Search

Your search keyword '"Zhang, Zhenxia"' showing total 216 results
Start Over Author "Zhang, Zhenxia"
216 results on '"Zhang, Zhenxia"'

15. Investigation of NWC-induced electron precipitation and theoretical simulation

Author

Zhang, Zhenxia, Li, Xinqiao, Wang, Chenyu, and Chen, Lunjin

Subjects
Physics - Space Physics
Abstract

Enhancement of the electron fluxes in the inner radiation belt, which is induced by the powerful North West Cape (NWC) very-low-frequency (VLF) transmitter, have been observed and analyzed by several research groups. However, all of the previous publications have focused on NWC-induced >100-keV electrons only, based on observations from the Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) and the Geostationary Operational Environmental Satellite (GOES) satellites. Here, we present flux enhancements with 30--100-keV electrons related to NWC transmitter for the first time, which were observed by the GOES satellite at night. Similar to the 100--300-keV precipitated-electron havior, the low energy 30--100-keV electron precipitation is primarily located east of the transmitter. However, the latter does not drift eastward to the same extent as the former, possibly because of the lower electron velocity. The 30--100-keV electrons are distributed in the L=1.8--2.1 shell range, in contrast to the 100--300-keV electrons which are at L=1.67--1.9. This is consistent with the perspective that the energy of the VLF-wave-induced electron flux enhancement decreases with higher L-shell values. We expand upon the rationality of the simultaneous enhancement of the 30--100- and 100--300-keV electron fluxes through comparison with the cyclotron resonance theory for the quasi-linear wave-particle interaction. In addition, we interpret the asymmetry characteristics of NWC electric power distribution in north and south hemisphere by ray tracing model. Finally, we present considerable discussion and show that good agreement exists between the observation of satellites and theory.

Published
2016
Full Text
View/download PDF

20. Study of typical space wave-particle coupling events possibly related with seismic activity

Author

Zhang, Zhenxia, Wang, Chenyu, Shen, Xuhui, Li, Xinqiao, and Wu, Shugui

Subjects
Physics - Geophysics, Physics - Space Physics
Abstract

Based on the DEMETER satellite, we found two space wave-particle coupling events during February 2010 taking place in the range of McIlwain parameter $L$($1.27\sim1.37$). There are strong spatial and temporal correlation between the particle bursts(PBs) and the electromagnetic disturbances of the coupling events. The two PBs show different energy spectrum characteristics, while the corresponding electromagnetic disturbances concentrated on different frequencies range. In agreement with the prediction of the theory of wave-particle interaction, we conclude that the two wave-particle interactions can be probably explained as following: one is electron dominant precipitation with energy of $0.09\sim0.2$ MeV induced by VLF electromagnetic wave with the frequency of $14\sim20$ kHz, and another is proton dominant precipitation with energy of $0.65\sim2.85$ MeV induced by VLF electromagnetic wave with the frequency of $\le 100$ Hz. For the first time, those particle bursts origin, from electron or proton detected by the Instrument for the Detection of Particles(IDP) on board, is inferred by theory calculation, although the Instrument has no ability to identify the particle species.

Published
2014
Full Text
View/download PDF

23. DEMETER Satellite Observations of Particle Burst Prior to Chile Earthquake

Author

Zhang, Zhenxia, Li, Xinqiao, Shen, Xuhui, Ma, Yuqian, Chen, Huaran, You, Xinzhao, and Yuan, Yahong

Subjects
Physics - Geophysics
Abstract

The lithosphere activity during seismogenic or occurrence of one earthquake may emit electromagnetic wave which propagate to ionosphere and radiation belt, then induce disturbance of electric and magnetic field and the precipitation of high energy charged particles. This paper, based on the data detected by DEMETER satellite, present the high energy charged particle burst(PB) with 4 to 6 times enhancement over the average value observed about ten days days before Chile earthquake. The obvious particle burst was also observed in the northern hemisphere mirror points conjugate of epicenter and no PB events in different years over the same epicenter region was found. The energy spectra of the PBs are different from the one averaged within the first three months in 2010. At the same time, the disturbance of the VLF electric spectrum in ionosphere over the epicenter detected by the DEMETER satellite are also observed in the same two orbits. Those observations from energetic PB and VLF electric spectrum disturbance demonstrates the coupling relation among the electromagnetic wave emitted by seismic activity, energetic particle and electric field in ionosphere. We eliminate the possible origination of PB including magnetic burst and Solar activities. Finally we think the PB is likely to be related to Chile earthquake and can be taken as the precursor of this earthquake.

Published
2010

24. Association of the TNF‐α‐308G>A gene polymorphism with left ventricular geometry and functional abnormalities in obstructive sleep apnea subjects.

Author

Chen, Shuqiong, Wang, Jian, Shui, Wen, Xing, Xueqing, Zhang, Zhenxia, and Hou, Ran

Abstract

Objective: Tumor necrosis factor‐α (TNF‐α) can induce left ventricular remodeling. In this study, we investigated whether the TNF‐α‐308G>A polymorphism is associated with left ventricular geometry (LVG) and left ventricular functional abnormalities in obstructive sleep apnea (OSA) subjects. Methods: Two hundred and seventy‐eight subjects were enrolled. Echocardiography and genetic data were assessed in all patients. Geometric patterns of the left ventricle were determined from the relative wall thickness and left ventricular mass index (LVMI). Genetic analysis for the TNF‐α‐308G>A SNP rs1800629 was identified by Sanger sequencing. The correlations of the TNF‐α‐308G>A polymorphism with LVG and left ventricular function were analyzed by difference analysis and logistic regression. Results: The chi‐square test showed that there were differences in genotype distributions among the four groups (p = 0.033), such that the frequency of GA+AA genotypes was significantly higher in the concentric hypertrophy group than in the normal geometry group (p < 0.05). Independent sample T tests showed that the GA+AA genotypes had higher IVST, LVPWT, LVMI, E/e' values, and lower e' values than those of the GG genotype (p < 0.05). Logistic regression analysis showed that the TNF‐α‐308G>A polymorphism was independently correlated with eccentric hypertrophy (OR = 2.456, p = 0.047) and concentric hypertrophy (OR = 2.456, p = 0.047). Conclusion: In OSA patients, the TNF‐α‐308G>A polymorphism was linked to LVG and abnormal left ventricular diastolic function, suggesting that the TNF‐α‐308G>A polymorphism may have an important influence on LVG alterations. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

30. Calycosin inhibits breast cancer cell migration and invasion by suppressing EMT via BATF/TGF-β1

Author

Zhang Zhenxia, Lin Min, Yuzhong Zheng, Fenglian Yang, Liu Yaqun, Peikui Yang, Junli Wang, and Zikai Chen

Subjects
Aging, Epithelial-Mesenchymal Transition, calycosin, Down-Regulation, Breast Neoplasms, Vimentin, BATF, Transforming Growth Factor beta1, chemistry.chemical_compound, breast cancer, Breast cancer, Downregulation and upregulation, Cell Movement, medicine, Humans, Neoplasm Invasiveness, Neoplasm Metastasis, skin and connective tissue diseases, Transcription factor, Cell Proliferation, Gene knockdown, Base Sequence, biology, Chemistry, TGFβ1, Cell Biology, medicine.disease, invasion and metastasis, Isoflavones, Gene Expression Regulation, Neoplastic, Basic-Leucine Zipper Transcription Factors, Calycosin, Disease Progression, MCF-7 Cells, biology.protein, Cancer research, Female, Chromatin immunoprecipitation, Research Paper
Abstract

In this study, we investigated the effects of calycosin on breast cancer cell progression and their underlying mechanisms. Calycosin dose- and time-dependently inhibited proliferation, migration, and invasion by T47D and MCF-7 breast cancer cells by downregulating basic leucine zipper ATF-like transcription factor (BATF) expression. Moreover, BATF promoted breast cancer cell migration and invasiveness by increasing TGFβ1 mRNA and protein levels. Bioinformatics analysis, dual luciferase reporter assays, and chromatin immunoprecipitation assays confirmed the presence of BATF-binding sites in the promoter sequence of TGFβ1 gene. Calycosin treatment inhibited epithelial-mesenchymal transition (EMT) of breast cancer cells by significantly increasing E-cadherin levels and decreasing N-cadherin, Vimentin, CD147, MMP-2, and MMP-9 levels through downregulation of BATF and TGFβ1. TGFβ1 knockdown reduced the migration and invasiveness of BATF-overexpressing breast cancer cells, whereas incubation with TGFβ1 enhanced the migration and invasiveness of calycosin-treated breast cancer cells. Our findings demonstrated that calycosin inhibited EMT and progression of breast cancer cells by suppressing BATF/TGFβ1 signaling. This suggests calycosin would be a promising therapeutic option for breast cancer patients.

Published
2021

35. The Possible Seismo-Ionospheric Perturbations Recorded by the China-Seismo-Electromagnetic Satellite

Author

Zhima, Zeren, primary, Yan, Rui, additional, Lin, Jian, additional, Wang, Qiao, additional, Yang, Yanyan, additional, Lv, Fangxian, additional, Huang, Jianping, additional, Cui, Jing, additional, Liu, Qinqin, additional, Zhao, Shufan, additional, Zhang, Zhenxia, additional, Xu, Song, additional, Liu, Dapeng, additional, Chu, Wei, additional, Zhu, Keying, additional, Sun, Xiaoying, additional, Lu, Hengxin, additional, Guo, Feng, additional, Tan, Qiao, additional, Zhou, Na, additional, Yang, Dehe, additional, Huang, He, additional, Wang, Jie, additional, and Shen, Xuhui, additional

Published
2022
Full Text
View/download PDF

38. Current Status and Main Scientific Outcomes of the CSES Mission

Author

ZEREN, Zhima, primary, HUANG, Jianping, additional, LIU, Dapeng, additional, YANG, Yanyan, additional, YAN, Rui, additional, ZHAO, Shufan, additional, ZHANG, Zhenxia, additional, LIN, Jian, additional, CUI, Jing, additional, CHU, Wei, additional, WANG, Qiao, additional, LU, Hengxin, additional, XU, Song, additional, GUO, Feng, additional, YANG, Dehe, additional, ZHOU, Na, additional, LIU, Qinqin, additional, HUANG, He, additional, WANG, Jie, additional, TAN, Qiao, additional, LI, Wenjing, additional, LÜ, Fangxian, additional, ZHU, Keying, additional, and SHEN, Xuhui, additional

Published
2022
Full Text
View/download PDF

39. Microbial phospholipase D: Identification, modification and application

Author

Zhang Zhenxia, Ming Chen, Wanmeng Mu, Wei Xu, Tao Zhang, Wenli Zhang, and Cuie Guang

Subjects
0106 biological sciences, 0303 health sciences, Phospholipase D, Rational design, SUPERFAMILY, Phosphatidic acid, 01 natural sciences, 03 medical and health sciences, chemistry.chemical_compound, Hydrolysis, Biochemistry, chemistry, 010608 biotechnology, Phosphatidylcholine, Substrate specificity, lipids (amino acids, peptides, and proteins), 030304 developmental biology, Food Science, Biotechnology, Thermostability
Abstract

Background Phospholipids (PLs) are major components of biological membranes in all living organisms and have been widely applied in the food, pharmaceutical and cosmetic industries for their numerous nutritional and bioactive functions. Traditionally, PLs have been extracted from egg yolk and soybean using organic solvents; however, the high cost of purification poses a limitation for their further application. Scope and approach Recently, growing attention has been paid to the biological production of PS using phospholipase D (PLD, EC 3.1.4.4). PLD, belonging to PLD superfamily, can catalyze both the hydrolysis of phosphatidylcholine (PC) to phosphatidic acid (PA) and the transphosphatidylation of PC to PL when an appropriate acceptor alcohol is provided. Transphosphatidylation plays a critical role in preparation of functional PLs. Key findings and conclusions To date, approximate 9 genera of microorganisms have been identified and used to prepare PLD. The overall crystal structure PLD and a two-step reaction mechanism have been proposed. In addition, examples of successful modification of PLD such as altering substrate specificity, enhancing thermostability and improving activity have been discussed. In the future, research aimed at searching for novel PLDs with a higher transphosphatidylation activity, determining the crystal structure of more PLDs, and improving the catalytic performance of PLDs through a rational design for the production of PLs should be conducted. Last but not least, more novel and biodegradable solvents for the production of PLD are essential for their further application in daily use.

Published
2020

46. The Mechanisms of Yu Ping Feng San in Tracking the Cisplatin-Resistance by Regulating ATP-Binding Cassette Transporter and Glutathione S-Transferase in Lung Cancer Cells

Author

Du, Yingqing, Zheng, Yuzhong, Yu, Ciel Xiaomei, Zhong, Lishan, Li, Yafang, Wu, Baomeng, Hu, Weihui, Zhu, Elsa Wanyi, Xie, Venus Wei, Xu, Qitian, Zhan, Xingri, Huang, Yamiao, Zeng, Liyi, Zhang, Zhenxia, Liu, Xi, Yin, Jiachuan, Zha, Guangcai, Chan, Kelvin, Tsim, Karl Wah Keung, Du, Yingqing, Zheng, Yuzhong, Yu, Ciel Xiaomei, Zhong, Lishan, Li, Yafang, Wu, Baomeng, Hu, Weihui, Zhu, Elsa Wanyi, Xie, Venus Wei, Xu, Qitian, Zhan, Xingri, Huang, Yamiao, Zeng, Liyi, Zhang, Zhenxia, Liu, Xi, Yin, Jiachuan, Zha, Guangcai, Chan, Kelvin, and Tsim, Karl Wah Keung

Abstract

Cisplatin is one of the first line anti-cancer drugs prescribed for treatment of solid tumors; however, the chemotherapeutic drug resistance is still a major obstacle of cisplatin in treating cancers. Yu Ping Feng San (YPFS), a well-known ancient Chinese herbal combination formula consisting of Astragali Radix, Atractylodis Macrocephalae Rhizoma and Saposhnikoviae Radix, is prescribed as a herbal decoction to treat immune disorders in clinic. To understand the fast-onset action of YPFS as an anti-cancer drug to fight against the drug resistance of cisplatin, we provided detailed analyses of intracellular cisplatin accumulation, cell viability, and expressions and activities of ATP-binding cassette transporters and glutathione S-transferases (GSTs) in YPFS-treated lung cancer cell lines. In cultured A549 or its cisplatin-resistance A549/DDP cells, application of YPFS increased accumulation of intracellular cisplatin, resulting in lower cell viability. In parallel, the activities and expressions of ATP-binding cassette transporters and GSTs were down-regulated in the presence of YPFS. The expression of p65 subunit of NF-kappa B complex was reduced by treating the cultures with YPFS, leading to a high ratio of Bax/Bcl-2, i.e. increasing the rate of cell death. Prim-O-glucosylcimifugin, one of the abundant ingredients in YPFS, modulated the activity of GSTs, and then elevated cisplatin accumulation, resulting in increased cell apoptosis. The present result supports the notion of YPFS in reversing drug resistance of cisplatin in lung cancer cells by elevating of intracellular cisplatin, and the underlying mechanism may be down regulating the activities and expressions of ATP-binding cassette transporters and GSTs.

Published
2021

48. The Mechanisms of Yu Ping Feng San in Tracking the Cisplatin-Resistance by Regulating ATP-Binding Cassette Transporter and Glutathione S-Transferase in Lung Cancer Cells

Author

Du, Yingqing, primary, Zheng, Yuzhong, additional, Yu, Ciel Xiaomei, additional, Zhong, Lishan, additional, Li, Yafang, additional, Wu, Baomeng, additional, Hu, Weihui, additional, Zhu, Elsa Wanyi, additional, Xie, Venus Wei, additional, Xu, Qitian, additional, Zhan, Xingri, additional, Huang, Yamiao, additional, Zeng, Liyi, additional, Zhang, Zhenxia, additional, Liu, Xi, additional, Yin, Jiachuan, additional, Zha, Guangcai, additional, Chan, Kelvin, additional, and Tsim, Karl Wah Keung, additional

Published
2021
Full Text
View/download PDF

50. Inhibition of tau aggregation and associated cytotoxicity on neuron-like cells by calycosin

Author

Wang Junli, Liu Yaqun, Yang Peikui, Lin Min, Chen Zikai, Yang Fenlian, Zhang ZhenXia, and Zheng YuZhong

Subjects
Amyloid, Cell Survival, Cell, tau Proteins, 02 engineering and technology, Biochemistry, 03 medical and health sciences, chemistry.chemical_compound, Protein Aggregates, Structural Biology, Cell Line, Tumor, medicine, Humans, MTT assay, Cytotoxicity, Molecular Biology, 030304 developmental biology, bcl-2-Associated X Protein, Neurons, 0303 health sciences, L-Lactate Dehydrogenase, Caspase 3, Fibrillogenesis, General Medicine, 021001 nanoscience & nanotechnology, Isoflavones, In vitro, Recombinant Proteins, Congo red, Calycosin, medicine.anatomical_structure, HEK293 Cells, Neuroprotective Agents, chemistry, Gene Expression Regulation, Proto-Oncogene Proteins c-bcl-2, Biophysics, 0210 nano-technology, Reactive Oxygen Species
Abstract

In this study, the in vitro assembly of tau and anti-amyloidogenic properties of one naturally occurring phytoestrogen, calycosin, was investigated by spectroscopic techniques including ThT and ANS fluorescence, CD, Congo red absorbance as well as TEM analysis. Afterwards the cytotoxicity of different amyloid species against SH-SY5Y cells was evaluated by MTT assay. Fluorescence spectroscopic studies revealed that calycosin exerts its anti-amyloidogenic effects through increasing the lag time and reducing the apparent growth rate constant (kapp), the amount of fibrillation, and the exposure of hydrophobic regions. Congo red absorbance and CD studies indicated that calycosin prevented the formation of tau aggregate species and β-sheets structures, respectively. TEM analysis also determined the capacity of calycosin to inhibit tau fibrillogenesis through formation of large amorphous aggregates. Furthermore, cellular assays disclosed that calycosin mitigated the cell mortality, LDH release, ROS level, and expression of Bax, Bcl-2, and Caspase-3 in both mRNA and protein levels induced by tau amyloid fibrils. In conclusion, this data may suggest that calycosin can prevent tau amyloid fibrillation and the associated cytotoxicity, mainly due to its effects on formation of lower content of oligomeric and fibrillar aggregates with lower solvent-exposed hydrophobic patches compared to those produced in the absence of calycosin.

Published
2020

Catalog

Books, media, physical & digital resources
See catalog results