Extended digital image correlation(X-DIC) method is one novel test method in experimental mechanics.In this paper,the principle of the X-DIC method was introduced in detail.A selection scheme of the initial value of N...Extended digital image correlation(X-DIC) method is one novel test method in experimental mechanics.In this paper,the principle of the X-DIC method was introduced in detail.A selection scheme of the initial value of Newton iteration method was proposed when Newton iteration method was applied to solve the partial differential equations.This scheme could make the X-DIC method suitable for the large deformation measurement and avoid the non-convergence phenomenon effectively.The performance of the X-DIC method was verified by simulated images.Since the pixel point with the maximum absolute error occurred mainly at the corner or on the interface of the region of interest(ROI,region used for correlation calculation),measured deformation of the core area(area surrounding the center point of the ROI with a smaller size) was taken as the reliable measured value.The measurement accuracy of the X-DIC method could be improved greatly by using the core area.Combined with a long-distance microscope,the X-DIC method could be used in the deformation measurement of the micro-region.Zero deformation experiment was done to test the precision of the measurement system.Then,the X-DIC method was applied to measure the micro-region deformation of the specimen with a crack.Test value was proved to be in accordance with the actual deformation,showing that the X-DIC method is suitable for the research of microscale mechanical behavior of materials.展开更多
The microstructures of 7.9/70/30 (Pb92.1La7.9)(Zr70Ti30)O3 (PLZT) transparent ferroelectric ceramics are studied by using the high-resolution electron microscopy (HREM) techniques and electron diffraction. The results...The microstructures of 7.9/70/30 (Pb92.1La7.9)(Zr70Ti30)O3 (PLZT) transparent ferroelectric ceramics are studied by using the high-resolution electron microscopy (HREM) techniques and electron diffraction. The results indicate that the structure of micro-domains presented in the cubic a-phase is exactly the same as that of its ferroelectric β-phase after poling. The fringe-shape micro-regions, appearing in the HREM microphotograph of 7.9/70/30 PLZT, are the result from lattice-overlapping of the orthorhomhic micro-domains and the cubic a-phase matrix. Furthermore, a 2×d111 superlattice along the <111>-direction has been observed in 7.9/70/30 PLZT ceramics. This is probably the result of gliding or rotation on the (111)-plane of self-structure regulation due to point defects.展开更多
The relationship between conformation change and activity of E. coli L-asparaginase hasbeen studied with circular dichroism spectra and microcaloric methods. In many papers [1-4],it has been pointed out that the activ...The relationship between conformation change and activity of E. coli L-asparaginase hasbeen studied with circular dichroism spectra and microcaloric methods. In many papers [1-4],it has been pointed out that the active site of L-asparaginase isclosely related to tyrosyl residues. The present authors[5] have studied the effects of L-cysteine on the activity and the conformation of L-asparaginase with UV difference spectraand kinetic methods. Moreover, we have studied the space arrangement of tyrosyl residuesin the enzyme molecule. The results show that every enzyme molecule contains about 56 tyrosylresidues,20 of which are in the hydrophobic core of the enzyme molecule, another 20 at thesurface of the enzyme molecule, and the rest in the rifts and hollows of the enzyme molecule.Meanwhile, further study has also been made to determine the relationship between the changesof the enzyme activity and the ionization of tyrosyl residues as well as their chemical modifica-tion. By Zou Chenglu’s graphical method we have proved that two tyrosyl residues at thesurface of the enzyme molecule are the essential groups.展开更多
Self-organized dithieno [3,2-b:2',3'-d] thiophene-2,5-dicarboxylic acid (A) and dithieno [2,3-b:3',2'-d] thiophene-2,5-dicarboxylic acid (B) films were prepared through solvent-induced order-disorder t...Self-organized dithieno [3,2-b:2',3'-d] thiophene-2,5-dicarboxylic acid (A) and dithieno [2,3-b:3',2'-d] thiophene-2,5-dicarboxylic acid (B) films were prepared through solvent-induced order-disorder transition method.The arrangement of the two molecules on substrates were observed by atomic force microscopy (AFM),which demonstrated that A was arranged orderly in a certain angle on mica,while B was flat-flying on mica.The optical and conductance properties in micro region of these two compound films were characterized by UV-vis absorption spectroscopy,fluorescence spectroscopy and conductive atomic force microscopy (C-AFM).The results revealed that the fluorescence and absorption peaks of A had a large red shift in comparison with those of B.The conductance of the J-aggregates for A is three orders magnitude higher than that of B.It is concluded that the large conductance difference mainly comes from different aggregation structures and orientations of these two molecules on substrate.展开更多
The present research investigated a segment of the micro-arthropod populations residing within nests of Messor arenarius ants in the Negev Desert of Israel. The total frequencies of micro-arthropods in the chaff of th...The present research investigated a segment of the micro-arthropod populations residing within nests of Messor arenarius ants in the Negev Desert of Israel. The total frequencies of micro-arthropods in the chaff of those ants’ nests were found to be higher than in the surrounding soil of the same nests. Acari (mites) were observed to be more abundant during the spring season, whereas their presence decreased during the summer months. Springtails (Collembola) were found to follow the Acari pattern, commonly found within the nests of those ants during spring but were absent during summer. Psocoptera order inhabiting soil habitats were infrequently encountered during spring, but their prevalence increased significantly during summer, particularly within the chaff of the ants’ nests, suggesting that chaff is their primary food source in the Negev Desert. Our research suggests that shifts in seasonality have important consequences on the distribution of soil invertebrate communities with implications on nutrient cycling.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 10772133 and 11072172)the Doctoral Fund of Ministry of Education of China (Grant No. 20090032110006)
文摘Extended digital image correlation(X-DIC) method is one novel test method in experimental mechanics.In this paper,the principle of the X-DIC method was introduced in detail.A selection scheme of the initial value of Newton iteration method was proposed when Newton iteration method was applied to solve the partial differential equations.This scheme could make the X-DIC method suitable for the large deformation measurement and avoid the non-convergence phenomenon effectively.The performance of the X-DIC method was verified by simulated images.Since the pixel point with the maximum absolute error occurred mainly at the corner or on the interface of the region of interest(ROI,region used for correlation calculation),measured deformation of the core area(area surrounding the center point of the ROI with a smaller size) was taken as the reliable measured value.The measurement accuracy of the X-DIC method could be improved greatly by using the core area.Combined with a long-distance microscope,the X-DIC method could be used in the deformation measurement of the micro-region.Zero deformation experiment was done to test the precision of the measurement system.Then,the X-DIC method was applied to measure the micro-region deformation of the specimen with a crack.Test value was proved to be in accordance with the actual deformation,showing that the X-DIC method is suitable for the research of microscale mechanical behavior of materials.
文摘The microstructures of 7.9/70/30 (Pb92.1La7.9)(Zr70Ti30)O3 (PLZT) transparent ferroelectric ceramics are studied by using the high-resolution electron microscopy (HREM) techniques and electron diffraction. The results indicate that the structure of micro-domains presented in the cubic a-phase is exactly the same as that of its ferroelectric β-phase after poling. The fringe-shape micro-regions, appearing in the HREM microphotograph of 7.9/70/30 PLZT, are the result from lattice-overlapping of the orthorhomhic micro-domains and the cubic a-phase matrix. Furthermore, a 2×d111 superlattice along the <111>-direction has been observed in 7.9/70/30 PLZT ceramics. This is probably the result of gliding or rotation on the (111)-plane of self-structure regulation due to point defects.
文摘The relationship between conformation change and activity of E. coli L-asparaginase hasbeen studied with circular dichroism spectra and microcaloric methods. In many papers [1-4],it has been pointed out that the active site of L-asparaginase isclosely related to tyrosyl residues. The present authors[5] have studied the effects of L-cysteine on the activity and the conformation of L-asparaginase with UV difference spectraand kinetic methods. Moreover, we have studied the space arrangement of tyrosyl residuesin the enzyme molecule. The results show that every enzyme molecule contains about 56 tyrosylresidues,20 of which are in the hydrophobic core of the enzyme molecule, another 20 at thesurface of the enzyme molecule, and the rest in the rifts and hollows of the enzyme molecule.Meanwhile, further study has also been made to determine the relationship between the changesof the enzyme activity and the ionization of tyrosyl residues as well as their chemical modifica-tion. By Zou Chenglu’s graphical method we have proved that two tyrosyl residues at thesurface of the enzyme molecule are the essential groups.
基金supported by the National Natural Science Foundation of China (Grant Nos.20672028,10874040,20803018)Program for New Century Excellent Talent in University (Grant Nos.NCET-04-0653,NCET-05-0610)Cultivation Fund of Key Scientific and Technical Innovation Project,Ministry of Education of China (Grant No.708062)
文摘Self-organized dithieno [3,2-b:2',3'-d] thiophene-2,5-dicarboxylic acid (A) and dithieno [2,3-b:3',2'-d] thiophene-2,5-dicarboxylic acid (B) films were prepared through solvent-induced order-disorder transition method.The arrangement of the two molecules on substrates were observed by atomic force microscopy (AFM),which demonstrated that A was arranged orderly in a certain angle on mica,while B was flat-flying on mica.The optical and conductance properties in micro region of these two compound films were characterized by UV-vis absorption spectroscopy,fluorescence spectroscopy and conductive atomic force microscopy (C-AFM).The results revealed that the fluorescence and absorption peaks of A had a large red shift in comparison with those of B.The conductance of the J-aggregates for A is three orders magnitude higher than that of B.It is concluded that the large conductance difference mainly comes from different aggregation structures and orientations of these two molecules on substrate.
文摘The present research investigated a segment of the micro-arthropod populations residing within nests of Messor arenarius ants in the Negev Desert of Israel. The total frequencies of micro-arthropods in the chaff of those ants’ nests were found to be higher than in the surrounding soil of the same nests. Acari (mites) were observed to be more abundant during the spring season, whereas their presence decreased during the summer months. Springtails (Collembola) were found to follow the Acari pattern, commonly found within the nests of those ants during spring but were absent during summer. Psocoptera order inhabiting soil habitats were infrequently encountered during spring, but their prevalence increased significantly during summer, particularly within the chaff of the ants’ nests, suggesting that chaff is their primary food source in the Negev Desert. Our research suggests that shifts in seasonality have important consequences on the distribution of soil invertebrate communities with implications on nutrient cycling.
