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| 1 | Overexpression of microRNA-124 promotes the neuronal differentiation of bone marrow-derived mesenchymal stem cells显示文摘microRNAs(miRNAs) play an important regulatory role in the self-renewal and differentiation of stem cells. In this study, we examined the effects of miRNA-124(miR-124) overexpression in bone marrow-derived mesenchymal stem cells. In particular, we focused on the effect of overexpression on the differentiation of bone marrow-derived mesenchymal stem cells into neurons. First, we used GeneChip technology to analyze the expression of miRNAs in bone marrow-derived mesenchymal stem cells, neural stem cells and neurons. miR-124 expression was substantially reduced in bone marrow-derived mesenchymal stem cells compared with the other cell types. We constructed a lentiviral vector overexpressing miR-124 and transfected it into bone marrow-derived mesenchymal stem cells. Intracellular expression levels of the neuronal early markers β-III tubulin and microtubule-associated protein-2 were significantly increased, and apoptosis induced by oxygen and glucose deprivation was reduced in transfected cells. After miR-124-transfected bone marrow-derived mesenchymal stem cells were transplanted into the injured rat spinal cord, a large number of cells positive for the neuronal marker neurofilament-200 were observed in the transplanted region. The Basso-Beattie-Bresnahan locomotion scores showed that the motor function of the hind limb of rats with spinal cord injury was substantially improved. These results suggest that miR-124 plays an important role in the differentiation of bone marrow-derived mesenchymal stem cells into neurons. Our findings should facilitate the development of novel strategies for enhancing the therapeutic efficacy of bone marrow-derived mesenchymal stem cell transplantation for spinal cord injury. | Defeng Zou Yi Chen Yaxin Han Chen Lv Guanjun Tu | 2014 | Neural Regeneration Research2014，9，12： | 15 |
| 2 | Spaceborne GPS receiver antenna phase center offset and variation estimation for the Shiyan 3 satellite显示文摘In determining the orbits of low Earth orbit(LEO) satellites using spaceborne GPS, the errors caused by receiver antenna phase center offset(PCO) and phase center variations(PCVs) are gradually becoming a major limiting factor for continued improvements to accuracy. Shiyan 3, a small satellite mission for space technology experimentation and climate exploration, was developed by China and launched on November 5, 2008. The dual-frequency GPS receiver payload delivers1 Hz data and provides the basis for precise orbit determination within the range of a few centimeters. The antenna PCO and PCV error characteristics and the principles influencing orbit determination are analyzed. The feasibility of PCO and PCV estimation and compensation in different directions is demonstrated through simulation and in-flight tests. The values of receiver antenna PCO and PCVs for Gravity Recovery and Climate Experiment(GRACE) and Shiyan 3 satellites are estimated from one month of data. A large and stable antenna PCO error, reaching up to10.34 cm in the z-direction, is found with the Shiyan 3 satellite. The PCVs on the Shiyan 3 satellite are estimated and reach up to 3.0 cm, which is slightly larger than that of GRACE satellites. Orbit validation clearly improved with independent k-band ranging(KBR) and satellite laser ranging(SLR) measurements. For GRACE satellites, the average root mean square(RMS) of KBR residuals improved from 1.01 cm to 0.88 cm. For the Shiyan 3 satellite, the average RMS of SLR residuals improved from 4.95 cm to 4.06 cm. | Gu Defeng Lai Yuwang Liu Junhong Ju Bing Tu Jia | 2016 | Chinese Journal of Aeronautics2016，29，5： | 11 |
| 3 | Phase Residual Estimations for PCVs of Spaceborne GPS Receiver Antenna and Their Impacts on Precise Orbit Determination of GRACE Satellites显示文摘In-flight phase center systematic errors of global positioning system(GPS) receiver antenna are the main restriction for improving the precision of precise orbit determination using dual-frequency GPS.Residual approach is one of the valid methods for in-flight calibration of GPS receiver antenna phase center variations(PCVs) from ground calibration.In this paper,followed by the correction model of spaceborne GPS receiver antenna phase center,ionosphere-free PCVs can be directly estimated by ionosphere-free carrier phase post-fit residuals of reduced dynamic orbit determination.By the data processing of gravity recovery and climate experiment(GRACE) satellites,the following conclusions are drawn.Firstly,the distributions of ionosphere-free carrier phase post-fit residuals from different periods have the similar systematic characteristics.Secondly,simulations show that the influence of phase residual estimations for ionosphere-free PCVs on orbit determination can reach the centimeter level.Finally,it is shown by in-flight data processing that phase residual estimations of current period could not only be used for the calibration for GPS receiver antenna phase center of foretime and current period,but also be used for the forecast of ionosphere-free PCVs in future period,and the accuracy of orbit determination can be well improved. | TU Jia GU Defeng WU Yi YI Dongyun | 2012 | Chinese Journal of Aeronautics2012，25，4： | 4 |
| 4 | Multiparameter fire detection based on wireless sensor network显示文摘 | Liu Shixing Tu Defeng Zhang Yongming | 2009 | Proceedings2009IEEE International Conference2009，58，11： | 1 |
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