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This study takes the mine wall of the isolated mine pillar in the Dongguashan Copper Mine as the research object. Based on the mechanical model of the mine wall under the trapezoidal loading of the backfill, the expressions for calculating the safety factor of the mine wall were derived by considering the load-bearing conditions of the backfill–mine-wall system under different roof-contacted filling rates. On this basis, the variation law of the safety factor of the mine wall with the roof-contacted filling rate was obtained, and the calculation result was verified by a numerical simulation and a field test. The research shows that for the same mine wall width, when the roof-contacted filling rate exceeds 9.53%, the safety factor of the mine wall exhibits a "trapezoidal" variation pattern with the increase in the roof-contacted filling rate. Moreover, the comprehensive benefits of isolated pillar recovery are made more credible by maintaining a wall width of 3 m and a filler jointing rate between 30% and 74.49%. This study analyzes the effect of the roof-contacted filling rate on the stability of the mine wall, which can provide a theoretical basis for mining isolated pillars by the filler method in deep mines. [ABSTRACT FROM AUTHOR]

ZnO/graphene and ZnO/stellerite composite photocatalysts were prepared through a facile hydrothermal-calcination processing with zinc acetate,urea,natural stellerite and graphene.The composition,morphology,specific surface area,pore size distribution and light absorption properties of prepared composites were characterized by scanning electron microscopy (SEM),X-ray diffraction (XRD),nitrogen adsorption/desorption and UV-visible diffused reflectance spectroscopy (UV-vis DRS).It was found that the prepared photocatalysts ZnO/stellerite and ZnO/graphene had wurtzite ZnO phase morphology with ZnO paticle sizes of 22.42 nm and 15.72 nm.SBET of composites were 16.54 m2/g and 35.55 m2/g respectively.3D structure between ZnO and graphene resulted in the response to visible light region,reduced recombination of free charges,and enhanced interface charge transfer.The disinfection action towards Staphylococcus aureus (S.aureus) under solar light showed that the optimal amount of ZnO/graphene was 100 mg/L.ZnO/graphene exhibited significantly enhanced photocatalytic disinfection efficiency than ZnO/stellerite powders,and disinfection rate up to 1.17 h-1 is 1.31 times that of ZnO/stellerite composite.

The biocidal cations of Cu2+ and Zn2+ were hosted on the surfaces and in the cavities of X zeolite via ion exchange. The microstructure and interface properties of the exchanged zeolite X samples were analyzed by XRD, SEM, XPS, and XRF. The as-prepared samples showed excellent antimicrobial activity towards gram-negative bacteria of Escherichia coli and gram-positive bacteria of Staphylococcus aureus. Furthermore, the batch antimicrobial experiments showed that the bacterial disinfection process fitted well with the first order model. The Cu2+-zeolite showed excellent and better antibacterial performance on S. aureus than on E. coli, and the mortalities of E. coli and S. aureus were almost 100% after 1 h with the initial Cu2+-zeolite concentrations of 1000 ppm and 100 ppm, respectively. However, the Zn2+-zeolites were found to be less effective on S. aureus than on E. coli, and the mortalities of E. coli and S. aureus were almost 100% after 1 h with the initial Zn2+-zeolite concentrations of 500 ppm and 1000 ppm, respectively. In addition, the relationships between the apparent rate constant (k) and reagent concentration (C) were also systematically investigated. The present results suggest that the as-prepared samples could be promising antibacterial materials for the efficient disinfection of contaminated water with bacteria. [ABSTRACT FROM AUTHOR]

Due to the controlled release of Ag, silver nanoparticles (AgNPs) not only display excellent anticancer activity but also possess cytotoxicity on normal cells. Up to now, no efficient method has been found to eliminate the side effect. In this study, AgNPs with different morphologies were synthesized and some main factors, i.e., the seed amount, CTAB concentration and temperature were discussed. Histidine (His) was applied to modify three kinds of AgNPs (near nanospheres, short nanorods and long nanorods) prepared by the above controlled synthesis, and the bioactivity of the modified AgNPs on cancer and normal cells was investigated. The results showed that the morphology and particle size of AgNPs had strong dependency on the quantity of seeds and reaction temperature except for CTAB concentration. IR spectra showed that His molecules had linked to AgNPs by coordination between AgNPs and C-N group of the imidazolyl in His. The bioactivity experiments in vitro showed that the cytotoxicity of His-modified AgNPs on HL7702 cells was effectively reduced and the anti-tumor activity against MCF-7 cells was not influenced obviously. The results supported that the His-modified AgNPs possess less cytotoxicity and higher targeting anticancer activity and thus the silver nanomaterials modified by His displayed potential applications for cancer therapies. We also suggested that the possible mechanism on the reduction of the cytotoxicity was that His-modified AgNPs could target cancer cells to decrease the cytotoxicity but affect a little on the viability of normal cells. [ABSTRACT FROM AUTHOR]