Search

The cofferdam built at the inlet of the diversion tunnel may be left due to incomplete blasting demolition, which affects the river closure. Several indexes have been used to evaluate the difficulty of river closure, but all indexes suffer from their limitations in use. Thus, it is more useful to combination multiple indexes to analyze the impact of residual cofferdam. Taking the river closure project of a Hydropower Station in southwest China as an example, the influence of the residual cofferdam heights on the river closure was studied by experiments. The discharge of river closure is 590 m3/s and 758 m3/s. In this paper, the results of studies on a 1:50 scale hydraulic model based on the Froude similitude relationships are presented. The test results show that the discharge capacity of the diversion tunnel is reduced by 27.2% at most when this height is more than 2 m. The residual height mainly affects the maximum of stream energy with unit width, which increase by more than 50% at most compare to Non-existent residual cofferdam. However, the final drop, max-velocity along the gap axis, the local scour of riverbed and the flow pattern of the gap are basically not affected. In addition, with the height increase, the bank collapse is intensified, and the amount of dumped material with medium size increases, especially when it reaches 4 m, the large or Extra-large size stones begin to be dumped. Based on the comprehensive evaluation of multiple indexes and the type of dumped material, it is shown that the residual cofferdam height more than a certain value, the value is 2 m for the case study, will significantly increase the river closure difficult.

Some medicinal plants have been known as immunostimulants, and the medicinal plants extract has been used to control the outbreak of the disease in aquaculture for many years. In this study, a total of 270 crucian carp (30 ± 5 g) were randomly distributed in 9 aquaria (55 cm l × 40 cm w × 50 cm h) and divided into three feeding groups including 0 (Control), 50 mg kg−1 (Diet A) and 100 mg kg−1 (Diet B) of salidroside. The expression of immune-related genes (IL-1β, TNFα, MYD88, CXCL-8, TGF-β, and IL-11) in the kidney had a significant increase when the crucian carp fed with Diet B for 4 weeks (P < 0.05). Meanwhile, the expression of IL-1β, TNFα, and CXCL-8 in the spleen was significantly up-regulated when the fish fed with Diet B (P < 0.05). Higher serum alkaline phosphatase (AKP) activity, catalase (CAT) activity, superoxide dismutase (SOD) activity, and complement C3 content were found in the fish which fed with salidroside-supplemented diet. Our results also proved that fish fed with salidroside-supplemented diet for four weeks, especially at a concentration of 100 mg kg−1 diet, improved the protection of crucian carp against A. hydrophila. The amount of A. hydrophila in the kidney and spleen was significantly decreased in salidroside-supplemented diet groups (P < 0.05). In conclusion, the present results demonstrate that the addition of salidroside for four weeks can improve the immune response of crucian carp and increase the protection against the pathogen, especially at the concentration of 100 mg kg−1 diet. The protective effect of the salidroside to the crucian carp could be used as alternatives to antibiotics for controlling fish diseases in aquaculture. • Salidroside evaluated as an immunostimulant in crucian carp. • Salidroside has strong immunostimulant effects up-regulated immune related gene expression. • Salidroside has strong immunostimulant effects stimulated serum enzyme activity. • The use of salidroside in crucian carp diet was increased fish resistance against A. hydrophila infection. [ABSTRACT FROM AUTHOR]

Chinese herbal medicines, as the natural and innocuous compounds, have been used commonly as immunostimulants to increase growth performance, immune response and disease resistance in fish. This study aimed to investigate the effects of dietary geniposide on the immune response and disease resistance in crucian carp. The fish were fed with three different levels of geniposide-supplemented diets, including 1 mg/kg (low level group, LLG), 10 mg/kg (medium level group, MLG), 100 mg/kg (high level group, HLG) geniposide, respectively. Innate immune response, immune-related genes expression, and disease resistance against Aeromonas hydrophila infection were detected to evaluate the immunostimulant effect of dietary geniposide. The results showed that compared with control group, crucian carp fed with different levels of geniposide showed significant (p <.05) improvement serum lysozyme activity, SOD activity, complement C3 and catalase activity (CAT). Dietary geniposide increased nine immune-related genes expression in spleen and kidney with different degree. In addition, the cumulative survival percent of fish in treatment groups were significant higher than control group (10%) in challenge experiment with A. hydrophila , the relative percent survivals were 22.2%, 48.1%, and 70.4% in LLG, MLG and HLG groups, respectively. Taken together, these results suggested that geniposide used as immunostimulant was capable of improving the immune response and disease resistance against A. hydrophila infection. The supplemental level of geniposide against A. hydrophila infection in crucian carp was estimated to be about 100 mg/kg diet. • Geniposide as immunostimulant enhanced the innate immune response. • Geniposide as immunostimulant upgulated immune-related genes expression. • Geniposide as immunostimulant increased the disease resistance. • The optimal dose of dietary geniposide was about 100 mg/kg diet in crucian carp. [ABSTRACT FROM AUTHOR]