Generally, Streptococcus thermophilus ferments sucrose, whereas Lactobacillus bulgaricus fails to utilize this disaccharide. When both sucrose and lactose were added to a basal medium, S. thermophilus fermented both carbon sources, produced sufficient acid to change the color of an acid-base indicator (bromcresol purple), and hence formed yellow colonies. On the same medium, most L. bulgaricus strains grew more slowly, produced less acid, and yielded white colonies. Acid diffusion around the S. thermophilus colonies was localized by incorporation of CaCO3 into the medium. To test the efficacy of this medium when known strains of starters are used, the effect of freezing with liquid nitrogen on mixed cultures of S. thermophilus and L. bulgaricus was studied.

The pseudo-binary (quasi-equilibrium) phase diagram for Zr-based bulk metallic glasses with crystalline in situ precipitates (β phase) has been constructed from high-temperature phase information and chemical composition analysis. The phase evolution was detected in situ by high-energy synchrotron x-ray diffraction followed by Rietveld analysis of the data for volume fraction estimation. The phase diagram delineates phase fields and allows the control of phase fractions. Combined with related previous work by the authors, this diagram offers a unique opportunity to control both the morphology and volume of the dendritic β phase precipitates to enhance the properties of the composites.

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