Production and characterization of electrospun composite fibers: confinement of thermosensitive microgels

Materials engineering focuses on the assembly of materials´ properties to design new products with the best performance. By using sub-micrometer size materials in the production of composites, it is possible to obtain objects with properties that none of their compounds show individually. Once three-dimensional materials can be easily customized to obtain desired properties, much interest has been paid to nanostructured poly-mers in order to build biocompatible devices. Over the past years, the thermosensitive microgels have become more common in the framework of bio-materials with potential applicability in therapy and/or diagnostics. In addition, high aspect ratio biopolymers fibers have been produced using the cost-effective method called electrospinning. Taking advantage of both microgels and electrospun fibers, surfaces with enhanced functionalities can be obtained and, therefore employed in a wide range of applications. This dissertation reports on the confinement of stimuli-responsive microgels through the colloidal electro-spinning process. The process mainly depends on the composition, properties and patterning of the precur-sor materials within the polymer jet. Microgels as well as the electrospun non-woven mats were investigated to correlate the starting materials with the final morphology of the composite fibers. PNIPAAm and PNIPAAm/Chitosan thermosensitive microgels with different compositions were obtained via surfactant free emulsion polymerization (SFEP) and characterized in terms of chemical structure, morphology, thermal sta-bility, swelling properties and thermosensitivity. Finally, the colloidal electrospinning method was carried out from spinning solutions composed of the stable microgel dispersions (up to a concentration of about 35 wt. % microgels) and a polymer solution of PEO/water/ethanol mixture acting as fiber template solution. The confinement of microgels was confirmed by Scanning Electron Microscopy (SEM). The electrospinning process was statistically analysed providing the optimum set of parameters aimed to minimize the fiber diameter, which give rise to electrospun nanofibers of PNIPAAm microgels/PEO with a mean fiber diameter of 63 ± 25 nm.

Recensão: C. Cosmen Alonso; M. V. Herráez Ortega; M. P. Gómez-Calcerrada, (coord.), El intercambio artístico entre los reinos hispanos y las cortes europeas en la baja edad media

Recensão de: C. Cosmen Alonso; M. V. Herráez Ortega; M. P. Gómez-Calcerrada, (coord.). 2009. El intercambio artístico entre los reinos hispanos y las cortes europeas en la baja edad media. León: Universidad de León

Damage propagation in composite Materials meso-mechanical models

Composite materials have a complex behavior, which is difficult to predict under different types of loads. In the course of this dissertation a methodology was developed to predict failure and damage propagation of composite material specimens. This methodology uses finite element numerical models created with Ansys and Matlab softwares. The methodology is able to perform an incremental-iterative analysis, which increases, gradually, the load applied to the specimen. Several structural failure phenomena are considered, such as fiber and/or matrix failure, delamination or shear plasticity. Failure criteria based on element stresses were implemented and a procedure to reduce the stiffness of the failed elements was prepared. The material used in this dissertation consist of a spread tow carbon fabric with a 0°/90° arrangement and the main numerical model analyzed is a 26-plies specimen under compression loads. Numerical results were compared with the results of specimens tested experimentally, whose mechanical properties are unknown, knowing only the geometry of the specimen. The material properties of the numerical model were adjusted in the course of this dissertation, in order to find the lowest difference between the numerical and experimental results with an error lower than 5% (it was performed the numerical model identification based on the experimental results).

Metodologias Participativas: Os media e a educação

Este livro reúne experiências e reflexões de académicos e não académicos sobre as potencialidades dos media para envolver e capacitar comunidades. Ao longo destas páginas, encontram-se textos que documentam propostas educativas e cívicas em torno dos media ou refletem sobre as capacidades dos media para trabalhar no seio das comunidades, incluindo as esferas da infância/juventude e/ou dos adultos e seniores. As metodologias participativas têm uma grande tradição em países da América Latina, de África e da Ásia e estão agora a ser mais usadas na Europa, particularmente, em Portugal. Esta inspiração reflete-se nas diferentes geografias que podem ser encontradas nesta obra, desde Reino Unido, Alemanha ou Brasil, até ao Quénia. Este livro está dividido em quatro partes. Uma primeira foca-se no projeto que deu mote ao livro, o RadioActive Europe, dando conta das suas práticas em Portugal e noutros países europeus. De seguida, juntamos experiências comunitárias e participativas nacionais e internacionais e, por fim, expomos vários caminhos de reflexão em torno da literacia e dos media.

How different generations contact and search for brands on social media? Comparing gen X and Y

This research intends to examine if there were significant differences on the brand engagement and on the electronic word of mouth (e-WOM)1 referral intention through Facebook between Generation X and Generation Y (also called millennials). Also, this study intends to examine if there are differences in the motivations that drive these generations to interact with brands through Facebook. Results indicated that Generation Y members consumed more content on Facebook brands’ pages than Generation X. Also, they were more likely to have an e-WOM referral intention as well as being more driven by brand affiliation and opportunity seeking. Finally, currently employed individuals were found to contribute with more content than students. This study fills the gap in the literature by addressing how marketing professionals should market their brand and interact and engage with their customers, based on customers’ generational cohort.

Young adult Brazilian beauty consumers perception of Lancôme and the effectiveness of social media relationhips with local celebrities on their purchase intention

The aim of this research is to evaluate if a premium beauty brand, in this case, Lancôme, can influence positively the purchase intention from Brazilian young adults, between 18 and 29 years old, consumers of beauty products, by initiating a relationship with a local celebrity or “it” girl on social media. This hypothesis has not been tested, and this research is a first attempt of evaluating it. Additionally, the consumer behavior, brand preferences and social media activeness of this age segment in Brazil are further studied as important insights for beauty brands to conquer these consumers. Results did not confirm the positive influence of local celebrities on this age segment’s purchase intention but several suggestions are made for future research to revisit this topic. Furthermore, there is a significant brand love for M.A.C., an international Lancôme competitor, amongst this target, as well as a probable price sensitivity facing premium beauty brands.