Measurement of Solution Composition as an Alternative to Titration for Evaluating the Hydrolytic Resistance of Glass.

The measurement of solution composition is proposed as an alternative to titration to determine titration volume, which is the figure of merit for evaluating the hydrolytic resistance of glass containers for pharmaceutical packaging. In the new method, instead of titrating the sample and blank solutions, their compositions are measured by inductively coupled plasma mass spectrometry, and these compositions are converted to titration volume using a set of coefficients and a simple equation. The coefficients were derived using the well-developed thermodynamic data and models for dilute aqueous solutions, which make it possible to calculate the pH from the solution composition and then simulate a titration as a series of pH calculations as titrant is progressively added to the solution.

Crack nucleation criterion and its application to impact indentation in glasses.

Molecular dynamics (MD) simulations are used to directly observe nucleation of median cracks in oxide glasses under indentation. Indenters with sharp angles can nucleate median cracks in samples with no pre-existing flaws, while indenters with larger indenter angles cannot. Increasing the tip radius increases the critical load for nucleation of the median crack.

Origin of dynamical heterogeneities in calcium aluminosilicate liquids.

We investigate the heterogeneous dynamics of calcium aluminosilicate liquids across both the peraluminous and peralkaline regimes. Using the isoconfigurational ensemble method we find a clear correlation between dynamical heterogeneities and concentration fluctuations. Regions of high dynamic propensity have higher concentrations of both calcium and aluminum, whereas low propensity regions are silica rich.