To investigate the progressive fracture processes around a tunnel triggered by static stress and dynamic disturbance,experiments and numerical simulations were performed.The results show that the spatial distributions...To investigate the progressive fracture processes around a tunnel triggered by static stress and dynamic disturbance,experiments and numerical simulations were performed.The results show that the spatial distributions of acoustic emission(AE)events become very different as lateral pressure coefficients change.The combined effect of static stress and dynamic disturbance causes the damage around the tunnel,and initial stress conditions control the damage morphology.The blast disturbance cannot fundamentally change the damaged area but will deepen the extent of damage and accelerate the failure speed.The more significant the difference between the vertical and horizontal stresses is,the higher the impact on the tunnel by the dynamic disturbance is.The AE activity recovers to a relatively stable state within a short time after the blast and conforms to power-law characteristics.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
The dynamic response and energy absorption performance of foam-filled tubes under lateral external blast loading were investigated experimentally and numerically.A series of blast tests for the foam-filled tubes with ...The dynamic response and energy absorption performance of foam-filled tubes under lateral external blast loading were investigated experimentally and numerically.A series of blast tests for the foam-filled tubes with different geometric parameters were carried out by the use of the ballistic pendulum system.Experimental results were compared with the numerical simulation results employing the software ABAQUS.The results showed that the finite element(FE)analysis was in good agreement with the experimental data.The effects of the diameter and wall thickness of the outer tube,the TNT explosive charge mass,and the standoff distance on the deformation modes,the blast resistance,and the energy absorption performance of the foam-filled tubes were investigated.Three deformation modes of the foam-filled tubes were observed under the lateral external blast loading,including local plastic deformation,large plastic deformation with an elliptic shape,and the tearing of the outer tube.The result revealed that the introduction of the foam core played a vital role in the deflection and energy absorption capacity of the structure.This study provided effective guidelines for designing foam-filled tubes with high energy absorption efficiency.展开更多
为更好地解决露天爆破参数优化问题,引入了可爆性系数k这一指标。基于爆破漏斗理论,建立了露天台阶爆破分析模型,得到了可爆性系数k与抵抗线、装药高度之间的关系方程,获得了炮孔直径分别为90、150、200和250 mm 4种情况下抵抗线W与装...为更好地解决露天爆破参数优化问题,引入了可爆性系数k这一指标。基于爆破漏斗理论,建立了露天台阶爆破分析模型,得到了可爆性系数k与抵抗线、装药高度之间的关系方程,获得了炮孔直径分别为90、150、200和250 mm 4种情况下抵抗线W与装药高度h的关系曲线,以及孔径200 mm时的a-h、k-W关系曲线。根据高村采场侧向爆破漏斗试验结果,确定试验区岩体的可爆性系数k=1.07,推荐矿山的抵抗线控制在7.5~8.0 m较为合适。展开更多
基金Project(2017YFC0602904)supported by the National Key Research and Development Program of ChinaProject(51974059)supported by the National Natural Science Foundation of ChinaProject(N180115010)supported by the Fundamental Research Funds for the Central Universities,China。
文摘To investigate the progressive fracture processes around a tunnel triggered by static stress and dynamic disturbance,experiments and numerical simulations were performed.The results show that the spatial distributions of acoustic emission(AE)events become very different as lateral pressure coefficients change.The combined effect of static stress and dynamic disturbance causes the damage around the tunnel,and initial stress conditions control the damage morphology.The blast disturbance cannot fundamentally change the damaged area but will deepen the extent of damage and accelerate the failure speed.The more significant the difference between the vertical and horizontal stresses is,the higher the impact on the tunnel by the dynamic disturbance is.The AE activity recovers to a relatively stable state within a short time after the blast and conforms to power-law characteristics.
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.
基金the National Natural Science Foundation of China(11772216,12072219 and 11902215)。
文摘The dynamic response and energy absorption performance of foam-filled tubes under lateral external blast loading were investigated experimentally and numerically.A series of blast tests for the foam-filled tubes with different geometric parameters were carried out by the use of the ballistic pendulum system.Experimental results were compared with the numerical simulation results employing the software ABAQUS.The results showed that the finite element(FE)analysis was in good agreement with the experimental data.The effects of the diameter and wall thickness of the outer tube,the TNT explosive charge mass,and the standoff distance on the deformation modes,the blast resistance,and the energy absorption performance of the foam-filled tubes were investigated.Three deformation modes of the foam-filled tubes were observed under the lateral external blast loading,including local plastic deformation,large plastic deformation with an elliptic shape,and the tearing of the outer tube.The result revealed that the introduction of the foam core played a vital role in the deflection and energy absorption capacity of the structure.This study provided effective guidelines for designing foam-filled tubes with high energy absorption efficiency.
文摘为更好地解决露天爆破参数优化问题,引入了可爆性系数k这一指标。基于爆破漏斗理论,建立了露天台阶爆破分析模型,得到了可爆性系数k与抵抗线、装药高度之间的关系方程,获得了炮孔直径分别为90、150、200和250 mm 4种情况下抵抗线W与装药高度h的关系曲线,以及孔径200 mm时的a-h、k-W关系曲线。根据高村采场侧向爆破漏斗试验结果,确定试验区岩体的可爆性系数k=1.07,推荐矿山的抵抗线控制在7.5~8.0 m较为合适。
