Traction power systems for electrified railways:evolution,state of the art,and future trends

Traction power systems(TPSs)play a vital role in the operation of electrified railways.The transformation of conventional railway TPSs to novel structures is not only a trend to promote the development of electrified railways toward high-efficiency and resilience but also an inevitable requirement to achieve carbon neutrality target.On the basis of sorting out the power supply structures of conventional AC and DC modes,this paper first reviews the characteristics of the existing TPSs,such as weak power supply flexibility and low-energy efficiency.Furthermore,the power supply structures of various TPSs for future electrified railways are described in detail,which satisfy longer distance,low-carbon,high-efficiency,high-reliability and high-quality power supply requirements.Meanwhile,the application prospects of different traction modes are discussed from both technical and economic aspects.Eventually,this paper introduces the research progress of mixed-system electrified railways and traction power supply technologies without catenary system,speculates on the future development trends and challenges of TPSs and predicts that TPSs will be based on the continuous power supply mode,employing power electronic equipment and intelligent information technology to construct a railway comprehensive energy system with renewable energy.

Dip2a regulates stress susceptibility in the basolateral amygdala

Dysregulation of neurotransmitter metabolism in the central nervous system contributes to mood disorders such as depression, anxiety, and post–traumatic stress disorder. Monoamines and amino acids are important types of neurotransmitters. Our previous results have shown that disco-interacting protein 2 homolog A(Dip2a) knockout mice exhibit brain development disorders and abnormal amino acid metabolism in serum. This suggests that DIP2A is involved in the metabolism of amino acid–associated neurotransmitters. Therefore, we performed targeted neurotransmitter metabolomics analysis and found that Dip2a deficiency caused abnormal metabolism of tryptophan and thyroxine in the basolateral amygdala and medial prefrontal cortex. In addition, acute restraint stress induced a decrease in 5-hydroxytryptamine in the basolateral amygdala. Additionally, Dip2a was abundantly expressed in excitatory neurons of the basolateral amygdala, and deletion of Dip2a in these neurons resulted in hopelessness-like behavior in the tail suspension test. Altogether, these findings demonstrate that DIP2A in the basolateral amygdala may be involved in the regulation of stress susceptibility. This provides critical evidence implicating a role of DIP2A in affective disorders.

Review of the Analysis and Suppression for High-frequency Oscillations of the Grid-connected Wind Power Generation System

High-frequency oscillation(HFO)of gridconnected wind power generation systems(WPGS)is one of the most critical issues in recent years that threaten the safe access of WPGS to the grid.Ensuring the WPGS can damp HFO is becoming more and more vital for the development of wind power.The HFO phenomenon of wind turbines under different scenarios usually has different mechanisms.Hence,engineers need to acquire the working mechanisms of the different HFO damping technologies and select the appropriate one to ensure the effective implementation of oscillation damping in practical engineering.This paper introduces the general assumptions of WPGS when analyzing HFO,systematically summarizes the reasons for the occurrence of HFO in different scenarios,deeply analyses the key points and difficulties of HFO damping under different scenarios,and then compares the technical performances of various types of HFO suppression methods to provide adequate references for engineers in the application of technology.Finally,this paper discusses possible future research difficulties in the problem of HFO,as well as the possible future trends in the demand for HFO damping.

Commercial indium-tin oxide glass:A catalyst electrode for efficient N_(2)reduction at ambient conditions

The typical Haber technical process for industrial NH_(3)production involves plenty of energy-consumption and large quantities of greenhouse gas emission.In contrast,electrochemical N_(2)reduction proffers environment-friendly and energy-efficient avenues to synthesize NH_(3)at mild conditions but demands efficient electrocatalysts for the N_(2)reduction reaction(NRR).Herein we report for the first time that commercial indium-tin oxide glass(ITO/G)can be used as a catalyst electrode toward artificial N_(2)fixation,as it demonstrates excellent selectivity at mild conditions.Such ITO/G delivers excellent NRR performance with a NH_(3)yield of 1.06×10^(-10) mol s^(-1) cm^(-2) and a faradaic efficiency of 6.17%at-0.40 V versus the reversible hydrogen electrode(RHE)in 0.5 M LiClO4.Furthermore,the ITO/G also possesses good electrochemical stability and durability.Finally,the possible reaction mechanism for the NRR on the ITO catalysts was explored using first-principles calculations.

The efficacy of NP11-4-derived immunotoxin scFv-artesunate in reducing hepatic fibrosis inducedby Schistosoma japonicum in mice

Schistosomiasis is one of the most prevalent parasitic diseases in China, and hepatic fibrosis caused by schistosome infection is the principal cause of death. The aim of this study was to evaluate the efficacy of NPll-4- derived immunotoxin scFv-artesunate on Schistosoma japonicum-induced hepatic fibrosis. A single-chain variable fragment （scFv） was generated from the murine anti-Schistosoma japonicum （S. japanicum） monoclonal antibody NP11-4. The scFv was expressed as a soluble protein and purified by Ni-affinity chromatography. After conjuga- tion with artesunate, the binding ability with soluble egg antigens （SEA） was determined by an enzyme-linked immunosorbent assay （ELISA）. The biological activity of purified scFv, scFv-artesunate （immunotoxin）, and artesunate was detected in vivo. Image-Pro Plus software was used to analyze the size of egg granuloma and the extent of liver fibrosis. The recombinant scFv expession vector was constructed and expressed successfully. After purification by a His-trap Ni-affinity column, the scFv yield was approximately 0.8 mg/L of culture medium. ELISA results showed that chemical conjugation did not affect the binding activity of the immunotoxin. Our animal experiments indicated that the immunotoxin could significantly reduce the size of egg granuloma in the liver and inhibit hepatic fibrosis. The immunotoxin could be used as a promising candidate in the targeted therapy of S. .japonicum-induced hepatic fibrosis.

Measurable surface d charge of Pd as a descriptor for the selective hydrogenation activity of quinoline

Au Pd nanoalloys with tunable Pd concentrations have been synthesized and used as model catalysts. They have been directly imaged by high-angle annular dark-field scanning transmission electron microscopy and investigated by thorough analyses of their extended X-ray absorption fine structure, X-ray absorption near-edge structure, X-ray diffraction and X-ray photoelectron spectroscopy measurements. The bimetallic nanoparticles are embedded in a carbonaceous matrix and have almost an identical structure at the atomic level and the same electronic properties as Au Pd bulk alloys with the same compositions. The d-electron increase at surface Pd sites is determined by the Pd concentration of the alloy. Similarly, their activation entropy and catalytic activity for the hydrogenation of quinoline is related to the Pd concentration, with Au50 Pd50 the most active of the alloys investigated. An almost 11 times higher activity was achieved compared to a pure Pd catalyst. The experimentally measurable surface d charge at the Pd sites in the Au Pd was found to linearly correlate with the activation entropy and catalytic activity for the hydrogenation of quinoline. The alloy structure is stable, showing negligible metal segregation, dissolution-redeposition and aggregation during the hydrogenation process which involves strong adsorption.

Valproic acid protects neurons and promotes neuronal regeneration after brachial plexus avulsion

Valproic acid has been shown to exert neuroprotective effects and promote neurite outgrowth in several peripheral nerve injury models. However, whether valproic acid can exert its beneficial effect on neurons after brachial plexus avulsion injury is currently unknown. In this study, brachial plexus root avulsion models, established in Wistar rats, were administered daily with valproic acid dis-solved in drinking water （300 mg/kg） or normal water. On days 1, 2, 3, 7, 14 and 28 after avulsion injury, tissues of the C 5-T 1 spinal cord segments of the avulsion injured side were harvested to in-vestigate the expression of Bcl-2, c-Jun and growth associated protein 43 by real-time PCR and western blot assay. Results showed that valproic acid significantly increased the expression of Bcl-2 and growth associated protein 43, and reduced the c-Jun expression after brachial plexus avulsion. Our findings indicate that valproic acid can protect neurons in the spinal cord and enhance neuronal regeneration fol owing brachial plexus root avulsion.

金@介孔碳核壳和空腔结构纳米材料制备及其催化氧化性能

采用表面活性剂自组装技术合成了金@介孔碳核壳纳米球及蛋黄-蛋壳空腔纳米催化材料.高温碳化后,尺寸为15 nm的Au核被限制在碳壳层或空腔内;其壳层或空腔碳层的平均厚度分别约为38和10 nm.核壳和空腔材料都拥有开放的介孔结构(孔径为2.0~2.8 nm)、高的比表面积(>640 m^(2)g^(–1))和大的孔体积(>0.55 cm^(3)g^(–1)).高温碳化过程中,C原子沉积导致Au的d电荷密度增加.在苯甲醇氧化为苯甲酸反应中,d电荷密度增加的金@介孔碳核壳纳米球具有优异的活性,转化频率高达5468 h^(–1).同时,催化剂具有良好的稳定性,循环使用6次后,未见明显Au的流失和活性降低.

FeOOH quantum dots decorated graphene sheet:An efficient electrocatalyst for ambient N2 reduction

Electrochemical N2 reduction offers a promising alternative to the Haber-Bosch process for sustainable NH3 synthesis at ambient conditions,but it needs efficient catalysts for the N2 reduction reaction(NRR).Here,we report that FeOOH quantum dots decorated graphene sheet acts as a superior catalyst toward enhanced electrocatalytic N2 reduction to NH3 under ambient conditions.In 0.1 M LiClO4,this hybrid attains a large NH3 yield rate and a high Faradaic efficiency of 27.3µg·h^−1·mg−1cat.and 14.6%at−0.4 V vs.reversible hydrogen electrode,respectively,rivalling the current efficiency of all Fe-based NRR electrocatalysts in aqueous media.It also shows strong durability during the electrolytic process.

Heat-shock protein 90 in Candida albicans

Researches on Candidal heat-shock protein 90 (HSP90) in recent years are summarized. Candida albicans is a commensal pathogen in human and animals. in immunocompromised individuals it behaves as an opportunist pathogen, giving rise to superficial or systemic infections. Systemic candidosis is a common cause of death among immunocompromised and debilitated patients, in which the mortality is as high as 70%. HSP90 is now recognized as an immunodominant antigen in C. albicans and plays a key role in systemic candidosis as a molecular chaperone. The 47-ku peptide is the breakdown product of HSP90. Patients who has recovered from systemic candidosis produce high titre of antibodies to 47-ku antigen, whereas the fatal cases have little antibody or falling titre? The three commonest epitopes of candidal HSP90 have been mapped, epitopes C, B and H. Epitopes C and H are immunogenic. The antibody probes of both epitopes may be developed into a new serological test agents for systemic candidosis due to rather