Flexible Voltage Support Control with Imbalance Mitigation Capability for Inverter-Based Distributed Generation Power Plants under Grid Faults

Wang, Yuewu,Yang, Ping,Xu, Zhirong The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.4

The high penetration level of inverter-based distributed generation (DG) power plants is challenging the low-voltage ride-through requirements, especially under unbalanced voltage sags. Recently, a flexible injection of both positive- (PS) and negative-sequence (NS) reactive currents has been suggested for the next generation of grid codes. This can enhance the ancillary services for voltage support at the point of common coupling (PCC). In light of this, considering distant grid faults that occur in a mainly inductive grid, this paper proposes a complete voltage support control scheme for the interface inverters of medium or high-rated DG power plants. The first contribution is the development of a reactive current reference generator combining PS and NS, with a feature to increase the PS voltage and simultaneously decrease the NS voltage, to mitigate voltage imbalance. The second contribution is the design of a voltage support control loop with two flexible PCC voltage set points, which can ensure continuous operation within the limits required in grid codes. In addition, a current saturation strategy is also considered for deep voltage sags to avoid overcurrent protection. Finally, simulation and experimental results are presented to validate the effectiveness of the proposed control scheme.

Flexible Voltage Support Control with Imbalance Mitigation Capability for Inverter-Based Distributed Generation Power Plants under Grid Faults

Yuewu Wang,Ping Yang,Zhirong Xu 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.4

The high penetration level of inverter-based distributed generation (DG) power plants is challenging the low-voltage ride-through requirements, especially under unbalanced voltage sags. Recently, a flexible injection of both positive- (PS) and negative-sequence (NS) reactive currents has been suggested for the next generation of grid codes. This can enhance the ancillary services for voltage support at the point of common coupling (PCC). In light of this, considering distant grid faults that occur in a mainly inductive grid, this paper proposes a complete voltage support control scheme for the interface inverters of medium or high-rated DG power plants. The first contribution is the development of a reactive current reference generator combining PS and NS, with a feature to increase the PS voltage and simultaneously decrease the NS voltage, to mitigate voltage imbalance. The second contribution is the design of a voltage support control loop with two flexible PCC voltage set points, which can ensure continuous operation within the limits required in grid codes. In addition, a current saturation strategy is also considered for deep voltage sags to avoid overcurrent protection. Finally, simulation and experimental results are presented to validate the effectiveness of the proposed control scheme.

The Hepatotoxicity and Testicular Toxicity Induced by Arecoline in Mice and Protective Effects of Vitamins C and E

Zhou, Jianhong,Sun, Qi,Yang, Zhirong,Zhang, Jie The Korean Society of Pharmacology 2014 The Korean Journal of Physiology & Pharmacology Vol.18 No.2

Arecoline is a major alkaloid of areca nuts which are widely chewed by southeast Asian and it manifests various toxic effects in different organs of human and animals. In this work, mature mice were treated by vitamins C plus E, arecoline, or both daily for four weeks. The results showed that arecoline significantly increased the levels of serum alkaline phosphatase (ALP), glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT) and significantly decreased the levels of reduced glutathione (GSH), glutathione-S-transferase (GST), superoxide dismutase (SOD) and catalase (CAT) in the liver tissues. Additionally, the body weight, testis weight, sperm counts, motility and normal sperms also were significantly decreased. The supplement of vitamins C and E can bring the activities of ALP and GPT to normal levels and partially restore the sperm counts compared to the arecoline-treated group but have no other positive effects. In conclusion, the vitamins C and E partially attenuated the arecoline-induced hepatotoxiciy but basically had on protective effects against the arecoline-induced testicular toxicity.

Quality Comparison of Sweet Flour Pastes Produced via Natural and Temperature-controlled Fermentation

Jing Deng,Huachang Wu,Zhirong Yang 한국식품과학회 2015 Food Science and Biotechnology Vol.24 No.6

The quality of sweet flour pastes (SFP) produced via natural and temperature-controlled fermentation was investigated. Temperature-controlled fermentation shortened the production time with no significant (p<0.05) differences between sample types in amino nitrogen, total acid, reducing sugar, and organic acid concentrations observed at the end of fermentation. Naturally fermented SFP exhibited higher concentrations of free amino acids than temperature-controlled fermented SFP. Analysis of SFP volatile compounds showed that naturally fermented SFP samples had higher concentrations of aroma constituents. Ethyl palmitate was the dominant ester in SFP with a 5.2× higher content of ethyl palmitate than for naturally fermented SFP. In addition, 4-ethyl guaiacol and 4-vinyl guaiacol were only identified in naturally fermented SFP samples. Temperature-controlled fermentation accelerates the production process, and naturally fermented SFP exhibited a higher quality.

1-Aminocyclopropane-1-Carboxylate Deaminase from Pseudomonas stutzeri A1501 Facilitates the Growth of Rice in the Presence of Salt or Heavy Metals

( Yunlei Han ),( Rui Wang ),( Zhirong Yang ),( Yuhua Zhan ),( Yao Ma ),( Shuzhen Ping ),( Liwen Zhang ),( Min Lin ),( Yongliang Yan ) 한국미생물 · 생명공학회 2015 Journal of microbiology and biotechnology Vol.25 No.7

1-Aminocyclopropane-1-carboxylate (ACC) deaminase, which is encoded by some bacteria, can reduce the amount of ethylene, a root elongation inhibitor, and stimulate the growth of plants under various environmental stresses. The presence of ACC deaminase activity and the regulation of ACC in several rhizospheric bacteria have been reported. The nitrogen-fixing Pseudomonas stutzeri A1501 is capable of endophytic association with rice plants and promotes the growth of rice. However, the functional identification of ACC deaminase has not been performed. In this study, the proposed effect of ACC deaminase in P. stutzeri A1501 was investigated. Genome mining showed that P. stutzeri A1501 carries a single gene encodingACC deaminase, designated acdS. The acdS mutant was devoid of ACC deaminase activity and was less resistant to NaCl and NiCl2 compared with the wild-type. Furthermore, inactivation of acdS greatly impaired its nitrogenase activity under salt stress conditions. It was also observed that mutation of the acdS gene led to loss of the ability to promote the growth of rice under salt or heavy metal stress. Taken together, this study illustrates the essential role of ACC deaminase, not only in enhancing the salt or heavy metal tolerance of bacteria but also in improving the growth of plants, and provides a theoretical basis for studying the interaction between plant growth-promoting rhizobacteria and plants.

Preparation and Characterization of a Novel pH-Sensitive Coated Microsphere for Duodenum-Specific Drug Delivery

Dan Zhou,Yuan Huang,Xi Zhu,Yang Wang,Yun Jin,Xuefan Xu,Tingting Fan,Yan Liu,Zhirong Zhang 대한약학회 2012 Archives of Pharmacal Research Vol.35 No.5

The aim of this study is to develop a duodenum-specific drug delivery system on the basis of a pH-sensitive coating and a mucoadhesive inner core for eradication of Helicobacter pylori (H. pylori) in the ulcer duodenum. Hydroxypropyl methylcellulose acetate maleate (HPMCAM) was used as the pH-sensitive material, which dissolves around pH 3.0. The mucoadhesive microspheres loaded with furazolidone (FZD-ad-MS) were prepared by the emulsification-solvent evaporation method using Carbopol 971NP as the mucoadhesive polymer. The prepared pH-sensitive coated mucoadhesive microspheres (AM-coated-MS) were characterized in regards to particle size, drug loading efficiency, morphological change, drug stability, drug release and in vitro anti-H. pylori activity. The particle size was 160.97 ± 47.24 μm and 336.44 ± 129.34 μm, and the drug content was 42.33 ± 3.43% and 10.96 ± 1.29% for FZD-ad-MS and AM-coated-MS, respectively. The morphological changes in different pH media were characterized by scanning electron microscopy (SEM). HPMCAM coating improved the stability of the FZD-ad-MS and these particles were expected to remain intact until their arrival in the duodenum. The drug release was extremely suppressed at pH 1.2 for AM-coated-MS, but increased at pH 4.0 after regeneration of FZD-ad-MS. In addition, FZD-ad-MS exhibited excellent anti-H. pylori activity in vitro. Thus, the HPMCAM-coated microspheres developed in this study hold great promise for use as a duodenum-specific drug delivery system for H. pylori clearance.

The Hepatotoxicity and Testicular Toxicity Induced by Arecoline in Mice and Protective Effects of Vitamins C and E

Jianhong Zhou,Jie Zhang,Qi Sun,Zhirong Yang 대한약리학회 2014 The Korean Journal of Physiology & Pharmacology Vol.18 No.2

Arecoline is a major alkaloid of areca nuts which are widely chewed by southeast Asian and itmanifests various toxic effects in different organs of human and animals. In this work, mature micewere treated by vitamins C plus E, arecoline, or both daily for four weeks. The results showed thatarecoline significantly increased the levels of serum alkaline phosphatase (ALP), glutamate oxaloacetatetransaminase (GOT), glutamate pyruvate transaminase (GPT) and significantly decreased thelevels of reduced glutathione (GSH), glutathione-S-transferase (GST), superoxide dismutase (SOD) andcatalase (CAT) in the liver tissues. Additionally, the body weight, testis weight, sperm counts, motilityand normal sperms also were significantly decreased. The supplement of vitamins C and E can bringthe activities of ALP and GPT to normal levels and partially restore the sperm counts compared tothe arecoline-treated group but have no other positive effects. In conclusion, the vitamins C and Epartially attenuated the arecoline-induced hepatotoxiciy but basically had on protective effects againstthe arecoline-induced testicular toxicity.

Antibacterial Activity of Organic Acids in Aqueous Extracts from Pine Needles (Pinus massoniana Lamb.)

Su Feng,Weicai Zeng,Fan Luo,Jian Zhao,Zhirong Yang,Qun Sun 한국식품과학회 2010 Food Science and Biotechnology Vol.19 No.1

Pine needle (Pinus massoniana Lamb.) of large quantity in China and health benefit makes its application on pharmaceutical and food industry in high demand. The chemical composition of pine needle aqueous extract (PNAE) analyzed by gas chromatograph-mass spectrometry revealed that among more than 10 compounds in PNAE,organic acids were over 76.92%, with acetic acid being 25.20%, hexadecanoic acid 18.19%, and 2-methoxy-4-vinylphenol 16.44%. Ultra-performance liquid chromatography-mass spectrometry disclosed other 5 short chain organic acids, including citric acid, succinic acid, malonic acid, malic acid, and oxalic acid. The antibacterial activity of PNAE on common spoilages and pathogenic bacteria showed that the growth of Bacillus subtilis, Staphylococcus aureus, Bacillus cereus, Micrococcus luteus, Escherichia coli, and Proteus vulgaris were inhibited significantly, with minimum inhibitory concentrations and minimum bactericidal concentrations being 3.8-15 and 7.5-30 mg/mL, respectively. Our findings suggested that pine needles with effective and safe antibacterial components possess the potential to be developed into efficacious natural antiseptic products for food disinfection and medical purpose.

Composition and Antioxidant Activity of Water-Soluble Polysaccharides from Tuber indicum

Qiang Luo,Jie Zhang,Liang Yan,Yuanlin Tang,Xiang Ding,Zhirong Yang,Qun Sun 한국식품영양과학회 2011 Journal of medicinal food Vol.14 No.12

Crude water-soluble Chinese truffle Tuber indicum polysaccharide (TIP) was extracted from the fruiting bodies with water and then successively purified by DEAE–cellulose 52 and Sephadex G-100 column chromatography,yielding two major polysaccharide fractions: TIP1-1 and TIP2-1. High-performance gel permeation chromatography analysis showed that the average molecular sizes of TIP1-1 and TIP2-1 were approximately 1.75×10⁴Da and 5.73×10³ Da, respectively. Monosaccharide component analysis by gas chromatography indicated that TIP1-1 was composed of mannose,glucose, galactose, and rhamannose in the respective molar ratio of 3.93:1.24:0.75:1.26 and that TIP2-1 contained mannose,glucose, and arabinose in the respective molar ratio of 5.27:1.44:0.43. The antioxidant activity analyses revealed that TIP1-1and TIP2-1 possessed considerable antioxidant activity. Compared with TIP1-1, which has a higher molecular weight and contains no uronic acid, TIP2-1 exhibited a protective effect on PC12 cells injured by H₂O₂and a higher scavenging activity against free radicals. The relative effects of the lower molecular size, the presence of uronic acid, and the antioxidant activity of TIP2-1 appear to be significant. Accordingly, the Chinese truffle T. indicum might serve as an effective antioxidative healthcare food and source of natural antioxidants.

Impact of NR1I2, adenosine triphosphate-binding cassette transporters genetic polymorphisms on the pharmacokinetics of ginsenoside compound K in healthy Chinese volunteers

Zhou, Luping,Chen, Lulu,Wang, Yaqin,Huang, Jie,Yang, Guoping,Tan, Zhirong,Wang, Yicheng,Liao, Jianwei,Zhou, Gan,Hu, Kai,Li, Zhenyu,Ouyang, Dongsheng The Korean Society of Ginseng 2019 Journal of Ginseng Research Vol.43 No.3

Background: Ginsenoside compound K (CK) is a promising drug candidate for rheumatoid arthritis. This study examined the impact of polymorphisms in NR1I2, adenosine triphosphate-binding cassette (ABC) transporter genes on the pharmacokinetics of CK in healthy Chinese individuals. Methods: Forty-two targeted variants in seven genes were genotyped in 54 participants using Sequenom MassARRAY system to investigate their association with major pharmacokinetic parameters of CK and its metabolite 20(S)-protopanaxadiol (PPD). Subsequently, molecular docking was simulated using the AutoDock Vina program. Results: ABCC4 rs1751034 TT and rs1189437 TT were associated with increased exposure of CK and decreased exposure of 20(S)-PPD, whereas CFTR rs4148688 heterozygous carriers had the lowest maximum concentration ($C_{max}$) of CK. The area under the curve from zero to the time of the last quantifiable concentration ($AUC_{last}$) of CK was decreased in NR1I2 rs1464602 and rs2472682 homozygous carriers, while $C_{max}$ was significantly reduced only in rs2472682. ABCC4 rs1151471 and CFTR rs2283054 influenced the pharmacokinetics of 20(S)-PPD. In addition, several variations in ABCC2, ABCC4, CFTR, and NR1I2 had minor effects on the pharmacokinetics of CK. Quality of the best homology model of multidrug resistance protein 4 (MRP4) was assessed, and the ligand interaction plot showed the mode of interaction of CK with different MRP4 residues. Conlusion: ABCC4 rs1751034 and rs1189437 affected the pharmacokinetics of both CK and 20(S)-PPD. NR1I2 rs1464602 and rs2472682 were only associated with the pharmacokinetics of CK. Thus, these hereditary variances could partly explain the interindividual differences in the pharmacokinetics of CK.