Structural relationships were studied among ternary Laves phases in the system ZrFe2 -ZrCr2 . Among the phenomena observed was the allotropy in ZrCr 2 , which was shown to exhibit a high temperature modification of the hexagonal C14 structure type close to the melting point and a low temperature modification of the C15 cubic type. In connection with the latter observation was the fact that at 8...

We give a complete classification of the phase portraits in Poincare´ disk for cubic polynomial systemsx˙=1−x−axy2,y˙=−by+axy2, R2 according with values its two parameters and b. These differential systems correspond to Gray-Scott model. Moreover we provide bifurcation diagram parameter plane (a,b) these systems.