Meloidogyne spp.is an economically important plant-parasitic nematode distributed worldwide.To fight with host immune system for successful parasitism,plant parasitic nematodes secrete effectors to promote infection.I...Meloidogyne spp.is an economically important plant-parasitic nematode distributed worldwide.To fight with host immune system for successful parasitism,plant parasitic nematodes secrete effectors to promote infection.In this study,we identified one chorismate mutase(CM)effector from M.enterolobii,named Me-CM.Spatial and temporal expression assays exhibited Me-cm is expressed in esophageal glands and up-regulated at parasitic-stage juveniles.Me-CM affects the pathogenicity of M.enterolobii based on the reduced infection rate,number of galls,egg masses,eggs per mass and multiplication rate collected from RNA silencing experiments.We showed that Me-CM localized in the cytoplasm and nucleus of plant cells and decreased the expression level of the marker gene PR1 of salicylic acid(SA)pathway.Besides,constitutive expression of Me-cm in Arabidopsis thaliana significantly reduced salicylic acid concentration.These results suggested that M.enterolobii may secrete effector Me-CM to fight with plantimmunesystemsvia regulating SA signaling pathway when interacting with host plants,ultimately facilitating parasitism.展开更多
In order to clarify the main pathogens of tomato Fusarium wilt in Shanxi Province, China, morphological identification, elongation factor 1 alpha （EF-1α） sequence analysis, specific primer amplification and pathoge...In order to clarify the main pathogens of tomato Fusarium wilt in Shanxi Province, China, morphological identification, elongation factor 1 alpha （EF-1α） sequence analysis, specific primer amplification and pathogenicity tests were applied to study the isolates which were recovered from diseased plants collected from 17 different districts of Shanxi Province. The results were as follows： 1） Through morphological and molecular identification, the following 7 species of Fusarium were identified： F. oxysporum, F. solani, F. verticillioides, F. subglutinans, F. chlamydosporum, F. sporotrichioides, and F. semitectum; 2） 56 isolates of F. oxysporum were identified using specific primer amplification, among which, 29, 5 and 6 isolates were respectively identified as F. oxysporum f. sp. lycopersici physiological race 1, race 2, and race 3; 3） pathogenicity test indicated the significant pathogenicity of F. oxysporum, F. solani, F. verticillioides, and F. subglutinans to tomato plant. Therefore, among these 4 species confirmed as pathogenic to tomato in Shanxi, the highest isolation rate （53.3％） corresponded to F. oxysporum. Three physiological species, race 1, race 2, and race 3 of F. oxysporum f. sp. lycopersici are detected in Shanxi, among which race 1 is the most widespread pathogen and is also considered as the predominant race.展开更多
Pressure fluctuation due to rotor-stator interaction in turbomachinery is unavoidable,inducing strong vibration in the equipment and shortening its lifecycle.The investigation of optimization methods for an industrial...Pressure fluctuation due to rotor-stator interaction in turbomachinery is unavoidable,inducing strong vibration in the equipment and shortening its lifecycle.The investigation of optimization methods for an industrial centrifugal pump was carried out to reduce the intensity of pressure fluctuation to extend the lifecycle of these devices.Considering the time-consuming transient simulation of unsteady pressure,a novel optimization strategy was proposed by discretizing design variables and genetic algorithm.Four highly related design parameters were chosen,and 40 transient sample cases were generated and simulated using an automatic program.70%of them were used for training the surrogate model,and the others were for verifying the accuracy of the surrogate model.Furthermore,a modified discrete genetic algorithm(MDGA)was proposed to reduce the optimization cost owing to transient numerical simulation.For the benchmark test,the proposed MDGA showed a great advantage over the original genetic algorithm regarding searching speed and effectively dealt with the discrete variables by dramatically increasing the convergence rate.After optimization,the performance and stability of the inline pump were improved.The efficiency increased by more than 2.2%,and the pressure fluctuation intensity decreased by more than 20%under design condition.This research proposed an optimization method for reducing discrete transient characteristics in centrifugal pumps.展开更多
The cavitation has received considerable attention for decades because of its negative influence on the performance and the safety of the hydraulic machinery.In this study,a large eddy simulation is carried out to num...The cavitation has received considerable attention for decades because of its negative influence on the performance and the safety of the hydraulic machinery.In this study,a large eddy simulation is carried out to numerically investigate the unsteady cavitating flow around a trailing-truncated NACA 0009 hydrofoil for determining the underlying physical mechanisms.Two types of cavitation morphologies are identified:The large-scale bubble cluster and the von Kármán vortex cavity,named as the cloud cavitation and the wake vortex cavitation,respectively.It is shown that the velocity profiles obtained over the hydrofoil suction surface are in good agreement with the experimental data,indicating the accuracy of the current simulation.The dynamic evolution of the sheet/cloud cavity is also well reproduced,covering the sheet cavity breakup,the sheet/cloud transformation,and the collapse of the cloudy bubble cluster.The wake-vortex cavitation is caused by the blunt geometry at the hydrofoil trailing edge,where pairs of vortex cavities are induced.Both the cloud and vortex cavities significantly affect the lift oscillation,which makes it difficult to decompose the components.The fundamental shedding mechanisms of the wake vortex cavitation are discussed based on the finite-time Lyapunov exponent field.Specifically,the suction-side bubble grows and squeezes the giant pressure bubble away from the trailing edge.After the pressure bubble detaches,a new counterclockwise vortex or a new bubble appears at the pressure side,thus lifting the ridge towards the suction trailing edge and generating a strong vortex eye that pinches off the trailing portion of the suction-side bubble.展开更多
基金supported by the Hainan Provincial Natural Science Foundation of China(323MS102 and 320QN307)Central Public-Interest Scientific Institution Basal Research Fund,China(1630042022008)。
文摘Meloidogyne spp.is an economically important plant-parasitic nematode distributed worldwide.To fight with host immune system for successful parasitism,plant parasitic nematodes secrete effectors to promote infection.In this study,we identified one chorismate mutase(CM)effector from M.enterolobii,named Me-CM.Spatial and temporal expression assays exhibited Me-cm is expressed in esophageal glands and up-regulated at parasitic-stage juveniles.Me-CM affects the pathogenicity of M.enterolobii based on the reduced infection rate,number of galls,egg masses,eggs per mass and multiplication rate collected from RNA silencing experiments.We showed that Me-CM localized in the cytoplasm and nucleus of plant cells and decreased the expression level of the marker gene PR1 of salicylic acid(SA)pathway.Besides,constitutive expression of Me-cm in Arabidopsis thaliana significantly reduced salicylic acid concentration.These results suggested that M.enterolobii may secrete effector Me-CM to fight with plantimmunesystemsvia regulating SA signaling pathway when interacting with host plants,ultimately facilitating parasitism.
基金partially supported by the Shanxi Provincial Science and Technology Planning Project,China (20120311019-3)the Shanxi Provincial Science and Technology Foundation Platform Construction Project,China (1105-0104)the Shanxi Provincial Graduate Education Innovation Project,China (2017BY065)
文摘In order to clarify the main pathogens of tomato Fusarium wilt in Shanxi Province, China, morphological identification, elongation factor 1 alpha （EF-1α） sequence analysis, specific primer amplification and pathogenicity tests were applied to study the isolates which were recovered from diseased plants collected from 17 different districts of Shanxi Province. The results were as follows： 1） Through morphological and molecular identification, the following 7 species of Fusarium were identified： F. oxysporum, F. solani, F. verticillioides, F. subglutinans, F. chlamydosporum, F. sporotrichioides, and F. semitectum; 2） 56 isolates of F. oxysporum were identified using specific primer amplification, among which, 29, 5 and 6 isolates were respectively identified as F. oxysporum f. sp. lycopersici physiological race 1, race 2, and race 3; 3） pathogenicity test indicated the significant pathogenicity of F. oxysporum, F. solani, F. verticillioides, and F. subglutinans to tomato plant. Therefore, among these 4 species confirmed as pathogenic to tomato in Shanxi, the highest isolation rate （53.3％） corresponded to F. oxysporum. Three physiological species, race 1, race 2, and race 3 of F. oxysporum f. sp. lycopersici are detected in Shanxi, among which race 1 is the most widespread pathogen and is also considered as the predominant race.
基金Supported by National Key Research and Development Program of China(Grant No.2022YFC3202901)Natural Science Foundation of China(Grant No.51879121)+1 种基金Jiangsu Provincial Primary Research&Development Plan(Grant No.BE2019009-1)China Scholarship Council(Grant No.202108690020).
文摘Pressure fluctuation due to rotor-stator interaction in turbomachinery is unavoidable,inducing strong vibration in the equipment and shortening its lifecycle.The investigation of optimization methods for an industrial centrifugal pump was carried out to reduce the intensity of pressure fluctuation to extend the lifecycle of these devices.Considering the time-consuming transient simulation of unsteady pressure,a novel optimization strategy was proposed by discretizing design variables and genetic algorithm.Four highly related design parameters were chosen,and 40 transient sample cases were generated and simulated using an automatic program.70%of them were used for training the surrogate model,and the others were for verifying the accuracy of the surrogate model.Furthermore,a modified discrete genetic algorithm(MDGA)was proposed to reduce the optimization cost owing to transient numerical simulation.For the benchmark test,the proposed MDGA showed a great advantage over the original genetic algorithm regarding searching speed and effectively dealt with the discrete variables by dramatically increasing the convergence rate.After optimization,the performance and stability of the inline pump were improved.The efficiency increased by more than 2.2%,and the pressure fluctuation intensity decreased by more than 20%under design condition.This research proposed an optimization method for reducing discrete transient characteristics in centrifugal pumps.
基金This work was supported by the University of Padua Project of Investigation of Passive Suppression of Unsteady Cloud Cavitation(Grant No.2020DII142)The authors acknowledge the Italian CINECA for Providing the Computational Resources(Grant No.HP10CZ82QS)。
文摘The cavitation has received considerable attention for decades because of its negative influence on the performance and the safety of the hydraulic machinery.In this study,a large eddy simulation is carried out to numerically investigate the unsteady cavitating flow around a trailing-truncated NACA 0009 hydrofoil for determining the underlying physical mechanisms.Two types of cavitation morphologies are identified:The large-scale bubble cluster and the von Kármán vortex cavity,named as the cloud cavitation and the wake vortex cavitation,respectively.It is shown that the velocity profiles obtained over the hydrofoil suction surface are in good agreement with the experimental data,indicating the accuracy of the current simulation.The dynamic evolution of the sheet/cloud cavity is also well reproduced,covering the sheet cavity breakup,the sheet/cloud transformation,and the collapse of the cloudy bubble cluster.The wake-vortex cavitation is caused by the blunt geometry at the hydrofoil trailing edge,where pairs of vortex cavities are induced.Both the cloud and vortex cavities significantly affect the lift oscillation,which makes it difficult to decompose the components.The fundamental shedding mechanisms of the wake vortex cavitation are discussed based on the finite-time Lyapunov exponent field.Specifically,the suction-side bubble grows and squeezes the giant pressure bubble away from the trailing edge.After the pressure bubble detaches,a new counterclockwise vortex or a new bubble appears at the pressure side,thus lifting the ridge towards the suction trailing edge and generating a strong vortex eye that pinches off the trailing portion of the suction-side bubble.
