363 research outputs found

    Vibration model of a multi-supported guide bar and analysis on the effect of supports location

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    Two methods (equivalent force method and segmental mode assuming method) of calculating the natural frequencies and mode shapes of a free-free-multi-supported beam subjected to an axial load is found, considering the structure characteristic of the guide bar, which has long length but small section, and supported by many bearings. The calculation shows that these two methods are convenient for computer programing and have the same results in obtaining the natural frequencies and mode shapes of a free-free-multi-supported beam subjected to an axial load, solving the problem that the vibration function of this kind of beam is hard to deal with because it cannot be simplified with the boundary condition of two ends. Then the segmental mode assuming method is used to analyze the impact of the support location on the natural frequencies and mode shapes of the guide bar. The relation graphs of the natural frequencies with support location, as well as the support locations where the natural frequencies reached the maximum and the minimum are found, providing a reference for the support location selection for the guide bar. The changing curves of the mode shapes with support location are plotted, which show that the bending deformation is homogeneous when the length of each segment is approximately equal, avoiding the phenomenon that bending stresses concentrates at the large-amplitude segments and cause breakage while less stress exists in small-amplitude segments and hinder the exploiting of their performance, providing a reference for the structure design of the guide bar

    Dynamical Analysis of Carrier-Track Contact Model in a Braiding Machine

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    As vibrations caused by the coupling of carriers and tracks could affect the performance of braiding machines a lot, it is necessary to establish the carrier-track contact model and investigate its dynamic characteristics. Therefore, a dynamic model of carrier-track contact model has been developed. Based on the Hertz\u27s law and Newton\u27s law, the dynamical equations of carriers were established. The influence of contact related parameters to the carriers\u27 dynamic characteristics were discussed. Besides, a comparison of contact parameters with different contact models was presented. The results show that although carriers keep a low contact speed, collisions still exist during carriers transferring between tracks. To avoid/decrease collisions and shocks, some methods were proposed, e.g. controlling the angular velocity of horn gears variable, changing the contact surface to have a higher coefficient of restitution and reducing the vibration of frame and tracks, which could be helpful to the design of braiding machines

    The Roles of Mitogen-Activated Protein Kinase Pathways in TGF-β-Induced Epithelial-Mesenchymal Transition

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    The mitogen-activated protein kinase (MAPK) pathway allows cells to interpret external signals and respond appropriately, especially during the epithelial-mesenchymal transition (EMT). EMT is an important process during embryonic development, fibrosis, and tumor progression in which epithelial cells acquire mesenchymal, fibroblast-like properties and show reduced intercellular adhesion and increased motility. TGF-β signaling is the first pathway to be described as an inducer of EMT, and its relationship with the Smad family is already well characterized. Studies of four members of the MAPK family in different biological systems have shown that the MAPK and TGF-β signaling pathways interact with each other and have a synergistic effect on the secretion of additional growth factors and cytokines that in turn promote EMT. In this paper, we present background on the regulation and function of MAPKs and their cascades, highlight the mechanisms of MAPK crosstalk with TGF-β signaling, and discuss the roles of MAPKs in EMT

    Diverse Roles of Macrophages in Atherosclerosis: From Inflammatory Biology to Biomarker Discovery

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    Cardiovascular disease, a leading cause of mortality in developed countries, is mainly caused by atherosclerosis, a chronic inflammatory disease. Macrophages, which differentiate from monocytes that are recruited from the blood, account for the majority of leukocytes in atherosclerotic plaques. Apoptosis and the suppressed clearance of apoptotic macrophages (efferocytosis) are associated with vulnerable plaques that are prone to rupture, leading to thrombosis. Based on the central functions of macrophages in atherogenesis, cytokines, chemokines, enzymes, or microRNAs related to or produced by macrophages have become important clinical prognostic or diagnostic biomarkers. This paper discusses the impact of monocyte-derived macrophages in early atherogenesis and advanced disease. The role and possible future development of macrophage inflammatory biomarkers are also described

    Microstructure Characterization Techniques for Shale Reservoirs : A Review

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    Funding This work was funded by the National Natural Science Foundation of China (Grant nos. U19B6003-03-01 and 42030804).Peer reviewedPublisher PD

    The complete chloroplast genome sequence of Gentiana triflora and comparative analysis with its congeneric species

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    Gentiana triflora is an important medicinal plant in China with economic and medicinal value. Here, we report the complete chloroplastsequences of G. trifloral. The cp genome of G. triflora of 149, 125 bp contains 130 unique genes, including 85 protein-coding genes,8 rRNA genes, and 37 tRNA genes. The analysis of repeat showed that palindromic had the highest frequency. Besides, a total numberof 45 SSR were identified, most of which were mononucleotide adenine-thymine. Comparative genome analysis of Gentiana speciesrevealed that the pair of the inverted repeat was more conserved than the single-copy region. This analysis resulted in identification of 8 hypervariable regions (trnH-GUG, trnG-UCC-intron, atpI, trnD-GUC, trnL-UAA, rpl32-trnL-UAG, petA and ycf1). Phylogenetic analysis revealed that G. triflora was most closely related to Gentiana manshurica. In conclusion, this study enriched the genomic resources of the Gentiana genus and provided a basis for evolution and phylogeny analyses