1,620 results on '"Fei Xu"'
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2. Continuous motion of particles attached to cavitation bubbles
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Fei Xu, Yanyang Liu, Mao Chen, Jing Luo, and Lixin Bai
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Cavitation bubble ,Particle ,Motion ,High-speed photography ,Ultrasonic field ,Chemistry ,QD1-999 ,Acoustics. Sound ,QC221-246 - Abstract
Microbubble-mediated therapeutic gene or drug delivery is a promising strategy for various cardiovascular diseases (CVDs), but the efficiency and precision need to be improved. Here, we propose a cavitation bubble-driven drug delivery strategy that can be applied to CVDs. A bubble-pulse-driving theory was proposed, and the formula of time-averaged thrust driven by bubble pulses was derived. The continuous motion of particles propelled by cavitation bubbles in the ultrasonic field is investigated experimentally by high-speed photography. The cavitation bubbles grow and collapse continuously, and generate periodic pulse thrust to drive the particles to move in the liquid. Particles attached to bubbles will move in various ways, such as ejection, collision, translation, rotation, attitude variation, and circular motion. The cavity attached to the particle is a relatively large cavitation bubble, which does not collapse to the particle surface, but to the axis of the bubble perpendicular to the particle surface. The cavitation bubble expands spherically and collapses asymmetrically, which makes the push on the particle generated by the bubble expansion greater than the pull on the particle generated by the bubble collapse. The time-averaged force of the cavitation bubble during its growth and collapse is the cavitation-bubble-driven force that propels the particle. Both the cavitation-bubble-driven force and the primary Bjerknes force act in the same position on the particle surface, but in different directions. In addition to the above two forces, particles are also affected by the mass force acting on the center of mass and the motion resistance acting on the surface, so the complex motion of particles can be explained.
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- 2024
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3. RETRACTED: Dong et al. Inhibition of SDF-1α/CXCR4 Signalling in Subchondral Bone Attenuates Post-Traumatic Osteoarthritis. Int. J. Mol. Sci. 2016, 17, 943
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Yonghui Dong, Hui Liu, Xuejun Zhang, Fei Xu, Liang Qin, Peng Cheng, Hui Huang, Fengjing Guo, Qing Yang, and Anmin Chen
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n/a ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
The journal retracts the article “Inhibition of SDF-1α/CXCR4 Signalling in Subchondral Bone Attenuates Post-Traumatic Osteoarthritis” [...]
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- 2024
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4. Formation of Pre-PCTA/DT Intermediates from 2-Chlorothiophenol on Silica Clusters: A Quantum Mechanical Study
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Fei Xu, Xiaotong Wang, Ying Li, Yongxia Hu, Ying Zhou, and Mohammad Hassan Hadizadeh
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2-chlorothiophenol ,silica clusters ,pre-PCTA/DT formation ,L–H and E–R mechanism ,DFT calculations ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Silica (SiO2), accounting for the main component of fly ash, plays a vital role in the heterogeneous formation of polychlorinated thianthrenes/dibenzothiophenes (PCTA/DTs) in high-temperature industrial processes. Silica clusters, as the basic units of silica, provide reasonable models to understand the general trends of complex surface reactions. Chlorothiophenols (CTPs) are the most crucial precursors for PCTA/DT formation. By employing density functional theory, this study examined the formation of 2-chlorothiophenolate from 2-CTP adsorbed on the dehydrated silica cluster ((SiO2)3) and the hydroxylated silica cluster ((SiO2)3O2H4). Additionally, this study investigated the formation of pre-PCTA/DTs, the crucial intermediates involved in PCTA/DT formation, from the coupling of two adsorbed 2-chlorothiophenolates via the Langmuir–Hinshelwood (L–H) mechanism and the coupling of adsorbed 2-chlorothiophenolate with gas-phase 2-CTP via the Eley–Rideal (E–R) mechanism on silica clusters. Moreover, the rate constants for the main elementary steps were calculated over the temperature range of 600–1200 K. Our study demonstrates that the 2-CTP is more likely to adsorb on the termination of the dehydrated silica cluster, which exhibits more effective catalysis in the formation of 2-chlorothiophenolate compared with the hydroxylated silica cluster. Moreover, the E–R mechanism mainly contributes to the formation of pre-PCTAs, whereas the L–H mechanism is prone to the formation of pre-PCDTs on dehydrated and hydroxylated silica clusters. Silica can act as a relatively mild catalyst in facilitating the heterogeneous formation of pre-PCTA/DTs from 2-CTP. This research provides new insights into the surface-mediated generation of PCTA/DTs, further providing theoretical foundations to reduce dioxin emission and establish dioxin control strategies.
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- 2024
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5. CircMTA2 Drives Gastric Cancer Progression through Suppressing MTA2 Degradation via Interacting with UCHL3
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Gengchen Xie, Bo Lei, Zhijie Yin, Fei Xu, and Xinghua Liu
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CircRNAs ,MTA2 ,gastric cancer ,UCHL3 ,ubiquitination ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Our previous study has reported that metastasis-associated protein 2 (MTA2) plays essential roles in tumorigenesis and aggressiveness of gastric cancer (GC). However, the underlying molecular mechanisms of MTA2-mediated GC and its upstream regulation mechanism remain elusive. In this study, we identified a novel circular RNA (circRNA) generated from the MTA2 gene (circMTA2) as a crucial regulator in GC progression. CircMTA2 was highly expressed in GC tissues and cell lines, and circMTA2 promoted the proliferation, invasion, and metastasis of GC cells both in vitro and in vivo. Mechanistically, circMTA2 interacted with ubiquitin carboxyl-terminal hydrolase L3 (UCHL3) to restrain MTA2 ubiquitination and stabilize MTA2 protein expression, thereby facilitating tumor progression. Moreover, circMTA2 was mainly encapsulated and transported by exosomes to promote GC cell progression. Taken together, these findings uncover that circMTA2 suppresses MTA2 degradation by interacting with UCHL3, thereby promoting GC progression. In conclusion, we identified a cancer-promoting axis (circMTA2/UCHL3/MTA2) in GC progression, which paves the way for us to design and synthesize targeted inhibitors as well as combination therapies.
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- 2024
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6. Biomimetic Gradient Hydrogels with High Toughness and Antibacterial Properties
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Mingzhu Zeng, Zhimao Huang, Xiao Cen, Yinyu Zhao, Fei Xu, Jiru Miao, Quan Zhang, and Rong Wang
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gradient hydrogel ,electrophoresis ,controlled release ,toughness ,antibacterial property ,Science ,Chemistry ,QD1-999 ,Inorganic chemistry ,QD146-197 ,General. Including alchemy ,QD1-65 - Abstract
Traditional hydrogels, as wound dressings, usually exhibit poor mechanical strength and slow drug release performance in clinical biomedical applications. Although various strategies have been investigated to address the above issues, it remains a challenge to develop a simple method for preparing hydrogels with both toughness and controlled drug release performance. In this study, a tannic acid-reinforced poly (sulfobetaine methacrylate) (TAPS) hydrogel was fabricated via free radical polymerization, and the TAPS hydrogel was subjected to a simple electrophoresis process to obtain the hydrogels with a gradient distribution of copper ions. These gradient hydrogels showed tunable mechanical properties by changing the electrophoresis time. When the electrophoresis time reached 15 min, the hydrogel had a tensile strength of 368.14 kPa, a tensile modulus of 16.17 kPa, and a compressive strength of 42.77 MPa. It could be loaded at 50% compressive strain and then unloaded for up to 70 cycles and maintained a constant compressive stress of 1.50 MPa. The controlled release of copper from different sides of the gradient hydrogels was observed. After 6 h of incubation, the hydrogel exhibited a strong bactericidal effect on Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli, with low toxicity to NIH/3T3 fibroblasts. The high toughness, controlled release of copper, and enhanced antimicrobial properties of the gradient hydrogels make them excellent candidates for wound dressings in biomedical applications.
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- 2023
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7. Characteristics of Shisa Family Genes in Zebrafish
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Yansong Liu, Na Du, Beibei Qian, Congcong Zou, Zhouxin Yu, Fei Xu, Lijuan Wang, Sishi Qin, Feng You, and Xungang Tan
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gene expression ,knockdown ,CRISPR/Cas13d ,shisa-2 ,mesp-ab ,somite formation ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Shisa represents a type of single-transmembrane adaptor protein containing an N-terminal cysteine-rich domain and a proline-rich C-terminal region. Nine shisa subfamily genes have been proposed in most vertebrates; however, some might be species-specific. The number of shisa genes present in zebrafish remains unclear. This study aimed to investigate the evolutionary relationships among shisa family genes in zebrafish (TU strain) using phylogenetic and syntenic analyses. The function of shisa-2 was preliminarily examined via CRISPR/Cas13d-mediated knockdown. Following identification in zebrafish, 10 shisa family genes, namely shisa-1, 2, 3, 4, 5, 6, 7, 8, 9a, and 9b, were classified into three main clades and six subclades. Their encoding proteins contained a cysteine-rich N-terminal domain and a proline-rich C-terminal region containing different motifs. A specific syntenic block containing atp8a2 and shisa-2 was observed to be conserved across all species. Furthermore, all these genes were expressed during embryogenesis. Shisa-2 was expressed in the presomitic mesoderm, somites, and so on. Shisa-2 was identified as a regulator of the expression of the somite formation marker mesp-ab. Overall, our study provides new insights into the evolution of shisa family genes and the control of shisa-2 over the convergent extension cells of somitic precursors in zebrafish.
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- 2023
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8. Recent progress in noble-metal-free electrocatalysts for alkaline oxygen evolution reaction
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Deming Tan, Hao Xiong, Tao Zhang, Xuelin Fan, Junjie Wang, and Fei Xu
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OER electrocatalyst ,electrochemical water splitting ,noble-metal-free electrocatalyst ,water electrolysis ,anion exchange membrane electrolysis ,Chemistry ,QD1-999 - Abstract
The practical application of splitting water to generate hydrogen is to a large extent hindered by an oxygen evolution reaction (OER) process. Electrocatalysts with low-cost, high activity, and durability are essential for the low kinetic threshold of the OER. Despite the high active performances of noble metal compound electrocatalysts like IrO2 and RuO2, they are heavily restricted by the high cost and scarcity of noble metal elements. In this context, noble-metal-free electrocatalysts have acquired increasing significance in recent years. So far, a broad spectrum of noble-metal-free electrocatalysts has been developed for improved OER performance. In this review, three types of electrolysis and some evaluation criteria are introduced, followed by recent progress in designing and synthesizing noble-metal-free alkaline OER electrocatalysts, with the classification of metal oxides/(oxy)hydroxides, carbon-based materials, and metal/carbon hybrids. Finally, perspectives are also provided on the future development of the alkaline OER on active sites and stability of electrocatalysts.
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- 2022
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9. Transcriptomic and Metabolomic Investigation on Leaf Necrosis Induced by ZmWus2 Transient Overexpression in Nicotiana benthamiana
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Xianwen Zhang, Shuang Liang, Biao Luo, Zhongjing Zhou, Jiandong Bao, Ruiqiu Fang, Fang Wang, Xijiao Song, Zhenfeng Liao, Guang Chen, Yan Wang, Fei Xu, Yi Teng, Wanchang Li, Shengchun Xu, and Fu-Cheng Lin
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WUSCHEL ,necrosis ,transcriptomics ,metabolomics ,tobacco ,plant transgenic technology ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
WUSCHEL (WUS) is a crucial transcription factor in regulating plant stem cell development, and its expression can also improve genetic transformation. However, the ectopic expression of WUS always causes pleiotropic effects during genetic transformation, making it important to understand the regulatory mechanisms underlying these phenomena. In our study, we found that the transient expression of the maize WUS ortholog ZmWus2 caused severe leaf necrosis in Nicotiana benthamiana. We performed transcriptomic and non-target metabolomic analyses on tobacco leaves during healthy to wilted states after ZmWus2 transient overexpression. Transcriptomic analysis revealed that ZmWus2 transformation caused active metabolism of inositol trisphosphate and glycerol-3-phosphate, while also upregulating plant hormone signaling and downregulating photosystem and protein folding pathways. Metabolomic analysis mainly identified changes in the synthesis of phenylpropanoid compounds and various lipid classes, including steroid synthesis. In addition, transcription factors such as ethylene-responsive factors (ERFs), the basic helix–loop–helix (bHLH) factors, and MYBs were found to be regulated by ZmWus2. By integrating these findings, we developed a WUS regulatory model that includes plant hormone accumulation, stress responses, lipid remodeling, and leaf necrosis. Our study sheds light on the mechanisms underlying WUS ectopic expression causing leaf necrosis and may inform the development of future genetic transformation strategies.
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- 2023
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10. Sensitive and Label-free Detection of Bacteria in Osteomyelitis through Exo III-Assisted Cascade Signal Amplification
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Yuanyuan Li, Fei Xu, Jinhua Zhang, Jinshan Huang, Di Shen, Yunmiao Ma, Xiufeng Wang, Yuan Bian, and Qing Chen
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Chemistry ,QD1-999 - Published
- 2021
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11. Main Factors on Effect of Precise Measurement and Precise Tamping Based on BP Neural Network
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Jianjun Qu, Pan Liu, Yiyu Long, and Fei Xu
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ballast track ,BP neural network ,precise measurement and precise tamping ,tamping effect ,influencing factors ,track geometry inspection data ,Technology ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Biology (General) ,QH301-705.5 ,Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
With the continuous development of precise measurement and precise tamping (PMPT) technology on Chinese railway conventional speed lines, the efficiency of machinery tamping operation and the quality of the track have been effectively improved. A variety of PMPT modes have been tried in the field operation, however there are some differences in the operation effect. The quality of the tamping operation is affected by multiple factors. In order to identify the key factors affecting the operation quality and to further improve the tamping operation effect, this paper establishes both the database of PMPT operation modes and the selection index system for evaluating the operation effect. Based on mega multi-source heterogeneous data and track geometry inspection data, this paper adopts the Back Propagation Neural Network (BPNN) prognosis model to quantify and sort the main factors affecting the effect of PMPT. The research results show that the initial quality of the track before tamping, whether the stabilizing operation or the tamping modes have great influence weights. It can scientifically guide the field operation to control the key factors and put forward some practical suggestions for promoting the field application of PMPT and the optimization of operation modes on the conventional speed lines.
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- 2023
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12. Calculation Method of the Finite Soil Pressure for a New Foundation Pit Adjacent to an Existing Subway Station
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Zhenbo Zhang, Jiadi Zhou, Fei Xu, Zhichun Liu, and Minglei Sun
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underground engineering ,foundation pit ,existing subway station ,finite soil ,resultant force ,calculation method ,Technology ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Biology (General) ,QH301-705.5 ,Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
The study aimed at the simple prediction problem of finite soil pressure for a new foundation pit adjacent to an existing subway station. Failure modes of the finite soil were proposed. Considering the friction between the soil and the structural interface, the formulas for calculating the finite soil pressure were derived with the horizontal differential element method, and the distribution was discussed. Furthermore, a simple calculation method for the resultant force of the finite soil pressure and the height of the action point was proposed with the principle of area equivalence. With the example and model tests, the rationality of the above method was verified. The influences of parameters on the resultant force of the soil pressure and the relative height of the resultant force were analyzed. The main conclusions are as follows: (1) The finite soil pressure has a nonlinear distribution and is lower than the conventional soil pressure. (2) Compared with other existing methods and model test results, the proposed finite soil pressure calculation method and simplified method are rational. (3) The finite soil pressure increases with the ground overload and soil weight and decreases with the internal friction angle and the structure-soil friction angle. (4) The relative height of the resultant force of the finite soil pressure increases with the structure-soil friction angle and decreases with the internal friction angle. (5) The proximity and covering soil thickness of the existing subway station have a lesser influence on the finite soil pressure, whereas the internal friction angle, weight, structure-soil friction angle and ground overload have a greater influence on the finite soil pressure. (6) The structure-soil friction angle has a greater influence on the height of the action point. The height of the resultant force is one-third of the enclosure structure depth if the structure-soil friction angle is 0.
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- 2023
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13. Preparation and Characteristics of the Fired Bricks Produced from Polyaluminum Chloride Slag and Glass Powder
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Fuqian Hei, Qing Liu, Guodong Zhao, Jinchen Ou, and Fei Xu
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polyaluminum chloride slag ,glass powder ,fired brick ,forming conditions ,microscopic characteristics ,Technology ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Biology (General) ,QH301-705.5 ,Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
Polyaluminum chloride slag produced in the production of water treatment agents pollutes the environment and wastes land resources in the process of landfill and waste. In order to solve the resource waste of researching polyaluminum chloride slag, it was used to prepare sintered bricks. In this study, sintered bricks were prepared from polyaluminum chloride slag and glass powder. Taking compressive strength, water absorption, linear shrinkage and bulk density as measurement indexes, the effects of the glass powder content (0–10 wt%), molding moisture (10–20%), molding pressure (15–27.5 MPa), heating method (heat preservation at 400 °C and 1000 °C for 2 h, heat preservation at 500 °C and 1000 °C for 2 h, and heat preservation at 1000 °C for 2 h), heating rate (2–10 °C/min) and sintering temperature (900–1100 °C) on the performance of sintered brick and the conditions for meeting Chinese standards were studied. Then, the sintered bricks prepared at different temperatures were characterized by X-ray diffraction and scanning electron microscopy. The results show that the compressive strength (bulk density) increases and the water absorption decreases with the increase of the glass powder content, molding pressure, molding moisture and sintering temperature. Moreover, the linear shrinkage increases with the increase of the molding pressure, molding moisture and sintering temperature, but decreases with the increase of the glass powder content. When the glass powder content of the sintered brick is 10 wt%, with molding moisture of 20 wt%, molding pressure of 25 MPa, heating mode to directly raise the temperature to the target temperature, heating speed of 10 °C/min and sintering temperature of 1100 °C, the properties, pH value and leaching toxicity of sintered bricks meet the requirements of Chinese standard brick MU15. XRD and SEM analyses showed that with the increase of the sintering temperature, new albite and amphibole phases were formed in the structure, and quartz and other silicate minerals melted to form a liquid phase, making the structure more compact and the performance better. The research results provide a reference for the comprehensive utilization of polyaluminum chloride slag.
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- 2023
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14. Maceral and Organic Geochemical Characteristics of the Late Permian Coals from Yueliangtian Mine, Guizhou, Southwestern China
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Qingfeng Lu, Shenjun Qin, Fei Xu, Xiangchun Chang, and Wenfeng Wang
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Chemistry ,QD1-999 - Published
- 2021
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15. Characterization of Free Fatty Acid Receptor 4 and Its Involvement in Nutritional Control and Immune Response in Pacific Oysters (Crassostrea gigas)
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Busu Li, Li Li, Wei Wang, Jie Meng, Fei Xu, Fucun Wu, and Guofan Zhang
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Chemistry ,QD1-999 - Published
- 2020
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16. New insights into the anti-hepatoma mechanism of Alisol G-metal ions complexes based on c-myc DNA
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Fei Xu, Jun Chen, Cai Lu, Hanyu Cao, Wei Gu, and Li Zeng
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Alisol G ,Metal ions ,c-myc DNA ,Multispectral methods ,Molecular docking ,Molecular dynamics simulation ,Chemistry ,QD1-999 - Abstract
This study investigated the anti-hepatoma molecular mechanism of Alisol G, which is an effective component of the Chinese medicine Alisma orientalis, in the presence of metal ions Cu2+ and Fe3+ based on c-myc DNA. Here, a combination of Alisol G and metal ions (Cu2+, Fe3+) to augment anti-hepatoma efficiencies of Alisol G has been identified by methyl thiazolyl tetrazolium (MTT) assay. Network pharmacology revealed that c-myc DNA was the potential target of Alisol G with respect to its anti-hepatoma effects. By performing multi-spectroscopic analyses, we showed that the interaction of Alisol G with c-myc DNA was a process of static quenching. The binding constants and thermodynamic constants indicated that a 1:1 complex was formed between Alisol G and c-myc DNA. Moreover, metal ions strengthened the interaction between Alisol G and c-myc DNA. Molecular docking and molecular dynamics simulation further unveiled that the higher binding affinity between Alisol G-Fe3+ complex and c-myc DNA as compared to Alisol G-Cu2+ complex. This probably resulted from the polarization of metal ions and the structural flexion of Alisol G. The C22-O31-H76 and C18-O32-H77 of Alisol G were key groups in the interaction with c-myc DNA. Addition of metal ion, had greatly changed the c-myc DNA-binding domain of Alisol G while didn’t affect the kinetic stability of the interaction, thus facilitating the insertion of Alisol G into c-myc DNA A-T base pair. Importantly, the DG113 of c-myc DNA was important for its binding to metal ions. Together, our findings suggested that Alisol G in combination with metal ions may be an efficient and promising option for the treatment of liver cancer.
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- 2021
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17. Printing Structurally Anisotropic Biocompatible Fibrillar Hydrogel for Guided Cell Alignment
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Zhengkun Chen, Nancy Khuu, Fei Xu, Sina Kheiri, Ilya Yakavets, Faeze Rakhshani, Sofia Morozova, and Eugenia Kumacheva
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anisotropy ,cellulose nanofiber ,3D printing ,hydrogels ,alignment ,Science ,Chemistry ,QD1-999 ,Inorganic chemistry ,QD146-197 ,General. Including alchemy ,QD1-65 - Abstract
Many fibrous biological tissues exhibit structural anisotropy due to the alignment of fibers in the extracellular matrix. To study the impact of such anisotropy on cell proliferation, orientation, and mobility, it is important to recapitulate and achieve control over the structure of man-made hydrogel scaffolds for cell culture. Here, we report a chemically crosslinked fibrous hydrogel due to the reaction between aldehyde-modified cellulose nanofibers and gelatin. We explored two ways to induce structural anisotropy in this gel by extruding the hydrogel precursor through two different printheads. The cellulose nanofibers in the hydrogel ink underwent shear-induced alignment during extrusion and retained it in the chemically crosslinked hydrogel. The degree of anisotropy was controlled by the ink composition and extrusion flow rate. The structural anisotropy of the hydrogel extruded through a nozzle affected the orientation of human dermal fibroblasts that were either seeded on the hydrogel surface or encapsulated in the extruded hydrogel. The reported straightforward approach to constructing fibrillar hydrogel scaffolds with structural anisotropy can be used in studies of the biological impact of tissue anisotropy.
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- 2022
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18. An Investigation on Mineral Dissolution and Precipitation in Cement-Stabilized Soils: Thermodynamic Modeling and Experimental Analysis
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Enyue Ji, Fei Xu, Hua Wei, Wenxun Qian, Yang He, and Pengfei Zhu
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thermodynamic modeling ,cement-stabilized soil ,dissolution and precipitation ,alkaline activator ,polynaphthalene sulfonate ,Technology ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Biology (General) ,QH301-705.5 ,Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
Thermodynamic modeling helps to reveal insights into the basic chemical kinetics of dissolution and precipitation in cementitious materials, but relevant applications to cement-stabilized soils have seldom been reported. Based on the thermodynamic database of Cemdata18 and the pore solution composition of cement-stabilized soils, this study formulated a specialized thermodynamic model, using essential thermodynamic constants for soil minerals that were calculated to ensure the model’s accuracy. Two commercial admixtures of alkaline activator and polynaphthalene sulfonate were selected for the different modification mechanisms and plain and modified cement-stabilized soils were prepared. Compressive strength was tested to determine the specimens for pore solution analysis and the influences of the admixture type and dose on dissolution and precipitation were investigated by modeling the ionic activity products and saturation indexes. An X-ray diffraction (XRD) analysis was performed to verify and complement the thermodynamic results. The major research findings were that (1) thermodynamic modeling can be reliably applied to cement-stabilized soils by providing the essential thermodynamic data and an appropriate product model, (2) the pozzolanic reaction is accelerated by increasing the OH− concentration in the pore solution, while the cement hydration is highly dependent on the dissolution of Ca(OH)2 and the relevant complexes and (3) the dissolution equilibrium of Ca(OH)2 is directly affected by the alkaline activator dissolution and is indirectly affected by the polynaphthalene sulfonate adsorption of the reactants.
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- 2022
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19. The Homogeneous Gas-Phase Formation Mechanism of PCNs from Cross-Condensation of Phenoxy Radical with 2-CPR and 3-CPR: A Theoretical Mechanistic and Kinetic Study
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Zhuochao Teng, Yanan Han, Shuming He, Mohammad Hassan Hadizadeh, Qi Zhang, Xurong Bai, Xiaotong Wang, Yanhui Sun, and Fei Xu
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polychlorinated naphthalenes ,chlorophenols ,formation mechanisms ,rate constants ,DFT calculations ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Chlorophenols (CPs) and phenol are abundant in thermal and combustion procedures, such as stack gas production, industrial incinerators, metal reclamation, etc., which are key precursors for the formation of polychlorinated naphthalenes (PCNs). CPs and phenol can react with H or OH radicals to form chlorophenoxy radicals (CPRs) and phenoxy radical (PhR). The self-condensation of CPRs or cross-condensation of PhR with CPRs is the initial and most important step for PCN formation. In this work, detailed thermodynamic and kinetic calculations were carried out to investigate the PCN formation mechanisms from PhR with 2-CPR/3-CPR. Several energetically advantageous formation pathways were obtained. The rate constants of key elementary steps were calculated over 600~1200 K using the canonical variational transition-state theory (CVT) with the small curvature tunneling (SCT) contribution method. The mechanisms were compared with the experimental observations and our previous works on the PCN formation from the self-condensation of 2-CPRs/3-CPRs. This study shows that naphthalene and 1-monochlorinated naphthalene (1-MCN) are the main PCN products from the cross-condensation of PhR with 2-CPR, and naphthalene and 2-monochlorinated naphthalene (2-MCN) are the main PCN products from the cross-condensation of PhR with 3-CPR. Pathways terminated with Cl elimination are preferred over those terminated with H elimination. PCN formation from the cross-condensation of PhR with 3-CPR can occur much easier than that from the cross-condensation of PhR with 2-CPR. This study, along with the study of PCN formation from the self-condensation 2-CPRs/3-CPRs, can provide reasonable explanations for the experimental observations that the formation potential of naphthalene is larger than that of 1-MCN using 2-CP as a precursor, and an almost equal yield of 1-MCN and 2-MCN can be produced with 3-CP as a precursor.
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- 2022
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20. Porous Functionalized Covalent-Triazine Frameworks for Enhanced Adsorption Toward Polysulfides in Li-S Batteries and Organic Dyes
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Qianhui Liu, Shuhao Yang, Hlib Repich, Yixuan Zhai, Xiaosa Xu, Yeru Liang, Hejun Li, Hongqiang Wang, and Fei Xu
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covalent triazine-based frameworks ,pore structure ,functionalization ,lithium- sulfur batteries ,organic dye adsorption ,Chemistry ,QD1-999 - Abstract
The incorporation of functional building blocks to construct functionalized and highly porous covalent triazine frameworks (CTFs) is essential to the emerging adsorptive-involved field. Herein, a series of amide functionalized CTFs (CTF-PO71) have been synthesized using a bottom-up strategy in which pigment PO71 with an amide group is employed as a monomer under ionothermal conditions with ZnCl2 as the solvent and catalyst. The pore structure can be controlled by the amount of ZnCl2 to monomer ratio. Benefitting from the highly porous structure and amide functionalities, CTF-PO71, as a sulfur cathode host, simultaneously demonstrates physical confinement and chemical anchoring of sulfur species, thus leading to superior capacity, cycling stability, and rate capability in comparison to unfunctionalized CTF. Meanwhile, as an adsorbent of organic dye molecules, CTF-PO71 was demonstrated to exhibit strong chemical interactions with dye molecules, facilitating adsorption kinetics and thereby promoting the adsorption rate and capacity. Furthermore, the dynamic adsorption experiments of organic dyes from solutions showed selectivity/priority of CTF-PO71s for specific dye molecules.
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- 2020
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21. Editorial: Metal/Covalent Organic Frameworks and Their Derivatives for Electrochemical Energy Applications
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Jian-Gan Wang, Fei Xu, and Yu Zhang
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metal-organic frameworks ,covalent organic frameworks ,supercapacitors ,Li-Sulfur batteries ,water splitting ,fuel cells ,Chemistry ,QD1-999 - Published
- 2020
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22. Zeolite H-Beta as a Dispersive Solid-Phase Extraction Sorbent for the Determination of Eight Neonicotinoid Insecticides Using Ultra-High-Performance Liquid Chromatography—Tandem Mass Spectrometry
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Wenshuai Si, Shouying Wang, Bing Bai, Nan Wu, Tai Ye, Fei Xu, and Cong Kong
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neonicotinoid ,zeolite H-Beta ,bottled water and honey products ,liquid chromatography—tandem mass spectrometry ,dispersive solid-phase extraction ,Technology ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Biology (General) ,QH301-705.5 ,Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
In this study, a dispersive solid-phase extraction (DSPE) pretreatment procedure using zeolite H-Beta as a sorbent was exploited for the determination of eight neonicotinoids in bottled water and honey products based on ultra-high-performance liquid chromatography–tandem mass spectrometry analysis. The zeolite H-Beta was demonstrated to be a suitable sorbent for neonicotinoid insecticides, even after 10 recycles of reuse. The method performance was evaluated by the linearity (R2 ≥ 0.998), recovery (71–108%), precision (0.1–7.8%), limit of detection (0.05–0.1 ng/mL) and limit of quantification (0.1–0.2 ng/mL), which suggested excellent stability and high sensitivity with the use of the DSPE procedure. The method was further successfully applied in the test of neonicotinoid insecticides in 34 samples. Zeolite H-Beta shows promise as an efficient and practical material for monitoring neonicotinoid insecticides in bottled water and multiplex honey matrices.
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- 2022
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23. Biomechanical Characteristics for Identifying the Cutting Direction of Professional Soccer Players
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Yo Chen, Tang-Yun Lo, Fei Xu, and Jia-Hao Chang
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football ,attack ,defense ,Technology ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Biology (General) ,QH301-705.5 ,Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
(1) Background: To understand the movement characteristics of soccer players when cutting in two directions (45° for the right and left cutting movements) through biomechanical analysis of the lower limbs to identify the cutting direction of the attacker; (2) Methods: A motion analysis system was used to capture the movements of 12 male professional soccer players dribbling to the left and right. Kinematics of the players’ cutting were analyzed, and the paired t-test was used for statistics, with a significant level of α = 0.05; (3) Results: When cutting towards the right, the height of the hip joint during the run-up was low (effect size, ES = 0.41, p = 0.031) at 91.8 ± 7.0 cm. When cutting towards the left, the value was 94.6 ± 6.7 cm. While cutting, the front foot was abducted by 4.3 ± 4.0° at landing when cutting towards the right and adducted by 2.7 ± 5.1° when cutting towards the left (ES = 0.38, p = 0.003); (4) Conclusions: When the attacker carries out the cutting action while approaching the defender, the cutting direction may be predicted by observing the attacker’s hip and foot movements.
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- 2021
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24. Prior Toxoplasma Gondii Infection Ameliorates Liver Fibrosis Induced by Schistosoma Japonicum through Inhibiting Th2 Response and Improving Balance of Intestinal Flora in Mice
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Fei Xu, Ruitang Cheng, Sunhan Miao, Yuwei Zhu, Ze Sun, Liying Qiu, Junqi Yang, and Yonghua Zhou
- Subjects
Toxoplasma gondii ,Schistosoma japonicum ,parasitic co-infection ,liver fibrosis ,T helper cell type 2 ,gut microbiome ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Schistosomiasis is an immunopathogenic disease in which a T helper (Th) cell type 2-like response plays vital roles. Hepatic fibrosis is its main pathologic manifestations, which is the leading cause of hepatic cirrhosis. Co-infections of Schistosoma japonicum (Sj) with other pathogens are frequently encountered but are easily ignored in clinical studies, and effective therapeutic interventions are lacking. In this study, we explored the effect of Toxoplasma gondii (Tg) prior infection on Th1/Th2 response, community shifts in gut microbiome (GM), and the pathogenesis of schistosomiasis in murine hosts. Mice were prior infected with Tg before Sj infection. The effects of co-infection on Th1/Th2 response and hepatic fibrosis were analyzed. Furthermore, we investigated this issue by sequencing 16S rRNA from fecal specimens to define the GM profiles during co-infection. Tg prior infection markedly reduced the granuloma size and collagen deposit in livers against Sj infection. Prior infection promoted a shift toward Th1 immune response instead of Th2. Furthermore, Tg infection promoted the expansion of preponderant flora and Clostridiaceae was identified as a feature marker in the GM of the co-infection group. Redundancy analysis (RDA)/canonical correspondence analysis (CCA) results showed that liver fibrosis, Th1/Th2 cytokines were significantly correlated (P < 0.05) with the GM compositions. Tg infection inhibits hepatic fibrosis by downregulating Th2 immune response against Sj infection, and further promotes the GM shifts through “gut–liver axis” in the murine hosts. Our study may provide insights into potential anti-fibrosis strategies in co-infection individuals.
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- 2020
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25. Data-Driven Modeling Identifies TIRAP-Independent MyD88 Activation Complex and Myddosome Assembly Strategy in LPS/TLR4 Signaling
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Xiang Li, Chuan-Qi Zhong, Zhiyong Yin, Hong Qi, Fei Xu, Qingzu He, and Jianwei Shuai
- Subjects
higher-order assembly strategy ,LPS signaling ,mathematical modeling ,SWATH-MS ,systems biology ,TLR4 complexes ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
TLR4 complexes are essential for the initiation of the LPS-induced innate immune response. The Myddosome, which mainly contains TLR4, TIRAP, MyD88, IRAK1/4 and TRAF6 proteins, is regarded as a major complex of TLR4. Although the Myddosome has been well studied, a quantitative description of the Myddosome assembly dynamics is still lacking. Furthermore, whether some unknown TLR4 complexes exist remains unclear. In this study, we constructed a SWATH-MS data-based mathematical model that describes the component assembly dynamics of TLR4 complexes. In addition to Myddosome, we suggest that a TIRAP-independent MyD88 activation complex is formed upon LPS stimulation, in which TRAF6 is not included. Furthermore, quantitative analysis reveals that the distribution of components in TIRAP-dependent and -independent MyD88 activation complexes are LPS stimulation-dependent. The two complexes compete for recruiting IRAK1/4 proteins. MyD88 forms higher-order assembly in the Myddosome and we show that the strategy to form higher-order assembly is also LPS stimulation-dependent. MyD88 forms a long chain upon weak stimulation, but forms a short chain upon strong stimulation. Higher-order assembly of MyD88 is directly determined by the level of TIRAP in the Myddosome, providing a formation mechanism for efficient signaling transduction. Taken together, our study provides an enhanced understanding of component assembly dynamics and strategies in TLR4 complexes.
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- 2020
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26. Vaccarin Regulates Diabetic Chronic Wound Healing through FOXP2/AGGF1 Pathways
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Yixiao Liu, Jiangnan Sun, Xinyu Ma, Shuangshuang Li, Min Ai, Fei Xu, and Liying Qiu
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vaccarin ,diabetic chronic wounds ,foxp2 ,aggf1 ,t1dm ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Background: Diabetes mellitus is a growing global health issue nearly across the world. Diabetic patients who are prone to develop diabetes-related complications often exhibit progressive neuropathy (painless and sensory loss). It is usual for small wounds to progress to ulceration, which especially worsens with peripheral arterial disease and in the presence of anaerobic bacteria, culminating into gangrene. In our study, vaccarin (VAC), the main active monomer extracted from Chinese herb vaccariae semen, is proven to have a role in promoting diabetic chronic wound healing through a cytoprotective role under high glucose conditions. Materials and methods: We constructed a pressure ulcer on both VAC-treated and control mice based on a type 1 diabetes (T1DM) model. The wound healing index was evaluated by an experimental wound assessment tool (EWAT). We also determined the effect of VAC on the proliferation and cell migration of human microvascular endothelial cells (HMEC-1) by a cell counting kit (CCK-8), a scratch and transwell assay. Results: The results demonstrated that VAC could promote the proliferation and migration of high glucose-stimulated HMEC-1 cells, which depend on the activation of FOXP2/AGGF1. Activation of the angiogenic factor with G patch and FHA domains 1 (AGGF1) caused enhanced phosphorylation of serine/threonine kinase (Akt) and extracellular regulated protein kinases (Erk1/2). By silencing the expression of forkhead box p2 (FOXP2) protein by siRNA, both mRNA and protein expression of AGGF1 were downregulated, leading to a decreased proliferation and migration of HMEC-1 cells. In addition, a diabetic chronic wound model in vivo unveiled that VAC had a positive effect on chronic wound healing, which involved the activation of the above-mentioned pathways. Conclusions: In summary, our study found that VAC promoted chronic wound healing in T1DM mice by activating the FOXP2/AGGF1 pathway, indicating that VAC may be a promising candidate for the treatment of the chronic wounds of diabetic patients.
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- 2020
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27. Inhibitory Effects of Peptide Lunasin in Colorectal Cancer HCT-116 Cells and Their Tumorsphere-Derived Subpopulation
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Samuel Fernández-Tomé, Fei Xu, Yanhui Han, Blanca Hernández-Ledesma, and Hang Xiao
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colorectal cancer ,cancer stem cells ,chemoprevention ,bioactive peptide ,lunasin ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
The involvement of cancer stem-like cells (CSC) in the tumor pathogenesis has profound implications for cancer therapy and chemoprevention. Lunasin is a bioactive peptide from soybean and other vegetal sources with proven protective activities against cancer and other chronic diseases. The present study focused on the cytotoxic effect of peptide lunasin in colorectal cancer HCT-116 cells, both the bulk tumor and the CSC subpopulations. Lunasin inhibited the proliferation and the tumorsphere-forming capacity of HCT-116 cells. Flow cytometry results demonstrated that the inhibitory effects were related to apoptosis induction and cell cycle-arrest at G1 phase. Moreover, lunasin caused an increase in the sub-GO/G1 phase of bulk tumor cells, linked to the apoptotic events found. Immunoblotting analysis further showed that lunasin induced apoptosis through activation of caspase-3 and cleavage of PARP, and could modulate cell cycle progress through the cyclin-dependent kinase inhibitor p21. Together, these results provide new evidence on the chemopreventive activity of peptide lunasin on colorectal cancer by modulating both the parental and the tumorsphere-derived subsets of HCT-116 cells.
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- 2020
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28. Theoretical Mechanistic and Kinetic Studies on Homogeneous Gas-Phase Formation of Polychlorinated Naphthalene from 2-Chlorophenol as Forerunner
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Fei Xu, Ruiming Zhang, Yunfeng Li, Qingzhu Zhang, and Wenxing Wang
- Subjects
2-chlorophenol ,reaction mechanism ,rate constants ,formation of polychlorinated naphthalene ,and theoretical mechanistic and kinetic study ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Polychlorinated naphthalenes (PCNs) are dioxins-like compounds and are formed along with polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in thermal and combustion procedures. Chlorophenols (CPs) are the most important forerunners of PCNs. A comprehensive comprehension of PCN formation procedure from CPs is a precondition for reducing the discharge of PCNs. Experiments on the formation of PCNs from CPs have been hindered by PCN toxicity and short of precise detection methods for active intermediate radicals. In this work, PCN formation mechanism in gas-phase condition from 2-chlorophenol (2-CP) as forerunner was studied by quantum chemistry calculations. Numbers of energetically advantaged formation routes were proposed. The rate constants of key elementary steps were calculated over 600–1200 K using canonical variational transition-state theory (CVT) with small curvature tunneling contribution (SCT) method. This study illustrates formation of PCNs with one chlorine atom loss from 2-CP is preferred over that without chlorine atom loss. In comparison with formation of PCDFs from 2-CP, PCN products are less chlorinated and have lower formation potential.
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- 2015
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29. Mechanistic and Kinetic Studies on the Homogeneous Gas-Phase Formation of PCTA/DTs from 2,4-Dichlorothiophenol and 2,4,6-Trichlorothiophenol
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Fei Xu, Xiangli Shi, Yunfeng Li, and Qingzhu Zhang
- Subjects
2,4-dithiochlorophenol ,2,4,6-Trithiochlorophenol ,PCTA/DT ,formation mechanism ,rate constants ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Polychlorinated thianthrene/dibenzothiophenes (PCTA/DTs) are sulfur analogues compounds to polychlorinated dibenzo-p-dioxin/dibenzofurans (PCDD/Fs). Chlorothiophenols (CTPs) are key precursors to form PCTA/DTs. 2,4-DCTP has the minimum number of Cl atoms to form 2,4,6,8-tetrachlorinated dibenzothiophenes (2,4,6,8-TeCDT), which is the most important and widely detected of the PCDTs. In this paper, quantum chemical calculations were carried out to investigate the homogeneous gas-phase formation of PCTA/DTs from 2,4-DCTP and 2,4,6-TCTP precursors at the MPWB1K/6-311+G(3df,2p)//MPWB1K/6-31+G(d,p) level. Several energetically feasible pathways were revealed to compare the formation potential of PCTA/DT products. The rate constants of the crucial elementary reactions were evaluated by the canonical variational transition-state (CVT) theory with the small curvature tunneling (SCT) correction over a wide temperature range of 600–1200 K. This study shows that pathways that ended with elimination of Cl step were dominant over pathways ended with elimination of the H step. The water molecule has a negative catalytic effect on the H-shift step and hinders the formation of PCDTs from 2,4-DCTP. This study, together with works already published from our group, clearly illustrates an increased propensity for the dioxin formation from CTPs over the analogous CPs.
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- 2015
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30. Quantum Chemical and Kinetic Study on Polychlorinated Naphthalene Formation from 3-Chlorophenol Precursor
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Fei Xu, Xiangli Shi, and Qingzhu Zhang
- Subjects
3-chlorophenol ,polychlorinated naphthalene ,formation mechanism ,rate constants ,density functional method ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Polychlorinated naphthalenes (PCNs) are the smallest chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs) and are often called dioxin-like compounds. Chlorophenols (CPs) are important precursors of PCN formation. In this paper, mechanistic and kinetic studies on the homogeneous gas-phase formation mechanism of PCNs from 3-CP precursor were investigated theoretically by using the density functional theory (DFT) method and canonical variational transition-state theory (CVT) with small curvature tunneling contribution (SCT). The reaction priority of different PCN formation pathways were disscussed. The rate constants of crucial elementary steps were deduced over a wide temperature range of 600−1200 K. The mechanisms were compared with the experimental observation and our previous works on the PCN formation from 2-CP and 4-CP. This study shows that pathways ended with Cl elimination are favored over those ended with H elimination from the 3-CP precursor. The formation potential of MCN is larger than that of DCN. The chlorine substitution pattern of monochlorophenols has a significant effect on isomer patterns and formation potential of PCN products. The results can be input into the environmental PCN controlling and prediction models as detailed parameters, which can be used to confirm the formation routes of PCNs, reduce PCN emission and establish PCN controlling strategies.
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- 2015
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31. Formation of Chlorotriophenoxy Radicals from Complete Series Reactions of Chlorotriophenols with H and OH Radicals
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Fei Xu, Xiangli Shi, Qingzhu Zhang, and Wenxing Wang
- Subjects
chlorothiophenols ,chlorothiophenoxy radicals ,H radicals ,OH radicals ,reaction mechanism ,rate constants ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
The chlorothiophenoxy radicals (CTPRs) are key intermediate species in the formation of polychlorinated dibenzothiophenes/thianthrenes (PCDT/TAs). In this work, the formation of CTPRs from the complete series reactions of 19 chlorothiophenol (CTP) congeners with H and OH radicals were investigated theoretically by using the density functional theory (DFT) method. The profiles of the potential energy surface were constructed at the MPWB1K/6-311+G(3df,2p)//MPWB1K/6-31+G(d,p) level. The rate constants were evaluated by the canonical variational transition-state (CVT) theory with the small curvature tunneling (SCT) contribution at 600–1200 K. The present study indicates that the structural parameters, thermal data, and rate constants as well as the formation potential of CTPRs from CTPs are strongly dominated by the chlorine substitution at the ortho-position of CTPs. Comparison with the study of formation of chlorophenoxy radicals (CPRs) from chlorophenols (CPs) clearly shows that the thiophenoxyl-hydrogen abstraction from CTPs by H is more efficient than the phenoxyl-hydrogen abstraction from CPs by H, whereas the thiophenoxyl-hydrogen abstraction from CTPs by OH is less impactful than the phenoxyl-hydrogen abstraction from CPs by OH. Reactions of CTPs with H can occur more readily than that of CTPs with OH, which is opposite to the reactivity comparison of CPs with H and OH.
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- 2015
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32. The Gas-Phase Formation Mechanism of Dibenzofuran (DBF), Dibenzothiophene (DBT), and Carbazole (CA) from Benzofuran (BF), Benzothiophene (BT), and Indole (IN) with Cyclopentadienyl Radical
- Author
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Xuan Li, Yixiang Gao, Chenpeng Zuo, Siyuan Zheng, Fei Xu, Yanhui Sun, and Qingzhu Zhang
- Subjects
nso-hets ,formation mechanism ,cyclopentadienyl ,rate constant ,density functional method ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Benzofuran (BF), benzothiophene (BT), indole (IN), dibenzofuran (DBF), dibenzothiophene (DBT), and carbazole (CA) are typical heterocyclic aromatic compounds (NSO-HETs), which can coexist with polycyclic aromatic hydrocarbons (PAHs) in combustion and pyrolysis conditions. In this work, quantum chemical calculations were carried out to investigate the formation of DBF, DBT, and CA from the reactions of BF, BT, and IN with a cyclopentadienyl radical (CPDyl) by using the hybrid density functional theory (DFT) at the MPWB1K/6-311+G(3df,2p)//MPWB1K/6-31+G(d,p) level. The rate constants of crucial elementary steps were deduced over 600−1200 K, using canonical variational transition state theory with a small-curvature tunneling contribution (CVT/SCT). This paper showed that the production of DBF, DBT, and CA from the reactions of BF, BT, and IN with CPDyl involved six elementary steps: the addition reaction, ring closure, the first H shift, C−C cleavage, the second H shift, and elimination of CH3 or H. The cleavage of the C−C bond was regarded as the rate-determining step for each pathway due to the extremely high barrier. The 1-methyl substituted products were more easily formed than the 4-methyl substituted products. The main products were DBF and 1-methyl-DBF, DBT and 1-methyl-DBT, and CA and 1-methyl-CA for reactions of BF, BT, and IN with CPDyl, respectively. The ranking of DBF, DBT, and CA formation potential was as follows: DBT and methyl-DBT formation > DBF and methyl-DBF formation > CA, and methyl-CA formation. Comparison with the reaction of naphthalene with CPDyl indicated that the reactions of CPDyl attacking a benzene ring and a furan/thiophene/pyrrole ring could be inferred to be comparable under high temperature conditions.
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- 2019
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33. Mechanistic and Kinetic Investigations on the Ozonolysis of Biomass Burning Products: Guaiacol, Syringol and Creosol
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Xiaoxiao Chen, Yanhui Sun, Youxiao Qi, Lin Liu, Fei Xu, and Yan Zhao
- Subjects
biomass burning ,guaiacol ,syringol ,creosol ,reaction pathways ,rate constant ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
The lignin pyrolysis products generated by biomass combustion make an essential contribution to the formation of secondary organic aerosols (SOAs). The ozone-initiated oxidation of guaiacol, syringol and creosol, major constituents of biomass burning, were investigated theoretically by using the density functional theory (DFT) method at the MPWB1K/6-311+G(3df,2p)//MPWB1K/6-31+G(d,p) level. Six primary addition reaction pathways and further decomposition routes with corresponding thermodynamic values were proposed. The Criegee intermediates can be excited by small molecules, such as NOx, H2O in the atmosphere, and would further proceed via self-decomposition or isomerization. The most predominant product for ozonation of guaiacol is the monomethyl muconate (P1). At 295 K and atmospheric pressure, the rate constant is 1.10 × 10−19 cm3 molecule−1 s−1, which is lies a factor of 4 smaller than the previous experimental study. The branching ratios of the six channels are calculated based on corresponding rate coefficient. The present work mainly provides a more comprehensive and detailed theoretical research on the ozonation of methoxyphenol, which aspires to offer novel insights and reference for future experimental and theoretical work and control techniques of SOAs caused by lignin pyrolysis products.
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- 2019
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34. Protective Effects and Mechanisms of Vaccarin on Vascular Endothelial Dysfunction in Diabetic Angiopathy
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Fei Xu, Yixiao Liu, Xuexue Zhu, Shuangshuang Li, Xuelin Shi, Zhongjie Li, Min Ai, Jiangnan Sun, Bao Hou, Weiwei Cai, Haijian Sun, Lulu Ni, Yuetao Zhou, and Liying Qiu
- Subjects
diabetic angiopathy ,endothelial dysfunction ,miRNA-34a ,NO production ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Cardiovascular complications are a major leading cause of mortality in patients suffering from type 2 diabetes mellitus (T2DM). Vascular endothelial dysfunction is a core pathophysiological event in the early stage of T2DM and eventually leads to cardiovascular disease. Vaccarin (VAC), an active flavonoid glycoside extracted from vaccariae semen, exhibits extensive biological activities including vascular endothelial cell protection effects. However, little is known about whether VAC is involved in endothelial dysfunction regulation under high glucose (HG) or hyperglycemia conditions. Here, in an in vivo study, we found that VAC attenuated increased blood glucose, increased glucose and insulin tolerance, relieved the disorder of lipid metabolism and oxidative stress, and improved endothelium-dependent vasorelaxation in STZ/HFD-induced T2DM mice. Furthermore, in cultured human microvascular endothelial cell-1 (HMEC-1) cells, we showed that pretreatment with VAC dose-dependently increased nitric oxide (NO) generation and the phosphorylation of eNOS under HG conditions. Mechanistically, VAC-treated HMEC-1 cells exhibited higher AMPK phosphorylation, which was attenuated by HG stimulation. Moreover, HG-triggered miRNA-34a upregulation was inhibited by VAC pretreatment, which is in accordance with pretreatment with AMPK inhibitor compound C (CC). In addition, both reactive oxygen species (ROS) scavenger N-acetyl-L-cysteine (NAC) and VAC abolished HG-evoked dephosphorylation of AMPK and eNOS, increased miRNA-34a expression, and decreased NO production. These results suggest that VAC impedes HG-induced endothelial dysfunction via inhibition of the ROS/AMPK/miRNA-34a/eNOS signaling cascade.
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- 2019
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35. Mechanistic and Kinetic Study on Self-/Cross- Condensation of PCTA/DT Formation Mechanisms from Three Types of Radicals of 2,4-Dichlorothiophenol
- Author
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Hetong Wang, Chenpeng Zuo, Siyuan Zheng, Yanhui Sun, Fei Xu, and Qingzhu Zhang
- Subjects
2,4-dichlorothiophenoxy radical ,2-sulfydryl-3,5-dichlorophenyl radical ,3,5-dichlorothiophenoxyl diradical ,PCTA/DTs ,formation mechanism ,rate constants ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Chlorothiophenols (CTPs) are known to be key and direct precursors of polychlorinated thianthrene/dibenzothiophenes (PCTA/DTs). Self/cross-coupling of the chlorothiophenoxy radicals (CTPRs), sulfydryl-substituted phenyl radicals and thiophenoxyl diradicals evolving from CTPs are initial and important steps for PCTA/DT formation. In this study, quantum chemical calculations were carried out to investigate the homogenous gas-phase formation of PCTA/DTs from self/cross-coupling of 2,4-dichlorothiophenoxy radical (R1), 2-sulfydryl-3,5-dichlorophenyl radical (R2) and 3,5-dichlorothiophenoxyl diradical (DR) at the MPWB1K/6-311+G(3df,2p)//MPWB1K/6-31+G(d,p) level. The rate constants of crucial elementary steps were deduced over 600−1200 K, using canonical variational transition state theory with a small curvature tunneling contribution. For the formation of PCTAs, the S•/σ-C• condensation with both thiophenolic sulfur in one radical and ortho carbon in the other radical bonded to single electron is the most efficient sulfur-carbon coupling mode, and the ranking of the PCTA formation potential is DR + DR > R2 + DR > R1 + DR > R1 + R2 > R1 + R1. For the formation of PCDTs, the σ-C•/σ-C• coupling with both ortho carbon in the two radicals bonded to single electron is the energetically favored carbon-carbon coupling mode, and the ranking of the PCDT formation potential is: R2 + DR > R2 + R2 > R1 + DR > R1 + R2 > R1 + R1. The PCTA/DTs could be produced from R1, R2 and DR much more readily than PCDD/DFs from corresponding oxygen substituted radicals.
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- 2019
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36. Quantum Chemical and Kinetic Study on Radical/Molecule Formation Mechanism of Pre-Intermediates for PCTA/PT/DT/DFs from 2-Chlorothiophenol and 2-Chlorophenol Precursors
- Author
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Chenpeng Zuo, Hetong Wang, Wenxiao Pan, Siyuan Zheng, Fei Xu, and Qingzhu Zhang
- Subjects
PCTA/PT/DTs ,formation mechanism ,radical/molecule coupling ,density functional theory ,rate constant ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Polychlorinated phenoxathiins (PCPTs), polychlorinated dibenzothiophenes (PCDTs), and polychlorinated thianthrenes (PCTAs) are sulfur analogues of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/DFs). Chlorothiophenols (CTPs) and chlorophenols (CPs) are key precursors for the formation of PCTA/PT/DTs, which can react with H or OH to form chloro(thio)phenoxy radical, sulfydryl/hydroxyl-substituted phenyl radicals, and (thio)phenoxyl diradicals. However, previous radical/radical PCTA/DT formation mechanisms in the literature failed to explain the higher concentration of PCDTs than that of PCTAs under the pyrolysis or combustion conditions. In this work, a detailed thermodynamics and kinetic calculations were carried out to investigate the pre-intermediate formation for PCTA/PT/DTs from radical/molecule coupling of the 2-C(T)P with their key radical species. Our study showed that the radical/molecule coupling mechanism explains the gas-phase formation of PCTA/PT/DTs in both thermodynamic and kinetic perspectives. The S/C coupling modes to form thioether-(thio)enol intermediates are preferable over the O/C coupling modes to form ether-(thio)enol intermediates. Thus, although the radical/molecule coupling of chlorophenoxy radical with 2-C(T)P has no effect on the PCDD/PT formation, the radical/molecule coupling of chlorothiophenoxy radical with 2-C(T)P plays an important role in the PCTA/PT formation. Most importantly, the pre-PCDT intermediates formation pathways from the couplings of sulfydryl/hydroxyl-substituted phenyl radical with 2-C(T)P and (thio)phenoxyl diradicals with 2-C(T)P are more favorable than pre-PCTA/PT intermediates formation pathways from the coupling of chlorothiophenoxy radical with 2-C(T)P, which provides reasonable explanation for the high PCDT-to-PCTA ratio in the environment.
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- 2019
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37. Ziyuglycoside I Inhibits the Proliferation of MDA-MB-231 Breast Carcinoma Cells through Inducing p53-Mediated G2/M Cell Cycle Arrest and Intrinsic/Extrinsic Apoptosis
- Author
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Xue Zhu, Ke Wang, Kai Zhang, Ting Zhang, Yongxiang Yin, and Fei Xu
- Subjects
ziyuglycoside I ,MDA-MB-231 cell line ,G2/M phase arrest ,intrinsic and extrinsic apoptosis ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Background: Due to the aggressive clinical behavior, poor outcome, and lack of effective specific targeted therapies, triple-negative breast cancer (TNBC) has currently been recognized as one of the most malignant types of tumors. In the present study, we investigated the cytotoxic effect of ziyuglycoside I, one of the major components extracted from Chinese anti-tumor herbal Radix Sanguisorbae, on the TNBC cell line MDA-MB-231. Methods: The underlying molecular mechanism of the cytotoxic effect ziyuglycoside I on MDA-MB-231 cells was investigated with cell viability assay, flow cytometric analysis and Western blot. Results: Compared to normal mammary gland Hs 578Bst cells, treatment of ziyuglycoside I resulted in a significant growth inhibitory effect on MDA-MB-231 cells. Ziyuglycoside I induced the G2/M phase arrest and apoptosis of MDA-MB-231 cells in a dose-dependent manner. These effects were found to be partially mediated through the up-regulation of p53 and p21WAF1, elevated Bax/Bcl-2 ratio, and the activation of both intrinsic (mitochondrial-initiated) and extrinsic (Fas/FasL-initiated) apoptotic pathways. Furthermore, the p53 specific siRNA attenuated these effects. Conclusion: Our study suggested that ziyuglycoside I-triggered MDA-MB-231 cell cycle arrest and apoptosis were probably mediated by p53. This suggests that ziyuglycoside I might be a potential drug candidate for treating TNBC.
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- 2016
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38. Inhibition of SDF-1α/CXCR4 Signalling in Subchondral Bone Attenuates Post-Traumatic Osteoarthritis
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Yonghui Dong, Hui Liu, Xuejun Zhang, Fei Xu, Liang Qin, Peng Cheng, Hui Huang, Fengjing Guo, Qing Yang, and Anmin Chen
- Subjects
SDF-1α/CXCR4 ,post-traumatic osteoarthritis (PTOA) ,subchondral bone ,articular cartilage ,osteoclast ,MAPK pathway ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Previous studies showed that SDF-1α is a catabolic factor that can infiltrate cartilage, decrease proteoglycan content, and increase MMP-13 activity. Inhibiting the SDF-1α/CXCR4 signalling pathway can attenuate the pathogenesis of osteoarthritis (OA). Recent studies have also shown that SDF-1α enhances chondrocyte proliferation and maturation. These results appear to be contradictory. In the current study, we used a destabilisation OA animal model to investigate the effects of SDF-1α/CXCR4 signalling in the tibial subchondral bone and the OA pathological process. Post-traumatic osteoarthritis (PTOA) mice models were prepared by transecting the anterior cruciate ligament (ACLT), or a sham surgery was performed, in a total of 30 mice. Mice were treated with phosphate buffer saline (PBS) or AMD3100 (an inhibitor of CXCR4) and sacrificed at 30 days post ACLT or sham surgery. Tibial subchondral bone status was quantified by micro-computed tomography (μCT). Knee-joint histology was analysed to examine the articular cartilage and joint degeneration. The levels of SDF-1α and collagen type I c-telopeptidefragments (CTX-I) were quantified by ELISA. Bone marrow mononuclear cells (BMMCs) were used to clarify the effects of SDF-1α on osteoclast formation and activity in vivo. μCT analysis revealed significant loss of trabecular bone from tibial subchondral bone post-ACLT, which was effectively prevented by AMD3100. AMD3100 could partially prevent bone loss and articular cartilage degeneration. Serum biomarkers revealed an increase in SDF-1α and bone resorption, which were also reduced by AMD3100. SDF-1α can promote osteoclast formation and the expression oftartrate resistant acid phosphatase (TRAP), cathepsin K (CK), and matrix metalloproteinase (MMP)-9 in osteoclasts by activating the MAPK pathway, including ERK and p38, but not JNK. In conclusion, inhibition of SDF-1α/CXCR4signalling was able to prevent trabecular bone loss and attenuated cartilage degeneration in PTOA mice.
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- 2016
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39. PREPARATIVE SEPARATION OF ISOQUINOLINE ALKALOIDS FROM PHELLODENDRI CORTEX BY PH-ZONE-REFINING COUNTER-CURRENT CHROMATOGRAPHY
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Daijie Wang, Shanming Tian, Li Cui, Huijiao Yan, Xiangyun Song, Yuguo Liu, Fei Xu, and Junjian Ma
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Phellodendri Cortex ,isoquinoline alkaloids ,palmatine ,berberine ,pH-Zone-Refining Counter-Current Chromatography ,Chemistry ,QD1-999 - Abstract
pH-Zone-refining counter-current chromatography (PZRCCC) was successfully used for preparative separation isoquinoline alkaloids from Phellodendri Cortex. Two target compounds of berberine and palmatine were completely resolved by a two-phase solvent system chloroform/methanol/water (4:2:2, v/v), with 10 mmol L-1 HCl in upper stationary phase and 10 mmol L-1 TEA in lower organic phase. From 2.0 g of the crude alkaloids, palmatine (448 mg, 95.1%) and berberine (159 mg, 95.4%) were obtained in one-step PZRCCC separation. The chemical structures were identified by ESI-MS and NMR data. The results indicated that PZRCCC separation is an excellent preparative separation method for isoquinoline alkaloids from Phellodendri Cortex.
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40. Supramolecular Polymerization Powered by Escherichia coli : Fabricating a Near-Infrared Photothermal Antibacterial Agent in Situ
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Jiang-Fei Xu, Zihe Yin, Guobin Song, Hao Hu, Yuchong Yang, Peng Zheng, and Jinpeng Yang
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In situ ,Materials science ,Fabrication ,technology, industry, and agriculture ,Supramolecular chemistry ,macromolecular substances ,General Chemistry ,Photothermal therapy ,Combinatorial chemistry ,chemistry.chemical_compound ,Monomer ,chemistry ,Polymerization ,parasitic diseases ,Bifunctional ,Antibacterial agent - Abstract
An E. coli reduction-powered supramolecular polymerization is reported, leading to the fabrication of an NIR photothermal antibacterial agent in situ. To this end, a bifunctional monomer containing...
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- 2022
41. Discovery of daspyromycins A and B, 2-aminovinyl-cysteine containing lanthipeptides, through a genomics-based approach
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Ren-Xiang Tan, Rui-Hua Jiao, Jia-Qi Ma, Jing Shi, Hui Ming Ge, Bo Zhang, Yong-Chao Wang, and Zi-Fei Xu
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02 engineering and technology ,General Chemistry ,Bacterial genome size ,Biology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,biology.organism_classification ,01 natural sciences ,DNA sequencing ,0104 chemical sciences ,chemistry.chemical_compound ,Biochemistry ,chemistry ,Gene cluster ,Heterologous expression ,0210 nano-technology ,Gene ,Streptomyces albus ,Bacteria ,Lanthionine - Abstract
Lanthipeptides are one of the largest groups of ribosomally synthesized and post-translationally modified peptides (RiPPs) and are characterized by the presence of lanthionine (Lan) or methyllanthionine residues (MeLan). Only very few lanthipeptides contain a C-terminal 2-aminovinyl-cysteine (AviCys) motif, but all of them show potent antibacterial activities. Recent advances of genome sequencing led to the rapid accumulation of new biosynthetic gene clusters (BGCs) for lanthipeptides. In this study, through our genome mining strategy, we found the AviCys containing lanthipeptides are widespread in the bacterial kingdom. A lanthipeptide-type biosynthetic gene cluster was identified from public bacterial genome database. Two new lanthipeptides, daspyromycins A and B (1 and 2) containing AviCys motif, along with two degraded products, daspyromycins C and D (3 and 4), were obtained after heterologous expression of the gene cluster in Streptomyces albus J1074. Daspyromycins A and B showed potent antimicrobial activity against a spectrum of Gram-positive and -negative bacteria including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE).
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- 2022
42. Parameter optimization and performance analysis of nanofiltration membrane in treatment of compound-contaminated high-hardness water
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Fei Xu, Song Wuchang, Li Guifang, Yonglei Wang, Yuting Gao, Shaohua Sun, and Ruibao Jia
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Environmental Engineering ,Chemistry ,Health, Toxicology and Mutagenesis ,Hard water ,Contamination ,Pulp and paper industry ,Environmental technology. Sanitary engineering ,high-hardness ,response-surface methodology ,Environmental sciences ,Membrane ,nanofiltration ,parameter optimization ,GE1-350 ,Nanofiltration ,composite-contaminated ,TD1-1066 ,Water Science and Technology - Abstract
Increased pollution caused by socio-economic development has led to compound-contaminated high-hardness water pollution. In this study, laboratory-scale nanofiltration (NF) treatment of such water was investigated. Response-surface methodology was used to optimize the NF operating parameters, and a regression model with desalination rate and transmembrane pressure changes as response values was established. The NF membrane efficiencies in contaminant removal from groundwater and surface water with compound-contaminated high hardness and the membrane-fouling characteristics during long-term operation were investigated. The results show that the optimal operating parameters for the NF membrane in the removal of inorganic salts from groundwater are as follows: influent pH 8, influent pressure 1 MPa, and water yield 27.976%. The removal rates for groundwater total hardness, total alkalinity, total soluble solids, K+, Na+, Ca2+, Mg2+, , Cl−, , and were 99.4, 90.3, 84.7, 63.2, 56.8, 99.6, 95.2, 99.6, 68.3, 86.1, and 65.9%, respectively. Surface water contains more complex components; therefore, membrane fouling during surface water is more serious. The NF membrane was operated continuously for more than 35 days under the optimal operating conditions with no serious membrane fouling. HIGHLIGHTS Response-surface methodology was used to optimize the NF operating parameters.; NF membrane was operated continuously for more than 35 days under the optimal operating conditions with no serious membrane fouling.; The membrane fouling by hardness ion was analyzed by SEM-EDS.
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- 2021
43. An Intracellular pH-Actuated Polymer for Robust Cytosolic Protein Delivery
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Wei Xu, Wei-Min Miao, Jin-Zhi Du, Yue Zhang, Jia-Xian Li, Jun Wang, Cong-Fei Xu, Feng-Qin Luo, and Qi-Song Tong
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chemistry.chemical_classification ,Chemistry ,Intracellular pH ,media_common.quotation_subject ,Cell ,General Chemistry ,Plasma protein binding ,Polymer ,Cytosol ,medicine.anatomical_structure ,Biophysics ,medicine ,Internalization ,media_common - Abstract
Robust cytosolic protein delivery requires both efficient protein binding with delivery vehicles and effective protein release after cell internalization. Although a variety of stimuli-responsive c...
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- 2021
44. Visible-Light-Promoted Multistep Tandem Reaction of Vinyl Azides toward the Formation of 1-Tetralones
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Xiu-Qin Hu, Qiang Hu, Peng-Fei Xu, and Meng-Jie Jiao
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chemistry.chemical_classification ,chemistry.chemical_compound ,chemistry ,Cascade reaction ,Organic Chemistry ,Tetralone ,Combinatorial chemistry ,Alkyl ,Tetralones ,Visible spectrum - Abstract
A visible-light-driven multistep tandem reaction between vinyl azides and alkyl bromides has been developed leading to the formation of tetralone skeletons under mild conditions, which can be easily scaled up to the gram scale. Various 1-tetralone derivatives are synthesized and transformed into desired products in good to high yields.
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- 2021
45. miR-31-5p/SOX4 Axis Affects Autophagy and Apoptosis of Chondrocytes by Regulating Extracellular Regulated Protein Kinase/Mechanical Target of Rapamycin Kinase Signalling
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Hai-Bin Wang, Yong-Ming Lv, Fei Xu, and Ying-Chun Song
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Sirolimus ,MAPK/ERK pathway ,Cell growth ,Chemistry ,Kinase ,Autophagy ,Apoptosis ,Cell Biology ,General Medicine ,mTORC1 ,SOXC Transcription Factors ,Pathology and Forensic Medicine ,Cell biology ,MicroRNAs ,Chondrocytes ,Downregulation and upregulation ,Osteoarthritis ,Humans ,Protein kinase A ,Protein Kinases ,Molecular Biology ,PI3K/AKT/mTOR pathway - Abstract
Background: Osteoarthritis (OA) is a common type of degenerative joint diseases that is regulated by a combination of complex intercellular signals and modulators, including non-coding RNAs. Mounting evidence suggests that miR-31-5p is physiologically involved in the regulation of chondrocytes, but the mechanism remains unclear. Methods: Expression levels of miR-31-5p and SOX4 in OA cartilage tissues and in IL-1β-stimulated chondrocytes were examined by quantification polymerase chain reaction (q-PCR) or immunohistochemistry assays. Cell proliferation and apoptosis were detected by Cell Counting Kit-8 (CCK-8) and flow cytometry assays, respectively. Expression of LC3 was detected using immunofluorescence staining. Expressions of autophagy-related proteins and extracellular regulated protein kinase (ERK)/mechanical target of rapamycin kinase (mTORC1) signal-related proteins were measured by Western blot analysis. Molecular interaction was validated by dual luciferase reporter assay. Results: Downregulation of miR-31-5p and upregulation of SOX4 were observed in both OA patients and OA chondrocytes. Mechanistic experiments revealed that miR-31-5p negatively modulated SOX4 expression by directly targeting its 3′- untranslated region. Moreover, overexpression of miR-31-5p suppressed the activation of mTORC1 in an ERK-dependent manner by inhibiting SOX4. Further functional experiments demonstrated that overexpressing miR-31-5p in OA chondrocytes markedly promoted its proliferation and autophagy while inhibiting apoptosis. However, these effects were abolished by overexpression of SOX4 or treatment with 3BDO, an mTOR activator. Conclusion: These results demonstrated that miR-31-5p enhanced survival and autophagy of OA chondrocytes through inactivation of mTORC1 via directly targeting SOX4, suggesting that miR-31-5p may play a protective role in OA progression.
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- 2021
46. LncRNA MIAT enhances cerebral ischaemia/reperfusion injury in rat model via interacting with EGLN2 and reduces its ubiquitin‐mediated degradation
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Chunmei Hu, Suping Li, Yi Wang, Jing Fu, and Fei Xu
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Pentose phosphate pathway ,Models, Biological ,Brain Ischemia ,Hypoxia-Inducible Factor-Proline Dioxygenases ,chemistry.chemical_compound ,MDM2 ,Ubiquitin ,Transcription (biology) ,medicine ,Animals ,Cells, Cultured ,Neurons ,ischaemic stroke ,Gene knockdown ,biology ,Protein Stability ,Chemistry ,Ubiquitination ,RNA-Binding Proteins ,Original Articles ,Cell Biology ,Glutathione ,medicine.disease ,MIAT ,Rats ,Ubiquitin ligase ,Cell biology ,Disease Models, Animal ,Oxidative Stress ,Gene Expression Regulation ,Reperfusion Injury ,Proteolysis ,biology.protein ,Molecular Medicine ,Mdm2 ,RNA, Long Noncoding ,Original Article ,Disease Susceptibility ,ischaemic/reperfusion injury ,Reperfusion injury ,Biomarkers ,EGLN2 - Abstract
Long non‐coding RNA (lncRNA) MIAT (myocardial infarction associated transcript) has been characterized as a functional lncRNA modulating cerebral ischaemic/reperfusion (I/R) injury. However, the underlying mechanisms remain poorly understood. This study explored the functional partners of MIAT in primary rat neurons and their regulation on I/R injury. Sprague‐Dawley rats were used to construct middle cerebral artery occlusion (MCAO) models. Their cerebral cortical neurons were used for in vitro oxygen‐glucose deprivation/reoxygenation (OGD/R) models. Results showed that MIAT interacted with EGLN2 in rat cortical neurons. MIAT overexpression or knockdown did not alter EGLN2 transcription. In contrast, MIAT overexpression increased EGLN2 stability after I/R injury via reducing its ubiquitin‐mediated degradation. EGLN2 was a substrate of MDM2, a ubiquitin E3 ligase. MDM2 interacted with the N‐terminal of EGLN2 and mediated its K48‐linked poly‐ubiquitination, thereby facilitating its proteasomal degradation. MIAT knockdown enhanced the interaction and reduced EGLN2 stability. MIAT overexpression enhanced infarct volume and induced a higher ratio of neuronal apoptosis. EGLN2 knockdown significantly reversed the injury. MIAT overexpression reduced oxidative pentose phosphate pathway flux and increased oxidized/reduced glutathione ratio, the effects of which were abrogated by EGLN2 knockdown. In conclusion, MIAT might act as a stabilizer of EGLN2 via reducing MDM2 mediated K48 poly‐ubiquitination. MIAT‐EGLN2 axis exacerbates I/R injury via altering redox homeostasis in neurons.
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- 2021
47. Structure‐Activity Relationship Studies of Hydantoin‐Cored Ligands for Smoothened Receptor
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Fei Li, Dongxiang Xue, Cuixia Li, Fei Xu, Fang Zhou, Yang Liu, Kang Ding, Suwen Zhao, Zhihao Zhu, Yueming Xu, Zhiping Le, and Houchao Tao
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inorganic chemicals ,Stereochemistry ,Hydantoin ,Ligands ,Structure-Activity Relationship ,chemistry.chemical_compound ,structural biology ,Structure–activity relationship ,Binding site ,QD1-999 ,anti-cancer ,Binding Sites ,Halogen bond ,Ligand ,Hydantoins ,Communication ,General Chemistry ,Communications ,molecular dynamics ,Ring size ,Chemistry ,Smoothened Receptor ,Transmembrane domain ,chemistry ,halogen bonding ,smoothened receptor - Abstract
An underside binding site was recently identified in the transmembrane domain of smoothened receptor (SMO). Herein, we report efforts in the exploration of new insights into the interactions between the ligand and SMO. The hydantoin core in the middle of the parent compound was found to be highly conservative in chirality, ring size, and substituents. On each benzene at two ends, a plethora of variations, particularly halogen substitutions, were introduced and investigated. Analysis of the structure‐activity relationship revealed miscellaneous halogen effects. The ligands with double halogen substituents exhibit remarkably enhanced potency, providing promising candidates that potentially overcome the common drug resistance and useful heavy‐atom labeled chemical tools for co‐crystallization studies of SMO., A series of diaryl hydantoin analogs were synthesized and evaluated in the inhibition of Hedgehog pathway by targeting the smoothened receptor. Double halogen substituents introduced at two ends of the molecule greatly enhanced the potency.
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- 2021
48. Cross-linked anion exchange membranes with flexible, long-chain, bis-imidazolium cation cross-linker
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Jianning Ding, Bencai Lin, Fei Xu, Ke Qiu, and Jing Li
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Ion exchange ,Renewable Energy, Sustainability and the Environment ,Small-angle X-ray scattering ,Chemistry ,Oxide ,Energy Engineering and Power Technology ,Condensed Matter Physics ,chemistry.chemical_compound ,Fuel Technology ,Membrane ,Chemical engineering ,Phenylene ,Reagent ,Alkaline anion exchange membrane fuel cells ,Chemical stability - Abstract
Herein, poly (phenylene) oxide (PPO)-based cross-linked anion exchange membranes (AEMs) with flexible, long-chain, bis-imidazolium cation cross-linkers are designed and synthesized. Although the cross-linked membranes possess high ion exchange capacity (IEC) values of up to 3.51–3.94 meq g−1, they have a low swelling degree and good mechanical strength because of their cross-linked structure. Though the membranes with the longest flexible bis-imidazolium cation cross-linker (BMImH-PPO) possess the lowest IEC among these PPO-based AEMs, they show the highest conductivity (24.10 mS cm−1 at 20 °C) and highest power density (325.7 mW cm−2 at 60 °C) because of the wide hydrophilic/hydrophobic microphase separation in the membranes that promote the construction of ion transport channels, as confirmed by atom force microscope (AFM) images and the small angle X-ray scattering (SAXS) analyses. Furthermore, the BMImH-PPO samples exhibit good chemical stability (10% and 6% decrease in IEC and conductivity, respectively, in 2 M KOH at 80 °C for 480 h, and a 22% decrease in weight in Fenton's reagent at 60 °C for 120 h), making such cross-linked AEMs potentially applicable in alkaline anion exchange membrane fuel cells.
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- 2021
49. Correlation of c-MET expression with clinical characteristics and the prognosis of colorectal cancer
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Qiumei Dong, Dongyang Yang, Fei Xu, Dong Ma, Xiaorong Lai, Ying Li, Sipei Wu, Chao Liu, and Zijun Li
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Neuroblastoma RAS viral oncogene homolog ,C-Met ,business.industry ,Colorectal cancer ,Gastroenterology ,Perineural invasion ,Gene mutation ,medicine.disease ,medicine.disease_cause ,chemistry.chemical_compound ,Exon ,Oncology ,chemistry ,Cancer research ,Immunohistochemistry ,Medicine ,Original Article ,KRAS ,business - Abstract
Background The proto-oncogene c-MET (mesenchymal-epithelial transition factor gene) plays a critical role in cellular proliferation, survival, migration, and invasion in cancers. The aim of this study is to explore the relationship between c-MET expression and the clinicopathological characteristics of colorectal cancer (CRC) patients. Methods A total of 337 enrolled patients were collected in present study. Here, the c-MET and EGFR expression were detected by immunohistochemistry (IHC). The mutational statuses of KRAS in exons 2, 3, and 4, NRAS in exons 2, 3, and 4, and BRAF in exon 15 from formalin-fixed sections were detected by direct DNA sequencing. Results Our results showed that high c-MET expression was significantly associated with tumor perineural invasion (P=0.007) and gender (P=0.016). High level c-MET expression (c-MET-high) in the primary tumors was observed in 68.2% of patients. In the 337 enrolled patients, 43.2% of patients had KRAS mutations, 3.3% of patients had NRAS mutations, and 4.7% of patients had BRAF mutations. However, KRAS, NRAS, and BRAF gene mutations had no association with c-MET protein levels in primary tumors. Additionally, c-MET protein expression had a strong correlation with EGFR expression (P=0.002). The survival time was not significantly longer for patients with c-MET-high primary tumors than for those with c-MET-low primary tumors. Conclusions c-MET immunohistochemistry was significantly higher in primary tumors with perineural invasion, female gender, and EGFR high expression. However, c-MET-high in the primary tumors was not significantly associated with longer survival compared with c-MET-low tumors. Further studies are required to investigate c-MET as potential molecular marker of progression and to test the possibility of its incorporation as a new therapeutic target.
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- 2021
50. An aptasensor for the detection of Pb 2+ based on photoinduced electron transfer between a G‐quadruplex–hemin complex and a fluorophore
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Xiuxiu Wu, Fengqin Yin, Min Yuan, Fei Xu, Tai Ye, Yu Jingsong, Ya Wang, Hui Cao, and Liling Hao
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Detection limit ,chemistry.chemical_compound ,Conformational change ,Fluorophore ,chemistry ,Chemistry (miscellaneous) ,Biophysics ,Nucleic Acid Strand ,G-quadruplex ,Photochemistry ,Fluorescence ,Photoinduced electron transfer ,Hemin - Abstract
Due to the threat to health of heavy metal contamination, simple and rapid detection methods for heavy metals are an urgent needed in environment protection and food safety. In this work, we have developed a fluorescent aptasensor for the 'turn-off' model detection of Pb2+ . The key feature of the aptasensor is that the dye-labelled nucleic acid strand can be folded into a G-quadruplex structure in the presence of Pb2+ . This conformational change induces photoinduced electron transfer (PET) between a G-quadruplex-hemin complex and 6-carboxyrhodamine X (ROX), which results in fluorescence quenching of ROX. We systematically investigated the interaction mechanism between Pb2+ and the aptasensor and the effects of several environmental parameters were also studied. Under the optimum conditions, the proposed method exhibited a good liner relationship between the concentration of Pb2+ and fluorescence quenching efficiency in the range 25-500 nM and the limit of detection was 1.02 nM. In addition, this method also manifested good performance in spiked lettuce samples with satisfactory recoveries of 87.10-109.6%. This target-induced PET platform can be further expanded to other heavy metal analysis.
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- 2021
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