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Groove, as a special structure at the front of solid–liquid (S/L) interface, takes a great influence on the distribution of impurities for silicon. In this work, the interaction between grooves and impurities was studied, and the evolution model of groove was proposed. It has been found that the crystal growth rate and the impurity content in the groove determine the evolution behavior of the groove. Correspondingly, the migration behavior of impurities in groove with solidification was studied and the mathematical model was proposed to describe the anomalous enrichment phenomenon. This work is helpful to understand the distribution behavior of impurities in micro-zone such as groove and make a theoretical foundation for the deep removal of impurities.

BackgroundHeterologous booster vaccines are more effective than homologous booster vaccines in combating the coronavirus disease 2019 (COVID-19) outbreak. However, our understanding of homologous and heterologous booster vaccines for COVID-19 remains limited.MethodsWe recruited 34 healthy participants from two cohorts who were primed with two-dose inactivated COVID-19 vaccine before, vaccinated with COVID-19 inactivated vaccine and adenovirus-vectored vaccine (intramuscular and aerosol inhalation of Ad5-nCoV) as a third booster dose. We assessed the immune responses of participants before and 14 days after vaccination, including levels of neutralizing antibodies, IgG, and cytokines, and quantified the transcriptional profile of peripheral blood mononuclear cells (PBMCs).ResultsThe Ad5-nCoV group showed a significantly higher neutralizing antibody geometric mean titer (GMT) compared to the ICV group after 14 days of heterologous boosting. The intramuscular Ad5-nCoV group had a GMT of 191.8 (95% CI 129.0, 285.1) compared to 38.1 (95% CI 23.1, 62.8) in the ICV1 group (p

Abstract. The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to scale up around the world, costing severe health and economic losses. The development of an effective COVID-19 vaccine is of utmost importance. Most vaccine designs can be classified into three camps: protein based (inactivated vaccines, protein subunit, VLP and T-cell based vaccines), gene based (DNA or RNA vaccines, replicating or non-replicating viral/bacterial vectored vaccines), and a combination of both protein-based and gene-based (live-attenuated virus vaccines). Up to now, 237 candidate vaccines against SARS-CoV-2 are in development worldwide, of which 63 have been approved for clinical trials and 27 are evaluated in phase 3 clinical trials. Six candidate vaccines have been authorized for emergency use or conditional licensed, based on their efficacy data in phase 3 trials. This review summarizes the strengths and weaknesses of the candidate COVID-19 vaccines from various platforms, compares, and discusses their protective efficacy, safety, and immunogenicity according to the published clinical trials results.

Under the combined impacts of climate change and human activities, a series of water issues, such as water shortages, have arisen all over the world. According to current studies in Science and Nature, water security has become a frontier critical topic. Water supply security (WSS), which is the state of water resources and their capacity and their capacity to meet the demand of water users by water supply systems, is an important part of water security. Currently, WSS is affected by the amount of water resources, water supply projects, water quality and water management. Water shortages have also led to water supply insecurity. WSS is now evaluated based on the balance of the supply and demand under a single water resources condition without considering the dynamics of the varying conditions of water resources each year. This paper developed an optimal allocation model for water resources that can realize the optimal allocation of regional water resources and comprehensively evaluate WSS. The objective of this model is to minimize the duration of water shortages in the long term, as characterized by the Water Supply Security Index (WSSI), which is the assessment value of WSS, a larger WSSI value indicates better results. In addition, the simulation results of the model can determine the change process and dynamic evolution of the WSS. Quanzhou, a city in China with serious water shortage problems, was selected as a case study. The allocation results of the current year and target year of planning demonstrated that the level of regional comprehensive WSS was significantly influenced by the capacity of water supply projects and the conditions of the natural water resources. The varying conditions of the water resources allocation results in the same year demonstrated that the allocation results and WSSI were significantly affected by reductions in precipitation, decreases in the water yield coefficient, and changes in the underlying surface. [ABSTRACT FROM AUTHOR]

An experimental investigation into the removal of aluminum (Al) and calcium (Ca) from molten silicon by using electron beam melting was carried out. Based on the distributions of Al and Ca along the growth direction of the ingot under different solidification conditions, the influence of segregation and evaporation behaviors on the removal of such impurities with both high saturated vapor pressure and low segregation coefficients was investigated. The results showed that the distributions of impurities depend upon the interaction between segregation and evaporation, so that the removal efficiency can be further improved by adjusting the melting parameters. Compared with the traditional electron beam melting process, the energy consumption decreases by 20% during the whole melting and solidification process. It is considered to be a more effective way for the purification of silicon and the reduction of energy consumption by electron beam melting. [ABSTRACT FROM AUTHOR]