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Two selenium tolerant Lysinibacillus sp. strains are capable of reducing selenite to elemental Se efficiently under aerobic conditions

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Journal of Environmental Sciences 2019年第3期31卷 238-249页

作者： Ju Zhang Yue Wang Zongyuan Shao Jing Li Shuting Zan Shoubiao Zhou Ruyi Yang College of Environmental Science and Engineering Anhui Normal University Anhui Provincial Engineering Laboratory of Water and Soil Pollution Control and Remediation Anhui Normal University Institute of Functional Food Anhui Normal University

Microbes play important roles in the transport and transformation of selenium(Se) in the environment, thereby influencing plant resistance to Se and Se accumulation in plant. The objectives are to characterize the bacteria with high Se tolerance and reduction capacity and explore the significance of microbial origins on their Se tolerance, reduction rate and efficiency. Two bacterial strains were isolated from a naturally occurred Se-rich soil at tea orchard in southern Anhui Province, China. The reduction kinetics of selenite was investigated and the reducing product was characterized using scanning electron microscopy and transmission electron microscopy-energy dispersive spectroscopy. The bacteria were identified as Lysinibacillus xylanilyticus and Lysinibacillus macrolides,respectively, using morphological, physiological and molecular methods. The results showed that the minimal inhibitory concentrations(MICs) of selenite for L. xylanilyticus and L. macrolides were 120 and 220 mmol/L, respectively, while MICs of selenate for L.xylanilyticus and L. macrolides were 800 and 700 mmol/L, respectively. Both strains aerobically reduced selenite with an initial concentration of 1.0 mmol/L to elemental Se nanoparticles(SeNPs) completely within 36 hr. Biogenic SeNPs were observed both inside and outside the cells suggesting either an intra-or extracellular reduction process. Our study implied that the microbes from Se-rich environments were more tolerant to Se and generally quicker and more efficient than those from Se-free habitats in the reduction of Se oxyanions. The bacterial strains with high Se reduction capacity and the biological synthesized Se NPs would have potential applications in agriculture, food, environment and medicine.

关键词： Selenium tolerant bacteria Selenite reduction Nanoparticles Reduction rate Reduction efficiency Sources

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An Efficient Message Dissemination Scheme for Minimizing DeliveryDelay in Delay tolerant Networks

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Journal of Computer Science & Technology 2018年第6期33卷 1101-1124页

作者： En Wang Wei-Shih Yang Yong-Jian Yang Jie Wu Wen-Bin Liu Department of Computer Science and Technology Jilin University Changchun 130012 China Department of Mathematics Temple University Philadelphia PA 19122 U.S.A. Department of Computer and Information Science Temple University Philadelphia PA 19122 U.S.A.

Delay tolerant networks （DTNs） are a kind of sparse and highly mobile wireless networks, where no stableconnectivity guarantee can be assumed. Most DTN users have several points of interest （PoIs）, and they enjoy disseminatingmessages to the other users of the same PoI through WiFi. In DTNs, some time-sensitive messages （disaster warnings, searchnotices, etc.） need to be rapidly propagated among specific users or areas. Therefore, finding a path from the source tothe destination with the shortest delay is the key problem. Taking the dissemination cost into consideration, we proposean efficient message dissemination strategy for minimizing delivery delay （MDMD） in DTNs, which first defines the user＇sactiveness according to the transiting habit among different PoIs. Furthermore, depending on the activeness, an optimaluser in each PoI is selected to constitute the path with the shortest delay. Finally, the MDMD with inactive state （on theway between PoIs） is further proposed to enhance the applicability. Simulation results show that, compared with otherdissemination strategies, MDMD achieves the lowest average delay, and the comparable average hopcounts, on the premisethat the delivery ratio is guaranteed to be 100% by the sufficient simulation time.

关键词： delay tolerant network (DTN) point of interest (PoI) dissemination strategy minimizing delay

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A Fault tolerant Control Scheme Using the Feasible Constrained Control Allocation Strategy

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International Journal of Automation and computing 2019年第5期16卷 628-643页

作者： Mehdi Naderi Tor Arne Johansen Ali Khaki Sedigh Center of Excellence in Industrial Control Faculty of Electrical EngineeringK.N.Toosi University of TechnologySeyyed Khandan BridgeShariati AvenueTehran ***Iran Center for Autonomous Marine Operation and Systems Department of Engineering CyberneticsNorwegian University of Science and TechnologyTrondheim 7491Norway

This paper investigates the necessity of feasibility considerations in a fault tolerant control system using the constrained control allocation methodology where both static and dynamic actuator constraints are considered. In the proposed feasible control allocation scheme, the constrained model predictive control(MPC) is employed as the main controller. This considers the admissible region of the control allocation problem as its constraints. Using the feasibility notion in the control allocation problem provides the main controller with information regarding the actuator′s status, which leads to closed loop system performance improvement. Several simulation examples under normal and faulty conditions are employed to illustrate the effectiveness of the proposed methodology. The main results clearly indicate that closed loop performance and stability characteristics can be significantly degraded by neglecting the actuator constraints in the main controller. Also, it is shown that the proposed strategy substantially enlarges the domain of attraction of the MPC combined with the control allocation as compared to the conventional MPC.

关键词： Control allocation feasibility fault tolerant control model predictive control domain of attraction

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Y_5Si_3C and Y_3Si_2C_2: Theoretically predicted MAX phase like damage tolerant ceramics and promising interphase materials for SiC_f/SiC composites

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Journal of Materials Science & Technology 2019年第3期35卷 313-322页

作者： Yanchun Zhou Huimin Xiang Fu-Zhi Dai Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials & Processing Technology

Researching for interphase materials that can protect SiC fibers from oxygen and water vapor attacks has become one of the most important issues for the applications of SiC_f/SiC composites in high-temperature combustion environment. However, such kinds of interphase materials are not available yet. Herein,we report theoretically predicted properties of two promising interphase materials Y_5Si_3 C and Y_3Si_2C_2.Although crystallizing in different structures, they share the common features of layered structure,anisotropic chemical bonding, anisotropic electrical and mechanical properties, and low shear deformation resistance. The bulk moduli for Y_5Si_3C and Y_3Si_2C_2 are 78 and 93 GPa, respectively; while their shear moduli are 52 and 50GPa, respectively. The maximum to minimum Young's modulus ratios are1.44 for Y_5Si_3C and 3.27 for Y_3Si_2C_2. Based on the low shear deformation resistance and low Pugh's ratios(G/B = 0.666 forY_5Si_3C and 0.537 for Y_3Si_2C_2; G: shear modulus; B: bulk modulus), they are predicted as damage tolerant and soft ceramics with predicted Vickers hardness of 9.6 and 6.9 GPa, respectively.The cleavage plane and possible slip systems are(000 l) and(0001)[1120] and(1010)[0001] forY_5Si_3C,and those for Y_3Si_2C_2 are {h00} and(010)[101]. Since the oxidation products are water-vapor resistant Y2 Si2 O7, Y2 SiO5 and/or Y_2 O_3 upon oxidation, and the volume expansions are ca 140% and ca 26% for Y_5Si_3C and Y_3Si_2C_2, they are expected to seal the interfacial cracks in SiC_f/SiC composites. The unique combination of easy cleavage, low shear deformation resistance, volume expansions upon oxidation, and the resistance of the oxidation products to water vapor attack warrant them promising as interphase materials of SiC_f/SiC composites for water-vapor laden environment applications.

关键词： Y5Si3C Y3Si2C2 Interphase material Damage tolerant ceramics Electronic structure

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Cooperative transmission in delay tolerant network

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Journal of Systems Engineering and Electronics 2019年第1期30卷 30-36页

作者： WANG Rong WU Yahui HUANG Hongbin DENG Su Science and Technology on Information Systems Engineering Laboratory National University of Defense Technology

The delay tolerant network(DTN) is an emerging concept, which is used to describe the network, where the communication link may disrupt frequently. To cope with this problem, the DTN uses the store-carry-forward(SCF) transmission mode. With this policy, the messages in the DTN are transmitted based on the nodes' cooperation. However, the nodes may be selfish, so the source has to pay certain rewards for others to get their help. This paper studies the optimal incentive policy to maximize the source's final utility. First, it models the message spreading process as several ordinary differential equations(ODEs) based on the meanfield approximation. Then, it mathematically gets the optimal policy and explores the structure of the policy. Finally, it checks the accuracy of the ODEs model and shows the advantages of the optimal policy through simulation and theoretical results respectively.

关键词： delay tolerant network (DTN) optimal control message transmission.

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A cold adapt and ethanol tolerant endoglucanase from a marine Bacillus subtilis

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Chinese Journal of Chemical Engineering 2018年第12期26卷 2601-2606页

作者： Dongsheng Xue Xuhao Zeng Chunjie Gong Dongqiang Lin Shanjing Yao Key Laboratory of Fermentation Engineering (Ministry of Education) Hubei Provincial Cooperative Innovation Center of Industrial Fermentation Hubei Key Laboratory of Industrial MicrobiologyHubei University of Technology Department of Chemical and Bioengineering Zhejiang University

The catalytic properties and thermodynamic kinetics of the endoglucanase from a marine Bacillus subtilis were analyzed. Optimum pH and temperature of the endoglucanase activity were 5.0 and 35 °C. The endoglucanase activity, melt point temperature was 1.13 folds(247.02 U·ml^(-1)), 2.1 °C higher(39.2 °C) in 6% ethanol solution than that(218.60 U·ml^(-1)),(37.1 °C) in free ethanol. At 40 °C–55 °C, Gibbs free energy, ΔG, and the content ofα-helix was higher in 6% ethanol solution than that in ethanol free solution. The increasing of α-helix content led to higher activity and better thermostability in ethanol solution. The cold adapt ethanol tolerant endoglucanase was valuable for bioethanol product by simultaneous saccharification and fermentation process.

关键词： Endoglucanase Ethanol tolerant Cold adapt Bioethanol

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Thermostable ethanol tolerant xylanase from a cold-adapted marine species Acinetobacter johnsonii

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Chinese Journal of Chemical Engineering 2019年第5期27卷 1166-1170页

作者： Dongsheng Xue Xuhao Zeng Dongqiang Lin Shanjing Yao Key Laboratory of Fermentation Engineering (Hubei Universty of Technology) Ministry of EducationHubei Provincial Cooperative Innovation Center of Industrial FermentationHubei Key Laboratory of Industrial MicrobiologyHubei University of TechnologyWuhan 430068China Department of Chemical and Bioengineering Zhejiang UniversityHangzhou 310027 China

A xylanase-producing bacterium, isolated from deep sea sediments, was identified as the cold-adapted marine species Acinetobacter Johnsonii. A cold-adapted marine species Acinetobacter Johnsonii could grow at 4 ℃. The optimum temperature and pH of xylanase from a cold-adapted marine species Acinetobacter Johnsonii were 55 ℃ and pH 6.0. Xylanase from a cold-adapted marine species Acinetobacter Johnsonii remained at 80% activity after incubation for 1 h at 65 ℃. The xylanase activity was 1.2-fold higher in 4% ethanol solution than in ethanol free solution. Gibbs free energy of denaturation, ΔG, was higher in 4% ethanol solution than in ethanol free solution. Thermostable ethanol tolerant xylanase was valuable for bioethanol production by simultaneous saccharification and fermentation process with xylan as a carbon source.

关键词： Xylanase Ethanol tolerant Thermostable Cold-adapted Acinetobacter Johnsonii

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Sliding Mode Fault tolerant Attitude Control Scheme for Spacecraft with Actuator Faults

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Transactions of Nanjing University of Aeronautics and Astronautics 2019年第1期36卷 119-127页

作者： CAO Teng GONG Huajun HAN Bing College of Automation Engineering Nanjing University of Aeronautics and Astronautics

An active fault tolerant control scheme is investigated for the attitude control systems of spacecraft with external disturbance and actuator faults by using the sliding mode technique. Firstly,the dynamic equations and kinematic equations of spacecraft are given. For the dynamic mode of spacecraft in faulty case,a fault diagnosis component is used for fault detection and estimation by using a nonlinear observer. According to the fault estimation information obtained during the fault diagnosis,the fault tolerant control scheme is developed by adopting the backstepping sliding mode control technique. Meanwhile,the Lyapunov theory is used to analyze the stability of the closed-loop attitude systems. Finally,simulation results for the attitude dynamics models show the feasibility of the proposed fault tolerant scheme.

关键词： fault tolerant control fault estimation actuator faults sliding mode control

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Remote sensing data classification using tolerant rough set and neural networks

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Science China Earth Sciences 2005年第12期48卷 2251-2259页

作者： MA Jianwen HASI Bagan State Key Laboratory of Remote Sensing Science Institute of Remote Sensing Applications Chinese Academy of Sciences Beijing 100101 China State Key Laboratory of Remote Sensing Science Institute of Remote Sensing Applications Chinese Academy of Sciences Beijing 100101 China

BP algorithm of neural net is used more in remote sensing data classification. One of drawbacks of BP algorithm is the overall low function when the net is training. To avoid this kind of problem, the paper introduces the tolerant rough set for classification-preprocessing the training data to reduce the influence elements of the training convergence in order to improve the net training successful rate. ETM+ data of Beijing in May 2003 is selected in the study. ETM+ data before and after classification preprocessing, respectively, are used for BP (Back propaga-tion) training. The result shows that such a preprocessing not only compensates the drawback of BP algorithm when processing ETM+ data but also improves classification accuracy.

关键词： tolerant rough set, neural network, BP algorithm, classification.

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RAPD tagging of a salt tolerant gene in rice

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Chinese Science Bulletin 1998年第4期43卷 330-332页

作者： Ding Haiyuan Zhang Gengyun Guo Yan Chen Shaolin Chen Shouyi Chinese Acad Sci Inst Genet Plant Biotechnol Lab Beijing 100101 Peoples R China

A salt tolerant rice mutant was obtained through tissue culture. The inheritance of salt tolerance in F2 population of mutant crossed with its original variety under salt stress was studied. According to the standard, the ratio of salt tolerant: sensitive was about 3:1 suggesting that there was a major gene related to salt tolerance in the mutant. By RAPD analysis with 220 10mer primers, the gene was tagged by a 1.0 kb DNA fragment named OPS1210 which was located on chromosome 7. The genetic distance between the major salt tolerant gene was 16.4 cm.

关键词： rice salt tolerant mutant line RAPD molecular marker.

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