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The National Time Service Center (NTSC), Chinese Academy of Sciences (CAS), Xi'an, China, has developed a method for common-view time transfer using Geostationary Earth Orbit (GEO) satellite (GCV) applicable to the time and frequency transfer at distant stations. This method is independent of Global Navigation Satellite System (GNSS) time and frequency transfer, as well as two-way satellite time and frequency transfer (TWSTFT). A master clock at the time laboratory transmits pseudorandom code signals to a GEO telecommunication satellite, and the time signals are retransmitted by the satellite. Receivers at the time laboratory and user locations coincidentally receive the time signals, and the offsets between the user clocks and the master clock of the time laboratory are determined with high precision if the precise coordinates of the user locations are known. For this technology, only a parabolic antenna with receiver devices and a demodulator are required at each user station, but the coordinates and precise orbits need to be obtained in advance. The key features of GCV include 1) continuous coverage of the signal from GEO communication satellites; 2) differential observations to reduce the effects of orbit error and the imprecision of the propagation delay model; 3) using a very small aperture terminal (VSAT) to enhance high signal ratio to noise to obtain precise ranging accuracy and antimultipath ability; and 4) utilizing the C-band or Ku-band to decrease the impact of the ionosphere. Experiments based on the TWSTFT network of CAS showed that the performance of GCV was at the same level as that of TWSTFT, and the rms of the residuals of GCV was less than 1.5 ns with respect to TWSTFT.

The present study aimed to investigate the protective effects of salidroside (SAL) on 1-methyl-4-phenylpyridinium (MPP+ )-induced PC12 cell model for Parkinson's disease. PC12 cells were pretreated with SAL in different concentrations and then exposed to MPP+ . To evaluate the effects of SAL on cytotoxicity, the survival rate was tested by the 3-(4,5-dimethylthiazol-2-yl)-2,5-dimethyltetrazolium bromide (MTT) assay and the apoptosis was tested via flow cytometry and Western blot. Reactive oxygen species (ROS), glutathione (GSH), and malondialdehyde (MDA) were detected to analyze the effects of SAL on oxidative stress. The mRNA and protein levels of inflammatory factors TNF-α and IL-1β were also determined by real-time quantitative polymerase chain reaction and Western blot. Pretreatment with SAL effectively relieved the MPP+ cytotoxic effects and decreased the release of ROS production and inflammatory cytokines. SAL also inhibited apoptosis, suppressed MDA activity, and increased GSH levels in MPP+ -treated PC12 cells. Moreover, the expression levels of caspase-9, caspase-3, and Bax were significantly decreased in the SAL treatment groups compared with the MPP+ group, whereas Bcl-2 expression was significantly increased in the SAL treatment groups. In summary, the overall results suggested that SAL have neuroprotective effects on the MPP+ -induced PC12 cell model by inhibiting inflammation, oxidative stress, and cell apoptosis. SAL may be a potential active product to protect against Parkinson's disease.

A new method of Common-view time transfer with transfer mode(TCV for abbreviation) via GEO telecommunication satellite is put forward, with which we can transfer the standard time kept in a time keeping laboratory, such as UTC (NTSC), to many users in the local area covered by the GEO satellite's signal. The time keeping laboratory is equipped with transmitting device and receiving device, and their external reference is from the main clock of the lab. The pseudo-code ranging signal is generated by the transmitting device in the lab, and is transmitted to the GEO satellite via a paraboloidal antenna, and then is broadcasted to the earth by the satellite. The pseudo-range from transmitter to GEO satellite and to the receiving device is measured in the lab. And at the same time the pseudo-range from transmitter to GEO satellite and to the user time receiver is also measured. By processing the pseudo-range measured by the user time receiver and that measured in the lab with paraboloidal antenna in common-view method, we can get the time difference between the user receiver clock and the main clock in the lab, carrying out the common-view time transfer with transfer mode (TCV). The precise coordinates of paraboloidal antenna in NTSC and the user time receiver, as well as precise orbit of the GEO satellite should be known in advance in this method. Chinese national standard time, UTC (NTSC) is kept in National Time Service Center (NTSC), Chinese Academy of Science. Based on the device of Two-Way Satellite Time and Frequency Transfer with C-band (TW(C) for abbreviation) in NTSC and Xinjiang Astronomical Observatory (XAO), we did TCV experiment. Both the transmitting and receiving units of the TW(C) device in NTSC are used, and only the receiving unit of the TW(C) device in XAO is used as a user time receiver. The main clock of UTC (NTSC) is a HP5071A Cs atomic clock, and an OSA5585 PRS Cs atomic clock is equipped in XAO. SATRE MODEM made by Timetech Company in Germany is used in our TW(C) devices and the code rate is 20MChips. The GEO satellite used in the experiment is Sinosat-1 telecommunication satellite (110.5°E). For the data processing in TCV method, the precise coordinates of the transmitting station and the receiving station are known in advance, the satellite orbit is provided by the Chinese Area Positioning System (CAPS) of Chinese Academy of Sciences, orbit precision is on the level of meter. And the system errors including Sagnac effect, ionosphere delay, troposphere delay etc, are taken out during the data processing, but the device delay is not deducted. We compare the results of TCV and TW(C), and it shows that ignoring the device delay (almost constant), the RMS of the difference between TCV and TW(C) is about 1ns for five consecutive days, and such result is very better than that in GPS Common-view time transfer with code.