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•A composite paper was prepared by combining aramid nanofibers, boron nitride nanotubes, and polyethyleneimine.•Elaborating interfacial hydrogen bonds design can optimize the ...mechanical properties of composite paper.•The composite paper has high thermal conductivity and unique dielectric performance.
Aramid paper is ubiquitous in advanced electronics and high-voltage equipment by virtue of their outstanding dielectric properties, mechanical reliability, and thermal stability. However, their limited thermal conductivity still fails to satisfy the stringent demands for heat dissipation in applications with high power and high energy density. Herein, we report a highly thermally conductive composite paper prepared by synergistically combining one-dimensional (1D) aramid nanofibers (ANFs), 1D edge-hydroxylated boron nitride nanotubes (BNNTs), and polyethyleneimine (PEI). The resultant composite paper exhibits high thermal conductivity (9.91 Wm−1K−1), low dielectric loss (<0.01), and ultrahigh electrical breakdown strength (∼334 kV/mm) with an exceptional heat resistance performance. Three-dimensional hydrogen bonding networks were constructed between the ANF framework, PEI, and BNNTs, endowing the composite paper with a superior tensile strength (up to 317 MPa) and Young’s modulus (∼7.7 GPa), which are significantly higher than those of the commercial Nomex T410 paper. This research provides important insights into the design and fabrication of multifunctional insulating paper for application in modern integrated electronic and power systems.
In this paper, the transition mechanisms between symmetric and asymmetric discharges in atmospheric helium dielectric barrier discharges (DBDs) are investigated via a one-dimensional fluid model. By ...gradually increasing the gap width, a complete evolution trajectory of the discharge states (i.e. from symmetric single period discharge (SP1) to asymmetric single-period (AP1) discharge, finally returns back to SP1 discharge) is observed. Unlike the previous reports which emphasize the dominant role of residual positive column, this work demonstrates that the transitions between SP1 and AP1 discharges could also be induced by the electron backflow effect. It is the residual electron backflow region that provides extra seed electrons to the subsequent discharge, restraining the development of electric field in the breakdown process, thus weakening the next discharge pulse. Upon the impairment of one discharge pulse, due to the reduction of charge generation and the impairment of electron backflow effect in the relevant discharge phase, its subsequent discharge would be strengthened. Those mechanisms function in different current pulses at different gap widths, inducing the mode transition. In addition, our simulation result reveals that the “residual positive column” referred in previous publications is essentially a special form of the “electron backflow region”, which is typically more remarkable in large gap widths. As a consequence, the dynamics of electron backflow provides more insights regarding the transition of nonlinear states in DBDs with controlling parameters varying.
Abstract
Non-thermal plasma catalysis is a promising way to achieve high efficiency in applications such as energy conversion and chemical engineering. Although synergistic effect between plasma and ...catalysts has been preliminarily considered as an underlying mechanism of this type of catalysis, the formation of discharges in small-size catalyst pores, which is possible a crucial factor in plasma-activated catalysis, is still not well understood. In this paper, investigations on the interactions between a helium atmospheric pressure plasma jet (APPJ) and catalysts with micrometer-size pores of different shapes and sizes are conducted with a 2D fluid model. Simulation results show that the existence of pores makes subtle difference to the APPJ by changing equivalent capacitance, indicating the potential to achieve moderate and stable APPJ-catalysts interactions. Trace of air impurity in helium can promote the discharges in catalyst pores, and thus allow discharges forming in smaller pores. In the case when a catalyst channel is too small for direct APPJ penetration, we propose a method by producing a prior discharge in a relatively large cavity to supply seed electron to ignite discharges inside the channel. The effects of channel and cavity sizes are discussed from perspectives of discharge behavior and plasma-surface interactions. This work will contribute to the preparation of structured catalysts to potentially achieve higher efficient plasma catalysis, and better understanding the physical processes in plasma-surface interactions inside micrometer pores.
Low temperature plasmas generated inside gas bubbles immersed in water is an effective method of rapidly transferring plasma generated reactive species to the water for applications in biomedicine, ...agriculture and environment. Reactive species are generally produced in the gas phase plasma and then solvate into the liquid. The large surface-to-volume ratio (SVR) of the bubble accelerates this process. In generating bubbles in water, aerosols and droplets are also contained within the bubble. These droplets also have a large SVR and so can be rapidly plasma activated. However, the presence of the droplets can also impact the propagation of the plasma in the bubble. In this paper, results are discussed from computational and experimental investigations of the formation and evolution of discharges in an air bubble immersed in water with an embedded water droplet. The computations were performed with a two-dimensional plasma hydrodynamics model. Experiments were performed with a quasi-2D bubble apparatus. In bubbles having a droplet, a plasma filament typically bridges from the powered electrode to the droplet, and then from the droplet to the bubble surface. A surface-hugging streamer also occurs on the inner bubble surface and on the surface of the droplet. Both surface streamers result in part from surface charge accumulation and can dominate the formation of reactive species that transport into the droplet. Increasing droplet conductivity suppresses propagation of the surface discharge and leads to a lower density of aqueous reactive species. Increasing conductivity of the surrounding water does not change the overall structure of the discharge but does slightly elevate the discharge intensity. The size and shape of the embedded droplet can significantly affect the formation and propagation of the streamer.
When the overhead line passes through the forest area, the conductor may contact the line to induce the tree-contact single-phase-to-ground fault (TSF), and the persistence of TSF may induce ...wildfires, bringing serious consequences. However, the amount of TSF electrical features is weak, and traditional protection devices cannot operate effectively, so it is urgent to obtain typical characteristics of TSF. In this study, the simulation experiment is carried out for the tree-contact single-phase-to-ground fault. Firstly, the relativity between fault and characteristics like zero-sequence voltage, zero-sequence current, and differential current are analyzed theoretically. Then, the simulation experiment platform of TSF is built, and the time-varying fault characteristics are acquired. The experimental results show that the average value of the zero-sequence voltage, the amplitude of the power-frequency component of the zero-sequence current, and the amplitude of the power-frequency component of the first and end differential current can accurately reflect the fault current development trend of the single-phase contact tree fault of the conductor, and can be used as the typical characteristic quantity of TSF. The results of this study are helpful for further understanding the fault characteristics of TSF and provide theoretical support for the identification and protection design of TSF.
With the development of the power industry and the increase in the capacity of power systems, vacuum switches have been developed rapidly. The distribution characteristics of the vacuum arc can ...reflect the working conditions of the vacuum switch. So, it is vital to understand the distribution characteristics in the vacuum arc burning process for understanding the interruption performance of vacuum switches. Based on the 3D magnetohydrodynamic model, we investigated the high-current vacuum arc burning process by modeling and numerical simulation. The research findings show a certain correspondence between the change in plasma parameters values and the change in arc current. The distribution of plasma parameters is uniform when the current is small. The distribution of plasma parameters in the first 1/4 cycle is more uniform than in the second 1/4 cycle. The evolution characteristics of the arc plasma parameters for interruption before the arc current maximum differ significantly from those for interruption after the arc current maximum and current maximum. The results of this study can provide a reference for the design and improvement of vacuum switches.
A systematic investigation on the dynamics and evolution mechanisms of multiple-current-pulse (MCP) behavior in homogeneous dielectric barrier discharge (HDBD) is carried out via fluid modelling. ...Inspecting the simulation results, two typical discharge regimes, namely the MCP-Townsend regime and MCP-glow regime, are found prevailing in MCP discharges, each with distinctive electrical and dynamic properties. Moreover, the evolution of MCP behavior with external parameters altering are illustrated and explicitly discussed. It is revealed that the discharge undergoes some different stages as external parameters vary, and the discharge in each stage follows a series of distinctive pattern in morphological characteristics and evolution trends. Among those stages, the pulse number per half cycle is perceived to observe non-monotonic variations with applied voltage amplitude (Vam) and gap width (dg) increasing, and a merging effect among pulses, mainly induced by the enhanced contribution of sinusoidal component to the total current, is considered responsible for such phenomenon. The variation of incipient discharge peak phase (Φpm) is dominated by the value of Vam as well as the proportion of total applied voltage that drops across the gas gap. Moreover, an abnormal, dramatic elevation in Jpm with dg increasing is observed, which could be evinced by the strengthened glow discharge structure and therefore enhanced space charge effect.
Sepsis is organ dysfunction due to the host's deleterious response to infection, and the kidneys are one of the organs damaged in common sepsis. Sepsis-associated acute kidney injury (SA-AKI) ...increases the mortality in patients with sepsis. Although a substantial volume of research has improved the prevention and treatment of the disease, SA-SKI is still a significant clinical concern.
Aimed to use weighted gene co-expression network analysis (WGCNA) and immunoinfiltration analysis to study SA-AKI-related diagnostic markers and potential therapeutic targets.
Immunoinfiltration analysis was performed on SA-AKI expression datasets from the Gene Expression Synthesis (GEO) database. A weighted gene co-expression network analysis (WGCNA) analysis was performed on immune invasion scores as trait data, and modules associated with immune cells of interest were identified as hub modules. Screening hub geneset in the hub module using protein-protein interaction (PPI) network analysis. The hub gene was identified as a target by intersecting with significantly different genes screened by differential expression analysis and validated using two external datasets. Finally, the correlation between the target gene, SA-AKI, and immune cells was verified experimentally.
Green modules associated with monocytes were identified using WGCNA and immune infiltration analysis. Differential expression analysis and PPI network analysis identified two hub genes (
and
). Further validation using additional AKI datasets GSE30718 and GSE44925 showed that
was significantly downregulated in AKI samples and correlated with the development of AKI. The correlation analysis of hub genes and immune cells showed that
was significantly associated with monocyte infiltration and hence, selected as a critical gene. In addition, Gene single-enrichment analysis (GSEA) and PPI analyses results showed that
was significantly related to the occurrence and development of SA-AKI.
is inversely correlated with the recruitment of monocytes and the release of various inflammatory factors in the kidneys of AKI.
can be a potential biomarker and therapeutic target for monocyte infiltration in sepsis-related AKI.
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