HIV-1 reverse transcriptase（RT） inhibitors are major components of HAART（highly active antiviral therapy）. The S-DABOs（dihydro-alkylthio-benzyl-oxopyrimidines） series and their similar skeletons have exhibited p...HIV-1 reverse transcriptase（RT） inhibitors are major components of HAART（highly active antiviral therapy）. The S-DABOs（dihydro-alkylthio-benzyl-oxopyrimidines） series and their similar skeletons have exhibited preferable activities to inhibit HIV-1 RT. In the present study, we generated field-based QSAR models using common structure alignment, which was characterized by Gaussian steric, electrostatic, hydrophobic, hydrogen bond donor, hydrogen bond acceptor and aromatic ring fields（R2 = 0.8421, RCV2 = 0.5949 for the training set, Q2 = 0.5486, Pearson-r = 0.7460 for the test set）. Docking, pocket surface and contour map analyses were carried out. Key pharmacophore features were investigated, including（i） π-π interaction with residue Tyr181, Tyr188 and Trp229, σ-π interaction with His236,（ii） hydrogen bond with residue Lys101 and halogen bond with residue Tyr188. The docking analysis and field-based QSAR models could provide reasonable guidance in the rational design of potent HIV-1 RT inhibitors.展开更多
The article deals with the effects of urea and controlled release nitrogen fertilizer （CRNF） on dynamics of pH, electronic conductivity （EC）, total nitrogen （TN）, NH4^＋-N and NO3 -N in floodwater, and the regul...The article deals with the effects of urea and controlled release nitrogen fertilizer （CRNF） on dynamics of pH, electronic conductivity （EC）, total nitrogen （TN）, NH4^＋-N and NO3 -N in floodwater, and the regulation of runoff TN loss from paddy field-based two-cropping rice in Dongting Lake, China, and probes the best fertilization management for controlling N loss. Studies were conducted through modeling alluvial sandy loamy paddy soil （ASP） and purple calcareous clayey paddy soil （PCP） using lysimeter, following the sequence of the soil profiles identified by investigating soil profile. After application of urea in paddy field-based two-cropping rice, TN and NHa＋-N concentrations in floodwater reached peak on the 1st and the 3rd day, respectively, and then decreased rapidly over time; all the floodwater NO3--N concentrations were very low; the pH of floodwater gradually rose in case of early rice within 15 d （late rice within 3 d） after application of urea, and EC remained consistent with the dynamics of NH4^＋-N. The applied CRNF, especially 70% CRNF, led to significantly lower floodwater TN and NH4^＋ concentrations, pH, and EC values compared with urea within 15 d after application. The monitoring result for N loss due to natural rainfall runoff indicated that the amount of TN lost in runoff from paddy field- based two-cropping rice with urea application in Dongting Lake area was 7.47 kg ha^-1, which accounted for 2.49% of urea- N applied, and that with CRNF and 70% CRNF application decreased 24.5 and 27.2% compared with urea application, respectively. The two runoff events, which occurred within 20 d after application, contributed significantly to TN loss from paddy field. TN loss due to the two runoffs in urea, CRNF, and 70% CRNF treatments accounted for 72, 70, and 58% of the total TN loss due to runoff over the whole rice growth season, respectively. And the TN loss in these two CRNF treatments due to the first run-off event at the 10th day after application to early rice decreased 44.9 and 44.2% compared with urea, respectively. In conclusion, the 15-d period after application of urea was the critical time during which N loss occurred due to high floodwater N concentrations. But CRNF decreased N concentrations greatly in floodwater and runoff water during this period. As a result, it obviously reduced TN loss in runoff over the whole rice growth season.展开更多
Field-based phenotyping(FBP)of crop root systemarchitecture(RSA)provides away to quantify the root growth and distribution in fieldwith a smaller scale.Studies on a better understanding of the interrelations between f...Field-based phenotyping(FBP)of crop root systemarchitecture(RSA)provides away to quantify the root growth and distribution in fieldwith a smaller scale.Studies on a better understanding of the interrelations between field crop root physiological traits,root developmental phases and environmental changes are hindered due to deficiency of in situ root system architecture testing and quantitative methods for field crop.The present study aimed to propose a protocol for field-based wheat root system architecture with technical details of key operational procedures.Phenotyping of RSA traits from root spatial coordinate data acquisition and visualization software presented scaled illustrations of wheat RSA dynamics and root developmental phases which also revealed the root topological heterogeneities,eitherwithin a plant oramong individuals.Percentage of horizontal and vertical soil coverage by root showed that root foraging capability along soil depth was better than within the horizontal dimension.In brief,our data indicated that FBP ofwheat RSA could be achieved using the protocol of datadriven model-assisted phenotyping procedure.The proposed protocol was demonstrated useful for FBP of RSAs.It was proved effective to illustrate the topological structures of the wheat root system and to quantify RSAderived parameters,this could be a useful tool for characterizing and analyzing the structural distortion,heterogeneous distribution and the soil space exploration characteristics of wheat root.展开更多
Advanced field methods of carbon (C) analysis should now be capable of providing repetitive, sequential measurements for the evaluation of spatial and temporal variation at a scale that was previously unfeasible. Some...Advanced field methods of carbon (C) analysis should now be capable of providing repetitive, sequential measurements for the evaluation of spatial and temporal variation at a scale that was previously unfeasible. Some spectroscopy techniques, such as laser-induced breakdown spectroscopy (LIBS), have portable features that may potentially lead to clean and rapid alternative approaches for this purpose. The goal of this study was to quantify the C content of soils with different textures and with high iron and aluminum concentrations using LIBS. LIBS emission spectra from soil pellets were captured, and the C content was estimated (emission line of C (I) at 193.03 nm) after spectral offset and aluminum spectral interference correction. This technique is highly portable and could be ideal for providing the soil C content in a heterogeneous experiment. Dry combustion was used as a reference method, and for calibration a conventional linear model was evaluated based on soil textural classes. The correlation between reference and LIBS values showed r = 0.86 for medium-textured soils and r = 0.93 for fine-textured soils. The data showed that better correlation and lower error (14%) values were found for the fine-textured LIBS model. The limit of detection (LOD) was found to be 0.32% for medium-textured soils and 0.13% for fine-textured soils. The results indicated that LIBS quantification can be affected by the texture and chemical composition of soil. Signal treatment was shown to be very important for mitigation of these interferences and to improve quantification.展开更多
Path planning for field agricultural robots must satisfy several criteria:establishing feeding routes,maintaining gentle slopes,approaching multiple livestock observation points,ensuring timely environmental monitorin...Path planning for field agricultural robots must satisfy several criteria:establishing feeding routes,maintaining gentle slopes,approaching multiple livestock observation points,ensuring timely environmental monitoring,and achieving high efficiency.The complex terrain of outdoor farming areas poses a challenge.Traditional A*algorithms,which generate only the shortest path,fail to meet these requirements and often produce paths that lack smoothness.Therefore,identifying the most suitable path,rather than merely the shortest one,is essential.This study introduced a path-planning algorithm tailored to field-based livestock farming environments,building upon the traditional A*algorithm.It constructed a digital elevation model,integrated an artificial potential field for evaluating multiple target points,calculated terrain slope,optimized the search neighborhood based on robot traversability,and employed Bézier curve segmentation for path optimization.This method segmented the path into multiple curves by evaluating the slopes of the lines connecting adjacent nodes,ensuring a smoother and more efficient route.The experimental results demonstrate its superiority to traditional A^(*),ensuring paths near multiple target points,significantly reducing the search space,and resulting in over 69.4%faster search speeds.Bézier curve segmentation delivers smoother paths conforming to robot trajectories.展开更多
基金National Natural Science Foundation of China(Grant No.21172014,20972011,21042009,21272017 and 81172917)Grants from the Ministry of Science and Technology of China(Grant No.2009ZX09301-010)
文摘HIV-1 reverse transcriptase（RT） inhibitors are major components of HAART（highly active antiviral therapy）. The S-DABOs（dihydro-alkylthio-benzyl-oxopyrimidines） series and their similar skeletons have exhibited preferable activities to inhibit HIV-1 RT. In the present study, we generated field-based QSAR models using common structure alignment, which was characterized by Gaussian steric, electrostatic, hydrophobic, hydrogen bond donor, hydrogen bond acceptor and aromatic ring fields（R2 = 0.8421, RCV2 = 0.5949 for the training set, Q2 = 0.5486, Pearson-r = 0.7460 for the test set）. Docking, pocket surface and contour map analyses were carried out. Key pharmacophore features were investigated, including（i） π-π interaction with residue Tyr181, Tyr188 and Trp229, σ-π interaction with His236,（ii） hydrogen bond with residue Lys101 and halogen bond with residue Tyr188. The docking analysis and field-based QSAR models could provide reasonable guidance in the rational design of potent HIV-1 RT inhibitors.
基金We acknowledge the support from the Phosphorus and Potassium Institute in Canada with China scheme （Canada-Sino Cooperation Project： HN- 13） and from the National Natural Science Foundation of China （30270770）.
文摘The article deals with the effects of urea and controlled release nitrogen fertilizer （CRNF） on dynamics of pH, electronic conductivity （EC）, total nitrogen （TN）, NH4^＋-N and NO3 -N in floodwater, and the regulation of runoff TN loss from paddy field-based two-cropping rice in Dongting Lake, China, and probes the best fertilization management for controlling N loss. Studies were conducted through modeling alluvial sandy loamy paddy soil （ASP） and purple calcareous clayey paddy soil （PCP） using lysimeter, following the sequence of the soil profiles identified by investigating soil profile. After application of urea in paddy field-based two-cropping rice, TN and NHa＋-N concentrations in floodwater reached peak on the 1st and the 3rd day, respectively, and then decreased rapidly over time; all the floodwater NO3--N concentrations were very low; the pH of floodwater gradually rose in case of early rice within 15 d （late rice within 3 d） after application of urea, and EC remained consistent with the dynamics of NH4^＋-N. The applied CRNF, especially 70% CRNF, led to significantly lower floodwater TN and NH4^＋ concentrations, pH, and EC values compared with urea within 15 d after application. The monitoring result for N loss due to natural rainfall runoff indicated that the amount of TN lost in runoff from paddy field- based two-cropping rice with urea application in Dongting Lake area was 7.47 kg ha^-1, which accounted for 2.49% of urea- N applied, and that with CRNF and 70% CRNF application decreased 24.5 and 27.2% compared with urea application, respectively. The two runoff events, which occurred within 20 d after application, contributed significantly to TN loss from paddy field. TN loss due to the two runoffs in urea, CRNF, and 70% CRNF treatments accounted for 72, 70, and 58% of the total TN loss due to runoff over the whole rice growth season, respectively. And the TN loss in these two CRNF treatments due to the first run-off event at the 10th day after application to early rice decreased 44.9 and 44.2% compared with urea, respectively. In conclusion, the 15-d period after application of urea was the critical time during which N loss occurred due to high floodwater N concentrations. But CRNF decreased N concentrations greatly in floodwater and runoff water during this period. As a result, it obviously reduced TN loss in runoff over the whole rice growth season.
基金Financial support from the China Postdoctoral Science Foundation(2018M632314)the State Key Program of China(2016YFD0300900)were acknowledged.
文摘Field-based phenotyping(FBP)of crop root systemarchitecture(RSA)provides away to quantify the root growth and distribution in fieldwith a smaller scale.Studies on a better understanding of the interrelations between field crop root physiological traits,root developmental phases and environmental changes are hindered due to deficiency of in situ root system architecture testing and quantitative methods for field crop.The present study aimed to propose a protocol for field-based wheat root system architecture with technical details of key operational procedures.Phenotyping of RSA traits from root spatial coordinate data acquisition and visualization software presented scaled illustrations of wheat RSA dynamics and root developmental phases which also revealed the root topological heterogeneities,eitherwithin a plant oramong individuals.Percentage of horizontal and vertical soil coverage by root showed that root foraging capability along soil depth was better than within the horizontal dimension.In brief,our data indicated that FBP ofwheat RSA could be achieved using the protocol of datadriven model-assisted phenotyping procedure.The proposed protocol was demonstrated useful for FBP of RSAs.It was proved effective to illustrate the topological structures of the wheat root system and to quantify RSAderived parameters,this could be a useful tool for characterizing and analyzing the structural distortion,heterogeneous distribution and the soil space exploration characteristics of wheat root.
基金The authors express their gratitude for the grant from FAPESP(2010/09211-6),CNPq(560292/2010-4)CAPES,Embrapa and Pecus Research Network.
文摘Advanced field methods of carbon (C) analysis should now be capable of providing repetitive, sequential measurements for the evaluation of spatial and temporal variation at a scale that was previously unfeasible. Some spectroscopy techniques, such as laser-induced breakdown spectroscopy (LIBS), have portable features that may potentially lead to clean and rapid alternative approaches for this purpose. The goal of this study was to quantify the C content of soils with different textures and with high iron and aluminum concentrations using LIBS. LIBS emission spectra from soil pellets were captured, and the C content was estimated (emission line of C (I) at 193.03 nm) after spectral offset and aluminum spectral interference correction. This technique is highly portable and could be ideal for providing the soil C content in a heterogeneous experiment. Dry combustion was used as a reference method, and for calibration a conventional linear model was evaluated based on soil textural classes. The correlation between reference and LIBS values showed r = 0.86 for medium-textured soils and r = 0.93 for fine-textured soils. The data showed that better correlation and lower error (14%) values were found for the fine-textured LIBS model. The limit of detection (LOD) was found to be 0.32% for medium-textured soils and 0.13% for fine-textured soils. The results indicated that LIBS quantification can be affected by the texture and chemical composition of soil. Signal treatment was shown to be very important for mitigation of these interferences and to improve quantification.
基金supported by the Subject construction projects in specific universities(Grant No.2023B10564003)the Science and Technology Rural Commissioner Project of Guangzhou(Grant No.20212100026).
文摘Path planning for field agricultural robots must satisfy several criteria:establishing feeding routes,maintaining gentle slopes,approaching multiple livestock observation points,ensuring timely environmental monitoring,and achieving high efficiency.The complex terrain of outdoor farming areas poses a challenge.Traditional A*algorithms,which generate only the shortest path,fail to meet these requirements and often produce paths that lack smoothness.Therefore,identifying the most suitable path,rather than merely the shortest one,is essential.This study introduced a path-planning algorithm tailored to field-based livestock farming environments,building upon the traditional A*algorithm.It constructed a digital elevation model,integrated an artificial potential field for evaluating multiple target points,calculated terrain slope,optimized the search neighborhood based on robot traversability,and employed Bézier curve segmentation for path optimization.This method segmented the path into multiple curves by evaluating the slopes of the lines connecting adjacent nodes,ensuring a smoother and more efficient route.The experimental results demonstrate its superiority to traditional A^(*),ensuring paths near multiple target points,significantly reducing the search space,and resulting in over 69.4%faster search speeds.Bézier curve segmentation delivers smoother paths conforming to robot trajectories.
