Considering the important functions of cellular Na(+) and K(+) together with their cooperative efforts on various biological processes, it is significant to simultaneously detect Na(+) and K(+) at a single-cell level. Here, we present a novel method to discriminate and quantify simultaneously Na(+) and K(+) in single cells using a new near-infrared fluorescent probe associated with microchip electrophoresis. The fluorescent probe selectively responds to both Na(+) and K(+). The microchip electrophoresis allows accurate single-cell manipulation and effective distinction of Na(+) and K(+). Based on the method, the concentration of Na(+) and K(+) in single normal and cancer cells was compared, and the variation of Na(+) and K(+) in single cancer cells during the early stage of apoptotic volume decrease was monitored, which would help us to better understand the critical roles of Na(+) and K(+) in malignant cells and apoptosis. This method has paved a new way for the research of the synergistic function of Na(+) and K(+) in the regulation of various biological processes at a single-cell level.

Various intracellular metal ions have closely related functional roles in the nervous system. An excess or deficiency of essential metal ions can contribute to neurodegenerative diseases. Thus, the detection of various metal ions in neurons is important for diagnosing and monitoring these diseases. In particular, single-cell analysis of multiple metal ions allows us to not only understand the cellular heterogeneity and differentiation but also determine the actual relationships among multiple metal ions in each individual cell. Aiming at the low efficient single-cell manipulation and interference of complex biological matrices within cells in the existing method for single-cell metal ion detection, in this manuscript, we present a convenient, sensitive, and reliable method to simultaneously identify and quantify multiple metal ions at the single-cell level using a microfluidic system. Using the combination of on-chip electrophoresis separation and multicolor fluorescence detection, we achieved the simultaneous analysis of Na, K, Ca, and Mg in single PC-12 cells and studied changes in these four metal ions in Aβ-treated PC-12 cells, which is a model of Alzheimer's disease (AD). The data showed that metal ions imbalances in neuron-like cells may be associated with AD induced by Aβ. This method paves the way for multiple metal ion detection in single neuron-like cells, and the results provide insights regarding synergistic function of multiple metal ions in regulation of neurological diseases at the single-cell level.

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Overlapping storage periods of the cascade reservoirs would lead to the unreasonable using of the water resources, and each reservoir in the cascade might not be filled, that would influence the comprehensive benefit of the cascade reservoirs. In this paper, the Runoff regulation model of the cascade reservoirs is established and verified, the flood regulating calculation of the Xiluodu-Xiangjiaba-Three Gorges cascade reservoirs is done, and based on the flood regulating calculation, the earliest dates of the starting impounding of the cascade reservoirs are as below: Xiluodu and Xiangjiaba reservoirs are both not earlier than Sep.11, and Three Gorges Reservoir is not earlier than Sep.1. Then by using the comparative analysis and based on an overall analysis of generating electricity and transport of the cascade reservoirs, the most reasonable impounding date are calculated as below: the Xiluodu reservoir starts impounding in Sep.1, the Xiangjiaba reservoir starts impounding in Oct.1, and the Three Gorges Reservoir starts impounding in Sep.1.

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