Simple one pot preparation of chemical hydrogels from cellulose dissolved in cold LiOH/urea

In this work, non-derivatized cellulose pulp was dissolved in a cold alkali solution (LiOH/urea) and chemically cross-linked with methylenebisacrylamide (MBA) to form a robust hydrogel with superior water absorption properties. Different cellulose concentrations (i.e., 2, 3 and 4 wt%) and MBA/glucose molar ratios (i.e., 0.26, 0.53 and 1.05) were tested. The cellulose hydrogel cured at 60 °C for 30 min, with a MBA/glucose molar ratio of 1.05, exhibited the highest water swelling capacity absorbing ca. 220 g H2O/g dry hydrogel. Moreover, the data suggest that the cross-linking occurs via a basic Michael addition mechanism. This innovative procedure based on the direct dissolution of unmodified cellulose in LiOH/urea followed by MBA cross-linking provides a simple and fast approach to prepare chemically cross-linked non-derivatized high-molecular-weight cellulose hydrogels with superior water uptake capacity.Portuguese Foundation for Science and Technology, FCT, via the projects PTDC/AGR-TEC/4814/2014, PTDC/ASP-SIL/30619/2017 and UIDB/05183/2020, and the research grant IF/01005/2014.info:eu-repo/semantics/publishedVersio

Transient and steady-state shear banding in a lamellar phase as studied by Rheo-NMR

Flow fields and shear-induced structures in the lamellar (L-alpha) phase of the system triethylene glycol mono n-decyl ether (C10E3)/water were investigated by NMR velocimetry, diffusometry, and H-2 NMR spectroscopy. The transformation from multilamellar vesicles (MLVs) to aligned planar lamellae is accompanied by a transient gradient shear banding. A high-shear-rate band of aligned lamellae forms next to the moving inner wall of the cylindrical Couette shear cell while a low-shear-rate band of the initial MLV structure remains close to the outer stationary wall. The band of layers grows at the expense of the band of MLVs until the transformation is completed. This process scales with the applied strain. Wall slip is a characteristic of the MLV state, while aligned layers show no deviation from Newtonian flow. The homogeneous nature of the opposite transformation from well aligned layers to MLVs via an intermediate structure resembling undulated multilamellar cylinders is confirmed. The strain dependence of this transformation appears to be independent of temperature. The shear diagram, which represents the shear-induced structures as a function of temperature and shear rate, contains a transition region between stable layers and stable MLVs. The steady-state structures in the transition region show a continuous change from layer-like at high temperature to MLV-like at lower temperature. These structures are homogeneous on a length scale above a few micrometers

Can We Speak?: Approaching Oral Proficiency in the EFL Classroom

A oralidade tem vindo a ser progressivamente promovida em programas e currículos, tanto nacional como internacionalmente, como um dos grandes objetivos do ensino da língua estrangeira. No entanto, as características únicas desta competência fazem de si a mais difícil de abordar em contextos de sala de aula. Apesar de toda a relevância dada à oralidade, bem como a todos os seus constituintes na maioria dos documentos oficiais nacionais e internacionais, como as novas metas de Inglês para Portugal, as Aprendizagens Essenciais e o Quadro Comum de Referência para as Línguas (QECR), os professores portugueses parecem debater-se para conseguirem aplicar procedimentos adequados para desenvolverem tais competências na sua plenitude. Assim, este projeto inclui uma análise da teoria e da prática do ensino da língua inglesa nas salas de aula portuguesas, considerando a abordagem à oralidade no geral e à inteligibilidade em particular. Na realidade, o conceito de inteligibilidade está hoje firmemente enraizado na área da linguística aplicada como um dos fatores determinantes para explicar o sucesso, ou não, da comunicação entre interlocutores de diferentes origens culturais e linguísticas. Este estudo está dividido em duas partes distintas, uma primeira parte de cariz teórico e uma segunda parte de cariz prático. Nos capítulos da parte 1 são postos criticamente em perspetiva os conceitos globalização, comunicação e mudança, como base para uma reflexão acerca dos fatores históricos e antropológicos mais influentes para a disseminação e estatuto da língua inglesa. O foco é então direcionado para o papel do Inglês na Europa, bem como em Portugal, atendendo aos contextos de ensino-aprendizagem de ambos para irem ao encontro das necessidades linguísticas dos alunos coevos. Numa tentativa de clarificar os complexos desenvolvimentos da língua, este estudo examina os fundamentos que subjazem a conceitos-chave de proficiência linguística em ambiente educacional, assim como as premissas teóricas que os norteiam. Logo, serão igualmente reavaliadas algumas das compartimentações habituais no mundo anglófono, de acordo com a mudança do “centro de gravidade” que está a ocorrer no uso da língua inglesa. Como afirmado, a parte 2 do estudo é eminentemente prática. O plano e o método através dos quais o estudo se desenvolveu são apresentados, detalhando-se a abordagem metodológica da investigação em relação à informação quantitativa e qualitativa recolhida (questionários / observações em sala de aula / entrevistas / gravações áudio). O propósito é perceber o que está a ser feito pelos professores em sala de aula em termos de oralidade e quão inteligíveis são os alunos de inglês do 9º ano de escolaridade. A partir da informação recolhida, é feita uma análise dos resultados mais pertinentes, que por sua vez conduzirá às implicações e conclusão do estudo. Estas duas últimas secções discutem os potenciais efeitos dos resultados obtidos no processo ensino-aprendizagem da oralidade e a sua influência na inteligibilidade dos alunos, enquanto falantes e ouvintes.Speaking has been increasingly promoted in language syllabuses and curriculums, both nationally and internationally, as one of the major aims of foreign language teaching. However, the unique features of this skill make it the most challenging one to address in classroom-based contexts. Despite the conspicuous importance given to speaking and all its subsets in most national and international official documents, new English targets for Portugal, the subject’s core curriculum and the Common European Framework of Reference for Languages (CEFR), Portuguese teachers seem to be at odds with suitable procedures to fully develop them inside the classroom. Thus, this project entails an analysis of the theory and practice of classroom English language teaching (ELT) in Portugal concerned with speaking in general and intelligibility in particular. Indeed, the concept of intelligibility is now firmly established in the field of applied linguistics as one of the key factors in explaining success or otherwise in communication between interlocutors from cultural and linguistic diverse backgrounds. This study is divided in two overarching parts, part 1 is a more theoretical one, whereas part 2 is a more practical one. Throughout the chapters of part 1 globalization, communication and change are critically put into perspective, laying the foundation for a reflection on the most significant historical and anthropological factors for English’s global spread and current status. The focus is then narrowed down to the role of English in Europe and further on in Portugal, bearing in mind the language learning and teaching contexts of these settings to meet the needs of students’ present-day reality. In order to shed greater light on these complex language developments, this study examines the rationale underlying some of the core concepts on educational language proficiency, including their definitions and key characteristics, as well as outlining the theoretical premises on which they are grounded. Thus, traditional divides in the English-speaking world are here reexamined in accordance with the change taking place in the ‘centre of gravity’ of the English language. As stated, part 2 of the study is eminently practical. The design and methods on which the study is carried out are delineated, detailing the research methodological approach of quantitative and qualitative data collection (questionnaires / classroom observations / semi-structured interviews / audio recordings). The goal is to understand what teachers do inside their classrooms in terms of speaking ability, as well as how intelligible 9th grade English students are. From the set of gathered data stems an analysis of the major findings, which in turn lead to the implications and conclusion of the study. These two last sections discuss the potential effect of the findings to the teaching and learning of speaking and its influence on the students’ intelligibility, either as speakers or listeners

Emulsion formation and stabilization by biomolecules: the leading role of cellulose

Emulsion stabilization by native cellulose has been mainly hampered because of its insolubility in water. Chemical modification is normally needed to obtain water-soluble cellulose derivatives. These modified celluloses have been widely used for a range of applications by the food, cosmetic, pharmaceutic, paint and construction industries. In most cases, the modified celluloses are used as rheology modifiers (thickeners) or as emulsifying agents. In the last decade, the structural features of cellulose have been revisited, with particular focus on its structural anisotropy (amphiphilicity) and the molecular interactions leading to its resistance to dissolution. The amphiphilic behavior of native cellulose is evidenced by its capacity to adsorb at the interface between oil and aqueous solvent solutions, thus being capable of stabilizing emulsions. In this overview, the fundamentals of emulsion formation and stabilization by biomolecules are briefly revisited before different aspects around the emerging role of cellulose as emulsion stabilizer are addressed in detail. Particular focus is given to systems stabilized by native cellulose, either molecularly-dissolved or not (Pickering-like effect).Financially support by the Portuguese Foundation for Science and Technology, FCT, via the projects PTDC/AGR-TEC/4814/2014, PTDC/ASP-SIL/30619/2017 and researcher grant IF/01005/2014. RISE Research Institutes of Sweden AB and PERFORM, a competence platform in Formulation Science at RISE, are acknowledged for additional financing. This research has been supported by Treesearch.se.info:eu-repo/semantics/publishedVersio

A Water Pumping Photovoltaic Powered System Based on a Merged DC-DC Sepic-Cuk Converter

Trabalho apresentado em 2019 8th International Conference on Renewable Energy Research and Applications (ICRERA), 3-6 novembro 2019, Brasov, RomeniaThis paper has the purpose to present a non-isolated dual output DC-DC converter for a water pumping photovoltaic powered system. The proposed topology is based in the integration of a traditional Sepic and Cuk converters but requires only a single power semiconductor switch. It is characterized by an extension of the voltage static gain when compared with the classical boost topology and by a reduced voltage stress across the power switch and diodes. The system will be implemented through a classical MPPT algorithm that will control the proposed DC-DC converter. Several simulation and experimental results are also presented in order to confirm the characteristics of the proposed power converter and global water pumping systems.N/

Bidirectional Boost/Buck Quadratic Converter for Distributed Generation Systems with Electrochemical Storage Systems

Trabalho apresentado no 5th IEEE International Conference on Renewable Energy Research and Applications, 20-23 de novembro 2016, Birmingham, Reino UnidoThe increasing number of distributed generation systems using renewable and non-conventional energy sources show the trend of future generation systems. Most of these systems require power electronic converters as an interface between the DC voltage buses and electrochemical storage systems. Such storage systems, like batteries or supercapacitors, usually need bidirectional DC-DC converters to allow their charge or discharge according with necessary operation conditions. In this paper, a non-isolated bidirectional Buck-Boost converter with high voltage gain for electrochemical storage devices used in distributed generation systems is presented. To achieve high voltage gain ratios, the proposed topology presents quadratic characteristics in both step-down (Buck) and step-up (Boost) operation modes. In addition to the wide conversion range, it presents continuous input and output current, reduced charging/discharging ripple and simple control circuitry. All these features allow the energy exchange smoothly and continuously resulting in a longer durability of storage devices. The principle of the operation of the proposed converter in both operation modes, as well as their theoretical analysis will be discussed. The performance of this bidirectional power converter is confirmed through simulation and experimental results.N/

Multimodal chromatography combining steric exclusion and cation exchange as an intermediate downstream step to purify yellow fever virus-like particles

Yellow fever (YF) is an hemorrhagic viral disease transmitted by infected mosquitoes, which is endemic in many African and Central/South American countries. The severe symptoms and the high mortality rate of the disease can have devastating effects in case an outbreak occurs in an area where the population is non-vaccinated. Before the current YF vaccine became available, outbreaks in cities like Barcelona (Spain) and Philadelphia (USA) led to the death of approximately 10% of the population. Recent outbreaks have shown that YF continues to be a major public health threat due to production capability issues and shortage of vaccine stockpiles, which even led to the use of an emergency fractional (1/5) dose in Africa in 2016 and in Brazil in 2018. Yellow fever virus-like particles (VLPs) represent an interesting alternative to develop a new YF vaccine. With the aim of developing an efficient and affordable process to purifiy yellow fever VLPs, in this work we developed a multimodal strategy combining cation exchange (CEX) and steric exclusion chromatography (SXC) under conditions where the product of interest does not bind to the CEX adsorber, whereas many contaminants do. In this way, the product of interest is retained just due to steric exclusion by the polyethylene glycol (PEG) added to the mobile phase. Product desorption can be achieved by decreasing PEG concentration, while contaminants remain bound to the adsorber and are eluted in the regeneration step. To the best of our knowledge, the application of such a multimodal strategy has not been published before. Please click Download on the upper right corner to see the full abstract

Contributos para a implementação de um Centro deExcelência de Combate em Áreas Edificadas (CdECAE) como modelo de formação e treino no Exército Português

O presente trabalho de investigação visa perceber se o modelo do Centro de Excelência de Combate em Áreas Edificadas do Exército, se mantém atualizado para garantir uma formação e treino adequados na vertente do combate em áreas edificadas. Neste trabalho, pretende-se fazer uma reflexão sobre o Combate em Áreas Edificadas e a necessidade de se criar modelos que permitam melhorar o treino e o desenvolvimento de capacidades nesta área específica. Procura-se analisar o conceito de Centro de Excelência de Combate em Áreas Edificadas como modelo sistémico que permite acompanhar a evolução da vertente do combate em áreas edificadas no moderno campo de batalha. Esta investigação rege-se segundo o método científico hipotético-dedutivo, descrito por Raymond Quivy e Luc Van Campenhoudt e segue as sete etapas do procedimento científico defendido pelos mesmos autores. Na etapa da Observação, a amostra foi constituída pelos oficiais que integraram os quatro Módulos de Formação de Combate em Áreas Edificadas, na missão da União Europeia no Uganda com o objetivo de ministrar formação às Forças Armadas da Somália (2010 a 2012). Utilizou-se a entrevista como método de recolha dos dados. Chegou-se à conclusão que o atual modelo do Centro de Excelência de Combate em Áreas Edificadas parece estar atual e garantir uma formação e treino adequados, na vertente específica do combate em áreas edificadas, para unidades de Infantaria, em formação e aprontamento, quer individualmente quer até ao escalão Companhia. Entende-se como principais contributos para a implementação/consolidação deste Centro de Excelência, ao nível da formação, dar mais atenção a determinadas matérias como o Socorrismo de combate e Sapadores. Quanto ao material que existe no Centro, verifica-se que importa melhorar os sistemas de simulação, nomeadamente no treino do tiro. Ao nível das infraestruturas, parece-nos adequado implementar edifícios modulares, criar uma área para rebentamento de explosivos, uma carreira de tiro que permita fazer tiro real de calibre 7,62 mm em várias direções, construir outros edifícios que representem vários tipos de áreas edificadas, e dar mais realismo às infraestruturas já existentes.Abstract This research aims to understand whether the model of the Army’s Centre of Excellence of Urban Operations, keeps up to date to ensure adequate instruction and training in aspects of Fighting In Built-Up Areas. In this work, we intend to make a study of Fighting In Built-Up Areas and the need to create models that allow to improve training and capacity development in this particular area. We seek to analyze the concept of Centre of Excellence for Urban Operations as a systemic model that allows for the evolution of fighting in built-up areas on the modern battlefield. This research applies the hypothetical-deductive scientific method, described by Raymond Quivy and Luc Van Campenhoudt and follows the seven steps of scientific procedure advocated by the same authors. In the Observation step, the sample was composed of officers who joined the four Fighting in Built-up Areas Training Modules, under European Union mission in Uganda to train the Somali Armed Forces, 2010-2012. We used the interview as a method for data collection. It is concluded that the current model of the Centre of Excellence for Urban Operations seems to be up to date and ensures adequate instruction and training in the specific aspect of fighting in built-up areas, for Infantry units, either individually or up to Company level. The main contributions to the implementation of the Centre of Excellence, in training, is to pay more attention to certain matters such as First Aid in combat and Explosives. As for the material, which exists at the centre, is important to improve the simulation systems, including training in shooting. In terms of infrastructure, we must implement modular buildings, create an area for blasting, a firing ground that allows live firing of 7.62 mm rounds in several directions, build other buildings representing several types of built-up areas, and to give more realism to the existing infrastructure

Road Motion Control Electric Vehicle with Speed and Torque Observer

This paper presents an electric vehicle (EV) with two independent rear wheel drives and with an electric differential system. A model of the vehicle dynamic model is presented. The electric differential was implemented assuring that, in straight right trajectory, the two wheels drives roll exactly at same velocity and, in curve, the difference between the two velocities assure a vehicle trajectory. A speed and torque observer for DC motor was also proposed and simulated. Analysis and simulation results of the proposed system are presented.Com o apoio RAADRI

On the development of all-cellulose capsules by vesicle-templated Layer-by-Layer assembly

Polymeric multilayer capsules formed by the Layer-by-Layer (LbL) technique are interesting candidates for the purposes of storage, encapsulation, and release of drugs and biomolecules for pharmaceutical and biomedical applications. In the current study, cellulose-based core-shell particles were developed via the LbL technique alternating two cellulose derivatives, anionic carboxymethylcellulose (CMC), and cationic quaternized hydroxyethylcellulose ethoxylate (QHECE), onto a cationic vesicular template made of didodecyldimethylammonium bromide (DDAB). The obtained capsules were characterized by dynamic light scattering (DLS), ζ potential measurements, and high-resolution scanning electron microscopy (HR-SEM). DLS measurements reveal that the size of the particles can be tuned from a hundred nanometers with a low polydispersity index (deposition of 2 layers) up to micrometer scale (deposition of 6 layers). Upon the deposition of each cellulose derivative, the particle charge is reversed, and pH is observed to considerably affect the process thus demonstrating the electrostatic driving force for LbL deposition. The HR-SEM characterization suggests that the shape of the core-shell particles formed is reminiscent of the spherical vesicle template. The development of biobased nano- and micro-containers by the alternating deposition of oppositely charged cellulose derivatives onto a vesicle template offers several advantages, such as simplicity, reproducibility, biocompatibility, low-cost, mild reaction conditions, and high controllability over particle size and composition of the shell.Portuguese Foundation for Science and Technology, FCT, via the projects PTDC/ASP-SIL/30619/2017, UIDB/05183/2020 and the researcher grant CEECIND/01014/2018info:eu-repo/semantics/publishedVersio