Advanced Materials Research Vols. 391-392

Abstract: So far, there were few models which could calculate the effective mass diffusivity D_e in nanofluids. In this paper, we proposed a lattice Boltzmann model to simulate the diffusion processes of Rhodamine B in 25nm-Cu/water nanofluids with different volume fractions and temperatures, and also calculated the effective mass diffusivity D_e. The results agreed well with the experimental data in literatures. So this model can be utilized to calculate the mass diffusivity in nanofluids. At last, we have discussed the enhancement mechanisms of diffusion in nanofluids.

Abstract: The temperature-stress testing machine can be adopted to evaluate the crack resistance of concrete, but because of the disadvantages of long time, costs much restrict the development of temperature-stress test method. Getting needed mechanical and thermal parameters by the test here, then be used in the temperature history calculated by simulation software to compare crack resistance of different concretes. By using the convenient method, we can compare crack resistance of different concretes under the actual condition through simulation. The results showed that: the B4Cast simulation software can be used to get different concrete internal temperature histories under different temperature control methods, using the temperature history close to the real condition can evaluate the crack resistance of concrete objectively; on the basis of the temperature-stress test results, via fitting obtained the rules of concrete coefficient of thermal expansion, contraction deformation, elastic modulus, tensile strength and other parameters with maturation changes, then be used in the temperature history calculated by B4Cast, the concrete cracking risk can be simulation analyzed; using this method to compare the same strength grade of normal and pump concrete, the result showed that crack resistance of normal concrete is better.

Abstract: The paper studied polymerization of rac-lactide catalyzed by a diketiminato aluminum alkoxide complex. The aluminum alkoxide complex bearing bulky isopropyl ortho substituents showed moderate activity for the rac-lactide polymerization. Microstructural study of polymer generated with the aluminum catalyst reveals that syndiotactic polylactide were produced. Results have shown that the conversion of lactide depend on the monomer/catalyst feed ratio and the reaction temperature.

Abstract: Molecularly imprinted polymers (MIPs) of L-phenylalanine ethyl ester were synthesized in this study. Then, the prepared MIPs were packed in a stainless column and evaluated as the chiral stationary phases of high performance liquid chromatography (HPLC). The MIPs exhibited a considerable capability of chiral separation between template molecule and its enantiomer with the separation factor of 1.69. Furthermore, the weakest interaction model was introduced to study the chiral recognition mechanism of MIPs. The results suggested that the weakest interaction between the template molecule and the imprinted cavity played crucial role in chiral separation, and the molecular tension should be taken into consideration during the separation procedure. The separation factor of 2.07 was calculated by the theoretical model, which was very close to the value obtained from chromatographic experiment.

Abstract: This paper reports a method for scale-up fabrication of hydrophobic and flexible aerogels derived from a combined precursor methyltrimethoxysilane and vinyltrimethoxysilane. The method developed enables the preparation of large pieces of monolithic aerogels at ambient pressure drying conditions. The thermal and acoustic insulation properties of the flexible aerogels were investigated and compared with the commercially available insulation materials.

Abstract: The microstructures and phase constituent of as-cast Mg-5Sn-5Zn-xSr (x=0, 0.5, 1, 2) alloys were analyzed by the optical microscopy (OM), the scanning electron microscope (SEM) and the X-ray diffraction (XRD). The results indicate that an addition of 0.5%-2% (mass fraction) Sr to the Mg-5Zn-5Sn alloy not only refines the dendrite arm spacing of -Mg but also results in the formation of MgSnSr phases. Furthermore, it was found that the increase of Sr results in Mg2Sn phase decreasing and MgSnSr phase increasing. While the MgZn phase which is attached with Mg2Sn phase exists in the form of -Mg+MgZn eutectic structure.

Abstract: The paper studied the effect of tide on the removal rate of COD, NH₃-N and TP in the dosing pool in order to provide data to simulate disorderly discharged sewage in tidal rivers. Due to the dilute effect of rivers, the removal rate of COD, NH₃-N and TP at the tidal state was higher than that at no tidal state. At the tidal state, the average removal rate of COD, NH₃-N and TP was 60.8%, 55.7%, 55.6%. At no tidal state, the average removal rate of COD, NH₃-N and TP was 57.5%, 47.5%, 8.6%. At the tidal state, the upper bio-film was exposed to air and the activity of microorganism decreased, and the activity of microorganism was high at middle-level bio-film. Therefore, the utilization of bio-film at the tidal state was lower than that at no tidal state. However, due to the tidal action, rivers entered into the dosing pool and the dilute effect of rivers on the pollutants was obvious.

Abstract: The paper studied the effect of water flow pattern on the treatment of disorderly discharged sewage in tidal rivers by bio-film process. The results indicated that biomass was greater under the fluctuation turn flow than under the folding flow around. Under the fluctuation turn flow, the concentration of COD was 168mg/L and the removal rate of COD was 37.1%. Under the folding flow around, the concentration of COD was 187mg/L and the removal rate of COD was 29.4%. The results indicated that the removal rate of COD was higher 7.7% under the fluctuation turn flow than under the folding flow around. The reason was that under the fluctuation turn flow, soft packing fiber was derided by water, and the effective use of surface area was great and microbial growth space was large.

Abstract: The paper studied the removal rate of COD under the impact of an instantly big flow of wastewater, and restoring capacity of bio-film after the impact in order to provide data to simulate disorderly discharged sewage in tidal rivers. At 2h after rising tide, the concentration of COD in the dosing pool was 187mg/L and the removal rate of COD was 33.2%. The removal rate of COD before the impact was similar to that after the impact, which indicated that bio-film had the adaptive ability. At 2h after ebb tide, the removal rate of COD was 30.7% after the impact in the dosing pool. The removal rate of COD was 32.0% before the impact in the dosing pool. Compared to the removal rate of COD before the impact, the removal rate of COD after the impact slightly decreased and the reason was that multiple enzyme stimulant had the positive effect on restoring capacity of bio-film.

Abstract: The rheological behavior of plant flour reinforced thermoplastics composites is very important to practical industry, however few research especially research about bamboo flour reinforced polypropylene(PP) composites is available regarding rheological field. In this paper, the torque rheometer made in Shanghai was used to examine the flow behavior of bamboo flour filled PP composites. The orthogonal test was adopted to analyze how three factors(weight percentage of bamboo, weight percentage of MAPP and rotate speed) influence the behavior of composites. The result indicated that bamboo flour filled PP composites was pseudo-plastics or shear-thinning flow under the experimental condition investigated. The effect of weight percentage of bamboo on rheological peoperties was signigficant,but the effect of both of the rest of two factors on rheological was not significant under the given experimental condition.