In the mainstream of the Lancang River, eight cascade dams have been constructed. In order to find the effects of the cascade reservoirs on the transformation of nitrate (NO3-N) and ammonium (NH4-N) in pore water of sediments, a field survey was carried out both in the upper natural river reach (NRR) and cascade reservoirs reach (CRR) of the Lancang River from January 10 to 20, 2018. The results indicated that (1) in the NRR, NO3-N concentrations in sediment pore water were higher than those in the CRR, whereas the total nitrogen (TN) and NH4-N were significantly lower; the diffusion fluxes of NH4-N from sediment to overlying water varied from -0.180 to 0.049 mg center dot(m(2)center dot d)(-1), and the diffusion fluxes of NO3-N varied from 0.012 to 0.098 mg center dot(m(2)center dot d)(-1). (2) in the CRR, the NH4-N concentrations in sediment pore water were much higher than those in the overlying water, but the NO3-N concentrations in the overlying water were much higher; the diffusion fluxes of NH4-N from the sediments to the overlying water varied from 0.161 to 1.561 mg center dot(m(2)center dot d)(-1), but the NO3-N diffused downward from the overlying water to the sediments and the diffusion fluxes varied from -0.011 to -0.223 mg center dot(m(2)center dot d)(-1). It was concluded that the cascade reservoirs could increase the NH4-N concentration and inversely decrease the NO3-N concentration in the sediment pore water, which meant that the risk of the nitrogen release from the sediment in the cascade reservoirs was much higher than that in the natural river.

Construction of cascade reservoirs in Lancang River had a certain influence on the ecological water environment of the basin, dividing the water into natural reaches and reservoir reaches. To explore the impact of the cascade reservoirs on the ecological environment, the nutrient and the chlorophyll a distribution data were measured in the natural reaches, reservoir reaches, and tributaries in June 2017. The results showed that the TN ranged from 0.37 to 1.22 mg·L-1, with an average of 0.70 mg·L-1, and the TP ranged from 0.01 to 0.19 mg·L-1, with an average of 0.04 mg·L-1. One-way ANOVA analysis showed significant spatial differences in the TN, with the TN concentration following the order tributaries > reservior reaches > natural reaches. However, the TP concentration did not show a significant trend. The chlorophyll a concentration varied from 2.6 to 10.2 μg·L-1, with a mean of 5.8 μg·L-1. Pearson correlation analysis showed significant relationships between the chlorophyll a concentration and the TP, water temperature, and Zeu/Zmix. The relationship between chlorophyll a and Zeu/Zmix was particularly significant, which indicated the Zeu/Zmix caused by thermal stratification may be the key factor influencing the growth of phytoplankton.

Clinically the isovolumic contraction time (IVCT) can be measured by 3 echocardiographic methods of M-mode, pulse-wave Doppler (PWD), and tissue Doppler imaging (TDI). But IVCT can be clinically different by the 3 methods. This study is to investigate whether there is a potentially unidentified phase causing the discrepancies by analyzing electric mechanical delay time (EMD), IVCT, and pre-ejection period (PEP).A total of 30 healthy subjects were recruited for the study. EMD, IVCT, and PEP were obtained by the 3 methods, respectively. MCT (the interval from the onset of the QRS wave to the closure point of the mitral valve measured by TDI) and ICMC (the interval from the onset of IVC wave S1 to the closure point of the mitral valve measured by TDI) were both measured by color TDI.IVCTt (IVCT measured by TDI) was significantly longer than IVCTm or IVCTd (IVCT measured by M-mode or PWD) (both P < .0001), while EMDt (EMD measured by TDI) was significantly shorter than EMDm or EMDd (EMD measured by M-mode or PWD) (both P < .0001). But MCT was not significantly different from EMDm or EMDd (P > .05) and ICMC did not differ significantly from EMDm or EMDd minus EMDt or IVCTt minus IVCTm or IVCTd (P > .05), in other words, ICMC almost equaled to (EMDm or EMDd minus EMDt) or (IVCTt minus IVCTm or IVCTd).There may be an unidentified phase between the end of atrial contraction and the closure of mitral valve causing the discrepancies in IVCT, which is named as the pre-isovolumic contraction phase. It is a non-isovolumic phase and is included in the traditional isovolumic contraction phase.