Effect of Calcium Carbide Residue on Strength Development along with Mechanisms of Cement-Stabilized Dredged Sludge.

The purpose of this research is to explore the feasibility of using calcium carbide residue (CCR), a by-product from acetylene gas production, as a solid alkaline activator on the strength development in CCR-Portland cement-stabilized dredged sludge (CPDS). The effects of cement content, CCR content and curing time on the strength development of CPDS were investigated using a series of unconfined compressive strength (UCS), pH and electric conductivity (EC) tests. Scanning electron microscopy and X-ray diffraction analyses were performed to gain additional insight into the mechanism of strength development. Meanwhile, the carbon footprints of CPDS were calculated. Following the results, it was found that CCR can significantly improve the strength of cemented dredged sludge. On the basis of the strength difference (ΔUCS) and strength growth rate (UCSgr), it was recommended that utilizing 20% cement with the addition of 20% CCR is the most effective way to develop the long-term strength of CPDS. In addition, the microstructural analysis verified that the optimum proportion of CCR benefits the formation of hydration products in CPDS, particularly needle-like gel ettringite, resulting in a less-porous and dense inter-locked structure. Furthermore, the solidification mechanism of CPDS was discussed and revealed. Finally, it was confirmed that CCR can be a sustainable alternative and effective green alkaline activator for the aim of improving cemented dredged sludge.

Efficacy of Montanide™ ISA 763 A VG as aquatic adjuvant administrated with an inactivated Vibrio harveyi vaccine in turbot (Scophthalmus maximus L.).

Turbot (Scophthalmus maximus L.) is a commercially important fish species in China. Despite of its great economic potential, fish farms often suffer severe economic losses due to certain fish diseases. Vaccination has become a common strategy to prevent diseases caused by pathogens in aquaculture industry. However, no inactivated vaccine against Vibrio harveyi of turbot has been reported so far. In this study, we developed an inactivated vaccine using formalin-killed cells of V. harveyi and the efficacy of a commercial adjuvant Montanide™ ISA 763 A VG on the inactivated vaccine was evaluated. We found that with an optimum vaccine dosage at 1.0 × 108 CFU/fish, a high relative percent survival (RPS) more than 75% was observed at 4 weeks post vaccination (w.p.v.). Moreover, enhanced antibody titer, lysozyme activity, total serum protein and antibacterial property in sera of vaccinated fish were observed at 4, 8, 12 and 16 w.p.v. In conclusion, we developed an efficient inactivated vaccine against V. harveyi in turbot, which not only induced humoral immunity, but also enhanced initial innate immune response for long-term protection.

A live attenuated Vibrio anguillarum vaccine induces efficient immunoprotection in Tiger puffer (Takifugu rubripes).

Tiger puffer (Takifugu rubripes) is becoming an economic promising aquaculture species in China. However, the development of Tiger puffer breeding industry is restricted by some serious aquatic disease such as vibriosis. An effective live attenuated vaccine MVAV6203 was developed in our previous studies by curing the virulence plasmid pEIB1 and unmarked inframe-deletion of the aroC gene from the virulent V. anguillarum. Here, we evaluated whether this live vaccine was suitable for Tiger puffer against disease caused by Vibrio genus. The live vaccine show virulence attenuation in both juvenile and adult fish vaccinated with either a single or high dose (50-fold single dose). In addition, administration of the live vaccine shew limited growth in fish and did not affect fish body weight significantly, with no adverse impact on growth between vaccinated and saline control fish. Furthermore, increased expression of cytokines involved in pro-inflammatory (IL-1ß, TNFα and IL-6), cell-mediated immunity inducing (IL-12p35, IL-12p40 and IL-18), antiviral/intracellular pathogen killing (I-IFN-1, IFN-γ and Mx), peripheral T cell expansion and survival controlling (IL-2, IL-7 and IL-15) and antigen processing maker and anti-inflammatory (MHC I and IL-10) were elicited significantly after the vaccination. These cellular responses correlate with protection against virulent strain challenge and high RPS of 90.67% and 80.31% in juvenile and adult fish were obtained, respectively. These data indicated for the first time that the live attenuated V. anguillarum vaccine is suitably applied for the development of an effective and safe vaccine for prevention of vibriosis in Tiger puffer aquaculture industry.

Flagellin enhances the immunoprotection of formalin-inactivated Edwardsiella tarda vaccine in turbot.

Edwardsiella tarda is an important fish pathogen that causes extensive losses in farmed fish around the world. Various types of vaccines have been developed against E. tarda infection, such as inactivated vaccine, live attenuated vaccine and subunit vaccine. However, inactivated vaccine exhibits poor immune protection against edwardsiellosis in some reports. In this study, we aimed to evaluate the protective effect of formalin-killed cells (FKC) against E. tarda with flagellin, FlgD, as an adjuvant in turbot. As a result, the relative percent survival (RPS) of turbot vaccinated with FKC reached 70% in the presence of FlgD adjuvant. Moreover, specific serum antibodies reached the highest level at 3weeks post vaccination. Furthermore, the transcription of some immune response-related genes, such as MHC-I, IgM, IL-1ß, TCR, and TNFα were up-regulated in turbot after vaccination, indicating that both humoral and cellular immune responses were induced by this vaccine. In summary, flagellin can enhance immunoprotection of the formalin-inactivated E. tarda vaccine, which can be used as a potential adjuvant in fish vaccine.