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Recent experimental and theoretical studies have shown that a La-H system displays remarkable superconducting properties, and it is also possible to improve the superconducting state by introducing other elements into this system. In this study, we systematically investigated the crystal structures and physical properties of an H–S–La system by using first-principles calculations combined with the CALYPSO structure exploration technique. We predicted four stable stoichiometries containing H2SLa, H3SLa, H4Sla, and H6SLa. These compounds undergo a series of phase transitions under 50–300 GPa. The bonding characters and electronic properties were calculated. It was found that Cm-H2SLa, C2/c-H2SLa, and Cmcm-H6SLa exhibit good metallic nature, which stimulates us to further study their superconducting properties. The calculated superconducting transition temperatures (Tc) of Cm-H2SLa, C2/c-H2Sla, and Cmcm-H6SLa are 15.0 K at 200 GPa, 6.9 K at 300 GPa, and 23.6 K at 300 GPa, respectively. [ABSTRACT FROM AUTHOR]

This research described the heterogeneous reactions of persulfate with different particle sizes of zero-valent iron (including 1 mm-ZVI,150 μm-ZVI,50 nm-ZVI) for degradation of acid orange 7(AO7) , and studied the kinetics and intermediate products of AO7 under these systems. The results demonstrated that these three types of ZVI were efficient in promoting the degradation of AO7, the degradation efficiencies of AO7 were 43% , 97% , and 100% within 90 min respectively, in the 1 mm-ZVI,150 μm-ZVI and 50 nm- ZVI systems, respectively. With the results of kinetic fitting models, the pseudo first-order kinetics exhibited better fitting results in the 1 mm-ZVI,150 μm-ZVI systems, while the second-order kinetics exhibited better fitting results in the 50 nm-ZVI system. And the different ZVI types exhibited difference on the AO7 degradation rate constant, which ranged as 50 nm-ZVI > 150 μm-ZVI > 1 mm-ZVI. The iron corrosion products coating on the ZVI after reaction were composed of α-Fe2 O3 and some Fe3O4 in the 1 mm-ZVI system while that consisted of Fe3O4 and α-Fe2O3, FeOOH respectively, in thel50 μm-ZVI and 50 nm-ZVI systems,. Which were identified by scanning electron microscope (SEM) with energy dispersive spectrometer (EDS) and Raman spectroscopy. Some intermediate products, including 2-naphthalenol, 2-methylphenol, 4-ethyl- 3-methyl-phenol, isoindole- 1,3-dione and phthalic acid et al. were identified by GC/MS measurement. Both UV-vis absorbance spectra and GC/MS determination indicated that there was difference in degradation paths of AO7 between the three systems.