The erosion failure mechanism of concrete is studied systematically based on field investigation and laboratory experiments of concrete samples from more than 30 km concrete lining and 10 hydraulic structures of Shand...The erosion failure mechanism of concrete is studied systematically based on field investigation and laboratory experiments of concrete samples from more than 30 km concrete lining and 10 hydraulic structures of Shandong Jiaodong water diversion project, in which the concrete failed only 3-6 months after conslruction was completed. With electron microscopy scanning, energy dispersive analysis, XKD （X-ray diffraction） analysis and Raman spectrum analysis of the mineral composition of the failure concrete and precipitates, chemical and physical reactions that occurred in the concrete under engineering environment were investigated. The analysis indicated that the rapid corrosion and dissolution reaction of the concrete in weak sulfate environment is due to sulfate and carbonate corrosion with the catalytic magnesium salt at low temperature. Also, corrosion damage facilitates the sulfate ions and carbonate ions into the concrete, and the expansion of ettringite and TSA （thaumasite sulfate attack） reaction also accelerates the corrosion damage of the concrete.展开更多
It is demonstrated that a low grade, silver containing manganese deposit can be exploited by reaction with a ZnS concentrate. In the process, Mn(IV) is reduced to Mn(II) and the ZnS converted to ZnSO4. In the process,...It is demonstrated that a low grade, silver containing manganese deposit can be exploited by reaction with a ZnS concentrate. In the process, Mn(IV) is reduced to Mn(II) and the ZnS converted to ZnSO4. In the process, Mn and Zn are solubilized. By studying the effects of quantity of reducing agent and sulfuric acid added and of time, temperature and liquid-to-solid ratio on the leaching process, the optimum technological conditions have been achieved under which the amount of manganese leached was 98 %. The silver can be removed from remaining solids by adding ammonia liquor. Then by adding hydrazine hydrate, sponge silver with purity up to 99 % can be obtained with a recovery of 87 %.展开更多
For the requirement of preliminary vascularization, the scaffolds for thick tissue engineering should have not only good cell affinity, but also anticoagulant ability. In this paper, enzymatically cross-linked hydroge...For the requirement of preliminary vascularization, the scaffolds for thick tissue engineering should have not only good cell affinity, but also anticoagulant ability. In this paper, enzymatically cross-linked hydrogel scaffolds based on sulfated chitosan （SCTS） were prepared. Firstly, sulfated chitosan-hydroxyphenylpionic acid （SCTS-HPA） conjugate was synthesized, and the structure of SCTS-HPA was identified by FITR and ~H NMR. And then the enzymatically cross-linked hydrogels were pre- pared in presence of horseradish peroxidase （HRP） and hydrogen peroxide （H202）. The gelation time, mechanical property, morphology and cytotoxicity to human umbilical vein endothelial cells （HUVECs） of the hydrogel were evaluated in vitro, the tissue compatibility of SCTS-HPA scaffold was studied in vivo. The results showed that the gelation time, mechanical property, morphology of the dehydrated hydrogel could be controlled by the the concentration of HRP and H202. The cytotoxicity test showed that the hydrogel extracts have no cytotoxicity to HUVECs. The in vivo assay indicated that SCTS-HPA scaffold have good tissue compatibility with no thrombus formation. All these results indicated that the SCTS-HPA scaffold could be used as a thick tissue engineering scaffold.展开更多
文摘The erosion failure mechanism of concrete is studied systematically based on field investigation and laboratory experiments of concrete samples from more than 30 km concrete lining and 10 hydraulic structures of Shandong Jiaodong water diversion project, in which the concrete failed only 3-6 months after conslruction was completed. With electron microscopy scanning, energy dispersive analysis, XKD （X-ray diffraction） analysis and Raman spectrum analysis of the mineral composition of the failure concrete and precipitates, chemical and physical reactions that occurred in the concrete under engineering environment were investigated. The analysis indicated that the rapid corrosion and dissolution reaction of the concrete in weak sulfate environment is due to sulfate and carbonate corrosion with the catalytic magnesium salt at low temperature. Also, corrosion damage facilitates the sulfate ions and carbonate ions into the concrete, and the expansion of ettringite and TSA （thaumasite sulfate attack） reaction also accelerates the corrosion damage of the concrete.
文摘It is demonstrated that a low grade, silver containing manganese deposit can be exploited by reaction with a ZnS concentrate. In the process, Mn(IV) is reduced to Mn(II) and the ZnS converted to ZnSO4. In the process, Mn and Zn are solubilized. By studying the effects of quantity of reducing agent and sulfuric acid added and of time, temperature and liquid-to-solid ratio on the leaching process, the optimum technological conditions have been achieved under which the amount of manganese leached was 98 %. The silver can be removed from remaining solids by adding ammonia liquor. Then by adding hydrazine hydrate, sponge silver with purity up to 99 % can be obtained with a recovery of 87 %.
基金supported by the National Basic Research Program of China(973 Project,2011CB606202)the National Natural Science Foundation of China(51273095)
文摘For the requirement of preliminary vascularization, the scaffolds for thick tissue engineering should have not only good cell affinity, but also anticoagulant ability. In this paper, enzymatically cross-linked hydrogel scaffolds based on sulfated chitosan （SCTS） were prepared. Firstly, sulfated chitosan-hydroxyphenylpionic acid （SCTS-HPA） conjugate was synthesized, and the structure of SCTS-HPA was identified by FITR and ~H NMR. And then the enzymatically cross-linked hydrogels were pre- pared in presence of horseradish peroxidase （HRP） and hydrogen peroxide （H202）. The gelation time, mechanical property, morphology and cytotoxicity to human umbilical vein endothelial cells （HUVECs） of the hydrogel were evaluated in vitro, the tissue compatibility of SCTS-HPA scaffold was studied in vivo. The results showed that the gelation time, mechanical property, morphology of the dehydrated hydrogel could be controlled by the the concentration of HRP and H202. The cytotoxicity test showed that the hydrogel extracts have no cytotoxicity to HUVECs. The in vivo assay indicated that SCTS-HPA scaffold have good tissue compatibility with no thrombus formation. All these results indicated that the SCTS-HPA scaffold could be used as a thick tissue engineering scaffold.
