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Zhaohui Yang,Jun Hong,JinHua Zhang,Michael Yu Wang 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.
An ultra-precision instrument is developed to measure the rotational accuracy of a rolling bearing under working conditions. Thisinstrument uses a high-precision aerostatic spindle, which has high-stiffness to support a test bearing under large axial loading. Thiswork demonstrates the capabilities of the double-probe error separation method for the measurement of aerostatic spindle errormotion at various axial forces and rotational speeds. The rotational performance of an aerostatic spindle is discussed. The resultsindicate that the error motion and the form of the error of the measurement surface are reliably separated at various axial forces androtational speeds. In addition, the error motion of the aerostatic spindle is very stable, increasing slightly and smoothly as therotational speed increases. The error motion is less than 0.18 um when the speed reaches 1920 rpm. In the future, it will be possibleto separate the error motion of an aerostatic spindle from the measurement results of a test bearing.
Influence of Structural Parameters and Tolerance on Stiffness of High-Speed Ball Bearings
Zhaohui Yang,Baotong Li,Tianxiang Yu 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.17 No.11
High-speed ball bearings are widely used in aerospace, high-speed machining tool and other complex mechanical systems. And the stiffness is one of most critical parameter of bearings to decide the machine performance. This paper attempts to construct a 5-DOF stiffness matrix based on quasi-dynamic model of high-speed ball bearings to analyze the variation of stiffness with different work condition precisely, and the variation of stiffness with structural parameter and manufacturing errors are calculated for the optimization of tolerance. In this method, the effect of combined loads and lubrication effect are considered, which can achieve high precision analysis of the relationship between contact load and displacement. And then a 5-DOF stiffness matrix can be calculated precisely. The results can be used to optimize the design bearing for improving stiffness.
Zhaohui Luan,Shuang Liu,Wei Wang,Kaige Xu,Shaosong Ye,Ruijue Dan,Hong Zhang,Zhenzhen Shu,Tongchuan Wang,Chaoqiang Fan,Malcolm Xing,Shiming Yang 한국생체재료학회 2022 생체재료학회지 Vol.26 No.4
Background: Wound closure in the complex body environment places higher requirements on suture’s mechanical and biological performance. In the scenario of frequent mechanical gastric motility and extremely low pH, single functional sutures have limitations in dealing with stomach bleeding trauma where the normal healing will get deteriorated in acid. It necessitates to advance suture, which can regulate wounds, resist acid and intelligently sense stomach pH. Methods: Based on fish swim bladder, a double-stranded drug-loaded suture was fabricated. Its cytotoxicity, histocompatibility, mechanical properties, acid resistance and multiple functions were verified. Also, suture’s performance suturing gastric wounds and Achilles tendon was verified in an in vivo model. Results: By investigating the swim bladder’s multi-scale structure, the aligned tough collagen fibrous membrane can resist high hydrostatic pressure. We report that the multi-functional sutures on the twisted and aligned collagen fibers have acid resistance and low tissue reaction. Working with an implantable “capsule robot”, the smart suture can inhibit gastric acid secretion, curb the prolonged stomach bleeding and monitor real-time pH changes in rabbits and pigs. The suture can promote stomach healing and is strong enough to stitch the fractured Achilles tendon. Conclusions: As a drug-loaded absorbable suture, the suture shows excellent performance and good application prospect in clinical work.
Sha Ke,Zhaohui Yang,Fei Yang,Xiaoming Wang,Juan Tan,Bo Liao 연세대학교의과대학 2019 Yonsei medical journal Vol.60 No.7
Purpose: Alzheimer’s disease (AD) is the most common neurodegenerative disease, with a rising prevalence worldwide. Longnoncoding RNAs (lncRNAs) have been found to play important roles in the development and treatment of AD. However, the exactrole of lncRNA nuclear enriched abundant transcript 1 (NEAT1) in neuronal damage in AD is largely unknown. Materials and Methods: The AD model was established in SH-SY5Y and SK-N-SH cells via treatment with amyloid β1-42 (Aβ). Theexpression of NEAT1 and microRNA-107 (miR-107) was measured by quantitative real-time polymerase chain reaction. Cell viabilityand apoptosis were detected by MTT assay, immunocytochemistry, and flow cytometry. The expression of phosphorylated tauprotein (p-Tau) was measured by Western blot. The interaction between NEAT1 and miR-107 was explored by bioinformaticsanalysis, luciferase activity, and RNA immunoprecipitation assays. Results: NEAT1 expression was enhanced in Aβ-treated SH-SY5Y and SK-N-SH cells, and its knockdown attenuated Aβ-inducedinhibition of viability and promotion of apoptosis and p-Tau levels. NEAT1 was indicated as a decoy of miR-107. miR-107 abundancewas reduced in Aβ-treated cells, and its overexpression reversed Aβ-induced injury. Moreover, interference of miR-107 abatedsilencing of NEAT1-mediated inhibition of neuronal damage in Aβ-treated SH-SY5Y and SK-N-SH cells. Conclusion: LncRNA NEAT1 aggravated Aβ-induced neuronal damage by sponging miR-107, indicating a novel avenue for treatmentof AD.
Study on the Kinetic Characteristics of Microbubbles in Cross-Shaped Flow Focusing Microchannels
Ding Weibing,Yang Qianwen,Zhao Yaohui,Wang Zhaohui,Chen Jie,Wang Hongxia 한국화학공학회 2024 Korean Journal of Chemical Engineering Vol.41 No.1
To study the mechanism of microbubbles generation in cross-shaped microchannels, numerical simulations of gas–liquid two-phase fl ow in microchannels are carried out in this paper using the volume of fl uid method (VOF). By varying the twophase fl ow rate, three diff erent fl ow regimes were obtained, including dripping regime, slugging regime and threading regime, and the relationship between the two-phase fl ow rate and the fl ow state was plotted. Meanwhile, the phase interface, pressure and velocity of microbubbles in three diff erent fl ow regimes were studied, and the evolution of the gas–liquid interface in microbubbles formation was analyzed. It is found that the microbubbles diameter decreases and the frequency increases as the viscosity of the continuous phase gradually increases. As the wall contact angle decreases, the adhesion of the liquid phase to the wall at the channel interaction increases and the microbubbles diameter increases. The increase in interfacial tension greatly increases the cohesion between molecules on the surface of the gas fl ow, making it diffi cult to achieve force equilibrium, which leads to a reduction in the shear stress required to dominate the interface to break the tip of the gas fl ow and slower bubbles formation, resulting in a larger microbubbles diameter.
Seismic performance of RC columns with full resistance spot welding stirrups
Yunlong Yu,Zhaohui Dang,Yong Yang,Yang Chen,Hui Li 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.73 No.5
This paper aims to investigate the seismic performance of RC short columns and long columns with welding stirrups. Through the low-cyclic horizontal loading test of specimens, the seismic performance indexes such as failure modes, hysteretic curve, skeleton curve, ductility, energy dissipation capacity, stiffness degradation and strength degradation were emphatically analyzed. Furthermore, the effects of shear span ratio, stirrups ratio and axial compression ratio on the performance of specimens were studied. The results showed that the seismic performance of the RC short columns with welding stirrups were basically the same as that of the RC short columns with traditional stirrups, but the seismic performance of RC long columns with welding stirrups was better than that of RC long columns with traditional stirrups. The seismic performance of RC short columns and long columns with welding stirrups could be improved by increasing stirrup ratio and shear span ratio and reducing axial pressure ratio. Moreover, the welding stirrup have the advantages of steel saving, industrialization and standardization production, convenient construction, and reducing time, which indicated that the welding stirrups could be applied in practical engineering.
Chen Liang,Yang Lanyun,Xu Chenxi,Chen Kechun,Wang Wei,Yang Liming,Hou Zhaohui 한국탄소학회 2023 Carbon Letters Vol.33 No.2
Recently, hollow carbon spheres (HCS) have aroused great interests in the field of energy storage and conversion owing to their unique morphology, structure and other charming properties. Nevertheless, unsatisfactory electrical conductivity and relatively poor volumetric energy density caused by inevitable gaps between discrete carbon spheres greatly impede the practical application of HCS. In this work, for the first time we propose a novel dual-template strategy and successfully fabricate interconnected 3D hollow N-doped carbon network (HNCN) by a facile and scalable pyrolysis process. By systematical characterization and analysis, it can be found that HNCN is assembled by HCS and lots of mesoporous carbon. Compared to the counterparts, the obtained HNCN exhibits unique 3D interconnected architecture, larger specific surface area, hierarchical meso/macropore structure, higher structure defects, higher N doping amount and more optimized N configurations (especially for pyridinic-N and graphitic-N). As a result, these advantageous features endow HNCN with remarkably promoted electrochemical performance for supercapacitor and oxygen reduction reaction. Clearly, our proposed dual-template strategy provides a good guidance on overcoming the intrinsic shortcomings of HCS, which undoubtedly broadens their application in energy storage and conversion.
Ci Dunwei,Tang Zhaohui,Ding Hong,Cui Li,Zhang Guanchu,Li Shangxia,Dai Liangxiang,Qin Feifei,Zhang Zhimeng,Yang Jishun,Xu Yang 한국미생물학회 2021 The journal of microbiology Vol.59 No.1
Peanut (Arachis hypogaea. L) is an important oil seed crop. Both arbuscular mycorrhizal fungi (AMF) symbiosis and calcium (Ca2+) application can ameliorate the impact of saline soil on peanut production, and the rhizosphere bacterial communities are also closely correlated with peanut salt tolerance; however, whether AMF and Ca2+ can withstand high-salinity through or partially through modulating rhizosphere bacterial communities is unclear. Here, we used the rhizosphere bacterial DNA from saline alkali soil treated with AMF and Ca2+ alone or together to perform high-throughput sequencing of 16S rRNA genes. Taxonomic analysis revealed that AMF and Ca2+ treatment increased the abundance of Proteobacteria and Firmicutes at the phylum level. The nitrogenfixing bacterium Sphingomonas was the dominant genus in these soils at the genus level, and the soil invertase and urease activities were also increased after AMF and Ca2+ treatment, implying that AMF and Ca2+ effectively improved the living environment of plants under salt stress. Moreover, AMF combined with Ca2+ was better than AMF or Ca2+ alone at altering the bacterial structure and improving peanut growth in saline alkali soil. Together, AMF and Ca2+ applications are conducive to peanut salt adaption by regulating the bacterial community in saline alkali soil.