Facile Synthesis of MnO2 Nanoflowers/N-Doped Reduced Graphene Oxide Composite and Its Application for Simultaneous Determination of Dopamine and Uric Acid

This study reports facile synthesis of MnO2 nanoflowers/N-doped reduced graphene oxide (MnO2NFs/NrGO) composite and its application on the simultaneous determination of dopamine (DA) and uric acid (UA). The microstructures, morphologies, and electrochemical performances of MnO2NFs/NrGO were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS), respectively. The electrochemical experiments showed that the MnO2NFs/NrGO composites have the largest effective electroactive area and lowest charge transfer resistance. MnO2NFs/NrGO nanocomposites displayed superior catalytic capacity toward the electro-oxidation of DA and UA due to the synergistic effect from MnO2NFs and NrGO. The anodic peak currents of DA and UA increase linearly with their concentrations varying from 0.2 μM to 6.0 μM. However, the anodic peak currents of DA and UA are highly correlated to the Napierian logarithm of their concentrations ranging from 6.0 μM to 100 μM. The detection limits are 0.036 μM and 0.029 μM for DA and UA, respectively. Furthermore, the DA and UA levels of human serum samples were accurately detected by the proposed sensor. Combining with prominent advantages such as facile preparation, good sensitivity, and high selectivity, the proposed MnO2NFs/NrGO nanocomposites have become the most promising candidates for the simultaneous determination of DA and UA from various actual samples

Morphology–Dependent Electrochemical Sensing Properties of Iron Oxide–Graphene Oxide Nanohybrids for Dopamine and Uric Acid

Various morphologies of iron oxide nanoparticles (Fe2O3 NPs), including cubic, thorhombic and discal shapes were synthesized by a facile meta-ion mediated hydrothermal route. To further improve the electrochemical sensing properties, discal Fe2O3 NPs with the highest electrocatalytic activity were coupled with graphene oxide (GO) nanosheets. The surface morphology, microstructures and electrochemical properties of the obtained Fe2O3 NPs and Fe2O3/GO nanohybrids were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. As expected, the electrochemical performances were found to be highly related to morphology. The discal Fe2O3 NPs coupled with GO showed remarkable electrocatalytic activity toward the oxidation of dopamine (DA) and uric acid (UA), due to their excellent synergistic effect. The electrochemical responses of both DA and UA were linear to their concentrations in the ranges of 0.02–10 μM and 10–100 μM, with very low limits of detection (LOD) of 3.2 nM and 2.5 nM for DA and UA, respectively. Moreover, the d-Fe2O3/GO nanohybrids showed good selectivity and reproducibility. The proposed d-Fe2O3/GO/GCE realized the simultaneous detection of DA and UA in human serum and urine samples with satisfactory recoveries

Dynamic improvement of inductive power transfer systems with maximum energy efficiency tracking using model predictive control : analysis and experimental verification

For inductive power transfer (IPT) systems, loads and system input voltages are subject to change, which affects system efficiency and stability. This article presents a perturbation and observation (P&O) method for maximum energy efficiency tracking (MEET) with a model predictive control (MPC) scheme for improving the dynamic performance of series-series compensated IPT systems. In the IPT system, the inverter at the primary side incorporates the P&O method and phase shift modulation (PSM) to minimize system input power. Meanwhile, the rectifier at the secondary side is controlled by MPC control based PSM to improve the dynamic response of the output voltage. Simulated and experimental results show that, compared to the PI controller, the MPC controller, based on a simple but accurate mathematical model, has a better dynamic response to load and input voltage variations. With the MPC controller, the settling time of the output voltage is reduced by 85.7%, which indicates a particularly stable power supply to the load. Furthermore, MEET adopting the P&O method in the IPT system can promote the system efficiency by 1.85% on average when the output voltage is regulated by the MPC controller. © 1986-2012 IEEE

Dynamic Improvement of Inductive Power Transfer Systems With Maximum Energy Efficiency Tracking Using Model Predictive Control: Analysis and Experimental Verification

For inductive power transfer (IPT) systems, loads and system input voltages are subject to change, which affects system efficiency and stability. This article presents a perturbation and observation (P&O) method for maximum energy efficiency tracking (MEET) with a model predictive control (MPC) scheme for improving the dynamic performance of series-series compensated IPT systems. In the IPT system, the inverter at the primary side incorporates the P&O method and phase shift modulation (PSM) to minimize system input power. Meanwhile, the rectifier at the secondary side is controlled by MPC control based PSM to improve the dynamic response of the output voltage. Simulated and experimental results show that, compared to the PI controller, the MPC controller, based on a simple but accurate mathematical model, has a better dynamic response to load and input voltage variations. With the MPC controller, the settling time of the output voltage is reduced by 85.7%, which indicates a particularly stable power supply to the load. Furthermore, MEET adopting the P&O method in the IPT system can promote the system efficiency by 1.85% on average when the output voltage is regulated by the MPC controller. © 1986-2012 IEEE

Glucagon-like peptide-1 receptor agonists rescued diabetic vascular endothelial damage through suppression of aberrant STING signaling

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) protect against diabetic cardiovascular diseases and nephropathy. However, their activity in diabetic retinopathy (DR) remains unclear. Our retrospective cohort study involving 1626 T2DM patients revealed superior efficacy of GLP-1 RAs in controlling DR compared to other glucose-lowering medications, suggesting their advantage in DR treatment. By single-cell RNA-sequencing analysis and immunostaining, we observed a high expression of GLP-1R in retinal endothelial cells, which was down-regulated under diabetic conditions. Treatment of GLP-1 RAs significantly restored the receptor expression, resulting in an improvement in retinal degeneration, vascular tortuosity, avascular vessels, and vascular integrity in diabetic mice. GO and GSEA analyses further implicated enhanced mitochondrial gene translation and mitochondrial functions by GLP-1 RAs. Additionally, the treatment attenuated STING signaling activation in retinal endothelial cells, which is typically activated by leaked mitochondrial DNA. Expression of STING mRNA was positively correlated to the levels of angiogenic and inflammatory factors in the endothelial cells of human fibrovascular membranes. Further investigation revealed that the cAMP-responsive element binding protein played a role in the GLP-1R signaling pathway on suppression of STING signaling. This study demonstrates a novel role of GLP-1 RAs in the protection of diabetic retinal vasculature by inhibiting STING-elicited inflammatory signals