Percorrer por autor "Alves, Miguel"
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- Avaliação dos riscos psicossociais nos Pilotos Aviadores da Força Aérea PortuguesaPublication . Alves, MiguelEste trabalho de investigação tem como objetivo principal avaliar a que fatores de risco psicossocial os Pilotos Aviadores da Força Aérea Portuguesa (FAP) estão sujeitos. A amostra composta por 62 indivíduos corresponde a 33% da população-alvo existente. A recolha de dados foi feita seguindo uma metodologia quantitativa por questionário, com a aplicação da versão média do COPSOQ II. Os indivíduos apresentaram fatores de engagement como a inexistência de comportamentos ofensivos e insegurança laboral. Igualmente observam o trabalho com possibilidades de desenvolvimento, confiança horizontal, espírito positivo da comunidade no local de trabalho e sensação de significado no trabalho. Exigências quantitativas, ritmo de trabalho, exigências emocionais, influência no trabalho, transparência do papel laboral desempenhado, recompensas, conflitos laborais, apoio social de superiores, qualidade de liderança, confiança vertical, justiça e respeito, satisfação no trabalho e conflito trabalho/família são considerados riscos moderados que carecerão de medidas de prevenção. As exigências cognitivas, relacionadas com tomadas de decisão difíceis, atenção necessária e capacidade de propor novas ideias no trabalho, revelaram ser um fator de risco severo, podendo necessitar de ações interventivas nesta área. As contribuições deste estudo reforçam a importância que as pessoas têm numa organização como a FAP. Assim, os investimentos em recursos humanos, financeiros e materiais, na prontidão das aeronaves, implicam que os Pilotos Aviadores se encontrem física e mentalmente na melhor forma para cumprir a missão em excelência. Para isto, é necessário perceber o ambiente psicossocial a que estão sujeitos e consequentemente a que riscos estão mais vulneráveis, de modo a serem prevenidos.
- Optimal nano-silica filler concentration to optimize kinetics, rheology and bonding of self-adhesive compositesPublication . Alves, Miguel; Pereira, Pedro; Silva, Diana C.; Delgado, António H. S.To determine how silica nanoparticle (NanoSi) content modulates polymerization kinetics, dentin bonding, and interfacial adaptation in self-adhesive flowable resin composites (SAFRCs). Five UDMA/PPGDMA/10-MDP SAFRCs containing 0, 2.5, 5, 7.5, or 10 wt% NanoSi were compared to a commercial reference (Vertise Flow, VF). Real-time ATR-FTIR provided t0.5, Rpmax, delay time, and DCmax; viscosity was measured under controlled shear. Shear bond strength (SBS) was tested at 24 h. Masson’s trichrome and environmental SEM (E-SEM) assessed interfaces. Two-way MANOVA examined formulation and exposure time (20 vs 40 s) effects on kinetics; one-way ANOVA analyzed µSBS (ɑ = 0.05). Formulation and time significantly affected the multivariate kinetic response (Wilks’ λ_formulation = 0.1905, p = 0.0099; Wilks’ λ_time = 0.4296, p = 0.0045), with no interaction. NanoSi_2.5 polymerized fastest (Rpmax 3.17 ± 0.43%·s⁻1); NanoSi_5 was slowest (1.61 ± 0.26%·s⁻1). DCmax increased with filler, peaking at NanoSi_10 (78.77 ± 2.64%); extending exposure from 20 to 40 s raised DCmax by 10.23 ± 2.16% without altering kinetics. All pastes were shear-thinning, with viscosity rising monotonically with NanoSi. SBS differed among materials (ANOVA F = 3.14, p = 0.02): VF was highest (8.6 ± 2.2 MPa); NanoSi_0 reached 6.0 ± 1.1 MPa (NS vs VF); NanoSi_2.5–5 clustered lower (~ 3–4 MPa) and NanoSi_7.5 reached the minimum. Trichrome and E-SEM showed thin, continuous interfaces at 0–2.5 wt% and increasing porosity/thin separations at 7.5–10 wt%. Nanosilica altered cure, flow and interfacial quality trade-offs; faster early kinetics and higher final conversion did not translate into higher SBS, emphasizing the need to optimize interfacial wetting/adaptation alongside mechanical parameters in SAFRC design. A formulation window may exist in which flow, cure, and bonding are balanced to enhance the clinical potential of self-adhesive composites.
- Self-adhesive flowable resin composites—Are we going somewhere?Publication . Delgado, António H. S.; Alves, Miguel; Pires, Inês; Ferreira, Marta Nunes; Cuevas-Suárez, Carlos EnriqueObjective: To map laboratory/clinical evidence on self-adhesive flowable resin composites (SAFRCs), tracing their chemical evolution, performance, and behavior, and to identify gaps that must be addressed to drive their optimization. Overview: A comprehensive literature search was performed in PubMed/MEDLINE, Scopus, and LILACS without language restrictions. To date, 11 commercial SAFRCs are available. These contain 5wt%–10 wt% hydrophilic monomers and ≤ 55 vol% fillers, as a flowable option, although susceptible to water sorption and color changes. Functional monomer trends shift from 4-META/GPDM to 10-MDP or phosphate-amide hybrids; meta-analytical and recent laboratory data confirm that μTBS to dentin is extremely low (rarely > 10 MPa). Inefficacy to bond/seal is the main reason for failure. Clinical evidence is scarce and short-term: RCTs suggest that small Class-I restorations survive comparably to controls at ≤ 24 months, but failures are frequent. Emerging strategies such as alternative conditioning, collagen depletion, or incorporation of bio-interactive fillers may improve outcomes. Conclusions: Current SAFRCs simplify placement and reduce technique sensitivity but are constrained by very low bond strengths, poor sealing, and high hygroscopicity. Until chemistry, paste acidity, and smear-layer interaction are co-optimized, their use should remain limited. Future research must couple novel chemical formulations and low-water-uptake matrices while validating performance in adequately powered RCTs.