Exhaust pollution and energy crises are worsening worldwide. China has become the largest motor vehicle producer; thus, promoting the use of new energy vehicles (NEVs) in China has important practical significance. In this paper, considering the limited rationality of governments, NEV enterprises and consumers, we study the subsidy policy of the China NEV market using the evolutionary game and system dynamics (SD) methods. First, a tripartite evolutionary game model is developed and the replicator dynamics equations and Jacobian matrix are obtained. A SD simulation of the model was conducted to further clarify the impact of the initial market proportion and three variables used in the model. The results show that the initial market proportion affects the evolution speed but does not affect the evolution result when the three group players all choose a mixed strategy. For governments, they should not hastily cancel price subsidies provided to consumers; rather, they should dynamically adjust the rate of the subsidy decrease and increase the consumers' extra cost for purchasing fuel vehicles (FVs). NEV enterprises should appropriately increase their investments in the research and development (R&D) of NEVs.
The experiment was conducted in a sealed, temperature-controlled room. The initial water temperature of the treatment group was 12°C, lowered by 1°C a day to 8°C using a chiller, and maintained at that temperature for 3 days. The water temperature was then increased by 1°C per day to 12°C using a heater. The control group were the fish that kept at 12°C at the beginning of the experiment; T1 represents the group that sampled on the first day when the water temperature reached 8 from 12°C; T2 represents the group that sampled when the fish had been kept at 8°C for 3 days; T3 represents the group sampled when the water temperature was increased to 12 from 8°C. The antioxidant abilities of the liver, muscle, and intestine of large yellow croaker at different temperatures and times were determined, and the expression of HSP70 and HSP90 in the liver as well as the changes in intestinal microbiota were investigated. The results showed that the activities of SOD, CAT, GSH-Px, and MDA content increased significantly when the water temperature decreased from 12 to 8°C, significantly higher than those in the control group. The gene expression levels of HSP70 and HSP90 in the liver of large yellow croaker significantly increased under low temperature stress and were significantly higher than those in the control group. The diversity and abundance of intestinal microbiota of large yellow croaker were altered when the water temperature was maintained at 8°C, although the change was not obvious. Proteobacteria, Firmicutes, and Bacteroidetes were the dominate phyla in both the 12 and 8°C groups, and the temperature variation did not change the functional pathways of the microbiota. In conclusion, the acute temperature variation affected the antioxidant ability and heat shock protein expression of large yellow croaker but did not affect the diversity or abundance of the intestinal microbiota. These results will provide a theoretical basis for studying the mechanisms of large yellow croaker overwintering and adaptation to low temperatures.
This study was conducted to investigate the effects of replacing dietary lipid source FO with a terrestrial lipid blend (LB) on the growth performance, body composition and immunity of juvenile Japanese sea bass when the dietary n‐3 long‐chain polyunsaturated fatty acids (n‐3 LC‐PUFAs) requirements are met (Lateolabrax japonicus). Two types of experimental diets were formulated with the total FO (the control) or the LB (linseed oil and lard = 1:1). A 56‐day feeding trial was conducted in floating cages with three replicates for each treatment. The results indicated that a significantly higher specific growth rate (SGR) and feed efficiency ratio (FER) occurred in fish that were fed the LB diet compared with the control group (p < 0.05). There was no significant difference in the survival rate, body composition or body indicates between the groups (p > 0.05). The respiratory burst, alternative complement pathway activity, lysozyme activity, cytokine genes expression and air exposure test results indicated that the replacement of FO with LB did not significantly affect the nonspecific immunity or stress resistance (p > 0.05). The serum antioxidant enzyme activities and liver tissue antioxidant‐related gene expression were significantly higher in the control group than in the other group (p < 0.05). Therefore, the terrestrial lipid blends from linseed and lard (1:1) could be used as an alternative for dietary fish oil without compromising the growth performance, nonspecific immunity and resistance to stress in juvenile Japanese sea bass.
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