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.


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Ma H.-L.,Beijing University of Chemical Technology | Zhang Y.,Peking University | Hu Q.-H.,Beijing University of Chemical Technology | Yan D.,Beijing University of Chemical Technology | And 2 more authors.
Journal of Materials Chemistry | Year: 2012

Ethylenediamine-reduced graphene oxide (ED-RGO) sheets were prepared by simple refluxing of graphene oxide (GO) solution with ethylenediamine (ED), which effectively reduced toxic Cr(vi) to less toxic Cr(iii) by an indirect reduction mechanism with the assistance of π electrons on the carbocyclic six-membered ring of ED-RGO. This journal is © The Royal Society of Chemistry 2012.


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.


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.


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.


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.


Lu Z.,Beijing University of Chemical Technology | Zhu W.,Beijing University of Chemical Technology | Yu X.,Beijing University of Chemical Technology | Zhang H.,Beijing University of Chemical Technology | And 8 more authors.
Advanced Materials | Year: 2014

The adhesion of as-formed gas bubbles on the electrode surface usually impedes mass-transfer kinetics and subsequently decreases electrolysis efficiency. Here it is demonstrated that nanostructured MoS2 films on conductive substrates show a faster hydrogen evolution reaction (HER), current increase, and a more-stable working state than their flat counterpart by significantly alleviating the adhesion of as-formed gas bubbles on the electrode. This study clearly reveals the importance of a nano-porous structure for HER, which should be general and beneficial for constructing other gas-evolution electrodes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Jiang J.,Beijing University of Chemical Technology | Jiang J.,University of California at Riverside | Cao D.,Beijing University of Chemical Technology | Jiang D.-E.,Oak Ridge National Laboratory | Wu J.,University of California at Riverside
Journal of Physical Chemistry Letters | Year: 2014

The charging kinetics of electric double layers (EDLs) has a pivotal role in the performance of a wide variety of nanostructured devices. Despite the prevalent use of ionic liquids as the electrolyte, relatively little is known on the charging behavior from a microscopic perspective. Here, we study the charging kinetics of ionic liquid EDLs using a classical time-dependent density functional theory that captures the molecular excluded volume effects and electrostatic correlations. By examining variations of the ionic density profiles and the charging density in response to an electrode voltage, we find that at certain conditions, the electrode charge shows a rapid surge in its initial response, rises quickly to the maximum, and then slowly decays toward equilibrium. The electrode charge and voltage may have opposite signs when the cell width is commensurate with the layer-by-layer ionic distributions. This unusual charging behavior can be explained in terms of the oscillatory structure of ionic liquids near the electrodes. © 2014 American Chemical Society.


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.


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.


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.


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.


Yang R.,Beijing University of Chemical Technology | Liu G.,Beijing University of Chemical Technology | Li M.,Beijing University of Chemical Technology | Zhang J.,Military Supply Research Institute | Hao X.,Military Supply Research Institute
Microporous and Mesoporous Materials | Year: 2012

A series of activated carbons (ACs) were prepared by chemical activation of hemp (Cannabis sativa L.) stem with KOH. The porous structure of the samples was characterized by N 2, CO 2 and H 2 adsorption, and the surface property was analyzed by IR. All samples show type I isotherms with multimodal pore size distributions in the <10 nm region, and a super AC with BET surface area of 3241 m 2/g and total pore volume of 1.98 cm 3/g is obtained. Hydrogen uptakes are linear function of specific surface area, total pore volume, and micropore volume, and the maximum hydrogen uptakes are 3.28 wt.% at -196 °C, 1.0 bar. The hydrogen adsorption mainly takes place in micropores but not absolutely, and mesopores in the range 2-5 nm also make important contribution. The gas adsorption amount is dominated by ultramicropores at lower pressure, and then lager micropores and mesopores make major contributions at higher pressure. © 2012 Elsevier Inc. All rights reserved.


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.


Kakaei S.,Beijing University of Chemical Technology | Chen N.,Beijing University of Chemical Technology | Xu J.,Beijing University of Chemical Technology | Xu J.,Peking University
Tetrahedron | Year: 2013

A radical addition reaction and subsequent performic acid oxidation were used for the synthesis of 1-substituted taurines with diverse functionalized side-chains from N-allylphthalimide and various xanthates. The current approach shows high yields and short synthetic route and reaction time. Moreover, the current method is a convenient and practical method for the synthesis of 1-substituted taurines with different functionalized side-chains. © 2012 Elsevier Ltd. All rights reserved.


Zhang H.,City University of Hong Kong | Zhang C.,Beijing University of Chemical Technology | Liu R.,City University of Hong Kong | Yi L.,Beijing University of Chemical Technology | Sun H.,City University of Hong Kong
Chemical Communications | Year: 2015

A new fluorescent probe installed with dual-reactive and dual-quenching groups was rationally designed for highly selective and sensitive sensing of biothiols. The sensitivity of the probe toward thiols was significantly improved by dual-quenching effects. Furthermore the selectivity of the probe was also greatly enhanced by installation of dual-reactive groups. This journal is © The Royal Society of Chemistry 2015.


Huang Z.,Beijing University of Chemical Technology | Xu J.,Beijing University of Chemical Technology | Xu J.,Peking University
Tetrahedron | Year: 2013

A series of N-protected 1-substituted homotaurines was synthesized efficiently from various olefins with O-ethyl S-2-phthalimidomethylxanthate as a sulfur-aminomethylation reagent via a radical addition and subsequent performic acid oxidation. The current method is a convenient and practical method for the synthesis of 1-substituted homotaurines with high yields and short synthetic route. © 2012 Elsevier Ltd. All rights reserved.


Liu X.,Tianjin University of Technology | Liu J.,Beijing University of Chemical Technology | Sun X.,Beijing University of Chemical Technology
Journal of Materials Chemistry A | Year: 2015

Hybrid metal oxide architectures have attracted much attention in recent years due to their great potential to meet the ever-increasing requirements of high energy density and power density in energy storage applications. Here, we report a facile hydrothermal synthesis of a binder-free hierarchical NiCo2O4@NiO nanowire array (HNW) with robust adhesion, for use in electrochemical capacitors (ECs). The resulting hybrid array electrode exhibits superior pseudocapacitive performance with high specific capacitance (2220 F g-1), remarkable rate capability, and excellent cycling performance (93.1% retention after 3000 cycles). Furthermore, a NiCo2O4@NiO//AC asymmetric supercapacitor was prepared and found to exhibit a high energy density (31.5 W h kg-1) at a power density of 215.2 W kg-1 and superior cycling stability (89% of the initial capacity retention at 50 A g-1 over 3000 cycles). This outstanding electrochemical performance benefits from the synergistic contribution of the composite and unique hierarchical architecture. Such highly integrated hybrid array electrodes will be extremely helpful towards the fabrication of high-performance nanoenergy systems. This journal is © The Royal Society of Chemistry.


Ge J.,Beijing University of Chemical Technology | Peng Y.,Beijing University of Chemical Technology | Li Z.,Changchun Gold Research Institute | Chen P.,North China Pharmaceutical Group Corporation | Wang S.,Curtin University Australia
Desalination | Year: 2014

Membrane wetting and fouling were studied using hollow-fiber polyvinylidene fluoride (PVDF) membranes to concentrate reverse osmosis (RO) brine in a direct contact membrane distillation (DCMD) process. The effect of the operating conditions, such as the feed temperature, the flow velocity and the feed solution concentration, was investigated. Membrane wetting was more significant at high feed temperatures, and the salts in the feed promoted membrane wetting; membrane wetting resulted in a decrease in the flux and salt rejection. A theoretical model was developed to simulate the DCMD process, and the results of the model were analyzed. The concentration factor significantly affected the flux and the electrical conductivity of the distillate. When the concentration factor (CF) was less than 3.5, CaSO4 did not crystallize because of high ionic strength and higher solubility of CaSO4 at the membrane surface than in the bulk solution; beyond CF of 3.5, membrane fouling was exacerbated because of CaSO4 crystallization. Membrane fouling was more significant at the higher of the two temperatures investigated for long-time DCMD operation: square CaSO4 crystals formed at 77°C, whereas snowflakes formed at 55°C. The permeate was lower in the divalent cations, Mg2+ and Ca2+, than in the monovalent cations, Na+ and K+. © 2014 Elsevier B.V.


Xu X.,Beijing University of Chemical Technology | Cao D.,Beijing University of Chemical Technology | Wu J.,University of California at Riverside
Soft Matter | Year: 2010

Polymer-based "non-stick" surfaces have been proposed as the next generation of effective and environmentally-friendly coating materials for protecting implanted biomedical devices and for marine antifouling. However, identification of polymeric systems for universal fouling control is often impeded by the poor knowledge of interactions between biological substances and polymeric substrates in diverse aqueous environments. In this article, we review predictions of the polymer density functional theory (DFT) on the structural and surface properties of polymer brushes and polymer nanocomposites that are potentially useful for antifouling applications. In comparison to alternative theoretical methods, DFT exhibits versatile features that are ideal for investigating various polymer-mediated interactions, self-organization of nanoparticles, and surface-induced phase transitions. It is capable of explicit description of important microscopic details of polymeric systems including the molecular excluded-volume effects, associating interactions, van der Waals attraction, Coulomb forces, and inter- and intra- molecular correlations. The theoretical descriptions of surface forces may provide helpful guidelines in the design and development of polymeric materials for preventing non-specific adsorption of biological substances. © 2010 The Royal Society of Chemistry.


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.


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.


Jun J.W.,Kyungpook National University | Tong M.,Beijing University of Chemical Technology | Jung B.K.,Kyungpook National University | Hasan Z.,Kyungpook National University | And 2 more authors.
Chemistry - A European Journal | Year: 2015

The adsorptive removal of organoarsenic compounds such as p-arsanilic acid (ASA) and roxarsone (ROX) from water using metal-organic frameworks (MOFs) has been investigated for the first time. A MOF, iron benzenetricarboxylate (also called MIL-100-Fe) exhibits a much higher adsorption capacity for ASA and ROX than activated carbon, zeolite (HY), goethite, and other MOFs. The adsorption of ASA and ROX over MIL-100-Fe is also much more rapid than that over activated carbon. Moreover, the used MIL-100-Fe can be recycled by simply washing with acidic ethanol. Therefore, it is determined that a MOF such as MIL-100-Fe can be used to remove organoarsenic compounds from contaminated water because of its high adsorption capacity, rapid adsorption, and ready regeneration. Moreover, only one of three analogous MIL-100 species (MIL-100-Fe, rather than MIL-100-Al or MIL-100-Cr) can effectively remove the organoarsenic compounds. This selective and high adsorption over MIL-100-Fe, different from other analogous MIL-100 species, can be explained (through calculations) by the facile desorption of water from MIL-100-Fe as well as the large (absolute value) replacement energy (difference between the adsorption energies of the organoarsenic compounds and water) exhibited by MIL-100-Fe. A plausible adsorption/ desorption mechanism is proposed based on the surface charge of the MOFs, FTIR results, calculations, and the reactivation results with respect to the solvents used in the experiments. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.


Fernandes D.,Adolfo Ibáñez University | Pitie F.,University of Warwick | Caceres G.,Adolfo Ibáñez 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.


Zhang C.,Beijing University of Chemical Technology | Zhang C.,Jiangsu University | Su H.,Beijing University of Chemical Technology | Baeyens J.,Beijing University of Chemical Technology | And 2 more authors.
Renewable and Sustainable Energy Reviews | Year: 2014

The uncontrolled discharge of large amounts of food waste (FW) causes severe environmental pollution in many countries. Within different possible treatment routes, anaerobic digestion (AD) of FW into biogas, is a proven and effective solution for FW treatment and valorization. The present paper reviews the characteristics of FW, the principles of AD, the process parameters, and two approaches (pretreatment and co-digestion) for enhancing AD of food waste. Among the successive digestion reactions, hydrolysis is considered to be the rate-limiting step. To enhance the performance of AD, several physical, thermo-chemical, biological or combined pretreatments are reviewed. Moreover, a promising way for improving the performance of AD is the co-digestion of FW with other organic substrates, as confirmed by numerous studies, where a higher buffer capacity and an optimum nutrient balance enhance the biogas/methane yields of the co-digestion system. © 2014 Elsevier Ltd. All rights reserved.


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.


Zhang M.,Beijing University of Chemical Technology | Li Y.,Beijing University of Chemical Technology | Su Z.,Beijing University of Chemical Technology | Wei G.,University of Bremen
Polymer Chemistry | Year: 2015

Graphene (G)-based nanocomposites have received much attention in various disciplines due to their high specific surface area, good compatibility, low mass density, elegant flexibility as well as the excellent synergistic effect of G with other nanomaterials. Numerous studies have been carried out to fabricate G-based polymer composites with novel and improved properties. However, the dispersion behavior of G in a polymer matrix and the interfacial bonding between G and polymers still restrict the better performances and broader applications of the fabricated G-polymer nanocomposites. In this review, we have summarized the most recent studies on the modification of G with polymers and the subsequent synthesis and applications of high quality G-polymer nanocomposites. The strategies for surface modification of G with polymers, including various covalent and non-covalent techniques, are introduced in detail. In addition, a series of effective processing routes for producing high quality G-polymer nanocomposites, such as melt compounding, solution blending, in situ polymerization, latex mixing, and electropolymerization, are introduced and discussed. Finally, the potential applications of the synthesized G-polymer nanocomposites in electrocatalysts, drug delivery, high performance materials, biosensors, and biomedical materials are presented. © The Royal Society of Chemistry 2015.


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.


Baeyens J.,University of Warwick | Baeyens J.,Beijing University of Chemical Technology | Kang Q.,Catholic University of Leuven | Kang Q.,Beijing University of Chemical Technology | And 4 more authors.
Progress in Energy and Combustion Science | Year: 2015

Bio-ethanol, as a clean and renewable fuel, is gaining increasing attention, mostly through its major environmental benefits. It can be produced from different kinds of renewable feedstock such as e.g. sugar cane, corn, wheat, cassava (first generation), cellulose biomass (second generation) and algal biomass (third generation). The conversion pathways for the production of bio-ethanol from disaccharides, from starches, and from lignocellulosic biomass are examined. The common processing routes are described, with their mass and energy balances, and assessed by comparing field data and simulations. Improvements through 5 possible interventions are discussed, being (i) an integrated energy-pinch of condensers and reboilers in the bio-ethanol distillation train; (ii) the use of Very High Gravity (VHG) fermentation; (iii) the current development of hybrid processes using pervaporation membranes; (iv) the substitution of current ethanol dewatering processes to >99.5 wt% pure ethanol by membrane technology; and (v) additional developments to improve the plant operation such as the use of microfiltration of the fermenter broth to protect heat exchangers and distillation columns against fouling, or novel distillation concepts. Whereas the benefits of introducing these techniques are recognized, extensive research is still needed to scientifically and economically justify their application. The paper finally presents a tentative economic assessment, with production costs not only depending on the extent of applying process improvements, but also on the raw material used in the process. © 2014 Elsevier Ltd. All rights reserved.


Zhao X.,Beijing University of Chemical Technology | Zhang P.,Beijing University of Chemical Technology | Chen Y.,Beijing University of Chemical Technology | Su Z.,Beijing University of Chemical Technology | Wei G.,University of Bremen
Nanoscale | Year: 2015

The preparation and applications of graphene (G)-based materials are attracting increasing interests due to their unique electronic, optical, magnetic, thermal, and mechanical properties. Compared to G-based hybrid and composite materials, G-based inorganic hybrid membrane (GIHM) offers enormous advantages ascribed to their facile synthesis, planar two-dimensional multilayer structure, high specific surface area, and mechanical stability, as well as their unique optical and mechanical properties. In this review, we report the recent advances in the technical fabrication and structure-specific applications of GIHMs with desirable thickness and compositions. In addition, the advantages and disadvantages of the methods utilized for creating GIHMs are discussed in detail. Finally, the potential applications and key challenges of GIHMs for future technical applications are mentioned. This journal is © The Royal Society of Chemistry 2015.


Wen S.,Beijing University of Chemical Technology | Wen S.,University of Illinois at Urbana - Champaign | Tan T.,Beijing University of Chemical Technology | Zhao H.,University of Illinois at Urbana - Champaign
Journal of Biotechnology | Year: 2013

Yarrowia lipolytica lipase Lip2 (YlLip2) is a highly versatile biocatalyst. However, its practical use is often hampered by its low stability. Here three complementary protein engineering strategies were used to improve the thermostability of this enzyme. The first strategy was error-prone PCR based directed evolution, which resulted in a YlLip2 variant with a 2.5-fold longer half-life of thermal inactivation at 50 °C compared to the wild-type enzyme. The second strategy was semi-rational design using the so-called B-factor iterative test (B-FIT), which led to the discovery of two thermostable YlLip2 variants that showed a half-life of thermal inactivation 2-fold and 5-fold longer than that of the wild-type enzyme, respectively, at 50 °C. The third strategy was to use site-directed mutagenesis to combinatorially combine all three thermostabilizing mutations identified in the first two strategies, which improved the half-life of thermal inactivation of YlLip2 by 7-fold compared to that of the wild-type enzyme. Such engineered lipases provide not only new insights on the protein structure and function relationship but also potentially useful catalysts for practical applications. © 2012 Elsevier B.V.


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.


Zhang W.,Beijing University of Chemical Technology | Zhang P.,Beijing University of Chemical Technology | Su Z.,Beijing University of Chemical Technology | Wei G.,University of Bremen
Nanoscale | Year: 2015

Molybdenum disulfide (MoS2) is a typical layered transition-metal dichalcogenide material, which has aroused a great deal of interest in the past few years. Recently, more and more attention has been focused on the synthesis and applications of MoS2-based nanocomposites. In this review, we aimed to present a wider view of the synthesis of various MoS2-based nanocomposites for sensor and biosensor applications. We highlighted the potential methods like self-assembly, hydrothermal reaction, chemical vapour deposition, electrospinning, as well as microwave and laser beam treatments for the successful preparation of MoS2-based nanocomposites. On the other hand, three representative types of detection devices fabricated by the MoS2-based nanocomposites, field-effect transistor, optical, and electrochemical sensors, were introduced in detail and discussed fully. The relationships between the sensing performances and the special nanostructures within the MoS2-based nanocomposites were presented and discussed. © 2015 The Royal Society of Chemistry.


News Article | December 12, 2016
Site: www.eurekalert.org

The pathway to zero-emission vehicles has taken two forks, one toward battery electric cars like the Tesla and the other toward fuel-cell-powered automobiles like the Toyota Mirai. The University of Delaware's Yushan Yan believes that fuel-cell vehicles are the way to go, because they best preserve the advantages of gasoline automobiles: low upfront cost, long driving range and fast refueling. But he also believes that a new fuel-cell technology may be necessary. For Yan, that approach is a new twist on traditional fuel cells, known as proton exchange membrane fuel cells, or PEMFCs, which rely on costly platinum-based catalysts. Yan and his research team are pursuing an alternative technology, the hydroxide exchange membrane fuel cell (HEMFC), because of its inherent cost advantages. He sees the rationale for this proposed switch as a matter of very simple arithmetic. "To make fuel-cell cars a reality, the DOE (Department of Energy) has set a system cost target of $30 per kilowatt, which translates into about $2,400 per car," he says. "Right now, the cost for PEMFCs is $52 per kilowatt, which is a big improvement over where the technology started." "But the catalyst accounts for only about $12 of that total, leaving $40 worth of other components. So even if we throw in some magic, we can't get the rest of the way down to the target of $30 with PEMFCs." Yan is co-author on a new paper published in the online version of Nature Nanotechnology that he views as a roadmap to a unified strategy for HEMFC zero-emission cars based on three arguments. "First, to become a commercial reality, fuel-cell engines have to be at cost parity with their gasoline counterparts," he says, "and moving from an acid platform with the PEMFC to a base system with the HEMFC will enable a collateral benefit in bringing down all of the associated costs. "Then, if we agree that this is the best approach, we need to get everyone in the HEMFC research community on board. If we want to succeed, we have to work together." Finally, Yan warns that it is insufficient just to have a lower cost. "It doesn't work to compare our results today with those from yesterday or the day before," he says. "To succeed commercially with HEMFCs, we have to match or beat the performance of PEMFCs. It's that simple -- we can't succeed without achieving performance parity." The paper, "Activity Targets for Nanostructured Platinum Group Metal-Free Catalysts in Hydroxide Exchange Membrane Fuel Cells," was co-authored by Brian P. Setzler, Zhongbin Zhuang, Jarrid A. Wittkopf, and Yushan Yan. Yan is Distinguished Engineering Professor in UD's Department of Chemical and Biomolecular Engineering, Setzler is a postdoctoral researcher in Yan's group, and Wittkopf is a doctoral student advised by Yan. Zhuang is a professor at Beijing University of Chemical Technology and a former postdoctoral researcher in Yan's group.


Xu Z.,Beijing University of Chemical Technology | He B.,China Agricultural University | Shen J.,China Agricultural University | Yang W.,Beijing University of Chemical Technology | Yin M.,Beijing University of Chemical Technology
Chemical Communications | Year: 2013

Different generations of perylenediimide-cored dendrimers with peripheral amine groups were synthesized. All these water-soluble dendrimers could rapidly internalize into live cells with high efficacy of gene transfection and low cytotoxicity. Increasing dendrimer generation increased their ability for gene transfection. This journal is © The Royal Society of Chemistry 2013.


Wan S.,Beijing University of Chemical Technology | Zheng Y.,China Agricultural University | Shen J.,China Agricultural University | Yang W.,Beijing University of Chemical Technology | Yin M.,Beijing University of Chemical Technology
ACS Applied Materials and Interfaces | Year: 2014

A novel spiropyran that responds to both extreme acid and extreme alkali and has an "on-off-on" switch is reported. Benzoic acid at the indole N-position and carboxyl group at the indole 6-position contribute to the extreme acid response. The ionizations of carboxyl and phenolic hydroxyl groups cause the extreme alkali response. Moreover, the fluorescent imaging in bacterial cells under extreme pH conditions supports the mechanism of pH response. (Chemical Equation Presented). © 2014 American Chemical Society.


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.


Cheng M.,Beijing University of Chemical Technology | Shi F.,Beijing University of Chemical Technology | Li J.,Sichuan University | Lin Z.,Sichuan University | And 5 more authors.
Advanced Materials | Year: 2014

Macroscopic supramolecular assembly is a promising method for manufacturing macroscopic, ordered structures for tissue-engineering scaffolds. A flexible spacing coating is shown to overcome undesired surface and size effects and to enable assembly of macroscopic cubes with host/guest groups. The assembled pairs disassembled upon introduction of competitive guest molecules, thereby demonstrating a multivalent assembly mechanism. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


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.


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.


Li X.-M.,Beijing University of Chemical Technology | Shen C.,Liming Research Institute of Chemical Industry | Li C.-X.,Beijing University of Chemical Technology
Journal of Chemical Thermodynamics | Year: 2012

Vapour pressures were measured using a quasi-static ebulliometer for the pseudo-binary mixtures of (water + ethanol), (water + methanol), and (methanol + ethanol) containing an alkanolammonium-based ionic liquid (IL), namely, mono-ethanolammonium formate ([HMEA][HCOO]) and di-ethanolammonium formate ([HDEA][HCOO]), respectively, with fixed IL mass fraction of 0.30 and over the temperature ranges of (292.12 to 371.13) K. The vapour pressures of the IL-containing ternary systems were favourably correlated using the NRTL model with an overall average absolute relative deviation (AARD) of 0.0082. Further, the salt effects of [HMEA][HCOO] and [HDEA][HCOO] on isobaric vapour liquid equilibria (VLE) of azeotrope and close boiling mixture, especially for the mixtures of (water + ethanol) and (methanol + ethanol), were investigated and compared with other ILs in terms of the x′-y phase diagrams predicted with the binary NRTL parameters. It is demonstrated that the relative volatilities of ethanol to water and ethanol to methanol are enhanced, and [HMEA][HCOO] might be used as a promising entrainer for the efficient separation of ethanol aqueous solution by special rectification. © 2012 Elsevier Ltd. All rights reserved.


Li J.,Beijing University of Chemical Technology | Guo K.,China Agricultural University | Shen J.,China Agricultural University | Yang W.,Beijing University of Chemical Technology | Yin M.,Beijing University of Chemical Technology
Small | Year: 2014

Functionalized fluorescent dyes have attracted great interest for the specific staining of subcellular organelles in multicellular organisms. A novel nanometer-sized water-soluble multi-functional squarylium indocyanine dye (D1) that contains four primary amines is synthesized. The dye exhibits good photostability, non-toxicity and biocompatibility. Isothermal titration calorimetry demonstrates that an affinity between D1 and DNA is higher than that between D1 and analogue of phospholipids. Analysis of circular dichroism spectra indicates that D1 targets to the DNA minor groove and aggregates to a helix. Because of the distinct affinity between the dye and subcellular organelles, the dye exhibits difunctional abilities to label the cell nuclei in fixed cells/tissue and the cell membranes in live cells/tissue. By combination of the two staining capabilities, the dye is further explored as a specific marker to distinguish apoptotic cells in live cells/tissue. The research opens a new way to design novel multifunctional dyes for life science applications. A water-soluble positively charged squarylium indocyanine dye exhibiting good photostability is synthesized. The difunctional dye selectively stains the cell nuclei in fixed cells/tissue and the cell membranes in live cells/tissue. The dye is further explored as a specific marker to detect apoptotic cells in live cells/tissue. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Cheng M.,Beijing University of Chemical Technology | Liu Q.,Beijing University of Chemical Technology | Ju G.,Beijing University of Chemical Technology | Zhang Y.,Beijing University of Chemical Technology | And 2 more authors.
Advanced Materials | Year: 2014

Superhydrophobic to neutral water droplets, superhydrophilic to acidic or basic. This double transition of surface wettability in response to a single stimulus - pH - is demonstrated for the first time. The smart surface is composed of a rough gold surface modified with a self-assembled monolayer (SAM) containing three thiols, HS(CH2)11CH3, HS(CH2)10COOH, and HS(CH2)11NH 2. A ternary diagram is generated that describes wettability as a function of the SAM composition and the pH of the surrounding solution. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Xiu K.M.,Beijing University of Chemical Technology | Yang J.J.,Sichuan University | Zhao N.N.,Beijing University of Chemical Technology | Li J.S.,Sichuan University | Xu F.J.,Beijing University of Chemical Technology
Acta Biomaterialia | Year: 2013

Controlled β-cyclodextrin (β-CD) core-based cationic star polymers have attracted considerable attention as non-viral gene carriers. Atom transfer radical polymerization (ATRP) could be readily used to produce the star-shaped polymers. The precise control of the number of initiation sites on the multifunctional core was of crucial importance to the investigation of the structure-property relationship of the functional star gene carriers. Herein, the controlled multiarm star polymers consisting of a β-CD core and various arm lengths of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) were prepared via ATRP from the chloroacetylated β-CD with well-designed initiation sites. Generally, these star polycations can condense plasmid DNA into 100-150 nm nanoparticles with positive zeta potentials of 30-40 mV at N/P ratios (star polymer to DNA ratios) of 17 or higher. The effects of arm numbers and lengths on gene delivery were investigated in detail. With a fixed length of the PDMAEMA arm, the fewer the number of arms, the lower the toxicity. The star polycations with suitable arm numbers possess the best transfection ability. On the other hand, with the fixed molecular weights, the shorter the arms, the lower the toxicity. The polymers with 21 arms possess the lowest transfection efficiency. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Yao J.,Peking Union Medical College | Yao J.,Beijing Key Laboratory of Clinical Study on Anticancer Molecular Targeted Drugs | Liu L.,Beijing University of Chemical Technology | Yang M.,Beijing University of Chemical Technology
Gene | Year: 2014

Aim: Interleukin-23 (IL-23) and IL-23 receptor (IL23R) play an important role during the T-helper 17 (Th17) cell-mediated inflammatory process as well as pathogenesis of multiple cancers. Several IL-23R single nucleotide polymorphisms (SNPs), especially rs6682925, rs10889677 and rs1884444 polymorphisms, are considered to have significant impacts on susceptibility of multiple cancers. A number of case-control studies have explored the role these genetic polymorphisms in development of carcinogenesis, but the conclusions are inconsistent. Therefore, we conducted this meta-analysis to systematically investigate the associations between the three genetic variants and multiple cancer risk. Methods: A total of ten studies are eligible (12,211 patients and 14,650 controls). Pooled odds ratios (ORs) and the 95% confidence interval (95% CI) were appropriately calculated using either fixed-effect model or random-effect model. Results: Significant associations between rs6682925 or rs10889677 polymorphism and cancer risk were found (OR. = 1.11, 95% CI. = 1.03-1.21, P= 0.007; or OR. = 0.85, 95% CI. = 0.71-0.92, P= 0.001). However, there was no such association between rs1884444 genotypes and cancer susceptibility (P>. 0.05). Conclusion: These findings reveal that the IL-23R rs6682925 and rs10889677 genetic variants play a more important part in pathogenesis of multiple cancers. © 2013 Elsevier B.V.


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.


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.


Mullner T.,University of Marburg | Zankel A.,University of Graz | Lv Y.,Beijing University of Chemical Technology | Svec F.,Beijing University of Chemical Technology | And 2 more authors.
Advanced Materials | Year: 2015

A general, model-free, quantitative approach to the key morphological properties of a porous polymer monolith is presented. After 3D reconstruction, image-based analysis delivers detailed spatial and spatially correlated information on the structural heterogeneities in the void space and the polymer skeleton. Identified heterogeneities, which limit the monolith's performance in targeted applications, are traced back to the preparation process. © 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim.


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.


Zhang F.,Beijing University of Chemical Technology | Zhang F.,Tsinghua University | Cao H.,Tsinghua University | Yue D.,Beijing University of Chemical Technology | And 2 more authors.
Inorganic Chemistry | Year: 2012

Here, we report a three-layer-structured hybrid nanostructure consisting of transition metal oxide TiO 2 nanoparticles sandwiched between carbonaceous polymer polyaniline (PANI) and graphene nanosheets (termed as PTG), which, by simultaneously hindering the agglomeration of TiO 2 nanoparticles and enhancing the conductivity of PTG electrode, enables fast discharge and charge. It was demonstrated that the PTG exhibited improved electrochemical performance compared to pure TiO 2. As a result, PTG nanocomposite is a promising anode material for highly efficient lithium ion batteries (LIBs) with fast charge/discharge rate and high enhanced cycling performance [discharge capacity of 149.8 mAh/g accompanying Coulombic efficiency of 99.19% at a current density of 5C (1000 mA/g) after 100 cycles] compared to pure TiO 2. We can conclude that the concept of applying three-layer-structured graphene-based nanocomposite to electrode in LIBs may open a new area of research for the development of practical transition-metal oxide graphene-based electrodes which will be important to the progress of the LIBs science and technology. © 2012 American Chemical Society.


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.


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.


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.


Liang X.,Beijing University of Chemical Technology | Xiao J.,Beijing University of Chemical Technology | Chen B.,Beijing University of Chemical Technology | Li Y.,Tsinghua University
Inorganic Chemistry | Year: 2010

A facile one-step strategy has been developed for preparing monodisperse CeO2 mesoporous spheres with high surface areas, uniform size distributions, and well-defined pore topologies. These mesoporous spheres have been demonstrated to be catalytically stable and active for CO oxidation. © 2010 American Chemical Society.


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.


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.


Li Q.,Beijing University of Chemical Technology | Liu F.,Beijing University of Chemical Technology | Lu C.,Beijing University of Chemical Technology | Lin J.-M.,Tsinghua University
Journal of Physical Chemistry C | Year: 2011

A novel method was used to synthesize triangular gold nanoparticles (AuNPs) (i.e., trisodium citrate reduction of HAuCl4 in the presence of nonionic fluorosurfactant). The as-prepared triangular AuNPs owned higher surface-to-volume ratio and more active surface sites compared to spherical AuNPs, which facilitated the active oxygen intermediates generation and electron-transfer processes on the surface of triangular AuNPs. Therefore, it was first found that triangular AuNPs displayed greater catalytic activity (ca. 125-fold) toward luminol chemiluminescence (CL) than spherical AuNPs. More interestingly, ultratrace aminothiols (ca. 0.1 nM) can interrupt the formation of the active oxygen intermediates by forming Au-S covalent bonds on the surface of triangular AuNPs, resulting in a great decrease in CL intensity, while the other biomolecules including 19 standard amino acids, alcohols, organic acids, and saccharides have no effect on triangular AuNPs-catalyzed luminol CL signals. These significant features of triangular AuNPs-catalyzed luminol CL were the ability to detect aminothiols in the presence of other essential amino acids and biomolecules. © 2011 American Chemical Society.


Zhao J.,Beijing University of Chemical Technology | Chen J.,Beijing University of Chemical Technology | Xu S.,Beijing University of Chemical Technology | Shao M.,Beijing University of Chemical Technology | And 6 more authors.
Advanced Functional Materials | Year: 2014

A hierarchical nanostructure composed of NiMn-layered double hydroxide (NiMn-LDH) microcrystals grafted on carbon nanotube (CNT) backbone is constructed by an in situ growth route, which exhibits superior supercapacitive performance. The resulting composite material (NiMn-LDH/CNT) displays a three-dimensional architecture with tunable Ni/Mn ratio, well-defined core-shell configuration, and enlarged surface area. An electrochemical investigation shows that the Ni3Mn1-LDH/CNT electrode is rather active, which delivers a maximum specific capacitance of 2960 F g-1 (at 1.5 A g-1), excellent rate capability (79.5% retention at 30 A g -1), and cyclic stability. Moreover, an all-solid-state asymmetric supercapacitor (SC) with good flexibility is fabricated by using the NiMn-LDH/CNT film and reduced graphene oxide (RGO)/CNT film as the positive and negative electrode, respectively, exhibiting a wide cell voltage of 1.7 V and largely enhanced energy density up to 88.3 Wh kg-1 (based on the total weight of the device). By virtue of the high-capacity of pseudocapacitive hydroxides and desirable conductivity of carbon-based materials, the monolithic design demonstrated in this work provides a promising approach for the development of flexible energy storage systems. A smart hierarchical nanostructure composed of NiMn-LDH shell and carbon nanotube backbone core is designed and fabricated using a facile in situ synthetic route. By virtue of the desirable features of each component and the well-defined 3D configuration, the resulting NiMn-LDH/CNT composite electrode displays excellent pseudocapacitive behavior in asymmetric flexible supercapacitors. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


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.


Jin Y.,Beijing University of Chemical Technology | Fang M.,Tsinghua University | Jia M.,Beijing University of Chemical Technology
Applied Surface Science | Year: 2014

In this work, graphene-polyaniline nanofiber (G/PANI-F) composite is prepared through a new and one-pot method that includes the reduction of graphene oxide (GO) by aniline and then followed by in-situ polymerization. Aniline plays the two roles in this method: as a chemical reducing agent to reduce GO to graphene and as a monomer to prepare polyaniline nanofiber (PANI-F). Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectra, X-ray photoelectron spectroscopy and transmission electron microscopy are employed to confirm that GO can be reduced by aniline and PANI-F can be deposited on the surface of graphene. The electrochemical properties of G/PANI-F composite electrode are measured by using cyclic voltammetry, galvanostatic charge-discharge test and electrochemical impedance spectroscopy. The G/PANI-F composite electrode exhibits enhanced specific capacitance of 965 F g -1 at 0.5 A g-1 and the capacity retention is 90% after 2000 cycles. © 2014 Elsevier B.V.


Zhang M.,Beijing University of Chemical Technology | Yao Q.,Beijing University of Chemical Technology | Guan W.,Beijing University of Chemical Technology | Lu C.,Beijing University of Chemical Technology | Lin J.-M.,Tsinghua University
Journal of Physical Chemistry C | Year: 2014

The development of a new heterogeneous Fenton-like catalyst is highly desired. Herein, we reported a simple and efficient method for the preparation of colloidal nanocomposites consisting of carbon dots and dodecylbenzenesulfonate (DBS)-layered double hydroxides (LDHs). The resulting nanocatalyst can function as an effective heterogeneous Fenton-like catalyst for the decomposition of acidified H2O2 to generate abundant hydroxyl radicals (·OH). With the aid of chemiluminescence (CL) technique, electron spin resonance (ESR) measurements and ion chromatography (IC) separation technique, we demonstrated that the unique structural configuration of the carbon dot-DBS-LDH nanocomposites was responsible for the highly efficient catalytic activities toward H2O2 decomposition. The fabricated material introduced a novel family of Fenton-like nanocatalysts with environmental friendliness, cost effectivity, and superior efficiency for the decomposition of H2O2 to ·OH radicals. Such heterogeneous Fenton-like catalyst could realize the degradation of DBS without any external energy input, showing a promising application for the oxidative degradation of organic contaminants in wastewater treatment applications. © 2014 American Chemical Society.


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.


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.


Sun J.,Stanford University | Sun J.,Beijing University of Chemical Technology | Zheng G.,Stanford University | Lee H.-W.,Stanford University | And 6 more authors.
Nano Letters | Year: 2014

High specific capacity battery electrode materials have attracted great research attention. Phosphorus as a low-cost abundant material has a high theoretical specific capacity of 2596 mAh/g with most of its capacity at the discharge potential range of 0.4-1.2 V, suitable as anodes. Although numerous research progress have shown other high capacity anodes such as Si, Ge, Sn, and SnO2, there are only a few studies on phosphorus anodes despite its high theoretical capacity. Successful applications of phosphorus anodes have been impeded by rapid capacity fading, mainly caused by large volume change (around 300%) upon lithiation and thus loss of electrical contact. Using the conducting allotrope of phosphorus, "black phosphorus" as starting materials, here we fabricated composites of black phosphorus nanoparticle-graphite by mechanochemical reaction in a high energy mechanical milling process. This process produces phosphorus-carbon bonds, which are stable during lithium insertion/extraction, maintaining excellent electrical connection between phosphorus and carbon. We demonstrated high initial discharge capacity of 2786 mAh·g-1 at 0.2 C and an excellent cycle life of 100 cycles with 80% capacity retention. High specific discharge capacities are maintained at fast C rates (2270, 1750, 1500, and 1240 mAh·g -1 at C/5, 1, 2, and 4.5 C, respectively). © 2014 American Chemical Society.


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.


Zhou J.,Beijing University of Chemical Technology | Ma L.,Beijing University of Chemical Technology | Ma L.,Rice University | Song H.,Beijing University of Chemical Technology | And 2 more authors.
Electrochemistry Communications | Year: 2011

Copper oxide hollow nanoparticles/graphene-nanosheet composites are prepared using the Kirkendall-effect approach. The composites exhibit a durable lifetime cycle at high rates. The reversible capacity of the material attains 640 mAhg -1 at 50 mAg -1 and the capacity retention is ca. 96% when the current density is increased 10 times. At 1 Ag -1 (ca. 1.7 C), the reversible capacity reaches 485 mAhg-1 and remains at 281 mAhg -1 after 500 cycles, indicating that the capacity fading is less than 0.4 mAhg -1 per cycle. This excellent electrochemical performance can be attributed to the hollow interior of CuO nanoparticles as well as synergistic effect between CuO and graphene. © 2011 Elsevier B.V. All rights reserved.


Hu J.,Beijing University of Chemical Technology | Chen J.,Tsinghua University | Mi J.,Beijing University of Chemical Technology
Industrial and Engineering Chemistry Research | Year: 2012

In this work, a density functional approach was applied to describe the interfacial thermodynamic properties of CO 2 binary mixtures including CO 2 + heptane, CO 2 + acetone, CO 2 + ethanol, and CO 2 + water. In the theoretical model, the first-order mean spherical approximation statistical associating fluid theory (FMSA-SAFT) was incorporated to describe the chemical potential of the bulk term, while, for inhomogeneous potential, the modified fundamental measure theory (MFMT) was employed to describe the hard sphere contribution, and a weighted density approximation was adopted for the attractive contribution. Without any adjustable parameter, the theoretical calculations have been well-testified by the available experimental data, showing a good predictive capability of the theory to the interfacial structure and tensions of CO 2 binary mixtures with nonpolar, polar, and associating fluids. © 2011 American Chemical Society.


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.


Ji K.,Beijing University of Chemical Technology | Deng J.,Beijing University of Chemical Technology | Zang H.,Tianjin Polytechnic University | Han J.,Tohoku University | And 2 more authors.
Applied Catalysis B: Environmental | Year: 2015

Three-dimensionally ordered macroporous (3DOM) InVO4-BiVO4 (InBi-3D) and its supported noble metal M nanoparticles (xM/InBi-3D; x=0.08-0.13wt%; M=Au, Ag, Pd, Pt) were prepared using the polymethyl methacrylate-templating and polyvinyl alcohol- or polyvinyl pyrrolidone-assisted reduction methods, respectively. Physical properties of the materials were characterized by a number of analytical techniques. Photocatalytic activities of the xM/InBi-3D samples were evaluated for the degradation of rhodamine B (RhB), methylene blue (MB), and their mixture. It is found that the as-fabricated samples possessed a surface area of 17-30m2/g, a M particle size of 2.5-3.8nm, and a bandgap energy of 2.50-2.56eV. The xM/InBi-3D photocatalysts showed high activities for the degradation of RhB, MB, and RhB+MB in the presence of a small amount of H2O2 under visible-light irradiation, among which complete degradation of RhB, MB, and RhB+MB was achieved within 50, 90, and 120min over 0.08wt% Au/InBi-3D, respectively. The degradation of MB and RhB fellow the zero- and first-order reaction mechanisms with respect to dye concentration, respectively. It is concluded that the high photocatalytic efficiency of the Au-loaded sample in the removal of organic dyes was associated with its high surface area, high-quality 3DOM hierarchical architecture, InVO4-BiVO4 composite, and high dispersion of gold nanoparticles. © 2014 Elsevier B.V.


Li Q.,Beijing University of Chemical Technology | Shang F.,Beijing University of Chemical Technology | Lu C.,Beijing University of Chemical Technology | Zheng Z.,Chinese Research Academy of Environmental Sciences | Lin J.-M.,Tsinghua University
Journal of Chromatography A | Year: 2011

Our recent study demonstrates the synthesized triangular gold nanoparticles (AuNPs) by trisodium citrate reduction of HAuCl 4 in the presence of nonionic fluorosurfactant (FSN) could display stronger catalytic activity towards luminol-chemiluminescence (CL) than spherical AuNPs. Ultratrace aminothiols may cause a great decrease in CL intensity of the triangular AuNPs-luminol CL system. In this article, we utilize the as-prepared triangular AuNPs as novel postcolumn CL reagents to explore a simple high-performance liquid chromatography (HPLC)-CL method for the determination of low molecular weight aminothiols (i.e., cysteine, homocysteine, glutathione, cysteinylglycine and glutamylcysteine). The as-prepared triangular AuNPs were easier to synthesize, stable at a wider pH range and high ionic strength, and highly selective and sensitive towards reduced aminothiols. The detection limits at a signal-to-noise ratio of 3 for cysteine, homocysteine, glutathione, cysteinylglycine and glutamylcysteine were 0.016, 0.08, 0.1, 0.04 and 0.1pmol, respectively. Recoveries from spiked urine and plasma samples were 95.7-104.3%. The applicability of the proposed method has been validated by determining these low molecular weight aminothiols in human urine and plasma samples with satisfactory results, and thus it will have great potential application in clinical diagnosis. © 2011 Elsevier B.V.


Liu Z.,Beijing University of Chemical Technology | Zhang S.,Beijing University of Chemical Technology | Li J.,Tsinghua University | Ma L.,CAS Institute of High Energy Physics
Applied Catalysis B: Environmental | Year: 2013

A series of MoO3-doped CeO2/TiO2 catalysts prepared by the impregnation method were investigated for the selective catalytic reduction of NOx by NH3(NH3-SCR). It was found that CeO2-MoO3/TiO2 catalyst is much more active than CeO2/TiO2 for NH3-SCR and the optimum MoO3 loading is 5%. The mechanistic cause of the promoting effect of MoO3 on the activity of CeO2/TiO2 catalyst for NH3-SCR was studied using in situ diffuse reflectance infrared transform spectroscopy (DRIFTS). The results revealed that the highly dispersed molybdenum on CeO2-MoO3/TiO2 catalyst not only resulted in more Brønsted acid sites formed on the catalyst surface, but also reduced the thermal stability of the inactive nitrate specie, leaving more active sites available for the adsorption of NH3, both of which are favorable for the promotion of SCR activity. © 2013 Elsevier B.V.


Xiao Q.,Beijing University of Chemical Technology | Gao H.,Beijing University of Chemical Technology | Yuan Q.,Beijing University of Chemical Technology | Lu C.,Beijing University of Chemical Technology | Lin J.-M.,Tsinghua University
Journal of Chromatography A | Year: 2013

Herein, a new postcolumn resonance light scattering (RLS) detection approach coupled with high-performance liquid chromatography (HPLC) was developed to detect cysteine and homocysteine. In the established system, the fluorosurfactant-capped gold nanoparticles (AuNPs) were first employed as postcolumn RLS reagents. The detection principle was based on the enhancement of RLS intensity of AuNPs upon the addition of cysteine/homocysteine. The RLS signals were detected by a common fluorescence detector at λEX=λEM=560nm. The linear ranges for both cysteine and homocysteine were in the range of 5.0-50μM. The detection limits were 5.9pmol for cysteine and 12pmol for homocysteine at a signal-to-noise ratio of 3. HPLC separation and RLS detection conditions were optimized in detail. The applicability of the proposed method has been validated by detecting cysteine and homocysteine in human urine samples. Recoveries from spiked urine samples were 95.0-103.0%. © 2012 Elsevier B.V.


Zhang C.,Beijing University of Chemical Technology | Luo L.,Beijing University of Chemical Technology | Luo J.,Tsinghua University | Evans D.G.,Beijing University of Chemical Technology | Sun X.,Beijing University of Chemical Technology
Chemical Communications | Year: 2012

Density gradient ultracentrifuge separation has been employed as a process-analysis microsystem combining a microreactor and a separator. As a paradigm, intermediates formed after tens of seconds in the galvanic replacement of Ag nanoplates in high concentrated AuCl 4 - solution are captured, providing evidence of the mechanism of the reaction, which is difficult to obtain in other ways. © 2012 The Royal Society of Chemistry.


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.


Ben T.,Jilin University | Li Y.,Jilin University | Zhu L.,Jilin University | Zhang D.,Jilin University | And 5 more authors.
Energy and Environmental Science | Year: 2012

A series of carbonized PAF-1s were obtained with enhanced gas storage capacities and isosteric heats of adsorption (Qst for short). Especially, PAF-1-450 can adsorb 4.5 mmol g-1 CO2 at 273 K and 1 bar. Moreover, it also exhibits excellent selectivity over other gases. On the basis of single component isotherm data, the dual-site Langmuir-Freundlich adsorption model-based ideal adsorption solution theory (IAST) prediction indicates that the CO2/N2 adsorption selectivity is as high as 209 at a 15/85 CO2/N2 ratio. Also, the CO2/CH4 adsorption selectivity is in the range of 7.8-9.8 at a 15/85 CO2/CH4 ratio at 0 < p < 40 bar, which is highly desirable for landfill gas separation. The calculated CO2/H2 adsorption selectivity is about 392 at 273 K and 1 bar for 20/80 CO2/H2 mixture. Besides, these carbonized PAF-1s possess excellent physicochemical stability. Practical applications in capture of CO2 lie well within the realm of possibility. This journal is © The Royal Society of Chemistry 2012.


Bai S.,Beijing University of Chemical Technology | Chen Q.,Beijing University of Chemical Technology | Lu C.,Beijing University of Chemical Technology | Lin J.-M.,Tsinghua University
Analytica Chimica Acta | Year: 2013

In general, the reduction of disulfide bonds with tris(2-carboxyethyl)phosphine (TCEP) is performed using off-line operation, which is not only time-consuming but also vulnerable to the spontaneous reoxidation of thiols during sample preparation and subsequent analysis procedures. To the best of our knowledge, there has been not any case on the on-line reduction for biological disulfides coupled with high performance liquid chromatography (HPLC). In this study, these obstacles are overcome by packing Zn(II)-TCEP complexes into a home-made column. The as-synthesized Zn(II)-TCEP complexes enable efficient reduction of disulfide bonds at pH 3.0. This acidic pH value was compatible with that of the mobile phase for HPLC separation of thiols and disulfides. Therefore, using fluorosurfactant-prepared triangular gold nanoparticles as HPLC postcolumn specific chemiluminescence (CL) reagents for thiols, the feasibility of the established on-line reduction column has been confirmed for the direct identification of both thiols and disulfides by incorporating this reduction column into a single chromatographic separation. Detection limits for these analytes range from 8.3 to 25.4 nM and the linear range in a log-log plot can comprise three orders of magnitude. Finally, the utility of this automated on-line reduction of disulfides-HPLC-CL system has been demonstrated for the reliable determination of thiols and disulfides in human urine and plasma samples. © 2013 Elsevier B.V.


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.


Lei M.,Beijing University of Chemical Technology | Zhang W.,Beijing University of Chemical Technology | Chen Y.,Beijing University of Chemical Technology | Tang Y.,Beijing Institute of Fashion Technology
Organometallics | Year: 2010

In this work, H2 activation processes in hydrogenation of ketones catalyzed by late transition metal-ligand bifunctional catalysts have been studied using the DFT method. For systems A (RuH2diphosephine/ diamine complex) and B (Ru-η5-Cp*-l,2-diamine complex), the dihydrogen activation process in neutral and basic conditions (path 1) consisted of two steps: H2 coordination and H-H cleavage. However, dihydrogen activations catalyzed by complexes C-F (Ru- η6-arene and Rh/ Ir-cyclopentadiene complexes) along path 1 consist of only H-H cleavage due to the absence of H2 coordination. Thus, systems C-F have higher energy barriers (△G >27 kcal/mol) for dihydrogen activation than systems A and B. However, for systems C-F under acidic conditions, dihydrogen activation (path 2) consists of the two steps involving H2 coordination; thus the dihydrogen activation barriers decrease greatly, resulting in an easy splitting of H2. These results agree well with experiments. In the conversion from transfer hydrogenation to H2 hydrogenation for C-F, the protonation of 16e complex MN C-F changes the N2-M1 -Y3 (Y = N or O) delocalized jr-bond into a M1-Y3 localized jr-bond. Therefore, the 16e complexes, which can provide a vacant site for H2 coordination, tend to perform H2 hydrogenation. © 2010 American Chemical Society.


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.


Zhang M.,Beijing University of Chemical Technology | Han D.,Beijing University of Chemical Technology | Lu C.,Beijing University of Chemical Technology | Lin J.-M.,Tsinghua University
Journal of Physical Chemistry C | Year: 2012

In this study, it was found that sodium dodecylbenzene sulfonate (SDBS)-modified LDHs can significantly enhance the chemiluminescence (CL) from the periodate-hydrogen peroxide (IO 4 --H 2O 2) CL reaction. Using CL spectrum, powder X-ray diffraction measurements, scanning electron microscope images, transmission electron microscopy images, Fourier transform infrared spectroscopy, the quenchers for reactive oxygen species, and elemental analysis techniques, the enhancement mechanism of SDBS-modified LDHs on the IO 4 --H 2O 2 CL was discussed in detail. The results showed that the adsorbed SDBS on the external surface of SDBS-modified LDHs made the disappearance of electrostatic repulsion between anionic surfactants and anionic CL reactants, resulting in the concentrating of anionic CL reactants on the adsorbed surfactant layers of SDBS-modified LDHs and the higher CL efficiency in LDH microenvironment. The success of this work expands currently limited applications of anionic surfactants in CL field. © 2012 American Chemical Society.


Zhang L.,Beijing University of Chemical Technology | Zhang Z.,Beijing University of Chemical Technology | Lu C.,Beijing University of Chemical Technology | Lin J.-M.,Tsinghua University
Journal of Physical Chemistry C | Year: 2012

The interlamellar dodecylbenzene sulfonate (DBS) in layered double hydroxides (LDHs) can amplify an ultraweak chemiluminescence (CL) from Fenton-like reaction (Co(II) + H 2O 2 + OH -). The CL enhancement mechanism of the intercalated DBS on the H 2O 2-Co(II) CL was investigated by CL spectrum, radical scavengers, powder X-ray diffraction measurements, scanning electron microscope images, transmission electron microscopy images, Fourier transform infrared spectroscopy, electronic spinning resonance measurements, and elemental analysis techniques. The hydrophobic microenvironment of the intercalated DBS in LDHs facilitated the formation of hydroxyl radical (•OH) by the reaction of Co(II) with H 2O 2 in alkaline medium. The abundant •OH radical can easily react with the intercalated DBS in LDHs to form sulfite radical (•SO 3 -). The recombination of •SO 3 - radical could generate an intermediate as the excited sulfur dioxide molecules (SO 2*), which generated strong CL emission centered at ∼430 nm. Our experiments illustrated a powerful use of surfactant-intercalated LDHs in CL studies and could have potential applications in the quantitative determination of radical production. © 2012 American Chemical Society.


Zhao H.,Tsinghua University | Zhao H.,Beijing University of Chemical Technology | Fu H.,Tsinghua University | Qiao R.,Beijing University of Chemical Technology
Journal of Organic Chemistry | Year: 2010

A simple copper-catalyzed direct amination of ortho-functionalized haloarenes (2-halobenzoic acid, 2-halobenzamide, and N-(2-bromophenyl)acetamide derivatives) has been developed with use of NaN3 as the amino source in ethanol, and the corresponding ortho-functionalized aromatic amines were synthesized in good to excellent yields. The protocol undergoes one-pot Ullmann-type coupling of ortho-functionalized haloarenes with NaN3 to lead to ortho-functionalized azidoarenes, followed by reduction with ethanol. © 2010 American Chemical Society.


Lu C.,Beijing University of Chemical Technology | Li J.,Beijing University of Chemical Technology | Yang Y.,Beijing University of Chemical Technology | Lin J.-M.,Tsinghua University
Talanta | Year: 2010

Peroxymonocarbonate (HCO4 -) was produced by the online reaction of bicarbonate with hydrogen peroxide. A strong chemiluminescence (CL) was observed when HCO4 - reacted with AuCl4 - without any special CL reagent. When bisphenol A (BPA) was added to AuCl4 --HCO4 - CL system, the CL emission was inhibited significantly. This new CL system was developed as a flow-injection method for the determination of BPA. Under the optimum experimental conditions, the inhibited CL intensity was linearly related to the concentration of BPA from 0.3 to 80 μM (R = 0.9958). The detection limit of BPA was 0.08 μM. The relative standard deviation for 12 repeated measurements of 1.0 μM BPA was 2.9%. The interferences of some cationic ions can be removed by an online cation-exchange column. The applicability of the present CL system was demonstrated for the sensitive and selective determination of BPA in real samples (mineral water bottle, baby bottle, beverage bottle and polycarbonate container). Based on the CL spectrum, UV-visible adsorption spectra, and the quenching effect of reactive oxygen species scavengers, a possible CL mechanism was proposed. © 2010 Elsevier B.V. All rights reserved.


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.


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.


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.


Ma X.,Beijing University of Chemical Technology | Tang Y.,Beijing Institute of Fashion Technology | Lei M.,Beijing University of Chemical Technology
Organometallics | Year: 2013

A DFT study on the carboxylation of hafnocene and ansa-zirconocene dinitrogen complexes with CO2 indicates that the most favorable initial CO2 insertion into M-N (M = Hf, Zr) proceeds by a stepwise path rather than a concerted [2 + 2] path. The calculated results explain the regioselectivity of the N-C formation in experiments. In addition, a comparative analysis of ring tension and charge distribution unveils the different activities of N-N bond cleavage in the CO and CO2 direct N-C bond formation reactions. © 2013 American Chemical Society.


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.


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_(1-x)Al_(x)(OH)_(2)(CO_(3))_(x/2).mH_(2)O. The inorganic layers of this material can play a physical shielding role against UV, and the metal elements dispersed on the layer as well as the interlayer anion can play a great role in the chemical absorbing. In addition, by controlling the particle size and the amount of the layers, UV light can be effectively shielded by multi-level reflection and absorption of the multi-level layered structure. Therefore, the material with multi-level chemical and physical shielding properties has a good UV barrier effect for the anti-ageing asphalt, and could significantly increase its UV resistance properties.


Yu Y.,Beijing University of Chemical Technology | Yang Q.,Beijing University of Chemical Technology | Teng D.,Beijing University of Chemical Technology | Yang X.,Beijing University of Chemical Technology | Ryu S.,Chungnam National University
Electrochemistry Communications | Year: 2010

Reticular tin nanoparticle-dispersed carbon (Sn/C) nanofibers were fabricated by stabilization of electrospun SnCl4/PAN composite fibers and subsequent carbonization at different temperatures. These Sn/C composite nanofibers used as anode materials for rechargeable lithium-ion batteries (LIBs) show that the Sn/C nanofibers at 700 and 850 °C present much higher charge (785.8 and 811 mA h g-1) and discharge (1211.7 and 993 mA h g-1) capacities than those at 550 and 1000 °C and the as-received CNFs at 850 °C, corresponding to coulombic efficiencies of 64.9% and 81.7%, respectively. The superior electrochemical properties of the intriguing Sn/C nanofibers indicate a promising application in high performance Li-ion batteries. © 2010 Elsevier B.V. All rights reserved.


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.


« 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 | November 20, 2015
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.


Liang H.,Beijing University of Chemical Technology | Yuan Q.,Beijing University of Chemical Technology | Vriesekoop F.,Harper Adams University College | Lv F.,Beijing University of Chemical Technology
Food Chemistry | Year: 2012

Essential oils (EOs) from plants are considered to be a safer alternative when compared to synthetic antimicrobial food additives. However, a major drawback of many EOs is their hydrophobic nature, which makes them insoluble in water based media and matrices. Although cyclodextrins (CDs) can increase the solubility of EO compounds, the effects of CDs on the antimicrobial activity of EOs have not been reported. In this paper, four different EO compounds (carvacrol, eugenol, linalool and 2-pentanoylfuran) were chosen to study the influence of CDs on the solubility and antimicrobial activity on bacteria and yeast. The greatest enhancement with regards to solubility of the four test compounds was achieved by hydroxypropyl-β-CD. In most instances, not only were the minimal antimicrobial concentrations of EO compounds decreased, but the interactivity of two combined EO compounds could be strengthened by the co-addition of CDs. Furthermore, the combination of carvacrol with hydroxypropyl-β-CD caused a marked change in the major membrane lipid composition of all microorganisms investigated; while scanning electron microscopy revealed that cellular integrity was significantly affected by 2× MIC, ultimately resulting in cell lysis. © 2012 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.


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.


Liu Y.,Beijing University of Chemical Technology | Dai H.,Beijing University of Chemical Technology | Du Y.,Beijing University of Technology | Deng J.,Beijing University of Chemical Technology | And 3 more authors.
Journal of Catalysis | Year: 2012

Three-dimensionally ordered macroporous (3DOM) single-phase rhombohedral perovskite-type oxide LaMnO 3 materials with nanovoid skeletons were prepared using the poly(methyl methacrylate)-templating methods with the assistance of surfactant (poly(ethylene glycol) (PEG) or triblock copolymer (Pluronic P123)). The nature of surfactant influenced the pore structure of the LaMnO 3 sample. The use of PEG400 alone led to a 3DOM-structured LaMnO 3 without nanovoid skeletons; with the addition of PEG400 and P123, however, one could prepare LaMnO 3 samples with high-quality 3DOM structures, nanovoid skeletons, and high surface areas (37-39 m 2/g). Under the conditions of toluene concentration = 1000 ppm, toluene/O 2 molar ratio = 1:400, and space velocity = 20,000 mL/(g h), the porous LaMnO 3 samples were superior to the bulk counterpart in catalytic performance, with the nanovoid-containing 3DOM-structured LaMnO 3 catalyst performing the best (the temperatures for toluene conversions of 50% and 90% were 222-232 and 243-253 °C, respectively). The apparent activation energies (57-62 kJ/mol) over the 3DOM-structured LaMnO 3 catalysts were much lower than that (97 kJ/mol) over the bulk LaMnO 3 catalyst. We believe that the excellent performance of the 3D macroporous LaMnO 3 materials in catalyzing the combustion of toluene might be due to factors such as large surface area, high oxygen adspecies concentration, good low-temperature reducibility, and unique nanovoid-containing 3DOM structure of the materials. © 2011 Elsevier Inc. All rights reserved.


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.


Liang L.,Beijing University of Chemical Technology | Liang L.,TU Ilmenau | Xu Y.,Beijing University of Chemical Technology | Lei Y.,TU Ilmenau | And 2 more authors.
Nanoscale | Year: 2014

Three-dimensional (3D) porous composite aerogels have been synthesized via an innovative in situ hydrothermal method assisted by a freeze-drying process. In this hybrid structure, one-dimensional (1D) AgVO3 nanowires are uniformly dispersed on two-dimensional (2D) graphene nanosheet surfaces and/or are penetrated through the graphene sheets, forming 3D porous composite aerogels. As cathode materials for lithium-ion batteries, the composite aerogels exhibit high discharge capacity, excellent rate capability, and good cycling stability. This journal is © the Partner Organisations 2014.


Liu Y.,Beijing University of Chemical Technology | Dai H.,Beijing University of Chemical Technology | Deng J.,Beijing University of Chemical Technology | Zhang L.,Beijing University of Chemical Technology | Au C.T.,Hong Kong Baptist University
Nanoscale | Year: 2012

Three-dimension ordered macroporous (3D-OM) bismuth vanadates with a monoclinic crystal structure and high surface area (18-24 m 2 g -1) have been prepared using ascorbic acid (AA)- or citric acid (CA)-assisted poly(methyl methacrylate) (PMMA)-templating strategy with bismuth nitrate and ammonium metavanadate as the metal sources, HNO 3 as the pH adjuster and ethylene glycol and methanol as the solvent. The materials were characterized by a number of analytical techniques. The photocatalytic performance of the porous BiVO 4 samples was evaluated for the degradation of phenol in the presence of a small amount of H 2O 2 under visible light illumination. The effects of the initial phenol concentration and the H 2O 2 amount on the photocatalytic activity of the photocatalyst were examined. It is shown that the chelating agent, AA or CA, and the amount in which it is added had a significant impact on the quality of the 3D-OM structure, with a "(Bi + V):chelating agent" molar ratio of 2:1 being the most appropriate. Among the as-prepared BiVO 4 samples, the one with a surface area of ca. 24 m 2 g -1 showed the best visible light-driven photocatalytic performance for phenol degradation (phenol conversion = ca. 94% at phenol concentration = 0.1 mmol L -1 and in the presence of 0.6 mL H 2O 2). A higher phenol conversion could be achieved within the same reaction time if the phenol concentration in the aqueous solution was lowered, but an excess amount of H 2O 2 was not a favorable factor for the enhancement of the catalytic activity. It is concluded that the excellent photocatalytic activity of 3D-OM BiVO 4 is due to the high quality 3D-OM structured BiVO 4 that has a high surface area and surface oxygen vacancy density. We are sure that the 3D-OM material is a promising photocatalyst for the removal of organics from wastewater under visible light illumination. © 2012 The Royal Society of Chemistry.


Fu Y.,Beijing Institute of Technology | Song J.,Beijing Composite Materials Co. | Song J.,Beijing University of Chemical Technology | Zhu Y.,Beijing Institute of Technology | Cao C.,Beijing Institute of Technology
Journal of Power Sources | Year: 2014

Amorphous mesoporous Ni(OH)2 nanoboxes are synthesized by template-engaged routes. The nanoboxes are characterized by SEM, TEM, XRD, XPS and BET methods. The nanoboxes have uniform morphology of 450-500 nm, high surface area of 214.6 m2 g-1 and mesoporous structure of 4-20 nm. Electrochemical characterization are tested using cyclic voltammetry, chronopotentiometry and impedance spectroscopy, respectively. These amorphous mesoporous Ni(OH)2 hollow nanoboxes shows high specific capacitance of 2495, 2378, 2197, 1993 F g-1 at discharge current of 1, 2, 5 and 10 A g-1 respectively. The property tests demonstrate the high specific capacitance and excellent cycling of the amorphous Ni(OH)2 nanoboxes material for high-performance electrochemical pseudocapacitors. © 2014 Elsevier Ltd. All rights reserved.


Zhong S.,Beijing University of Chemical Technology | Zhan C.,Nanchang University | Cao D.,Beijing University of Chemical Technology
Carbon | Year: 2015

A series of nitrogen-doped porous carbons are prepared from nitrogen-containing zeolitic imidazolate framework (ZIF) and additional carbon sources (including melamin, urea, xylitol and sucrose) via co-carbonization at T = 950 °C. Results indicate that macromolecular carbon sources, say, sucrose, can effectively protect the nitrogen loss from ZIF backbone owing to the pre-melting and polymerization of the sucrose adsorbed on the ZIF surface in the carbonization process, which makes the corresponding ZIF-derived porous Carbon-ZS have high nitrogen content and excellent capacitive performance. The specific capacitance of Carbon-ZS in 6 M KOH solution reaches 285.8 F g-1 at a current density of 0.1 A g-1 owing to its relatively high nitrogen content and proper hierarchical pore structure. In particular, the capacitance of Carbon-ZS is higher than previously reported IRMOF-derived carbon, ZIF-67-derived carbon and ZIF-8/furfuryl alcohol co-derived carbon. Besides high capacitance, moreover, Carbon-ZS also shows excellent cycling stability and good electric conductivity as electrode materials for electric double-layer capacitors. © 2014 Elsevier Ltd. All rights reserved.


Liu X.,Beijing University of Chemical Technology | Cao D.,Beijing University of Chemical Technology | Yu A.,University of Waterloo
Journal of Physical Chemistry C | Year: 2010

The effects of structure, temperature, and strain rate on mechanical properties of all the SiGe nanotubes in armchair and zigzag structures (n ) 4-13) in two atomic arrangement types are investigated by classical molecular dynamics simulation. During the extending tests, we observe three structural transformations from initial structure, tensile structure, to critical structure deformation. The simulation results indicate that the Young's modulus of nanotubes is closely dependent on their diameter, chirality, and arrangement structure. The type 1 (alternating atom arrangement type) armchair SiGe nanotube exhibits the largest Young's modulus, compared with other nanotubes with the same index n. By exploring the effects of temperature and strain rate on mechanical properties of SiGe nanotubes, it is found that the higher temperature and lower strain rate lead to the lower critical strain and tensile strength. Furthermore, it is also found that the critical strains for both armchair and zigzag nanotubes in two arrangement types are significantly dependent on the tube diameter and chirality. The armchair type 1 nanotube exhibits the highest mechanical critical strain and tensile strength among all these nanotubes with the same index n. On the basis of the transition-state theory model, we predict that the critical strain of the SiGe (6,6) type 1 nanotube at 300 K, stretched with a strain rate of 5%/h, is about 3.38%, which is in good agreement with the recent experimental results. Our results might provide potential applications in manipulating mechanical and electromechanical properties of the nanostructures suitable for electronic devices. © 2010 American Chemical Society.


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.


Sang N.,Beijing University of Chemical Technology | Zhan C.,Nanchang University | Cao D.,Beijing University of Chemical Technology
Journal of Materials Chemistry A | Year: 2015

Rapid and sensitive detection of nitroaromatic explosives has attracted considerable attention due to their serious harm to our world. In this work, two porous luminescent covalent-organic polymers (COP-401 and COP-301) have been synthesized through copolymerization of double ligands. The results indicate that the two COPs with high thermal stability show significant luminescence quenching effects for nitroaromatic explosives. In particular, the two COPs exhibit not only a high sensitivity (about 1 ppm) for nitoraromatic explosives, but also an extremely high selectivity for 2,4,6-trinitrophenol (PA), which suggests that they are promising luminescent probes for highly sensitive and selective detection of nitroaromatic explosives, especially for PA. This journal is © The Royal Society of Chemistry 2015.


Bai S.,Beijing University of Chemical Technology | Zhang K.,Beijing University of Chemical Technology | Luo R.,Beijing University of Chemical Technology | Li D.,Beijing University of Chemical Technology | And 2 more authors.
Journal of Materials Chemistry | Year: 2012

Tungsten trioxide (WO 3) nanorods with an aspect ratio of ∼50 have been successfully synthesized by hydrothermal reaction at a low temperature of 100 °C. The crystal structure, morphology evolution and thermal stability of the products are characterized in detail by XRD, FESEM, FTIR, and TG/DTA techniques. The diameter evolution and distribution of WO 3 nanorods strongly depend on hydrothermal temperature and time. Hydrothermal conditions of 100 °C and 24 h ensure the formation of well-defined WO 3 nanorods. The transition of the crystal structure from monoclinic WO 3 to hexagonal WO 3 occurs after calcination at 400 °C. The appropriate calcination conditions of the WO 3 nanorods are defined to be 600 °C and 4 h for gas-sensing applications. Response measurements reveal that the WO 3 sensor operating at 200 °C exhibits high sensitivity to ppm-level NO 2 and small cross-sensing to CO and CH 4, which makes this kind of sensor a competitive candidate for NO 2-sensing applications. Moreover, impedance measurements indicate that a conductivity mechanism of the sensor is mainly dependent on the grain boundaries of WO 3 nanorods. A possible adsorption and reaction model is proposed to illustrate the gas-sensing mechanism. © 2012 The Royal Society of Chemistry.


Wei S.,Beijing University of Chemical Technology | Zhang H.,Beijing Research Institute of Chemical Defense | Zhang H.,University of Science and Technology Beijing | Huang Y.,Beijing University of Chemical Technology | And 3 more authors.
Energy and Environmental Science | Year: 2011

Pig bone derived carbon with a unique hierarchical porous structure was prepared by potassium hydroxide (KOH) activation. The effects of activation temperature on the textural properties of the pig bone based carbons were investigated. The hierarchical porous carbons exhibit the largest BET specific surface areas and pore volume when the activation temperature reaches 850 °C, and the carbon still maintains a highly hierarchical structure even when the temperature is up to 950 °C. The pig bone derived hierarchical porous carbon/sulfur composites have been tested as a novel cathode for lithium-sulfur batteries. The result shows that the cycle stability and the utilization of sulfur in the lithium-sulfur batteries have been largely improved. The hierarchical porous carbon/sulfur cathode has a high initial capacity of 1265 mAh g-1 and 643 mAh g-1 after 50 cycles, which is higher than that of the normal cathodes with compact structures. © 2011 The Royal Society of Chemistry.


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.


Xu B.,Beijing Research Institute of Chemical Defense | Zheng D.,Beijing University of Chemical Technology | Jia M.,Beijing University of Chemical Technology | Cao G.,Beijing Research Institute of Chemical Defense | Yang Y.,Beijing Research Institute of Chemical Defense
Electrochimica Acta | Year: 2013

Nitrogen-doped porous carbons are very simply prepared by direct pyrolysis of a nitrogen-containing organic salt, the tetrasodium salt of ethylenediamine tetraacetic acid for example, at 600-900 °C in an inert atmosphere without activation. The porosity and surface chemistry of the carbon depend strongly on the pyrolysis temperature. The surface area and pore volume increase with the pyrolysis temperature, and vary from 408 to 1171 m2 g-1 and 0.209 to 0.709 cm3 g-1, respectively. While the nitrogen content decreases from 8.59 at% for pyrolysis at 600 °C to 1.02 at% at 900 °C. The unique microstructure and nitrogen functionalities enable the carbon to exhibit a capacitance of 245 F g-1 in a 6 mol L -1 KOH aqueous electrolytes, which is attributed to the contributions of double layer capacitance and pseudo-capacitance, with an excellent rate capability (188 F g-1 remained at 20 A g-1) and cycle durability. © 2013 Elsevier Ltd. All rights reserved.


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.


Xiang Z.,Beijing University of Chemical Technology | Cao D.,Beijing University of Chemical Technology | Huang L.,Beijing University of Chemical Technology | Shui J.,Case Western Reserve University | And 2 more authors.
Advanced Materials | Year: 2014

Using covalent organic polymer precursors, we have developed a new strategy for location control of N-dopant heteroatoms in the graphitic porous carbon, which otherwise is impossible to achieve with conventional N-doping techniques. The electrocatalytic activities of the N-doped holey graphene analogues are well correlated to the N-locations, showing possibility for tailoring the structure and property of N-doped carbon nanomaterials. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Dang Z.-M.,University of Science and Technology of China | Dang Z.-M.,Beijing University of Chemical Technology | Dang Z.-M.,Xi'an Jiaotong University | Yuan J.-K.,Beijing University of Chemical Technology | And 5 more authors.
Progress in Materials Science | Year: 2012

There is an increasing need for high-permittivity (high-k) materials due to rapid development of electrical/electronic industry. It is well-known that single composition materials cannot meet the high-k need. The combination of dissimilar materials is expected to be an effective way to fabricate composites with high-k, especial for high-k polymer-matrix composites (PMC). This review paper focuses on the important role and challenges of high-k PMC in new technologies. The use of different materials in the PMC creates interfaces which have a crucial effect on final dielectric properties. Therefore it is necessary to understand dielectric properties and processing need before the high-k PMC can be made and applied commercially. Theoretical models for increasing dielectric permittivity are summarized and are used to explain the behavior of dielectric properties. The effects of fillers, fabrication processes and the nature of the interfaces between fillers and polymers are discussed. Potential applications of high-k PMC are also discussed. © 2011 Elsevier Ltd. All rights reserved.


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.


Bai S.,Beijing University of Chemical Technology | Hu J.,Beijing University of Chemical Technology | Li D.,Beijing University of Chemical Technology | Luo R.,Beijing University of Chemical Technology | And 2 more authors.
Journal of Materials Chemistry | Year: 2011

Quantum-sized ZnO nanoparticles have been synthesized at room temperature by a mild sol-gel process using tetraethylorthosilicate (TEOS) as the capping agent to control the particle growth of ZnO. The crystal structure, particle size and optical properties have been investigated by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), photoluminescence (PL) spectra and Raman spectra, respectively. The results show that the ZnO nanoparticles exhibit hexagonal wurtzite structure and the average crystallite size is 5.7 nm which is a little less than TEM results. It has been testified by room-temperature PL spectra that the TEOS capped the surface of ZnO nanoparticles and obviously reduced grain size, as an emission at 520 nm almost disappeared and a new peak with an anomalous blue shift as great as 9 nm, appeared for the TEOS capped ZnO. The sensing tests indicate that the ZnO based sensors not only show a high response to NO2 but also exhibit high selectivity over CO and CH4 at a low operating temperature of 290 °C. The response increases with NO2 concentration and decreases with calcination temperature, and is in agreement with Raman and XRD results. © 2011 The Royal Society of Chemistry.


Chen W.,Beijing University of Chemical Technology | Zhang H.,Beijing Research Institute of Chemical Defense | Zhang H.,University of Science and Technology Beijing | Huang Y.,Beijing University of Chemical Technology | Wang W.,Beijing Research Institute of Chemical Defense
Journal of Materials Chemistry | Year: 2010

A hierarchical lamellar porous carbon material was prepared with fish scale using a natural template. Electric double layer capacitors electrodes prepared from this kind of porous carbon exhibited exceptional ration ability which demonstrated that fish scale is a promising candidate precursor to prepare low cost but high performance porous carbon material. © The Royal Society of Chemistry 2010.


Xiang Z.,Case Western Reserve University | Xiang Z.,Beijing University of Chemical Technology | Xue Y.,Case Western Reserve University | Cao D.,Beijing University of Chemical Technology | And 3 more authors.
Angewandte Chemie - International Edition | Year: 2014

A class of 2D covalent organic polymers (COPs) incorporating a metal (such as Fe, Co, Mn) with precisely controlled locations of nitrogen heteroatoms and holes were synthesized from various N-containing metal-organic complexes (for example, metal-porphyrin complexes) by a nickel-catalyzed Yamamoto reaction. Subsequent carbonization of the metal-incorporated COPs led to the formation of COP-derived graphene analogues, which acted as efficient electrocatalysts for oxygen reduction in both alkaline and acid media with a good stability and free from any methanol-crossover/CO-poisoning effects. Metal-containing (M=Fe, Co, Mn) 2D covalent organic polymers with precisely controlled locations of N heteroatoms and holes were synthesized from metal-porphyrin complexes by a nickel-catalyzed Yamamoto reaction. Subsequent carbonization led to graphene analogues, which are efficient electrocatalysts for oxygen reduction in both alkaline and acid media and are free from methanol-crossover/CO poisoning. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Patent
CHILWEE POWER Co. and Beijing University of Chemical Technology | Date: 2014-05-27

Provided is a method for recycling a lead oxide-containing waste material, comprising: (1) contacting the lead oxide-containing waste material with a desulphurizer under desulphurization reaction conditions, and performing a solid-liquid separation on the mixture after contacting to obtain a filtrate and a filtration residue; (2) performing a conversion reaction on the above-mentioned filtration residue at a temperature of 350-750 C. so as to convert the lead-containing components in the filtration residue into lead oxide; (3) contacting the product obtained from step (2) with an alkaline solution so as to dissolve the PbO therein, and then performing a solid-liquid separation to obtain a PbO-alkaline solution; and (4) crystallizing the PbO-alkaline solution from step (3) to obtain PbO crystals and an alkaline filtrate. The method can reduce the energy consumption.


Patent
CHILWEE POWER Co. and Beijing University of Chemical Technology | Date: 2014-05-27

Provided is a method for directly recovering lead oxide used for a lead-acid battery negative electrode from waste lead paste. The method comprises: (1) contacting waste lead paste with a barium-containing desulphurizer under desulphurization reaction conditions, and performing a solid-liquid separation on the mixture after contacting to obtain a filtrate and a filtration residue; and (2) performing a conversion reaction on the above-mentioned filtration residue at a temperature of 350-750 C. so as to convert the lead-containing components in the filtration residue into lead oxide. In the method, the direct recovery of a lead oxide raw material applicable to a lead-acid battery negative electrode from waste lead paste is achieved by quantitatively replenishing a barium sulphate additive in the process of desulphuration thereby substantially decreasing the recovery cost and energy consumption, and improving the comprehensive utilization of waste lead paste.


Huang W.,Beijing University of Chemical Technology | Zhang H.,Beijing Research Institute of Chemical Defense | Zhang H.,University of Science and Technology Beijing | Huang Y.,Beijing University of Chemical Technology | And 2 more authors.
Carbon | Year: 2011

Animal bone, an abundant biomass source and high volume food waste, had been converted into a hierarchical porous carbon in a simple two-step sustainable manner to yield a highly textured material. The structures were characterized by nitrogen sorption at 77 K, scanning electron microscopy and X-ray diffraction. The electrochemical measurement in 7 M KOH electrolyte showed that the porous carbon had excellent capacitive performances, which can be attributed to the unique hierarchical porous structure (abundant micropores with the size of 0.5-0.8 and 1-2 nm, mesopores and macropores with the size of 2-10 and 10-100 nm), high surface area (SBET = 2157 m2/g) and high total pore volume (Vt = 2.26 cm3/g). Its specific capacitance was 185 F/g at a current density of 0.05 A/g. Of special interest was the fact that the porous carbon still maintained 130 F/g even at a high current density of 100 A/g. © 2010 Published by Elsevier Ltd. All rights reserved.


Patent
Chilwee Power Co. and Beijing University of Chemical Technology | Date: 2016-04-27

Provided is a method for recycling a lead oxide-containing waste material, comprising: (1) contacting the lead oxide-containing waste material with a desulphurizer under desulphurization reaction conditions, and performing a solid-liquid separation on the mixture after contacting to obtain a filtrate and a filtration residue; (2) performing a conversion reaction on the above-mentioned filtration residue at a temperature of 350-750C so as to convert the lead-containing components in the filtration residue into lead oxide; (3) contacting the product obtained from step (2) with an alkaline solution so as to dissolve the PbO therein, and then performing a solid-liquid separation to obtain a PbO-alkaline solution; and (4) crystallizing the PbO-alkaline solution from step (3) to obtain PbO crystals and an alkaline filtrate. The method can reduce the energy consumption.


Patent
Chilwee Power Co. and Beijing University of Chemical Technology | Date: 2016-04-27

Provided is a method for directly recovering lead oxide used for a lead-acid battery negative electrode from waste lead paste. The method comprises: (1) contacting waste lead paste with a barium-containing desulphurizer under desulphurization reaction conditions, and performing a solid-liquid separation on the mixture after contacting to obtain a filtrate and a filtration residue; and (2) performing a conversion reaction on the above-mentioned filtration residue at a temperature of 350-750C so as to convert the lead-containing components in the filtration residue into lead oxide. In the method, the direct recovery of a lead oxide raw material applicable to a lead-acid battery negative electrode from waste lead paste is achieved by quantitatively replenishing a barium sulphate additive in the process of desulphuration, thereby substantially decreasing the recovery cost and energy consumption, and improving the comprehensive utilization of waste lead paste.


Sun M.,Beijing University of Chemical Technology | Mullen K.,Max Planck Institute for Polymer Research | Yin M.,Beijing University of Chemical Technology
Chemical Society Reviews | Year: 2016

Water-soluble perylenediimides (PDIs) with high fluorescence intensity, photostability and biocompatibility have been successfully prepared and applied in the biological field. In this tutorial review, we briefly focus on the synthetic strategies for the preparation of water-soluble PDIs by incorporating ionic or non-ionic substituents with multiple polar groups into the bay-region, imide- or ortho-positions of PDIs. These ionic/non-ionic substituents can suppress π-π aggregation and shield the inner perylene chromophores, thus contributing to the water solubility which is essential for biological applications. The optical properties, absorption and emission maxima above 500 nm, minimize the autofluorescence background of cells and provide access to imaging in living cells. The biological applications of water-soluble PDIs are discussed from simple (basic) to complex (advanced) processes, including biosensing in vitro studies, imaging and gene/drug delivering in living cells, tissues and the whole body. The promising future of designed multi-functional water-soluble PDIs will be highlighted in this review. © 2016 The Royal Society of Chemistry.


You S.,Beijing University of Chemical Technology | Cai Q.,Beijing University of Chemical Technology | Mullen K.,Max Planck Institute for Polymer Research | Yang W.,Beijing University of Chemical Technology | Yin M.,Beijing University of Chemical Technology
Chemical Communications | Year: 2014

Unimolecular fluorescent micelles of star polyelectrolytes with a perylenediimide core are very sensitive to changes in pH values. The pH-responsive behavior relies on the ionization or deionization of the star polyelectrolytes, which causes a reversible volume phase transition and optical response. This journal is © The Royal Society of Chemistry.


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.


Sui Z.,Beijing Institute of Technology | Meng Q.,Beijing University of Chemical Technology | Zhang X.,Beijing Institute of Technology | Ma R.,Beijing University of Chemical Technology | Cao B.,Beijing University of Chemical Technology
Journal of Materials Chemistry | Year: 2012

Carbon nanotube-graphene hybrid aerogels have been fabricated by supercritical CO 2 drying of their hydrogel precursors obtained from heating the aqueous mixtures of graphene oxide and carbon nanotubes with Vitamin C without stirring. The resulting hybrid aerogels show very promising performance in water purification including capacitive deionization of light metal salts, removal of organic dyes and enrichment of heavy metal ions. © 2012 The Royal Society of Chemistry.


Omwoma S.,Beijing University of Chemical Technology | Gore C.T.,Beijing University of Chemical Technology | Ji Y.,Beijing University of Chemical Technology | Hu C.,Beijing Institute of Technology | Song Y.-F.,Beijing University of Chemical Technology
Coordination Chemistry Reviews | Year: 2014

Polyoxometalates (POMs) are a class of versatile and discrete anionic metal oxides in groups 5 and 6. POMs have unique physical and chemical properties, e.g., strong Brønsted acidity, strong oxidizing agents, an unmatched range of molecular structures, efficient adsorbents, green catalysts, and redox activity. These properties have been utilized in the design of multifunctional POM materials with the ability to address different environmental issues, such as toxic gas sequestration, wastewater decontamination, fine chemical production, corrosion, and radioactive waste processing. In this study, we discuss the chemical mechanisms that involve POMs, and which have been used to solve important environmental problems. Understanding of these mechanisms will facilitate the design and synthesis of more environmentally benign POM-containing materials to solve various environmental problems. © 2014.


Xiao Y.,Beijing Institute of Technology | Wang X.,Beijing Institute of Technology | Wang W.,Beijing Institute of Technology | Zhao D.,Beijing Institute of Technology | And 2 more authors.
ACS Applied Materials and Interfaces | Year: 2014

A facile and low-cost strategy is demonstrated for preparing MnO/C-N hybrid, in which the MnO nanoparticles chemically combine with N-doped C by Mn-N bonding to achieve the hybridization of MnO with N-doped C. When served as an anode in lithium ion batteries (LIBs), the resultant hybrid manifested high capacity, excellent cyclability, and superior rate capability. A lithium storage capacity of 1699 mAh g-1 could be obtained at 0.5 A g-1 after 170 discharge-charge cycles. Even at a current density up to 5 A g -1, a high reversible capacity (907.8 mAh g-1) can be retained after 400 cycles. The excellent lithium storage performance of the MnO/C-N hybrid can be ascribed to the synergetic effects of several factors including the unique hybrid structure, the N-doping and the chemical bonding of MnO and N-doped C. © 2014 American Chemical Society.


Zhang C.,Beijing University of Chemical Technology | Xu L.,Beijing University of Chemical Technology | Shan N.,Beijing University of Chemical Technology | Sun T.,Beijing University of Chemical Technology | And 2 more authors.
ACS Catalysis | Year: 2014

Three-dimensionally ordered mesoporous carbon sphere array (OMCS)-supported Pt nanoparticles (Pt/OMCS) were synthesized and studied as electrocatalysts for the methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR). In the Pt/OMCS, the Pt particles with a mean size of ∼1.6 nm are homogeneously dispersed on the mesopore walls of the carbon spheres. The Pt/OMCS catalyst exhibits smaller Pt particle size, greater Pt dispersion, larger specific electrochemically active surface area (ECSA), higher activity for MOR and ORR, and better electrocatalytic stability than the carbon black (Vulcan XC-72R)-supported Pt and commercial Pt/C catalysts. © 2014 American Chemical Society.


Jiang X.-F.,Beijing University of Chemical Technology | Hau F.K.-W.,University of Hong Kong | Sun Q.-F.,CAS Fujian Institute of Research on the Structure of Matter | Yu S.-Y.,Beijing University of Chemical Technology | And 2 more authors.
Journal of the American Chemical Society | Year: 2014

Metal-metal bonding interactions have been used to generate a number of unique supramolecular assemblies with fascinating functions. We presented here a new class of gold(I)-containing metallosupramolecular cages and cage-built two-dimensional (2-D) arrays of {Au8L2}n (n = 1 or ∞, L = tetrakis-dithiocarbamato-calix[4]arene, TDCC), 1-3, which are constructed from the self-assembly of deep-cavitand calix[4]arene-based supramolecular cages consisting of octanuclear Au(I) motifs. Synchrotron radiation X-ray diffraction structural analyses of 1-3 revealed their quadruple-stranded helicate dimeric cage structure and the presence of 2-D arrays of cages linked together by inter- and intramolecular Au I···AuI interactions. Electronic absorption and emission studies of complexes 1-3 indicated the occurrence of a programmable self-assembly process in a concentration-dependent stepwise manner with the links built via aurophilic interactions. These novel gold(I) supramolecular cages exhibited green phosphorescence and have been shown to serve as highly selective proof-of-concept luminescent sensors toward Ag I cation among various competitive transition-metal ions. © 2014 American Chemical Society.


Zhang P.,Beijing University of Chemical Technology | Sun F.,Beijing University of Chemical Technology | Xiang Z.,Beijing University of Chemical Technology | Shen Z.,Beijing University of Chemical Technology | And 3 more authors.
Energy and Environmental Science | Year: 2014

We have successfully prepared nanoporous Carbon-L and -S materials by using ZIF-7 as a precursor and glucose as an additional carbon source. Results indicate that Carbon-L and -S show an appropriate nitrogen content, high surface area, robust pore structure and excellent graphitization degree. The addition of an environmentally friendly carbon source-glucose-not only improves the graphitization degree of samples, but also plays a key role in removing residual Zn metal and zinc compound impurities, which makes the resulting materials metal-free in situ nitrogen-doped porous carbons. By further investigating the electrocatalytic performance of these nitrogen-doped porous carbons for oxygen reduction reaction (ORR), we find that Carbon-L, as a metal-free electrocatalyst, shows excellent electrocatalytic activity (the onset and half-wave potentials are 0.86 and 0.70 V vs. RHE, respectively) and nearly four electron selectivity (the electron transfer number is 3.68 at 0.3 V), which is close to commercial 20% Pt/C. Moreover, when methanol was added, the Pt/C catalyst would be poisoned while the Carbon-L and -S would be unaffected. By exploring the current-time chronoamperometric response in 25 000 s, we found that the duration stability of Carbon-L is much better than the commercial 20% Pt/C. Thus, both Carbon-L and -S exhibit excellent ability to avoid methanol crossover effects, and long-term operation stability superior to the Pt/C catalyst. This work provides a new strategy for in situ synthesis of N-doped porous carbons as metal-free electrocatalysts for ORR in fuel cells. This journal is © 2014 The Royal Society of Chemistry.


Yang J.,University of South Australia | Zou L.,University of South Australia | Song H.,Beijing University of Chemical Technology | Hao Z.,CAS Research Center for Eco Environmental Sciences
Desalination | Year: 2011

Capacitive deionization (CDI) is a technology for desalination and water purification that charged ions are electrosorbed on the porous electrodes, thus its performance largely affected by choice of electrodes. In this paper, the MnO2/nanoporous carbon composites were prepared and used as electrodes in CDI. Salt removal efficiency for the MnO2/nanoporous carbon was 16.9μmol/g which was higher than 5.4μmol/g of the commercially available activated carbon (AC). The nanoporous carbons were synthesised using silica templates while their composites were prepared by a co-precipitation method and were characterised carefully. The capacitance of the MnO2/carbon composites (204.7F/g) was higher than the AC (98.6F/g). The capacitance increase may be attributed to the high surface area and suitable pore size distribution properties. Moreover, the MnO2 film provided a high surface adsorption capability and an effective cation intercalation. © 2011 Elsevier B.V.


Zhang J.,Beijing University of Chemical Technology | Lam J.,University of Hong Kong | Xia Y.,Beijing Institute of Technology
Information Sciences | Year: 2014

This paper is concerned with the design and analysis problems of output feedback delay compensation controller for networked control systems (NCSs) with random network delay. By taking the full advantage of the packet-based transmission in NCSs, a delay compensation control approach is proposed to actively compensate the network-induced delay in Markovian jump linear system framework. Different from previously reported delay compensation control approaches to NCSs, an output feedback strategy is used to generate the control input packet. A new necessary and sufficient condition is proposed to perform the stability analysis of networked closed-loop system. Furthermore, by using the recently established singular Markovian jump system theory, the controller design problem is solved. Finally, the effectiveness of the proposed method is illustrated by using a numerical example. © 2013 Elsevier Inc. All rights reserved.


Xue J.,Beijing University of Chemical Technology | Niu Y.,Beijing University of Chemical Technology | Gong M.,Beijing University of Chemical Technology | Shi R.,Beijing Research Institute of Traumatology and Orthopaedics | And 3 more authors.
ACS Nano | Year: 2015

Guided tissue regeneration/guided bone regeneration membranes with sustained drug delivery were developed by electrospinning drug-loaded halloysite clay nanotubes doped into poly(caprolactone)/gelatin microfibers. Use of 20 wt % nanotube content in fiber membranes allowed for 25 wt % metronidazole drug loading in the membrane. Nanotubes with a diameter of 50 nm and a length of 600 nm were aligned within the 400 nm diameter electrospun fibers, resulting in membranes with doubling of tensile strength along the collector rotating direction. The halloysite-doped membranes acted as barriers against cell ingrows and have good biocompatibility. The metronidazole-loaded halloysite nanotubes incorporated in the microfibers allowed for extended release of the drugs over 20 days, compared to 4 days when directly admixed into the microfibers. The sustained release of metronidazole from the membranes prevented the colonization of anaerobic Fusobacteria, while eukaryotic cells could still adhere to and proliferate on the drug-loaded composite membranes. This indicates the potential of halloysite clay nanotubes as drug containers that can be incorporated into electrospun membranes for clinical applications. © 2015 American Chemical Society.


Gao Y.,Beijing University of Chemical Technology | Cheng M.,Beijing University of Chemical Technology | Wang B.,Beijing University of Chemical Technology | Feng Z.,Chinese PLA General Hospital | Shi F.,Beijing University of Chemical Technology
Advanced Materials | Year: 2010

A functionally cooperating device has been fabricated by combining a pH-responsive surface with hydrogen peroxide-responsive platinum, which displays a diving-surfacing cycle towards mimicking a submarine. This smart device may open a new avenue to the research of nanoscience and bridge the gap between active nanomaterials and three-dimensional nanosystems or systems of systems. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Cao M.,Beijing Institute of Technology | Lian H.,Beijing University of Chemical Technology | Hu C.,Beijing Institute of Technology
Nanoscale | Year: 2010

Hollow CdSe nanospheres were successfully synthesized by a ligand-assisted solvothermal method based on an Ostwald ripening mechanism. The hollow CdSe nanospheres were synthesized in benzyl alcohol under solvothermal conditions using Cd(Ac)2 and Se as the precursors, and tryptophan as a ligand. The resulting hollow structures consisted of small nanocrystallite building blocks. More importantly, the hollow CdSe nanospheres could be used as an excellent microwave absorber for cm- and mm-wave absorption, depending on the thickness of the absorber. © 2010 The Royal Society of Chemistry.


Cai X.,Chinese PLA General Hospital | Yang M.,Beijing University of Chemical Technology
Journal of Cancer Research and Clinical Oncology | Year: 2012

Purpose: The P53-MDM2 pathway plays a central role in sarcoma pathogenesis. Functional P53 Arg72Pro and MDM2 T309G single-nucleotide polymorphisms (SNP) are considered to have significant effects on risk of sarcomas. Methods: Several molecular epidemiology studies have evaluated how these genetic variants are involved in sarcoma development, but the conclusions are inconsistent. Therefore, we conducted this meta-analysis to systematically examine the association between these functional SNPs and sarcoma risk. Results: There are four studies eligible for P53 Arg72Pro SNP (466 sarcoma patients and 552 controls), and three studies for MDM2 T309G SNP (355 sarcoma patients and 645 controls). Pooled odds ratios were appropriately calculated using either fixed-effect model or random-effect model. We did not find a significant association between P53 Arg72Pro polymorphism and sarcoma risk. However, in a stratified analysis, a statistically significant correlation between this SNP and osteosarcoma risk was observed. For MDM2 T309G variant, pooled results from the metaanalysis indicate that carriers of TG and GG genotypes showed a 34% increased risk to develop sarcomas compared to TT carriers. Conclusion: These results suggest that the functional MDM2 T309G genetic variant may play a more important role in carcinogenesis of sarcoma. © Springer-Verlag 2011.


Wang T.,CAS Institute of Chemistry | Li H.,Beijing University of Chemical Technology | Wang F.,Beijing University of Chemical Technology | Schultz J.M.,University of Delaware | Yan S.,Beijing University of Chemical Technology
Polymer Chemistry | Year: 2011

The morphological features and mechanical properties of PVDF/PBS blends with a variety of blend ratios and under different preparation conditions have been studied by optical and atomic force microscopy, as well as by tensile tests. It was found that, at high PVDF crystallization temperature, a small amount of PBS in the 70/30 PVDF/PBS blends has been expelled into the PVDF spherulite margin areas and interspherulitic regions due to the high diffusion ability of PBS and the slower crystal growth rate of the PVDF at high temperature. Nevertheless, the PBS affects the crystallization of PVDF significantly, which has been revealed by the increase in birefringence of PVDF spherulites of both α and γ types and the increase in band period of the α PVDF spherulites. With increasing PBS content, the increase in birefringence of PVDF spherulites and the increase in band period of the α PVDF spherulites get more evident, reflecting a more efficient influence of PBS on the crystallization of PVDF. In the PBS-rich blends, e.g., in the 40/60 and 30/70 PVDF/PBS blends, the PVDF forms isolated spherulites with large non-crystallizing PBS melt regions, which results in an interspherulitic phase separation with bigger interspherulitic PVDF areas. There is, however, PBS dispersed within the PVDF spherulites. During the crystallization of PBS at low temperature, it was found that the PBS in the interspherulitic and interaspherulitic regions growth in different manner with different growth rates. At lower PVDF crystallization temperatures, the PVDF crystallizes first and fills all the volume in regardless its content in the blends. This leads to the PBS being distributed in the interlamellar or interfibrillar regions of PVDF spherulites only. However, the growth of PBS in banded and non-banded PVDF matrix is different, reflecting the influence of pre-existing PVDF crystals on the crystallization of PBS. Tensile test shows that the deformation behavior depends remarkably on the blend ratio and the crystallization temperature of the PVDF. Such phenomena has been correlated and explained in view of the inner morphological change. © 2011 The Royal Society of Chemistry.


Yang J.,University of South Australia | Zou L.,University of South Australia | Song H.,Beijing University of Chemical Technology
Desalination | Year: 2012

It is of great interest to control the pore structure, conductivity and electrochemical activity properties of electrode materials, as their capacitance in the electrosorption process is determined by these properties. These properties can be modified effectively during the synthesis process. The layer-by-layer deposition approach was employed to prepare a manganese oxide (MnO 2)/carbon nanotubes (CNTs) composite. In this study, Polystyrene Sodium Sulfonate (PSS) facilitated the dispersion of CNTs and even growth of MnO 2. The resulting composite material was used for electrodes in the membrane capacitive deionisation (MCDI) process and a high salt removal efficiency of 96.8% was achieved, with an ion adsorption capacity of 80.4μmol/g of MnO 2/PSS/CNTs electrode material. Conversely, a MnO 2/CNTs composite that was prepared using a hydrothermal synthesis process did not show such excellent advantages. © 2011 Elsevier B.V.


Zhang R.,Beijing University of Chemical Technology | Zhang R.,Laval University | Teoh W.Y.,University of New South Wales | Amal R.,University of New South Wales | And 2 more authors.
Journal of Catalysis | Year: 2010

Mixed oxides of 4% Cu/CexZr1-xO 2 (x = 0, 0.25, 0.50, 0.75, 1) were synthesized by flame spray pyrolysis and characterized by N2 adsorption, XRD, XPS, O 2-TPD and H2-TPR. The as-prepared catalysts were assessed for the equimolar reduction of NO by CO (3000 ppm each, space velocity 50,000 h-1). Incorporation of Zr4+ in the form of solid solution with CeO2 stabilizes the Cu+ species, which was in turn beneficial for the initial reductive chemisorption of NO to N2O. A peculiar low-temperature activity giving 40% N2 yield was found with the composition of Cu/Ce0.75Zr0.25O2 at 150 °C. This is traced to the low-temperature activation of rapid CO oxidation (as probed by in situ DRIFTS), related to the abundance of surface reactive lattice oxygen sites and their high reducibility. At 250 °C and above, a N2 yield of >85% (and ∼100% at 350 °C) was obtained for all Zr-containing catalysts i.e. Cu/CexZr1- xO2 (x < 1.0), with essentially no intermediate N 2O detected in the exhaust gas stream. An organonitrogen mechanism is occurring in this case. © 2010 Elsevier Inc.


Patent
Beijing University of Chemical Technology, Wang, Cao, Liu and Li | Date: 2015-10-28

Provided are a gas diffusion electrode and a preparation method thereof. The gas diffusion electrode comprises a current collector 1, a gas diffusion layer 2, a gas catalysis layer 3 coated on the gas diffusion layer, and a liquid guide layer 4 located on the gas catalysis layer. The gas diffusion layer comprises highly-graphitized carbon black and polytetrafluoroethylene, and the gas catalysis layer comprises a catalyst, acidified highly-graphitized carbon black and polytetrafluoroethylene; the highly-graphitized carbon black has a peak intensity ratio I_(D)/I_(G) between 0.3 and 1.0 in the Raman spectrum, and the degrees of graphitization in the gas diffusion layer and the gas catalysis layer may be the same or different. The gas diffusion electrode has good corrosion resistance and excellent and stable electrochemical performance in alkali solutions, thus it is suitable for electrolytic reactions in the chlor-alkali industry.


Abstract: The pathway to zero-emission vehicles has taken two forks, one toward battery electric cars like the Tesla and the other toward fuel-cell-powered automobiles like the Toyota Mirai. The University of Delaware's Yushan Yan believes that fuel-cell vehicles are the way to go, because they best preserve the advantages of gasoline automobiles: low upfront cost, long driving range and fast refueling. But he also believes that a new fuel-cell technology may be necessary. For Yan, that approach is a new twist on traditional fuel cells, known as proton exchange membrane fuel cells, or PEMFCs, which rely on costly platinum-based catalysts. Yan and his research team are pursuing an alternative technology, the hydroxide exchange membrane fuel cell (HEMFC), because of its inherent cost advantages. He sees the rationale for this proposed switch as a matter of very simple arithmetic. "To make fuel-cell cars a reality, the DOE (Department of Energy) has set a system cost target of $30 per kilowatt, which translates into about $2,400 per car," he says. "Right now, the cost for PEMFCs is $52 per kilowatt, which is a big improvement over where the technology started." "But the catalyst accounts for only about $12 of that total, leaving $40 worth of other components. So even if we throw in some magic, we can't get the rest of the way down to the target of $30 with PEMFCs." Yan is co-author on a new paper published in the online version of Nature Nanotechnology that he views as a roadmap to a unified strategy for HEMFC zero-emission cars based on three arguments. "First, to become a commercial reality, fuel-cell engines have to be at cost parity with their gasoline counterparts," he says, "and moving from an acid platform with the PEMFC to a base system with the HEMFC will enable a collateral benefit in bringing down all of the associated costs. "Then, if we agree that this is the best approach, we need to get everyone in the HEMFC research community on board. If we want to succeed, we have to work together." Finally, Yan warns that it is insufficient just to have a lower cost. "It doesn't work to compare our results today with those from yesterday or the day before," he says. "To succeed commercially with HEMFCs, we have to match or beat the performance of PEMFCs. It's that simple -- we can't succeed without achieving performance parity." ### Yan is Distinguished Engineering Professor in UD's Department of Chemical and Biomolecular Engineering, Setzler is a postdoctoral researcher in Yan's group, and Wittkopf is a doctoral student advised by Yan. Zhuang is a professor at Beijing University of Chemical Technology and a former postdoctoral researcher in Yan's group. For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.


News Article | December 13, 2016
Site: www.cemag.us

The pathway to zero-emission vehicles has taken two forks, one toward battery electric cars like the Tesla and the other toward fuel-cell-powered automobiles like the Toyota Mirai. The University of Delaware’s Yushan Yan believes that fuel cell vehicles are the way to go, because they best preserve the advantages of gasoline automobiles: low upfront cost, long driving range, and fast refueling. But he also believes that a new fuel cell technology may be necessary. For Yan, that approach is a new twist on traditional fuel cells, known as proton exchange membrane fuel cells, or PEMFCs, which rely on costly platinum-based catalysts. Yan and his research team are pursuing an alternative technology, the hydroxide exchange membrane fuel cell (HEMFC), because of its inherent cost advantages. He sees the rationale for this proposed switch as a matter of very simple arithmetic. “To make fuel-cell cars a reality, the DOE (Department of Energy) has set a system cost target of $30 per kilowatt, which translates into about $2,400 per car,” he says. “Right now, the cost for PEMFCs is $52 per kilowatt, which is a big improvement over where the technology started.” “But the catalyst accounts for only about $12 of that total, leaving $40 worth of other components. So even if we throw in some magic, we can’t get the rest of the way down to the target of $30 with PEMFCs.” Yan is co-author on a paper published in the online version of Nature Nanotechnology on Dec. 6 that he views as a roadmap to a unified strategy for HEMFC zero-emission cars based on three arguments. “First, to become a commercial reality, fuel cell engines have to be at cost parity with their gasoline counterparts,” he says, “and moving from an acid platform with the PEMFC to a base system with the HEMFC will enable a collateral benefit in bringing down all of the associated costs. “Then, if we agree that this is the best approach, we need to get everyone in the HEMFC research community on board. If we want to succeed, we have to work together.” Finally, Yan warns that it is insufficient just to have a lower cost. “It doesn’t work to compare our results today with those from yesterday or the day before,” he says. “To succeed commercially with HEMFCs, we have to match or beat the performance of PEMFCs. It’s that simple — we can’t succeed without achieving performance parity.” The paper, “Activity Targets for Nanostructured Platinum Group Metal-Free Catalysts in Hydroxide Exchange Membrane Fuel Cells,” was co-authored by Brian P. Setzler, Zhongbin Zhuang, Jarrid A. Wittkopf, and Yushan Yan. Yan is Distinguished Engineering Professor in UD’s Department of Chemical and Biomolecular Engineering, Setzler is a postdoctoral researcher in Yan’s group, and Wittkopf is a doctoral student advised by Yan. Zhuang is a professor at Beijing University of Chemical Technology and a former postdoctoral researcher in Yan’s group.


Yuan W.,Chinese Academy of Sciences | Li C.,Beijing University of Chemical Technology | Zhao C.,Chinese Academy of Sciences | Sui C.,Chinese Academy of Sciences | And 3 more authors.
Advanced Functional Materials | Year: 2012

Efficient local gene transfection on a tissue scaffold is of crucial importance in facilitating tissue repair and regeneration. In this work, the gelatin-functionalized polycaprolactone (PCL) film surfaces are prepared via surface-initiated atom transfer radical polymerization of glycidyl methacrylate. The resultant covalent attachment of gelatin could enhance the cell-adhesion and local gene transfection properties. The gelatin-functionalized PCL film surfaces exhibit excellent cell-adhesion ability to both adherent and suspension cells. The attached adherent cells demonstrate the characteristic elongated morphologies with good spreading capability, while the attached suspension cells can maintain the original status of the round morphologies without spreading. More importantly, the gelatin coupled on the PCL surface could be used to absorb the cationic vector/plasmid deoxyribonucleic acid (pDNA) complexes via electrostatic interaction. The local gene transfection property on the immobilized cells is dependent on both the density of the immobilized cells and the loading types of pDNA complexes. The transfection efficiency of different assemble methods of pDNA complex was compared. With the pre- and post-loading sandwich-like gene transfection, the gelatin-functionalized PCL film surface can substantially enhance the transfection properties to different cell lines. The present study is very useful to spatially control local gene delivery within PCL-based tissue scaffolds. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


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 X.,Beijing University of Chemical Technology | Zhao X.,Beijing University of Chemical Technology | Zhu Y.,Beijing University of Chemical Technology | Zhang F.,Beijing University of Chemical Technology
Applied Catalysis B: Environmental | Year: 2013

This work aims at revealing the role of pristine layered double hydroxide (LDH) materials in the elimination of organic pollutants from solution. Typical LDH samples, ZnCr- and MgAl-LDHs (with Zn2+/Cr3+ or Mg2+/Al3+ molar ratio 2), are prepared and used for the removal of methylene blue (MB), methyl orange (MO), and formaldehyde. The systematic investigations of structural characterization and periodic density functional theory (DFT) calculation of the LDH samples demonstrate that: (1) no electron-hole pairs could be generated for MgAl-LDHs under the irradiation of visible light due to the large calculated gap energy above 5.0eV. (2) ZnCr-LDHs are sensitive to the irradiation of visible light with the calculated gap energy between 2.0 and 3.0eV, but the rapid charge recombination and low efficiency in electron/hole separation would suggest that photocatalytic activity of ZnCr-LDHs would be greatly limited. In the experimental work, ZnCr- and MgAl-LDHs show no photocatalytic activity for the removal of formaldehyde under the visible light. The disposal of the organic dyes molecules in the solution would be caused by the photoassisted degradation and surface adsorption effect rather than the photocatalysis impact for both LDH samples. This is confirmed by the elimination tests that carry out in the dark condition with the similar procedure under visible light irradiation. Moreover, the two types of LDH samples exhibit the different adsorption capability for the MB and MO molecules due to the different colloidal properties of the LDH samples, which is revealed by Zeta potential measurement. The above finding that elimination of organic dyes from solution by the pristine LDH samples through photoassisted degradation and adsorption processes would be important for the rational design and use of clay-like materials for the treatment of sewage containing toxic compounds. © 2013 Elsevier B.V.


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.


Gu C.,Beijing University of Chemical Technology | Zhou Y.,Beijing University of Chemical Technology | Liu L.,Beijing University of Chemical Technology | Tan T.,Beijing University of Chemical Technology | Deng L.,Beijing University of Chemical Technology
Bioresource Technology | Year: 2013

An immobilization method using net was developed for fumaric acid fermentation by Rhizopus arrhizus RH-07-13. The large surface of the net immobilized enough filamentous mycelia which produced fumaric acid rapidly. Net size and spore concentration were optimized to enhance fermentation performance and 150cm2 of net size, 0.5×106per ml of spore concentration were selected finally. Compared to free-cell fermentation, fumaric acid production was flat (32.03 vs. 31.23g/L) but fermentation time reduced 83.3% (24 vs. 144h). © 2012 Elsevier Ltd.


Wei S.,Beijing University of Chemical Technology | Li D.,Beijing University of Chemical Technology | Huang Z.,Beijing University of Chemical Technology | Huang Y.,Beijing University of Chemical Technology | Wang F.,Beijing University of Chemical Technology
Bioresource Technology | Year: 2013

A hierarchical porous carbon obtained from pig bone (HPC) was utilized as the adsorbent for removal of Cr(VI) from aqueous solution. The effects of solution pH value, concentration of Cr(VI), and adsorption temperature on the removal of Cr(VI) were investigated. The experimental data of the HPC fitted well with the Langmuir isotherm and its adsorption kinetic followed pseudo-second order model. Compared with a commercial activated carbon adsorbent (Norit CGP), the HPC showed an high adsorption capability for Cr(VI). The maximum Cr(VI) adsorption capacity of the HPC was 398.40. mg/g at pH 2. It is found that a part of the Cr(VI) was reduced to Cr(III) on the adsorbent surface from desorption experiment data. The regeneration showed adsorption capacity of the HPC can still achieve 92.70. mg/g even after fifth adsorption cycle. © 2013 Elsevier Ltd.


Zhang C.,Beijing University of Chemical Technology | Xiao G.,Beijing University of Chemical Technology | Peng L.,Beijing University of Chemical Technology | Su H.,Beijing University of Chemical Technology | Tan T.,Beijing University of Chemical Technology
Bioresource Technology | Year: 2013

This study assessed the anaerobic co-digestion of food waste and cattle manure, in order to identify the key parameters that determine the biogas and methane yield. Results of both batch and semi-continuous tests indicated that the total methane production is enhanced in co-digestion, with an optimum food waste (FM) to cattle manure (CM) ratio of 2. At this ratio, the total methane production in batch tests was enhanced by 41.1%, and the corresponding methane yield was 388mL/g-VS. In the semi-continuous mode, the total methane production in co-digestion, at the organic loading rate (OLR) of 10g-VSFW/L/d, increased by 55.2%, corresponding to the methane yield of 317mL/g-VS. Addition of cattle manure enhanced the buffer capacity (created by NH4+ and VFAs), allowing high organic load without pH control. The C/N ratio and the higher biodegradation of lipids might be the main reasons for the biogas production improvement. © 2012 Elsevier Ltd.


Zhang P.,Beijing University of Chemical Technology | Sun F.,Beijing University of Chemical Technology | Shen Z.,Beijing University of Chemical Technology | Cao D.,Beijing University of Chemical Technology
Journal of Materials Chemistry A | Year: 2014

A series of ZIF-derived porous carbon materials are prepared via co-carbonization of ZIF-7 and additional carbon sources, such as glucose, ethylene glycol, glycerol and furfuryl alcohol. Results indicate that ZIF-7/glucose composite-derived Carbon-L-950 as an electrode for the electrochemical capacitor exhibits a high specific capacitance of 228 F g -1 in 6 M KOH at a current density of 0.1 A g-1, even 178 F g-1 at a high current of 10 A g-1 and good stability over 5000 cycles. Moreover, the conductive agent (like acetylene black) is not required in the preparation process of the working electrode, which not only lowers the preparation costs but also is favorable for stability and performance. This facile fabrication of ZIF-derived porous carbon materials may open up a new avenue for producing a new family of porous carbon materials for advanced energy storage devices, such as fuel cells, supercapacitors and lithium batteries. © 2014 the Partner Organisations.


Xiang Z.,Beijing University of Chemical Technology | Fang C.,Beijing University of Chemical Technology | Leng S.,Beijing University of Chemical Technology | Cao D.,Beijing University of Chemical Technology
Journal of Materials Chemistry A | Year: 2014

In this work, metal-organic framework (MOF) UMCM-1 and amino functionalized MOF (i.e., UMCM-1-NH2) were synthesized and their performances as luminescent probes were investigated. It is found that both unmodified and amino functionalized MOFs exhibit a luminescence quenching effect on metal ions. In particular, the amino functionalized MOF (UMCM-1-NH2) possesses high sensitivity and selectivity for Fe3+ ions and the luminescence is completely quenched in 10-3 M DMF solution of Fe3+. Moreover, the regenerated UMCM-1-NH2 still has high selectivity for Fe3+ ions, which suggests that the functionalized UMCM-1-NH 2 is a promising luminescent probe for selectively sensing iron ions. This journal is © the Partner Organisations 2014.


Ning X.,Hunan University | Zhong W.,Hunan University | Li S.,Hunan University | Wang Y.,Beijing University of Chemical Technology | Yang W.,Beijing University of Chemical Technology
Journal of Materials Chemistry A | Year: 2014

Nitrogen-doped porous graphene/carbon (NPGC) framework electrode materials have been synthesized via chemical activation of graphene oxide/polypyrrole (GOP) composites with KOH. The effects of the mass ratio of KOH/GOP and activation temperature on the electrochemical performance of NPGC have been discussed. It is found that the NPGC prepared by activating GOP (GO:Py = 1:40) with 3.5 times mass of KOH at 650 °C (NPGC650) exhibits the highest specific capacitance of 405 F g-1 at a current density of 0.2 A g -1. Particularly, the specific capacitance still remains at 249 F g-1 even at a current density as high as 10 A g-1. Moreover, 96% of the capacitance can be retained after 1000 cycles even under a high operation current of 10 A g-1. The present work provides a novel strategy to synthesize NGPC electrode material for supercapacitors. This journal is © the Partner Organisations 2014.


Jin Z.,Beijing Forestry University | Yan X.,Beijing University of Chemical Technology | Yu Y.,Beijing University of Chemical Technology | Zhao G.,Beijing Forestry University
Journal of Materials Chemistry A | Year: 2014

Activated carbons are regarded as the most important electrode materials for commercial supercapacitors because of their low cost, high surface area, and good electrical conductivity. The environmentally friendly, low-cost and renewable biomass is a promising raw material for the high-performance carbon electrode material. Herein, a series of activated carbon fibers (ACFs) are fabricated by one-step carbonization and activation of wood-derived fibers with different activation times. The micropore surface area, mesopore/micropore ratio and pore size of the ACF series are successfully controlled by adjusting the levels of burn-off in order to study the effects of these parameters on specific capacitance and rate capability. Electrochemical measurements show that the electrochemical performance of the ACF series increases with the progress of gasification unless excessive burn-off occurs. The sample with optimal structure exhibits an outstanding specific capacitance of 280 F g-1 at 0.5 A g-1 and excellent rate capability (81.8% capacitance retention at 10 A g-1) in 1 M H2SO4. Furthermore, it demonstrates good cyclic stability, showing a high capacitance retention of 99.3% over 2000 charge-discharge cycles. The excellent electrochemical performance of this sample is attributed to the large micropore surface area, a proportion of mesopores in the range of 3-4 nm, good electrical conductivity and fast charge transfer. This journal is © the Partner Organisations 2014.


Gong H.-C.,Beijing University of Chemical Technology
Advanced Materials Research | Year: 2014

In order to diagnose the economic performance of unit online, a new algorithm to forecast the exhaust enthalpy in the steam turbine online based on RBF process neural network with to hidden layers neural network is introduced in this paper. This online forecasting method establishes the complicated relation model between the steam turbine exhaust enthalpy and the relative operating parameters. The enthalpy of the last stage extraction steam and that of the exhaust are online calculated for a 300MW set in this paper. The example result shows that this method can accurately forecast the steam turbine exhaust enthalpy and the model is simple, accurate and convergence. This is an effective and feasible predicting method. © (2014) Trans Tech Publications, Switzerland.


Zhou D.,Beijing University of Chemical Technology | Mi J.,Beijing University of Chemical Technology | Zhong C.,Beijing University of Chemical Technology
Journal of Physical Chemistry B | Year: 2012

We present a three-dimensional density functional approach to investigate heterogeneous nucleation behaviors of Lennard-Jones fluid on solid walls. In the theoretical calculation, fast Fourier transforms to compute the convolutions of Euler-Lagrange equation enables a high-efficient algorithm in three-dimensional space. The density distributions of a growing nucleus are presented to account for the nucleation process. Accordingly, the structures of nucleated droplet and surrounding supersaturated vapor on different walls are analyzed, and the corresponding free energy barriers and the critical radii are obtained to evaluate the difficulty of droplet formation. Since the theoretical approach is strictly constructed in three-dimensional space, and the liquid-solid, vapor-solid, and vapor-liquid interfacial tensions as well as the vapor-liquid-solid line tension are entirely integrated into the excess free energy expression, the present approach provides a flexible and efficient tool for studying heterogeneous nucleation. © 2012 American Chemical Society.


Wang Y.,Beijing University of Chemical Technology | Yang Y.,Beijing University of Chemical Technology | Zhao Z.,Beijing University of Chemical Technology
Journal of Process Control | Year: 2013

A novel combination of PI control and iterative learning control (ILC), referred to enhanced ILC-based PI control, was proposed in this study. This algorithm could be used on a class of multi-input multi-output batch processes with modeling uncertainties and unknown disturbances. Based on a two-dimensional (2D) Roesser's system description, a sufficient condition for robust asymptotical stability of the closed-loop system was derived in this paper. Furthermore, the monotonic convergence of the closed-loop system in the batch direction has been proved. Applications on a three-tank system show that the proposed method can achieve the design objective well, with performance improvement along both time and batch direction, and also owns good robustness to uncertainties and non-repetitive disturbances. © 2012 Elsevier Ltd. All rights reserved.


Xie Y.,Beijing University of Chemical Technology | Yang H.,Beijing University of Chemical Technology | Wang Z.U.,Troy University | Liu Y.,Texas A&M University | And 2 more authors.
Chemical Communications | Year: 2014

A new porous metal-organic framework (MOF) with three types of preserved polyhedral molecular building units, all of which have been observed in a series of isostructural MOFs constructed from highly symmetrical hexacarboxylic ligands, was formed even from a pre-designed related tetracarboxylic ligand with drastically reduced symmetry. This journal is © The Royal Society of Chemistry 2014.


Wang Z.,Beijing University of Chemical Technology | Fu H.,Beijing University of Chemical Technology | Han D.,Beijing University of Chemical Technology | Gu F.,Beijing University of Chemical Technology
Journal of Materials Chemistry A | Year: 2014

Au-based nanocatalysts are usually capped with surfactant and cannot be directly used. Thermal annealing is an effective method for surface cleaning. However, the effect of Au species on activity in the thermal annealing process has not previously been researched. We studied the effects of surfactant and Au species on catalytic performance using Au@porous SiO2 (Au@pSiO2). It was found that Au@pSiO2 annealed at different temperatures showed different performances toward the reduction of 4-nitrophenol even though the size of Au was maintained. The activity of the annealed Au@pSiO2 was higher than that of the untreated sample. The sample annealed at 500°C had the best performance, and the catalytic activity was higher than that of the Au-based catalysts reported in the literature. It was concluded that the cationic Au species and the surfactant poly(vinyl pyrrolidone) (PVP) had a combined effect on catalytic performance. The removal of the surfactant PVP from the surface of the Au NPs during the thermal annealing process enhanced the activity, and the cationic Au species played a vital role in catalytic performance. The results are important in relation to surface cleaning and the determination of the pre-treatment conditions of catalysts. Surprisingly, there was an induction period for the untreated Au@pSiO2 in the catalytic process because PVP blocked the adsorption and migration of 4-nitrophenol on the surface of the Au. The disappearance of the induction period for the annealed samples can be attributed to the removal of PVP. © The Royal Society of Chemistry 2014.


Li K.,Beijing University of Chemical Technology | Wang W.,Beijing University of Chemical Technology | Cao D.,Beijing University of Chemical Technology
Journal of Physical Chemistry C | Year: 2011

Using the first-principles calculation, we investigate the adsorption of CO and NO on (8, 0) silicon nanotubes (SiNTs). The detailed analysis of the structural and electronical properties of various optimized configurations is performed. The results show that CO molecule can be chemisorbed on SiNT with the C atom bonding with the Si atom of the tubular surface when CO is located on the top site, accompanying with the binding energy of 1.559 eV and charge transfer of 0.658|e|, which are larger than the results of other configurations. For the SiNT-NO systems, there exist four strong chemical adsorption configurations. The most stable configuration is the N atom bonding with two Si atoms on the bridge site. The binding energy is 2.135 eV and charge transfer is 2.064|e|. In addition, it is found that both the C-O and N-O bonds are elongated when CO and NO are chemisorbed on SiNT. Compared to carbon nanotubes (CNTs) or silicon carbon nanotubes (SiCNTs), the SiNTs have stronger interaction with the CO and NO and can provide more sensitive signal for CO and NO sensing. In particular, the semiconducting (16, 0) SiNT would become metallic after adsorption CO, and the SiNTs after adsorption of NO would be magnetic, which can serve as a sensitive signal for CO or NO sensing. In short, the SiNTs with the semconducting structure are a very promising candidate for CO and NO sensing and detection. © 2011 American Chemical Society.


Luo D.,Beijing University of Chemical Technology | Zhang G.,Beijing University of Chemical Technology | Liu J.,Beijing University of Chemical Technology | Sun X.,Beijing University of Chemical Technology
Journal of Physical Chemistry C | Year: 2011

Reduced graphene oxide (RGO) is an intriguing nanomaterial with tremendous potential for many applications. Although considerable efforts have been devoted to develop the reduction methods, it still needs further improvement, and how to choose an appropriate one for a specific application is a troublesome problem. In this study, RGOs were prepared by six typical reduction methods: N2H4 · H2O, NaOH, NaBH4, solvothermal, high-temperature, and two-step. The samples were systematic compared by four aspects: dispersibility, reduction degree, defect repair degree, and electrical conductivity. On the basis of the comparison, a simple evaluation criterion was proposed for qualitatively judging the quality of RGO. This evaluation criterion would be helpful to understand the mechanism of reduction and design more ideal reduction methods. © 2011 American Chemical Society.


Zhu H.,Beijing University of Chemical Technology | Li X.,Beijing University of Chemical Technology | Wang F.,Beijing University of Chemical Technology
International Journal of Hydrogen Energy | Year: 2011

A Cu@Pt/C catalyst was synthesized by a two-step reduction method using Vulcan XC-72R as the supporting material. Physical and electrochemical techniques were applied to investigate the structure and performance of the catalyst. X-ray diffraction (XRD) and transmission electron microscopy (TEM) examinations showed that the catalyst has a core-shell structure, the distribution of the catalyst particles is quite uniform, and the particle size ranges from 5 to 6 nm. Cyclic voltammetry (CV) and rotating disk electrode (RDE) tests confirmed the high performance of the Cu@Pt/C catalyst with the atom ratio Cu: Pt of 2.73: 1, making it a promising low-Pt catalyst for proton exchange membrane fuel cell (PEMFC). © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.


Xu F.J.,Beijing University of Chemical Technology | Yang W.T.,Beijing University of Chemical Technology
Progress in Polymer Science (Oxford) | Year: 2011

The design of efficient gene delivery vectors is a challenging task in gene therapy. Recent progress in living/controlled radical polymerizations (LRPs), in particular atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain transfer (RAFT) polymerization providing a means for the design and synthesis of new polymeric gene vectors with well-defined compositions, architectures and functionalities is reviewed here. Polymeric gene vectors with different architectures, including homopolymers, block copolymers, graft copolymers, and star-shaped polymers, are conveniently prepared via ATRP and RAFT polymerization. The corresponding synthesis strategies are described in detail. The recent research activities indicate that ATRP and RAFT polymerization have become essential tools for the design and synthesis of advanced, noble and novel gene carriers. © 2011 Elsevier Ltd.


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.


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.


Chen M.,Beijing University of Chemical Technology | Wang Z.,Beijing University of Chemical Technology | Han D.,Beijing University of Chemical Technology | Gu F.,Beijing University of Chemical Technology | Guo G.,Beijing University of Chemical Technology
Journal of Physical Chemistry C | Year: 2011

Unique porous ZnO polygonal nanoflakes were synthesized by the microwave hydrothermal method. The structural properties of the products were investigated by using X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), and high-resolution TEM techniques. In situ diffuse reflectance infrared Fourier transform spectroscopy technique was employed to investigate the mechanism of NO2 sensing. Free nitrate ions, nitrate ions, and nitrite anions were the main adsorbed species. N2O was formed via NO- and N2O2 - that were stemmed from NO. Comparative tests for gas sensing between gas sensors based on the as-prepared porous ZnO nanoflakes and purchased ZnO nanoparticles clearly showed that the former exhibited more excellent NO2 sensing performances. Photoluminescence and X-ray photoelectron spectroscopy spectra further proved that the intensities of donors (oxygen vacancy (VO) and/or zinc interstitial (Zni)) and surface oxygen species (O 2 - and O2), which were involved in the mechanism of gas sensing led to the different gas-sensing properties. © 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.


Jin Y.,Beijing University of Chemical Technology | Jia M.,Beijing University of Chemical Technology | Zhang M.,Beijing University of Chemical Technology | Wen Q.,Beijing University of Chemical Technology
Applied Surface Science | Year: 2013

Using potassium hydroxide as the reduction agent, a stable aqueous dispersion of graphene nanosheets was successfully prepared and characterized for its structural and electrochemical properties for supercapacitor application. The structure and morphology of the as-prepared material were investigated by Fourier transform infrared spectra, X-ray diffraction pattern and high resolution transmission electron microscopy, respectively. The electrochemical supercapacitive properties of as-prepared material were evaluated using cyclic voltammetry, galvanostatic charge-discharge methods and electrochemical impedance spectroscopy. The as-prepared material showed maximum specific capacitance of (200 F g-1) in 6.0 M aqueous KOH electrolyte at scan rate 5 mV s-1. For comparison, we add the data of traditional chemical reduction agent-hydrazine. © 2012 Elsevier B.V. All rights reserved.


Jia Y.,Beijing University of Chemical Technology | Li Z.,Beijing University of Chemical Technology | Shi W.,Beijing University of Chemical Technology
Sensors and Actuators, B: Chemical | Year: 2013

The fabrication of the ordered colorimetric molecule/layered double hydroxide (LDH) ultrathin films (UTFs) by the LBL deposition technique was reported, and demonstrates their application as a colorimetric chemosensor for F-. The structural and surface morphology studies show that the UTF is continuous and uniform with stacking order in the normal direction of the substrate. The LDH nanoparticles isolate Alizarin complexone (AC) molecules from each other. The AC/LDH UTFs display a stepwise and regular growth of upon increasing deposition cycles proved by UV-vis absorption and a periodical layered structure perpendicular to the substrates with a thickness of 5.96-6.28 nm per bilayer observed by X-ray diffraction and scanning electron microscopy. Moreover, the (AC/LDH)20 UTF displays an excellent behavior as colorimetric chemosensor for F- with a low detection limit (12.9 μM), good regeneration and reversibility, high stability (light and storage stability) as well as selectivity. In addition, the mechanism of measurement-regeneration cycle for the colorimetric chemosensor indicates F - enters/departs from the AC/LDH UTF giving rise to reversible change in chemical composition and surface morphology of the UTF. Therefore, this work provides new opportunities for fabrication and application of chromophore/LDH UTFs as colorimetric chemosensors. © 2013 Elsevier B.V.


Zhang W.,Beijing University of Chemical Technology | Huang H.,Beijing University of Chemical Technology | Zhong C.,Beijing University of Chemical Technology | Liu D.,Beijing University of Chemical Technology
Physical Chemistry Chemical Physics | Year: 2012

In this work, the cooperative effect of temperature and linker functionality on CO 2 capture in metal-organic frameworks (MOFs) was investigated using experimental measurements in combination with molecular simulations. To do this, four MOFs with identical topology but different functional groups on the linkers and three important CO 2-containing industrial gas mixtures were adopted. The interplay between linker functionality and temperature was analyzed in terms of CO 2 storage capacity, adsorption selectivity, working capacity of CO 2 in temperature swing adsorption (TSA) processes, as well as sorbent selection parameter (S ssp). The results show that the effect of linker functionality on CO 2 capture performance in the MOFs is strongly interconnected with temperature: up to moderate pressures, the lower the temperature, the larger the effect of the functional groups. Furthermore, the modification of a MOF by introducing more complex functional groups can not only improve the affinity of framework for CO 2, but also reduce the free volume, and thus may contribute negatively to CO 2 capture capability when the packing effect is obvious. Therefore, when we design a new MOF for a certain CO 2 capture process operated at a certain temperature, the MOF should be designed to have maximized affinity for CO 2 but with a negligible or small effect caused by the reduction of free volume at that temperature and the corresponding operating pressure. © 2012 the Owner Societies.


Zhong X.,Beijing University of Chemical Technology | Fan Z.,Beijing University of Chemical Technology | Liu Z.,Beijing University of Chemical Technology | Cao D.,Beijing University of Chemical Technology
Journal of Physical Chemistry B | Year: 2012

Our recently developed improved united atom force field shows a good quality to reproduce both the static and transport properties of neat ionic liquids (ILs). Combined with the TIP4P-Ew water model, the force field is used to simulate the mixture of 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]) and water without further optimization to adjust any cross parameters. Liquid densities of the mixture are well predicted over the entire concentration range at temperatures from 298.15 to 353.15 K. Simulations also reproduce the positive values of excess volumes and excess enthalpies, as well as their increase with temperature. The simulated viscosities are in good agreement with experimental values, especially in the water-rich region. We found three distinct regions by analyzing the concentration dependent self-diffusion coefficients via Stokes-Einstein (SE) relation, indicating the mixture experiences significant microheterogeneity with the adding of water. This observation is well connected to the structure features obtained in simulations, such as radial distribution functions (RDFs), spatial distribution functions (SDFs) and water clustering analysis. At the water mole fraction (x2) less than 0.2, most of the water molecules are isolated in the polar cation-anion network in ionic liquids. With the increase of x2 from 0.2 to 0.8, large water cluster forms and eventually percolates the whole system. When x2 > 0.8, ionic liquids show a moderate degree of aggregation (with maximum around 0.9 to 0.95) before the cations and anions are fully dissolved in water. © 2012 American Chemical Society.


Liu M.,Beijing University of Chemical Technology | Su H.,Beijing University of Chemical Technology | Tan T.,Beijing University of Chemical Technology
Carbohydrate Polymers | Year: 2012

Various interpenetrating polymer network (IPN) hydrogels with sensitivity to temperature and pH were prepared by introducing the pH-sensitive polymer polyaspartic acid (PASP) hydrogel, into the poly(Nisopropylacrylamide) (PNIPAAm) hydrogel system for the purpose of improving its response rate to temperature. The morphologies and thermal behavior of the prepared IPN hydrogels were studied by both scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The IPN hydrogels showed a large and uneven porous network structure, without showing the common PNIPAAm hydrogel structure. The paper moreover studied their swelling properties, such as temperature dependence of equilibrium swelling ratio, shrinking kinetics, re-swelling kinetics and oscillatory swelling behavior in water. The swelling experiment results revealed that IPN hydrogels exhibited much faster shrinking and re-swelling in function of the composition ratio of the two network components. These fast responsive hydrogels foster potential applications in biomedical and biotechnology fields. © 2011 Elsevier Ltd.


Shi W.,Beijing University of Chemical Technology | He S.,Beijing University of Chemical Technology | Wei M.,Beijing University of Chemical Technology | Evans D.G.,Beijing University of Chemical Technology | Duan X.,Beijing University of Chemical Technology
Advanced Functional Materials | Year: 2010

The preparation of a highly oriented photoluminescent film of fluorescein (FLU) and 1-heptanesulfonic acid sodium (HES) co-intercalated in a layered double hydroxide (LDH) matrix by electrophoretic deposition (EPD) is reported, and its application as an optical pH sensor is demonstrated. The FLU-HES/LDH films with thickness ranging from nanometer to micrometer on indium tin oxide substrates exhibite good c-orientation of LDH platelets (the ab-plane of the LDH platelets parallel to the substrate), as confirmed by X-ray diffraction and scanning electron microscopy. Polarized luminescence of the film is observed with anisotropy value r = 0.29, resulting from the highly oriented FLU in the LDH gallery. Furthermore, the optical pH sensor with film thickness of 300 nm exhibits a broad linear dynamic range for solution pH (5.02-8.54), good repeatability (relative standard deviation (RSD) less than 1.5% in 20 consecutive cycles) and reversibility (RSD less than 1.5% in 20 cycles), high photostability and storage stability (ca. 95.2% of its initial fluorescence intensity remains after one month) as well as fast response time (2 s). Therefore, this work creates new opportunities for the preparation and application of LDH-based chromophores in the field of optical sensors. An optical pH sensor based on fluorescein intercalated in a layered double hydroxide matrix film is fabricated by electrophoretic deposition. In addition to its facile preparation, its characterization is described, by which its high sensitivity and stabilityboth mechanical and photostability as well as its rapid response are demonstrated. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Ma G.,Beijing University of Chemical Technology | Fang D.,Changzhou University | Liu Y.,Changzhou University | Zhu X.,Changzhou University | Nie J.,Beijing University of Chemical Technology
Carbohydrate Polymers | Year: 2012

Core-shell structure nanofibers of sodium alginate/poly(ethylene oxide) were prepared via electrospinning their dispersions in water solution. The core-shell structure morphology of the obtained nanofibers was viewed under scanning electron microscope (SEM) and transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS) analysis was used to further quantify the chemical composition of the core-shell composite SA/PEO nanofibers surface in detail. Furthermore, one-step cross-linking method through being immersed in CaCl2 solution was investigated to improve the anti-water property of the electrospun nanofibers mats in order to facilitate their practical applications as tissue engineering scaffolds, and the changes of the structural of nanofibers before and after cross-linking was characterized by Fourier transform infrared (FT-IR). Indirect cytotoxicity assessment indicated that SA/PEO nanofibers membrane was nontoxic to the fibroblasts cells, and cell culture suggested that SA/PEO nanofibers tended to promote fibroblasts cells attachment and proliferation. It was assumed that the nanofibers membrane of electrospun SA/PEO could be used for tissue engineering scaffolds. © 2011 Published by Elsevier Ltd.


Liang R.,Beijing University of Chemical Technology | Wei M.,Beijing University of Chemical Technology | Evans D.G.,Beijing University of Chemical Technology | Duan X.,Beijing University of Chemical Technology
Chemical Communications | Year: 2014

Inorganic nanomaterials including gold nanoparticles, mesoporous silica nanoparticles, graphene, magnetic nanoparticles, quantum dots and layered double hydroxides have become one of the most active research fields in biochemistry, biotechnology and biomedicine. Benefiting from the facile synthesis/modification, intrinsically physicochemical properties and good biocompatibility, inorganic nanomaterials have shown great potential in bioimaging, targeted drug delivery and cancer therapies. This Feature Article summarizes recent progress on various inorganic nanocarriers, including the background, synthesis, modification, cytotoxicity, physicochemical properties as well as their applications in biomedicine. This journal is © the Partner Organisations 2014.


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.


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.


Li Y.,Beijing University of Chemical Technology | Chen F.,Beijing University of Chemical Technology | Nie J.,Beijing University of Chemical Technology | Yang D.,Beijing University of Chemical Technology
Carbohydrate Polymers | Year: 2012

The core-shell structure nanofibers of poly(lactic acid)/chitosan with different weight ratios were successfully electrospun from homogeneous solution. The preparation process was more simple and effective than double-needle electrospinning. The nanofibers were obtained with chitosan in shell while poly(lactic acid) in core attributing to phase separation, which were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). The electrospun nanofibrous membrane was evaluated in vitro by using mouse fibroblasts (L929) as reference cell lines. Cell culture results indicated that these materials were good in promoting cell growth and attachment, thus they could be used for tissue engineering and wound healing dressing. © 2012 Elsevier Ltd. All rights reserved.


Wang T.,Beijing University of Chemical Technology | Nie J.,Beijing University of Chemical Technology | Yang D.,Beijing University of Chemical Technology
Carbohydrate Polymers | Year: 2012

A two-component tissue adhesive based on biocompatible and bio-degradable polymers (oxidized urethane dextran (Dex-U-AD) and gelatin) was prepared and photocrosslinked under the ultraviolet (UV) irradiation. The adhesive could adhere to surface of gelatin, which simulated the human tissue steadily. The structures of above Dex-U-AD were characterized by FTIR, 1H NMR spectroscopy and XRD. The adhesion property of result products was evaluated by lap-shear test. The maximum adhesion strength could reach to 4.16 ± 0.72 MPa which was significantly higher than that of fibrin glue. The photopolymerization process of Dex-U-AD/gelatin was monitored by real time infrared spectroscopy (RTIR). It took less than 5 min to complete the curing process. The cytotoxicity of Dex-U-AD/gelatin also was evaluated which indicated that Dex-U-AD/gelatin gels were nontoxic to L929 cell. The relationship between all the above-mentioned properties and degree of oxidization of Dex-U-AD was assessed. The obtained products have the potential to serve as tissue adhesive in the future. © 2012 Elsevier Ltd. All rights reserved.


Zhang D.,Beijing University of Chemical Technology | Ren C.,Beijing University of Chemical Technology | Yang W.,Beijing University of Chemical Technology | Deng J.,Beijing University of Chemical Technology
Macromolecular Rapid Communications | Year: 2012

This Communication reports optically active helical substituted polyacetylenes which solely catalyzed asymmetric Aldol reaction between cyclohexanone and p-nitrobenzaldehyde; more importantly the helical structures are found to play crucial roles in the asymmetric catalysis, with a remarkable yield and ee (both up to 80%). A synergic effect is observed between the helical structures in the polymer main chains and the pendent prolinamide moieties for successfully catalyzing the asymmetric reaction. The role of the helical polymer backbones is further verified by tuning the relative helical structure content. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Liu D.,Beijing University of Chemical Technology | Zhang L.,Beijing University of Chemical Technology | Li M.,Beijing University of Chemical Technology | Yang W.,Beijing University of Chemical Technology | Deng J.,Beijing University of Chemical Technology
Macromolecular Rapid Communications | Year: 2012

This communication reports the first integration of two significant concepts, "macromolecular helicity-derived chirality," and "magneticity" in one single microsphere entity. The novel chiral magnetic composite microspheres consisted of magnetic Fe 3O 4 nanoparticles and optically active helical substituted polyacetylene. Therefore, they exhibited both remarkable optical activity and magneticity. The microspheres adsorbed (R)-(+)-1-phenylethylamine much more quickly than the other enantiomer, demonstrating the potential applications of the chiral magnetic composite microspheres in chiral recognition and chiral resolution. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


He Y.,Beijing University of Chemical Technology | Liang L.,Beijing University of Chemical Technology | Liu Y.,Beijing University of Chemical Technology | Feng J.,Beijing University of Chemical Technology | And 2 more authors.
Journal of Catalysis | Year: 2014

An effective and versatile synthetic approach is presented to produce highly dispersed bimetallic Pd-Ga catalysts that can be used as hydrogenation catalysts. Mg-Ga-Al-layered double hydroxide (LDH) was synthesized in situ on the surface of spherical alumina to obtain MgGaAl-LDH@Al2O 3 precursor, followed by the introduction of PdCl42-. The positive charge of MgGaAl-LDH layer offers an opportunity to realize uniform dispersion of PdCl42-, which facilitates the formation of bimetallic Pd-Ga nanoalloys. Upon thermal reduction of PdCl42-/MgGaAl-LDH@Al2O3 precursor, highly stable dispersed bimetallic Pd-Ga/MgO-Al2O3 catalysts were obtained. Owing to high dispersion and synergistic effect of bimetallic nanoalloys, Pd-Ga/MgO-Al2O3 catalysts exhibited comparable activity and much higher selectivity compared with the monometallic Pd/MgO-Al2O3 in partial hydrogenation of acetylene. More significantly, this good catalytic performance can be totally retained after three times recycling due to the net trap confinement effect, which suppressed the migration and aggregation of bimetallic Pd-Ga nanoalloys. © 2013 Elsevier Inc. All rights reserved.


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.


Jianwen Z.,Beijing University of Chemical Technology | Da L.,Beijing University of Chemical Technology | Wenxing F.,Petrochina
Journal of Hazardous Materials | Year: 2014

China is well known being rich in sulfurous natural gas with huge deposits widely distributed all over the country. Due to the toxic nature, the release of hydrogen sulfide-containing natural gas from the pipelines intends to impose serious threats to the human, society and environment around the release sources. CFD algorithm is adopted to simulate the dispersion process of gas, and the results prove that Gaussian plume model is suitable for determining the affected region of the well blowout of sulfide hydrogen-containing natural gas. In accordance with the analysis of release scenarios, the present study proposes a new approach for estimating the risk of hydrogen sulfide poisoning hazards, as caused by sulfide-hydrogen-containing natural gas releases. Historical accident-statistical data from the EGIG (European Gas Pipeline Incident Data Group) and the Britain Gas Transco are integrated into the approach. Also, the dose-load effect is introduced to exploit the hazards' effects by two essential parameters - toxic concentration and exposure time. The approach was applied to three release scenarios occurring on the East-Sichuan Gas Transportation Project, and the individual risk and societal risk are classified and discussed. Results show that societal risk varies significantly with different factors, including population density, distance from pipeline, operating conditions and so on. Concerning the dispersion process of hazardous gas, available safe egress time was studied from the perspective of individual fatality risks. The present approach can provide reliable support for the safety management and maintenance of natural gas pipelines as well as evacuations that may occur after release incidents. © 2013 Elsevier B.V.


Gao Y.,Beijing University of Chemical Technology | Gu Y.,Beijing University of Chemical Technology | Wei Y.,Beijing University of Chemical Technology
Journal of Agricultural and Food Chemistry | Year: 2011

An analytical method for the quantitative determination of migration levels of polymer additives such as antioxidants and UV absorbers in food packages by high-performance liquid chromatography coupled with UV-vis photodiode array detection has been developed. The pretreatment step involved solid-phase extraction with silica C18 cartridges. The analytical method showed good linearity, presenting regression coefficients (R 2) ≥0.9990 for all compounds. This optimized method was also validated with respect to precision, reproducibility, stability, and accuracy. The limits of detection and quantification were between 0.09 and 1.72 μg mL -1 and between 0.20 and 5.64 μg mL -1 for 12 analytes, respectively. Recoveries were in the range of 67.48 and 108.55%, with relative standard deviations between 2.76 and 9.81%. Migration levels of antioxidants and UV absorbers were determined. Butylated hydroxyanisole, 2,6-di-tert-butyl-4-methylphenol (BHT), 2,4-di-tert-butylphenol, Cyanox 2246, Irganox 1035, Tinuvin 326, Tinuvin 328, Irganox 1010, and Irganox 1330 were detected; BHT and Cyanox 2246 were at higher levels than the specific migration levels in some food simulants. © 2011 American Chemical Society.


Liu H.,Beijing University of Chemical Technology | Zhao L.,Beijing University of Chemical Technology | Wang J.,Beijing University of Chemical Technology | He J.,Beijing University of Chemical Technology
Journal of Catalysis | Year: 2013

The catalysts using layered double hydroxide (LDH) nanosheet-modified α-amino acid anions as ligands has been proved to be easily recycled in vanadium-catalyzed asymmetric epoxidation of cinnamyl alcohol with the enantioselectivity well preserved and the yield only slightly reduced. The α-amino acids employed here include l-glutamate, l-alanine, and l-serine, which are anchored to LDH layers through monodentate electrostatic interactions in the ascending intensity while coordinated with vanadium center in the coordinating intensity of l-glutamate > l-serine > l-alanine. The stronger coordination with α-amino acid anion caused the vanadium center to be leached independently in less percentage, while the leaching of α-amino acid anion depends on the dual host-guest interactions. In nanosheet-modified l-glutamate system, all of the vanadium centers leached together with l-glutamate, but in nanosheet-modified l-alanine system, all of the vanadium centers leached independently. The electrostatic interaction of brucite-like layer with l-serine is stronger than with l-alanine, yet the stronger coordination of l-serine to vanadium caused more l-serine to be leached. The weakest electrostatic interactions between intercalated l-glutamate and LDH layer result in the visible loss of l-glutamate in the vanadium/LDH nanosheet-modified l-glutamate system, but the V-glutamate species leached into the solution was catalytically active in the epoxidation, compensating for the activity loss in the recycling experiments in spite of the higher l-glutamate leaching. © 2012 Published by Elsevier Inc.


Chen H.,Beijing University of Chemical Technology | Huang K.,Beijing University of Chemical Technology | Wang S.,Beijing University of Chemical Technology
Separation and Purification Technology | Year: 2010

Although the ideal heat-integrated distillation column (ideal HIDiC) is much more thermodynamically efficient than its conventional analogues, its applications in the chemical and petrochemical process industries have been restrained due to the great difficulties and complexities in the design and implementation of internal heat integration between the rectifying section and the stripping section. For the avoidance of these difficulties and complexities, a novel simplified configuration for the ideal HIDiC, termed the SIHIDiC, is proposed and studied in this paper. Only three internal heat exchangers are used to approximate the internal heat integration, and their locations and sizes are key decision variables for process synthesis and design and should be considered to enhance thermodynamic efficiency in process development. A simple stepwise procedure is thus derived for process synthesis and design, and the SIHIDiC is then evaluated through intensive comparison with conventional distillation columns and the ideal HIDiC in terms of the separations of ethylene/ethane and benzene/toluene binary mixtures. The results obtained indicate that the SIHIDiC could be an excellent candidate to approximate the ideal HIDiC with reduced capital investment and somewhat similar (if not smaller) operating cost. The SIHIDiC offers essentially a much simpler way than the current available methods to design and implement the concept of the ideal HIDiC into separation processes. © 2010 Elsevier B.V. All rights reserved.


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.


Shi H.,Beijing University of Chemical Technology | Yu C.,Beijing University of Chemical Technology | He J.,Beijing University of Chemical Technology
Journal of Catalysis | Year: 2010

Kagan-Medona and Sharpless titanium tartrate complexes (Ti(IV)TA m, subscript m represents the coordination ratio of l-tartaric acid to the Ti center in the complex) have been intercalated into the interlayer of layered double hydroxides (LDHs) by anionic exchange method using Mg/Al-CO 3 LDH as the precursor. Titanium tartrate-intercalated LDHs (designated Mg/Al-Ti(IV)TA m LDHs) with varied interlayer spacing were produced by tuning the area unit charge (A c) of the brucite-like layer from 0.24 to 0.44 nm 2. The interlayer spacing decreases from 1.87 to 1.44 nm with the increase in A c. The interlayer titanium tartrate anions are present in an interdigitated bilayer arrangement. The bidimensional interlayer space can be swollen, and thus accommodates the reactants in the interlayer. The titanium tartrate complex constrained in the LDH interlayer region shows enhanced asymmetric induction in the heterogeneous sulfoxidation of pro-chiral methyl phenyl sulfide. © 2010 Elsevier Inc. All rights reserved.


Liu J.,Beijing University of Chemical Technology | Wang L.,Beijing University of Chemical Technology | Sun X.,Beijing University of Chemical Technology | Zhu X.,Anton Paar
Angewandte Chemie - International Edition | Year: 2010

Line them up: Uniform CeVO4 nanorod arrays (see picture) were synthesized in a self-assembly approach assisted by ethylenediaminetetraacetic acid (EDTA) molecules in aqueous media. EDTA is important not only in controlling anisotropic growth by restricting the active points of certain faces, but also in mediating the assembly by forming intermolecular hydrogen bonds. (Figure Equation Present). © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.


Li M.,Beijing University of Chemical Technology | Dong H.-R.,Beijing University of Chemical Technology
Separation and Purification Technology | Year: 2010

In this paper, a new technique, aqueous two-phase floatation (ATPF) which combines solvent sublation with aqueous two-phase system was used to separate and concentrate lincomycin. In the ATPF system of polyethylene glycol (PEG)/inorganic salt, the effects of solution pH, PEG molecular weight, concentration of inorganic salt in aqueous solution, nitrogen flow rate and floatation time were investigated in details, and the optimal conditions for ATPF were obtained. Under optimal conditions, the distribution ratio of ATPF was more than 118. Compared with aqueous two-phase extraction (ATPE), ATPF can not only separate and concentrate lincomycin from aqueous phase, but also efficiently reduce the wastage of PEG. The kinetics of the process of lincomycin in ATPF was also studied, and results showed it could be divided into two stages distinctly, and each stage obeyed the first-order kinetic equation. © 2010 Elsevier B.V. All rights reserved.


Bi P.-Y.,Beijing University of Chemical Technology | Dong H.-R.,Beijing University of Chemical Technology | Yuan Y.-C.,Beijing University of Chemical Technology
Separation and Purification Technology | Year: 2010

Aqueous two-phase flotation (ATPF), which has the advantages of both solvent sublation and aqueous two-phase extraction, is an effective separation technique for separating strongly polar compounds. A highly effective, economically applicable and environmentally safe method has been successfully developed for separating puerarin from Puerariae extract. In an ATPF system composed of polyethylene glycol (PEG)/ammonium sulfate, the effects of various solution pHs, polymer molar masses, concentrations of ammonium sulfate in aqueous solution, nitrogen flow rates, flotation time and initial volumes of the PEG phase were investigated. Under the selected optimal conditions, the separation efficiency of ATPF was more than 87%. The comparison results between aqueous two-phase extraction (ATPE) and ATPF showed that ATPF can effectively separate puerarin from a Puerariae extract with high concentration coefficient. At the same time, the flotation product was purified by high-speed counter-current chromatography (HSCCC), and the purity of the final product was more than 95%. The experimental results show that ATPF-HSCCC is an effective method for preparing higher purity puerarin from a Puerariae extract. © 2010 Elsevier B.V. All rights reserved.


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.


Xia Y.,Beijing University of Chemical Technology | Dai H.,Beijing University of Chemical Technology | Jiang H.,Beijing University of Chemical Technology | Zhang L.,Beijing University of Chemical Technology
Catalysis Communications | Year: 2010

Three-dimensional (3D) ordered mesoporous cubic Co3O4 (denoted as Co-KIT6 and Co-SBA16) were fabricated adopting the KIT-6- and SBA-16-templating strategies, respectively. It is shown that Co-KIT6 and Co-SBA16 possessed large surface areas (118-121 m2/g), high oxygen adspecies concentrations, and good low-temperature reducibility. Over Co-KIT6 at space velocity = 20,000 mL/(g h), 90% toluene and methanol conversions were achieved at 180 and 139 °C, respectively. The excellent catalytic performance of Co-KIT6 and Co-SBA16 was associated with their larger surface areas, higher oxygen adspecies concentrations, better low-temperature reducibility, and 3D ordered mesoporous structure. © 2010 Elsevier B.V. All rights reserved.


Zhang M.,Beijing University of Chemical Technology | Jia M.,Beijing University of Chemical Technology | Jin Y.,Beijing University of Chemical Technology | Shi X.,Beijing University of Chemical Technology
Applied Surface Science | Year: 2012

We developed one-spot in situ synthesis method to fabricate CoO/reduced graphene oxide (CoO/RGO) nanocomposite by directly employing C4H 6O4·Co·4H2O and hydrophilic graphite oxides as raw materials. The electrochemical performances of the as-prepared CoO/RGO nanocomposite were evaluated in coin-type cells. It delivers a high reversible capacity of 740.7 mAh g-1 at 100 mA g -1, and retains a capacity retention of 95% after 50 cycles. Even after 435 cycles at various rates from 100 to 4000 mA g-1, the capacity still retains 577.9 mAh g-1 when the current density is back to 100 mA g-1. The extraordinary performance is ascribed to the well-designed structure of the CoO/RGO nanocomposite. The small-sized, high crystalline and dense CoO nanoparticles uniformly disperse on conductive graphene substrates, supplying large number of accessible active sites for lithium-ion insertion, short diffusion length for lithium ions, good conductivity and strong interfacial interaction between CoO nanoparticles and RGO nanosheets, which are beneficial for high capacity and long cycling stability. © 2012 Elsevier B.V.


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.


Han J.,Beijing University of Chemical Technology | Dou Y.,Beijing University of Chemical Technology | Wei M.,Beijing University of Chemical Technology | Evans D.G.,Beijing University of Chemical Technology | Duan X.,Beijing University of Chemical Technology
Angewandte Chemie - International Edition | Year: 2010

"Chemical Equation Presented" A reversible nanoporous antireflection coating can be fabricated by assembly of layered double hydroxide nanoparticles with polyanions using an electrostatic layer-by-layer method followed by calcination. Antireflection properties of the coating can be switched between the porous and non-porous state by alternating calcination and rehydration processes. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.


Jiang F.,Beijing University of Chemical Technology | Wang X.,Beijing University of Chemical Technology | Wu D.,Beijing University of Chemical Technology
Energy | Year: 2016

We have designed a type of dual-functional magnetic microcapsules containing a phase change material core and an organo-silica shell for the electromagnetic shielding and thermal regulating PI (polyimide) films. The magnetic microcapsules were synthesized through interfacial polycondensation in a reverse emulsion templating system. The resulting microcapsules show an interesting cup-like morphology as well as a well-defined core-shell structure. Their chemical compositions and crystalline structures were confirmed by Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and X-ray powder diffraction. The magnetic microcapsules not only achieved good phase-change performance and high energy-storage efficiency but also exhibited a superparamagnetic nature. PI/magnetic microcapsules hybrid films were fabricated through casting the poly(amic acid)/magnetic microcapsules mixtures onto glass plates followed by thermal imidization. The scanning electronic microscopy indicates a good interfacial adhesion between the PI matrix and magnetic microcapsules, resulting in a homogeneous dispersion of the microcapsules in the hybrid films accordingly. The hybrid films are also endowed with both temperature retention and microwave absorbing capabilities due to the introduction of magnetic microcapsules. With such a dual-functional feature, the PI-based hybrid films developed by this work show potential applications for the manufacture of microelectronic elements and electronic devices with anti-jamming and thermal regulating effectiveness. © 2016 Elsevier Ltd.


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.


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.


Wang H.,Beijing University of Chemical Technology | Zeng X.,Beijing University of Chemical Technology | Cao D.,Beijing University of Chemical Technology
Journal of Materials Chemistry A | Year: 2014

We develop a new S(DIH) equation based on the difference of isosteric heats (DIH) to calculate the selectivity for CO2 over CH4 in metal-organic frameworks (MOFs) and covalent-organic materials. Using the S(DIH) equation to predict the selectivity requires only the adsorption isotherms of pure components and the DIH of the two components. By comprehensive comparison with the GCMC data in different types of porous materials, including MOFs, ZIFs, COFs and PAFs, it is found that the new S(DIH) equation can predict with high accuracy the selectivity of different types of porous materials for CO 2 over CH4 at the low pressure of p = 0-1 bar. Therefore, the new S(DIH) can serve as an efficient tool for the selectivity predictions of porous materials for CO2 over CH4 at p = 0-1 bar, especially for the cases in which experiments can measure the adsorption isotherms and adsorption heats of pure components (such as CO2, CH4, N2 and H2) because the new S(DIH) requires only the adsorption isotherms and adsorption heats of pure components as inputs. In short, the new S(DIH) equation can be considered as a valuable screening tool for obtaining an estimation about the selectivity of a porous material for a certain component of the gas mixture. © 2014 the Partner Organisations.


Huang L.,Beijing University of Chemical Technology | Zeng X.,Beijing University of Chemical Technology | Cao D.,Beijing University of Chemical Technology
Journal of Materials Chemistry A | Year: 2014

The recently reported diamondyne is a fascinating new carbon allotrope with multifunctional applications (J. Mater. Chem. A, 2013, 1, 3851; ibid 2013, 1, 9433). Here we theoretically predict two new tetrahedral node diamondyne (TND) frameworks by replacing the carbon nodes of diamondyne and diamond with the acetylenic linkage (C-CC-C)-formed tetrahedron node. The two resulting theoretical materials (marked as TND-1 and TND-2) exhibit extremely high specific surface areas (SSA) of 6250 and 2992 m2 g-1, respectively. Interestingly, the SSA of TND-1 is calculated to be the highest among all porous carbon materials. By further studying the CO2 capture performance of TND-1 and TND-2, it is found that the CO2 uptake of TND-1 reaches 2461 mg g-1 at 298 K and 50 bar, which outperforms all MOFs, COFs and ZIFs, while the selectivity of TND-2 for CO 2/H2 reaches 104 at 35 bar, which is superior to most of the porous materials. In short, the hypothetical TND frameworks are promising candidates for CO2 capture in practical industry. This journal is © the Partner Organisations 2014.


Weng H.,Beijing University of Chemical Technology | Gao J.,Beijing University of Chemical Technology
Zhendong Ceshi Yu Zhenduan/Journal of Vibration, Measurement and Diagnosis | Year: 2013

The system of on-line condition monitoring and fault diagnosis has put forward strict requirement in real-time storage and remote transmission. As a common method in data processing, wavelet analysis has been widely used in data compression and achieved good effect. Methods of signal compression are presented based on wavelet firstly. According to analysis on the characters of the vibration-signal of rotating machinery and analysis on several key attributes of wavelet basis, a new selection method of optimum wavelet basis in vibration-signal compression of rotating machinery is proposed. The compression effect of corresponding wavelet basis is compared by using a practical fault vibration signal. The results show that, the signal-to-noise ratio of reconstructing signal can be improved effectively by choosing an appropriate wavelet basis function. The biorthogonal wavelet basis with lower vanishing moment in decomposition and higher regularity reconstruction is better fitting for complex vibration-signal compression of rotating machinery.


Lu X.,Beijing University of Chemical Technology | Zuo Y.,Beijing University of Chemical Technology | Zhao X.,Beijing University of Chemical Technology | Tang Y.,Beijing University of Chemical Technology
Corrosion Science | Year: 2012

A silane film is prepared on AZ91D magnesium alloy and the effect of the silane pretreatment on the performance of a Mg-rich primer on AZ91D alloy are studied. After the silane treatment, Si-O-Mg covalent bonds form between the silane film and magnesium substrate and Si-O-Si structure forms in the silane film. As the result, the adhesion of the Mg-rich primer to AZ91D substrate increases obviously. Machu test and electrochemical measurements indicate that the silane pre-treatment significantly improves the performance of the Mg-rich primer on AZ91D alloy, which is attributed to strengthened barrier effect of the coating system. © 2012 Elsevier Ltd.


Wang T.-C.,CAS Institute of Chemistry | Li H.-H.,Beijing University of Chemical Technology | Yan S.-K.,Beijing University of Chemical Technology
Chinese Journal of Polymer Science (English Edition) | Year: 2012

The effect of PBS on the morphological features of PVDF has been investigated by optical and atomic force microscopies under various conditions. It was found that neat PVDF forms large γ form spherulites with extraordinarily weak birefringence at 170°C. Adding 30% PBS makes PVDF exhibit intrigued flower-like spherulitic morphology. The growth mechanism was explained by the decrease of the supercooling and the materials dissipation. Increasing the PBS content to 70% favors the formation of ring banded spherulites. Temperature dependent experiments verify the a' phase transition occurs from the junction sites of the and γ crystals, while starts from the centers of a spherulites in the blends. Ring banded structures could be observed in neat PVDF, 70/30 blend and 30/70 blend when crystallized at 155°C, without γ crystals. The band period of PVDF a spherulites increases with crystallization temperature as well as the amount of PBS content. At 140°C, spherulites in neat PVDF lose their ring banded feature, while coarse spherulites consisting of evident lamellar bundles could be found in 30/70 blend. © 2012 Chinese Chemical Society Institute of Chemistry, CAS Springer-Verlag Berlin Heidelberg.


Cheng D.,Beijing University of Chemical Technology | Xu H.,Beijing University of Chemical Technology | Fortunelli A.,CNR Institute of Chemistry of organometallic Compounds
Journal of Catalysis | Year: 2014

Using a combination of analytic-potential and first-principles density functional theory (DFT) calculations, composition effects on energetics, adsorption energies, and catalytic activity of Au-Pd nanoalloys are investigated, selecting CO oxidation to CO2 as a prototypical reaction and 55-atom Au-Pd clusters with Mackay icosahedral structure as template systems. It is first shown that the Au54Pd1, Au43Pd12, Au42Pd13, and Au 12Pd43 nanoalloys with highly symmetric structures are well separated from other nanoalloys due to their special relative stability at the empirical potential and/or DFT levels, with CO adsorption energies on top of Au atoms found to be weakly dependent on composition in a range around 50:50 Au:Pd ratio. The explicit calculation of reaction energy barriers for the CO oxidation process then shows that these are sensitive to the composition of nanoalloys, where Au-rich clusters possess a high catalytic activity and the Au43Pd12 cluster is predicted to have the highest catalytic activity among the clusters here considered. Our results highlight a non-monotonous behavior of the catalytic activities of Au-Pd nanoalloys on composition that is of fundamental interest for the design of new catalysts, but also the subtleties of a delicate interplay of structural and electronic effects in determining reaction energetics, which are difficult to summarize into few, simple prescriptions. © 2014 Elsevier B.V. All rights reserved.


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.


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.


Bao M.,Beijing University of Chemical Technology | Su H.,Beijing University of Chemical Technology | Tan T.,Beijing University of Chemical Technology
Energy and Fuels | Year: 2012

The energy use of hydrogen is recognized for its environmental advantages. Its utilization is expected to grow significantly over the coming years, and the development of new production methods to complement or substitute the traditional steam reforming, gasification, or electrolysis will further enhance that growth. The microbial conversion of biomass is considered to be the route with the highest immediate potential for its significant hydrogen yield and low energy requirement. The present research investigates this potential, using starch as the raw material for dark fermentation and by using appropriate micro-organisms. Fermentation using a single micro-organism strain is shown to be of limited efficiency for H 2 production, with a low H 2 content and low yield. The combination of two bacterial strains, belonging to Bacillus sp and Brevumdimonas sp., respectively, and each with a specific action in the H 2 production, significantly enhances the biohydrogen production yield. Its H 2 yield reached 1.04 mol H 2/mol glucose, being twice the yield obtained with pure cultures. The specific hydrogen production rate was up to 400 mL H 2/(g biomass h). The end products were mainly butyric and acetic acid, with traces of ethanol. The dark fermentation of starch can be considered to be a butyrate-type fermentation. © 2012 American Chemical Society.


Shao M.,Beijing University of Chemical Technology | Ning F.,Beijing University of Chemical Technology | Zhao Y.,Beijing University of Chemical Technology | Zhao J.,Beijing University of Chemical Technology | And 3 more authors.
Chemistry of Materials | Year: 2012

Core-shell layered double hydroxide microspheres with tunable interior architecture have been synthesized by a facile and cost-effective in situ growth method. The SEM and TEM images revealed that the obtained microspheres display a three-dimensional architecture with core-shell, yolk-shell, and hollow interior structure respectively, with continuous changes in specific surface area and pore-size distribution. Moreover, the hollow NiAl-LDH microspheres exhibit excellent pseudocapacitance performance, including high specific capacitance and rate capability, good charge/discharge stability and long-term cycling life, owing to the greatly improved faradaic redox reaction and mass transfer. Therefore, this work provides a promising approach for the design and synthesis of structure tunable materials with largely enhanced supercapacitor behavior, which can be potentially applied in energy storage/conversion devices. © 2012 American Chemical Society.


Li M.,Beijing University of Chemical Technology | Yin Y.-X.,Beijing University of Chemical Technology | Yin Y.-X.,CAS Beijing National Laboratory for Molecular | Li C.,Beijing University of Chemical Technology | And 4 more authors.
Chemical Communications | Year: 2012

CoO/CoFe2O4 nanocomposites, derived from scalably prepared CoFe-layered double hydroxide (CoFe-LDH) single-resource precursors, exhibit tunable cycle performances and rate capabilities, which are supported by the homogenous dispersion of bi-component active CoO and CoFe2O 4 phases.


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.


Lu Z.,Beijing University of Chemical Technology | Chang Z.,Beijing University of Chemical Technology | Zhu W.,Beijing University of Chemical Technology | Sun X.,Beijing University of Chemical Technology
Chemical Communications | Year: 2011

β-Ni(OH)2 was constructed into a three-dimensional mesoporous film on Ni foam with ultra-thin (∼6 nm) primary nanowalls showing ultrahigh specific capacitance (2675 F g-1) and excellent cycling performance (>96% for 500 cycles). The capacitance was higher than theoretical value possibly due to the combination of Faradic and electrical double-layer capacitances. © The Royal Society of Chemistry 2011.


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.


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.


Li K.,Beijing University of Chemical Technology | Fan G.,Beijing University of Chemical Technology | Yang L.,Beijing University of Chemical Technology | Li F.,Beijing University of Chemical Technology
Sensors and Actuators, B: Chemical | Year: 2014

In this work, a series of novel non-enzymatic glucose sensors were developed based on three types of tailored flower-like (chrysanthemum-like, candock-like, and dandelion-like) CuO micro/nanostructures grown on Cu foils. The as-fabricated CuO hierarchical films were directly integrated to be structured electrodes. The results showed that the structured CuO film electrodes exhibited enhanced electrochemical properties and electrocatalytic performance toward the oxidation of glucose with remarkably high sensitivities (3252 μA mM-1 cm-2 for chrysanthemum-like CuO, 4078 μA mM-1 cm-2 for candock-like one, and 5368 μA mM-1 cm-2 for dandelion-like one), which are much better than some reports in the literature. The as-fabricated non-enzymatic glucose sensors presented good anti-interference property in the presence of dopamine, ascorbic acid, uric acid, and other carbohydrate compounds and long-term stability. In addition, the CuO film electrode was also used to analyze glucose concentration in human serum samples. The excellent electrocatalytic performance toward glucose oxidation can be attributed to the combination of more electron transfer passages, lower charge transfer resistance, and more accessibility to reaction sites originating from high-density nanoscale "petal-like" building units with large surface-to-volume ratio and high surface area, as well as strong immobilization of hierarchical CuO micro/nanostructures on the substrate. © 2014 Elsevier B.V.


Zhang L.,Beijing University of Chemical Technology | Chen Y.,Beijing University of Chemical Technology | Zhang Z.,Beijing University of Chemical Technology | Lu C.,Beijing University of Chemical Technology
Sensors and Actuators, B: Chemical | Year: 2014

In this study, Co(II)-EDTA-intercalated Mg-Al layered double hydroxides (LDHs) synthesized by anion exchange method were immobilized in a clear quartz tube to fabricate a novel chemiluminescence (CL) flow-through sensor. Interestingly, this simple micro-fabricated flow cell could greatly enhance the CL signals from the luminol-H2O2 reaction. The detection limit for H2O2 (S/N = 3) was 0.14 μM. Trace metal ions in the matrix had no effect because they were easy to complex with EDTA. The proposed sensor has been successfully applied to determine H2O 2 in snow water samples with simple procedures, shorter response time and higher selectivity. The results demonstrated that this proposed method had great potential in chemical/biological sensing for H2O2 as well as for other oxidase-based reactions producing H2O2. To the best of our knowledge, this is the first report on the use of metal complex-intercalated LDHs for CL signal amplification. © 2013 Elsevier B.V.


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.


Yang K.,Soochow University of China | Zhang S.,Soochow University of China | Zhang G.,Beijing University of Chemical Technology | Sun X.,Beijing University of Chemical Technology | And 2 more authors.
Nano Letters | Year: 2010

Although biomedical applications of carbon nanotubes have been intensively studied in recent years, its sister, graphene, has been rarely explored in biomedicine. In this work, for the first time we study the in vivo behaviors of nanographene sheets (NGS) with polyethylene glycol (PEG) coating by a fluorescent labeling method. In vivo fluorescence imaging reveals surprisingly high tumor uptake of NGS in several xenograft tumor mouse models. Distinctive from PEGylated carbon nanotubes, PEGylated NGS shows several interesting in vivo behaviors including highly efficient tumor passive targeting and relatively low retention in reticuloendothelial systems. We then utilize the strong optical absorbance of NGS in the near-infrared (NIR) region for in vivo photothermal therapy, achieving ultraefficient tumor ablation after intravenous administration of NGS and low-power NIR laser irradiation on the tumor. Furthermore, no obvious side effect of PEGylated NGS is noted for the injected mice by histology, blood chemistry, and complete blood panel analysis in our pilot toxicity study. Although a lot more efforts are required to further understand the in vivo behaviors and the long-term toxicology of this new type of nanomaterials, our work is the first success of using carbon nanomaterials for efficient in vivo photothermal therapy by intravenous administration and suggests the great promise of graphene in biomedical applications, such as cancer treatment. © 2010 American Chemical Society.


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.


Bai Y.,Beijing University of Chemical Technology | Dou Y.,Beijing University of Chemical Technology | Xie L.-H.,Beijing University of Chemical Technology | Rutledge W.,Texas A&M University | And 2 more authors.
Chemical Society Reviews | Year: 2016

Among the large family of metal-organic frameworks (MOFs), Zr-based MOFs, which exhibit rich structure types, outstanding stability, intriguing properties and functions, are foreseen as one of the most promising MOF materials for practical applications. Although this specific type of MOF is still in its early stage of development, significant progress has been made in recent years. Herein, advances in Zr-MOFs since 2008 are summarized and reviewed from three aspects: design and synthesis, structure, and applications. Four synthesis strategies implemented in building and/or modifying Zr-MOFs as well as their scale-up preparation under green and industrially feasible conditions are illustrated first. Zr-MOFs with various structural types are then classified and discussed in terms of different Zr-based secondary building units and organic ligands. Finally, applications of Zr-MOFs in catalysis, molecule adsorption and separation, drug delivery, and fluorescence sensing, and as porous carriers are highlighted. Such a review based on a specific type of MOF is expected to provide guidance for the in-depth investigation of MOFs towards practical applications. © The Royal Society of Chemistry 2016.


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.


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.


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.


Bai D.,Beijing University of Chemical Technology | Chen G.,China University of Petroleum - Beijing | Zhang X.,Beijing University of Chemical Technology | Wang W.,Beijing University of Chemical Technology
Langmuir | Year: 2012

Using molecular dynamics simulations on the microsecond time scale, we investigate the nucleation and growth mechanisms of CO 2 hydrates in a water/CO 2/silica three-phase system. Our simulation results indicate that the CO 2 hydrate nucleates near the three-phase contact line rather than at the two-phase interfaces and then grows along the contact line to form an amorphous crystal. In the nucleation stage, the hydroxylated silica surface can be understand as a stabilizer to prolong the lifetime of adsorbed hydrate cages that interact with the silica surface by hydrogen bonding, and the adsorbed cages behave as the nucleation sites for the formation of an amorphous CO 2 hydrate. After nucleation, the nucleus grows along the three-phase contact line and prefers to develop toward the CO 2 phase as a result of the hydrophilic nature of the modified solid surface and the easy availability of CO 2 molecules. During the growth process, the population of sI cages in the formed amorphous crystal is found to increase much faster than that of sII cages, being in agreement with the fact that only the sI hydrate can be formed in nature for CO 2 molecules. © 2012 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.


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.


Yang X.,Beijing University of Chemical Technology | Liu L.,Beijing University of Chemical Technology | Yang W.,Beijing University of Chemical Technology
Polymer | Year: 2012

By exploringly introducing a bicationic viologen, N-hexyl-N'-(4- vinylbenzyl)-4,4′-bipyridinium bromide chloride (HVV) to dispersion polymerization of styrene (St) in a mixture of methanol and water, we achieved the following results: (1) monodisperse, core-shell microspheres with antibacterial surface were prepared by a simple one-step procedure, (2) diameter, core radii and shell thickness of resultant particles could be controlled by concentrations of HVV, monomer and initiator, and composition of media, (3) HVV could act not only as a monomer as that in previous modifications, but also as an efficient, novel stabilizer, and its copolymerization with St at interfacial layer and coagglutination of (co-)oligomers on core surface due to its moderate reactivity and hydrophilicity were conceived to be main reasons for formation of core-shell structures. Effects of HVV on polymerization behavior of St, evolution of core-shell structure, and morphology, size of particles were investigated. Moreover, antibacterial activity of resulted microspheres against Staphylococcus aureus was assayed. © 2012 Elsevier Ltd. All rights reserved.


Zhu X.,Beijing University of Chemical Technology | Wang B.,Beijing University of Chemical Technology | Shi F.,Beijing University of Chemical Technology | Nie J.,Beijing University of Chemical Technology
Langmuir | Year: 2012

We develop a facile method for preparing copper nanoparticles and patterned surfaces with copper stripes by ultraviolet (UV) irradiation of a mixture solution containing a photoinitiator and a copper-amine coordination compound. The copper-amine compound is formed by adding diethanol amine to an ethanol solution of copper chloride. Under UV irradiation, free radicals are generated by photoinitiator decomposition. Meanwhile, the copper-amine coordination compound is rapidly reduced to copper particles because the formation of the copper-amine coordination compound prevents the production of insoluble cuprous chloride. Poly(vinylpyrrolidone) is used as a capping agent to prevent the aggregation of the as-prepared copper nanoparticles. The capping agent increases the dispersion of copper nanoparticles in the ethanol solution and affects their size and morphology. Increasing the concentration of the copper-amine coordination compound to 0.1 M directly forms a patterned surface with copper stripes on the transparent substrate. This patterned surface is formed through the combination of the heterogeneous nucleation of copper nanoparticles and photolithography. We also investigate the mechanism of photoreduction by UV-vis spectroscopy and gas chromatography-mass spectrometry. © 2012 American Chemical Society.


Hu Z.,Beijing University of Chemical Technology | Xu L.,Beijing University of Chemical Technology | Chen J.,Beijing University of Chemical Technology
Materials Letters | Year: 2013

A preparation of three-dimensionally ordered arrays of N-doped mesoporous TiO2 spheres by a dual-templating synthesis approach employing a combination of both polymer inverse opal templating (hard-templating) and surfactant templating (soft-templating) techniques was developed in this work. The N-doped mesoporous TiO2 spheres were composed of nanocrystalline anatase titania and exhibited well-defined mesoporous structure. The ordered arrays of N-doped mesoporous TiO2 spheres showed enhanced visible light photocatalytic activity, which could be attributed to the N doping effect, abundant ordered mesopores and unique opal structure. Such obtained TiO 2 sphere arrays may be promising for practical applications in the fields of environmental purification, water photoelectrolysis and dye-sensitized solar cells. © 2013 Elsevier B.V. All rights reserved.


Guan Y.,Beijing University of Chemical Technology | Zhang L.-X.,Beijing University of Chemical Technology | Zhang L.-Q.,Beijing University of Chemical Technology | Lu Y.-L.,Beijing University of Chemical Technology
Polymer Degradation and Stability | Year: 2011

The ablative properties of hydrogenated nitrile butadiene rubber (HNBR) composites filled with fumed silica, organically modified montmorillonite (OMMT), or expanded graphite (EG) were examined. The HNBR/OMMT composite has the lowest linear ablation rate and the highest mass ablation rate and does not tend to be carbonized. On the other hand, the HNBR/EG composite has the highest linear ablation rate and the lowest mass ablation rate, and is prone to carbonization. The ablative properties of the HNBR/silica composite are between those of HNBR/OMMT and HNBR/EG. From the viewpoint of thermal shielding capability, the HNBR/OMMT has the best ablation resistance. Thermogravimetric analysis (TGA) on different HNBR composites indicated that the filler type has no significant effect on the thermal stability of the composites. To understand the ablation mechanisms, the char layers of different HNBR composites after ablation experiments were characterized by scanning electron microscopy (SEM), energy disperse X-ray spectroscopy (EDS), and wide-angle X-ray diffraction (WAXD). The results showed that the porosity in the char layers of the HNBR/OMMT composite was the highest and the corresponding structure was the loosest of the three composites. The montmorillonite (MMT) dispersed in HNBR experienced phase transition, melting and vaporization when exposed to the flame with the temperature over 2000 °C. Fumed silica only melted at such situation. On the other hand, the EG kept their original crystalline structures after the ablation test. Based on these results, the effect of the filler type on the ablation mechanisms of the HNBR composites was discussed. © 2011 Elsevier Ltd. All rights reserved.


Ma X.,Beijing University of Chemical Technology | Kuang Y.,Beijing University of Chemical Technology | Bai L.,Beijing University of Chemical Technology | Chang Z.,Beijing University of Chemical Technology | And 3 more authors.
ACS Nano | Year: 2011

Identifying the phase purity of CdS nanorods (NRs) is complicated by the serious overlap between the X-ray diffraction peaks of zinc blende and wurtzite phases as well as anisotropic growth, which might hide a mixed phase. Here we show that the density gradient ultracentrifugation rate separation method can be used to sort CdS NRs synthesized under nitrogen according to differences in particle size and morphology. Furthermore, it was found that the different sized NRs formed in a single batch synthesis had different phases: the thinner ones (<3.5 nm in diameter) were predominantly wurtzite phase, while the thicker ones (>5 nm in diameter) were mainly zinc blende phase. Dark-field transmission electron microscopy (TEM) and high-resolution TEM images indicated the presence of numerous stacking faults in the thick zinc blende rods, while the wurtzite thin rods were exclusively single crystals. As a result of the differences in phase and stacking faults, the NRs showed different photoluminescent properties. The development of an effective way of separating such NRs thus leads to further insight into the differences in phase, structure, and optical properties between individual colloidal particles synthesized in a single batch. A preliminary mathematical model of the separation process has been proposed. © 2011 American Chemical Society.


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.


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.


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.


Wang S.,Beijing University of Chemical Technology | Yong W.,Chinese Academy of Inspection and Quarantine | Liu J.,Beijing University of Chemical Technology | Zhang L.,Beijing University of Chemical Technology | And 2 more authors.
Biosensors and Bioelectronics | Year: 2014

Tetracycline (TC) is widely used for prevention and control of animal diseases for its broad spectrum antimicrobial activity and low cost, but its abuse can seriously affect human health and may result in trade loss. Thus there is an imperative need to develop high-performing analytical technique for TC detection. In this study, we developed a biosensor based on an indirect competitive enzyme-linked aptamer assay (ic-ELAA). A 76mer single-stranded DNA (ssDNA) aptamer, selected by Systematic Evolution of Ligands by Exponential Enrichment (SELEX), was applied for the recognition and detection of TC in honey. The limit of detection was 9.6×10-3ng/mL with a linear working range from 0.01 to 100ng/mL toward TC in honey, and a mean recovery rate of 93.23% in TC-spiked honey was obtained. This aptasensor can be applied to detect TC residue in food with high sensitivity and simplicity, and it is prospective to develop useful ELAA Kits for TC determination in food. © 2014 Elsevier B.V.


Liu N.,Beijing University of Chemical Technology | Zhang R.,Beijing University of Chemical Technology | Chen B.,Beijing University of Chemical Technology | Li Y.,Beijing University of Chemical Technology
Journal of Catalysis | Year: 2012

Catalytic activities of M (Fe, Cu, Co)-beta (BEA) zeolites for N 2O direct decomposition were systematically investigated by employing both experimental and theoretical [density functional theory (DFT)] approaches. The activities of M-BEA determined by intrinsic kinetic evaluations are in good agreement with the DFT calculations and the microkinetic analyses, revealing that the distinguishing activities of M-BEA were mainly attributed to their distinct energy barriers for the O 2 desorption (Part 3). During the DFT calculations, a unique intermediate (IM) was generated only over Co-BEA, which was verified by the activity evaluation and N 2O-TPD experiments, showing that the formation of IM reduced N 2O decomposition rate of Co-BEA. The negative effect of the IM was thereafter investigated by the microkinetic analyses through which it was known that the second forward reaction rate constant of Co-BEA was lower than its reverse reaction rate constant, resulting in a final decline of the N 2O decomposition rate. © 2012 Elsevier Inc. All rights reserved.


Lv X.,Beijing University of Chemical Technology | Chen J.-F.,Beijing University of Chemical Technology | Tan Y.,Shanxi Institute of Coal CAS Chemistry | Zhang Y.,Beijing University of Chemical Technology
Catalysis Communications | Year: 2012

The modification of silica support using ethylene glycol (EG) significantly modified surface properties of silica support, resulting in the decreased decomposition temperature of impregnated nickel nitrate and the enhanced metal-support interaction. The catalyst prepared by modified silica support realized excellent stability and two times higher catalytic activity than the catalyst obtained from non modified silica support in dry reforming of CH 4, since its highly dispersed supported nickel and strong nickel-silica interaction. The properties of silica supports, catalyst precursors and catalysts were characterized by TG-DSC, FT-IR, XRD, H 2 chemisorption, O 2 titration, TPR and TEM. © 2012 Elsevier B.V. All rights reserved.


Chen X.,Beijing University of Chemical Technology | Song D.,Beijing University of Chemical Technology | Asumana C.,Beijing University of Chemical Technology | Yu G.,Beijing University of Chemical Technology
Journal of Molecular Catalysis A: Chemical | Year: 2012

A series of Lewis acidic ionic liquids (ILs) based on 1-n-butyl-3- methylimidazolium metal chloride, i.e., [C 4mim]Cl/MCl 2 (M = Zn, Fe, Cu, Mg, Sn, Co), are synthesized and used to investigate the oxidative removal of sulfur compounds (S-compounds) from diesel fuels, with ILs serving as both extractant and catalyst and 30 wt% H 2O 2 solution as oxidant. It is observed that metal chloride species affect S-removal, as S-removal efficiency follows the order: [C 4mim]Cl/ZnCl 2 > [C 4mim]Cl/FeCl 2 > [C 4mim]Cl/CoCl 2 > [C 4mim]Cl/MgCl 2 > [C 4mim]Cl/CuCl 2 > [C 4mim]Cl/SnCl 2. The highly efficient [C 4mim]Cl/ZnCl 2 is selected to investigate the effects of ZnCl 2 content on desulfurization. It is interesting to find out that ZnCl 2 content has a significant influence on desulfurization; specifically, 99.9% S-removal is observed for [C 4mim]Cl/3ZnCl 2 after 3 h at 45 °C, O/S molar ratio of 8, IL/oil mass ratio of 1/2. [C 4mim]Cl/3ZnCl 2 then undergoes series of parallel experiments to systematically investigate the influence of factors such as temperature, molar ratio of O/S, mass ratio of IL/oil, and ILs recycling. The incorporation of real diesel fuel into this study demonstrates the efficacy of this IL in desulfurization. This work shows that oxidative desulfurization using Lewis acidic ILs may be a new option for producing cleaner diesel fuels. © 2012 Elsevier B.V. All rights reserved.


Wang S.,Beijing University of Chemical Technology | Qin L.,Beijing University of Chemical Technology | Zhou Z.,Beijing University of Chemical Technology | Wang J.,Beijing University of Chemical Technology
Journal of Chemical and Engineering Data | Year: 2012

The solubility of betaine in water, methanol, ethanol, n-propanol, 2-propanol, and n-butanol and also in methanol + ethanol and ethanol + water binary mixtures has been experimentally measured using a laser monitoring observation technique. The modified Apelblat equation was used to correlate the solubility of betaine in the studied pure solvents. The solubility of betaine in the binary solvent mixtures was correlated by a hybrid model based on the Jouyban-Acree model and modified Apelblat equation. The associated P-values of terms for model were used to simplify the hybrid model, which reduced the number of the model parameters without affecting the values of mean percentage deviation (MPD) and R 2. With these models the maximum MPD for studied solvents is 1.94. Thermodynamic functions including δHsoln 0, δGsoln 0, and δSsoln 0 of solution of betaine were obtained from the modified van't Hoff equation. A comparison of the relative contributions by enthalpy (ζ H) and entropy (ζ TS) was made (with ζ H > 0.6 and even up to 0.99 in methanol), which indicated that the main contributor to the positive standard molar Gibbs energy of solution of betaine was enthalpy in both pure solvents and mixtures. © 2012 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.


Wang Z.,Beijing University of Chemical Technology | Wu Z.,Beijing University of Chemical Technology | Tan T.,Beijing University of Chemical Technology
Bioresource Technology | Year: 2013

To identify the adsorption characteristics of 1,3-propanediol on beta zeolite, the effects of temperature, zeolite dose, and 1,3-propanediol concentration were studied through batch experiments. The results showed that the pseudo-second order model expressed the kinetic data better. The experimental and theoretical adsorption capacities were 116.2 and 119.0mg/g at 293K, respectively. The adsorption equilibrium data were observed to satisfy the Freundlich isotherm model. Based on the Boyd plot, intraparticle diffusion primarily governed the uptake process. Moreover, thermodynamic parameters, such as changes in standard free energy (δG0), standard enthalpy (δH0), and standard entropy, were estimated. The negative values of δG0 and δH0 (-9.4kJ/mol) indicated that the adsorption process was spontaneous, exothermic, and feasible. Finally, the activation energy derived from the Arrhenius equation suggested that the interaction mainly constitute physical adsorption. © 2013 Elsevier Ltd.


Zhang C.,Beijing University of Chemical Technology | Su H.,Beijing University of Chemical Technology | Tan T.,Beijing University of Chemical Technology
Bioresource Technology | Year: 2013

To avoid the inhibition from both of waste oil and high concentrations of cationic elements, anaerobic digestion of food waste in a dual solid-liquid (ADSL) system was examined in this present paper. Results from batch test indicated that a higher methane yield could be obtained in the ADSL system. The methane yield of food solid waste (FSW), food liquid waste (FLW) and raw food waste (RFW) were 643, 659 and 581mL/g-VS, respectively. In semi-continuous anaerobic digestion, the optimum organic loading rates (OLR) for FSW, FLW and RFW were 9, 4 and 7g-VS/L/d, respectively. The total methane production of RFW and ADSL systems, based on 1kg-VSRFW, were 405 and 460L, respectively, indicating that the methane production increased by 13.6% in the ADSL system. The optimum C/N ratio, redistribution of metal element and lower content of waste oil in FSW explain the higher methane production. © 2013 Elsevier Ltd.


Qin F.,Beijing University of Chemical Technology | Li S.,Beijing University of Chemical Technology | Qin P.,Beijing University of Chemical Technology | Karim M.N.,Texas A&M University | Tan T.,Beijing University of Chemical Technology
Green Chemistry | Year: 2014

Producing furfural based on the hydrolysis of biomass rich in hemicellulose is a sustainable technique; however, separating furfural from the hydrolysate by the conventional methods like distillation is energy-intensive and environmentally unfriendly. Pervaporation, an energy-efficient 'clean technology', is thus suggested for the separation of furfural. A polydimethylsiloxane (PDMS) membrane was prepared using water as a solvent in the presence of a surfactant (sodium dodecyl sulfate, SDS). Effects of feed concentration and temperature, thickness of the PDMS layer and operation time on pervaporation performance were investigated, and the apparent activation energies of furfural and water permeating through the membrane were calculated according to the Arrhenius-type equation. Permeate concentration and furfural flux reached 62.4 wt% and 3222.6 g m-2 h-1 when separating 6.5 wt% furfural aqueous solution at 95 °C. Compared to distillation, pervaporation by the PDMS membrane provided higher selectivity while consuming 70% less evaporation energy. Additionally, the PDMS membrane displayed more promising potential in industrial application than those reported in the literature due to its higher furfural flux. © 2014 The Royal Society of Chemistry.


Xiao G.,Beijing University of Chemical Technology | Huang A.,Beijing University of Chemical Technology | Su H.,Beijing University of Chemical Technology | Tan T.,Beijing University of Chemical Technology
Building and Environment | Year: 2013

Through a novel green and low-cost emulsion blend method, acrylic-silicon/nano-TiO2 films (ASTF) were prepared showing a broad absorption band in the visible light region and could be used for the photodegradation of indoor gaseous pollutants under visible light irradiation. Compared with acrylic-silicon films, the photodegradation rate of ASTF with TiO2 content of 1% (w/v) increased by almost twice for both gaseous formaldehyde (from 28% to 76.7% at the initial concentration of 0.8mg/m3) and NO2 (from 20% to 68% at the initial concentration of 3.7mg/m3) under visible light irradiation for 24h and 50h, respectively. The binary gas degradation confirmed the higher affinity of NO2 for ASTF. In addition, ASTF with FeIII ion doping (<100mg/L) showed even higher photocatalytic activity with maximum degradation rate of 83.4% for formaldehyde under visible light irradiation for 24h. ASTF, as a kind of eco-friendly coating material, could be used easily in domestic buildings for our daily life. © 2013 Elsevier Ltd.


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.


Zheng X.,Beijing University of Chemical Technology | Li W.,Beijing University of Chemical Technology | Guan C.,Beijing University of Chemical Technology
Physica A: Statistical Mechanics and its Applications | Year: 2010

The level of service in public walking spaces is mainly determined by the differences in pedestrian traffic demand and infrastructure supply. A problem worth studying is the evacuation process in a closed square with partition wall. In this paper, a cellular automaton model is presented to simulate the evacuation process in the square. This model defines a floor field and considers the selection of an exit and effect of social forces. Some simulation results show the model's correct description of the pedestrian dynamics. Both the total evacuation time and the degree of pedestrians jamming in a certain area are regarded as the indicators of the evacuation progress and the measure of evacuation efficiency. Concerning the two indicators, some viewpoints on the evacuation design of the partition wall are put forward: (1) changing the length of the partition wall could reduce the evacuation time, however, it could also bring the serious pedestrians jamming in a certain area, which may cause potential injury; (2) with the prior consideration for evacuation time, the length of the partition wall should be better chosen to make the pedestrians jamming less severe. © 2010 Elsevier B.V. All rights reserved.


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.


Li Y.,Beijing University of Chemical Technology | Zhang X.,Beijing University of Chemical Technology | Cao D.,Beijing University of Chemical Technology
Journal of Physical Chemistry B | Year: 2013

Nanoparticle-assisted drug delivery has been emerging as an active research area. Achieving high drug loading is only one facet of drug delivery issues; it is also important to investigate the effect of surface charge distribution on self-assembly of nanoparticles on cellular membranes. By considering the electrostatic distribution of patterned nanoparticles, we used dissipative particle dynamics simulations to investigate the self-assembly of pattern charged nanoparticles with five different surface charged patterns. It is found that both surface charged pattern and nanoparticle size significantly affect the self-assembly of nanoparticles on cellular membranes. Results indicate that 1/2 pattern charged small nanoparticles can self-assemble into dendritic structures, while those with a 1/4 pattern self-assemble into clusters. As the nanoparticle size increases, 1/2 pattern charged medium nanoparticles can self-assemble into linear structures, while those with a 1/4 pattern self-assemble into clusters. For very large nanoparticles, both 1/2 pattern and 1/4 pattern charged nanoparticles self-assemble into flaky structures with different connections. By considering the effects of surface charged pattern and nanoparticle size on self-assembly, we found that nanoparticle self-assembly requires a minimum effective charged area. When the local charged area of nanoparticles is less than the threshold, surface charge cannot induce nanoparticle self-assembly; that is, the surface charged pattern of a nanoparticle would determine effectively the self-assembly structure. It is expected that this work will provide guidance for nanoparticle-assisted drug delivery. © 2013 American Chemical Society.


Ren S.,Beijing University of Chemical Technology | Hou Y.,Taiyuan Normal University | Tian S.,Beijing University of Chemical Technology | Chen X.,Beijing University of Chemical Technology | Wu W.,Beijing University of Chemical Technology
Journal of Physical Chemistry B | Year: 2013

As a kind of novel and efficient material, ionic liquids (ILs) are used for capture of acidic gases including SO2 and CO2 from flue gas. Due to very low content of acidic gases in flue gas, it is important to find functional ILs to absorb the acidic gases. However, up to now, there is no criterion to distinguish if the ILs are functional or not before use, which greatly influences the design of functional ILs. In this work, a series of ILs were synthesized and used to determine functional or normal ILs for the capture of acidic gases. It has been found that the pKa of organic acids forming the anion of ILs can be used to differentiate functional ILs from normal ILs for the capture of acidic gases from flue gas. If the pKa of an organic acid is larger than that of sulfurous acid (or carbonic acid), the ILs formed by the organic acid can be called functional ILs for SO2 (or CO2) capture, and it can have a high absorption capacity of SO 2 (or CO2) with low SO2 (or CO2) concentrations. If not, the IL is just a normal IL. The pKa of organic acids can also be used to explain the absorption mechanism and guide the synthesis of functional ILs. © 2013 American Chemical Society.


Liu Z.,Beijing University of Chemical Technology | Zhang G.,Beijing University of Chemical Technology | Lu Z.,Beijing University of Chemical Technology | Jin X.,Beijing University of Chemical Technology | And 2 more authors.
Nano Research | Year: 2013

N-doped porous carbon materials have been prepared by a simple one-step pyrolysis of ethylenediaminetetraacetic acid (EDTA) and melamine in the presence of KOH and Co(NO3)2·6H2O. The combination of the high specific area (1485 m2·g-1), high nitrogen content (10. 8%) and suitable graphitic degree results in catalysts exhibiting high activity (with onset and half-wave potentials of 0. 88 and 0. 79 V vs the reversible hydrogen electrode (RHE), respectively) and four-electron selectivity for the oxygen reduction reaction (ORR) in alkaline medium-comparable to a commercial Pt/C catalyst, but far exceeding Pt/C in stability and durability. Owing to their superb ORR performance, low cost and facile preparation, the catalysts have great potential applications in fuel cells, metal-air batteries, and ORR-related electrochemical industries. © 2013 Tsinghua University Press and Springer-Verlag Berlin Heidelberg.


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.


An M.,Beijing University of Chemical Technology | Cui J.,Beijing University of Chemical Technology | He Q.,Beijing University of Chemical Technology | Wang L.,Beijing University of Chemical Technology
Journal of Materials Chemistry B | Year: 2013

Dual-modal luminescence nanocomposites (NCs) were successfully prepared via a facile and versatile strategy by embedding the hydrophobic down-conversion (DC) fluorescence ZnS:Mn2+ quantum dots (QDs) and up-conversion (UC) luminescence NaYF4:Er3+/Yb3+ nanoparticles (NPs) into hydrophilic polymer matrixes through in situ cross-linking polymerization. Due to the enriched carboxylic groups in the polymer matrixes, the as-prepared NCs are highly water-stable and bioconjugatable with chemical and biological moieties. The results of cytotoxicity assay and dual-modal luminescence cell imaging application of DC-UC NCs indicate that the as-prepared NCs are biocompatible and applicable in biomedical fields. The current work paves the way to the fabrication of multifunctional NCs including down- and up-conversion dual-modal luminescence, luminescence-magnetism, magnetic targeted drug vehicles and magnetic recyclable catalyst NCs, and will attract wide attention from the fields of chemistry, materials, catalysis, nanotechnology, nanobiotechnology and nanomedicine. © 2013 The Royal Society of Chemistry.


Li H.,Beijing University of Chemical Technology | Wang H.,Beijing University of Chemical Technology | Wang L.,Beijing University of Chemical Technology
Journal of Materials Chemistry C | Year: 2013

Via a facile one-pot strategy, polyaspartate (PASP) coated LaF 3:Ce3+/Tb3+ luminescent nanocrystals have been successfully prepared. Based on the luminescence quenching of the PASP modified LaF3:Ce3+/Tb3+ nanocrystals by Fe3+, a simple and novel luminescent chemosensor for Fe3+ has been developed. High selectivity and sensitivity is observed over other cations, which is mainly attributed to the formation of a PASP-Fe3+ complex on the NP surface. The luminescence of the suspensions was gradually quenched with the addition of Fe3+ ion, with a linear range of 5 × 10 -7 to 1 × 10-4 mol L-1. This journal is © 2013 The Royal Society of Chemistry.


Wang C.,Beijing University of Chemical Technology | Kuang Y.,Beijing University of Chemical Technology | Luo L.,Beijing University of Chemical Technology | Sun X.,Beijing University of Chemical Technology
Journal of Materials Chemistry C | Year: 2013

Well-dispersed Ag@rubrene core-shell nanostructures have been fabricated by an in situ chemical reaction route. The reduction in cationic precursors of rubrene+ by Ag atoms generated neutral rubrene molecules which had a local high concentration to realize the site-specific nucleation, and followed by the in situ growth of rubrene shell. The rubrene shell thickness can be highly tuned from 2 to 16 nm by adjusting the amount of rubrene+ radical cations. Such core-shell nanostructures have significant integrated multiple enhanced optical signal outputs: thickness-dependent fluorescence and SERS signals. The results show that the shell thickness and the match of local surface plasmon resonance and the excitation band of rubrene played dominant roles in fluorescence enhancement. Additionally, these nanostructures integrating the Raman-active substrate with Ag colloidal nanoparticles could obtain an enhancement factor (EF) of ∼103. © The Royal Society of Chemistry 2013.


Ma H.,Beijing University of Chemical Technology | Gao R.,Beijing University of Chemical Technology | Yan D.,Beijing University of Chemical Technology | Zhao J.,Beijing University of Chemical Technology | Wei M.,Beijing University of Chemical Technology
Journal of Materials Chemistry C | Year: 2013

The luminescent film materials sensitive to external stimuli are important to develop new types of optical sensors and switches. Herein we report organic-inorganic hybrid ultrathin films (UTFs) with reversible luminescence response to nitroaromatic explosive compounds by the use of layer-by-layer assembly of optical brightener BBU and Mg-Al-layered double hydroxide (LDH) nanosheets. UV-Visible absorption and fluorescence spectroscopy showed an orderly growth of the BBU/LDH films upon increasing the number of deposition cycle. XRD, AFM and SEM measurements indicated that the films feature periodic layered structure with a period of ca. 2 nm as well as uniform surface morphology. The BBU/LDH UTFs exhibit well-defined one/two-photon polarized photoemission with the anisotropy as high as 0.38. Moreover, the UTFs show a fast, selective and reversible luminescence response to different nitroaromatic explosives with the most significant luminescent red-shift occurring for picric acid; in addition, by combining suitable luminescent building blocks, the films can also be extended to other dual-color luminescence systems, which exhibit changes in both luminescence intensity and ratiometric fluorescence upon interaction with explosives, enlightening that these films can serve as new types of selective solid luminescent sensors towards nitroaromatic compounds. © The Royal Society of Chemistry 2013.


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 D.,Beijing University of Chemical Technology | Chen H.,Beijing University of Chemical Technology | Deng J.,Beijing University of Chemical Technology | Yang W.,Beijing University of Chemical Technology
Journal of Materials Chemistry C | Year: 2013

This paper reports the preparation of unique composite gels demonstrating both optical activity and magnetic responsivity (the gels are denoted as OAMGs). The composite gels consist of magnetic Fe3O4 nanoparticles (Fe3O4 NPs) and helical substituted polyacetylene with a predominantly one-handed screw sense. The former provides magnetic responsivity, while the latter provides optical activity. The OAMGs were synthesized from alkyne-modified Fe3O4 NPs and substituted acetylene monomer (M1) via coordination polymerization by using (nbd)Rh+B-(C6H5)4 as a catalyst and dipropargyl adipate (M3) as a crosslinker. The substituted polyacetylene chains in the gels adopted helical structures of preferential helicity, according to circular dichroism and UV-vis absorption spectroscopy. The gel (Gel-3) showed a high saturation magnetization of 21.2 emu g -1 and rapid magnetic responsivity. The gel also demonstrated a preferential adsorption toward the (R)-(+)-1-phenylethylamine of the two enantiomers. After use, the gels can be easily recycled simply with the assistance of an external magnetic field, indicating the potential applications of the novel gels in chiral resolution, enantioselective-controlled release, chiral reactors for asymmetric catalysis, etc. © 2013 The Royal Society of Chemistry.


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.


Xu X.,Beijing University of Chemical Technology | Cao D.,Beijing University of Chemical Technology
Journal of Chemical Physics | Year: 2010

We developed a new density-functional theory (DFT) for inhomogeneous hyperbranched polymers that is able to describe the polydisperse degree of branching quantitatively. The topological contributions of the polymer chains to the Helmholtz free energy take into account the effect of triple connections that are absent in previous DFT investigations. One key advantage of the new theory is that the computational cost shows only a linear relationship with the molecular weight (rather than an exponential relationship). The practical utility of the new DFT is illustrated by investigating colloidal stability in the presence of monodisperse and polydisperse hyperbranched polymers. © 2010 American Institute of Physics.


Yue T.,Beijing University of Chemical Technology | Li S.,Beijing University of Chemical Technology | Zhang X.,Beijing University of Chemical Technology | Wang W.,Beijing University of Chemical Technology
Soft Matter | Year: 2010

The mechanism of biomembrane curvature generation has been studied for decades because of its role in many cellular functions. In this article, N-varied dissipative particle dynamics was used to investigate the relationship between membrane curvature generation and self-assembly of anchored proteins, and a protein aggregation mechanism of curvature generation was proposed. According to the mechanism, the curvature production is enhanced by the self-assembly of proteins, and the enhancement depends on the protein hydrophobic length. Contrary to the theoretic predictions that shallow insertion depth of proteins is more effective in producing positive membrane curvature, our simulations show the opposite trend if the self-assembly of proteins is taken into account. Furthermore, for the membrane proteins with deep insertion, simulations indicate that the self-assembly of proteins may induce membrane vesiculation at negative membrane tensions. In addition, the protein aggregates can sense the membrane curvature, although the way they respond to the local curvature again depends on the protein hydrophobic length. Especially, the self-assembly of shallow inserting proteins is significantly affected by the local membrane curvature. © 2010 The Royal Society of Chemistry.


Wang W.,Beijing University of Chemical Technology | Chen R.,Beijing University of Chemical Technology | Qi X.,Beijing University of Chemical Technology
Journal of Alloys and Compounds | Year: 2012

In this paper, based on the molecular field theory, a new and improved three-sublattice model on studying the magnetic properties of ferrimagnetic rare-earth iron garnet in high magnetic fields is introduced. Here, the effective exchange field is described as Hi = λM = λχHe, where λ is the coefficient associated with the molecular field, χ is the effective magnetic susceptibility, and H e is external magnetic fields. As is known, the magnetic sublattices in rare-earth iron garnets can be classified three kinds labeled as a, c and d, in our calculations, whose magnetizations are defined as Ma, M c and Md, respectively. Then, using this model, the temperature and field dependences of the total magnetization in Dy 3Fe5O12 (DyIG) are discussed. Meanwhile, the magnetizations of the three kinds of magnetic sublattices are analyzed. Furthermore, our theory suggests that the coefficients αi associated with λ and χ in DyIG show obvious anisotropic, temperature-dependence and field-dependence characteristics. And, the theoretical calculations exactly fit the experimental data. © 2011 Elsevier B.V.


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.


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.


Wei H.,Beijing University of Chemical Technology | Yang W.,Beijing University of Chemical Technology | Xi Q.,Beijing University of Chemical Technology | Chen X.,Beijing University of Chemical Technology
Materials Letters | Year: 2012

Core-shell structure Fe 3O 4@graphene oxide (GO) submicron particles have been prepared via a simple electrostatic self-assembly process. The Fe 3O 4@GO particles had good dispersibility in water, high saturation magnetization and sensitive magnetic response. Bovine serum albumin (BSA) was chosen as model protein to study the efficacy of the Fe 3O 4@GO particles for protein adsorption. By virtue of the combined benefits of GO and Fe 3O 4, the Fe 3O 4@GO particles exhibited large adsorption capacity (181.8 mg/g) and fast adsorption kinetics for BSA. The performance of GO as a shell material for core-shell magnetic composites was found to be superior to that of conventional shell materials such as polymers and silicon, thus demonstrating the great potential of the Fe 3O 4@GO particles for application in magnetic bioseparation. © 2012 Published by Elsevier B.V. All rights reserved.


Shen D.,Beijing University of Chemical Technology | Wang Y.,Beijing University of Chemical Technology
Journal of Process Control | Year: 2014

Iterative learning control (ILC) is suitable for systems that are able to repeatedly complete several tasks over a fixed time interval. Since it was first proposed, ILC has been further developed through extensive efforts. However, there are few related results on systems with stochastic signals, where by stochastic signal we mean one that is described by a random variable. Stochastic iterative learning control (SILC) is defined as ILC for systems that contain stochastic signals including system noises, measurement noises, random packet losses, etc. This manuscript surveys the current state of the art in SILC from the perspective of key techniques, which are divided into three parts: SILC for linear stochastic systems, SILC for nonlinear stochastic systems, and systems with other stochastic signals. In addition, three promising directions are also provided, namely stochastic ILC for point-to-point control, stochastic ILC for iteration-varying reference tracking, and decentralized/distributed coordinated stochastic ILC, respectively. © 2014 Elsevier Ltd. All rights reserved.


Fan J.,Beijing University of Chemical Technology | Qin S.J.,Beijing University of Chemical Technology | Qin S.J.,University of Southern California | Wang Y.,Beijing University of Chemical Technology
Control Engineering Practice | Year: 2014

In this paper, a novel approach for processes monitoring, termed as filtering kernel independent component analysis-principal component analysis (FKICA-PCA), is developed. In FKICA-PCA, first, a method to calculate the variance of independent component is proposed, which is significant to make Gaussian features and non-Gaussian features comparable and to select dominant components legitimately; second, Genetic Algorithm is used to determine the kernel parameter through minimizing false alarm rate and maximizing detection rate; furthermore, exponentially weighted moving average (EWMA) scheme is used to filter the monitoring indices of KICA-PCA to improve monitoring performance. In addition, a novel contribution analysis scheme is developed for FKICA-PCA to diagnosis faults. The feasibility and effectiveness of the proposed method are validated on the Tennessee Eastman (TE) process. © 2013 Elsevier Ltd.


Xue Y.,Beijing University of Chemical Technology | Liu J.,Beijing University of Chemical Technology | Liang J.,Beijing University of Chemical Technology
Polymer Degradation and Stability | Year: 2013

The correlations and differences among the processes of critical reactions in polyacrylonitrile (PAN) copolymer [containing itaconic acid (IA)] [P(AN-IA)] and terpolymer [containing itaconic acid (IA) and methyl acrylate (MA)] [P(AN-IA-MA)] fibers during thermal-oxidative stabilization have been studied by the comparative method. Fourier transform infrared spectroscopy (FTIR) analyzed the chemical kinetics and structural evolution in two types of PAN precursor fibers; the results indicates that P(AN-IA) possesses lower reaction rates and higher activation energies for critical reactions compared with P(AN-IA-MA). Differential scanning calorimetry (DSC) analyses show that the thermal stability of P(AN-IA) is superior to that of P(AN-IA-MA). FTIR and DSC results demonstrate that the stabilization process of P(AN-IA) is easier to control. By solid state 13C nuclear magnetic resonance, the mechanism of critical reactions verifies that the isomerization among quasi-pyridone, hydroxyl pyridine and pyridone structures in oxidized PAN leads to the amount of resultant groups first increasing and then decreasing. © 2012 Elsevier Ltd. All rights reserved.


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.


Wang Z.,Beijing University of Chemical Technology | Liu J.,Beijing University of Chemical Technology | Wu S.,Beijing University of Chemical Technology | Wang W.,Beijing University of Chemical Technology | Zhang L.,Beijing University of Chemical Technology
Physical Chemistry Chemical Physics | Year: 2010

Nano-strengthening by employing nanoparticles is necessary for high-efficiency strengthening of elastomers, which has already been validated by numerous researches and industrial applications, but the underlying mechanism is still an open challenge. In this work, we mainly focus our attention on studying the variation of the tensile strength of nanofilled elastomers by gradually increasing the filler content, within a low loading range. Interestingly, the percolation phenomenon is observed in the relationship between the tensile strength and the filler loading, which shares some similarities with the percolation phenomenon occurring in rubber toughened plastics. That is, as the loading of nanofillers (carbon black, zinc oxide) increases, the tensile strength of rubber nanocomposites (SBR, EPDM) increases slowly at first, then increases abruptly and finally levels off. Meanwhile, the bigger the particle size, the higher the filler content at the percolation point, and the lower the corresponding tensile strength of rubber nanocomposites. The concept of a critical particle-particle distance (CPD) is proposed to explain the observed percolation phenomenon. It is suggested that rubber strengthening through nanoparticles is attributed to the formation of stretched straight polymer chains between neighbor particles, induced by the slippage of adsorbed polymer chains on the filler surface during tension. Meanwhile, the factors to govern this CPD and the critical minimum particle size (CMPS) figured out in this work are both discussed and analyzed in detail. Within the framework of this percolation phenomenon, this paper also clearly answers two important and intriguing issues: (1) why is it necessary and essential to strengthen elastomers through nanofillers; (2) why does it need enough loading of nanofillers to effectively strengthen elastomers. Moreover, on the basis of the percolation phenomenon, we give out some guidance for reinforcement design of rubbery materials: the interfacial interactions between rubber and fillers cannot be complete chemical bonding, and partial physical absorption of macromolecular chains on the filler surface is necessary, otherwise the formation of stretched straight chains would be seriously hindered. There should exist such an optimum crosslinking density for a certain filler reinforced rubber system, and as well an optimum filler loading for rubber strengthening. Additionally, the different percolation behaviors of Young's modulus, the tensile strength and the electrical conductivity are compared and analyzed in our work. Lastly, molecular simulation indicates that it is not possible to strengthen glassy or hard polymer matrices by incorporating spherical nanoparticles. In general, by providing substantial experimental data and detailed analyses, this work is believed to promote the fundamental understanding of rubber reinforcement, as well provide better guidance for the design of high-performance and multi-functional rubber nanocomposites. © 2010 the Owner Societies.


Huang L.,Beijing University of Chemical Technology | Yang X.,Beijing University of Chemical Technology | Cao D.,Beijing University of Chemical Technology
Journal of Physical Chemistry C | Year: 2015

Developing high-capacity gas storage materials is still an important issue, because it is closely related to carbon dioxide capture and hydrogen storage. This work proposes a "from inorganic to organic" strategy, that is, using tetrakis(4-bromophenyl)methane (TBM) to replace silicon in zeolites, to design porous aromatic frameworks (PAF-XXXs) with extremely high pore volume and accessible surface area, because the silicon atom in the silicon-based zeolites and the TBM ligand have the same coordination manner. Through the adoption of this strategy, 115 organic PAF-XXXs based on the inorganic zeolite structures were designed. These designed PAF-XXXs have the same topology with the corresponding matrix zeolites but possess significantly higher porosity than matrix zeolites. In general, the surface area, pore volume, and pore size of PAF-XXX are in the ranges of 4600-6000 m2/g, 2.0-7.9 g/cm3, and 10-55 Å, respectively. In particular, the hydrogen uptake of PAF-RWY reaches 5.9 wt % at 100 bar and 298 K, exceeding the DOE 2015 target (5.5 wt %) for hydrogen storage. Moreover, PAF-RWY is also a promising candidate for methane storage and CO2 capture, owing to its extremely high pore volume and accessible surface area. © 2015 American Chemical Society.


He F.,Beijing University of Chemical Technology | Wang X.,Beijing University of Chemical Technology | Wu D.,Beijing University of Chemical Technology
Renewable Energy | Year: 2015

A series of n-alkanes/silica composites as form-stable phase change materials (PCMs) were synthesized in a sol-gel process using sodium silicate precursor. The chemical compositions and structures of the synthesized composites were characterized by Fourier transform infrared spectroscopy. Scanning electric micrographs show an irregularly spherical morphology of the n-alkanes/silica composites, and transmission electric micrographs confirm that the n-alkanes have been well encapsulated by silica. These n-alkanes/silica composites keep a good sharp stability due to the support of silica wall even if the n-alkanes are in molten state. The differential scanning calorimetric analysis indicates that the phase change behaviors and characteristics of the n-alkanes/silica composites strongly depend on the carbon atom number in n-alkanes, and meanwhile, the encapsulated n-alkanes have a high thermal storage capability. The investigation on thermal performance demonstrated that the n-alkanes/silica composites achieved a high thermal conductivity, low supercooling, and good work reliability as a result of the encapsulation of n-alkanes with highly thermal conductive inorganic silica. Moreover, the thermal stability of the composites was also improved due to the protection of silica wall toward the encapsulated n-alkanes. It is anticipative that, owing to the easy availability and low cost of sodium silicate, the synthetic technology developed by this work has a high feasibility in the industrial manufacture of the form-stable PCMs. © 2014 Elsevier Ltd.


Chai L.,Beijing University of Chemical Technology | Wang X.,Beijing University of Chemical Technology | Wu D.,Beijing University of Chemical Technology
Applied Energy | Year: 2015

A sort of novel bifunctional microencapsulated phase change material (PCM) was designed by encapsulating n-eicosane into a crystalline titanium dioxide (TiO2) shell and, then, was successfully synthesized through in-situ polycondensation in the sol-gel process using tetrabutyl titanate as a titania precursor. The resultant microcapsule samples were characterized by Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy to determine their chemical compositions and structures. Furthermore, the crystallinity of the TiO2 shell was verified by powder X-ray diffraction patterns. It was confirmed that the fluorinions could induce the phase transition from the amorphous TiO2 to the brookite-form crystals during the sol-gel process, thus resulting in a crystalline TiO2 shell for the microencapsulated n-eicosane. The scanning and transmission electron microscopy investigations indicated that all of the resultant microcapsules presented a perfect spherical shape with a uniform particle size of 1.5-2μm, and they also exhibited a well-defined core-shell structure as well as a smooth and compact shell. The crystalline TiO2 shell made the resultant microcapsules a photocatalytic activity, and therefore, these microcapsules demonstrated a good photocatalytic effect for the chemical degradation and an antimicrobial function for some of the Gram-negative bacteria. Most of all, all of the microencapsulated n-eicosane samples indicated good phase-change performance and high thermal reliability for latent-heat storage and release, and moreover, they achieved a high encapsulation efficiency and a high thermal-storage capability. The bifunctional microencapsulated n-eicosane synthesized in this study will be a potential candidate for the applications of waste heat recovery and treatment, intelligent textiles or fabrics for the warmth underwear and medical protective clothing, preservation and sterilization of foods, and solar energy storage and recovery, etc. © 2014 Elsevier Ltd.


Fan G.,Beijing University of Chemical Technology | Wang J.,Beijing University of Chemical Technology | Li F.,Beijing University of Chemical Technology
Catalysis Communications | Year: 2011

High-surface-area ZnAl2O4 with micro/mesoporous frameworks was synthesized via a facile one-pot solvothermal approach without using any surfactants or post-treatment. The results revealed that the textural properties of micro/mesoporous ZnAl2O4 were tuned by changing alcohol/water mixture solvents used in solvothermal synthesis and Ag nanoparticles were dispersed uniformly on the surface of ZnAl2O 4 supports. Especially, the supported Ag catalyst on the microporous ZnAl2O4 synthesized in methanol/water solvent exhibited good catalytic performance for liquid phase selective hydrogenation of o-chloronitrobenzene to o-chloroaniline, owing to the high dispersion of Ag nanoparticles and the strong metal-support interaction. © 2011 Elsevier B.V. All rights reserved.


Song C.,Beijing University of Chemical Technology | Ding L.,Beijing University of Chemical Technology | Yao F.,Beijing University of Chemical Technology | Deng J.,Beijing University of Chemical Technology | Yang W.,Beijing University of Chemical Technology
Carbohydrate Polymers | Year: 2013

This article reports the preparation and evaluation of polymeric microspheres as a new class of oil-absorbent (POAMs). Based on our earlier oil-absorbents, the present microspheres contained β-cyclodextrin (β-CD) moieties as both cross-linking agent and porogen agent, and showed exciting high oil absorbency, fast oil absorption speed and good reusability. Such microspheres were prepared via suspension polymerization with octadecyl acrylate and butyl acrylate as co-monomers, β-CD derivative as cross-linking agent, 2,2′-azoisobutyronitrile as initiator and polyvinylalcohol as stabilizer. Oil absorbency of the POAMs was, for CCl 4, 83.4; CHCl3, 75.1; xylene, 48.7; toluene, 42.8; gasoline, 30.0; kerosene 27.1; and diesel, 18.2 g/g (oil/POAMs). Saturation oil absorption reached within 3 h in CCl4. The POAMs exhibited high oil retention percentage (>90%), and can be reused for at least 10 times while keeping oil absorbency almost unchanged. © 2012 Elsevier Ltd.


Liu W.,Beijing University of Chemical Technology | Wang F.,Beijing University of Chemical Technology | Tan T.,Beijing University of Chemical Technology | Chen B.,Beijing University of Chemical Technology
Carbohydrate Polymers | Year: 2013

Diesters and diols were successfully converted into aliphatic polyesters by enzymatic lipase Candida sp.99-125 catalysis, with β-cyclodextrin acting as supporting architecture (in a similar way as chaperone proteins). No organic solvents were used. The polytransesterification was a much greener process, being solvent-free and without metal residues. Lipase Candida sp.99-125 showed a high catalytic activity for bulkpolymerization of diesters and diols with various numbers of methylene groups in their chains. β-Cyclodextrin encircled the linear polymer chain and maintained the chain in a proper configuration to avoid its coagulation. Lipase initiated the polymerization and β-cyclodextrin threaded onto the polymer chain to control the structure for producing high molecular weight polyesters. From a combination of diesters and diols, polyesters with a high molecular weight of 62,100 Da were obtained at 70 °C. The corresponding polyesters showed an excellent thermal stability till 350 °C and had a strong ability to crystallize with up to 72% crystallinity, contributing to their high storage modulus. © 2012 Elsevier Ltd. All rights reserved.


Huo F.,Beijing University of Chemical Technology | Liu Z.,Beijing University of Chemical Technology | Wang W.,Beijing University of Chemical Technology
Journal of Physical Chemistry B | Year: 2013

Ionic liquids (ILs) are promising nonderivatizing solvents for the dissolution of cellulose and lignin in biomass pretreatment processes, which are, however, retarded by sluggish dynamics. Recent investigations showed that cosolvents such as dimethyl sulfoxide (DMSO) can accelerate the dissolution dramatically. On the other hand, water is used as a common antisolvent to regenerate cellulose from solutions. To understand the co-/antisolvent effects in dissolving cellulose by ILs, we performed molecular dynamics simulations of the interfaces between an Iβ cellulose crystal and different solvent systems, including ILs, DMSO, water, and mixed solvent systems. The density profiles and pair energy distributions (PEDs) show that the anions interact much more strongly with the cellulose surface than the cations, which is responsible for the dissolution of cellulose. It was found that the number of chloride ions in contact with cellulose does not cause the co-/antisolvent effect. In contrast, the cellulose-chloride PEDs are sensitive to the addition of molecular solvents, such as DMSO and water. Detailed analyses show that multiple hydrogen-bond (HB) patterns are formed between chloride and the hydroxyl groups of cellulose that are noticeably changed in the presence of DMSO or water. A combined analyses of both the PEDs and HB patterns can provide valuable information about the enhancement of cellulose dissolution. The simulation results in this work present useful knowledge for the design of solvent systems for dissolving cellulose or other types of biomass. © 2013 American Chemical Society.


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.


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.


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.


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.


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.


Zhu J.,Beijing University of Chemical Technology | Chen X.,Beijing University of Chemical Technology | Yang W.,Beijing University of Chemical Technology
Sensors and Actuators, B: Chemical | Year: 2010

The electrocatalytical oxidation of dihydronicotinamide adenine dinucleotide (NADH) based on exfoliated graphite nanosheet (GNS) modified glassy carbon (GC) electrode was firstly explored. The GNSs/GC electrode showed favorable electron transfer for NADH oxidation and the oxidative peak potential was decreased to +0.32 V vs. Ag/AgCl. The electrochemical sensor based on the GNSs/GC electrode exhibited very high sensitivity of 535.0 mA M-1 cm-2, wide dynamic range from 2 μM to 4.69 mM and good stability for the detection of NADH, which are comparable to or better than those of previously reported most carbon nanomaterials modified electrodes, including recent graphene modified electrodes. Combining the low cost of GNSs with ready preparation from graphite, GNSs would be extremely attractive for numerous dehydrogenase-based bioelectrochemical devices such as biosensors, biofuel cells, and bioreactors in the future work. © 2010 Elsevier B.V.


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.


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.


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.


Guo T.,Beijing University of Chemical Technology | Wang L.,Beijing University of Chemical Technology | Evans D.G.,Beijing University of Chemical Technology | Yang W.,Beijing University of Chemical Technology
Journal of Physical Chemistry C | Year: 2010

The synthesis of p-type polyaniline (PAN) by the in situ polymerization of aniline in the confined interlamellar galleries of an n-type semiconducting layered protonic titanate (LPT) affords an intercalated PAN/LPT nanocomposite. The in situ polymerization of aniline can be initiated by oxygen in the air. The resulting nanocomposites have been characterized by XRD, FTIR, UV-visible spectroscopy, TG-DTG, SEM, and elemental analysis. The PAN/LPT nanocomposites show significant absorption in the visible region, whereas the pristine LPT absorbs only in the ultraviolet region. Under visible irradiation, the PAN π-π* transition delivers excited electrons into the conduction band of LPT, and the subsequent electron transfer to a substrate electrode contributes to the photocurrent. The PAN/LPT nanocomposites exhibit much higher photocatalytic activities for the degradation of methylene blue in aqueous solution under visible light irradiation than LPT itself. © 2010 American Chemical Society.


Zhao F.,Beijing University of Chemical Technology | Zhao F.,CAS Institute of Chemistry | Tang G.,Beijing University of Chemical Technology | Zhang J.,CAS Institute of Chemistry | Lin Y.,CAS Institute of Chemistry
Electrochimica Acta | Year: 2012

A TiO 2 nanocrystalline thin film, sensitized by CdSe quantum dots, was further modified by a TiCl 4 treatment strategy. The CdSe quantum dots with a cubic zinc blende structure were synthesized in situ on the TiO 2 nanocrystalline thin films by chemical bath deposition, after which the sensitized TiO 2 film was further modified by a TiCl 4 treatment strategy. The modification of the amorphous TiO 2 thin layer enhanced the photovoltaic performance of the quantum dot-sensitized thin film. This enhancement was detected by fabricating a solar cell based on the sensitized thin film electrode, a polysulfide electrolyte and a platinized electrode. The modified amorphous TiO 2 was partly crystallized by heating the film at 200 °C to analyze the effect of crystallization on interfacial recombination and the photovoltaic performance. The enhancement due to the TiCl 4 treatment was attributed to the formation of an amorphous TiO 2 thin layer, which separated the uncovered surface of TiO 2 nanoparticles from the electrolyte, and reduced the surface states of the TiO 2 nanocrystals and the quantum dots. The highest conversion efficiency was 2.13%, and it was obtained for the quantum dot-sensitized solar cell after optimizing the CdSe quantum dot deposition and amorphous TiO 2 thin layer modification processes. © 2011 Elsevier Ltd.


Lan J.,Beijing University of Chemical Technology | Cao D.,Beijing University of Chemical Technology | Wang W.,Beijing University of Chemical Technology
Journal of Physical Chemistry C | Year: 2010

A multiscale theoretical method, which combines the first-principles calculation and grand canonical Monte Carlo (GCMC) simulation, is used to investigate the adsorption capacities of hydrogen in nondoped and Li-doped covalent organic borosilicate frameworks (COF-202). Our simulations indicate that the total gravimetric and volumetric hydrogen uptakes of COF-202 reach 7.83 wt % and 44.37 g/L at T = 77 K and p = 100 bar, respectively. To enhance the hydrogen storage capacity of COF-202, the doping of Li atoms in COF-202 is studied systematically. First, the first-principles calculations are performed to investigate the possible adsorption sites and the quantity of Li atoms doped in COF-202. Our results prove that, for a single Li atom, the top of the phenyl groups in COF-202 is the most favorable adsorption site; for coadsorption of two Li atoms, with one adsorbed at the top site of a phenyl group and the other at its neighboring interstitial site between the phenyl group and the B-O-Si linkage is the most favorable adsorption mode. Our GCMC simulations predict that the total gravimetric and volumetric uptakes of hydrogen in the Li-doped COF-202 reach 4.39 wt % and 25.86 g/L at T = 298 K and p = 100 bar, respectively, where the weight percent of Li equals to 7.90 wt %. This suggests that the Li-doped COF-202 is one of the most promising candidates for hydrogen storage at room temperature. © 2010 American Chemical Society.