Improving the Hydraulic Effects Resulting from the Use of a Submerged Biofiter to Enhance Water Quality in Polluted Streams.

Water scarcity is one of the most serious problems facing many countries. In addition, water pollution could lose more water. A submerged biofilter (SB) is used to enhance the self-purification process in polluted streams. However, most previous studies have focused on the efficiency of SB to remove pollutants and there is a lack of studies investigating the hydraulic changes in streams. The current paper aimed to study the hydraulic effects of SB on the flow behavior in streams and how to improve it. An empirical equation for determining the flow rate through SB was developed. Different cases were studied to improve the hydraulic effects resulting from the use of SB. The effect of increasing SB length was tested using different SB lengths. The results showed that increasing the length increased the upstream water depth (h1) and relative heading up (h1/h2). In the second case, comparison between continuous and fragmented SB was tested. The results showed that a fragmented biofilter increased the upstream water depth and the relative heading up. Case three tested the effect of SB height. Different SB heights were tested with a fixed length and constant flow rate. The results revealed that the upstream water depth and relative heading up decreased when the biofilter height decreased. Case four tested the effect of SB with a fixed volume and constant flow rate. In this case, the length and height of SB were changed where the volume was fixed. The results showed that the relative heading up decreased when the SB height decreased and the length increased, which revealed that the SB height can improve the hydraulic impacts. Finally, the use of SB to improve the water quality in polluted streams led to an increase of the relative heading up, which can be reduced by decreasing the height of SB.

Selective inhibition of tumor microvascular permeability by cavtratin blocks tumor progression in mice.

Tumor vasculature is hyperpermeable to macromolecules compared to normal vasculature; however, the relationship between tumor hyperpermeability and tumor progression is poorly understood. Here we show that a cell-permeable peptide derived from caveolin-1, termed cavtratin, reduces microvascular hyperpermeability and delays tumor progression in mice. These antipermeability and antitumor actions of cavtratin occur in the absence of direct cytostatic or antiangiogenic effects. Cavtratin blocks microvascular permeability by inhibiting endothelial nitric oxide synthase (eNOS), as the antipermeability and antitumor actions of cavtratin are markedly diminished in eNOS knockout mice. Our results support the concepts that hyperpermeability of tumor blood vessels contributes to tumor progression and that blockade of eNOS may be exploited as a novel target for antitumor therapy.