http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Synthesis, Antibacterial Activity, and Structure–Activity Relationship of Fusaric Acid Analogs
Qing-Yan Zhang,Yang Fei‐Yu,Liao Shang‐Gao,Wang Bing,Li Rui,Dong Yong‐Xi,Zhou Meng,Yang Yuan‐Yong,Xu Guo‐Bo 대한화학회 2021 Bulletin of the Korean Chemical Society Vol.42 No.4
Forty-one fusaric acid analogs possessing a pyridine carboxylic acid scaffold have been synthesized. The antibacterial activity results demonstrated that compounds 5b, 7b, 8c, and 8d displayed strong antibacterial activities against Staphylococcus aureus ATCC25923 with minimum inhibitory concentrations (MICs) of 4–16 μg/mL. Molecular docking study indicated that these compounds have strong hydrogen-bonding interactions with TyrRS. Meanwhile, 8c and 8d showed promising antibacterial activities against Pseudomonas aeruginosa ATCC9027. Compound 4 exhibited pronounced antibacterial activities against a clinically isolated multidrug-resistant strain of Escherichia coli (MIC: 64 μg/mL as compared 64 μg/mL of levofloxacin and 1024 μg/mL of ceftriaxone sodium). Moreover, compound 17e displayed strong synergistic antibacterial effect with levofloxacin against the multidrug-resistant strain, decreasing the MIC value of levofloxacin to 1/16 of its original MIC. No obvious cytotoxic activities against LO2 was observed for compounds 4, 5b, 8c, 8d, 17d, and 17e at 50 μM. The preliminary structure–activity relationship of fusaric acid analogs was also discussed.
Effect of joint gap on bead formation in laser butt welding of stainless steel
Zhang, Yan-Xi,Han, Sang-Woo,Cheon, Jason,Na, Suck-Joo,Gao, Xiang-Dong Elsevier 2017 Journal of materials processing technology Vol.249 No.-
<P>Simulations and experiments of laser butt welding are presented in the paper with the laser beam traveling along an inclined line across the gap. Full penetration was observed when the laser beam focused on the gap, while partial penetration was achieved when the laser beam deviated from the gap. A three-dimensional numerical model coupled with a ray tracing algorithm was established to investigate and compare the transient dynamics of the keyhole, molten pool and laser induced plume. The shape of the simulation cross-sections of the welds show good agreement with the experimental results. The gap contributed to transmission of laser beam energy deep into the inner part of the workpiece. The absorbed energy by the workpiece decreased when the laser beam was focused on the gap as some rays escaped through the opening gap. The decrease in absorbed energy resulted in a lower velocity of the molten pool and lower average pressure on the free surface. The velocity and volume of the plume on the top side of the workpiece also decreased. Flow patterns in the molten pool were also identified and discussed.</P>
Xiang-Dong Gao,Yan-Xi Zhang 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.
Morphology of molten pool is significantly associated with welding quality. In this study, an active vision system was designed to form the shadow of a molten pool to get its morphology information during high-power disk laser welding of Type 304 austenitic stainless steel. The shadow was segmented from the recorded images, and four features of the shadow were defined to describe the morphology of a molten pool. The BP (Back propagation) and RBF (Radial based function) neural networks were established to model the relation between the four features and the solid weld width which is the foremost characteristic of weld quality. The effectiveness of two models were compared and analyzed at different welding speeds, and it was found that the BP model had the better results than RBF. The study focuses on predicting the solid weld width by observing the morphology of a molten pool, and provides a necessary foundation for online monitoring and control of weld width during laser welding.
Mu, Xiao-Yan,Dong, Xue-Li,Sun, Jie,Ni, Yu-Hua,Dong, Zhang,Li, Xi-Li,Sun, Er-Lian,Yi, Zhou,Li, Gao Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.1
The effects of erlotinib combined with celecoxib in a lung cancer xenograft model were here explored with a focus on possible mechanisms. A xenotransplanted lung cancer model was established in nude mice using the human lung cancer cell A549 cell line and animals demonstrating tumour growth were randomly divided into four groups: control, erlotinib, celecoxib and combined (erotinib and celecoxib). The tumor major axis and short diameter were measured twice a week and after 40 days tissues were collected for immunohistochemical analyses of Bcl-2 and Bax positive cells and Western-blotting analyses for the epidermal growth factor recepto (EGFR), P-EGFR, and cyclooxygenase-2 (COX-2). Tumor size in the combined group was smaller than in the others (p<0.01) and the percentage of Bcl-2 positive cells was fewer in most cases (p<0.01), while that of Bax positive cells was greater than in the erlotinib and celecoxib groups (P>0.05). Western blotting showed decreased expression of P-EGFR and COX-2 with both erlotinib and celecoxib treatments, but most pronouncedly in the combined group (P<0.05). Simultaneous blockage of the EGFR and COX-2 signal pathways exerted stronger growth effects in our human xenotransplanted lung cancer model than inhibition of either pathway alone. The anti-tumor effects were accompanied by synergetic inhibition of tumor cell apoptosis, activation of p-EGFR and expression of COX-2.
A Computational Investigation of Fuel-Air Mixture Formation in the TR Combustion System
( He Xu ),( Xi Yan Gao ),( Wei Guo Liu ),( Chun Ming Liao ),( De Sheng Yang ) 한국액체미립화학회 2005 한국액체미립화학회 학술강연회 논문집 Vol.2005 No.-
A new combustion system applied in the 135-type diesel engine - TR(Three-Rapidity), was modified from deep cave ω combustion chamber with an oriented arc in the middle of chamber wall, and perfectly fit in a nozzle with orifices in conic section plus orifice in the center. In this paper, three-dimensional numerical simulation was completed and compared on TR combustion system and original 135 diesel engine combustion system. The results show that in TR combustion system, fuel ignition location is near TDC, and premix combustion proportion increases. The oriented arc, contracted cave and centric spray contribute to enhancing air flow, making more reasonable fuel distribution and formatting more homogeneous mixture. The usage of air in chamber is effectively increased and heat loss from the chamber wall is obviously decreased. The cold start performance of the engine is improved also. A performance test on TR combustion system was made on a 135-type diesel engine. The results demonstrate that TR has better exhaust smoke than original engine. At the low and part load, NOX emission of TR combustion system is less than original diesel, but more at high load conditions, which could be solved by delaying fuel spray timing. TR combustion has much potential to improve emission with less structure changed of original engine, so it has large foreground.
Molecular and Biochemical Characterization of a Novel Intracellular Low-Temperature-Active Xylanase
( Jun Pei Zhou,),( Yan Yan Dong ),( Xiang Hua Tang ),( Jun Jun Li ),( Bo Xu ),( Qian Wu ),( Ya Jie Gao ),( Lu Pan ),( Zun Xi Huang ) 한국미생물 · 생명공학회 2012 Journal of microbiology and biotechnology Vol.22 No.4
A 990 bp full-length gene (xynAHJ2) encoding a 329- residue polypeptide (XynAHJ2) with a calculated mass of 38.4 kDa was cloned from Bacillus sp. HJ2 harbored in a saline soil. XynAHJ2 showed no signal peptide, distinct amino acid stretches of glycoside hydrolase (GH) family 10 intracellular endoxylanases, and the highest amino acid sequence identity of 65.3% with the identified GH 10 intracellular mesophilic endoxylanase iM-KRICT PX1-Ps from Paenibacillus sp. HPL-001 (ACJ06666). The recombinant enzyme (rXynAHJ2) was expressed in Escherichia coli and displayed the typical characteristics of low-temperatureactive enzyme (exhibiting optimum activity at 35 o C, 62% at 20 o C, and 38% at 10 o C; thermolability at ≥45 o C). Compared with the reported GH 10 low-temperature-active endoxylanases, which are all extracellular, rXynAHJ2 showed low amino acid sequence identities (<45%), low homology (different phylogenetic cluster), and difference of structure (decreased amount of total accessible surface area and exposed nonpolar accessible surface area). Compared with the reported GH 10 intracellular endoxylanases, which are all mesophilic and thermophilic, rXynAHJ2 has decreased numbers of arginine residues and salt bridges, and showed resistance to Ni 2+ , Ca 2+ , or EDTA at 10 mM final concentration. The above mechanism of structural adaptation for low-temperature activity of intracellular endoxylanase rXynAHJ2 is different from that of GH 10 extracellular low-temperature-active endoxylanases. This is the first report of the molecular and biochemical characterizations of a novel intracellular low-temperatureactive xylanase.
Ze-Long Liu,Xi-Wen Bi,Xue-Wen Zhang,De-Xin Lei,Pan-Pan Liu,Hang Yang,Yan Gao,Yuan-Xue Jiang,Wen-Qi Jiang,Yi Xia 대한암학회 2019 Cancer Research and Treatment Vol.51 No.4
Purpose The extranodal natural killer (NK)/T-cell lymphoma (NKTCL) of non-upper aerodigestive tract (NUAT) was found to have clinical heterogeneity compared with NKTCL of the upper aerodigestive tract (UAT) in small scale studies. We conducted this study in a much larger cohort to analyze the clinical characteristics, prognostic factors, treatment modality, and clinical outcomes of patients with NUAT-NKTCL. Materials and Methods From January 2001 to December 2017, a total of 757 NKTCL patients were identified and included in this study, including 92 NUAT-NKTCL patients (12.2%) and 665 UAT-NKTCL patients (87.8%). Results NUAT-NKTCL patients had relatively poorer performance status, more unfavorable prognostic factors, and more advanced stage, compared with UAT-NKTCL patients. The 5-year overall survival (OS) was 34.7% for NUAT-NKTCL, which was significantly worse than UAT-NKTCL (64.2%, p < 0.001). The median OS duration was 30.9 months for NUAT-NKTCL. Multivariate analysis showed that presence with B symptoms and elevated serum lactate dehydrogenase independently predicted worse OS. International prognostic index score and prognostic index of NK lymphoma score still had prognostic values in NUAT-NKTCL, while the Ann Arbor system could not accurately predict the OS. Conclusion NUAT-NKTCL is a distinctive subtype of NKTCL in many aspects. Patients with NUAT-NKTCL have relatively poorer performance status, more unfavorable prognostic factors, more advanced stage, and poorer prognosis.
Bo Ma,Xiang-Dong Gao,Lin Wang,Yan-Xi Zhang,Nanfeng Zhang,Deyong You 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.6
During multi-layer single-pass additive manufacture based on gas metal arc welding, the formation of product surface is highly affected by the robot welding process status. The thermal history of the manufacturing process was recorded by a thermocouple, and the arc current was collected by a current sensor to investigate the relationship between arc current stability and manufacture workpiece surface formation. The empirical mode decomposition energy entropy of different Z as , which are related to the current stability and utilization of arc power, were calculated. The 3D geometric dimension information of the workpiece was scanned by a laser vision sensing system. Experimental results show the current signal of the arc can be used to assess process stability, current stability caused the temperature of the basement, and surface formation changed. The energy entropy of arc current increased with the increase of Z as . The unstable arc can take away much of the heat generated by the arc heat source leading to the increase of deposition height and side surface roughness.