Browsing by Issue Date, starting with "2023-01-03"
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- Potential pathogenic and opportunistic oral bacteria in early life: the role of maternal factors in a portuguese populationPublication . Fernandes, Mariana; Azevedo, Maria João; Campos, Carla; Ferreira, Ana Filipa; Azevedo, Álvaro; Falcão-Pires, Inês; Zaura, Egija; Ramalho, Carla; Campos, Joana; Sampaio-Maia, BeneditaIn early life, maternal factors are of the utmost relevance for oral microbiome acquisition and maturation. Therefore, our study explored the impact of maternal factors, such as saliva and breastmilk colonization, cardiovascular risk factors (CRF), type of delivery, oral health, and caregiving habits on the prevalence of potential pathogenic and opportunistic oral bacteria in early life. A total of 26 healthy mothers, 23 mothers with CRF, and their 50 children were included and samples (child’s oral swabs, mother’s saliva, and breastmilk) were collected 4 to 12 weeks after delivery and inoculated in selective and differential media for detection of non-fastidious Gram-negative and Gram-positive bacteria to isolate potential pathogenic and opportunistic bacteria identified by MALDI-TOF MS (414 isolates). Within mother–child dyads, the same species were identified in 86% of the pairs and potential pathogenic microorganisms from the Staphylococcaceae and Enterobacteriaceae families were found to be statistically significantly concordant between mother–child samples, particularly in the healthy group. Staphylococcus saprophyticus and Stenotrophomonas maltophilia oral colonization in mother–child pairs were associated with the presence of CRF. Breastfeeding was related to the early life oral colonization of Staphylococcus epidermidis in children from healthy mothers and C-section was associated with higher diversity of pathogens, independent of cardiovascular status (p = 0.05). This study reveals the presence of potential oral opportunistic and pathogenic bacteria in early life and highlights the importance of maternal factors in its acquisition.
- The Influence of H Content on the Properties of a-C(W):H CoatingsPublication . Evaristo, Manuel; Fernandes, Filipe; Jeynes, Chris; Cavaleiro, AlbanoDiamond-like-carbon “DLC” coatings can be deposited in many different ways, giving a large range of material properties suitable for many different types of applications. Hydrogen content significantly influences the mechanical properties and the tribological behavior of DLC coatings, but its determination requires techniques that are not available in many research centers. Thus, it is important to find alternative indirect techniques, such as Raman spectroscopy or nanoindentation (hardness measurements), which can give comparative and indicative values of the H contents in the coatings, particularly when depositions with a reactive gas flow are being studied. In this work, “DLC” composite coatings with varying H content were deposited via Physical Vapor Deposition (PVD) magnetron sputtering in a reactive atmosphere (Ar + CH4). An Ion Beam Analysis was used to determine the elemental depth profile across the coating thickness (giving both average C:W:H ratios and film density when combined with profilometer measurements of film thickness). The hardness was evaluated with nanoindentation, and a decrease from 16 to 6 GPa (and a decrease in the film density by a factor of two) with an increasing CH4 flow was observed. Then, the hardness and Raman results were correlated with the H content in the coatings, showing that these indirect methods can be used to find if there are variations in the H content with the increase in the CH4 flow. Finally, the adhesion and tribological performance of the coatings were evaluated. No significant differences were found in the adhesion as a function of the H content. The tribological properties presented a slight improving trend with the increase in the H content with a decrease in the wear rate and friction.