Separate luminous structures leading positive leader steps.

The physics governing the propagation of lightning leaders and long spark leaders is still not well understood. Positive and negative leaders seem to behave differently. Negative leaders develop in a step manner, guided by the separate luminous structures termed space stems and space leaders. Positive leaders, on the other hand, are generally thought to have no separate luminous structure involved in their propagation. However, a separate luminous structure observed in a positive leader discharge had been reported in recent literature, suggesting that positive leaders may similarly do steps to negative leaders under certain conditions. Here we report the observation of the positive leader step led by a separate luminous structure at high humidity in laboratory lightning-like discharges. We also found the streamer-like common zone connecting the primary leader channel with the separate luminous structure, as well as the bi-directional development of the separate luminous structure. We hope that these findings would contribute to a better understanding of the nature underlying positive long spark leaders and lightning leaders.

Enhancing Dielectric Strength of Epoxy Polymers by Constructing Interface Charge Traps.

Epoxy polymer-based dielectric materials play a crucial role in advanced electronic devices and power equipment. However, high voltage-stress applications impose stringent requirements, such as a high dielectric strength, on epoxy polymers. Previously reported studies have shown promising material architectures in the form of epoxy polymer-nanoparticle dielectrics, which can restrict the movement of high-energy electrons by the interface charge traps associated with the various interfacial regions. However, these high-energy electrons inevitably traverse the epoxy polymer matrix and destroy the molecular structure, thereby creating a weak link for dielectric breakdown. In this study, a general strategy is developed to improve the dielectric strength by constructing interface charge traps in the molecular structure of the epoxy polymer matrix, using the -CF3 group in partial replacement of the -CH3 group. The proposed strategy increases the dielectric strength (39.5 kV mm-1) and surface breakdown voltage (26.9 kV) of the epoxy polymer matrix by 22.08% and 13.3%, respectively, because the interface charge trap hinders the movement of high-energy electrons. At the same time, the strategy does not degrade the mechanical and thermal properties. The results hold potential for wide application in the manufacturing of advanced future electrical and electronic equipment requiring resilience to high-voltage stress.

Study on the enhancing water collection efficiency of cactus- and beetle-like biomimetic structure using UV-induced controllable diffusion method and 3D printing technology.

Collecting water from fog flow has emerged as a promising strategy for the relief of water shortage problems. Herein, using a UV-induced (ultraviolet light induced) controllable diffusion method combined with technology of three-dimensional (3D) printing, we fabricate biomimetic materials incorporating beetle-like hydrophobic-hydrophilic character and cactus-like cone arrays with various structure parameters, and then systematically study their fog-harvesting performance. The UV-induced controllable diffusion method can break away from the photomask to regulate the hybrid wettability. Moreover, employing 3D printing technology can flexibly control the structure parameters to improve the water collection efficiency. It is found that the water collection rate (WCR) can be optimized by controlling the hybrid wettability of the sample surface and cone distance and using substrates with printed holes, which lead to a 109% increase of WCR.

Particle trajectories and its charging behaviors: effect of gas type and electric field.

Conductive particles in the gas insulated transmission lines (GIL) induce the breakdown between electrodes or the flashover along insulators. To solve the problem of particle moving and realize the particle-moving regulation, particle trajectories should firstly be determined in air and SF6. This paper presents the results of particle trajectories and its charging behaviors at vacuum and SF6, respectively. Metal particles with different materials and sizes were introduced and the charge quantity was calculated. The results showed that the particle lift-off electric field in SF6 was higher than that in air under the same gas pressure, that is, the charge on particle in SF6 was about 0.789 times lower than that in air under the same condition. Besides, the lift-off electric field of particle increased with the pressure increase of SF6. The charge on particle was affected by the concentration of electric field near particle and the electrical negative features of SF6. The work provided the data support for development of DC GIL in particle defect suppression.

Genetic characterization of a new radish introgression line carrying the restorer gene for Ogura CMS in Brassica napus.

Creating a homologous restorer line for Ogura cytoplasmic male sterility (Ogu-CMS) in Brassica napus is meaningful for the wider application of Ogu-CMS system in rapeseed production. Previously, an independent development of a new Ogu-CMS restorer line (CLR650) was reported locally from crossing between Raphanobrassica (AACCRR, 2n = 56) and B. napus and a new version of Ogu CMS lines CLR6430 derived from CLR650 was characterized in this study. The results showed that the fertility restoration gene in CLR6430 presented a distorted segregation in different segregating populations. However, the majority of somatic cells from roots had a regular chromosome number (2n = 38) and no radish signal covered a whole chromosome was detected using GISH. Thirty-two specific markers derived from the introgressed radish fragments were developed based on the re-sequencing results. Unique radish insertions and differences between CLR6430 and R2000 were also identified through both radish-derived markers and PCR product sequences. Further investigations on the genetic behaviors, interactions between the fertility restoration and other traits and specific molecular markers to the introgression in CLR6430 were also conducted in this study. These results should provide the evidence of nucleotide differences between CLR6430 and R2000, and the specific markers will be helpful for breeding new Ogura restore lines in future.

An electric field measurement method based on electro-optical modulation for corona discharge in air.

To study corona discharge in air, it is important to measure the electric field in the discharge space, which is directly related to the corona discharge process. In this paper, we present a method for measuring the electric field with electro-optical modulation. This method uses space laser modulation based on Bi4Ge3O12 (BGO) crystals, and we suggest using the dual optical path difference method to improve the measurement performance. The measurement error is analyzed from theory, including the measurement error of a highly inhomogeneous electric field and the error due to theoretical approximation. In system calibration, the system noise and the dual optical path difference method were analyzed. The dynamic linear range is determined, and measurement effectiveness in the severely nonuniform electric field is verified by comparison with a finite element numerical simulation. We measured the electric field in Trichel pulses under negative dc voltage and found electric field pulses. These measurement results show that the characteristics of Trichel pulses are directly related to the electric field. Therefore, this method can provide strong support for the study of corona discharges.

Which is the ideal sanction for cooperation? An experimental study on different types of third-party sanctions.

Cooperation is the crux of many social problems, thus third-party sanction, as one of the most important ways to promote cooperation, is worth studying. The present study compared the effects of third-party punishment alone, third-party reward alone, and the combination of third-party reward and third-party punishment on cooperation in the context of a public goods experiment. In addition, we explored the characteristics of third-party sanctioning behaviors. A total of 280 students participated in the present study. The results showed that the operation of third-party sanctions did raise the level of cooperation and changed the discrete trend of cooperation-specifically, the differences between the cooperation level of every group member and the average level of the whole group. Furthermore, when third-party rewards and third-party punishments were used simultaneously in the public goods game (PGG), the level of cooperation was greatly enhanced, which meant that in the context of the third party, when punishment opportunities and reward opportunities coexist, they may have a "compensatory effect." In terms of the characteristics of sanctioning behaviors, the frequency of third-party sanctions did not differ significantly under different conditions (third-party punishment alone, third-party reward alone, and a combination of third-party reward and third-party punishment), and neither did expenditures on third-party sanctions, but the strategies that third parties used changed under different conditions, thus their effects on other group members' cooperative behavior varied under different conditions. The present study provides a comprehensive picture of how third parties behave in different conditions of third-party sanctions and how these sanctions exert influence on cooperation. Understanding these mechanisms can help us build more effective institutions.

A fully enclosed, compact standard lightning impulse generator for testing ultra-high-voltage-class gas-insulated switchgears with high capacitance.

At present, conducting standard lightning impulse (LI) tests in the field for gas-insulated switchgear (GIS) equipment is difficult because of the high capacitance of the test equipment and large circuit inductance of traditional impulse devices, which leads to a wavefront time T(f) ≥ 2.5 µs. A novel fully enclosed, compact standard LI generator for testing ultra-high-voltage-class GIS equipment with high capacitance is presented to solve the problem of T(f) exceeding the standard during LI voltage tests for actual large-sized equipment. The impulse generator is installed in a metal vessel filled with SF6 or SF6/N2 gas mixture at a pressure of 0.3-0.5 MPa, providing a more compact structure and a lower series inductance. A newly developed conical voltage sensor is used to accurately measure the output voltage waveform. Two test modes (via bushing docking and direct docking) for the GIS test based on the impulse generator are introduced. Calculation results show that the impulse generator can generate an LI test waveform following the present IEC standard for the test of equipment with capacitance >10,000 pF.

Synthesis, DNA/HSA Interaction Spectroscopic Studies and In Vitro Cytotoxicity of a New Mixed Ligand Cu(II) Complex.

A new mixed ligand copper(II)-dipeptide complex with 2-(2'-pyridyl)benzothiazole (pbt), [Cu(Gly-L-leu)(pbt)(H2O)]·ClO4 (Gly-L-leu = Glycyl-L-leucine anion) was synthesized and characterized by various physico-chemical means. The DNA binding and cleavage properties of the complex investigated by viscosity, agarose gel electrophoresis and multi-spectroscopic techniques (UV, circular dichroism (CD) and fluorescence) showed that the complex was bound to CT-DNA through intercalation mode with moderate binding constant (K b = 3.132 × 10(4) M(-1)), and cleaved pBR322 DNA efficiently (~ 5 µM) in the presence of Vc, probably via an oxidative mechanism induced by •OH. Additionally, the interaction of the complex with human serum albumin (HSA) was explored by UV-visible, CD, fluorescence, synchronous fluorescence and 3D fluorescence spectroscopy. The complex exhibits desired affinity to HSA through hydrophobic interaction. Moreover, the cytotoxicity of the complex against three human carcinoma cell lines (HeLa, HepG2 and A549) was evaluated by MTT assay, which showed that the complex had effective cytotoxicity and higher inhibition toward A549 cell lines with IC50 of 38.0 ± 3.2 µM.