Microstructure and property evolution of diamond-like carbon films co-doped by Al and Ti with different ratios

Zhou, Yong,Guo, Peng,Sun, Lili,Liu, Linlin,Xu, Xiaowei,Li, Wenxian,Li, Xiaowei,Lee, Kwang-Ryeol,Wang, Aiying Elsevier Sequoia 2019 Surface & coatings technology Vol.361 No.-

<P><B>Abstract</B></P> <P>Diamond-like carbon (DLC) films with weak carbide metal Al and carbide metal Ti co-doping (Al/Ti-DLC) were prepared by a hybrid ion beam deposition system. The atomic ratios of doped Al to Ti were tailored via designing the special Al/Ti combined sputtering target. The composition, microstructure, roughness, residual stress, hardness, toughness, and tribological behaviors of the deposited films were systematically evaluated to explore the dependence of structural properties on Al/Ti ratios. Results indicated that the high-throughput preparation of DLC films with different Al/Ti atomic ratios was achieved by tailoring the sputtering target and process parameters without the difference in both the film thickness and total Al/Ti content. With the Al/Ti ratios in the films decreased from 8.8 to 3.0, the residual stress, hardness, and toughness of Al/Ti-DLC films increased obviously, originating from the increased fraction of titanium carbide and the reduced Al content. However, the coefficient of friction and wear rate with decreasing the Al/Ti ratio were obviously improved, which was related with the transformation of underlying friction mechanism from the sliding interface graphitization to dangling bond-passivation. The present results not only suggest a high-throughput method to fabricate co-doped DLC films, but also promote the scientific understanding and engineering application of DLC films with high performance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ti/Al co-doped diamond-like carbon films were fabricated by a hybrid ion beam method. </LI> <LI> Different Al/Ti ratios were successfully achieved at one time using designed target. </LI> <LI> Al/Ti ratios had no effect on the chemical state of co-doped Ti and Al atoms. </LI> <LI> The mechanical and tribological properties were strongly dependent on Ti/Al ratios. </LI> <LI> Different friction mechanisms were observed with Al/Ti ratios ranged from 8.8 to 3.0. </LI> </UL> </P>

In-situ synthesized ZnFe₂O₄ firmly anchored to the surface of MWCNTs as a long-life anode material with high lithium storage performance

Yang, Tianbo,Zhang, Wanxi,Li, Linlin,Jin, Bo,Jin, Enmei,Jeong, Sangmoon,Jiang, Qing Elsevier 2017 APPLIED SURFACE SCIENCE - Vol.425 No.-

<P><B>Abstract</B></P> <P>Because of two different metal cations in the crystal structures, binary transition metal oxides possess a lot of unique properties. ZnFe<SUB>2</SUB>O<SUB>4</SUB> emerges from these transition metal oxides on account of its high theoretical capacity (1072mAhg<SUP>−1</SUP>). One-dimensional multi-walled carbon nanotubes (MWCNTs) would be a desirable conductive additive for ZnFe<SUB>2</SUB>O<SUB>4</SUB>, thereby improving the electrochemical performance of ZnFe<SUB>2</SUB>O<SUB>4</SUB>. In this work, we prepare ZnFe<SUB>2</SUB>O<SUB>4</SUB>/MWCNTs by solvothermal method with further heat-treatment. ZnFe<SUB>2</SUB>O<SUB>4</SUB> nanoparticles are firmly anchored to the surface of MWCNTs. ZnFe<SUB>2</SUB>O<SUB>4</SUB>/MWCNTs nanocomposite displays high specific capacity (1278mAhg<SUP>−1</SUP> at a current density of 200mAg<SUP>−1</SUP> after 200 cycles, and 565mAhg<SUP>−1</SUP> at a current density of 1500mAg<SUP>−1</SUP> after 500 cycles), and good rate performance (367mAhg<SUP>−1</SUP> even at a current density of 6000mAhg<SUP>−1</SUP> after 80 cycles). The superior electrochemical performance may promote ZnFe<SUB>2</SUB>O<SUB>4</SUB> to be a promising alternative anode in lithium-ion batteries.</P> <P><B>Highlights</B></P> <P> <UL> <LI> ZnFe<SUB>2</SUB>O<SUB>4</SUB> nanoparticles and ZnFe<SUB>2</SUB>O<SUB>4</SUB>/MWCNTs composites have been prepared by a facile solvothermal method. </LI> <LI> ZnFe<SUB>2</SUB>O<SUB>4</SUB> nanoparticles are firmly anchored to the surface of MWCNTs. MWCNTs can suppress the growth of ZnFe<SUB>2</SUB>O<SUB>4</SUB> nanoparticles. </LI> <LI> ZnFe<SUB>2</SUB>O<SUB>4</SUB>/MWCNTs nanocomposite displays high specific capacity at a high current density. </LI> </UL> </P>

Effects of string tension and impact location on tennis playing

Linlin Li,양승한,황창순,김영석 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.11

Finite element impact simulations were performed to observe the vibration of a tennis racket and its strings, as well as the effects of string tension and impact location on a player’s hand and his chances of getting an injury. Studies using the finite element method [FEM] revealed that decreasing the string tension lowers the coefficient of restitution. The ratio of speed to angle change increases with a decrease in string tension. Moreover, the resultant force on the player’s hand is stronger if the tennis ball hits the dead spot than if it hits the sweet spot. For instance, as a tennis ball hits the dead spot with a speed of 10.05m/s, an angle of 15°, and a string tension of 222N, the player’s hand feels a maximum resultant force of almost 424N, which is 1.61 times higher than if the ball hits the sweet spot, at t=0.081 and t=0.0149. Moreover, the force exerted on the player's hand if the ball hits either the best-bounce spot or the off-center spot is 1.4 times higher than if the ball hits the sweet spot.

Academic work within a mode of mixed governance: perspectives of university professors in the research context of western China

Linlin Li 서울대학교 교육연구소 2013 Asia Pacific Education Review Vol.14 No.3

Chinese higher education institutions have been subjected to the intensive bureaucratic governance led by the central authorities since 1949. Since the new public management has been a burgeoning social discourse, some reforms have been conducted recently, centering on the competitive contract-centered employment of staff, integration of industrial sectors, universities, and research institutes, and the evaluation of teaching quality at the undergraduate level. By embracing the ideas of new public management, a mode of mixed governance has evolved within the larger milieu of Chinese higher education. By in-depth interviews with 36 university teachers from a university in western China, this study finds that the distribution of income within the academic community has been polarized, so that the career development of new teachers and those in low priority disciplines is curtailed. Additionally, research is assigned more priority than teaching; institutional service has made distracted academics from knowledge. Lastly, Chinese academics’ work has been greatly affected by a mixed mode of governance spawned by the unique integration between paternalistic governance, bureaucratic management, and new public management.

Grape seed proanthocyanidins protect retinal ganglion cells by inhibiting oxidative stress and mitochondrial alteration

Linlin Li,Xing Geng,Lili Tian,Dabo Wang,Qin Wang 대한약학회 2020 Archives of Pharmacal Research Vol.43 No.10

Grape seed proanthocyanidins (GSP) are knownas condensed tannins and have been used as an anti-oxidantin various neurodegenerative diseases. In our study, GSPwas used as a daily dietary supplement and the neuroprotectiveeffects were evaluated on the retinal ganglion cells(RGCs) in the retinal tissues in glaucomatous DBA/2D (D2)mice. D2 mice and age-matched non-glaucomatous DBA/2JGpnmb+(D2-Gpnmb+) mice were fed with GSP or a controldiet for up to 6 months. The intraocular pressure (IOP), RGCsurvival, glial fibrillary acidic protein (GFAP), the levels ofapoptotic proteins, and the expression of oxidative stressmarkers in retinal tissues were determined. In our study, theneuroprotective effects of GSP on retinal tissues were confirmed,as evidenced by (a) GSP inhibited the IOP elevationin D2 mice; (b) GSP enhanced RGC survival and mediatedthe apoptotic protein expression; (c) GSP suppressed GFAPexpression; and (d) the oxidative stress and the levels ofmitochondrial reactive oxygen species were regulated byGSP. Our findings indicate that GSP has promising potentialto preserve retinal tissue functions via regulating oxidativestress and mitochondrial functions.

LINC00319 promotes cancer stem cell-like properties in laryngeal squamous cell carcinoma via E2F1-mediated upregulation of HMGB3

Yuan Linlin,Tian Xiufen,Zhang Yanfei,Huang Xinhui,Li Qing,Li Wencai,Li Shenglei 생화학분자생물학회 2021 Experimental and molecular medicine Vol.53 No.-

Laryngeal squamous cell carcinoma (LSCC) is one of the most common subtypes of head and neck malignancies worldwide. Long intervening/intergenic noncoding RNAs (LINCRNAs) have been recently implicated in various biological processes that take place in the setting of laryngeal cancer, but the regulatory role of LINC00319 in LSCC remains largely unknown. The current study aimed to elucidate the regulatory effect of LINC00319 on the development and progression of LSCC via high-mobility group box 3 (HMGB3). Microarray-based analysis was initially conducted to identify differentially expressed long noncoding RNAs, after which the expression of LINC00319 and HMGB3 in LSCC tissues and cells was determined accordingly. CD133 + CD144 + TU177 cells were subsequently isolated and transfected with LINC00319 overexpression vector (oe-LINC00319), short hairpin RNA (sh)-LINC00319, sh-HMGB3, sh-E2F transcription factor 1 (E2F1), and oe-E2F1, as well as their corresponding controls. The proliferative, invasion, self-renewal, and tumorigenic abilities of CD133 + CD144 + TU177 cells were then evaluated. Our in vitro findings were further confirmed following subcutaneous injection of cells expressing the corresponding plasmids into nude mice. LINC00319 and HMGB3 expressions were elevated in LSCC cells and tissues. LINC00319 increased HMGB3 expression by recruiting E2F1. Furthermore, the stimulatory role of LINC00319 on the proliferation, invasion, self-renewal ability, and tumorigenicity of CD133 + CD144 + TU177 cells was achieved by upregulating HMGB3 via recruitment of E2F1. The in vitro findings were also confirmed by in vivo experiments. Taken together, these data show that downregulating LINC00319 in CD133 + CD144 + TU177 cells may serve as a potential anticancer regimen by inhibiting the proliferation and invasion of cancer stem cells in LSCC.

Multi-objective variable parameter optimization algorithm for spiral bevel gear tooth surface considering meshing efficiency and contact performance

Fei Li,Sanmin Wang,Peng Chen,Zhibin Li,Linlin Li,Qi’an Peng 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.7

A multi-objective variable parameter optimization method that considers meshing efficiency and contact performance simultaneously is proposed to optimize the tooth surface of spiral bevel gears to achieve higher contact performance and transmission efficiency. First, the tooth surface equations of the spiral bevel gear are established in line with the gear cutting process, and the deviation of tooth surface is analyzed and controlled. Second, the machine tool parameters with the greatest impact on the tooth surface are selected on the basis of the sensitivity analysis approach as the optimization design variables, and the relationship between the machine tool parameters, contact performance, and meshing efficiency is established. Third, the multi-objective variable parameter optimization algorithm is applied to determine the final optimal machine parameters, and the multi-objective optimization algorithm for the tooth surface of spiral bevel gear is formed. Finally, the correctness and effectiveness of the algorithm are verified by numerical simulation and experiment.

Betulin induces reactive oxygen species-dependent apoptosis in human gastric cancer SGC7901 cells

Yang Li,Xiaokang Liu,Dan Jiang,Yingjia Lin,Yushi Wang,Qing Li,Linlin Liu,Ying-Hua Jin 대한약학회 2016 Archives of Pharmacal Research Vol.39 No.9

Betulin, an abundant natural compound, significantly inhibited the cell viability of advanced human gastric cancer SGC7901 cells. Mechanism study demonstrated that betulin induced apoptosis through mitochondrial Bax and Bak accumulation-mediated intrinsic apoptosis pathway. Downregulation of the anti-apoptosis proteins Bcl-2 and XIAP was involved during betulin-induced cell apoptosis. Reactive oxygen species (ROS) was generated in cells after betulin treatment in a time- and dose-dependent manner. Addition of antioxidant N-acetyl-L-cysteine (NAC) significantly attenuated betulin-induced ROS generation as well as Bcl-2 and XIAP downregulation. The mitochondrial accumulation of Bax and Bak, as well as caspase activity, was also remarkably inhibited by NAC treatment, indicating that ROS are important signaling intermediates that lead to betulin-induced apoptosis by modulating multiple apoptosis-regulating proteins in SGC7901 cells.

PM2.5 in poultry houses synergizes with Pseudomonas aeruginosa to aggravate lung inflammation in mice through the NF-κB pathway

Meng Li,Xiuli Wei,Youzhi Li,Tao Feng,Linlin Jiang,Hongwei Zhu,Xin Yu,Jinxiu Tang,Guozhong Chen,Jianlong Zhang,Xingxiao Zhang 대한수의학회 2020 Journal of Veterinary Science Vol.21 No.3

Background: High concentrations of particulate matter less than 2.5 µm in diameter (PM2.5) in poultry houses is an important cause of respiratory disease in animals and humans. Pseudomonas aeruginosa is an opportunistic pathogen that can induce severe respiratory disease in animals under stress or with abnormal immune functions. When excessively high concentrations of PM2.5 in poultry houses damage the respiratory system and impair host immunity, secondary infections with P. aeruginosa can occur and produce a more intense inflammatory response, resulting in more severe lung injury. Objectives: In this study, we focused on the synergistic induction of inflammatory injury in the respiratory system and the related molecular mechanisms induced by PM2.5 and P. aeruginosa in poultry houses. Methods: High-throughput 16S rDNA sequence analysis was used for characterizing the bacterial diversity and relative abundance of the PM2.5 samples, and the effects of PM2.5 and P. aeruginosa stimulation on inflammation were detected by in vitro and in vivo. Results: Sequencing results indicated that the PM2.5 in poultry houses contained a high abundance of potentially pathogenic genera, such as Pseudomonas (2.94%). The lung tissues of mice had more significant pathological damage when co-stimulated by PM2.5 and P. aeruginosa, and it can increase the expression levels of interleukin (IL)-6, IL-8, and tumor necrosis factor-α through nuclear factor (NF)-κB pathway in vivo and in vitro. Conclusions: The results confirmed that poultry house PM2.5 in combination with P. aeruginosa could aggravate the inflammatory response and cause more severe respiratory system injuries through a process closely related to the activation of the NF-κB pathway.

Analysis of thermoelastic damping in bilayered rectangular microplate resonators with three-dimensional heat conduction

Linlin Wang,Xiaopeng Li,Wujiu Pan,Zemin Yang,Jinchi Xu 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.4

Thermoelastic damping (TED) is considered to be the main internal energy dissipation mechanism in microresonators, the study of which has become increasingly significant in the design of microresonators with high quality factor. In this paper, the bilayered cantilever, fixed-fixed and fully clamped rectangular microplate resonators are taken as the research object, and then three theoretical models of thermoelastic damping with three-dimensional heat conduction are built. The analysis on convergence items of the present threedimensional models with different combinations of materials are carried out, and the influence of material plating on TED in Si microplate resonators is also analyzed. The analysis on the effects of the geometry size and boundary conditions on thermoelastic damping of microresonators at the first-order natural frequency are both carried out. Moreover, in order to verify the validation and accuracy of the present three-dimensional (3-D) models, the previous one-dimensional (1-D) models and the FEM models built in this paper are used to compare with the present models. Finally, the validation and accuracy of the present three-dimensional models are confirmed.