Anecdotal reports have suggested that hypokalemia is an independent predictor of mortality in patients with acute paraquat poisoning. However, the clinical significance of hypokalemia has not been systematically investigated in the early stage of paraquat poisoning. This study aimed to evaluate whether initial hypokalemia is a good predictor of mortality in patients with acute paraquat poisoning within 4 h. We retrospectively analyzed patients who were admitted to the emergency department after paraquat poisoning between September 2012 and January 2015. Demographic, clinical, and laboratory data were recorded, and the prognostic significance of hypokalemia was analyzed. A total of 120 patients were included. The 60-day mortality was 71.7 %. Serum potassium concentrations were significantly lower in non-survivors (3.1 ± 0.5 mmol/L) than in survivors (3.8 ± 0.3 mmol/L, P < 0.001). Independent predictors of death were amount of paraquat ingested (hazard ratio 1.005; 95 % confidence interval 1.002-1.007), serum potassium (0.498, 0.277-0.897), bicarbonate (0.934, 0.876-0.995), and white blood cell count (1.032, 1.001-1.065). For receiver operating characteristic curve analysis, serum potassium had an area under the curve of 0.852 (95 % confidence interval 0.784-0.920, P < 0.001), and the best cutoff value was 3.5 mmol/L (sensitivity, 88.2 %; specificity, 75.6 % in predicting survivors). Kaplan-Meier analysis showed that decreased serum potassium concentrations were associated with an increase in 60-day mortality (P < 0.001). Hypokalemia may be a reliable predictor in evaluating prognosis in paraquat poisoning within 4 h. The mechanism is not clear, and further studies verifying the precise mechanism of hypokalemia are required.

We demonstrate and analyze the phase noise of optical carrier­assisted (OCA) single­sideband system with Kramers­Kronig receiver. The results show that the tardy variation phase noise induced by Kramers­Kronig receiver is periodically linear related to the guard band and baud rate.

A passive microfluidically tunable power divider (PD) with a wide-frequency-agile range based on substrate integrated waveguide (SIW) has been presented. The proposed structure consists of two SIW resonators loaded on the same complementary split-ring resonator and five identical filling-water tubes placed on the top plane. By injecting water into five tubes, the effective permittivity of the substrate can be controlled, and thus the operating frequency of the PD can be precisely tuned. For demonstration, the proposed PD is designed and fabricated. The measured and simulated results are given, showing good agreement.

This paper investigates the noise sources in a single-ended class D amplifier (SECDA) and suggests corresponding ways to lower the noise. The total output noise could be expressed as a function of the gain and noises from different sources. According to the function, the bias voltage (V B / is a primary noise source, especially for a SECDA with a large gain. A low noise SECDA is obtained by integrating a filter into the SECDA to lower the noise of the V B . The filter utilizes an active resister and an 80 pF capacitance to get a 3 Hz pole. A noise test and fast Fourier transform analysis show that the noise performance of this SECDA is the same as that of a SECDA with an external filter.