We study a two-dimensional granular rapid flow with rough sidewalls stuck with the same size discs by molecular dynamics simulation. A transient state of the double-humped density profile in the flowing process has be...We study a two-dimensional granular rapid flow with rough sidewalls stuck with the same size discs by molecular dynamics simulation. A transient state of the double-humped density profile in the flowing process has been found, which appears and moves as travelling wave and is the same as the phenomena in the recent experiments [Acta Phys. Sin. 53 （2004） 3389 （in Chinese）]. Our simulation shows that the rough sidewalls play an important role in the converting momentum of boundary discs from the vertical direction to the horizontal one through particle collisions to form this profile and the good elasticity of discs ensures this effect. The appearance of the double-humped profile may be a precursor, which determines if the whole flow will be far repulsed from the boundary and become dilute eventually.展开更多
Wheat blast,caused by the fungus Magnaporthe oryzae Triticum(MoT)pathotype,is a devastating disease persistent in South America and Bangladesh.Since MoT generally fails to cause visual symptoms in wheat until the head...Wheat blast,caused by the fungus Magnaporthe oryzae Triticum(MoT)pathotype,is a devastating disease persistent in South America and Bangladesh.Since MoT generally fails to cause visual symptoms in wheat until the heading stage when the infection would have advanced,disease control by fungicide application solely based on the detection of visual symptoms is ineffective.To develop an accurate and sensitive method to detect MoT at the seedling and vegetative stages for disease control,we sequenced the genomes of two MoT isolates from Brazil and identified two DNA fragments,MoT-6098 and MoT-6099,that are present in the MoT genome but not in the genome of the rice-infecting Magnaporthe oryzae Oryzae(MoO)pathotype.Using polymerase chain reaction(PCR),we confirmed the specificity of the two markers in 53 MoT and MoO isolates from South America and Bangladesh.To test the efficiency of the two markers,we first established a loop-mediated isothermal amplification(LAMP)method to detect MoT at isothermal conditions,without the use of a PCR machine.Following this,we used the Cas12a protein and guide RNAs(gRNAs)to target the MoT-6098 and MoT-6099 sequences.The activated Cas12a showed indiscriminate single-stranded deoxyribonuclease(ssDNase)activity.We then combined targetdependent Cas12a ssDNase activation with recombinase polymerase amplification(RPA)and nucleic acid lateral flow immunoassay(NALFIA)to develop a method that accurately,sensitively,and cost-effectively detects MoT-specific DNA sequences in infected wheat plants.This novel technique can be easily adapted for the rapid detection of wheat blast and other important plant diseases in the field.展开更多
基金Supported by the National Hi-Tech Inertial Confinement Fusion Committee under Grant No 202AA84ts06, and the National Natural Science Foundation of China under Grant No 10274071.
文摘We study a two-dimensional granular rapid flow with rough sidewalls stuck with the same size discs by molecular dynamics simulation. A transient state of the double-humped density profile in the flowing process has been found, which appears and moves as travelling wave and is the same as the phenomena in the recent experiments [Acta Phys. Sin. 53 （2004） 3389 （in Chinese）]. Our simulation shows that the rough sidewalls play an important role in the converting momentum of boundary discs from the vertical direction to the horizontal one through particle collisions to form this profile and the good elasticity of discs ensures this effect. The appearance of the double-humped profile may be a precursor, which determines if the whole flow will be far repulsed from the boundary and become dilute eventually.
基金The data that support the findings of this study have being submitted to GenBank and the accession numbers are JAAXMV000000000 and JAAXMU000000000.
文摘Wheat blast,caused by the fungus Magnaporthe oryzae Triticum(MoT)pathotype,is a devastating disease persistent in South America and Bangladesh.Since MoT generally fails to cause visual symptoms in wheat until the heading stage when the infection would have advanced,disease control by fungicide application solely based on the detection of visual symptoms is ineffective.To develop an accurate and sensitive method to detect MoT at the seedling and vegetative stages for disease control,we sequenced the genomes of two MoT isolates from Brazil and identified two DNA fragments,MoT-6098 and MoT-6099,that are present in the MoT genome but not in the genome of the rice-infecting Magnaporthe oryzae Oryzae(MoO)pathotype.Using polymerase chain reaction(PCR),we confirmed the specificity of the two markers in 53 MoT and MoO isolates from South America and Bangladesh.To test the efficiency of the two markers,we first established a loop-mediated isothermal amplification(LAMP)method to detect MoT at isothermal conditions,without the use of a PCR machine.Following this,we used the Cas12a protein and guide RNAs(gRNAs)to target the MoT-6098 and MoT-6099 sequences.The activated Cas12a showed indiscriminate single-stranded deoxyribonuclease(ssDNase)activity.We then combined targetdependent Cas12a ssDNase activation with recombinase polymerase amplification(RPA)and nucleic acid lateral flow immunoassay(NALFIA)to develop a method that accurately,sensitively,and cost-effectively detects MoT-specific DNA sequences in infected wheat plants.This novel technique can be easily adapted for the rapid detection of wheat blast and other important plant diseases in the field.
