Superior tribology property of zinc phosphate impregnated graphite block at high-temperature oxidative friction

Xu Yuxuan,Tu Chuanjun,Liu Yanli,Liu Ping,Chen Gang,Tan Jiao,Xiong Wei,He Yubo,Liang Shilin,Ma Qingchun 한국탄소학회 2022 Carbon Letters Vol.32 No.5

High-temperature friction performances of graphite blocks (GBs) and zinc phosphate impregnated graphite blocks (IGBs) were evaluated under various friction temperatures. The surface of IGB exhibited extremely lower average friction coefficient values, that was 0.007 at 400 °C and 0.008 at 450 °C, in comparison to that of GB (0.13 at 400 °C and 0.16 at 450 °C, respectively). The worn surface of IGB in the high-temperature friction test was smoother and more complete than that of GB. The wear under high temperature and load caused the transformation of zinc pyrophosphate to zinc metaphosphate and the formation of a continuous large-area boundary lubrication layer combined with graphite and metallic element on the wear surface. The superior tribology property of IGB could be attributed to the digestion of iron oxides by tribo-chemical reactions and passivation of the exposed dangling covalent bonds. Specifically, the layered structure generated on the IGB wear interface effectively decreased the adhesive forces and prevented the surface from serious damage.

The role of CTNNB1 and LEF1 in feather follicles development of Anser cygnoides and Anser anser

Yue Sun,Yuxuan Zhou,Petunia Msuthwana,Jing Liu,Chang Liu,Cornelius Tlotliso Sello,Yupu Song,Ziqiang Feng,Shengyi Li,Wei Yang,Yunpeng Xu,Xiaomin Yan,Chuanghang Li,Yujian Sui,Jingtao Hu,Yongfeng Sun 한국유전학회 2020 Genes & Genomics Vol.42 No.7

Background Wingless-types/beta-catenin (Wnt/β-catenin) signaling pathway is one of the most extensively studied transcriptional cascades involved in various types of organogenesis including embryonic and postnatal development. Downy feather quantity is primarily affected by follicular development and gene regulations. Objective This research was aimed to investigate the role of catenin beta-1(CTNNB1) and lymphoid enhancerbinding factor-1 (LEF1) on feather follicles development at different developmental stages. Methods Fluorescence quantitative PCR, Western-blot and immunohistochemical methods were used in Anser cygnoides and Anser anser embryos (E12, E13 E18, and E28) and after birth gosling stages (G18, G48, G88) for gene expression analysis. Results CTNNB1 and LEF1 genes were expressed in Anser cygnoides and Anser anser at different embryonic and after-birth gosling developmental stages and the expression levels were significantly different in different stages (p < 0.05). The mRNA expression of CTNNB1 and LEF1 genes reached the highest level at D88 in Anser cygnoides, while the highest expression levels were at D18 and D88 in Anser anser, and the expression levels of CTNNB1 genes at D88 in all embryonic stages were significantly lower than after-birth stages. CTNNB1 and LEF1 protein expression were the highest at E12 and E28 for Anser cygnoides feather follicles development. While at a similar stage for Anser anser, the expression of CTNNB1 and LEF1 protein was the highest at D48 and D18. Protein expression at embryonic stages was in the epidermis (E) and the hair basal plate (P), the expression site for after-birth stages was in the dermal papilla (DP). Conclusion Our study illustrated that CTNNB1 and LEF1 has an impact on Anser cygnoides and Anser anser feather follicles growth and development.

A High Accuracy Method for the Field Dynamic Balancing of Rigid Spindles in the Ultra-Precision Turning Machine

Xiufeng Liu,Wei Wei,JinChun Yuan,Yuxuan Tao,Yuheng Li,Yu Huang 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.11

For the ultra-precision turning machine, the spindle system is a core component and plays a decisive role in precise machining. The unbalancing state in the spindle can degrade the quality of the machining surface. Therefore, the spindle system must be exceptionally well balanced before processing. In this paper, we proposed a high accuracy spindle balance method, which adopts the real-time data in the CNC system and combines with disturbance observer (DOB) to estimate the unbalancing vector without any extra sensors. Moreover, this method takes full advantage of the ultra-precision machine structure, the high precision grating, and the high-performance motor servo system to achieve high accuracy measurement for the spindle unbalancing. According to the experimental results, the proposed method accuracy is up to G0.0073, which is at least three levels greater than the highest official ISO balancing quality grade G0.16. In the cutting experiments, the PV value reduce to 0.207 μm from 0.528 μm with upgrading the spindle balance grade to G0.01024 from G0.16, verifies the accuracy of the spindle dynamic balancing method from the practice side.

Effect of P3HT passivation layer on triple cation organic-inorganic hybrid perovskite memristor

Wang Yucheng,Xiong Yuxuan,Wang Hongsu,Wu Xiang,Sha Jian,Shang Yueyang,Zhang Yongqi,Li Wei,Wang Shaoxi 한국물리학회 2023 Current Applied Physics Vol.47 No.-

Triple cation organic-inorganic hybrid perovskite (TCP) memristor is a novel candidate for artificial visual applications due to the integrating of recognition, storage, and computing. However, concerns remain regarding the moisture-induced degradation and thermal stability. Here, P3HT was deposited on the TCP film to optimize the memristor performance which showed better film surface quality and lower power consumption. When the thickness of the P3HT layer increases, the grain boundary of the TCP film was gradually filled, leading to the inhibition of the ions/vacancies drifting, and thus the device type was changed from digital to analog. Besides, various functions are demonstrated in TCP photoelectric memristor including excitatory postsynaptic current under optic and electric stimulations and spike rate-dependent plasticity, proving the great application prospects in numerical calculation and information perception.

Principle Issues and Future Prospect on Sliding Arc Ablation of Metal Rail

Cong Haoxi,Zhou Yang,Zhaori Getu,Wang Yuxuan,Wei Haobo,Liu Zhaoling,Wang Jian,Zhang Li,Liu Hongshun,Li Qingmin 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.3

Arc ablation occurs when the armature passes over the surface of metal rail. Ablation not only seriously afects the service life, but also may cause the failure to launch. In this paper, the research status of sliding arc ablation technology is summarized from the mechanism of sliding arc ablation, the characterization method of sliding arc ablation degree, and the enhanced design of materials or structures. Three key issues that need to be further solved are listed: the infuence mechanism of sliding arc ablation on microstructure and properties of metal materials, the service properties evaluation and quantitative characterization methods of metal material, as well as the modifed and enhanced design of materials or structures. In response to those problems, eforts are needed to improve the awareness of sliding arc ablation with the theoretical basis and characterization methods, as well as guide the improvement and strengthening of rail design.

The technology and properties of sponge city permeable bricks prepared using refractory waste

Jieguang Song,Xueqing Yang,Ping Chen,Rongjin Liu,Deping Luo,Yuxuan Wei,Wenjin Yao,Jingjing Liu,Qing Zeng 한양대학교 세라믹연구소 2021 Journal of Ceramic Processing Research Vol.22 No.4

With the widespread development of sponge city projects across the country, the use of industrial permeable bricks hasincreased dramatically. My country produces a large amount of refractory waste and pollutes the environment seriously. Wasterefractory insulation bricks are used as the main raw materials, and a small amount of auxiliary raw materials are added toprepare sponge urban permeable bricks through forming and sintering processes. Through performance tests, such asporosity, flexural strength, and water permeability coefficient, the effect of process parameters on the performance ofpermeable bricks is studied, the process parameters of using refractory waste are comprehensively optimized to preparesponge urban permeable bricks, and permeable bricks are prepared for the industrialization of high-quality industrial solidwaste. Brick provides reference. Through the experimental results and analysis, the following conclusions are drawn: the rawmaterial ratio of refractory brick waste: binder: foaming agent: sintering aid is 80:10:1:9. Slurry water mill foaming occurswhen the water to material ratio is 0.5, the ball milling speed is 80 r/min, and the ball milling time is 2 h; the foaming effectand molding performance are better. In the drying stage, drying at 45 oC for 12 h has the best molding effect. The sinteringsystem at 1,300 oC and holding time of 1 h has the best sintering performance. After optimizing the process, the porosity ofthe permeable bricks can reach 48.4%, the water permeability coefficient is 2.1×10^-2 cm/s, the national permeable brick hasA-level standard, and the compressive strength is 26.8 MPa.

Engineered exosomes enriched in netrin-1 modRNA promote axonal growth in spinal cord injury by attenuating inflammation and pyroptosis

Lu Xiao,Xu Guangyu,Lin Zhidi,Zou Fei,Liu Siyang,Zhang Yuxuan,Fu Wei,Jiang Jianyuan,Ma Xiaosheng,Song Jian 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00

Spinal cord injury (SCI) brings a heavy burden to individuals and society, and there is no effective treatment at present. Exosomes (EX) are cell secreted vesicles containing molecules such as nucleic acids and proteins, which hold promise for the treatment of SCI. Netrin-1 is an axon guidance factor that regulates neuronal growth. We investigated the effects of engineered EX enriched in netrin-1 chemically synthetic modified message RNA (modRNA) in treating SCI in an attempt to find a novel therapeutic approach for SCI.Netrin-1 modRNA was transfected into bone marrow mesenchymal stem cells to obtain EX enriched with netrin-1 (EX-netrin1). We built an inflammatory model in vitro with lipopolysaccharide (LPS) in vitro to study the therapeutic effect of EX-netrin1 on SCI. For experiments in vitro, ELISA, CCK-8 assay, immunofluorescence staining, lactate dehydrogenase release experiments test, real-time quantitative polymerase chain reaction, and western blot were conducted. At the same time, we constructed a rat model of SCI. MRI, hematoxylin-eosin and Nissl staining were used to assess the extent of SCI in rats.In vitro experiments showed that EX had no effect on the viability of oligodendrocytes and PC12 cells. EX-netrin1 could attenuate LPS-induced inflammation and pyroptosis and accelerate axonal/dentritic growth in PC12 cells/oligodendrocytes. In addition, netrin-1 could activate the PI3K/AKT/mTOR signalling pathway upon binding to its receptor unc5b. When Unc5b and PI3K were inhibited, the effect of EX-netrin1 was weakened, which could be reversed by PI3K or mTOR activator. Our in vivo experiments indicated that EX-netrin1 could promote recovery in rats with SCI.We found that EX-netrin1 regulated inflammation, pyroptosis and axon growth in SCI via the Unc5b/PI3K/AKT/mTOR pathway, which provides a new strategy for the treatment of SCI.