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Nobiletin (NOB) has attracted much attention owing to its outstanding bioactivities. This study aimed to investigate its anti-arrhythmic effect through electrophysiological and molecular docking studies. We assessed the anti-arrhythmic effects of NOB using aconitine-induced ventricular arrhythmia in a rat model and the electrophysiological effects of NOB on rat cardiomyocytes utilizing whole-cell patch-clamp techniques. Moreover, we investigated the binding characters of NOB with rNav1.5, rNav1.5/QQQ, and hNaV1.5 via docking analysis, comparing them with amiodarone and aconitine. NOB pretreatment delayed susceptibility to ventricular premature and ventricular tachycardia and decreased the incidence of fatal ventricular fibrillation. Whole-cell patch-clamp assays demonstrated that the peak current density of the voltage-gated Na+ channel current was reversibly reduced by NOB in a concentration-dependent manner. The steady-state activation and recovery curves were shifted in the positive direction along the voltage axis, and the steady-state inactivation curve was shifted in the negative direction along the voltage axis, as shown by gating kinetics. The molecular docking study showed NOB formed a π-π stacking interaction with rNav1.5 and rNav1.5/QQQ upon Phe-1762, which is the homolog to Phe-1760 in hNaV1.5 and plays an important role in antiarrhythmic action This study reveals that NOB may act as a class I sodium channel anti-arrhythmia agent. [ABSTRACT FROM AUTHOR]

Abstract: In a urea selective catalytic reduction (urea‐SCR) system for diesel engines, the atomization, evaporation, and mixing conditions of urea water solution (UWS) play a crucial role for NOX conversion and ammonia slip in the SCR process. In this paper, a series of novel mixing modules were proposed to improve UWS evaporation, mixing, and distribution for NOX reduction in the SCR system. Experimental investigations were conducted on the performances of the existing and developed mixing modules under various engine test conditions, including particle size test, NOX conversion efficiency, flow bench tests, etc. To determine ammonia slip, the urea and ammonia distribution patterns were constructed and the non‐uniformity index was then calculated. Compared with the baseline (without mixing module) and existing mixing module, the NOX conversion efficiency of the SCR system with a developed mixing module is improved by 37.7 and 14.1 % at maximum, respectively. Furthermore, ammonia slip and distribution are ameliorated significantly with low‐pressure drops simultaneously. Among the mixing modules, Concept 3 design exhibits superior performance under the engine test conditions. [ABSTRACT FROM AUTHOR]