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January 15,2017
Volume 10,Issue 1
Pages -
Subject Area:Extraction,Chemical System Engineering,Electrochemistry,Coordination Chemistry,Catalytic Chemistry,Fatigue,Heat Transfer,Applied Mathematics,Computational Mathematics

Title: Separating aromatics from aromatics/aliphatics mixtures using deep eutectic solvents formed by tetraethylammonium chloride and different hydrogen bond donors

Authors: WANG Yan, HOU Yucui, REN Shuhang, YAO Congfei, JI Youan, WU Weize
PP: 106-112
Abstract: In this paper, three kinds of deep eutectic solvents (DESs) were used to separate toluene/ n-heptane mixtures. The DESs were made of tetraethylammonium chloride (TEAC) as a hydrogen bond acceptor (HBA) and levulinic acid (LA), ethylene glycol (EG), and triethylene glycol (TEG), which was used as a hydrogen bond donor (HBD) respectively. It was found that when the mole ratio of TEAC to LA was 1:4, this kind of DES showed the best performance to separate toluene from n-heptane among the three kinds of synthetized DESs. Then the DES made of TEAC and LA was used to separate various model oil systems. When the model oil was made of toluene and linear aliphatics, the longer the chain of aliphatics, the higher purity of toluene was obtained. When the model oil was made of benzene and cyclohexane, the DES could also separate the mixture well even though the aliphatic was in a ring state. As a conclusion, the DES made of TEAC and LA at a mole ratio of 1:4 can separate aromactics from aliphatics mixtures efficiently. This work can provide useful information for the application of DESs to separate aromactics/aliphatics mixtures.
Keywords: extraction; deep eutectic solvents; aromatics and aliphatics mixtures; hydrogen bond acceptor; hydrogen bond donor

Title: Study on the dynamic control of extractive dividing-wall column for separating ethyl acetate-acetonitrile systems with azeotrope

Authors: WANG Xiaohong, TIAN Guangzhen, XIE Li
PP: 98-105
Abstract: In order to separate the system of ethyl acetate-acetonitrile, a new separating process of extractive dividing-wall column was put forward to replace the distillation of the conventional sequence. Using the software of Aspen Plus, the steady-state process was optimized. On the basis of the steady state flow sheet, the dynamic characteristics of control structure were studied and the effectiveness of the control structure was evaluated by the disturbance of feed flow rate and feed composition. Results show that the basic control structure cannot deal with the disturbance of feed flow rate and feed composition well. The problems of large deviation of purity and slow response to the temperature would still be existed. Ultimately, the improved control structure scheme with temperature controller, composition controller and q/f (ratio of reboil thermal load and feed quantity) feed-forward control can deal with the disturbance of feed flow rate and feed composition well. The results will be of theoretical guiding significance to the design and production of the industrial separation process for lower carbon binary azeotrope systems.
Keywords: chemical system engineering; ethyl acetate-acetonitrile; extractive dividing-wall column; dynamic simulation; control scheme

Title: Electrocatalytic performance of PtCuNi ternary alloy nanocrystals doped with high-melting-point metal

Authors: CHEN Kai, TU Wenzhe, LI Yujing
PP: 89-97
Abstract: This paper focused mainly on PtCuNi alloy nanocrystals which are synthesized with monodispersity in size through facile solvothermal approach, utilizes an acidic treatment protocol to remove organic capping agents and obtain clean surface, and then carries out a surface doping of W atoms, in order to drastically achieve the enhancement of activity and durability towards oxygen reduction reaction (ORR). By loading the PtCuNi nanocrystals on high surface area carbon black, PtCuNi-W/C can be obtained as practically usable electrocatalysts. The ORR electrochemical measurements reveal that as-synthesized PtCuNi-W/C shows obviously enhanced ORR performance, with a 2.1-time electrochemical surface area (ECSA) compared with commercial Pt/C catalyst. They display a mass activity (MA) of 2.42 A/mgPt and specific activity (SA) of 2.22 mA/cm2, which means 15.1- and 9.3-fold enhancements, respectively, compared with the commercial Pt/C (0.16 A/mgPt of MA and 0.24 mA/cm2 of SA). Further accelerated durability test, by exerting 20 000 cycles of potential scanning, reveals the high stability of the PtCuNi-W/C catalyst. This work demonstrates that by surface-doping of W atoms, the activity and stability of the Pt-alloy catalysts can be greatly enhanced, which provides a new thought for designing high performance ORR catalysts of fuel cell.
Keywords: electrochemistry; alloy nanocrystal; surface doping; PtCuNi alloy; oxygen reduction reaction; fuel cell

Title: Synthesis and structure characterization of [Mn3(C10H6NO6)2(H2O)6]•H2O

Authors: LI Zhimeng, CHEN Ming, REN Guojian, ZHANG Cailing, ZHI Xia, NIU Cheng, WANG Fuxiang
PP: 83-88
Abstract: A novel complex [Mn3(L2)2(H2O)6]•H2O (1) (H3L2 = 5-carboxyamino-isophthalic acid, H3L2 is obtained by decarboxylation of H4L1) was hydrothermally synthesized using H4L1 [H4L1=5-(bis- carboxymethyl-amino)-isophthalic acid] as organic ligand and characterized by X-ray single crystal structure analysis, elemental analysis, infrared spectroscopy (IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA). Complex 1 is of monoclinic, space group C2/c. The structural analysis results showed that a 2D layer is constructed by the assembly of Mn2 clusters, organic ligands, and Mn atoms, meanwhile, a 3D supramolecular structure is formed through hydrogen bonding between the adjacent layers.
Keywords: coordination chemistry; coordination polymer; hydrogen bond; supramolecular; solvothermal synthesis

Title: Stability of Ni/silica-alumina catalyst in the hydrogenation of 1,4-butynediol aqueous solution

Authors: LI Haitao, GUO Jiangyuan, LIU Linli, WANG Zhipeng, YANG Guofeng, ZHAO Yongxiang
PP: 76-82
Abstract: The SA-1 and SA-2 supports were obtained by introducing silicon oxide into the boehmite and alumina, respectively. The Ni/alumina, Ni/SA-1 and Ni/SA-2 catalysts with 15% Ni loading were prepared by equal volume impregnation method using SA-1, SA-2 and alumina as supports. The stability of catalysts in the catalytic hydrogenation of 1,4-butyndiol was investigated. Also, combined with the X-ray diffraction (XRD), nitrogen adsorption-desorption, Fourier transform infrared spectroscopy (FTIR), temperature programmed oxidation-mass spectroscopy (TPO-MS) methods, the evolution of structure and texture properties of the catalyst was discussed. The results showed that, three kinds of catalysts exhibit different degrees of activity decay in 1,4-butynediol hydrogenation reaction. The Ni/SA-1 catalyst shows not only the highest initial activity, but also better stability than other catalysts. The active component aggregation, surface area carbon and pore blockage exist in the used catalysts. In addition, hydration of alumina also exists in Ni/alumina catalyst. These may be the main causes for the active decay of catalysts.
Keywords: catalytic chemistry; Ni/silica-alumina; stability; aqueous phase hydrogenation; 1,4-butynediol; 1,4-butanediol

Title: Base cleavage of 7,7-dimethyl-2-methylenebicyclo[3.1.1]heptan-6-one

Authors: ZHU Yujuan, HE Ling, LI Weidong
PP: 69-75
Abstract: 2,2,4-trimethyl-3-cyclohexene-1-carboxylic acid (2a) is an important synthetic intermediate in organic synthesis. Basic cleavage of 7,7-dimethyl-2-methylenebicyclo[3.1.1]heptan-6-one (13) with potassium hydroxide, potassium t-butoxide (t-BuOK), potassium bis(trimethylsilyl)amide (KHMDS) was studied in this work and confirmed that KHMDS was the most efficient base, providing 2,2,4-trimethyl-3-cyclohexene-1-carboxylic acid (2a) with high regioselectivity respectively. Cleavage of 13 with potassium t-BuOK afforded the corresponding esters simultaneously. The protonation was speculated to process through a 1,5-σ proton shift to produce 2a.
Keywords: organic chemistry; 7,7-dimethyl-2-methylenebicyclo[3.1.1]heptan-6-one; cyclobutanone; hydrolytic cleavage; 1,5-σ proton shift

Title: Closure and crack-tip plasticity of short fatigue growing cracks

Authors: WANG Deqiang, ZHU Mingliang, XUAN Fuzhen
PP: 63-68
Abstract: The crack closure and crack-tip plasticity were investigated based on in situ short crack growth experiment combined with digital image correlation (DIC) technique. Results showed that closure effect existed in short crack growth process, and the level of closure was similar at loading and unloading stages. A revised model for calculating size of cyclic plastic zone was proposed by taking crack closure into account, and the predicted values agreed well with DIC results.
Keywords: fatigue; short fatigue crack; crack closure; cyclic plastic zone; digital image correlation technique

Title: Research of analogy experiment material deformation properties of CO2 injection buried layer

Authors: DONG Yan, LIU Weiqun, SANG Sheng, ZHU Li
PP: 58-62
Abstract: In order to study the reservoir caprock’s deformation and the variation characteristics of field of stress in the process of injecting CO2 to coal with the similar simulation experiment, it’s necessary to study the relativity of imbibitions of the water bar, which substitute for coal seam, and coal seam’s adsorption for CO2. To this end, experiments of full immersion and unconstrained condition end-to-end flood to water bar was carried out, and the results of experiments and the existing results of coal’s adsorption for CO2 were compared. The results demonstrate that there is a well positive correlation between imbibition of the water bar and the expansion of adsorption of coal seam for CO2, and it’s feasible to substitute the water bar for coal seam. The course of injecting of CO2 to coal seam was simulated by the course of water absorption of the water bar. The simulate experiments to research the changing rule of deformation and stress of reservoir cap when injecting CO2 to coal seam were carried out, and then the conditions of security of CO2 coal storage were studied. It is meaningful for researching the security of CO2 coal storage.
Keywords: solid mechanics; CO2 seam sequestration; adsorption swelling; deformation; analogy experiment; similar materials

Title: Morphology study of longitudinal hydraulic fracture during hydraulic fracturing process

Authors: FU Daming, SHANG Fuling
PP: 49-57
Abstract: Longitudinal hydraulic fracture may be with one wing or two wings during hydraulic fracturing process. In this paper, hydraulic fracture with one wing is considered initially form after well fracture, the corresponding finite element model (FEM) model is proposed, and the condition that hydraulic fracture with one wing changes into hydraulic fractures with two wings is analyzed. Taking into account the influence of pore pressure on the stress-strain relationship of rock, we use Biot’s poroelastic theory as the theoretical basis of numerical calculation. This theory can well describe the mechanical behavior of underground rock. Be taking into account the influence of pore pressure on hydraulic fracture, the generalized J integral formula for hydraulic fracture is derived further. Numerical results show that this formula can give a reasonable interpretation for the crack-tip effect of hydraulic fracture. The FEM results show that both the hydraulic fracture with one wing and the asymmetric hydraulic fracture with two wings may emerge when the difference between the two ground stresses parallel to the cross-section of the wellbore is small. In addition, the critical bottomhole pressure for that the hydraulic fracture with one wing changes into the hydraulic fracture with two wings at the beginning of fracturing is obtained.
Keywords: solid mechanics; longitudinal hydraulic fracture; Biot constitutive relation; hydraulic fracture with one wing; hydraulic fracturing

Title: Natural element method for transient vector radiative transfer in one-dimensional scattering media

Authors: ZHANG Yong, YI Hongliang, TAN Heping
PP: 41-48
Abstract: In this work, a natural element method (NEM) model for the polarized light propagation model in one-dimensional scattering medium with short-pulsed laser irraditaion is established. The NEM of parallel light and diffuse Stokes vector in the transient process was realized simultaneously. Firstly, a square short-pulsed laser transport in the atmosphere with Mie scattering is simulated. The distributions of Stokes vector at different time obtained by the present method compare well with those by Monte Carlo method (MCM) which shows that the NEM is accurate and effective in solving transient polarized radiative transfer. Afterwards, the transient polarized radiative transfer problem in the atmosphere-ocean two-layer system with short-pulsed irradiation is investigated. The Stokes vector, time-resolved reflected signals and the polarization state of the Stokes vector are presented and analyzed.
Keywords: heat transfer; participant media; vector radiative; short-pulsed laser; natural element method

Title: Eigenvalues and eigenstates of the evolution operator of quantum random walk on 1D chain

Authors: WANG Yue, XU Xinping
PP: 35-40
Abstract: Using the Chebyshev polynomial method, we derive the eigenvalues and eigenstates of the evolution operator of the discrete-time quantum random walk on 1D chain for the first time. It is found that the eigenvalues of the evolution operator are closely related to the Chebyshev polynomial of the second kind. The results presented in this paper are important to quantatively analyze the dynamical properties of discrete-time quantum random walk on 1D chain.
Keywords: theoretical physics; statistical physics; quantum physics; quantum random walk; complex network

Title: Ultrafast carrier dynamics and broadband saturable absorption in graphene

Authors: JIANG Yaqin
PP: 28-34
Abstract: In order to make graphene material better application in ultrafast optoelectronic field, in this paper, systematical study of the ultrafast carrier dynamics in graphene from the shape, layers and excitation intensity was made. It is found that the shape and number of layers don’t affect the dynamics process, but the excitation intensity can change carrier concentration, thus change the ultrafast relaxation process of graphene. Then we studied the nonlinear absorption through open aperture Z-scan system from the visible to the mid-infrared broadband frequency range. This finding suggests the saturable absorption property of graphene with possible applications as a passive Q-switcher and mode-locker in ultrafast lasers and ultrafast optical switches.
Keywords: optics; graphene; ultrafast carrier dynamics; nonlinear absorption

Title: Research on the information spillover effect of stock markets in China, India, US: based on ternary asymmetric VAR-BEKK-GARCH model

Authors: CHEN Xiaomeng, LEI Qinli, WU Jialin
PP: 18-27
Abstract: The ternary asymmetric VAR-BEKK-GARCH model is used to test the information spillover effect of stock markets in China, India, China, the United States. The results showed that: before the financial crisis, there are significant one-way volatility spillovers and asymmetric effect between China and the United States, but existence of such relations between China and India is not existed. Meanwhile, there are no revenue spillover effect among China, the United States and India. After the financial crisis, there are a two-way volatility spillover and unidirectional asymmetric effect between China and the United States and the US stock market’s influence on Chinese stock market declines. The one-way volatility spillover effects and two-way asymmetric effect between China and India exist while the US stock market for the Indian stock market also has information spillovers. The three markets have feedback and indirect effects.
Keywords: financial mathematics; volatility spillover; asymmetric effect; BEKK-GARCH model; difference

Title: An improved backtracking adaptive matching

Authors: WANG Shaohui, CAO Yanhua
PP: 10-17
Abstract: Facing the problem of reconstruct signals with unknown sparsity in compressed sensing, in this paper, an improved backtracking adaptive matching pursuit algorithm was presented. The proposed algorithm combines the idea of backtracking in the compressed sampling matching pursuit (CoSaMP) algorithm and the idea of adaptive in sparsity adaptive matching pursuit (SAMP) algorithm. The number of support set atoms can be selected adaptively in each iterations with unknown sparsity of signals. And then it uses the idea of backtracking, the atoms corresponding to the projection coefficients which are bigger are selected again from the selected atoms through introducing parameter, so that realizes the second selecting of the atoms in the support set. Finally, the new algorithm can achieve the accuracy of reconstruction. The simulation results show that the proposed algorithm can reconstruct the original signal accurately, and it outperforms orthogonal matching pursuit (OMP) algorithm, generalized OMP (gOMP) algorithm, SAMP algorithm, and stagewise weak OMP (SWOMP) algorithm from comparing their reconstruction error.
Keywords: computational mathematics; compressed sensing; backtracking; adaptive; matching pursuit; reconstruction

Title: Pure alternative segment explicit-implicit parallel difference methods for the payment of dividend Black-Scholes equation

Authors: YAN Ruifang, SUN Shuzhen, YANG Xiaozhong
PP: 1-9
Abstract: Black-Scholes (B-S) equation is the cornerstone of option pricing theory and the research of the numerical solution has a significant effect on the pricing methods of many financial derivatives. In this paper, a numerical method with parallelism which were the pure alternative segment explicit-implicit (PASE-I) and pure alternative segment implicit-explicit (PASI-E) difference schemes for the payment of dividend B-S equation was proposed. It gave the existence and uniqueness, the stability and the convergence of numerical solution. Theoretical analysis and numerical experiments showed that PASE-I scheme and PASI-E scheme had obvious parallel computing properties and they were unconditionally stable and second-order convergence in both space and time. Their overall accuracies were better than that of the existing alternative segment explicit-implicit (ASE-I) and alternative segment implicit-explicit (ASI-E) difference schemes. The calculation time of our schemes could save 89.93% for classical Crank-Nicolson (C-N) scheme. It showed that the parallel numerical methods of PASE-I and PASI-E schemes were efficient and practical for solving the payment of dividend B-S equation.
Keywords: computational mathematics; payment of dividend Black-Scholes equation; pure alternative segment explicit-implicit difference scheme; stability; parallel computing; numerical experiment

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