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The development of marine resources and the construction of coastal islands need a reliable energy supply. The floating nuclear power plant (FNPP) is a combination of small nuclear reactors and offshore platforms, and it can be used in many fields such as offshore power supply, combined heat and power, and seawater desalination treatment. FNPP has the advantages of high power density, sustainable power generation, and low carbon emission. But due to environmental factors such as wind and waves on the sea or ship navigation, FNPP will generate complex motions in actual sea conditions. Liquid sloshing will occur in accumulators and other liquid storage tanks subjected to additional inertial forces under moving conditions. The free surface fluctuation will disturb the measurement of critical parameters such as liquid level, and the fluid impact load will affect the operation and maintenance of equipment. So measurement experiments were carried out based on the 6-DOF motion platform to study the sloshing characteristics and pressure variation rule of the accumulator. The pressure surge was studied by multi-directional pressure sensors, the free surface sloshing process was obtained by the high-speed camera system, and the natural frequency of the accumulator was obtained according to the model equivalent and mathematical analysis. The results show that under rolling motions, the pressure variation period is consistent with the motion period and the pressure amplitude can be determined by motion angle. The motion forms of liquid surface are basically stationary waves and marginal hydraulic jump, and the pressure measurement results show a regular sine and cosine variation, so the system analysis model under rolling conditions can be reasonably simplified based on the above analysis and safety margin assessment. Under horizontal sloshing, the additional inertial force will induce many kinds of nonlinear liquid surface sloshing. Based on time and frequency domain analysis, it can be seen that the pressure variation rule is mainly dominated by natural frequency, excitation frequency, and frequency multiplication. The pressure variation amplitude increases sharply and reaches the peak value under resonance conditions. There are unstable evolution processes and chaotic sections of pressure surge under specific sloshing conditions, where the pressure variation has randomness and initial value sensitivity. In addition, the breaking and rotation of the free surface will occur near the resonance frequency. Under the coupled motion, the pressure at the measurement point is affected by the characteristics of single degree of freedom motion and the coupling form of different motion. The coupled motion can be disassembled and analyzed based on considering the phase difference. In summary, the study can provide an analytical basis for sloshing research of liquid storage equipment and provide a reference for structural improvement and sloshing suppression optimization.

Controllable variable stiffness compliant actuator mechanism has the characteristics of high compliance, high environmental adaptability and good man-machine interaction. The variable stiffness compliant actuator mechanism is based on the transmission principle of a four-bar linkage with a zero-length rack. The variable stiffness control can be realized by changing the properties and the winding mode of the elastomer, or the configuration scheme. Through configuration analysis and structure design, the stiffness and torque models of the compliant actuator mechanism are established to reveal its stiffness behavior. The Lagrangian method is used to establish the dynamic model of the compliant actuator mechanism, and the frequency theoretical results are obtained by solving the average stiffness. The virtual prototype is established to motion simulation, which reveals its performance characteristics and verifies the correctness of theoretical analysis. Compared with other similar designs, the compliant actuator mechanism proposed has the characteristics of miniaturization and lightweight with strong applicability. It can be used as a single module and integrated into the exoskeleton system.

Objective: To produce human papillomavirus type 11 virus-like particles (HPV11 VLPs) from Escherichia coli and to investigate its immunogenicity and type cross neutralization nature., Methods: We expressed the major capsid protein of HPV11 (HPV11-L1) in Escherichia coli ER2566 in non fusion fashion and purified by amino sulfate precipitation, ion-exchange chromatography and hydrophobic interaction chromatography, sequentially. Then we removed the reductant DTT to have the purified HPV11-L1 self-assemble into VLPs in vitro. We investigated the morphology of these VLPs with dynamic light scattering and transmission electron microscopy. We assayed the immunogenicity of the resultant HPV11 VLPs by vaccinations on mice and evaluated by HPV6/11/16/18 pseudovirion neutralization cell models., Results: We expressed HPV11 L1 in Escherichia coli with two forms, soluble and inclusion body. The soluble HPV11 L1 with over 95% purity can self assemble to VLPs in high efficiency. Morphologically, these VLPs were globular, homogeneous and with a diameter of - 50 nm, which is quite similar with native HPV11 virions. The half effective dosage (ED50) of HPV11 VLPs is 0.031 microg, and the maximum titer of neutralizing antibody elicited is averaged to 10(6). The cross neutralization activity (against HPV6/16/18) of the anti-HPV11 serum was found to have exact correlation to the inter-type homology in amino acid alignment., Conclusion: We can provide HPV11 VLPs with highly immunogenicity from prokaryote expression system, which may pave a new way for research and development of prophylactic vaccine for HPV11.

Here, we presented a method to bacterially express the major structural protein L1 of Human Papillomavirus type 18 (HPV18) as soluble form. We found that the purified L1 could self-assemble to virus-like particles (VLPs). Further, we investigated the immunogenicity and the induced level of neutralizing antibody using these VLPs. First, the genome of HPV18 was cloned from a patient in Xiamen. It was used as template for PCR amplification of HPV18 L1 gene. The resultant DNA fragment was inserted into expression vector pTrxFus and expressed in Escherichia coli GI724. Second, L1 protein was purified by ammonium sulfate precipitation, ion-exchange chromatography and hydrophobic interaction chromatography; and the purified L1 was subjected to self-assembly to form VLPs with the removal of premixed reductant DTT. Finally, the size and morphology of these VLPs was investigated by Dynamic Light Scattering and Transmission Electronic Microscopy as 29.34 nm in hydrated radius and globular particles similar with native HPV18. The half effective dosage (ED50) and maximum level of neutralizing antibody elicitation were measured by vaccinations on mice, rabbit and goat using pseudovirus neutralization cell model. The results showed that the ED50 of HPV18 VLPs is 0.006 microg in mice, and the maximum titer of neutralizing antibody elicited in rabbit and goat is up to 10(7). As a conclusion, we can provide HPV18 VLPs with highly immunogenicity from prokaryote expression system, which may pave a new way for research and development of prophylactic vaccine for HPV18.

We produced high pathogenic avian influenza H5N1 haemagglutinin protein HA1 in recombinant Pichia pastoris in a 10 L fermentor, to establish a high-density cell fermentation method. We studied the effects of different factors such as culture temperature, induced temperature, methanol feeding methods, trace elements on the growth of Pichia pastoris, the yield and the biologic activity of recombinant HA1 protein. The culture temperature in pre-induced and induced stage were optimized at 25 degrees C to adapt cell growth and recombinant protein expression, and induced temperature at 25 degrees C also resulted in higher biologic activity of rHA1 than at 30 degrees C. The binding activity of rHA1 against a wide-spectrum neutralizing antibody was susceptible to the presence of any trace elements, although trace elements would essentially benefit for the cell fermentation. As a conclusion, the expression level of rHA1 produced with optimized fermentation process reached 120 mg/L, which was 10.5 times higher than the one produced in regular shaking flask. The resultant high-density cell fermentation can likely produce rHA1 of H5N1 in large scale.