A new phenolic constituent along with five known compounds were isolated from Fagopyrum dibotrys (D.Don) Hara. The new compound was characterized as 1,3-dimethoxy-2-O-β-xylo-pyranosyl-5-O-β-glucopyranosyl-benzene, b...A new phenolic constituent along with five known compounds were isolated from Fagopyrum dibotrys (D.Don) Hara. The new compound was characterized as 1,3-dimethoxy-2-O-β-xylo-pyranosyl-5-O-β-glucopyranosyl-benzene, by spectroscopic analysis and enzymatic hydrolysis.展开更多
This paper proposes a method for planning the three-dimensional path for low-flying unmanned aerial vehicle（UAV） in complex terrain based on interfered fluid dynamical system（IFDS） and the theory of obstacle avoid...This paper proposes a method for planning the three-dimensional path for low-flying unmanned aerial vehicle（UAV） in complex terrain based on interfered fluid dynamical system（IFDS） and the theory of obstacle avoidance by the flowing stream. With no requirement of solutions to fluid equations under complex boundary conditions, the proposed method is suitable for situations with complex terrain and different shapes of obstacles. Firstly, by transforming the mountains, radar and anti-aircraft fire in complex terrain into cylindrical, conical, spherical, parallelepiped obstacles and their combinations, the 3D low-flying path planning problem is turned into solving streamlines for obstacle avoidance by fluid flow. Secondly, on the basis of a unified mathematical expression of typical obstacle shapes including sphere, cylinder, cone and parallelepiped, the modulation matrix for interfered fluid dynamical system is constructed and 3D streamlines around a single obstacle are obtained. Solutions to streamlines with multiple obstacles are then derived using weighted average of the velocity field. Thirdly, extra control force method and virtual obstacle method are proposed to deal with the stagnation point and the case of obstacles＇ overlapping respectively. Finally, taking path length and flight height as sub-goals, genetic algorithm（GA） is used to obtain optimal 3D path under the maneuverability constraints of the UAV. Simulation results show that the environmental modeling is simple and the path is smooth and suitable for UAV. Theoretical proof is also presented to show that the proposed method has no effect on the characteristics of fluid avoiding obstacles.展开更多
In this paper,a 20kW vehicle built-in permanent magnet synchronous motor is taken as an example,and a magnetic barrier structure is added to the rotor of the motor to solve the uneven saturation problem of the rotor s...In this paper,a 20kW vehicle built-in permanent magnet synchronous motor is taken as an example,and a magnetic barrier structure is added to the rotor of the motor to solve the uneven saturation problem of the rotor side magnetic bridge.This structure improves the air-gap flux density waveform of the motor by influencing the internal magnetic flux path of the motor rotor,thus improving the sine of the no-load back EMF waveform of the motor and reducing the torque ripple of the motor.At the same time,Taguchi method is used to optimize the structural parameters of the added magnetic barrier.In order to facilitate the analysis of its uneven saturation phenomenon and improve the optimization effect,a simple equivalent magnetic network(EMN)model considering the uneven saturation of rotor magnetic bridge is established in this paper,and the initial values of optimization factors are selected based on this model.Finally,the no-load back EMF waveform distortion rate,torque ripple and output torque of the optimized motor are compared and analyzed,and the influence of magnetic barrier structure parameters on the electromagnetic performance of the motor is also analyzed.The results show that the optimized motor can not change the output torque of the motor as much as possible on the basis of reducing the waveform distortion rate of no-load back EMF and torque ripple.展开更多
A new isoflavane named astraganoside, together with five known compounds had been isolated from the processed Astragralus membranaceus. The structure of the novel compound was elucidated as (3R, 4R)-3-(2-hydroxy-3,4-d...A new isoflavane named astraganoside, together with five known compounds had been isolated from the processed Astragralus membranaceus. The structure of the novel compound was elucidated as (3R, 4R)-3-(2-hydroxy-3,4-dimethoxyphenyl)chroman-4,7-diol-7-O-β-d-glucopyranoside (1) based on spectroscopic methods including UV, IR, ESI-MS, 1D NMR and 2D NMR techniques.展开更多
A technology to achieve stable and high ammonia nitrogen removal rates for corn distillery wastewater （ethanol fuel production） treatment has been designed.The characteristics of nitrifying bacteria entrapped in a w...A technology to achieve stable and high ammonia nitrogen removal rates for corn distillery wastewater （ethanol fuel production） treatment has been designed.The characteristics of nitrifying bacteria entrapped in a waterborne polyurethane （WPU） gel carrier were evaluated after acclimation.In the acclimation period,nitrification rates of WPU-immobilized nitrobacteria were monitored and polymerase chain reaction （PCR） was also carried out to investigate the change in ammonium-oxidizing bacteria.The results showed that the pellet nitrification rates increased from 21 to 228 mg-N/（L-pellet·hr） and the quantity of the ammonia oxidation bacteria increased substantially during the acclimation.A continuous ammonia removal experiment with the anaerobic pond effluent of a distillery wastewater system was conducted with immobilized nitrifying bacteria for 30 days using an 80 L airlift reactor with pellets at a fill ratio of 15% （V/V）.Under the conditions of 75 mg/L influent ammonia,hydraulic retention time （HRT） of 3.7-5.6 hr,and dissolved oxygen （DO） of 4 mg/L,the effluent ammonia concentration was lower than 10 mg/L and the ammonia removal efficiency was 90%.While the highest ammonia removal rate,162 mg-N/（L-pellet·hr）,was observed when the HRT was 1.3 hr.展开更多
Soil macroinvertebrates as ecosystem engineers play significant, but largely ignored, roles in affecting mercury(Hg) cycle by altering soil physical-chemical properties. Ant is likely expanded into boreal mires with c...Soil macroinvertebrates as ecosystem engineers play significant, but largely ignored, roles in affecting mercury(Hg) cycle by altering soil physical-chemical properties. Ant is likely expanded into boreal mires with climate warming, however, its impacts on Hg cycle remained poorly understood. We compared total Hg(THg) and methylmercury(Me Hg) contents in soils from antmounds( Lasius flavus) and the nearby ambient in a boreal mire in Northeast China. The present work seeks to unravel factors that controlling Me Hg levels in case of ant appearance or absence. The average THg was 179 μg/kg in the ant mound and was 106.1 μg/kg in nearby soils, respectively. The average Me Hg was 10.9 μg/kg in the ant mound and was 12.9 μg/kg in nearby soils, respectively. The ratios of Me Hg to THg(%Me Hg) were 7.61% in ant mounds and 16.75% in nearby soils, respectively. Ant colonization caused THg enrichment and Me Hg depletion, and this change was obvious in the 10-20 cm depth soil layer where ants mainly inhabited. Spectrometry characteristics of soil dissolved organic matter(DOM) exert a stronger control than microorganisms on Me Hg variation in soils. A structural equation model revealed that the molecular weight of DOM inhibited Me Hg irrespective of ant presence or absence, while humification conducive to Me Hg significantly in ant mound soils. Microorganisms mainly affected Hg methylation by altering the molecular weight and humification of DOM. We propose that the effects of ant colonization on Me Hg rested on DOM feature variations caused by microorganisms in boreal mires.展开更多
A model was presented to describe the microstructure evolution during the directional solidification process. In this model, the problem of different properties in the solid and liquid phase was solved by making the p...A model was presented to describe the microstructure evolution during the directional solidification process. In this model, the problem of different properties in the solid and liquid phase was solved by making the properties continuous at the solid/liquid interface. Furthermore, a random noise was incorporated to reflect the anisotropic growth. Moreover, the averaging solute conservation was developed to keep the total solute conservation in the interface region. A simple ingot was simulated by this method, the model can represent the microstructure evolution, solute concentration redistribution, micro-segregation and the columnar-to-equiaxed transition.展开更多
μC/OS-Ⅱ is an open source real-time kernel adopting priority preemptive schedule strategy. Aiming at the problem of μC/OS-Ⅱ failing to support homology priority tasks scheduling, an approach for solution is propos...μC/OS-Ⅱ is an open source real-time kernel adopting priority preemptive schedule strategy. Aiming at the problem of μC/OS-Ⅱ failing to support homology priority tasks scheduling, an approach for solution is proposed. The basic idea is adding round-robin scheduling strategy in its original scheduler in order to schedule homology priority tasks through time slice roundrobin. Implementation approach is given in detail. Firstly, the Task Control Block （TCB） is extended. And then, a new priority index table is created, in which each index pointer points to a set of homology priority tasks. Eventually, on the basis of reconstructing μC/OS-Ⅱ real-time kernel, task scheduling module is rewritten. Otherwise, schedulability of homology task supported by modified kernel had been analyzed, and deadline formula of created homology tasks is given. By theoretical analysis and experiment verification, the modified kernel can support homology priority tasks scheduling, meanwhile, it also remains preemptive property of original μC/OS-Ⅱ.展开更多
In this study,we constructed single mutants MTS-1,MTS-2 of IroN and ShuA gene and double mutant MTS of them in Shigella dysenteriae A1 strain 51197 by insert and absence.The functional detection of every mutant was pe...In this study,we constructed single mutants MTS-1,MTS-2 of IroN and ShuA gene and double mutant MTS of them in Shigella dysenteriae A1 strain 51197 by insert and absence.The functional detection of every mutant was performed at the level of culture medium and cell experiment.The gene expression profiles of the mutants and the wild-type strains under iron-enriched and iron-limited conditions were analyzed by the SD51197 whole genomic microarray.The results showed that all the mutants grew obviously less well than the wild-type strains in L broth appending iron chelator DIP.The addition of iron to the cultures can stimulate the growth of mutants back to wild-type levels.In either the experiments on the ability of intracellular multiplication or the cell-to-cell spread in HeLa and U937 cell lines,mutants showed no obvious change in virulence compared with the parental strain SD51197.However when DIP was added to the cultured HeLa cells,the ability of intracellular multiplication of MTS-1,MTS-2,MTS has reduced about 23.4%,25.2%,43.6%respectively.The analysis of expression profiles under the iron-limited condition showed that the mutants were more sensitive for the changes of iron deficiency than the wild-type strains,many genes have been altered.Up-regulated genes mainly involved genes of transcription,coenzyme metabolism,amino acid transport and metabolism,and unknown functional genes,while down-regulated genes mainly involved genes of energy and carbohydrate metabolism and unknown function genes;the expression levels of known iron-transport associated genes generally showed up-regulated.The results demonstrated that iron-transport associated genes IroN,ShuA were likely to have some effects on the virulence and growth of S.dysenteriae.展开更多
Comparative Genomic Hybridization (CGH) microarray analysis was used tocompare the genomic compositions of all eighteen Shigella boydii serotype representative strains.The results indicated the genomic ''backb...Comparative Genomic Hybridization (CGH) microarray analysis was used tocompare the genomic compositions of all eighteen Shigella boydii serotype representative strains.The results indicated the genomic ''backbone'' of this subgroup contained 2552 ORFs homologous tononpatho-genic E. coli K12. Compared with the genome of K12199 ORFs were found to be absent in allS. boydii serotype representatives, including mainly outer membrane protein genes and O-antigenbiosynthesis genes. Yet the specific ORFs of S. boydii subgroup contained basically bacteriophagegenes and the function unknown (FUN) genes. Some iron metabolism, transport and type Ⅱ secretionsystem related genes were found in most representative strains. According to the CGH phylogeneticanalysis, the eighteen S. boydii serotype representatives were divided into four groups, in whichserotype C13 strain was remarkably distinguished from the other serotype strains. This groupingresult corresponded to the distribution of some metabolism related genes. Furthermore, the analysisof genome backbone genes, specific genes, and the phylogenetic trees allowed us to discover theevolution laws of S. boydii and to find out important clues to pathogenesis research, vaccinationand the therapeutic medicine development.展开更多
文摘A new phenolic constituent along with five known compounds were isolated from Fagopyrum dibotrys (D.Don) Hara. The new compound was characterized as 1,3-dimethoxy-2-O-β-xylo-pyranosyl-5-O-β-glucopyranosyl-benzene, by spectroscopic analysis and enzymatic hydrolysis.
基金supported by the National Natural Science Foundation of China(No.61175084)
文摘This paper proposes a method for planning the three-dimensional path for low-flying unmanned aerial vehicle（UAV） in complex terrain based on interfered fluid dynamical system（IFDS） and the theory of obstacle avoidance by the flowing stream. With no requirement of solutions to fluid equations under complex boundary conditions, the proposed method is suitable for situations with complex terrain and different shapes of obstacles. Firstly, by transforming the mountains, radar and anti-aircraft fire in complex terrain into cylindrical, conical, spherical, parallelepiped obstacles and their combinations, the 3D low-flying path planning problem is turned into solving streamlines for obstacle avoidance by fluid flow. Secondly, on the basis of a unified mathematical expression of typical obstacle shapes including sphere, cylinder, cone and parallelepiped, the modulation matrix for interfered fluid dynamical system is constructed and 3D streamlines around a single obstacle are obtained. Solutions to streamlines with multiple obstacles are then derived using weighted average of the velocity field. Thirdly, extra control force method and virtual obstacle method are proposed to deal with the stagnation point and the case of obstacles＇ overlapping respectively. Finally, taking path length and flight height as sub-goals, genetic algorithm（GA） is used to obtain optimal 3D path under the maneuverability constraints of the UAV. Simulation results show that the environmental modeling is simple and the path is smooth and suitable for UAV. Theoretical proof is also presented to show that the proposed method has no effect on the characteristics of fluid avoiding obstacles.
基金supported by the National Natural Science Funds of China No.51907129Technology program of Liaoning province No.2021-MS-236。
文摘In this paper,a 20kW vehicle built-in permanent magnet synchronous motor is taken as an example,and a magnetic barrier structure is added to the rotor of the motor to solve the uneven saturation problem of the rotor side magnetic bridge.This structure improves the air-gap flux density waveform of the motor by influencing the internal magnetic flux path of the motor rotor,thus improving the sine of the no-load back EMF waveform of the motor and reducing the torque ripple of the motor.At the same time,Taguchi method is used to optimize the structural parameters of the added magnetic barrier.In order to facilitate the analysis of its uneven saturation phenomenon and improve the optimization effect,a simple equivalent magnetic network(EMN)model considering the uneven saturation of rotor magnetic bridge is established in this paper,and the initial values of optimization factors are selected based on this model.Finally,the no-load back EMF waveform distortion rate,torque ripple and output torque of the optimized motor are compared and analyzed,and the influence of magnetic barrier structure parameters on the electromagnetic performance of the motor is also analyzed.The results show that the optimized motor can not change the output torque of the motor as much as possible on the basis of reducing the waveform distortion rate of no-load back EMF and torque ripple.
文摘A new isoflavane named astraganoside, together with five known compounds had been isolated from the processed Astragralus membranaceus. The structure of the novel compound was elucidated as (3R, 4R)-3-(2-hydroxy-3,4-dimethoxyphenyl)chroman-4,7-diol-7-O-β-d-glucopyranoside (1) based on spectroscopic methods including UV, IR, ESI-MS, 1D NMR and 2D NMR techniques.
基金supported by the National Water Pollution Control and Management Technology Major Projects(No. 2008ZX07101-010-03)the National Natural Science Foundation of China (No. 50708058)+2 种基金the National High Technology Research and Development Program (863)of China (No. 2012AA062703)the Shanghai Municipal Science and Technology Commission Major Project (No.04DZ12030-2)the Shanghai Committee of Science and Technology (No.10231201800)
文摘A technology to achieve stable and high ammonia nitrogen removal rates for corn distillery wastewater （ethanol fuel production） treatment has been designed.The characteristics of nitrifying bacteria entrapped in a waterborne polyurethane （WPU） gel carrier were evaluated after acclimation.In the acclimation period,nitrification rates of WPU-immobilized nitrobacteria were monitored and polymerase chain reaction （PCR） was also carried out to investigate the change in ammonium-oxidizing bacteria.The results showed that the pellet nitrification rates increased from 21 to 228 mg-N/（L-pellet·hr） and the quantity of the ammonia oxidation bacteria increased substantially during the acclimation.A continuous ammonia removal experiment with the anaerobic pond effluent of a distillery wastewater system was conducted with immobilized nitrifying bacteria for 30 days using an 80 L airlift reactor with pellets at a fill ratio of 15% （V/V）.Under the conditions of 75 mg/L influent ammonia,hydraulic retention time （HRT） of 3.7-5.6 hr,and dissolved oxygen （DO） of 4 mg/L,the effluent ammonia concentration was lower than 10 mg/L and the ammonia removal efficiency was 90%.While the highest ammonia removal rate,162 mg-N/（L-pellet·hr）,was observed when the HRT was 1.3 hr.
基金supported by the National Natural Science Foundation of China (Nos. U20A2083, U19A2042, and 41771103)the Youth Innovation Promotion Association CAS (No. 2018265)。
文摘Soil macroinvertebrates as ecosystem engineers play significant, but largely ignored, roles in affecting mercury(Hg) cycle by altering soil physical-chemical properties. Ant is likely expanded into boreal mires with climate warming, however, its impacts on Hg cycle remained poorly understood. We compared total Hg(THg) and methylmercury(Me Hg) contents in soils from antmounds( Lasius flavus) and the nearby ambient in a boreal mire in Northeast China. The present work seeks to unravel factors that controlling Me Hg levels in case of ant appearance or absence. The average THg was 179 μg/kg in the ant mound and was 106.1 μg/kg in nearby soils, respectively. The average Me Hg was 10.9 μg/kg in the ant mound and was 12.9 μg/kg in nearby soils, respectively. The ratios of Me Hg to THg(%Me Hg) were 7.61% in ant mounds and 16.75% in nearby soils, respectively. Ant colonization caused THg enrichment and Me Hg depletion, and this change was obvious in the 10-20 cm depth soil layer where ants mainly inhabited. Spectrometry characteristics of soil dissolved organic matter(DOM) exert a stronger control than microorganisms on Me Hg variation in soils. A structural equation model revealed that the molecular weight of DOM inhibited Me Hg irrespective of ant presence or absence, while humification conducive to Me Hg significantly in ant mound soils. Microorganisms mainly affected Hg methylation by altering the molecular weight and humification of DOM. We propose that the effects of ant colonization on Me Hg rested on DOM feature variations caused by microorganisms in boreal mires.
文摘A model was presented to describe the microstructure evolution during the directional solidification process. In this model, the problem of different properties in the solid and liquid phase was solved by making the properties continuous at the solid/liquid interface. Furthermore, a random noise was incorporated to reflect the anisotropic growth. Moreover, the averaging solute conservation was developed to keep the total solute conservation in the interface region. A simple ingot was simulated by this method, the model can represent the microstructure evolution, solute concentration redistribution, micro-segregation and the columnar-to-equiaxed transition.
基金Supported by the "Chunhui" Plan of Ministry of Education of China (Z2005-2-11013)
文摘μC/OS-Ⅱ is an open source real-time kernel adopting priority preemptive schedule strategy. Aiming at the problem of μC/OS-Ⅱ failing to support homology priority tasks scheduling, an approach for solution is proposed. The basic idea is adding round-robin scheduling strategy in its original scheduler in order to schedule homology priority tasks through time slice roundrobin. Implementation approach is given in detail. Firstly, the Task Control Block （TCB） is extended. And then, a new priority index table is created, in which each index pointer points to a set of homology priority tasks. Eventually, on the basis of reconstructing μC/OS-Ⅱ real-time kernel, task scheduling module is rewritten. Otherwise, schedulability of homology task supported by modified kernel had been analyzed, and deadline formula of created homology tasks is given. By theoretical analysis and experiment verification, the modified kernel can support homology priority tasks scheduling, meanwhile, it also remains preemptive property of original μC/OS-Ⅱ.
基金supported by the High Technology Research and Development Program of China(Grant No.2004AA223090)the State Key Basic Research Program(Grant No.2005CB522904)Interational Science and Technology Co-operation Project(Grant No.2001AA223116).
文摘In this study,we constructed single mutants MTS-1,MTS-2 of IroN and ShuA gene and double mutant MTS of them in Shigella dysenteriae A1 strain 51197 by insert and absence.The functional detection of every mutant was performed at the level of culture medium and cell experiment.The gene expression profiles of the mutants and the wild-type strains under iron-enriched and iron-limited conditions were analyzed by the SD51197 whole genomic microarray.The results showed that all the mutants grew obviously less well than the wild-type strains in L broth appending iron chelator DIP.The addition of iron to the cultures can stimulate the growth of mutants back to wild-type levels.In either the experiments on the ability of intracellular multiplication or the cell-to-cell spread in HeLa and U937 cell lines,mutants showed no obvious change in virulence compared with the parental strain SD51197.However when DIP was added to the cultured HeLa cells,the ability of intracellular multiplication of MTS-1,MTS-2,MTS has reduced about 23.4%,25.2%,43.6%respectively.The analysis of expression profiles under the iron-limited condition showed that the mutants were more sensitive for the changes of iron deficiency than the wild-type strains,many genes have been altered.Up-regulated genes mainly involved genes of transcription,coenzyme metabolism,amino acid transport and metabolism,and unknown functional genes,while down-regulated genes mainly involved genes of energy and carbohydrate metabolism and unknown function genes;the expression levels of known iron-transport associated genes generally showed up-regulated.The results demonstrated that iron-transport associated genes IroN,ShuA were likely to have some effects on the virulence and growth of S.dysenteriae.
文摘Comparative Genomic Hybridization (CGH) microarray analysis was used tocompare the genomic compositions of all eighteen Shigella boydii serotype representative strains.The results indicated the genomic ''backbone'' of this subgroup contained 2552 ORFs homologous tononpatho-genic E. coli K12. Compared with the genome of K12199 ORFs were found to be absent in allS. boydii serotype representatives, including mainly outer membrane protein genes and O-antigenbiosynthesis genes. Yet the specific ORFs of S. boydii subgroup contained basically bacteriophagegenes and the function unknown (FUN) genes. Some iron metabolism, transport and type Ⅱ secretionsystem related genes were found in most representative strains. According to the CGH phylogeneticanalysis, the eighteen S. boydii serotype representatives were divided into four groups, in whichserotype C13 strain was remarkably distinguished from the other serotype strains. This groupingresult corresponded to the distribution of some metabolism related genes. Furthermore, the analysisof genome backbone genes, specific genes, and the phylogenetic trees allowed us to discover theevolution laws of S. boydii and to find out important clues to pathogenesis research, vaccinationand the therapeutic medicine development.
