Elastic Modulus Limit of Support Layer in Twin-Block Ballastless Track Based on Train Load Effect

The support layer is an important component of twin-block ballastless track. The modulus of the support layer is an important design parameter and must be carefully solved. We studied the bending stress and deformation of track slab and support layer due to train load using the beam-plate finite element model on elastic foundation. The results show that support layer type has great impact on both support layer deformation and the stress on subgrade, but has little impact on the bending stress of either track slab or support layer. The continuous support layer type, and articulated support layer type with shear transfer device at their ends, are recommended. In order to keep the stress in the support layer less than that in track slab, the modulus of the continuous, unit, and articulated types of support layer （ in unit twin-block ballastless track）, and the support layer in continuous twin-block ballastless track, should not be larger than 15, 22, 20.5 and 5 GPa, respectively. In addition, the modulus of the unit-type support layer should not be more than 20 GPa, to ensure the step in support layer remains less than 1 mm.

Metal–organic-framework derived supporting layers for highly efficient CdSe QDSSCs

Metal–organic-framework(MOF)has been an increasingly hot organic-inorganic hybrid compounds. Here we develop an innovative concept by engineering a supporting layer made of MOF derived carbon materials. The supporting thin layer is prepared by carbonizing zeolitic-imidazole framework(ZIF-67). CdSe quantum dot sensitized TiO_2 nanocrystalline thin film deposited by the method of chemical bath deposition(CBD). The MOF unique microstructure in the support layer builds the electronic highway, which greatly improves the efficiency of the CdSe quantum dot-sensitized solar cells(QDSSCs), and the power conversion efficiency(PCE)of the device was significantly improved from 2.98% to 5.79% via ZIF-67 derived carbon supporting thin layer.

Remediation of Cu and As contaminated water and soil utilizing biochar supported layered double hydroxide:Mechanisms and soil environment altering

Preparing materials for simultaneous remediation of anionic and cationic heavy metals contamination has always been the focus of research. Herein a biochar supported FeMnMg layered double hydroxide(LDH) composites(LB) for simultaneous remediation of copper and arsenic contamination in water and soil has been assembled by a facile co-precipitation approach. Both adsorption isotherm and kinetics studies of heavy metals removal by LB were applied to look into the adsorption performance of adsorbents in water. Moreover, the adsorption mechanisms of Cu and As by LB were investigated, showing that Cu in aqueous solution was removed by the isomorphic substitution, precipitation and electrostatic adsorption while As was removed by complexation. In addition, the availability of Cu and As in the soil incubation experiments was reduced by 35.54%–63.00% and 8.39%–29.04%, respectively by using LB. Meanwhile, the addition of LB increased the activities of urease and sucrase by 93.78%–374.35% and 84.35%–520.04%, respectively, of which 1% of the dosage was the best. A phenomenon was found that the richness and structure of microbial community became vigorous within 1% dosage of LB, which indirectly enhanced the passivation and stabilization of heavy metals. These results indicated that the soil environment was significantly improved by LB. This research demonstrates that LB would be an imaginably forceful material for the remediation of anionic and cationic heavy metals in contaminated water and soil.

The influence of manufacturing parameters and adding support layer on the properties of Zirfon separators

The composite separator comprising of polysulfone and zirconia was prepared by phase inversion precipitation technique. The influence of manufacturing parameters on its properties was investigated, and the results show that the manufacturing parameters affect the ionic resistance and maximum pore size significantly. A modified composite separator with a support layer was prepared to enhance the tensile strength of separator. By adding support layer, the tensile strength of the separator increases from 1.85MPa to 13.66MPa. In order to evaluate the practical applicability of the composite separator, a small-scale industrial electrolytic experiment was conducted to investigate the changes of cell voltage, gas purity and separator stability. The results show that the modified composite separator has a smaller cell voltage and a higher H2 purity than the asbestos separator, and are promising material for industrial hydrogen production.

Improved hydrogen separation performance of asymmetric oxygen transport membranes by grooving in the porous support layer

Hydrogen separation through oxygen transport membranes(OTMs)has attracted much attention.Asymmetric membranes with thin dense layers provide low bulk diffusion resistances and high overall hydrogen separation performances.However,the resistance in the porous support layer(PSL)limits the overall separation performance significantly.Engineering the structure of the PSL is an appropriate way to enable fast gas transport and increase the separation performance.There is no relevant research on studying the influence of the PSL on hydrogen separation performance so far.Herein,we prepared Ce0.85Sm0.15O1.925–Sm0.6Sr0.4Cr0.3Fe0.7O3-δ(SDC-SSCF)asymmetric membranes with straight grooves in PSL by tape-casting and laser grooving.A~30%improvement in the hydrogen separation rate was achieved by grooving in the PSLs.It indicates that the grooves may reduce the concentration polarization resistance in PSL for the hydrogen separation process.This work provides a straight evidence on optimizing the structures of PSL for improving the hydrogen separation performance of the membrane reactors.