$\epsilon$	Porosity
$\mu$	Dynamic viscosity, ${\mathrm{kg} \mathrm{m}}^{-1}{ \mathrm{s}}^{-1}$
$\sigma$	Local entropy generate rate, ${\mathrm{J} \mathrm{K}}^{-1}{ \mathrm{m}}^{-1}{ \mathrm{s}}^{-1}$
$\xi$	Conversion rate
$\rho$	Density, $\mathrm{kg}\cdot {\mathrm{m}}^{-3}$
$\mathsf{\lambda }$	Covariate variable vector
$\Delta G$	Gibbs free energy change of reaction, ${\mathrm{J} \mathrm{mol}}^{-1}$
$\Delta H$	Enthalpy of reaction, ${\mathrm{J} \mathrm{mol}}^{-1}$