Search

The Simultaneous Localization and Mapping (SLAM) technique has achieved astonishing progress over the last few decades and has generated considerable interest in the autonomous driving community. With its conceptual roots in navigation and mapping, SLAM outperforms some traditional positioning and localization techniques since it can support more reliable and robust localization, planning, and controlling to meet some key criteria for autonomous driving. In this study the authors first give an overview of the different SLAM implementation approaches and then discuss the applications of SLAM for autonomous driving with respect to different driving scenarios, vehicle system components and the characteristics of the SLAM approaches. The authors then discuss some challenging issues and current solutions when applying SLAM for autonomous driving. Some quantitative quality analysis means to evaluate the characteristics and performance of SLAM systems and to monitor the risk in SLAM estimation are reviewed. In addition, this study describes a real-world road test to demonstrate a multi-sensor-based modernized SLAM procedure for autonomous driving. The numerical results show that a high-precision 3D point cloud map can be generated by the SLAM procedure with the integration of Lidar and GNSS/INS. Online four–five cm accuracy localization solution can be achieved based on this pre-generated map and online Lidar scan matching with a tightly fused inertial system. [ABSTRACT FROM AUTHOR]

Simple Summary: Nile tilapia (Oreochromis niloticus) as one of the main commercially cultivated fishes in China, is plagued by liver diseases caused by some stressors. Salvianolic acid B (Sal B) has the strongest antioxidant effect and has a good protective effect on the liver. The objective of this study is to evaluate the protective effect of Sal B on oxidative hepatic injury in Nile tilapia, followed by assessing the potential protective mechanism. Our experimental data show that Sal B can not only directly reduce the level of reactive oxygen species (ROS), but can also resist CTX-induced oxidative injury by adjusting the autophagy and apoptosis levels of hepatocytes. Notably, the hepatoprotective effect of Sal B on Nile tilapia is related to the regulation of Nrf2, AMPK/mTOR and MAPK pathways. The research will lay the foundation for the application of Sal B in tilapia culture. Salvianolic acid B (Sal B), as one of the main water-soluble components of Salvia miltiorrhizae, has significant pharmacological activities, including antioxidant, free radical elimination and biofilm protection actions. However, the protective effect of Sal B on Nile tilapia and the underlying mechanism are rarely reported. Therefore, the aim of this study was to evaluate the effects of Sal B on antioxidant stress, apoptosis and autophagy in Nile tilapia liver. In this experiment, Nile tilapia were fed diets containing sal B (0.25, 0.50 and 0.75 g·kg−1) for 60 days, and then the oxidative hepatic injury of the tilapia was induced via intrapleural injection of 50 g·kg−1 cyclophosphamide (CTX) three times. After the final exposure to CTX, the Nile tilapia were weighed and blood and liver samples were collected for the detection of growth and biochemical indicators, pathological observations and TUNEL detection, as well as the determination of mRNA expression levels. The results showed that after the CTX treatment, the liver was severely damaged, the antioxidant capacity of the Nile tilapia was significantly decreased and the hepatocyte autophagy and apoptosis levels were significantly increased. Meanwhile, dietary Sal B can not only significantly improve the growth performance of tilapia and effectively reduce CTX-induced liver morphological lesions, but can also alleviate CTX-induced hepatocyte autophagy and apoptosis. In addition, Sal B also significantly regulated the expression of genes related to antioxidative stress, autophagy and apoptosis pathways. This suggested that the hepatoprotective effect of Sal B may be achieved through various pathways, including scavenging free radicals and inhibiting hepatocyte apoptosis and autophagy. [ABSTRACT FROM AUTHOR]

With the development of technology, low-temperature plasma plays an increasingly important role in industrial applications. The industrial application of low-temperature plasma has the following requirements for plasma, high electron energy, low macroscopic temperature, and uniformity. Low-temperature plasma driven by nanosecond pulses reflects more significant advantages in these aspects compared to direct current plasma and alternating current plasma. In this paper, a simple topology is proposed, which is based on the pseudospark switch and the diode opening switch. A pulse generator is developed, which can eventually output pulses with an amplitude of 106 kV, a rise time of 15.5 ns, a pulse width of 46 ns, and a maximum repetition rate of 1 kHz on a 260 Ω resistive load. The pulse generator can successfully drive needle-plate discharge plasma in ambient air. It has excellent parameters, stability, compactness, and a long lifetime. The proposed topology may be helpful for nanosecond pulse generators with amplitude ranging from tens to hundreds of kilovolts, which could be widely used in industry. [ABSTRACT FROM AUTHOR]

Pseudospark switch is a special kind of low-pressure (typically 1–100 Pa) high-voltage pulsed discharge switch with the hollow electrode configuration. This paper experimentally investigates the pre-breakdown processes of a single-gap pseudospark switch triggered from the anode side. The species and contents of impurities on copper electrode surface are firstly analyzed, which mainly include C, N and O. Then, at the same conditions, the trigger delay and jitter of triggering from the anode side are significantly higher than the cathode side, as well as the minimum voltage and pressure that the switch can be triggered. The evolution of the discharge region of the pseudospark switch triggered from the anode side is observed by the ICCD camera for the first time in the literature. The time-resolved images show that the luminescence firstly appears in the hollow anode where the trigger discharge happens and then in the hollow cathode, the cathode hole, the main gap and the anode hole successively, which is completely different from triggering from the cathode side. Finally, a model considering the migration and collisions of ions and fast atoms is established, and it points out that the ion flux from the hollow anode plays an important role in triggering from the anode side. The key processes also include the formations of the positive space charge column inside the hollow cathode and the intense secondary electron emission as an electron source for the main gap. • Ignition mechanism of pseudospark switch triggered from the anode side by ion beams. [ABSTRACT FROM AUTHOR]

Electrode erosion caused by dense plasma in constrictive discharge channel is one of the fundamentally detrimental effects existing in pulsed discharge switches. An enhanced plasma expansion in pseudospark discharge assisted by a magnetic switch (MS) is observed from ICCD images in this paper, accompanied by reduced commutation loss, and the mechanisms are revealed by experiments and simulations. The characteristics of the discharge waveforms and channel images of the pseudospark discharge with and without a series-connected MS are compared, and the influence of the number of magnetic cores is studied. As the loop current increases, the discharge channel expands radically and reaches the maximum as the current rising rate reaches the maximum. As the number of magnetic cores increases from 0 to 8, the maximum diameter of the discharge channel increases from 16 mm to about 38 mm, and the commutation loss is reduced from 30 mJ to 11 mJ. The electrode erosion rate of the case with a MS is lower than that without a MS. A particle in cell/Monte Carlo collision model coupling to nonlinear external circuit elements is established. The simulation results fit well with the experiment phenomena, including the discharge waveforms and the profiles of the discharge channel. The distribution of ions shows more diffused features than that of electrons, while the distribution of electrons is more similar to the discharge channel observed in experiments. The enhanced plasma expansion is mainly caused by the higher radial acceleration component of the charged particles during the magnetically delayed time. [ABSTRACT FROM AUTHOR]

Electrode erosion caused by dense plasma in constrictive discharge channel is one of the fundamentally detrimental effects existing in pulsed discharge switches. An enhanced plasma expansion in pseudospark discharge assisted by a magnetic switch (MS) is observed from ICCD images in this paper, accompanied by reduced commutation loss, and the mechanisms are revealed by experiments and simulations. The characteristics of the discharge waveforms and channel images of the pseudospark discharge with and without a series-connected MS are compared, and the influence of the number of magnetic cores is studied. As the loop current increases, the discharge channel expands radically and reaches the maximum as the current rising rate reaches the maximum. As the number of magnetic cores increases from 0 to 8, the maximum diameter of the discharge channel increases from 16 mm to about 38 mm, and the commutation loss is reduced from 30 mJ to 11 mJ. The electrode erosion rate of the case with a MS is lower than that without a MS. A particle in cell/Monte Carlo collision model coupling to nonlinear external circuit elements is established. The simulation results fit well with the experiment phenomena, including the discharge waveforms and the profiles of the discharge channel. The distribution of ions shows more diffused features than that of electrons, while the distribution of electrons is more similar to the discharge channel observed in experiments. The enhanced plasma expansion is mainly caused by the higher radial acceleration component of the charged particles during the magnetically delayed time. [ABSTRACT FROM AUTHOR]

In this paper, a novel repetitive frequency voltage booster (named repetitive Fitch booster by the authors) based on magnetic switches and Fitch generators is proposed. The principle of operation is to charge capacitors in parallel when magnetic switches (MSs) are unsaturated and reverse voltage polarity of every other capacitor when MSs saturate. With the principle, circuit topology of a 4-stage repetitive Fitch booster (RFB) is presented. Simulation as well as experiment shows its feasibility in boosting voltage and compressing rise-time. In simulation, the input voltage of 100 V is boosted to 372 V, while test stand yields output voltage with frequency of 1 kHz, amplitude of 19 kV with each capacitor charged to about 5.6 kV, and rise-time compression from 7.3 μs to 700 ns. Meanwhile, calculations show that the 4-stage RFB effectively reduces core volume by about half, from 1093.5 cm3 to 585.2 cm3. Furthermore, design rules are proposed so that topologies of RFBs with stages other than four can be conveniently derived. As an example, an 8-stage RFB is proposed and verified with circuit simulation, which shows an output voltage of 759 V with the input voltage of 100 V. [ABSTRACT FROM AUTHOR]

Electrical wire explosions have many applications in scientific research and industry. Optical diagnosis is a powerful method to clarify the evolutionary process of such explosions. In this paper, an experimental platform was established to diagnose the optical radiation of electrical wire explosions. A low-jitter trigatron switch and its trigger generator were designed to ensure accurate synchronization. The spatial–temporal evolution process and the self-emission spectrum of electrical explosion plasmas from different wires (copper and tantalum) were obtained and analyzed. The optical diagnosis results indicated that the electrical explosion of copper wire was mainly characterized by the inhomogeneity of partial ionization and the rapid expansion of the discharge channel. The spectrum in the early discharge stage of the copper wire electrical explosion was a continuum, and most of the self-radiation spectral lines belonged to Cu I or Cu II. At the later stage of the plasma dissipation process, the continuous spectrum gradually transformed into a line spectrum. The development of the tantalum wire discharge channel was relatively uniform, and the plasma was mainly established in the gas–liquid mixed phase channel of the tantalum wire. The self-emission spectrum of the tantalum wire was always continuous, and the absorption process of line spectrum radiation was distinct. [ABSTRACT FROM AUTHOR]

The present study aimed to evaluate the hepatoprotective effects of Angelica sinensis extract (ASE) against carbon tetrachloride (CCl4)-induced hepatotoxicity in Jian carp ( Cyprinus carpio var.Jian). Fish were fed diets containing four doses of ASE (0%, 0.1%, 0.5% and 1.0%) for 60 days, and then given an intraperitoneal injection of 30% CCl4 in olive oil at a volume of 0.05 mL/10 g body weight. At 72 h post injection, blood and liver samples were collected for biochemical analysis, comet assay, histopathological examination and CYP3A mRNA expression. Results showed that the increases of glutamate pyruvate transaminase (GPT) and glutamate oxalate transaminase (GOT) induced by CCl4 were significantly inhibited by pre-treating the fish with 0.1%, 0.5% and 1.0% ASE in the diets. The elevation of lactate dehydrogenase (LDH) and the reductions of the total protein (TP) and albumin (Alb) in the serum induced by CCl4 were also inhibited by pre-treatments with 0.5 and 1.0% ASE. In the liver tissue, pre-treatment with 1.0% ASE significantly inhibited the malondialdehyde (MDA) formation and the reductions of the total antioxidant capacity (T-AOC), superoxide dismutase (SOD), glutathione (GSH) and CYP3A mRNA expression induced by CCl4. Comet assay showed that tail moment, olive tail moment, tail length and tail DNA% were positively changed in fish pretreated with 0.5 and 1.0% ASE. CCl4-induced histological changes were obviously reduced by 0.5% and 1.0% ASE. Overall results prove the hepatoprotective effect of ASE in a dose-dependent manner and support the use of ASE (1.0%) as a hepatoprotective and antioxidant agent in fish. [ABSTRACT FROM AUTHOR]

In this paper, an experimental study was performed to document the characteristics of underwater electrical explosions involving different wires made from 15 different metals/alloys. Experiments were undertaken with those wires (4 cm in length; 100–300 μm in diameter) driven by a pulsed current source with 500 J initial stored energy. The results indicated that the electrical and thermophysical properties of the metal were critical in the explosion process. Non-refractory metals, such as Al, Cu, Ag, and Au, absorbed about twice as much energy as their enthalpy of atomization before the voltage peak, while for refractory metals, such as Nb, Mo, Ta, and W, the deposited energy before the peak was close to their atomization enthalpy. Accordingly, the strongest measured shock wave for non-refractory metals was 12.4 MPa (peak pressure) while that for refractory metals was only 8.5 MPa (peak pressure). By contrast, the light intensities of non-refractory metals were at least an order of magnitude lower than those of refractory metals. From 100 to 300 μm, the estimated average temperature at the plasma-water interface decreased from ∼10 000 K to ∼4000 K. It was also found that, as evidenced from the time-integrated spectra, obvious chemical reactions occurred between water and relatively active metals such as Al, Ti, and Fe. In addition, Pt and Au, which have high first ionization energies, exhibited longer current pauses (>50 μs) or vaporization phases relative to the other metals. [ABSTRACT FROM AUTHOR]

To reduce the commutation loss of the pseudospark switch, we connect a magnetic switch in series to the anode of the pseudospark switch. Herein, the typical discharge process and switching characteristics of a pseudospark switch in series with a magnetic switch are experimentally investigated at a different number of magnetic cores, gas pressures, and applied voltages. The results show that the addition of the magnetic switch extends the duration of the hollow cathode discharge of the pseudospark. Moreover, the rapid increase of the loop current and the fast decrease of the discharge voltage are separated, which is beneficial for reducing the commutation loss. With an increasing number of magnetic cores, the magnetic delay time increases and the commutation loss significantly decreases. However, the trigger delay time hardly changes since the magnetic switch does not affect the development of the pre-breakdown phase. At a fixed applied voltage, the trigger delay, magnetic delay time, and commutation loss decrease with increasing gas pressure. Furthermore, at a fixed gas pressure, the trigger delay of the pseudospark switch in series with a magnetic switch first decreases and then remains unchanged with increasing applied voltage, which is similar to that of a pseudospark switch without a magnetic switch because of the strong enough trigger injection. The magnetic delay time decreases and the commutation loss almost linearly increases with increasing applied voltage. [ABSTRACT FROM AUTHOR]

Used widely in microwave devices and material processing, triggered pseudospark discharge can generate an electron beam, the adjustability of which is affected greatly by the working gas pressure and the applied voltage of the pseudospark discharge. This paper reports the development of an electron-beam source based on a single-gap triggered pseudospark discharge device. Its working performance, as measured by the peak beam current, charge quantity, and pulse width, was studied experimentally, and the results showed that the peak beam current increased initially and then decreased with increasing gas pressure. This was because the beam current was limited by the low plasma density at low pressures, while the electron scattering and ion neutralization during drift decreased the beam current at high pressures. The pulse width of the beam current was consistent with that of the loop current and was determined by the damping coefficient of the discharge circuit. With increasing gas pressure, the pulse width decreased gradually. When the gas pressure was constant, the peak beam current increased significantly with increasing applied voltage because of the enhanced electron-emission current and weakened electron scattering. The charge quantity of the beam current also increased with increasing applied voltage, but the pulse width decreased slightly. Based on the above results, this paper also reports qualitative analysis of the change of the discharge process corresponding to the variation of the electron-beam parameters with gas pressure and applied voltage. [ABSTRACT FROM AUTHOR]

In this article, we show the feasibility of improving the performance of a high voltage and high repetition avalanche transistor pulse generator by applying a two-phase immersion cooling technique. The forced air cooling, single-phase immersion cooling, and two-phase immersion cooling techniques were applied to a 60-stage subnanosecond pulse generator. The experimental results indicate that the two-phase immersion cooling technique can effectively control the temperature rising of the avalanche transistor and, thus, reduce the time base jitter and voltage amplitude jitter. Five types of dielectric fluid with different boiling temperatures were comparatively studied. The FC-72 was finally adopted for the balanced performance on voltage amplitude and repetition rate. The two-phase immersion cooling technique could reduce the thermal resistance between the case and ambient and increase the maximum power from 330 to 876 mW. With this cooling method, the surface temperature of the transistor can be effectively controlled below 62 °C. The pulse generator could achieve outstanding performance with a voltage of 2350 V and a rise time of 180 ps. It can work stably at 200 kHz for more than 30 min, and the burst repetition rate could be 260 kHz within 1 min. This article offers new perspectives in the design of high repetitive avalanche transistorized subnanosecond generators. [ABSTRACT FROM AUTHOR]

This study explores the precursors of employees' safety behaviors based on a dual-process model, which suggests that human behaviors are determined by both controlled and automatic cognitive processes. Employees' responses to a self-reported survey on safety attitudes capture their controlled cognitive process, while the automatic association concerning safety measured by an Implicit Association Test (IAT) reflects employees' automatic cognitive processes about safety. In addition, this study investigates the moderating effects of inhibition on the relationship between self-reported safety attitude and safety behavior, and that between automatic associations towards safety and safety behavior. The results suggest significant main effects of self-reported safety attitude and automatic association on safety behaviors. Further, the interaction between self-reported safety attitude and inhibition and that between automatic association and inhibition each predict unique variances in safety behavior. Specifically, the safety behaviors of employees with lower level of inhibitory control are influenced more by automatic association, whereas those of employees with higher level of inhibitory control are guided more by self-reported safety attitudes. These results suggest that safety behavior is the joint outcome of both controlled and automatic cognitive processes, and the relative importance of these cognitive processes depends on employees' individual differences in inhibitory control. The implications of these findings for theoretical and practical issues are discussed at the end. [ABSTRACT FROM AUTHOR]

Clarifying the trigger characteristics of pseudospark switch triggered by laser (backlight thyratron, BLT) is crucial for optimizing the trigger performance under different conditions. This paper investigates the electron and ion emission characteristics of metal irradiated by nanosecond focused laser, and tests the trigger characteristics of BLT triggered from the back of the cathode (CBLT) and the back of anode (ABLT) with different targets (Mg, Ti, Cu, Mo, W), and discusses the trigger mechanism. The trigger characteristics of CBLT depends on the emission of prompt electrons e 1 and the expansion of ultrafast electrons e 2. When the laser energy ε is less than 0.3 mJ, there will be no e 1 emission, and low-density metals (e.g. Mg and Ti) are prone to ablation, resulting in large e 2 amplitude and short trigger delay t d. Due to the slow speed of e 2 , t d of CBLT has an exponential relationship with the laser irradiation position. When ε is increased to above 1 mJ, different metals can be fully heated, and the emission of e 1 will be enhanced and play a major role in trigger. In this case, metals with high melting and boiling points will produce more e 1 , so the trigger performance of Mg is the worst and W is the best. Due to the fast speed of e 1 , the sensitivity of t d of CBLT triggered by e 1 to the laser irradiation position is low, and the trigger lifetime can be improved by fine-tuning the laser irradiation position. The trigger of ABLT depends on the expansion of fast ions i 2 , and heavy metal ions diffuse easily in the background gas, so the laser irradiation area where ABLT can be stably triggered is larger, and the corresponding trigger performance of ABLT is better. • Laser ablation of metals produces different charged particles emissions. • The charged particles emission process is related to laser energy. • Different charged particles determine the different trigger characteristics. • Different polarity switches rely on different charged particles. [ABSTRACT FROM AUTHOR]

The on-site measurement of transient voltages is of great significance in analyzing the fault cause of power systems and optimizing the insulation coordination of power equipment. Conventional voltage transformers normally have a narrow bandwidth and are unable to accurately measure various transient voltages in power systems. In this paper, a wideband parallel resistive–capacitive voltage divider is developed, which can be used for online monitoring of transient voltages in a 220 kV power grid. The structures of the high-voltage and low-voltage arms were designed. The internal electric field distribution of the high-voltage arm was analyzed. The influence factors and improvement techniques of the upper frequency limit were studied. The parameters of the elements of the divider were determined. The voltage withstand performances and scale factors under lightning impulses and AC and DC voltages, the temperature stabilities of scale factors and the step response and bandwidth of the developed voltage divider were tested. The results show that the deviations of the scale factors under various voltage waveforms and different temperatures ranging from −20 to 40 °C are within 3%. The withstand voltage meets the relevant requirements specified in IEC60071-1-2011. The step response 10~90% rise time is approximately 29 ns, and the 3 dB bandwidth covers the range of DC to 10 MHz. [ABSTRACT FROM AUTHOR]

The wall-less Hall thruster is expected to overcome the issue of wall erosion in miniaturized Hall thrusters. A unique structure of negative gradient magnetic field is used to constrain the plasma behavior. In this paper, permanent magnet rings with different thicknesses were used to adjust the magnetic field strength, and its effect on discharge characteristics and thrust performance was experimentally investigated. The experiment results show that increasing the magnetic field strength can reduce the current oscillation and increase the maximum operating voltage. Within a limited range, increasing the magnetic field strength can significantly improve thrust performance. However, excessive magnetic field strength leads to a decrease in anode efficiency. The optimal magnetic field strength appears at 121 mT, with a thrust of 5.5 mN, a specific impulse of 935 s, a thrust power ratio of 51 mN/kW, and an anode efficiency of 23.1 %. Based on the analysis of different efficiency parameters and plume images, under excessively high magnetic field strength, the shortening of the ionization region may lead to intensified leakage of neutral atoms, which may be the primary reason for the reduction in propellant utilization and anode efficiency. • The effect of magnetic field strength on discharge characteristics and thrust performance was experimentally studied. • Increasing the magnetic field strength can suppress the anode current oscillation and enhance the maximum operating voltage. • There is an optimal magnetic field strength to maximize the thrust performance. • The reduced propellant utilization under high magnetic field strength is the main reason for the decrease in performance. [ABSTRACT FROM AUTHOR]

Pseudospark discharge is a special low pressure discharge and has been widely used in the gas switch and electron beam sources. From experiments, when the work pressure is relatively low, the electron beam current or loop current generated by a pseudospark discharge usually has two or more peaks, which has not been fully explained. In this paper, a single-gap pseudospark discharge model is established using 2D kinetic plasma simulation code VSim to study this phenomenon. According to the simulation results, when the anode voltage is 20 kV and the helium pressure is 100 Pa, the current has two peaks, which is similar to the experimental results, accompanied by the stepwise penetration of the virtual anode. This is mainly related to the formation and disappearance of the potential barrier in the cathode hole region. The formation of the potential barrier is caused by the consumption of ions at the cathode hole, and the disappearance is caused by the increase in electrons in the cathode cavity. By classifying the electrons, it is found that the increased electrons are generated by secondary emission caused by ion bombardment on the wall of the cathode. The simulation results also show that the stepwise penetration of the virtual anode can be suppressed or eliminated by increasing the working gas pressure, the secondary electron yield of the cathode material, or the trigger intensity. [ABSTRACT FROM AUTHOR]

The avalanche transistor-based Marx circuit has great advantages in generating high-voltage nanosecond pulses. The introduction of auxiliary triggering topology (ATT) can reduce the damage probability of transistors in M × N-stage Marx bank circuits (MBCs). However, as the number of modified stages increases, the output voltage drops significantly, which makes it not achievable to adopt ATT at each stage. The transistors in nonmodified stages still have a certain failure rate when operating at a high repetition rate. Moreover, the previous ATT is only applicable in the negative polarity MBC. In this article, an improved ATT is proposed to solve the above problems. First, its operating principle is analyzed, and the feasibility of its application in both negative and positive MBCs is verified by simulations. Then, the effects of the improved ATT on M × N-stage MBCs are experimentally studied, and the results show that the improved ATT can be used in all stages of MBC without reducing the output voltage. It can also reduce the minimum operating voltage of transistors and widen the regulating range of output voltage. In addition, it can improve the synchronous conduction of parallel-connected transistors. Finally, two nanosecond pulse generators with positive and negative polarity, respectively, are developed and used to drive the atmospheric pressure plasma jet. The amplitude of output voltage can be adjusted in the range of 5–10 kV, measuring at the open end of a coaxial cable with 75 Ω impedance, and the maximum repetition rate is up to 7 kHz. [ABSTRACT FROM AUTHOR]

Abstract: The aglycon, or so-called ‘warhead’ portion, of several potent 10-membered ring enediyne antitumor antibiotics contain dienonecarbamate and enediyne chromophores in an unusual bicyclic ring structure in which these two subunits are essentially orthogonal to each other. The circular dichroism (CD) spectra of the calicheamicin, esperamicin, and shisijimicin A families, all of which contain this bicyclic ring system, exhibit a characteristic negative exciton coupled CD at about 310 and 270nm. This signature CD feature suggested the absolute stereochemical relationship between these chromophores as originally assigned and which was later confirmed by stereospecific total synthesis. Because of the unique nature of this chromophoric interaction and the importance of using this CD spectral feature in the assignment of the absolute stereochemistry of other related enediynes, we report here simulations of the CD spectra of the calicheamicin aglycon A, and of two other truncated models, B and C, by using density functional theory (DFT) and the DeVoe coupled oscillator approach. The DFT calculations provide a strong theoretical basis that the planar enediyne chromophore alone gives a negligible CD contribution, while that coming from the twisted dienonecarbamate is much more substantial. However, the shape and the largest part of the intensity of experimental CD spectrum can only be reproduced when the two unsaturated moieties are simultaneously present. Thus, the exciton coupling between the two chromophores provides the most important contribution to the experimental CD spectrum of calicheamicin. This conclusion is in full agreement with the results from the DeVoe calculation. [Copyright &y& Elsevier]

The physical image of breakdown dynamics inside striations is depicted. High-speed photography along with electrophysical and spectral diagnostics reveals three modes for plasma development in Cu wire explosion: current cutoff, initial breakdown (with quenching), and main breakdown (with re-strike). The growth of spatial heterogeneity by electrothermal instability (ETI) provides a stratified structure before the initial breakdown. The characteristic wavelength of the strata is <100 μm for thinner wires (d = 90/130 μm) but in mm level for thicker ones (d = 240/290 μm). By increasing the stored energy from 200 to 220 J, the 290-μm-diameter Cu wire experiences a transition from current cutoff to initial breakdown, with a deposited energy of 2.64 and 3.10 eV/atom. Although the energy is not sufficient to vaporize the wire, axial micro-plasma-channels develop among bright layers (higher temperature but lower density), forming a crossed low-conductive "plasma-network" connecting two electrodes. If the residual energy is enough, the scenario (main breakdown) would be similar to "streamer-spark transition" and enhance the expansion of discharge channel. Two paralleled wires are exploded simultaneously but only one establishes main breakdown; therein, three stronger shock waves are detected, namely, two for vaporization and one for breakdown. [ABSTRACT FROM AUTHOR]

All-solid-state linear transformer drivers (LTDs) are widely used in high-voltage repetitive nanosecond-pulsed generators, and only a few LTD generators can output bipolar rectangular waves currently. Furthermore, owing to the large reverse overshoot when the output pulse width is long, fewer LTD generators can achieve a rectangular wave output with a microsecond pulse width. In this study, a bipolar LTD circuit topology based on a push–pull circuit is proposed for irreversible electroporation. In this topology, a single-stage LTD module has four push–pull branches in its primary winding to achieve a bipolar output and a short-circuited winding with two resistor–capacitor–diode snubbers to suppress forward/reverse overshoot. A single-stage LTD module and a 12-stage LTD have been tested, and the results show that they can output bipolar rectangular pulses with variable parameters. When the output pulse width is 100 ns to 1 µs, the maximum output voltage amplitude is 5.74 kV, the rise time is 29.1 ns, and the reverse overshoot at 1 µs is 2.9%. When the output pulse width is 1–8 µs, the maximum output voltage amplitude is 2.93 kV, the rise time is 24.3 ns, and the reverse overshoot at 8 µs is 11.3%. [ABSTRACT FROM AUTHOR]

Avalanche transistor (AT)-based repetitive nanosecond pulse generators with high amplitude, fast rise time, narrow pulse width, and low jitter have been widely developed and applied in numerous fields. However, relatively little research has been carried out on the positive nanosecond pulse generation with high flexibility in a wide range of output voltage amplitude. In this article, a novel AT-based Marx circuit (MC) topology adopting base-triggering method is proposed to avoid the formation of current filamentation inside the transistors and resolve the contradiction between high-voltage output and high repetition rate operation. A $6\times 10$ -stage MC prototype is implemented with optimized parameters to validate the feasibility of the proposed topology. The conduction processes of transistors show that, with the injection of additional base current, the switched-ON modes are transformed, which contributes to reliable conduction of transistors even without sufficient overvoltage ramp. With the adoption of inner triggering loops, the minimum working voltage of the prototype is extended to 1150 V. The operation characteristics of the generator in the whole operation range are investigated in depth. Experimental results illustrate that, at the 75- $\Omega $ match-ended coaxial cable, the prototype is capable of generating positive pulses with an adjustable voltage amplitude in the range of 6.50 to 12.39 kV, a basically consistent rise time of 3.6 ns and pulse width of 19.5 ns. Over 107 successive pulses are generated at a maximum repetition rate of 1 kHz without any device failure. [ABSTRACT FROM AUTHOR]

Low-temperature plasma technology is widely used in various industrial fields, which require the plasma to be of large volume, diffuse, and stable. Furthermore, previous studies have shown that better plasma performance has been obtained by using generators with a high voltage, a high repetition rate, a fast rise time, and a short pulse duration. In this paper, a novel topology is proposed for such generators, which is based on magnetic switches and diode opening switches. A prototype is developed, and its output characteristics are investigated by varying essential parameters, such as the load resistance and the power supply voltage. The experimental results show that it can generate pulses with a voltage of 30.6 kV, a rise time of 7.1 ns, a pulse duration of 8.2 ns, and a maximum repetition rate of 12 kHz on a 300 Ω resistive load. The prototype has been successfully used to drive uniform plasma in ambient air. In the proposed topology, a diode is added to make the magnetic cores independent of each other, significantly simplifying the design calculation. It may help develop nanosecond solid-state generators. [ABSTRACT FROM AUTHOR]

Trigger injection and its influence on performances of a single-gap pseudospark switch were studied by using a high-dielectric trigger unit and two types of pulse generators, where pulse parameters, polarity effect, anode voltage, and electrode geometries were varied. It is found that pulses with the rising edge of nanosecond scale can cause diffused electron emission in a large region of the trigger unit, while the slower pulses result in a localized surface flashover. The trigger injection is strongly polarity-dependent, and the way of applying the negative pulse voltage to the outer electrode is more favorable. Not all injected electrons can contribute to the triggering process, and the only factors that can lead to higher charge quantity and energetic components of electrons with a short injection delay are helpful to reduce the trigger delay. A model considering the potential penetration is presented to explain the influence of trigger injection, anode voltage, and electrode geometries. When trigger injection is strong enough or the ratio of cathode hole diameter to its thickness is relatively large, the trigger delay remains constant at different anode voltage; otherwise, it decreases as the anode voltage increases. [ABSTRACT FROM AUTHOR]

In this paper, a 60-stage Marx circuit with the two-phase immersion cooling technique is presented. The performance parameters of the pulse generator with phase change immersion cooling and forced air cooling are compared. The results show that the maximum repetition rate is increased from 80 to 260 kHz, the pulse drift is significantly reduced from 900 to 200 ps, and the temperature rise of transistors is controlled effectively to enhance the stability of the amplitude. We also studied the influence of temperature on the turn-on and turn-off processes of the transistors to show the importance of heat management under high repetition conditions. Finally, a pulse generator is developed with the repetition rate of 200 kHz, the rise time of 180 ps, and the amplitude of 2350 V on a matched 50 Ω resistive load, which can work for more than 30 min. [ABSTRACT FROM AUTHOR]

Avalanche transistor Marx bank circuits (MBCs) are widely used in high voltage repetitive nanosecond pulse generators, but problems exist with respect to increasing the output voltage due to the limited pulsed current. Accordingly, a novel topology based on an avalanche transistor MBC combined with a linear transformer driver is proposed, the latter of which exhibits advantageous stress distribution and modular structure. A four-module prototype with four units in each module is developed in the laboratory. The output characteristics are investigated by varying important parameters such as the main capacitance, the number of conducting units, the number of cascaded modules, and the trigger signal time delay. The test results verify the validity of the proposed topology. For a 50 Ω resistive load, the prototype can generate pulses with an amplitude of 10.9 kV, a rise time of 3.3 ns, and a voltage superposition efficiency of 89%. The topology proposed in this paper may help to provide a method to further improve the output performance of avalanche transistor MBCs. [ABSTRACT FROM AUTHOR]

Microcystin-leucine-arginine (MC-LR) is widespread in the water and food, which has suspected to be associated with adverse pregnancy outcomes. In the present study, we aim to assess the interaction between MC-LR exposure and preeclampsia development and elucidate the molecular events involved. After exposure to MC-LR during pregnancy, the mice developed hypertension and proteinuria, the typical symptoms of preeclampsia. This was associated with decreased invasiveness of placental trophoblast and vascular dysplasia caused by MC-LR through down-regulating VEGFA and TGF-β expression via AKT/m-TOR/HIF-1α pathway. In addition, this conclusion has been confirmed in a case-control study. Significantly, the addition of Deferoxamine (DFM), a phosphorylated serine-threonine protein kinases (p-AKT) specific agonist, can antagonize the inhibitory effect of MC-LR on the expression of related proteins, which further ameliorate the migration and invasion ability of HTR-8/Svneo cells. To sum up, our study revealed the pathologic mechanism by which MC-LR lead to preeclampsia and emphasized the importance of pregnancy management. [Display omitted] • MC-LR exposure induced preeclampsia-like changes such as hypertension and proteinuria in pregnant mice. • MC-LR inhibiting placental trophoblast invasion and angiogenesis. • MC-LR reduced the expression of TGF-β and VEGFA in mice placenta, HTR-8/Svneo cells and patients with preeclampsia. [ABSTRACT FROM AUTHOR]

Avalanche transistor-based Marx bank circuit (MBC) is widely used to generate nanosecond pulses with high amplitude, high repetition rate, fast rise time, and low jitter. Recently, the problem that avalanche transistors in the first several stages of $M \times N$ -stage MBC fail frequently has been alleviated by adopting auxiliary triggering topology (ATT). However, the reasons for improvement and the optimal design method have not been fully understood. In this article, a flexible $4\,\,\times10$ -stage MBC is developed to further investigate the output characteristics under different modified stages, capacitors, and loads through both experiments and simulations. The results show that on the one hand, adopting ATT will cause energy loss of the main capacitors to auxiliary triggering capacitors, which can decrease the output voltage; and on the other hand, transistors operating in the auxiliary triggering switching-ON mode have lower residual voltage than in the lower overvoltage switching-ON mode, which can increase the output voltage. This implies that there exists an optimal value of modified stages, which is 5 for the $4\,\,\times10$ -stage MBC. Besides, by adopting ATT, the waveform of output pulse changes, and the rising edge becomes faster. Finally, a repetitive nanosecond pulse generator is developed based on the optimized parameters, which can produce pulses with an amplitude of 9.04 kV, a rise time of 3.4 ns, a pulse width of 18.8 ns, and a maximum repetition rate of 1 kHz at the 75- $\Omega $ open-ended cable. Also, the feasibility of this modified MBC is validated by the preliminary experiments of driving atmospheric pressure plasma jet (APPJ). [ABSTRACT FROM AUTHOR]

This paper deals with an experimental study regarding the spatial–temporal evolution of single wire explosions in air and water at atmospheric pressure. Experiments were carried out with a microsecond timescale pulsed current source under 500 J stored energy. The morphology of the exploding wire with different discharge type, wire material, insulating coat, and ambient medium was intensively observed via self-emission images. The results revealed that the plasma radiation of wire explosion in air mainly contained two stages: initial intense radiation from optically thick plasma, and later decaying radiation from expanded arc-like plasma. A hollow structure was observed in a Cu exploding wire in air, and the plasma channel tended to develop inside it. As for W case, there would always be a core-corona structure, resulting in lower expansion rate and shock wave strength. Moreover, the plasma radiation of the underwater wire explosion was mainly determined by two factors: expansion rate and chemical reaction. The expansion rate of the radiant region in water was only 10–1 mm μs–1 level (1 mm μs–1 level for air), leading to the lagging radiation. No noticeable difference in morphology was found between Cu and W wire explosions in water. Particularly, the Al wire explosion generated a bright light emission due to chemical reactions. Finally, radiative characteristics in an exploding wire were preliminarily concluded and existing problems proposed. [ABSTRACT FROM AUTHOR]

According to statistics, solid product formed by the reaction between SF6 gas and metal electrodes at the connecting joint of ultra-high-voltage direct current (UHVDC) wall bushing is likely to adhere to the surface of insulating materials, which may seriously threaten the insulation of the bushing. Thus, studying the effect of the solid products on DC surface flash-over voltage is of great significance for evaluating the internal insulation of UHVDC wall bushing. The electrical parameters of the solid products were measured and compared with those of epoxy-impregnated composite insulating materials. The comparison result shows that there is a significant difference between them, which demonstrate that the solid products may have an impact on the DC flash-over voltage of epoxy-impregnated composite insulating materials. Furthermore, by means of the DC surface flash-over platform, the characteristic of the surface flash-over voltage of the epoxy-impregnated composite insulating materials with the solid products attached directly is analyzed. It is found that the decrease in the surface flash-over voltage is closely related to the type of solid product, gas pressure, distance between electrodes, way of attachment, etc. [ABSTRACT FROM AUTHOR]

This paper deals with an experimental study of a copper wire explosion in air and water at atmospheric pressure. The influence of the stored energy, discharge type, ambient medium on the electrical and optical characteristics of a single wire explosion was examined and clarified. Particularly, optical emission spectroscopy as well as self-emission image diagnosis were conducted to understand the radiant and quenching process of the explosion. The results revealed that the radiation mainly contained two stages: a white light (continuous spectrum) flash soon after the moment of explosion, and a long period of line radiation of Cu ions/atoms in the following dozens of microseconds. By analysing characteristic lines, Cu2+ was found in the very early stage of the expansion of the discharge channel (DC). Besides, obvious line radiation of O and N ions/atoms was found when there existed a current pause. As for plasma parameters, the Boltzmann plot method indicated that the average temperature of explosion products was ∼1 eV, while the electron density experienced an apparent attenuation as the expansion of DC. In addition to this, the optical emission in air and water followed two distinctly different patterns, relating to the expansion of DC and diffusion of the ambient medium. [ABSTRACT FROM AUTHOR]

This paper investigates the external circuit effect in corona discharge by means of numerical simulation, while the effect is usually disregarded in previous plasma simulations. A general numerical solution method of serial external circuit, which can compute surface charges on any shape of electrodes adaptively and solve electrode potential and circuit current simultaneously, is developed to support the investigation, due to lack of theoretical solution in irregular electrode systems. Brief description and validation of the scheme are presented in section 2. In general, the accuracy of numerical solution improves with mesh refinement in orthogonal mesh, due to stair step approximation. Simulations are performed in our self-developed 3D PIC-MCC (particle-in-cell, Monte Carlo collision) code with photoionization and external circuit. The simulation model including recently developed photoionization model is described briefly in section 3. Then the simulation results in a needle-plate electrode in air, such as spatiotemporal evolution of corona discharge and waveforms of electrode voltage and circuit current, are presented. Physical mechanisms of formation of branched corona discharge and self-consistent adjustment of electrode voltage and circuit current are discussed. The waveforms of voltage and current in this simulation are generally consistent with experimental result. The external circuit has negative feedback effect on the discharge, and can adjusts electrode voltage self-consistently. The application of external circuit improves the applicability of particle simulation method to the simulation of discharge phenomenon in actual devices. [ABSTRACT FROM AUTHOR]

An induction voltage adder (IVA) has been developed to drive rod-pinch diodes (RPDs), to produce X-rays for flash radiography. The IVA facility consists of four-stage induction cavities stacked in series, each of which is single-point driven by a 6- $\Omega $ pulseline. The prime pulsed-power source comprises two Marx generators and four de-ionized water pulselines. Each Marx generator fast charges two pulselines to about 2.2 MV in less than 370 ns. Four electrically triggered, SF6-insulated gas switches serve as energy-transfer switches from pulse-forming lines to output transmission lines, and thus without an additional intermediate energy storage. A stepped inner stalk is utilized to make the vacuum impedance of the secondary transmission line increase from $30~\Omega $ at the first cavity to $120~\Omega $ at the last cavity, to prevent the electron emission from cathode surfaces. The RPD is chosen to create bremsstrahlung X-rays, which are believed to be optimal at voltage levels of about 4 MV. In this article, the design details and experimental results concerning the main components, such as the Marx/PFLs, IVA, and RPD, are demonstrated. The electrical performances of the facility are characterized. Presently, the IVA provides voltages of up to 4.3 MV and currents of up to 85 kA. The X-ray dose is up to 15.5 Rad [lithium fluoride (LiF)] at 1 m with a spot size of 1.4 mm and a FWHM time of 55 ns. [ABSTRACT FROM AUTHOR]

8-oxoguanine (8-oxoG) is one of the most prevalent genotoxic lesions, and it is generated in DNA attacked by reactive oxygen species (ROS). Adenine misincorporated opposite to 8-oxoG during replication is excised by MutY homolog (MUTYH), an important protein of the base excision repair (BER) system. Mutyh plays an important role in the maintenance of genomic integrity, but the functional consequences of Mutyh deficiency are not fully understood. In the current study, we investigated the histological and functional changes of five tissues (hippocampus, heart, liver, kidney and lung) and their molecular basis in Mutyh −/− and wild-type mice exposed to D -galactose (D -gal). Our data indicated that Mutyh deficiency hindered the weight gain of experimental mice and induced substantial alterations of 8-oxoG content and superoxide dismutase (SOD) activity, but no significant histological and functional impairment appeared in the investigated tissues of Mutyh- deficient mice without D -gal exposure. Under low-dose D -gal exposure, Mutyh deficiency altered expression of genes involved in mitochondrial unfolded protein response (UPRmt) in the heart, liver and lung, and caused an enhanced expression of mitochondrial dynamics proteins (MDPs) in hippocampus and liver. The stress responses could maintain mitochondrial proteostasis and function. However, such responses were not noted when experiencing excessive damage burden induced by high-dose D -gal exposure, in which Mutyh deficiency increased accumulation of 8-oxoG and aggravated mitonuclear protein imbalance, as well as histological lesions in heart, liver and kidney. A higher sensitivity to ROS-induced cardiotoxicity with high-dose D -gal exposure was noticed in Mutyh −/− mice. However, no differences in learning and memory impairments were observed between Mutyh −/− and wild-type mice with high-dose D -gal exposure. In conclusion, our data demonstrated that Mutyh deficiency has different impacts on various tissues based on the degree of oxidative stress. Image 1 • Impact associated with Mutyh deficiency in oxidative stress is tissue-dependent. • Mutyh deficiency causes an increase of 8-oxoG content in most investigated tissues. • The aggravated lesions associated with Mutyh deficiency appeared in severe stress. • Less histological damage associated with Mutyh deficiency was observed in the lungs. [ABSTRACT FROM AUTHOR]

Plenty of solid products will be produced when the arc discharge fault occurs in SF6 gas-insulated electrical equipment, which will extremely threaten the internal insulation properties of the equipment. Therefore, it is necessary to carry out research on the solid products formed by the reaction of SF6 with metal electrode under electric arc, aiming to study their effect on the operation of the equipment. First of all, the formation characteristics of the solid products with different metal electrodes and different pressures are studied. Then, the composition of the solid products is determined. Besides, the quantitative relationship between the mass of the solid products and the discharge energy is analyzed as well. [ABSTRACT FROM AUTHOR]

The external discharge plasma thruster removes the annular channel of the traditional Hall thruster, allowing the ionization region to appear outside the thruster, which is expected to reduce the plasma-wall interaction and extend the thruster lifetime. Due to its simpler structure and lighter weight, the external discharge plasma thruster is expected to be scaled down to lower power levels. In this work, the effect of radial scaling down on the performance of low-power external discharge plasma thrusters was experimentally investigated by comparing the discharge characteristics, thrust performance, beam characteristics, and spectral characteristics of thrusters with two different anode diameters of 15 and 30 mm. The 30 mm thruster has thrust of 78–235 mN, specific impulse of 566–1071 s, and anode efficiency of 11.8–23.4% at 78–235 W anode power. Compared with the 30 mm thruster, the anode power and thrust of the 15 mm thruster were decreased by approximately half. Plume diagnostic results show that the 15 mm thruster had a higher current utilization, higher ion peak energy and more active ionization due to better electron confinement. However, the propellant utilization of the 15 mm thruster was lower because of the shortened ionization region length. • The manuscript's highlights are as follows: • The performance of external discharge plasma thrusters with anode diameters of 15 and 30 mm were experimentally compared. • The 15 mm thruster had a higher current utilization, higher ion peak energy and more active ionization. • The shortened ionization region length leads to a lower propellant utilization. • The external discharge plasma thruster has an advantage in thrust density. [ABSTRACT FROM AUTHOR]

Lateral flow assays (LFAs) are promising points-of-care tests, playing a vital role in diseases screening, diagnosis and surveillance. However, development of portable, cheap, and smart LFAs platform for sensitive and accurate quantification of disease biomarkers in complex media is challenging. Here, a cheap handheld device was developed to realize on-site detection of disease biomarkers by Nd3+/Yb3+ co-doped near-infrared (NIR)-to-NIR downconversion nanoparticles (DCNPs) based LFA. Its sensitivity is at least 8-fold higher for detecting NIR light signal from Nd3+/Yb3+ co-doped nanoparticles than conventional expensive InGaAs camera based detection platform. Additionally, we enhance NIR quantum yield of Nd3+/Yb3+ co-doped nanoparticles up to 35.5% via simultaneous high dopant of sensitizer ions Nd3+ and emitter ions Yb3+. Combination of NIR-to-NIR handheld detection device and ultra-bright NIR emitting NaNbF 4 :Yb60%@NaLuF 4 nanoparticle probe allows the detection sensitivity of SARS-CoV-2 ancestral strain and Omicron variants specific neutralizing antibodies LFA up to the level of commercial enzyme linked immunosorbent assay kit. Furthermore, by this robust method, enhanced neutralizing antibodies against SARS-CoV-2 ancestral strain and Omicron variants are observed in healthy participants with Ad5-nCoV booster on top of two doses of inactivated vaccine. This NIR-to-NIR handheld platform provides a promising strategy for on-site evaluating protective humoral immunity after SARS-CoV-2 vaccination or infection. [ABSTRACT FROM AUTHOR]

By triggering the switches in sequence and controlling the brick charging voltage independently, a pulsed power system can generate flexible current waveform in the load, which could allow high-accurate magnetic pressure in experimental materials in the study of EOS data and dynamic response of material characterization. Currently, a 1.5-MA driver with 20 independent bricks has been developed, and a programmable 256-brick parallel discharge driver which is able to generate shaped current greater than 6.5 MA is under construction in the China Academy of Engineering Physics. In this paper, for these two multibrick parallel discharge drivers, the method of optimizing the output current waveform of the driver is studied by using the genetic algorithm and the corresponding optimization results of different target current waveforms are obtained. An experimental platform is set up for studying the gas switch breakdown characteristics. The self-breakdown and triggering breakdown experiments of the switch are conducted, and its breakdown characteristics are researched. Meanwhile, the effect of breakdown delay and jitter on the output current waveform is studied by simulation. This paper is of great significance to the actual operation of the multibrick parallel discharge drivers. [ABSTRACT FROM AUTHOR]

Highlights • Reliable detection and quantification of myoglobin in blood plasma is realized through an upconversion nanoparticles based lateral flow assay. • The assay is able to reach a limit of detection as low as 0.21 ng/mL, a linear range of 10–400 ng/mL, and a detection time within 10 min. • The assay is commensurate with the clinically used Abbott Chemiluminescence system on Mb concentration evaluation in human blood plasmas. Abstract Reliable detection and quantification of myoglobin (Mb) in blood plasma is of significance for clinical diagnosis and management of acute myocardial infarction (AMI). Here, we describe a homemade platform combining efficient core-shell upconversion nanoparticles (UCNPs) and lateral flow assay (LFA) for ultrasensitive and specific fluorescence ratiometric evaluation of Mb in clinical blood samples. After a systematic optimization, this platform was able to reach a limit of detection as low as 0.21 ng/ml, a linear range of 0.5–400 ng/ml, a recovery rate of 90.6–110.5%, an inter-assay coefficient of variation (CV) of 3.0–6.2%, an intra-assay CV of 8.8–13.6%, and a detection time of 10 min. Furthermore, the acquired concentration results were unresponsive to the interference of high-bilirubin, high-lipids, and hemolysis, and a range of other biomarkers (CRP, PCT, and BSA), substantiating robust Mb-specific detection. Importantly, the platform showed a significant linear correlation (R2 = 0.9484) with clinically used Abbott Chemiluminescence detection system (CLDS) on evaluation of Mb concentration in 50 clinical human blood plasmas. The achievement of rapid, sensitive and reliable quantification of Mb in clinical plasma promises the prevalent use of the described platform for on-field diagnosis or rule-out of AMI in clinical practice. [ABSTRACT FROM AUTHOR]

Isentropic compression experiments (ICEs) are an important method to study the dynamic characteristics of materials at pressures, temperatures, and stress or strain rate not attainable in conventional shock experiments. Yet it makes high demands toward the precise current pulse tailoring capability of the source. The China Academy of Engineering Physics is now developing a 20-brick parallel discharge driver and a 256-brick parallel discharge driver (CQ-7) to improve the performance and flexibility of compact magnetic compression devices. The load current of ICEs is tailored by optimizing the switch trigger sequence and the brick charging voltage. This paper establishes the equivalent circuit model of the 20-brick parallel discharge driver, taking the distributed inductance, resistance, and capacitance of transmission plates into account based on the partial-element equivalent circuit method. Besides, the equivalent circuit model of discharge brick based on the switch arc resistance model is also established to study the influence of key structural parameters on the output current. Furthermore, by comparing the simulation and experimental results of simultaneous discharge of 20-brick driver, the accuracy of simulation model is confirmed. This paper is of great significance to the design and optimization of multibrick parallel discharge drivers. [ABSTRACT FROM AUTHOR]

A pair of W–Ni–Fe and W–Cu electrodes were tested under 100 kA level pulsed currents for 10 000 shots, respectively. Surface roughness and morphology characteristics of the two pairs of electrodes were obtained and compared. Experimental results indicated cracks divided the W–Cu electrode surface to polygons while the W–Ni–Fe electrode surface remained as a whole with pits and protrusions. Accordingly, the surface roughness of W–Ni–Fe electrodes increased to ∼3 μm while that of W–Cu electrodes reached ∼7 μm at the end of the test. The results reveal that the W–Ni–Fe alloy has a better erosion resistance and potential to be further applied in spark gaps. [ABSTRACT FROM AUTHOR]

This paper presents the design and development of a trigger with a high repetition rate, low jitter, and compact structure for the pseudospark switch (PSS), which includes an improved Marx generator based on avalanche transistors and a corona-plasma trigger unit. The generator adopted a novel 3 × 12-stage Marx circuit based on avalanche transistors in which the failure rate of transistors in the first and second stages was significantly reduced by connecting the parallel capacitors compared to the previous similar generator. The reason for the improved performance was also discussed. The main parameters of output pulses were an amplitude of −7 kV, rise time of 6 ns, jitter of 0.2 ns, and repetition rate of 2 kHz. The corona-plasma trigger unit adopted BaTiO3 ceramics with high εr as the dielectric and was arranged in the hollow cathode of the PSS. The experiments of triggering a PSS prototype were conducted. The influence of anode voltage and pressure on the trigger delay and jitter was studied, and the minimum trigger jitter achieved <1 ns. This trigger worked for 107 shots at the repetition rate of 2 kHz continuously without obvious performance degradation and any failure of the generator. The main advantage of this trigger is the simultaneous combination of the high repetition rate, low jitter, long lifetime, and great simplicity in a compact structure. [ABSTRACT FROM AUTHOR]

Many diseases are believed to be driven by pathological levels of reactive oxygen species (ROS) and oxidative stress has long been recognized as a driver for inflammatory disorders. Apoptosis signal-regulating kinase 1 (ASK1) has been reported to be activated by intracellular ROS and its inhibition leads to a down regulation of p38-and JNK-dependent signaling. Consequently, ASK1 inhibitors may have the potential to treat clinically important inflammatory pathologies including renal, pulmonary and liver diseases. Analysis of the ASK1 ATP-binding site suggested that Gln756, an amino acid that rarely occurs at the GK+2 position, offered opportunities for achieving kinase selectivity for ASK1 which was applied to the design of a parallel medicinal chemistry library that afforded inhibitors of ASK1 with nanomolar potency and excellent kinome selectivity. A focused optimization strategy utilizing structure-based design resulted in the identification of ASK1 inhibitors with low nanomolar potency in a cellular assay, high selectivity when tested against kinase and broad pharmacology screening panels, and attractive physicochemical properties. The compounds we describe are attractive tool compounds to inform the therapeutic potential of ASK1 inhibition. [ABSTRACT FROM AUTHOR]

Astragaloside IV (ASIV) has effects of antioxidation and immunologic enhancement. However, there are few reports on the application and potential mechanism of ASIV in aquaculture. In this study, we investigated the effect of ASIV on growth, antioxidation, and immune function of tilapia. Tilapia were fed a diet containing 0.1, 0.2, and 0.5 g·kg−1 ASIV for 60 days, followed by an intrapleural injection of 50 mg·kg−1 cyclophosphamide (CTX) to induce oxidative damage and immunosuppression. Then tilapia were weighed and blood, liver, spleen, kidney, and intestinal were collected. The results showed ASIV increased the final weight, relative weight rate, and specific growth rate of tilapia, reduce conversion ratio, and reduced the morphological lesions of tissues. Meanwhile, ASIV alleviated CTX-induced oxidative damage by improving antioxidant activity in serum and tissues and inhibiting lipid peroxidation. Additionally, ASIV attenuated the immunosuppression of tilapia caused by CTX, regulated immunochemical indexes in serum, increased the viability of peripheral blood leukocytes and head kidney macrophages, and restored respiratory burst activity (O 2 −) in head kidney macrophages and splenocytes. Furthermore, q PCR data showed ASIV up-regulated antioxidant-related gene expression of nrf2 , ho-1 , gpx3 , and cat and immune-related gene expression including C3 and igm. In conclusion, ASIV as a feed additive can not only improve the growth performance but also enhance the antioxidant capacity and immune function of tilapia, which may be associated with the ability of ASIV to scavenge free radicals, reduce lipid peroxidation levels, and stabilize numbers of immune cells. [Display omitted] • CTX treatment inhibits antioxidant capacity and immunity of tipilia. • ASIV pretreatment promotes growth indexes of tilapia. • ASIV pretreatment can alleviate CTX-induced oxidative damage of tilapia. • ASIV pretreatment attenuats the immunosuppression of tilapia caused by CTX. [ABSTRACT FROM AUTHOR]

Microcystin-leucine-arginine (MC-LR) reduces the fertility of female mice, but the mechanism is unknown. We studied the effect of MC-LR on early pregnancy and elucidated its possible mechanism. The number of embryo beds and embryo volume decreased in pregnant mice at 6 or 8 days after fertilization after acute exposure to MC-LR. The corpus luteum secretes estrogen and progesterone, which are involved in embryo implantation and maintenance of early pregnancy. MC-LR exposure reduced luteal blood vessel branches and inhibited hormone synthesis. Functional blood vessels are essential to the maintenance of luteal structure and function. Reduced migration and tube-forming were also detected in human umbilical vascular endothelial cells (HUVECs) treated with MC-LR. MC-LR significantly decreased the expression of vascular endothelial growth factor receptor 2 (VEGFR2) in vivo and in vitro , which was responsible for the inhibited construction of the vascular network. The MEK/ERK/SP1 signal pathway mediated the decrease in VEGFR2 expression, and the agonists of phosphorylated extracellular regulated protein kinases (p-ERK) alleviated the anti-angiogenic effect of MC-LR. In conclusion, we demonstrated the toxicity of MC-LR on construction of vascular network in corpus luteum, which could provide a new perspective on female infertility or miscarriage caused by environmental factors. [Display omitted] • MC-LR induced embryo implantation disorder in pregnant mice. • Corpus luteal vascular network was impacted by MC-LR. • VEGFR2 expression was strongly down-regulated in ovarian of MC-LR treat mice and HUVECs. • MEK/ERK/SP1 signal pathway mediated the decrease in VEGFR2 expression in HUVECs. [ABSTRACT FROM AUTHOR]

In this paper, a torsional thrust balance with an asymmetrical arm is designed and tested which is effective for the microthruster performance evaluation in the vacuum facilities with limited space. An optimization design method for the key parameters of the thrust balance has been developed. By utilizing the asymmetrical arm, a great resolution can be obtained with a restrained arm length. A novel printed circuit board electrostatic comb has been applied to the thrust balance calibration. Experimental results show that the comb is capable of producing steady force in the range of about 30 μN–3300 μN and an impulse bit of 7 µNs–777 µNs which can be further extended to nano-Newton second range with a shorter pulse width and a lower voltage. The calibration results show that the thrust balance has a great repeatability and reliability. The total uncertainty of the thrust stand is estimated to be 3.33% in the 1 µNs range. [ABSTRACT FROM AUTHOR]

Background: To evaluate the potential effects of irreversible electroporation ablation on the Achilles tendon in a rabbit model and to compare the histopathological and biomechanical changes between specimens following electroporation ablation and radiofrequency ablation. Methods: A total of 140 six-month-old male New Zealand rabbits were used. The animals were randomly divided into two groups, 70 in the radiofrequency ablation group and 70 in the electroporation group. In situ ablations were applied directly to the Achilles tendons of rabbits using typical electroporation (1800 V/cm, 90 pulses) and radiofrequency ablation (power control mode) protocols. Histopathological and biomechanical evaluations were performed to examine the effects of electroporation ablation and radiofrequency ablation over time. Results: Both electroporation and radiofrequency ablation produced complete cell ablation in the target region. Thermal damage resulted in tendon rupture 3 days post radiofrequency ablation. In contrast, electroporation-ablated Achilles tendons preserved their biomechanical properties and showed no detectable rupture at this time point. The electroporation-ablated tendons exhibited signs of recovery, including tenoblast regeneration and angiogenesis within 2 weeks, and the restoration of their integral structure was evident within 12 weeks. Conclusions: When applying electroporation to ablate solid tumors, major advantage could be that collateral damage to adjacent tendons or ligaments is minimized due to the unique ability of electroporation ablation to target the cell membrane. This advantage could have a significant impact on the field of tumor ablation near vital tendons or ligaments. [ABSTRACT FROM AUTHOR]

Cyclophosphamide (CTX) is a common immunosuppressant, and it can also results in liver injury in human and animals. In this study, the CTX-induced liver injury mechanism in tilapia (Oreochromis niloticus) was investigated by studying alteration of endoplasmic reticulum stress (ERS), inflammation and anti-oxidative status. Tilapia was intraperitoneally injected CTX at the doses of 10, 25, 50, 75 and 100 mg·kg−1, and the blood and liver tissues were collected. The results showed that CTX administration had a significant cytotoxicity on hepatocytes, and increased the liver index. The extensive vacuolar degeneration, unclear cell outline and other histological lesions were also observed. CTX administration markedly decreased the antioxidant ability and enhanced lipid peroxidation in liver. Furthermore, qPCR data showed that CTX administration at 50–100 mg·kg−1 up-regulated gene expressions of cyp1a , cyp2k1 and cyp3a , and inflammatory response-related genes including rel , relb , nfκb1 , il-6 , il-8 , il-10 and tnf-α. CTX significantly promoted the mRNA levels of ERS-related genes (eif2α , crt , parp1 , grp78 , ire1 , xbp1s and chop) in a dose dependent manner. Additionally, CTX injection at 75–100 mg·kg−1 could down-regulate gene expressions of anti-oxidative status including nrf2 , ucp2 , ho-1 , gpx3 , gstα and cat. Overall results suggested CTX injection induced liver damage which was related to the cytotoxic effect on hepatocytes, decrease of antioxidant capacity, inflammatory response and ERS. [Display omitted] • CTX treatment induces hepatic injury in Nile tilapia. • CTX treatment inhibits antioxidant capacity. • CTX treatment stimulates inflammatory response. • CTX treatment promotes endoplasmic reticulum stress. [ABSTRACT FROM AUTHOR]

ITK (interleukin-2-inducible T-cell kinase) is a critical component of signal transduction in T-cells and has a well-validated role in their proliferation, cytokine release and chemotaxis. ITK is an attractive target for the treatment of T-cell-mediated inflammatory diseases. In the present study we describe the discovery of kinase inhibitors that preferentially bind to an allosteric pocket of ITK. The novel ITK allosteric site was characterized by NMR, surface plasmon resonance, isothermal titration calorimetry, enzymology and X-ray crystallography. Initial screening hits bound to both the allosteric pocket and the ATP site. Successful lead optimization was achieved by improving the contribution of the allosteric component to the overall inhibition. NMR competition experiments demonstrated that the dual-site binders showed higher affinity for the allosteric site compared with the ATP site. Moreover, an optimized inhibitor displayed noncompetitive inhibition with respect to ATP as shown by steadystate enzyme kinetics. The activity of the isolated kinase domain and auto-activation of the full-length enzyme were inhibited with similar potency. However, inhibition of the activated full-length enzyme was weaker, presumably because the allosteric site is altered when ITK becomes activated. An optimized lead showed exquisite kinome selectivity and is efficacious in human whole blood and proximal cell-based assays. [ABSTRACT FROM AUTHOR]