Modified Modular Multilevel Converter with Submodule Voltage Fluctuation Suppression

Huang, Xin,Zhang, Kai,Kan, Jingbo,Xiong, Jian The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.4

Modular multilevel converters (MMCs) have been receiving extensive research interest in high/medium-voltage applications due to its modularity, scalability, reliability, high-voltage capability, and excellent harmonic performance. Submodule capacitors are usually rather bulky because they have to withstand fundamental frequency voltage fluctuations. To reduce the capacitance of these capacitors, this study proposes a modified MMC with an active power decoupling circuit within each submodule. The modified submodule contains an auxiliary half bridge, with its capacitor split in two. Also, the midpoints of the half bridge and the split capacitors are connected by an inductor. With this modified submodule, the fundamental frequency voltage fluctuation can be suppressed to a great extent. The second-order voltage fluctuation, which is the second most significant component in submodule voltage fluctuations, is removed by the proper control of the second-order circulating current. Consequently, the submodule capacitance is significantly reduced. The viability and effectiveness of the proposed new MMC are confirmed by the simulation and experimental results. The proposed MMC is best suited for medium-voltage applications where power density is given a high priority.

The 14-3-3 Gene Function of Cryptococcus neoformans Is Required for its Growth and Virulence

( Jingbo Li ),( Yun C. Chang ),( Chun Hua Wu ),( Jennifer Liu ),( Kyung J. Kwon Chung ),( Sheng He Huang ),( Hiro Shimada ),( Rob Fante ),( Xiaowei Fu ),( Ambrose Jong ) 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.5

Cryptococcus neoformans is a life-threatening pathogenic yeast that causes devastating meningoencephalitis. The mechanism of cryptococcal brain invasion is largely unknown, and recent studies suggest that its extracellular microvesicles may be involved in the invasion process. The 14-3-3 protein is abundant in the extracellular microvesicles of C. neoformans, and the 14-3-3-GFP fusion has been used as the microvesicle’s marker. However, the physiological role of 14-3-3 has not been explored. In this report, we have found that C. neoformans contains a single 14-3-3 gene that apparently is an essential gene. To explore the functions of 14-3-3, we substituted the promoter region of the 14-3-3 with the copper-controllable promoter CTR4. The CTR4 regulatory strain showed an enlarged cell size, drastic changes in morphology, and a decrease in the thickness of the capsule under copper-enriched conditions. Furthermore, the mutant cells produced a lower amount of total proteins in their extracellular microvesicles and reduced adhesion to human brain microvascular endothelial cells in vitro. Proteomic analyses of the protein components under 14-3-3-overexpressed and -suppressed conditions revealed that the 14-3-3 function(s) might be associated with the microvesicle biogenesis. Our results support that 14-3-3 has diverse pertinent roles in both physiology and pathogenesis in C. neoformans. Its gene functions are closely relevant to the pathogenesis of this fungus.

Extraction of Pigment from Sugarcane Juice Alcohol Wastewater and Evaluation of Its Antioxidant and Free Radical Scavenging Activities

Jingbo Li,Lei Liang,Jingrong Cheng,Yunan Huang,Ming-Jun Zhu,Shizhong Liang 한국식품과학회 2012 Food Science and Biotechnology Vol.21 No.5

Pigment was extracted to decolor the sugarcane juice alcohol wastewater and its antioxidant activities were evaluated. The pigment was extracted using ion exchange fiber along with macroporous resin D-101 as the absorbent and an ethanol-water mixture (6:4, v/v) as the eluent. Total flavonoid and phenolic contents of the pigment were determined. DPPH radical scavenging ability and reducing power of 1.0 mg/mL of the pigment were approximately 78.5 and 16.8%, respectively, compared to 1.0 mg/mL of the tea polyphenol (positive control). The hydroxyl radical scavenging ability of 10.0 mg/mL of the pigment was about 92.5% compared to that of positive control. The DPPH radical scavenging ability of the pigment was enhanced significantly with thermal treatment at 70 and 100oC. The result shows the proposed procedure can be effective to decolor such wastewater and to get antioxidative pigment.

Modified Modular Multilevel Converter with Submodule Voltage Fluctuation Suppression

Xin Huang,Kai Zhang,Jingbo Kan,Jian Xiong 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.4

Modular multilevel converters (MMCs) have been receiving extensive research interest in high/medium-voltage applications due to its modularity, scalability, reliability, high-voltage capability, and excellent harmonic performance. Submodule capacitors are usually rather bulky because they have to withstand fundamental frequency voltage fluctuations. To reduce the capacitance of these capacitors, this study proposes a modified MMC with an active power decoupling circuit within each submodule. The modified submodule contains an auxiliary half bridge, with its capacitor split in two. Also, the midpoints of the half bridge and the split capacitors are connected by an inductor. With this modified submodule, the fundamental frequency voltage fluctuation can be suppressed to a great extent. The second-order voltage fluctuation, which is the second most significant component in submodule voltage fluctuations, is removed by the proper control of the second-order circulating current. Consequently, the submodule capacitance is significantly reduced. The viability and effectiveness of the proposed new MMC are confirmed by the simulation and experimental results. The proposed MMC is best suited for medium-voltage applications where power density is given a high priority.

Open‑circuit fault diagnosis of three‑phase PWM rectifier circuits based on transient characteristics and random forest classification

RenZhong Shan,JingBo Yang,ShengLi Huang 전력전자학회 2024 JOURNAL OF POWER ELECTRONICS Vol.24 No.1

Fault diagnosis is becoming increasingly important in improving the reliability of power electronic devices. The research in this paper focuses on the issue of the faulty operation that can occur after partial IGBT open-circuit faults in three-phase PWM rectifier circuits. To promptly and effectively diagnose faults and to determine their locations, a fault diagnosis method based on transient characteristics and random forest classification is proposed. First, the characteristics of single and double IGBT open-circuit faults in three-phase PWM rectifier circuits are analyzed. It is discovered that these faults do not immediately manifest. Instead, they exhibit fault characteristics in the corresponding time sequence. Then the random forest classifier is trained using transient fault samples from the three-phase PWM rectifier circuit. Finally, generalized testing is performed on data that was not involved in the training process, with an accuracy rate of over 98%. The use of frequency distribution graphs for visual analysis of the diagnostic results solves the problem of diagnosing multiple IGBT open-circuit faults.

Pterostilbene Protects Against Lipopolysaccharide/D-Galactosamine-Induced Acute Liver Failure by Upregulating the Nrf2 Pathway and Inhibiting NF-κB, MAPK, and NLRP3 Inflammasome Activation

Erli Zhang,Jingbo Huang,Kun Wang,Qinlei Yu,Chao Zhu,Hua Ren 한국식품영양과학회 2020 Journal of medicinal food Vol.23 No.9

The purpose of this study was to evaluate the protective effect of pterostilbene (Psb) against lipopolysaccharide and D-galactosamine (L/D)-induced acute liver failure (ALF) in mice and its potential mechanisms. Histology of liver was detected by H&E staining. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels in serum and malondialdehyde (MDA), myeloperoxidase (MPO), glutathione (GSH), and superoxide dismutase (SOD) contents in liver were examined using detection kits. The levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) secretion were detected by ELISA. Meanwhile, MAPK, NF-κB, NLRP3 inflammasome, and Nrf2 were assessed by western blotting. Our findings showed that pretreatment with Psb protected against L/D-induced ALF by lowering the lethality, improving liver histology, reducing ALT, AST, IL-6, IL-1β, TNF-α, MDA, and MPO levels, and boosting liver GSH content and SOD activity. Moreover, Psb pretreatment effectively suppressed inflammation by decreasing NLRP3 inflammasome, MAPK, and NF-κB pathway activations. Moreover, Psb pretreatment efficiently enhanced the expression of several antioxidant enzymes, mainly depending on Nrf2 activation. This was the first study to demonstrate that Psb protects against L/D-induced ALF by inactivating MAPK, NF-κb, and NLRP3 inflammasome and upregulating the Nrf2 signaling pathway, indicating a potential therapeutic application for ALF treatment.

Inhibitory Effects of Salidroside on Nitric Oxide and Prostaglandin E2 Production in Lipopolysaccharide-Stimulated RAW 264.7 Macrophages

Bocui Song,Guoren Huang,Ying Xiong,Jingbo Liu,Linli Xu,Zhenning Wang,Gen Li,Jing Lu,Shuang Guan 한국식품영양과학회 2013 Journal of medicinal food Vol.16 No.11

The aim of this study was to evaluate the effect of salidroside on lipopolysaccharide (LPS)-induced nitric oxide (NO) and prostaglandin E2 (PGE2) production in RAW 264.7 macrophages and related anti-inflammatory mechanism. PGE2 production was measured by enzyme-linked immunosorbent assay (ELISA); NO production was tested by Griess reagent. Inducible nitric oxidesynthase (iNOS) and COX-2 were determined by RT-PCR and Western blot analysis; IjB and P-IjB protein express were detected by Western blot analysis; cytosolic free Ca2+ ([Ca2 + ]i)was measured by a fluorescent microscope. The data showed salidroside inhibited LPS-induced NO and PGE2 production and reduced iNOS and COX-2 protein expression in RAW 264.7 macrophages. Consistent with these observations, salidroside inhibited LPS-induced cytosolic free Ca2 + concentration ([Ca2 +]i) elevation. In addition, we further investigated signal transduction mechanisms and found that the activation of NF-jBwas suppressed by salidroside in a dose-dependent manner. These results suggest that salidroside suppresses NO and PGE2 production by inhibiting iNOS and COX-2 protein expression, level of [Ca2 + ]i, and activation of NF-jB signal transduction pathway.

Cadherin 17 Nanobody-Mediated Near-Infrared-II Fluorescence Imaging-Guided Surgery and Immunotoxin Delivery for Colorectal Cancer

Youbin Ding,Runhua Zhou,Guangwei Shi,Yuke Jiang,Zhifen Li,Xiaolong Xu,Jingbo Ma,Jingnan Huang,Chunjin Fu,Hongchao Zhou,Huifang Wang,Jiexuan Li,Zhiyu Dong,Qingling Yu,Kexin Jiang,Yehai An,Yawei Liu,Yil 한국생체재료학회 2024 생체재료학회지 Vol.28 No.00

Surgery and targeted therapy are of equal importance for colorectal cancer (CRC) treatment. However, complete CRC tumor resection remains challenging, and new targeted agents are also needed for efficient CRC treatment. Cadherin 17 (CDH17) is a membrane protein that is highly expressed in CRC and, therefore, is an ideal target for imaging-guided surgery and therapeutics. This study utilizes CDH17 nanobody (E8-Nb) with the near-infrared (NIR) fluorescent dye IRDye800CW to construct a NIR-II fluorescent probe, E8-Nb-IR800CW, and a Pseudomonas exotoxin (PE)-based immunotoxin, E8-Nb-PE38, to evaluate their performance for CRC imaging, imaging-guided precise tumor excision, and antitumor effects. Our results show that E8-Nb-IR800CW efficiently recognizes CDH17 in CRC cells and tumor tissues, produces high-quality NIR-II images for CRC tumors, and enables precise tumor removal guided by NIR-II imaging. Additionally, fluorescent imaging confirms the targeting ability and specificity of the immunotoxin toward CDH17-positive tumors, providing the direct visible evidence for immunotoxin therapy. E8-Nb-PE38 immunotoxin markedly delays the growth of CRC through the induction of apoptosis and immunogenic cell death (ICD) in multiple CRC tumor models. Furthermore, E8-Nb-PE38 combined with 5-FU exerts synergistically antitumor effects and extends survival. This study highlights CDH17 as a promising target for CRC imaging, imaging-guided surgery, and drug delivery. Nanobodies targeting CDH17 hold great potential to construct NIR-II fluorescent probes for surgery navigation, and PE-based toxins fused with CDH17 nanobodies represent a novel therapeutic strategy for CRC treatment. Further investigation is warranted to validate these findings for potential clinical translation.