Abstract:In this paper, we study cosmologies containing the reduced modified Chaplygin gas (RMCG) fluid which is reduced from the modified Chaplygin gas p = Aρ − Bρ −α for the value of α = −1/2. In this special case, dark cosmological models can be realized for different values of model parameter A. We investigate the viabilities of these dark cosmological models by discussing the evolutions of cosmological quantities and using the currently available cosmic observations. It is shown that the special RMCG model (A = 0 or A = 1) which unifies the dark matter and dark energy should be abandoned. For A = 1/3, RMCG which unifies the dark energy and dark radiation is the favorite model according to the objective Akaike information criteria. In the case of A < 0, RMCG can achieve the features of the dynamical quintessence and phantom models, where the evolution of the universe is not sensitive to the variation of model parameters.

On the basis of their size effect and structural characteristics, carbon nanomaterials have great application potential in building materials, especially for strengthening and toughening cement-based materials. However, because of the poor dispersant of graphene oxide (GO) in cement-based materials with high-alkalinity and high-calcium content, its application in cement concrete is facing great challenges. Here, a method of self-assembling GO by phenyl polymer to achieve effective dispersion is reported. The good dispersion stability is due to hybridization between the phenyl group of the polymer and GO through noncovalent interactions, so the polymer can be anchored to the surface of the GO sheet and dispersed by steric hindrance of the side chain of poly(ethylene oxide) (PEO). The results show that when the length of the PEO side chain is constant, the phenyl content in the copolymer may not only affect the π−πstacking interaction (from offset face-to-face to edge-to-face) but also significantly affect the dispersion stability of the system. When the molar ratio of phenyl to the PEO side chain is about 2, it shows good dispersibility (i.e., the size of the self-assembled composite is the smallest). This provides reference and enlightenment for regulation of the dispersion stability of GO under severe environmental conditions.

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