During the process of landslide, its dynamic mechanism is important to understand and predict these kinds of natural hazard. In this paper, a new method, based on concepts of complex networks, has been proposed to inv...During the process of landslide, its dynamic mechanism is important to understand and predict these kinds of natural hazard. In this paper, a new method, based on concepts of complex networks, has been proposed to investigate the evolution of contact networks in mesoscale during the sliding process of slope. A slope model was established using the discrete element method (DEM), and influences of inter-particle frictional coefficients with four different values on?dynamic landslides were studied. Both macroscopic analysis on slope?landslide?and mesoanalysis on structure evolution of contact networks, including the?average degree, clustering coefficient?and N-cycle, were done during the process?of landslide. The analysis results demonstrate that: 1) with increasing inter-particle?frictional coefficients, the displacement of slope decreases and the stable angle of slope post-failure increases, which is smaller than the peak internal frictional angle;2) the average degree decreases with the increase of inter-particle frictional coefficient. When the displacement at the toe of the slope is smaller,?the average degree there changes more greatly with increasing inter-particle?frictional coefficient;3) during the initial stage of landslide, the clustering coefficient?reduces sharply, which may leads to easily slide of slope. As the landslide?going?on, however, the clustering coefficient?increases denoting increasing stability?with?increasing inter-particle frictional coefficients. When the inter-particle?frictional coefficient is smaller than 0.3, its variation can affect the clustering coefficient?and stable inclination of slope post-failure greatly;and 4) the number of?3-cycle increases, but 4-cycle and 5-cycle decrease with increasing inter-particle frictional coefficients.展开更多
The coronavirus disease 2019(COVID-19)pandemic has highlighted the importance of developing novel vaccines.An ideal vaccine should trigger an intense immune reaction without causing significant side effects.In this st...The coronavirus disease 2019(COVID-19)pandemic has highlighted the importance of developing novel vaccines.An ideal vaccine should trigger an intense immune reaction without causing significant side effects.In this study we found that substitution of tryptophan located in the cores of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)protein structures with certain smaller amino acids resulted in variants with melting temperatures of 33-37℃.An enzyme activity assay indicated that the proteolytic activity of the main proteinase(3CLpro)decreased sharply when the environmental temperature exceeded the melting temperature,implying that other protein variants may lose most of their functions under the same conditions.This finding suggests that a virus variant containing engineered proteins with melting temperatures of 33-37℃ may only be functional in the upper respiratory tract where the temperature is about 33℃,but will be unable to invade internal organs,which maintain temperatures above 37℃,thus making it possible to construct temperature-sensitive attenuated vaccines.展开更多
文摘During the process of landslide, its dynamic mechanism is important to understand and predict these kinds of natural hazard. In this paper, a new method, based on concepts of complex networks, has been proposed to investigate the evolution of contact networks in mesoscale during the sliding process of slope. A slope model was established using the discrete element method (DEM), and influences of inter-particle frictional coefficients with four different values on?dynamic landslides were studied. Both macroscopic analysis on slope?landslide?and mesoanalysis on structure evolution of contact networks, including the?average degree, clustering coefficient?and N-cycle, were done during the process?of landslide. The analysis results demonstrate that: 1) with increasing inter-particle?frictional coefficients, the displacement of slope decreases and the stable angle of slope post-failure increases, which is smaller than the peak internal frictional angle;2) the average degree decreases with the increase of inter-particle frictional coefficient. When the displacement at the toe of the slope is smaller,?the average degree there changes more greatly with increasing inter-particle?frictional coefficient;3) during the initial stage of landslide, the clustering coefficient?reduces sharply, which may leads to easily slide of slope. As the landslide?going?on, however, the clustering coefficient?increases denoting increasing stability?with?increasing inter-particle frictional coefficients. When the inter-particle?frictional coefficient is smaller than 0.3, its variation can affect the clustering coefficient?and stable inclination of slope post-failure greatly;and 4) the number of?3-cycle increases, but 4-cycle and 5-cycle decrease with increasing inter-particle frictional coefficients.
基金funding from the Shandong Provincial Key Research and Development Program (2020CXGC011305).
文摘The coronavirus disease 2019(COVID-19)pandemic has highlighted the importance of developing novel vaccines.An ideal vaccine should trigger an intense immune reaction without causing significant side effects.In this study we found that substitution of tryptophan located in the cores of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)protein structures with certain smaller amino acids resulted in variants with melting temperatures of 33-37℃.An enzyme activity assay indicated that the proteolytic activity of the main proteinase(3CLpro)decreased sharply when the environmental temperature exceeded the melting temperature,implying that other protein variants may lose most of their functions under the same conditions.This finding suggests that a virus variant containing engineered proteins with melting temperatures of 33-37℃ may only be functional in the upper respiratory tract where the temperature is about 33℃,but will be unable to invade internal organs,which maintain temperatures above 37℃,thus making it possible to construct temperature-sensitive attenuated vaccines.
