γ radiation caused graphene defects and increased carrier density

We report on a micro-Raman investigation of inducing defects in mono-layer, hi-layer and tri-layer graphene by γ ray radiation. It is found that the radiation exposure results in two-dimensional （2D） and G band position evolution with the layer number increasing and D and D~ bands rising, suggesting the presence of defects and related crystal lattice deformation in graphene. Bi-layer graphene is more stable than mono- and tri-layer graphene, indicating that the former is a better candidate in the application of radiation environments. Also, the DC electrical property of the mono-layer graphene device shows that the defects increase the carrier density.

BL Lacertae objects and the extragalactic γ-ray background

A tight correlation between γ-ray and radio emission is found for a sample of BL Lacertae （BL Lac） objects detected by the Fermi Gamma-ray Space Telescope （Fermi） and the Energetic Gamma-Ray Experiment Telescope （EGRET）. The γ-ray emission of BL Lac objects exhibits strong variability, and the detection rate of γ-ray BL Lac objects is low, which may be related to the γ-ray duty cycle of BL Lac objects. We estimate the γ-ray duty cycle, δγ ≌ 0.11, for BL Lac objects detected by EGRET and Fermi. Using the empirical relation of γ-ray emission with radio emission and the estimated γ-ray duty cycle δγ, we derive the γ-ray luminosity function （LF） of BL Lac objects from their radio LE Our derived γ-ray LF of BL Lac objects can almost reproduce that calculated with the recently released Fermi bright active galactic nuclei （AGN） sample. Comparison of the derived LF of the γ-ray BL Lac objects in this work with that derived by Abdo et al. （2009a） requires the γ-ray duty cycle of BL Lac objects to be almost luminosity-independent. We find that - 45% of the extragalactic diffuse γ-ray background （EGRB） is contributed by BL Lac objects. Combining the estimate of the quasar contribution to the EGRB in the previous work, we find that 77% of the EGRB is contributed by BL Lac objects and radio quasars.

Radiation-induced one-pot synthesis of grafted covalent organic frameworks

Post-synthetic functionalization of covalent organic frameworks(COFs)is an alternative way to enhance and broaden their properties and potential applications.However,the chemical functionalization of COFs is a great challenge because traditional procedures are often time-and energy-consuming,while the crystallinity of COFs can be damaged under harsh conditions.Here we report the in-situ introduction of functional graft chains onto the skeleton of COFs during the synthesis process through the combination of radiation-induced synthesis and graft polymerization techniques under ^(60)Co gamma-ray radiation.The synthesis and functionalization of COFs are simultaneously accomplished in a chemical system under ambient conditions yielding a large number of different functionalized COFs.The obtained carboxyl-functionalized COFs exhibit excellent radioactive uranium removal capabilities from aqueous solution with fast uptake dynamics,high adsorption capacity,and excellent selectivity over other competing metal ions.