Thermal Evolutions to Glass-Ceramics Bearing Calcium Tungstate Crystals in Borate Glasses Doped with Photoluminescent Eu³⁺ Ions

Thermal evolutions of calcium-tungstate-borate glasses were investigated for the development of luminescent glass-ceramics by using Eu3+ dopant in a borate glass matrix with calcium tungstate, which was expected to have a combined character of glass and ceramics. This study revealed that single-phase precipitation of CaWO4 crystals in borate glass matrix was possible by heat-treatment at a temperature higher than glass transition temperature Tg for (100−x) (33CaO-67B2O3)−xCa3WO6 (x = 8−15 mol%). Additionally, the crystallization of CaWO4 was found by Raman spectroscopy due to the formation of W=O double bondings of WO4 tetrahedra in the pristine glass despite starting with the higher calcium content of Ca3WO6. Eu3+ ions were excluded from the CaWO4 crystals and positioned in the borate glass phase as a stable site for them, which provided local environments in higher symmetry around Eu3+ ions

Effects of Medium pH and Preconditioning Treatment on Protein Adsorption on 45S5 Bioactive Glass Surfaces

Protein adsorption on 45S5 bioactive glass (BG, Bioglass) surfaces influences the biocompatibility of Bioglass and the cellular response to the material. The medium pH greatly affects protein adsorption behavior. However, the influence of pH variation on protein adsorption on Bioglass has not been investigated in detail before, although an acidifying pH has been observed in fractured or injured bone tissues. This study investigates how the medium pH (pH 7, 5, and 2) affects protein (serum albumin) adsorption on Bioglass with or without preconditioning in simulated body fluid (SBF). The results show that Bioglass can adsorb a larger amount of bovine serum albumin (BSA) than bioinert glasses at all tested pHs. The BSA adsorption on Bioglass surfaces is pH‐dependent and a larger amount of adsorbed BSA is observed at lower pH (5 and 2). After preconditioning, BSA adsorption is significantly enhanced. However, the trend of pH‐dependent adsorption is attenuated. No significant difference in BSA adsorption is observed at different pHs after preconditioning. The results reveal for the first time the influence of medium pH on protein adsorption on Bioglass with or without preconditioning treatment in SBF, which provides useful information for developing Bioglass based biomedical devices that will be in contact with protein‐containing physiological fluids during applications

Modeling of the effect of tool edge radius on surface generation in elliptical vibration cutting

10.1007/s00170-012-4146-8International Journal of Advanced Manufacturing Technology651-435-42IJAT