Advancing the assessment of pacifier effects with a novel computational method.

BACKGROUND: Numerous studies have demonstrated a high likelihood of malocclusions resulting from non-nutritive sucking. Consequently, quantifying the impact of pacifiers can potentially aid in preventing the development or exacerbation of malocclusions and guide the design of improved performance pacifiers. METHODS: This work proposes and assesses a computational methodology that can effectively gather crucial information and provide more precise data regarding the consequences of non-nutritive pacifier sucking. The computational framework utilized is based on solids4Foam [1, 2], a collection of numerical solvers developed within the OpenFOAM® computational library [3]. The computational model focuses on the palate of a six-month-old baby and incorporates various components such as palate tissues, pacifier and tongue, and considers the negative intraoral pressure generated and the tongue displacement. Different models were tested, each offering varying levels of detail in representing the palate structure. These models range from a simplified approach, with one tissue, to a more intricate representation, involving up to five different tissues, offering a more comprehensive palate model compared to existing literature. RESULTS: The analysis of results involved examining the distribution of stress on the palate surface, as well as the displacement and forces exerted on the dental crowns. By comparing the obtained results, it was possible to evaluate the precision of the approaches previously described in the literature. The findings revealed that the predictions were less accurate when using the simplified model with a single tissue for the palate, which is the most common approach proposed in the literature. In contrast, the results demonstrated that the palate model with the most intricate structure, incorporating five different tissues, yielded distinct outcomes compared to all other combinations. CONCLUSIONS: The computational methodology proposed, employing the most detailed palate model, has demonstrated its effectiveness and necessity in obtaining accurate data on the impact of non-nutritive sucking habits, which are recognized as a primary contributor to the development of dental malocclusions. In the future, this approach could be extended to conduct similar studies encompassing diverse pacifier designs, sizes, and age groups. This would foster the design of innovative pacifiers that mitigate the adverse effects of non-nutritive sucking on orofacial structures.

Analytical and numerical study of the electro-osmotic annular flow of viscoelastic fluids.

In this work we present semi-analytical solutions for the electro-osmotic annular flow of viscoelastic fluids modeled by the Linear and Exponential PTT models. The viscoelastic fluid flows in the axial direction between two concentric cylinders under the combined influences of electrokinetic and pressure forcings. The analysis invokes the Debye-Hückel approximation and includes the limit case of pure electro-osmotic flow. The solution is valid for both no slip and slip velocity at the walls and the chosen slip boundary condition is the linear Navier slip velocity model. The combined effects of fluid rheology, electro-osmotic and pressure gradient forcings on the fluid velocity distribution are also discussed.

Removal of phosphorus from water using active barriers: Al2O3 immobilized on to polyolefins.

Phosphorus is known to contribute to eutrophication of fresh water systems, as generally it is the limiting nutrient controlling algae growth. Laboratory studies were conducted to develop and test active barriers composed of aluminium oxide immobilized on to polyolefins to remove phosphorus from water. For this purpose, flat plates of polyethylene and polyethylene grafted with maleic anhydride were prepared and tested. The adsorption mechanism of phosphorus on to aluminium oxide was described by the Freundlich isotherm. The optimum pH interval for phosphorus removal was between 5.2 and 7.8, which includes the pH of natural waters. The maximum phosphorus removal capacity was around 11.1 microg/cm2 for both active barriers. Both barriers removed more than 90% of phosphorus from a 100 mirog/L solution in a static batch experiment carried out for 90 d. The in situ implementation of the active barriers developed in the present study might be a valuable strategy to sequester phosphate and thus to control eutrophication in natural ecosystems, though further work is required to evaluate possible interferences coming from other substances present in the water.