We report the formation and local electronic structure of Ge clusters on the Si（111）-7×7 surface studied by using variable temperature scanning tunnelling microscopy （VT-STM） and low-temperature scanning tunn...We report the formation and local electronic structure of Ge clusters on the Si（111）-7×7 surface studied by using variable temperature scanning tunnelling microscopy （VT-STM） and low-temperature scanning tunnelling spectroscopy （STS）. Atom-resolved STM images reveal that the Ce atoms are prone to forming clusters with 1.0 nm in diameter for coverage up to 0.12 ML. Such Ce clusters preferentially nucleate at the centre of the faulted-half unit cells, leading to the ＇dark sites＇ of Si centre adatoms from the surrounding three unfaulted-half unit cells in filled-state images. Biasdependent STM images show the charge transfer from the neighbouring Si adatoms to Ce clusters. Low-temperature STS of the Ce clusters reveals that there is a band gap on the Ce cluster and the large voltage threshold is about 0.9 V.展开更多
To construct the EGFR targeted non-viral vector GE7 system and explore the in vitro effect of p21^WAF-1/CIP1 gene on growth of human glioma cells mediated by the GE7 system. Methods: The EGFR targeted non-vi-ral vecto...To construct the EGFR targeted non-viral vector GE7 system and explore the in vitro effect of p21^WAF-1/CIP1 gene on growth of human glioma cells mediated by the GE7 system. Methods: The EGFR targeted non-vi-ral vector GET gene delivery system was constructed. The malignant human glioma cell llne U251MG was transfected in vitro with β-galactosidase gene( reporter gene) and p21^WAF-1/CIP1 gene (therapeutic gene) using the GET system. By means of X-gal staining, MTS and FACS, the transfection efficiency of exogenous gene and apoptosis rate of tumor cells were examined. The expression of p21^WAF-1/CIP1 gene in transfected U251MG cell was examined by immunohistochemitry staining. Results: The highest transfer rate of exogenous gene was 70%. After transfection with p21^WAF-l/CIP1 gene,the expression of WAF-1 increased remarkably and steadily; the growth of U251MG cells were inhibited evidently.FACS examination showed G1 arrest. The average apoptosis rate was 25.2%. Conclusion: GE7 system has the ability to transfer exogenous gene to targeted cells efficiently, and expression of p21^WAF-l/CIP1 gene can induce apoptosis of glio-ma cell and inhibit its growth.展开更多
基金Project supported by the National Natural Science Foundation of China （Grant Nos 90406022 and 10674159）.
文摘We report the formation and local electronic structure of Ge clusters on the Si（111）-7×7 surface studied by using variable temperature scanning tunnelling microscopy （VT-STM） and low-temperature scanning tunnelling spectroscopy （STS）. Atom-resolved STM images reveal that the Ce atoms are prone to forming clusters with 1.0 nm in diameter for coverage up to 0.12 ML. Such Ce clusters preferentially nucleate at the centre of the faulted-half unit cells, leading to the ＇dark sites＇ of Si centre adatoms from the surrounding three unfaulted-half unit cells in filled-state images. Biasdependent STM images show the charge transfer from the neighbouring Si adatoms to Ce clusters. Low-temperature STS of the Ce clusters reveals that there is a band gap on the Ce cluster and the large voltage threshold is about 0.9 V.
基金Supported by the National High Science and Technical Foundation of China(No. 102-12-02-05)
文摘To construct the EGFR targeted non-viral vector GE7 system and explore the in vitro effect of p21^WAF-1/CIP1 gene on growth of human glioma cells mediated by the GE7 system. Methods: The EGFR targeted non-vi-ral vector GET gene delivery system was constructed. The malignant human glioma cell llne U251MG was transfected in vitro with β-galactosidase gene( reporter gene) and p21^WAF-1/CIP1 gene (therapeutic gene) using the GET system. By means of X-gal staining, MTS and FACS, the transfection efficiency of exogenous gene and apoptosis rate of tumor cells were examined. The expression of p21^WAF-1/CIP1 gene in transfected U251MG cell was examined by immunohistochemitry staining. Results: The highest transfer rate of exogenous gene was 70%. After transfection with p21^WAF-l/CIP1 gene,the expression of WAF-1 increased remarkably and steadily; the growth of U251MG cells were inhibited evidently.FACS examination showed G1 arrest. The average apoptosis rate was 25.2%. Conclusion: GE7 system has the ability to transfer exogenous gene to targeted cells efficiently, and expression of p21^WAF-l/CIP1 gene can induce apoptosis of glio-ma cell and inhibit its growth.
