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Acoustic imaging technology has the advantages of non-contact and intuitive positioning. It is suitable for the rapid positioning of defects such as the mechanical loosening, discharge, and DC bias of power equipment. However, the existing research lacks the optimization design of microphone array topology. The acoustic frequency domain characteristics of typical power equipment are elaborately sorted out. After that, the cut-off frequencies of acoustic imaging instruments are determined, to meet the needs of the full bandwidth test requirements. Through a simulation calculation, the circular array is demonstrated to be the optimal shape. And the design parameters affect the imaging performance of the array to varying degrees, indicating that it is difficult to obtain the optimal array topology by an exhaustive method. Aimed at the complex working conditions of power equipment, a topology optimization design method of an acoustic imaging array for power equipment is proposed, and the global optimal solution of microphone array topology is obtained. Compared with the original array, the imaging performance of the improved LF and HF array is promoted by 54% and 49%, respectively. Combined with the simulation analysis and laboratory test, it is verified that the improved array can not only accurately locate the single sound source but also accurately identify the main sound source from the interference of the contiguous sound source. [ABSTRACT FROM AUTHOR]

Phase–locked loop (PLL) is commonly used for the grid-connected voltage-source converter (VSC) to synchronize with the grid. Under weak grid conditions, it has been found that the frequency-dependent characteristic of the network impedance inherently introduces a positive feedback loop into PLL. Previous studies focused on the PLL analysis intuitively believe that the positive feedback loop will deteriorate the dynamic performance of the PLL. However, this conclusion is not rigorous since only the dynamic of the PLL is considered and the theoretical analysis is insufficiency to reveal the influence of the positive feedback loop on system stability. In this paper, the impact of the frequency-dependent network on VSC stability is quantified in terms of the overall system based on the damping torque analysis. It is found that the influence of the positive feedback loop on stability depends on the parameters of the PLL and the damping of the dominant eigenvalues. Besides, an angular frequency feedback scheme is proposed to eliminate the adverse effect of the frequency-dependent network and enhance the stability of the VSC under weak grid conditions. Time-domain numerical simulations and reduced-scale experiments are performed to validate the effectiveness of the proposed scheme. [ABSTRACT FROM AUTHOR]

Virtual synchronous generator (VSG)-based control approaches for AC machine drivers have attracted much attention in recent years. The contradiction between the strong motor loading capacity and the small DC voltage fluctuation is disregarded in previous studies. A larger virtual inertia is required to raise the torque gain and drive the motor with heavier loads, thus resulting in greater DC voltage variations. A systematic method is proposed for the optimal design of the virtual inertia for VSG-based motor starting systems to achieve the maximal motor loading capacity and the low DC voltage fluctuation in this paper. Firstly, the relationship between the virtual inertia and the loading capacity is revealed on the basis of the closed-loop analysis. Considering the DC voltage variation, the constraint on the maximal value of the virtual inertia is proposed from the energy-balance perspective despite the unknown contribution of the DC capacitors to the virtual inertia. To fully exploit the energy storage capacity of the DC capacitors and raise the upper limit of the virtual inertia under the same permitted DC voltage variation, a modified DC voltage reference is introduced. Extensive simulation and experimental results are presented to validate the effectiveness of the proposed methods. [ABSTRACT FROM AUTHOR]

The high penetration of renewable energy generation (REG) systems influences the dynamics of power systems. Accurate transient simulations and dynamic models are indispensable for the research on the dynamic behavior of REG systems. A large-scale REG system consisting of numerous grid-connected inverters consumes a large amount of computation time, so a dynamic aggregated model is needed for efficient simulation. The aggregated model established by coherent equivalence fits the detailed model well, and thus it is widely used in the aggregation of large-scale dynamic systems. Presently, the key challenge of the application of the coherent-equivalence method is to identify inverters that have similar dynamic characteristics. The Hamilton principle expressed by Hamilton's action has a simple form and indicates the comprehensive dynamic characteristics of inverters. Thus, this paper proposes a coherent-equivalence method of inverters based on Hamilton's action. The proposed method is applied to a wind farm of 16 permanent magnet synchronous generator-based wind turbines for demonstration. Compared with the existing equivalence method without considering coherency, the proposed method shows advantages in effectiveness and accuracy. [ABSTRACT FROM AUTHOR]

Abstract Wind power ramps cause large-amplitude power fluctuation which harmfully affects the stability of power system's operation. As a new issue in wind power integration, the existing ramp forecasting methods still has some imperfection, e.g., harmonization on long-term trend and short-term precision. Therefore, an advanced method is proposed in this paper, mainly focus on improving the performance of wind power ramp prediction. This method utilizes wind power curve to build a primary model which can capture the trend of wind power variation. Then, prediction residual of the primary model is corrected by a MSAR (Markov-Switching-Auto-Regression) model which combining the advantages of AR models and Markov chain. Finally, an improved swinging door algorithm is applied to extract linear segments, and ramp definitions are used to detect ramp events. Actual wind farm data is used to test the proposed method. Comparison with traditional methods are presented, the numerical results validate that the proposed approach has improved performance not only on wind power prediction but also on ramp prediction. Highlights • An advanced approach is proposed to improve ramp prediction. • The approach contains wind power prediction, residual correction, ramp detection. • Primary models capture trend of wind power variation. • Details precision are corrected by MSAR correction prediction residual. [ABSTRACT FROM AUTHOR]

Summary: The voltage source converter (VSC) is often faced with unbalanced grid conditions that will degrade its performance because of the distorted current with a large amount of harmonics. One of the main parts of current distortion is the third‐order harmonics caused by the negative‐sequence voltage component at the fundamental frequency. The distorted output of the synchronous reference frame phase‐locked loop (SRF‐PLL) due to the unbalanced grid voltage is the main reason for the existence of the harmonics. This paper analyzes the mechanism of the generation of harmonics currents and proposes a compensation method for the PLL in VSCs based on the harmonic linearization method without changing the structure of SRF‐PLL. The proposed PLL can work properly under unbalanced grid conditions and has a good dynamic response. The third‐order current harmonics are reduced significantly by using the proposed PLL instead of the conventional SRF‐PLL without changing the current control strategy of VSC. The compensation method is verified by cycle‐by‐cycle circuit simulations and controller hardware‐in‐the‐loop experiments. [ABSTRACT FROM AUTHOR]

Prediction of wind power ramp events is important to the stability operation of power system, it is realized by combining wind power prediction of several continuous units for long-term power prediction, then using detecting algorithms to extract ramps. A prediction unit is a prediction time window. Its size impacts the accuracy of predicting ramps, and an optimization model is proposed to select the suitable window size. First, a swinging door algorithm is applied to extract ramp events from historical data. A model for optimizing the time window size is established based on the minimum non-ramp data in a ramp window. The solution of the proposed model is discussed, including the selection of variables, constraints and algorithm. The model presented in this paper is tested, and performance of selected time window is discussed. Computational analysis demonstrates the validity of the model. [ABSTRACT FROM AUTHOR]

The intermittent and fluctuation of wind power has a harmful effect on power grid. To direct system operators to mitigate the harm, a combined multivariate model is proposed to improve wind power prediction accuracy. This model is built through two stages. First, valid meteorological variables for prediction are selected by Granger causality testing approach, and reconstructed in homeomorphic phase spaces. Then each variable is taken to build a wind power prediction model independently, and their effect on prediction is illustrated through different kernel functions in support vector regression models. Second, prediction results of univariate models are taken as inputs of a combined model predicting wind power. The final model is multivariate and expressive to reflect the interactive effects of selected meteorological variables on wind power prediction. Four data mining algorithms are trained for selecting the model with high accuracy. The industrial data from wind farms is taken as the study case. Prediction of models at two stages are tested, and performance of the proposed model is validated better at four error metrics. [ABSTRACT FROM AUTHOR]

Nuclear receptor-binding SET domain 2 (NSD2) is a histone lysine methyltransferase (HKMTase), which is mainly responsible for the di-methylation of lysine residues on histones, which are involved in the regulation of various biological pathways. The amplification, mutation, translocation, or overexpression of NSD2 can be linked to various diseases. NSD2 has been identified as a promising drug target for cancer therapy. However, relatively few inhibitors have been discovered and this field still needs further exploration. This review provides a detailed summary of the biological studies related to NSD2 and the current progress of inhibitors, research, and describes the challenges in the development of NSD2 inhibitors, including SET (su(var), enhancer-of-zeste, trithorax) domain inhibitors and PWWP1 (proline-tryptophan-tryptophan-proline 1) domain inhibitors. Through analysis and discussion of the NSD2-related crystal complexes and the biological evaluation of related small molecules, we hope to provide insights for future drug design and optimization methods that will stimulate the development of novel NSD2 inhibitors. [Display omitted] • The structure and biological functions of NSD2 are summarized. • The potential role of NSD2 in different diseases is reviewed. • Cocrystal structures of small molecules with NSD2 and binding modes are highlighted. • Future strategies are suggested for the development of NSD2 inhibitors. [ABSTRACT FROM AUTHOR]

To reduce the harm of wind power ramp events in advance, an effective wind power ramp prediction system is needed. A new ramp prediction approach utilizing suitable selected time windows as units is proposed in this paper. Two risk factors are defined based on the performance analysis of ramp prediction, and the risk minimization principle is applied to build the risk model. Combining the correlation analysis and the statistical analysis of ramp duration, model constraints are studied. The optimal time window of industrial data is computed for ramp prediction based on a support vector regression model. Four evaluation indicators are chosen to verify that the proposed approach improves the performance of ramp prediction, and that the risk model is effective to select an optimal time window for prediction. [ABSTRACT FROM AUTHOR]

• The resilient operation of grid-connected converters (GCCs) is constrained by the grid-synchronization control, the converter current control and device failures. • The operation constraints of GCCs can be studied by eigenvalue analysis, impedance analysis, energy function analysis, phase portrait, equal area criterion and nonlinear time-domain analytical method. • The time-varying reference current limit based on the multi-timescale operating region can improve the resilience of GCCs effectively under grid faults. High power grid-connected converters exposed to disturbances such as grid faults and cyber-attacks may pose enormous threat to the safety of the power system. This predicament has led to a growing interest in analyzing the safe operation issues of GCCs. To further comprehend the operation issues and the corresponding analysis methods of grid-connected converters, this paper presents a thorough review of developed methods that describe the operation constraints and design the advanced controller from resilience perspective. From the paper, it can be known that the safe operation of grid-connected converters is restricted by the stability of the synchronization control, the current/power/voltage control and the fragility of electronic devices. Fully considering all the operating constraints, the current limiting strategies based on multi-timescale operation region is given to obtain a resilient converter. Finally, future resilient operation challenges are discussed. © 2017 Elsevier Inc. All rights reserved. [ABSTRACT FROM AUTHOR]

The fluctuation of wind cause threat to power grid, this paper proposed a wind power prediction method to improving this situation. The proposed method is based on time series and regime of switching kernel functions. First, the mutual information method and the false nearest neighbor method were used to calculate parameters to reconstruct the original data. The recurrence figure and the Lyapunov exponent were applied to verify that the time series data was from a chaotic system. Then, this paper proposed a prediction method based on the kernel function and also a switching regime based on the support vectors machine. The new prediction method combining these two parts was proposed to predict wind power. The comparison of wind power prediction by the proposed method and traditional methods were present, the results validated that the proposed method is feasible to predict wind power, and that the precision of prediction is improved, which will be useful for the future analysis of wind power. [ABSTRACT FROM AUTHOR]

A class of flavanone was found to improve melanogenesis in B16F10 mouse melanoma cell line, but little is known about its target. Herein we described the synthesis and bioevaluation of sixteen 3′,4′,7-trihydroxyflavanone analogues and further synthesized a novel fluorescent flavanone–BODIPY, which could improve melanogenesis in B16F10 cell line by selectively binding to its endoplasmic reticulum. The fluorescent flavanone–BODIPY was proved to be a valuable probe for studying the localization of intracellular flavanone on living cells. [ABSTRACT FROM AUTHOR]

Abstract: Background: Leptin is a circulating peptide hormone, encoded by the obesity (ob) gene, acting as a regulator of food intake via hypothalamic-mediated effects. Recent studies have shown that leptin and leptin receptor (ObR) are involved in the carcinogenesis and development of breast cancer. In addition, functional cross talk between leptin and estrogen signaling has been registered. Here, we investigated the relation of leptin and ObR expression with survival in women with breast cancer treated with the anti-estrogen tamoxifen, and whether leptin can interfere with the estrogen receptor alpha (ERα) and the effect of tamoxifen in breast cancer cells. Methods: The protein expression of leptin and ObRb in 114 breast cancer samples was evaluated by immunohistochemistry, quantified by Immunoreactivity Score (IRS) and correlated to survival and other clinicopathological features. The expression of ObRb in ERα positive MCF-7 breast cancer cells was examined by immunofluorescence and western blot. Leptin effect on cell proliferation was determined by MTT assay. The interference of leptin with tamoxifen on ERα degradation was studied by western blot and immunofluorescence. Effects of leptin on the transcriptional activity of ERα were explored using luciferase reporter assays. Results: Positive staining (Immunoreactivity Score, IRS≥1) of leptin and ObR isoform ObRb in breast cancer tissues were seen in 79.8% and 85.1% of patients respectively. In overall and in tamoxifen-treated breast cancer patients, leptin expression (IRS≥1) correlated with poor prognosis, (log-rank test, P =0.016, overall; P =0.031, tamoxifen-treated). Overexpressed ObRb was found by western blotting andimmunofluorescence in MCF-7 as well as in MDA-MB-231, T47D, and MDA-MB-435 cell lines. Tamoxifen (1000μM) significantly inhibited the proliferation of MCF-7 cells, degraded ERα and reduced ERα-dependent transcription from estrogen response element-containing promoter. On the contrary, simultaneous treatment with leptin (100ng/ml) significantly attenuated these effects, similar to the effects of estradiol. Conclusions: Leptin correlated significantly with poor prognosis in overall and tamoxifen-treated breast cancer patients. Leptin interferes with the action of tamoxifen in MCF-7 cells, at least partly, through inducing increased nuclear expression of ERα. Thus, leptin may contribute to tamoxifen resistance and consequently, leptin suppression could be a novel way of circumventing resistance to anti-estrogen treatment. [Copyright &y& Elsevier]

As a flexible and reliable way for distributed energy consumption and integration, the converters-dominated microgrid has attracted more and more attention recently. Owing to the low inertia and high nonlinearity of power converters, the islanded microgrid under large-signal disturbances is easily suffer to transient stability problems. To support the stable operation of microgrid, grid-forming converters are extensively investigated and applied. In this paper, an improved equal area criterion (IEAC) is proposed for the transient stability analysis of a simple microgrid equipped with both grid-following and grid-forming converters. Firstly, a simplified second-order model of the microgrid is established, which contains a nonlinear damping term relying on the power angle. Then, the limitation of conventional equal area criterion (EAC) for transient stability analysis is revealed, which completely ignores the unfavorable influence of negative damping and may lead to erroneous judgement. To fill this gap, an improved equal area criterion is proposed to derive the transient stability conditions for islanded microgrid, which could improve the estimation accuracy of stability boundaries. Moreover, impacts of system parameters and controller parameters on transient stability are studied, which provides useful guidelines for the parameter optimization of grid-forming and grid-following converters. Eventually, simulation and hardware-in-loop experiments are conducted to verify the effectiveness and superiority of the proposed method. [ABSTRACT FROM AUTHOR]

A process for the synthesis of aryl thioglycosides from the aryl thianthrenium salts and 1‐thiosugars is achieved by copper(I)‐mediated, photoredox‐catalyzed reactions. The desired products could be obtained in 32% to 78% yield after irradiation with 34 W blue light at room temperature. Various functional groups, especially including halogen groups, were well tolerated under standard reaction conditions. This strategy differs conceptually from all previous S‐glycosylations in that thiosugar functionality could be incorporated into complex natural products or drugs at a late stage site‐selectively, which has not been shown via aryl halides and aryldiazonium salts. [ABSTRACT FROM AUTHOR]

Background: We explored the potential novel anticancer mechanisms of 25‐hydroxyvitamin D (25(OH)D), a vitamin D metabolite with antitumour effects in breast cancer. It is stable in serum and is used to assess vitamin D levels in clinical practice. Transfer RNA‐derived small RNAs are small noncoding RNAs that generate various distinct biological functions, but more research is needed on their role in breast cancer. Methods: Small RNA microarrays were used to explore the novel regulatory mechanism of 25(OH)D. High‐throughput RNA‐sequencing technology was used to detect transcriptome changes after 25(OH)D treatment and tRF‐1‐Ser knockdown. RNA pull‐down and high‐performance liquid chromatography–mass spectrometry/mass spectrometry were used to explore the proteins bound to tRF‐1‐Ser. In vitro and in vivo functional experiments were conducted to assess the influence of 25(OH)D and tRF‐1‐Ser on breast cancer. Semi‐quantitative PCR was performed to detect alternative splicing events. Western blot assay and qPCR were used to assess protein and mRNA expression. Results: The expression of tRF‐1‐Ser is negatively regulated by 25(OH)D. In our breast cancer (BRCA) clinical samples, we found that the expression of tRF‐1‐Ser was higher in cancer tissues than in paired normal tissues, and was significantly associated with tumour invasion. Moreover, tRF‐1‐Ser inhibits the function of MBNL1 by hindering its nuclear translocation. Functional experiments and transcriptome data revealed that the downregulation of tRF‐1‐Ser plays a vital role in the anticancer effect of 25(OH)D. Conclusions: In brief, our research revealed a novel anticancer mechanism of 25(OH)D, unveiled the vital function of tRF‐1‐Ser in BRCA progression, and suggested that tRF‐1‐Ser could emerge as a new therapeutic target for BRCA. [ABSTRACT FROM AUTHOR]

As the crucial interface of renewable energy integration, the grid-tied inverter is a complicated system with a multi-timescale feature, containing both fast dynamics and slow dynamics that determine the system stability. However, previous researches on stability analysis mainly focus on the slow dynamics without considering the impact of fast dynamics, which may bring to inaccurate stability prediction. In this paper, the impact of fast dynamics on stability is investigated for grid-tied inverter from a physical perspective. Considering the dynamics of the current control loop and network, a two degrees-of-freedom oscillator model is firstly established to extract the fast dynamics separately. The damping torque analysis is then applied to analyze the impact of the extracted fast dynamics on the damping and spring coefficients of slow dynamics. Moreover, based on the fast dynamic analysis, a novel reduced-order model is proposed with the consideration of the dominant characteristics of fast dynamics, which improves the model accuracy without increasing the complexity. Eventually, both numerical evaluations and experiments are performed to validate the proposed analysis method. [ABSTRACT FROM AUTHOR]

In this article, a dual active bridge (DAB)–LLC–DCX dc–dc converter with integrated magnetics and shared rectifier is proposed for point of load applications, which is able to achieve tight voltage regulation, zero-voltage switching (ZVS) operation for all switches and zero-current switching operation for rectifier. The challenge of the proposed converter is the realization of ZVS operation for all the switches within full power range to achieve high efficiency and high reliability, which is beneficial for light load efficiency improvement of microprocessors. Therefore, with different input voltage range, a hybrid control strategy is proposed to realize ZVS operation for all switches of the proposed converter within full power range in this article. When at high input voltage, extended phase shift control is applied to extend the ZVS range. When at low input voltage, variable gain LLC converter is designed to regulate the voltage distribution among DAB converter and LLC converter for the ZVS operation of DAB converter. Besides, the charging/discharging of junction capacitors are added into consideration of ZVS analysis. The operating principle, design considerations, and control schemes are presented. Finally, the experimental results of an 80-W prototype verified the theoretical analysis. [ABSTRACT FROM AUTHOR]

Blood bone metabolic biomarkers are noninvasive indices for evaluating metabolic bone diseases. We investigated the relationships between blood bone metabolic biomarkers and anemia in chronic kidney disease (CKD) patients and analyzed the effects of parathyroidectomy (PTX) on the above indices. In this cross-sectional study, 100 healthy controls and 239 CKD patients, including 46 secondary hyperparathyroidism (SHPT) patients with PTX, were enrolled. Moreover, a prospective study was conducted in which 28 PTX patients were followed up. The degree of anemia was classified as mild, moderate, or severe based on the tertiles of hemoglobin (Hb) levels of the anemic CKD patients, with cutoff values of 83 g/L and 102 g/L. Bone metabolic biomarkers, including calcium (Ca), phosphorus (P), intact parathyroid hormone (iPTH), fibroblast growth factor 23 (FGF23), and α-klotho, were tested. The mean estimated glomerular filtration rate (eGFR) in CKD patients was 25.7 ± 36.0 ml/min/1.73 m2, and 84.10% of CKD patients had anemia. The baseline Hb levels in the mild, moderate, and severe anemia subgroups were 110.86 ± 5.99 g/L, 92.71 ± 5.96 g/L, and 67.38 ± 10.56 g/L, respectively. CKD patients had higher adjusted Ca, P, alkaline phosphatase (ALP), iPTH, and FGF23 levels and lower α-klotho levels than controls. Baseline adjusted Ca, P, iPTH, and α-klotho levels were associated with Hb levels in CKD patients. Blood adjusted Ca, P, and iPTH levels were correlated with anemia severity. After PTX (median interval: 6.88 months), anemia and high blood adjusted Ca, P, iPTH, and FGF23 levels were ameliorated, while α-klotho levels were increased. Blood adjusted Ca, P, iPTH, and α-klotho levels were correlated with Hb levels in CKD patients. Correction of bone metabolic disorders may be a therapeutic strategy for anemia treatment. [ABSTRACT FROM AUTHOR]

In this study, we not only optimized and improved the synthesis process of levobupivacaine hydrochloride (21) but also conducted a comprehensive exploration of critical industrial-scale production details, and a novel high-performance liquid chromatography (HPLC) analysis method was developed. Starting with the readily available and cost-effective (R,S)-N-(2,6-dimethylphenyl)piperidine-2-carboxamide (28) as the initial material and utilizing l-(–)-dibenzoyl tartaric acid (29) for chiral separation, and then through substitution and a salting reaction, levobupivacaine hydrochloride (21) was obtained with high purity (chemical purity of 99.90% and enantiomeric excess (ee) values of 99.30%). The total yield of the three steps was 45%. Structures of intermediates and the final product were confirmed using nuclear magnetic resonance (NMR) (1H NMR, 13C NMR), mass spectrometry (MS), and elemental analysis. The crystal structure of the final product was determined through differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). Furthermore, we evaluated the risk of the substitution reaction using a reaction calorimeter and accelerating rate calorimetry (ARC). This process offers the advantages of simple operation, greenness, safety, controllable quality, and cost-effectiveness. It provides reliable technical support for the industrial-scale production of levobupivacaine hydrochloride (21), which is of significant importance in meeting clinical demands. Pilot-scale production has already been successfully completed by China National Medicines Guorui Pharmaceutical Co., Ltd., with a production scale of 20 kg. [ABSTRACT FROM AUTHOR]

Purpose: Accurate preoperative parathyroid localization is important for successful parathyroidectomy (PTX). The aim of our study was to investigate whether SPECT/CT has enhanced effect in preoperative localization of parathyroids. Methods: In our retrospective cohort study, we evaluated the effects of technetium-99m methoxyisobutylisonitrile-single-photon emission computed tomography/computed tomography (99mTc-MIBI SPECT/CT) on preoperative parathyroid localization for 645 secondary hyperparathyroidism (SHPT) patients. Among them, 569 successful PTX patients were divided into group A (received 99mTc-MIBI scintigraphy, n = 175) and group B (received 99mTc-MIBI scintigraphy and SPECT/CT imaging, n = 394). Sensitivity, specificity, and consistency of two imaging methods in preoperative localization of parathyroids were compared. Results: Overall sensitivity and consistency were higher in group B, while there was no difference in specificity between the two groups. In group A, the sensitivity of 99mTc-MIBI was 50.00%, 77.11%, 61.76%, and 76.54% in the right upper gland (RU), right lower gland (RL), left upper gland (LU), and left lower gland (LL) subgroups, while the consistency was 52.00%, 76.57%, 61.71%, and 75.43%, respectively. In group B, the sensitivity of 99mTc-MIBI with SPECT/CT was 69.39%, 90.03%, 78.07%, and 84.27%, and the consistency was 69.54%, 88.32%, 78.43%, and 84.26%, respectively. The sensitivity and consistency in lower glands were higher than in upper glands in both groups. Sensitivity for eutopic parathyroid was higher in group B, while there was no difference for ectopic parathyroid. Conclusions:99mTc-MIBI SPECT/CT can increase the sensitivity and consistency of preoperative localization of eutopic parathyroid glands, and it can accurately locate ectopic parathyroid without sensitivity improvement. [ABSTRACT FROM AUTHOR]

At the occurrence of a permanent fault in a DC microgrid, apart from isolating the faulty section using a solid-state circuit breaker, the protection system should also have the fault position located so that repair crew can be sent to clear the fault and restore the isolated section. Available fault location methods are either influenced by network topology or need to add costly equipment. Located immediately next to the faulty line, the solid-state circuit breaker has the advantage of position required for injecting and detecting fault location signals, and it is isolated from the rest of the system by disconnector after fault interruption. Therefore, using the solid-state circuit breaker for fault location has a potential research value. However, it is rarely discussed in previous literatures. In this paper, an improved topology of the solid-state circuit breaker is proposed, which is able to inject signals into the isolated faulty line to determine fault position. By reusing components, the improved topology can achieve function expansion without much increasing the size and cost for fault protection, obtaining an accurate result uninfluenced by the network topology. Simulations and experiments are conducted in a 200 V/DC system to verify the effectiveness of the design. [ABSTRACT FROM AUTHOR]

Short-circuit faults are hazardous for high-power modular multilevel converters (MMCs). Hence, an accurate current calculation will be helpful for the design of the system protection. In this letter, a new method for the short-circuit current calculation based on discrete-time modeling is proposed. With commonly adopted nearest level modulation, the operating state during one period can be divided into several stages according to the number of submodules inserted into a bridge arm. Then, a piecewise analysis allows the construction of a new discrete-time model by recursion of the state variables stage-by-stage. From this model, the current evolution during a short-circuit fault can be accurately calculated when given an initial state. The effects of different fault occurrence times in one period are also calculated and discussed. Finally, PSCAD/EMTDC simulations and a circuit experiment with a single-phase five-level MMC verify the effectiveness of the proposed calculation method. [ABSTRACT FROM AUTHOR]

A cascaded H-bridge (CHB) converter-based medium or high-voltage motor drive system, that consists of three single-phase CHB chains, may suffer a severe second-harmonic ripple power issue. Oversizing dc capacitors and using active power decoupling control with additional active or passive components are the two possible ways to address this issue, but this is achieved at the expense of increased system cost and complexity. This paper proposes a power decoupling control to tackle this issue without using any extra components for regenerative CHB-based converters. By introducing a set of negative-sequence decoupling currents to the front-end pulsewidth-modulated rectifier of each submodule, the second-harmonic ripple power can be removed from the submodule dc capacitors, and all the ripple power in the transformer core legs can be counteracted without affecting the magnetic flux and the grid current. The decoupling current is derived from the input and output measurements of the CHB converter. It gives the minimal increase of the modulation index and has no impacts on the input and output power quality. The effectiveness of the proposed control is verified in simulations and a 72-kW experimental prototype. [ABSTRACT FROM AUTHOR]

Background: Patients who do not achieve a pathological complete response (pCR) after neoadjuvant systemic treatment (NST) have a significantly worse prognosis. A reliable predictor of prognosis is required to further subdivide non‐pCR patients. To date, the prognostic role in terms of disease‐free survival (DFS) between the terminal index of Ki‐67 after surgery (Ki‐67T) and the combination of the baseline Ki‐67 at biopsy before NST (Ki‐67B) and the percentage change in Ki‐67 before and after NST (Ki‐67C) has not been compared. Aim: This study aimed to explore the most useful form or combination of Ki‐67 that can provide prognostic information to non‐pCR patients. Patients and Methods: We retrospectively reviewed 499 patients who were diagnosed with inoperable breast cancer between August 2013 and December 2020 and received NST with anthracycline plus taxane. Results: Among all the patients, 335 did not achieve pCR (with a follow‐up period of ≥1 year). The median follow‐up duration was 36 months. The optimal cutoff value of Ki‐67C to predict a DFS was 30%. A significantly worse DFS was observed in patients with a low Ki‐67C (p < 0.001). In addition, the exploratory subgroup analysis showed relatively good internal consistency. Ki‐67C and Ki‐67T were considered as independent risk factors for DFS (both p < 0.001). The forecasting model combining Ki‐67B and Ki‐67C showed a significantly higher area under the curve at years 3 and 5 than Ki‐67T (p = 0.029 and p = 0.022, respectively). Conclusions: Ki‐67C and Ki‐67T were good independent predictors of DFS, whereas Ki‐67B was a slightly inferior predictor. The combination of Ki‐67B and Ki‐67C is superior to Ki‐67T for predicting DFS, especially at longer follow‐ups. Regarding clinical application, this combination could be used as a novel indicator for predicting DFS to more clearly identify high‐risk patients. [ABSTRACT FROM AUTHOR]

The multiport dc/dc converter with input independent output series structure is simple and efficient for photovoltaic (PV) applications. Through the cascade of sub-modules (SM), the converter has a high step-up ratio to connect MVdc bus. However, it has many ports which increase the risk of short-circuit faults. Therefore, this article proposes a fault ride-through (FRT) topology for multiport converter. When low-voltage ports are short-circuited, they can be isolated by blocking the switches of their own. The FRT topology can support the output voltage of faulty SMs to avoid the disconnection from MVdc bus. Other healthy ports can still generate power to MVdc bus. When the medium-voltage port is short-circuited, the FRT topology can quickly clear the fault current to prevent devices from being damaged. Due to the zero voltage switching, the proposed topology has higher efficiency. For medium-voltage fault, the FRT topology has faster fault clearing speed because more capacitors are reused. Finally, the proposed topology is verified by simulation and experiment. [ABSTRACT FROM AUTHOR]

Input-independent and output-series (IIOS) modular converters are characterized by high step-up ratio and independent maximum power point tracking and can therefore be used to integrate renewable energy into medium voltage dc grids. However, the associated power mismatch can lead to voltage imbalance of the submodules(SMs). At present, the only solution using no extra active switch involves the insertion of an LC-branch-based power balancing unit (PBU) between every two adjacent SMs (the SM and PBU share the switches). However, the considerable peak current of the shared switches threatens the security of the switches and increases the power loss. Therefore, this article considered the peak-current problem. A dual active bridge (DAB) converter was employed as the SM of the IIOS converter. The basis for the large peak current associated with the shared switches was analyzed and a peak current reducing method using the DAB inner-phase-shift control was proposed. The contribution of this article is that the current stress can be reduced and the power efficiency can be increased. A two-SM and 1000-W down-scaled experimental prototype was developed for verification of the theoretical analysis results. The peak currents and efficiencies with and without the proposed method were compared with experimental results. [ABSTRACT FROM AUTHOR]

Aims: As one of the mainstays of breast cancer therapy, chemotherapy inevitably induces neutropenia. In this study, we explored the role of PEG‐rhG‐CSF (pegylated recombinant human granulocyte colony‐stimulating factor) in the emergency treatment of chemotherapy‐induced grades 3–4 neutropenia. Methods: A total of 100 patients with breast cancer were randomized (1:1) into the study. Fifty patients randomized to the experimental group were treated with PEG‐rhG‐CSF after grades 3–4 neutropenia following the first cycle of chemotherapy, while 50 patients randomized to the control group received a daily injection of rhG‐CSF (recombinant human granulocyte colony‐stimulating factor). The primary endpoint was the recovery time of grades 3–4 neutropenia. Results: Compared with patients in the control group, the mean ± SD recovery time of grades 3–4 neutropenia and febrile neutropenia (FN) was significantly shorter for patients in the experimental group (grades 3–4, P =.000; grade 4, P =.000; FN, P =.038). There is no significant difference in the incidence of FN for the two groups. In the experimental group, the duration of grades 3–4 neutropenia in patients aged <60 years and ≥60 years was 2.15 and 3.20 days, respectively (P =.037). Adverse events (AEs) of any grade were reported in 37 (75.5%) and 28 (59.6%) patients from the two groups, respectively. No grade ≥3 AEs were reported. Conclusion: This study supported that the PEG‐rhG‐CSF was more effective and convenient than rhG‐CSF for treating grades 3–4 neutropenia and FN in patients with breast cancer and had manageable toxicity. [ABSTRACT FROM AUTHOR]

Under a short-circuit fault in low-voltage dc microgrid, solid-state circuit breaker (SSCB) assumes the responsibility of the quick and effective isolation of the faulted area, while its own safety and reliability depends on the overvoltage suppression ability of its snubber. For SSCB snubber design, however, traditional method suited for converter switch snubber cannot be directly applied, because SSCB snubber stresses more on its overvoltage suppression and fault current withstanding instead of snubber loss reduction. Therefore, this paper strives to build a snubber design method specialized for SSCB overvoltage suppression at bus fault interruption. A comprehensive and target-focused set of measurements is proposed and applied to the comparison of three RCD snubber candidates: charge–discharge type, discharge-suppressing type I, and discharge-suppressing type II. The set of measurements includes six indicators with peak SSCB voltage and peak bus current as the main indexes. After parameters are determined, the indicators of the three snubbers are compared, through which discharge-suppressing type I is selected as the most appropriate SSCB snubber. Experiments of the three snubbers have also been conducted in a ±200-V/dc system to verify the correctness of comparison results and the validity of discharge-suppressing type I for SSCB overvoltage suppression at dc-bus fault. [ABSTRACT FROM AUTHOR]

Negative-sequence current is required to be intentionally injected to support the power grid or compensate the imbalanced load in asymmetrical faults utilizing STATCOM. However, the extreme compensation range of negative-sequence current injection becomes complicated when grid voltage becomes asymmetrical. This article presents a novel off-line strategy for negative-sequence current compensation under two typical kinds of asymmetrical grid faults — single-phase voltage drop and double-phase voltage drop, with the following two benefits simultaneously: maximizing negative current compensation capacity; avoiding iterations and reducing computation burdens. In this paper, the mechanism of DC voltage balancing among three phases in STATCOM is analyzed and a new identification method of negative-sequence current compensation range is explored out. To simplify the calculation, this paper takes the ratio of negative-sequence reactive (Iq-) and active (Id-) current as a variable (s). In this way, the relationship between the extreme compensation range, asymmetrical voltage sag depth of power grid h is drawn with MATLAB. Different from the previous iterative method, the off-line identification method is applied to avoid huge iterations. By fitting the curve, the precise ranges of negative-sequence current compensation under different asymmetrical grid faults are approximated as simple polynomials, thus significantly reducing the computation burdens. Simulation and experimental results verify the practicability of the proposed compensation method. [ABSTRACT FROM AUTHOR]

Diamond has compelling advantages in power devices as an ultrawide-bandgap semiconductor. Using first-principles calculations, we systematically investigate the structural and electronic properties of hydrogen-terminated diamond (H-diamond) (111) van der Waals (vdW) heterostructures with graphite and hexagonal boron nitride (h-BN) layers. The graphite/H-diamond heterostructure forms a p-type ohmic contact and the p-type Schottky barrier decreases as the number of graphite layers increases. In contrast, the h-BN/H-diamond heterostructure exhibits semiconducting properties and a tunable type-II band alignment. Moreover, the charge transfer is concentrated at the interface with a large amount of charge accumulating on the C–H bonds on the H-diamond (111) surface, indicating the formation of a highly conductive two-dimensional hole gas (2DHG) layer. In a similar vein, the promising structural and electronic properties of graphite, h-BN, and H-diamond (111) in the graphite/h-BN/H-diamond (111) vdW heterostructure are well preserved upon their contact, while such heterostructure exhibits flexible band offset and Schottky contacts. These studies of interface engineering for H-diamond heterostructures are expected to advance the application of 2D materials in H-diamond field effect transistors, which is an important development in the design of surface transfer doping for 2DHG H-diamond devices. [ABSTRACT FROM AUTHOR]

The wide bandwidth impedance of grid and inverter are the critical parameters for small-signal stability analysis and control optimization of grid-tied inverter systems. The impedance measurement is an effective way to obtain the grid and inverter impedance by injecting a series of perturbations into the measured system. However, previous studies fail to fully consider the adverse grid voltage conditions; including harmonics, unbalance, frequency deviation, voltage sag, and phase jump; which may bring errors to the measured impedance. In this article, a cascaded delayed signal cancellation (CDSC)-based method is proposed to accurately obtain the impedance of the measured system under adverse grid voltage conditions. The proposed CDSC-based method is mainly composed of the perturbation extraction module (PEM) and frequency adaptive module (FAM). Different CDSC blocks are applied to implement the PEM and FAM to extract the injected perturbations adaptively, under various adverse grid voltage conditions. Simulation and hardware-in-the-loop experiment results are presented to validate the effectiveness and feasibility of the proposed impedance measurement method. [ABSTRACT FROM AUTHOR]

State-of-the-art capacitor online monitoring methods are designed for the whole dc bank. The capacitance or equivalent series resistance of the dc bank, as an aging indicator, is obtained by the sensors installed at the dc terminal, or derived from the state equation of the system. The difference of capacitor parameters from manufacturing and the arrangement of the dc bank will result in uneven thermal stress for the capacitors. Due to the restriction of the low stray inductance specification and high power density requirement, the traditional online monitoring circuits are hard to be designed for the single capacitor in the dc bank. In this article, a Rogowski coil based online monitoring circuit has been designed for the single capacitor in the dc bank. A new aging criterion has been established for aluminum electrolytic capacitors based on the accelerated aging test. To achieve a compact integration design, a six-layer printed-circuit-board-type Rogowski coil is designed under an optimized frequency. A 2-kW single-phase inverter is built to verify the theoretical analysis and practical performance of the monitoring circuit. [ABSTRACT FROM AUTHOR]

The development of a low-voltage dc distribution network has advanced the research on dc circuit breakers. Compared with the Z-source circuit breakers, T-source circuit breakers offer more advantages and greater research value. However, the existing bidirectional Z-source and T-source circuit breakers still suffer from limitations, such as high conduction loss, complex topology, and no physical isolation. Therefore, to solve these limitations, in this article, a novel low-loss bidirectional T-source circuit breaker with physical isolation is proposed. The proposed circuit breaker employs mechanical switches to reduce conduction loss, realize physical isolation, and change the power-flow direction. Since mechanical switches do not need to operate in the fault-clearing stage, the novel circuit breaker does not generate a dc arc and retains the fast self-shut-off characteristic of T-source circuit breakers. Moreover, soft-starting circuit and manual-tripping circuit are integrated into the proposed circuit breaker. The detailed analysis and design equations of the circuit breaker are provided. Finally, the capabilities of the novel circuit breaker are verified by simulation and experiment. [ABSTRACT FROM AUTHOR]

Sirtuin belongs to a family of coenzyme nicotinamide adenine dinucleotide (NAD+)-dependent histone deacetylases, which could be classified as seven isoforms (SIRT1-SIRT7). Recently, SIRT5 has drawn extensive attention due to its specific catalytic activity for low deacetylation activity but significant desuccinylation, demalonylation and deglutarylation activities. SIRT5 is thought to be closely related to some diseases such as cancer and neurodegenerative diseases. Herein, we present an overview of the structure and biological function of SIRT5 as well as the advances in SIRT5 inhibitors research. We also provide insights for the future exploitation of SIRT5 inhibitors. [Display omitted] • Targeting SIRT5 has emerged as a promising strategy for the treatment of cancer and neurodegenerative diseases. • The structure and biological function of SIRT5 are comprehensively summarized. • The different series of SIRT5 inhibitors are reviewed. • The design strategies for the development of SIRT5 inhibitors are discussed. [ABSTRACT FROM AUTHOR]

Grid-connected inverters inevitably operate under uncertain system parameters. These uncertain parameters such as inductance and capacitance are caused by device aging or uncertain grid conditions. And they will affect the stability margin of the inverter and bring an unstable operation risk even with a well initial design. The existing research articles mainly focus on robust stability analysis and control strategies while ignoring the influence of parameter distributions on operational risk. How to evaluate the instability risk of the inverter under multiparameter distribution is still an open question. In this article, the structured singular value (SSV) method is proposed to evaluate the robust stability of the inverter with multiparameter distributions. The distribution characteristics of uncertain parameters are briefly reviewed. The system model of a single-phase grid-connected inverter is established with the parameter distributions of the system key components. The probability of stable system operation can be quantified by the SSV method. Experiment and case study results verify the correctness and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

To realize a soft-switching inverter with small volume and high efficiency, a synchronous auxiliary resonant commutated pole (SARCP) soft-switching inverter with improved load adaptability is proposed, which only contains two auxiliary inductors. In one switching cycle, all commutation processes can be synchronously assisted by an auxiliary inductor. Soft switching is achievable for all switches of the SARCP inverter. Compared with the auxiliary resonant commutated pole (ARCP) inverter, the SARCP inverter has improved load adaptability, especially in the light load current condition, which is beneficial to reduce the total power loss and the dc-link capacitance. The equivalent circuits of the SARCP inverter are given under different operation modes. The operation principle, soft-switching implementation conditions, parameter optimization design methods, and the characteristics of the SARCP inverter are analyzed. Finally, simulation and experimental results verify the effectiveness of the SARCP inverter. [ABSTRACT FROM AUTHOR]

In the traditional dc distribution networks with both a low-voltage dc (LVdc) and a medium-voltage dc (MVdc) bus, dc units, such as photovoltaics solar, storage devices, and dc loads, are connected to the LVdc bus through LVdc converters, such as dc/dc boost converters and bidirectional buck–boost dc/dc converters. In this approach, no galvanic isolation is provided and two power conversion stages are needed between the dc units and the MVdc grid, hence leading to a high number of converters and higher costs. To address these shortcomings, this article proposes a novel multiport dc solid-state transformer (MDCSST) to interface these dc units directly to the MVdc bus. Multiple modules are connected in series on the medium-voltage side to the MVdc bus, whereas dc units are independently connected on the low-voltage side of the MDCSST. Compared with a traditional dc distribution network, the proposed scheme connects dc units to the MVdc bus without an extra converter or an LVdc bus, therefore, saving cost and reducing the number of converters. In addition, dc units are galvanically isolated by high-frequency transformers. The main challenge of the MDCSST is to resolve the voltage-imbalance problem on the MVdc side, which is caused by the dc units’ power differences. An LC branch is used to balance the voltages among the modules and to transfer their differential powers. Simulations and experiments were carried out to validate the proposed approach and verify the theoretical analysis. [ABSTRACT FROM AUTHOR]

This article proposed a grid-connected photovoltaic (PV) converter based on modular multilevel converter (MMC), which can realize long-distance dc transmission while realizing the local consumption of PV. In addition to the advantage that there is no PV power mismatch between the upper and lower arms, the isolation transformer couples the two submodules of the upper and lower arms on a three-port transformer, and the differential-mode components of the capacitor voltage ripples in the upper and lower arms can be canceled between each other. Besides, through the double fundamental frequency circulating current control, the power exchange among MMC phase units can be realized, thereby eliminating the common-mode component of the capacitor voltage ripple. Through the combination of topology and control strategy, the low-frequency components of the voltage ripple can be completely canceled. Since the decoupling capacitance is reduced dozens of times, the volume and cost of the system are significantly reduced. Therefore, the life and reliability of the system are increased. Simulation and experimental results verify the effectiveness of the proposed topology and its control strategy. [ABSTRACT FROM AUTHOR]

[Display omitted] Nicotinamide phosphoribosyltransferase (NAMPT) is a key rate-limiting enzyme in the nicotinamide adenine dinucleotide (NAD+) salvage pathway, primarily catalyzing the synthesis of nicotinamide mononucleotide (NMN) from nicotinamide (NAM), phosphoribosyl pyrophosphate (PRPP), and adenosine triphosphate (ATP). Metabolic diseases, aging-related diseases, inflammation, and cancers can lead to abnormal expression levels of NAMPT due to the pivotal role of NAD+ in redox metabolism, aging, the immune system, and DNA repair. In addition, NAMPT can be secreted by cells as a cytokine that binds to cell membrane receptors to regulate intracellular signaling pathways. Furthermore, NAMPT is able to reduce therapeutic efficacy by enhancing acquired resistance to chemotherapeutic agents. Recently, a few novel activators and inhibitors of NAMPT for neuroprotection and anti-tumor have been reported, respectively. However, NAMPT activators are still in preclinical studies, and only five NAMPT inhibitors have entered the clinical stage, unfortunately, three of which were terminated or withdrawn due to safety concerns. Novel drug design strategies such as proteolytic targeting chimera (PROTAC), antibody-drug conjugate (ADC), and dual-targeted inhibitors also provide new directions for the development of NAMPT inhibitors. In this perspective, we mainly discuss the structure, biological function, and role of NAMPT in diseases and the currently discovered activators and inhibitors. It is our hope that this work will provide some guidance for the future design and optimization of NAMPT activators and inhibitors. [ABSTRACT FROM AUTHOR]

Purpose: Studies show that axillary surgery can be potentially omitted in certain breast cancer patients who achieve breast pathologic complete response (pCR) after neoadjuvant systemic therapy (NST). However, potential differences between the ypT0 and ypTis subgroups remain to be explored. Furthermore, whether axillary surgery can be omitted in patients with clinically assessed positive axillary lymph nodes (cN+) remains unknown. This study was to evaluate the status of axillary lymph nodes for patients who achieved breast pCR after NST in the real-world study. Methods: This retrospective cohort study included 258 patients with early or locally advanced breast cancer who underwent breast and axillary surgery after NST. Clinical and pathologic data were compared between patients with breast pCR (ypT0/is) and those without breast pCR. Results: The rate of breast pCR after NST was 27.1% (70/258). Among the patients with initial cN0, the rate of axillary pCR was similar between the breast pCR and breast non-pCR groups (100% vs. 85.7%, P = 0.1543). Among those with breast pCR, the rate of axillary pCR was 100% in both the ypT0 and ypTis subgroups. Furthermore, among those with initial cN+, the rate of axillary pCR was higher in the breast pCR group than in the breast non-pCR group (82.7% vs. 22.9%, P < 0.0001). Among the patients with breast pCR, the rate of axillary pCR was higher in the ypT0 subgroup than in the ypTis subgroup (94.3% vs. 58.8%, P = 0.0034). Conclusion: Axillary surgery may potentially be omitted in patients with initial cN0 who achieve breast pCR (ypT0/is), and may also be considered for omission in patients with initial cN+ who achieve ypT0 (not ypTis). [ABSTRACT FROM AUTHOR]

Interactions of identical inverters in weak grids have received wide attentions. However, in a practical wind farm, parameters of grid-side inverters and lengths of collecting lines are not completely the same. In this case, a multi-inverter system is not symmetric, and thus the interaction mechanism could be more complicated than that of identical inverters. To investigate the interaction mechanism of differently parameterized inverters, this paper proposes a clustering-based modeling method, in which inverters with identical parameters are classified as one group. The clustering-based model allows for efficient stability assessment using three low-order transfer function matrices, instead of a full-order dynamic model. The root locus analysis is applied in the clustering-based model for stability analysis. Results show that the interconnection of distinct groups of inverters deteriorates common current stability, but has no impact on interactive current stability. The simulation and rtlab-based experimental results validate the effectiveness of the proposed model and the interaction mechanism of differently parameterized inverters. [ABSTRACT FROM AUTHOR]

Grid-connected converters may operate under grid fault conditions, such as the short-/open-circuit and the transmission line switching, which may be accompanied by a phase angle difference between the grid and converter. This variation will affect the normal operation of the converter since its phase-locked loop is not able to track the grid voltage phase angle immediately. In this article, an instability phenomenon with unregulated ac line current is identified in a modular multilevel converter (MMC) based high-voltage direct-current transmission system when there is a sudden phase angle change on the grid side. A set of analytical constraints is developed for the MMC in terms of the Lyapunov stability, the modulation index, and the maximum power transfer capability. Then, a multiconstraint operating region of the MMC under various phase disturbances is derived. Moreover, the parameter influence on the operating region is analyzed and two stability-enhancing methods for the MMC system are proposed. Finally, the boundaries of the operating region and the stability-enhancing methods are verified by simulations and laboratory measurements of three-phase grid-connected MMCs. [ABSTRACT FROM AUTHOR]

Flexible DC distribution networks have been widely developed because of their advantages of high efficiency, low cost, and easy access to renewable energy. However, as distribution networks have more ends than the two-terminal transmission line, it is more challenging to protect them and locate their faults. Therefore, this paper proposes a modified T-source circuit breaker to protect against DC faults. Based on the proposed circuit breaker, an integral fault location method using double-terminal asynchronous data is proposed. The accuracy of the algorithm is not affected by the fault resistance. There are no differential terms in the algorithm, which greatly reduces the sensitivity to noise. The integral algorithm can remain steady when the voltage and current are zero in oscillation and attenuation periods. This constitutes the main contribution of this paper. Finally, it is verified by simulation and experiment that the proposed circuit breaker can isolate the power source within a short time in the typical DC distribution network. Under a noise of 30 dB for simulation, the location error of the proposed algorithm is <0.4% when the fault resistance is 0.5 Ω–500 Ω. [ABSTRACT FROM AUTHOR]

Chylous leakage is a rare occurrence after breast surgery. Trauma to the thoracic duct and its main distribution may be the main cause of chylous leakage, but the cause of such an injury during breast surgery is unknown. We herein report the first case of chylous leakage from many minimal lymph ducts in a skin flap. In all, four cases of chylous leakage were observed out of 1 096 breast cancer patients who underwent axillary lymph node dissection. Of these four cases, three cases were successfully treated conservatively; however, surgical exploration was performed in the fourth case because of the large drainage volume. Furthermore, we reviewed the recently published studies on chylous leakage after breast surgery; 20 cases (our 4 cases included) have been reported in all. Of the 20 pooled cases, most were cured with conservative treatment and only three cases were cured with surgical treatment. [ABSTRACT FROM AUTHOR]

The large-capacity electrically excited synchronous machines are widely applied in modern industrial production, and starting issues have become one of the most concerns of the synchronous motors in practical operation, such as the long starting time, large current shock, and poor adaption to a wide-ranging load. To deal with these starting problems, many starting methods have been proposed in previous studies. Regrettably, high-performance methods depend on specific motor parameters and complex sensorless technology, while simple and low-cost methods are low performance. In this article, a modified back-to-back starting method is proposed for large-capacity synchronous machines based on virtual synchronous generator (VSG) technology, where the cascaded H-bridge converter is controlled as a VSG to replace the prime mover and synchronous generator of the conventional back-to-back starting system. To reduce the current shock, an initial relative-angle regulator is designed. To improve the robustness in the presence of a wide-ranging load, a damping torque branch is adopted. Extra speed sensors are no longer required since the VSG speed is directly applied in the feedback control loop. To validate the effectiveness of the proposed approach, extensive simulation and experimental results are presented. Compared with conventional approaches, the proposed starting method achieves faster response, smaller starting current, and stronger robustness. [ABSTRACT FROM AUTHOR]

An input-independent and output-series modular dc–dc converter with multiple input ports and high voltage conversion ratio can apply well to medium-voltage dc interface of distributed photovoltaics (PV). However, PV power mismatch will result in output voltage imbalance of the submodules (SMs), which is contrary to the standardized multimodule design. In this article, a multiport modular dc–dc converter with low-loss series LC power balancing unit (PBU) is proposed to address this problem. An isolated dc–dc converter is employed as the SM, which consists of full-bridge (FB) circuit on the PV side and half-bridge (HB) circuit on the grid side. Independent maximum power point tracking can be realized by controlling the phase shift between the FB and the HB, while voltage balancing (or power balancing) of SMs can be achieved by regulating the phase shift between adjacent HBs. Only one inductor and one capacitor are used in the PBU and all the switches of SM turn on with zero-voltage switching, which contributes to the low-cost and low-loss characteristic of the converter. Simulations and experiments are carried out to verify the validity of the theory. [ABSTRACT FROM AUTHOR]

A multiport dc/dc converter with cascaded submodules (SMs) can be employed in a photovoltaic (PV) power generation system for its high step-up ratio. Consisting of multiple low-voltage (LV) input ports and one high-voltage (HV) output port, the multiport converter is more likely to suffer short-circuit faults than a two-port converter. To ensure reliable operation of the converter, its short-circuit fault-tolerant capability should be necessarily considered. In this article, a short-circuit fault-tolerant topology for multiport cascaded dc/dc converter in the PV power generation system is proposed to satisfy the requirements of fault tolerance ability. When one or more short-circuit faults occur at LV ports, the proposed topology guarantees the normal operation of other fault-free SMs. When a short-circuit fault occurs at the HV port, the short-circuit fault current can be interrupted rapidly by the fault-tolerant topology, which protects the converter from a large current surge. The fault-tolerant ability of the proposed topology is verified by both simulation and experimental results. [ABSTRACT FROM AUTHOR]

The undesired nonlinear operation of phase-locked loops (PLL) is one of the main causes of transient instability in grid-connected converters. However, the stable operating region of PLL, knowing which is helpful for protection purposes, is hard to find due to the nonlinear characteristic of the transient process. In this article, the nonlinear characteristic of the PLL control loop relevant to the grid-connected converter operation is identified. The averaging method is applied to derive a time-domain expression for the PLL operation under disturbance. Based on the analytical expression, the transient response and related stability criterion are established, and the PLL design is improved while targeted to focus on various ac grid faults or disturbances. The results, applicable to transient stability enhancement, are verified by circuit simulations and experiments. [ABSTRACT FROM AUTHOR]