Developing homogeneous ion exchange membranes derived from sulfonated polyethersulfone/N-phthaloyl-chitosan for improved hydrophilic and controllable porosity

Zhixue Li,Zhun Ma,Yuting Xu,Xiaomeng Wang,Yongchao Sun,Rong Wang,Jian Wang,Xueli Gao,Jun Gao 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.8

Ion exchange membranes (IEMs) composed of sulfonated poly (ether sulfone) (SPES) and N-phthaloyl chitosan (NPHCs) were synthesized. NPHCs was employed in membrane fabrication to improve the porosity and hydrophilicity of membranes. The effect of blend ratio of sulfonation (DS) and NPHCs content on physico-chemical characteristics of home-made membranes was investigated. The morphology of prepared membranes was investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD) and scanning electron microscopy (SEM). SEM images revealed the formation of a more porous membrane structure and smoother surface. The electrochemical and physical properties of CEMs were characterized comprising water content, contact angle, ion exchange capacity (IEC) and thermal stability. Membrane water content, surface hydrophilicity and IEC were enhanced with increase of DS and NPHCs blend ratios in casting solution. Furthermore, the diffusion coefficient was also improved slightly with increase of DS and NPHCs blend ratios in prepared membranes. Membrane potential, permselectivity, transport number and areal membrane resistance all showed decreasing trends by the increase in NPHCs blend ratio in casting solution. These results indicated that the prepared membrane has good prospective and great potential for desalination in electrodialysis applications.

Optimal birth control for competition system of three species with age-structure

Zhixue Luo 한국전산응용수학회 2007 Journal of applied mathematics & informatics Vol.24 No.1

Optimal harvesting for a population dynamics problem withage-structure and diffusion

Zhixue Luo 한국전산응용수학회 2007 Journal of applied mathematics & informatics Vol.25 No.1

Survey Analysis on Tourist Satisfaction in Jiuzhai Valley

Zhixue Liao,Maozhu Jin,Lu Huang 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.6

On the basis of empirical study on the characteristics of Jiuzhai Valley and tourist satisfaction, sample data which can reflect tourist satisfaction is obtained through questionnaires. With the help of SPSS 16.0, the data is processed and analyzed, and the result indicates that among all the factors that influent tourist satisfaction, satisfaction in varied dimensions differed greatly and each factor’s correspondent satisfaction in each dimension differed distinctively as well. Specifically, satisfaction of the scenic spot’s environment, infrastructure, management and service are higher than that of tourist scale, accommodation and catering. Correlation analysis and one-way ANOVA are adopted to analyze the aspects with low tourist satisfaction and put forward workable proposals.

OPTIMAL BIRTH CONTROL FOR COMPETITION SYSTEM OF THREE SPECIES WITH AGE-STRUCTURE

Luo, Zhixue 한국전산응용수학회 2007 Journal of applied mathematics & informatics Vol.24 No.1

In this paper, we investigate optimal policies for three age-dependent populations in a competition system, which is controlled by fertility. By using Dubovitskii-Milyutin's general theory, the maximum principles are obtained for problems with free terminal states, infinite horizon and target sets, respectively.

OPTIMAL HARVESTING FOR A POPULATION DYNAMICS PROBLEM WITH AGE-STRUCTURE AND DIFFUSION

Luo, Zhixue 한국전산응용수학회 2007 Journal of applied mathematics & informatics Vol.25 No.1

In this work, optimal harvesting policy for the predator-prey system of three species with age-dependent and diffusion is discussed. Existence and uniqueness of non-negative solution to the system are investigated by using the fixed point theorem. The existence of optimal control strategy is discussed and optimality conditions are obtained. Our results extend some known criteria.

Research and Application of Video Surveillance for Substation Sequence Control

Zhang, Zhixue,Huo, Zhihong 대한전기학회 2014 The Journal of International Council on Electrical Vol.4 No.3

Video surveillance system has been set up in new-built or reformed smart substations for safe operation, fire alarm and assets safety. In this paper video surveillance system has been developed for operation, especially for programmed operation of smart substation. Therefore, video image information besides conventional signals such as telemetry, remote signal, telecontrol, and remote regulating has been integrated in the novel integrated system to assist safety operation. The system architecture has been divided into three components and introduced in this paper firstly. Communication protocol has been developed for exchange information between integrated SCADA system and video surveillance system.

Query XML Streaming Data with List

He Zhixue,Liao Husheng 보안공학연구지원센터 2016 International Journal of Database Theory and Appli Vol.9 No.10

There has been a growing practical need for querying XML streaming data efficiently. Stream requires to be read sequentially and only once into memory, the query must be processed on the fly. QXSList technique is proposed for massive data processing, which takes the SAX events sequence as input, buffer the incoming elements for further processing, remove unnecessary elements from the buffer in time, and give the results on the fly. Data model and algorithm integrated framework are defined, the integrate methods of how to process predicate and wildcard are discussed respectively. Level value is used for determining the relationship of two elements and relational pointers are constructed for linking multi lists in this method. The experimental results show that our approach is effective and efficient on this problem, and outperforms the state-of-the-art algorithms and query engines especially for data size is very large. At the same time, memory usage is nearly constant.

Controlling Switching in Bistable [2]Catenanes by Combining Donor–Acceptor and Radical–Radical Interactions

Zhu, Zhixue,Fahrenbach, Albert C.,Li, Hao,Barnes, Jonathan C.,Liu, Zhichang,Dyar, Scott M.,Zhang, Huacheng,Lei, Juying,Carmieli, Raanan,Sarjeant, Amy A.,Stern, Charlotte L.,Wasielewski, Michael R.,Sto American Chemical Society 2012 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.134 No.28

<P>Two redox-active bistable [2]catenanes composed of macrocyclic polyethers of different sizes incorporating both electron-rich 1,5-dioxynaphthalene (DNP) and electron-deficient 4,4′-bipyridinium (BIPY<SUP>2+</SUP>) units, interlocked mechanically with the tetracationic cyclophane cyclobis(paraquat-<I>p</I>-phenylene) (CBPQT<SUP>4+</SUP>), were obtained by donor–acceptor template-directed syntheses in a threading-followed-by-cyclization protocol employing Cu(I)-catalyzed azide–alkyne 1,3-dipolar cycloadditions in the final mechanical-bond forming steps. These bistable [2]catenanes exemplify a design strategy for achieving redox-active switching between two translational isomers, which are driven (i) by donor–acceptor interactions between the CBPQT<SUP>4+</SUP> ring and DNP, or (ii) radical–radical interactions between CBPQT<SUP>2(•+)</SUP> and BIPY<SUP>•+</SUP>, respectively. The switching processes, as well as the nature of the donor–acceptor interactions in the ground states and the radical–radical interactions in the reduced states, were investigated by single-crystal X-ray crystallography, dynamic <SUP>1</SUP>H NMR spectroscopy, cyclic voltammetry, UV/vis spectroelectrochemistry, and electron paramagnetic resonance (EPR) spectroscopy. The crystal structure of one of the [2]catenanes in its trisradical tricationic redox state provides direct evidence for the radical–radical interactions which drive the switching processes for these types of mechanically interlocked molecules (MIMs). Variable-temperature <SUP>1</SUP>H NMR spectroscopy reveals a degenerate rotational motion of the BIPY<SUP>2+</SUP> units in the CBPQT<SUP>4+</SUP> ring for both of the two [2]catenanes, that is governed by a free energy barrier of 14.4 kcal mol<SUP>–1</SUP> for the larger catenane and 17.0 kcal mol<SUP>–1</SUP> for the smaller one. Cyclic voltammetry provides evidence for the reversibility of the switching processes which occurs following a three-electron reduction of the three BIPY<SUP>2+</SUP> units to their radical cationic forms. UV/vis spectroscopy confirms that the processes driving the switching are (i) of the donor–acceptor type, by the observation of a 530 nm charge-transfer band in the ground state, and (ii) of the radical–radical ilk in the switched state as indicated by an intense visible absorption (ca. 530 nm) and near-infrared (ca. 1100 nm) bands. EPR spectroscopic data reveal that, in the switched state, the interacting BIPY<SUP>•+</SUP> radical cations are in a fast exchange regime. In general, the findings lay the foundations for future investigations where this radical–radical recognition motif is harnessed in bistable redox-active MIMs in order to achieve close to homogeneous populations of co-conformations in both the ground and switched states.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2012/jacsat.2012.134.issue-28/ja3037355/production/images/medium/ja-2012-037355_0011.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja3037355'>ACS Electronic Supporting Info</A></P>

Radically Enhanced Molecular Switches

Fahrenbach, Albert C.,Zhu, Zhixue,Cao, Dennis,Liu, Wei-Guang,Li, Hao,Dey, Sanjeev K.,Basu, Subhadeep,Trabolsi, Ali,Botros, Youssry Y.,Goddard, William A.,Stoddart, J. Fraser American Chemical Society 2012 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.134 No.39

<P>The mechanism governing the redox-stimulated switching behavior of a tristable [2]rotaxane consisting of a cyclobis(paraquat-<I>p</I>-phenylene) (CBPQT<SUP>4+</SUP>) ring encircling a dumbbell, containing tetrathiafulvalene (TTF) and 1,5-dioxynaphthalene (DNP) recognition units which are separated from each other along a polyether chain carrying 2,6-diisopropylphenyl stoppers by a 4,4′-bipyridinium (BIPY<SUP>2+</SUP>) unit, is described. The BIPY<SUP>2+</SUP> unit acts to increase the lifetime of the metastable state coconformation (MSCC) significantly by restricting the shuttling motion of the CBPQT<SUP>4+</SUP> ring to such an extent that the MSCC can be isolated in the solid state and is stable for weeks on end. As controls, the redox-induced mechanism of switching of two bistable [2]rotaxanes and one bistable [2]catenane composed of CBPQT<SUP>4+</SUP> rings encircling dumbbells or macrocyclic polyethers, respectively, that contain a BIPY<SUP>2+</SUP> unit with either a TTF or DNP unit, is investigated. Variable scan-rate cyclic voltammetry and digital simulations of the tristable and bistable [2]rotaxanes and [2]catenane reveal a mechanism which involves a bisradical state coconformation (BRCC) in which only one of the BIPY<SUP>•+</SUP> units in the CBPQT<SUP>2(•+)</SUP> ring is oxidized to the BIPY<SUP>2+</SUP> dication. This observation of the BRCC was further confirmed by theoretical calculations as well as by X-ray crystallography of the [2]catenane in its bisradical tetracationic redox state. It is evident that the incorporation of a kinetic barrier between the donor recognition units in the tristable [2]rotaxane can prolong the lifetime and stability of the MSCC, an observation which augurs well for the development of nonvolatile molecular flash memory devices.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2012/jacsat.2012.134.issue-39/ja306044r/production/images/medium/ja-2012-06044r_0014.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja306044r'>ACS Electronic Supporting Info</A></P>