Investigation of morphological changes of HPS membrane caused by cecropin B through scanning electron microscopy and atomic force microscopy

Han Hu,Changsheng Jiang,Binzhou Zhan,Nan Guo,Zhonghua Li,Xiaozhen Guo,Yang Wang,Binlei Liu,Qigai He 대한수의학회 2021 Journal of Veterinary Science Vol.22 No.5

Background: Antimicrobial peptides (AMPs) have been identified as promising compounds for consideration as novel antimicrobial agents. Objectives: This study analyzed the efficacy of cecropin B against Haemophilus parasuis isolates through scanning electron microscopy (SEM) and atomic force microscopy (AFM) experiments. Results: Cecropin B exhibited broad inhibition activity against 15 standard Haemophilus parasuis (HPS) strains and 5 of the clinical isolates had minimum inhibition concentrations (MICs) ranging from 2 to 16 μg/mL. Microelectrophoresis and hexadecane adsorption assays indicated that the more hydrophobic and the higher the isoelectric point (IEP) of the strain, the more sensitive it was to cecropin B. Through SEM, multiple blisters of various shapes and dents on the cell surface were observed. Protrusions and leakage were detected by AFM. Conclusions: Based on the results, cecropin B could inhibit HPS via a pore-forming mechanism by interacting with the cytoplasmic membrane of bacteria. Moreover, as cecropin B concentration increased, the bacteria membrane was more seriously damaged. Thus, cecropin B could be developed as an effective anti-HPS agent for use in clinical applications.

Development of a micro-scale Y – Zr – O oxide-dispersion-strengthened steel fabricated via vacuum induction melting and electro-slag remelting

Guoxing Qiu,Dongping Zhan,Changsheng Liu,Min Qi,Zhouhua Jiang,Huishu Zhang 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.6

In this paper, the CLAM steel strengthened by micro-scale YeZreO was prepared by vacuum inductionmelting followed by electroslag remelting (VIM-ESR). Yttrium (Y) and zirconium (Zr) were easy to aggregatesinto massive yttrium-zirconium-rich inclusions in the steel melted by vacuum inductionmelting (VIM), which would interrupt the continuity of the matrix and reduce the mechanical propertiesof steel. Micron-sized YeZreO inclusions would be produced with the removal of original blocky YeZrrichinclusions and the submicron-sized inclusions smaller than 0.2 mm could be retained in the steel. The small grain size and the better refinement and distribution uniformity of YeZreO inclusions afterremelting would be responsible for the better yield strength and toughness. For VIM-ESR alloy, the ultimatetensile strength is 749 MPa and the yield strength is 642 MPa at room temperature, meanwhilethey are 391 MPa and 367 MPa at 600 C, respectively. Meanwhile, the ductile-brittle transition temperature(DBTT) reduced from 43 C (VIM) to-76 C (VIM-ESR).

Synthesis of multi-wall carbon nanotubes by Ni-substituted (loading) MCM-41 mesoporous molecular sieve catalyzed pyrolysis of ethanol

Qian Zhao,Tingshun Jiang,Changsheng Li,Hengbo Yin 한국공업화학회 2011 Journal of Industrial and Engineering Chemistry Vol.17 No.2

Ni-loading MCM-41 mesoporous molecular sieve (Ni/MCM-41) and Ni-substituted MCM-41 mesoporous molecular sieve (Ni-MCM-41) were synthesized by wet impregnation method and hydrothermal method, respectively. Their mesoporous structures were evaluated by X-ray diffraction (XRD) and N2physical adsorption technique. Chemical vapor deposition (CVD) was employed to catalytically synthesize carbon nanotubes (CNTs) using Ni-MCM-41 or Ni/MCM-41 as catalyst via pyrolysis of ethanol at atmospheric pressure and 700 8C. The resulting carbon nanotubes were characterized by means of transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM)and Raman spectroscopy, respectively. The results show that the multi-wall carbon nanotubes (MWCNTs) were successfully obtained at 700 8C utilizing NiMCM-41 (or Ni/MCM-41) as a catalytic template by the pyrolysis of ethanol. MWCNTs obtained over Ni-MCM-41 catalyst have uniform diameter and high quality. On the other hand, the technique has great advantages such as low cost and easy operation for the preparation of carbon nanotubes.

A Method of Network Public Opinion Analysis Based on Quantum Particle Swarm Algorithm Optimization Least Square Vector Machine

Bo Li,BaoXing Bai,Changsheng Zhang,Yixue Jiang 보안공학연구지원센터 2016 International Journal of Database Theory and Appli Vol.9 No.8

Prediction of network public opinion is a complicated prediction featuring poor information, small samples and uncertainty. A prediction model of network public opinion based on grey support vector machine (SVM) is specified to increase prediction accuracy. First, network data are preprocessed by text clustering, hotpot extraction and data aggregation. Then a time series model GM(1,1) is established and SVM is used to modify prediction outcomes of GM(1,1). At last, simulation experiment is conducted to test performance of the model. Simulation results indicate that grey SVM improves the prediction accuracy of network public opinion compared with traditional prediction models. The predictions have certain practical values.

Effects of Y and Ti addition on microstructure stability and tensile properties of reduced activation ferritic/martensitic steel

Guoxing Qiu,Dongping Zhan,Changsheng Liu,Min Qi,Zhouhua Jiang,Huishu Zhang 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.5

The effects of Y and Ti on the microstructure stability and tensile properties of the reduced activationferritic/martensitic steel have been investigated. The addition of Y and Ti affected the prior austenitegrain size due to the pinning of the inclusions. Ti addition of 0.008 wt% to the steel was intended topromote the precipitation of nano-sized carbides with a high resistance to coarsening. 8Ti14Y exhibited ahigher yield strength and a lower DBTT than the other alloys due to the fine grain size and additionalprecipitation hardening by (Ti, Ta)-rich MX. After thermal exposure at 550 C for 1500 h, yield strengthwas dropped significantly in exposed 0Ti13Y. On the contrary, a lower reduction of YS was observed in8Ti14Y. The M23C6 in 0Ti13Y and 8Ti14Y and MX in 25Ti14Y and 39Ti15Y coarsened seriously duringageing, which could be responsible for the reduction of the tensile properties of alloys.

Mechanism of shear deformation, failure and energy dissipation of artificial rock joint in terms of physical and numerical consideration

Xuepeng Zhang,Yujing Jiang,Gang Wang,Jiankang Liu,Dong Wang,Changsheng Wang,Satoshi Sugimoto 한국지질과학협의회 2019 Geosciences Journal Vol.23 No.3

The physical and mechanical change processes of rock are closely related to energy transformation, and its deformation and failure is an instability phenomena driven by energy exchange. This study investigated mechanism of shear deformation, failure and energy dissipation of joint using both physical and numerical direct shear tests under constant normal load (CNL) condition. Three kinds of joint surface were artificially prepared. An acoustic emission system was employed to monitor acoustic emission in physical test, and rupture frequency was recorded in numerical test to represent micro-crack development. By research of numerical micro-crack development accompanied with physical acoustic emission results, mechanism of shear deformation and failure of joints were illustrated schematically. By definition of dissipation energy, captured using the particle flow code (PFC2D), energy releasing and dissipation were discussed with microscopic damage evolution of joints. Results showed that joints under shearing present a dissipation trend of four stages including a slow rise stage, a rapid rise stage, a shock rise stage and a rapid decline stage.

Visualized experimental investigation on the hydraulic characteristics of two-phase flow in a single smooth and single rough rock fractures

Chen Wang,Yujing Jiang,Jiankang Liu,Changsheng Wang,Satoshi Sugimoto 한국지질과학협의회 2021 Geosciences Journal Vol.25 No.3

In present engineering applications, calculations of hydraulic properties in two-phase flow are still highly dependent on empirical or semi-empirical equations obtained from experiments. However, the empirical equations that can reproduce the experiment data on a certain fracture specimen may have errors on other specimens. Researchers have obtained results that show quite different evolution forms of hydraulic characteristics of two-phase flow, which is induced by the variety of the influencing factors in two-phase flow. This paper aims at expanding the experimental results on the hydraulic characteristics of two-phase flow in rock fractures. With a newly developed experiment system, visualized two-phase flow experiments were introduced. The difference in the surface morphology of the fractures leads to totally different flow structures, which indicates the role of capillary pressure differs due to different fracture surfaces. The relative permeability in the rough specimen approximately follows the Corey model, which confirmed that the pressure drop is in this rough fracture is dominated by the capillary pressure, but the relative permeability is not only the function of saturation, but also the function of water flow velocities. However, the relative permeability is not perfect for evaluating the difference of two-phase hydraulic characteristics induced by the fracture surface morphology. On the contrary, the Lockhart-Martinelli model is appropriate for evaluating the difference in the two-phase hydraulic characteristics between the smooth fracture and the rough fracture, which indicates that the two-phase flow turbulence is obviously increased by the fracture roughness.

Effects of electroslag remelting process and Y on the inclusions and mechanical properties of the CLAM steel

Qiu, Guoxing,Zhan, Dongping,Li, Changsheng,Yang, Yongkun,Jiang, Zhouhua,Zhang, Huishu Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.4

Y-containing CLAM steels were melted via vacuum induction melting and electroslag remelting. In this study, the evolution, microstructure, and mechanical properties of the alloy inclusions (ESR-1 (0 wt.% Y), ESR-2 (0.016 wt.% Y) and ESR-3 (0.042 wt.% Y)) were investigated. Further, the number of inclusions in ESRed steel was observed to obviously decrease, and the distributions were more uniform. The fine Y-Al-O inclusions (1-2 ㎛) were the main inclusions in ESR-2. The addition of Y affected the prior austenite grain size (PAGZ), increasing the tensile strength at test temperature. Low ductile-brittle transition temperature (DBTT) was obtained because of the fine PAGZ and dispersive inclusions. For the ESRed CLAM steel with 0.016 wt.% Y, the yield strengths were 621 MPa at 20 ℃ and 354 MPa at 600 ℃ in air. Further, the uniform elongation and elongation of the ESR-2 alloy were 5.5% and 20.1% at 20 ℃, respectively. Meanwhile, the DBTT tested using full-size Charpy impact specimen (55 cm × 10 cm × 10 cm) was reduced to -83 ℃.