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Cognitive impairment, an intrinsic feature of major depressive disorder (MDD), affects daily and social functioning in depression patients. However, the cognitive impairment profile in MDD remains ambiguous because of the high heterogeneity of previous studies.Four cognitive domains, including memory, processing speed, executive function (EF), and attention, were assessed in 184 first-episode drug-naïve (FEDN) MDD patients and matched 71 healthy controls (HCs). The effects of demographic and depressive factors on cognitive performance were analyzed using various statistical methods, including multi-factor analysis of variance, Mann-Whitney U test, and Spearman's rank correlation. In addition, the impact of depression severity on cognitive function was further assessed using subgroup analyses and partial correlation analyses.Age and education significantly impacted most cognitive performances, and depression severity appeared to influence processing speed. Moreover, cognitive scores in memory and processing speed, rather than in EF and attention, were significantly different between FEDN MDD patients and HCs after controlling for sex, age, educational attainment, household income, and body mass index.The number of HCs was relatively small, which may have slightly reduced the study's statistical power.Age and educational attainment have confirmative confounding effects greater than those of depression in most cognitive functions. More importantly, memory and processing speed were impaired in MDD after strictly controlling for confounders. These findings provide new information for understanding the pattern of cognitive impairment and offer clues for further exploring the pathogenesis of cognitive abnormalities in MDD.

Background. Realgar (REA), a Chinese herbal decoction, has been used to treat various tumors and has produced positive outcomes; however, there is a lack of convincing evidence for the treatment of esophageal cancer. The present study aimed to investigate the effects of REA on esophageal cancer (EC) and explore its mechanism. Methods. EC cells Eca109 and KYSE150 were selected for this study, and different groups of treated cells were set up. We studied the inhibition rate and half inhibition concentration (IC50) by CCK-8 method, the clone formation assay was used to detect the clone formation ability, the scratch assay is used to determine the cell migration ability, the Transwell assay was used to detect the cell invasion ability, the protein expressions of E-cadherin, Slug, N-cadherin, ASK1, p38 MAPK, p-p38 MAPK, and GPX4 were determined using Western blot, the mRNA expressions of ASK1 and p38 MAPK were assessed using qRT-PCR, transmission electron microscopy was used to observe the cellular ultrastructure, Prussian blue staining was used to observe the intracellular iron particle distribution, and biochemical analysis of cellular MDA, SOD, GSH, and GPXS activities, flow cytometric analysis of cellular ROS levels, immunofluorescence staining to detect cellular GPX4 expression, and JC-1 method to detect mitochondrial membrane potential were used. Results. REA inhibited the proliferation of Eca109 and KYSE150 cells in a time- and concentration-dependent manner, and REA significantly inhibited the migration and invasion of Eca109 and KYSE150 cells and activated the cellular ferroptosis and ROS-ASK1-p38 MAPK signaling pathways ( P < 0.05 ). Inhibition of activation of the ROS-ASK1-p38 MAPK signaling pathway promoted the inhibition of proliferation, migration, and invasion of Eca109 and KYSE150 cells and the induction of ferroptosis by REA. Conclusion. REA induced ferroptosis and inhibited the migration of EC cells by activating the ROS-ASK1-p38 MAPK signaling pathway.

The therapeutic outcomes in major depressive disorder (MDD), one of the most common and heterogeneous mental illnesses, are affected by factors that remain unclear and often yield unsatisfactory results. Herein, we characterized the composition and metabolic function of the gut microbiota of patients with MDD during antidepressant treatment, based on 16S rRNA sequencing and metabolomics. The microbial signatures at baseline differed significantly between responder and non-responder groups. The gut microbiota of the non-responder group was mainly characterized by increased relative abundances of the phylum Actinobacteria, families Christensenellaceae and Eggerthellaceae, and genera Adlercreutzia and Christensenellaceae R7 group compared to that of the responder group. Additionally, the gut microbiota composition of the responder and non-responder groups differed significantly before and after treatment, especially at the genus level. Moreover, 20 differential metabolites between the responder and non-responder groups were identified that were mainly involved in lipid metabolism (cholestane steroids and steroid esters). Eggerthellaceae and Adlercreutzia displayed strong co-occurrence relationships with certain metabolites, suggesting alternations in the gut microbiome, and associated metabolites may be potential mediators of successful antidepressant treatment. Overall, our study demonstrates that alterations in gut microbiota composition and metabolic function might be relevant to the response to antidepressants, thereby providing insight into mechanisms responsible for their efficacy.

To support the “carbon peak and carbon neutrality” goal, new energy is poised to explode, and new energy power generation converter is simultaneously facing new challenges. The conventional current-controlled new energy converter can quickly transmit active power on the DC bus to the power grid. However, for the weak grid, the stability margin of the converter grid-connected system is reduced on the one hand, which can easily cause resonance oscillation, on the other hand, the current controlled converter cannot actively respond to system frequency and voltage fluctuation to offer support. The voltage controlled virtual synchronous generator (VVSG) is used to improve system small signal stability and frequency stability, however, its power response speed is too slow to meet the requirements of fast following power command. Although a voltage/current dual-mode switching control scheme is put forward to achieve characteristics complementary of current controlled converter and voltage-controlled converter, the control structure switching and intermediate variable following is required to realize mode switching, which is prone to large power shocks and switching failures. In view of the problem, a direct power control strategy based on VVSG is proposed. The control structure is raised based on a conventional VVSG outer active power control loop, and the output active power and frequency characteristics are analyzed. Compared with the voltage and current dual-mode control, VVSG with direct power control can perform large inertia characteristic in the weak grid and fast power following characteristics in the strong grid by adjusting λ, and without control structure switching and intermediate variable following. Moreover, the two characteristics can be smoothly transited. In addition, the active support ability of voltage source can be maintained under both characteristics. Finally, the effectiveness of the proposed control strategy is verified through simulation results.

With increasing penetration of renewable energy sources into distributed power systems, multi-parallel inverters are commonly employed in the interface to the utility grid, giving rise to potential resonance problems. Aiming at this issue, common-mode resonance of single inverter and multi-parallel inverters are analyzed. First, single inverter common-mode circuits model is built. Common-mode paths are found in it and the admittances of each path are analyzed. Based on it, multi-parallel inverters equivalent circuits are modeled and analyzed. In order to investigate common-mode resonance characteristics, self-coupled and mutual-coupled paths are analyzed and compared to single inverter's path. To get more accuracy resonance characteristics, a crossover filter function is introduced and used to separate output common-mode currents at different frequencies for two-parallel inverters. The impact of parasitic capacitance on resonance is examined. Experimental results validate the developed models and the proposed resonance characteristics.

With the growth of renewable energy, grid-connected inverter as the interface has gradually increased its application. However, with the large-scale connection of inverters, resonance and stability problems have also been brought to distributed systems. Aiming at this issue, in this paper, a multi-parallel equivalent small signal model based on the structure of the multi-inverter grid-connected system is established firstly, and the expression of the output current of each inverter is obtained. According to the phase characteristics of the inverter’s output at different frequency bands, the output current expressions for synchronized and interleaved control period are further obtained. On this basis, influences of penetration, control gain and delay on harmonic or resonance are analyzed. Finally, a platform of four 30kW inverters is setup, and "resonance stability margin" method is proposed to verify the harmonic resonance characteristics of the inverter output current under high penetration.

In recent years, virtual inertia algorithms are mostly applied to inverters of high-penetration distributed generation systems to improve system equivalent inertia. When distributed generators (DG) based on traditional first-order virtual inertia (TFVI) algorithm operates in weak grid connected mode, there is contradiction between its output active power steady state and dynamic characteristics adjustment. Although the virtual inertia with improved structures such as first-order virtual inertia based on differential compensation (DCFVI) and second-order virtual inertia (SVI) have better active power control accuracy and power oscillation damping ability simultaneously, its frequency support ability in high permeability distributed generation system is weaker due to its fast frequency response and small inertia in the initial stage of response, which is easier to cause under-frequency load shedding. In this paper, firstly, the frequency characteristics of the DG based on the above virtual inertia algorithms operating in islanded mode are analyzed, and the active power steady-state and dynamic characteristics of the DG operating in grid connected mode are studied as well. Afterwards, based on the active power steady-state and dynamic characteristics comparison and summary of DG grid-connected system with each improved virtual inertia algorithm, through optimization of the second-order virtual inertia structure, an optimized second-order virtual inertia (OSVI) algorithm is proposed, which can not only maintain the active power control accuracy and suppress power oscillation, but also can provide larger frequency support capability. Finally, the effectiveness of the proposed control strategy is verified by simulation.

Simple Summary The Pyraloidea is a large superfamily of Lepidoptera in species composition. To date, the higher-level phylogenetic relationships in this group remain unresolved, and many taxa, with taxonomic positions historically established by morphological characters, need to be confirmed through sequencing of DNA, including mitochondrial genome sequences (mitogenomes). Here, we newly generated nine complete mitogenomes for Pyraloidea that shared identical gene content, and arrangements that are typical of Lepidoptera. The current phylogenetic results confirmed previous multilocus studies, indicating the effectiveness of mitogenomes for inference of Pyraloidea higher-level relationships. Unexpectedly, Orybina Snellen was robustly placed as basal to the remaining Pyralidae taxa, rather than nested in the Pyralinae of Pyralidae as morphologically defined and placed. Our results bring a greater understanding to Pyraloidea phylogeny, and highlight the necessity of sequencing more pyraloid taxa to reevaluate their phylogenetic positions. Abstract The Pyraloidea is one of the species-rich superfamilies of Lepidoptera and contains numerous economically important pest species that cause great loss in crop production. Here, we sequenced and annotated nine complete mitogenomes for Pyraloidea, and further performed various phylogenetic analyses, to improve our understanding of mitogenomic evolution and phylogeny of this superfamily. The nine mitogenomes were circular, double-stranded molecules, with the lengths ranging from 15,214 bp to 15,422 bp, which are comparable to other reported pyraloid mitogenomes in size. Gene content and arrangement were highly conserved and are typical of Lepidoptera. Based on the hitherto most extensive mitogenomic sampling, our various resulting trees showed generally congruent topologies among pyraloid subfamilies, which are almost in accordance with previous multilocus studies, indicating the suitability of mitogenomes in inferring high-level relationships of Pyraloidea. However, nodes linking subfamilies in the “non-PS clade” were not completely resolved in terms of unstable topologies or low supports, and future investigations are needed with increased taxon sampling and molecular data. Unexpectedly, Orybina Snellen, represented in a molecular phylogenetic investigation for the first time, was robustly placed as basal to the remaining Pyralidae taxa across our analyses, rather than nested in Pyralinae of Pyralidae as morphologically defined. This novel finding highlights the need to reevaluate Orybina monophyly and its phylogenetic position by incorporating additional molecular and morphological evidence.

The virtual inertia and virtual damping affect both the dynamic stability of the virtual synchronous generator(VSG) and the configuration of energy storage, but there is a conflict between them while selecting the virtual inertia and virtual damping. An optimal coordination control strategy of micro-grid inverter and energy storage based on variable virtual inertia and damping is proposed to mitigate this conflict. With the integrated optimal constraint of the VSG frequency variation and the energy storage capacity, the virtual inertia and damping of VSG are configured dynamically, adopting linear quadratic optimal control. It can suppress the oscillations of the active power and frequency to improve the stability of VSG and optimally configure the energy storage capacity of VSG simultaneously. The proposed strategy aims to improve the control performance of micro-grid inverter and the system economy. The simulation and experimental results verify the effectiveness of the strategy.

This paper investigates the use of a virtual synchronous generator (VSG) to improve frequency stability in an autonomous photovoltaic-diesel microgrid with energy storage. VSG control is designed to emulate inertial response and damping power via power injection from/to the energy storage system. The effect of a VSG with constant parameters (CP-VSG) on the system frequency is analyzed. Based on the case study, self-tuning algorithms are used to search for optimal parameters during the operation of the VSG in order to minimize the amplitude and rate of change of the frequency variations. The performances of the proposed self-tuning (ST)-VSG, the frequency droop method, and the CP-VSG are evaluated by comparing their effects on attenuating frequency variations under load variations. For both simulated and experimental cases, the ST-VSG was found to be more efficient than the other two methods in improving frequency stability.

Mega-scale solar projects are turning to string inverters nowadays. Multi-parallel string inverters are employed as the interface to the utility grid, giving rise to potential unstable problems. Aiming at this issue, the relationship between number of inverters, output power and grid impedance is analyzed. Based on this, according to different topology, control structures and filter parameters, four types of Standard Equivalent Model (SEM) for multi-inverters system are established. By analyzing the stability margin of the four SEMs and the sensitivity of their control parameters, the difference of stability between the string inverters and the central inverters is compared. Finally, the established SEM and the comparison results of the string and central inverters are verified by simulation and experimental results.

In view of the contradiction between active power steady-state and dynamic characteristics regulation of VSG based on the existing first-order virtual inertia algorithm operating in grid- connected mode and multi-paralleled mode, a virtual inertia control strategy based on multi-stage lead-lag compensation is proposed in this paper. By cascading a multi-stage lead-lag link in the first -order virtual inertia forward channel, the control freedom of VSG grid-connected and paralleled system is increased, so that the zero and poles can be freely configured. Furthermore, a first-order lead-lag link is taken as an example to analyze its effect on the output active power steady-state and dynamic characteristics of VSG grid-connected system and paralleled systems. Through reasonable configuration of the second-order virtual inertia parameters, the system damping ratio can be increased and the power oscillation can be eliminated while its steady-state characteristics are not changed under the circumstance of a large inertia. Experimental results verify the effectiveness of the proposed strategy.

Photovoltaic(PV) inverters have been widely used in large-scale PV power generation systems to reduce the system mismatch and increase the output power. With the increasing installed capacity of PV power stations, the number of string PV inverters increases, which brings about risk of inverter resonance and influences the quality and stability of multi-parallel inverters grid-connected system. Thus, the problems of multi-parallel inverters resonance have become a hot research topic. This paper is focused on the case of grid-connected string PV inverter systems, and the grid-connected PV inverter resonance where resonance suppression strategy will be analyzed and discussed. Firstly, the structure of string PV inverter and multi-parallel inverters system are presented. Secondly, discussions are made about the model of multi-parallel inverters system and its resonance characteristics based on the multi-input-multi-output(MIMO) system, Norton equivalent circuit and carrier synchronization. Thirdly, two strategies of “inverter level” and “system level” are provided to summarize the multi-parallel inverters resonance suppression strategy. Finally, the development tendency of resonance suppression strategy and conclusions are prospected.

The resonant stability problems of LCL filter have become big challenges for grid-connected inverter in weak grid. This paper takes the effect of non-minimum phase time delay on the ratio between resonance frequency and sampling frequency into account and use it to design the LCL filter. Both LCL resonance frequency and inverter-side inductor and filter capacitor related L 1 C resonance frequency are limited to a specific stability region considering the following factors: different computation delay, inductance variation and grid impedance variation in a large range. Associated with the maximum current ripple expression for inverter-side inductance calculation, three expressions can establish a simple and robust method to calculate LCL filter parameters without active damping. Simulation and experimental results are provided to validate the correctness of the developed model and control scheme.

Determining a wellhead protection area (WHPA) is a basic and important step in protecting groundwater from contamination. Based on availability of data and complexity of hydrogeological conditions, different delineation methods can be adopted. This study’s objective was to examine the relation and difference of the results calculated using six WHPA delineation methods, which ranged from simplified shapes to stochastic models with superior sampling means. All the methods were applied to a well field in Beijing, China. The WHPA probability distribution from a stochastic simulation was used as reference for comparison with other methods. WHPAs calculated using simplified and analytical approaches turned out to be smaller than reference WHPA. Those calculated using the numerical model provided better results but still cannot include a considerable area of reference WHPA. The stochastic approach based on efficient orthogonal Latin hypercube sampling provided an estimation of the probability distribution of WHPA delineation with different degrees of uncertainty, which played an important role in the WHPA delineation of the well field in Beijing. To attain a realistic WHPA delineation in a complex aquifer system, various delineation approaches can be adopted and all results that validate each other must be considered.

This paper explores the impact of the output impedance on the power-sharing stability between parallelized microgrid inverters (MGIs) operating with virtual synchronous generator (VSG) method. In these systems, a virtual output impedance is usually added to the control loop of each MGI to improve the power sharing, regardless of line impedance unbalances. The time derivative of the MGI output current is usually used to implement the virtual impedance, which makes the system highly sensitive to the output current with high slew rate. To solve this, the virtual impedance is designed based on a cascaded second order general integrator (CSOGI) scheme, which is less sensitive to the output current noise, avoids to perform the time derivative function, achieves better output voltage total harmonic distortion. The proposed strategy is demonstrated in detail and validated with a two 100kVA-MGIs parallel system under linear and nonlinear loads.

Due to the large adjust inertia of the diesel generator set (DGS), the quality of power supply would decline when a large load disturbance occurs to the diesel generator system. This paper aims to improve the stability of the diesel generator system voltage amplitude and frequency under impact load conditions using a virtual synchronous generator (VSG) method. Firstly, a mathematical model of DGS is built, the dynamic performances of DGS under a variety of load conditions is analyzed. Secondly, a three-phase energy storage inverter based on VSG control is selected as the parallel power compensator to suppress the system voltage amplitude and frequency fluctuations. Finally, experimental results are given to verify the feasibility and validity of the proposed control strategy.

This paper presents a state of charge (SOC) based control strategy for virtual synchronous generator (VSG) when connecting to the grid. The VSG is operated in voltage source mode, the output frequency of VSG is calculated by considering the virtual inertial and the power reference together. The power reference is acquired by adding the SOC control module and the frequency control module, the proportion of each module is determined by applying a weight coefficient, if the SOC control module is in the majority, the VSG is more inclined to maintain the SOC, otherwise the VSG is more inclined to stable the frequency. Considering the dynamic response and stability of control system the select range for the weight coefficient is designed. Simulation results are presented in order to validate the proposed approach.

With increasing penetration of renewable energy sources into modern power systems, multi-parallel inverters are commonly employed in the interface to the utility grid, giving rise to potential resonance problems. Firstly, 2-parallel inverters equivalent circuit model is established based on its control. In order to decouple inverter output current, the components characteristics of inverter output are analyzed in different frequencies, and one of 2-parallel inverter output current under condition of synchronized and asynchronized carriers are worked out. An idea “Resonance Stability Margin” is raised to investigate and evaluate resonance characteristics, variables that represent the stability of the system are found in control system of single inverter, and are used to record when the system achieves the same closed-loop dominant pole position or open-loop phase margin under different conditions. Values of those variables recorded indirectly reflect the degree of resonance in the paralleled inverters system. Experimental results validate the developed resonance characteristics and the proposed resonance stability margin.

This paper concentrates on the load disturbance in three phase microgrid inverter (MGI) with an isolated transformer based on virtual synchronous generator (VSG) control. The transformer can provide the VSG with inductive output impedance when placed behind the LC filter. But the load disturbance may lead to steady-state error and poor dynamic performance with only capacitor voltage feedback control. The capacitor voltage differential feedback control is proposed to damp the output LC filter resonance and thus increases the system stability margin. The output current differential feedforward control is proposed to eliminate the influence of load disturbance then obtains error-free steady-state output and excellent dynamic responses. These theoretical findings have been eventually verified experimentally both on simulation and laboratory prototypes.

This paper proposes a novel seamless transfer method for microgrid connected fuel cell inverters (FCIs) between voltage source and current source modes. In order to protect the fuel cell, the FCI output power should be restricted when the microgrid frequency is greatly disturbed. In this sense, the FCI is transfered from voltage source mode to constant current source mode. Meanwhile, the FCI is transfered from constant current source mode to voltage source mode until service can be restored. The proposed method can cooperatively work with well developed virtual synchronous generator (VSG) control algorithm so that these FCIs are able to share load among them as well as subsist under transient events of the system. Theoretical analysis and experimental results validate effectiveness of the proposed method.

The adoption of virtual synchronous generation (VSG) control can maintain the stability of voltage and frequency in power electronic interfaced mircogrid. In this paper virtual impedance is added to the VSG control strategy in order to improve the system control performance in resistive-inductive line impedance, the influence of virtual impedance on VSG system stability and dynamic performance is analyzed through the small-signal model. Simulation is presented to verify the conclusion of this paper.

China Machinery Industry Standard (CMIS) GB/T 12326-2008 prescribed in the islanded operation mode, microgrid inverter (MGI) output voltage dynamic transient range is less than 10% when the resistive load is switched rapidly between 0% and 100%. The three-loop power virtual synchronous generator (VSG) control methods are commonly used in MGI units to share the loads among the parallel MGIs. However, the transient output voltage of the MGI is beyond the CMIS when the resistive load steps sharply. In order to meet the CMIS, an output voltage differential feedback improved algorithm was employed. Comparing to the traditional control method, the improved method could obtain satisfying dynamic transient voltage suppression, resonance inhibition and improve system stability. These theoretical findings were eventually verified experimentally both on simulation and laboratory prototypes.

The three-loop power virtual synchronous generator (VSG) control methods are commonly used in microgrid inverter (MGI) units to share the loads among the parallel MGI units. In order to achieve stable operation of the MGI units under paralleled or grid-connected mode, a droop synchronization controller is designed in this paper. The difference of phase and amplitude between different MGI units is detected and is used to calculate the output frequency and amplitude of the MGI. The control principle is introduced and the synchronization control block diagram is given. The simulation and experimental results verify that the proposed method is effective in achieving paralleled operation of the MGI units.

For the problem that paralleled inverters cannot share reactive power proportional to their power capacity in islanding microgrid. Originally, the effect of inverter output impedance and line impedance to reactive power sharing with conventional droop control is analyzed. Following, a method adjusting the output reactive power by paralleling capacitor at the inverter output is proposed, and the relationship between paralleled capacitors, line impedance and reactive power is analyzed. On the basis, virtual capacitor method is realized to improve reactive power balance. Finally, the proposed method and analysis are verified through simulation.

Microgrid should be operated in both grid-connected and islanded mode to ensure high voltage quality and reliability. In the case of continuous uninterrupted power supply, seamless transfer is important between the two modes,and synchronization of the voltage of the point of common coupling (PCC) and utility grid should be finished first to achieve the goal. In this paper varies of synchronization strategies used in different microgrid control structures from islanded mode to grid-connected mode are summarized, and a new method based on droop control is proposed. This method does not affect power sharing during synchronization procedure. Simulation and experiment results are presented to show the feasibility of the method.

In this paper, a general active damping method based on capacitor voltage detection for stable control of LCL-filter grid-connect inverter is proposed. Three active damping methods are derived from the general form. Root locus and bode diagrams are used to analysis these three active damping methods. And in the case of different control delay, robustness of three active damping methods are compared. Integrated the advantages and disadvantages of each method, and eventually come to a relatively better active damping method. Finally, each active damping method is verified by simulation and experiment.

Stochastic modeling is a rapidly evolving, popular approach to the study of the uncertainty and heterogeneity of groundwater systems. However, the use of Monte Carlo-type simulations to solve practical groundwater problems often encounters computational bottlenecks that hinder the acquisition of meaningful results. To improve the computational efficiency, a system that combines stochastic model generation with MODFLOW-related programs and distributed parallel processing is investigated. The distributed computing framework, called the Java Parallel Processing Framework, is integrated into the system to allow the batch processing of stochastic models in distributed and parallel systems. As an example, the system is applied to the stochastic delineation of well capture zones in the Pinggu Basin in Beijing. Through the use of 50 processing threads on a cluster with 10 multicore nodes, the execution times of 500 realizations are reduced to 3% compared with those of a serial execution. Through this application, the system demonstrates its potential in solving difficult computational problems in practical stochastic modeling.

Groundwater protection is of great importance in terms of public health and environmental safety. Wellhead Protection Area (WHPA) Delineation is a basic and effective measurement for protecting groundwater from contaminated. Different methods of WHPA delineation can be selected depending on the feasible data and complexity of the hydrogeologic conditions, during which numerical simulation is one of the most popular methods. However, simple steady-state assumptions were always made to simplify the calculation and inaccurate estimations may be resulted in. The purpose of this paper is to emphasize the importance of considering transient property for delineating WHPA. The popular numerical model (MODFLOW) combined with a particle tracking code (MODPATH) were used and the WangDuZhuang (WDZ) wellfield in Beijing, China was taken as an example. Both transient and steady-state models were calculated and different WHPAs were gained and compared. The transient WHPA are comparable in shape with the steady one but not in size due to the differences in drawdowns taking in account the seasonal variation of recharge. The influence of considering the transient property was discussed.