为明确白及初加工过程中多菌灵、三唑酮、戊唑醇和苯醚甲环唑的残留变化规律和加工因子,在实验室条件下,模拟白及的清洗、水煮和烘干3个初加工过程,采用超高效液相色谱串联质谱法(ultra high performance liquid chromatography-tandem ...为明确白及初加工过程中多菌灵、三唑酮、戊唑醇和苯醚甲环唑的残留变化规律和加工因子,在实验室条件下,模拟白及的清洗、水煮和烘干3个初加工过程,采用超高效液相色谱串联质谱法(ultra high performance liquid chromatography-tandem mass spectrometry,UHPLC-MS/MS)检测白及初加工各阶段的农药残留浓度,并计算加工因子。结果表明,白及不同加工过程对4种杀菌剂残留浓度的影响差异较大。清洗过程使农药残留浓度降低4.6%~57.8%,加工因子为0.42~0.95,在清水中分别添加质量分数2%淀粉、2%食盐和2%小苏打对农药的去除效果可提升1.4~7.3倍;水煮过程使农药残留浓度降低38.6%~67.8%,加工因子为0.32~0.61;烘干过程由于浓缩效应使农药残留浓度升高2.1~3.2倍,加工因子为2.08~3.23。白及依次经2%食盐水清洗、水煮4 min、60℃烘干的初加工全过程对4种杀菌剂的降解作用大于因脱水造成的浓缩作用,可降低4种杀菌剂在干白及产品中的残留风险,全过程加工因子为0.34~0.67。因此,以鲜白及中4种杀菌剂残留评价经此初加工后干白及中4种杀菌剂残留的安全性是可行的,研究结果可为白及产品的安全风险评估提供基础数据参考。展开更多
A bidirectional ribbed concrete beam slab structure was widly adopted for the upper space of industrial buildings.To maintain ample space and minimize the presence of conventional columns,a bidirectional prestressed c...A bidirectional ribbed concrete beam slab structure was widly adopted for the upper space of industrial buildings.To maintain ample space and minimize the presence of conventional columns,a bidirectional prestressed concrete beam is often employed.The intersection node of the prestressed concrete frame beam column was characterized by a high density of steel reinforcement,significant structural loads,and complex construction requirements.To ensure the quality,safety,and progress of prestressed frame beamcolumn intersection nodes during construction,this article proposed a new technology for constructing such nodes,which includes setting the tensioning and haunching ends of nodes at different positions,using ABAQUS finite element software to optimize the design of cross-sectional dimensions,conducting stress analysis simulations.展开更多
This work aims at online calibration of signal attenuation of the long cable used in Tibet water Cherenkov muon detector array-A (Tibet MD-A) under the Tibet air shower array.Based on a waterproof connection of the si...This work aims at online calibration of signal attenuation of the long cable used in Tibet water Cherenkov muon detector array-A (Tibet MD-A) under the Tibet air shower array.Based on a waterproof connection of the signal cable to PMT (R3600_06) and characters of the high voltage divider,terminal reflection method is used for measuring the signal attenuation with a practical way to eliminate contribution of the pulse baseline.Comparison measurement data-taking method (with charge-to-digital conversion) was carried out by using open-ended cables,confirming that terminal reflection method is a fast and convenient,and suitable to online calibration of the signal attenuation for Tibet MD-A.At 26℃,the measured attenuation coefficient with the 250-m cable connected permanently to the PMT,was ～13.9%.The cable frequency response was measured by using the sinusoidal signals.The method could be used to study time dispersion of signals produced with Tibet MD-A detector via Fourier analysis.展开更多
文摘为明确白及初加工过程中多菌灵、三唑酮、戊唑醇和苯醚甲环唑的残留变化规律和加工因子,在实验室条件下,模拟白及的清洗、水煮和烘干3个初加工过程,采用超高效液相色谱串联质谱法(ultra high performance liquid chromatography-tandem mass spectrometry,UHPLC-MS/MS)检测白及初加工各阶段的农药残留浓度,并计算加工因子。结果表明,白及不同加工过程对4种杀菌剂残留浓度的影响差异较大。清洗过程使农药残留浓度降低4.6%~57.8%,加工因子为0.42~0.95,在清水中分别添加质量分数2%淀粉、2%食盐和2%小苏打对农药的去除效果可提升1.4~7.3倍;水煮过程使农药残留浓度降低38.6%~67.8%,加工因子为0.32~0.61;烘干过程由于浓缩效应使农药残留浓度升高2.1~3.2倍,加工因子为2.08~3.23。白及依次经2%食盐水清洗、水煮4 min、60℃烘干的初加工全过程对4种杀菌剂的降解作用大于因脱水造成的浓缩作用,可降低4种杀菌剂在干白及产品中的残留风险,全过程加工因子为0.34~0.67。因此,以鲜白及中4种杀菌剂残留评价经此初加工后干白及中4种杀菌剂残留的安全性是可行的,研究结果可为白及产品的安全风险评估提供基础数据参考。
基金Funded by the Nantong Science and Technology Plan Project(No.JC2021172)the Cyan and Blue Project of Universities in Jiangsu Province。
文摘A bidirectional ribbed concrete beam slab structure was widly adopted for the upper space of industrial buildings.To maintain ample space and minimize the presence of conventional columns,a bidirectional prestressed concrete beam is often employed.The intersection node of the prestressed concrete frame beam column was characterized by a high density of steel reinforcement,significant structural loads,and complex construction requirements.To ensure the quality,safety,and progress of prestressed frame beamcolumn intersection nodes during construction,this article proposed a new technology for constructing such nodes,which includes setting the tensioning and haunching ends of nodes at different positions,using ABAQUS finite element software to optimize the design of cross-sectional dimensions,conducting stress analysis simulations.
基金supported by the National Natural Science Foundation of China (No.111 072552430)the Key Laboratory of Particle Astrophysics,Institute of High Energy Physics,Chinese Academy of Sciences
文摘This work aims at online calibration of signal attenuation of the long cable used in Tibet water Cherenkov muon detector array-A (Tibet MD-A) under the Tibet air shower array.Based on a waterproof connection of the signal cable to PMT (R3600_06) and characters of the high voltage divider,terminal reflection method is used for measuring the signal attenuation with a practical way to eliminate contribution of the pulse baseline.Comparison measurement data-taking method (with charge-to-digital conversion) was carried out by using open-ended cables,confirming that terminal reflection method is a fast and convenient,and suitable to online calibration of the signal attenuation for Tibet MD-A.At 26℃,the measured attenuation coefficient with the 250-m cable connected permanently to the PMT,was ～13.9%.The cable frequency response was measured by using the sinusoidal signals.The method could be used to study time dispersion of signals produced with Tibet MD-A detector via Fourier analysis.
