Electrical Contact Characteristics of Ag-SnO₂ Materials with Increased SnO₂ Content

Chen, Pengyu,Liu, Wei,Wang, Yaping The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.6

The electrical contact characteristics including temperature rise, contact resistance and arc erosion rate of the $Ag-SnO_2$ materials with increased $SnO_2$ content were investigated during the repeated make-and-break operations. The thickness of arcing melting layer reduces by half and the arc erosion rate decreases more than 70% under 10000 times operations at AC 10 A with the $SnO_2$ content increasing from 15 wt.% to 45 wt.%, on one hand, temperature rise and contact resistance increase obviously but could be reduced to the same order of conventional $Ag-SnO_2$ materials by increasing the contact force. The microstructure evolution and the effect of $SnO_2$ on the arc erosion, contact resistance were analyzed.

Electrical Contact Characteristics of Ag-SnO₂ Materials with Increased SnO₂ Content

Pengyu Chen,Wei Liu,Yaping Wang 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.6

The electrical contact characteristics including temperature rise, contact resistance and arc erosion rate of the Ag-SnO₂ materials with increased SnO₂ content were investigated during the repeated make-and-break operations. The thickness of arcing melting layer reduces by half and the arc erosion rate decreases more than 70% under 10000 times operations at AC 10 A with the SnO₂ content increasing from 15 wt.% to 45 wt.%, on one hand, temperature rise and contact resistance increase obviously but could be reduced to the same order of conventional Ag-SnO₂ materials by increasing the contact force. The microstructure evolution and the effect of SnO₂ on the arc erosion, contact resistance were analyzed.

Rainwater Harvesting with Treatment and Utilization in an Interchange Ramp Area of Highway

Youyuan Chen,Yaping Li,Bo Hong,Meijun Feng,Bin Dong 한국도시환경학회 2010 한국도시환경학회지 Vol.10 No.2

Manufacturing Principle and Meshing Limit Line of Toroidal Surface Enveloping Cylindrical Worm Drive with Arc-Toothed Worm

Xinyue Zhu,Yaping Zhao,Yifei Chi,Gongfa Li,Xinyuan Chen 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.23 No.3

The main purpose of this article is to determine the processing parameters of the worm and establish the theory of the meshing limit line of toroidal surface enveloping cylindrical worm drive with the arc-toothed worm. Based on this condition that the instantaneous contact line is a planar curve during grinding the worm blank, it can be deduced that its torsion is equal to zero, then the formulae which determine the installing position of the grinding wheel are acquired. Following this, the equations of the tooth surfaces and the meshing limit function are all obtained. According to the geometric construction and elimination method, the meshing limit points are determined by iteratively solving the corresponding nonlinear equation in its solution domain. In addition, the result of the numerical case demonstrates that the worm helicoid is divided into two parts by the meshing limit line, which makes the working length of the worm cannot reach half of its total thread length. And by adjusting the design parameters of the worm pair and the processing parameters of the worm, the meshing limit line cannot be eliminated and its position on the surfaces of the worm and the worm gear has no notable change.

Physical Layer Security for Two-Way Relay NOMA Systems with Energy Harvesting

Hui Li,Yaping Chen,Borong Zou 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.6

Due to the wide application of fifth generation communication, wireless sensor networks have become an indispensable part in our daily life. In this paper, we analyze physical layer security for two-way relay with energy harvesting (EH), where power splitter is considered at relay. And two kinds of combined methods, i.e., selection combining (SC) and maximum ratio combining (MRC) schemes, are employed at eavesdropper. What’s more, the closed-form expressions for security performance are derived. For comparison purposes, this security behaviors for orthogonal multiple access (OMA) networks are also investigated. To gain deeper insights, the end-to-end throughput and approximate derivations of secrecy outage probability (SOP) under the high signal-to-noise ratio (SNR) regime are studied. Practical Monte-Carlo simulative results verify the numerical analysis and indicate that: i) The secure performance of SC scheme is superior to MRC scheme because of being applied on eavesdropper; ii) The secure behaviors can be affected by various parameters like power allocation coefficients, transmission rate, etc; iii) In the low and medium SNR region, the security and channel capacity are higher for cooperative non-orthogonal multiple access (NOMA) systems in contrast with OMA systems; iv) The systematic throughput can be improved by changing the energy conversion efficiency and power splitting factor. The purpose of this study is to provide theoretical direction and design of secure communication.

Selective surface functionalization at regions of high local curvature in graphene

Wu, Qingzhi,Wu, Yaping,Hao, Yufeng,Geng, Jianxin,Charlton, Matthew,Chen, Shanshan,Ren, Yujie,Ji, Hengxing,Li, Huifeng,Boukhvalov, Danil W.,Piner, Richard D.,Bielawski, Christopher W.,Ruoff, Rodney S. The Royal Society of Chemistry 2013 Chemical communications Vol.49 No.7

<P>Monolayer graphene was deposited on a Si wafer substrate decorated with SiO<SUB>2</SUB> nanoparticles (NPs) and then exposed to aryl radicals that were generated <I>in situ</I> from their diazonium precursors. Using micro-Raman mapping, the aryl radicals were found to selectively react with the regions of graphene that covered the NPs. The enhanced chemical reactivity was attributed to the increased strain energy induced by the local mechanical deformation of the graphene.</P> <P>Graphic Abstract</P><P>Due to the increased strain energy caused by local mechanical deformation, aryl radicals were found to selectively react with regions of graphene that were curved by underlying SiO<SUB>2</SUB> nanoparticles. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2cc36747e'> </P>

Variations of microbial community in Aconitum carmichaeli Debx. rhizosphere soilin a short-term continuous cropping system

Fei Xia,Lina Wang,Jiayang Chen,Meng Fu,Guodong Wang,Yaping Yan,Langjun Cui 한국미생물학회 2021 The journal of microbiology Vol.59 No.5

Aconitum carmichaeli Debx. (Ranunculaceae) is a potential source of an important herbal drug named “Fuzi”, which is derived from the lateral root of the plant. Increased therapeutic usage resulted in the great demand for artificial cultivation of A. carmichaeli, however, the obstacles caused by continuous cropping is a serious problem. Continuous cropping has shown to affect the soil biological and non-biological factors. The current study attempted to discover the variations of microbial communities and soil properties in shortterm continuous cropping of A. carmichaeli. An experimental procedure with A. carmichaeli planted two years continuously was established. The variation of the soil microbial community, disease incidence, soil properties, and the correlation between soil microbe and disease incidence were investigated. The disease incidence increased during the continuous cropping of A. carmichaeli. The PCoA and LefSe results indicated that fungal communities in rhizosphere soil were altered during the short-term continuous croppingand the bacterial community was disturbed by the cultivation of A. carmichaeli, however, in the following two years of continuous cropping period, the soil bacterial community has not changed obviously. Proportions of some fungal and bacterial genera were varied significantly (p < 0.05), and some genera of microflora showed a significant correlation with adisease incidence of A. carmichaeli. Microorganisms contributing to community composition discrepancy were also elucidated. Continuous cropping of A. carmichaeli disturbed the rhizosphere soil microbial community and altered the soil chemical parameters and soil pH. These variations in soil may be related to the occurrence of plant diseases. The current study will not only provide theoretical and experimental evidence for the A. carmichaeli continuous cropping obstacles but will also contribute to A. carmichaeli agricultural production and soil improvement.

Electrorheological properties of poly[N,N0-(2-amino-5-carboxybutyl-1,3- phenylenedimethylene)-2,20-diamino-4,40-bithiazole]

Song Xinrong,Song Kunyang,Ding Sha,Chen Yaping,Lin Yuanbin 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.2

Poly[N,N0-(2-amino-5-carboxybutyl-1,3-phenylenedimethylene)-2,20-diamino-4,40-bithiazole] was synthesized and characterized with Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Anhydrous electrorheological (ER) fluids were prepared using the polymer particles as disperse phase and bromodiphenylmethane as a disperse medium. Rheological measurements were carried out via a rotational rheometer to investigate the effects of electric field strength and the polymer particle content on the ER properties. Results indicate that suspensions of the polymer particles containing amino and carboxybutyl groups in bromodiphenylmethane exhibit a substantial ER effect.

Expression and Characterization of a New L-amino Acid Oxidase AAO Producing α-ketoglutaric Acid from L-glutamic Acid

Rao Ben,Liao Xianqing,Liu Fang,Chen Wei,Zhou Ronghua,Ma Lixin,Wang YaPing 한국생물공학회 2019 Biotechnology and Bioprocess Engineering Vol.24 No.6

L-amino acid oxidase (AAO) was reported to be capable of converting L-glutamic acid to α-aketoglutaric acid (α-KG). The sequence of AAO from Kitasatospora cheerisanensis was synthesized based on Pichia pastoris codon-usage preferences. AAO gene was cloned into plasmid pPICZα which was transformed into P. pastoris. Next, multi-copy expression plasmids were constructed by using plasmid pHBM905BDM. High-density fermentation was performed and the recombinant enzyme was characterized. The conversion conditions were optimized. By using Escherichia coli expression system, no soluble or active AAO was obtained from two strains after fermentation and induction. We can’t obtain high-level expression of recombinant strains by using plasmid pPICZα. Therefore, we constructed multi-copy expression plasmids using plasmid pHBM905BDM. By using this plasmid, multi-copy strains were constructed and named as PAAO1, PAAO2, PAAO3, PAAO4, and PAAO5, respectively. The following results showed that expression of AAO in multicopy strains increased as designed and strain PAAO5 was chosen for high-density fermentation and enzyme activity experiments. After high-density fermentation, we achieved an AAO-expression yield of 120.8 U/mL. After temperature and pH optimization, the highest AAO activity was observed at a temperature and pH of 20°C and 6, respectively. After optimization of the conversion conditions, the average production rate of L-glutamic acid to α-KG was 3.46 g/L/h and the highest α-KG titer (103 g/L) was converted from 120 g/L L-glutamic acid. In this study, AAO was abundantly expressed by using P. pastoris expression system. The following experiments indicated that AAO is suitable for use in industrial applications.

Folate-decorated Polysaccharide-doxorubicin Polymer: Synthesis, Characterization, and Activity in HeLa Cells

Lei Zhang,Lulu Guo,Jingna Ding,Yongming Lu,Yaping Zhang,Yan Chen 대한화학회 2015 Bulletin of the Korean Chemical Society Vol.36 No.8

In order to develop the application of the natural polysaccharide lentinan (LNT) and decrease the side effects of doxorubicin, we successfully synthesized a novel folate-modified maleilated lentinan-doxorubicin (FA-M.LNT-DOX) polymer and used it for tumor-targeted drug delivery. The release efficiency and cytotoxicity of the prodrugs were evaluated in vitro. Although DOX release from FA-M.LNT-DOX was quite slow in a neutral buffer, it was particularly fast in an acidic solution with a pH of 5.0. Compared with DOX, FA-M.LNT-DOX showed higher cytotoxicity in HeLa cells and significantly lower cytotoxicity in normal cells. These results suggested that FA-M.LNT-DOX could be considered as a potential drug delivery candidate for folate receptor-positive cancer therapy.