de um sistema relaxor constituído por materiais sem chumbo.Telecommunications systems are one of the sectors of electronic industry showing more dramatic growth in the last two decades. In order to achieve the highest communication densities or traffic these have moved on to higher frequencies such as the microwave range. The increasing need for components for these systems lead to the development of new dielectric materials suitable for applications at microwave systems, where the control of dielectric properties like permittivity (εr), losses and temperature stability of resonant frequency is fundamental. One way to tune these properties has been achieved trough the formation of solid solutions or mixtures in order to fulfil the fundamental requirements, such as high permittivity, low dielectric losses and a temperature coefficient of resonant frequency (τf) close to zero. Aiming to understand the factors affecting microwave dielectric properties, the relationships between processing, structure and dielectric properties of La(Mg0.5Ti0.5)O3 [LMT] based materials were studied. This dielectric ceramic material is a promising one since it shows a high quality factor, Q·fo = 114000 GHz at 7GHz, and a εr = 27. Nevertheless, it presents a high τf (-81ppm/K) that needs to be adjusted. Mixing dielectric materials with opposite τf values has been the current practice but a more efficient materials development rather imposes the understanding of the responsible mechanisms controlling these relevant properties. In this work, perovskite solid solutions based on LMT and a group of earthalkaline titanates (CaTiO3, SrTiO3 and BaTiO3) were used in order to change the structure and dielectric properties of the base material. Powder processing has a great influence on the ceramic dielectric characteristics and so a chemical powder preparation was used instead of the conventional mixed oxide route. With the chemically prepared powders it was possible to prepare dense, single phase ceramics with homogeneous microstructures at lower temperatures. These ceramics even presented lower dielectric losses than the ones obtained by the conventional route. Processing of all compositions resulting from solid solution formation with calcium, strontium and barium titanates [(1-x)LMT-xAT, and A = Ca, Sr and Ba; 0≤x<1] was optimized. For all compositions the objective of getting dense (>95%), single phase and homogeneous ceramics was achieved, which is fundamental for dielectric characterization studies as well as for the final dielectric properties of microwave materials. Crystallographic structure of perovskite materials may influence their dielectric properties which led to the detailed study in this work of those solid solutions structure, with the help of techniques such as X-ray diffraction, together with Rietveld refinements studies, and transmission electron microscopy. The base material [LMT] belongs to P21/n space group (a-a-c+ tilt system) and presents a 1:1 B-site ordered monoclinic structure, with in-phase and anti-phase tilting of the oxygen octahedra, and anti-parallel shift of the lanthanum cations (A site). Formation of solid solutions with A-site partial substitution leaded to a series of structural modifications which were different for the three used cations (Ca, Sr, Ba). LMT-CT system was the one that presented slighter changes since all compositions with x>0.1 belong to the same space group (Pbnm) and present anti-parallel of A-site cations, in-phase and anti-phase tilting of oxygen octahedra (a-a-c+ tilt system). Regarding LMT-ST system, it exhibits several structural changes with the increase of ST content (x) [P21/n (a-a-c+, B site ordered) → Pbnm (a-a-c+) → Imma (a-a-c0) → I4/mcm (a0a0c-)]. For LMT-BT solid solutions greater variations were observed [P21/n (a-a-c+, B site ordered) → Pbnm (a-a-c+) → I4/mcm (a0a0c-) → Pm3m (a0a0a0)]. These observations were confirmed by TEM with the help of electron diffraction patterns and darkfield imaging. Aiming to correlate processing, structure and dielectric properties of the materials in these systems, these last ones were measured at microwave frequencies (GHz), at radiofrequency (MHz) and, for the study of its responsible mechanisms, they were complemented by measurements at even higher frequencies (far infrared spectroscopy). Dielectric properties changes with the composition of these solid solutions. Permittivity variation is monotonic, following the classic mixture rule and interesting values for microwave frequencies (εr>40) were obtained. Temperature coefficient of resonant frequency (τf) varies in a similar way for the three systems and close to zero values were obtained for compositions near x=0.5. This property varies linearly with permittivity throughout the entire LMTCT and LMT-ST solid solutions. This behaviour strongly indicates that ionic polarizability dilution is the main τf controlling mechanism. For LMT-BT this linearity is cut off around x>0.5, which may indicate that τf tuning is also conditioned by the onset of oxygen octahedral tilting happening in this range. Dielectric losses, often described by the quality factor (Q) vary in a similar way for the three studied systems. The AT increase causes a Q decrease, which is more pronounced for x=0.1 and presenting a minimum for x=0.5, although with technological interesting values. The initial drop in Q values results from the decrease of the cation ordering whereas the minimum at x=0.5 is related with the presence of short range order as confirmed from Raman spectroscopy. Far infrared spectroscopy as revealed to be useful for the evaluation of intrinsic and extrinsic contributions to dielectric loss. Still regarding the LMT-BT system, it is worth to emphasise the appearance of a relaxor behaviour in the BT-rich compositions. This is particularly important since it is a lead-free material relaxor system

Carbon-modified titanium oxide materials for photocatalytic water and air decontamination

Titanium oxide-based materials with different physical and chemical features were synthetized aiming at removing organic pollutants from both water and air media. The materials were produced employing two different heating methodologies (thermal, T and hydrothermal, H) at distinct temperatures resulting in porous materials. These materials were also modified with either graphene oxide (GO) or carbon nanotubes (CNT), using an in-situ approach. All materials were tested as photocatalysts using ultra-violet (UV), visible (Vis) and solar radiation. Rhodamine B (RhB) and benzene were used as representative pollutants in water and air, respectively. The addition of carbon to the catalysts improved the removal of both pollutants. In the case of the photocatalytic degradation of rhodamine B, under both UV and Vis light, it was found that, the materials containing carbon nanostructures allowed the highest degradation degree, while the photosensitisation phenomenon became negligible. The best catalyst is the one containing CNT (2.98 wt% of C) and thermally treated at 300 °C (T300_CNT). This material showed higher degradation ability than the commercial TiO2 nanopowder Degussa P25 (P25) under Vis light. Regarding benzene removal, the samples thermally treated at 300 °C and modified with CNT and GO (T300_CNT and T300_GO, respectively) outperformed Degussa P25. The former material was successfully reused in the photocatalytic degradation of benzene over 6 consecutive cycles.publishe

Ni-doped Hibonite (CaAl12O19): A New Turquoise Blue Ceramic Pigment

A new structure for ceramic pigments was synthesized by a conventional solid state reaction process. It is based on Ni-doped hibonite, CaAl12O19, which assumes a turquoise-like blue colour similar to that of V-doped zircon. Hibonite is associated with anorthite, CaAl2Si2O8, acting like a fluxing agent in order to lower the synthesis temperature, and with cassiterite, SnO2, acting as a tin buffer to promote coupled Ni2+ + Sn4+ -> Al3+ + Al3+ substitution, in order to ensure the electric neutrality of the hibonite lattice. Since relatively low chromophore contents are required, this new system constitutes an interesting alternative to the common blue ceramic pigments based on cobalt aluminate spinel or vanadium-doped zircon, implying lower cost and environmental advantages. The pigments characterization was performed by X-ray powder diffraction, diffuse reflectance spectroscopy, CIELAB colourimetric analysis, and testing in ceramic glazes and bodies. The substitution of Al3+ by bigger ions, like Ni2+ and Sn4+, increases the cell volume compared to undoped hibonite and is responsible of the turquoise blue colour, as verified by UV-Vis analysis. The chromatic mechanism is due to incorporation of Ni2+ in tetrahedral coordination, likely occurring at the site M3 of the hibonite lattice, where it partially substitutes the Al3+ ion. While this product shows a strong hue as a pigment, it is not stable after severe testing in glazes and attempts to improve its colouring performance are now under development

Projeto EGID3: perceções dos estudantes sobre a Geometria e o seu ensino

O projeto de investigação – EGID3: ensino da Geometria, investindo no diagnóstico, dificuldades e desafios surge do interesse comum dos investigadores nas práticas letivas dos professores e, particularmente, no ensino superior. O contexto de realização deste é a unidade curricular de Geometria da Licenciatura em Educação Básica. Este trabalho apresenta características de investigação sobre a própria prática profissional, com uma natureza reflexiva e colaborativa. É nosso entendimento que o envolvimento do professor na investigação o ajuda a lidar com as situações decorrentes da sua prática letiva que por vezes surgem de forma imprevista. Simultaneamente, este envolvimento, propicia-lhe a construção do seu conhecimento profissional. Além da importância atribuída ao diagnóstico das dificuldades dos estudantes, à valorização do ensino do tipo exploratório e ao papel das tarefas matemáticas na condução da prática letiva, numa primeira etapa, deste projeto, averiguámos as perceções do estudante face à Geometria e o seu ensino. Estas perceções poderão ter implicações na forma como os estudantes interpretam os conteúdos em estudo e no modo como futuramente os irão trabalhar na sua prática enquanto professores. Assim, nesta comunicação pretendemos aprofundar a análise realizada numa divulgação anterior, cruzando os resultados relativos às perceções dos estudantes sobre o significado atribuído à Geometria e às estratégias que consideram ser as adequadas no processo de ensino e aprendizagem da unidade curricular em causa, com as perceções manifestadas face ao experienciado nos ensino básico e secundário: atividades que recordam com agrado, dificuldades sentidas e recursos utilizados. Os participantes neste projeto são, pois, a professora e os estudantes de uma turma. A recolha de dados, no caso concreto da etapa aqui exposta, foi efetuada com recurso a questionários. A análise dos dados focou-se na análise de conteúdo das respostas dos estudantes ao questionário inicial. É possível destacar: (i) o conceito de geometria é significativamente associado a “figuras geométricas” ou simplesmente “figuras”; (ii) o recurso a “aulas práticas” destaca-se nas sugestões de estratégias no ensino da Geometria, se bem que com idêntica eloquência é também referido “aulas expositivas”; (iii) acerca das dificuldades sentidas no ensino básico e secundário no estudo da geometria sobressai a realização de cálculos (por exemplo, o cálculo dos ângulos); (iv) o trabalho com sólidos geométricos é enfatizado na identificação de estratégias de maior agrado nos níveis de ensino anteriores; e (v) a régua, o esquadro e o compasso são identificados como os recursos mais utilizados anteriormente.info:eu-repo/semantics/publishedVersio

Supervision in continuous teacher training

The concept of Supervision is not new, however, in the XXI century, has been reframed and gained a more relevant status in Portugal, because it operates in a changing context of the exercise of the teaching profession, emerging associated with a new paradigm of teachers’ intervention and action. With regard, continuing education is assumed as a determining factor, and therefore the present study searched for i) evidence of implementation of supervising nature of supervision practices and iii) perceptions/opinions of those involved in the CFAEs, in order to establish the concept of supervision of its stakeholders. We followed a multiple case study design, selected and characterized five CFAEs geographically dispersed in the Portuguese mainland (North, Centre, Lisbon and South), we developed instruments for opinion collection, with a sample of directors, trainers and trainees with a mixed methodology: qualitative through interview with the directors of the CFAE’s and quantitative (the predominant approach) through a questionnaire applied to trainees and trainers (who do not accumulate those two functions in the period of analysis). Results of both the interviews and the questionnaires were presented by category. The relevance of pedagogical supervision in order to present a recognized and respected praxis is therefore assumed, with the purpose of making it essential to the efficient and effective balance of the Education and Training system(s) in Portugal.info:eu-repo/semantics/publishedVersio

Development of a platform to align education and practice: bridging academia and the profession in Portugal

Limited fitness for practice may result from a mismatch between education and practice. Aiming to meet the common interests of academics and practitioners, the Portuguese Pharmaceutical Society (PPS) developed the Education and Practice Platform (EPP). The EPP includes one representative from each pharmacy faculty, and all Councils of Speciality Boards of Practice. Brainstorming with involved parties enabled sharing of interests, concerns and identifying a common path. Aims, mission, vision and values were set. The EPP's mission is to: act as an enabler to foster the quality and adequacy of education through sharing best practices, ultimately leading to facilitate professional integration, and to foster quality development in teaching practices with recognition for autonomy in freedom to teach and to learn. Its vision is an alignment of education and practice with the PPS' statutes to ensure validation of the competences defined for each practice area, and compliance with international guidance. Key performance indicators (KPIs) were set. Activities developed include the creation of a national forum to discuss education and practice, development of workshops on teaching methods and pharmacy internships, enhanced representation in international events and response to global and national requests. Ongoing work focuses on the creation of a common training framework in hospital and community pharmacy practice adapted to Portugal. The EPP is a worldwide case study, encouraging the development of discussion contributing to an open climate of sharing best practices, indirectly leading to foster a better alignment between education and practice. Many of these results are so far intangible in scientific terms but worth describing.info:eu-repo/semantics/publishedVersio

Evaluation of the antioxidant activity of cell extracts from microalgae

A growing market for novel antioxidants obtained from non-expensive sources justifies educated screening of microalgae for their potential antioxidant features. Characterization of the antioxidant profile of 18 species of cyanobacteria (prokaryotic microalgae) and 23 species of (eukaryotic) microalgae is accordingly reported in this paper. The total antioxidant capacity, accounted for by both water- and lipid-soluble antioxidants, was evaluated by the (radical cation) ABTS method. For complementary characterization of cell extracts, a deoxyribose assay was carried out, as well as a bacteriophage P22/Salmonella-mediated approach. The microalga Scenedesmus obliquus strain M2-1 exhibited the highest (p > 0.05) total antioxidant capacity (149 ± 47 AAU) of intracellular extracts. Its scavenger activity correlated well with its protective effects against DNA oxidative damage induced by copper(II)-ascorbic acid; and against decay in bacteriophage infection capacity induced by H2O2. Finally, performance of an Ames test revealed no mutagenic effects of the said extract.info:eu-repo/semantics/publishedVersio

Sol gel graphene/TiO2 nanoparticles for the photocatalytic-assisted sensing and abatement of NO2

Abstract Human exposure to volatile organic compounds and NO2 can lead to health problems, therefore strategies to mitigate against the risks are required. Abatement and sensing are approaches which could both neutralise and monitor these species thus providing a safer environment and warning occupants of harmful levels. This paper presents pure TiO2 and TiO2/graphene hybrids synthesized through a sol-gel route. Electron optical, helium ion microscopy, X-ray diffraction and spectroscopic methods have been applied to elucidate the physical and chemical behaviour. NO2 sensing properties of TiO2/graphene hybrids formed by the addition of graphene to the reaction vessel prior to initiating the sol gel reaction followed by annealing (GTiO2S), and an alternative manufacturing method involving the addition of graphene to TiO2 nanoparticles which had already been annealed (GTiO2M) were compared and evaluated. A conductometric sensor based on TiO2/graphene prepared using material GTiO2S showed a higher response to NO2 compared to sensors based on pure TiO2 and TiO2/graphene prepared with material GTiO2M. Under UV irradiation generated by a low power LED, the sensor showed a remarkably enhanced response to 1750 ppb NO2, about double the response in the dark, and a limit of detection of about 50 ppb of NO2 (Signal/Noise = 3). Photocatalytic tests to assess the degradation of NOx showed that TiO2/graphene hybrids using material GTiO2S were the most active amongst the whole series of TiO2-based materials. Our data highlights the unique characteristics of material GTiO2S TiO2/graphene and the suitability for multi-purpose applications in the field of environmental monitoring and remediation. The capability of the material for both sensing and abatement of NOx could be exploited to offer a safer environment through providing a warning of the presence of NOx whilst also reducing levels