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>

FNC, a Novel Nucleoside Analogue, Blocks Invasion of Aggressive Non-Hodgkin Lymphoma Cell Lines Via Inhibition of the Wnt/β-Catenin Signaling Pathway

Zhang, Yan,Wang, Chen-Ping,Ding, Xi-Xi,Wang, Ning,Ma, Fang,Jiang, Jin-Hua,Wang, Qing-Duan,Chang, Jun-Biao Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.16

Chemotherapy is the primary therapy for malignant lymphoma (ML). However, the clinical outcome is still far from satisfactory. Consequently, an understanding of the mechanism of modulating cancer cell invasion, migration and metastasis is important for the development of more effective chemotherapeutic agents. FNC, 2'-deoxy-2'-${\beta}$-fluoro-4'-azidocytidine, a novel cytidine analogue, has demonstrated significantly inhibitory effects on proliferation of several non-Hodgkin lymphoma (NHL) cell lines. A previous study indicated that FNC effectively inhibited the growth of Raji and JeKo-1 cells in dose-time dependent effects with $IC_{50}$ values of $0.2{\mu}M$ and $0.097{\mu}M$, respectively. This study was focused on investigating the anti-invasive properties of FNC on NHL cells and its potential mechanisms of action. Cell adhesion and transwell chamber assays were utilized to investigate the anti-invasive effects of FNC on Raji and JeKo-1 cells. Real-time PCR and Western blotting were employed to qualify the expression of ${\beta}$-catenin, the glycogen synthase kinase-3 beta (GSK-$3{\beta}$), E-cadherin vascular endothelial growth factor (VEGF), matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9). The results revealed that FNC remarkably inhibited the adhesion, migration and invasion of two human aggressive non-Hodgkin lymphoma cell lines in a dose dependent manner. Furthermore, ${\beta}$-catenin, MMP-2, MMP-9, VEGF mRNA and protein levels were decreased after FNC treatment, while GSK-$3{\beta}$ and E-cadherin increased. Our studies thus provide evidence and a rationale that FNC may offer an effective chemotherapeutic agent by regulating the invasion and metastasis of aggressive non-Hodgkin lymphoma via inhibition of the Wnt/${\beta}$-catenin signaling pathway.

Experimental study on Chinese ancient timber-frame building by shaking table test

Xi-cheng Zhang,Jian-yang Xue,Hong-tie Zhao,Yan Sui 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.4

A one-story, wooden-frame, intermediate-bay model with Dou-Gon designed according to the Building Standards of the Song Dynasty (A.D.960-1279), was tested on a unidirectional shaking table. The main objectives of this experimental study were to investigate the seismic performance of Chinese historic wooden structure under various base input intensities. El Centro wave (N-S), Taft wave and Lanzhou wave were selected as input excitations. 27 seismic geophones were instrumented to measure the real-time displacement, velocity and acceleration respectively. Dynamic characteristics, failure mode and hysteretic energy dissipation performance of the model are analyzed. Test results indicate that the nature period and damping ratio of the model increase with the increasing magnitude of earthquake excitation. The nature period of the model is within 0.5~0.6 s, the damping ratio is 3~4%. The maximum acceleration dynamic magnification factor is less than 1 and decreases as the input seismic power increases. The frictional slippage of Dou-Gon layers (corbel brackets) between beams and plates dissipates a certain amount of seismic energy, and so does the slippage between posts and plinths. The mortise-tenon joint of the timber frame dissipates most of the seismic energy. Therefore, it plays a significant part in shock absorption and isolation.

Letters to the Editor : Evaluation of the Potential Association between NOS Gene Polymorphisms (iNOS G-954C and eNOS G894T) and Psoriasis

( Xi Duan ),( Yan Cheng ),( Linbo Gao ),( Lijuan Li ),( Tao Wang ),( Min Zhang ) 대한피부과학회 2016 Annals of Dermatology Vol.28 No.1

HPLC Determination of Malondialdehyde in ECV304 Cell Culture Medium for Measuring the Antioxidant Effect of Vitexin-4"-O-glucoside

Xi-xiang Ying,Hai-bo Li,Zheng-yun Chu,Yan-jun Zhai,Ai-jing Leng,Xun Liu,Wen-jie Zhang,Ting-guo Kang,Chun Xin 대한약학회 2008 Archives of Pharmacal Research Vol.31 No.7

To investigate the antioxidant effect of vitexin-4"-O-glucoside, a flavone glycoside, isolated from the leaves of Crataegus pinnatifida Bge. var. major, we developed a simple and sensitive high-performance liquid chromatography (HPLC) method to determine levels of malondialdehyde (MDA) in ECV304 cell culture medium after induction by tert-butyl-hydroperoxide (TBHP). The preparation of analyzed samples involved a one-step derivatization with thiobarbituric acid (TBA). HPLC analysis was performed on a SynergiTM Hydro-RP, a polar end-capped C18 column (250×4.6 mm, 4 μm), using an acetonitrile-ammonium acetate aqueous solution (10 mM, pH 6.8) as the mobile phase under linear gradient conditions with UV detection at 532 nm. The calibration curve was linear over 0.0125-1.25 μM MDA (r = 0.9951). Relative standard deviations (RSDs) of intra-day and inter-day precision were less than 6.1% and 5.0%, respectively. The mean recovery was 96.9 ± 1.6%. The lower limit of quantification (LLOQ) of MDA was 0.0125 μM. This chromatographic method was successfully applied to investigating the in vitro antioxidant effect of vitexin-4"-O-glucoside. Vitexin-4"-O-glucoside (120 M) protected ECV304 cells from peroxidation induced by TBHP.

Experimental study on Chinese ancient timber-frame building by shaking table test

Zhang, Xi-Cheng,Xue, Jian-Yang,Zhao, Hong-Tie,Sui, Yan Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.4

A one-story, wooden-frame, intermediate-bay model with Dou-Gon designed according to the Building Standards of the Song Dynasty (A.D.960-1279), was tested on a unidirectional shaking table. The main objectives of this experimental study were to investigate the seismic performance of Chinese historic wooden structure under various base input intensities. El Centro wave (N-S), Taft wave and Lanzhou wave were selected as input excitations. 27 seismic geophones were instrumented to measure the real-time displacement, velocity and acceleration respectively. Dynamic characteristics, failure mode and hysteretic energy dissipation performance of the model are analyzed. Test results indicate that the nature period and damping ratio of the model increase with the increasing magnitude of earthquake excitation. The nature period of the model is within 0.5~0.6 s, the damping ratio is 3~4%. The maximum acceleration dynamic magnification factor is less than 1 and decreases as the input seismic power increases. The frictional slippage of Dou-Gon layers (corbel brackets) between beams and plates dissipates a certain amount of seismic energy, and so does the slippage between posts and plinths. The mortise-tenon joint of the timber frame dissipates most of the seismic energy. Therefore, it plays a significant part in shock absorption and isolation.

Ethylene/propylene separation using mixed matrix membranes of poly (ether block amide)/nano-zeolite (NaY or NaA)

Xi Zhang,Mengyu Yan,Xianshe Feng,Xiaodong Wang,Wei Huang 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.3

Generally, the energy and capital intensive cryogenic distillation process is applied to separate light olefins. To lower the cost of light olefin production, mixed matrix membranes (MMMs) incorporating nano-zeolite (NaY or NaA) into a rubbery poly (ether block amide) (PEBA 2533) were fabricated to separate a propylene/ethylene mixture. The effect of additive content and kind, MMM thickness, and operating temperature and pressure on the separation performance of the synthesized membranes for a propylene/ethylene mixture were investigated. As an additive, NaY was found to be more effective than NaA. Interestingly, the result of pure gas adsorption was consistent with the permeation performance of the membranes. Membranes with 6 wt% NaY showed the highest C3H6/C2H4 selectivity in all synthesized membranes (3 wt%-10 wt%), on which, the C3H6/C2H4 selectivity was increased from 2.3 to 13.1, the permeability of propylene increased from 194 barrer to 262 barrer and the permeability of ethylene decreased from 85 barrer to 19.8 barrer when the propylene concentration in feed mixture increased from 10 mol% to 80 mol% at 35 o C and 0.2 MPa. This membrane has the potential to separate propylene and ethylene in industry, and this work will push forward the membrane separation process for olefin production.

Study on Joint Simulation of Very Fast Transient Overvoltage and Transient Enclosure Voltage in 1000 kV GIS

Zhang Yan-Ze,Chen Xiao-Yue,Si Jun-Jie,He Ze-Yu,Wen Xi-Shan 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.5

Disconnector operation in GIS generates VFTO and TEV, which threaten device insulation and personnel safety. In order to calculate VFTO and TEV more accurately, this paper proposes a VFTO-TEV joint simulation model. Among them, dynamic arc model is used to reflect the dynamic characteristics of high frequency AC arc. In order to reflect the electromagnetic leakage phenomenon caused by the impedance mismatch of high-frequency electromagnetic waves, and the influence of the transient potential difference formed by the transient electromagnetic field on grounding grid on TEV, the geometric structures of high-voltage bushing, grounding pillars and grounding grid are modeled to obtain their respective frequency-dependent admittance matrices, which are converted into corresponding broadband equivalent circuit models by combining vector fitting method and impedance synthesis method. The above modeling method is applied to the 1000 kV GIS test circuit, and the simulation model is built in the ATP-EMTP electromagnetic transient program, and the joint simulation research of VFTO and TEV is carried out. The results show that at each measurement point of the test circuit, the amplitude error of the VFTO obtained by simulation and actual measurement is mostly less than 7%, and the frequency spectrum both contains the main frequency components of 18 MHz and 25 MHz; Compared with the traditional calculation model of obtaining VFTO/TEV using CIGRE model/Petersen's law, the amplitude of VFTO and TEV obtained by joint simulation model is lower and contains richer high-frequency components. In addition, the opening speed of 0.8 m/s also corresponds to the maximum point of the VFTO amplitude of the test circuit. Finally, based on the above modeling method, the effectiveness of adding ferrite beads to suppress VFTO is verified by simulation. © 2017 Elsevier Inc. All rights reserved.

Effects of winter and spring housing on growth performance and blood metabolites of Pengbo semi-wool sheep in Tibet

Yan Mei Jin,Xiao Qing Zhang,Warwick B Badgery,Peng Lin,Jun Xi Wu 아세아·태평양축산학회 2019 Animal Bioscience Vol.32 No.10

Objective: Sixty Pengbo semi-wool sheep ewes (approximately 1.5-years-old; 31.33±0.43 kg) were randomly assigned to two groups, either grazing (G) or dry lot feeding (D), to examine the effects of traditional daily grazing and dry lot feeding on performance and blood metabolites during the cold season in Tibetan Plateau. Methods: The ewes in the G group were grazed continuously each day and housed in one shed each evening, while the ewes in the D group were housed in another shed all day. All animals were fed 400 g/d of commercial concentrate, and grass hay was available freely throughout the experimental period. Results: Compared with the G group, the ewes in the D group had higher (p<0.05) live weight and weight gain. The D group ewes had greater (p<0.05) numbers of white blood cells and platelets, while they had lower (p<0.05) platelet-large cell ratios, cholesterol, high-density lipoprotein cholesterol and glutathione peroxidase, as compared with the G group ewes. Additionally, three serum metabolites, abscisic acid, xanthoxin and 3,4-dihydroxy-5-polypren, were upregulated (p<0.05) in the G group in comparison with the D group. Conclusion: In conclusion, a dry lot feeding regime during the winter and spring period will increase the productivity of sheep and improve blood physiological and biochemical profiles.

LKB1 on POMC neurons affect the formation of diet-induced obesity by regulating the expression of HDAC1

Zhang Yan,Wu Zhaoxia,Xi Pengjiao,Wang Haomin,Zhu Wenjuan,Tian Derun 한국유전학회 2022 Genes & Genomics Vol.44 No.4

Background: Obesity is considered a major public health issue worldwide. Liver Kinase B1 (LKB1) is a serine/threonine kinase, peripheral LKB1 is involved in obesity by regulating adipogenesis, but the role of central LKB1 in the development of obesity remains unclear. Objective: This study aims to explore the main role of LKB1 in POMC neurons on obesity, and reveal the underlying mechanism of central LKB1 affecting obesity through quantitative proteomics. Methods: We constructed POMC neuron specific LKB1 knockout mice (PomcLkb1 KO) and exposed them to high fat diet intervention for three months. The effect of LKB1 knockout on obesity was evaluated by monitoring body weight, food intake and measuring fat content. The hypothalamus tissues were collected for proteomic analysis and validated by RT-PCR. Results: The degree of obesity was aggravated in PomcLkb1 KO mice fed with high fat diet. Proteomic results showed that only Histone deacetylase 1 (HDAC1) was down-regulated in the hypothalamus of PomcLkb1 KO mice. Our research also found that LKB1 knockout on POMC neurons led to reduction of Peroxisome proliferator-activated receptor γ (PPARγ). Meanwhile, the software predicted that the transcription factor PPARγ binds to the HDAC1 promoter. Therefore, we speculated that central LKB1 may regulate diet-induced obesity development by influencing HDAC1/PPARγ expression. Conclusion: We firstly found that central LKB1 may affect the development of obesity by regulating the expression of HDAC1, which provides a new idea for the central regulatory mechanism of obesity.