Abstract:The DongHaoChong (DHC) basin is located in the central city zone of Guangzhou City, China. Owing to the high density of buildings and low quality of the drainage pipe network in the city, diversion of rain and sewage is difficult. Waterlogging occurs frequently and combined sewer overflow (CSO) pollution is a serious problem during the rainy season. Therefore, a deep tunnel for the DongHaoChong basin has been planned and its construction is currently underway. An urban rainstorm model for the DongHaoChong basin was developed on the basis of the Storm Water Management Model (SWMM), and both the interception effect of CSO pollution and the degree of mitigation of flood were analyzed. Reasonable scenarios for the deep tunnel in terms of rainstorms with different design recurrence periods were evaluated. From the viewpoints of preventing rainstorm waterlogging disasters and protecting water quality in the region downstream of DongHaoChong River, the river flood control and drainage capacities of the region were improved to a 2-year rainstorm design recurrence period by the construction of the deep tunnel. Furthermore, the main pollutant load of the CSO is expected to be reduced by about 30%-40%.

Accelerated soil erosion is an undesirable process that adversely affects the conservation of water and soil. This paper used a procedure linking the Revised Universal Soil Loss Equation (RUSLE) and geographic information system (GIS) to map the soil erosion level from 1990 to 2010 caused by land-cover change in the Dongjiang River basin, China. Results indicate that the significant land-cover change greatly impacted soil erosion. The overall soil erosion level of the basin belonged to Level II (mild erosion) but the erosion amount shown an uptrend. Erosion areas of Levels I and II occupied more than 90% and other levels (Levels III–VI) occupied less than 10% of the total area. Approximately 90.85% of the area maintained the original levels, 5.84% converted from lower levels to higher levels, and 3.32% converted from higher levels to lower levels. The erosion in the downstream regions was more serious than that in the central and upstream regions. Although soil erosion was mild as a whole in the study region, some local areas underwent intense erosion. The study demonstrated that linking RUSLE with GIS tools is an efficient procedure for mapping soil erosion levels at basin scale. The gradual deterioration condition caused by land-cover changes at present or in the future requires further study.

In addition to serve as a physical scaffold, acellular scaffold should be involved in tissue repair processes such as hemostasis, inflammation, proliferation, and remodeling/regeneration as a bioactive material. The biological activities of acellular scaffold related to free amine groups may have a great influence on tissue repairing process after in situ implantation. In order to investigate the role of free amine groups in acellular scaffold on tissue repairing/regeneration process, the amine-blocked acellular scaffolds and amine-unblocked acellular scaffolds were prepared by using bovine pericardia. The scaffolds were in situ implanted in a dog model. The in vitro and in vivo experiment results showed that free amine groups in acellular scaffolds were indispensable for the biological activities of acellular scaffolds. Free amine groups of the acellular scaffold directly or indirectly took part in tissue repairing process including integration of acellular scaffold with the damaged tissue and the remolding process of the damaged tissue. Lack of the free amine groups made the acellular scaffolds difficult to integrate with the damaged tissue and impeded extracellular matrix dynamic process, which made the tissue remolding/regeneration process impossible.

Ion-exchange membranes have been widely used in the separation of ionic mixtures or as a barrier in some types of chemical power source because of their selectivity to cations and anions. In this article, a novel single-ion selective ionexchange membrane was fabricated to selectively separate copper ion from aqueous media. Polyethylenemine (PEI) was deposited onto a commercial cation-exchange membrane through an electric-field-enhanced procedure, and was subsequently modified with an ion imprinting technique. The effects of different parameters such as current density and feed composition on the deposition of PEI were studied. The copper ion imprinted membrane (Cu-IIM) showed lower resistance than the nonimprinted membrane (NIM) indicating the formation of a specific transportation path for the ions. The difference of binding isotherms for copper ion and zinc ion confirmed that the Cu-IIM had specificity to recognize copper ions. The permselectivity of the Cu-IIM was tested on an electrodialysis setup. The imprinting factor calculated from the separation factors of the imprinted and nonimprinted membrane was 1.99, demonstrating that the imprinting process enhanced the permselectivity of the membrane. The transport mechanism of ions in the Cu-IIM was also studied and analyzed.

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