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Cheng W.-X.,Chongqing University | Liu C.-L.,Chongqing University | Xie T.-P.,State Key Laboratory of Coal Mine Disaster Dynamics and Control
Gongneng Cailiao/Journal of Functional Materials | Year: 2013

A new type of Pb2+ chromogenic imprinted adsorbent was prepared by sol-gel approach with Pb2+ as the template and dithizone grafting onto the silica gel surface. The adsorbent was characterized by FT-IR and scanning electron microscopy. The adsorption property, chromogenic property and selective recognition ability of the adsorbent were studied by equilibrium-adsorption method. Results showed that the dithizone was coated on the silica gel through hydrogen bond. The chromogenic limit of the printed adsorbent was 10 μmol/L, the relative selectivity coefficient was 250 while Cd2+ existed; the extraction behavior of the Pb2+ was conformed by Langmuir's equation and the enthalpy of adsorption was 66.054 kJ/mol. The adsorption capacity reached 97% in 5 min and it could be used for separation and determination of trace Pb2+ in the waste water. Source


Wang J.-L.,China University of Mining and Technology | Liu G.-J.,Hefei University of Technology | Wang W.-Z.,State Key Laboratory of Coal Mine Disaster Dynamics and Control | Zhang S.-J.,China University of Mining and Technology | Yuan L.-L.,China University of Mining and Technology
Meitan Xuebao/Journal of the China Coal Society | Year: 2013

The shale samples were collected from the Longmaxi Formation of Lower Silurian in southern Sichuan Basin. The pore-fissure structures of shale samples were measured and their characteristics were analyzed in this study. Based on the different superiority distribution of pore-fissure, the structures of pore-fissure was divided into three types: pore-superior distribution, fissure-superior distribution and pore-fissure equipotent distribution. In different conditions of axial compression, confining pressure and gas pressure gradient, the CH4 seepage experiments of some shale samples were carried out in three-dimensional stress field. Also, the effect of effective stress and gas slippage effect on the absolute permeability(K0) of shale were calculated and analyzed. It reveals that the permeability K0 and stress difference have negative exponential correlation on the condition of low pressure gradient. The permeability K0 and pressure gradient also have negative exponential correlation. The permeability K0 attenuates observably as the pressure gradient ranges from 0 to 0.2 MPa. It concludes that the effective stress increase will lead to micro-fissures closing and permeability decreasing. The adverse effect of matrix shrinkage and gas slippage effect coexist in the process of pressure gradient increasing while the contribution of slippage effect to permeability is lower than the adverse effect of matrix shrinkage. The shale permeability is different under the condition of different stresses. The shale permeability itself shows non-uniformity which implicates the difference of its micro-fissures development. Source


Zhang X.,Key Laboratory of Dependable Service Computing | Zhang X.,Chongqing University | Zhang X.,State Key Laboratory of Coal Mine Disaster Dynamics and Control | Qu Y.,Chongqing University | And 3 more authors.
IEEE Transactions on Pattern Analysis and Machine Intelligence | Year: 2015

Scale-space behavior of corners is important for developing an efficient corner detection algorithm. In this paper, we analyze the scale-space behavior with the Laplacian of Gaussian (LoG) operator on a planar curve which constructs Laplacian Scale Space (LSS). The analytical expression of a Laplacian Scale-Space map (LSS map) is obtained, demonstrating the Laplacian Scale-Space behavior of the planar curve corners, based on a newly defined unified corner model. With this formula, some Laplacian Scale-Space behavior is summarized. Although LSS demonstrates some similarities to Curvature Scale Space (CSS), there are still some differences. First, no new extreme points are generated in the LSS. Second, the behavior of different cases of a corner model is consistent and simple. This makes it easy to trace the corner in a scale space. At last, the behavior of LSS is verified in an experiment on a digital curve. © 2015 IEEE. Source


Xie T.,State Key Laboratory of Coal Mine Disaster Dynamics and Control | Xu L.,State Key Laboratory of Coal Mine Disaster Dynamics and Control | Liu C.,Chongqing University
RSC Advances | Year: 2013

Sr-Zn ferrite composites were synthesized by chemical coprecipitation with different sintering process. The composites were characterized by XRD, XPS, IR, VSM, and N2-adsorption. The results revealed that the composites were composed of S-type ZnFe2O4 and M-type SrFe 12O19. Zn2+ ions inserted and occupied the 12k or 2a sites for Fe3+ ions in M-type SrFe12O19. The Zn2+ ions were therefore not on the external surface of the composites. The microwave absorption properties at a frequency range of 0-18 GHz were estimated using the electromagnetic parameters obtained through the agency of microwave vector network analyzer. The microwave absorbing properties of composites were excellently superior to that of the pure SrFe12O 19 or ZnFe2O4 due mainly to the exchange coupling between the hard- and soft-magnetic phases. The synthesis process was found to facilitate mass production for various composite materials, especially the two phases or multiphase composite materials. © 2013 The Royal Society of Chemistry. Source


Xie T.,State Key Laboratory of Coal Mine Disaster Dynamics and Control | Xu L.,State Key Laboratory of Coal Mine Disaster Dynamics and Control | Liu C.,Chongqing University
Powder Technology | Year: 2012

The composites SrCo xFe 12-xO 19(x=0-0.3) were prepared by coprecipitation high-temperature sintering method with low-cost reagents. The structures and properties of SrCo xFe 12-xO 19 were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) techniques. There were hard magnetic phase (SrFe 12O 19) and soft magnetic phase (CoFe 2O 4) in SrCo xFe 12-xO 19(x=0.05-0.3). The saturation magnetization of SrCo xFe 12-xO 19(x=0.3) was larger than those of SrCo xFe 12-xO 19(x≤0.2). The synthesized composites were fit to act as good magnetic substrate of catalysts. © 2012. Source

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