A Modified Calculation Method for a Centered Water Nozzle Steam–Water Injector

A centered water nozzle steam–water injector is driven by cold water to pump steam at a low pressure and to produce a high outlet water pressure. It can be used as a safety pump in a light water reactor to inject cooling water into the reactor core with no power supply in case of an accident. In this study, a modified calculation method for a centered water nozzle steam–water injector is proposed and verified by experimental data in the literature. The calculation method consists of a water nozzle model, a steam nozzle model, a mixing section model, and a shock wave model. Comparisons between the calculated results and the experimental results under different inlet steam pressures, inlet water pressures, and back pressures are conducted, and the calculated results show good agreement with the experimental results. The calculated results with different back pressures show that no shock wave occurs in the mixing section when the back pressure is small, but with the back pressure increasing, the pressure undergoes a dramatic increase in the throat tube, and the shock wave position moves towards the inlet of the mixing section. Due to the complexity of shock wave characteristics, it is necessary to conduct a more in-depth study of shock wave characteristics in the mixing section to determine more detailed boundary conditions for shock wave generation

CFD Simulation on Pressure Profile for Direct Contact Condensation of Steam Jet in a Narrow Pipe

In the published experimental results, it has been observed that when high-speed steam spurt into the subcooled waterflow, the total pressure along the axial direction at trailing edge of the steam plume shows a pressure-lift. To reveal the mechanism behind this phenomenon, this study utilizes a particle model to investigate the pressure profile of steam jet condensation in subcooled water flow in a narrow pipe. A numerical model based on the Eulerian–Eulerian multiphase model has been developed to accurately simulate the characteristics of pressure profile along the axial direction. The model’s validity is established by comparing the steam plume shape and temperature profiles with the experimental data. By analyzing the total pressure profile of the axis and the contours of gas volume fraction, it is found that there exists a pressure-lift phenomenon at trailing edge of the steam plume. The dynamic pressure of the water also shows a pressure-lift at this position, so it can be inferred that the dynamic pressure of the water is the main factor of the total pressure-lift

Pre-marketing immunogenicity and safety of a lyophilized purified human diploid cell rabies vaccine produced from microcarrier cultures: a randomized clinical trial

The large-scale production of a human diploid cell (HDC) vaccine (HDCV) for rabies is limited by several technical challenges. Kanghua Biological Products Co., Ltd., has successfully used microcarrier technology for the large-scale culture of HDCs in bioreactors to develop a lyophilized and purified HDCV. In this blinded, randomized, parallel-group study conducted between July and October 2014 in Mianzhu, Sichuan Province, China, we monitored the safety and immunogenicity of this vaccine in a healthy population vaccinated according to the Essen post-exposure immunization schedule. A hamster kidney cell vaccine was used as the control. Adverse reactions were monitored 0.5, 6, 24, 48, and 72 h post vaccination to assess safety. Neutralizing antibodies in venous blood were measured on day 7, 14, and 72 to evaluate the immunogenicity of the vaccine while follow-up monitoring continued for 1 month. No serious adverse reactions were observed in any volunteer. The incidence rates of systemic and local adverse reactions were, respectively, 10.6% and 2.9% in the test group and 20.0% and 13.6% in the control group. After the third injection, the positive conversion rates of antibodies in the test and control groups were 100% and 98.82%, respectively. In addition, the average antibody titers on day 7, 14, and 42, were respectively, 1.71, 2.72, and 1.29 times higher than those in the control group. These results indicate that HDCV had a better safety profile and higher immunogenicity than the hamster kidney cell rabies vaccine. Trial registration number: 20130602

Combining intramuscular and intranasal homologous prime-boost with a chimpanzee adenovirus-based COVID-19 vaccine elicits potent humoral and cellular immune responses in mice

The efficacy of many coronavirus disease 2019 (COVID-19) vaccines has been shown to decrease to varying extents against new severe acute respiratory syndrome coronavirus 2 variants, which are responsible for the continuing COVID-19 pandemic. Combining intramuscular and intranasal vaccination routes is a promising approach for achieving more potent immune responses. We evaluated the immunogenicity of prime-boost protocols with a chimpanzee adenovirus serotype 68 vector-based vaccine, ChAdTS-S, administered via both intranasal and intramuscular routes in BALB/c mice. Intramuscular priming followed by an intranasal booster elicited the highest levels of IgG, IgA, and pseudovirus neutralizing antibody titres among all the protocols tested at day 42 after prime immunization compared with the intranasal priming/intramuscular booster and prime-boost protocols using only one route. In addition, intramuscular priming followed by an intranasal booster induced high T-cell responses, measured using the IFN-γ ELISpot assay, that were similar to those observed upon intramuscular vaccination. All ChAdTS-S vaccination groups induced Th1-skewing of the T-cell response according to intracellular cytokine staining and Meso Scale Discovery cytokine profiling assays on day 56 after priming. This study provides reference data for assessing vaccination schemes of adenovirus-based COVID-19 vaccines with high immune efficacy