Selective formation of monodisperse spherical vaterite calcium carbonate (CaCO 3 ) precipitate using glycine (Gly) in a calcium hydroxide (Ca(OH) 2 )-carbon dioxide (CO 2 ) reaction system at room temperature and atmospheric pressure is reported. Crystalline products were examined by scanning electron microscopy, powder X-ray diffraction, Fourier transform infrared spectrometer, Raman spectra and laser particle size analysis. The experimental results suggest that increasing Gly concentration caused inhibition of the nucleation and growth of calcite and promoted the formation of vaterite. By adjusting the content of additive Gly, the crystalline product was almost monodisperse spherical vaterite CaCO 3 . The resulting product had good thermal stability, still keeping its crystal type, spherical shape, and size after being heated above 350°C. Mechanism studies illustrated that the complex effects between Gly and Ca 2+ played the key role in the formation process of monodisperse spherical vaterite CaCO 3 . Further studies indicated that this method might also apply to other reaction systems, such as CaCl 2 -NH 3 ·H 2 O-CO 2 and CaCl 2 -Na 2 CO 3 reaction systems. These studies are paving the way for industrial preparation and further commercial applications of monodisperse spherical vaterite CaCO 3 .

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In the present paper it is shown that the elastic range in the second Piola-Kirchhoff stress space can be chosen in a hyperplane which is through the origin of Lagrangian stress space and perpendicular to the normal of the constraint manifold at the plastic configuration, if the determinate stress response of the elastic-plastic material with simple internal constraints with some condition is correctly chosen, otherwise, it is in general in a hypersurface and the normal flow rule by Il yushin's postulate will have an indeterminate part. The choice of determinate stress response is probable because of its indeterminacy. Therefore the yield function should be a function of the second Piola-Kirchhoff stress lying in the hyperplane so that it is more simple and the back stress as the geometric center of the elastic range in general is inside the elastic range. Finally some examples are concerned.