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Keratinase production and keratin degradation by a mutant strain of Bacillus subtilis

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2008年第1期9卷 60-67页

作者： cheng-gang cai Bing-gan LOU Xiao-dong ZHENG College of Food Science and Biosystem Engineering Zhejiang University Hangzhou 310029 China Institute of Biotechnology Zhejiang University Hangzhou 310029 China

A new feather-degrading bacterium was isolated from a local feather waste site and identified as Bacillus subtilis based on morphological, physiochemical, and phylogenetic characteristics. Screening for mutants with elevated keratinolytic activity using N-methyl-N＇-nitro-N-nitrosoguanidine mutagenesis resulted in a mutant strain KD-N2 producing keratinolytic activity about 2.5 times that of the wild-type strain. The mutant strain produced inducible keratinase in different substrates of feathers, hair, wool and silk under submerged cultivation. Scanning electron microscopy studies showed the degradation of feathers, hair and silk by the keratinase. The optimal conditions for keratinase production include initial pH of 7.5, inoculum size of 2% （v/v）, age of inoculum of 16 h, and cultivation at 23 ℃. The maximum keratinolytic activity of KD-N2 was achieved after 30 h. Essential amino acids like threonine, valine, methionine as well as ammonia were produced when feathers were used as substrates. Strain KD-N2, therefore, shows great promise of finding potential applications in keratin hydrolysis and keratinase production.

关键词： Bacillus subtilis Keratin Keratin degradation Keratinase production N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) mutagenesis

A frequency and amplitude dependent model of rail pads for the dynamic analysis of train-track interaction

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Science China(Technological Sciences) 2015年第2期58卷 191-201页

作者： ZHU Sheng Yang cai cheng Biao LUO Zhen LIAO Zhong Qi State Key Laboratory of Traction Power Southwest Jiaotong University China Railway Construction Heavy Industry Co. Ltd. China Railway Longchang Materials Co. Ltd.

A frequency and amplitude dependent model is used to describe the complex behavior of rail pads. It is implemented into the dynamic analysis of three dimensional coupled vehicle-slab track （3D-CVST） systems. The vehicle is treated as a 35-degree- of-freedom multi-body system, and the slab track is represented by two continuous Bernoulli-Euler beams supported by a se- ries of elastic rectangle plates on a viscoelastic foundation. The rail pad model takes into account the influences of the excita- tion frequency and of the displacement amplitude through a fractional derivative element, and a nonlinear friction element, re- spectively. The Granwald representation of the fractional derivatives is employed to numerically solve the fractional and non- linear equations of motion of the 3D-CVST system by means of an explicit integration algorithm. A dynamic analysis of the 3D-CVST system exposed to excitations of rail harmonic irregularities is primarily carried out, which reveals the dependence of stiffness and damping on excitation frequency and displacement amplitude. Subsequently, sensitive analyses of the model parameters are investigated by conducting the dynamic analysis of the 3D-CVST system subjected to excitations of welded rail joint irregularities. Following this, parameters of the rail pad model are optimized with respect to experimental values. For elu- cidation, the 3D-CVST dynamic model incorporated with the rail pads model is used to calculate the wheel/rail forces induced by excitations of measured random track irregularities. Further, the numerical results are compared with experimental data, demonstrating the reliability of the proposed model.

关键词： rail pads vehicle-track coupled dynamics frequency dependent amplitude dependent

Safety threshold of high-speed railway pier settlement based on train-track-bridge dynamic interaction

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Science China(Technological Sciences) 2015年第2期58卷 202-210页

作者： CHEN Zhao Wei ZHAI Wan Ming cai cheng Biao SUN Yu State Key Laboratory of Traction Power Southwest Jiaotong University

This paper presents a method to determine the safety threshold of bridge pier settlement in high-speed *** analytical expression of the mapping relationship between the pier settlement and the rail deformation is derived theoretically for the double block ballastless track-bridge *** adopting the superposition of the track random irregularity and the rail deformation caused by the pier settlement as the excitation inputs,the variations of vehicle dynamics indices with pier settlement are comparatively ***,the safety threshold of the bridge pier settlement is obtained according to the limit of vehicle running safety and ride comfort indices of the high-speed *** show that the dynamics indices of different trains have different sensitivities to the pier settlement,and the train CRH2C is the most sensitive one among all the types of Chinese high-speed *** passing through the bridges in common span with pier settlement at the speed of 250–350 km/h,the trains suffer the low-frequency excitations,and the vertical acceleration of car body is most sensitive to the pier settlement of all the dynamics *** the car body vertical acceleration just exceeds the allowable limit,the critical settlement value is 23.4 mm,which is much bigger than the pier differential settlement limit in the current code for Chinese high-speed railways.

关键词： high-speed railway pier settlement safety threshold dynamic characteristics train-track-bridge dynamic interaction

Efficacy and cost-effectiveness of antiviral regimens for entecavir-resistant hepatitis B:A systematic review and network meta-analysis

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Hepatobiliary & Pancreatic Diseases International 2020年第6期19卷 507-514页

作者： Si-Si Yang cheng-Wei cai Xue-Qing Ma Jia Xu cheng-Bo Yu State Key Laboratory for Diagnosis and Treatment of Infectious Diseases National Clinical Research Center for Infectious DiseasesCollaborative Innovation Center for Diagnosis and Treatment of Infectious Diseasesthe First Affiliated HospitalZhejiang University School of MedicineHangzhou 310003China Department of Neurosurgery Second Affiliated HospitalZhejiang University School of MedicineHangzhou 310003China Kidney Disease Center the First Affiliated HospitalZhejiang University School of MedicineHangzhou 310003China

Background:Chronic hepatitis B(CHB)patients who had exposed to lamivudine(LAM)and telbivudine(LdT)had high risk of developing entecavir(ETV)-resistance after long-term *** aimed to conduct a systematic review and a network meta-analysis on the efficacy and cost-effectiveness on antiviral regimens in CHB patients with *** sources:We searched PubMed,EMBASE and Web of Science for studies on nucleos(t)ide analogues(NAs)treatment[including tenofovir disoproxil fumarate(TDF)-based rescue therapies,adefovir(ADV)-based rescue therapies and double-dose ETV therapy]in CHB patients with *** network meta-analysis was conducted for 1-year complete virological response(CVR)and biological response(BR)rates using GeMTC and ADDIS.A cost-effective analysis was conducted to select an economic and effective treatment regimen based on the 1-year CVR ***:A total of 6 studies were finally included in this *** antiviral efficacy was *** network meta-analysis,the 1-year CVR rate in ETV-TDF[odds ratio(OR)=22.30;95%confidence interval(CI):2.78-241.93],LAM-TDF(OR=70.67;95%CI:5.16-1307.45)and TDF(OR=16.90;95%CI:2.28-186.30)groups were significantly higher than that in the ETV double-dose group;the 1-year CVR rate in the LAM-TDF group(OR=14.82;95%CI:1.03-220.31)was significantly higher than that in the LAM/LdTADV *** 1-year BR rate of ETV-TDF(OR=28.68;95%CI:1.70-1505.08)and TDF(OR=21.79;95%CI:1.43-1070.09)therapies were significantly higher than that of ETV double-dose *** therapies had the highest possibility to achieve the CVR and BR at 1 year,in which LAM-TDF combined therapy was the most effective *** ratio of cost/effectiveness for 1-year treatment was 8526,17649,20651 Yuan in the TDF group,TDF-ETV group,and ETV-ADV group,***:TDF-based combined therapies such as ETV-TDF and LAM-TDF therapies were the first-line treatment if financial condition is allowed.

关键词： Chronic hepatitis B Drug resistance Entecavir Anitviral therapy

Dynamics of luffing motion of a hydraulically driven shell manipulator with revolute clearance joints

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Defence Technology（防务技术） 2022年第4期18卷 689-708页

作者： Chen Zhi-qun Qian Lin-fang Chen Guang-song Nie Shou-cheng Yin Qiang Yue cai-cheng School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing210094China Northwest Institute of Mechanical and Electrical Engineering Xianyang712099ShaanxiChina China North Industry Corporation Beijing100053China

In this study,a modeling method for investigating the dynamic characteristics of a hydraulically driven shell manipulator with revolute clearance joints is *** model accounts for the effect of the clearance,the flexibility of the rotating beam,and the coupled dynamic characteristics of the hydraulic cylinder.A modified contact force model was developed to simulate the physical properties of realistic revolute joints with small clearances,heavy loads,and variable contact stiffnesses and damping coefficients with variations of the *** the strong coupling relationship between the hydraulic cylinder and the flexible beam,a system equation of motion combining the state variables of the hydraulic cylinder and mechanical system was *** complex nonlinear friction force of the hydraulic cylinder motion was constructed using a modified Lu Gre model,and the parameters of the friction model were identified using intelligent identification ***,a test system for the shell manipulator was established to achieve experimental ***,the effects of the clearance size and the stiffness of the cylinder support on the dynamic response were investigated.

关键词： Parameter identification Shell manipulator Hydraulic cylinder Revolute clearance joint

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Chinese Physics Letters 2018年第6期35卷 41-44页

作者： Hong-Mei Zhang cheng cai Xiu-Jun Fu School of Physics and Optoelectronics South China University of Technology

Based on the matching rules for squares and rhombuses,we study the self-similar transformation and the vertex configurations of the Ammann-Beenker *** structural properties of the configurations and their relations during the self-similar transformation are *** results reveal the distribution correlations of the configurations,which provide an intuitive understanding of the octagonal quasi-periodic structure and also give implications for growing perfect quasi-periodic tiling according to the local rules.

关键词： Self-Similar Transformation and Vertex Configurations of the Octagonal Ammann-Beenker Tiling

Decagonal and Dodecagonal Quasicrystals Obtained by Molecular Dynamics Simulations

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Chinese Physics Letters 2019年第3期36卷 61-64页

作者： Jian-Hui Chen cheng cai Xiu-Jun Fu School of Physics and Optoelectronics South China University of Technology

Double-well potentials are used for molecular dynamics simulation in monatomic systems. The potentials change as their parameters are adjusted, resulting in different structures. Of particular interest, we obtain decagonal and dodecagonal quasicrystals by simulations. We also verify the results and explain the formation of quasicrystals from the perspective of potential energy.

关键词： Decagonal Dodecagonal Quasicrystals Molecular

Effect of pre-recovery on microstructure and properties of rolled Al-12.18Zn-3.31Mg-1.43Cu-0.20Zr-0.04Sr aluminum alloy

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International Journal of Minerals,Metallurgy and Materials 2019年第2期26卷 241-250页

作者： cheng-bin cai Xiao-jing Xu Jin-dong Huang Shi-hao Ju Qing Ding cheng-song Wang Engineering Institute of Advanced Manufacturing and Modern Equipment Technology Jiangsu University

The independently designed and manufactured ultra-high-strength aluminum alloy Al-12.18 Zn-3.31 Mg-1.43 Cu-0.20 Zr-0.04 Sr was investigated via scanning electron microscopy observations, X-ray diffraction analysis, hardness tests, electrical conductivity tests, tensile tests, intergranular corrosion tests, and exfoliation corrosion tests. The effect of pre-recovery on the microstructure and mechanical properties of this aluminum alloy was also studied. The results show that the pre-recovery heat treatment releases deformation energy, inhibits recrystallization, and decreases the dislocation density. Although the pre-recovery heat treatment has little effect on the hardness, electrical conductivity, and elongation of this aluminum alloy, it can dramatically improve the alloy's tensile strength(the maximum tensile strength increased from 785.0 MPa to 809.2 MPa). Moreover, the tensile properties of this aluminum alloy have a certain degree of isotropy, and the pre-recovery heat treatment does not affect this property. In addition, the rolled aluminum alloy exhibits good corrosion resistance, but the effect of the pre-recovery heat treatment on the alloy's resistance to intergranular and exfoliation corrosion is negligible.

关键词： ultra-high strength aluminum alloy pre-recovery microstructure mechanical property corrosion resistance

Natural Variation of Pto and Fen Genes and Marker-Assisted Selection for Resistance to Bacterial Speck in Tomato

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Agricultural Sciences in China 2011年第6期10卷 827-837页

作者： SUN Wan-yu ZHAO Wan-ying WANG Yuan-yuan PEI cheng-cheng YANG Wen-cai Department of Vegetable Science College of Agronomy and Biotechnology China Agricultural University Beijing 100193 P.R.China

The resistance in tomato plants to bacterial speck caused by Pseudomonas syringae pv. tomato is triggered by the interactions between the plant resistance protein Pto and the pathogen avirulence proteins AvrPto or AvrPtoB. Fen is a gene encoding closely related functional protein kinases as the Pto gene. To investigate the status of resistance to the pathogen and natural variation of Pto and Fen genes in tomato, 67 lines including 29 growing in China were subject to disease resistance evaluation and fenthion-sensitivity test. Alleles of Pto and Fen were amplified from genomic DNA of 25 tomato lines using polymerase chain reaction （PCR） and sequences were determined by sequencing the PCR products. The results indicated that none of the 29 cultivars/hybrids growing in China were resistant to bacterial speck race 0 strain DC3000. Seven of eight tomato lines resistant to DC3000 were also fenthion-sensitive. Analysis of deduced amino acid sequences identified three novel residue substitutions between Pto and pto, and one new substitution identified between Fen and fen. A PCR-based marker was developed and successfully used to select plants with resistance to DC3000.

关键词： tomato bacterial speck Pto Fen natural variation marker-assisted selection