\frac{dx_{3}}{dt} = \left(1 \cdot k_{15} \cdot 1 / \left(1 + k_{8} / x_{3}^{k_{10}}\right) \cdot k_{4} \cdot x_{3} \cdot \left(\log_{10}(k_{9}) - \log_{10}(x_{3})\right) / \log_{10}(k_{9}) + -1 \cdot k_{15} \cdot k_{5} \cdot x_{1} \cdot x_{3} / \left(k_{11} + x_{1} + x_{3}\right)\right) / k_{15}\\
\frac{dx_{1}}{dt} = \operatorname{piecewise}(k_{1} \cdot x_{1} \cdot x_{3} / \left(k_{3} + x_{1} + x_{3}\right), t \le k_{12}, \left(-\left(k_{6} + k_{2}\right)\right) \cdot x_{1})\\
\frac{dx_{2}}{dt} = \operatorname{piecewise}(0, t \le k_{12}, k_{6} \cdot x_{1} - k_{7} \cdot x_{2})