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FATIGUE ANALYSIS OF WELD REGION IN TORSION BEAM REAR SUSPENSION SYSTEM
Nan Zhan,Xiaochuan Zhang,Xulong Jin,Hongwei Cao 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.2
Torsion beam rear suspension systems have been widely used in small passenger vehicles. However, welding can lead to local stress concentrations, residual stresses and other various defects, which affects the fatigue life of this system. In this paper, 3D digital image correlation (DIC) technique was used to measure the weld region deformation of a torsion beam rear suspension system in the bench test. The test results show that the obvious strain concentration occurred at the welding seam under the cyclic loading. The numerical simulation work by finite element analysis (FEA) has been done to predict the fatigue damage of the torsion beam rear suspension system. The simulation results show that the location of the fatigue crack was at the strain concentration region in the test work. The enhancement test was performed on a proving ground. The fatigure crack location of the torsion beam rear suspension system in the test automobile was coincident with the results by DIC and FEA. If the load conditions of bench tests are close to the road test, DIC is a useful method to predict the fatigue damage by the strain concentration. As a in lab test it would reduce the cost of fatigue analysis.
Synthesis of S-adenosyl-L-methionine in Escherichia coli
Xiao-Nan Wei,Minjie Cao,Jian Li,Huan Li,Yi Song,Cuihong Du 한국생물공학회 2014 Biotechnology and Bioprocess Engineering Vol.19 No.6
S-adenosyl-L-methionine (SAM) is an importantphysiological metabolite in vivo and may be useful inmedicines. SAM is produced from L-methionine and ATPcatalyzed by S-adenosyl-L-methionine synthetase (SAMS)in vivo. In this study, the gene encoding SAMS was clonedand a genetically engineered Escherichia coli (E. coli)BL21(pET-28a-SAMS) was constructed. The recombinantSAMS with a molecular mass of approximately 46 kDawas expressed by inducing the engineered E. coli usingisopropyl-β-D-1-thiogalactopyranoside (IPTG) as an inducer. To produce SAM using a low-cost, nontoxic and highperformanceexpression system, lactose was used as asubstitute for IPTG to induce BL21(pET-28a-SAMS). Byoptimizing the expression conditions, the concentration ofSAM produced by the engineered E. coli was 48 mg/L in theculture medium supernatant. To increase the concentrationof SAM produced, a coupled system was constructedconsisting of E. coli BL21(pET-28a-SAMS) and Saccharomycescerevisiae (S. cerevisiae) JM-310. In this coupled system,ATP generated from S. cerevisiae was provided to E. colifor producing a higher concentration of SAM. The SAMconcentration in the coupled system reached 1.7 g/L. SAMwas purified by a weak acid cationic exchange resin D113,and a simple and economical purification procedure forSAM isolation was achieved. SAM was confirmed byHigh Performance Liquid Chromatography-tandem MassSpectrometry analysis. Our study provides a feasible andconvenient approach to produce SAM.
Effects of biochar and Trichoderma on bacterial community diversity in continuous cropping soil
Xia Cao,Ning Zhang,Xiaoyu Zeng,Qinglin Lan,Nan Ma,Chuncheng Wu 한국원예학회 2022 Horticulture, Environment, and Biotechnology Vol.63 No.1
Soil acidifi cation has become a serious issue in protected production in northern China as a consequence of many years ofcontinuous cropping. Besides aff ecting the growth and quality of vegetables, soil acidifi cation also restricts the sustainabledevelopment of vegetables grown in protected environments. A single application of biochar or Trichoderma can repair thesoil environment, optimize the microbial community structure, reduce plant diseases, and promote plant growth. However,it is not known whether biochar combined with Trichoderma has a synergistic eff ect on these parameters. In this study,long-term continuous cropping of cucumbers in a greenhouse was used to study the eff ect of biochar and Trichoderma onmicro-ecological environmental changes in acidifi ed soil using Illumina sequencing. The results showed that the combinedapplication of biochar and Trichoderma promoted cucumber growth; signifi cantly enhanced root vitality and superoxidedismutase, peroxidase, and catalase activities in leaves; and reduced malondialdehyde content. In addition, soil physicaland chemical properties improved; cation exchange capacity, the activity of soil polyphenol oxidase and invertase, and thediversity of soil bacterial communities increased; and the structure and relative abundance of soil bacteria changed after thecombined application of biochar and Trichoderma . Correlation analysis of environmental factors showed that total nitrogenand soil pH had the greatest impact on bacterial communities. The metabolic function of soil bacteria was improved, andthe circulation of soil nutrients was increased as a consequence of the combined application of biochar and Trichoderma .
Zero-Watermarking Algorithm in Transform Domain Based on RGB Channel and Voting Strategy
( Qiumei Zheng ),( Nan Liu ),( Baoqin Cao ),( Fenghua Wang ),( Yanan Yang ) 한국정보처리학회 2020 Journal of information processing systems Vol.16 No.6
A zero-watermarking algorithm in transform domain based on RGB channel and voting strategy is proposed. The registration and identification of ownership have achieved copyright protection for color images. In the ownership registration, discrete wavelet transform (DWT), discrete cosine transform (DCT), and singular value decomposition (SVD) are used comprehensively because they have the characteristics of multi-resolution, energy concentration and stability, which is conducive to improving the robustness of the proposed algorithm. In order to take full advantage of the characteristics of the image, we use three channels of R, G, and B of a color image to construct three master shares, instead of using data from only one channel. Then, in order to improve security, the master share is superimposed with the copyright watermark encrypted by the owner’s key to generate an ownership share. When the ownership is authenticated, copyright watermarks are extracted from the three channels of the disputed image. Then using voting decisions, the final copyright information is determined by comparing the extracted three watermarks bit by bit. Experimental results show that the proposed zero watermarking scheme is robust to conventional attacks such as JPEG compression, noise addition, filtering and tampering, and has higher stability in various common color images.
Chen, Jing-nan,Yu, Wen-hua,Du, Hang-gen,Jiang, Li,Dong, Xiao-qiao,Cao, Jie The Korean Neurosurgical Society 2018 Journal of Korean neurosurgical society Vol.61 No.6
Objective : To prospectively compare facial pain outcomes for patients having either a repeat microvascular decompression (MVD) or percutaneous balloon compression (PBC) as their surgery for trigeminal neuralgia (TN) recurrence. Methods : Prospective cohort study of 110 patients with TN recurrence who had either redo MVD (n=68) or PBC (n=42) from July 2010 until September 2016. The mean follow-up was 45.6 months. Results : After redo MVD, 65 patients (95.6%) experienced immediate relief of pain. After PBC, 34 patients (81%) were immediately relieved of their neuralgia. After 1 month, the clinical effect of redo MVD was better than PBC (p<0.01). Patients who had redo MVD more commonly were pain free off medications (93.4% at 1 year, 78.2% at 4 years) compared with the PBC patients (85.1% at 1 year, 59.3% at 4 years). However, mean length of stay was longer (p>0.05). Patients after PBC who occurred developed herpes simplex (35.7%), facial numbness (76.2%), and annoying dysesthesia (21.4%) more frequently compared with patients after redo MVD who occurred developed herpes simplex (14.7%), facial numbness (8.8%), and hypoesthesia (5.9%) (p<0.05). The symptoms recurred respectively in 15 patients (22.1%) and 19 patients (45.2%) after redo MVD and PBC within the entire 6-year follow-up period. Conclusion : For the patients with TN recurrence, redo MVD was a more effective procedure than PBC. The cure rate and immediate relief of pain were better, and the incidence of complications was lower.
Hierarchical TiO2–Ag/hydrogel coating used for outstanding antifouling detection of serotonin
Xiaoyan He,Shuo Ma,Nan Sun,Miaomiao Hou,Zheping Tan,Runze Cao 한국고분자학회 2024 Macromolecular Research Vol.32 No.6
Serotonin (5-HT) is an important neurotransmitter in vivo, regulating almost all human behavior and cognitive processes. Antifouling surface that can prevent undesirable adhesion is a key factor in the detection of 5-HT, hydrogels are considered as excellent candidates for non-fouling materials. It still remains a challenge to fabricate antifouling composites on electrode that can combine the properties of the hydrogels and surface morphology characteristics, at the same time, keeping good conductivity of the electrode. Herein, we report a new antifouling electrochemical biosensor for 5-HT detection. Using the photocatalytic activity of TiO2 and the conductivity of Ag nanoparticles, the antifouling layer of P(VPA-SBMA-GMA) hydrogel was formed by in situ polymerization on the surface of hierarchical nanoscale TiO2– Ag nanocomposite, 5-HT aptamers were further bound on the surface of the hydrogel for specific recognition. With these advantages, the constructed sensor had a wide detection range (0.5 pM–100 nM) and a lower detection limit (5 fM) for 5-HT.