Search

Simple Summary: Poly-β-hydroxybutyrate (PHB) has proven potential to promote growth and immunity in aquaculture. This study aimed to investigate the effects of adding amorphous Halomonas-PHB to the diet for grouper culture. The findings revealed that supplementation with amorphous Halomonas-PHB did not significantly improve fish growth performance, but it increased the content of fatty acids, including long-chain unsaturated fatty acids C18:1n9, EPA, and DHA in fish muscle. Additionally, it enhanced the resistance of the fish to Vibrio anguillarum possibly by regulating immune-related gene expression in different tissues and organs. These results will contribute valuable insights for the practical application of amorphous Halomonas-PHB in aquaculture. Poly-β-hydroxybutyrate (PHB) is a bacterial metabolite produced by bacteria such as Halomonas sp. that serves as a carbon and energy storage compound for bacteria under nutrient-limited conditions. Two experiments were conducted to investigate the effects of dietary supplementation with Halomonas-PHB on hybrid grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatu ♂). In experiment I, juvenile groupers were fed basal diets supplemented with 3% Halomonas-PHB (3% HM-PHB) containing 1.4% PHB and 3% Halomonas (3% HM) without PHB, as well as a control diet, for seven weeks. The results showed no significant difference in survival rate, weight gain, and crude fat content between the 3% HM-PHB group and the control group; however, the crude protein of the 3% HM-PHB group was significantly lower than that of the control group. Furthermore, supplementation with 3% HM-PHB increased the fatty acids content in fish muscles, including long-chain unsaturated fatty acids C18:1n9, EPA, and DHA. In experiment II, groupers were fed a basal diet supplemented with 6.5% Halomonas-PHB (6.5% HM-PHB) containing 3% PHB and 6.5% Halomonas (6.5% HM) containing no PHB, as well as a basal diet (Control). After seven weeks of rearing, the fish were challenged with Vibrio anguillarum for 48 h. Although no significant difference in survival rate and growth was observed among different groups, the dietary supplement of 6.5% Halomonas-PHB improved the survival rate of V. anguillarum challenged grouper and significantly increased the gene expressions of catalase (CAT) and superoxide dismutase (SOD) in blood, interleukin 1 (IL1) and interleukin 10 (IL10) in the liver, spleen, head kidney, and blood (p < 0.05). In conclusion, dietary supplementation of Halomonas-PHB had no significantly positive effect on fish growth performance but increased the content of fatty acids, including long-chain unsaturated fatty acids C18:1n9, EPA, and DHA in fish muscle; it also improved the V. anguillarum resistance, possibly through increasing immune-related gene expression in different tissues and organs. Our findings offer compelling evidence that Halomonas-PHB can be utilized as a feed additive in intensive grouper farming to enhance the groupers' resistance to Vibrio. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) membranes with doorman characteristic, tunable nanochannel microenvironment and high interfacial adhesion were fabricated. Herein, polyethyleneimine (PEI) molecules were selected for bridging, reducing and intercalating the GO nanosheets in GO-PEI membranes. Moreover, the optimal amount of PEI molecules facilitated the expansion and alignment of the transfer channels with the spacing of 0.93 nm to 1.52 nm. In particular, the GO nanosheets undertook deoxidations twice under the action of a strong alkaline NaOH solution and PEI molecules, which led to more structural defects and certain wrinkles for providing extra water transfer channels. On this basis, PEI molecules exhibited doorman characteristics at different pH values. As the state-of-the-art technology, the nano-scratch tests showed that the interfacial adhesion of the GO-PEI membrane (18.62 μN) bridged by PEI was nearly 9 times stronger than that of the pure GO membrane (2.15 μN). [ABSTRACT FROM AUTHOR]

Electromagnetic interference (EMI) shielding material with good flexibility and lightweight is an effective way to eliminate electromagnetic pollution sources. Herein, lightweight, flexible, and strong CoFe/C/HCF composites with hierarchical pore structures were constructed by in situ growth, etching/ion exchange reaction, and high-temperature pyrolysis using cotton fabric (CF) as the substrate. The Co-MOF nanosheet was in situ grown on the surface of CF, and CoFe-LDH nanosheets were formed after the etching/ion-exchange reaction. CoFe/C/HCF composites with hierarchical pore structures were obtained after high-temperature pyrolysis. The hierarchical pore structure was verified using small-angle neutron scattering analysis. The unique hierarchical pore structure and strong interfacial interaction make the composites have higher average shielding efficiency (SE) and specific shielding efficiency (SSE), when the thickness is only 0.9 mm, which reached 30.7 dB and 109.64 dB·cm3 g–1, respectively. Meanwhile, ultrafast photothermal performance is also achieved, which can ensure the normal function of the composite material in cold conditions. This work provides possibilities for the potential applications of CoFe/C/HCF composites in flexible sensing and wearable smart electronics. [ABSTRACT FROM AUTHOR]