Síntese e caracterização de nanocompósitos funcionais de matriz polimérica

Doutoramento em QuímicaO principal objectivo desta tese foi investigar diversas estratégias de síntese de nanocompósitos de matriz polimérica. A funcionalidade destes nanomateriais consiste no enorme potencial que apresentam para aplicações tecnológicas, tais como em optolectrónica ou em biomedicina. No primeiro capítulo apresenta-se uma revisão bibliográfica, onde são realçados os principais tópicos discutidos ao longo da tese. Apresentam-se inicialmente algumas considerações sobre a utilização de nanopartículas inorgânicas como cargas. Em seguida, descrevem-se aplicações possíveis dos nanocompósitos de matriz polimérica, que ilustram o enorme impacto tecnológico destes nanomateriais. São ainda abordadas metodologias de modificação da superfície dos componentes inorgânicos, e a revisão é concluída com uma breve descrição das estratégias de síntese de nanocompósitos. Neste tópico é dado especial destaque para os mecanismos de polimerização radicalar controlada/viva (CRP/LRP) em meio aquoso, e a partir de superfícies inorgânicas. No segundo capítulo, apresentam-se os resultados obtidos com nanocompósitos do tipo Bi2S3/SiO2/poli(estireno). As nanofibras de Bi2S3 previamente recobertas com SiO2, foram modificadas com MPS. Na preparação destes nanocompósitos, utilizaram-se duas técnicas de polimerização in situ em meio aquoso: emulsão e suspensão. A escolha da técnica de polimerização foi efectuada, considerando o tipo e dimensão das cargas inorgânicas e a morfologia pretendida para as partículas do compósito, de forma a obter nanomateriais homogéneos. Os resultados obtidos mostraram que, o tipo de morfologia obtida no nanocompósito, é influenciada por vários factores envolvidos na sua síntese nomeadamente, pela técnica de polimerização e pela modificação da superfície das nanopartículas inorgânicas. No terceiro capítulo, é apresentado um estudo sobre as características das superfícies presentes em nanocompósitos de SiO2/poli(estireno), ao longo do processo de síntese. Os resultados permitiram evidenciar a importância das interacções entre o polímero e as nanopartículas, na morfologia e características destes nanocompósitos poliméricos, preparados por polimerização in situ em emulsão. Investigou-se ainda a influência da utilização do MPS em polimerização radicalar em meio aquoso. Este estudo foi efectuado através da medição de ângulos de contacto, áreas de superfície e porosidade dos materiais, nas várias fases do processo de síntese dos nanocompósitos de SiO2/poli(estireno). No quarto capítulo apresentam-se resultados obtidos com nanocompósitos de QDs/ polímero, preparados por polimerização radicalar in situ em miniemulsão. Descreve-se em primeiro, a utilização do mecanismo de polimerização radicalar convencional, para preparar nanocompósitos de poli(estireno) e poli(acrilato de butilo), na presença de QDs de CdS e CdSe. As propriedades ópticas destes nanocompósitos foram investigadas através de absorção no visível e PL. Os nanocompósitos preparados apresentam efeitos de confinamento quântico, conferidos pela presença dos QDs. No quinto capítulo, foram utilizados dois mecanismos de polimerização radical controlada (CRP/LRP) para preparar o mesmo tipo de nanocompósitos: ATRP e RAFT. Nestes casos, a polimerização foi efectuada a partir da superfície dos QDs, e obteve-se maior controlo sobre as características das matrizes poliméricas (M n e PDI). Nesta dissertação estabeleceram-se novos caminhos para a compreensão e optimização dos mecanismos de formação de materiais híbridos, bem como das interacções que ocorrem ao nível das interfaces de natureza inorgânica/orgânica. As propriedades destes nanomateriais permitem antecipar futuras aplicações em diversas áreas tecnológicas.The aim of this thesis was to investigate different synthetic strategies for the preparation of polymer based nanocomposites. The functionality of these nanomaterials relies on their enormous potential for technological applications, such as in optoelectronics or biomedicine. The first chapter consists in a literature review focused on the aim topics discussed in the thesis. The first considerations regard the use of inorganic nanoparticles as fillers. Next, some of the possible applications for nanocomposites are described, evidencing the large impact of these nanomaterials in different technological fields. A brief review of the methods currently used to modify the inorganic materials surface is also presented. The review is concluded with a description of the methods most commonly used to prepare nanocomposites, with special attention to controlled/living radical polymerization (CRP/LRP) mechanisms on aqueous media, and from inorganic surfaces. In the second chapter the preparation and characterization of Bi2S3/SiO2/poly(styrene) nanocomposites is presented. The Bi2S3 nanofibers were previously covered with SiO2, and modified with a silane coupling agent, (MPS). Two different in situ polymerization techniques were used in the preparation of these nanocomposites: emulsion and suspension. The polymerization technique was tuned in order to obtain homogeneous nanocomposites, based on the type and dimensions of the fillers and on the target morphology for the final particles. The results have shown that the morphology observed for the final nanocomposites is strongly influenced by several parameters concerning the synthetic procedure, namely the polymerization technique used and the modification carried out on the inorganic fillers surface. The third chapter, is devoted to study of the characteristics of the different surfaces present in SiO2/poly(styrene) nanocomposites, along the synthesis process. The results substantiate the importance of the interactions between polymers and fillers, in the morphology and characteristics of these nanocomposites, when prepared by in situ emulsion polymerization. The influence of the use of the silane coupling agent MPS in aqueous media on the final properties of the nanocomposites was also investigated. These studies were carried out by measuring contact angles, specific surface areas, and the porosity of the materials, throughout the synthesis of the SiO2/poly(styrene) nanocomposites. The fourth chapter is concerned with the synthesis and characterization of QDs/Polymer nanocomposites prepared via in situ miniemulsion polymerization. In the first part, conventional radical polymerization was used to prepare poly(styrene) and poly(butyl acrylate) nanocomposites in the presence of CdS and CdSe QDs. The optical properties of the nanocomposites were evaluated by Visible absorption and PL. Quantum confinement effects were assigned to the nanocomposites due to the presence of the QDs. In the fifth chapter, two controlled/living radical polymerization (CRP/LRP) mechanisms: ATRP and RAFT, were investigated to prepare QDs/Polymer nanocomposites. In this case, the polymerization was carried out directly from the surface of the QDs, and a higher control over the polymer characteristics (M n and PDI) was obtained. In this thesis, new routes have been opened to the understanding and optimization of the mechanisms of nanocomposites formation, as well as the nature of the interactions between inorganic/organic interfaces. These nanomaterials evidence exhibit unique properties that allow anticipating potential technologic applications

Relação entre a matemática e a educação física em integração curricular

Relatório de Prática de Ensino Supervisionada apresentado à Escola Superior de Educação de Lisboa para obtenção de grau de mestre em Ensino do 1.º Ciclo do Ensino Básico e de Matemática e Ciências Naturais no 2.º Ciclo do Ensino BásicoO presente relatório surge no âmbito da Prática de Ensino Supervisionada II, inserida no plano de estudos do 2.º ano do Mestrado em Ensino do 1.º Ciclo do Ensino Básico (CEB) e de Matemática e Ciências Naturais do 2.º Ciclo do Ensino Básico. São expostos dois contextos de ensino, um em 1.º CEB e o outro em 2.º CEB e apresentada a síntese das duas práticas interventivas. Ademais é apresentado um estudo investigativo realizado no contexto do 1.º Ciclo do Ensino Básico. O estudo apresentado procurou compreender quais as potencialidades de integração curricular entre a matemática e a educação física, especificamente na relação entre as capacidades matemáticas e o desenvolvimento da competência motora, intentando: (i) conhecer os contributos da integração curricular entre matemática e Educação Física na aprendizagem dos alunos; e (ii) - relacionar a aprendizagem da matemática com a competência motora. Trata-se de um estudo de natureza qualitativa e com abordagem interpretativa. Na investigação participaram 20 alunos (13 rapazes e 7 raparigas) de uma turma de 4.ºano de escolaridade. Para atingir os objetivos acima referidos, foram elaboradas tarefas onde a matemática e a educação física se encontravam articuladas. Assim, foi possível concluir que através das atividades realizadas, os alunos melhoraram as suas aprendizagens a matemática e a educação física e ainda, melhoraram a sua motivação na realização das tarefas propostas.This report is part of the Supervised Teaching Practice II, included in the study plan of the 2nd year of the Master's Degree in Teaching in the1st Cycle of Basic Education (CEB) and Mathematics and Natural Sciences of the 2nd Cycle of Basic Education. Two teaching contexts are exposed, one in Primary School and the other in Secondary School and a synthesis of the two interventional practices is presented. Furthermore, an investigative study carried out in the context of the 1st cycle of basic education is presented. The presented study tried to understand which are the potentialities of curricular integration between mathematics and physical education, specifically in the relation between mathematical abilities and the development of motor competence, intending: (i) to know the contributions of curricular integration between mathematics and Physical Education in the students' learning; and (ii) - to relate the learning of mathematics with motor competence. This is a qualitative study with an interpretative approach. Twenty students (13 boys and 7 girls) from a 4th grade class participated in the research. To achieve the above-mentioned objectives, tasks were developed where mathematics and physical education were articulated. Thus, it was possible to conclude that through the activities performed, students improved their learning in mathematics and physical education and also improved their motivation in performing the proposed tasks.N/

The Changing Landscape for Stroke\ua0Prevention in AF: Findings From the GLORIA-AF Registry Phase 2

Background GLORIA-AF (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients with Atrial Fibrillation) is a prospective, global registry program describing antithrombotic treatment patterns in patients with newly diagnosed nonvalvular atrial fibrillation at risk of stroke. Phase 2 began when dabigatran, the first non\u2013vitamin K antagonist oral anticoagulant (NOAC), became available. Objectives This study sought to describe phase 2 baseline data and compare these with the pre-NOAC era collected during phase 1. Methods During phase 2, 15,641 consenting patients were enrolled (November 2011 to December 2014); 15,092 were eligible. This pre-specified cross-sectional analysis describes eligible patients\u2019 baseline characteristics. Atrial fibrillation disease characteristics, medical outcomes, and concomitant diseases and medications were collected. Data were analyzed using descriptive statistics. Results Of the total patients, 45.5% were female; median age was 71 (interquartile range: 64, 78) years. Patients were from Europe (47.1%), North America (22.5%), Asia (20.3%), Latin America (6.0%), and the Middle East/Africa (4.0%). Most had high stroke risk (CHA2DS2-VASc [Congestive heart failure, Hypertension, Age  6575 years, Diabetes mellitus, previous Stroke, Vascular disease, Age 65 to 74 years, Sex category] score  652; 86.1%); 13.9% had moderate risk (CHA2DS2-VASc = 1). Overall, 79.9% received oral anticoagulants, of whom 47.6% received NOAC and 32.3% vitamin K antagonists (VKA); 12.1% received antiplatelet agents; 7.8% received no antithrombotic treatment. For comparison, the proportion of phase 1 patients (of N = 1,063 all eligible) prescribed VKA was 32.8%, acetylsalicylic acid 41.7%, and no therapy 20.2%. In Europe in phase 2, treatment with NOAC was more common than VKA (52.3% and 37.8%, respectively); 6.0% of patients received antiplatelet treatment; and 3.8% received no antithrombotic treatment. In North America, 52.1%, 26.2%, and 14.0% of patients received NOAC, VKA, and antiplatelet drugs, respectively; 7.5% received no antithrombotic treatment. NOAC use was less common in Asia (27.7%), where 27.5% of patients received VKA, 25.0% antiplatelet drugs, and 19.8% no antithrombotic treatment. Conclusions The baseline data from GLORIA-AF phase 2 demonstrate that in newly diagnosed nonvalvular atrial fibrillation patients, NOAC have been highly adopted into practice, becoming more frequently prescribed than VKA in Europe and North America. Worldwide, however, a large proportion of patients remain undertreated, particularly in Asia and North America. (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients With Atrial Fibrillation [GLORIA-AF]; NCT01468701

Nanocompósitos de matriz polimérica do tipo SIO2/ polímero e Cds/ Polímero

Mestrado em Ciência e Engenharia de MateriaisO principal objectivo desta dissertação foi estudar novas perspectivas na preparação de nanocompósitos de matriz polimérica, através da síntese e caracterização de nanomateriais do tipo SiO2/ polímero e CdS/ polímero. O primeiro capítulo consiste numa revisão bibliográfica, com destaque para os principais tópicos discutidos ao longo da tese. São efectuadas algumas considerações sobre a utilização de nanopartículas inorgânicas como cargas, e sobre os aspectos mais relevantes da aplicação de polímeros como matrizes. São ainda descritas, algumas estratégias utilizadas para compatibilizar estes componentes. A revisão é concluída com uma breve descrição das metodologias aplicadas na preparação de nanocompósitos de matriz polimérica. No segundo capítulo apresenta-se a síntese e caracterização das cargas inorgânicas. Seguindo métodos descritos na literatura, foram preparadas nanopartículas de SiO2, esféricas e sob a forma de fibras ocas, nanocristais de CdS e compósitos inorgânicos do tipo SiO2@CdS. Estes últimos, foram sujeitos a um tratamento superficial orgânico com TOPO e ainda com SiO2. Para os materiais tratados com TOPO verificou-se uma melhoria das suas propriedades ópticas, nomeadamente ao nível da fotoluminescência à temperatura ambiente. No terceiro e quarto capítulos, são apresentados os nanocompósitos do tipo SiO2/ polímero, que foram sintetizados por polimerização in situ de matrizes semicristalinas (poliamidas e poliuretanos), e amorfas (poli(estireno)). A sua caracterização foi efectuada por espectroscopia de IV, SEM, TEM, TGA e DSC. Os nanocompósitos de matriz semicristalina foram preparados por polimerização por etapas. No caso das poliamidas, foi investigada a influência das cargas de SiO2 com diferentes morfologias e tratamentos de superfície, no processos de fusão e cristalização da matriz. Os materiais de matriz amorfa foram preparados por polimerização radicalar em emulsão e dispersão. Neste caso o estudo incidiu sobre a morfologia das partículas dos nanocompósitos, nas possíveis condições experimentais que a determinam e na influência destas sobre as propriedades térmicas do nanocompósito. Por fim descreve-se no quinto capítulo a síntese e caracterização dos nanocompósitos do tipo CdS/ polímero. Estes materiais foram preparados por polimerização radicalar em solução, na presença de nanocristais de CdS, e compósitos inorgânicos do tipo SiO2@CdS. A inserção das cargas na matriz promoveu as suas propriedades de fotoluminescência à temperatura ambiente. Foram ainda avaliadas as propriedades térmicas de algumas amostras representativas. Neste trabalho foram preparados uma série de novos nanocompósitos de matriz polimérica, que fazem antever futuras aplicações tecnológicas. Foram ainda estabelecidos novos caminhos para a compreensão dos mecanismos de formação de materiais híbridos, e das interacções que ocorrem ao nível das interfaces de natureza orgânica/ inorgânica.The aim of this thesis was to study new methods for the preparation of polymer based nanocomposites, through the synthesis and characterisation of SiO2/polymer and CdS/ polymer nanomaterials. The first chapter consists in an introduction to the aim topics that are discussed in the thesis as well as a literature review. Some considerations are made regarding the use of inorganic nanoparticles as fillers, and to the methods used to modify the inorganic materials surface in order to make them more compatible with the organic nature of polymeric matrices. In this introduction some relevant aspects of the use of polymers as matrices are reported, and a brief review of the polymerisation methods to be used in the nanocomposites preparation is given. The second chapter is devoted to the preparation and characterisation of the fillers. Following methods previously described on the literature, SiO2 nanoparticles with spherical and hollow fibres morphologies, CdS nanocristalites and SiO2@CdS inorganic composites were prepared. The last were organically treated with TOPO and also with SiO2. It was concluded that the TOPO capping results in improved room temperature photoluminescence properties. In the third and fourth chapters, the synthesis and characterisation of SiO2/ polymer nanocomposites is discussed. Using several in situ polymerisation techniques semi-crystalline (polyurethanes and polyamides) and amorphous (poly(styrene)) matrices were prepared. The materials were characterised by FTIR spectroscopy, TEM and SEM, TGA and DSC analysis. The semicrystalline polymeric matrix nanocomposites were prepared by steppolymerisation. In the case of the polyamide based nanocomposites the influence of the SIO2 nanoparticles on the melting and crystallization behaviour of the matrices is discussed. As regards the amorphous matrix nanocomposites these were prepared by radical emulsion and dispersion polymerisation. The morphology of the nanocomposite particles is discussed in light of changes in experimental conditions, and its possible influence on thermal properties. Finally, the chapter five is concerned with CdS/ polymer nanocomposites prepared by in situ polymerisation in the presence of CdS nanocrystals, and SiO2@CdS inorganic composites. TOPO capping results in higher affinity of the fillers to the matrix, and its insertion on the matrices promotes their optical properties, namely room temperature photoluminescence. The thermal properties of some representative samples were also studied. In this work a wide range of novel polymer based nanocomposites were prepared. This study showed that nanomaterials have unique properties that can anticipate potential technologic applications. Furthermore, new routes have been opened to the understanding of the mechanisms of nanocomposites formation, as well as the nature of interactions between organic/ inorganic interfaces

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved

Brazilian Flora 2020: Leveraging the power of a collaborative scientific network

International audienceThe shortage of reliable primary taxonomic data limits the description of biological taxa and the understanding of biodiversity patterns and processes, complicating biogeographical, ecological, and evolutionary studies. This deficit creates a significant taxonomic impediment to biodiversity research and conservation planning. The taxonomic impediment and the biodiversity crisis are widely recognized, highlighting the urgent need for reliable taxonomic data. Over the past decade, numerous countries worldwide have devoted considerable effort to Target 1 of the Global Strategy for Plant Conservation (GSPC), which called for the preparation of a working list of all known plant species by 2010 and an online world Flora by 2020. Brazil is a megadiverse country, home to more of the world's known plant species than any other country. Despite that, Flora Brasiliensis, concluded in 1906, was the last comprehensive treatment of the Brazilian flora. The lack of accurate estimates of the number of species of algae, fungi, and plants occurring in Brazil contributes to the prevailing taxonomic impediment and delays progress towards the GSPC targets. Over the past 12 years, a legion of taxonomists motivated to meet Target 1 of the GSPC, worked together to gather and integrate knowledge on the algal, plant, and fungal diversity of Brazil. Overall, a team of about 980 taxonomists joined efforts in a highly collaborative project that used cybertaxonomy to prepare an updated Flora of Brazil, showing the power of scientific collaboration to reach ambitious goals. This paper presents an overview of the Brazilian Flora 2020 and provides taxonomic and spatial updates on the algae, fungi, and plants found in one of the world's most biodiverse countries. We further identify collection gaps and summarize future goals that extend beyond 2020. Our results show that Brazil is home to 46,975 native species of algae, fungi, and plants, of which 19,669 are endemic to the country. The data compiled to date suggests that the Atlantic Rainforest might be the most diverse Brazilian domain for all plant groups except gymnosperms, which are most diverse in the Amazon. However, scientific knowledge of Brazilian diversity is still unequally distributed, with the Atlantic Rainforest and the Cerrado being the most intensively sampled and studied biomes in the country. In times of “scientific reductionism”, with botanical and mycological sciences suffering pervasive depreciation in recent decades, the first online Flora of Brazil 2020 significantly enhanced the quality and quantity of taxonomic data available for algae, fungi, and plants from Brazil. This project also made all the information freely available online, providing a firm foundation for future research and for the management, conservation, and sustainable use of the Brazilian funga and flora

Correction to: Comparative effectiveness and safety of non-vitamin K antagonists for atrial fibrillation in clinical practice: GLORIA-AF Registry

International audienceIn this article, the name of the GLORIA-AF investigator Anastasios Kollias was given incorrectly as Athanasios Kollias in the Acknowledgements. The original article has been corrected

Patterns of oral anticoagulant use and outcomes in Asian patients with atrial fibrillation: a post-hoc analysis from the GLORIA-AF Registry

Background: Previous studies suggested potential ethnic differences in the management and outcomes of atrial fibrillation (AF). We aim to analyse oral anticoagulant (OAC) prescription, discontinuation, and risk of adverse outcomes in Asian patients with AF, using data from a global prospective cohort study. Methods: From the GLORIA-AF Registry Phase II-III (November 2011-December 2014 for Phase II, and January 2014-December 2016 for Phase III), we analysed patients according to their self-reported ethnicity (Asian vs. non-Asian), as well as according to Asian subgroups (Chinese, Japanese, Korean and other Asian). Logistic regression was used to analyse OAC prescription, while the risk of OAC discontinuation and adverse outcomes were analysed through Cox-regression model. Our primary outcome was the composite of all-cause death and major adverse cardiovascular events (MACE). The original studies were registered with ClinicalTrials.gov, NCT01468701, NCT01671007, and NCT01937377. Findings: 34,421 patients were included (70.0 ± 10.5 years, 45.1% females, 6900 (20.0%) Asian: 3829 (55.5%) Chinese, 814 (11.8%) Japanese, 1964 (28.5%) Korean and 293 (4.2%) other Asian). Most of the Asian patients were recruited in Asia (n = 6701, 97.1%), while non-Asian patients were mainly recruited in Europe (n = 15,449, 56.1%) and North America (n = 8378, 30.4%). Compared to non-Asian individuals, prescription of OAC and non-vitamin K antagonist oral anticoagulant (NOAC) was lower in Asian patients (Odds Ratio [OR] and 95% Confidence Intervals (CI): 0.23 [0.22-0.25] and 0.66 [0.61-0.71], respectively), but higher in the Japanese subgroup. Asian ethnicity was also associated with higher risk of OAC discontinuation (Hazard Ratio [HR] and [95% CI]: 1.79 [1.67-1.92]), and lower risk of the primary composite outcome (HR [95% CI]: 0.86 [0.76-0.96]). Among the exploratory secondary outcomes, Asian ethnicity was associated with higher risks of thromboembolism and intracranial haemorrhage, and lower risk of major bleeding. Interpretation: Our results showed that Asian patients with AF showed suboptimal thromboembolic risk management and a specific risk profile of adverse outcomes; these differences may also reflect differences in country-specific factors. Ensuring integrated and appropriate treatment of these patients is crucial to improve their prognosis. Funding: The GLORIA-AF Registry was funded by Boehringer Ingelheim GmbH