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Tribological performance of surface treated piston assembly with infiltrated layer
Bo Xu,Bifeng Yin,Dashu Gao,Xijun Hua 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.1
By applying surface treatment on piston assembly and typical samples, an infiltrated layer with the depth of about 30 μm was formed on the treated sample surface. The surface hardness and linear expansion coefficient of treated piston sample decreased, while the hardness of treated ring sample increased. The results of ball-on-disc rotating friction test indicated that the infiltrated layer is helpful for improving the tribological properties of aluminum alloy, reducing friction coefficient under both dry friction and oil lubricated conditions, and improving the anti-friction and wear resistance performance of cast iron. In addition, the reciprocating friction testing results showed that surface treatment technology has stable antifriction effect on piston/liner pair under various working conditions, with the average friction coefficient being reduced by about 10.2-22.1 %; while the anti-friction effect on ring/liner pair is mainly reflected under low-speed heavy-load condition, with the average friction coefficient being reduced by approximately 7.2-9.9 %.
Xu, Hai Bo,Kim, Jeong Hun,Kim, Sangtae,Hwang, Hee Jae,Maurya, Deepam,Choi, Dukhyun,Kang, Chong-Yun,Song, Hyun-Cheol Elsevier 2019 Nano energy Vol.62 No.-
<P><B>Abstract</B></P> <P>Triboelectric generators (TEG), based on contact electrification and electro-static induction, has received a significant attention because of their numerous applications. To improve the electrified surface charge density in TEG, increasing the surface area of dielectric materials or forming internal hollow structures are typically employed to increase capacitance. However, the fabrication processes of such structures are complex and time-consuming. Here, we provide a facile and cost-effective synthesis method for the porous PDMS based TEG via a novel vapor encapsulation casting (VEC). The double dielectric layer composed of the porous and dense PDMS layers are formed in-site through VEC. The thickness and the thickness ratio of the double dielectric layer can be precisely controlled by adjusting the uncured PDMS thickness and vapor penetration depth. The double dielectric layer TEG (DTEG) exhibits the improved harvesting performance because the porous dielectric layer increases the capacitance and compressibility, while the dense layer passivates the fully open pores which reduce the charging surface area as completely opening through the dielectric layer without contacting the bottom electrode. We obtain the maximum output voltage of 345 V and short circuit current of 3 μA/cm<SUP>2</SUP> from DTEG having 0.95 porous thickness ratio, resulting 330% enhancement in the power output as compared to the dense PDMS based TEG. We further investigate the performance of DTEG under various operating conditions. We also demonstrate the operation of Bluetooth distance/temperature sensors using capacitors charged by DTEG.</P> <P><B>Highlights</B></P> <P> <UL> <LI> TEG based on the double dielectric layer composed of the sponge-like porous and flat dense elastomer is demonstrated. </LI> <LI> Facile and affordable synthesis method for the porous PDMS is provided via the novel vapor encapsulation casting. </LI> <LI> Highly deformable porous PDMS effectively enhances its capacitance under a pressure. </LI> <LI> Flat dense second layer of PDMS reduces the device impedance and improves the contact interface with an electrode. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Bo Xu,Yingzhe WANG,Shixin ZHU,Haizhu ZHOU,Changlong GOU,Wenlong DONG,Yu Wang,Yunhang GAO,Hongxia MA 한국곤충학회 2019 Entomological Research Vol.49 No.1
Chalkbrood, which results from Ascosphaera apis infection, is one of the bee diseases that causes serious damage to the bee colony. Understanding the molecular bases underlying immune response to chalkbrood disease would facilitate the genetic breeding of bees by selecting races with superior chalkbrood resistance. In this study, transcriptome sequencing was performed to identify genes and pathways involved in the immune response to As. apis infection in A. mellifera larvae. In total, 2,890 differentially expressed genes (DEGs) (FDR < 0.001) were identified between the healthy and As. apis infected bee larvae, including 2,214 up‐regulated and 676 down‐regulated unigenes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway classification of the DEGs revealed association with development, energy metabolism, signal transduction, disease, and immune response. Among the immune‐related genes, p38, toll‐like receptors (TLRs), integrin, and antimicrobial peptides were up‐regulated under As. apis infection. This study provides valuable gene transcriptional information towards the investigation of molecular mechanisms related to chalkbrood immune response and host pathogenesis in A. mellifera.
( Bo Xu ),( Fu Ya Yang ),( Cai Yun Xiong ),( Jun Jun Li ),( Xiang Hua Tang ),( Jun Pei Zhou ),( Zhen Rong Xie ),( Jun Mei Ding ),( Yun Juan Yang ),( Zun Xi Huang ) 한국미생물 · 생명공학회 2014 Journal of microbiology and biotechnology Vol.24 No.4
To isolate novel and useful microbial enzymes from uncultured gastrointestinal microorganisms, a fecal microbial metagenomic library of the pygmy loris was constructed. The library was screened for amylolytic activity, and 8 of 50,000 recombinant clones showed amylolytic activity. Subcloning and sequence analysis of a positive clone led to the identification a novel gene (amyPL) coding for α-amylase. AmyPL was expressed in Escherichia coli BL21 (DE3) and the purified AmyPL was enzymatically characterized. This study is the first to report the molecular and biochemical characterization of a novel α-amylase from a gastrointestinal metagenomic library.
( Bo Xu ),( Li Ming Dai ),( Jun Jun Li ),( Meng Deng ),( Hua Biao Miao ),( Jun Pei Zhou ),( Yue Lin Mu ),( Qian Wu ),( Xiang Hua Tang ),( Yun Juan Yang ),( Jun Mei Ding ),( Nan Yu Han ),( Zun Xi Huang 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.1
Xylanases sourced from different bacteria have significantly different enzymatic properties. Therefore, studying xylanases from different bacteria is important to their applications in different fields. A potential xylanase degradation gene in Massilia was recently discovered through genomic sequencing. However, its xylanase activity remains unexplored. This paper is the first to report a xylanase (XynRBM26) belonging to the glycosyl hydrolase family (GH10) from the genus Massilia. The gene encodes a 383-residue polypeptide (XynRBM26) with the highest identity of 62% with the endoxylanase from uncultured bacterium BLR13. The XynRBM26 expressed in Escherichia coli BL21 is a monomer with a molecular mass of 45.0 kDa. According to enzymatic characteristic analysis, pH 5.5 is the most appropriate for XynRBM26, which could maintain more than 90% activity between pH 5.0 and 8.0. Moreover, XynRBM26 is stable at 37°C and could maintain at least 96% activity after being placed at 37°C for 1 h. This paper is the first to report that GH10 xylanase in an animal gastrointestinal tract (GIT) has salt tolerance, which could maintain 86% activity in 5 M NaCl. Under the optimum conditions, Km, Vmax, and kcat of XynRBM26 to beechwood xylan are 9.49 mg/ml, 65.79 μmol/min/mg, and 47.34 /sec, respectively. Considering that XynRBM26 comes from an animal GIT, this xylanase has potential application in feedstuff. Moreover, XynRBM26 is applicable to high-salt food and seafood processing, as well as other high-salt environmental biotechnological fields, because of its high catalytic activity in high-concentration NaCl.
Bo Xu,Zhihua Jin,Qingchao Jin,Ninghui Li,Peilin Cen 한국생물공학회 2009 Biotechnology and Bioprocess Engineering Vol.14 No.2
To isolate an improved pristinamycin producing strain of Streptomyces pristinaespiralis, the technique of Genome shuffling was used which resulted in a high-yield recombinant G 3-56 strain. Strain G 3-56 yielded 322 ± 17 mg/L of pristinamycin which was 11.4-fold higher than that of the initial strain and 3.7-fold higher than strain UN-78 which previously had the highest yield of pristinamycin. The genetic characteristics of the recombinant G 3-56 strain was stable as revealed by our subculture experiments. The optimal production medium was determined using the orthogonal matrix method. Under the optimal medium conditions, the maximum yield of pristinamycin was 412 mg/L with about 1.24-fold higher than the original medium. To isolate an improved pristinamycin producing strain of Streptomyces pristinaespiralis, the technique of Genome shuffling was used which resulted in a high-yield recombinant G 3-56 strain. Strain G 3-56 yielded 322 ± 17 mg/L of pristinamycin which was 11.4-fold higher than that of the initial strain and 3.7-fold higher than strain UN-78 which previously had the highest yield of pristinamycin. The genetic characteristics of the recombinant G 3-56 strain was stable as revealed by our subculture experiments. The optimal production medium was determined using the orthogonal matrix method. Under the optimal medium conditions, the maximum yield of pristinamycin was 412 mg/L with about 1.24-fold higher than the original medium.
Xu, Guo-Bo,Yang, Tao,Bao, Jin-Ku,Fang, Dong-Mei,Li, Guo-You 대한약학회 2014 Archives of Pharmacal Research Vol.37 No.5
Isochaetomium $A_2$ (1), a new bis(naphthodihydropyran-4-one), along with chaetochromins A (2) and B (3), was isolated from the solid-state fermented rice culture of Chaetomium microcephalum. The structure of compound 1 was elucidated on the basis of 1D and 2D NMR spectral data, and the relative configuration was confirmed by CD spectrum. Compounds 1-3 possessed significant antimicrobial activity against Escherichia coli 1.044, Staphylococcus aureus 1.252, and Bacillus subtilis 1.079. Moreover, compounds 1-3 showed obvious inhibitory effects on mouse spleen cell proliferation with successive $IC_{50}$ values of 0.52, 0.19, and $0.24{\mu}M$.