It is always desirable to know the interior deformation pattern when a rock is subjected to mechanicalload. Few experimental techniques exist that can represent full-field three-dimensional （3D） straindistribution i...It is always desirable to know the interior deformation pattern when a rock is subjected to mechanicalload. Few experimental techniques exist that can represent full-field three-dimensional （3D） straindistribution inside a rock specimen. And yet it is crucial that this information is available for fully understandingthe failure mechanism of rocks or other geomaterials. In this study, by using the newlydeveloped digital volumetric speckle photography （DVSP） technique in conjunction with X-ray computedtomography （CT） and taking advantage of natural 3D speckles formed inside the rock due to materialimpurities and voids, we can probe the interior of a rock to map its deformation pattern under load andshed light on its failure mechanism. We apply this technique to the analysis of a red sandstone specimenunder increasing uniaxial compressive load applied incrementally. The full-field 3D displacement fieldsare obtained in the specimen as a function of the load, from which both the volumetric and the deviatoricstrain fields are calculated. Strain localization zones which lead to the eventual failure of the rock areidentified. The results indicate that both shear and tension are contributing factors to the failuremechanism. 2015 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.展开更多
Detection of local strain at the nanometer scale with high sensitivity remains challenging.Here we report near-field infrared nano-imaging of local strains in bilayer graphene by probing strain-induced shifts of phono...Detection of local strain at the nanometer scale with high sensitivity remains challenging.Here we report near-field infrared nano-imaging of local strains in bilayer graphene by probing strain-induced shifts of phonon frequency.As a non-polar crystal,intrinsic bilayer graphene possesses little infrared response at its transverse optical phonon frequency.The reported optical detection of local strain is enabled by applying a vertical electrical field that breaks the symmetry of the two graphene layers and introduces finite electrical dipole moment to graphene phonon.The activated phonon further interacts with continuum electronic transitions,and generates a strong Fano resonance.The resulted Fano resonance features a very sharp near-field infrared scattering peak,which leads to an extraordinary sensitivity of-0.002%for the strain detection.Our results demonstrate the first nano-scale near-field Fano resonance,provide a new way to probe local strains with high sensitivity in non-polar crystals,and open exciting possibilities for studying strain-induced rich phenomena.展开更多
A reasonable evaluation of unloading deformation characteristics is of great significance for the effective analysis of deformation and stability of surrounding rocks after underground excavation.In this study,the dam...A reasonable evaluation of unloading deformation characteristics is of great significance for the effective analysis of deformation and stability of surrounding rocks after underground excavation.In this study,the damage-controlled cyclic triaxial loading tests were conducted to investigate the pore compaction mechanism and its influences on the unloading deformation behavior of red sandstone,including Young’s modulus,Poisson’s ratio,volumetric strain,and irreversible strain.The experimental results show that the increases of volumetric and irreversible strains of rocks can be attributed to the compaction mechanism,which almost dominates the entire pre-peak deformation process.The unloading deformation consists of the reversible linear and nonlinear strains,and the irreversible strain under the influence of the porous grain structure.The pre-peak Young’s modulus tends to increase and then decrease due to the influence of the unloading irreversible strain.However,it hardly changes with the increasing volumetric strain compaction under the influence of reversible nonlinear strain.Instead,the initial unloading tangent modulus is highly related to the volumetric strain,and clearly reflects the compaction state of red sandstone.Furthermore,both the reversible nonlinear and irreversible unloading deformations are independent of confining pressure.This study is beneficial for the theoretical modeling and prediction of cyclic unloading deformation behavior of red sandstone.展开更多
The objective of this research was to evaluate the muscle growth of the Nile tilapias of Thai and supreme strain. Hyperplasia and hypertrophy of muscle fibers were studied by histology. The fish were cultivated in cag...The objective of this research was to evaluate the muscle growth of the Nile tilapias of Thai and supreme strain. Hyperplasia and hypertrophy of muscle fibers were studied by histology. The fish were cultivated in cages in a dam and as they grew they were weighed and measured in length. In tissue samples, it was evaluated the quantity of cells area~ and the diameter of the white, pink and red muscle fibers. The supreme strain presented greater number of white and pink fibers mm2 and smaller number of red fibers when compared to the Thai strain. 5-10 cm fish presented higher number of white, pink and red fibers mm： and smaller average diameter of the white and pink fibers, when compared to a 10-15 cm fish. The average diameter of the white and pink fibers increased in 10-15 cm fish, compared to 5-10 era. White fibers smaller than 10 ~tm were found only in the 5-10 cm supreme strain. Tilapias of Thai and supreme strain presented different standard distribution of red, pink and white muscle fibers. Supreme strain, genetically improved, presented higher hyperplasia of white fibers than Thai strain, and this can indicate its higher potential growth.展开更多
大肠杆菌的rnc基因编码产物为RNaseIII酶,RNaseIII酶能降解细菌中绝大多数dsRNA。利用来源于λ噬菌体的Red重组系统和重叠延伸PCR技术(gene splicing by overlap extension PCR,SOE-PCR),敲除了大肠杆菌origami(DE3)菌株的rnc基因,获得...大肠杆菌的rnc基因编码产物为RNaseIII酶,RNaseIII酶能降解细菌中绝大多数dsRNA。利用来源于λ噬菌体的Red重组系统和重叠延伸PCR技术(gene splicing by overlap extension PCR,SOE-PCR),敲除了大肠杆菌origami(DE3)菌株的rnc基因,获得了RNaseIII缺失型菌株M-origami。利用电激法,将构建的TMV运动蛋白基因(movement protein gene,MP)的dsRNA表达载体LMP480导入M-origami菌株中,IPTG诱导表达的结果显示:构建的M-origami/LMP480原核表达系统能高效表达TMV运动蛋白基因的dsRNA。初步的抗病性鉴定显示,表达的dsRNA能够诱发烟草对TMV的抗性。展开更多
基金financially supported by National Basic Research Program of China (973 Program) (No. 2010CB732002)National Natural Science Foundation of China (Nos. 51374211, 51374215)+1 种基金National Key Foundation for Exploring Scientific Instrument of China (No. 2013YQ240803)Fundamental Research Funds for the Central Universities (No. 2009QM02)
文摘It is always desirable to know the interior deformation pattern when a rock is subjected to mechanicalload. Few experimental techniques exist that can represent full-field three-dimensional （3D） straindistribution inside a rock specimen. And yet it is crucial that this information is available for fully understandingthe failure mechanism of rocks or other geomaterials. In this study, by using the newlydeveloped digital volumetric speckle photography （DVSP） technique in conjunction with X-ray computedtomography （CT） and taking advantage of natural 3D speckles formed inside the rock due to materialimpurities and voids, we can probe the interior of a rock to map its deformation pattern under load andshed light on its failure mechanism. We apply this technique to the analysis of a red sandstone specimenunder increasing uniaxial compressive load applied incrementally. The full-field 3D displacement fieldsare obtained in the specimen as a function of the load, from which both the volumetric and the deviatoricstrain fields are calculated. Strain localization zones which lead to the eventual failure of the rock areidentified. The results indicate that both shear and tension are contributing factors to the failuremechanism. 2015 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.
基金Supported by the National Key Research and Development Program of China (Grant No.2016YFA0302001)the National Natural Science Foundation of China (Grant Nos.11774224,12074244,11521404,and 61701394)+1 种基金support from the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learningadditional support from a Shanghai talent program。
文摘Detection of local strain at the nanometer scale with high sensitivity remains challenging.Here we report near-field infrared nano-imaging of local strains in bilayer graphene by probing strain-induced shifts of phonon frequency.As a non-polar crystal,intrinsic bilayer graphene possesses little infrared response at its transverse optical phonon frequency.The reported optical detection of local strain is enabled by applying a vertical electrical field that breaks the symmetry of the two graphene layers and introduces finite electrical dipole moment to graphene phonon.The activated phonon further interacts with continuum electronic transitions,and generates a strong Fano resonance.The resulted Fano resonance features a very sharp near-field infrared scattering peak,which leads to an extraordinary sensitivity of-0.002%for the strain detection.Our results demonstrate the first nano-scale near-field Fano resonance,provide a new way to probe local strains with high sensitivity in non-polar crystals,and open exciting possibilities for studying strain-induced rich phenomena.
基金supported by the National Natural Science Foundation of China(Grant No.52109135)the Key R&D Projects of Sichuan Province,China(Grant No.2022YFSY0007)the Postdoctoral Research Foundation of China(Grant No.2019M653402).
文摘A reasonable evaluation of unloading deformation characteristics is of great significance for the effective analysis of deformation and stability of surrounding rocks after underground excavation.In this study,the damage-controlled cyclic triaxial loading tests were conducted to investigate the pore compaction mechanism and its influences on the unloading deformation behavior of red sandstone,including Young’s modulus,Poisson’s ratio,volumetric strain,and irreversible strain.The experimental results show that the increases of volumetric and irreversible strains of rocks can be attributed to the compaction mechanism,which almost dominates the entire pre-peak deformation process.The unloading deformation consists of the reversible linear and nonlinear strains,and the irreversible strain under the influence of the porous grain structure.The pre-peak Young’s modulus tends to increase and then decrease due to the influence of the unloading irreversible strain.However,it hardly changes with the increasing volumetric strain compaction under the influence of reversible nonlinear strain.Instead,the initial unloading tangent modulus is highly related to the volumetric strain,and clearly reflects the compaction state of red sandstone.Furthermore,both the reversible nonlinear and irreversible unloading deformations are independent of confining pressure.This study is beneficial for the theoretical modeling and prediction of cyclic unloading deformation behavior of red sandstone.
文摘The objective of this research was to evaluate the muscle growth of the Nile tilapias of Thai and supreme strain. Hyperplasia and hypertrophy of muscle fibers were studied by histology. The fish were cultivated in cages in a dam and as they grew they were weighed and measured in length. In tissue samples, it was evaluated the quantity of cells area~ and the diameter of the white, pink and red muscle fibers. The supreme strain presented greater number of white and pink fibers mm2 and smaller number of red fibers when compared to the Thai strain. 5-10 cm fish presented higher number of white, pink and red fibers mm： and smaller average diameter of the white and pink fibers, when compared to a 10-15 cm fish. The average diameter of the white and pink fibers increased in 10-15 cm fish, compared to 5-10 era. White fibers smaller than 10 ~tm were found only in the 5-10 cm supreme strain. Tilapias of Thai and supreme strain presented different standard distribution of red, pink and white muscle fibers. Supreme strain, genetically improved, presented higher hyperplasia of white fibers than Thai strain, and this can indicate its higher potential growth.
文摘大肠杆菌的rnc基因编码产物为RNaseIII酶,RNaseIII酶能降解细菌中绝大多数dsRNA。利用来源于λ噬菌体的Red重组系统和重叠延伸PCR技术(gene splicing by overlap extension PCR,SOE-PCR),敲除了大肠杆菌origami(DE3)菌株的rnc基因,获得了RNaseIII缺失型菌株M-origami。利用电激法,将构建的TMV运动蛋白基因(movement protein gene,MP)的dsRNA表达载体LMP480导入M-origami菌株中,IPTG诱导表达的结果显示:构建的M-origami/LMP480原核表达系统能高效表达TMV运动蛋白基因的dsRNA。初步的抗病性鉴定显示,表达的dsRNA能够诱发烟草对TMV的抗性。
