| The kinetics of growth and dissolution of three sparingly soluble calcium containing minerals: the oxalates (CaOx), phosphates (CaP) and carbonates (CaCO3) were studied using the constant composition technique.; First, the influence of macromolecules on CaOx growth and nucleation was studied in an effort to elucidate the mechanisms of renal lithiasis. More than 2/3 of these stones are comprised primarily of calcium oxalate minerals containing an organic matrix. Therefore, the influence of the urinary proteins, osteopontin, OPN and human serum albumin, HSA, on the nucleation and growth of CaOx minerals was investigated. Results showed that OPN is capable of inhibiting CaOx growth by as much as 90%, whereas human serum albumin (∼30%) was much less effective. This was attributed to the numerous contiguous acidic acid residues within the OPN molecule. Interestingly, HSA and OPN proved equally effective at inducing nucleation of CaOx at CaP surfaces.; Next, the different parameters involved in the inhibition of dental enamel dissolution by laser irradiation were investigated and it was shown that inhibition is markedly dependent on pulse duration, lasing fluence (J/cm2) and wavelength. It was also observed that dissolution rates decreased as a function of depth, despite an increasing enamel solubility. This can be interpreted in terms of a combination of diffusion effects as well as the reduction of size of the enamel crystallites which may reach a critical size at which the dissolution is effectively terminated.; Finally, the influence of potential surfactants on the growth of CaCO 3 was investigated as possible inhibitors of industrial scale formation. Sodium dodecyl sulfate, SDS, was shown to effectively inhibit CaCO3 formation at low concentrations and was significantly more effective than the cationic surfactants such as dodecyl trimethyl ammonium bromide and benzalkonium chloride. When present at higher concentrations, it may lead to secondary calcification due to complexation with the Ca2+ ions in solution. The effectiveness of SDS was attributed to both the chelation of Ca 2+ ions, thus lowering the effective driving force, and by surface adsorption, thereby inhibiting step advancement. |
