Nanoindentation tests performed in a commercial atomic force microscope have been utilized to directly measure the elastic modulus and the hardness of single crystal copper thin films fabricated by the vacuum vapor de...Nanoindentation tests performed in a commercial atomic force microscope have been utilized to directly measure the elastic modulus and the hardness of single crystal copper thin films fabricated by the vacuum vapor deposition technique. Nanoindentation tests were conducted at various indentation depths to study the effect of indentation depths on the mechanical properties of thin films. The results were interpreted by using the Oliver-Pharr method with which direct observation and measurement of the contact area are not required. The elastic modulus of the single crystal copper film at various indentation depths was determined as (67.0±(6.9) GPa) on average which is in reasonable agreement with the results reported in literature. The indentation hardness constantly increases with decreasing indentation depth, indicating a strong size effect.展开更多
Cell-free system is interesting and useful for studying nuclear assembly in mitosis. Atomic force micro- scopy (AFM), which is a simple way for imaging fixed reas-semble nuclei with high resolution, has not been used ...Cell-free system is interesting and useful for studying nuclear assembly in mitosis. Atomic force micro- scopy (AFM), which is a simple way for imaging fixed reas-semble nuclei with high resolution, has not been used in the cell-free system. In this paper, we put forward an air-drying sample preparation for AFM. Using AFM, we observed nu-clear reassembly process within 100 nm resolution in a cell-free system. As a result, we found that the images were artifact-free, and with higher resolution compared with fluo-rescent optical microscope images. Furthermore, the mor-phology of membrane vesicles was obtained clearly, and a dynamic change of morphology during the vesicles?ap-proaching to nuclear envelope was also observed, which is enlightened to understand the mechanism of nuclear enve-lope assembly.展开更多
文摘Nanoindentation tests performed in a commercial atomic force microscope have been utilized to directly measure the elastic modulus and the hardness of single crystal copper thin films fabricated by the vacuum vapor deposition technique. Nanoindentation tests were conducted at various indentation depths to study the effect of indentation depths on the mechanical properties of thin films. The results were interpreted by using the Oliver-Pharr method with which direct observation and measurement of the contact area are not required. The elastic modulus of the single crystal copper film at various indentation depths was determined as (67.0±(6.9) GPa) on average which is in reasonable agreement with the results reported in literature. The indentation hardness constantly increases with decreasing indentation depth, indicating a strong size effect.
基金supported by the National Natural Science Foundation of China(Grant Nos.19890380 and 30070388)the Special Funds for the Major State Bask Research of China(Grant No.G19990539).
文摘Cell-free system is interesting and useful for studying nuclear assembly in mitosis. Atomic force micro- scopy (AFM), which is a simple way for imaging fixed reas-semble nuclei with high resolution, has not been used in the cell-free system. In this paper, we put forward an air-drying sample preparation for AFM. Using AFM, we observed nu-clear reassembly process within 100 nm resolution in a cell-free system. As a result, we found that the images were artifact-free, and with higher resolution compared with fluo-rescent optical microscope images. Furthermore, the mor-phology of membrane vesicles was obtained clearly, and a dynamic change of morphology during the vesicles?ap-proaching to nuclear envelope was also observed, which is enlightened to understand the mechanism of nuclear enve-lope assembly.
