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Abstract LLC resonant converters are widely adopted in many different industrial applications due to their high efficiency operation. To further improve LLC resonant converters' efficiency, the secondary unregulated diode rectifier is replaced by the synchronous rectifier (SR). In many applications, LLC converter is designed to operate at resonant frequency to maximize the system efficiency and act as a DC transformer (DCX). The SR driving signal is set as the same as the primary driving signal to work in an open‐loop mode. However, the resonant frequency will deviate due to the tolerance, working environment, and ageing effect of circuit components, which will lead to the degradation of the system efficiency and output voltage variation. Unfortunately, most of the existing techniques cannot be simply adopted in SR LLC DCX. Therefore, an adaptive SR driving strategy that can compensate the circuit components' variations is necessary for SR LLC DCX. Inan adaptive SR strategy based on the constant voltage gain characteristic at resonant frequency point is proposed. The proposed strategy is applicable for all different scenarios with easy implementation and low cost.

Herein, a novel strategy for regulating the phase structure was used to significantly enhance the recoverable energy storage density (Wrec) and the thermal stability via designing the (1-x)[(Bi0.5Na0.5)0.7Sr0.3TiO3]-xBiScO3 ((1-x)BNST-xBS) relaxor ferroelectric ceramics. The incorporation of BS into BNST ceramics markedly increases the local micro-structure disorder, causing a high polarization and inhibiting polarization hysteresis for 0.95BNST-0.05BS ceramics, leading to a large Wrec of 5.41 J/cm3 with an ideal efficiency (η) of 78.5%. Meanwhile, transmission electron microscope (TEM) results further proved that the nano-domain structure and the tetragonal (P4bm) phase superlattice structure of 0.95BNST-0.05BS ceramics possess an excellent thermal stability (20–200 °C). An outstanding Wrec value of 3.18 × (1.00 ± 0.03) J/cm3 and an η value of 74.500 ± 0.025 are achieved under a temperature range from 20 °C to 200 °C. This work provides a promising method for phase-structure design that can make it possible to apply temperature-insensitive ceramic dielectrics with a high energy storage density in harsh environments.

Abstract Small‐signal modelling of modular multilevel converters (MMC) has drawn lots of attention recently. Existing research mainly studies MMC terminal impedances by injecting corresponding AC‐side and DC‐side external small‐signal perturbations. This paper focuses on the MMC internal small‐signal perturbations, that is, perturbations in control signal and their effect. There are two kinds, that is, differential‐mode and common‐mode, of internal small‐signal perturbations, which influence MMC external and internal state variables, respectively. Then, the existing MMC small‐signal model is improved. With its help, accurate MMC control‐signal to state‐variables transfer functions are established, which can aid precise MMC controller analysis and performance optimization. In this paper, an analysis of MMC phase capacitor voltage regulation control is demonstrated as an example. The stability can be precisely ascertained based on the obtained transfer function. The effect of parameter variation of the proportional‐integral controller is also studied. Moreover, an additional compensator is introduced in the existing control loop to attenuate resonance peaks in the transfer function, which mitigates the large voltage overshoot and makes the transient state much smoother. Simulation and experimental results support and well confirm the analysis of this paper.

Viscous slickwater has a higher viscosity and better sand-carrying ability than conventional slickwater at the same concentration. At a concentration of 0.4 wt.%, the viscosity of the viscous slickwater is 4.7 times that of the conventional slickwater. It is generally believed that viscosity is one of the main influencing factors on the sand-carrying ability of the fluid. However, this study has shown that the good sand-carrying ability of the viscous slickwater is more attributed to its viscoelasticity. Through rheology and sand-carrying tests, it has been found that the viscoelastic properties vary when fluids have the same viscosity; this then leads to a significant difference in the settling rate of sand and the sand-carrying threshold of the fluid in a fracture at a certain flow rate. The routine method of characterizing the viscoelastic property of the slickwater was to observe the cross point of the elastic modulus (G′) and viscous modulus (G″) curves. The smaller the frequency of the cross point, the better the viscoelastic property of the fluid. However, it has been found in experiments that even when the cross point is the same, there is still a significant difference in the sand-carrying ability of fluids. Therefore, sand-carrying experiments are conducted under a similar cross point and different magnitudes of modulus, of which the results indicate that as the elastic modulus increases, the settling rate of sand decreases. The flow rate threshold occurring as sand settles obtained from laboratory experiments is compared with the field condition during hydraulic fracturing. From laboratory experiments, the threshold of inner-fracture flow rate that prevents the sand settling is found to be 8.02 m/min for 0.6 wt.% viscous slickwater with a sand ratio of 30%. In the field operation, the operation conditions meet the sand-carrying threshold obtained from laboratory experiments. Observations from the field test confirm the applicability of the threshold plot proposed according to laboratory measurements, which can provide guidance for optimizing the fracturing scheme in the field.

Grid-forming inverters, which are represented by droop control and virtual synchronous generator control, have been widely studied and applied because of their excellent grid-supporting ability and smooth off-grid switching. When a grid-forming inverter is connected to a microgrid or utility grid, the control loops of active power and reactive power will be coupled because of the voltage phase difference, which will affect the power control performance. This paper first derives the small-signal linearized model of the system, based on which a frequency feedforward control and an amplitude feedforward control are proposed to decouple the active power and reactive power control loops, respectively. The proposed decoupling strategy directly modifies the reference values through feedforward with an easily implementable principle that is applicable to various control coordinate systems, control coordinate systems, and control structures. By comparing system models with and without the proposed decoupling strategy, its effectiveness can be theoretically proven. Time-domain simulations and hardware experiments are presented to further validate its effectiveness.

Environmentally friendly lead-free ceramics capacitors, with outstanding power density, rapid charging/discharging rate, and superior stability, have been receiving increasing attention of late for their ability to meet the critical requirements of pulsed power devices in low-consumption systems. However, the relatively low energy storage capability must be urgently overcome. Herein, this work reports on lead-free SrTi0.875Nb0.1O3 (STN) replacement of (Bi0.47La0.03Na0.5)0.94Ba0.06TiO3 (BLNBT) ferroelectric ceramics with excellent energy storage performance. Improving relaxor behaviour and breakdown strength (Eb), decreasing grain size, and mitigating large polarization difference are conductive to the enhancement of comprehensive energy storage performances. The phase-field simulation methods are further analysized evolution process of electrical tree in the experimental breakdown. In particular, the 0.70BLNBT-0.30STN ceramic exhibit a large discharged energy density of 4.2 J/cm3 with an efficiency of 89.3% at room temperature under electric field of 380 kV/cm. Additionally, for practical applications, the BLNBT-based ceramics achieve a high power density (∼62.3 MW/cm3) and fast discharged time (∼148.8 ns) over broad temperature range (20–200 °C). Therefore, this work can provide a simple and effective guideline paradigm for acquiring high-performance dielectric materials in low-consumption systems operating in a wide range of temperatures and long-term operations.

A single-phase voltage source inverter (VSI) still suffers from a long settling time and significant voltage overshoot/undershoot under the abrupt step-change of load current. This article analyzes the comprehensive large-signal dynamic process and limitation of the linear controller during step change in load current. The combination of linear and nonlinear control is presented which is a realistic, simple, and low-cost technique for enhancing the dynamic response of the single-phase VSI. A nonlinear controller based on the simplified capacitor charge balance algorithm is employed to drive the inductor current and capacitor voltage to attain the target value by precisely following the projected optimal trajectory during the transient process in a brief period. A linear PI controller is utilized during the steady-state operations such as input voltage variations, temperature drifts, and component ageing. The complete mathematical derivation as well as a design method is presented to guide the practical hardware implementation for the given main circuit parameters and identified load step change. Even though accurate time instants can be obtained using off-line numerical calculations, reasonable simplifications are provided for real-time practical engineering applications in DSP. Finally, simulation and experimental verifications prove that the single-phase VSI achieves a substantial settling time decrease and reduced voltage oscillations.

The hybrid droop and master-slave structure studied in existing work complements the advantages of droop control and master-slave control, at the cost of frequency and voltage deviations in microgrids. To eliminate these deviations and maintain accurate power sharing among distributed generators, this paper proposes a decentralized secondary control method based on mode switching, where the secondary controller switches among three modes. In the first mode, a feedback strategy is applied to maintain accurate power sharing among slave distributed generators, and then the load demand is estimated and redistributed among distributed generators to calculate new secondary control commands in the second mode, which are further updated in the third mode to eliminate frequency and point-of-common-coupling bus voltage deviations. The proposed method is communication-free and is able to eliminate the influence of triggering delay among slave distributed generators during the mode switching. The effectiveness of the proposed method is verified through hardware experiments.

Abstract To explore whether patients with unilateral idiopathic sudden sensorineural hearing loss (uISSNHL) have normal speech in noise (SIN) perception under different masking conditions after complete recovery of pure tone audiometry. Eight completely recovered uISSNHL patients were enrolled in ISSNHL group, while 8 normal-hearing adults matched with age, gender, and education experience were selected as the control group. Each group was tested SIN under four masking conditions, including noise and speech maskings with and without spatial separation cues. For both ISSNHL and control groups a two-way ANOVA showed a statistically significant effect of masking type (p = 0.007 vs p = 0.012). A significant effect of perceived spatial separation (p

As production and life require more and more high-end and precise power equipment, high-quality electrical energy becomes the basis for the operation of these equipment. The impact of voltage sags on these devices has also increased. The quantification of the impact of voltage sags on various sensitive equipment through tests is an important basis for equipment manufacturers to improve the equipment’s ability to withstand voltage sag and users to take governance measures. The existing test schemes are to manually change the voltage sag conditions, repeatedly test, manually analyze the test data and draw the voltage sag tolerance curve. The actual process operation is trivial and has low degree automation, which consumes a lot of human resources. This paper put forward an auto test system, it comprehensively considers the characteristics of voltage sag, sensitive equipment types, attributes, and load status, automatically generates voltage characteristic vectors, automatically tests and resets the equipment, automatically analyzes the experimental results and draws the voltage sag tolerance curve, which greatly reduces the test time and labor costs.

Recent study shows that recommendation system not only relys on user’s static preference, but also dynamic preference. Consequently, it leads to the emergence of session-based recommendation. With the development of recurrent neural network, this kind of method can capture representations of users’ sequential behaviors from a large number of sessions. However it is prone to spurious dependency problem. Recently, convolutional neural network has also shown its potential in modelling session, especially in extracting complex local pattern of subsequence. Therefore, we propose a hybrid neural model, called SGPD, for learning sequential general pattern and dependency for session-based recommendation. In SGPD, we propose recurrent residual convolution network to extract general pattern of subsequence in a session. Furthermore, the SGPD scans sequence from forward and reverse direction by bidirectional recurrent neural network, and learns sequential dependency of a session. Finally, the objective function is constructed by cross entropy and the model parameters are learned. The experimental results show that the precision rate, recall rate and mean reciprocal ranking of SGPD are greatly improved compared with the state-of-art methods. It has good application prospect.

Subjective tinnitus patients experience more hearing difficulties than normal peers in complex hearing environments, even though most of these patients have normal pure-tone hearing thresholds. Using speech recognition tasks under different masking conditions can provide insight into whether the effects of tinnitus are lateralized and the mechanisms behind the effects. By simulating sound field recordings, we obtain a target speech sentence that can be perceived as presented on one side and noise or speech masking with or without spatial separation from it. Our study used the virtual sound field technique to investigate the difference in speech recognition ability between chronic subjective tinnitus patients and a normal-hearing control group under the four masking conditions (speech-spectrum noise masking or two-talker speech masking, with or without perceived spatial separation). Experiment 1 showed no differences for target speech perceived location (left or right), which rules out a lateralization of the effect of tinnitus patients. Experiment 2 further found that although tinnitus patients had weaker performance than normal people in very complex auditory scenarios, when the spatial cue of the target speech exists, they can make good use of this cue to make up for the original processing disadvantage and achieve a similar performance as the normal-hearing group. In addition, the current study distinguished the effects of informational masking and energetic masking on speech recognition in patients with tinnitus and normal hearing. The results suggest that the impact of tinnitus on speech recognition in patients is more likely to occur in the auditory center rather than the periphery.

Bitumen emits a large amount of volatile organic compounds (VOCs) during the production and construction of asphalt mixture, which can cause both environmental hazards and health risks. In this study, a setup was designed to collect the VOCs released by base and crumb rubber-modified bitumen (CRMB) binders and their composition was characterized by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). Next, organic montmorillonite (Mt) nanoclay was added into CRMB binder and its inhibiting effect on the VOCs emission of the binder was investigated. Finally, the VOCs emission models for the CRMB and Mt-modified CRMB (Mt-CRMB) binders were established according to reasonable assumptions. The results indicated that the VOCs emission of CRMB binder was 3.2 times larger than that of the base binder. Due to its intercalated structure, the nanoclay can reduce the VOCs emission of CRMB binder by 30.6%. Especially, its inhibition effects on alkanes, olefins, and aromatic hydrocarbons were more significant. After finite element verification, the established model based on the Fick’s second law can describe the emission behavior of CRMB and Mt-CRMB binders well. Overall, the Mt nanoclay can be used as an effective modifier to inhibit the VOCs emission of CRMB binder.

As an important energy replacement block in China, the tight conglomerate oilfields in the Mahu area are difficult to develop and are characterized by strong heterogeneity, large horizontal stress differences, and undeveloped natural fractures. However, new development processes including temporary blocking diversion and large section-multiple clusters have been implemented on the oilfields in the past few years. In 2020, two adjacent horizontal wells in the MD well area experienced a poor fracturing development effect compared with the earlier wells in this area. Analysis suggests that the main reasons are water sensitivity of the reservoir, insufficient fracturing scale, and/or interference from the adjacent old wells. To ameliorate the problem, this study presents an experimental study of multiple temporary plugging and refracturing technology in long horizontal well sections, in combination with electromagnetic and microseismic monitoring. Results from the study show a great difference between the two monitoring techniques, which is attributed to their different detection principles. Interestingly, the combination of the two approaches provides a greater performance than either approach alone. As the fracturing fluid flow diversion is based on temporary plugging diversion and electromagnetic monitoring of fracturing fluid is advantageous in temporary plugging diversion monitoring, both approaches require further research and development to address complex situations such as multiple temporary plugging and refracturing in long intervals of adjacent older wells.

Abstract Background The Zika virus (ZIKV) outbreak that occurred in multiple countries was linked to increased risk of nervous system injuries and congenital defects. However, host immunity- and immune-mediated pathogenesis in ZIKV infection are not well understood. Interleukin-22 (IL-22) is a crucial cytokine for regulating host immunity in infectious diseases. Whether IL-22 plays, a role in ZIKV infection is unknown. Methods The cellular source of IL-22 was identified in IFNAR -/- mice and wild-type (WT) neonatal mice during ZIKV infection. To determine the role of IL-22, we challenged 1-day-old WT and IL-22 -/- mice with ZIKV and monitored clinical manifestations. Glial cell activation in the brain was assessed by confocal imaging. ZIKV-specific CD8+ T cell responses in both the spleen and brain were analyzed by flow cytometry. In addition, glial cells were cultured in vitro and infected with ZIKV in the presence of IL-22, followed by the evaluation of cell proliferation, cytokine expression, and viral loads. Results We found that γδ T cells were the main source of IL-22 during ZIKV infection in both the spleen and brain. WT mice began to exhibit weight loss, staggered steps, bilateral hind limb paralysis, and weakness at 10 days post-infection (dpi) and ultimately succumbed to infection at 16–19 dpi. IL-22 deficiency lessened weight loss, moderated the systemic inflammatory response, and greatly improved clinical signs of neurological disease and mortality. ZIKV infection also induced the activation of microglia and astrocytes in vitro. Additional analysis demonstrated that the absence of IL-22 resulted in reduced activation of microglia and astrocytes in the cortex. Although IL-22 displayed a negligible effect on glial cells in vitro, IL-22 -/- mice mounted more vigorous ZIKV-specific CD8+ T cell responses, which led to a more effective control of ZIKV in the brain. Conclusions Our data revealed a pathogenic role of IL-22 in ZIKV encephalitis.

Percolating composites with negative permittivity can be promising candidates for metamaterials. Herein, novel all-organic composite films containing of random coil polypyrrole (PPy) and poly(vinylidene fluoride) (PVDF) are fabricated via a solution casting method. The random coil PPy is prepared by oxidative template assembly approach for the first time. The experimental result indicates that the negative permittivity is easily adjusted through controlling the random coil PPy contents. Especially, the random coil PPy contents exceeded 7 wt% the negative permittivity appear attributed to the formation of 3D interconnected PPy network. This facile approach not only opens a new way to preparing negative permittivity of all-organic composite films, but also points out a route to facilitate the practical applications of metamaterials. Keywords: Polypyrrole, Composite films, Random coil, Negative permittivity

A self-adaptive controller is proposed to operate inverter in both grid-connected (GC) state and stand-alone (SA) state and ensure seamless transfer between them without reconfiguring the control structure. The controller is mainly composed of phase-locked-loop (PLL) and two cascaded control loops. The role of PLL is not only to estimate the frequency but also to generate the reference of voltage loop. When the grid is normal, the reference and the feedback value of voltage loop are always equal and the proposed controller accurately regulates the grid current of inverter. When islanding occurs, the inverter can automatically convert from current control mode to voltage control mode without critical islanding detection. The self-adaptive controller has several advantages. First, compared with direct current control, it can operate in both strong and weak grid conditions. Second, its dynamic performance in the GC state is much better than that of indirect current control. Third, when the grid returns to normal, the pre-synchronization of inverter's output voltage and grid voltage can be achieved automatically without any extra control algorithm. Finally, simulation and experimental results are provided to verify the effectiveness of proposed self-adaptive controller.

The carrier-based PWM method (CBPWM) and the space vector PWM method (SVPWM) are two main modulation methods for diode clamped multilevel converters, and there is a certain relationship between these two modulation strategies. For general 8 segments SVPWM modulation sequence in the multilevel inverter, the inherent relationship between these two modulation methods have been researched, but the relationship between CBPWM and SVPWM in an arbitrary level sequence has not been obtained. To solve this problem, an in-depth study of the relationship between the multilevel SVPWM method and the CBPWM method has been made in this paper. By decomposing the modulation wave, and the SVPWM can be achieved by multi-modulation waves CBPWM. And the relationship between SVPWM and CBPWM in N level with an arbitrary number of segments sequence are obtained. Thus, through simple multi-modulation waves CBPWM strategy, less THD in the spectrum and higher DC voltage utilization switching sequences of multilevel inverters can be obtained. The simulation and experimental results illustrate that the relationship between CBPWM and SVPMM is correct.

As a powerful feature extraction tool, a convolutional neural network (CNN) has strong adaptability for big data applications such as bearing fault diagnosis, whereas the classification performance is limited when the quality of raw signals is poor. In this paper, stochastic resonance (SR), which provides an advanced feature enhancement approach for weak signals with strong background noise, is introduced as a data pre-processing method for the CNN to improve its classification performance. First, a multiparameter adjusting bistable Duffing system that can achieve SR under large-parameter weak signals is introduced. A hybrid optimization algorithm (HOA) combining the genetic algorithm (GA) and the simulated annealing (SA) is proposed to adaptively obtain the optimized parameters and output signal-to-noise ratio (SNR) of the Duffing system. Therefore, the data optimization based on the multiparameter-adjusting SR of Duffing system can be realized. An SR-based mapping method is further proposed to convert the outputs of the Duffing system into grey images, which can be further processed by a normal CNN with batch normalization (BN) layers and dropout layers. After verifying the feasibility of the HOA in multiparameter optimization of the Duffing system, the bearing fault data set from the CWRU bearing data center was processed by the proposed fault enhancement classification and identification method. The research showed that the weak features of the bearing signals could be enhanced significantly through the adaptive multiparameter optimization of SR, and classification accuracies for 10 categories of bearing signals could achieve 100% and those for 20 categories could achieve more than 96.9%, which is better than other methods. The influences of the population number on the classification accuracies and calculation time were further studied, and the feature map and network visualization are presented. It was demonstrated that the proposed method can realize high-performance fault enhancement classification and identification.

While photoredox catalysis offers a new dimension to chemical synthesis, there are few heterogeneous organocatalysts for metal-free transformations. Here, authors prepare and perform in-depth studies on polymeric photocatalyst scaffolds for organic chemistry transformations.

In computer science, consensus theory has been studied for decades. “Consensus” in a multi-agent system means reaching an agreement regarding a certain quantity of interest. The modular multilevel converter (MMC) is a promising topology for medium- and high-power applications owing to its salient features. In MMC operation, one key point is to regulate the capacitor voltage of each submodule (SM). The SMs in MMCs are interconnected both physically and via a control system, and these SMs can be regarded as a multi-agent system, with the control objective of regulating their capacitor voltages, which could formulate a consensus problem. In this paper, through mathematical derivation, it is found that individual capacitor voltage regulation control of phase-shifted-carrier pulse-width modulation (PSC-PWM) MMC is one special case of consensus theory. Furthermore, based on the consensus theory, the influence of different communication structures on the MMC voltage regulation performance is discussed. The analysis proves that the existing one has the highest rate of convergence. The impact of current-tracking dynamics on consensus-based interpretation is also analyzed. In addition, the proportional relationship between the rate of convergence and the P controller parameter is also justified. The experiments on a seven-level down-scaled prototype are conducted to confirm the analysis.

Real-time strategy (RTS) game is a kind of strategy game, in which the players compete for resources on 2D terrain by establishing the economy, training army, and guiding them into battle in real time. The winner prediction of the RTS games often involves studying a highly uncertain problem in an adversarial environment. In addition, the limit of the number of samples restricts on the application and performance of the prediction models. To obtain better winner prediction accuracy and maintain the prediction uncertainty under an adversarial environment, this paper proposes a neural network-based prediction method incorporated probability inference dealing with a small set of samples. This paper uses a dataset released based on SC2LE, a reinforcement learning environment released jointly by Blizzard Entertainment and DeepMind, and then employed the proposed neural processes model to build a winner prediction model. To verify, this paper implemented different features types' grouping and different game length grouping experiments for demonstrating better adaptability to such problems. Furthermore, this paper also implemented the SVM model experiments and compared the proposed method with the SVM model. Finally, when making predictions on a 1000 size testing data, the results show that the proposed prediction model achieves an accuracy of 0.811 at 200 and 0.821 at 1000 sizes of training sets, which is better than the SVM model with small training datasets.

Abstract In this study, we used data from multiple sensors onboard NASA Aqua satellite to conduct a 10‐year (2002–2011) remote sensing of microwave emissivity difference vegetation index (EDVI) over China. We investigated the spatial and temporal variations of EDVI in tropical and subtropical evergreen forest, deciduous forest, rice and wheat farmlands, grassland, and montane vegetation regions. The average of China's EDVI is positive in dense vegetation regions and negative in sparse vegetation regions, depending on the proportion of bare soil and open water. In all selected studying regions, the seasonal variation of EDVI follows the trend of vegetation phenology, even in regions with large proportion of open water. EDVI is positively correlated to the greenness of vegetation (normalized difference vegetation index [NDVI]) with certain phase difference in their seasonal cycle. In autumn, EDVI begins to decline earlier and faster than NDVI. In tropical rainforest, EDVI also starts to increase earlier than NDVI in spring. The large‐scale spatial distribution of EDVI under clear sky and cloudy sky is similar. In montane vegetation regions, EDVI under heavy clouds (90% fraction) conditions is significantly greater than that under clear sky (10% fraction), indicating a possible cloud induced enhancement of vegetation water content. In forests and croplands in the plains, such effect is not remarkable.

Orientia tsutsugamushi infection can cause acute lung injury and high mortality in humans; however, the underlying mechanisms are unclear. Here, we tested a hypothesis that dysregulated pulmonary inflammation and Tie2-mediated endothelial malfunction contribute to lung damage. Using a murine model of lethal O. tsutsugamushi infection, we demonstrated pathological characteristics of vascular activation and tissue damage: 1) a significant increase of ICAM-1 and angiopoietin-2 (Ang2) proteins in inflamed tissues and lung-derived endothelial cells (EC), 2) a progressive loss of endothelial quiescent and junction proteins (Ang1, VE-cadherin/CD144, occuludin), and 3) a profound impairment of Tie2 receptor at the transcriptional and functional levels. In vitro infection of primary human EC cultures and serum Ang2 proteins in scrub typhus patients support our animal studies, implying endothelial dysfunction in severe scrub typhus. Flow cytometric analyses of lung-recovered cells further revealed that pulmonary macrophages (MΦ) were polarized toward an M1-like phenotype (CD80+CD64+CD11b+Ly6G-) during the onset of disease and prior to host death, which correlated with the significant loss of CD31+CD45- ECs and M2-like (CD206+CD64+CD11b+Ly6G-) cells. In vitro studies indicated extensive bacterial replication in M2-type, but not M1-type, MΦs, implying the protective and pathogenic roles of M1-skewed responses. This is the first detailed investigation of lung cellular immune responses during acute O. tsutsugamushi infection. It uncovers specific biomarkers for vascular dysfunction and M1-skewed inflammatory responses, highlighting future therapeutic research for the control of this neglected tropical disease.

Diode-clamped multi-level converters have DC-side capacitors in series, which will lead to the unbalance of DC-side capacitor voltage, the distortion of the output waveform, the increase of total harmonic distortion (THD), and even the damage of switching devices, which will make the system inoperable. The proposal of virtual space vector pulse-width modulation (VSVPWM) realizes the balanced control of the capacitor voltage, but when the output level of converter increases, the implementation of VSVPWM becomes very complicated, and the amount of calculation also increases greatly, thus hindering its application in the multi-level circuit. Compared with VSVPWM, the carrier-based pulse-width modulation (CBPWM) is simple to operate and easy to implement. If the equivalent relationship between CBPWM and VSVPWM can be found, the application of VSVPWM can be generalized to any level, and the advantages of VSVPWM can be fully utilized. This paper aims to study the inner relationship of VSVPWM and the multi-modulation carrier CBPWM (MCBPWM). After strict theoretical analysis, the equivalent relationship of VSVPWM and MCBPWM in the three-level and four-level and converter is realized by injecting the zero-sequence component into the modulation waves. Furthermore, the equivalent relationship between VSVPWM and MCBPWM is deduced to the N-level converter. Finally, the correctness of the relevant theoretical analysis is verified by the experiment.

The dynamic magnetic domain structure in magnetization and demagnetization process of hot-deformed and NdCu-diffused Nd2Fe14B magnets were in-situ observed by Lorentz transmission electron microscopy (LTEM). The demagnetization process of hot-deformed sample is dominated by domain-wall pinning, while that of NdCu-diffused sample is mainly the magnetization reversal of single grains or grain aggregations. This firstly observed result gives an explicit evidence to understand the coercivity mechanism of magnetically segregated magnet. The effect of magnetic field of TEM on decrease in domain wall energy was theoretically analyzed, which helps to understand the in-situ observation process of magnetic materials.

Background: The anti-infammatory and cardioprotective effect of acetylcholine (ACh) has been reported; nevertheless, whether and how ACh exhibits an antioxidant property against ischemia/reperfusion (I/R)-induced oxidative stress remains obscure. Methods: In the present study, H9c2 rat cardiomyocytes were exposed to hypoxia/reoxygenation (H/R) to mimic I/R injury. We estimated intracellular different sources of reactive oxygen species (ROS) by measuring mitochondrial ROS (mtROS), mitochondrial DNA (mtDNA) copy number, xanthine oxidase (XO) and NADPH oxidase (NOX) activity and expression of rac 1. Cell injury was determined by lactate dehydrogenase (LDH) release and cleaved caspase-3 expression. The siRNA transfection was performed to knockdown of M2 acetylcholine receptor (M2 AChR) expression. Results: 12-h hypoxia followed by 2-h reoxygenation resulted in an abrupt burst of ROS in H9c2 cells. Administration of ACh reduced the levels of ROS in a concentration-dependent manner. Compared to the H/R group, ACh decreased mtROS, recovered mtDNA copy number, diminished XO and NOX activity, rac 1 expression as well as cell injury. Co- treatment with atropine rather than hexamethonium abolished the antioxidant and cardioprotective effect of ACh. Moreover, knockdown of M2 AChR by siRNA showed the similar trends as atropine co-treatment group. Conclusions: ACh inhibits mitochondria-, XO- and NOX-derived ROS production thus protecting H9c2 cells against H/R-induced oxidative stress, and these benefcial effects are mainly mediated by M2 AChR. Our findings suggested that increasing ACh release could be a potential therapeutic strategy for treatment and prevention of I/R injury.

Mechanical fault diagnosis usually requires not only identification of the fault characteristic frequency, but also detection of its second and/or higher harmonics. However, it is difficult to detect a multi-frequency fault signal through the existing Stochastic Resonance (SR) methods, because the characteristic frequency of the fault signal as well as its second and higher harmonics frequencies tend to be large parameters. To solve the problem, this paper proposes a multi-frequency signal detection method based on Frequency Exchange and Re-scaling Stochastic Resonance (FERSR). In the method, frequency exchange is implemented using filtering technique and Single SideBand (SSB) modulation. This new method can overcome the limitation of "sampling ratio" which is the ratio of the sampling frequency to the frequency of target signal. It also ensures that the multi-frequency target signals can be processed to meet the small-parameter conditions. Simulation results demonstrate that the method shows good performance for detecting a multi-frequency signal with low sampling ratio. Two practical cases are employed to further validate the effectiveness and applicability of this method.

A simple, accurate and reliable high performance liquid chromatography coupled with photodiode array detection (HPLC-DAD) method was developed and then successfully applied for simultaneous quantitative analysis of eight compounds, including chlorogenic acid (1), (R/S)-flavanomarein (2), butin-7-O-β-d-glucopyranoside (3), isookanin (4), taxifolin (5), 5,7,3′,5′-tetrahydroxyflavanone-7-O-β-d-glucopyranoside (6), marein (7) and okanin (8), in 23 batches of snow chrysanthemum of different seed provenance and from various habitats. The results showed total contents of the eight compounds in the samples with seed provenance from Keliyang (Xinjiang, China), are higher than in samples from the other five provenances by 52.47%, 15.53%, 19.78%, 21.17% and 5.06%, respectively, which demonstrated that provenance has a great influence on the constituents in snow chrysanthemum. Meanwhile, an ultra performance liquid chromatography coupled with electrospray ionization and quadrupole time-of-flight-mass spectrometry (UPLC-ESI-QTOF-MS) was also employed to rapidly separate and identify flavonoids and phenolic acids in snow chrysanthemum from Keliyang. As a result, a total of 30 constituents, including 26 flavonoids and four phenolic acids, were identified or tentatively identified based on the exact mass information, the fragmentation characteristics, and retention times of eight reference standards. This work may provide an efficient approach to comprehensively evaluate the quality of snow chrysanthemum.