Melanosomes at a glance

Melanosomes, the pigment granules that provide tissues with colour and photoprotection, are the cellular site of synthesis, storage and transport of melanin pigments. They are synthesised in mammalian skin melanocytes, in choroidal melanocytes and retinal pigment epithelial (RPE) cells in the eye, and in melanophores (a class of pigment-containing cells) in lower vertebrates. The precise fate and functions of melanosomes vary according to cell type – epidermal melanocytes supply neighbouring keratinocytes with melanosomes, which results in the pigmentation of skin and hair, whereas pigment granules are retained intracellularly in RPE cells and choroidal melanocytes. In lower vertebrates, the reversible aggregation and dispersion of melanosomes throughout the melanophore enables rapid colour change and adaptation to the environment

Red mud-based geopolymers with tailored alkali diffusion properties and pH buffering ability

This study develop novel porous red mud (RM) based geopolymers and evaluates their potential to ensure prolonged pH control. Several properties of the novel geopolymers were examined including buffering ability, alkalis leaching behaviour, mineralogical composition, microstructure and physical properties. Two experimental plans were defined to evaluate the influence of porosity and RM content on those properties. The pH values of the eluted water and geopolymers OH ions leaching have been determined over time showing that total OH ions and the leaching rate can be tailored by controlling the geopolymers porous structure and the availability of free alkaline species. The lower pH gradient over 28th d (1.64 pH units) was achieved by combining a 0.025 wt% pore forming agent (aluminium powder) with 45 wt% MK replacement by red mud. A high and prolonged buffer capacity was accomplished, proving that red mud-based geopolymers have potential to be applied as pH buffering material.This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT Ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement.info:eu-repo/semantics/publishedVersio

Selection of novel geopolymeric mortars for sustainable construction applications using fuzzy topsis approach

Construction is recognized as one of the most polluting and energy consuming industries worldwide, especially in developing countries. Therefore, Research and Development (R&D) of novel manufacturing technologies and green construction materials is becoming extremely compelling. This study aims at evaluating the reuse of various wastes, originated in the Kraft pulp-paper industry, as raw materials in the manufacture of novel geopolymeric (GP) mortars whose properties fundamentally depend on the target application (e.g., insulating panel, partition wall, structural element, furnishing, etc.). Five different wastes were reused as filler: Two typologies of Biomass Fly Ash, calcareous sludge, grits, and dregs. The produced samples were characterized and a multi criteria analysis, able to take into account not only the engineering properties, but also the environmental and economic aspects, has been implemented. The criteria weights were evaluated using the Delphi methodology. The fuzzy Topsis approach has been used to consider the intrinsic uncertainty related to unconventional materials, as the produced GP-mortars. The computational analysis showed that adding the considered industrial wastes as filler is strongly recommended to improve the performance of materials intended for structural applications in construction. The results revealed that the formulations containing 5 wt.% of calcareous sludge, grits, and dregs and the one containing 7.5 wt.% of calcareous sludge, grits, dregs, and Biomass Fly Ash-1 have emerged as the best alternatives. Furthermore, it resulted that the Biomass Fly Ash-2 negatively influences the structural performance and relative rank of the material. Finally, this case study clearly shows that the fuzzy Topsis multi-criteria analysis represents a valuable and easy tool to investigate construction materials (either traditional and unconventional) when an intrinsic uncertainty is related to the measurement of the quantitative and qualitative characteristics

Educação e Formação

Conhecer para agir: contributos das ciências sociais para o Livro Branco da Juventude

In vitro inhibition of linoleic acid peroxidation by primary S-nitrosothiols

Nitric oxide ( NO) is an effective chain-breaking antioxidant in the inhibition of lipid peroxidation and circulates in vivo mainly as primary S-nitrosothiols (RSNOs). In this work, the in vitro peroxidation of linoleic acid-SDS comicelles (LA-SDS) catalyzed by soybean lipoxygenase (SLO) and FeII ions was monitored in the presence and absence of three primary RSNOs: S-nitrosocysteine, S-nitroso-N-acetylcysteyne and S-nitrosoglutathione. Kinetic measurements based on the formation of conjugated double bonds and fluorescent oxidized LA-lysine adducts, showed that RSNOs are more potent antioxidants than their corresponding free thiols (RSHs) in equimolar conditions. These results are consistent with the blocking of LA-SDS peroxidation by RSNOs through the inactivation of peroxyl/alkoxyl (LOO /LO ) radicals, leading to nitrogen-containing products of oxidized LA, which release free NO. These results indicate that endogenous RSNOs may play a major role in the blocking of lipid peroxidation in vivo, through the primary inactivation of alkoxyl/peroxyl radicals and also of preformed lipid hydroperoxides.O óxido nítrico ( NO) é um antioxidante efetivo na inibição da peroxidação lipídica e circula in vivo principalmente como S-nitrosotióis primários (RSNOs). Neste trabalho, a peroxidação in vitro de comicelas do ácido linileico-SDS (LA-SDS) catalisada por lipoxigenase de soja (SLO) e íons FeII foi monitorada na presença e na ausência de três RSNOs: S-nitrosocisteína, S-nitroso-N-acetilcisteína e S-nitrosoglutationa. Medidas cinéticas baseadas na formação de duplas ligações conjugadas e adutos fluorescentes de lisina-La oxidado mostraram que os RSNOs são antioxidantes mais potentes que seus tióis livres (RSHs) correspondentes em condições equimolares. Esses resultados são consistentes com o bloqueio da peroxidação de LA-SDS por RSNOs através da inativação dos radicais peroxila/alcoxila (LOO /LO ), levando a produtos nitrogenados do LA oxidado, os quais liberam NO. Esses resultados indicam que os RSNOs endógenos podem desempenhar um papel importante no bloqueio da peroxidação lipídica in vivo, através da inativação primária de radicais alcoxila/peroxila bem como de hidroperóxidos lipídicos pré-formados.18851895Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Correlates of changes in BMI of children from the Azores islands

Objective: To model changes in body mass index (BMI), including its stability, and to investigate the association between physical activity, 1-mile run/walk and levels of gross motor coordination and BMI during 5 consecutive years. Design: A longitudinal study of children 6 years of age at baseline followed at annual intervals over 5 years. Subjects: A total of 285 children (143 boys and 142 girls) were enrolled in grade 1 (age 6 years) and followed through grade 5 (age 10 years). Measurements: BMI was recorded and physical activity was assessed by questionnaire, aerobic fitness was evaluated with the 1-mile run/walk and gross motor coordination was measured with the KTK test battery (Korperkoordination test fur Kinder). Multilevel modelling techniques were for the primary analysis. Results: Changes in BMI showed similar curvilinear trends in boys and girls, with ample inter-individual crossing trajectories that is, low tracking. Longitudinal changes in physical activity (PA) and aerobic fitness were not significantly associated with BMI-changes during the 5 years. Children who were more proficient in their motor coordination showed lower values of BMI during the 5 years. Conclusions: BMI trajectories of both boys and girls show low tracking of BMI-values. Considerable inter-individual variation exists both in baseline BMI-values and changes (velocity and acceleration) over time. PA and fitness were not associated with BMI-changes, but gross motor function was negatively associated with BMI-changes. No gender-specific associations were found. If confirmed in other populations these observations could be translated in the promotion of physical activities that improve gross motor function in children aged 6-10 years. This seems to be of major importance for the physical education curriculum of primary school children

To practice or not to practice? Designing higher education curriculum to boost employability

One important dimension of Higher education curriculum design pertains to the inclusion of internships in study programmes. These have been generally conceptualized as learning experiences capable of bridging theoretical knowledge and hands-on experiences. The underlying pedagogical relevance is based on the premise that internships create the possibility of contextualized learning, fostering both professional growth and students’ self-esteem and pro-activity (Little, 2006). Interns are provided with the opportunity of early networking, as they enrol in practical activities and professionally interact with other people, besides their academic teachers and their graduate colleagues (Alpert, Heaney, & Kuhn, 2009; Weible, 2009). Research concerning internships has extensively reported the overwhelming positive effect of internships. Nevertheless, a more recent trend in literature has argued that little has been said concerning the relationship between internships and graduate employment or employability. Wilton (2012), for example, argues that more needs to be understood about the characteristics and specificities of internships and the extent to which such characteristics are capable of overcoming the current concern over the increase of graduates’ unemployment rates. Research conducted on the Portuguese case based on a database of 1,168 study programmes of first cycle degrees sough to redress this gap. Besides demonstrating that study programmes which include internships (cooperative education) tend to generate lower levels of unemployment than those that do not include internships, this research has suggested that the nature and structure of internships significantly impacts on graduate unemployment rates. In specific, mandatory internships tend to outperform their optional counterpart in reducing graduate unemployment levels. Moreover, thin sandwich courses also seem to be more beneficial than thick sandwich courses, suggesting that expanding and diversifying internships throughout the curriculum can reduce graduate unemployment rates. These results strongly suggest that it is not (only) the internship learning experience per se that makes the difference considering graduate employability, but (also) the way those internship experiences are organized along the study programme. This poster is, thus, focused on the nature and structure of internships, assessing their implications for higher education curriculum design. It does so by exploring the perspectives of the main stakeholders involved in internships regarding their motivations; required efforts; and expected outcomes. Empirically, the poster is based on the content analysis of semi-structured individual interviews to units coordinators and also focus groups conducted with coordinators of study programmes; internship supervisors (both academics and employers); and also interns. Qualitative analysis has been sustained by the main learning models traditionally used in research on work-based learning and aims at identifying a set of principles related with internships design, and modes of embedding them along an entire course, which may contribute to the development of graduates’ employability. Reported findings may constitute an important primer for reflection on the design of pedagogical strategies that maximize the contextual learning outputs of internships in a more systematic way, being particularly relevant for leading academics, namely those involved in curriculum design

Numerical simulation of strongly nonlinear and dispersive waves using a Green-Naghdi model

We investigate here the ability of a Green-Naghdi model to reproduce strongly nonlinear and dispersive wave propagation. We test in particular the behavior of the new hybrid finite-volume and finite-difference splitting approach recently developed by the authors and collaborators on the challenging benchmark of waves propagating over a submerged bar. Such a configuration requires a model with very good dispersive properties, because of the high-order harmonics generated by topography-induced nonlinear interactions. We thus depart from the aforementioned work and choose to use a new Green-Naghdi system with improved frequency dispersion characteristics. The absence of dry areas also allows us to improve the treatment of the hyperbolic part of the equations. This leads to very satisfying results for the demanding benchmarks under consideration

Physical Activity in Rural African School-Aged Children and Adolescents

In industrialized countries, reduced levels of physical activity (PA) associated with increased prevalence of the so-called “hypokinetic diseases” stimulates the interest in research in PA and its correlate