目的:建立百合药材高效液相色谱法(HPLC)指纹图谱及王百合苷B、王百合苷C、王百合苷E的定量方法,对不同产地百合的质量进行较全面评价。方法:采用Agilent Eclipse Plus C 18色谱柱(250 mm×4.6 mm,5μm),以乙腈-0.3%磷酸水溶液为流...目的:建立百合药材高效液相色谱法(HPLC)指纹图谱及王百合苷B、王百合苷C、王百合苷E的定量方法,对不同产地百合的质量进行较全面评价。方法:采用Agilent Eclipse Plus C 18色谱柱(250 mm×4.6 mm,5μm),以乙腈-0.3%磷酸水溶液为流动相梯度洗脱,指纹图谱及含量测定检测波长为250 nm,柱温为30℃,体积流量为1.0 mL·min^(-1)。采用相似度评价(SA)、主成分分析(PCA)、随机森林分析(RFA)对21批百合药材指纹图谱进行研究。结果:建立了百合药材的HPLC指纹图谱,确定了31个共有峰;相似度和PCA结果显示,不同产地百合存在差异,进而利用随机森林算法将湖南产区和其他4个主要产地的百合样品进行区分。结论:可为全面、有效评价百合药材的质量提供参考。展开更多
The cause and treatment of rail corrugation for the metro have always been a popular and challenging issue. In this work, the field measurements were carried out on rail corrugation, track stiffness, and the track dyn...The cause and treatment of rail corrugation for the metro have always been a popular and challenging issue. In this work, the field measurements were carried out on rail corrugation, track stiffness, and the track dynamic response. A three-dimensional finite element model was developed to investigate the cause of rail corrugation. The constraints on rail vibration from two wheelsets and adjacent wheel-rail interactions were taken into account in the model. According to experimental and simulation results, the suppression measure for rail corrugation was proposed and the suppression mechanism was discussed. It was found that the cause of rail corrugation is related to vertical and lateral vibration of the rails outside the two wheelsets at around 380 Hz. The increased stiffness of the fasteners reduces the vibration energy of the rail and the wheel-rail force. However, simply increasing the stiffness of the fasteners may not be effective in the suppression of rail corrugation. If necessary, the rails need to be grinded to reduce the roughness to a certain level, so that increasing the fastener stiffness can effectively suppress the rail corrugation.展开更多
文摘目的:建立百合药材高效液相色谱法(HPLC)指纹图谱及王百合苷B、王百合苷C、王百合苷E的定量方法,对不同产地百合的质量进行较全面评价。方法:采用Agilent Eclipse Plus C 18色谱柱(250 mm×4.6 mm,5μm),以乙腈-0.3%磷酸水溶液为流动相梯度洗脱,指纹图谱及含量测定检测波长为250 nm,柱温为30℃,体积流量为1.0 mL·min^(-1)。采用相似度评价(SA)、主成分分析(PCA)、随机森林分析(RFA)对21批百合药材指纹图谱进行研究。结果:建立了百合药材的HPLC指纹图谱,确定了31个共有峰;相似度和PCA结果显示,不同产地百合存在差异,进而利用随机森林算法将湖南产区和其他4个主要产地的百合样品进行区分。结论:可为全面、有效评价百合药材的质量提供参考。
基金Project(52178405) supported by the National Natural Science Foundation of ChinaProject(Z191100002519010) supported by the Project of Beijing Municipal Science&Technology Plan,ChinaProjects(2018JBZ003, 2020JBZD013) supported by the Fundamental Research Funds for the Central Universities,China。
文摘The cause and treatment of rail corrugation for the metro have always been a popular and challenging issue. In this work, the field measurements were carried out on rail corrugation, track stiffness, and the track dynamic response. A three-dimensional finite element model was developed to investigate the cause of rail corrugation. The constraints on rail vibration from two wheelsets and adjacent wheel-rail interactions were taken into account in the model. According to experimental and simulation results, the suppression measure for rail corrugation was proposed and the suppression mechanism was discussed. It was found that the cause of rail corrugation is related to vertical and lateral vibration of the rails outside the two wheelsets at around 380 Hz. The increased stiffness of the fasteners reduces the vibration energy of the rail and the wheel-rail force. However, simply increasing the stiffness of the fasteners may not be effective in the suppression of rail corrugation. If necessary, the rails need to be grinded to reduce the roughness to a certain level, so that increasing the fastener stiffness can effectively suppress the rail corrugation.
