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Epoxyaclay nanocomposites were prepared using two types of surface-treated montmorillonite (Closite 30B and Nanomer I28E). Wide angle X-ray scattering showed that all the nanocomposites had an intercalated structure. Improvements in tensile and fracture properties were found. The pure epoxy polymer was very brittle with a fracture energy, G c, of 131 J ma2. The addition of the nanoclays significantly increased the value of G c, up to 240 J ma2 for 5 wt% C30B. The toughening mechanisms acting in the nanocomposites were identified using scanning electron microscopy as crack deflection and plastic deformation of the epoxy matrix around the clay platelets following debonding. From electrical testing, the permittivity and loss angle of the nanocomposites decreased, and their breakdown strength increased as desired for insulation applications. The breakdown strength of the pure epoxy was found to be 11.7 kV mma1, while for a 2 wt% C30B nanocomposite, it increased to 14.7 kV mma1. It was concluded that the restriction of chain mobility inhibited electrical polarisation and thus decreased the permittivity and loss angle. The electrical damage zone was analysed using scanning electron microscopy. It was found that the higher resistance-to-surface degradation by partial discharges and the creation of a tortuous electrical path, which delayed the propagation of the electrical tree, were the main factors which improved the breakdown strengths of the nanocomposites.

This article proposed a new extended gate towards a source in AlGaN/GaN metal-oxide-semiconductor-high-electron-mobility transistors in order to increase breakdown voltage and reduce on-resistance. The TaN gate was isolated from the source by a 15 nm-thick RF-sputtered HfO sub( 2) gate insulator. A high breakdown voltage of 1410 V was measured as a result of the successfully blocked gate leakage current and surface passivation by the HfO sub( 2) gate insulator. The extended gate towards the source was an effective method to improve the on-resistance and drain current density by eliminating the gate-source space. The proposed device with the extended gate exhibited low specific on-resistance of 2.28 m Omega ...cm super( 2) while that of the MOS-HEMT with the conventional structure was 2.91 m Omega ...cm super( 2). Also, maximum drain current density at the V sub( GS) of 2 V was increased from 332 to 420 mA/mm by the proposed extended TaN gate.(ProQuest: ... denotes formulae/symbols omitted.)

A series of strontium barium niobate-based borate system glass-ceramics with Gd sub(2)O sub(3) addition have been prepared by controlled crystallization method. The effect of Gd sub(2)O sub(3) addition on the microstructure, phase evolution and dielectric properties has been investigated. The results show that the addition of Gd sub(2)O sub(3) to the glass-ceramics changes the dielectric property and energy-storage density. Typically, the glass-ceramics with 0.5 mol% Gd sub(2)O sub(3) heat treated at 630 degree C/2 h + 800 degree C/3 h possesses a dielectric constant of 136, a breakdown strength of 1,075 kV/mm and energy-storage density of 6.94 J/cm super(3), which is suitable for the application in high energy-storage capacitors.

Aiming at the transient process generated by the operation of the disconnector, the fast transient overvoltage (VFTO) transmitted to the casing from the GIS system causes the induced casing voltage between the casing and the ground, posing safety hazards to the secondary equipment and operation personnel of the GIS system. This paper combines the internal VFTO and external TEV transient circuits of GIS, considers the mutual coupling of the three-phase GIS enclosures, establishes a 252 kV GIS system transient model, and studies the characteristics of the three-phase GIS enclosure TEV under multiple breakdown discharge conditions of the disconnector, providing a theoretical basis for the external measurement of the transient induced casing voltage. In the process of multiple breakdown conditions, the maximum TEV value of the operating phase is the highest, with the maximum TEV amplitude reaching 0.03 p.u. in Phase A. TEV amplitude of the operating phase is significantly higher than that of the other two phases.

In this paper, the transient breakdown voltage (TrBV) of a silicon-on-insulator (SOI) laterally diffused metal-oxide-semiconductor (LDMOS) device was increased by introducing a step P-type doping buried layer (SPBL) below the buried oxide (BOX). Device simulation software MEDICI 0.13.2 was used to investigate the electrical characteristics of the new devices. When the device was turned off, the SPBL could enhance the reduced surface field (RESURF) effect and modulate the lateral electric field in the drift region to ensure that the surface electric field was evenly distributed, thus increasing the lateral breakdown voltage (BVlat). The enhancement of the RESURF effect while maintaining a high doping concentration in the drift region (Nd) in the SPBL SOI LDMOS resulted in a reduction in the substrate doping concentration (Psub) and an expansion of the substrate depletion layer. Therefore, the SPBL both improved the vertical breakdown voltage (BVver) and suppressed an increase in the specific on-resistance (Ron,sp). The results of simulations showed a 14.46% higher TrBV and a 46.25% lower Ron,sp for the SPBL SOI LDMOS compared to those of the SOI LDMOS. As the SPBL optimized the vertical electric field at the drain, the turn-off non-breakdown time (Tnonbv) of the SPBL SOI LDMOS was 65.64% longer than that of the SOI LDMOS. The SPBL SOI LDMOS also demonstrated that TrBV was 10% higher, Ron,sp was 37.74% lower, and Tnonbv was 10% longer than those of the double RESURF SOI LDMOS.

We investigate sequential processes underlying the initial development of in‐cloud lightning flashes in the form of initial breakdown pulses (IBPs) between 7.4 and 9.0 km altitudes, using a 30–250 MHz VHF interferometer. When resolved, IBPs exhibit typical stepped leader features but are notably extensive (>500 m) and infrequent (∼1 millisecond intervals). Particularly, we observed four distinct phases within an IBP stepping cycle: the emergence of VHF sources forming edge structures at previous streamer zone edges (interpreted as space stem/leader development), the fast propagation of VHF along the edge structure (interpreted as the main leader connecting the space leader), the fast extension of VHF beyond the edge structure (interpreted as fast breakdown), and a decaying corona fan. These measurements illustrate clearly the processes involved in the initial development of in‐cloud lightning flashes, evidence the conducting main leader forming, and provide insights into other processes known to occur simultaneously, such as terrestrial gamma ray flashes. Plain Language Summary The initial development of a lightning flash inside a cloud has long been a mystery. This study utilizes state‐of‐the‐art lightning imaging techniques with a 30–250 MHz VHF interferometer, providing clear images of the processes involved in the initial development of in‐cloud lightning flashes. New radio features suggest distinct development phases, including what we interpret as space stems, space leaders, connection between the main leader and the space leader, fast breakdown, and corona fan development within an initial breakdown pulse stepping cycle. This provides evidence of the conducting main leader in the initial breakdown stage. These observations showcase the intricate streamer discharge phenomena during initial lightning development, and shed light on other processes known to occur simultaneously, including Terrestrial Gamma ray Flashes. Key Points We observed four distinct VHF processes in the development of 300–1,000 m long initial breakdown pulses (IBPs) in in‐cloud lightning flashes These four processes appear to map to the known processes in a conventional stepped leader, including space stem and space leader formation During an initial breakdown step, fast extension over several hundred meters indicates that fast breakdown may be an essential part of in‐cloud flash

Epilepsy, a neurological disease characterized by recurrent seizures, is often associated with a history of previous lesions in the nervous system. Impaired regulation of the activation and resolution of inflammatory cells and molecules in the injured neuronal tissue is a critical factor to the development of epilepsy. However, it is still unclear as to how that unbalanced regulation of inflammation contributes to epilepsy. Therefore, one of the goals in epilepsy research is to identify and elucidate the interconnected inflammatory pathways in systemic and neurological disorders that may further develop epilepsy progression. In this paper, inflammatory molecules, in neurological and systemic disorders (rheumatoid arthritis, Crohn’s, Type I Diabetes, etc.) that could contribute to epilepsy development, are reviewed. Understanding the neurobiology of inflammation in epileptogenesis will contribute to the development of new biomarkers for better screening of patients at risk for epilepsy and new therapeutic targets for both prophylaxis and treatment of epilepsy.

In order to study the effects of the crystallinity of polyethylene with different densities on breakdown strength and conductance properties, this paper mainly tests the X-ray diffraction (XRD), different scanning calorimeter (DSC), direct current (DC) breakdown and conductance properties of low-density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), and high-density polyethylene (HDPE), and further analyzes the experimental results separately. The results show that an increase in the density of polyethylene leads to the continuous improvement of crystallinity, and an increase in crystallinity causes a significant decrease in the conduction current at the same field strength. The field strength corresponding to the two turning points in the conductance characteristic curve increases simultaneously.

In this study, the DC breakdown characteristics of CF3I-N2 mixtures at low pressure are investigated and compared with those of pure CF3I to assess their insulating properties. Utilizing the particle-in-cell/Monte Carlo collisions (PIC/MC) model, we explore the breakdown process in detail, analyzing electron and ion kinetics across various phases. Our findings reveal that the CF3I-N2 mixture exhibits a faster breakdown rate than pure CF3I but requires more time to achieve a steady state. Additionally, we examine the Paschen curve of CF3I-N2 at varying pressures, discovering that the insulating performance improves with higher CF3I proportions at increased pressures. This study contributes to understanding the insulating behavior of CF3I-N2 mixtures, offering insights for their application in environmentally friendly high-voltage insulation technologies.