On the mechanical and tribological performances of the tribofilm formed by zinc dialkyl dithiophosphate

Weimin Feng,Hui Song,Ziyan Lu,ZhiquanYang,Xianguo Hu 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.122 No.-

The zinc dialkyl dithiophosphate (ZDDP) as multi-effect additive used in lubricating oil has always beenpaid more attention on the antioxidation, anticorrosion and antiwear performances. How to explain itsrole in tribology field has been paid more attention in the world. This studying showed a new insight intothe antiwear mechanism from the perspective of tribofilm of lubricating oil containing ZDDP using SEM/EDS, Raman spectrometer, atomic force microscope (AFM) etc. It was found that ZDDP tribofilm containeda little graphitic carbon and iron oxides besides metal phosphates and sulfides. The bonding of ZDDP tribofilmto the substrate was stronger than that of base oil (poly-alpha-olefin, PAO) tribofilm. The mechanicalproperties of ZDDP tribofilm were more stable than those of PAO tribofilm. Statistical analysisrevealed that ZDDP tribofilm was harder and less adhesive effects than PAO tribofilm, which might provideit with the ability to resist abrasive and adhesive wear. The similar elastic modulus of the two kindsof films indicated their similar plastic deformation. Moreover, the micro friction-reducing ability of ZDDPtribofilm might be the origin of ZDDP reducing the macro friction under boundary lubrication.

Active Disturbance Rejection Control Based on Extended State Observer for Three-Phase Battery Energy Storage Power Conversion System with LCL Filter

Gao Ning,Lin Xin,Lu Song,Xia Yue,Wu Weimin 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.2

Utilizing battery energy storage system is considered to be a reliable approach to improve the stability of modern power grid. By properly controlling the battery energy storage system, the redundant power can be absorbed and the lack of power can be supplemented. The control strategy of power conversion system directly aff ects the performance of battery energy storage system. Therefore, an improved active disturbance rejection control algorithm for power conversion system with LCL fi lter is presented in this paper. First of all, a pole placement strategy based on full state feedback is implemented in order to solve the resonance problem of LCL fi lter. Secondly, the total internal and external disturbances of power conversion system are compensated on basis of a linear extended state observer for purpose of improving the system robustness against inevitable interferences and parameter uncertainty. Furthermore, the stability of presented control strategy is analyzed and discussed in detail. Finally, the simulation and experimental results extracted based on a 2.6 kVA prototype are both provided, which can confi rm the feasibility and correctness of the control strategy.

Device-to-Device assisted user clustering for Multiple Access in MIMO WLAN

( Zhao Hongyi ),( Wu Weimin ),( Lu Li ),( Liu Yingzhuang ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.7

WLAN is the best choice in the place where complex network is hard to set up. Intelligent terminals are more and more assembled in some areas now. However, according to IEEE 802.11n/802.11ac, the access-point (AP) can only serve one user at a single frequency channel. The spectrum efficiency urgently needs to be improved. In theory, AP with multi-antenna can serve multiple users if these users do not interfere with each other. In this paper, we propose a user clustering scheme that could achieve multi-user selection through the mutual cooperation among users. We focus on two points, one is to achieve multi-user communication with multiple antennas technique at a single frequency channel, and the other one is to use a way of distributed users` collaboration to determine the multi-user selection for user clustering. Firstly, we use the CSMA/CA protocol to select the first user, and then we set this user as a source node using users` cooperation to search other proper users. With the help of the users` broadcast cooperation, we can search and select other appropriate user (while the number of access users is limited by the number of antennas in AP) to access AP with the first user simultaneously. In the network node searching, we propose a maximum degree energy routing searching algorithm, which uses the shortest time and traverses as many users as possible. We carried out the necessary analysis and simulation to prove the feasibility of the scheme. We hope this work may provide a new idea for the solution of the multiple access problem.

The effect of Al and B on the luminescent property of porous silicon

Yue Zhao,Zhiyong Lv,Linjun Wang,Jiahua Min,Weimin Shia,Xudong Lu 한국물리학회 2010 Current Applied Physics Vol.10 No.3

In this paper, we studied the PL property and the surface morphology of porous silicon prepared from Ntype single silicon wafers coated with and without Al film. By introducing the Al film on the surface of silicon wafer before etching, the morphology of porous silicon exhibits obvious discrimination compared with that of the conventional porous silicon, which can be explained by the formation mechanism of the samples, and the emission property of two-type porous silicon also showed the clear difference, which may be attributed to the discrepancy in the structural configuration of the samples. Furthermore, it was found that the blue emission decreased and the green emission was almost completely quenched after boron-particle deposition, which is attributed to the structural change or annihilation of the emission defects during annealing process.

A stable and highly efficient visible-light-driven hydrogen evolution porous CdS/WO₃/TiO₂ photocatalysts

Qian, Yongteng,Yang, Mengke,Zhang, Fangfang,Du, Jimin,Li, Kaidi,Lin, Xialing,Zhu, Xinrui,Lu, Yayun,Wang, Weimin,Kang, Dae Joon Elsevier 2018 Materials characterization Vol.142 No.-

<P><B>Abstract</B></P> <P>It is well known that both catalytic efficiency and stability are the two important parameters of photocatalysts for visible-light-driven hydrogen production reactions. However, light-driven hydrogen evolution based applications still suffer from sluggish reaction kinetics due to the lack of high-performance photocatalysts. In this paper, we successfully synthesized a ternary porous CdS/WO<SUB>3</SUB>/TiO<SUB>2</SUB> photocatalyst with high efficiency and stability via two-stage approach. The as-prepared samples are characterized by XRD, FESEM, EDS, TEM, XPS, and UV–Vis, respectively, which illustrated that the CdS and WO<SUB>3</SUB> moieties are in-situ formed inside the porous TiO<SUB>2</SUB>. Particularly, the photocatalytic hydrogen (H<SUB>2</SUB>) evolution rate of such ternary 8% CdS/WO<SUB>3</SUB>/TiO<SUB>2</SUB> (molar ration of CdS:WO<SUB>3</SUB>:TiO<SUB>2</SUB> = 8:8:100) photocatalyst ranges up to 2106 μmol h<SUP>−1</SUP> g<SUP>−1</SUP> under visible-light irradiation, which is higher than that of pure TiO<SUB>2</SUB> and other binary (CdS/TiO<SUB>2</SUB> and WO<SUB>3</SUB>/TiO<SUB>2</SUB>) porous photocatalysts. The superior H<SUB>2</SUB> evolution efficiency can be attributed to the coexistence of CdS and WO<SUB>3</SUB> in porous TiO<SUB>2</SUB> which can promote the interfacial charge transfer and separation as well as extend the light absorption up to the visible range.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Highly efficient and stable photocatalytic activity of CdS/WO<SUB>3</SUB>/TiO<SUB>2</SUB> photocatalysts were synthesized by a two-step method. </LI> <LI> CdS and WO<SUB>3</SUB> inlaid on porous TiO<SUB>2</SUB> can extend the light absorption and enhance photogenerated electron-hole pairs separation. </LI> <LI> The porous structure can provide more reaction active sites and improve photoproduced-electrons and holes transport speed. </LI> </UL> </P> <P><B>Graphical Abstract</B></P> <P>[DISPLAY OMISSION]</P>

The stacked over-expression of FPS, CYP71AV1 and CPR genes leads to the increase of artemisinin level in Artemisia annua L.

nter, Shanghai Jiao Tong University,Chen, Yunfei,Shen, Qian,Wang, Yueyue,Wang, Tao,Wu, Shaoyan,Zhang, Ling,Lu, Xu,Zhang, Fangyuan,Jiang, Weimin,Qiu, Bo,Gao, Erdi,Sun, Xiaofen,Tang, Kexuan 한국식물생명공학회 2013 Plant biotechnology reports Vol.7 No.3

Rheinic acid ameliorates radiation‑induced acute enteritis in rats through PPAR‑γ/NF‑κB

Haixia Sha,Yu Gu,Weixing Shen,Li Zhang,Fei Qian,Yudong Zhao,Haixiao Li,Ting Zhang,Weimin Lu 한국유전학회 2019 Genes & Genomics Vol.41 No.8

Background Acute radiation enteritis (ARE), a common complication of intestinal caused by abdominal and pelvic radiation therapy. Rheinic acid is a major active ingredient derived from Rhubarb. Rhubarb could suppress inflammation, tumor, fibrosis oxidative damage. However, RA as the main active component and extract monomer of Rhubarb, the pharmacological activity and the underlying molecular mechanism on various diseases has not yet been revealed. Objective To determine the potential role of rheinic acid (RA) in ameliorating inflammation of rats with acute radiation enteritis (ARE), and explore the underlying mechanism. Methods ARE rat model was established by irradiated with single-dose 10 Gy X-rays at a rate of 0.62 Gy/min to the abdomen. The rats were executed after orally administered with Rheinic acid 7 days and used in the subsequent experiments. Body weight, fecal characteristics and bloody of rats were used to assess the disease activity index. Histological analysis of the jejunum and colon were evaluated using H&E staining. The pro-inflammatory cytokines levels were measured by immunohistochemistry and ELISA. The levels of nitric oxide (NO), malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione (GSH) were also determined. The mRNA and protein expression were examined by real-time polymerase chain reaction (qRT-PCR) and western blot, respectively. Results Rheinic acid promoted intestinal functional recovery, and ameliorated intestinal damage and bloody stool in ARE rats. Rheinic acid strongly decreased the levels of tumor necrosis factor-α, interleukin-1, interleukin-6, NO, and MDA, whereas increased levels of anti-oxidants, SOD and GSH. Moreover, the expression of apoptosis-related proteins, cleaved caspase-3 and cleaved poly (ADP-ribose) polymerase (PARP), were decreased with RA treatment. Further study indicated that PPAR-γ was activated and thereby NF-κB and p38 MAPK signaling pathway were suppressed after rheinic acid treatment. Conclusion Rheinic acid could ameliorate acute radiation enteritis and the underlying molecular mechanism is, at least partially, through PPAR-γ/NF-κB and p38 MAPK/JNK pathways.

The stacked over-expression of FPS, CYP71AV1 and CPR genes leads to the increase of artemisinin level in Artemisia annua L.

Yunfei Chen,Qian Shen,Yueyue Wang,Tao Wang,Shaoyan Wu,Ling Zhang,Xu Lu,Fangyuan Zhang,Weimin Jiang,Bo Qiu,Erdi Gao,Xiaofen Sun,Kexuan Tang 한국식물생명공학회 2013 Plant biotechnology reports Vol.7 No.3

Artemisinin is an endoperoxide sesquiterpenelactone isolated from the aerial parts of Artemisia annua L.,and is presently the most potent anti-malarial drug. Owingto the low yield of artemisinin from A. annua as well as thewidespread application of artemisinin-based combinationtherapy recommended by the World Health Organization,the global demand for artemisinin is substantially increasingand is therefore rendering artemisinin in short supply. An economical way to increase artemisinin production is toincrease the content of artemisinin in A. annua. In thisstudy, three key genes in the artemisinin biosynthesispathway, encoding farnesyl diphosphate synthase, amorpha-4, 11-diene C-12 oxidase and its redox partner cytochromeP450 reductase, were over-expressed in A. annuathrough Agrobacterium-mediated transformation. Thetransgenic lines were confirmed by Southern blotting andthe over-expressions of the genes were demonstrated byreal-time PCR assays. The HPLC analysis showed that theartemisinin contents in transgenic lines were increasedsignificantly, with the highest one found to be 3.6-foldhigher (2.9 mg/g FW) than that of the control. Theseresults demonstrate that multigene engineering is aneffective way to enhance artemisinin content in A. annua.