Three-Cornered Hats is a classical method to obtain the frequency stability of one single atomic clock without more stable frequency standards available. In this paper, the measurement data of three hydrogen masers in a ground station is used to analyze the frequency stability of one single atomic clock. The analysis steps and problems in application of this method are introduced. The negative values of the calculated Allan variance of one clock with averaging time larger than 4000s occur. It probably implies that the hypothesis of uncorrelated clocks is not acceptable, which will be analyzed further.

A series of ZnFe2O4/expanded graphite composites (EG/ZF) were prepared by the chemical precipitation method. The structure, composition and morphology of the as-prepared samples were characterized. Taking methylene blue (MB) as the simulate organic pollutant, the influences of various factors on the decontamination of the as-samples and their reusing performance were researched. The results showed that the decontamination activity of the EG/ZF composite with mass ratio of EG to ZF equal to 0.8 reaches the maximum in the MB solution of pH = 5, and has good performance for repeated use. What’s more, the possible mechanism of decontamination was studied further.