METHODS: Four groups [WMTA, RMPC, fast-set WMTA (FS-WMTA) and fast-set RMPC (FS-RMPC)] were prepared. Initial setting time was evaluated using Vicat apparatus. The pH was measured at seven-day intervals. For discolouration potential, cements were packed in the pulp chamber of 46 extracted maxillary incisors. Spectrophotometric readings were obtained at seven-day intervals, and the rate of colour change (ΔE) was recorded. For the push-out bond strength testing, cements were applied in 48 sectioned root samples, and the test was performed using universal testing machine at crosshead speed of 0.5 mm/min until bond failure. Statistical analysis was done according to the nature of each group of data using SPSS 26.
RESULTS: Addition of CaCl2.2H2O decreased the initial setting times of both RMPC and WMTA significantly (p<0.05). The pH values of FS-WMTA and FS-RMPC were comparable to their non-accelerated counterparts ranging from 10 to 12. Discolouration effect was more obviously observed with WMTA and FS-WMTA with time compared to RMPC formulations. Push-out bond strength of the two materials also showed an increase with the addition of the accelerator, however, only FS-WMTA showed statistically significant difference compared to WMTA (p<0.05).
CONCLUSION: The addition of CaCl2.2H2O improves the physical and mechanical properties of the newly formulated RMPC and WMTA. The RMPC formulation overcomes the discolouration potential of WMTA. (EEJ-2022-12-155).
Objectives: The main aim of this fundamental investigation is to examine the influence of a two-phase hybrid nanofluid approach on mixed convection characteristics including the consequences of varying Richardson number, number of oscillations, nanoparticle volume fraction, and dimensionless length and dimensionless position of the solid obstacle.
Methods: The migration of composite hybrid nanoparticles due to the nano-scale forces of the Brownian motion and thermophoresis was taken into account. There is an inner block near the middle of the enclosure, which contributes toward the flow, heat, and mass transfer. The top lid cover wall of the enclosure is allowed to move which induces a mixed convection flow. The impact of the migration of hybrid nanoparticles with regard to heat transfer is also conveyed in the conservation of energy. The governing equations are molded into the non-dimensional pattern and then explained using the finite element technique. The effect of various non-dimensional parameters such as the volume fraction of nanoparticles, the wave number of walls, and the Richardson number on the heat transfer and the concentration distribution of nanoparticles are examined. Various case studies for Al2O3-Cu/water hybrid nanofluids are performed.
Results: The results reveal that the temperature gradient could induce a notable concentration variation in the enclosure.
Conclusion: The location of the solid block and undulation of surfaces are valuable in the control of the heat transfer and the concentration distribution of the composite nanoparticles.