Table of Content

  

20 November 2018
Volume 53 Issue 11

 

Expression, purification and crystallization of gas vesicle structure protein GvpC from the cyanobacterium Microcystis aeruginosa

Bo-ying XU,Tian-tian ZHANG

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2018, 53(11):  1-8.  doi:10.6040/j.issn.1671-9352.0.2018.200

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Preliminary crystallographic study on the gas vesicle structure protein GvpC from the cyanobacterium Microcystis aeruginosa was performed. Firstly, gene gvpC was cloned and expressed; then, the recombinant protein was purified by denaturation and renaturation and gel filtration chromatography; the result of renaturation was detected by circular dichroism. Crystal screening was performed by sitting drop vapor diffusion techniques. GvpC was overexpressed as inclusion body in E. coli, and then the protein has been purified through denaturation and renaturation. The result of circular dichroism indicated that GvpC was refolded successfully in vitro. Crystals of GvpC were also obtained by crystal screening. Hence, the three-dimensional structure of GvpC could be determinated by solving its crystal structure.

Hierarchically porous Au-Cu thin films as catalysts for aerobic oxidation of benzyl alcohol

Shu-ren HE,Bin TANG,Xin-feng XING,Chun-ying SHI,Xiu-mei ZHANG,Xiao-mei ZHANG,Xiao-hong XU

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2018, 53(11):  9-17.  doi:10.6040/j.issn.1671-9352.0.2018.345

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Hierarchically porous Au-Cu thin films (HPAFs) fabricated on Au-Cu alloy wire surface by an alloying/dealloying process are reported, which exhibit superior catalytic performance for benzyl alcohol aerobic oxidation. The porous structure is composed of large-sized ligament channels (several micrometers) coupled with small-sized ligament pores (tens of nanometers), which interpenetrate in the big architecture. The morphology and composition of HPAFs can be easily tailored by altering electrodeposition, pretreatment and corrosion conditions. The characterization reveals that Cu residue in Au-rich ligament created an Au dominated AuCu(alloy)-CuO_x heterostruture, which is highly active for molecular oxygen activation and favorable for benzyl alcohol aerobic oxidation. Furthermore, the surface thin-layer hierarchically porous structure of HPAFs enables the decrease in the internal diffusion resistance, and therefore further improves their catalytic performance where the pore diffusion is the rate-limiting step.

Release of the antifoulant in equilibrium swollen polymer: molecular dynamics simulation

Dong-cai CHENG,Zhi-xiong HUNAG,Run-tao REN,Jing-jing WANG,Zhang-ji YE,Liang ZHANG,Yue-ping WANG

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2018, 53(11):  18-25, 34.  doi:10.6040/j.issn.1671-9352.0.2018.031

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To investigate the release of the antifouling molecules in equilibrium swelling (ES) states, molecular dynamics (MD) simulation was performed to analyze the diffusion of 4, 5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) molecule in P(MMA-co-n-BMA) immersed in water. The glass transition temperature (T_g) was simulated in the dry and equilibrium swelling states, and the dynamics of water and the pendant groups in the ES state were investigated, as well as the influence of water content on the local dynamics of water. The diffusion mechanisms of DCOIT were also analyzed. T_g values of three P(MMA-co-n-BMA)s in the ES state are from 14.84, 17.27 K to 21.73 K lower than in the dry state. Water has the higher mobility than the pendant groups by approx. 2 orders of magnitude in ES systems and has dynamic properties on the same level as those of bulk water. The diffusion of a large-mass penetrant can be controlled effectively with water and T_g as the crucial factors, and the diffusion ability of DCOIT is significantly enhanced when the swollen matrix is in the rubbery state.

Virtual brand community opinion leader recognition based on complex network——example of the Meizu Flyme community

Si-min WEI,Xian-hua ZHANG,Zhen ZHANG,Qing-chun MENG,Xia-ran ZHANG

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2018, 53(11):  26-34.  doi:10.6040/j.issn.1671-9352.0.2018.439

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A consumer response network is built based on the social relationship of the virtual brand community, and the structural characteristics of the virtual brand community is analyzed by using complex network, and individual indicators and overall indicators are selected to construct a complete indicator system of opinion leader identification. Based on this, the entropy method is used to design a calculation formula of opinion leader recognition. Finally the virtual brand community of Meizu Flyme community is taken as an example, and the appropriate number of opinion leaders are selected and its effectiveness is verified.

Privacy preservation for location-based services

Hai-yan KANG,Wan-xiang ZHU

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2018, 53(11):  35-50.  doi:10.6040/j.issn.1671-9352.0.2018.128

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The disclosure of privacy involves not only the users' locations and queries data, but also the users' identities, interests, social habits, behavior patterns and privacy hidden in these data. A review of privacy preserving for location-based services (LBS) is provided. The application scenarios of location services is introduced, the method of location privacy attack is given. The existing research on the privacy protection system structure and protection technology is summarized. Finally, future research is prospected, and a cache-based spatiotemporal disturbance method and LBS privacy protection metric hypothesis scheme are proposed.

Wireless single spectrum secure auction algorithm

Zhao-xia WU,Jia-qi WANG

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2018, 53(11):  51-55.  doi:10.6040/j.issn.1671-9352.0.2018.430

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Because of the efficiency and impartiality of the electronic auction itself, auction mechanisms which is based on wireless spectrum allocation come into being and meet the growing demand for wireless communication services. However, the secure spectrum auction algorithm is an important guarantee to ensure the operation safely of the wireless spectrum auction mechanism. According to analyze the algorithm characteristics of wireless spectrum allocation and the security requirements it ensures, a secure auction algorithm based on wireless single spectrum allocation is proposed. The algorithm combines the auction characteristics of the wireless spectrum allocation with the cryptographic mechanism to ensure the security of the information during the auction process, correctly select the auction winners, and calculate the spectrum auction price that the winner needs to pay. The analysis proves that it has higher security.

Novel artificial bee colony algorithm based on objective space decomposition for solving multi-objective optimization problems

WAN Peng-fei, GAO Xing-bao

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2018, 53(11):  56-66.  doi:10.6040/j.issn.1671-9352.0.2018.002

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When solving multi-objective optimization problems, how to keep balance between convergence and distribution of solutions is a task which extremely important, but it is not easy. In this paper, we develop a novel artificial bee colony algorithm based on objective space decomposition for solving these issues. First, we divide the objective space into a series of sub-regions by a set of direction vectors, and one solution is at least chosen at each sub-region to maintain the diversity of the obtained solutions. To improve the convergence performance, we propose a search strategy based on information exchanging and two selection strategies based on decomposition respectively to enhance the search capacity of artificial bee colony algorithm. Moreover, a search strategy based on Gaussian distribution is employed to improve the effectiveness. The proposed algorithm is empirically compared with eight state-of-the-art multi-objective evolutionary algorithms on 10 benchmark problems. The comparative results demonstrate that the convergence and distribution performance of the proposed algorithm are superior to the compared algorithms.

Important-node-based community detection algorithm

WANG Xin, ZUO Wan-li, ZHU Feng-tong, WANG Ying

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2018, 53(11):  67-77.  doi:10.6040/j.issn.1671-9352.1.2017.023

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The internal community structure is the specific expression of structural features and attribute features in complex networks. First, the maximum k eigenvectors matrix of the modularity matrix of the network was calculated based on the modularity maximization theory. Then, the method of cluster centrality was proposed and used to calculate the important nodes of the k communities as k cluster centralities. The distance between each node and k cluster centralities was calculate by Euclidean distance and each node was assigned to the nearest cluster centrality of the community. Final, k-means iterative calculation method was applied into the network and the k communities divisions was eventually obtained. The algorithm was verified experimentally on both Karate Club Network dataset and American College Football dataset. The experimental results show that the algorithm can effectively identify potential community. The algorithm improves the purity and modularity to a certain extent compared with other community detection algorithms, and with fewer iterations and higher efficiency.

Properties of the expansion factor over quotient ring

WANG Ai-lan, SONG Wei-tao, ZHAO Xiu-feng

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2018, 53(11):  78-84.  doi:10.6040/j.issn.1671-9352.0.2017.370

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Because of the simplicity, security and efficiency R-LWE-based FHE schemes become the mainstream design of FHE. The value of polynomial expansion factor of R-LWE-based FHE for quotient ring R=Z［x］/(f(x))has an important influence on the noise expansion speed for homomorphic operation of ciphertexts. Based on the expansion factor of ∞ norm for different polynomials, the values of expansion factors of ∞ norm over ring R for some special polynomials f(x)are obtained. It proves that the larger numbers of monomials with coefficient being zero for polynomials f(x), the smaller the corresponding expansion factors is. The higher the power of a monomial with a coefficient of 0, the smaller the corresponding expansion factor. The results can provide theoretical guidance for the design of efficient R-LWE-based FHE schemes.

Grid community case classification and distribution model based on Bayesian decision

WANG He-qin, WANG Yang

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2018, 53(11):  85-94.  doi:10.6040/j.issn.1671-9352.3.2018.001

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Along with the intensification of urbanization in China, smart city and collaborative governance are becoming the novel paradigm of development. In the meantime, popularization of information technology and smart end devices makes it possible for civilians to widely participate in social public management. However, traditional channels of communication between people and government and the community management platform architecture have failed to meet the increasingly growing scale of data and the social reality that civilians are broadly engaging in urban governance. Hence, the grid community case classification and distribution model based on the Bayesian decision is proposed in this study. Firstly, the model adopted uses the theory of Bayesian decision to analyze and classify the social management case information that civilians have handed in. Then, involving the location information as the cases report, it ensures the certain social grid where exactly it is. Consequently, cases are to be delivered to the relevant departments of the social grid to which it belongs in terms of the classification results. K-fold cross-validation results show that the case distribution model proposed in the study has high availability and accuracy.