Using Monte Carlo simulation methods, the effects of the comonomer sequence distribution on the interfacial properties (including interfacial tension, interfacial thickness, saturated interfacial area per copolymer, and bending modulus) and interfacial structures (including chain conformations and comonomer distributions of the simulated copolymers at the interfaces) of a ternary symmetric blend containing two immiscible homopolymers and one gradient copolymer are investigated. We find that copolymers with a larger composition gradient width have a broader comonomer distribution along the interface normal, and hence more pronouncedly enlarge the interfacial thickness and reduce the interfacial tension. Furthermore, the counteraction effect, which arises from the tendency of heterogeneous segments in gradient copolymers to phase separate and enter their miscible phases to reduce the local enthalpy, decreases the stretching of copolymers along the interface normal direction. As a result, copolymers with a larger width of gradient composition can occupy a larger interfacial area and form softer monolayers at saturation and are more efficient in facilitating the formation of bicontinuous microemulsions. Additionally, chain length ratio, segregation strength, and interactions between homopolymers and copolymers can alter the interfacial character of gradient copolymers. There exists a strong coupling between the comonomer sequence distribution, chain conformation, and interfacial properties. Especially, bending modulus is mainly determined by the complicated interplay of interfacial copolymer density and interfacial chain conformation.

We conducted a 71-day experiment to investigate the effects of stocking density in a recirculating aquaculture system (RAS) on the growth performance, body composition, digestive activity, and blood biochemical parameters of the marbled eel Anguilla marmorata. We stocked marbled eel in 1.0 m 3 tanks at stocking densities of 12, 20, and 28 kg/m 3 , which were designated the low-density (LD), medium-density (MD) and high-density (HD) groups. The fish weighed 169.72 ± 2.75 g at the baseline level. Results revealed that the fish in the LD and MD groups had a higher ash content than fish in the HD group. The crude lipid content was significantly lower in the MD and HD groups than in the LD group. The protease activities in the stomach and intestine did not differ among the three groups. The total protein and aspartate aminotransferase levels were higher in the LD group than in the MD group. The alanine aminotransferase level was significantly lower in the LD group. These results indicate that a greater increase resulted in stress and significantly affected the growth of the fish. The optimum stocking density of A. marmorata can be achieved at 20.0 kg/m 3 in a RAS.

No abstract