Determine the circulation of $\displaystyle F(x,y,z) = (z-x)i +(x-y)j + (e^{xyz})k$ around the curve $\displaystyle \alpha $ traveled in a counter-clockwise direction when viewed from the axis OZ, knowing that this curve is the edge of the surface: S1 $\displaystyle x^2+y^2+z^2 = 4; z > 0$