Entity

Time filter

Source Type

Beijing, China

Beijing University of Chemical Technology , abbreviated as BUCT, colloquially known in Chinese as Beihua or Huada , is one of the outstanding universities in mainland China. BUCT was founded in 1958 and is affiliated with the Ministry of Education. As one of China's key institutions of higher learning, especially in chemistry studies, a member university of the Project 211, BUCT has developed from an institution of scientific specialties to a comprehensive university with a core curriculum of science, economic management, languages and other liberal arts. Wikipedia.


Kong D.,Stanford University | Wang H.,Stanford University | Lu Z.,Stanford University | Lu Z.,Beijing University of Chemical Technology | And 2 more authors.
Journal of the American Chemical Society | Year: 2014

Development of a non-noble-metal hydrogen-producing catalyst is essential to the development of solar water-splitting devices. Improving both the activity and the stability of the catalyst remains a key challenge. In this Communication, we describe a two-step reaction for preparing three-dimensional electrodes composed of CoSe2 nanoparticles grown on carbon fiber paper. The electrode exhibits excellent catalytic activity for a hydrogen evolution reaction in an acidic electrolyte (100 mA/cm2 at an overpotential of ∼180 mV). Stability tests though long-term potential cycles and extended electrolysis confirm the exceptional durability of the catalyst. This development offers an attractive catalyst material for large-scale water-splitting technology. © 2014 American Chemical Society.


Jing Y.,Tsinghua University | Wei L.,Tsinghua University | Wei L.,Beijing University of Chemical Technology | Wang Y.,Tsinghua University | Yu Y.,Tsinghua University
Microporous and Mesoporous Materials | Year: 2014

A series of novel CO2 adsorbents (SBA-15/G1-G4, SBA-15/D1-D3, SBA-15/T1-T3 and SBA-15/PAMAM1-PAMAM3) were synthesized by functionalizing SBA-15 through stepwise growth of melamine-based and acrylate-based amine dendrimers. In order to ensure that amine dendrimers had successfully grafted onto the mesopores of SBA-15, the physical properties of all the adsorbents were systematically characterized by IR spectra, thermogravimetric analysis (TGA), nitrogen adsorption/desorption, X-ray diffraction (XRD) and element analysis. Then CO2 adsorption performance was determined in fixed bed flow system under simulated flue gas (12% CO2 and 88% N2) at 30 C, 50 C and 75 C, respectively. The experimental adsorption data were analyzed and compared with theoretical and previous results. Two important findings of amine dendrimer functionalized adsorbents were revealed: primary amines were the active groups within all adsorbents and branched dendrimers could weaken diffusion resistance of CO2 adsorption. This strategy of SBA-15 grafted with amine dendrimers can provide a perspective to design further novel adsorbents for CO2 capture. © 2013 Elsevier Inc. All rights reserved.


Xu J.,Beijing University of Chemical Technology
Tetrahedron | Year: 2012

β-Lactams are crucial structural feature of β-lactam antibiotics and important intermediates in synthetic and pharmaceutical chemistry. Synthetic methods for β-lactams with π electron-withdrawing substituents, such as formyl (carbaldehyde), acyl, imino, carboxylic acids, carboxylates, carboxamides, cyano (carbonitriles), and nitro groups, on their 3- and/or 4-position(s) are presented in this review. The methods are divided mainly into intramolecular cyclizations, cycloaddition, and other methods, for example, Ugi-type reaction of β-keto acids, amines, and isonitriles, and modification of β-lactam derivatives. Cyclizations include cyclization of haloacetamidoacetates(malonates), intramolecular carbene insertion of α-diazoalkanamides, ring-opening cyclization of α,β- epoxyalkanamidoacetates, oxidative coupling of 3-oxoalkanamidoacetates, oxidative cyclization of N-p-hydroxyphenyl β-oxoalkanamides, intramolecular cyclization of aspartic acid derivatives or β-hydroxyalkanamides, and radical cyclization of N-vinyl β-oxoalkanamides. Cycloadditions incorporate Staudinger cycloaddition of ketenes and imines, cycloaddition of nitrones and alkynes, cycloaddition of nitrones and alkylidenecycopropanes and subsequent acidic rearrangement, and condensation of imines and enolates (ethers) of esters. The scope, limitation, and stereoselectivity are also discussed for some methods. Most of the β-lactam derivatives are key intermediates or precursors for preparation of β-lactam antibiotics and their analogs. © 2012 Elsevier Ltd. All rights reserved.


Wang H.,CAS Technical Institute of Physics and Chemistry | Wang H.,University of Chinese Academy of Sciences | Xie L.,Beijing University of Chemical Technology | Peng Q.,CAS Beijing National Laboratory for Molecular | And 5 more authors.
Advanced Materials | Year: 2014

Thermally activated delayed fluorescence emitters with small energy gap between the triplet and singlet (ΔEST), TXO-PhCz and TXO-TPA, have been successfully synthesized by combining a hole-transporting TPA/PhCz moiety and an electron-transporting TXO moiety. Both compounds display efficient solid-state luminescence with an efficient up-conversion of the triplet to singlet. OLEDs based on them exhibt high performance up to 21.5%, which is among the best reported for OLEDs. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Yang P.,Shaanxi Normal University | Yang W.,Beijing University of Chemical Technology
ACS Applied Materials and Interfaces | Year: 2014

It may be hardly believable that inert C-H bonds on a polymeric material surface could be quickly and efficiently transformed into C-OH by a simple and mild way. Thanks to the approaches developed recently, it is now possible to transform surface H atoms of a polymeric substrate into monolayer OH groups by a simple/mild photochemical reaction. Herein the method and application of this small-molecular interfacial chemistry is highlighted. The existence of hydroxyl groups on material surfaces not only determines the physical and chemical properties of materials but also provides effective reaction sites for postsynthetic sequential modification to fulfill the requirements of various applications. However, organic synthetic materials based on petroleum, especially polyolefins comprise mainly C and H atoms and thus present serious surface problems due to low surface energy and inertness in reactivity. These limitations make it challenging to perform postsynthetic surface sequential chemical derivatization toward enhanced functionalities and properties and also cause serious interfacial problems when bonding or integrating polymer substrates with natural or inorganic materials. Polymer surface hydroxylation based on direct conversion of C-H bonds on polymer surfaces is thus of significant importance for academic and practical industrial applications. Although highly active research results have reported on small-molecular C-H bond activation in solution (thus homogeneous), most of them, featuring the use of a variety of transition metals as catalysts, present a slow reaction rate, a low atom economy and an obvious environmental pollution. In sharp contrast to these conventional C-H activation strategies, the present Spotlight describes a universal confined photocatalytic oxidation (CPO) system that is able to directly convert polymer surface C-H bonds to C-OSO3- and, subsequently, to C-OH through a simple hydrolysis. Generally speaking, these newly implanted hydroxyl groups preserve their own reactivity toward other complementary compounds, thus creating a novel base with distinct surface properties. Thanks to this functionalized platform, a wide range of organic, inorganic and metal materials have been attached to conventional organic polymer substrates through the rational engineering of surface molecular templates from small functional groups to macromolecules. It is expected that the proposed novel CPO method and its versatile usages in advanced material applications will offer new opportunities for a variety of scientific communities, especially for those working on surface/interface modulation. © 2014 American Chemical Society.


Bai J.,Shanghai JiaoTong University | Shi Z.,Shanghai JiaoTong University | Yin J.,Shanghai JiaoTong University | Tian M.,Beijing University of Chemical Technology
Macromolecules | Year: 2014

Benzoxazine-functionalized poly(styrene-b-butadiene-b-styrene) (SBS) has been successfully synthesized via the thiol-ene click reaction. Unlike the typical method for fabrication of blends of SBS and thermosetting resins, the benzoxazine could be directly attached on to the chains of PB domains of this triblock copolymer without any prechemical modification for SBS via the incorporation of thiol functionalized benzoxazine (PTMP-BZ). AFM characterization shows that both thiol-ene and subsequent benzoxazine ring-opening reactions have a profound influence on the final morphologies of SBS, which undergoes great change from the cylinders for the pure SBS to different types of lamella structure for the SBS with different contents of the benzoxazines and the results obtained from AFM indicate that the interaction between PB and PS domains is strengthened after two reaction steps and this is responsible for the substantial improvement on the mechanical properties of material including tensile strength and storage modulus. In the meantime, the resilence of SBS is also improved significantly by the incorporation of benzoxazine and the modified SBS blends could recover its original shape without residual elongation after the tests of cyclic tensile stress-strain. © 2014 American Chemical Society.


Wu Y.,Tsinghua University | Wang D.,Tsinghua University | Chen X.,Tsinghua University | Zhou G.,Beijing University of Chemical Technology | And 2 more authors.
Journal of the American Chemical Society | Year: 2013

Here we present a shape recovery phenomenon of Pt-Ni bimetallic nanocrystals that is unequivocally attributed to the defect effects. High-resolution electron microscopy revealed the overall process of conversion from concave octahedral Pt3Ni to regular octahedral Pt 3Ni@Ni upon Ni deposition. Further experiments and theoretical investigations indicated that the intrinsic defect-dominated growth mechanism allows the site-selective nucleation of a third metal around the defects to achieve the sophisticated design of trimetallic Pt3Ni@M core-shell structures (M = Au, Ag, Cu, Rh). Consideration of geometrical and electronic effects indicated that trimetallic atomic steps in Pt3Ni@M could serve as reactive sites to significantly improve the catalytic performance, and this was corroborated by several model reactions. The synthesis strategy based on our work paves the way for the atomic-level design of trimetallic catalysts. © 2013 American Chemical Society.


Li X.,Beijing University of Chemical Technology | Yang X.,Beijing Jiaotong University
International Journal of Uncertainty, Fuzziness and Knowlege-Based Systems | Year: 2013

With fixed running times at sections, cooperative scheduling (CS) approach optimizes the dwell times and the headway time to coordinate the accelerating and braking processes for trains, such that the recovery energy generated from the braking trains can be used by the accelerating trains. In practice, trains always have stochastic departure delays at busy stations. For reducing the divergence from the given timetable, the operation company generally adjusts the running times at the following sections. Focusing on the randomness on delay times and running times, this paper proposes a stochastic cooperative scheduling (SCS) approach. Firstly, we estimate the conversion and transmission losses of recovery energy, and then formulate a stochastic expected value model to maximize the utilization of the recovery energy. Furthermore, we design a binary-coded genetic algorithm to solve the optimal timetable. Finally, we conduct experimental studies based on the operation data from Beijing Yizhuang subway line. The results show that the SCS approach can save energy by 15.13% compared with the current timetable, and 8.81% compared with the CS approach. © 2013 World Scientific Publishing Company.


Tong H.,Beijing University of Chemical Technology
Environmental technology | Year: 2011

The catalyst CuSO4-CeO2/TiO2-SiO2 (CuSO4-CeO2/TS), for low temperature catalytic reduction (LT-SCR) of NO with NH was prepared by the impregnation method. The impacts of H2O and SO2 on the catalyst were investigated. Experiments showed that H2O brought down the catalyst's activity at low reaction temperature. However, this negative effect of H2O could be mostly eliminated with a raised temperature of above 220 degrees C. In a 10-hour experiment on the catalyst's resistibility to SO2 poisoning, NO conversion increased slightly by the promoting effect of SO2. The same catalyst underwent continuous examination with both SO2 and H2O in the feed gas; NO conversion of around 90.2% was maintained for 37 hours, showing better performance than CuSO4-CeO2/TiO2. This suggested that SiO2 in the TiO2-SiO2 catalyst supported the supression of the oxidization of SO2 to SO3. Therefore, the formation of ammonium sulphate over the catalyst and the sulphation of CeO2 in the catalyst were greatly alleviated, leading to a better resistibility of the catalyst to SO2 poisioning. After the 37 hours, the catalyst activity began to fall, and an irrecoverable deactivation of the catalyst was observed.


Jiang S.,Beijing University of Chemical Technology | Wang L.,University of Chinese Academy of Sciences | Hong J.,CAS Academy of Mathematics and Systems Science
Communications in Computational Physics | Year: 2013

In this paper we propose stochastic multi-symplectic conservation law for stochastic Hamiltonian partial differential equations, and develop a stochastic multisymplectic method for numerically solving a kind of stochastic nonlinear Schrödinger equations. It is shown that the stochasticmulti- symplecticmethod preserves themultisymplectic structure, the discrete charge conservation law, and deduces the recurrence relation of the discrete energy. Numerical experiments are performed to verify the good behaviors of the stochastic multi-symplectic method in cases of both solitary wave and collision. © 2013 Global-Science Press.


A novel solid superacid catalyst TiO2-Zr-La/SO4 2- was prepared by doping Zr and La to the bulk of TiO2. The modified TiO2-Zr-La/SO4 2- and the unmodified TiO2/SO4 2- were used to catalyze the esterification of acetic acid and n-butanol, in which these two catalysts were systematically compared in a lost of aspects such as catalytic activity and stability and so on. When a small amount of Zr and La were co-doped into the bulk of TiO2, the modified catalyst obtained a by far better catalytic activity and stability than the unmodified, showing that the modified is more resistive to deactivation than the unmodified. Under the set reaction conditions, the average conversion (of acetic acid) and the 20th-cycle conversion (of acetic acid) are 88.83 and 77.35 % for the modified, 80.83 and 46.15 % for the unmodified, respectively. The two catalysts were characterized by means of FTIR, XRD, BET, SEM, TG, and NH3-TPD methods to find the possible reasons for the superiority of the modified catalyst to the unmodified one. The characteristic results indicated that the incorporation of a small amount of Zr and La into the catalyst was beneficial to the modified catalyst: (1) improving its water-tolerance; (2) increasing its surface sulfate group content; (3) decreasing its crystallinity after calcination by retarding its crystallization from amorphous TiO2 to anatase TiO2; (4) increasing its specific surface area; (5) increasing its acidity including the concentration and acid strength of the surface acidic sites of it. All the above advantageous effects arisen from the two-element-doping are to be responsible for the substantially-improved catalytic performances of the modified catalyst. © 2013 Springer Science+Business Media New York.


Zhao D.-L.,Beijing University of Chemical Technology | Luo F.,Northwestern Polytechnical University | Zhou W.-C.,Northwestern Polytechnical University
Journal of Alloys and Compounds | Year: 2010

Microwave absorbing property and complex permittivity of the nano SiC particles doped with nitrogen within the frequency range of 8.2-18 GHz were investigated. The nano SiC particles doped with nitrogen was synthesized from hexamethyldisilazane ((Me3Si)2NH) (Me:CH3) by a laser-induced gas-phase reaction. The complex permittivities of the composites can be tailored by the contents of the nano SiC particles. The real part (ε′) and imaginary part (ε″) of the complex permittivity, and the dielectric dissipation factor (tg δ = ε″/ε′) of the composites increase with the volume filling factor (v) of the nano SiC particles doped with nitrogen. The ε′ and ε″ of the composites can be effectively modeled using second-order polynomials (ε′, ε″ = Av 2 + Bv + C). The ε′ and ε″ of the nano SiC particles doped with nitrogen decrease with frequency. The high ε″ and tg δ of the nano SiC particles doped with nitrogen are believed to be caused by the substitution of nitrogen for carbon in the nanocrystals of SiC. The single layer composites of 7 wt% nano SiC particles doped with nitrogen with a thickness of 2.96 mm achieved a reflection loss below -10 dB (90% absorption) at 9.8-15.8 GHz, and the minimum value was -63.41 dB at 12.17 GHz. The reflection loss calculations show that the prepared nano SiC particles doped with nitrogen are good electromagnetic wave absorbers in the microwave range. © 2009 Elsevier B.V. All rights reserved.


Chan W.-F.,Virginia Polytechnic Institute and State University | Chen H.-Y.,University of Pittsburgh | Surapathi A.,Virginia Polytechnic Institute and State University | Taylor M.G.,University of Pittsburgh | And 4 more authors.
ACS Nano | Year: 2013

We have shown from both simulations and experiments that zwitterion functionalized carbon nanotubes (CNTs) can be used to construct highly efficient desalination membranes. Our simulations predicted that zwitterion functional groups at the ends of CNTs allow a high flux of water, while rejecting essentially all ions. We have synthesized zwitterion functionalized CNT/polyamide nanocomposite membranes with varying loadings of CNTs and assessed these membranes for water desalination. The CNTs within the polyamide layer were partially aligned through a high-vacuum filtration step during membrane synthesis. Addition of zwitterion functionalized CNTs into a polyamide membrane increased both the flux of water and the salt rejection ratio. The flux of water was found to increase by more than a factor of 4, from 6.8 to 28.7 GFD (gallons per square foot per day), as the fraction of CNTs was increased from 0 to 20 wt %. Importantly, the ion rejection ratio increased slightly from 97.6% to 98.6%. Thus, the nanotubes imparted an additional transport mechanism to the polyamide membrane, having higher flow rate and the same or slightly better selectivity. Simulations show that when two zwitterions are attached to each end of CNTs having diameters of about 15 Å, the ion rejection ratio is essentially 100%. In contrast, the rejection ratio for nonfunctionalized CNTs is about 0%, and roughly 20% for CNTs having five carboxylic acid groups per end. The increase in ion rejection for the zwitterion functionalized CNTs is due to a combination of steric hindrance from the functional groups partially blocking the tube ends and electrostatic repulsion between functional groups and ions, with steric effects dominating. Theoretical predictions indicate that an ideal CNT/polymer membrane having a loading of 20 wt % CNTs would have a maximum flux of about 20000 GFD at the conditions of our experiments. © 2013 American Chemical Society.


Tang Z.,South China University of Technology | Lei Y.,South China University of Technology | Guo B.,South China University of Technology | Zhang L.,Beijing University of Chemical Technology | Jia D.,South China University of Technology
Polymer | Year: 2012

Individually dispersed graphene colloid is prepared using cationic dye rhodamine B (RhB) as a non-covalent modifier. Characterizations by UV-vis, photoluminescence and Raman, the graphene-RhB interactions are shown to be cation-π and π-π. Subsequently, the obtained graphene is incorporated into polyvinyl alcohol (PVA) to fabricate PVA/graphene composites by simple solution casting. On addition of 1.0 wt% graphene, the tensile strength and tensile modulus are increased by 178% and 139%, respectively. Interestingly, the strain of the composites is greatly maintained, which is related to the uniqueness interfacial structure and morphology of the composites. This work provides a promising methodology to fabricate high performance graphene-based composites with superior strength and ductility by simultaneously combining the reinforcement of graphene sheets and the uniqueness interfacial structure. © 2011 Elsevier Ltd. All rights reserved.


Yang Z.,Liaoning University | Qiao Q.,Liaoning University | Yang W.,Beijing University of Chemical Technology
Electrochimica Acta | Year: 2011

Commercial LiCoO 2 has been modified with LaF 3 as a new coating material. The surface modified materials were characterized by X-ray diffraction (XRD), transmission electronic microscopy (TEM), field emission scanning electron microscopy (FE-SEM), auger electron spectroscopy (AES) and galvanostatic charge-discharge cycling. The LaF 3-coated LiCoO 2 had an initial discharge specific capacity of 177.4 mAh g -1 within the potential ranges 2.75-4.5 V (vs. Li/Li +), and showed a good capacity retention of 90.9% after 50 cycles. It was found that the overcharge tolerance of the coated cathode was significantly better than that of the pristine LiCoO 2 under the same conditions - the capacity retention of the pristine LiCoO 2 was 62.3% after 50 cycles. The improvement could be attributed to the LaF 3 coating layer that hinders interaction between LiCoO 2 and electrolyte and stabilizes the structure of LiCoO 2. Moreover, DSC showed that the coated LiCoO 2 had a higher thermal stability than the pristine LiCoO 2. © 2011 Elsevier Ltd. All rights reserved.


Yang X.,Beijing Normal University | Yan D.,Beijing Normal University | Yan D.,Beijing University of Chemical Technology
Chemical Science | Year: 2016

Luminescent metal-organic frameworks (MOFs) have received much attention due to their wide structural tunability and potential application in light-emitting diodes, biological imaging and chemical sensors. However, successful examples of long-persistent afterglow MOFs are still quite limited to date. In this work, we report that two types of Zn-terephthalate (TPA) MOFs (namely [Zn(TPA)(DMF)] (1-DMF) and MOF-5) could exhibit an obvious room-temperature afterglow emission with a time-resolved luminescence lifetime as high as 0.47 seconds. The phosphorescence-based afterglow was also highly sensitive to the temperature, and the reversible emission intensity could be recycled under high/low temperatures. Moreover, both 1-DMF and MOF-5 showed highly tunable afterglow phosphorescence colors (from cyan to yellow and from green to red, respectively) upon treatment with pyridine solution. The fluorescence/phosphorescence emission color of MOF-5 can be reversibly switched due to the addition and removal of a pyridine guest to and from the host nanochannel, as shown in both experimental and computational studies. Therefore, this work not only shows a facile method to develop MOF-based long-afterglow materials at room temperature, but also presents a strategy to tune their phosphorescence in a wide range based on host-guest interactions. © 2016 The Royal Society of Chemistry.


Zhang J.,Beijing University of Chemical Technology | Feng G.,City University of Hong Kong
Automatica | Year: 2014

This paper concerns the problem of event-driven observer-based output feedback control of linear systems. Contrary to normal sampled-data control systems, where the controller is updated periodically, in event-driven systems, it is updated only when an "event" happens, and a typical event is defined as some error signals exceeding a given threshold. Both continuous- and discrete-time event detector cases are considered. It is shown that even with the significantly reduced sampling frequency, the global uniform ultimate boundedness of the event-driven closed-loop systems can also be guaranteed. A numerical example is finally used to illustrate the effectiveness and advantages of the proposed approaches. © 2014 Elsevier Ltd. All rights reserved.


Liu T.,Dalian University of Technology | Liu T.,RWTH Aachen | Wang Y.,Beijing University of Chemical Technology
Automatica | Year: 2012

For industrial nonlinear batch processes that can be practically divided into a series of piecewise affine operating regions, a two-dimensional (2D) closed-loop iterative learning control (ILC) method is proposed for robust tracking of the set-point profile against cycle-to-cycle process uncertainties and load disturbances. Both state feedback and output feedback are considered for the control design, together with the process input and output constraints for implementation. Based on a 2D system description for the batch operation, a few synthetic performance and robust control objectives are proposed for developing the 2D ILC schemes, in combination with the 2D Lyapunov-Krasovskii functions that can guarantee monotonic state energy (or output error) decrease in both the time (during a cycle) and batch (from cycle to cycle) directions. Both the polyhedral and norm-bounded descriptions of process uncertainties are considered to derive the corresponding linear matrix inequality (LMI) conditions for the closed-loop ILC system robust stability. An important merit of these LMI conditions is that there are adjustable convergence indices prescribed for both the time and batch directions, and an adjustable robust control performance level for the closed-loop system. By specifying/optimizing these adjustable parameters to solve these LMI conditions, the 2D ILC controller can be explicitly derived for implementation. The application to a highly nonlinear continuous stirred tank reactor (CSTR) is shown to illustrate the effectiveness and merits of the proposed ILC method. © 2012 Elsevier Ltd. All rights reserved.


Li W.,Beijing University of Chemical Technology | Du Q.,Mississippi State University
IEEE Transactions on Geoscience and Remote Sensing | Year: 2014

In this paper, collaborative representation is proposed for anomaly detection in hyperspectral imagery. The algorithm is directly based on the concept that each pixel in background can be approximately represented by its spatial neighborhoods, while anomalies cannot. The representation is assumed to be the linear combination of neighboring pixels, and the collaboration of representation is reinforced by ℓ2-norm minimization of the representation weight vector. To adjust the contribution of each neighboring pixel, a distance-weighted regularization matrix is included in the optimization problem, which has a simple and closed-form solution. By imposing the sum-to-one constraint to the weight vector, the stability of the solution can be enhanced. The major advantage of the proposed algorithm is the capability of adaptively modeling the background even when anomalous pixels are involved. A kernel extension of the proposed approach is also studied. Experimental results indicate that our proposed detector may outperform the traditional detection methods such as the classic Reed-Xiaoli (RX) algorithm, the kernel RX algorithm, and the state-of-the-art robust principal component analysis based and sparse-representation-based anomaly detectors, with low computational cost. © 1980-2012 IEEE.


Du Y.,Beijing University of Technology | Shi S.,Beijing University of Technology | Dai H.,Beijing University of Chemical Technology
Particuology | Year: 2011

Zeolite P was synthesized for the first time via a novel water-bathing route at 90 °C using scrubbed diatomite, sodium hydroxide, and aluminum hydroxide as precursor, with SiO2/Al2O3, SiO2/Na2O, and H2O/Na2O molar ratios of 7.43, 3.81, and 80.00, respectively. The as-fabricated samples were characterized by means of scanning electron microscopy, X-ray diffraction, and nitrogen adsorption measurements. This study showed that (i) treating the diatomite raw material with sodium hexametaphosphate could open the pores in the diatomite via removal of the clay clogged in its pores; (ii) tetragonal mesoporous zeolite P samples with a surface area of 56-60 m2/g could be generated after 6-24 h of water-bathing reaction at 90 °C; (iii) extension of water-bathing reaction time could improve the mesoporous structure of zeolite P; and (iv) Ca2+ adsorption capacity of the zeolite P sample was about 300 cmol/kg. Such high-surface-area porous zeolite P could be used as an effective adsorbent for the treatment of water containing calcium and magnesium ions. © 2010 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.


Wang D.,Zhejiang University of Technology | Wang D.,Beijing University of Chemical Technology | Qian J.,Zhejiang University of Technology | Qin W.,Hong Kong University of Science and Technology | And 4 more authors.
Scientific Reports | Year: 2014

Bioimaging systems with cytocompatibility, photostability, red fluorescence, and optical nonlinearity are in great demand. Herein we report such a bioimaging system. Integration of tetraphenylethene (T), triphenylamine (T), and fumaronitrile (F) units yielded adduct TTF with aggregation-induced emission (AIE). Nanodots of the AIE fluorogen with efficient red emission were fabricated by encapsulating TTF with phospholipid. The AIE dots enabled three-dimensional dynamic imaging with high resolution in blood vessels of mouse brain under two-photon excitation.


Song X.,Central South University | Liu H.,Central South University | Cheng L.,Central South University | Qu Y.,Beijing University of Chemical Technology
Desalination | Year: 2010

In this study, two series of functionalized samples were prepared by means of oxidation of a commercially available activated carbon with either HNO3 or H2O2. The effect of the liquid-phase oxidation on the Pb2+ adsorption capacities of activated carbon was investigated. The porous structure of the functionalized activated carbon was characterized using N2 adsorption at 77 K. The surface functional group characteristics were examined by Fourier transform infrared (FTIR) spectroscopy, acid/base titrations, Zeta potential as well as the point of zero charge (pHPZC) measurement. The adsorption capacity for lead ions in aqueous solution was found to depend on the amount of acidic oxygen functional groups. The isothermal adsorption data were measured and were fitted with the Langmuir and Freundlich isotherm model. The adsorption capacity of activated carbon oxidized with HNO3 (10 mol L- 1) at 363 K was about 2.5 times higher than that of the original activated carbon. The increase in the adsorption capacity of the oxidized activated carbons is attributed to the increased oxygen groups, which enhanced the hydrophilicity of the activated carbon, lowered the pHPZC, made the surface more negatively charged, and increased the amount of homogeneous active sites available for lead ions. © 2010 Elsevier B.V. All rights reserved.


Liu Z.,Beijing University of Chemical Technology | Shi S.,China Coal Research Institute | Li Y.,Shanxi Institute of Coal CAS Chemistry
Chemical Engineering Science | Year: 2010

With fast increasing demand in liquid transportation fuels, limited and unevenly distributed petroleum resources, and volatile petroleum prices, coal liquefaction technologies have again received the world's attention since the beginning of this century. China has actively pursued R&D of coal liquefaction technologies in the past decade and is deploying the first and the largest direct coal liquefaction plant since WWII and the largest indirect coal liquefaction plants after Sasol, South Africa. This paper analyzes the historical developments of coal liquefaction technologies from science point of view, presents recent developments of the technologies in China, and identifies challenges of the technologies towards successful industrial application. © 2009 Elsevier Ltd. All rights reserved.


Feng Y.,French National Center for Scientific Research | Feng Y.,Beijing University of Chemical Technology | Alonso-Vante N.,French National Center for Scientific Research
Electrochimica Acta | Year: 2012

A Carbon-supported CoSe 2 nanocatalyst has been developed as an alternative non-precious metal electrocatalyst for oxygen reduction reaction (ORR) in alkaline medium. The catalyst was prepared via a surfactant-free route and its electrocatalytic activity for the ORR has been investigated in detail in 0.1 M KOH electrolyte at 25°C using rotating disk electrode (RDE) and rotating ring-disk electrode (RRDE) techniques. The prepared catalyst showed promising catalytic activity towards ORR in a four-electron transfer pathway and higher tolerance to methanol compared to commercial Pt/C catalyst in 0.1 M KOH. To some extent, the increase of CoSe 2 loading on the electrode favors a faster reduction of H 2O 2 intermediate to H 2O. © 2012 Elsevier Ltd.


Xiang Z.,Case Western Reserve University | Cao D.,Beijing University of Chemical Technology | Dai L.,Case Western Reserve University
Polymer Chemistry | Year: 2015

Two-dimensional (2D) covalent organic polymers (COPs) and derivatives hold great potential for a large variety of applications, including gas storage, sensing, energy conversion and storage, and electrocatalysis. Moreover, 2D COPs offer excellent opportunities for fundamental study on an exciting class of new polymeric materials with unique 2D structures and novel properties. However, the design and synthesis of well-defined 2D COPs remain a big challenge. In this article, we review recent progress on 2D COPs and their derivatives. Some concepts on the rational design and syntheses of well-defined 2D COPs and their derivatives are discussed, along with their potential applications as well as the perspectives and challenges in this emerging field. © 2015 The Royal Society of Chemistry.


Yan D.,Beijing Normal University | Yan D.,Beijing University of Chemical Technology
Chemistry - A European Journal | Year: 2015

Molecule-based micro-/nanomaterials have attracted considerable attention because their properties can vary greatly from the corresponding macro-sized bulk systems. Recently, the construction of multicomponent molecular solids based on crystal engineering principles has emerged as a promising alternative way to develop micro-/nanomaterials. Unlike single-component materials, the resulting multicomponent systems offer the advantages of tunable composition, and adjustable molecular arrangement, and intermolecular interactions within their solid states. The study of these materials also supplies insight into how the crystal structure, molecular components, and micro-/nanoscale effects can influence the performance of molecular materials. In this review, we describe recent advances and current directions in the assembly and applications of crystalline multicomponent micro-/nanostructures. Firstly, the design strategies for multicomponent systems based on molecular recognition and crystal engineering principles are introduced. Attention is then focused on the methods of fabrication of low-dimensional multicomponent micro-/nanostructures. Their new applications are also outlined. Finally, we briefly discuss perspectives for the further development of these molecular crystalline micro-/nanomaterials. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA.


Huang J.,Beijing University of Chemical Technology
Advanced Materials Research | Year: 2012

The design procedures of a Supervisory Control and Data Acquisition (SCADA) platform are presented for the purpose of developing, studying and evaluating process control technology. Based on Tennessee Eastman (TE) process, OPC (OLE for Process Control) communication standards and iFIX configuration software, a two-way information exchange channel between TE process and iFIX is set up via OPC. Through iFIX HMI (human machine interface), the operator can monitor the state of TE process and the operational commands can be transmitted to TE process easily. Other functions such as history view can be developed according to user's demand. With the SCADA platform, researchers could enjoy more flexible data and information in research and training programs in contrast to conventional way. © (2012) Trans Tech Publications.


Xue Z.,Renmin University of China | Xue Z.,Beijing University of Chemical Technology | Zhang Z.,CAS Beijing National Laboratory for Molecular | Han J.,Renmin University of China | And 2 more authors.
International Journal of Greenhouse Gas Control | Year: 2011

A dual amino ionic liquid with amino-functionalized imidazolium cation and taurine anion was synthesized and characterized. Absorption isotherm of carbon dioxide into the ionic liquid was investigated using a volumetric method at 303.15 and 323.15. K. Results showed that absorption capacity reached about 0.9. mol carbon dioxide per mol of ionic liquid at ambient pressure, which is a chemical process verified by NMR and FTIR. Moreover, the as-synthesized ionic liquid can be recycled at higher temperatures or under vacuum. © 2011 Elsevier Ltd.


Sun Z.,Beijing University of Technology | Wei X.,Beijing University of Technology | Han Y.,Beijing University of Technology | Tong S.,Beijing University of Technology | Hu X.,Beijing University of Chemical Technology
Journal of Hazardous Materials | Year: 2013

The electrochemically reductive dechlorination of 2,4-dichlorophenol (2,4-DCP) in aqueous solution on palladium/polymeric pyrrole-cetyl trimethyl ammonium bromide/foam-nickel electrode (Pd/PPy-CTAB/foam-Ni electrode) was investigated in this paper. Pd/PPy-CTAB/foam-Ni electrode was prepared and characterized by cyclic voltammetry (CV), scanning electron microscope (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) adsorption and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The influences of some experimental factors such as the dechlorination current, dechlorination time and the initial pH on the removal efficiency and the current efficiency of 2,4-DCP dechlorination on Pd/PPy-CTAB/foam-Ni electrode were studied. Complete removal of 2,4-DCP was achieved and the current efficiency of 47.4% could be obtained under the conditions of the initial pH of 2.2, the dechlorination current of 5mA and the dechlorination time of 50min when the initial 2,4-DCP concentration was 100mgL-1. The analysis of high performance liquid chromatography (HPLC) identified that the intermediate products were 2-chlorophenol (2-CP) and 4-chlorophenol (4-CP). The final products were mainly phenol. Its further reduction product cyclohexanone was also detected. The electrocatalytic dechlorination pathways of 2,4-DCP on Pd/PPy-CTAB/foam-Ni electrode were discussed. The stability of the electrode was favorable that it could keep dechlorination efficiency at 100% after having been reused 10 times. Results revealed that the stable prepared Pd/PPy-CTAB/foam-Ni electrode presented a good application prospect in dechlorination process with high effectiveness and low cost. © 2012 Elsevier B.V.


Liu Z.,Beijing University of Chemical Technology | Li J.,Tsinghua University | Junaid A.S.M.,University of Alberta
Catalysis Today | Year: 2010

Catalytic removal of NOx under lean-burn conditions is challenging to attain the future stringent NOx emission standards. Selective catalytic reduction (SCR) of NOx with different reducing agents and NOx storage-reduction (NSR) are viewed as the two most promising technologies for NOx removal. Although a variety of catalytic systems have been developed for these processes, their practical applications remain difficult due to catalyst deactivation caused by SO 2 in the exhaust gases. Therefore, improving catalyst tolerance against SO2 is one of the most important targets in the deNO x catalyst development. This review focuses on the knowledge and know-how that have been developed in improving the sulfur tolerance of deNO x catalysts. Ag/Al2O3 is the most promising catalyst for the HC-SCR of NOx. Support modification, H2 co-feeding and some other strategies to improve the sulfur tolerance of Ag/Al2O3 are discussed. Some novel catalyst systems with high sulfur tolerance for NH3-SCR, H2-SCR and NSR are addressed, respectively. For NSR catalysts, developing novel sulfur resistant NOx storage systems and effective desulfation processes seem to be two avenues to improve their sulfur resistance. © 2010 Elsevier B.V.


Yan J.,Nagoya Institute of Technology | Gomi M.,Nagoya Institute of Technology | Yokota T.,Nagoya Institute of Technology | Song H.,Beijing University of Chemical Technology
Applied Physics Letters | Year: 2013

We prepared the chemical-solution deposited films of BiFe 1-xGaxO3, which was previously only possibly synthesized under high-pressure and high-temperature. The thin films crystallized in rhombohedral perovskite structure (R3c) up to x = 0.05 and in tetragonal-like monoclinic structure (Cm) above x = 0.2. The coexistence of R3c and Cm phases was observed at x = 0.1. It is found that Bi-based film with coexistence phase exhibits a huge ferroelectric polarization of 230 μC cm-2, which can be attributed to the presence of the morphotropic phase boundary. © 2013 AIP Publishing LLC.


Fan M.,University of Wyoming | Jin Yang X.,Beijing University of Chemical Technology
Journal of the American Chemical Society | Year: 2010

(Figure Presented) The candidature of Fe-Si and Mg-Al alloys at millimeter-scale particle sizes for chemical degradation of disinfection byproducts (DBPs) in drinking water systems was substantiated by their enhanced corrosion resistance and catalytic effect on the degradation. The Mg-Al particles supplied electrons for reductive degradation, and the Fe-Si particles acted as a catalyst and provided the sites for the reaction. The alloy particles are obtained by mechanical milling and stable under ambient conditions. The proposed method for chemical degradation of DBPs possesses the advantages of relatively constant degradation performance, long-term durability, no secondary contamination, and ease of handling, storage and maintenance in comparison with nanoparticle systems. Copyright © 2010 American Chemical Society.


Xu P.,Rensselaer Polytechnic Institute | Wang W.,Rensselaer Polytechnic Institute | Wang W.,Beijing University of Chemical Technology | Li L.,Rensselaer Polytechnic Institute | And 3 more authors.
ACS Chemical Biology | Year: 2014

Malonyl-CoA is the rate-limiting precursor involved in the chain elongation reaction of a range of value-added pharmaceuticals and biofuels. Development of malonyl-CoA responsive sensors holds great promise in overcoming critical pathway limitations and optimizing production titers and yields. By incorporating the Bacillus subtilis trans-regulatory protein FapR and the cis-regulatory element fapO, we constructed a hybrid promoter-regulatory system that responds to a broad range of intracellular malonyl-CoA concentrations (from 0.1 to 1.1 nmol/mgDW) in Escherichia coli. Elimination of regulatory protein and nonspecific DNA cross-communication leads to a sensor construct that exhibits malonyl-CoA-dependent linear phase kinetics with increased dynamic response range. The sensors reported in this study could potentially control and optimize carbon flux leading to robust biosynthetic pathways for the production of malonyl-CoA-derived compounds. © 2013 American Chemical Society.


Dang Z.-M.,Beijing University of Chemical Technology | Yao S.-H.,University of Science and Technology Beijing | Yao S.-H.,UniverSud | Yuan J.-K.,UniverSud | Bai J.,UniverSud
Journal of Physical Chemistry C | Year: 2010

The carbon nanotube (CNT) has been chosen as an excellent candidate for acquiring high dielectric constant polymer matrix composites according to percolation theory. However, its nanometer-scale dimension makes it naturally form bundles, which makes it difficult to use. Compared with chemical modification of multiwalled carbon nanotube (MWNT), the incorporation of the third component (nanosized BaTiO3 (NBT)) particles into MWNT/polymer composites would realize the uniform dispersion of MWNT without sacrificing the inherent properties of MWNT. We reported a three-phase (NBT-MWNT)/polyvinylidene fluoride nanocomposite with a significantly enhanced dielectric constant (643 at 103 Hz) and a gradually decreased loss, which was extremely hard to be realized at the same time for composites only filled by conductive MWNT filler. Adjustable dielectric properties were discovered by employing the three-phase system due to the nanocomposites microstructure change. Furthermore, impedance analysis and simulated circuit confirmed the existence of microcapacitors comprised of MWNT- and NBT-rich composites. © 2010 American Chemical Society.


Song Y.-F.,Beijing University of Chemical Technology | Long D.-L.,University of Glasgow | Ritchie C.,University of Melbourne | Cronin L.,University of Glasgow
Chemical Record | Year: 2011

The latest advances in the area of polyoxometalate (POM)-based inorganic/organic hybrid materials prepared by self-assembly, covalent modification, and supramolecular interactions are presented. This Review is composed of five sections and documents the effect of organic cations on the formation of novel POMs, surfactant encapsulated POM-based hybrids, polymeric POM/organic hybrid materials, POMs-containing ionic crystals, and covalently functionalized POMs. In addition to their role in the charge-balancing, of anionic POMs, the crucial role of organic cations in the formation and functionalization of POM-based hybrid materials is discussed. © 2011 The Chemical Society of Japan and Wiley-VCH, Weinheim.


Wang L.,Beijing University of Chemical Technology | Zhang Y.,Anhui Normal University | Zhu Y.,Anhui Normal University
Nano Research | Year: 2010

This paper describes the synthesis of new upconverting luminescent nanoparticles that consist of YF3:Yb3+/Er3+ functionalized with poly(acrylic acid) (PAA). Unlike the upconverting nanocrystals previously reported in the literature that emit visible (blue-green-red) upconversion fluorescence, these as-prepared nanoparticles emit strong near-infrared (NIR, 831 nm) upconversion luminescence under 980 nm excitation. Scanning electron microscopy, transmission electron microscopy, and powder X-ray diffraction were used to characterize the size and composition of the luminescent nanocrystals. Their average diameter was about 50 nm. The presence of the PAA coating was confirmed by infrared spectroscopy. The particles are highly dispersible in aqueous solution due to the presence of carboxylate groups in the PAA coating. By carrying out the synthesis in the absence of PAA, YF3:Yb3+/Er3+ nanorice materials were obtained. These nanorice particles are larger (∼700 nm in length) than the PAA-functionalized nanoparticles and show strong typical visible red (668 nm), rather than NIR (831 nm), upconversion fluorescence. The new PAA-coated luminescent nanoparticles have the pottential be used in a variety of bioanalytical and medical assays involving luminescence detection and fluorescence imaging, especially in vivo fluorescence imaging, due to the deep penetration of NIR radiation. © 2010 Tsinghua University Press and Springer-Verlag Berlin Heidelberg.


Zeng C.,South China University of Technology | Tang Z.,South China University of Technology | Guo B.,South China University of Technology | Zhang L.,Beijing University of Chemical Technology
Physical Chemistry Chemical Physics | Year: 2012

For the purpose of preparing liquefied graphene oxide (GO), a process consisting of sulfonation with sodium sulfanilic acid and ionization with bulky amine-terminated Jeffamine® was designed and performed. The obtained hybrid fluid is actually a supramolecular ionic liquid (SIL) with sulfonated GO as the central anions and the terminal ammonium groups of Jeffamine® as the surrounding cations. The successful grafting of the GO sheets with Jeffamine® via an ionic structure was verified and the morphology of the SIL was characterized. The SIL based on GO (GO-SIL) exhibits excellent solubility and amphiphilicity. The rheological measurements confirm the essential viscoelasticity and the liquid-like behavior of GO-SIL. The present GO based SIL suggests promising applications in the fabrication of various GO or graphene based composite materials. In addition, the new functionalization method may guide the future work on acquiring derivatives with tunable properties by simply changing the bulky canopy. © the Owner Societies 2012.


Xing F.,Tsinghua University | Zhao B.,Tsinghua University | Shi W.,Beijing University of Chemical Technology
Electrochimica Acta | Year: 2013

This paper reports that novel method to tune the reflection properties of the ultra-black nickel-phosphorus (Ni-P) film by anodization of the Ni-P films in non-oxide acid electrolyte. The Ni-P films (x%, x stands for mass percentage of phosphorus), which possess both crystalline and amorphous structure with a thickness of 10 μm confirmed by XRD and SEM, were obtained by electroless deposited method on Al substrates. The blacking process of the Ni-P film is first divided definitely into two parts involving acid etching and oxidation testified by XPS and SEM. The mechanism study on blacking process demonstrates the acid etching introduces the change in morphology inducing the presence in conical cavities with minute hairlike structures and decreasing the reflectance; oxidation brings on the change in chemical composition enhancing the absorption capacity. The ultra-black Ni-P film with an etched pore depth of 5 μm obtained by anodization method demonstrates easiness of control and operation, strong adhesion and low reflectance (0.45%). Therefore, this work provides a facile approach for the tunable fabrication of the ultra-black Ni-P film based on anodization method in non-oxidizing acid electrolyte, which can be practical applied in fields of black coating. © 2013 Elsevier Ltd.


Tang Z.,South China University of Technology | Zhang L.,Beijing University of Chemical Technology | Zeng C.,South China University of Technology | Lin T.,South China University of Technology | Guo B.,South China University of Technology
Soft Matter | Year: 2012

A graphene material with liquid-like behavior has been synthesized by decorating graphene in a generic, non-covalent fashion and subsequently combining the modified material with bulky polymer chains. The independently dispersed graphene core was first prepared through the chemical reduction of graphene oxide using a fluorescent whitening agent, VBL, as a non-covalent modifier. The negative groups of VBL, which are anchored onto the graphene sheets, impart anionic characteristics to graphene. The combination of the modified graphene with bulky Jeffamine M2070 chains through an electrostatic interaction yields a homogeneous graphene fluid, i.e., graphene-based nanoparticle ionic materials (G-NIMs). The microstructures of G-NIMs were characterized. G-NIMs can be stably dispersed in a broad spectrum of solvents with a super-high concentration of 500 mg mL-1. The intriguing properties of the graphene core and fluidity properties of G-NIMs may offer new scientific and technological opportunities for the applications of graphene. This journal is © 2012 The Royal Society of Chemistry.


Li W.,Beijing University of Chemical Technology | Prasad S.,University of Houston | Fowler J.E.,Mississippi State University
IEEE Transactions on Geoscience and Remote Sensing | Year: 2014

The one-against-one (OAO) strategy is commonly employed with classifiers - such as support vector machines - which inherently provide binary two-class classification in order to handle multiple classes. This OAO strategy is introduced for the classification of hyperspectral imagery using discriminant analysis within kernel-induced feature spaces, producing a pair of algorithms - kernel discriminant analysis and kernel local Fisher discriminant analysis - for dimensionality reduction, which are followed by a quadratic Gaussian maximum-likelihood-estimation classifier. In the proposed approach, a multiclass problem is broken down into all possible binary classifiers, and various decision-fusion rules are considered for merging results from this classifier ensemble. Experimental results using several hyperspectral data sets demonstrate the benefits of the proposed approach - in addition to improved classification performance, the resulting classifier framework requires reduced memory for estimating kernel matrices. © 2013 IEEE.


Wang E.,Nankai University | He T.,CAS National Center for Nanoscience and Technology | Zhao L.,Nankai University | Chen Y.,Beijing University of Chemical Technology | Cao Y.,Nankai University
Journal of Materials Chemistry | Year: 2011

Tin and nitrogen co-doped titania has been prepared by a hydrolysis precipitation method and studied by X-ray diffraction, X-ray photoelectron spectroscopy, diffuse reflectance UV-vis absorption spectra, and photoluminescence. The surface area has been determined by using the BET method. Tin is incorporated into the TiO2 crystal lattice in substitutional mode, while nitrogen is present as surface species. The resultant energy levels of tin doping and nitrogen surface states are located inside the bandgap, which are close to the conduction and valence bands, respectively. Hence, co-doping of tin and nitrogen can greatly enhance the absorption in the visible light region and inhibit the recombination of photogenerated charge carriers, leading to a higher photocatalytic activity for the co-doped catalyst than pure TiO 2 and solely doped TiO2 with nitrogen or tin for degradation of 4-chlorophenol under both visible and UV-light irradiation. This indicates that co-doping simultaneously with two foreign elements is a feasible way to improve the photocatalytic activity of TiO2. © The Royal Society of Chemistry.


Li J.,Beijing University of Chemical Technology | Choi T.-M.,Hong Kong Polytechnic University | Cheng T.C.E.,Hong Kong Polytechnic University
IEEE Transactions on Systems, Man, and Cybernetics: Systems | Year: 2014

This paper is motivated by observed industrial practices. We conduct a mean variance (MV) analysis of a fast fashion supply chain with returns policy. Different from the conventional newsvendor type products, fast fashion brands plan to have stock-out because it is a feature of fast fashion and can bring some benefit. Based on the fast fashion features, we build an analytical MV optimization model for a two-echelon fast fashion supply chain to address the following research questions. 1) What are the differences and similarities in the structural properties between the supply chains that carry fast fashion products and conventional newsvendor type products? 2) How do we optimize a fast fashion supply chain with multiple retailers under the MV framework? 3) Can a simple returns policy optimize (and 'coordinate') such a multiretailer supply chain? 4) How do individual retailers' degrees of risk aversion affect the achievability of coordination? 5) Can the above simple contract help coordinate the supply chain under information asymmetry? We propose a novel approach called 'negotiated space' in the analysis. We generate several important insights which include an interesting finding that a simple returns policy can be applied to coordinate the fast fashion supply chain even in the presence of multiple retailers. © 2013 IEEE.


Xu P.,Rensselaer Polytechnic Institute | Gu Q.,Rensselaer Polytechnic Institute | Wang W.,Rensselaer Polytechnic Institute | Wang W.,Beijing University of Chemical Technology | And 4 more authors.
Nature Communications | Year: 2013

Microbial fatty acid-derived fuels have emerged as promising alternatives to petroleum-based transportation fuels. Here we report a modular engineering approach that systematically removed metabolic pathway bottlenecks and led to significant titre improvements in a multi-gene fatty acid metabolic pathway. On the basis of central pathway architecture, E. coli fatty acid biosynthesis was re-cast into three modules: the upstream acetyl coenzyme A formation module; the intermediary acetyl-CoA activation module; and the downstream fatty acid synthase module. Combinatorial optimization of transcriptional levels of these three modules led to the identification of conditions that balance the supply of acetyl-CoA and consumption of malonyl-CoA/ACP. Refining protein translation efficiency by customizing ribosome binding sites for both the upstream acetyl coenzyme A formation and fatty acid synthase modules enabled further production improvement. Fed-batch cultivation of the engineered strain resulted in a final fatty acid production of 8.6 g l-1. The modular engineering strategies demonstrate a generalized approach to engineering cell factories for valuable metabolites production. © 2013 Macmillan Publishers Limited. All rights reserved.


Owing to the existence of high index gallium nitride (GaN) confinement layer, most of the light generated inside the active layer of GaN-based light emitting diode (LED) is converted to guided optical wave, propagating back and forth in the confinement layer, and fails to emit outwardly. This waveguide effect prevents light from being extracted from inside LED; therefore the extraction efficiency remains poor for such device. This study reports analysis of LED structure by waveguide theory and optimization of light extraction efficiency via patterned dielectric interface, of which the pattern was determined by satisfying momentum matching condition for coupling of bound mode to radiation mode. The proposal was validated by finite difference time domain (FDTD) simulation of top emitting GaN LED, in which the proposed pattern was respectively induced on GaN surface and sapphire substrate. The resultant structure exhibited significant extraction efficiency enhancement over conventional unpatterned LED. And two mechanisms for the enhancement-mode coupling and wave scattering-were compared. The results also revealed that the favorable location for the top emitting GaN LED to induce patterned dielectric interface is on the GaN surface. © 2012 Elsevier GmbH. All rights reserved.


Huang K.,Tsinghua University | Wang T.,Tsinghua University | Cheng Y.,Beijing University of Chemical Technology | Zheng X.,Tsinghua University
PLoS ONE | Year: 2015

Understanding the emergence of cooperation in spatial public goods game remains a grand challenge across disciplines. Inmost previous studies, it is assumed that the investments of all the cooperators are identical, and often equal to 1. However, it is worth mentioning that players are diverse and heterogeneous when choosing actions in the rapidly developingmodern society and researchers have shown more interest to the heterogeneity of players recently. For modeling the heterogeneous players without loss of generality, it is assumed in this work that the investment of a cooperator is a random variable with uniform distribution, themean value of which is equal to 1. The results of extensive numerical simulations convincingly indicate that heterogeneous investments can promote cooperation. Specifically, a large value of the variance of the random variable can decrease the two critical values for the result of behavioral evolution effectively.Moreover, the larger the variance is, the better the promotion effect will be. In addition, this article has discussed the impact of heterogeneous investments when the coevolution of both strategy and investment is taken into account. Comparing the promotion effect of coevolution of strategy and investment with that of strategy imitation only, we can conclude that the coevolution of strategy and investment decreases the asymptotic fraction of cooperators by weakening the heterogeneity of investments, which further demonstrates that heterogeneous investments can promote cooperation in spatial public goods game. © 2015 Huang et al.


He B.,China Agricultural University | Chu Y.,China Agricultural University | Yin M.,Beijing University of Chemical Technology | Mullen K.,Max Planck Institute for Polymer Research | And 2 more authors.
Advanced Materials | Year: 2013

A fluorescent cationic core-shell nanoparticle efficiently enters into cells with high transfection efficacy. A FNP/CHT10-dsRNA complex is orally fed to insect pests and knocks down a midgut-specific chitinase gene of the Asian corn borer, which leads to death. This is the first report on the genetic control of insect pests through a non-viral gene delivery system to knock down key developmental gene expression. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Liu Z.,Beijing University of Chemical Technology | Ma L.,CAS Institute of High Energy Physics | Junaid A.S.M.,University of Alberta
Journal of Physical Chemistry C | Year: 2010

Al2O3 and its supported metal catalysts are widely used in deNOx catalysis, but the true nature of the catalytic sites and the structure-activity relationships are still unclear. By a set of systematic and comparative calculations, this study investigates the adsorption of NO and NO2 and nitrate formation via the oxidation of NO on Al2O3 and Ga modified Al2O3 surfaces using density functional theory. It is found that NOx gases (NO and NO2) preferentially adsorb on (110) planes, and are oriented in different configurations. While NO bonds with the (110) surfaces through an N-down orientation, the most stable mode of adsorption of NO2 on the (110) surfaces is a bidentate configuration, causing much higher net charge transfer from the surface and noticeable elongation of the N-O bond. Both the NO and NO2 adsorption and activation are promoted on the Ga modified Al2O3 (110) surface. Moreover, the activation energy barrier for nitrate formation via NO oxidation, a process crucial for the selective catalytic reduction of NOx, is about 35% less on the Ga modified Al2O3 (110) surface compared to the pristine Al2O3 (110) surface. This is one of the reasons for the high activity of Ga2O3-Al2O3 catalyst for the selective catalytic reduction of NOx. © 2010 American Chemical Society.


Hu X.,University of Bonn | Hu X.,Beijing University of Chemical Technology | Hu Y.,University of Bonn | Vogt M.,University of Bonn | And 2 more authors.
Journal of Chemical Information and Modeling | Year: 2012

Activity cliffs are generally defined as pairs of structurally similar compounds having large differences in potency. The analysis of activity cliffs is of general interest because structure-activity relationship (SAR) determinants can often be deduced from them. Critical questions for the study of activity cliffs include how similar compounds should be to qualify as cliff partners, how similarity should be assessed, and how large potency differences between participating compounds should be. Thus far, activity cliffs have mostly been defined on the basis of calculated Tanimoto similarity values using structural descriptors, especially 2D fingerprints. As any theoretical assessment of molecular similarity, this approach has its limitations. For example, calculated Tanimoto similarities might often be difficult to reconcile and interpret from a chemical perspective, a point of critique frequently raised in medicinal chemistry. Herein, we have explored activity cliffs by considering well-defined substructure replacements instead of calculated similarity values. For this purpose, the matched molecular pair (MMP) formalism has been applied. MMPs were systematically derived from public domain compounds, and activity cliffs were extracted from them, termed MMP-cliffs. The frequency of cliff formation was determined for compounds active against different targets, MMP-cliffs were analyzed in detail, and re-evaluated on the basis of Tanimoto similarity. In many instances, chemically intuitive activity cliffs were only detected on the basis of MMPs, but not Tanimoto similarity. © 2012 American Chemical Society.


Wang H.,Beijing University of Chemical Technology | Chen P.,Mie University
IEEE Sensors Journal | Year: 2011

In order to effectively diagnose faults for rotating machinery in the variable rotating speed, a novel diagnosis method is proposed based on time-frequency analysis techniques, the automatic feature extraction method, and fuzzy inference. The diagnosis sensitivities of three time-frequency analysis methods, namely, the short-time Fourier transform (STFT), wavelet analysis (WA), and the pseudo-Wigner-Ville distribution (PWVD), are investigated for condition diagnosis of rotating machinery. In the case of the bearing diagnosis, the diagnosis sensitivity of the PWVD was found to be highest. An extraction method for instantaneous feature spectrum is proposed using the relative crossing information (RCI), by which the feature spectrum from time-frequency distribution can be automatically extracted by a computer in order to identify among the conditions of a machine. The symptom parameters are also defined in the frequency domain using the feature spectrum extracted by the RCI. The synthetic symptom parameters can be obtained by the least squares mapping (LSM) technique to increase the diagnosis sensitivity of the symptom parameters. Based on the above studies, a fuzzy diagnosis method using sequential inference and possibility theory was also proposed, by which the conditions of machinery can be well identified sequentially. Practical examples of diagnosis for a roller bearing are given in order to verify the effectiveness of the approaches proposed in this paper. © 2006 IEEE.


Li K.,Mie University | Chen P.,Mie University | Wang H.,Beijing University of Chemical Technology
IEEE Sensors Journal | Year: 2012

This paper proposes an intelligent diagnosis method for condition diagnosis of rotating machinery by using wavelet transform (WT) and ant colony optimization (ACO), in order to detect faults and distinguish fault types at an early stage. The WT is used to extract a feature signal of each machine state from a measured vibration signal for for high-accuracy condition diagnosis. The decision method of optimum frequency area for the extraction of the feature signal is discussed by using real plant data. We convert the state identification for the condition diagnosis of rotating machinery to a clustering problem of the values of the nondimensional symptom parameters (NSPs). ACO is introduced for this purpose. NSPs are calculated with the recomposed signals of each frequency level. These parameters can reflect the characteristics of the signals measured for the condition diagnosis. The synthetic detection index (SDI), on the basis of statistical theory, is defined to evaluate the applicability of the NSPs. The SDI can be used to select better NSPs for the ACO. Practical examples of diagnosis for a bearing used in the centrifugal fan system are shown to verify the effectiveness of the methods proposed in this paper. © 2012 IEEE.


Mo S.,Beijing University of Chemical Technology
Synlett | Year: 2014

Cyanation of Aryl and Heteroaryl Bromides through In Situ Generated Grignard Reagents: Beller and co-workers disclosed the first use of NCTS as cyanating reagent. (Hetero)aryl bromides were converted into the corresponding Grignard reagents in the presence of LiCl. Subsequent cyanation of the Grignard reagents afforded (hetero)aryl nitriles. Applying this method, several interesting agrochemical and pharmaceutical intermediates, for example, 2-chloro-5-cyanopyridine and 2-(para-tolyl) benzonitrile, were synthesized. (B) Rhodium-Catalyzed Cyanation of Aryl and Alkenyl Boronic Acids: Catalyzed by [Rh(OH)(cod)] aryl and alkenyl boronic acids were successfully cyanated by NCTS. The combination of this procedure with the direct borylation of arenes and hydroboration of alkynes yields nitriles in a more straightforward fashion. (C) Cyanation of Indoles and Pyrroles Catalyzed by a Lewis Acid: Wang described a direct cyanation of indoles and pyrroles by NCTS with BFOEt as catalyst.7 The protocol does not involve a transition- metal catalyst and achieves excellent regioselectivity, providing accesss to various 3-cyanoindoles and 2-cyanopyrroles. Additionally, the cyanation of electron-rich 1,3,5-trimethoxybenzene is also successful, although with low yield. (D) Rhodium-Catalyzed Directed CH Cyanation of Arenes: Fu and co-workers achieved a [CpRhCl2]2-catalyzed directed CH cyanation with NCTS. Many different directing groups, for example, oxime, pyridine and pyrazole can be used in the CH cyanation process. The substrate can be extended to heteroarenes, such as furan, thiophene, pyrrole and indole. The overall transformation has been identified to involve a CH activation process via a KIE experiment. Independently, Anbarasan and colleagues also reported a[CpRhCl2] 2-catalyzed directed CH cyanation with NCTS, but with different additives, solvent, and directing groups. Both groups developed their methods to synthesize intermediates for some important pharmaceuticals. Most recently, using the same catalytic system, Gu et al. accomplished the directed CH cyanation of dialkyl phosphoryl directing arenes. (E) Ruthenium(II)-Catalyzed CH Cyanations of (Hetero)aryl Formamide: Employing a robust ruthenium(II) catalyst, Liu and Ackermann achieved a direct cyanation of arenes and heteroarenes with amide as directing group.11 A high site-selectivity was obtained for the heteroarene substrates. Mechanistic studies indicate a reversible CH metalation mechanism involving a cationic ruthenium(II) complex.


Yang P.,Shaanxi Normal University | Yang W.,Beijing University of Chemical Technology
Chemical Reviews | Year: 2013

Researchers discuss chemoselective phototransformation of C-H bonds on organic polymeric materials and related high-tech applications. New demands on polymer surfaces have led chemists to develop chemical systems that can directly convert C-H bonds on these soft organic material surfaces into functional groups or polymer chains in facile, efficient, specific, and selective ways. Several methods have been established for C-H transformations in molecules based on the use of different catalysts such as transition metal complexes, enzymes, and pure organic compound-catalyzed coupling methods. Examples based on photochemistry have emerged to achieve chemoselective activation of C-H bonds, which have become the emphasis of extensive discussion and summary. Top-down techniques such as photochemistry, which facilitate the preparation of gradient surfaces, have also found a wide range of applications in high-tech fields.


Liu Z.,Beijing University of Chemical Technology | Liu Z.,Clemson University | Ma L.,CAS Institute of High Energy Physics | Zhang J.,Clemson University | And 2 more authors.
Catalysis Reviews - Science and Engineering | Year: 2013

Both the CO poisoning problem on the anode and the slow oxygen reduction reaction kinetics on the cathode lead to significantly decreased output power and energy utilization efficiency and remain main obstacles hindering commercialization of proton-exchange membrane fuel cells (PEMFCs). A promising means to mitigate CO poisoning and to improve the oxidation reduction reaction (ORR) activity is through the use of platinum alloy catalysts. This article reviews recent developments in Pt alloy catalyst utilization and addresses activity comparisons and the relationship between activity and structure characteristics. The mechanisms for improved CO-tolerance and ORR activity are also discussed. Finally, theoretical studies on Pt alloy catalysts are discussed briefly. © 2013 Copyright Taylor & Francis Group, LLC.


Geng Z.,Beijing University of Chemical Technology
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2014

The theory of electronic Raman scattering in cuprate superconductors based on the t-J model is evolved to describe the magnetic field dependent electronic Raman response. The magnetic field dependence of Raman response in the overdoped regime is studied at different doping cases. The results show that the peak and intensity in the B1g and B2g symmetry give depletion as the magnetic field increased. We indicate the decrease of the superconducting order parameter Δ under the magnetic field. The overall density of Cooper pairs is also investigated and yields suppression with the increase of the magnetic fields. © 2014 Elsevier B.V.


Huang H.-C.,Beijing University of Chemical Technology | Huang H.-C.,Beijing Union University | Xu K.,Capital Normal University
Journal of Alzheimer's Disease | Year: 2012

The deposition of amyloid-β (Aβ) peptides in senile plaques is one of pathological hallmarks of Alzheimer's disease (AD). Mitochondrial dysfunction is an early event of cell apoptosis. Increasing evidence indicates that Aβ induces neuronal apoptosis through mitochondrial dysfunction. Curcumin, an anti-oxidative component of turmeric (Curcuma longa), has shown anti-tumor, anti-inflammatory, and anti-oxidative properties. In this study, we investigated the protective effects of curcumin against mitochondrial dysfunction induced by Aβ. Based on the assay results of mitochondrial metabolic markers, we found that curcumin protects human neuroblastoma SH-SY5Y cells against the Aβ-induced damage of mitochondrial energy metabolism. Curcumin inhibits Aβ-induced mitochondrial depolarization of membrane potential (Δψm) and suppresses mitochondrial apoptosis-related proteins including cytochrome c, caspase-3, and Bax, which are activated by Aβ. Aβ-induced disturbances of redox state are linked to mitochondrial dysfunction. Curcumin normalizes cellular antioxidant enzymes (including SOD and catalase) in both protein expression and activity and decreases oxidative stress level in Aβ-treated cells. Both total GSK-3β expression and phospho-Ser9 GSK-3β (pSer9-GSK-3β) are down-regulated in the cells pre-treated with curcumin. This study demonstrates curcumin-mediated neuroprotection against Aβ-induced mitochondrial metabolic deficiency and abnormal alteration of oxidative stress. Inhibition of GSK-3β is involved in the protection of curcumin against Aβ-induced mitochondrial dysfunction. © 2012-IOS Press and the authors. All rights reserved.


Wan P.,Beijing University of Chemical Technology | Chen X.,Nanyang Technological University
ChemElectroChem | Year: 2014

Inspired by natural biochemical promotion and inhibition of electron-transport processes in response to real-life physical/chemical stimuli, artificial signal-triggered bioelectrocatalysis and modulation of the electron-transfer processes of redox biomolecules are vitally important for understanding electron-transport pathways in bioelectrochemical systems and for mimicking the dynamic properties of sensitive biochemical reactions in real bioprocesses. Recently, the reversible activation and deactivation of bioelectrocatalysis by external stimuli on functional electrodes integrated with redox enzymes has been established, especially at stimuli-responsive supramolecular interfaces. Potential applications in various research fields include controllable biofuel cells, bioelectronic devices, stimuli-responsive biosensors, energy transduction, information storage, and data processing. This Minireview aims to summarize the current state-of-the-art knowledge on various controllable bioelectrocatalysts from diverse functional interfaces formed by supramolecular interactions and supramolecular assemblies. The role of the assembled interface is highlighted, and the electrochemical kinetics during "on" and "off" states of bioelectrocatalysis is discussed. Finally, possible strategies for the future design of stimuli-responsive bioelectrocatalysts integrated with multifunctional supramolecular interfaces are presented. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Zhou H.,Beijing Institute of Petrochemical Technology | Zeng D.,Beijing Institute of Petrochemical Technology | Pan S.,Beijing University of Chemical Technology
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2013

High quality polycrystalline CdZnTe films were prepared by aluminum induced crystallization (AIC) and radio frequency (r.f.) magnetron sputtering. The crystallinity, morphology and optical property of both as-deposited and AIC samples were investigated by X-ray diffraction (XRD), and atomic force microscopy (AFM), as well as Raman and ultraviolet-visible spectrometry. The results of XRD showed that AIC favours the preferential orientation [1 1 1], and promotes the crystallinity of the CdZnTe films. AFM micrographs show that the grain size was increased from 50 nm to 300 nm after AIC. In the Raman spectrum of CdZnTe films, the intensity of CdTe-like TO mode is enhanced after AIC. From the optical transmittance and absorption coefficient, the value of the band gap varied from 1.53 eV to 1.65 eV. © 2012 Elsevier B.V.


Cheng D.,Beijing University of Chemical Technology | Negreiros F.R.,CNR Institute for Chemical and Physical Processes | Apra E.,Pacific Northwest National Laboratory | Fortunelli A.,CNR Institute for Chemical and Physical Processes
ChemSusChem | Year: 2013

The conversion of CO2 into fuels and chemicals is viewed as an attractive route for controlling the atmospheric concentration and recycling of this greenhouse gas, but its industrial application is limited by the low selectivity and activity of the current catalysts. Theoretical modeling, in particular density functional theory (DFT) simulations, provides a powerful and effective tool to discover chemical reaction mechanisms and design new catalysts for the chemical conversion of CO2, overcoming the repetitious and time/labor consuming trial-and-error experimental processes. In this article we give a comprehensive survey of recent advances on mechanism determination by DFT calculations for the catalytic hydrogenation of CO2 into CO, CH 4, CH3OH, and HCOOH, and CO2 methanation, as well as the photo- and electrochemical reduction of CO2. DFT-guided design procedures of new catalytic systems are also reviewed, and challenges and perspectives in this field are outlined. Calculating transformations: A comprehensive and critical review of the status of research in the field of the chemical conversion of CO2 into carbon forms in a lower oxidation state is presented. Particular attention is devoted to the description of reaction mechanism of CO2 transformation catalyzed by various types of systems (heterogeneous, homogeneous, and electro- and photocatalysts) and to the possible essential role that theoretical and computational approaches can play in this field. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Wang Y.,Beijing Normal University | Shen Z.,Beijing Normal University | Chen X.,Beijing University of Chemical Technology
Journal of Hazardous Materials | Year: 2010

This study focused on the effects of 2,4-dichlorphenol (2,4-DCP) initial concentration, initial pH value, applied current density and supporting electrolyte in water on 2,4-DCP degradation over Er-chitosan-PbO2 electrode in a batch reactor. The results showed that higher initial 2,4-DCP concentration promoted the instantaneous current efficiency (ICE) and average current efficiency (ACE), however, 2,4-DCP degradation rate was inhibited although the removal amount was increased. In the range of initial pH between 3.3 and 12.5, both the highest and the lowest pH conditions favored 2,4-DCP degradation. With the increase of applied current density (1-10mA/cm2), 2,4-DCP degradation efficiency increased initially, however, no significant change was observed afterwards. An acidic condition and higher applied current density were more beneficial to COD removal. The removal efficiency of 2,4-DCP was increased when NaCl was used as the supporting electrolyte instead of Na2SO4 or NaNO3. The increase of supporting electrolyte (NaSO4) concentration (0.01-0.05mol/L) advanced 2,4-DCP degradation, COD removal and ACE. However, obvious inhibitory effect was exhibited when NaSO4 concentration increased over a certain value (0.1mol/L). The activity of Er-chitosan-PbO2 electrode for 2,4-DCP degradation kept steady after repeated use. © 2010 Elsevier B.V.


Song Y.Z.,Huaiyin Normal University | Song Y.,Beijing University of Chemical Technology | Zhong H.,Huaiyin Normal University
Gold Bulletin | Year: 2011

A sensor based on gold nanoparticle/doublewalled carbon nanotube-modified glassy carbon electrode is prepared. Electrochemical behavior of dopamine hydrochloride at gold nanoparticle/double-walled carbon nanotube-modified glassy carbon electrode is investigated. A simple, sensitive, and inexpensive method for determination of dopamine hydrochloride is proposed. © The Author(s) 2011. This article is published with open access at Springerlink.com.


Cao Y.,Nankai University | He T.,CAS National Center for Nanoscience and Technology | Chen Y.,Beijing University of Chemical Technology
Journal of Physical Chemistry C | Year: 2010

A new type of composite film (heterostructure) with optoelectronic properties have been prepared by coupling Sn-doped rutile TiO2 (R-TiO2-Sn) and N-doped anatase TiO2 (A-TiO2-N) with use of a sol-gel method. Under visible and UV light irradiation, it exhibits a higher photocatalytic activity than both R-TiO2-Sn and A-TiO2-N films due to the formation of a heterojunction at the interface, as well as the increase of total amount of photogenerated charge carriers and introduction of doping states. If R-TiO2-Sn is the outmost layer, moreover, the composite film shows a much higher photodegradation capability of HCHO than that when A-TiO2-N is the outmost layer. Our results offer a paradigm for developing optoelectronic functional materials that can be used in many fields, such as solar cells, photocatalysis, and photosynthesis. © 2010 American Chemical Society.


Huang C.-P.,Nanjing University of Technology | Yin X.-G.,Nanjing University | Kong L.-B.,Beijing University of Chemical Technology | Zhu Y.-Y.,Nanjing University
Journal of Physical Chemistry C | Year: 2010

The plasmon coupling in a nanorod dimer obeys the exponential size dependence according to the universal plasmon ruler equation. However, it was shown recently that such a model does not hold at short nanorod distances (Nano Lett. 2009, 9, 1651). Here we study nanorod coupling in various cases, including a nanorod dimer with asymmetrical lengths and a symmetrical dimer with varying gap width. The asymmetrical nanorod dimer causes two plasmon modes: one is the attractive lower energy mode and the other the repulsive high-energy mode. Using a simple coupled LC-resonator model, the position of dimer resonance has been determined analytically. Moreover, we found that the plasmon coupling of a symmetrical cylindrical (or rectangular) nanorod dimer is governed uniquely by the gap width scaled for the (effective) rod radius rather than for the rod length. A new plasmon ruler equation without using the fitting parameters has been proposed which agrees well with the finite-difference time-domain calculations. The method has also been extended to study plasmonic waveguiding in a linear chain of gold nanorod particles. A field decay length up to 2700 nm with a lateral mode size of about 50 nm (∼λ/28) has been suggested. © 2010 American Chemical Society.


Li X.,Beijing University of Chemical Technology
IEEE Transactions on Fuzzy Systems | Year: 2015

Fuzzy simulation is used to approximate the expected values of functions of fuzzy variables, which plays an important role in the solution algorithms of fuzzy optimization problems. The traditional discretization-based simulation algorithms fail to return a satisfactory approximation within an acceptable computation time, which hinders the applications of fuzzy optimization methods in large-size or even middle-size problems. In this paper, we first prove some equivalent formulas for the expected values of strictly monotone functions of ordinary fuzzy variables. Then, we propose a new fuzzy simulation algorithm based on the numerical integration technique. Finally, we present some numerical examples to make comparisons between the traditional approach and our approach. The results show that our approach has higher performances on the reliability, stability, and computation time. © 1993-2012 IEEE.


Fernandes D.,Adolfo Ibanez University | Pitie F.,University of Warwick | Caceres G.,Adolfo Ibanez University | Baeyens J.,Beijing University of Chemical Technology
Energy | Year: 2012

Thermal energy storage is an expanding field within the subject of renewable energy technologies. After a listing of the different possibilities available for energy storage, this paper provides a comparison of various materials for High Temperature Thermal Energy Storage (HTTS). Several attributes and needs of each solution are listed. One in particular is using the latent heat as one of the most efficient ways to store thermal energy. The mixture of phase change material (PCM) embedded in a metal foam is optimising the thermal properties of the material for latent heat energy storage. The results of previous studies show that mechanical and thermal properties of foam were extensively studied separately. This paper highlights the potential for an advanced study of thermo-mechanical properties of metal foams embedded with PCM. © 2012 Elsevier Ltd.


Qi S.,Nagoya University | Qi S.,Beijing University of Chemical Technology | Iida H.,Nagoya University | Liu L.,Nagoya University | And 3 more authors.
Angewandte Chemie - International Edition | Year: 2013

Exploding peapods? A helical syndiotactic poly(methyl methacrylate) encapsulates C60 molecules within its helical cavity to form a supramolecular peapod-like molecular wire. Sandwich devices using these molecular wires in the active layer exhibit an irreversible electrical switching effect. Calculations predict a violent Coulomb explosion in the peapod C 60 wires during the charge injection process, which would account for the observed irreversible electrical switching. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Su S.,Beijing Jiaotong University | Tang T.,Beijing Jiaotong University | Li X.,Beijing University of Chemical Technology | Gao Z.,Beijing Jiaotong University
IEEE Transactions on Intelligent Transportation Systems | Year: 2014

Energy efficiency is paid more and more attention in railway systems for reducing the cost of operation companies and emissions to the environment. In subway systems, the optimizations on timetable and driving strategy are two important and closely dependent parts of energy-efficient operations. The former regulates the fleet size and the trip time at interstations, and the latter determines the control sequences of traction and braking force during the trip. Most conventional research optimized the timetable and the driving strategy separately such that global optimality cannot be achieved. In this paper, we analyze the hierarchy of energy-efficient train operation and then propose an integrated algorithm to generate the globally optimal operation schedule, which can get better energy-saving performance. Within the criteria of meeting the passenger demand, the integrated energy-efficient algorithm can simultaneously obtain the optimal timetable and driving strategy for trains, which realizes the combination of the high-level transportation management and the low-level train operation control. The simulation results based on the Beijing Yizhuang Subway Line illustrate that the integrated algorithm can achieve a 24.0% energy reduction for one day, on average. In addition, the computation time is within 2 s, which is short enough to be applied for real-time control system. © 2000-2011 IEEE.


Yang Q.,Beijing University of Chemical Technology | Yang Q.,Charles Gerhardt Institute | Wiersum A.D.,CNRS Chemistry Laboratory | Llewellyn P.L.,CNRS Chemistry Laboratory | And 3 more authors.
Chemical Communications | Year: 2011

The ligand functionalization effect on the CO 2/CH 4 separation performance of the MOF type UiO-66(Zr) was explored computationally. The -SO 3H and -CO 2H functionalized forms show the highest selectivity, good working capacity and medium ranged CO 2 adsorption enthalpy that make these materials very promising for physisorption-based processes. © The Royal Society of Chemistry 2011.


Xu D.,Qingdao University of Science and Technology | Wang H.,Qingdao University of Science and Technology | Guo Q.,Qingdao University of Science and Technology | Ji S.,Beijing University of Chemical Technology
Fuel Processing Technology | Year: 2011

Activated carbon (AC) supported Ni-B, Co-B, and Co-Ni-B catalysts with different Co/Ni mass ratios were synthesized by impregnation of commercial activated carbon with the solution of cobalt and/or nickel salt, and then reduction of metal salts with sodium borohydride at room temperature. Structural properties and morphology of the catalysts were studied using inductively coupled plasma (ICP), XRD and SEM techniques. The B content of the catalyst is less than that required for stoichiometric alloy formation, which indicates the simultaneous presence of the Co and/or Ni metal along with Co-B and/or Ni-B alloy on the surface of activated carbon. The catalytic activity of the catalysts has been tested by measuring the hydrogen generation rate during the hydrolysis of potassium borohydride in basic medium. The results show that Co-B/AC exhibits the highest activity among Ni-B/AC, Co-B/AC and Co-Ni-B/AC catalysts investigated. For supported bimetallic boride catalysts, the catalytic activity increases with Co/Ni mass ratio. The effects of reaction parameters, such as KBH4 concentration, NaOH concentration, and reaction temperature, on the reaction were also surveyed. © 2011 Elsevier B.V. All rights reserved.


Li H.Y.,Handan College | Xiao T.,Beijing University of Chemical Technology
Advanced Materials Research | Year: 2013

A core-shell nanocomposite particle with polystyrene sphere core and polythiophene overlayer shell was synthesized through thiophene chemical oxidative polymerization using uniquely structured polystyrene latexes template. The morphology of polythiophene shell, which has nanorods shaped or featureless surface morphology, can be simply controlled through varying the dosage and feeding methods of oxidizers. © (2013) Trans Tech Publications, Switzerland.


Rafiee J.,Rensselaer Polytechnic Institute | Rafiee M.A.,Rensselaer Polytechnic Institute | Yu Z.-Z.,Beijing University of Chemical Technology | Koratkar N.,Rensselaer Polytechnic Institute
Advanced Materials | Year: 2010

(Figure Presented) The wetting of graphene films from superhydrophobic (contact angle of ∼160°) to superhydrophilic (∼0°) is controlled using surface chemistry/roughness effects. Graphene sheets dispersed in water/acetone solvents are deposited on various substrates, where the contact angle of the graphene films could be tuned from superhydrophobic to superhydrophilic by simply controlling the relative proportion of acetone and water in the solvent. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA.


Srivastava I.,Rensselaer Polytechnic Institute | Mehta R.J.,Rensselaer Polytechnic Institute | Yu Z.-Z.,Beijing University of Chemical Technology | Schadler L.,Rensselaer Polytechnic Institute | Koratkar N.,Rensselaer Polytechnic Institute
Applied Physics Letters | Year: 2011

We tracked the strain-sensitive characteristic Raman G-band shift of graphene platelets in polydimethyl-siloxane (PDMS) nanocomposites revealing the filler-to-matrix interactions. We obtained large debonding strains of ∼7% for graphene in PDMS, with the peak shift rate with strain being ∼2.4 cm-1 /composite strain % in comparison to single-walled carbon nanotube composites, where a relatively low rate of ∼0.1 cm-1 /composite strain % was obtained, suggesting enhanced load-transfer effectiveness for graphene. A surprising observation was that for large strains (>1.5%) the graphene fillers went into compression under uniaxial tensile deformation and vice versa. We propose that this effect is related to the high mobility of the PDMS chains at room temperature. © 2011 American Institute of Physics.


Wang H.,Beijing University of Chemical Technology | Chen P.,Mie University
Computers and Industrial Engineering | Year: 2011

This paper presents an intelligent diagnosis method for a rolling element bearing; the method is constructed on the basis of possibility theory and a fuzzy neural network with frequency-domain features of vibration signals. A sequential diagnosis technique is also proposed through which the fuzzy neural network realized by the partially-linearized neural network (PNN) can sequentially identify fault types. Possibility theory and the Mycin certainty factor are used to process the ambiguous relationship between symptoms and fault types. Non-dimensional symptom parameters are also defined in the frequency domain, which can reflect the characteristics of vibration signals. The PNN can sequentially and automatically distinguish fault types for a rolling bearing with high accuracy, on the basis of the possibilities of the symptom parameters. Practical examples of diagnosis for a bearing used in a centrifugal blower are given to show that bearing faults can be precisely identified by the proposed method. © 2010 Published by Elsevier Ltd. All rights reserved.


Liu Z.,Beijing University of Chemical Technology | Li J.,Tsinghua University | Woo S.I.,Korea Advanced Institute of Science and Technology
Energy and Environmental Science | Year: 2012

Selective catalytic reduction of NOx by hydrogen (H 2-SCR) in the presence of oxygen has received much attention as a potential technology for reducing NOx emissions. A lot of research has been done in order to understand the reaction mechanism of H2-SCR and some possible mechanisms have been proposed. These mechanisms can be classified into two categories: NO adsorption/dissociation mechanisms and oxidation-reduction mechanisms. Based on the discussion of the reaction mechanism, the influence of the nature of the noble metal, catalyst support, catalyst preparation method, promoters and reaction conditions (including the presence of H2 and O2, water, sulfur, CO and CO 2) on the catalytic performance of some H2-SCR catalysts has been discussed. Finally, future research directions in the area of H 2-SCR have been proposed. © 2012 The Royal Society of Chemistry.


Wei G.,University of Bremen | Zhang Y.,CAS Changchun Institute of Applied Chemistry | Steckbeck S.,University of Bremen | Su Z.,Beijing University of Chemical Technology | Li Z.,CAS Changchun Institute of Applied Chemistry
Journal of Materials Chemistry | Year: 2012

Biomimetic synthesis is one of the facile strategies for creating novel nanostructured materials. Here we reported ferritin (Fr)-mediated biomimetic synthesis of FePt nanoparticles (NPs) on graphene nanosheets (GNs). GNs were noncovalently modified with 1-pyrenebutyric acid N-hydroxysuccinimide ester to provide binding sites for Fr molecules. The successful modification was demonstrated by X-ray photoelectron spectroscopy (XPS) and the formation of GN-Fr nanohybrids were identified with atomic force microscopy (AFM) and transmission electron microscopy (TEM). FePt NPs were synthesized by chemical reduction of metallic Fe 2+ and PtCl 6 2- that entered the core of Frs. The created GN-FePt nanohybrids exhibit multifunctions like high water-solubility, ferromagnetism, fluorescence, and enhanced electrocatalytic activity. The synthesized GN-FePt nanohybrids have potential applications in drug delivery, cell imaging, and biosensors. © The Royal Society of Chemistry 2012.


Yan D.,Beijing University of Chemical Technology
Chemistry - A European Journal | Year: 2015

Molecule-based micro-/nanomaterials have attracted considerable attention because their properties can vary greatly from the corresponding macro-sized bulk systems. Recently, the construction of multicomponent molecular solids based on crystal engineering principles has emerged as a promising alternative way to develop micro-/nanomaterials. Unlike single-component materials, the resulting multicomponent systems offer the advantages of tunable composition, and adjustable molecular arrangement, and intermolecular interactions within their solid states. The study of these materials also supplies insight into how the crystal structure, molecular components, and micro-/nanoscale effects can influence the performance of molecular materials. In this review, we describe recent advances and current directions in the assembly and applications of crystalline multicomponent micro-/nanostructures. Firstly, the design strategies for multicomponent systems based on molecular recognition and crystal engineering principles are introduced. Attention is then focused on the methods of fabrication of low-dimensional multicomponent micro-/nanostructures. Their new applications are also outlined. Finally, we briefly discuss perspectives for the further development of these molecular crystalline micro-/nanomaterials. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Wang J.-Y.,Hebei University of Science and Technology | Jiang H.-C.,Beijing University of Chemical Technology | Liu Y.-M.,Hebei University of Science and Technology | Hu Y.-Q.,Hebei University of Science and Technology
Journal of Chemical Thermodynamics | Year: 2011

The density and surface tension of 1-ethyl-3-methylimidazolium l-lactate ([emim][l-lactate]) ionic liquid were determined from T = (283.15 to 333.15) K. The coefficients of thermal expansion were calculated from the experimental density results using an empirical correlation for T = (283.15 to 333.15) K. Molecular volume and standard entropies of the IL were calculated from the experimental density values. The surface properties of IL were investigated. The critical temperature and enthalpy of vaporization were also discussed. Density and surface tension have been measured over the whole composition range for {[emim][l-lactate]+water} binary systems at a temperature of 298.15 K and atmospheric pressure. Excess molar volumes VE and the surface tension deviations δγ have been determined. © 2011 Elsevier Ltd. All rights reserved.


Tian D.,Tsinghua University | Liu Z.,Tsinghua University | Li D.,Beijing University of Chemical Technology | Shi H.,Tsinghua University | And 2 more authors.
Fuel | Year: 2013

The bimetallic Ni-Fe catalysts used in CO total-methanation reaction were prepared by the impregnation method on γ-Al2O3 support for the production of substitute natural gas (SNG). The catalysts were characterized by N2 physisorption measurements, field-emission scanning electron microscopy (FE-SEM), and H2 temperature-programmed reduction (H2-TPR). The methanation performance under the industrial total-methanation conditions (0.1-3.0 MPa, H2/CO = 3.0-3.1) was studied in detail using Ni-Fe/γ-Al2O3 as a heterogeneous catalyst. The results showed that the addition of Fe to the catalyst can effectively improve the catalytic activity of Ni/γ-Al 2O3, while the high activity of bimetallic Ni-Fe catalyst was attributed to the quality of Ni-Fe alloy in the catalyst in terms of the experimental results of H2-TPR. The sample with appropriate Ni/Fe molar ratio of about 3 exhibited the highest CO conversion (near 100% at 225-550 °C) and the highest CH4 selectivity (over 99% at 300-450 °C) under the reaction pressure of 3.0 MPa. Furthermore, based on the systematic study of catalyst components, MgO in the catalyst can increase the reduction temperature of nickel oxide on the support. The silicon species as an impurity in the support play a negative role in the catalytic activity, especially for the CH4 selectivity. © 2010 Elsevier Ltd. All rights reserved.


Xu B.,Tsinghua University | He P.,Tsinghua University | Liu H.,Tsinghua University | Wang P.,Tsinghua University | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2014

Multidimensional nano-heterostructures (NHSs) that have unique dimensionality-dependent integrative and synergic effects are intriguing but still underdeveloped. Here, we report the first helical 1D/2D epitaxial NHS between CdS and ZnIn2S4. Experimental and theoretical studies reveal that the mismatches in lattice and dangling bonds between 1D and 2D units govern the growth procedure. The resulting well-defined interface induces the delocalized interface states, thus facilitate the charge transfer and enhance the performance in the photoelectrochemical cells. We foresee that the mechanistic insights gained and the electronic structures revealed would inspire the design of more complex 1D/2D NHSs with outstanding functionalities. Rotate and connect! The shape evolution of a helical 1D/2D semiconductor nano-heterostructure (NHS) consisting of CdS and ZnIn2S4 is demonstrated. This NHS exhibits enhanced performance in photoelectrochemical cells, which is explained by the interface electronic states and the tailored band alignment. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Li W.,Beijing University of Chemical Technology | Du Q.,Mississippi State University
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing | Year: 2014

Representation-based classification has gained great interest recently. In this paper, we extend our previous work in collaborative representation-based classification to spatially joint versions. This is due to the fact that neighboring pixels tend to belong to the same class with high probability. Specifically, neighboring pixels near the test pixel are simultaneously represented via a joint collaborative model of linear combinations of labeled samples, and the weights for representation are estimated by an ℓ2-minimization derived closed-form solution. Experimental results confirm that the proposed joint within-class collaborative representation outperforms other state-of-the-art techniques, such as joint sparse representation and support vector machines with composite kernels. © 2014 IEEE.


Li W.,Beijing University of Chemical Technology | Du Q.,Mississippi State University
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing | Year: 2014

By coupling the nearest-subspace classification with a distance-weighted Tikhonov regularization, nearest regularized subspace (NRS) was recently developed for hyperspectral image classification. However, the NRS was originally designed to be a pixel-wise classifier which considers the spectral signature only while ignoring the spatial information at neighboring locations. Gabor features have currently been successfully applied for hyperspectral image analysis due to the ability to represent useful spatial information. In this paper, we mainly exploit the benefits of using spatial features extracted from a simple Gabor filter for the NRS classifier. The proposed Gabor-filtering-based classifier has been validated on several real hyperspectral datasets. Experimental results demonstrate that the proposed method significantly increases the classification accuracy compared to conventional pixel-wise classifiers as well as Gabor-filtering-based support vector machine and sparse-representation-based classification. © 2008-2012 IEEE.


Yue T.,China University of Petroleum - East China | Wang X.,China University of Petroleum - East China | Huang F.,China University of Petroleum - East China | Zhang X.,Beijing University of Chemical Technology
Nanoscale | Year: 2013

Although rapid progress has been made in understanding the interaction of nanoparticles (NPs) with lipid membrane, little is known about the interaction between neighboring NPs on the membrane. With the aid of computer simulation techniques, in this work we systematically investigate the membrane mediated interaction between anisotropic NPs with at least one dimension with the size of several nanometers, and find that the interaction between neighboring NPs is orientation- and membrane wrapping-dependent. For rodlike NPs with a weak NP-membrane adhesion strength that the membrane wrapping of NPs occurs at a slow rate and has a limited extent, the orientation-dependent interaction between two neighboring anisotropic NPs arises purely as a result of non-homogeneous distribution of membrane curvature induced by anisotropic NP adsorption. While for rodlike NPs with a strong NP-membrane adhesion, the rapid wrapping rate and extensive wrapping cause the different responses of upper and lower leaflets of the membrane to the NP adsorption, which force the NPs to enter the hydrophobic part of the membrane and lead to the formation of inverted micelles surrounding the NPs. The unusual asymmetrical wrapping also induces orientation-dependent NP interaction, which shows a short-range repulsion, intermediate-range attraction and long-range repulsion for rodlike NPs. © The Royal Society of Chemistry 2013.


Wang S.-J.,Ta Hwa University of Science and Technology | Huang K.,Beijing University of Chemical Technology
Chemical Engineering and Processing: Process Intensification | Year: 2012

In the process of manufacturing terephthalic acid, very small amount of reactant . p-xylene may enter into the feed stream of an acetic acid dehydration column. Traditionally, acetic esters were used as entrainers to separate acetic acid and water by heterogeneous azeotropic distillation (HAD). However, they can contaminate the process. In the study, the feasibility of using . p-xylene as the entrainer is evaluated to eliminate the drawbacks of the HAD column using acetic esters as entrainers. An improved column is proposed for the separation of acetic acid and water in the presence of methyl acetate and tiny amount of . p-xylene. Two configurations of the HAD column using . p-xylene as the entrainer are designed by using different . p-xylene purge strategies. The HAD column with a side stream to purge . p-xylene accumulated in the column gives the most economical design.A temperature control strategy is proposed for this HAD column to maintain acetic acid compositions in both the aqueous phase of the decanter and the column bottom. The controlled stage temperatures are chosen by singular value decomposition and closed-loop analysis methods. Dynamic simulation results reveal that the proposed control strategy can maintain product purities in spite of feed flow and feed composition changes. © 2012 Elsevier B.V.


Yuan J.,Beijing University of Chemical Technology | Hao C.,Tianjin University of Traditional Chinese Medicine
Solar Energy Materials and Solar Cells | Year: 2013

The reduction of CO2 into solar fuel is not only beneficial to the reduction of CO2 emission, but also beneficial to the release of energy shortage. In this study, a solar-driven photoelectrochemical reduction reaction of CO2 to methanol is conducted using a chalcopyrite p-CuInS2 thin film as a photocathode. The CuInS2 thin film is fabricated by electrodeposition of Cu-In alloy layer followed by sulfurization. With pyridinium ion as the co-catalyst, the photoelectrochemical reduction of CO2 to methanol can occur at the overpotential of 20 mV with the faradaic efficiency of 97%. © 2012 Elsevier B.V.


Tu J.,Beijing University of Chemical Technology | Zhou W.,IBM
Information Processing Letters | Year: 2011

We consider the vertex cover P n (VCP n) problem, that is, the problem of finding a minimum weight set F⊂V such that the graph G[V-F] has no P n, where P n is a path with n vertices. The problem also has its application background. In this paper, we restrict our attention to the VCP 3 problem and give a 2-approximation algorithm using the technique of layering. © 2011 Elsevier B.V.


Zhang W.,China Agricultural University | Wei Q.,Beijing University of Chemical Technology | Wu S.,China Agricultural University | Qi D.,China Agricultural University | And 3 more authors.
Applied Energy | Year: 2014

The objective of this study was to investigate the characteristic of anaerobic co-digestion of pig manure (PM) with dewatered sewage sludge (DSS). The batch experiment was conducted under mesophilic (37±1°C) conditions at five different PM/DSS volatile solid (VS) ratios of 1:0, 2:1, 1:1, 1:2, and 0:1. The batch test evaluated the methane potential, methane production rate of the PM co-digestion with DSS at different mixing ratios. The first-order kinetic model and modified Gompertz model were also introduced to predict the methane yield and evaluate the kinetic parameters. The optimum mixing ratio of PM with DSS was 2:1 and the cumulative methane yield (CMY) was 315.8mL/gVSadded, which is greater by 82.4% than that of digesting DSS alone. This result might be due to the positive synergy of PM with DSS, which resulted in an active microbial activity and a higher hydrolytic capacity of DSS. The systems with co-digestion of PM and DSS was demonstrated to be more stable. The modified Gompertz model (R2: 0.976-0.999) showed a better fit to the experimental results and the calculated parameters indicated that the co-digestion of PM with DSS markedly improved the methane production rate and shortened the effective methane production time. © 2014 Elsevier Ltd.


Yin L.C.,Beijing University of Chemical Technology
Advanced Materials Research | Year: 2012

This thesis illustrate the effect of reusing high-temperature condensed water thermal energy and the characteristics of the methods about removing iron and oil from high-temperature condensed water, eventually propose the using of the heat-resisting NF and RO membrance system as the best choice of all methods.


Tu J.,Beijing University of Chemical Technology | Zhou W.,IBM
Theoretical Computer Science | Year: 2011

We introduce the vertex cover P n (VCP n ) problem, that is, the problem of finding a minimum weight set F⊂V such that the graph G[V-F] has no P n , where P n is a path with n vertices. The problem also has its application background. In this paper, we first show that the VCP n problem is NP-hard for any integer n≥2. Then we restrict our attention to the VC P3 problem and give a 2-approximation algorithm using the primal-dual method. © 2011 Elsevier B.V. All rights reserved.


Yue T.,China University of Petroleum - East China | Zhang X.,Beijing University of Chemical Technology | Huang F.,China University of Petroleum - East China
Soft Matter | Year: 2014

Understanding how nanoparticles (NPs) interact with the lipid membrane is of importance for their potential applications in biomedicine and cytotoxic effects. In this paper, with the aid of computer simulation techniques, we report that NPs can be wrapped by lipid membranes in a pathway different from the conventional endocytic pathway. Our simulation results show that under the conditions of strong NP-membrane adhesion and low membrane tension, NPs can be wrapped by membranes with a pathway regulated by membrane monolayer protrusion. We also find that in the monolayer protrusion mediated wrapping pathway NPs are first trapped in the membrane and the subsequent NP internalization can be achieved by several means, including decreasing the membrane tension, breaking the membrane symmetry between upper and lower leaflets, and exerting an external force on the NPs. The findings from our simulations are well supported by the free energy analysis. © 2014 The Royal Society of Chemistry.


Zhang T.,Lanzhou University of Technology | Wang Y.,Lanzhou University of Technology | Shi H.,Lanzhou University of Technology | Yang W.,Beijing University of Chemical Technology
Energy Conversion and Management | Year: 2012

This work is focused on the preparation, characterization and thermal properties of stearic acid/polycarbonate (SA/PC) microcapsule as a new kind of phase change material (PCM) for thermal energy storage, which was prepared by solution casting method. Its morphology, chemical structure and thermal performances were characterized by scanning electron microscope (SEM), Fourier transform infrared (FT-IR), differential scanning calorimetry (DSC), temperature curves and volume expansion coefficient, respectively. The results show that stearic acid was encapsulated successfully with the maximum mass fraction of 52% without leakage from the composite. The average diameter of microcapsule was found to be 0.50 μm. Two components of the composite PCM, SA and PC, have no chemical reaction and exhibit good compatibility with each other. The melting and freezing temperatures and the latent heats of the microcapsule were measured as 60.0 °C and 51.2 °C, 91.4 J/g and 96.8 J/g, respectively. Iron filings were employed to improve thermal storage and release rates and the rates increased 23% compared with the composite without iron filings. Accelerated thermal cycling test showed that the microcapsules have good thermal reliability after subjected to 1000 thermal cycling because it has similar volume expansion coefficient of polycarbonate. Due to its excellent thermal stability and reliability and simple preparation method, the shape-stabilized SA/PC microcapsule can be considered as candidate PCM for thermal energy storage applications. © 2012 Elsevier Ltd. All rights reserved.


Liu S.,Shandong University | Zhang X.,Shandong University | Yu Y.,Beijing University of Chemical Technology | Zou G.,Shandong University
Analytical Chemistry | Year: 2014

A promising electrochemiluminescence (ECL) sensing strategy was proposed with dual-stabilizers-capped CdSe quantum dots (QDs) as ECL emitters. The dual-stabilizers-capped CdSe QDs were covalently immobilized onto p-aminobenzoic acid modified glass carbon electrode with ethylenediamine as a link molecule. This strategy can preserve the completely passivated surface states of dual-stabilizers-capped CdSe QDs, so that the sensor demonstrated eye-visible greenish, band gap engineering and monochromatic ECL emission at 546 nm with a fwhm of 35 nm. Moreover, the proposed sensor could accurately quantify dopamine from 10.0 nM to 3.0 μM with a detection limit of 3.0 nM in practical drug, human urine, and cerebrospinal fluid samples without any signal amplification techniques. This strategy is promising for developing ECL sensors with high sensitivity and spectral selectivity. © 2014 American Chemical Society.


Dong F.,Tianjin University | Wang J.,Tianjin University | Wang Y.,Beijing University of Chemical Technology | Ren S.,Tianjin University
Journal of Materials Chemistry | Year: 2012

In order to obtain a high performance humidity controlling composite material, a halloysite/poly(sodium acrylate-acrylamide) (halloysite/PAA-AM copolymer) composite was first synthesized using an inverse suspending polymerization method, and the morphology, structure, specific surface area and thermal stability of the composite were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) analysis and thermogravimetry (TG). The results show that the halloysite and PAA-AM copolymer have a good combination with each other during the polymerization process. Additionally, humidity controlling behavior tests suggest that the absorption and desorption ratio of the optimal sample are 1.873 g g -1 and 1.618 g g -1 under the most favorable preparation parameters: a halloysite content of 4%, a neutralization degree of 90% and a mass ratio of acrylic acid (AA) to acrylamide (AM) of 7:1. © 2012 The Royal Society of Chemistry.


Ke X.,Beijing University of Chemical Technology | Zhang G.,Renmin University of China | Wan T.,Harbin Institute of Technology | Gao F.,Harbin Institute of Technology
Journal of Environmental Engineering (United States) | Year: 2012

This paper used a sonication-cryptic growth technique in sequencing batch reactor (SBR) to reduce sludge yield and then analyzed the accumulation of eight typical heavy metals in sludge, namely, Hg, Cr, Ni, Cu, Zn, As, Cd, and Pd. SBR-1 was blank, SBR-2 used sonication, SBR-3 was dosed with heavy metals, and SBR-4 had both sonication and heavy metals. Artificial wastewater dosed with 12.5-mg/L heavy metals was used for SBR-3 and SBR-4. Results showed that the addition of heavy metals in influent caused the latter to accumulate in sludge and that each metal exhibits different behavior. Heavy-metal addition dropped sludge bioactivity by 53% and decreased the effluent chemical oxygen demand (COD) (SBR-3 versus SBR-1). Application of sonication (each day, 15% sludge was treated for 15 min by 1.2-W/ml ultrasound) decreased the excess sludgy by almost half; however, it increased sludge heavy-metal concentration only by 3.5% (SBR-4 versus SBR-3). Furthermore, sonication benefited sludge bioactivity and thus improved the effluent COD quality. It also significantly changed the individual accumulation patterns of eight heavy metals. © 2012 American Society of Civil Engineers.


Lv B.,Nanchang Hangkong University | Huang B.,Beijing University of Chemical Technology | Huang B.,Central University of Finance and Economics
Nonlinearity | Year: 2015

Two-dimensional barotropic compressible magnetohydrodynamic equations with shear and bulk viscosities being a positive constant and a power function of the density, respectively, are considered. We prove that the Cauchy problem on the whole two-dimensional space with vacuum as the far field density admits a unique local strong solution provided the initial density and magnetic field do not decay very slowly at infinity. In particular, the initial density can have a compact support. © 2015 IOP Publishing Ltd & London Mathematical Society.


Wan Y.,CAS Beijing National Laboratory for Molecular | Gan Z.,Beijing University of Chemical Technology | Li Z.,CAS Beijing National Laboratory for Molecular
Polymer Chemistry | Year: 2014

Poly(ethylene oxide)-block-poly(ε-caprolactone) (PEG-b-PCL) copolymers with three kinds of terminal functional groups (amino, carboxyl and methoxyl) at the hydrophilic block end were synthesized via sequential ring-opening polymerization (ROP). Their structures were characterized by GPC and 1H NMR. Micelles prepared from these copolymers showed different surface charge properties. The enzymatic degradation behaviour of these charged micelles in PBS (pH 7.0) was investigated using DLS, UV and TEM. BSA was used as a model protein to simulate the interactions between charged micelles and plasma components. It was found that micelles with different surface charges showed distinct degradation behaviour using lipase PS as the enzyme and different stability in the presence of BSA. Micelles with a neutral surface group showed a slow and partial degradation, while charged micelles showed a quick and complete degradation. We found that the nature of interactions between charged micelles and proteins was critical to the stability of polymeric micelles in vitro. © 2014 The Royal Society of Chemistry.


Liu Z.,Beijing University of Chemical Technology
Huagong Xuebao/CIESC Journal | Year: 2016

This paper analyzes fast coal pyrolysis technologies from a chemical reaction engineering point of view. It shows that the volatiles generated from coal transport in a direction against that of the heat transfer, and that the principle behind the fast coal pyrolysis technologies, i.e. reducing pyrolysis time by increasing the heating source temperature, may not reduce the reactions of volatiles as expected. Rather it promotes the reactions of volatiles leading to a low tar yield and formation of coke fines. Compared with the reduction in reaction time of volatiles the reduction in pyrolysis temperature is more important for reducing the volatiles' reaction (cracking), and therefore is favorable for a high tar yield and less coke formation in tar. © All Right Reserved.


Zhao L.,Beijing University of Chemical Technology | Zhao F.,Yunnan Normal University
Zeitschrift fur Angewandte Mathematik und Physik | Year: 2013

In this paper, we study the following Hamiltonian elliptic systems V(x) ∈ C(ℝN), f(x,t), g(x,t) ∈ C(ℝN × ℝ are superlinear in t at infinity. Without Ambrosetti-Rabinowtitz condition, the existences of ground state solutions are obtained via the combination of generalized linking theorem and monotonicity method. © 2012 Springer Basel AG.


Li J.,Beijing University of Chemical Technology | Wang S.,CAS Academy of Mathematics and Systems Science | Cheng T.C.E.,Hong Kong Polytechnic University
International Journal of Production Economics | Year: 2010

Many retailers diversify their supply disruption risk by sourcing from multiple suppliers. While a retailer's sourcing strategy impacts the profit of the supply chain, the pricing strategies of suppliers influence all aspects of the supply chain. In this paper we investigate the sourcing strategy of a retailer and the pricing strategies of two suppliers in a supply chain under an environment of supply disruption. We characterize the sourcing strategies of the retailer in a centralized and a decentralized system. We derive a sufficient condition for the existence of an equilibrium price in the decentralized system when the suppliers are competitive. Based on the assumption of a uniform demand distribution, we obtain an explicit form of the solutions when the suppliers are competitive. Finally we devise a coordination mechanism to maximize the profits of both suppliers. © 2009 Elsevier B.V. All rights reserved.


Zhang H.,Massachusetts Institute of Technology | Pereira B.,Massachusetts Institute of Technology | Li Z.,Massachusetts Institute of Technology | Li Z.,Beijing University of Chemical Technology | And 2 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2015

Engineering microbial consortia to express complex biosynthetic pathways efficiently for the production of valuable compounds is a promising approach for metabolic engineering and synthetic biology. Here, we report the design, optimization, and scale-up of an Escherichia coli-E. coli coculture that successfully overcomes fundamental microbial production limitations, such as high-level intermediate secretion and low-efficiency sugar mixture utilization. For the production of the important chemical cis,cis-muconic acid, we show that the coculture approach achieves a production yield of 0.35 g/g from a glucose/xylose mixture, which is significantly higher than reported in previous reports. By efficiently producing another compound, 4-hydroxybenzoic acid, we also demonstrate that the approach is generally applicable for biosynthesis of other important industrial products.


Choi T.-M.,Hong Kong Polytechnic University | Li J.,Beijing University of Chemical Technology | Wei Y.,Jinan University
Decision Support Systems | Year: 2013

Information sharing has been known to be crucial in supply chain management. Prior empirical finding reveals that suppliers in practice tend to help their trading partners improve forecast accuracy. This paper examines this issue and explores the up-down (from an upstream supplier to a downstream retailer) strategic information sharing issues in a two-echelon supply chain. We first model a supply chain with forecast updating and returns policy. The forecast updating scheme adopts the Bayesian approach with unknown mean and unknown variance. We then proceed to analytically explore the effects of forecast updating on the supplier and the retailer. Our analysis has revealed that: 1. Demand information with low relevance can lead to a loss to the retailer. 2. In the absence of returns policy, the supplier has an incentive to provide "bad information" which may be harmful to the retailer. 3. The supplier will provide "good information" to the retailer only under the returns policy. 4. With up-down information sharing, win-win coordination can be achieved by using a proper returns policy. Many of these results can supplement and challenge the prior research findings that supplier has good incentive to help retailers in improving forecast. © 2013 Elsevier B.V.


Dong Y.,Beijing University of Chemical Technology | Dong Y.,Chinese Academy of Inspection and Quarantine | Xu Y.,Osaka Prefecture University | Yong W.,Chinese Academy of Inspection and Quarantine | And 2 more authors.
Critical Reviews in Food Science and Nutrition | Year: 2014

Accompanied by industrial globalization, rapid urbanization, and population increment, mass production and staple trading for food consumption are upsoaring continuously, foodborne disease resulted from various food safety issues is currently a crucial public health concern worldwide, which has not only created a great burden on both economy and society, but also greatly threatened the sustainability of mankind's livelihood and human reproduction. In order to better ensure food safety and thus effectively curb the occurrence of foodborne diseases, the development and evolving of inspection strategies are indispensable measures for quality assurance and conformity assessment. Nowadays, as complementary measures to and with advantageous merits over classic analytical methods, highly specific and selective aptamer-based assays have found their increasingly important roles in various domains of food analysis. This critical review summarizes the advantages of aptamer as compared with antibody, introduces important evolving variants of systematic evolution of ligands by exponential enrichment (SELEX), and presents an overview of potential aptamer applications for food safety. © 2014 Copyright Taylor & Francis Group, LLC.


Zheng Q.,Tsinghua University | Hua R.,Tsinghua University | Wan Y.,Beijing University of Chemical Technology
Applied Organometallic Chemistry | Year: 2010

CuCl with the use of a catalytic amount of piperidine as additive shows high catalytic activity for the oxidative homocoupling reactions of terminal alkynes in toluene at 60 ?C in air to afford 1,3-diynes in high yields. Copyright © 2010 John Wiley & Sons, Ltd.


Yang H.,Yanshan University | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne | Zhang J.,Beijing University of Chemical Technology | Qiu J.,Hebei University of Science and Technology
Information Sciences | Year: 2012

In this paper, we investigate a robust H∞ control problem for a class of T-S fuzzy systems with time delays by using delta operator approach. It is known that a better control effect can be obtained by using delta operator approach than using shift operator approach for small sampling periods. Furthermore, the delta operator can unify some previous related continuous and discrete fuzzy systems into fuzzy delta operator system framework. Based on Lyapunov-Krasovskii functionals in delta domain, a new fuzzy H∞ state feedback controller is presented in terms of linear matrix inequalities. Some experiment results of an ball and beam model on a laboratory-scale setup are presented to illustrate the effectiveness and potential for the developed techniques. © 2011 Elsevier Inc. All rights reserved.


Wan Y.-J.,Hangzhou Normal University | Tang L.-C.,Hangzhou Normal University | Gong L.-X.,Hangzhou Normal University | Yan D.,Beijing University of Chemical Technology | And 4 more authors.
Carbon | Year: 2014

Epoxy composites filled with both graphene oxide (GO) and diglycidyl ether of bisphenol-A functionalized GO (DGEBA-f-GO) sheets were prepared at different filler loading levels. The correlations between surface modification, morphology, dispersion/exfoliation and interfacial interaction of sheets and the corresponding mechanical and thermal properties of the composites were systematically investigated. The surface functionalization of DGEBA layer was found to effectively improve the compatibility and dispersion of GO sheets in epoxy matrix. The tensile test indicated that the DGEBA-f-GO/epoxy composites showed higher tensile modulus and strength than either the neat epoxy or the GO/epoxy composites. For epoxy composite with 0.25 wt% DGEBA-f-GO, the tensile modulus and strength increased from 3.15 ± 0.11 to 3.56 ± 0.08 GPa (∼13%) and 52.98 ± 5.82 to 92.94 ± 5.03 MPa (∼75%), respectively, compared to the neat epoxy resin. Furthermore, enhanced quasi-static fracture toughness (KIC) was measured in case of the surface functionalization. The GO and DGEBA-f-GO at 0.25 wt% loading produced ∼26% and ∼41% improvements in KIC values of epoxy composites, respectively. Fracture surface analysis revealed improved interfacial interaction between DGEBA-f-GO and matrix. Moreover, increased glass transition temperature and thermal stability of the DGEBA-f-GO/epoxy composites were also observed in the dynamic mechanical properties and thermo-gravimetric analysis compared to those of the GO/epoxy composites. © 2013 Elsevier Ltd. All rights reserved.


Liang X.,Beijing University of Chemical Technology
Journal of Alloys and Compounds | Year: 2013

Series of Ni-Co bimetal hydroxides nanosheets have been obtained by tuning the molar ratio of cobalt and nickel in an oleylamine assisted synthetic system. Porous Ni-Co bimetal oxide nanosheets with tunable compositions have been obtained by directly thermal decomposition of corresponding hydroxides at 400 °C. The physicochemical properties of these Ni-Co bimetal oxides have been fully characterized and analyzed. Compared with pure NiO and Co 3O4, the bimetal oxides show better catalytic performance for CO oxidation. By increasing Co content in the reaction system, the as-prepared Ni-Co bimetal oxides system can be classified into three different crystal structure types. When Co percentage is less than 20%, the samples display identical cubic crystal structure with pure NiO and possess higher surface area and better catalytic performance than others. As Co percentage in the system is between 40% and 60%, the samples tend to form a stable lamellar structure of NiCo2O4. Co3O4 based crystal structure type of Ni-Co bimetal oxides is observed when Co percentage is more than 80%. © 2013 Elsevier B.V. All rights reserved.


Patent
Beijing University of Chemical Technology | Date: 2012-02-17

Methods for making high quality polyimide fibers suitable for continuous industrial production are described. Polyimide fibers are continuously prepared from a polyamic acid solution through sequentially spinning the polyamic acid solution by either a wet or a dry-wet process, coagulating, drying or drying after washing, thermally treating and stretching the resulting polyamic acid fibers to obtain polyimide fibers, and winding polyimide fibers as prepared into rolls.


Patent
Beijing University of Chemical Technology | Date: 2010-06-12

The present invention discloses a reactive distillation apparatus for multistage counter-current rotating bed and its application, the apparatus comprises a closed shell, in the center of which a revolving shaft linking each shell section is set, the said shaft is provided with two or more rotors in series connection, a feeding inlet, a reflux inlet and an outlet of the gas phase are mounted on the top end face of the shell while a waste liquid outlet and an inlet of the gas phase are set on the bottom end face of the shell, the said shell consists of an upper section of the shell and a lower section of the shell along the axial direction, the said rotor consists of a rotating disc firmly connecting with the revolving shaft and a static disc mounted to the shell, a group of concentric dynamic filler rings but with different diameters are installed at intervals along the radial direction, wherein the wall of the dynamic filler rings is holed, and the ring clearance between the dynamic filler rings is configured with static rings fastened on the static disc; the filler filled in the said dynamic filler ring includes a catalytic filler and a wire gauze filler with the catalyst filler filled in the dynamic filler ring of the outer circle of the upper rotor and the inner circle of the lower rotor and the wire gauze filler filled in the rest of the dynamic filler rings, to make the whole rotor structure equivalent to the distillation section, reactive distillation section and stripping section; a feeding inlet is arranged on the top cover of the shell corresponding to the spray nozzle of raw material liquid; a rotating liquid distributor is arranged on the inner side of the innermost dynamic filler ring of the said lower rotor. The catalyst of the present invention not only plays the role of catalytic reaction, but also increases the interphase mass transfer area; the present invention improves the mass transfer efficiency and the separation efficiency of the reactive distillation process.


Patent
Beijing University of Chemical Technology | Date: 2012-03-23

The present disclosure provides polyimide fibers with kidney-shaped cross-section and their preparation methods thereof, falling within the technical field of polyimide fiber. Polyimide fibers with kidney-shaped cross-sections are prepared by a continuous, integrated approach, starting from a polyamic acid solution prepared by reacting an aromatic dianhydride with an aromatic diamine. PAA nascent fibers with kidney-shaped cross-sections are obtained by adopting a spinneret having circular orifices under wet spinning process. The kidney-shaped cross-sections are obtained by varying the processing condition, including spinning speed, coagulation bath composition, coagulation temperature, and depth of coagulation bath. After washing and drying, polyamic acid nascent fibers are converted to polyimide fibers with kidney-shaped cross-sections under thermal curing. The integrated preparation methods are suitable for mass industrial production.


Patent
Beijing University of Chemical Technology | Date: 2011-12-09

A method for enhancing heterogeneous asymmetric selectivity and catalytic activity belongs to the field of catalytic asymmetric organic synthesis technology, the preparation method of the invention are as follows: firstly preparing the chiral


Patent
Beijing University of Chemical Technology and Jiangyin Ruifa Chemical Co. | Date: 2013-05-21

The present invention belongs to the synthesis technology field of inorganic functional materials, and particularly provides a self-balanced high-pressure and high-shear autoclave and its application in the preparation of layered double hydroxides (LDHs). In this invention, by imbedding the handpiece of emulsification mill into the autoclave, and by taking the motor driving system outside of the autoclave, the pressure of the autoclave can be highly stable by the use of self-balanced seal gland. These characters solve the problem that the typical emulsification mill cannot be used in high-pressure system, and ensure the crystallization under the high-pressure and high-shear conditions. Such autoclave takes the advantages of additional equipment, and eliminates the volume effect in the amplification process. By the use of this new autoclave, the reaction time can be shorten from 24 hours to 2-6 hours, the reaction temperature can be reduced from 180 C. to 140 C. The LDHs products with small particle size and narrow size distribution are obtained. These results are better than those prepared at the laboratory level.


Patent
Beijing University of Chemical Technology | Date: 2014-07-08

A method for preparing a graphene oxide/white carbon black/rubber nanocomposite material is described. The prepared graphene oxide/white carbon black/rubber nanocomposite material contains nanoscale graphene oxide and white carbon black that are highly dispersed. The nanocomposite material has a relatively high modulus, excellent wear resistance and tear resistance, a relatively low rolling resistance, and at the same time has a low air-permeability and excellent self-healing capability.


Patent
Beijing University of Chemical Technology | Date: 2014-06-29

A process for preparing a completely delaminated graphene oxide/rubber nanocomposite. The process combines emulsion compounding with flocculation or spray drying, retains the morphology of graphene oxide/rubber composite in a liquid state, and achieves highly dispersed and highly delaminated morphology dispersed on nano scale. Furthermore, a substance able to produce ionic bonding or chemical bonding with the surface functional groups of graphene oxide is added to graphene oxide/hydrosol, as a surfactant, thus the interfacial bonding between graphene oxide and the rubber is increased. The composite is subjected to subsequent compounding and vulcanization to prepare a vulcanizate with dynamic performance, such as a high tensile strength, stress at a definite elongation, tearing strength, etc.


A composition for manufacturing the inner liners and inner tubes of tires, and a method of preparing the same. The composition includes the following two phases: A) a continuous phase of a composition of graphene oxide/rubber including graphene oxide, a reactive rubber, and a solid rubber; and B) a dispersion phase of an epoxy natural rubber or a thermoplastic resin. In the composition of graphene oxide/rubber, the graphene oxide leads to low gas permeability and remarkably reinforces the rubber composition. The epoxy natural rubber or thermoplastic resin is dispersed in the composition of graphene oxide/rubber and forms an islands-in-the-sea structure. The composition has low gas permeability, excellent mechanical properties, and flexibility, and is adhesive to adjacent rubber.


Patent
Beijing University of Chemical Technology | Date: 2011-08-29

The present invention relates to an extreme low formaldehyde emission UF resin with a novel structure, and a process for its preparation. This UF resin is produced from formaldehyde, urea, a long chain multi-aldehyde prepolymer, and some modifiers. Its process follows three steps: weak caustic, weak acid and weak caustic. By using this prepolymer, the modified UF resin has stable alkyl ether structure, and the residual aldehyde groups on the UF polymer chain could accelerate cross-linking instead of dissociative formaldehyde. The UF resin made from this invention has extreme low dissociative formaldehyde and simple technology. The boards produced from this resin have good physical performance and water resistance. Moreover, the formaldehyde emission of the boards is extreme low, achieving Japan F grade, the average emission value0.3 mg/L.


The present invention relates to a method for preparing graphene using the two-dimensional confined space between the layers of inorganic layered materials. Such method comprises the following steps: mix a soluble salt of a divalent metal ion M


Patent
Wuhan University of Technology and Beijing University of Chemical Technology | Date: 2012-02-22

The present invention relates to a preparation method for a UV-shielding material based on MgAl Layered Double Hydroxide. The material with multi-layered overlay structure is made from MgAl double hydroxide layers and interlayer carbonate, its molecular composition is: Mg


Tu J.,Beijing University of Chemical Technology
Information Processing Letters | Year: 2015

A subset F of vertices of a graph G is called a vertex cover Pt set if every path of order t in G contains at least one vertex from F. Denote by ψt(G) the minimum cardinality of a vertex cover Pt set in G. The vertex cover Pt (VCPt) problem is to find a minimum vertex cover Pt set. The VCPt problem is NP-hard for any integer t≥2. In this paper, we restrict our attention to the VCP3 problem and present a fixed-parameter algorithm with runtime O(2k k3.376+n4m) for the VCP3 problem. Here, n denotes the number of vertices, m denotes the number of the edges, k denotes the size of the vertex cover P3 set searched for. © 2014 Elsevier B.V. All rights reserved.


Kandanur S.S.,Rensselaer Polytechnic Institute | Rafiee M.A.,Rensselaer Polytechnic Institute | Yavari F.,Rensselaer Polytechnic Institute | Schrameyer M.,Rensselaer Polytechnic Institute | And 3 more authors.
Carbon | Year: 2012

Polytetrafluoroethylene (PTFE) is one of the most widely used solid lubricants but suffers from a high wear rate which limits its applications. Here we report four orders of magnitude reduction in the steady state wear rate of PTFE due to graphene additives. The wear rate of unfilled PTFE was measured to be ∼0.4 × 10 -3 mm 3/N m which is reduced to ∼10 -7 mm 3/N m by the incorporation of 10 wt% of graphene platelets. We also performed a head-to-head comparison of wear rate with graphene and micro-graphite fillers at the same weight fractions. In general, we find that graphene fillers gave 10-30 times lower wear rates than micro-graphite at the same loading fraction. Scanning electron microscopy analysis indicated noticeably smaller wear debris size in the case of graphene/PTFE composites indicating that graphene additives are highly effective in regulating debris formation in PTFE leading to reduced wear. © 2011 Elsevier Ltd. All rights reserved.


Liu H.,Tsinghua University | Shen Y.,Tsinghua University | Song Y.,Tsinghua University | Nan C.-W.,Tsinghua University | And 2 more authors.
Advanced Materials | Year: 2011

A carbon nanotube (CNT)/polymer composite is prepared with a CNT array using an electrospinning method and hot-pressing technology. This composite exhibits a stable high dielectric permittivity and low dielectric loss over a wide frequency range, in addition to a large energy density. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Xu J.,Beijing University of Chemical Technology
Current Organic Synthesis | Year: 2010

As steric repulsion, the electronic effect of catalysts also plays a crucial role in asymmetric catalysis. The influence of the electronic effect of catalysts on the enantioselectivity in asymmetric catalysis, including metal-chiral ligand complex and organocatalyst systems, was reviewed. The applicability and complexity of the influence were discussed. Rationally tuning the electronic effect of catalysts can indeed improve enantioselectivity. It is one of the important pathways to achieve the best stereoselectivity in asymmetric catalysis. © 2010 Bentham Science Publishers Ltd.


Patent
Beijing University of Chemical Technology | Date: 2012-12-24

A high-strength high-modulus polyimide fiber and its preparation method pertain to the technical field of high-performance organic fiber. This fiber includes the polyimide (PI) fiber made from 3,3,4,4-biphenyl tetracarboxylic diandhydride (BPDA), p-phenylenediamine (pPDA) and 2-(4-aminophenyl)-1H-benzimidazol-5-amine (BIA), wherein the molar ratio between PPDA and BIA is 1:103:1. During the synthesis, other diamine and diandhydride monomers may also be added. In the preparation process, the gradient temperature reaction method and one-step continuous preparation method are adopted, the synthesis and processing difficulty caused by the increase of the content of BIA is overcome, the problem of poor uniformity and stability of fiber is solved and PI fiber with high strength and high modulus is obtained. Its strength may reach 4.5 GPa and modulus may reach 201 GPa. Moreover, the sources of the raw materials are extensive, the spinning process is continuous, the cost is low, the efficiency is high and industrial production may be realized.


Yang X.,Beijing Jiaotong University | Ning B.,Beijing Jiaotong University | Li X.,Beijing University of Chemical Technology | Tang T.,Beijing Jiaotong University
IEEE Transactions on Intelligent Transportation Systems | Year: 2014

The train timetable optimization problem in subway systems is to determine arrival and departure times for trains at stations so that the resources can be effectively utilized and the trains can be efficiently operated. Because the energy saving and the service quality are paid more attention, this paper proposes a timetable optimization model to increase the utilization of regenerative energy and, simultaneously, to shorten the passenger waiting time. First, we formulate a two-objective integer programming model with headway time and dwell time control. Second, we design a genetic algorithm with binary encoding to find the optimal solution. Finally, we conduct numerical examples based on the operation data from the Beijing Yizhuang subway line of China. The results illustrate that the proposed model can save energy by 8.86% and reduce passenger waiting time by 3.22% in comparison with the current timetable. © 2000-2011 IEEE.


Patent
Beijing University of Chemical Technology | Date: 2010-05-27

A supported noble metal catalyst and a process for preparing the same in situ are provided. Hexamethylenetetramine, a soluble divalent metal salt solution, a Al


Patent
Beijing University of Chemical Technology | Date: 2010-01-12

The present invention discloses a preparation method of carbon nanotube by decomposing the polymer with hydrotalcite as a catalyst, which belongs to the field of preparation technology of carbon nanotube (CNT). The technical solution of the present invention are as below: firstly, the hydrotalcite with the particle size at nanometer or sub-micron level is prepared, and then is added into the polymer. After the calcination process at high temperature and a treatment with acid, the nano-scale CNT can be obtained. The CNTs prepared by the method supplied in this invention not only have the advantages including high yield, uniform diameter, few structural defects, low impurity content, low cost and simple preparation process, which is suitable for large-scale industrial production, but also can solve the problem of recirculation of waste plastics and utilization of the resource.


« Obama Administration proposes $4B to accelerate development and adoption of autonomous vehicles; policy update | Main | Mammoet switches Dutch operations to Shell GTL fuel » Researchers at the University of Delaware, with a colleague at the Beijing University of Chemical Technology, have developed a composite catalyst—nickel nanoparticles supported on nitrogen-doped carbon nanotubes—that exhibits hydrogen oxidation activity in alkaline electrolyte similar to platinum-group metals. An open access paper on their work is published in the journal Nature Communications. Although nitrogen-doped carbon nanotubes are a very poor hydrogen oxidation catalyst, as a support, they increase the catalytic performance of nickel nanoparticles by a factor of 33 (mass activity) or 21 (exchange current density) relative to unsupported nickel nanoparticles, the researchers reported. Owing to its high activity and low cost, the catalyst shows significant potential for use in low-cost, high-performance fuel cells, the team suggested. Polymer electrolyte membrane (PEM) fuel cells are based on two half-cell reactions: hydrogen oxidation reaction (HOR) at the anode and oxygen reduction reaction (ORR) at the cathode. Pt is the most active catalyst for both HOR and ORR; the high price of the metal (~$50 g−1) has hindered fuel cell commercialization. This, in turn, has compelled engineers to (1) work to reduce the platinum loading in the membrane assemblies and (2) find alternate, lower-cost catalysts that offer comparable performance to platinum. Although the various efforts have managed to reduce the total content of platinum-group metals (PGMs) in the state-of-the-art proton exchange membrane fuel cell (PEMFC) stacks, more than 0.137  g Pt kW−1 is still needed, the University of Delaware team said. One promising approach to reduce the cost of fuel cells is to switch the operating environment from an acidic to a basic one (that is, a hydroxide exchange membrane fuel cell, HEMFC), thus opening up the possibility of using PGM-free catalysts and other cheaper components. For the cathode of the HEMFC, some PGM-free and metal-free ORR catalysts have been developed that show comparable activity to Pt in alkaline media. However, for the anode side, only a few PGMs (for example, Pt, Ir and Pd) show adequate activity. The HOR catalyzed by Pt is very fast in acidic conditions so that a very low loading of the Pt catalyst could be used relative to the cathode side in PEMFCs. However, the HOR activities of PGMs are ~100 times slower in alkaline solutions. As a result, a much higher loading of the HOR catalyst is required (0.4  mg Pt  cm−2 in a HEMFC compared with 0.03  mg Pt  cm−2 in a PEMFC) to achieve similar performance. Thus, it is highly desirable to develop PGM-free anode catalysts for the HOR in alkaline electrolyte. Unlike its reverse reaction (hydrogen evolution reaction, HER), only a few PGM-free HOR catalysts have been reported. One possibility is to use Raney Ni as the HOR catalyst in liquid alkaline fuel cells. However, it is functional only under very high alkalinity (6 M KOH) while the activity remains low. It is not catalytically active for a HEMFC, which can be mimicked as 0.1–1 M KOH. Efforts have been made to improve the HOR activity of the Ni-based catalyst in the last decade. Ni alloys, such as NiMo and NiTi, have been shown to enhance the HOR activity. Our recent work has also shown that electrochemically deposited NiCoMo on an Au substrate has a high HOR activity. Zhuang and co-workers decorated Ni particles with CrOx to weaken the Ni–O bond and stabilize the Ni catalysts. A HEMFC incorporating this PGM-free catalyst has been fabricated, and it exhibits a peak power density of 50  mW  cm−2. Although the power density is still low (compared with the peak power density of more than 1,000  mW  cm−2 for PEMFCs), it demonstrates the possibility to fabricate low-cost PGM-free fuel cells. However, their activities are still incomparable with PGM-based catalysts. In the Nature Communications study, the team synthesized Ni nanoparticles supported on N-doped carbon nanotubes (Ni/N-CNT) using a wet chemical method. The nanotubes are not only the support for the Ni nanoparticles, but also a promoter for the catalytic activity. Using density functional theory (DFT) calculations to understand the interaction between the Ni nanoparticle and the N-CNT support, the team found that, when nitrogen dopants are present at the edge of the nanoparticle, the Ni nanoparticle is stabilized on the support and locally activated for the HOR because of modulation of the Ni d-orbitals. The experimental work was supported by the ARPA-E program of the US Department of Energy under Award Number DE-AR0000009. The computational work was financially supported by the Catalysis Center for Energy Innovation, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001004. Stephen Giles was supported by a fellowship from the University of Delaware Energy Institute. The research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.


News Article
Site: www.materialstoday.com

A new study on halloysite clay tubes has shown their potential as a safe natural biocompatible nanomaterial that is abundantly and cheaply available and therefore able to be scaled-up for production, and which also does no harm to the environment. Composite organic–inorganic halloysite nanotubes are known to have advantages over carbon or metal oxides nanotubes, and able to store and release functional agents such as antioxidants, anticorrosion agents, flame-retardant agents, drugs or proteins in a controllable way, offering promise in drug delivery, antimicrobial materials, self-healing polymeric composites, and also in regenerative medicine. In new research published in Advanced Materials [Lvov et al. Adv. Mater. (2015) DOI: 10.1002/adma.201502341], a team from Kazan Federal University in Tatarstan and Beijing University of Chemical Technology, pioneers in the field of natural clay nanotube composites, demonstrated how the nanotubes form a kind of ceramic “skeleton” in the bulk polymers, improving the composite strength as well as adhesivity. These skeletons can be loaded with active compounds to offer extra functionality for polymers in the same way real bones are loaded with marrow. Halloysite clay nanotubes have an inner diameter of 10–20 nm, outer diameter of 40–70 nm and a length of 500–1500 nm, with the inside being composed of Al2O3 and externally mainly SiO2. The inner lumen of halloysite can be altered by etching to 20–30% of the volume of the tube, and as a nanocontainer can be used for loading and sustained release of chemical agents. Halloysite tubes can encase enzymes to provide longer storage, higher temperature and more functionality, and the opening of the tube also allows for delivery of small substrate molecules into the tube interior for biocatalysis. The team had first looked to formulate new paint composites with antifouling properties to prevent the attachment of shells and other sea micro-organisms to the body of ships, which slows them down. Since biocides would be washed off, they encapsulated them in clay nanotubes added to paint to provide very slow and sustained release. This breakthrough led to the concept of smart functional nano-composites that are doped with 4–5% of clay nanotubes loaded with the chemical inhibitors. One problem is that the halloysite clay tubes are not biodegradable, due to there being no biological mechanisms that can degrade them in the body. Although they also can’t be injected intravenously, using them for external medical treatment based on the sustained release of encapsulated drugs offers much promise, so the team now intends to explore the potential for biocomposites in this way.


Deng M.,Beijing University of Chemical Technology | Tu N.,Beijing University of Chemical Technology | Bai F.,Henan University | Wang L.,Beijing University of Chemical Technology
Chemistry of Materials | Year: 2012

A facile and general strategy was successfully developed for the surface modification of kinds of hydrophobic inorganic nanomaterials with various chemical compositions, shapes, and sizes. Via this ultrasonication assistant encapsulation technology, these hydrophobic inorganic nanocrystals were successfully encapsulated into the carboxylated phospholipids and polymers micelles with one particle per micelle. The surface modified nanocrystals were characterized by transmission electron microscopy (TEM), Fourier-transform infrared (FTIR), and thermogravimetric analysis (TGA). After encapsulation, the particle size, shape, and optical and magnetic properties were effectively retained. These functionalized nanocrystals are highly water-stable and biocompatible. After being bioconjugated with the antibodies, the functionalized quantum dots (QDs) have been successfully used as biolabels for targeted cell fluorescence imaging. © 2012 American Chemical Society.


Yue T.,China University of Petroleum - East China | Yue T.,Beijing University of Chemical Technology | Zhang X.,Beijing University of Chemical Technology
Soft Matter | Year: 2013

In this work we systematically investigate the pathways of the interaction between elastic vesicles and lipid membranes with the aid of computer simulation techniques. Different vesicle responses to the vesicle-membrane adhesion, including vesicle fusion, vesicle hemi-fusion, vesicle adhesion, vesicle endocytosis and vesicle rupture, are observed from our simulations. We also investigate how the pathways of vesicle-membrane interaction depend on the adhesion strength, and the membrane and vesicle properties. © The Royal Society of Chemistry 2013.


Liu H.,Beijing University of Chemical Technology | Zhou H.,Japan National Institute of Advanced Industrial Science and Technology | Chen L.,Beijing University of Chemical Technology | Tang Z.,Beijing University of Chemical Technology | Yang W.,Beijing University of Chemical Technology
Journal of Power Sources | Year: 2011

A well defined nano-structured material, NaV6O15 nanorods, was synthesized by a facile low temperature hydrothermal method. It can perform well as the cathode material of rechargeable sodium batteries. It was found that the NaV6O15 nanorods exhibited stable sodium-ion insertion/deinsertion reversibility and delivered 142 mAh g -1 sodium ions when worked at a current density of 0.02 A g -1. In galvanostatic cycling test, a specific discharge capacity of around 75 mAh g-1 could be obtained after 30 cycles under 0.05 A g-1 current density. Concerned to its good electrochemical performance for reversible delivery of sodium ions, it is thus expected that NaV6O15 may be used as cathode material for rechargeable sodium batteries with highly environmental friendship and low cost. © 2010 Elsevier B.V.


Fang C.,Beijing University of Chemical Technology | Wang J.,Beijing University of Chemical Technology | Zhang T.,Beijing Institute of Ancient Architecture
Applied Surface Science | Year: 2014

The effects of deposition to carbon fibers surfaces with mixture of functionalized multi-walled carbon fibers (MWCNTs) and sizing agent were investigated. Relationships between CNTs and sizing agent were studied with Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectroscopy (XPS) and Ubbelohde viscometer. The results revealed that CNTs could react with sizing agent at 120°C, and optimal reaction occurs when mass ratio was about 1:20. Then, carbon fibers were immersed in mixed aqueous suspension of CNTs and sizing agent with the above ratio dispersed by ultrasonication. According to scanning electron microscope (SEM) observations, fibers surfaces were coated with CNTs and sizing agent. The static contact angle tests indicated wetting performance between fibers and epoxy resin were improved after deposited procedures. Interlaminar shear strength was increased by 67.01% for fibers/epoxy resin composites after mixture deposited process. Moreover, the tensile strength of single fibers after depositing showed a slightly increase compared with that of fibers without depositing layer. © 2014 Elsevier B.V. All rights reserved.


Xiang Z.,State Key Laboratory of Organic Inorganic Composites | Peng X.,Beijing University of Chemical Technology | Cheng X.,State Key Laboratory of Organic Inorganic Composites | Li X.,Beijing University of Chemical Technology | Cao D.,State Key Laboratory of Organic Inorganic Composites
Journal of Physical Chemistry C | Year: 2011

Effectively separating CO 2 from the natural gas, which is one of alternative "friendly" fuels, is a very important issue. A hybrid material CNT@Cu 3(BTC) 2 has been prepared to separate CO 2 from the CO 2/CH 4 mixture. For comparison of separation efficiency, a series of representative metal-organic frameworks (MOF-177, UMCM-1, ZIF-8, MIL-53 (Al), and Cu 3(BTC) 2) have also been synthesized by the solvothermal method. Adsorption isotherms of CO 2 and CH 4 pure gases are measured by Hiden Isochema Intelligent Gravimetric Analyzer (IGA-003). The dual-site Langmuir-Freundlich (DSLF)-based ideal adsorption solution theory (IAST) is used to predict adsorption of each component in the CO 2/CH 4 mixture. The IAST-predicted results show that the hybrid material CNT@Cu 3(BTC) 2 exhibits the greatest selectivity among the six materials, and its selectivity keeps in the range of 5.5 to 7.0 for equimolar CO 2/CH 4 mixture at 1 < p < 20 bar, which is higher than activated carbons. Moreover, the selectivity of CNT@Cu 3(BTC) 2 for the CO 2/CH 4 mixture keeps almost no change with the composition of CH 4, which is one of the excellent properties as a promising separation material. In short, this hybrid material CNT@Cu 3(BTC) 2 shows great potential in separation and purification of CO 2 from various CO 2/CH 4 mixtures by adsorptive processes in important industrial systems. © 2011 American Chemical Society.


Liu H.,Beijing University of Chemical Technology | Yang W.,Beijing University of Chemical Technology
Energy and Environmental Science | Year: 2011

A novel hybrid material constructed from 2D graphene nanosheets (GNS) and 1D vanadium pentoxide (V 2O 5) nanowires was successfully fabricated via a very simple green approach. The ultralong V 2O 5 single crystalline nanowires were supported on the transparent GNS substrate and exhibited excellent electrochemical properties. When used as a cathode material of lithium-ion batteries, the composite material revealed high initial discharge capacities and exceptional rate capacities. For instance, at the lower current density of 50 mA g -1, an initial specific discharge capacity of 412 mAh g -1 could be achieved; when the current density was increased to 1600 mA g -1, the composite still delivered 316 mAh g -1 lithium ions. The good performance of the composite resulted from its unique nano-scaled V 2O 5 wires with short diffusion pathway for lithium ions and the excellent electrical conductivity of GNS. Note that the fabrication approach in the present work is environmental friendly without any strong reduction and oxidation reagents, or causing the generation of toxic gas during the fabrication process. We believe that this green approach may open up the possibility of fabricating more novel structured graphene-based functional materials. © 2011 The Royal Society of Chemistry.


Zhang J.,Beijing University of Chemical Technology | Xia Y.,Beijing Institute of Technology | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne | Shi P.,University of Adelaide
IEEE Transactions on Control Systems Technology | Year: 2013

This brief is concerned with the networked predictive control and stability analysis for networked control systems (NCSs) with time-varying network communication delay. By taking the full advantage of the packet-based transmission in NCSs, a state-based networked predictive control approach is proposed to actively compensate the network communication delay. Based on switched system approach, stability analysis result is also established via the average dwell time technique. Finally, the effectiveness of the proposed method is illustrated by a practical experiment. © 1993-2012 IEEE.


Wu Y.,Tsinghua University | Wang D.,Tsinghua University | Zhou G.,Beijing University of Chemical Technology | Yu R.,Tsinghua University | And 2 more authors.
Journal of the American Chemical Society | Year: 2014

We have developed a priority-related chemical etching method to transfer the starting Pt-Ni polyhedron to a nanoframe. Utilizing the lower electronegativity of Ni in comparison to Au atoms, in conjunction with the galvanic replacement of catalytically active Au to Ni tops, a unique Au island on a Pt-Ni trimetallic nanoframe is achieved. The design strategy is based on the structural priority mechanism of multimetallic nanocrystals during the synthesis and thus can be generalized to other analogous metal-bimetallic nanocrystal combinations (such as Pd and Cu islands on Pt-Ni nanoframes), which is expected to pave the way for the future development of efficient catalysts. © 2014 American Chemical Society.


Jing X.,Beijing University of Chemical Technology | Zheng D.,Beijing University of Chemical Technology
Energy Conversion and Management | Year: 2014

To recover mid-low grade heat, a new power/cooling cogeneration cycle was proposed by combining the Kalina cycle and the double-effect ammonia-water absorption refrigeration (DAAR) cycle together, and the equivalent heat-to-power and exergy efficiencies of the cogeneration cycle reached 41.18% and 58.00%, respectively. To determine the effect of cycle coupling-configuration on energy cascade utilization for the new cycle, the cycle coupling-configuration of the Kalina and DAAR cycles were first analyzed, after which the cycle coupling-configuration of the new cycle was analyzed. Analysis results showed that the cycle coupling-configuration of the new cycle enhanced the energy cascade utilization. Furthermore, the energy efficiency boosting mechanism of the new cycle was elucidated. © 2013 Elsevier Ltd. All rights reserved.


Yan D.,Beijing University of Chemical Technology | Evans D.G.,Beijing University of Chemical Technology
Materials Horizons | Year: 2014

Tuning and controlling the luminescent properties of molecular materials by changing the orientation and arrangement of the fluorophores within a solid has played an important role in realizing multi-color emission. The formation of polymorphs and multi-component molecular solids have attracted considerable interest as new ways of achieving controllable luminescence and other photophysical properties for application in the next generation of photofunctional materials. In this article, recent advances in the synthesis of fluorescent polymorphs and multi-component materials and potential photo-related applications of the resulting materials are described. We first review the methods of preparation of polymorphs with tunable static luminescence, and the switching of the dynamic luminescence between polymorphs for potential sensor applications is also introduced. Attention is then focused on the supramolecular design (making use of hydrogen bonding and halogen bonding interactions) and methods of fabrication of multi-component molecular solids, and their color-tunable fluorescence and phosphorescence together with their stimuli-responsive properties for use as sensors. The use of density functional theory to study intramolecular and intermolecular energy transfer as well as the electronic structures of multi-component molecular solids is also outlined. Finally, we briefly discuss perspectives for the further development of these luminescent molecular solid-state materials. © The Royal Society of Chemistry.


Guan W.,Beijing University of Chemical Technology | Qiu Z.,Beijing University of Chemical Technology
Industrial and Engineering Chemistry Research | Year: 2012

Biodegradable poly(ε-caprolactone) (PCL) and octavinyl-polyhedral oligomeric silsesquioxanes (ovi-POSS) nanocomposites were prepared at low ovi-POSS loadings via a solution casting method in this work. Scanning electron microscopy observation reveals not only the fine dispersion but also the crystallization of ovi-POSS in the PCL matrix. The overall isothermal melt crystallization kinetics, spherulitic morphology, crystal structure, and dynamic mechanical properties of neat PCL and its nanocomposites were studied with various techniques. The presence of ovi-POSS has enhanced the overall isothermal melt crystallization rates of PCL in the nanocomposites; however, the crystallization mechanism and crystal structure of PCL remain unchanged despite the ovi-POSS loading. In addition, the storage modulus of the nanocomposites has been enhanced significantly relative to neat PCL, while the glass transition temperature varies slightly irrespective of the presence of ovi-POSS. © 2012 American Chemical Society.


Ma X.,Beijing University of Chemical Technology | Lei M.,Beijing University of Chemical Technology
Progress in Chemistry | Year: 2013

Dinitrogen fixation activated by organometallic complexes under mild conditions is one of hot fields in modern industry, which try to convert abound but quite inert dinitrogen into ammonia or other nitrogenous compounds. In this review, coordination modes of N2 molecule with transition-metal complexes are classified, and the main factors such as steric effect and electronic effect on the dinitrogen activation and functionalization promoted by dinuclear transition-metal complexes are surveyed. This review attempts to summarize recent experimental and theoretical studies concerning the reactivity patterns of dinitrogen with binuclear transition-metal complexes in the dinitrogen cleavage and functionalization as well as the CO/CO2 induced N2 activation. The prospects of dinitrogen fixation activated by transition-metal complexes is presented, which is hoped to assist chemists in guiding research in the future.


Luo B.,CAS National Center for Nanoscience and Technology | Fang Y.,CAS National Center for Nanoscience and Technology | Wang B.,CAS National Center for Nanoscience and Technology | Zhou J.,Beijing University of Chemical Technology | And 2 more authors.
Energy and Environmental Science | Year: 2012

A novel porous nanoarchitecture composed of 2D graphene-SnS 2 (G-SnS 2) units is developed via a two-step approach in this work. The special structure endows the high-rate transportation of electrolyte ions and electrons throughout the electrode matrix, resulting in remarkable electrochemical performance when it was used as anode in lithium ion batteries. © 2011 The Royal Society of Chemistry.


He K.,Beijing University of Chemical Technology | He K.,City University of Hong Kong | Yu L.,Beijing University of Chemical Technology | Lai K.K.,City University of Hong Kong
Energy | Year: 2012

To improve the forecasting accuracy of crude oil price with deeper understanding of the market microstructure, this paper proposes a wavelet decomposed ensemble model. The proposed model follows the Heterogeneous Market Hypothesis that assumes the unstationarity and dynamic changing nature of the underlying market structure and introduces the wavelet analysis to analyze the dynamic underlying Data Generating Process at finer time scale domain. The simple averaging based ensemble model is introduced to reduce the estimation bias resulting from the use of different wavelet families by deriving market consensus view. The ensemble members are selected dynamically based on their in-sample performance among forecast matrices based on different wavelet families. Results from empirical studies show the superior performance of the proposed algorithm against the benchmark models, in terms of both level and directional predictive accuracy. The proposed model can effectively extract and model the time varying heterogeneous market microstructure, whose accurate characterization results in further improvement in market analysis and predictability. © 2012 Elsevier Ltd.


Sun Y.,CAS Beijing National Laboratory for Molecular | Sun Y.,Beijing University of Chemical Technology | Cui C.,CAS Beijing National Laboratory for Molecular | Wang H.,Beijing University of Chemical Technology | Li Y.,CAS Beijing National Laboratory for Molecular
Advanced Energy Materials | Year: 2012

The photovoltaic properties of poly(3-pentylthiophene) (P3PT) are studied. P3PT-based polymer solar cells with IC 60BA and IC 70BA as acceptors demonstrate high power conversion efficiencies of 4.50% and 5.44% with high open-circuit voltages of 0.89 and 0.88 V, respectively. These devices benefit from the high-lying LUMO energy levels of IC 60BA and IC 70BA. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Su S.,Beijing Jiaotong University | Li X.,Beijing Jiaotong University | Tang T.,Beijing Jiaotong University | Gao Z.,Beijing University of Chemical Technology
IEEE Transactions on Intelligent Transportation Systems | Year: 2013

Given rising energy prices and environmental concerns, train energy-efficient operation techniques are paid more attention as one of the effective methods to reduce operation costs and energy consumption. Generally speaking, the energy-efficient operation technique includes two levels, which optimize the timetable and the speed profiles among successive stations, respectively. To achieve better performance, this paper proposes to optimize the integrated timetable, which includes both the timetable and the speed profiles. First, we provide an analytical formulation to calculate the optimal speed profile with fixed trip time for each section. Second, we design a numerical algorithm to distribute the total trip time among different sections and prove the optimality of the distribution algorithm. Furthermore, we extend the algorithm to generate the integrated timetable. Finally, we present some numerical examples based on the operation data from the Beijing Yizhuang subway line. The simulation results show that energy reduction for the entire route is 14.5%. The computation time for finding the optimal solution is 0.15 s, which implies that the algorithm is fast enough to be used in the automatic train operation (ATO) system for real-time control. © 2011 IEEE.


Bin G.F.,Beijing University of Chemical Technology | Bin G.F.,Hunan University of Science and Technology | Gao J.J.,Beijing University of Chemical Technology | Li X.J.,Hunan University of Science and Technology | Dhillon B.S.,University of Ottawa
Mechanical Systems and Signal Processing | Year: 2012

After analyzing the shortcomings of current feature extraction and fault diagnosis technologies, a new approach based on wavelet packet decomposition (WPD) and empirical mode decomposition (EMD) are combined to extract fault feature frequency and neural network for rotating machinery early fault diagnosis is proposed. Acquisition signals with fault frequency feature are decomposed into a series of narrow bandwidth using WPD method for de-noising, then, the intrinsic mode functions (IMFs), which usually denoted the features of corresponding frequency bandwidth can be obtained by applying EMD method. Thus, the component of IMF with signal feature can be separated from all IMFs and the energy moment of IMFs is proposed as eigenvector to effectively express the failure feature. The classical three layers BP neural network model taking the fault feature frequency as target input of neural network, the 5 spectral bandwidth energy of vibration signal spectrum as characteristic parameter, and the 10 types of representative rotor fault as output can be established to identify the fault pattern of a machine. Lastly, the fault identification model of rotating machinery with rotor lateral early crack based on BP neural network is taken as an example. The results show that the proposed method can effectively get the signal feature to diagnose the occurrence of early fault of rotating machinery. © 2011 Elsevier Ltd. All rights reserved.


Lin Y.,Beijing University of Chemical Technology | Wang G.,Beijing University of Chemical Technology
Recent Patents on Nanotechnology | Year: 2012

Layered double hydroxides (LDHs) can be incorporated in a variety of composites with different structures and properties. The choice of synthesis method is a very important factor in achieving LDHs with the desired structure and properties. A method involving separate nucleation and aging steps (SNAS), layer-by-layer self-assembly methods, in situ surface synthesis methods and a clean method have been developed in recent years. LDHs with different structure and properties have been synthesized using these different methods. Applications of these LDHs include as environmentally-friendly functional additives in cement and asphalt, as new catalytic materials, as novel optical materials, in biosensors and as superhydrophobic materials. This paper summarizes recent patents describing methods for synthesizing LDHs with tailored structures and properties. © 2012 Bentham Science Publishers.


Zhang Y.,Peking University | Ma H.-L.,Beijing University of Chemical Technology | Zhang Q.,Peking University | Peng J.,Peking University | And 3 more authors.
Journal of Materials Chemistry | Year: 2012

We demonstrate a facile and environmentally friendly approach to prepare well-dispersed graphene sheets by γ-ray induced reduction of a graphene oxide (GO) suspension in N,N-dimethyl formamide (DMF) at room temperature. GO is reduced by the electrons generated from the radiolysis of DMF under γ-ray irradiation. The reduced GO by γ-ray irradiation (G-RGO) can be re-dispersed in many organic solvents, and the resulting suspensions are stable for two weeks due to the stabilization of N(CH 3) 2 + groups on G-RGO. Additionally, G-RGO is efficient in improving the conductivity of polystyrene (PS). Its PS nanocomposites exhibit a sharp transition from electrically insulating to conducting with a low percolation threshold of 0.24 vol% and a high electrical conductivity of 45 S m -1 is obtained with only 2.3 vol% of G-RGO. The superior electrical conductivity is attributed to the uniform dispersion of the G-RGO sheets in the PS matrix. © 2012 The Royal Society of Chemistry.


Li H.,Beijing University of Chemical Technology | Yan S.,Beijing University of Chemical Technology
Macromolecules | Year: 2011

The dependence of properties on the structure and morphology of semicrystalline polymers offers an effective way to tailor the properties of these materials through crystal engineering. For purposeful control of the structure and morphology, and therefore the physical and mechanical properties, a full understanding of the crystallization habits of polymers under different environments and conditions is essential. This has stimulated a mass of research work on polymer crystallization. Considering that these materials are frequently in contact with some kinds of solid surfaces in a variety of applications, surfaceinduced crystallization of polymers has attracted considerable attention during the past decades. This Perspective provides the context as to how the solid surface influences the crystallization behavior of polymers and what kinds of unique crystal structure and morphology of the polymers can be fabricated. We hope that this will afford useful information for polymer processing in different application fields and promote the technical development of new methods of preparation of polymeric materials for advanced applications. © 2011 American Chemical Society.


Wang H.,Beijing University of Chemical Technology | Qiu Z.,Beijing University of Chemical Technology
Thermochimica Acta | Year: 2011

Crystallization behaviors of biodegradable poly(l-lactic acid) (PLLA)/graphene oxide (GO) nanocomposites at different GO loadings from the amorphous state were investigated in detail in this work. During the nonisothermal cold crystallization, the crystallization peak temperature of PLLA shifts to low temperature range in the nanocomposites with increasing the GO loading relative to neat PLLA despite heating rate; moreover, the overall nonisothermal cold crystallization has been accelerated with increasing heating rate for both neat PLLA and its nanocomposites. In addition, the variations of crystallization enthalpy of PLLA during isothermal and nonisothermal cold crystallization processes were also discussed. Relative to neat PLLA, the overall isothermal cold crystallization rate of PLLA is increased with increasing the GO loading in the nanocomposites despite crystallization temperature. The crystallization rate becomes faster with increasing crystallization temperature, while the crystallization mechanism and crystal structure remain unchanged for both neat PLLA and its nanocomposites. © 2011 Elsevier B.V. All rights reserved.


Yue T.,Beijing University of Chemical Technology | Zhang X.,Beijing University of Chemical Technology
Soft Matter | Year: 2011

The cytotoxicity of nanoparticles (NPs) and their potential applications in drug delivery and intracellular imaging have been extensively investigated, and a thorough molecular understanding of how cellular membrane responds to the introduction of NPs is essential for biomaterial design. In this work, N-varied dissipative particle dynamics (DPD) simulation is applied to investigate how a membrane responds to adsorption of ligand-coated NP. Depending on the membrane surface tension, ligand area density and NP size, four kinds of membrane responses are observed: membrane rupture, NP adhesion, NP penetration, and receptor-mediated endocytosis. While endocytosis provides an effective pathway for cellular uptake of NPs, the NP penetration and NP-induced membrane rupture are related to cytotoxicity. These results support the recent experimental reports that NPs have a Janus face for their biomedical applications: serving as carriers for the transmembrane transport of drug and causing cytotoxicity. © 2011 The Royal Society of Chemistry.


Zheng D.,Beijing University of Chemical Technology | Jing X.,Beijing University of Chemical Technology
Energy | Year: 2013

A new concept, which is named as a chemical amplifier or CHC (chemical heat converter), was proposed to analyze the heat conversion cycle systems and its application in system innovation. This new concept primarily comprises a pair of reversible reactions, an endothermic and an exothermic reaction, which occur in the liquid-gas or solid-gas phase. By introducing the heat flux of high-temperature input and low-temperature output to meet the reactions, the CHC cycle produces two types of work capacities, wA* and wR*, which respectively employ the working fluid for the heat engine and the heat pump as carriers. These wok capacities can be used either separately or together when coupling with a heat engine sub-cycle and/or a heat pump sub-cycle, and the different heat conversion mechanisms in five kinds of heat conversion configurations were revealed using the proposed concept. And then to show a full application example of the CHC concept, an absorption power/cooling cogeneration cycle with working fluid difluoromethane and N,N-dimethylformamide was analyzed. This research exhibited that both the benefits of the increasing of expansion work in the heat engine sub-cycle and the reduction of work consumption for compression in the heat pump sub-cycle can be obtained through the work abilities output by the CHC which is driven by mid-low grade heat. © 2013 Elsevier Ltd.


Xiong C.,Beijing University of Chemical Technology | Tu W.,Beijing University of Chemical Technology
European Journal of Inorganic Chemistry | Year: 2014

Spherical boron nitride nanoparticles with good aqueous dispersibility were synthesized by means of a direct reaction of boric acid and ammonium chloride. The X-ray powder diffraction pattern confirmed the hexagonal BN structure (h-BN) with d002 = 3.33 Å. Copper oxide (CuO) was found to affect the morphology and surface properties of the BN nanoparticles. The average size of the spherical h-BN nanoparticles synthesized with the addition of CuO was about 30 nm. The h-BN had a high surface area of 75 m2 g-1 and a mesoporous volume of 0.32 cm3 g-1. The presence of CuO during the synthesis could enhance the surface electronegativity of the h-BN nanoparticles and change their isoelectric point to pH = 2.7. The zeta potentials of BN were between -30 and -50 mV in the pH range of 4-10. The h-BN nanoparticles were well dispersed and stable in aqueous solution. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Su Z.,Beijing University of Chemical Technology | Ding J.,Beijing University of Chemical Technology | Wei G.,University of Bremen
RSC Advances | Year: 2014

The increased interest in electrospinning (ES) and its recent applications for fabrication of sensors and biosensors is driven by the development of materials science and nanotechnology. Compared with other fabrication processes, ES is versatile and superior for producing and constructing ordered and complex nanofibrous materials. The introduction of carbon nanotubes (CNTs) and metallic nanoparticles (MNPs) into the electrospun polymeric nanofibers (NFs) extends their potential applications as electrical and electrochemical sensors and biosensors. In this review, we summarize the recent progress using the ES technique to fabricate different polymeric NFs doped with CNTs and various MNPs, as well as their applications for detecting alcohols, H2S, H2, glucose, H2O2, and urea. The fabrication, intrinsic fundamentals, and optimization design of the sensors were introduced and discussed in detail. In addition, the improvements and challenges of ES techniques were mentioned. It is expected that this review will promote development in the ES field and guide studies to create nanofibrous hybrid materials as novel sensors and biosensors. This journal is © the Partner Organisations 2014.


Yu J.,Beijing University of Chemical Technology | Qiu Z.,Beijing University of Chemical Technology
Thermochimica Acta | Year: 2011

Biodegradable poly(l-lactide) (PLLA)/octavinyl-polyhedral oligomeric silsesquioxanes (ovi-POSS) nanocomposites were prepared via solution and casting method at low loadings of ovi-POSS in this work. Effect of ovi-POSS on the crystallization behavior, spherulitic morphology, crystal structure, and thermal stability of PLLA in the nanocomposites was investigated in detail. It is found that both nonisothermal melt and cold crystallization of PLLA in the nanocomposites are enhanced by the presence of ovi-POSS. In addition, the enhancement becomes more significant with the increase of POSS content to 1 wt%. For isothermal melt crystallization, the overall crystallization rates are faster in the PLLA/ovi-POSS nanocomposites than those in neat PLLA and improved with increasing the ovi-POSS loading; however, the crystallization mechanism and crystal structure of PLLA remain unchanged despite the presence of ovi-POSS. The thermal stability of PLLA in the PLLA/ovi-POSS nanocomposites is reduced slightly relative to neat PLLA. © 2011 Elsevier B.V.


Sun S.,Beijing University of Chemical Technology | Li J.,Beijing University of Chemical Technology
Swarm and Evolutionary Computation | Year: 2014

Particle swarm optimization (PSO) is a powerful stochastic evolutionary algorithm based on swarm intelligence. However, the canonical PSO is easily and prematurely trapped in the local optima due to loss of its diversity. Although some improved algorithms retain the diversity, their speeds of convergence become slow. Meanwhile, PSO could only find out the global optimum in a small search interval, which greatly limits its applications to many practical engineering problems. In this study, the two-swarm cooperative particle swarm optimization (TCPSO) is presented. TCPSO can not only catch the global optimum in a large search space such as 2×1010, but also obtains a good balance between the swarm diversity and the convergence speed. It uses two particle swarms, the slave swarm and the master swarm with the clear division of their works. The former particles are updated without using the current velocities, the dimension of each particle learns from the same dimension of its neighboring particle instead of the best-so-far position. These features make the particles of the slave swarm concentrate toward the local optimum, thus accelerating the convergence. The latter particles are updated based on the former particles. And the equation in which the velocities of its particles are updated uses a large inertia weight. The feature of the master swarm keeps its diversity invariant. The experiments on TCPSO through 14 test functions showed that it significantly improves the performance of PSO and possesses the best performance among all the examined problems no matter multimodal or unimodal functions. © 2014 Elsevier Inc. © 2013ElsevierB.V.Allrightsreserved.


Xia C.,Beijing University of Chemical Technology | Xia C.,University of Minnesota | Zhang J.,University of Minnesota | Zhang W.,Beijing University of Chemical Technology | Hu B.,University of Minnesota
Biotechnology for Biofuels | Year: 2011

The recent energy crisis has triggered significant attention on the microbial synthesis of lipids, which comprise the raw material for biodiesel production. Microbial oil accumulation with filamentous fungi has great potential because filamentous fungi can form pellets during cell growth, and these pellets are much easier to harvest from cell broth. This paper focuses on the cell pelletization process of the oleaginous Mucor circinelloides. We have studied the effect of various cultural conditions on pelletized cell growth and lipid accumulation. This study is the first to report that pH adjustment during cell growth plays a key role in pellet formation of M. circinelloides and describes a handy method by which to induce cell pelletization in submerged fungal cultivation. Our study reveals that cell growth and lipid production are not significantly affected by pelletization and that lipid accumulation is triggered at stressed conditions, such as a high carbon-to-nitrogen ratio and high temperature. © 2011 Xia et al; licensee BioMed Central Ltd.


Yin Y.-X.,CAS Beijing National Laboratory for Molecular | Yin Y.-X.,Beijing University of Chemical Technology | Xin S.,CAS Beijing National Laboratory for Molecular | Wan L.-J.,CAS Beijing National Laboratory for Molecular | And 2 more authors.
Journal of Physical Chemistry C | Year: 2011

An optimized nanostructure design of Si-based anode material for high-performance lithium-ion batteries is realized in the form of Si/C nanoporous microspheres. Self-assembled Si/C nanoporous microspheres are synthesized by a programmed method and are investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, N2 adsorption-desorption isotherms, and electrochemical experiments. The programmed synthesis steps involve electrojetting Si nanoparticle-containing sodium alginate aqueous solution followed by calcination, carbon coating, and final etching. The electrospray step is the key step toward the formation of the microspheres in which sodium alginate acts as a dispersant and a carbon precursor for nano-Si particles as well as a coagulant together with Cu2+. The Si/C nanoporous microspheres exhibit remarkably enhanced cycling performance and rate performance compared with nano-Si particles when used as anode materials in lithium-ion batteries. The improved electrochemical performances benefit from the advanced nano/microstructure with proper size, carbon coating, and porosity as well as from the as-formed Cu3Si with good electronic conductivity and surface stability. © 2011 American Chemical Society.


Xie Q.,Beijing University of Chemical Technology | Wei Y.,Beijing University of Chemical Technology | Zhang G.,Chinese Academy of Agricultural Sciences
Separation and Purification Technology | Year: 2010

In order to utilize and control the invasive weed, Flaveria bidentis (L.) Kuntze, bioactive compounds mainly flavonoids from F. bidentis (L.) Kuntze were studied. High-speed counter-current chromatography (HSCCC) was successfully used for the separation of flavonol glycosides from F. bidentis (L.) Kuntze. The two-phase solvent system composed of ethyl acetate-methanol-water (10:0.4:10, v/v) was used for HSCCC. About 400 mg of the crude extract was separated by HSCCC, yielding 3.6 mg of patuletin-3-O-glucoside at a purity of over 97%; 4.4 mg of astragalin (kaempferol-3-O-glucoside) at a purity of over 98% and 4.5 mg of a mixture of hyperoside (quercetin-3-O-galactoside) and 6-methoxykaempferol-3-O-galactoside constituting over 97% of the fraction. The chemical structures were confirmed by MS and 1H, 13C, 1-D TOCSY NMR. © 2010 Elsevier B.V. All rights reserved.


Yue T.,Beijing University of Chemical Technology | Zhang X.,Beijing University of Chemical Technology
Journal of Physical Chemistry B | Year: 2011

The controllable self-assembly of semiflexible homopolymers into regular bundles has received much attention because of its potential importance in various fields, such as the storage of elastic energy, the fabrication of nanostructures, and the formation of the cytoskeleton in living cells. In this article, using computer simulations, we investigate how semiflexible homopolymers anchored on a substrate self-organize into ordered structures, focusing on both the patterns formed and the dynamics of self-assembly. For the self-assembly pattern, four different patterns, including patterns with unclustered polymers, disordered semispherical clusters, highly ordered helical bundles, and parallel bundles, are observed from our simulations. The formation of stable bundles requires semiflexible homopolymers having a sufficient molecule length and intermediate bending stiffness, whereas the formation of the helical structures depends on the balance between the inter-homopolymer attraction and the bending stiffness of homopolymers. Furthermore, the bundle formation reinforces the bending stiffness, and the stiffness is further enhanced by the helical bundling. For the dynamic aspect, both hierarchical bundling and nonhierarchical bundling are observed from our simulations. © 2011 American Chemical Society.


Zhao Y.,Beijing University of Chemical Technology | Qiu Z.,Beijing University of Chemical Technology
Journal of Nanoscience and Nanotechnology | Year: 2012

The effect of low carboxyl-functionalized multi-walled carbon nanotubes (f-MWCNTs) loading on the crystallization behavior of biodegradable poly(butylene adipate) (PBA) was studied with various techniques in this work. For the nonisothermal melt crystallization, f-MWCNTs accelerate the crystallization process of PBA apparently due to the heterogeneous nucleation effect. The Ozawa method fails to describe the nonisothermal crystallization process of neat PBA and its nanocomposite. Isothermal melt crystallization kinetics of neat PBA and its nanocomposite was analyzed by the Avrami equation. The overall isothermal crystallization rate of neat PBA and its nanocomposite increases with increasing crystallization temperature. The addition of f-MWCNTs accelerates the isothermal crystallization of PBA as compared with that of neat PBA at a given crystallization temperature, indicative of the nucleating agent effect of f-MWCNTs; however, the crystallization mechanism does not change. The crystal structure of PBA remains unchanged in the PBA/f-MWCNTs nanocomposite despite the presence of f-MWCNTs. Copyright © 2012 American Scientific Publishers. All rights reserved.


Zhang J.,Beijing University of Chemical Technology | Qiu Z.,Beijing University of Chemical Technology
Industrial and Engineering Chemistry Research | Year: 2011

Biodegradable poly(ε-caprolactone) (PCL)/thermally reduced graphene (TRG) nanocomposites were prepared via a solution mixing method at low TRG loadings in this work. Transmission electron microscopy and high resolution transmission electron microscopy observations reveal that a fine dispersion of TRG has been achieved throughout the PCL matrix. Scanning electron microscopy observation shows not only a nice dispersion of TRG but also a strong interfacial adhesion between TRG and the matrix, as evidenced by the presence of some TRG nanosheets embedded in the matrix. Nonisothermal melt crystallization behavior, isothermal melt crystallization kinetics, spherulitic morphology, and crystal structure of neat PCL and the PCL/TRG nanocomposites were studied in detail with various techniques. The experimental results indicate that both nonisothermal and isothermal melt crystallization of PCL have been enhanced significantly by the presence of TRG in the nanocomposites due to the heterogeneous nucleation effect; however, the crystallization mechanism and crystal structure of PCL do not change. Dynamic mechanical analysis study shows that the storage modulus of the nanocomposites has been greatly improved by about 203% and 292%, respectively, with incorporating only 0.5 and 2.0 wt % TRG at -80 °C as compared with neat PCL. © 2011 American Chemical Society.


Zhang H.-D.,Beijing University of Chemical Technology | Zheng X.-P.,Beijing University of Chemical Technology
Journal of Loss Prevention in the Process Industries | Year: 2012

Utilizing data from official sources, 1632 hazardous chemical accidents (HCAs) occurring in China (2006-2010) were investigated for statistical characteristics. The following results were obtained: (1) Time volatility: The yearly number of HCAs is shown to be almost constant (with a slightly increasing number of fixed facility HCAs); fixed facility and transportation HCAs do not always follow similar patterns at month and hour-level. (2) Location distribution: There are provincial classifications of HCA materials involved in certain types of industries and the potential for HCAs is highly concentrated in urban areas. (3) Fixed facility type versus transportation type: Explosions represent almost half (48.4%) of fixed facility HCAs followed by releases (41.5%) and fires (10.1%); whereas for transportation HCAs, releases account for 79.6%, then explosions (15.1%) and fires (5.3%). As for domino effects, releases were often the cause of subsequent explosions or fires. (4) Injury versus death: In contrast with other industrial accidents, HCAs result in more severe casualties. For explosion and release HCAs in China, the ratio of death to major injury is quite high, with the exception of fire HCAs. (5) Cause: Concerning immediate causes, human factors account for the majority of HCAs followed by equipment deficiency; environment is also a causative factor. Internal corporate management failures and lack of external government supervision (particularly HCAs occurring in illegal corporations) are both root causes in China. (6)Corporate proneness: Majority of HCAs occur in private corporations; as corporations grow, the occurrence of HCAs are shown to decline steadily then level off, following which they are forecasted to increase again in the " aging stages" , all of which can be explained by Corporate Lifecycles Theory. © 2012 Elsevier Ltd.


Wang Q.,Beijing University of Chemical Technology | Gao J.,Beijing University of Chemical Technology
Journal of Loss Prevention in the Process Industries | Year: 2012

Oil transfer stations of PetroChina mostly scatter in Gobi, mountain areas or other sparsely populated areas, inconvenient transportation and absent professional engineers often delay the best time to repair the machines. Time-or interval-based maintenance (TBM) accounts for almost 100%, while, On-condition maintenance and other proactive maintenance are seldom adopted. TBM not only can't prevent happens of equipment fault but also cause the waste of the maintenance resource. In order to allocate maintenance resources reasonably, ascertain the minimum preventive maintenance requirement, ensure the reliability, availability and safety, this paper carries out a research on Risk and Condition Based Maintenance (RCBM) task optimization technology. Utilizing the internet of things (IOT), real-time database, signal-processing, Gray Neural Network, probability statistical analysis and service oriented architecture (SOA) technology, a Risk and Condition Based Indicator Decision-making System (RCBIDS) is built. RCBIDS integrates RCM, condition monitoring system (CMS), key performance management module, file management module, fault and defect management module, maintenance management module together, which aims to realize remote condition monitoring, maintenance technical support services (TSS), quantitative maintenance decision-making, and to ensure the Reliability, Availability, Maintainability and Safety (RAMS). The Predictive Maintenance Indicator model, reliability prediction model and Key Performance Indicator (KPI) model, which are embedded in the RCBIDS, are constructed separately. An engineering case shows that the risk and condition based maintenance task optimization technology can be used to optimize maintenance content and maintenance period, to minimize maintenance deficiencies and maintenance surplus, and to prolong the lifespan of equipment. © 2012 Elsevier Ltd.


Su C.,Beijing University of Chemical Technology | Li H.,Beijing University of Chemical Technology
Applied Intelligence | Year: 2012

Traditional interactive evolutionary computing approaches are usually susceptible to limited searching ability and human's strong subjectivity. In response, by extending a traditional Belief-Desire-Intention (BDI) structure, a kind of affective learning agent which can perform affective computing and learning activities in human-computer interaction environment is explicitly introduced. In solving human-computer interactive multi-objective decision-making problems whose objectives are usually far from well structured and quantified, this kind of agent may help reduce human's subjective fatigue as well as make decisions more objective and scientific. Specifically, a conceptual model of the agent, affective learning-BDI (AL-BDI) agent, is proposed initially, along with corresponding functional modules to learn human's affective preference. After that, a kind of high level Petri nets, colored Petri nets are employed to realize the components and scheduler of the AL-BDI agents. To exemplify applications of the approaches, test functions are suggested to case studies, giving rise to satisfied results and showing validity of the contribution. © 2012 Springer Science+Business Media, LLC.


Ma X.,Beijing University of Chemical Technology | Tang Y.,Beijing Institute of Fashion Technology | Lei M.,Beijing University of Chemical Technology
Dalton Transactions | Year: 2014

This work studied the bent and planar structures of M2N 2 cores of a series of dinuclear early transition-metal complexes (M = Zr, Hf, Nb, Ta, Mo and W) containing a side-on bridging dinitrogen ligand using DFT method. The calculated results propose three key factors favoring a bent structure: (1) the availability of a single electron in the metal centers which leads to the bonding interaction between two metal atoms, (2) no remarkable steric effect around the metal centers, and (3) the cis conformation of the ligands in the dinitrogen dinuclear complexes. In addition, the bent and planar structures of M2N2 could be transformed into each other if the steric hindrance was slight. This journal is © the Partner Organisations 2014.


Fan G.,Beijing University of Chemical Technology | Li F.,Beijing University of Chemical Technology
Chemical Engineering Journal | Year: 2011

In this paper, we report on the three-dimensional nanostructured Cu2O/CuO films with controlled flower-like shapes using a direct crystallization approach in the presence of sodium borohydride without using any performed template, surfactant or oxidant. The microstructures and shapes of Cu2O/CuO architectures were investigated by field emission scanning electron microscopy, X-ray diffraction and transmission electron microscopy. Three types of chrysanthemum-like, candock-like and dandelion-like CuO microstructures consisting of densely packed building blocks of nanobelts or nanoribbons were achieved by governing the concentrations of NaBH4. Possible growth mechanisms for the controlled organization of primary building units into three-dimensional flower-like architectures were proposed. After simple surface modification with sodium laurate, the resulting films displayed hydrophobic and even superhydrophobic properties owing to their special surface nano-/microstructures. © 2011 Elsevier B.V.


Zhou J.,Beijing University of Chemical Technology | Li G.,Beijing University of Chemical Technology | Wang H.,University of Manchester
Automatica | Year: 2014

In this paper, the robust tracking control problem for uncertain singular stochastic distribution control (SDC) systems is considered. A new control target, where the distribution tracking error at each time instant satisfies a certain upper bound beyond a limited time, is proposed. This control target is different from the tracking control in the output SDC systems which makes the output probability density function (PDF) track a desired PDF as close as possible. Then an instant performance index instead of the infinite integration index is adopted, and the upper bound of this index is taken as the stability condition of a Lyapunov function to obtain a robust tracking controller via an augmentation control and linear matrix inequality (LMI). Simulations are also included to show the effectiveness of the proposed algorithm and encouraging results have been obtained. © 2014 Elsevier Ltd. All rights reserved.


Wan P.,Beijing University of Chemical Technology | Yang X.J.,Beijing University of Chemical Technology
ChemSusChem | Year: 2012

Pass the salt please: The electrolysis of water and aqueous solutions of common salts (NaCl, Na 2CO 3, and Na 2SO 4) with renewable electricity is potentially the best pathway to move towards a hydrogen economy and sustainable environment, but its cost-effectiveness is a major challenge. This Highlight looks at hurdles and opportunities for the large-scale production of hydrogen through electrolysis. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Abdellaoui H.,Beijing University of Chemical Technology | Xu J.,Beijing University of Chemical Technology
Tetrahedron | Year: 2014

A series of 4-spiro-cyclohexadienonyl-β-lactam-3-carbonitriles, 2,7-dioxo-1-azaspiro[3.5]nona-5,8-diene-3-carbonitriles, was synthesized in satisfactory to excellent yields via the intramolecular nucleophilic cyclization of N-(p-hydroxyphenyl)cyanoacetamides with iodobenzene diacetate (IBD) as oxidant and potassium hydroxide as base. Acetic 4-spiro-cyclohexadienonyl- β-lactam-3-carbimidic anhydrides were obtained when organic base triethylamine was applied instead of potassium hydroxide. The mechanisms of the intramolecular nucleophilic cyclization and formation of acetic β-lactam-3-carbimidic anhydrides were proposed. The cyclization is a sequence of nucleophilic ipso addition and oxidative dearomatization. The formation of acetic carbimidic anhydrides is an acid-catalyzed acetate addition to the nitriles. © 2014 Elsevier Ltd. All rights reserved.


Li W.,Beijing University of Chemical Technology | Du Q.,Mississippi State University | Xiong M.,Beijing University of Chemical Technology
IEEE Geoscience and Remote Sensing Letters | Year: 2015

In this letter, kernel collaborative representation with Tikhonov regularization (KCRT) is proposed for hyperspectral image classification. The original data is projected into a high-dimensional kernel space by using a nonlinear mapping function to improve the class separability. Moreover, spatial information at neighboring locations is incorporated in the kernel space. Experimental results on two hyperspectral data prove that our proposed technique outperforms the traditional support vector machines with composite kernels and other state-of-the-art classifiers, such as kernel sparse representation classifier and kernel collaborative representation classifier. © 2014 IEEE.


Wang X.,Beijing University of Chemical Technology | Zhao J.,Beijing University of Chemical Technology
Journal of Agricultural and Food Chemistry | Year: 2013

Microcapsules of the herbicide picloram (PLR) were formulated by a layer-by-layer (LbL) self-assembly method using the polyelectrolyte biopolymers of biocompatible chitosan (CS) and the UV-absorbent sodium lignosulfonate (SL) as shell materials. The herbicide PLR was recrystallized and characterized using XRD analysis. The obtained PLR-loaded microcapsules were characterized by using SEM, FTIR, CLSM, and ζ-potential measurements. The herbicide loading and encapsulation efficiency were also analyzed for the PLR-loaded microcapsules. The influence of LbL layer numbers on herbicide release and photodegradation rates was investigated in vitro. The results showed that the release rates and photodegradation rates of PLR in microcapsules decreased with increasing number of CS/SL self-assembly layers. The results demonstrated that polyelectrolyte biopolymer-based LbL multilayer microcapsules can be a promising approach for the controlled release of PLR as well as other pesticides with poor photostability or short half-release time. © 2013 American Chemical Society.


Liu H.-J.,Beijing University of Chemical Technology | Wang F.,Beijing University of Chemical Technology | Zhao Y.,South Dakota School of Mines and Technology | Fong H.,South Dakota School of Mines and Technology
Nanoscale | Year: 2013

Mechanically resilient mats consisting of overlaid electrospun nanofibers with self-generated TiC crystallites embedded in a carbon matrix are surface-decorated with Pt nanoparticles as a novel electrocatalytic system for oxygen reduction reaction. Electrocatalytic activities (e.g., on-set potential and current density) of Pt are substantially enhanced due to high specific surface area of the support and the synergetic effect of TiC and Pt on electrocatalysis. © 2013 The Royal Society of Chemistry.


Li W.,Beijing University of Chemical Technology | Chen C.,University of Texas at Dallas | Su H.,Hohai University | Du Q.,Mississippi State University
IEEE Transactions on Geoscience and Remote Sensing | Year: 2015

It is of great interest in exploiting texture information for classification of hyperspectral imagery (HSI) at high spatial resolution. In this paper, a classification paradigm to exploit rich texture information of HSI is proposed. The proposed framework employs local binary patterns (LBPs) to extract local image features, such as edges, corners, and spots. Two levels of fusion (i.e., feature-level fusion and decision-level fusion) are applied to the extracted LBP features along with global Gabor features and original spectral features, where feature-level fusion involves concatenation of multiple features before the pattern classification process while decision-level fusion performs on probability outputs of each individual classification pipeline and soft-decision fusion rule is adopted to merge results from the classifier ensemble. Moreover, the efficient extreme learning machine with a very simple structure is employed as the classifier. Experimental results on several HSI data sets demonstrate that the proposed framework is superior to some traditional alternatives. © 1980-2012 IEEE.


Zhao M.,Beijing University of Chemical Technology | Song H.,Beijing University of Chemical Technology
Journal of Materials Science and Technology | Year: 2011

The catalytic graphitization of thermal plastic phenolic-formaldehyde resin with the aid of ferric nitrate (FN) was studied in detail. The morphologies and structural features of the products including onion-like carbon nanoparticles and bamboo-shaped carbon nanotubes were investigated by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction and Raman spectroscopy measurements. It was found that with the changes of loading content of FN and residence time at 1000°C, the products exhibited various morphologies. The TEM images showed that bamboo-shaped carbon nanotube consisted of tens of bamboo sticks and onion-like carbon nanoparticle was made up of quasi-spherically concentrically closed carbon nanocages. © 2011 The Chinese Society for Metals.


Weng M.,Beijing University of Chemical Technology | Qiu Z.,Beijing University of Chemical Technology
Thermochimica Acta | Year: 2014

Biodegradable poly(butylene succinate-co-butylene carbonate) (PBSC) and tannic acid (TA) blends were prepared via a solution and casting method in this work. Miscibility and crystallization behavior of PBSC/TA blends were investigated with various techniques. PBSC is miscible with TA as evidenced by both a single composition dependent glass transition temperature and the depression of equilibrium melting point of PBSC in the blends. Relative to neat PBSC, blending with TA does not modify the crystal structure of PBSC in the blends. The nonisothermal melt crystallization of PBSC was retarded by TA in the blends. Both the overall isothermal melt crystallization rates and spherulitic growth rates of PBSC/TA blends show the similar variation trends, which become slower with increasing crystallization temperature and the TA composition. The crystallization mechanism of PBSC does not change, regardless of crystallization temperature and the TA composition in the blends.© 2013 Elsevier B.V. All rights reserved.


Liu S.,Shandong University | Zhang X.,Shandong University | Yu Y.,Beijing University of Chemical Technology | Zou G.,Shandong University
Biosensors and Bioelectronics | Year: 2014

The development of electrochemiluminescence (ECL) emitters over a broad spectrum of wavelengths is anticipated for the multiplexed ECL sensing and diagnostic application. Herein, a facile dual-stabilizers-capped strategy was developed for synthesizing a series of water-soluble CdSe nanocrystals (NCs) with strong, bandgap engineered and monochromatic ECL emissions in greenish region. The linkage of surface cadmium atoms to the dual stabilizers, mercaptopropionic acid and sodium hexametaphosphate, not only can effectively remove the nonradiative surface state and deep surface trap of CdSe NCs for improved ECL efficiency and monochromaticity, but is also favorable for the electrochemical involved electron and hole injection processes for higher ECL intensity. ECL spectra of dual-stabilizers-capped CdSe NCs are narrow and much close to corresponding photoluminescence spectra, which indicates a series of bandgap engineered and monochromatic ECL emitters. The ECL signal of dual-stabilizers-capped CdSe NCs also shows acceptable accuracy and precision for the detection of dopamine concentration in the practical drug (dopamine hydrochloride injection). © 2013.


Weng M.,Beijing University of Chemical Technology | Qiu Z.,Beijing University of Chemical Technology
Thermochimica Acta | Year: 2014

Biodegradable poly(l-lactide) (PLLA) and cyanuric acid (CA) composites were prepared via a solution and casting method at low CA loadings. The nonisothermal melt crystallization behavior, overall isothermal melt crystallization kinetics, spherulitic morphology, and crystal structure of neat PLLA and the PLLA/CA composites were investigated with various techniques. Relative to neat PLLA, the crystallization process of PLLA was accelerated obviously by the presence of CA under both nonisothermal and isothermal melt crystallization conditions, indicating that CA acted as an efficient nucleating agent for the crystallization of PLLA; however, CA did not change the crystallization mechanism and crystal structure of PLLA in the composites. © 2013 Elsevier B.V.


Jiang J.,University of California at Riverside | Jiang J.,Beijing University of Chemical Technology | Cao D.,Beijing University of Chemical Technology | Henderson D.,Brigham Young University | Wu J.,University of California at Riverside
Physical Chemistry Chemical Physics | Year: 2014

We present a contact-corrected density functional theory for ionic distributions at an interface that not only accounts for the steric effects and electrostatic correlations often ignored by conventional electrochemical methods but also conforms to the exact statistical-mechanical sum rule for the contact ionic densities. The theoretical predictions are in excellent agreement with the simulation results for both the interfacial structure and electrochemical properties over a wide variety of electric double layer systems including those containing asymmetric electrolytes with multivalent ions. This journal is © 2014 the Owner Societies.


Wang G.,Beijing University of Chemical Technology | Qiu Z.,Beijing University of Chemical Technology
Industrial and Engineering Chemistry Research | Year: 2012

Biodegradable poly(butylene succinate) and a series of poly(butylene succinate-co- hexamethylene succinate) (P(BS-co-HS)) with hexamethylene succinate (HS) comonomer composition ranging from 14 to 35 mol % were prepared in the present work via a two-stage melt polycondensation method. Basic thermal behaviors, crystal structure, isothermal melt crystallization kinetics, and spherultic morphology and growth of P(BS-co-HS) copolyesters with different HS composition were studied in detail with various techniques and compared with those of neat PBS. With respect to neat PBS, the glass transition temperature of P(BS-co-HS) decreases slightly, while the melting point temperature and equilibrium melting point temperature of P(BS-co-HS) are reduced significantly with an increase in the HS composition. Both neat PBS and P(BS-co-HS) have the same crystal structure; however, the crystallinity values are slightly smaller in P(BS-co-HS) than in neat PES. The overall isothermal melt crystallization kinetics of neat PBS and P(BS-co-HS) were studied in a wide crystallization temperature range and analyzed by the Avrami equation. The experimental results indicate that the crystallization mechanism remains unchanged for both neat PBS and P(BS-co-HS); however, the overall crystallization rates of P(BS-co-HS) decrease with increasing HS composition and crystallization temperature. The spherulitic morphology of neat PBS and P(BS-co-HS) were also investigated in a wide crystallization temperature range; moreover, the spherulitic growth rates of P(BS-co-HS) also decrease with increasing HS content and crystallization temperature. © 2012 American Chemical Society.


Yao F.,Beijing University of Chemical Technology | Jia Y.,Beijing University of Chemical Technology | Mao Z.,Tsinghua University
International Journal of Hydrogen Energy | Year: 2010

Currently, the increasing price of oil and the possibility of global energy crisis demand for substitutive energy to replace fossil energy. Many kinds of renewable energy have been considered, such as hydrogen, solar energy, and wind energy. Many countries including China have their own plan to support the research of hydrogen, because of its premier features. But, at present, the cost of hydrogen energy production, storage and transportation process is higher than that of fossil energy and its commercialization progress is slow. Life cycle cost analysis (LCCA) was used in this paper to evaluate the cost of hydrogen energy throughout the life cycle focused on the stratagem selection, to demonstrate the costs of every step and to discuss their relationship. Finally, the minimum cost program is as follows: natural gas steam reforming - high-pressure hydrogen bottles transported by car to hydrogen filling stations - hydrogen internal-combustion engines. © 2009 Professor T. Nejat Veziroglu.


Yang Z.,Beijing University of Chemical Technology
Synlett | Year: 2014

(A) Amination of C-NucleophilesFollowing Sheradsky and co-workers report,2a the amination of differentC-nucleophiles was assessed.2b The results reveal that the enolatesderived from deprotonation of variously substituted ethylacetates smoothly undergo amination with 1, affording ethyl aminoacetates in moderate to good yields in most cases. However, the aminationof the carbanion derived from phenylacetonitrile gives thedesired product in only 7% yield. In addition, neither Reformatskyreagents nor sily enolates are susceptible to this transformation, evenunder violent reflux conditions.(B) Amination of N-Nucleophiles with C=N BondsAmination of pyridines with 1 followed by protection of the resultantfree NH2 group and deprotonation with a base leads to N-iminopyridiumylides in up to 99% yield.3 The yields are depended on thesteric hindrance of the 2- and 6-positions and the electronic densitiesof the pyridine rings. The product N-iminopyridium ylides are versatilebuilding blocks for the preparation of pyridine derivatives.3The amination is also applicable to other heterocycles such as imidazoles.4. © Georg Thieme Verlag Stuttgart New York.


Jin Q.B.,Beijing University of Chemical Technology | Liu Q.,Beijing University of Chemical Technology
Journal of Process Control | Year: 2014

This communication addresses the analytical PID tuning rules for integrating processes. First, this paper provides an analytical tuning method of two-degree-of-freedom (2-Dof) PID controller using an enhanced internal model control (IMC) principle. On the basis of the robustness analyses, the presented method can easily achieve the performance/robustness tradeoff by specifying a desired robustness degree. Second, an analytical tuning method of one-degree-of-freedom (1-Dof) PID also is proposed in terms of performance/robustness and servo/regulator tradeoffs, which are not commonly considered for 1-Dof controller design. The servo/regulator tradeoff is formulated as a constrained optimization problem to provide output responses as similar as possible to those produced by the 2-Dof PID controller. The presented PID settings are applicable for a wide range of integrating processes. Simulation studies show the effectiveness and merits of the proposed method. © 2013 Published by Elsevier Ltd. All rights reserved.


Chen L.,Beijing University of Chemical Technology | Yuan Q.,Beijing University of Chemical Technology
Journal of Functional Foods | Year: 2013

The antioxidant capacities of 15 commercial raspberry varieties grown in North China were evaluated and their anthocyanin profiles determined by LC-ESI-MS. Total polyphenol content (TPC), total flavonoid content (TFC), total anthocyanin content (TAC) and antioxidant capacities (AOC) of the 15 raspberries were measured, respectively and the results showed that the TPC, TFC and TAC contents of raspberries correlated well with their antioxidant capacities. Raspberries with higher contents of phytochemicals showed higher antioxidant capacity. The results indicated that the 15 raspberry varieties may be divided into three groups according to their anthocyanin component analysis. The first group was made up of Triple Crown, Shawnee, and Navaho varieties with identical anthocyanin profiles and dark red color. The second group included Canby, Bristol and Mac black varieties, which possessed higher TAC/TPC ratio and contribute more to antioxidant capacity and the rest of the varieties were in the third group with lower antioxidant capacities. The higher phytochemical contents and antioxidant activities of raspberry varieties in the second group indicated that their consumption would be more beneficial to health. © 2012 Elsevier Ltd.


Fang Y.,Beijing University of Chemical Technology | Li J.,Siemens AG | Wang M.,Beijing University of Chemical Technology
Energy Policy | Year: 2012

Government policy continues to play a crucial role in the development of wind power industry in China. The 2005 "Renewable Energy Law" and related policies have driven the rapid increase in wind power installed capacity in China over the past half-decade, with capacity doubling annually since 2005. However, a large number of wind farms generate electricity well below their installed capacity, resulting in considerable wastage of resources. Non-grid-connected wind power theory proposes that large-scale wind power output does not necessarily have to be fed into the grid, but can be used directly in industrial production. Thus, the use of the theory can promote the sustainable development of the wind power industry by obviating the need for power grid. In this paper we analyze the influence of government policy on wind power industry from the perspective of institutional change, by employing the basic theories of new institutional economics. A development model for non-grid-connected wind power is proposed in order to implement institutional change in accordance with the specific characteristics of wind power industry in China. This model requires the government to play an active role in institutional development by increasing economic efficiency in order to promote the sustainable development of wind power. © 2012 Elsevier Ltd.


Li H.,Beijing University of Chemical Technology | Wang L.,Beijing University of Chemical Technology
Chemistry - An Asian Journal | Year: 2014

Multicolor upconversion (UC) luminescence of NaYF4:Yb 3+/Er3+ nanoparticles (NPs) was successfully tuned by simply controlling the NaF dosage. Unlike UC nanocrystals previously reported in the literature with multicolor emission obtained by varying the rare-earth dopants, the current work developed a new approach to tune the UC emission color by controlling the NaF concentration without changing the ratio and dosage of rare-earth ions. TEM and powder XRD were used to characterize the shape, size, and composition of the UC luminescent nanocrystals. The luminescence images, emission spectra, and multicolor emission mechanism of the NPs have also been demonstrated. As a result of the excellent ability of this new method to manipulate color emission, this will open up new avenues in the areas of bioprobes, light-emitting devices, color displays, lasers, and so forth. To demonstrate their biological applications, the water-stable, biocompatible, and bioconjugatable NaYF4:Yb3+/Er3+@poly(acrylic acid) NPs were synthesized by this developed strategy and applied in targeted-cell UC luminescence imaging. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Wang H.,Beijing University of Chemical Technology | Cao D.,Beijing University of Chemical Technology
Journal of Physical Chemistry C | Year: 2015

We use grand canonical Monte Carlo and molecular dynamics simulations to systematically investigate the membrane-based separation performance of four diamond-like frameworks (PAF-1, Diamondyne, TND-1, and TND-2) for CO2/H2, CO2/N2, CO2/CH4 and CH4/H2 mixtures. Diamondyne (also named D-Carbon) shows high membrane selectivity for gas mixtures of CO2/H2, CO2/N2, CO2/CH4, and CH4/H2 compared to MOF and COF membranes. Comprehensively considering the permeation selectivity and permeability, we find that diamondyne and TND-2 are promising candidates for CO2/H2 and CO2/N2 separation. Moreover, diamondyne and TND-2 exceed the Robesons upper line for CO2/N2 mixtures. The separation performance of diamondyne for CO2/CH4 mixtures also exceeds the Robesons upper limitation, indicating that diamondyne is also a promising candidate for separation of the CO2/CH4 mixtures. It is expected that this work can provide guidance and reference for development and design of high selectivity membranes for gas mixtures. © 2015 American Chemical Society.


Chen M.,Beijing University of Chemical Technology | Yin M.,Beijing University of Chemical Technology
Progress in Polymer Science | Year: 2014

Because fluorescence-based techniques are inherently sensitive, selective, convenient, diverse, non-destructive, potentially real time and in situ, they have been widely used in biological imaging. Especially those, with specific fluorescent nanostructures (FNSs) as detecting media in bioimaging, have already been intensively studied for more than a decade because of the convenient transduction of optical signal, high sensitivity and rapid response of FNSs. In this review, we summarize the major strategies to design FNSs with specific structures for biological imaging. First, recent advances are briefly introduced. Then, the specific design of FNSs and their applications are reviewed, in which their fluorescence mechanism, strategies in designing and development, preparation methods, and some representative applications in bioimaging are described. Finally, future perspectives and ongoing issues of FNSs and their applications in bioimaging are discussed. Although many FNSs have been synthesized and applied biologically, many studies still should be done before they can be widely employed as fluorescent probes in clinical tests. With further advances in design and synthesis of high quality multifunctional FNSs, the widespread application of FNSs may be expected not only in advanced bioimaging, but also in ultra-sensitive molecular diagnosis, novel light-emitting nanodevices and intracellular drug delivery. © 2013 Elsevier Ltd. All rights reserved.


Zhang L.,Beijing University of Chemical Technology | Li F.,Beijing University of Chemical Technology
Applied Clay Science | Year: 2010

Carbon nanotubes/metal oxide composites were prepared by catalytic chemical vapor deposition of acetylene over Ni-Mg-Al layered double hydroxides (LDHs). Power X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) measurements revealed that multi-walled carbon nanotubes (CNTs) were synthesized in a catalytic reaction by Ni nanoparticles derived from LDHs. The spinel-type NixMg1-xAl2O4 was in situ formed together with CNTs. Electrodes modified with platinum particles supported on the as-fabricated CNTs/NixMg1-xAl2O4 composites showed excellent electrocatalytic activity for the electrooxidation of ethanol. The present study provided a new method to optimize electrodes modified with platinum particles, based on deposition of CNTs combined with metal oxides. © 2010 Elsevier B.V.


Ma D.,CSIRO | Ma D.,Beijing University of Chemical Technology | Lv M.,CSIRO | Lv M.,CAS Chengdu Institute of Organic Chemistry | And 5 more authors.
ACS Nano | Year: 2014

We present a strategy to fabricate polymer solar cells in inverted geometry by self-organization of alcohol soluble cathode interfacial materials in donor-acceptor bulk heterojunction blends. An amine-based fullerene [6,6]-phenyl-C61-butyric acid 2-((2-(dimethylamino)-ethyl)(methyl)amino)ethyl ester (PCBDAN) is used as an additive in poly(3-hexylthiophene) (P3HT) and 6,6-phenyl C61-butyric acid methyl ester (PCBM) blend to give a power conversion efficiency of 3.7% based on devices ITO/P3HT:PCBM:PCBDAN/MoO 3/Ag where the ITO alone is used as the cathode. A vertical phase separation in favor of the inverted device architecture is formed: PCBDAN is rich on buried ITO surface reducing its work function, while P3HT is rich on air interface with the hole-collecting electrode. The driving force of the vertical phase separation is ascribed to the surface energy and its components of the blend compositions and the substrates. Similar results are also found with another typical alcohol soluble cathode interfacial materials, poly[(9,9-bis(3′-(N, N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9- dioctylfluorene)] (PFN), implying that self-organization may be a general phenomenon in ternary blends. This self-organization procedure could eliminate the fabrication of printing thin film of interlayers or printing on such thin interlayers and would have potential application for roll-to-roll processing of polymer solar cells. © 2014 American Chemical Society.


Yao H.,Beijing University of Chemical Technology | Chu J.,Beijing University of Chemical Technology
Chemical Engineering Research and Design | Year: 2012

Like any other production processes, atmospheric distillation of crude oil is too complex to be accurately described with first principle models, and on-site experiments guided by some statistical optimization method are often necessary to achieve the optimum operating conditions. In this study, the design of experiment (DOE) optimization procedure proposed originally by Chen et al. (1998) and extended later by Chu et al. (2003) has been revised by using support vector regression (SVR) to build models for target processes. The location of future experiments is suggested through information analysis which is based on SVR models for the performance index and observed variables and reduces significantly the number of experiments needed. A simulated atmospheric distillation column (ADC) is built with Aspen Plus (version 11.1) for a real operating ADC. Kernel functions and parameters are investigated for SVR models to represent suitably the behavior of the simulated ADC. To verify the effectiveness of the revised DOE optimization procedure, three case studies are carried out: (1) The modified Himmelblau function is minimized under a circle constraint; (2) the net profit of the simulated ADC is maximized with all the 15 controlled variables free for adjusting in their operational ranges; (3) the net profit of the simulated ADC is maximized with fixed production rates for the three side-draws. © 2012 The Institution of Chemical Engineers.


Cheng G.,Beijing University of Chemical Technology | Zhang X.,Beijing University of Chemical Technology | Simmons B.,Joint BioEnergy Institute | Simmons B.,Sandia National Laboratories | And 2 more authors.
Energy and Environmental Science | Year: 2015

Efficient deconstruction of lignocelluosic biomass into fermentable sugar depends largely on the development of advanced biomass pretreatment technologies. Due to the highly heterogeneous nano- and microstructure of the plant cell walls, there is a lack of understanding with regard to interactions between biomass recalcitrance and biomass pretreatment. Progress has been made by comparing the changes in chemical compositions and physical structures during the pretreatment processes and their correlations with the enzymatic hydrolysis of pretreated biomass. Recent studies suggest the necessity of investigating the impact of biomass pretreatment on plant cell walls using analytical tools spanning multiple length scales. Scattering techniques including X-ray and neutron scattering, complementary to imaging techniques, offer several advantages like minimal sample preparation, versatile sample environment and in situ dynamic investigation of cell wall structures. The combination of wide and small angle scattering (WAS and SAS) techniques covers length scales from a few angstroms to several hundred nanometres. In this review article, a detailed overview of the application of WAS and SAS techniques to study the supramolecular structures of cellulose and lignin, the examination of the presence of pores in plant cell walls as well as in the cellulose fibres are presented. In situ enzymatic hydrolysis of cellulose investigated by SAS, providing important insight into enzyme-biomass interactions, is also summarized. This review highlights how probing structural changes during pretreatment of biomass samples by WAS and SAS can reveal valuable information that is often not accessible by other techniques. © 2015 The Royal Society of Chemistry.


Xiang Z.,Beijing University of Chemical Technology | Cao D.,Beijing University of Chemical Technology
Macromolecular Rapid Communications | Year: 2012

Three porous luminescent covalent - organic polymers (COPs) have been synthesized through self-polycondensation of the monomers of tris(4-bromophenyl)amine, 1,3,5-tris(4-bromophenyl)benzene, and 2,4,6-tris-(4-bromo-phenyl)-[1,3,5]triazine by using Ni-catalyzed Yamamoto reaction. All the COP materials possess not only high Brunauer-Emmett-Teller (BET) specific surface area of about 2000 m 2 g -1, high hydrothermal stability, but also graphene-like layer texture. Interestingly, COP-3 and COP-4 show very fast responses and high sensitivity to the nitroaromatic explosives, and also high selectivity for tracing picric acid (PA) and 2,4,6-trinitrotoluene (TNT) at low concentration (<1 ppm). In short, the COPs may be a new kind of material for detecting explosives and small organic molecules. Three porous graphene-like covalent-organic polymers (COPs) have been synthesized by Ni-catalyzed Yamamoto reaction in this work. These COP materials show fast responses and high sensitivity to the nitroaromatic explosives. The COP materials may be a new candidate for detecting explosives. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Cheng L.,Beijing University of Chemical Technology | Cao D.,Beijing University of Chemical Technology
ACS Nano | Year: 2011

Owing to the important roles of chemical gates in biological systems, the biomimetic design of artificial switchable nanodevices has been attracting tremendous interest. Here, we design a cylindrical thermo-sensitive channel, in which nanofliudic transport properties can be controlled by manipulating environmental temperature. The switchable channel is formed by a polystyrene-b-poly(acrylic acid)-b-polystyrene (PS-PAA-PS)-like triblock copolymer brush whose conformation and phase behavior are dependent on temperature. With the increase of temperature, the designed channel exhibits "close→open→close" behavior, which can serve as a kind of excellent switchable nanodevice for nanofluidic controllable transportation. © 2011 American Chemical Society.


Zhang H.,Beijing University of Chemical Technology | Zhang H.,Uppsala University | Tan T.,Beijing University of Chemical Technology | Hetenyi C.,Hungarian Academy of Sciences | Van Der Spoel D.,Uppsala University
Journal of Chemical Theory and Computation | Year: 2013

We introduce an indirect approach to estimate the solvation contributions to the thermodynamics of noncovalent complex formation through molecular dynamics simulation. This estimation is demonstrated by potential of mean force and entropy calculations on the binding process between β-cyclodextrin (host) and four drug molecules puerarin, daidzin, daidzein, and nabumetone (guest) in explicit water, followed by a stepwise extraction of individual enthalpy (ΔH) and entropy (ΔS) terms from the total free energy. Detailed analysis on the energetics of the host-guest complexation demonstrates that flexibility of the binding partners and solvation-related ΔH and ΔS need to be included explicitly for accurate estimation of the binding thermodynamics. From this, and our previous work on the solvent dependency of binding energies (Zhang et al. J. Phys. Chem. B 2012, 116, 12684-12693), it follows that calculations neglecting host or guest flexibility, or those employing implicit solvent, will not be able to systematically predict binding free energies. The approach presented here can be readily adopted for obtaining a deeper understanding of the mechanisms governing noncovalent associations in solution. © 2013 American Chemical Society.


Mo S.,Beijing University of Chemical Technology | Xu J.,Beijing University of Chemical Technology
ChemCatChem | Year: 2014

A chemospecific intramolecular Buchner reaction of N-benzyl-2-cyano-2- diazoacetamides catalyzed by inexpensive copper(II) acetylacetonate (acac) has been achieved to synthesize a variety of 9-aza-1-cyanobicyclo[5.3.0]deca-2,4,6- trien-10-ones, 5,7-bicyclic products. The methodology involves sole chemoselectivity, an inexpensive metal catalyst, broad substrate scope, and moderate to excellent yields. Cheap as copper: Copper(II) acetylacetonate is an efficient catalyst in the intramolecular Buchner reaction of N-benzyl-2-cyano-2-diazoacetamides for the chemospecific synthesis of 9-aza-1-cyanobicyclo[5.3.0]deca-2,4,6-trien-10-one derivatives in moderate to excellent yields with a broad substrate scope. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Cui L.,Beijing University of Chemical Technology | Li W.,Beijing University of Chemical Technology
IEEE Transactions on Image Processing | Year: 2011

In this paper, a multibit, multiplicative, spread spectrum watermarking using the discrete multiwavelet (including unbalanced and balanced multiwavelet) transform is presented. Performance improvement with respect to existing algorithm is obtained by means of a new just perceptual weighting (JPW) model. The new model incorporates various masking effects of human visual perception by taking into account the eye's sensitivity to noise changes depending on spatial frequency, luminance and texture of all the image subbands. In contrast to conventional JND threshold model, JPW describing minimum perceptual sensitivity weighting to noise changes, is fitter for nonadditive watermarking. Specifically, watermarking strength is adaptively adjusted to obtain minimum perceptual distortion by employing the JPW model. Correspondingly, an adaptive optimum decoding is derived using a statistic model based on generalized-Gaussian distribution (GGD) for multiwavelet coefficients of the cover-image. Furthermore, the impact of multiwavelet characteristics on proposed watermarking scheme is also analyzed. Finally, the experimental results show that proposed JPW model can improve the quality of the watermarked image and give more robustness of the watermark as compared with a variety of state-of-the-art algorithms. © 2011 IEEE.


Liu Q.,Beijing University of Chemical Technology | Liu Z.,Beijing University of Chemical Technology | Su J.,Shanxi Institute of Coal CAS Chemistry
Catalysis Today | Year: 2010

Al2O3-coated cordierite supported CuO catalyst shows high activities for selective catalytic reduction (SCR) of NO by NH3 at 350-500 °C after being sulfated by SO2. Its surface properties and reaction mechanism are elucidated in this paper by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) coupled with mass spectroscopy. Results show that the catalyst has both Lewis and Brønsted acid sites, the Brønsted acidity is far weaker than the Lewis acidity and the protonated ammonia on Brønsted sites is less stable than the coordinated ammonia on Lewis sites. Ammonia coordinated on sulfated CuAl 2O4 may transfer to NH2-NH2, where aluminum species is responsible for NH3 storage and copper species is responsible for activation of NH3 to NH2. The SCR reaction involves the adsorbed NH2-NH2 and gaseous NO, following Eley-Rideal mechanism. When NH3 is insufficient, NO may convert to NO2 through oxidation by O2 or to N 2O and NO2 through disproportionation. © 2010 Elsevier B.V.


Lu T.,Beijing University of Chemical Technology | Liu B.,Beijing University of Chemical Technology | Jiang P.X.,Tsinghua University
Applied Thermal Engineering | Year: 2011

Thermal stratification occurs in flows through elbows used for mixing hot and cold fluids. The movement of the interface between the hot and cold fluids over time causes fluctuations of the inner wall temperature, which can lead to the stress variations and structural thermal fatigue. Therefore, accurate inner wall temperature data detailing the fluctuations is essential for analysis and predictions of thermal fatigue of the piping. In the present study, the conjugate gradient method (CGM) is applied to solve the three-dimensional inverse heat conduction problem (IHCP) to estimate the unknown temperature fluctuations on the inner wall of a pipe elbow from simulated outer temperature measurements. First, the direct heat conduction problem is solved using the finite element method (FEM) to produce the outer and inner wall temperatures. Then, the inverse heat conduction problem is solved to estimate the inner wall temperatures based on the outer wall temperature data. The accuracy of the inverse algorithm is then examined by comparing the estimated inner wall temperatures with the exact temperatures from the direct solution. The numerical results show that the inner wall temperature of the elbow can be accurately estimated by using the present algorithm for the test case considered. © 2011 Elsevier Ltd. All rights reserved.


Yu G.,Beijing University of Chemical Technology | Chen X.,Beijing University of Chemical Technology
Journal of Physical Chemistry B | Year: 2011

Ionic liquids (ILs) show good performances in SO2 separation science, e.g., SO2 capture from high-temperature flue gas or separation from gas mixtures. In this work, the mechanism of capturing SO 2 by three guanidinium-based ILs, 1,1,3,3-tetramethylguanidinium lactate ([tmgHH][L]), 1,1,3,3-tetramethylguanidinium bis(trifluoromethylsulfonyl)imide ([tmgHH][Tf2N]), and 1,1,3,3-tetramethylguanidinium tetrafluoroborate ([tmgHH][BF4]), is investigated by using molecular dynamic simulation and ab initio calculation. The results of condensed phase molecular dynamic simulation for the mixtures of SO2 and these three ILs indicate the similar SO2 organization and interaction among them; SO2 may organize around [tmgHH]+ while it favorably organizes around the anions through Lewis acid - base interaction. Gas phase ab initio calculations show that [tmgHH][L] chemically interacts with SO2 while [tmgHH][Tf2N] and [tmgHH][BF4] do not, which is supported by the earlier FT-IR and 1H NMR data and is also consistent with the experimental result of a much higher absorption capability of [tmgHH][L] for SO2 than the latter two. The anion plays a key role in the chemical interaction between [tmgHH][L] and SO2, the S atom is bonded to the N atom on - NH 2 of [tmgHH]+, and some products with aminosulfate or aminosulfinic acid fragment may be formed. This work shows that IL structures should be carefully tailored for their final application in SO2 capture. © 2011 American Chemical Society.


Yang Y.,Beijing University of Chemical Technology | Qiu Z.,Beijing University of Chemical Technology
Industrial and Engineering Chemistry Research | Year: 2012

Crystallization and morphology were studied in a 30/70 poly(ethylene succinate-co-6 mol % butylene succinate)/poly(ethylene oxide) (P(ES-co-6 mol % BS)/PEO) blend in this work. Depending on the crystallization conditions, including one-step and two-step crystallization, both components may crystallize separately or simultaneously. P(ES-co-6 mol % BS) and PEO crystallized separately via two-step crystallization. When the crystallization temperature was between the melting points of the two components, both the spherulitic growth rate and the overall crystallization rate of P(ES-co-6 mol % BS) decreased with increasing crystallization temperature; moreover, they were slower in the blend than in neat P(ES-co-6 mol % BS) at the same crystallization temperature. When the crystallization temperature was further lowered below the melting point of PEO, PEO crystallized only as tiny crystals within the P(ES-co-6 mol % BS) spherulites formed earlier, while its overall crystallization rate was increased significantly in the presence of the P(ES-co-6 mol % BS) crystals. In the case of simultaneous crystallization, growth of both P(ES-co-6 mol % BS) and PEO spherulites and the formation of interpenetrated spherulites were observed in a wide crystallization temperature range via one-step crystallization. © 2012 American Chemical Society.


Yin S.,Northwestern University | Xu S.,Beijing University of Chemical Technology
Applied Physics A: Materials Science and Processing | Year: 2010

Supramolecular self-assembly on surfaces offers attractive features, which are usually tuned through the choice of the chain-length-varying molecular building blocks and stabilized by hydrogen bonding. Here the linear nanopatterns of bi-component building blocks between 1,18-octadecanedionic acid (HOOC(CH2)18COOH) and 4,4′-bipyridine (BPy), 1-hydroxyhexadecanoic acid (HO(CH2)15COOH) and BPy on highly ordered pyrolytic graphite are presented. By merely changing terminal groups, we reveal by using scanning tunneling microscopy (STM) that it is rational to steer the periodicity of the linearly patterned nanostructures with nanometer precision over an extended length scale. Different surface nanopatterns on graphite surface are created by tuning different disubstituted terminal groups and the ratio of them to their complementary recognizing molecules. The STM observations are supported by the reference nanostructure of bi-component 1,16-hexadecandiol (HO(CH2)16OH) and BPy. © Springer-Verlag 2009.


Zhao B.,Beijing University of Chemical Technology | Deng J.,Beijing University of Chemical Technology
Polymer Reviews | Year: 2016

Emulsion polymerizations of acetylenics have largely advanced in recent years for preparing polymer nanoparticles and emulsions thereof. This article presents a review on polyacetylene-derived nanoparticles with emphasis on the preparation of optically active helical polymer particles through emulsion polymerization processes. Chiral polymer nanoparticles obtained by emulsion polymerization techniques are classified into four main groups: nanoparticles, core/shell nanoparticles, hollow particles, and hybrid materials consisting of nanoparticles of the kind. Helix-sense-selective emulsion polymerizations are equally highlighted. Perspectives on the novel chiral polymer particles are also provided. This review article is expected to inspire more interest in advanced chiral polymeric nanoparticles. © 2016 Taylor & Francis Group, LLC


Yang Y.,Beijing University of Chemical Technology | Qiu Z.,Beijing University of Chemical Technology
CrystEngComm | Year: 2011

The crystallization kinetics and morphology of a series of biodegradable poly(butylene succinate-co-ethylene succinate) (P(BS-co-ES)) with ethylene succinate (ES) comonomer composition ranging from 13 to 28 mol% were investigated with various techniques and compared with those of the homopolymer poly(butylene succinate) (PBS) in this work. The crystal structures of P(BS-co-ES) are the same as that of neat PBS, but the crystallinity decreases slightly with increasing the ES composition. The glass transition temperature increases slightly while the nonisothermal melt crystallization peak temperature and melting point decrease for P(BS-co-ES) with increasing the ES composition; moreover, the equilibrium melting point temperature of P(BS-co-ES) is also reduced. The overall isothermal crystallization kinetics of P(BS-co-ES) was studied and compared with that of neat PBS. The crystallization mechanism does not change for either neat PBS and P(BS-co-ES) while the overall crystallization rates of P(BS-co-ES) decrease with increasing ES composition and crystallization temperature. The spherulite growth rates of P(BS-co-ES) also decrease with increasing ES composition and crystallization temperature. Both neat PBS and P(BS-co-ES) exhibit a crystallization regime II to III transition independent of ES composition; moreover, the crystallization regime transition temperature shifts to lower temperatures with increasing the ES composition. © 2011 The Royal Society of Chemistry.


Xu C.,Beijing University of Chemical Technology | Xu J.,Beijing University of Chemical Technology
Amino Acids | Year: 2011

A series of 1-substituted and 1,1-disubstituted taurines were synthesized from nitroolefins via the Michael addition with sodium ethylxanthate, oxidation with performic acid, and reduction with hydrogen in the presence of palladium on carbon powder. The current route is a versatile and salt-free method for synthesis of both aliphatic and aromatic 1-substituted and 1,1-disubstituted taurines. © Springer-Verlag 2010.


Li M.,Beijing University of Chemical Technology | Cheng D.,Beijing University of Chemical Technology
Journal of Physical Chemistry C | Year: 2013

Understanding the thermal stability of the novel crown-jewel structured Au-Pd nanoalloys with the Au atoms at the top positions is attractive and significant for their potential application in catalysis. In this work, the melting of crown-jewel structured Au-Pd nanoalloys with atoms from 561 to 2057 is investigated by molecular dynamics simulations, based on the Gupta potential. Melting properties for these clusters are studied based on the indicators such as potential energy curve, specific heat capacity, bond order parameters, and deformation parameters. It is found that there is a monotonic decrease of the melting temperature with the concentration of the Au atoms, indicating that doping of Au atoms on the Pd clusters could decrease the thermal stability of the Pd cluster. In addition, linear decrease in cluster melting point with the inverse cluster diameter is predicted for the same kind of cluster, which is well-known as the Pawlow's law. © 2013 American Chemical Society.


Xiang Z.,Beijing University of Chemical Technology | Cao D.,Beijing University of Chemical Technology
Journal of Materials Chemistry A | Year: 2013

Porous covalent-organic materials (COMs) are a fascinating class of nanoporous material with high surface area and diverse pore dimensions, topologies and chemical functionalities. These materials have attracted ever-increasing attention from different field scientists, owing to their potential applications in gas storage, adsorptive separation and photovoltaic devices. The versatile networks are constructed from covalent bonds (B-O, C-C, C-H, C-N, etc.) between the organic linkers by homo- or hetero-polymerizations. To design and synthesize novel porous COMs, we first summarize their synthesis methods, mainly including five kinds of coupling reaction, i.e. boronic acid, amino, alkynyl, bromine and cyan group-based coupling reactions. Then, we review the progress of porous COMs in clean energy applications in the past decade, including hydrogen and methane storage, carbon dioxide capture, and photovoltaic applications. Finally, to improve their gas adsorptive properties, four possible strategies are proposed, and high-capacity COMs for gas storage are designed by a multiscale simulation approach. This journal is © 2013 The Royal Society of Chemistry.


The slow crystallization rate and low elongation at break are the main drawbacks of biodegradable poly(l-lactide) (PLLA) from a viewpoint of practical application. Such disadvantages of PLLA have been successfully resolved by blending with low molecular weight biodegradable poly(ethylene adipate) (PEA) in the present work. As a biodegradable plasticizer, PEA not only formed fully miscible and biodegradable polymer blends with PLLA but also apparently reduced the glass transition temperature of the blends. The increased chain mobility favored the nonisothermal cold and melt crystallization behaviors, increased the spherulitic growth rate, and accelerated the overall isothermal melt crystallization process of the blends; however, the blends had the same crystallization mechanism and crystal structures as neat PLLA. One of the exciting results was that the elongation at break value of an 80/20 PLLA/PEA blend was dramatically increased; therefore, for a wider practical application, the preparation of PLLA-based materials with fast crystallization rate, good mechanical properties, and complete biodegradability could be accomplished by the blending with a small amount of PEA with low molecular weight as an efficient plasticizer. This journal is © the Partner Organisations 2014.


Huang L.,Beijing University of Chemical Technology | Cao D.,Beijing University of Chemical Technology
Journal of Materials Chemistry A | Year: 2013

Olefin-paraffin separation is one of the most significant processes in the petrochemical industry. An energy efficient method such as adsorption is considered to be a promising alternative to the traditional cryogenic distillation for the purification of olefins or paraffins. In this work, the grand canonical Monte Carlo (GCMC) method was used to study the adsorption and separation of light hydrocarbons (including ethylene, ethane, propylene and propane) by two diamond-like frameworks: diamondyne (originally named D-carbon in J. Mater. Chem. A, 2013, 1, 3851) and PAF-302, and further explore the mechanism for the adsorptive separation of olefins and paraffins. It is found that both diamondyne and PAF-302 show high uptake of hydrocarbons under ambient conditions, which greatly exceed those of MOFs and ZIFs. The saturation adsorption amounts of ethylene, ethane, propylene and propane on diamondyne are 14.5, 12.3, 10.3 and 8.9 mmol g-1, while they are 31.8, 28.0, 32.0, 30.3 mmol g-1 for PAF-302, which indicates that PAF-302 is an excellent candidate for hydrocarbon adsorption. In addition, it is also found that diamondyne shows preferential adsorption of olefins in the olefin-paraffin mixtures, like most commonly reported MOFs and ZIFs. However, interestingly, PAF-302 exhibits favorable adsorption for paraffins over olefins, which is an entirely different behavior to diamondyne, even though they have similar diamond-like structures. © 2013 The Royal Society of Chemistry.


Li X.,Beijing University of Chemical Technology | Xu J.,Beijing University of Chemical Technology
Tetrahedron | Year: 2011

The course, especially the regioselectivity, of the nucleophilic ring opening of thiiranes with ammonia and amines was investigated with the density functional theory (DFT) calculation. In the ring-opening reaction, thiiranes could be attacked on either their less or more substituted carbon atoms. The analyses of the potential energy surfaces, the bond lengths, and charges of key species in both pathways indicate that alkyl-substituted thiiranes are attacked dominantly on their less substituted ring carbon atom, whereas arylthiiranes are on their more substituted one due to the existence of the p-π conjugative effect, which stabilizes the transition states generated in the reaction. Furthermore, the Lewis acid can modulate the regioselectivity. However, the steric hindrance of nucleophiles and solvents affect the regioselectivity slightly as they show similar influence on both pathways, despite the fact that they can put an impact on the energy. NBO and MO analyses also support the substituent-depended regioselectivity. This is the first DFT calculational investigation on the regioselective ring opening of thiiranes and provides a rational explanation for the experimental results. The theoretical investigation gives a general understanding and a rule for the rationale and prediction of the regioselectivity in the nucleophilic ring opening of thiiranes, even other three-membered heterocycles. © 2011 Elsevier Ltd. All rights reserved.


Lv Y.,Beijing University of Chemical Technology | Lv Y.,University of California at Berkeley | Tan T.,Beijing University of Chemical Technology