949 resultados para Scientific apparatus and instruments
Resumo:
Polymer/montmorillonite nanocomposites were prepared. Intercalation of 2-aminobenzene sulfonic acid with aniline monomers into montmorillonite modified by cation was followed by subsequent oxidative polymerization of monomers in the interlayer spacing. The clay was prepared by cation exchange process between sodium cation in (M–Na) and copper cation (M–Cu). XRD analyses show the manifestation of a basal spacing (d-spacing) for M–Cu changes depending on the inorganic cation and the polymer intercalated in the M–Cu structure. TGA analyses reveal that polymer/M–Cu composites is less stable than M–Cu. The conductivity of the composites is found to be 103 times higher than that for M–Cu. The microscopic examinations including TEM picture of the nanocomposite demonstrated an entirely different and more compatible morphology. Remarkable differences in the properties of the polymers have also been observed by UV–Vis and FTIR, suggesting that the polymer produced with presence of aniline has a higher degree of branching. The electrochemical behavior of the polymers extracted from the nanocomposites has been studied by cyclic voltammetry which indicates the electroactive effect of nanocomposite gradually increased with aniline in the polymer chain.
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Polyaniline/montmorillonite nanocomposites (PANI/M) were obtained by intercalation of aniline monomer into M modified with different cations and subsequent oxidative polymerization of the aniline. The modified-clay was prepared by ion exchange of sodium, copper and iron cations in the clay (Na–M, Cu–M and Fe–M respectively). Infrared spectroscopy confirms the electrostatic interaction between the oxidized PANI and the negatively charged surface of the clay. X-ray diffraction analysis provides structural information of the prepared materials. The nanocomposites were characterized by transmission electron microscopy and their thermal degradation was investigated by thermogravimetric analysis. The weight loss suggests that the PANI chains in the nanocomposites have higher thermal stability than pure PANI. The electrical conductivity of the nanocomposites increased between 12 and 24 times with respect to the pure M and this increase was dependent on the cation-modification. The electrochemical behavior of the polymers extracted from the nanocomposites was studied by cyclic voltammetry and a good electrochemical response was observed.
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This study analyses the relationship between self-reported social anxiety and academic performance in a sample of 1,616 Spanish students (52.1% males) in compulsory secondary education, aged 12 to 16 years old. Social anxiety was assessed by the Social Phobia and Anxiety Inventory (SPAI) and academic performance was measured with school grades and failing grades. Results reveal that adolescents with social anxiety show a similar academic performance to adolescents without social anxiety. Although t tests found some significant differences in academic grades and number of failing grades, the effect size analysis showed that these differences had no empirical relevance. These findings are discussed considering the gender and grade levels and their theoretical and practical implication.
Resumo:
A simple method was used to synthesize poly(2-aminophenol), poly(2-aminophenol-co-Aniline) and polyaniline nanocomposites with sodium-montmorillonite (Na-M) using in situ intercalative oxidative polymerization. Morphology and thermal properties of the synthesized nanocomposites were examined by transmission electron microscopy (TEM) and thermogravimetric analysis. The thermal analysis shows an improved thermal stability of the nanocomposites in comparison with the pure poly(2-aminophenol). The intercalation of polymers into the clay layers was confirmed by X-ray diffraction studies, TEM images and FTIR spectroscopy. In addition, the room temperature conductivity values of these nanocomposites varied between 8.21 × 10−5 and 6.76 × 10−4 S cm−1. The electrochemical behavior of the polymers extracted from the nanocomposites, has been analyzed by cyclic voltammetry. Good electrochemical response has been observed for polymer films; the observed redox processes indicate that the polymerization into Na-M produces electroactive polymers.
Resumo:
A novel polymer/TiC nanocomposites “PPA/TiC, poly(PA-co-ANI)/TiC and PANI/TiC” was successfully synthesized by chemical oxidation polymerization at room temperature using p-anisidine and/or aniline monomers and titanium carbide (TiC) in the presence of hydrochloric acid as a dopant with ammonium persulfate as oxidant. These nanocomposites obtained were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and thermogravimetric analysis (TGA). XRD indicated the presence of interactions between polymers and TiC nanoparticle and the TGA revealed that the TiC nanoparticles improve the thermal stability of the polymers. The electrical conductivity of nanocomposites is in the range of 0.079–0.91 S cm−1. The electrochemical behavior of the polymers extracted from the nanocomposites has been analyzed by cyclic voltammetry. Good electrochemical response has been observed for polymer films; the observed redox processes indicate that the polymerisation on TiC nanoparticles produces electroactive polymers. These nanocomposite microspheres can potentially used in commercial applications as fillers for antistatic and anticorrosion coatings.
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The study of digital competence remains an issue of interest for both the scientific community and the supranational political agenda. This study uses the Delphi method to validate the design of a questionnaire to determine the perceived importance of digital competence in higher education. The questionnaire was constructed from different framework documents in digital competence standards (NETS, ACLR, UNESCO). The triangulation of non-parametric techniques made it possible to consolidate the results obtained through the Delphi panel, the suitability of which was highlighted through the expert competence index (K). The resulting questionnaire emerges as a good tool for undertaking future national and international studies on digital competence in higher education.
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The European Union (EU) has increasingly become a comprehensive security actor. With the development of the Common Foreign and Security Policy (CFSP), including the Common Security and Defence Policy (CSDP) as a reaction to the failure of the EU to act during the wars in Yugoslavia/Western Balkans in the 1990s, the EU has a wide range of instruments for crisis prevention, crisis management as well as post-crisis intervention at its disposal. Observers typically agree that “hard power” is no longer sufficient to address the complex security challenges of today’s world while the EU, often criticised for only utilising “soft power”, is now able to exercise “smart power”. Through a comprehensive approach, facilitated by the Lisbon Treaty, the EU can now use the various instruments at its disposal, such as diplomacy, development aid, humanitarian assistance, trade, sanctions, international cooperation and crisis management capabilities in a joined-up manner. This mix of tools and instruments is helping the EU to achieve the aim set out in its European Security Strategy: “a secure Europe in a better world”.
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The European Union and Singapore are vastly different entities, each with its own regional and global priorities and policies. Both actors employ a range of tools and instruments to aid in their foreign policy objectives, including in the projection of their soft power. It is worth analysing and comparing the specific instruments of these two actors’ soft power strategies, including but not limited to their stated objectives and perceived effectiveness. This paper will compare the role of higher education and scholarships in diffusing soft power through a comparative case study of the Erasmus Mundus scholarship program and the Singapore Scholarship administered by the Ministry of Foreign Affairs. It will look at the ways in which these programs have shaped the standing of the actors in diffusing their norms and objectives in the regional and international arena. A comparative analysis of these programs will hopefully provide some insight into the proximity between foreign policy-making and higher education internationalisation. This paper will begin with an overview of the aforementioned programs and related schemes, before dissecting and comparing the intent and the policy-making processes behind these, and concludes with a discussion on the present and future role of higher education as a strategic soft power tool.
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The Education and Training Programme has been set up in recognition of the growing importance of continuing education in modern technological society. It is designed to improve the dissemination of scientific and technical knowledge in subjects related to the research activities of the JRC, to the potential external users: industries, public bodies, research and educational organizations, etc. . . Moreover, owing to the number and the quality of specialists of the various fields covered by the courses who are brought to Ispra as lecturers or participants, this programme plays an important role in the integration of the research teams of the JRC with the European scientific world, and in. the development of contacts and ties between European scientists active in a given field.
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Este estudo insere-se num relatório de estágio, referente ao grau de Mestre em Educação Pré-Escolar e Ensino do 1.º Ciclo do Ensino Básico, e baseia-se numa problemática assente na análise das potencialidades do trabalho prático de orientação investigativa (TPOI). Tratase de uma pesquisa na prática profissional desenvolvida em contexto de estágio, em duas escolas do 1.º CEB do Concelho de Santarém, que teve ainda como objetivo compreender as dificuldades que se colocam durante a planificação e implementação de atividades POI. Para o efeito, utilizaram-se diferentes instrumentos de recolha de dados: observação, entrevistas e documentos escritos. Ao longo do processo de planificação/implementação/reflexão foram identificadas as principais dificuldades sentidas pela futura educadora/professora nomeadamente a preparação dos guiões e do material, a gestão da turma e as dificuldades dos alunos. Os resultados demonstraram inúmeras potencialidades do TPOI na promoção de aprendizagens ao nível dos conteúdos científicos abordados, dos processos científicos e do trabalho de grupo. Contudo, os resultados permitiram também constatar que um grau de abertura elevado das atividades nem sempre apresenta o efeito desejável nas aprendizagens dos alunos, verificando-se que as características dos alunos e uma maior familiarização com este tipo de atividade é condição essencial para promover a autonomia.
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Les institutions de mémoire et de savoir (par exemple, les bibliothèques, les archives, les musées) font face à des défis importants dans leurs responsabilités d’assurer la pérennité du patrimoine documentaire à l’ère numérique. Citons la surabondance de l’information numérique, la possibilité de production, théoriquement illimitée, offerte aux individus comme aux groupes sociaux, les limites dans les capacités de stockage et de diffusion de l’information numérique qui sont à la disposition des institutions mandataires du patrimoine documentaire. De plus, il est apparu que les approches et les méthodes utilisées pour identifier, gérer, préserver et diffuser le patrimoine documentaire de la société canadienne dans un environnement analogique n’étaient transférables à un environnement numérique. Nous suggérons que la théorie sociale de la connaissance peut servir de base à une réflexion portant sur le développement d’une politique publique qui viserait à encadrer l’identification, la sélection, la gestion et la préservation du patrimoine documentaire d’une société à l'ère numérique. Nous définissons la problématique puis proposons des réponses à travers trois articles scientifiques. Les résultats indiquent que les connaissances et les pratiques professionnelles utilisées demeurent persistantes et limitent la formulation et l'application de nouveaux cadres théoriques, de politiques administratives et de techniques associés à l'identification et la sélection du patrimoine documentaire. Cette recherche propose un cadre conceptuel qui permet de développer des politiques publiques sur le patrimoine documentaire du Canada.
Resumo:
Long-term ecological data are essential for conservation and to monitor and evaluate the effects of environmental change. Bird populations have been routinely assessed on islands off the British coast for many years and here long term data for one such island, Skokholm, is evaluated for robustness in the light of some 20 changes in observers (wardens) on the island over nearly eight decades. It was found that the dataset was robust when compared to bootstrap data with no species showing significant changes in abundance in years when wardens changed. It is concluded that the breeding bird populations on Skokholm and other British offshore islands are an important scientific resource and that protocols should be enacted to ensure the archiving of records, the continuance of data collection using standardised protocols into the future, and the recognition of such long-term data for science in terms of an appropriate conservation designation.
Resumo:
The mass-accumulation rate and grain size of the total eolian component of North Pacific pelagic clays at Deep Sea Drilling Project Sites 576 and 578 have been used to evaluate changes in eolian sedimentation and the intensity of atmospheric circulation that have occurred during the past 70 m.y. Eolian deposition, an indicator of source area aridity, was low in the Paleocene, Eocene, and Oligocene, apparently reflecting the humid environments of that time as well as the lack of glacial erosion products. A general increase in eoiian accumulation in the Miocene apparently reflects the relative increase in global aridity during the latter part of the Cenozoic. A dramatic increase in eolian accumulation rates in the Pliocene reflects the increased aridity and availability of glacial erosion products associated with Northern Hemisphere glaciation 2.5 m.y. ago. Eolian grain size, an indicator of wind intensity, suggests that Late Cretaceous wind strength was comparable to present-day wind strength. A sharp decrease in eolian grain size across the Paleocene/Eocene boundary is not readily interpreted, but may indicate a significant reduction in the intensity of atmospheric circulation at that time. Fine eolian grain size and low accumulation rates in the Eocene and early Oligocene are in agreement with low early Tertiary thermal gradients and less vigorous atmospheric circulation. Large increases in grain size during the Oligocene, mid-to-late Miocene, and Pliocene appear to be a response to steepening thermal gradients resulting from increasing polar isolation.
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