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Study on the lubrication film formation and characteristics of different graphite seal composites
Qili Wang,Jiarui Sun,Mingquan Yu,Yuehu Chen 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.8
In order to study the formation and characteristics of the lubricating film of graphite composites in solid lubrication, the mechanical properties, micro-structure, friction and wear properties of graphite and impregnated samples are compared and analysed. Results show that the graphite/antimony composites have compression strength of 300.2 MPa and hardness of 98.3 HS, which has excellent friction performance and exhibits the law of full film lubrication. The graphite/resin composites with compression strength of 244.9 MPa and hardness of 87.0 HS exhibit the law of residual film lubrication. Under the condition that the load is 24.1 MPa (heavy load) and the friction pair is 45# (small hardness), the lubrication state of the composite materials are close to full film lubrication. External environmental factors such as load, speed, and pair of grinding pairs have different effects on the friction coefficient and the formation of lubricating film.
( Suxia Bao ),( Jianming Zheng ),( Ning Li ),( Chong Huang ),( Mingquan Chen ),( Qi Cheng ),( Kangkang Yu ),( Shengshen Chen ),( Mengqi Zhu ),( Guangfeng Shi ) 대한간학회 2017 Gut and Liver Vol.11 No.6
Background/Aims: To investigate the role of selected serum microRNA (miRNA) levels as potential noninvasive biomarkers for differentiating S0-S2 (early fibrosis) from S3-S4 (late fibrosis) in patients with a chronic hepatitis B virus (HBV) infection. Methods: One hundred twenty-three treatment-naive patients with a chronic HBV infection who underwent a liver biopsy were enrolled in this study. The levels of selected miRNAs were measured using a real-time quantitative polymerase chain reaction assay. A logistic regression analysis was performed to assess factors associated with fibrosis progression. Receiver operating characteristic (ROC) curve and discriminant analyses validated these the ability of these predicted variables to discriminate S0-S2 from S3-S4. Results: Serum miR-29, miR-143, miR-223, miR-21, and miR-374 levels were significantly downregulated as fibrosis progressed from S0-S2 to S3-S4 (p<0.05), but not miR-16. The multivariate logistic regression analysis identified a panel of three miRNAs and platelets that were associated with a high diagnostic accuracy in discriminating S0-S2 from S3-S4, with an area under the curve of 0.936. Conclusions: The levels of the studied miRNAs, with the exception of miR-16, varied with fibrosis progression. A panel was identified that was capable of discriminating S0-S2 from S3-S4, indicating that serum miRNA levels could serve as a potential noninvasive biomarker of fibrosis progression. (Gut Liver 2017;11:860-869)