Antibiotics including tetracycline (TC), enrofloxacin (ENR), and norfloxacin (NOR) were efficiently degraded via photocatalytic Fenton reactions employing boron-doped ferric oxide (B-Fe2O3) as the catalyst. A series of boron-doped Fe2O3 catalysts (x-B/Fe2O3) was synthesized by pyrolyzing an iron-based metal-organic framework precursor (Fe-ZIF). Boron atoms were in situ incorporated using boric acid as the boron source during the pyrolysis process, enabling homogeneous doping of boron into the Fe2O3 lattice. Boron doping effectively narrows the band gap of Fe2O3 and shifts its conduction band edge negatively, resulting in an expanded light-response range and enhanced reduction potential. This modulation in the energy band structure increases visible-light absorption and favours the activation of H2O2, thereby promoting the generation of more reactive oxygen species in the Fenton process. The optimal degradation rate of tetracycline (TC, 100 mg center dot L-1) reached 78 % within 15 min by using 0.6 g center dot L-1B-Fe2O3 and 11 mmol center dot L-1 H2O2 in a broad pH range from 4 to 10. Trapping experiments revealed that the addition of a hole scavenger accelerated TC degradation, while the use of scavengers for excited electrons, hydroxyl radicals (center dot OH), and superoxide anion radicals (O2 center dot-) inhibited TC removal to varying extents. The generation of hydroxyl (center dot OH) and superoxide anion radicals (O2 center dot-) was confirmed by electron spin resonance (ESR) experiments using DMPO as a spin-trapping agent. center dot OH radicals were detected in aqueous suspension, while O2 center dot- radicals were identified in ethanol suspension. This demonstrates the efficiency of the prepared photocatalyst in promoting Fenton-assisted degradation of antibiotics, while also providing mechanistic insights into the active species involved.

An oxygen-doped ZnIn2S4 photocatalyst was synthesized by a one-step hydrothermal method to realize efficient degradation of high concentration of TBBPA (200 mg.L-1). Among them, the degradation rate of 150-O-ZnIn2S4 is the highest, reaching 100 % within 12 min, with a degradation amount of 400 mg center dot gcat-1 and a degradation rate of 33.33 mg center dot gcat-1 center dot min-1. The active species of center dot O2- is demonstrated to play a major role in the degradation process. Based on the structural characterization and mechanistic investigation of the catalysts, it is hypothesized that the enhanced degradation performance is due to the doped oxygen atoms. They not only broaden the photo-responsive range by narrowing the forbidden bandwidth, but also shift the conduction band position upwards and enhance the reduction ability of conduction band electrons. This work prepared an effective photocatalyst for TBBPA degradation, and significantly enhanced the degradation efficient of TBBPA.

Rapid and sensitive analysis of bisphenol A (BPA) is essential for preventing health risks to humans and animals. Hence, a signal-amplified electrochemical aptasensor without repetitive polishing and modification of working electrode was developed for BPA using Au-decorated magnetic reduced graphene oxide (Au/MrGO)-based recognition probe (RP) and DNA nanospheres (DNS)-based signal probe (SP) cooperative signal amplification. The DNS served as a signal molecule carrier and signal amplifier, while Au/MrGO acted as a signal amplifier and excellent medium for magnetic adsorption and separation. Moreover, utilizing the excellent magnetic properties of Au/MrGO eliminates the need for repetitive polishing and multi-step direct modification of the working electrode while ensuring that all detection processes take place in solution and that used Au/MrGO can be easily recycled. The proposed aptasensor exhibited not only good stability and selectivity, but also excellent sensitivity with a limit of detection (LOD) of 8.13 fg/mL (S/N=3). The aptasensor’s practicality was proven by spiking recovery tests on actual water samples and comparing the results with those detected by HPLC. The excellent sensitivity and selectivity make this aptasensor an alternative and promising avenue for rapid detection of BPA in environmental monitoring.

An ultrasensitive electrochemical biosensor to detect trace Hg2+ in environmental samples was developed utilizing nanogold-decorated magnetic reduced graphene oxide (MrGO-AuNPs), exonuclease III-assisted target cycle (Exo III-ATC) and hybridization chain reaction (HCR) synergistic triple signal amplification. The MrGO-AuNPs is a superior carrier for capture DNA (cDNA) and acts as magnetic media for automatic separation and adsorption. This innovative utilization of the magnetism and improved sensing efficiency obviates the need for direct modification and repeated polishing of the working electrode. Additionally, the three DNA hairpins (cDNA, methylene blue (MB) labeled HP1 and HP2) further contribute to biosensor specificity and selectivity. When cDNA captures Hg2+, it activates Exo III-ATC due to the formation of a sticky end in the cDNA stem via thymine-Hg2+-thymidine (T-Hg2+-T), this leads to the hydrolysis of self-folded cDNA by Exo III-ATC to form “key” DNA (kDNA). The kDNA subsequently initiates HCR, resulting in massive super-sandwich structures (kDNA-[HP1/HP2]n carrying signaling molecules on MrGO-AuNPs, and this overall structure serves as a signal probe (SP). Leveraging magnetic adsorption, the SP was automatically adsorbed onto the magneto-glass carbon electrode (MGCE), generating an amplified signal. This biosensor’s detection limit (LOD) was 3.14 pmol/L, far below the limit of 10 nmol/L for mercury in drinking water set by the US EPA. The biosensor also showed excellent selectivity when challenged by interfering ions, and the results of its application in actual samples indicate that it has good potential for practical applications in environmental monitoring.

A novel multilayer fiber mesh electrode was developed and manufactured at the pilot scale to treat ammonia nitrogen wastewater containing chlorine. The performance of the new electrode was investigated and evaluated in a lab-scale reactor and a pilot-scale reactor. The results of electrochemical characterization methods showed that the multilayer fiber mesh electrode had better performance than the plate electrode under the same conditions. Moreover, the ammonia removal efficiency with the multilayer fiber mesh electrode reached 100

随着宽禁带电力电子器件与电机技术的发展,推进电机的比功率密度与容量大大提高,能够更好的满足多电飞机推进的需求,但极端环境条件(低气压、高温)与具有高dU/dt(快速上升、下降时间)的高频方波电应力更加容易引发局部放电(partial discharge,PD),加速电机绕组绝缘材料的老化,导致电机系统失效.局部放电检测是衡量绝缘可靠性的重要手段,但与正弦电压下局部放电检测方法不同,具有高dU/dt的方波电压在上升沿和下降沿会引发强烈电磁干扰,极大地影响局部放电检测.为了解决此问题并研究低气压下多电飞机电机绝缘局放特性,提出基于特高频下混频技术和硅光电倍增技术的多电飞机推进电机绝缘局部放电联合检测方法,有效解决了高dU/dt方波下的电磁干扰问题.针对飞机实际运行工况,利用所提出的检测方法测量了不同气压下(低至20 kPa),施加方波电压时电机绝缘试样的局部放电特性,并与施加正弦电压的情况进行对比.分析了电机绝缘气-固复合绝缘的界面电荷弛豫过程,发现重复方波电压下界面弛豫电荷与局放残余电荷对瞬态电场的存在拮抗作用.提出了不同气压高dU/dt方波下局部放电起始电压的改进Paschen公式,并分析了低气压对快速方波下电机绝缘局放特性的影响规律,为多电飞机推进电机绝缘性能评估和优化设计提供参考.

Due to the on-site interference and system noise,conventional electrical measurements to detect partial discharge（PD） in gas insulated switchgear（GIS） will cause cases of missed and false detection. In order to improve the accuracy of PD detection and explore the distinction in characteristics of discharges initiated by different defects, this paper proposes a quadrifilar helical antenna optimization process based on particle swarm algorithm, designs a flexible power divider network, and forms an optic-electric integrated sensor based on ultra-high frequency antenna and silicon photomultiplier by combining flexible power divider network with silicon photomultiplier tube loaded with fluorescent fiber.On this basis, the typical discharge signals caused by defects in GIS are detected and statistically analyzed by combined sensors. The results show that the quadrifilar helical antenna attached a power division network maintains gain above 5.0dBi ranged from 0.5～2.0GHz, retaining small-size and high-gain;the discharge signals of typical defects detected by the integrated sensor show that the optical signals and the UHF signals maintain linear relationships with the discharge volume;optic-electric integrated sensing has distinctive sensing efficiencies for corona discharge, surface discharge and air-gap discharge, and the partial discharge interval time of different defect types also has different characteristics. The application of optic-electric integrated detection technology can provide a new and dependable solution for PD detection in GIS.

出于可持续发展考虑,近几十年来,飞机正在向电气化发展以减少对机械、液压和气动系统的依赖,进一步提高系统效率与可靠性.但是由于当前技术限制,多电/全电飞机的功率远不及传统飞机,提高飞机推进功率和系统比功率是重点研究问题.更高的系统电压等级和新型宽禁带功率器件都能够改善以上问题,但与此同时也会带来严峻的挑战:高海拔区域高压绝缘设计与低海拔区域有显著差异,高海拔运行将面临低气压、高温和高湿等恶劣环境条件;由宽禁带器件驱动的电机需要耐受更快上升时间和更高频的脉宽调制(pulse width modulation,PWM)脉冲电压,这会对电机绕组带来更大的冲击.本文总结了多电飞机电机电气绝缘设计相关标准与挑战,考虑了高海拔环境因素与快速PWM脉冲电应力因素对电机绝缘影响,并指出现有标准中的不足和未来研究展望.

The method of enhancing mass transfer and improving reaction efficiency by confinement has attracted much attention in the electrochemical research field. In this research, to make low diffusion-limited electrochemical reactors fieldable, a new electrochemical reactor in flow-through mode was established with the mass-produced Ti/RuO2-IrO2 felt fibers as the electrodes. The effects of voltage, current, and electrode thickness were explored in this study. When the flow mode was switched from flow-by to flow-through, the single-pass degradation effect of rhodamine B rose from 4.4% to 74.8% under the same operating conditions. Meanwhile, a mass transfer model was established based on the results of removal efficiency and electrode channel parameters. The model was in good agreement with the new electrode parameters verification (R-2 > 0.970). With this model, it could derive specific results on the effect of pore size change on the treatment effect. The impact of enhancing mass transfer by confining the pore sizes is most clearly gained at a certain range (less than 100 mu m). Furthermore, a pilot-scale electrochemical reactor in flow-through mode was built, and excellent performance was shown in the treatment of actual waste leachate. The removal efficiencies of total nitrogen, ammonia, and nitrate were 80.9%, 88.6%, and 64.5% in 30 min, respectively. It will be a promising technology with good prospect.

随着高压功率模块在直流输电、高速铁路和新能源发电等领域的普及和应用,高压功率模块的可靠性问题将越来越突出.该文阐述高压功率模块封装结构、绝缘材料、放电检测、失效机理以及可靠性改进等方面研究的最新进展.首先,针对现有的高压功率模块封装结构,分析广泛应用的高压硅基IGBT和SiC MOSFET模块的封装结构,以及高压功率模块封装绝缘材料的类型与特性.随后,评述高压功率模块封装绝缘的老化和失效机理以及现有的局部放电评估标准和测量方法.此外,总结高压功率模块封装绝缘可靠性改进的方法.在综述的基础上,结合高压功率模块小型化、集成化、耐高温化的发展趋势,指出高压功率模块封装绝缘的主要威胁、挑战和发展趋势.

Surface flashover is an important accident threating the safe operation of gas-insulated switchgear (GIS). Non-invasive surface potential measurement for flashover test device with finger-shape electrodes is proposed,and the feasibility of this device is analyzed by finite element software. The results show that non-invasive measurement error is 2.42% under simulation parameter settings in this paper. Surface potential of epoxy with nano-SiO2 mass fraction of 2% is measured using this device and the ascending applied voltage step is 0.5 kV/5 min. When the applied voltage is unable to induce flashover phenomenon,Maxwell-Wagner interface polarization caused by nanoparticle addition causes surface potential decay process. When the applied voltage approaches flashover voltage,surface potential presents periodic rise phenomenon in the decay process and the frequency of rise phenomenon becomes faster as the applied voltage higher. Periodic rise phenomenon in surface potential decay process before flashover can be used as a signal for predicting surface flashover. Fluctuation of surface potential in the continuous flashover process is smaller than that of intermittent flashover and the interval between adjacent flashover becomes shorter,which is related to the fact that surface burning path in the continuous flashover is prone to flashover. Surface potential measurement of DC flashover provides guidance for flashover prevention and flashover severity evaluation.

Herein, a sensitive electrochemical biosensor based on an enzyme-free and entropy-driven DNA walker is presented for the determination of Hg2+. This biosensor uses Hg2+ as a key to induce a mismatch between thymine-rich oligonucleotides to start the DNA walker, and it utilizes the entropy change of the sensing system to continuously drive the hybridization of oligonucleotides as a driving force for its walking. As the DNA walker runs, the detection signal is amplified to improve the sensitivity of the biosensor. Square wave voltammetry (SWV) of this biosensor shows a linear response of the methylene blue (MB) oxidation signal with an increase of Hg2+ concentration in the range of 0 to 80 nM with a detection limit of 0.136 nM, which satisfactorily meets the sensitivity requirement of the U.S. Environmental Protection Agency (EPA). The biosensor also exhibits excellent selectivity over a spectrum of interfering ions and performs well in real water samples, suggesting that it is a promising candidate for Hg2+ detection.

The Trichel pulse in negative corona discharge received widespread attention, while the current pulse in surface discharge was rarely mentioned. This paper took the needle-plate electrodes for surface discharge, and the epoxy sample was fixed on the electrodes. A negative ramping voltage with a rising rate of 200 V/min was applied to the needle electrode, both discharge current and light signal were measured. The current pulse and the light pulse appeared synchronously when discharging, and the discharge current amplitude kept a linear relationship with the light signal amplitude. The pulse sequence pattern changed with the applied voltage increased, and the turning voltage was around 8.6 kV. The increased voltage made it easier for the accumulated surface charge to reach the discharge threshold, and the pulse sequence showed lower amplitude and shorter intervals.

Bisphenol A (BPA) is a harmful endocrine disruptor, sensitive and rapid quantification of BPA is highly desirable. In this work, a novel synergistic signal-amplifying electrochemical biosensor was developed for BPA detection by using a recognition probe (RP) constructed by BPA aptamer modified gold nanoparticles-loaded magnetic reduced graphene oxide (Aptamer-MrGO@AuNPs), and a signal probe (SP) constructed by BPA aptamer-complementary single-stranded DNA (ssDNA) functionalized methylene blue (MB)-loaded gold nanoparticle (ssDNA-AuNP@MBs). The RP and SP can self-assemble to form a stable RP-SP complex through complementary base pairing. The current intensity of the biosensor correlates with the number of RP-SP complexes. In the presence of BPA, the BPA aptamer can capture BPA with high selectivity and affinity, form an RP-BPA complex and dissociate the RP-SP complex to release SP, resulting in a decrease in the current signal intensity of the biosensor. A single AuNP could be loaded with multiple BPA aptamers and MBs, which improves the recognition efficiency and enhances the signal intensity. Due to the magnetic properties of MrGO@AuNPs, the magnetic separation and adsorption of RP or RP-SP complex is very convenient, enabling all reaction processes to be carried out in solution, which not only improves the mass transfer efficiency, but also simplifies the operation. Under optimal conditions, the developed biosensor had a detection limit as low as 0.141 pg/mL and had been successfully applied to the detection of real environmental water samples. Therefore, the synergistic signal amplification strategy of RP and SP has potential value in the detection of trace pollutants in the water environment.

To study the electrical tree growth and partial discharge (PD) characteristics of cross-linked polyethylene (XLPE) under the DC electric field, the XLPE insulation was made into needle-plate electrode samples to carry out experiments at 25°C and 50 °C. The results show that the electrical tree grows at 50°C accompanied by PD, and the PD amplitude positively correlates with the tree length. However, under the same voltage condition, the DC electrical tree does not grow at 25°C, and there is only a small amount of PD observed. The elevated temperature not only promotes the growth of the electrical tree but also enhances the amplitude and frequency of PD signals. In addition, when the power is turned off and the applied DC voltage begins to decay to zero, PD with the reversal polarity can be detected in the sample with an electrical tree defect at both 25°C and 50 °C. With the exponential decline of the applied voltage, the PD amplitude increases, as well as the discharge interval, until the applied voltage is close to zero. This may be due to the formation of a reverse electric field at the needle tip during the applied voltage drop, resulting in PD in the electrical tree.

在高压直流电缆接头绝缘中,携带被深陷阱捕获电荷的分子链在库伦力作用下会发生位移,导致聚合物绝缘中深陷阱能级发生变化,进而对电荷输运造成影响.该文基于分子链动力学对传统双极性电荷输运模型进行改进,在温度梯度下分析高压直流电缆接头不同界面的深陷阱能级、空间电荷及电场分布,探讨在温度梯度下深陷阱能级变化对电缆接头绝缘界面电荷分布的影响.研究表明:基于分子链动力学改进的双极性电荷输运模型中,复合绝缘界面以及介质内部深陷阱能级增大,导致电荷在介质内部的扩散和迁移受到阻碍,大量电荷在界面积聚;界面电荷分布规律与界面深陷阱能级分布一致;相较于接头内部整体高温,接头两侧存在较大的温差更容易使接头绝缘面临更严峻的挑战,电缆接头在10K的温差下能够保持较为良好的电气绝缘和运行状态.所得结果为进一步理清电缆接头绝缘电荷输运特性提供了支撑.

随着我国特高压直流输电系统工程的发展,换流变压器的电压等级越来越高,绝缘问题也越来越突出.局部放电的研究对于换流变压器绝缘状况的判断以及设备寿命的评估具有重要的意义.本文介绍了换流变压器的绝缘特点、现场试验的过程、局部放电的检测方法及其注意事项,回顾了中外专家学者对换流变压器局部放电研究的成果,最后展望了换流变压器局部放电的研究方向,为换流变压器的运行维护和学术研究提供参考.

局部放电(partial discharge,PD)检测天线在检测方向上应保持高增益,以改善灵敏度和信噪比.由于适配的功分网络截面积大,因此高增益立体螺旋天线尚未运用于局部放电检测领域.以单臂螺旋天线和四臂螺旋天线作为研究对象,通过仿真确定天线优化区间,并以带宽、增益作为目标,基于粒子群优化算法优化结构参数,以提高检测灵敏度,保持定向高增益;设计适配的柔性功分馈电网络,以减小天线体积、提高信噪比;通过局放测试检验设计的高增益立体螺旋天线的性能,并与商用平面等角螺旋天线比较.研究结果表明:优化后的单臂螺旋天线具有多频段检测特点,结构简单,占用空间小;通过柔性功分网络加载的四臂螺旋天线在0.5～2.0 GHz频段的增益均＞5.0dB,主谐振点1.02 GHz处的增益达到了 6.37 dB,整体横截面直径缩小至60mm,测试信噪比优于平面等角螺旋天线.与传统局放检测天线相比,设计的高增益柔性馈电立体螺旋天线能在特高频范围的低频段保持高增益,并在各谐振频率保持轴向检测特性.

Although the activation of H(2)O(2 )by electro-generated atomic hydrogen (H*) on Pd to produce hydroxyl radical (center dot oH) has been considered promising in wastewater oxidation, low apparent reaction kinetic constant (k(obs)) around 0.15.h(-1) still restricted its application, being only suitable for mu g.L-1-level decontamination. Application of water treatment containing mg.L-1-level pollutants requires a significant increase of k(obs). Herein, we introduced a 316L fiber felt as the cathode to electrocatalytic activate H(2)O(2 & nbsp;)in the flow-through reactor for wastewater treatment. Using recently developed mu m-scale metal fiber electrode, both the diffusion of H2O2, the generation of surface-adsorbed active species of H*, stabilization of intermediate, and the mass transfer of pollutants could be enhanced in flow-through reactor. A k(obs )of 1.93 & BULL;h? 1 of mineralization to 30 mg & BULL;L? 1 benzoic acid, being 12.8 times over previously reports, had been reached at pH 3.0, which was the most robust direct electrocatalytic activation of H2O2 & nbsp; accordingly up to now. The activation intermediate of center dot & nbsp;OH was demonstrated by DMPO in-situ trapping and electron spin resonance measurement which guaranteed mineralization of contaminations. It was also demonstrated a balance of pH 3.0 by bipolar membrane during 180 min, which guaranteed a stable k(obs) during long time electrolysis. Strategies reported in this study promote electrocatalytic activation of H(2)O(2 & nbsp;)to be practically applicable and support further development for green water oxidation of water containing higher concentration contaminants.

交联聚乙烯(XLPE)电缆中电树枝的生长伴随局部放电(PD)的产生,二者间存在一定关联.XLPE材料绝缘强度较高,其中发生的PD在超高频(SHF,3～30 GHz)频段的信号幅值相对较高.文中采用基于针-板电极结构和XLPE绝缘材料的试样,在不同温度和电压下对电树枝生长过程中的形态和PD的SHF信号进行同步检测,分析了电压与温度条件对二者的影响,并研究了二者间的特征关系.研究表明XLPE中电树枝的长与宽和温度与电压呈正相关,电压较低时对分形维数较低,较高时分形维数无明显变化.SHF信号幅值也与温度和电压呈正相关关系,电压较高时,信号幅值呈现先增大再减小至平缓趋势,频率在电压较低时信号有一定程度下降.电树枝生长情况和SHF信号的幅值呈正相关关系,且当电树枝生长速度较快时,SHF信号的频率也会升高.