Optimum Conditions for Transformation of Synechocystis sp. PCC 6803

Xiaonan Zang,Bin Liu,Shunmei Liu,K.K.I.U. Arunakumara,Xuecheng Zhang 한국미생물학회 2007 The journal of microbiology Vol.45 No.3

This study was conducted to determine the optimal conditions for introduction of exogenous DNA into Synechocystis sp. PCC 6803. Of the three transformation techniques studied, electroporation, ultrasonic transformation and natural transformation, natural transformation showed the highest efficiency. Additionally, this study demonstrated that the higher plasmid concentration and longer homologous recombining fragments resulted in a greater number of transformants. For successful transformation, the lowest concentration of plasmid was 0.02 μg/ml, and the shortest homologous recombining fragment was 0.2 kb. Use of Synechocystis sp. PCC 6803 in the logarithmic growth phase resulted in two-fold higher transformation rate than that of the same organism when cells in the latent phase or the plateau phase were used for transformation. Pretreatment of the host strain, Synechocystis sp. PCC 6803, with EDTA (2 mM) for two days prior to transformation increased the transformation efficiency by 23%. Additionally, incubation of the cells and DNA for 5 h under light conditions increased the transformation efficiency by two orders of magnitude. Moreover, recovery treatment of the cells before they were plated onto antibiotic medium also increased the transformation efficiency.

The Synthesis and Mechanism of (001)-Orientated Hematite Nano Rings: A Combined Theoretical and Experimental Investigation

Xiaonan Liu,Gang He,Jin-shan Li,Guangfu Yin 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.9

In this study, we synthesized Hematite nano rings using hydrothermal treatment. The experimental results demonstrated that the (001)-orientated Hematite nano rings were produced in all of the obtained products. To determine the formation mechanism of the (001) orientation, the lowest three index crystal faces of Hematite, Hematite (001), Hematite (101), and Hematite (104), were investigated with the Cambridge Sequential Total Energy Package (CASTEP) within the Materials Studio software environment (MS5.5) using the density functional theory (DFT). Our theoretical results showed that Hematite (001), the Hematite crystal with the lowest surface energy, had the greatest Hematite nano ring growth. In addition, we present the growth process of the Hematite nano rings based on our experimental and theoretical results.

Study on In-Situ Nucleation, Growth Kinetics and Crystallographic Structure of Acicular Ferrite in X100 Pipeline Steel Welds

Xiaonan Qi,Xiaonan Wang,Xinjun Shen,Pengcheng Huan,Zhenguang Liu,Hongshuang Di 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.9

Acicular ferrite has appeared in various low carbon microalloyed steel welds (e.g., laser-arc hybrid welds) due to its highgrain boundary density and toughness. However, the transformation kinetics and crystallographic structure characteristics ofacicular ferrite in laser-arc hybrid welds are still unclear. In this paper, the nucleation and growth kinetics of acicular ferritein laser-metal active gas hybrid welds with different cooling rates (1–150 K/s) were investigated and their crystallographiccharacteristics were revealed from the perspective of variant. The result showed that acicular ferrite can nucleate at all thetest cooling rates in weld metal, and the microstructure coexisting with acicular ferrite changes from polygonal ferrite andgranular bainite with a low cooling rate to lath martensite with a high cooling rate. As the cooling rate increases, the phasetransformation temperature of acicular ferrite decreased, and the phase transformation mode changed from partitioninglocal equilibrium to negligible partitioning local equilibrium. The variety of the phase transformation mode and the higherphase transformation driving force led to an increase in the growth rate of acicular ferrite. Compared with the bainite andmartensite in the base metal, the acicular ferrite had the characteristics of light variant selection, uniformly distributedoperating factor and small variant size, which resulted in high-density effective grain boundaries. To obtain more acicularferrite, the cooling rate should be increased as much as possible on the premise that the phase transformation terminationtemperature was higher than the Ms.

Optimum Conditions for Transformation of Synechocystis sp. PCC 6803

Zang, Xiaonan,Liu, Bin,Liu, Shunmei,Arunakumara, K.K.I.U.,Zhang, Xuecheng The Microbiological Society of Korea 2007 The journal of microbiology Vol.45 No.3

This study was conducted to determine the optimal conditions for introduction of exogenous DNA into Synechocystis sp. PCC 6803. Of the three transformation techniques studied, electroporation, ultrasonic transformation and natural transformation, natural transformation showed the highest efficiency. Additionally, this study demonstrated that the higher plasmid concentration and longer homologous recombining fragments resulted in a greater number of transformants. For successful transformation, the lowest concentration of plasmid was $0.02\;{\mu}g/ml$, and the shortest homologous recombining fragment was 0.2 kb. Use of Synechocystis sp. PCC 6803 in the logarithmic growth phase resulted in two-fold higher transformation rate than that of the same organism when cells in the latent phase or the plateau phase were used for transformation. Pretreatment of the host strain, Synechocystis sp. PCC 6803, with EDTA (2 mM) for two days prior to transformation increased the transformation efficiency by 23%. Additionally, incubation of the cells and DNA for 5 h under light conditions increased the transformation efficiency by two orders of magnitude. Moreover, recovery treatment of the cells before they were plated onto antibiotic medium also increased the transformation efficiency.

Cross-architecture Binary Function Similarity Detection based on Composite Feature Model

( Xiaonan Li ),( Guimin Zhang ),( Qingbao Li ),( Ping Zhang ),( Zhifeng Chen ),( Jinjin Liu ),( Shudan Yue ) 한국인터넷정보학회 2023 KSII Transactions on Internet and Information Syst Vol.17 No.8

Recent studies have shown that the neural network-based binary code similarity detection technology performs well in vulnerability mining, plagiarism detection, and malicious code analysis. However, existing cross-architecture methods still suffer from insufficient feature characterization and low discrimination accuracy. To address these issues, this paper proposes a cross-architecture binary function similarity detection method based on composite feature model (SDCFM). Firstly, the binary function is converted into vector representation according to the proposed composite feature model, which is composed of instruction statistical features, control flow graph structural features, and application program interface calling behavioral features. Then, the composite features are embedded by the proposed hierarchical embedding network based on a graph neural network. In which, the block-level features and the function-level features are processed separately and finally fused into the embedding. In addition, to make the trained model more accurate and stable, our method utilizes the embeddings of predecessor nodes to modify the node embedding in the iterative updating process of the graph neural network. To assess the effectiveness of composite feature model, we contrast SDCFM with the state of art method on benchmark datasets. The experimental results show that SDCFM has good performance both on the area under the curve in the binary function similarity detection task and the vulnerable candidate function ranking in vulnerability search task.

Transparent Lamellar Porous Material and Its Greatly Reduced Dielectric Constant

Lili Liu,Cuijiao Zhao,Yawen Huang,Xiaonan Wei,Hongtao Yu,Junxiao Yang 한국고분자학회 2017 Macromolecular Research Vol.25 No.10

One trend for low dielectric materials is to reach low dielectric constant values at as low porosity as possible. In this work, a lamellar porous material was prepared by spin-coating of poly(vinyl alcohol) (PVA)/manganese dioxide (MnO2) nanosheet composited film, followed by cross-linking of PVA and removing nanosheets. FTIR, XRD and TGA measurement results demonstrate that the templates were almost completely removed. SEM image shows that the etched PVA film has a lamellar porous structure. Dielectric test results indicate that at the porosity of only 17.5%, the dielectric constant of porous PVA is reduced to approximately half that of neat cross-linked PVA. The serial model shows a good consistence with experimental dielectric constant value. This explains well the high efficiency of lamellar porous structure in reducing dielectric constant.

Four-port Hydraulic Transformer with Inlet and Outlet Equal Flow and Its Efficiency Characteristics

Qiang Liu,Lianquan Zhou,Xiaonan Bo,Chu Zhang 한국유체기계학회 2020 International journal of fluid machinery and syste Vol.13 No.2

In order to avoid throttling loss and recover differential pressure energy, braking energy and gravitational potential energy without changing the original hydraulic system, the four-port hydraulic transformer (FHT) is proposed. Its theoretical and experimental efficiency characteristics are researched. The basic structure and principle of the FHT are explained. Besides, the mathematical model of its efficiency is established. The results show that the pressure ratio can be changed by adjusting the control angle of valve plate, and the efficiency characteristics of the FHT match the efficiency characteristics of the hydraulic pump/motor. The total efficiency increases first and decreases afterwards with the increment of cylinder speed, and increases with the control angle of valve plate, while decreases with the recycling pressure difference.

Wind Power Short Term Forecasting based on Back Propagation Neural Network

Shenghui Wang,Xiaonan Liu,Yuexin Jin,Keding Qu 보안공학연구지원센터 2015 International Journal of Smart Home Vol.9 No.7

This paper analyze and summarize the current situation as well as methods of forecasting wind power from home and aboard based on wind power development of China. Due to the BP neural network can approximate any nonlinear mapping with any arbitrary precision and its generalization ability is strong. This paper used BP neural network for power prediction, set up a model with numerical weather prediction data and wind power of a wind farm in Inner Mongolia Autonomous Region. Then used MATLAB to simulate and verify the feasibility of this prediction model the precision meet the requirements. In the last of this paper, the author development and design a simple system of wind power forecasting by using visual basic. The system has made the forecasting process to be simple and convenient, and also made easy to operation for the dispatcher.

A Method of Finding Hidden Key Users Based on Transfer Entropy in Microblog Network

( Meijuan Yin ),( Xiaonan Liu ),( Gongzhen He ),( Jing Chen ),( Ziqi Tang ),( Bo Zhao ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.8

Finding key users in microblog has been a research hotspot in recent years. There are two kinds of key users: obvious and hidden ones. Influence of the former is direct while that of the latter is indirect. Most of existing methods evaluate user's direct influence, so key users they can find usually obvious ones, and their ability to identify hidden key users is very low as hidden ones exert influence in a very covert way. Consequently, the algorithm of finding hidden key users based on topic transfer entropy, called TTE, is proposed. TTE algorithm believes that hidden key users are those normal users possessing a high covert influence on obvious ones. Firstly, obvious key users are discovered based on microblog propagation scale. Then, based on microblogs' topic similarity and time correlation, the transfer entropy from ordinary users' blogs to obvious key users is calculated and used to measure the covert influence. Finally, hidden influence degrees of ordinary users are comprehensively evaluated by combining above indicators with the influence of both ordinary users and obvious ones. We conducted experiments on Sina Weibo, and the results showed that TTE algorithm had a good ability to identify hidden key users.

Novel Method for Circulating Current Suppression in MMCs Based on Multiple Quasi-PR Controller

Qiu, Jian,Hang, Lijun,Liu, Dongliang,Geng, Shengbao,Ma, Xiaonan,Li, Zhen The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6

An improved circulating current suppression control method is proposed in this paper. In the proposed controller, an outer loop of the average capacitor voltage control model is used to balance the sub-module capacitor voltage. Meanwhile, an individual voltage balance controller and an arm voltage balance controller are also used. The DC and harmonic components of the circulating current are separated using a low pass filter. Therefore, a multiple quasi-proportional-resonant (multi-quasi-PR) controller is introduced in the inner loop to eliminate the circulating harmonic current, which mainly contains second-order harmonic but also contains other high-order harmonics. In addition, the parameters of the multi-quasi-PR controller are designed in the discrete domain and an analysis of the stability characteristic is given in this paper. In addition, a simulation model of a three-phase MMC system is built in order to confirm the correctness and superiority of the proposed controller. Finally, experiment results are presented and compared. These results illustrate that the improved control method has good performance in suppressing circulating harmonic current and in balancing the capacitor voltage.