After a brief review of studies on artificial boundaries in dynamic soil-structure interaction, a three-dimensional viscous-spring artificial boundary （VSAB） in the time domain is developed in this paper. First, the...After a brief review of studies on artificial boundaries in dynamic soil-structure interaction, a three-dimensional viscous-spring artificial boundary （VSAB） in the time domain is developed in this paper. First, the 3D VSAB equations in the normal and tangential directions are derived based on the elastic wave motion theory. Secondly, a numerical simulation technique of wave motion equations along with the VSAB condition in the time domain is studied. Finally, numerical examples of some classical elastic wave motion problems are presented and the results are compared with the associated theoretical solutions, demonstrating that high precision and adequate stability can be achieved by using the proposed 3D VSAB. The proposed 3D VSAB can be conveniently incorporated in the general finite element program, which is commonly used to study dynamic soil-structure interaction problems.展开更多
The outbreak of coronavirus disease(COVID-19)caused by SARS-CoV-2 virus continually lead to worldwide human infections and deaths.Currently,there is no specific viral protein-targeted therapeutics.Viral nucleocapsid p...The outbreak of coronavirus disease(COVID-19)caused by SARS-CoV-2 virus continually lead to worldwide human infections and deaths.Currently,there is no specific viral protein-targeted therapeutics.Viral nucleocapsid protein is a potential antiviral drug target,serving multiple critical functions during the viral life cycle.However,the structural information of SARS-CoV-2 nucleocapsid protein remains unclear.Herein,we have determined the 2.7 A crystal structure of the N-terminal RNA binding domain of SARS-CoV-2 nucleocapsid protein.Although the overall structure is similar as other reported coronavirus nucleocapsid protein N-terminal domain,the surface electrostatic potential characteristics between them are distinct.Further comparison with mild virus type HCoV-OC43 equivalent domain demonstrates a unique potential RNA binding pocket alongside theβ-sheet core.Complemented by in vitro binding studies,our data provide several atomic resolution features of SARS-CoV-2 nucleocapsid protein N-terminal domain,guiding the design of novel antiviral agents specific targeting to SARS-CoV-2.展开更多
Highly ordered Bi4Si3O12 micro-crystals were prepared at normal atmosphere. Phase identification of the prepared crystals was accomplished by X-ray diffractometer (XRD). Domain structure and defects were characterized...Highly ordered Bi4Si3O12 micro-crystals were prepared at normal atmosphere. Phase identification of the prepared crystals was accomplished by X-ray diffractometer (XRD). Domain structure and defects were characterized by environmental scanning electron microscopy (ESEM). XRD shows that the obtained micro-crystals are of eulytite structure with chemical formulation of Bi4Si3O12. A highly ordered growth pattern is confirmed due to the faster growth of the {124} faces than that of the {204} faces by ESEM. The growing process of the domain structure is of pollen parent and filial generation pattern. The filial generations of Bi4Si3O12 crystals are generated from the pollen parent. Cracks generate from the defect areas and propagate along the {124} faces due to their lower binding energy under a proper temperature gradient, contributing to the total transcrystalline fracture. It is confirmed that the generation and development of the voids in the crystal grains can be developed when unmatched dimensions of the two opposite faces are formed. And the development of the voids is dependent on the dimensions and orientations of the two opposite faces.展开更多
LATERAL ORGAN BOUNDARIES DOMAIN(LBD)基因家族是在拟南芥中发现的高等植物所特有的一类基因,编码的蛋白中含有LATERAL ORGAN BOUNDARIES(LOB)结构域。LBD基因一般在侧生器官与茎尖分生组织的边界处、侧生器官的近轴面一侧的基部表达,...LATERAL ORGAN BOUNDARIES DOMAIN(LBD)基因家族是在拟南芥中发现的高等植物所特有的一类基因,编码的蛋白中含有LATERAL ORGAN BOUNDARIES(LOB)结构域。LBD基因一般在侧生器官与茎尖分生组织的边界处、侧生器官的近轴面一侧的基部表达,并呈现出在多种组织内特异性表达的特征,暗示该类基因可能在植物的多种发育过程中发挥功能。LBD蛋白结构中除含有上述LOB结构域以外,尚未发现其它已知功能的结构域的存在。目前,已经在拟南芥中发现43个LBD基因,而在玉米和水稻中各有35和43个LBD基因。根据LBD蛋白结构中是否含有亮氨酸拉链类似基序,将LBD基因分为两类:第一类(class I)LBD蛋白结构域中包含完整亮氨酸拉链基序;第二类(class II)LBD蛋白结构域中不含亮氨酸拉链基序。本文就LBD基因的结构以及它们对高等植物生长发育的影响、LBD基因和植物激素的关系、LBD基因与miRNA的关系进行了系统的总结。展开更多
基金National Natural Science Foundation of ChinaUnder Grant No.50478014Special Funds for Major State Basic Research Project Under Grant No.2002CB412706Research Funds from National Civil Defense Oficce of Chinafor the Tenth Five-year Plan。
文摘After a brief review of studies on artificial boundaries in dynamic soil-structure interaction, a three-dimensional viscous-spring artificial boundary （VSAB） in the time domain is developed in this paper. First, the 3D VSAB equations in the normal and tangential directions are derived based on the elastic wave motion theory. Secondly, a numerical simulation technique of wave motion equations along with the VSAB condition in the time domain is studied. Finally, numerical examples of some classical elastic wave motion problems are presented and the results are compared with the associated theoretical solutions, demonstrating that high precision and adequate stability can be achieved by using the proposed 3D VSAB. The proposed 3D VSAB can be conveniently incorporated in the general finite element program, which is commonly used to study dynamic soil-structure interaction problems.
基金supported by National Natural Science Foundation of China(31770801)Special Fund for Scientific and Technological Innovation Strategy of Guangdong Province of China(2018B030306029 and 2017A030313145)+2 种基金National Natural Science Foundation of China(81430041,81620108017)National Key Basic Research Program,China(SQ2018YFC090075)National Natural Science Foundation of China(81870019)
文摘The outbreak of coronavirus disease(COVID-19)caused by SARS-CoV-2 virus continually lead to worldwide human infections and deaths.Currently,there is no specific viral protein-targeted therapeutics.Viral nucleocapsid protein is a potential antiviral drug target,serving multiple critical functions during the viral life cycle.However,the structural information of SARS-CoV-2 nucleocapsid protein remains unclear.Herein,we have determined the 2.7 A crystal structure of the N-terminal RNA binding domain of SARS-CoV-2 nucleocapsid protein.Although the overall structure is similar as other reported coronavirus nucleocapsid protein N-terminal domain,the surface electrostatic potential characteristics between them are distinct.Further comparison with mild virus type HCoV-OC43 equivalent domain demonstrates a unique potential RNA binding pocket alongside theβ-sheet core.Complemented by in vitro binding studies,our data provide several atomic resolution features of SARS-CoV-2 nucleocapsid protein N-terminal domain,guiding the design of novel antiviral agents specific targeting to SARS-CoV-2.
基金Supported by the Innovation Research Team Funds of Shaanxi University of Science & Technology (Grant No. SUST-A04)
文摘Highly ordered Bi4Si3O12 micro-crystals were prepared at normal atmosphere. Phase identification of the prepared crystals was accomplished by X-ray diffractometer (XRD). Domain structure and defects were characterized by environmental scanning electron microscopy (ESEM). XRD shows that the obtained micro-crystals are of eulytite structure with chemical formulation of Bi4Si3O12. A highly ordered growth pattern is confirmed due to the faster growth of the {124} faces than that of the {204} faces by ESEM. The growing process of the domain structure is of pollen parent and filial generation pattern. The filial generations of Bi4Si3O12 crystals are generated from the pollen parent. Cracks generate from the defect areas and propagate along the {124} faces due to their lower binding energy under a proper temperature gradient, contributing to the total transcrystalline fracture. It is confirmed that the generation and development of the voids in the crystal grains can be developed when unmatched dimensions of the two opposite faces are formed. And the development of the voids is dependent on the dimensions and orientations of the two opposite faces.
文摘LATERAL ORGAN BOUNDARIES DOMAIN(LBD)基因家族是在拟南芥中发现的高等植物所特有的一类基因,编码的蛋白中含有LATERAL ORGAN BOUNDARIES(LOB)结构域。LBD基因一般在侧生器官与茎尖分生组织的边界处、侧生器官的近轴面一侧的基部表达,并呈现出在多种组织内特异性表达的特征,暗示该类基因可能在植物的多种发育过程中发挥功能。LBD蛋白结构中除含有上述LOB结构域以外,尚未发现其它已知功能的结构域的存在。目前,已经在拟南芥中发现43个LBD基因,而在玉米和水稻中各有35和43个LBD基因。根据LBD蛋白结构中是否含有亮氨酸拉链类似基序,将LBD基因分为两类:第一类(class I)LBD蛋白结构域中包含完整亮氨酸拉链基序;第二类(class II)LBD蛋白结构域中不含亮氨酸拉链基序。本文就LBD基因的结构以及它们对高等植物生长发育的影响、LBD基因和植物激素的关系、LBD基因与miRNA的关系进行了系统的总结。
