Study on the Reinforcement Mechanism of Graphene Oxide for Non-asbestos Gasket Composites

LI Yuxian,LIU Meihong,GU Wenjuan,Wang Juan,SUN Junfeng 한국유체기계학회 2021 International journal of fluid machinery and syste Vol.14 No.1

To improve the quality of the gasket and reduce leakage, non-asbestos gasket composites reinforced by graphene oxide(GO) were prepared. The effect of GO on the microscopic physics and chemistry of slurry suspension and the macroscopic properties of gasket composites were investigated. The microstructure and morphology were analyzed by Fourier-transform infrared (FTIR) spectroscopy and Field emission scanning electron microscopy (FSEM). The results show that the addition of GO improves the microscopic interaction during the wet forming process, which improves the macro properties of the gasket material. The enhancement can be ascribe to the crumpled morphology of GO and the presence of many oxygen-containing functional groups, which enhance the microscopic mechanical interlocking and interfacial interactions of the composite gasket material.

In vitro antiviral, anti-inflammatory, and antioxidant activities of the ethanol extract of Mentha piperita L.

YuXian Li,YiBo Liu,AiQin Ma,Yong Bao,Man Wang,ZhenLiang Sun 한국식품과학회 2017 Food Science and Biotechnology Vol.26 No.6

The objective of this study is to investigate the antiviral, anti-inflammatory, and antioxidant effects of the ethanol extract of Mentha piperita L. leaves (MPE). M. piperita L. leaves were extracted by reflux with ethanol. Total phenolic acid and total flavonoid content were determined. The antiviral activity of MPE against the respiratory syncytial virus (RSV) and the anti-inflammatory activity were evaluated in vitro. The levels of key preinflammatory mediators and cytokines including nitric oxide (NO), tumor necrosis factor alpha (TNF-a), interleukin (IL)-6, and prostaglandin E2 (PGE2) were determined. The antioxidant activities were also evaluated using a colorimetry method. MPE contained high levels of phenolic acid and flavonoid, showed antiviral activity against RSV with a high selectivity index, and significantly decreased the production of NO, TNF-a, IL-6, and PGE2 in lipopolysaccharide-stimulated RAW 264.7 cells. Meanwhile, MPE showed potential free-radical scavenging activities. These results indicate that Mentha piperita L. might be a good source of medicinal plants.

MiR-200-3p inhibits tumor cell proliferation and induces apoptosis by upregulation of FOXO1 in Osteosarcoma cells

Yuchun Li,Yuxian Wu 대한독성 유전단백체 학회 2018 Molecular & cellular toxicology Vol.14 No.1

Osteosarcoma has been reported as a severe and worldwide clinical problem, research focusing on osteosarcoma for overall analysis and understanding of the mechanism will be of great importance for theoretical basis and treatment of osteosarcoma. In the present study, we sought to explore the correlation of miR-200-3p with osteosarcoma proliferation, apoptosis and the related signaling pathway. MTT, flow cytometry, qRT-PCR and western blot were separately used to test the influence of miR-200-3p on cells proliferation, cells apopsotis and the FOXO expression. The results shown that miR-200-3p inhibits cell viability, and promotes apoptosis in Saos-2 and U2OS. The wertern blot results proved the overexpression of miR200-3p can activate the FOXO signaling pathway by upregulating FOXO1 expression.

Madecassic acid protects human periodontal ligament fibroblasts against hydrogen peroxide-induced cell damage by maintaining mitochondrial membrane potential

Jin Yuqin,Li Jialing,Ding Liang,Zhao Qing,Song Yuxian,Li Guifeng,Ji Jun,Ni Yanhong,Hu Qingang 대한독성 유전단백체 학회 2022 Molecular & cellular toxicology Vol.18 No.1

Background Oxidative stress is involved in the pathogenesis of various inflammatory diseases, such as periodontitis. When periodontitis occurs, reactive oxygen species (ROS) are overproduced and cannot be balanced by the antioxidant defense system, resulting in tissue damage. Madecassic acid (MA), an abundant triterpenoid in Centella asiatica (L.) Urban, has been used as a wound healing, antiinflammatory, and anticancer agent. Moreover, recent studies have shown that MA has an antioxidative effect, but the underlying mechanism remains unclear. Objective Here, we established an effective oxidative stress model induced by hydrogen peroxide (H 2 O 2 ) in human periodontal ligament fi broblasts (hPDLFs) to investigate the antioxidant and protective effects of MA against cell damage and its underlying mechanism of action. Results Pretreatment with MA inhibited cell apoptosis and promoted cell invasion and migration against oxidative injury induced by H 2 O 2 . In addition, MA was able to maintain mitochondrial membrane potential (ΔΨm) under oxidative stress. Notably, we found that MA restored redox balance by reducing intracellular ROS production. Furthermore, we investigated apoptosis-related proteins and found that the levels of anti-apoptosis markers Bcl-xL and Bcl-2 were remarkably upregulated, whereas that of the pro-apoptotic marker Bax was strikingly downregulated. Conclusions Collectively, these findings suggest that MA inhibits H 2 O 2 -induced oxidative stress and apoptosis of hPDLFs by reducing intracellular ROS production to maintain ΔΨm stability.

High Step-up Active-Clamp Converter with an Input Current Doubler and a Symmetrical Switched-Capacitor Circuit

He, Liangzong,Zeng, Tao,Li, Tong,Liao, Yuxian,Zhou, Wei The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.3

A high step-up dc-dc converter is proposed for photovoltaic power systems in this paper. The proposed converter consists of an input current doubler, a symmetrical switched-capacitor doubler and an active-clamp circuit. The input current doubler minimizes the input current ripple. The symmetrical switched-capacitor doubler is composed of two symmetrical quasi-resonant switched-capacitor circuits, which share the leakage inductance of the transformer as a resonant inductor. The rectifier diodes (switched-capacitor circuit) are turned off at the zero current switching (ZCS) condition, so that the reverse-recovery problem of the diodes is removed. In addition, the symmetrical structure results in an output voltage ripple reduction because the voltage ripples of the charge/pump capacitors cancel each other out. Meanwhile, the voltage stress of the rectifier diodes is clamped at half of the output voltage. In addition, the active-clamp circuit clamps the voltage surges of the switches and recycles the energy of the transformer leakage inductance. Furthermore, pulse-width modulation plus phase angle shift (PPAS) is employed to control the output voltage. The operation principle of the converter is analyzed and experimental results obtained from a 400W prototype are presented to validate the performance of the proposed converter.

High Step-up Active-Clamp Converter with an Input Current Doubler and a Symmetrical Switched-Capacitor Circuit

Liangzong He,Tao Zeng,Tong Li,Yuxian Liao,Wei Zhou 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.3

A high step-up dc-dc converter is proposed for photovoltaic power systems in this paper. The proposed converter consists of an input current doubler, a symmetrical switched-capacitor doubler and an active-clamp circuit. The input current doubler minimizes the input current ripple. The symmetrical switched-capacitor doubler is composed of two symmetrical quasi-resonant switched-capacitor circuits, which share the leakage inductance of the transformer as a resonant inductor. The rectifier diodes (switched-capacitor circuit) are turned off at the zero current switching (ZCS) condition, so that the reverse-recovery problem of the diodes is removed. In addition, the symmetrical structure results in an output voltage ripple reduction because the voltage ripples of the charge/pump capacitors cancel each other out. Meanwhile, the voltage stress of the rectifier diodes is clamped at half of the output voltage. In addition, the active-clamp circuit clamps the voltage surges of the switches and recycles the energy of the transformer leakage inductance. Furthermore, pulse-width modulation plus phase angle shift (PPAS) is employed to control the output voltage. The operation principle of the converter is analyzed and experimental results obtained from a 400W prototype are presented to validate the performance of the proposed converter.