Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and represents a potentially fatal disease of great global public health importance. As ...of March 26, 2020, the outbreak of COVID-19 has resulted in 462,801 confirmed cases and 20,839 deaths globally, which is more than those caused by SARS and Middle East respiratory syndrome (MERS) in 2003 and 2013, respectively. The epidemic has posed considerable challenges worldwide. Under a strict mechanism of massive prevention and control, China has seen a rapid decrease in new cases of coronavirus; however, the global situation remains serious. Additionally, the origin of COVID-19 has not been determined and no specific antiviral treatment or vaccine is currently available. Based on the published data, this review systematically discusses the etiology, epidemiology, clinical characteristics, and current intervention measures related to COVID-19 in the hope that it may provide a reference for future studies and aid in the prevention and control of the COVID-19 epidemic.
Manganese (Mn) is generally regarded as not being sufficiently active for the oxygen reduction reaction (ORR) compared to other transition metals such as Fe and Co. However, in biology, ...manganese‐containing enzymes can catalyze oxygen‐evolving reactions efficiently with a relative low onset potential. Here, atomically dispersed O and N atoms coordinated Mn active sites are incorporated within graphene frameworks to emulate both the structure and function of Mn cofactors in heme–copper oxidases superfamily. Unlike previous single‐metal catalysts with general M‐N‐C structures, here, it is proved that a coordinated O atom can also play a significant role in tuning the intrinsic catalytic activities of transition metals. The biomimetic electrocatalyst exhibits superior performance for the ORR and zinc–air batteries under alkaline conditions, which is even better than that of commercial Pt/C. The excellent performance can be ascribed to the abundant atomically dispersed Mn cofactors in the graphene frameworks, confirmed by various characterization methods. Theoretical calculations reveal that the intrinsic catalytic activity of metal Mn can be significantly improved via changing local geometry of nearest coordinated O and N atoms. Especially, graphene frameworks containing the Mn‐N3O1 cofactor demonstrate the fastest ORR kinetics due to the tuning of the d electronic states to a reasonable state.
Atomically dispersed O‐ and N‐atoms‐coordinated Mn active sites (especially Mn‐N3O1) are incorporated within graphene frameworks to emulate both the structure and function of Mn cofactors in the heme–copper oxidase superfamily, which exhibit excellent activity for the oxygen reduction reaction (onset potential 0.94, half‐wave potential 0.86 V) and zinc–air battery performance, superior to even that of commercial 20 wt% Pt/C.
Electrochemical water splitting is considered as the most promising technology for hydrogen production. Considering overall water splitting for practical applications, catalysis of the oxygen ...evolution reaction (OER) and hydrogen evolution reaction (HER) should be performed in the same electrolyte, especially in alkaline solutions. However, designing and searching for highly active and inexpensive electrocatalysts for both OER and HER in basic media remain significant challenges. Herein, we report a facile and universal strategy for synthesizing nonprecious transition metals, binary alloys, and ternary alloys encapsulated in graphene layers by direct annealing of metal–organic frameworks. Density functional theory calculations prove that with an increase in the degree of freedom of alloys or a change in the metal proportions in FeCoNi ternary alloys, the electronic structures of materials can also be tuned intentionally by changing the number of transferred electrons between alloys and graphene. The optimal material alloys FeCo and FeCoNi exhibited remarkable catalytic performance for HER and OER in 1.0 M KOH, reaching a current density of 10 mA cm–2 at low overpotentials of 149 mV for HER and 288 mV for OER. In addition, as an overall alkaline water electrolysis, they were comparable to that of the Pt/RuO2 couple, along with long cycling stability.
The vibration control problem was investigated in this study in the presence of unknown loss of actuator effectiveness fault and loss of sensor effectiveness fault in a flexible aircraft wing system. ...A series of partial differential equations was used as the mathematical model of the wing with unknown boundary disturbances. An adaptive fault-tolerant boundary controller was designed accordingly. All signals of the closed-loop control system are globally uniformly bounded and the controlled state asymptotically converges. Numerical simulations were conducted to validate the proposed control scheme.
•Most of the aldehyde groups mainly located on the edge of the SG particles.•Oxidization might be not only carried out on surface, but also within granules of SG.•The surface hydroxyl numbers of CLSG ...decreased with increasing cross-linking degree.•Cross-linking degree was better calculated by determining the surface hydroxyl numbers.•l-Asparagine was adsorpted by DCLSG through forming sesbania gum based Schiff base.
This paper studied the modification mechanism of Sesbania gum (SG) by means of the variations in the numbers of surface hydroxyl groups on the granules, Schiff’s agent coloration of aldehyde groups, Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD), energy dispersive spectrum (EDS), etc., and also examined the preparation, property and adsorption of dialdehyde cross-linked sesbania gum (DCLSG). The results showed that the surface hydroxyl numbers of cross-linked sesbania gum (CLSG) decreased with increasing the cross-linking degree. The distribution of the aldehyde groups on the DCLSG particles was nonuniform because most of aldehyde groups mainly located on the edge of particles. The cross-linking occurred only on the surface of SG particles. The oxidization occurred not only on the surface of SG particles, but also in the interior of particles. The cross-linking or oxidization changed the thermal properties, and reduced the swelling power, viscosity, alkali and acid resistance of SG.
Transient electromagnetic method (TEM) inversion is significantly nonlinear. To eliminate the multicollinearity problem faced by the extreme learning machine (ELM) algorithm for TEM inversion, an ...improved ELM algorithm (F-ELM) based on fractal dimension technology is proposed. By reducing the dimension of the hidden layer output matrix (H) based on fractal dimension theory without losing the main statistical information, the proposed algorithm can not only guarantee the full column rank of the newly produced hidden layer output matrix (H′) but also enhance the training speed of the overall process. To prove the effectiveness of the F-ELM algorithm, a synthetic example and a field example using TEM inversion are established in this study. The experimental results illustrate that compared with the ordinary ELM algorithm and its variants, the proposed algorithm greatly reduces the computing time, improves the inversion accuracy and stability of the algorithm. Furthermore, it is also proven that the F-ELM algorithm is a very effective technique for TEM inversion.
•The F-ELM is applied for TEM inversion.•The F-ELM is proposed to eliminate the multicollinearity problem.•The fractal dimension technology greatly enhances the training speed of the ELM algorithm without losing the main statistical information.
Stroke is a leading cause of death and disability in humans. The excessive production of reactive oxygen species (ROS) is an important contributor to oxidative stress and secondary brain damage after ...stroke. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, an enzyme complex consisting of membrane subunits and cytoplasmic subunits, regulates neuronal maturation and cerebrovascular homeostasis. However, NADPH oxidase overproduction contributes to neurotoxicity and cerebrovascular disease. NADPH oxidase has been implicated as the principal source of ROS in the brain, and numerous studies have shown that the knockout of NADPH exerts a protective effect in the model of ischemic stroke. In this review, we summarize the mechanism of activation of the NADPH oxidase family members, the pathophysiological effects of NADPH oxidase isoforms in ischemic stroke, and the studies of NADPH oxidase inhibitors to explore potential clinical applications.
Abstract
As a large agricultural country, China should pay more attention to the carbon emission in agriculture in the context of achieving the goal of ‘peak carbon and carbon neutrality’. This paper ...measures the agricultural carbon emissions and analyzes its temporal characteristics in Jiangxi from 2000 to 2019, examines the influencing factors using Kaya’s constant equation. The study shows that: (1) from 2000 to 2019, Jiangxi’s agricultural carbon emissions show a general upward trend, but the growth rate tends to slow down gradually; (2) the factors of agricultural production efficiency, agricultural industrial structure and agricultural labor force have a negative driving effect on carbon emissions, while the factors of agricultural economic development and urbanization level have a positive driving effect on agricultural carbon emissions.
Hemorrhagic stroke is a life-threatening neurological disease characterized by high mortality and morbidity. Various pathophysiological responses are initiated after blood enters the interstitial ...space of the brain, compressing the brain tissue and thus causing cell death. Recently, three new programmed cell deaths (PCDs), necroptosis, pyroptosis, and ferroptosis, were also found to be important contributors in the pathophysiology of hemorrhagic stroke. Additionally, blood-brain barrier (BBB) dysfunction plays a crucial role in the pathophysiology of hemorrhagic stroke. The primary insult following BBB dysfunction may disrupt the tight junctions (TJs), transporters, transcytosis, and leukocyte adhesion molecule expression, which may lead to brain edema, ionic homeostasis disruption, altered signaling, and immune infiltration, consequently causing neuronal cell death. This review article summarizes recent advances in our knowledge of the mechanisms regarding these new PCDs and reviews their contributions in hemorrhagic stroke and potential crosstalk in BBB dysfunction. Numerous studies revealed that necroptosis, pyroptosis, and ferroptosis participate in cell death after subarachnoid hemorrhage (SAH) and intracerebral hemorrhage (ICH). Endothelial dysfunction caused by these three PCDs may be the critical factor during BBB damage. Also, several signaling pathways were involved in PCDs and BBB dysfunction. These new PCDs (necroptosis, pyroptosis, ferroptosis), as well as BBB dysfunction, each play a critical role after hemorrhagic stroke. A better understanding of the interrelationship among them might provide us with better therapeutic targets for the treatment of hemorrhagic stroke.
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