The oxygen evolution reaction has an important role in many alternative-energy schemes because it supplies the protons and electrons required for converting renewable electricity into chemical fuels
.... Electrocatalysts accelerate the reaction by facilitating the required electron transfer
, as well as the formation and rupture of chemical bonds
. This involvement in fundamentally different processes results in complex electrochemical kinetics that can be challenging to understand and control, and that typically depends exponentially on overpotential
. Such behaviour emerges when the applied bias drives the reaction in line with the phenomenological Butler-Volmer theory, which focuses on electron transfer
, enabling the use of Tafel analysis to gain mechanistic insight under quasi-equilibrium
or steady-state assumptions
. However, the charging of catalyst surfaces under bias also affects bond formation and rupture
, the effect of which on the electrocatalytic rate is not accounted for by the phenomenological Tafel analysis
and is often unknown. Here we report pulse voltammetry and operando X-ray absorption spectroscopy measurements on iridium oxide to show that the applied bias does not act directly on the reaction coordinate, but affects the electrocatalytically generated current through charge accumulation in the catalyst. We find that the activation free energy decreases linearly with the amount of oxidative charge stored, and show that this relationship underlies electrocatalytic performance and can be evaluated using measurement and computation. We anticipate that these findings and our methodology will help to better understand other electrocatalytic materials and design systems with improved performance.
The flower buds of Cleistocalyx operculatus are used as an important ingredient in herbal tea and herbal products in several tropical countries. However, their protective effects and underlying ...mechanisms on lipopolysaccharide (LPS)-induced endotoxic shock remain unclear. The aim of this study was to investigate the anti-inflammatory effects of ethanol extract of C. operculatus flower buds (ECO) and its major constituent 2′,4′-dihydroxy-6′-methoxy-3′,5′-dimethylchalcone (DMC) in macrophages and in an experimental LPS-induced sepsis mouse model. ECO inhibited the LPS-induced production and expression of pro-inflammatory mediators in macrophages. In an endotoxic shock mouse model, the oral administration of ECO rescued LPS-induced mortality, and attenuated LPS-induced increases in the serum levels of pro-inflammatory mediators, and damage of the lung and liver tissues. ECO increased the nuclear translocation of the nuclear factor erythroid 2-related factor 2 (Nrf2), as well as the expression of Nrf2 target genes, including heme oxygenase-1 (HO-1), in macrophages. Similar to the effects of ECO, DMC also inhibited the LPS-induced inflammatory response in macrophages and endotoxic shock in mice, and activated the Nrf2/HO-1 pathway. In conclusion, our findings suggested that ECO and its major constituent, DMC, attenuated LPS-induced endotoxic shock by activating the Nrf2/HO-1 pathway.
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•The flower buds of Cleistocalyx operculatus are used as an ingredient in herbal products in several tropical countries.•The anti-inflammatory effects of C. operculatus flower buds (ECO) and its major constituent DMC are demonstrated.•ECO and DMC attenuates lipopolysaccharide-induced inflammatory response in macrophages and endotoxic shock in mice.•The Nrf2/HO-1 pathway is attributable to the anti-inflammatory properties of ECO and DMC in macrophages.•The mechanism explains the anti-inflammatory effects of ECO and DMC.
The multitargeted protein kinase inhibitor midostaurin is approved for the treatment of both newly diagnosed FLT3-mutated acute myeloid leukemia (AML) and KIT-driven advanced systemic mastocytosis. ...AML is a heterogeneous malignancy, and investigational drugs targeting FLT3 have shown disparate effects in patients with FLT3-mutated AML, probably as a result of their inhibiting different targets and pathways at the administered doses. However, the efficacy and side effects of drugs do not just reflect the biochemical and pharmacodynamic properties of the parent compound but are often comprised of complex cooperative effects between the properties of the parent and active metabolites. Following chronic dosing, two midostaurin metabolites attain steady-state plasma trough levels greater than that of the parent drug. In this study, we characterized these metabolites and determined their profiles as kinase inhibitors using radiometric transphosphorylation assays. Like midostaurin, the metabolites potently inhibit mutant forms of FLT3 and KIT and several additional kinases that either are directly involved in the deregulated signaling pathways or have been implicated as playing a role in AML via stromal support, such as IGF1R, LYN, PDPK1, RET, SYK, TRKA, and VEGFR2. Consequently, a complex interplay between the kinase activities of midostaurin and its metabolites is likely to contribute to the efficacy of midostaurin in AML and helps to engender the distinctive effects of the drug compared to those of other FLT3 inhibitors in this malignancy.
The movement of cooperative robots in a densely cluttered environment may be impossible if the formation type is invariant. Hence, we investigate a novel method of switching time-invariant formation ...control for a group of heterogeneous autonomous vehicles, which may include Unmanned Ground Vehicles (UGV) and Unmanned Aerial Vehicles (UAV). We have extended a Negative Imaginary (NI) consensus control approach to switch the formation shape of the robots whilst only using the relative distances between agents, in combination with those between agents and obstacles. All agents can automatically create a new safe formation to overcome obstacles, then restore the prototype formation once the obstacles are cleared. We address the oscillation and local minima problems, generated by existing algorithms, using a newly developed circle fitting approach. We also highlight the advantages of our proposed algorithms over the kinematic controller and the conventional Artificial Potential Field (APF) controller from both theoretical and experimental standpoints. Simulation and experimental results are then analyzed to validate the feasibility of our proposed approach.
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•A novel Leader–Follower NI switching formation control law based on the relative-position consensus for networked robots moving in formation.•Three comprehensive and effective obstacle avoidance strategies-based formation switches for a heterogeneous multi-robot system, considering even the various sizes of robots.•The stability of complete formation-avoidance control architecture is proved.•The homogeneity, synchronization, and simplification of the formation control, along with the obstacle avoidance is guaranteed based on a homogeneous NI framework.•All performances of formation control and avoid obstacles are distributed.•The main strength of our proposed method over others are verified through tests.
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