A New Direct Power Control Strategy for NPC Three-Level Voltage Source Rectifiers Using a Novel Vector Influence Table Method

Xia, Chang-Liang,Xu, Zhe,Zhao, Jia-Xin The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.1

This paper proposes a novel direct power control (DPC) strategy for neutral-point-clamped (NPC) three-level rectifiers, to directly control the active power, the reactive power and the neutral point potential of the rectifiers by referring to three pre-calculated vector influence tables and minimizing an objective function. In the three vector influence tables, the influences of different voltage vectors on the active power, the reactive power and the neutral-point potential are shown explicitly. A conceptual description and control algorithm of the proposed controller are presented in this paper. Then, numerical simulations and experiments are carried out to validate the proposed method. Both the simulation and experimental results show that good performances during both the steady-state and transient operating conditions are achieved. As a result, the proposed strategy has been proven to be effective for NPC three-level rectifiers.

Combined fine-needle aspiration with core needle biopsy for assessing thyroid nodules: a more valuable diagnostic method?

Zhe Chen,Jia-jia Wang,Dong-ming Guo,Yu-xia Zhai,Zhuo-zhi Dai,Hong-hui Su 대한초음파의학회 2023 ULTRASONOGRAPHY Vol.42 No.2

Purpose: This study aimed to evaluate the diagnostic value of combined fine-needle aspiration (FNA) with core needle biopsy (CNB) in thyroid nodules. Methods: FNA and CNB were performed simultaneously on 703 nodules. We compared the proportions of inconclusive results and the diagnostic performance for malignancy among FNA, CNB, and combined FNA/CNB for different nodule sizes. Results: Combined FNA/CNB showed lower proportions of inconclusive results than CNB for all nodules (2.8% vs. 5.7%, P<0.001), nodules ≤1.0 cm (4.9% vs. 7.3%, P=0.063), nodules >1.0 cm (2.0% vs. 5.0 %, P<0.001), nodules ≤1.5 cm (3.8% vs. 7.9 %, P<0.001), and nodules >1.5 cm (2.1% vs. 3.9 %, P=0.016). The sensitivity of combined FNA/CNB in predicting malignancy was significantly higher than that of CNB (89.0% vs. 80.0%, P<0.001) and FNA (89.0% vs. 58.1%, P<0.001) for all nodules. Within American College of Radiology Thyroid and Imaging Reporting and Data System grades 4-5, in the subgroup of nodules ≤1.5 cm, combined FNA/ CNB showed the best sensitivity in predicting malignancy (91.4%), significantly higher than that of CNB (81.0%, P<0.001) and FNA (57.8%, P<0.001). However, in the subgroup of nodules >1.5 cm, the difference between combined FNA/CNB and CNB was not significant (84.2% vs. 78.9%, P=0.500). Conclusion: Regardless of nodule size, combined FNA/CNB tended to yield lower proportions of inconclusive results than CNB or FNA alone and exhibited higher performance in diagnosing malignancy. The combined FNA/CNB technique may be a more valuable diagnostic method for nodules ≤1.5 cm and nodules with a risk of malignancy than CNB and FNA alone.

Corporate Social Responsibility and Unsecured Debt: Evidence from China

Xia CHEN,Zhe MA,Jiayu SHI,Bingyan TU,Songtao XU 한국유통과학회 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.11

This study aims to investigate whether Corporate Social Responsibility (CSR) performance can help companies gain more bank unsecured loans. Additionally, this study analyzes the moderating effect of firm size and industry characteristics. Data was collected through the case of companies listed on the Shanghai Stock Exchange or the Shenzhen Stock Exchange in China between 2009 and 2018 with 5373 firmyear observations. The results of multivariable regression analysis show that good CSR performance exhibits a strong positive impact on unsecured debt, including short-term, long-term, and total unsecured debt, which indicates that corporate with good CSR performance can borrow more unsecured debt. further research shows that this effect is more pronounced for small enterprises and firms operating in heavy-polluting industries. Additionally, research on the impact mechanism finds that good CSR performance can help mitigate information asymmetry between borrower and lender, reduce moral hazard of borrower, and obtain support from key stakeholders, and therefore reduces the risk of default. The findings of this study suggest that firms with good CSR performance exhibit a preference for unsecured debt, but decline to provide collateral for debt. Overall, we emphasize and illustrate the important role of corporate CSR in bank credit financing.

Communities of ammonia oxidizers at different stages of Spartina alterniflora invasion in salt marshes of Yangtze River estuary

Fei Xia,Jemaneh Zeleke,Qiang Sheng,Ji-Hua Wu,Zhe-Xue Quan 한국미생물학회 2015 The journal of microbiology Vol.53 No.5

Spartina alterniflora, an aggressive invasive plant species at the estuarine wetlands of China’s coasts, has become a major threat to the natural ecosystems. To understand its potential influence on nitrification processes, the community structures and abundance of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) were investigated using 454-pyrosequencing and quantitative real-time PCR (qPCR) in S. alterniflora invading salt marsh sediments at the Yangtze River estuary in Chongming island, Shanghai, China. Copy numbers of archaeal and bacterial ammonia monooxygenase subunit A (amoA) genes did not show accordant shifts with S. alterniflora invasion in the two sampling sites. However, the copy numbers of archaeal amoA gene were higher in summer than in spring. Phylogenetic analysis indicated that more than 90% of the archaeal and 92% of the bacterial amoA gene sequences were closely related to marine group I.1a and the clusters 13 and 15 in Nitrosospira lineage, respectively. The effect of different seasons (spring and summer) was important for the abundance variation of AOA, while different stages of S. alterniflora invasion did not show significant effect for both AOA and AOB. Variation of AOA community was significantly related to total carbon (TC) and sulfate concentration (P < 0.05), whereas the AOB community was significantly related to sulfate concentration, total nitrogen (TN), TC and pH (P < 0.05). In conclusion, the abundance and diversity of ammonia oxidizing microbial communities were not strongly affected by S. alterniflora invasion.

Roles of Signaling Pathways in the Epithelial-Mesenchymal Transition in Cancer

Liu, Xia,Yun, Fen,Shi, Lin,Li, Zhe-Hai,Luo, Nian-Rong,Jia, Yong-Feng Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.15

The epithelial-mesenchymal transition (EMT) is a cellular process though which an epithelial phenotype can be converted into a phenotype of mesenchymal cells. Under physiological conditions EMT is important for embryogenesis, organ development, wound repair and tissue remodeling. However, EMT may also be activated under pathologic conditions, especially in carcinogenesis and metastatic progression. Major signaling pathways involved in EMT include transforming growth factor ${\beta}(TGF-{\beta})$, Wnt, Notch, Hedgehog and other signaling pathways. These pathways are related to several transcription factors, including Twist, Smads and zinc finger proteins snail and slug. These interact with each other to provide crosstalk between the relevant signaling pathways. This review lays emphasis on studying the relationship between EMT and signaling pathways in carcinogenesis and metastatic progression.

hOGG1, p53 Genes, and Smoking Interactions are Associated with the Development of Lung Cancer

Cheng, Zhe,Wang, Wei,Song, Yong-Na,Kang, Yan,Xia, Jie Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.5

This study aimed to investigate the effects of Ser/Cys polymorphism in hOGG1 gene, Arg/Pro polymorphism in p53 gene, smoking and their interactions on the development of lung cancer. Ser/Cys polymorphism in hOGG1 and Arg/Pro polymorphism in p53 among 124 patients with lung cancer and 128 normal people were detected using PCR-RFLP. At the same time, smoking status was investigated between the two groups. Logistic regression was used to estimate the effects of Ser/Cys polymorphism and Arg/Pro polymorphisms, smoking and their interactions on the development of lung cancer. ORs (95% CI) of smoking, hOGG1 Cys/Cys and p53 Pro/Pro genotypes were 2.34 (1.41-3.88), 2.12 (1.03-4.39), and 2.12 (1.15-3.94), respectively. The interaction model of smoking and Cys/Cys was super-multiplicative or multiplicative, and the OR (95% CI) for their interaction item was 1.67 (0.36 -7.78). The interaction model of smoking and Pro/Pro was super-multiplicative with an OR (95%CI) of their interaction item of 5.03 (1.26-20.1). The interaction model of Pro/Pro and Cys/Cys was multiplicative and the OR (95%CI) of their interaction item was 0.99 (0.19-5.28). Smoking, hOGG1 Cys/Cys, p53 Pro/Pro and their interactions may be the important factors leading to the development of lung cancer.

Construction of Z-scheme W18O49/NiAl-LDH heterojunction with photothermal effect for photocatalytic reduction of CO2

Cheng Xia,Rui-Tang Guo,Zhen-rui Zhang,Chen-yuan Fan,Yu-zhe Liu,Yu-cheng Lin,Chu-fan Li,Wei-Guo Pan 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.128 No.-

Recently, the photocatalytic CO2 reduction technology is an effective solution to remit the energy crisis. Inorder to improve the photocatalytic performance, Z-scheme W18O49/NiAl-LDH composite catalysts wereprepared by hydrothermal method. Fortunately, the prepared catalysts revealed excellent photocatalyticperformance under the simulated sunlight, and CO and CH4 could be detected in the reduction products. WO/LDH-0.5 catalyst possessed the optimal activity, with CO and CH4 yield of 37.09 and 8.01 lmol g-1h1separately, which were 7.9 and 3.6 times that of NiAl-LDH monomer. In addition, W18O49 endowedW18O49/NiAl-LDH catalysts with photothermal effect, which raised the surface temperature andfacilitated the catalytic reaction. Meanwhile, the Z-scheme heterojunction composed of flower-likeNiAl-LDH and urchin-like W18O49 accelerated the separation of photoexcited carriers and enhanced theredox ability. Through a series of characterizations and investigations, this work is promising to breaknew ground for the design of photocatalysts with photothermal effect.

Study of dry friction characteristics of silicon nitride full ceramic ball bearing with PEEK-based cage

Jian Sun,Zhe Zhang,Zhongxian Xia,Xin Fang,Renyun Guan,Guangxiang Zhang,Jinmei Yao 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.3

In order to investigate the influence of polyether ether ketone (PEEK) and its composite cage on the dry friction characteristicsof silicon nitride all-ceramic ball bearings, this paper firstly conducted a theoretical analysis of silicon nitride deep groove ballbearings subjected to radial load under dry friction conditions, and then conducted dry friction tests and simulation studieson PEEK, CF30 and PVX cage silicon nitride full ceramic ball bearings. The test results show that the temperature rise ofCF30 and PVX cage bearings is higher than that of PEEK cage bearings; the relationship between the root mean square valueof vibration of PEEK, CF30 and PVX cage bearings is PEEK cage bearings > CF30 cage bearings > PVX cage bearings; thesimulation model has good accuracy; Surface morphology analysis of the PVX cage bearing after the test show that thetransfer film has the effect of wear reduction and lubrication on the bearing. The results of the study have positive significancefor the research of transfer film lubricated bearings and the selection of cage materials.

A New Direct Power Control Strategy for NPC Three-Level Voltage Source Rectifiers Using a Novel Vector Influence Table Method

Chang-Liang Xia,Zhe Xu,Jia-Xin Zhao 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.1

This paper proposes a novel direct power control (DPC) strategy for neutral-point-clamped (NPC) three-level rectifiers, to directly control the active power, the reactive power and the neutral point potential of the rectifiers by referring to three pre-calculated vector influence tables and minimizing an objective function. In the three vector influence tables, the influences of different voltage vectors on the active power, the reactive power and the neutral-point potential are shown explicitly. A conceptual description and control algorithm of the proposed controller are presented in this paper. Then, numerical simulations and experiments are carried out to validate the proposed method. Both the simulation and experimental results show that good performances during both the steady-state and transient operating conditions are achieved. As a result, the proposed strategy has been proven to be effective for NPC three-level rectifiers.

Metabolic Characteristic of the Liver of Dairy Cows during Ketosis Based on Comparative Proteomics

Xu, Chuang,Wang, Zhe,Liu, Guowen,Li, Xiaobing,Xie, Guanghong,Xia, Cheng,Zhang, Hong You Asian Australasian Association of Animal Productio 2008 Animal Bioscience Vol.21 No.7

The objective of the present study was to identify differences in the expression levels of liver proteins between healthy and ketotic cows, establish a liver metabolic interrelationship of ketosis and elucidate the metabolic characteristics of the liver during ketosis. Liver samples from 8 healthy multiparous Hostein cows and 8 ketotic cows were pooled by health status and the proteins were separated by two-dimensional-electrophoresis (2D-E). Statistical analysis of gels was performed using PDQuest software 8.0. The differences in the expression levels of liver proteins (p<0.05) between ketotic and healthy cows were identified by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF-TOF) tandem mass spectrometry. Five enzymes/proteins were identified as being differentially expressed in the livers of ketotic cows: expression of 3-hydroxyacyl-CoA dehydrogenase type-2 (HCDH), acetyl-coenzyme A acetyltransferase 2 (ACAT) and elongation factor Tu (EF-Tu) were down-regulated, whereas that of alpha-enolase and creatine kinase were up-regulated. On the basis of this evidence, it could be presumed that the decreased expression of HCDH, which is caused by high concentrations of acetyl-CoA in hepatic cells, in the livers of ketotic cows, implies reduced fatty acid ??oxidation. The resultant high concentrations of acetyl-CoA and acetoacetyl CoA would depress the level of ACAT and generate more ??hydroxybutyric acid; high concentrations of acetyl-CoA would also accelerate the Krebs Cycle and produce more ATP, which is stored as phosphocreatine, as a consequence of increased expression of creatine kinase. The low expression level of elongation factor Tu in the livers of ketotic cows indicates decreased levels of protein synthesis due to the limited availability of amino acids, because the most glucogenic amino acids sustain the glyconeogenesis pathway; thus increasing the level of alpha-enolase. Decreased protein synthesis also promotes the conversion of amino acids to oxaloacetate, which drives the Krebs Cycle under conditions of high levels of acetyl-CoA. It is concluded that the livers of ketotic cows possess high concentrations of acetyl-CoA, which through negative feedback inhibited fatty acid oxidation; show decreased fatty acid oxidation, ketogenesis and protein synthesis; and increased gluconeogenesis and energy production.