Heterogeneity of biological samples is usually considered a major obstacle for three-dimensional (3D) structure determination of macromolecular complexes. Heterogeneity may occur at the level of composition or conform...Heterogeneity of biological samples is usually considered a major obstacle for three-dimensional (3D) structure determination of macromolecular complexes. Heterogeneity may occur at the level of composition or conformational variability of complexes and affects most 3D structure determination methods that rely on signal averaging. Here, an approach is described that allows sorting structural states based on a 3D statistical approach, the 3D sampling and classification (3D-SC) of 3D structures derived from single particles imaged by cryo electron microscopy (cryo-EM). The method is based on jackknifing & bootstrapping of 3D sub-ensembles and 3D multivariate statistical analysis followed by 3D classification. The robustness of the statistical sorting procedure is corroborated using model data from an RNA polymerase structure and experimental data from a ribosome complex. It allows resolving multiple states within heterogeneous complexes that thus become amendable for a structural analysis despite of their highly flexible nature. The method has important implications for high-resolution structural studies and allows describing structure ensembles to provide insights into the dynamics of multi-component macromolecular assemblies.展开更多
This study focuses on the seismic fragility analysis of arch dams.The multiple stripe analysis(MSA),cloud analysis(CLA),and incremental dynamic analysis(IDA)methods are compared.A comprehensive dam-reservoir-foundatio...This study focuses on the seismic fragility analysis of arch dams.The multiple stripe analysis(MSA),cloud analysis(CLA),and incremental dynamic analysis(IDA)methods are compared.A comprehensive dam-reservoir-foundation rock system,which considers the opening of contraction joints,the nonlinearity of dam concrete and foundation rock,the radiation damping effect of semi-unbounded foundation,and the compressibility of reservoir water,is used as a numerical example.225,80,and 15 earthquake records are selected for MSA,CLA,and IDA,respectively.The results show that MSA provides satisfactory fragility analysis,while both CLA and IDA have assumptions that may lead to deviations.Therefore,MSA is the most reliable method among the three methods and is recommended for the fragility analysis of arch dams.It is also shown that the choice of demand level affects the reliability of fragility curves and the effect of the material uncertainty on the fragility of the dam is not significant.展开更多
采用感官定量描述分析法(SQDA)对A(JA1~JA3)、B(JB1~JB3)、C(JC1~JC3)三组复合香型白酒9个样品的风味结构进行分析,结果表明:三组复合香型白酒在香气评分上差异不显著,粮香、焦香、麦芽香突出,在口感评分上差异显著,A组白酒各维度口感...采用感官定量描述分析法(SQDA)对A(JA1~JA3)、B(JB1~JB3)、C(JC1~JC3)三组复合香型白酒9个样品的风味结构进行分析,结果表明:三组复合香型白酒在香气评分上差异不显著,粮香、焦香、麦芽香突出,在口感评分上差异显著,A组白酒各维度口感评分高于其他两组。采用顶空-气相色谱质谱联用技术(HS-GC-MS)对3种白酒挥发性化合物组成进行检测分析,共检测到148种挥发性物质。相关性分析结果显示,异丁醛、3-甲基呋喃、二甲基二硫醚、巴豆酸、环氧丙烷、丙烯醛和草酸只在A组白酒中被检测出来,丁酸乙酯在B组白酒中含量最高,JA3中含量偏低,表明3组白酒样品间存在明显的风味物质种类和含量差异。同步结合特征差异代谢物分析挖掘出74个VIP>1的潜在差异代谢物,A vs B组、A vs C组、B vs C组分别有14种、7种、4种化合物呈现极显著性差异(p<0.01),这些含量具有显著差异性的化合物可能与复合香型白酒风味特征的差异具有重要联系。综上所述,本研究采用两种技术协同分析,获得了3种白酒更全面的挥发性风味信息,解析了三组复合香型白酒的风味结构特征及差异,为深入研究复合香型白酒风味形成的机理奠定了基础。展开更多
A cloud method for generating percentile engineering demand parameter versus intensity measure(EDP-IM) curves of a structure subjected to a set of synthetic ground motions is presented. To this end, an ensemble of syn...A cloud method for generating percentile engineering demand parameter versus intensity measure(EDP-IM) curves of a structure subjected to a set of synthetic ground motions is presented. To this end, an ensemble of synthetic ground motions based on available real ones is generated. This is done by using attenuation relationships, duration and suitable Gutenberg-Richter relations attributed to the considered seismic hazard at a given site by estimating a suitable distribution of magnitude and site to source distance. The study aims to clarify the significance of the duration and frequency content on the seismic performance of structures, which were not considered in developing percentile incremental dynamic analysis(IDA) curves. The collapse probabilities of two steel moment-resisting frames with different ductility levels generated by IDA and the proposed cloud method are compared at different intensity levels. When compared with conventional IDA, the suggested cloud analysis(SCA) methodology with the same run number of dynamic analyses was able to develop response hazard curves that were more consistent with site-specific seismic hazards. Eliminating the need to find many real records by generating synthetic records consistent with site-specific seismic hazards from a few available recorded ground motions is another advantage of using this scheme over the IDA method..展开更多
文摘Heterogeneity of biological samples is usually considered a major obstacle for three-dimensional (3D) structure determination of macromolecular complexes. Heterogeneity may occur at the level of composition or conformational variability of complexes and affects most 3D structure determination methods that rely on signal averaging. Here, an approach is described that allows sorting structural states based on a 3D statistical approach, the 3D sampling and classification (3D-SC) of 3D structures derived from single particles imaged by cryo electron microscopy (cryo-EM). The method is based on jackknifing & bootstrapping of 3D sub-ensembles and 3D multivariate statistical analysis followed by 3D classification. The robustness of the statistical sorting procedure is corroborated using model data from an RNA polymerase structure and experimental data from a ribosome complex. It allows resolving multiple states within heterogeneous complexes that thus become amendable for a structural analysis despite of their highly flexible nature. The method has important implications for high-resolution structural studies and allows describing structure ensembles to provide insights into the dynamics of multi-component macromolecular assemblies.
基金National Natural Science Foundation of China under Grant Nos.51725901 and 52022047the State Key Laboratory of Hydroscience and Hydraulic Engineering under Grant No.2021-KY-04。
文摘This study focuses on the seismic fragility analysis of arch dams.The multiple stripe analysis(MSA),cloud analysis(CLA),and incremental dynamic analysis(IDA)methods are compared.A comprehensive dam-reservoir-foundation rock system,which considers the opening of contraction joints,the nonlinearity of dam concrete and foundation rock,the radiation damping effect of semi-unbounded foundation,and the compressibility of reservoir water,is used as a numerical example.225,80,and 15 earthquake records are selected for MSA,CLA,and IDA,respectively.The results show that MSA provides satisfactory fragility analysis,while both CLA and IDA have assumptions that may lead to deviations.Therefore,MSA is the most reliable method among the three methods and is recommended for the fragility analysis of arch dams.It is also shown that the choice of demand level affects the reliability of fragility curves and the effect of the material uncertainty on the fragility of the dam is not significant.
文摘采用感官定量描述分析法(SQDA)对A(JA1~JA3)、B(JB1~JB3)、C(JC1~JC3)三组复合香型白酒9个样品的风味结构进行分析,结果表明:三组复合香型白酒在香气评分上差异不显著,粮香、焦香、麦芽香突出,在口感评分上差异显著,A组白酒各维度口感评分高于其他两组。采用顶空-气相色谱质谱联用技术(HS-GC-MS)对3种白酒挥发性化合物组成进行检测分析,共检测到148种挥发性物质。相关性分析结果显示,异丁醛、3-甲基呋喃、二甲基二硫醚、巴豆酸、环氧丙烷、丙烯醛和草酸只在A组白酒中被检测出来,丁酸乙酯在B组白酒中含量最高,JA3中含量偏低,表明3组白酒样品间存在明显的风味物质种类和含量差异。同步结合特征差异代谢物分析挖掘出74个VIP>1的潜在差异代谢物,A vs B组、A vs C组、B vs C组分别有14种、7种、4种化合物呈现极显著性差异(p<0.01),这些含量具有显著差异性的化合物可能与复合香型白酒风味特征的差异具有重要联系。综上所述,本研究采用两种技术协同分析,获得了3种白酒更全面的挥发性风味信息,解析了三组复合香型白酒的风味结构特征及差异,为深入研究复合香型白酒风味形成的机理奠定了基础。
文摘A cloud method for generating percentile engineering demand parameter versus intensity measure(EDP-IM) curves of a structure subjected to a set of synthetic ground motions is presented. To this end, an ensemble of synthetic ground motions based on available real ones is generated. This is done by using attenuation relationships, duration and suitable Gutenberg-Richter relations attributed to the considered seismic hazard at a given site by estimating a suitable distribution of magnitude and site to source distance. The study aims to clarify the significance of the duration and frequency content on the seismic performance of structures, which were not considered in developing percentile incremental dynamic analysis(IDA) curves. The collapse probabilities of two steel moment-resisting frames with different ductility levels generated by IDA and the proposed cloud method are compared at different intensity levels. When compared with conventional IDA, the suggested cloud analysis(SCA) methodology with the same run number of dynamic analyses was able to develop response hazard curves that were more consistent with site-specific seismic hazards. Eliminating the need to find many real records by generating synthetic records consistent with site-specific seismic hazards from a few available recorded ground motions is another advantage of using this scheme over the IDA method..
