\frac{dx_{1}}{dt} = \left(1 \cdot k_{9} \cdot k_{1} \cdot \left(1 + \operatorname{piecewise}(\frac{13}{5}, \operatorname{and}\left(t > 10, t < 150\right), 0) + k_{5} \cdot x_{2} / k_{6}^{4} / \left(1 + x_{2} / k_{6}^{4}\right)\right) + -1 \cdot k_{9} \cdot k_{2} \cdot x_{1} \cdot k_{8}\right) / k_{9}\\
\frac{dx_{2}}{dt} = \left(1 \cdot k_{9} \cdot k_{3} \cdot x_{1} \cdot k_{8} + -1 \cdot k_{9} \cdot k_{4} \cdot x_{2} \cdot k_{8}\right) / k_{9}