Traditional transgenic detection methods require high test conditions and struggle to be both sensitive and efficient.In this study,a one-tube dual recombinase polymerase amplification(RPA)reaction system for CP4-EPSP...Traditional transgenic detection methods require high test conditions and struggle to be both sensitive and efficient.In this study,a one-tube dual recombinase polymerase amplification(RPA)reaction system for CP4-EPSPS and Cry1Ab/Ac was proposed and combined with a lateral flow immunochromatographic assay,named“Dual-RPA-LFD”,to visualize the dual detection of genetically modified(GM)crops.In which,the herbicide tolerance gene CP4-EPSPS and the insect resistance gene Cry1Ab/Ac were selected as targets taking into account the current status of the most widespread application of insect resistance and herbicide tolerance traits and their stacked traits.Gradient diluted plasmids,transgenic standards,and actual samples were used as templates to conduct sensitivity,specificity,and practicality assays,respectively.The constructed method achieved the visual detection of plasmid at levels as low as 100 copies,demonstrating its high sensitivity.In addition,good applicability to transgenic samples was observed,with no cross-interference between two test lines and no influence from other genes.In conclusion,this strategy achieved the expected purpose of simultaneous detection of the two popular targets in GM crops within 20 min at 37°C in a rapid,equipmentfree field manner,providing a new alternative for rapid screening for transgenic assays in the field.展开更多
Based on back analysis of lateral displacements measured in situ by using the analytical solution, a useful method for estimating stress concentration ratio of geosynthetic-reinforced and pile-supported(GRPS) embankme...Based on back analysis of lateral displacements measured in situ by using the analytical solution, a useful method for estimating stress concentration ratio of geosynthetic-reinforced and pile-supported(GRPS) embankments was proposed. In order to validate the proposed method, a full-scale high-speed railway embankment(HSRE) with four instrumented subsections over medium compressibility silty clay was constructed in three stages. The soil profile, construction procedure and monitoring of settlements and lateral displacements of the four test sections were described. The field deformation analysis results show that 1) the combined reinforcement of CFG piles and geosynthetic layer perform well in terms of reducing lateral displacements; 2) the development of lateral displacements lags behind the increase of fill load, which can be attributed to the vertical load transfer mechanism of the pile foundation; and 3) pile length has a dominant effect on the stress distribution proportion between piles and surrounding soils. The comparison between predicted and experimental results suggests that the proposed analytical solution and the back analysis-based method are capable of reasonably estimating the lateral deformation and the stress concentration ratio, respectively, if the appropriate soil elastic modulus is chosen.展开更多
In this work,a novel conjugate of ractopamine and bovine serum albumin(RAC–BSA)has been developed via the Mannich reaction,with a mole coupling ratio for RAC–BSA of 9:1.The proposed conjugation method provides a sim...In this work,a novel conjugate of ractopamine and bovine serum albumin(RAC–BSA)has been developed via the Mannich reaction,with a mole coupling ratio for RAC–BSA of 9:1.The proposed conjugation method provides a simple and one-step method with the use of fewer reagents compared with other conjugation methods for competitive immunoassays.RAC–BSA conjugation was used to fabricate a competitive lateral flow strip test for RAC detection in animal feed.For sample preparation,RAC was spiked in swine feed purchased from the local markets in Thailand,and methanol and running buffer at a volume ratio of 10:90 was used as extraction buffer.The procedures for sample preparation were completed within 25 min.Under optimal conditions,the limit of detection(LOD),assessed by the naked eye within 5 min,was found to be 1 ng/g.A semi-quantitative analysis was also conducted using a smart phone and computer software,with a linearity of 0.075–0.750 ng/g,calculated LOD of 0.10 ng/g,calculated limit of quantitation of 0.33 ng/g,and good correlation of 0.992.The recoveries were found in the range of 96.4%–103.7%with a relative standard deviation of 2.5%–3.6%for intra-and inter-assays.Comparison of the results obtained by the strip test with those obtained by enzyme-linked immunosorbent assay had a good agreement in terms of accuracy.Furthermore,this strip test exhibited highly specific RAC detection without cross reactivity with related compounds.Therefore,the RAC–BSA conjugation via the Mannich reaction can be accepted as a one-step and easy conjugation method and applied to the competitive lateral flow strip test.展开更多
In this work,a very simple dual-readout lateral flow test strip(LFTS)platform was developed for sensitive detection of alkaline phosphatase(ALP)based on a portable device.In this assay,quantum dots(QDs)conjugated with...In this work,a very simple dual-readout lateral flow test strip(LFTS)platform was developed for sensitive detection of alkaline phosphatase(ALP)based on a portable device.In this assay,quantum dots(QDs)conjugated with bovine serum albumin(QDs-BSA)were chosen as fluorescence signal labels.In the absence of ALP,MnO_(2)nanosheets aggregate on the test line and exhibit an obvious brown color,which can be observed by naked eyes to realize semi-qualitative analysis.Meanwhile,fluorescence intensity of QDs-BSA can also be effectively quenched by MnO_(2)nanosheets due to inner-filter effect.Correspondingly,in the presence of ALP,ALP can catalyze the hydrolysis of ascorbic acid 2-phosphate(AAP)to generate L-ascorbic acid(AA),which can reduce MnO_(2)into Mn^(2+),accompanying with the obvious fluorescence recovery of the QDs.By simply monitoring the change of colorimetric and fluorescent signal on the test line,trace amount of ALP can be quantitatively detected.Under the optimal conditions,measurable evaluation of ALP was reached in a linear range from 1 U/L to 20 U/L with a detection limit of 0.7 U/L based on fluorescence signal.Furthermore,this colorimetric/fluorescent dual-readout assay was successfully applied to monitor ALP in human serum samples,showing its great potential as a point of care biosensor for clinical diagnosis.展开更多
Pavement horizontal curve is designed to serve as a transition between straight segments, and its presence may cause a series of driving-related safety issues to motorists and drivers. As is recognized that traditiona...Pavement horizontal curve is designed to serve as a transition between straight segments, and its presence may cause a series of driving-related safety issues to motorists and drivers. As is recognized that traditional methods for curve geometry investigation are time consuming, labor intensive, and inaccurate, this study attempts to develop a method that can automatically conduct horizontal curve identification and measurement at network level. The digital highway data vehicle （DHDV） was utilized for data collection, in which three Euler angles, driving speed, and acceleration of survey vehicle were measured with an inertial measurement unit （IMU）. The 3D profiling data used for cross slope calibration was obtained with PaveVision3D Ultra technology at 1 mm resolution. In this study, the curve identification was based on the variation of heading angle, and the curve radius was calculated with ki- nematic method, geometry method, and lateral acceleration method. In order to verify the accuracy of the three methods, the analysis of variance （ANOVA） test was applied by using the control variable of curve radius measured by field test. Based on the measured curve radius, a curve safety analysis model was used to predict the crash rates and safe driving speeds at horizontal curves. Finally, a case study on 4.35 km road segment demonstrated that the proposed method could efficiently conduct network level analysis.展开更多
Smaller class sizes in early grades translated into students scoring higher on math tests in later grades in Tennessee’s experiment to see if smaller classes improved education, a study said on Friday. 低年级的小型...Smaller class sizes in early grades translated into students scoring higher on math tests in later grades in Tennessee’s experiment to see if smaller classes improved education, a study said on Friday. 低年级的小型班级能够使学生在高年级时获得数学测试的高分。田纳西州的一项旨在了解小型班级是否能够改进教育的实验得出如此结论。一项研究周五如是说。展开更多
基金supported by the Scientific and Innovative Action Plan of Shanghai(21N31900800)Shanghai Rising-Star Program(23QB1403500)+4 种基金the Shanghai Sailing Program(20YF1443000)Shanghai Science and Technology Commission,the Belt and Road Project(20310750500)Talent Project of SAAS(2023-2025)Runup Plan of SAAS(ZP22211)the SAAS Program for Excellent Research Team(2022(B-16))。
文摘Traditional transgenic detection methods require high test conditions and struggle to be both sensitive and efficient.In this study,a one-tube dual recombinase polymerase amplification(RPA)reaction system for CP4-EPSPS and Cry1Ab/Ac was proposed and combined with a lateral flow immunochromatographic assay,named“Dual-RPA-LFD”,to visualize the dual detection of genetically modified(GM)crops.In which,the herbicide tolerance gene CP4-EPSPS and the insect resistance gene Cry1Ab/Ac were selected as targets taking into account the current status of the most widespread application of insect resistance and herbicide tolerance traits and their stacked traits.Gradient diluted plasmids,transgenic standards,and actual samples were used as templates to conduct sensitivity,specificity,and practicality assays,respectively.The constructed method achieved the visual detection of plasmid at levels as low as 100 copies,demonstrating its high sensitivity.In addition,good applicability to transgenic samples was observed,with no cross-interference between two test lines and no influence from other genes.In conclusion,this strategy achieved the expected purpose of simultaneous detection of the two popular targets in GM crops within 20 min at 37°C in a rapid,equipmentfree field manner,providing a new alternative for rapid screening for transgenic assays in the field.
基金Project(2010G003-F)supported by Technological Research and Development Programs of the Ministry of Railways,China
文摘Based on back analysis of lateral displacements measured in situ by using the analytical solution, a useful method for estimating stress concentration ratio of geosynthetic-reinforced and pile-supported(GRPS) embankments was proposed. In order to validate the proposed method, a full-scale high-speed railway embankment(HSRE) with four instrumented subsections over medium compressibility silty clay was constructed in three stages. The soil profile, construction procedure and monitoring of settlements and lateral displacements of the four test sections were described. The field deformation analysis results show that 1) the combined reinforcement of CFG piles and geosynthetic layer perform well in terms of reducing lateral displacements; 2) the development of lateral displacements lags behind the increase of fill load, which can be attributed to the vertical load transfer mechanism of the pile foundation; and 3) pile length has a dominant effect on the stress distribution proportion between piles and surrounding soils. The comparison between predicted and experimental results suggests that the proposed analytical solution and the back analysis-based method are capable of reasonably estimating the lateral deformation and the stress concentration ratio, respectively, if the appropriate soil elastic modulus is chosen.
基金Project Project supported by the Thailand Research Fund through the International Research Network(No.PHD58W0001)the Thailand Research Fund through Research Team Promotion Grant the Ratchadaphisaksomphot Endowment Fund of Chulalongkorn University(No.RTA6080002),Thailand
文摘In this work,a novel conjugate of ractopamine and bovine serum albumin(RAC–BSA)has been developed via the Mannich reaction,with a mole coupling ratio for RAC–BSA of 9:1.The proposed conjugation method provides a simple and one-step method with the use of fewer reagents compared with other conjugation methods for competitive immunoassays.RAC–BSA conjugation was used to fabricate a competitive lateral flow strip test for RAC detection in animal feed.For sample preparation,RAC was spiked in swine feed purchased from the local markets in Thailand,and methanol and running buffer at a volume ratio of 10:90 was used as extraction buffer.The procedures for sample preparation were completed within 25 min.Under optimal conditions,the limit of detection(LOD),assessed by the naked eye within 5 min,was found to be 1 ng/g.A semi-quantitative analysis was also conducted using a smart phone and computer software,with a linearity of 0.075–0.750 ng/g,calculated LOD of 0.10 ng/g,calculated limit of quantitation of 0.33 ng/g,and good correlation of 0.992.The recoveries were found in the range of 96.4%–103.7%with a relative standard deviation of 2.5%–3.6%for intra-and inter-assays.Comparison of the results obtained by the strip test with those obtained by enzyme-linked immunosorbent assay had a good agreement in terms of accuracy.Furthermore,this strip test exhibited highly specific RAC detection without cross reactivity with related compounds.Therefore,the RAC–BSA conjugation via the Mannich reaction can be accepted as a one-step and easy conjugation method and applied to the competitive lateral flow strip test.
基金supported by the National Natural Science Foundation of China(Nos.21974125,21605038)the National 111 Project(No.D20003)+1 种基金the Collaborative Innovation Project of Zhengzhou(Zhengzhou University)(No.18XTZX12002)the Key Scientific Research Project in Universities of Henan Province(No.19A150048).
文摘In this work,a very simple dual-readout lateral flow test strip(LFTS)platform was developed for sensitive detection of alkaline phosphatase(ALP)based on a portable device.In this assay,quantum dots(QDs)conjugated with bovine serum albumin(QDs-BSA)were chosen as fluorescence signal labels.In the absence of ALP,MnO_(2)nanosheets aggregate on the test line and exhibit an obvious brown color,which can be observed by naked eyes to realize semi-qualitative analysis.Meanwhile,fluorescence intensity of QDs-BSA can also be effectively quenched by MnO_(2)nanosheets due to inner-filter effect.Correspondingly,in the presence of ALP,ALP can catalyze the hydrolysis of ascorbic acid 2-phosphate(AAP)to generate L-ascorbic acid(AA),which can reduce MnO_(2)into Mn^(2+),accompanying with the obvious fluorescence recovery of the QDs.By simply monitoring the change of colorimetric and fluorescent signal on the test line,trace amount of ALP can be quantitatively detected.Under the optimal conditions,measurable evaluation of ALP was reached in a linear range from 1 U/L to 20 U/L with a detection limit of 0.7 U/L based on fluorescence signal.Furthermore,this colorimetric/fluorescent dual-readout assay was successfully applied to monitor ALP in human serum samples,showing its great potential as a point of care biosensor for clinical diagnosis.
文摘Pavement horizontal curve is designed to serve as a transition between straight segments, and its presence may cause a series of driving-related safety issues to motorists and drivers. As is recognized that traditional methods for curve geometry investigation are time consuming, labor intensive, and inaccurate, this study attempts to develop a method that can automatically conduct horizontal curve identification and measurement at network level. The digital highway data vehicle （DHDV） was utilized for data collection, in which three Euler angles, driving speed, and acceleration of survey vehicle were measured with an inertial measurement unit （IMU）. The 3D profiling data used for cross slope calibration was obtained with PaveVision3D Ultra technology at 1 mm resolution. In this study, the curve identification was based on the variation of heading angle, and the curve radius was calculated with ki- nematic method, geometry method, and lateral acceleration method. In order to verify the accuracy of the three methods, the analysis of variance （ANOVA） test was applied by using the control variable of curve radius measured by field test. Based on the measured curve radius, a curve safety analysis model was used to predict the crash rates and safe driving speeds at horizontal curves. Finally, a case study on 4.35 km road segment demonstrated that the proposed method could efficiently conduct network level analysis.
文摘Smaller class sizes in early grades translated into students scoring higher on math tests in later grades in Tennessee’s experiment to see if smaller classes improved education, a study said on Friday. 低年级的小型班级能够使学生在高年级时获得数学测试的高分。田纳西州的一项旨在了解小型班级是否能够改进教育的实验得出如此结论。一项研究周五如是说。
