into forms of energy conservation, $$\dot{\rho}_X+3H(1+w_X^{(e)})\rho_X=0~,$$ $$\dot{\rho}_{dm}+3H(1+w_{dm}^{(e)})\rho_{dm}=0~.$$ By means of the concrete forms of dark energy and dark matter in NGCG scenario, Eqs. (\[de\]) and (\[dm\]), one can obtain $$w_X^{(e)}=w_X+{(\eta-1)w_X(1-\Omega_X^0-\Omega_b^0)a^{3w_X\eta}\over
\Omega_X^0+(1-\Omega_X^0-\Omega_b^0)a^{3w_X\eta}}~,\label{wXeff}$$ $$w_{dm}^{(e)}=-{(\eta-1)w_X\Omega_X^0\over
\Omega_X^0+(1-\Omega_X^0-\Omega_b^0)a^{3w_X\eta}}~.$$

Now we switch to discuss the cosmological evolution. Consider a spatially flat FRW Universe with baryon matter component $\rho_{b}$ and NGCG fluid $\rho_{\rm Ch}$, the Friedmann equation reads $$3M_P^2H^2=\rho_{\rm Ch}+\rho_{b}~,$$ where $M_P$ is the reduced Planck mass. The Friedmann equation can also be expressed as $$H(a)=H_0E(a)~,$$ where $$E(a)=\left\{(1-\Omega_b^0)a^{-3}\left[1-{\Omega_X^0\over
1-\Omega_b^0}(1-a^{-3w_X\eta})\right]^{1/\eta}+\Omega_b^0
a^{-3}\right\}^{1/2}~.$$ Then, the fractional energy densities of various components can be easily obtained $$\Omega_X=\Omega_X^0
E^{-2}a^{-3(1+w_X\eta)}\left[1-{\Omega_X^0\over 1-\Omega_{
b}^0}(1-a^{-3w_X\eta})\right]^{{1\over\eta}-1}~,\label{OmegaX}$$ $$\Omega_{dm}=(1-\Omega_X^0-\Omega_{b}^0)E^{-2}a^{-3}\left[1-{\Omega_X^0\over
1-\Omega_{b}^0}(1-a^{-3w_X\eta})\right]^{{1\over\eta}-1}~,$$ $$\Omega_{b}=\Omega_{b}^0E^{-2}a^{-3}~.$$

So far we see clearly that the NGCG model is totally dual to a coupled dark energy scenario [@IXCDM; @Cai], namely an interacting XCDM parametrization. It is remarkable that the interaction between dark energy and dark matter can be interpreted as arising from the time variation of the mass of dark matter particles. The GCG model is a special case in the NGCG model corresponding to $w_X=-1$, thus the GCG model is actually an interacting $\Lambda$CDM model. Fig.1 and Fig.2 illustrate examples of the density evolution in the NGCG model. The current density parameters used in the plots 