A current-turbidity monitoring system (CTMS) was deployed on the intertidal flat at Wanggang, northern Jiangsu during October 16-17, 2000, to measure the tidal current speeds and seawater turbidities at 5 levels above...A current-turbidity monitoring system (CTMS) was deployed on the intertidal flat at Wanggang, northern Jiangsu during October 16-17, 2000, to measure the tidal current speeds and seawater turbidities at 5 levels above the seabed. Based upon the logarithmic-profile equation, the boundary layer parameters, i.e., u, z0 and C60, were obtained for 247 tidal flow velocity profiles. Around 90% of the profiles were logarithmic according to the critical correlation coefficient. Internal consistency analysis shows that these parameters derived by different methods are consistent with each other. In addition, the height of the bedforms observed is close to the seabed roughness lengths calculated from the velocity profiles, indicating that the boundary layer parameters obtained can reveal the conditions at the sediment-water interface on the intertidal flats. Suspended sediment concentrations were obtained from the 5 CTMS turbidity meters using laboratory and in-situ calibrations. The results show that the in-situ calibrated SSCs have a much higher accuracy than the laboratory calibrated ones. Calculation of suspended sediment fluxes on the intertidal flats, with a magnitude of 104 kg/m per spring tidal cycle, indicates that suspended sediment moves towards the northwest, which is reversal to the transport pattern controlled by the southward Northern Jiangsu Coastal Current in the sub-tidal zone and adjacent shallow waters.展开更多
A Nortek acoustic Doppler current profiler (NDP) was installed on a moving vessel to survey the entrance to the Jinhae Bay on August 22~23, 2001. The current velocity and acoustic backscattering signal were collected ...A Nortek acoustic Doppler current profiler (NDP) was installed on a moving vessel to survey the entrance to the Jinhae Bay on August 22~23, 2001. The current velocity and acoustic backscattering signal were collected along two cross-sections; water samples were also collected during the measurement. The acoustic signals were normalized to compensate for the loss incurred by acoustic beam spreading in the seawater. The in situ calibration shows that a significant relationship is present between suspended sediment concentrations (SSC) and normalized acoustic signals. Two acoustic parameters have been determined to construct an acoustic-concentration model. Using this derived model, the SSC patterns along the surveyed cross-sections were obtained by the conversion of acoustic data. Using the current velocity and SSC data, the flux of suspended sediment was estimated. It indicates that the sediment transport into the bay through the entrance has an order of magnitude of 100 t per tidal cycle.展开更多
Neural stem cell (NSC) is the progenitor of the neural system with the character of self-renew and hav-ing the potential to differentiate into all the phenotypes in the central nervous system (CNS). NSC may serve as a...Neural stem cell (NSC) is the progenitor of the neural system with the character of self-renew and hav-ing the potential to differentiate into all the phenotypes in the central nervous system (CNS). NSC may serve as a source of cell transplantation for the treatment of neurodegenerative diseases to replace degenerative neurons. In this study, NSCs derived from E12.5 rat mesencephalon were main-tained and expanded using a serum-free defined medium containing basic fibroblast growth factor (bFGF) and epi-dermal growth factor (EGF). While proliferating, the cells were immunoreactive for nestin and remained multipotent to generate neurons, astrocytes, and oligodendrocytes. After 15 times passage the total number of the cell expanded about 2.4×104 fold. Compared with untreated cultures, ascorbic acid (AA) treatment led to more dopaminergic (DAergic) differentitiation as indicated by the expression of tyrosine hydroxylase (TH). With the concentration increasing, more TH+ neurons were obtained. 100 mmol/L AA could lead to a increase more than 20-fold, and a concentration of 10 靘ol/L could lead to nearly 5-fold increase in TH+ cells. However, the ratio of TH+ cells was not improved any longer with the AA increasing above the concentration of 100 靘ol/L. The results demonstrate that expanded NSCs can be induced to differentiate into dopamine neurons in vitro, which can pro-vide enough cell population for the cell transplantation, as a main intervention for the neurodegenerative diseases such as Parkinson抯 disease.展开更多
文摘A current-turbidity monitoring system (CTMS) was deployed on the intertidal flat at Wanggang, northern Jiangsu during October 16-17, 2000, to measure the tidal current speeds and seawater turbidities at 5 levels above the seabed. Based upon the logarithmic-profile equation, the boundary layer parameters, i.e., u, z0 and C60, were obtained for 247 tidal flow velocity profiles. Around 90% of the profiles were logarithmic according to the critical correlation coefficient. Internal consistency analysis shows that these parameters derived by different methods are consistent with each other. In addition, the height of the bedforms observed is close to the seabed roughness lengths calculated from the velocity profiles, indicating that the boundary layer parameters obtained can reveal the conditions at the sediment-water interface on the intertidal flats. Suspended sediment concentrations were obtained from the 5 CTMS turbidity meters using laboratory and in-situ calibrations. The results show that the in-situ calibrated SSCs have a much higher accuracy than the laboratory calibrated ones. Calculation of suspended sediment fluxes on the intertidal flats, with a magnitude of 104 kg/m per spring tidal cycle, indicates that suspended sediment moves towards the northwest, which is reversal to the transport pattern controlled by the southward Northern Jiangsu Coastal Current in the sub-tidal zone and adjacent shallow waters.
文摘A Nortek acoustic Doppler current profiler (NDP) was installed on a moving vessel to survey the entrance to the Jinhae Bay on August 22~23, 2001. The current velocity and acoustic backscattering signal were collected along two cross-sections; water samples were also collected during the measurement. The acoustic signals were normalized to compensate for the loss incurred by acoustic beam spreading in the seawater. The in situ calibration shows that a significant relationship is present between suspended sediment concentrations (SSC) and normalized acoustic signals. Two acoustic parameters have been determined to construct an acoustic-concentration model. Using this derived model, the SSC patterns along the surveyed cross-sections were obtained by the conversion of acoustic data. Using the current velocity and SSC data, the flux of suspended sediment was estimated. It indicates that the sediment transport into the bay through the entrance has an order of magnitude of 100 t per tidal cycle.
基金supported by the State“863"High-Tech Project(Grant Nos.2002AA205051 and 2001 AA216l5l)the National Key Project for Basic Research of China(Grant No.001CB509906)the Project of Beijing Science Community(Grant No.020220010190).
文摘Neural stem cell (NSC) is the progenitor of the neural system with the character of self-renew and hav-ing the potential to differentiate into all the phenotypes in the central nervous system (CNS). NSC may serve as a source of cell transplantation for the treatment of neurodegenerative diseases to replace degenerative neurons. In this study, NSCs derived from E12.5 rat mesencephalon were main-tained and expanded using a serum-free defined medium containing basic fibroblast growth factor (bFGF) and epi-dermal growth factor (EGF). While proliferating, the cells were immunoreactive for nestin and remained multipotent to generate neurons, astrocytes, and oligodendrocytes. After 15 times passage the total number of the cell expanded about 2.4×104 fold. Compared with untreated cultures, ascorbic acid (AA) treatment led to more dopaminergic (DAergic) differentitiation as indicated by the expression of tyrosine hydroxylase (TH). With the concentration increasing, more TH+ neurons were obtained. 100 mmol/L AA could lead to a increase more than 20-fold, and a concentration of 10 靘ol/L could lead to nearly 5-fold increase in TH+ cells. However, the ratio of TH+ cells was not improved any longer with the AA increasing above the concentration of 100 靘ol/L. The results demonstrate that expanded NSCs can be induced to differentiate into dopamine neurons in vitro, which can pro-vide enough cell population for the cell transplantation, as a main intervention for the neurodegenerative diseases such as Parkinson抯 disease.
