Time filter

Source Type

Patent
South China University of Technology | Date: 2014-12-02

A system of mixed multivariate digital signature is disclosed. The system includes a signature module configured to sign a message to be signed, and a verification module configured to verify a signature. The signature module includes a data input/output port, a single-pole double-throw switch, a processor, an affine transformation component, a random generator, a linear equations solving component, and an affine transformation inversion component. The verification module includes a data input/output port, a single-pole double-throw switch, a processor and a public key verification component. The system and its method disclosed, under choosing appropriate parameters, can resist known algebraic attacks of multivariate public key cryptosystems, such as the Separation Attack, the Rank Attack, the Direct Attack and the Exhaustive Search Attack, etc. The security level of the system is greater than 2^(84 )and its signing speed is quite fast.


Patent
BOE Technology Group and South China University of Technology | Date: 2015-09-02

This disclosure discloses an oxide semiconductor thin film, a thin film transistor, a manufacturing method and a device, belonging to the field of flat panel display. The oxide semiconductor thin film is made of an oxide containing zirconium and indium. A method of manufacturing the oxide semiconductor thin film comprises preparing a target using the oxide containing zirconium and indium, and sputtering the target to obtain the oxide semiconductor thin film.


Patent
South China University of Technology and Guangzhou Huaxinke Enterprise Co. | Date: 2015-07-13

The present invention relates to a volume pulsed deformation plasticating and conveying method and device by an eccentric rotor. The rotation of the eccentric rotor and the rolling of the rotor in the inner cavity of a stator during constant reverse revolutions cause the volume of the material between the eccentric rotor and the stator to periodically change alternatively along the axial direction and the radial direction of the stator, thereby enabling the volume pulsed deformation plasticating and conveying of the material. The volume pulsed deformation plasticating and conveying device consists of a stator, of which the inner cavity comprises multiple alternatingly disposed spiral segments and straight segments, and an eccentric rotor comprising multiple alternatingly disposed eccentric spiral segments and eccentric straight segments. The eccentric rotor is disposed in the inner cavity of the stator. The eccentric spiral segments and the eccentric straight segments of the eccentric rotor correspond one-to-one with the spiral segments and straight segments of the stator. The present invention can be used as the extruding system of an extruder or be combined with different plunger injection units to form a plasticating injection device of an injection molding machine. The present invention has a short thermo-mechanical distance for the materials, low energy consumption, and wide adaptability.


Patent
South China University of Technology and Guangzhou Huaxinke Enterprise Co. | Date: 2014-12-03

Disclosed are a power time sequence conversion method and device for manufacturing products in batches. A common power is sequentially coupled with power input ends of a plurality of execution mechanisms in different time periods, so as to provide in time order a plurality of power drives required during a batch manufacturing process of products, or provide power drives in different forms such as movements and forces to the same execution mechanism in a relaying manner in two adjacent time periods. A change gear capable of rotation and revolution is sequentially meshed with a plurality of tail end driving gears in different time periods, wherein the tail end driving gears are uniformly distributed in the circumferential direction and serve as power outputs, the revolution of the change gear is braked after each meshing to achieve the power drive of a certain execution mechanism in batch manufacturing of the products, and meanwhile, power drives in different forms such as movements and forces are provided to the same execution mechanism in a relaying manner through a torque converter. Compared with the conventional batch manufacturing of products where a plurality of independent power drives are required, the present invention has remarkable characteristics in low cost, low energy consumption, high reliability, good stability and the like.


Patent
South China University of Technology | Date: 2014-08-12

The present invention discloses a stiffness-controllable earthquake-isolation support using negative gravity stiffness, which comprises an upper plate connected to an upper structure, a lower plate connected to a base structure at the bottom, K supporting columns arranged longitudinally between the upper and lower plates, with the supporting columns respectively connected with the upper and lower plates through a ball hinge, and L elastic connecting plates arranged laterally between the supporting columns, wherein K3, LNK and N1. The mechanical motion mechanism of the present invention composed of the earthquake-isolation support, the supporting column and the ball hinges at both ends of the supporting column forms, under the action of gravity of the upper structure, the negative gravity stiffness that causes the upper structure to deviate from the equilibrium position, and the frame structure consisting of the connecting plates between the supporting columns forms the positive stiffness that restores the upper structure to the equilibrium position, with the stiffness of the earthquake-isolation support adjustable by adjusting the connecting plate, thus allowing the seismic energy to be effectively isolated.


The present invention discloses a stiffness control mechanism of a variable stiffness earthquake-isolation layer adapted to structural earthquake isolation and wind resistance, which comprises an upper flange plate connected to an upper structure, a lower flange plate connected to a base structure at the bottom, a pin key provided between hollow portions of the upper and lower flange plates, with the pin key movable up and down between the hollow portions of the upper and lower flange plates and the height of the pin key greater than the distance between the upper and lower flange plates, and a control means for fixing the pin key or controlling the pin key to move downward. The stiffness control mechanism of the earthquake-isolation layer of the present invention can automatically change stiffness of the earthquake-isolation layer, both effectively wind resistant and effectively earthquake resistant.


Patent
South China University of Technology | Date: 2014-12-04

The present invention discloses an information prediction and crawling method based on a webpage link parameter analysis, comprising the following sequence of steps: calculating statistical parameter features of webpage links, calculating distribution patterns of outlinks contained in webpages, classifying the webpages according to the distribution patterns of the outlinks of the webpages, performing a sampling prediction on webpage resources, performing an crawling test on prediction samples, and performing an overall prediction on the webpage resources. According to the method of the present invention, the deficiencies of the traditional webpages crawling mode are effectively supplemented, the quantity of link resources to be crawled is expanded, a great number of undiscovered webpage resources are predicted by means of the known webpage resource features, and the speed and coverage rate of the webpage information crawling is improved.


Patent
South China University of Technology and Guangzhou Huaxinke Enterprise Co. | Date: 2017-03-22

The present invention relates to a volume pulsed deformation plasticating and conveying method and device by an eccentric rotor. The rotation of the eccentric rotor and the rolling of the rotor in the inner cavity of a stator during constant reverse revolutions cause the volume of the material between the eccentric rotor and the stator to periodically change alternatively along the axial direction and the radial direction of the stator, thereby enabling the volume pulsed deformation plasticating and conveying of the material. The volume pulsed deformation plasticating and conveying device consists of a stator, of which the inner cavity comprises multiple alternatingly disposed spiral segments and straight segments, and an eccentric rotor comprising multiple alternatingly disposed eccentric spiral segments and eccentric straight segments. The eccentric rotor is disposed in the inner cavity of the stator. The eccentric spiral segments and the eccentric straight segments of the eccentric rotor correspond one-to-one with the spiral segments and straight segments of the stator. The present invention can be used as the extruding system of an extruder or be combined with different plunger injection units to form a plasticating injection device of an injection molding machine. The present invention has a short thermo-mechanical distance for the materials, low energy consumption, and wide adaptability.


Patent
South China University of Technology and Guangzhou Huaxinke Enterprise Co. | Date: 2017-03-22

Disclosed are a power time sequence conversion method and device for manufacturing products in batches. A common power is sequentially coupled with power input ends of a plurality of execution mechanisms in different time periods, so as to provide in time order a plurality of power drives required during a batch manufacturing process of products, or provide power drives in different forms such as movements and forces to the same execution mechanism in a relaying manner in two adjacent time periods. A change gear capable of rotation and revolution is sequentially meshed with a plurality of tail end driving gears in different time periods, wherein the tail end driving gears are uniformly distributed in the circumferential direction and serve as power outputs, the revolution of the change gear is braked after each meshing to achieve the power drive of a certain execution mechanism in batch manufacturing of the products, and meanwhile, power drives in different forms such as movements and forces are provided to the same execution mechanism in a relaying manner through a torque converter. Compared with the conventional batch manufacturing of products where a plurality of independent power drives are required, the present invention has remarkable characteristics in low cost, low energy consumption, high reliability, good stability and the like.


Patent
BOE Technology Group and South China University of Technology | Date: 2017-01-25

This invention discloses a thin film transistor and the preparation method thereof, an array substrate, and a display panel, so as to solve the problem that the active layer is prone to be corroded when a metal oxide thin film transistor is produced by a back channel etching process. The preparation method comprises: forming a gate electrode metal thin film on a base substrate, and allowing the gate electrode metal thin film to form a gate electrode metal layer comprising a gate electrode by a patterning process; forming a gate electrode insulating layer on the gate electrode metal layer; forming an active layer on the gate electrode insulating layer; preparing a metal nanoparticle layer on the active layer, said metal nanoparticle layer being used as an etching protection layer; forming a source and drain electrode metal thin film on the base substrate on which the above processes are finished, and allowing the source and drain electrode metal thin film to form a source and drain electrode metal layer comprising a source electrode and a drain electrode by a patterning process, wherein the source electrode and the drain electrode cover a part of the metal nanoparticle layer; removing or oxidizing the part of the metal nanoparticle layer which is not covered by the source electrode and the drain electrode in an oxygen-containing atmosphere; and forming a passivation layer on the source and drain electrode metal layer.


Yuan Y.,National University of Singapore | Kwok R.T.K.,Hong Kong University of Science and Technology | Tang B.Z.,Hong Kong University of Science and Technology | Tang B.Z.,South China University of Technology | And 2 more authors.
Journal of the American Chemical Society | Year: 2014

Targeted drug delivery to tumor cells with minimized side effects and real-time in situ monitoring of drug efficacy is highly desirable for personalized medicine. In this work, we report the synthesis and biological evaluation of a chemotherapeutic Pt(IV) prodrug whose two axial positions are functionalized with a cyclic arginine-glycine-aspartic acid (cRGD) tripeptide for targeting integrin αvβ3 overexpressed cancer cells and an apoptosis sensor which is composed of tetraphenylsilole (TPS) fluorophore with aggregation-induced emission (AIE) characteristics and a caspase-3 enzyme specific Asp-Glu-Val-Asp (DEVD) peptide. The targeted Pt(IV) prodrug can selectively bind to αvβ3 integrin overexpressed cancer cells to facilitate cellular uptake. In addition, the Pt(IV) prodrug can be reduced to active Pt(II) drug in cells and release the apoptosis sensor TPS-DEVD simultaneously. The reduced Pt(II) drug can induce the cell apoptosis and activate caspase-3 enzyme to cleave the DEVD peptide sequence. Due to free rotation of the phenylene rings, TPS-DEVD is nonemissive in aqueous media. The specific cleavage of DEVD by caspase-3 generates the hydrophobic TPS residue, which tends to aggregate, resulting in restriction of intramolecular rotations of the phenyl rings and ultimately leading to fluorescence enhancement. Such noninvasive and real-time imaging of drug-induced apoptosis in situ can be used as an indicator for early evaluation of the therapeutic responses of a specific anticancer drug. © 2014 American Chemical Society.


Rao Z.,South China University of Technology | Wang S.,South China University of Technology | Zhang G.,Guangdong University of Technology
Energy Conversion and Management | Year: 2011

Thermal energy management performance of ageing commercial rectangular LiFePO 4 power batteries using phase change material (PCM) and thermal behavior related to thermal conductivity between the PCM and the cell are discussed in this paper. The heat sources are simplified according to the experimental results of the cells discharged at 35 A (≈5 C). 3-D modules of a single cell and battery pack are formulated, respectively. The results show that the thermal resistance in the cell leads to an inevitable temperature difference. It is necessary to improve the thermal conductivity and to lower the melting point of the PCM for heat transfer enhancement. The PCM with a melting point lower than 45 °C will be more effective for heat dissipation, with a desired maximum temperature below 50 °C. The temperature difference in the whole unit before PCM melting will be decreased significantly. In addition, a proper k PCM:k c is necessary for a well designed battery thermal energy management system. © 2011 Elsevier Ltd. All rights reserved.


Liao C.,South China University of Technology | Xie Y.,Guangdong Pharmaceutical University | Zhou J.,South China University of Technology
RSC Advances | Year: 2014

The orientation and adsorption mechanism of the 10th and 7-10th type III modules of fibronectin (FN-III10, FN-III7-10) on hydroxyapatite surfaces were investigated by a combination of parallel tempering Monte Carlo (PTMC) and molecular dynamics (MD) methods. The PTMC results show a positively charged surface at low ionic strength is beneficial for FN-III10 and FN-III7-10 adsorption with RGD accessible in solution, i.e., FN-III10 adsorbs with "side-on" orientation while FN-III7-10 adsorbs with "lying" orientation. During the adsorption, FN-III10 adsorbs on the hydroxyapatite (HAP) surface first driven by Coulombic interactions at the pre-Adsorption stage. At the post-Adsorption stage, the driving force changes from Coulombic interactions to VDW interactions. Accordingly, slow translation of FN-III10 on the HAP surface was found due to the mismatching of charged groups of protein on the alternative charged surface. The conformational changes of adsorbed FN-III10 mainly take place at its coil/loop parts. FN-III7-10 experiences two stages from weak adsorption to strong adsorption when Coulombic interactions become the dominant driving force. The transition is determined by the anchoring of the basic residues in the Ca2+ vacancies by significant complementary electrostatic interactions and hydrogen bonds formed between the guanidine group and the surrounding phosphate groups. The module III10 of FN-III7-10 exhibits the largest conformational change and contributes to the adsorption most. The affinity of the guanidine group binding suggests that vacancies on biomaterials have the capacity to trap specific residues. This journal is © the Partner Organisations 2014.


Zhang Y.,University of Oslo | Yu R.,South China University of Technology | Xie S.,South China University of Technology | Yao W.,South China University of Technology | And 2 more authors.
IEEE Communications Magazine | Year: 2011

It is envisioned that home networks will shift from current machine-to-human communications to the machine-to-machine paradigm with the rapid penetration of embedded devices in home surroundings. In this article, we first identify the fundamental challenges in home M2M networks. Then we present the architecture of home M2M networks decomposed into three subareas depending on the radio service ranges and potential applications. Finally, we focus on QoS management in home M2M networks, considering the increasing number of multimedia devices and growing visual requirements in a home area. Three standards for multimedia sharing and their QoS architectures are outlined. Cross-layer joint admission and rate control design is reported for QoS-aware multimedia sharing. This proposed strategy is aware of the QoS requirements and resilience of multimedia services. Illustrative results indicate that the joint design is able to intelligently allocate radio bandwidth based on QoS demands in resourceconstrained home M2M networks. © 2006 IEEE.


Wang S.,South China University of Technology | Wang S.,Guangdong Pharmaceutical University | Zhou S.,South China University of Technology
Journal of Hazardous Materials | Year: 2011

A novel nanoscale photocatalyst CNTs/P-TiO2 was successfully prepared by hydrothermal method. The morphology and the physicochemical properties of the prepared samples were investigated using TEM, XPS, XRD, BET, FTIR, TG-DSC and UV-vis DRS spectroscopy. The photocatalytic activity was evaluated by degradation of methyl orange (MO) dye. The results demonstrated that CNTs/P-TiO2 nanoparticles could effectively photodegrade MO not only under UV irradiation but also under visible-light (VL) irradiation. The MO degradation performance on CNTs/P-TiO2 was superior to that of the commercial P25. The optimal mass ratio of CNTs to P-TiO2 in the nanocomposite catalyst was 5:100. The synergetic effect was discussed in terms of different roles played by phosphorus doping and introducing CNTs into the composite catalysts. © 2010.


Pan Y.,South China University of Technology | Er M.J.,Nanyang Technological University | Huang D.,South China University of Technology | Wang Q.,Guangdong University of Technology
IEEE Transactions on Fuzzy Systems | Year: 2011

With no a priori knowledge of plant boundary functions, a novel direct adaptive fuzzy controller (AFC) for a class of single-input single-output (SISO) uncertain affine nonlinear systems is developed in this paper. Based on the theory of fuzzy logic systems (FLSs) with variable universes of discourse (UDs), sufficient conditions that guarantee that the optimal fuzzy approximation error (FAE) is locally convergent are given. By the use of the output tracking error and its derivatives as input variables and by the selection of suitable adjusting parameters, a variable UD FLS with an optimal FAE local convergence is constructed, and its parameter adaptive law is derived by virtue of the Lyapunov stability theorem. Under the assumption that the optimal FAE is bounded, it is proved that the closed-loop system is asymptotically stable in the sense that all variables are uniformly ultimately bounded and that the tracking errors converge to zero. The proposed approach eliminates the influence of the FAE on the tracking errors by means of the inherent mechanism of the variable UD FLS. Thus, it has the potential to achieve high control performance without additional compensation under only a few fuzzy rules. Simulation studies demonstrate the superiority of the proposed AFC in terms of the settling time, tracking accuracy, smoothness of the control input, and robustness against external disturbances and parameter variations. © 2011 IEEE.


Ji H.,National University of Singapore | Yang X.,South China University of Technology | Ling H.,Temple University | Xu Y.,South China University of Technology
IEEE Transactions on Image Processing | Year: 2013

In this paper, we propose a new texture descriptor for both static and dynamic textures. The new descriptor is built on the wavelet-based spatial-frequency analysis of two complementary wavelet pyramids: standard multiscale and wavelet leader. These wavelet pyramids essentially capture the local texture responses in multiple high-pass channels in a multiscale and multiorientation fashion, in which there exists a strong power-law relationship for natural images. Such a power-law relationship is characterized by the so-called multifractal analysis. In addition, two more techniques, scale normalization and multiorientation image averaging, are introduced to further improve the robustness of the proposed descriptor. Combining these techniques, the proposed descriptor enjoys both high discriminative power and robustness against many environmental changes. We apply the descriptor for classifying both static and dynamic textures. Our method has demonstrated excellent performance in comparison with the state-of-the-art approaches in several public benchmark datasets. © 1992-2012 IEEE.


Cao H.,Guangdong Pharmaceutical University | Zhan H.,Guangdong Pharmaceutical University | Lin Y.,Guangdong Pharmaceutical University | Lin X.,Guangdong Pharmaceutical University | And 2 more authors.
Organic Letters | Year: 2012

A convenient method for the copper(I)-catalyzed arylation of substituted imidazo[1,2-a]pyridine has been developed. This method is applicable to a variety of aryl electrophiles, including bromides, iodides, and triflates. It represents the first general process for C-3 arylation of substituted imidazo[1,2-a]pyridine by Cu(I) catalysis to construct various functionalized imidazo[1,2-a]pyridine core π-systems. © 2012 American Chemical Society.


Guo X.,South China University of Technology | Zhang Q.,South China University of Technology | Sun Y.,Peking University | Zhao Q.,Peking University | And 2 more authors.
ACS Nano | Year: 2012

Selective growth/etching of hybrid materials is very important for the rational synthesis of hierarchical structures and precise modulation of their physical properties. Here, the lateral etching of the core-shell Au@Ag nanorods is achieved by FeCl 3 at room temperature, producing a number of dumbbell-like Ag-tipped Au nanorods. This selective etching at the side of the core-shell nanorods is attributed to the increased reactivity of the side facets, due to less surface passivation of cetyltrimethylammonium bromide. The similar synthetic strategy has also been demonstrated to be successful for the Pd-tipped Au nanorods that have not been reported before, indicating the great potential of this selective etching. The Ag-tipped Au nanorods are examined as a catalyst for the reduction of p-nitrophenol at room temperature. The Ag-tipped Au nanorods exhibit a higher catalytic activity than Au nanorods and core-shell Au@Ag nanorods, which could be attributed to the electronic effect and the unique structure in the Ag-tipped Au nanorods. © 2012 American Chemical Society.


Li H.,Guangzhou University | Shi Z.,Guangdong University of Technology | Jiang X.,Guangdong University of Technology | Zhu X.,South China University of Technology
Optics Letters | Year: 2011

We numerically study the gray solitons in parity-time (PT) symmetric potentials. Simulated results show that there are two kinds of gray solitons, the dip-shaped gray solitons and the hump-shaped solitons, and both of them can be stable. Hump-shaped solitons can always exist, but the grayness of a stable dip-shaped gray soliton should exceed a threshold value. More interesting, it is discovered that when propagating in PT symmetric potentials, the gray solitons have no transverse deviation, and this is a phenomenon different from the usual gray solitons. © 2011 Optical Society of America.


Shi H.,National University of Singapore | Kwok R.T.K.,Hong Kong University of Science and Technology | Liu J.,Hong Kong University of Science and Technology | Xing B.,Nanyang Technological University | And 5 more authors.
Journal of the American Chemical Society | Year: 2012

Real-time monitoring of cell apoptosis could provide valuable insights into early detection of therapy efficiency and evaluation of disease progression. In this work, we designed and synthesized a new live-cell-permeable, fluorescent light-up probe for real-time cell apoptosis imaging. The probe is comprised of a hydrophilic caspase-specific Asp-Glu-Val-Asp (DEVD) peptide and a hydrophobic tetraphenylethene (TPE) unit, a typical fluorogen with aggregation-induced emission characteristics. In aqueous solution, the probe is almost nonfluorescent but displays significant fluorescence enhancement in response to caspase-3/-7, which are activated in the apoptotic process and able to cleave the DEVD moieties. This fluorescence "turn-on" response is ascribed to aggregation of cleaved hydrophobic TPE residues, which restricts the intramolecular rotations of TPE phenyl rings and populates the radiative decay channels. The light-up nature of the probe allows real-time monitoring of caspase-3/-7 activities both in solutions and in living cells with a high signal-to-noise ratio. The probe provides a new opportunity to screen enzyme inhibitors and evaluate the apoptosis-associated drug efficacy. © 2012 American Chemical Society.


Yuan Y.,National University of Singapore | Zhang C.-J.,National University of Singapore | Gao M.,Institute of Materials Research and Engineering of Singapore | Zhang R.,National University of Singapore | And 4 more authors.
Angewandte Chemie - International Edition | Year: 2015

Activatable photosensitizers (PSs) have been widely used for the simultaneous fluorescence imaging and photodynamic ablation of cancer cells. However, the ready aggregation of traditional PSs in aqueous media can lead to fluorescence quenching as well as reduced phototoxicity even in the activated form. We have developed a series of PSs that show aggregation-enhanced emission and phototoxicity and thus the exact opposite behavior to that of previously reported PSs. We further developed a dual-targeted enzyme-activatable bioprobe based on the optimized photosensitizer and describe simultaneous light-up fluorescence imaging and activated photodynamic therapy for specific cancer cells. The design of smart probes should thus open new opportunities for targeted and image-guided photodynamic therapy. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.


Ding D.,National University of Singapore | Li K.,Institute of Materials Research and Engineering of Singapore | Liu B.,National University of Singapore | Liu B.,Institute of Materials Research and Engineering of Singapore | And 3 more authors.
Accounts of Chemical Research | Year: 2013

Fluorescent bioprobes are powerful tools for analytical sensing and optical imaging, which allow direct visualization of biological analytes at the molecular level and offer useful insights into complex biological structures and processes. The sensing and imaging sensitivity of a bioprobe is determined by the brightness and contrast of its fluorescence before and after analyte binding. Emission from a fluorophore is often quenched at high concentration or in aggregate state, which is notoriously known as concentration quenching or aggregation-caused quenching (ACQ). The ACQ effect limits the label-to-analyte ratio and forces researchers to use very dilute solutions of fluorophores. It compels many probes to operate in a fluorescence "turn-off" mode with a narrow scope of practical applications.The unique aggregation-induced emission (AIE) process offers a straightforward solution to the ACQ problem. Typical AIE fluorogens are characterized by their propeller-shaped rotorlike structures, which undergo low-frequency torsional motions as isolated molecules and emit very weakly in solutions. Their aggregates show strong fluorescence mainly due to the restriction of their intramolecular rotations in the aggregate state. This fascinating attribute of AIE fluorogens provides a new platform for the development of fluorescence light-up molecules and photostable nanoaggregates for specific analyte detection and imaging.In this Account, we review our recent AIE work to highlight the utility of AIE effect in the development of new fluorescent bioprobes, which allows the use of highly concentrated fluorogens for biosensing and imaging. The simple design and fluorescence turn-on feature of the molecular AIE bioprobes offer direct visualization of specific analytes and biological processes in aqueous media with higher sensitivity and better accuracy than traditional fluorescence turn-off probes. The AIE dot-based bioprobes with different formulations and surface functionalities show advanced features over quantum dots and small molecule dyes, such as large absorptivity, high luminosity, excellent biocompatibility, free of random blinking, and strong photobleaching resistance. These features enable cancer cell detection, long term cell tracing, and tumor imaging in a noninvasive and high contrast manner. Recent research has significantly expanded the scope of biological applications of AIE fluorogens and offers new strategies to fluorescent bioprobe design. We anticipate that future development on AIE bioprobes will combine one- or multiphoton fluorescence with other modalities (e.g., magnetic resonance imaging) or functionalities (e.g. therapy) to fully demonstrate their potential as a new generation of theranostic reagent. In parallel, the advances in molecular biology will provide more specific bioreceptors, which will enable the development of next generation AIE bioprobes with high selectivity and sensitivity for molecular sensing and imaging. © 2013 American Chemical Society.


Zhou S.,Fujian Normal University | Xiao W.,South China University of Technology
Information Processing Letters | Year: 2010

The growing size of a multiprocessor system increases its vulnerability to component failures. In order to maintain the system's high reliability, it is crucial to identify and replace the faulty processors through testing, a process known as fault diagnosis. The minimum size of a largest connected component in such a networked system is typically used as a measure for fault tolerance of the system. For this measure, the conditional diagnosability of the system in terms of an alternating group network is important, which is studied in the present paper under a comparison model, with some precise and useful bounds of tolerance derived. © 2010.


Wang C.,South China University of Technology | Chen T.,Guangdong University of Technology
IEEE Transactions on Neural Networks | Year: 2011

Detection of small faults is one of the most important and challenging tasks in the area of fault diagnosis. In this paper, we present an approach for the rapid detection of small oscillation faults based on a recently proposed deterministic learning (DL) theory. The approach consists of two phases: the training phase and the test phase. In the training phase, the system dynamics underlying normal and fault oscillations are locally accurately approximated through DL. The obtained knowledge of system dynamics is stored in constant radial basis function (RBF) networks. In the diagnosis phase, rapid detection is implemented. Specially, a bank of estimators are constructed using the constant RBF neural networks to represent the training normal and fault modes. By comparing the set of estimators with the test monitored system, a set of residuals are generated, and the average L1 norms of the residuals are taken as the measure of the differences between the dynamics of the monitored system and the dynamics of the training normal mode and oscillation faults. The occurrence of a test oscillation fault can be rapidly detected according to the smallest residual principle. A rigorous analysis of the performance of the detection scheme is also given. The novelty of the paper lies in that the modeling uncertainty and nonlinear fault functions are accurately approximated and then the knowledge is utilized to achieve rapid detection of small oscillation faults. Simulation studies are included to demonstrate the effectiveness of the approach. © 2011 IEEE.


Fan J.,South China University of Technology | Zeng F.,South China University of Technology | Wu S.,South China University of Technology | Wang X.,Guangdong Pharmaceutical University
Biomacromolecules | Year: 2012

In this study, an novel amphiphilic block copolymer P[PEGMA-b-(DEMA-co- APMA)]-FA and its cross-linker uracil-(CH2)6-uracil (U-(CH2)6-U) were synthesized and used as the targeted and pH-responsive nanocarriers for anticancer drug delivery. The hydrophobic block of the copolymer contains adenine (A) and tertiary amine moieties and the hydrophilic block is terminated with a targeting ligand folic acid (FA). Under neutral pH, the hydrophobic chain segments of the copolymer are cross-linked by U-(CH2)6-U through the A-U nucleobase pairing based on complementary multiple hydrogen bonding, and the copolymer forms stable micelles with their mean diameter of around 170 nm in water. While under acidic pH, the micelles dissociate as a result of protonation of tertiary amines and disruption of the A-U nucleobase pairing. Flow cytometry and fluorescent microscope observation show that, when loaded with an anticancer drug DOX, the micelles can preferably enter folate receptor (FR)-positive cancer cells and kill the cells via intracellular release of the anticancer drug. Cytotoxicity tests (MTT tests) indicate that the micelles with FA on their surfaces exhibit higher cytotoxicity toward FR-positive cells than those without FA. This study provides useful insights on designing and improving the applicability of copolymer micelles for other targeted drug delivery systems. © 2012 American Chemical Society.


Xu Y.,South China University of Technology | Quan Y.,South China University of Technology | Ling H.,Temple University | Ji H.,National University of Singapore
Proceedings of the IEEE International Conference on Computer Vision | Year: 2011

In this paper, we developed a novel tool called dynamic fractal analysis for dynamic texture (DT) classification, which not only provides a rich description of DT but also has strong robustness to environmental changes. The resulting dynamic fractal spectrum (DFS) for DT sequences consists of two components: One is the volumetric dynamic fractal spectrum component (V-DFS) that captures the stochastic self-similarities of DT sequences as 3D volume datasets; the other is the multi-slice dynamic fractal spectrum component (S-DFS) that encodes fractal structures of DT sequences on 2D slices along different views of the 3D volume. Various types of measures of DT sequences are collected in our approach to analyze DT sequences from different perspectives. The experimental evaluation is conducted on three widely used benchmark datasets. In all the experiments, our method demonstrated excellent performance in comparison with state-of-the-art approaches. © 2011 IEEE.


Fan J.,South China University of Technology | Fang G.,South China University of Technology | Zeng F.,South China University of Technology | Wang X.,Guangdong Pharmaceutical University | Wu S.,South China University of Technology
Small | Year: 2013

Prodrug therapy is one strategy to deliver anticancer drugs in a less reactive manner to reduce nonspecific cytotoxicity. A new multifunctional anticancer prodrug system based on water-dispersible fullerene (C60) aggregates is introduced; this prodrug system demonstrates active targeting, pH-responsive chemotherapy, and photodynamic therapeutic (PDT) properties. Incorporating (via a cleavable bond) an anticancer drug, which is doxorubicin (DOX) in this study, and a targeting ligand (folic acid) onto fullerene while maintaining an overall size of approximately 135 nm produces a more specific anticancer prodrug. This prodrug can enter folate receptor (FR)-positive cancer cells and kill the cells via intracellular release of the active drug form. Moreover, the fullerene aggregate carrier exhibits PDT action; the cytotoxicity of the system towards FR-positive cancer cells is increased in response to light irradiation. As the DOX drug molecules are conjugated onto fullerene, the DOX fluorescence is significantly quenched by the strong electron-accepting capability of fullerene. The fluorescence restores upon release from fullerene, so this fluorescence quenching-restoring feature can be used to track intracellular DOX release. The combined effect of chemotherapy and PDT increases the therapeutic efficacy of the DOX-fullerene aggregate prodrug. This study provides useful insights into designing and improving the applicability of fullerene for other targeted cancer prodrug systems. Kill cancer cells with dual actions: A water-dispersible fullerene-aggregate-based Water-dispersible C60 aggregate based anticancer prodrug can selectively enter folic acid-positive cancer cells and kill them with both released drug and photodynamic therapeutic action under light irradiation. Thus enhanced cytotoxicity towards these cancer cells can be realized. The fluorescence quenching-restoring feature is utilized to track the intracellular drug release. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Zhou Y.,Peking University | Ding L.,Peking University | Shi K.,Peking University | Dai Y.-Z.,Peking University | And 3 more authors.
Advanced Materials | Year: 2012

A novel n-type small molecule FFI-1 was synthesized as the electron acceptor to replace PCBM in solution-processed organic BHJ solar cells. Its LUMO level (around -3.5 eV) both matches the work function of the cathode and increases VOC of the devices, making it a promising acceptor candidate. With P3HT: FFI-1 (1:2 w/w) as active layer and LiF/Al as the cathode, the best power conversion efficiency (PCE) reaches 1.86%. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Li W.,Guangdong University of Technology | Liu Z.,South China University of Technology
Procedia Environmental Sciences | Year: 2011

Network intrusion is always hidden in a mass of routine data and the differences between these data are very large. Normalization can help to speed up the learning phase and avoiding numerical problems such as precision loss from arithmetic overflows. Some normalization methods are analyzed and simulated. Experiments results show that the method using SVM with normalization has much better performance compared to the method using SVM without normalization in classing intrusion data of KDD99 and Min-Max Normalization has better performance in speed, accuracy of cross validation and quantity of support vectors than other normalization methods. © 2011 Published by Elsevier Ltd.


Xiao H.,South China University of Technology | Li Z.,South China University of Technology | Philip C.,University of Macau
IEEE Transactions on Industrial Electronics | Year: 2016

In this paper, a neural-dynamic optimization-based nonlinear model predictive control (NMPC) is developed for controlling leader-follower mobile robots formation. Consider obstacles in the environments, a control strategy is proposed for the formations which includes separation-bearing-orientation scheme (SBOS) for regular leader-follower formation and separation-distance scheme (SDS) for obstacle avoidance. During the formation motion, the leader robot shall track a desired trajectory and the desire leader-follower relationship can be maintained through SBOS method; meanwhile, the followers can avoid the collision by applying the SDS. The formation-error kinematics of both SBOS and SDS are derived and a constrained quadratic programming (QP) can be obtained by transforming the MPC method. Then, over a finite-receding horizon, the QP problem can be solved by utilizing the primal-dual neural network (PDNN) with parallel capability. The computation complexity can be greatly reduced by the implemented neural-dynamic optimization. Compared with other existing formation control approaches, the developed solution in this paper is rooted in NMPC techniques with input constraints and the novel QP problem formulation. Finally, experimental studies of the proposed formation control approach have been performed on several mobile robots to verify the effectiveness. © 1982-2012 IEEE.


Zhou Y.,Peking University | Lei T.,Peking University | Wang L.,South China University of Technology | Pei J.,Peking University | And 2 more authors.
Advanced Materials | Year: 2010

High performance p-channel transistors based on a single-crystal organic microribbon self-assembled through a solution process, are achieved by enhancing the crystallinity, improving the interface between the dielectric and the crystal, shrinking the channel length, and realizing asymmetric metal electrodes for source and drain (see figure). The highest mobility reached is 2.1Cm 2V-1S-1 with an on/off ratio of 2 x 10 5 and a threshold voltage of-7 V. (Figure Presented) © 2010 WILEY-VCH Verlag GmbH & Co. KCaA.


Dong Y.Z.,South China University of Technology | Zhao Y.M.,South China University of Technology | Duan H.,Guangdong University of Technology
Journal of Electroanalytical Chemistry | Year: 2011

The Mg-doped Li3V2-xMgx(PO 4)3 (x = 0.00, 0.01, 0.02, 0.05, 0.10, 0.20, 0.30, 0.33, 0.50, 1.00 and 1.33) compounds have been prepared by a sol-gel method in reducing atmosphere (70%Ar + 30%H2) using citric acid as a chelating agent and a carbon source coated on the samples. The Mg-doped effects on the structural and electrochemical performance of Li3V 2(PO4)3 are investigated by X-ray diffraction, galvanostatic, charge/discharge and four-point probe measurement method. The Li3V2-xMgx(PO4) 3 solid solution phase can exist stable in the composition range between x = 0.00 and 0.27. The simple improve mechanism of the electrochemical performance for Mg-doped Li3V2-xMg x(PO4)3 system is discussed too. In the Mg-doped Li3V2-xMgx(PO 4)3 system, at a lower charge/discharge rate (0.1C), the cycle performance has no much improvement with the increasing Mg doping content. However, at higher rates, there has an excited improvement in both cycle performance and rate capability due to the increase of electrical conductivity (more than one order of magnitude). At 5C charge/discharge rate, for the Li 3V1.95Mg0.05(PO4)3 sample, the discharge capacities for the 1st and 100th cycle were 138.9 and 123.3 mAh g-1. The discharge capacity retention reached to 89% (more than 51% for undoped Li3V2(PO4)3 system). More important is that, except for the first 15 cycles, the discharge capacities kept almost a constant. Based on the excellent electrochemical performance, Li3V1.95Mg0.05(PO 4)3 will be a promising cathode material for rechargeable lithium-ion batteries. © 2011 Elsevier B.V. All rights reserved.


Xie J.H.,Guangdong University of Technology | Huang P.Y.,South China University of Technology | Guo Y.C.,Guangdong University of Technology
Construction and Building Materials | Year: 2012

A series of experiments were conducted to investigate the fatigue damage behavior of reinforced concrete (RC) beams strengthened with prestressed fiber reinforced polymer (FRP) under three-point bending. Based on the experimental results, the fatigue failure mechanism of the strengthened beams and the propagation process of the fatigue interface cracks were presented, and an empirical formula was developed to predict the fatigue lives of such members. Moreover, a theoretical method was proposed to quantify the dynamic flexural stiffness of the strengthened beams. Based on the flexural stiffness, a fatigue accumulative damage model was established to describe the fatigue fracture process of the strengthened beams. The results show that the theoretical model is in good agreement with the experimental data. © 2011 Elsevier Ltd. All rights reserved.


Mei J.,Hong Kong University of Science and Technology | Hong Y.,Hong Kong University of Science and Technology | Hong Y.,China Institute of Technology | Lam J.W.Y.,Hong Kong University of Science and Technology | And 6 more authors.
Advanced Materials | Year: 2014

"United we stand, divided we fall."-Aesop.Aggregation-induced emission (AIE) refers to a photophysical phenomenon shown by a group of luminogenic materials that are non-emissive when they are dissolved in good solvents as molecules but become highly luminescent when they are clustered in poor solvents or solid state as aggregates. In this Review we summarize the recent progresses made in the area of AIE research. We conduct mechanistic analyses of the AIE processes, unify the restriction of intramolecular motions (RIM) as the main cause for the AIE effects, and derive RIM-based molecular engineering strategies for the design of new AIE luminogens (AIEgens). Typical examples of the newly developed AIEgens and their high-tech applications as optoelectronic materials, chemical sensors and biomedical probes are presented and discussed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Chen S.,University of Adelaide | Liu G.,South China University of Technology | Yadegari H.,University of Western Ontario | Wang H.,South China University of Technology | Qiao S.Z.,University of Adelaide
Journal of Materials Chemistry A | Year: 2015

Two-dimensional (2D) ultrathin nanocrystals represent a family of emerging nanomaterials with many proposed applications; however, the interlayer re-stacking between sheets greatly decreases the performance during practical operation. This work demonstrates a facile strategy to solve this challenging problem by rational assembly of 2D nanocrystals into three-dimensional (3D) aerogels, which paves the way for harvesting excellent structural properties of both nanostructures and macrostructures. The resultant 3D MnO2 aerogel shows significantly increased discharge capacity in Li-air batteries in comparison to its powder-like counterpart (4581.4 vs. 3902.6 mA h g-1), which outperforms many MnO2 and other transition metal-based electrocatalysts. Meanwhile, the as-fabricated Li-air cell demonstrates good rate capability and cycle life. Further mechanism study reveals that the improved performance is associated with ultrathin MnO2 nanosheets which allow highly exposed catalytic centres, as well as its excellent aerogel structure with rich porosity and a 3D continuous network that maximizes the utilization of MnO2 species for catalytic reactions. This study may open up new opportunities for making full use of 2D nanocrystals for a number of energy storage/conversion techniques. © The Royal Society of Chemistry 2015.


Mei J.,China Institute of Technology | Mei J.,Hong Kong University of Science and Technology | Leung N.L.C.,China Institute of Technology | Leung N.L.C.,Hong Kong University of Science and Technology | And 7 more authors.
Chemical Reviews | Year: 2015

Aggregation-induced emission (AIE) is another photophysical phenomenon associated with chromophore aggregation. The concept of AIE has been introduced by a group of researchers in 2001. In the AIE process, non-emissive luminogens are induced to emit by the aggregate formation. The luminogens exhibiting AIE attributes are termed AIEgens, by analogue with the term of 'mesogens' for the molecules showing mesomorphism under suitable conditions.


Zhou W.,South China University of Technology | Lian Z.,University of Macau
International Journal of Production Economics | Year: 2011

The classical Shewhart NP control chart is used widely in industrial and service practice for the relative simplicity of handling attribute quality characteristics. However, the static strategies become less and less adequate for today's highly competitive industrial society because of their low efficiency to detect slight process changes promptly. To improve the capability of control charts, some adaptive schemes, such as variable sample size (VSS), variable sample interval (VSI), and variable control limits (VCL), have been extensively studied in the recent decade. In this paper, we propose a new VSS NP control chart with adjusting sampling inspection (called ASI-NP chart) and give the performance analysis using Markov chain. As the optimal model is related to an integer nonlinear program, genetic algorithms (GAs) are involved and Taguchi experiments are applied to configure the parameter of the GAs in numerical examples. The comparison study between classical NP chart and ASI-NP chart is conducted, and the result shows that ASI-NP chart's performance characteristics are significantly better than those of classical NP charts in all situations, especially, in processes with slight shift and high quality. © 2010 Elsevier B.V. All rights reserved.


Kwok R.T.K.,China Institute of Technology | Kwok R.T.K.,Hong Kong University of Science and Technology | Leung C.W.T.,China Institute of Technology | Leung C.W.T.,Hong Kong University of Science and Technology | And 5 more authors.
Chemical Society Reviews | Year: 2015

Fluorescent biosensors are powerful analytical tools for studying biological events in living systems. Luminescent materials with aggregation-induced emission (AIE) attributes have attracted much research interest and have been identified as a novel class of luminogens to develop fluorescent turn-on biosensors with superior sensitivity. In this Tutorial Review, we present an overview of the AIE phenomenon and its mechanism. We summarize the structural design and working principle of AIE biosensors developed recently. Typical examples of AIE biosensors are presented. This journal is © The Royal Society of Chemistry.


Liang J.,National University of Singapore | Tang B.Z.,Hong Kong University of Science and Technology | Tang B.Z.,South China University of Technology | Liu B.,National University of Singapore | Liu B.,Institute of Materials Research and Engineering ASTAR
Chemical Society Reviews | Year: 2015

Driven by the high demand for sensitive and specific tools for optical sensing and imaging, bioprobes with various working mechanisms and advanced functionalities are flourishing at an incredible speed. Conventional fluorescent probes suffer from the notorious effect of aggregation-caused quenching that imposes limitation on their labelling efficiency or concentration to achieve desired sensitivity. The recently emerged fluorogens with an aggregation-induced emission (AIE) feature offer a timely remedy to tackle the challenge. Utilizing the unique properties of AIE fluorogens (AIEgens), specific light-up probes have been constructed through functionalization with recognition elements, showing advantages such as low background interference, a high signal to noise ratio and superior photostability with activatable therapeutic effects. In this tutorial review, we summarize the recent progress in the development of specific AIEgen-based light-up bioprobes. Through illustration of their operation mechanisms and application examples, we hope to provide guidelines for the design of more advanced AIE sensing and imaging platforms with high selectivity, great sensitivity and wide adaptability to a broad range of biomedical applications. This journal is © The Royal Society of Chemistry.


Wang Z.,Beijing Normal University | Dai Z.,Beijing Normal University | Gong G.,Beijing Normal University | Zhou C.,Hong Kong Baptist University | And 2 more authors.
Neuroscientist | Year: 2015

Relating the brain's structural connectivity (SC) to its functional connectivity (FC) is a fundamental goal in neuroscience because it is capable of aiding our understanding of how the relatively fixed SC architecture underlies human cognition and diverse behaviors. With the aid of current noninvasive imaging technologies (e.g., structural MRI, diffusion MRI, and functional MRI) and graph theory methods, researchers have modeled the human brain as a complex network of interacting neuronal elements and characterized the underlying structural and functional connectivity patterns that support diverse cognitive functions. Specifically, research has demonstrated a tight SC-FC coupling, not only in interregional connectivity strength but also in network topologic organizations, such as community, rich-club, and motifs. Moreover, this SC-FC coupling exhibits significant changes in normal development and neuropsychiatric disorders, such as schizophrenia and epilepsy. This review summarizes recent progress regarding the SC-FC relationship of the human brain and emphasizes the important role of large-scale brain networks in the understanding of structural-functional associations. Future research directions related to this topic are also proposed. © The Author(s) 2014.


News Article | December 5, 2016
Site: www.materialstoday.com

The recipient of the 2017 Acta Biomaterialia Gold Medal is Professor Allan S. Hoffman,             Emeritus Professor of Bioengineering at the University of Washington in Seattle. The Award will be presented at the 2017 Meeting of the Society for Biomaterials to be held in Minneapolis in April 2017. Professor Hoffman studied at M.I.T., where he received his B.S., M.S., and Sc.D. degrees in Chemical Engineering between 1953 and 1957. He taught on the faculty of the Chemical Engineering Department at M.I.T. for a total of ten years. He then spent 46 years as Professor of Bioengineering and Chemical Engineering at the University of Washington in Seattle, Washington. Prof. Hoffman’s major research interests are in drug delivery; diagnostic assays; “smart”, stimuli-responsive polymers; hydrogels; and chemical and biological modification of biomaterial surfaces. He has published over 400 peer-reviewed articles and is co-inventor on over 35 issued patents.  He is co-Editor (along with Buddy D. Ratner, Fred J. Schoen and Jack E. Lemons) of “Biomaterials Science”, Elsevier Publishers, now in its 3rd Edition. His early work in 1984 on the use of “smart” polymers in a temperature-driven phase separation immunoassay sparked a huge worldwide interest in such stimuli-responsive polymers as biomaterials.  Biomedical applications of “smart” polymers continue to grow rapidly around the world at the present time. He has been an Honorary Professor at: Sichuan University, Chengdu, China; South China University of Technology, Guangzhou, China; Wuhan University, Wuhan, China; Shanghai University, Shanghai, China; and Aarhus University, Aarhus, Denmark. In 2013 he completed a four-year appointment (2009-2013) as WCU (“World Class University”) Distinguished Professor at the Kyungpook National University Medical School in Daegu, South Korea. Professor Hoffman was elected to the US National Academy of Engineering in 2005.  His other recognitions and awards include Presidency of the US Society for Biomaterials (1983); the “Biomaterials Science Prize” of the Japanese Society for Biomaterials (1990); the Founders’ Award of the US Society for Biomaterials (in 2000); the Chandra Sharma Award of the Society for Biomaterials and Artificial Organs of India (2003); the “International Polymer Research Award” of the Japanese Society of Polymer Science (2006), and the Founder’s Award of the US Controlled Release Society (2007); Special symposia have been organized in Maui, Hawaii by his colleagues to celebrate his 60th, 70th and 80th birthdays. Former students, along with many academic colleagues, have also organized symposia which they have called “Hoffman Family Symposia” (HFS) and since 2010 there have been four, the first two were in Tokyo, Japan in 2012 and 2014, the third was in Gwangju, Korea in 2015, and a fourth was in Taipei, Taiwan September, 2016.  A fifth HFS will be held in Shanghai, China this coming October, 2017.


Li Z.,Shanghai JiaoTong University | Li Z.,South China University of Technology | Yang C.,University of Plymouth
IEEE Transactions on Control Systems Technology | Year: 2012

The wheeled inverted pendulum (WIP) models have been widely applied in the transportation vehicles formed by a mobile wheeled inverted pendulum system with an operator (demonstrated in Fig.1 ). In this paper, we focus on the study of nonlinear control design for the WIP model-based vehicles, for which accurate dynamics could not be obtained beforehand due to the presence of uncertainties caused by the human operator as well as the vehicle. We develop an output feedback adaptive neural network (NN) control incorporating a linear dynamic compensator to achieve stable dynamic balance and tracking of the desired given trajectories. Comparison simulation studies demonstrate guaranteed tracking performance and stable dynamics balance in the presence of uncertainties and thus verify the efficiency of the developed nonlinear controller. © 2012 IEEE.


Deng F.,South China University of Technology | Luo Q.,Nanjing University of Information Science and Technology | Mao X.,University of Strathclyde
Automatica | Year: 2012

This paper aims to determine whether or not a stochastic state feedback control can stabilize a given linear or nonlinear hybrid system. New methods are developed and sufficient conditions on the stability for hybrid stochastic differential equations are provided. These results are then used to examine stochastic stabilization by stochastic feedback controls. Two types of structure controls, namely state feedback and output injection, are discussed. Our stabilization criteria are in terms of linear matrix inequalities (LMIs) whence the feedback controls can be designed more easily in practice. A couple of examples and computer simulations are worked out to illustrate our theory. © 2012 Elsevier Ltd. All rights reserved.


Chang L.,University of Illinois at Urbana - Champaign | Wu Z.,South China University of Technology
International Journal of Electrical Power and Energy Systems | Year: 2011

The stability and reliability of electrical power grids are indispensable to the continuous operation of modern cities and critical for preparedness, response, recovery and mitigation in emergence management. Because present power grids in China are often running near their critical operation points, they are especially vulnerable and sensitive to external disturbances such as hurricanes, earthquakes and terrorist attacks, which may trigger cascading failures or blackouts. This paper describes a quantitative investigation of the stability and reliability of power grids with a focus on cascading failures under external disturbances. The 118-bus (substation) power network in Hainan, China is employed as a case study to investigate the risk of cascading failure of the regional power grids. System performance and reliability of the power grids are evaluated under two hypothetical scenarios (seismic impact and intentional disturbance) that could trigger cascading failures. By identifying the most vulnerable (critical) edges and nodes, the robustness of the power network is evaluated under the triggered cascading failures. It is found that the system reliabilities could decline as much as 95% during the triggered cascading failure. This paper also explores the use of concepts from modern complex network theories such as state transition graph and characteristic length to understand the complex mechanism of cascading failures. The findings could be useful for power industries and emergency managers to evaluate the vulnerability of power systems, understand the risk of blackout induced by cascading failures, and improve the resilience of power systems to external disturbances. © 2011 Elsevier Ltd. All rights reserved.


Hu R.,HKUST Shenzhen Research Institute | Hu R.,Hong Kong University of Science and Technology | Leung N.L.C.,Hong Kong University of Science and Technology | Tang B.Z.,HKUST Shenzhen Research Institute | And 2 more authors.
Chemical Society Reviews | Year: 2014

Macromolecules with aggregation-induced emission (AIE) attributes are a class of luminescent materials that display enhanced emission when they are aggregated. They have attracted much attention because of their good solubility, processability, high emission efficiency in the aggregated states, etc. A large variety of AIE macromolecules have been developed, showing exponential growth of research interest in this field. This review summarizes the design principles and recent synthetic advancements, topological structures, as well as the frontiers of functionalities and potential applications of AIE macromolecules, especially fluorescence sensing, biological applications and optoelectronic applications, with an emphasis on the recent progress. New luminogenic systems without conventional chromophores displaying aggregated state emission are discussed. The highly dense clusters of heteroatoms with lone pair electrons in these systems may serve as the chromophore and are cited as "heterodox clusters". It is expected that the mechanistic insights into the AIE phenomena, based on the restriction of intramolecular motions and structure rigidification, can guide the future design of AIE materials with fascinating structures and functionalities. © 2014 The Royal Society of Chemistry.


Guan Q.,South China University of Technology | Yu F.R.,Carleton University | Jiang S.,South China University of Technology | Leung V.C.M.,University of British Columbia
IEEE Transactions on Vehicular Technology | Year: 2012

Security is the main concern and bottleneck for widely deployed wireless applications due to the fact that wireless channels are vulnerable to attacks and that wireless bandwidth is a constrained resource. In this sense, it is desirable to adaptively achieve security according to the available resource. In particular, mobile ad hoc networks (MANETs) based on cooperative communication (CC) present significant challenges to security issues, as well as issues of network performance and management. In this paper, we focus on authentication and topology control issues. Although authentication and topology control are separately studied in most existing works, they are, in fact, closely correlated in MANETs. For example, both authentication and topology control schemes have significant impacts on throughput. In this paper, we jointly consider authentication and topology control. Specifically, we analyze the effective throughput with upper layer authentication schemes and physical-layer schemes related to channel conditions and relay selections for CCs. A joint authentication and topology control (JATC) scheme is proposed to improve the throughput. JATC is formulated as a discrete stochastic optimization problem, which does not require prior perfect channel status but only channel estimate. We also mathematically prove the tracking convergence property and the convergence rate of the discrete stochastic optimization approach in this paper. Simulation results show that our scheme can substantially improve throughput in MANETs with CC. © 2012 IEEE.


Gu G.-Y.,Shanghai JiaoTong University | Zhu L.-M.,Shanghai JiaoTong University | Su C.-Y.,South China University of Technology | Su C.-Y.,Concordia University at Montréal | Ding H.,Shanghai JiaoTong University
IEEE/ASME Transactions on Mechatronics | Year: 2013

In this paper, a general skeleton on modeling, controller design, and applications of the piezoelectric positioning stages is presented. Toward this framework, a general model is first proposed to characterize dynamic behaviors of the stage, including frequency response of the stage, voltage-charge hysteresis and nonlinear electric behavior. To illustrate the validity of the proposed general model, a dynamic backlash-like model is adopted as one of hysteresis models to describe the hysteresis effect, which is confirmed by experimental tests. Thus, the developed model provides a general frame for controller design. As an illustration to this aspect, a robust adaptive controller is developed based on a reduced dynamic model under both unknown hysteresis nonlinearities and parameter uncertainties. The proposed control law ensures the boundedness of the closed-loop signals and desired tracking precision. Finally, experimental tests with different motion trajectories are conducted to verify the proposed general model and the robust control law. Experimental results demonstrate the excellent tracking performance, which validates the feasibility and effectiveness of the proposed approach. © 1996-2012 IEEE.


Lin S.-L.,South China University of Technology | Xu M.-Y.,Guangdong Industry Technical College | Yang Z.-R.,South China University of Technology
Soft Matter | Year: 2012

For the first time dissipative particle dynamics (DPD) simulations were employed to study the microstructures of an emulsion with alternating copolymers as the emulsifier. To model the alternating copolymers, an angular force was introduced by determining the stiffness parameters based on a linear quantitative structure-property relationship model. We studied the kinetics of emulsion formation by analyzing the time evolution of pressure, temperature, droplet number, the mean end-to-end distance and the morphologies of the emulsified oil droplets. The effect of emulsifier concentration on the mesostructures of the emulsified oil droplets was also discussed and the simulation results can interpret the experimental results on the microscopic level. Accordingly, the DPD method is a powerful tool for investigating emulsions with alternating copolymers and may be extended to drug delivery systems containing these copolymers.


Guan Q.,South China University of Technology | Yu F.R.,Carleton University | Jiang S.,South China University of Technology | Leung V.C.M.,University of British Columbia
IEEE Transactions on Wireless Communications | Year: 2011

Cooperative communications can significantly enhance transmission reliability and bandwidth efficiency in wireless networks. However, many upper layer aspects of cooperative communications merit further research. In this paper, we investigate its impacts on network topology and network capacity, which is determined by considerable aspects, such as physical layer capacity, interference, path length, etc. Since cooperative communications enhance physical layer capacity and relay selection impacts network topology directly, we present a Capacity-Optimized COoperative (COCO) topology control scheme for mobile ad hoc networks (MANETs) with cooperative communications. We consider both upper layer network capacity and physical layer relay selections in the proposed scheme. In addition, only the channel estimate, not the perfect channel status, is assumed to be known in our scheme. The topology control problem in MANETs is then formulated as a discrete stochastic optimization problem, which can be solved using a stochastic approximation approach. Further, an improved COCO is presented to reconfigure network topology to track the changing mobile environment dynamically. Simulation results are presented to show the effectiveness of the proposed scheme. © 2006 IEEE.


Zhang Z.,South China University of Technology | Shi G.,South China University of Technology | Wang S.,South China University of Technology | Fang X.,South China University of Technology | Liu X.,Guangdong Industry Technical College
Renewable Energy | Year: 2013

Here we demonstrate thermal energy storage cement mortar (TESCM) fabricated by integrating ordinary cement mortar with a composite phase change material (PCM) based on n-octadecane and expanded graphite (EG). The mass percentage of n-octadecane in the composite PCM can reach as high as 90% due to the excellent adsorption ability of EG, which endows the composite PCM with large latent heat. SEM images of the composite PCM show that n-octadecane is adsorbed into the pores of EG and uniformly covers on the nanosheets of EG, which microstructure contributes to preventing leakage of melted n-octadecane after it changes phase from solid state to liquid state. The n-octadecane/EG composite PCM has a good compatibility with ordinary cement mortar, and does not obviously deteriorate the apparent densities of the TESCM samples. Based on the thermal energy storage performance evaluation, it is found that the TESCM containing the n-octadecane/EG composite PCM plays a role in reducing the variation of indoor temperature, which helps to decrease the energy consumption for buildings. © 2012 Elsevier Ltd.


Yang S.-Q.,University of Wollongong | Liu P.-W.,South China University of Technology
Journal of Great Lakes Research | Year: 2010

Taihu Lake, the third largest freshwater lake in China, is located in the Chanjiang Delta of the Yangtze River. Its waters are used by agriculture, industry and as major drinking water for several cities including Shanghai and Wuxi. The lake also is important for tourism, aquaculture and flood control. Taihu Lake and its surrounding areas are facing three major water-related threats: deteriorating water quality with inflow and runoff from its watershed; flooding during the rainy seasons; and water shortages during drier months. Noxious algae blooms are occurring with increasing frequency and water quality continues to decline. Remedial actions implemented to date have been ineffective. This paper proposes that the problems could be remedied by constructing a by-pass channel (BPC), which would divert low-quality water from the lake during low precipitation periods and allow better quality water to flow into the lake during high flow periods. This remedial action would simultaneously deal with the deteriorating water quality of Lake Taihu and maintain its water level at a desired level. A preliminary assessment of this strategy shows that, if the BPC were implemented, the water quality of Taihu Lake would be improved significantly in few years, the flood disaster would be greatly mitigated, and the water shortage problem in the basin would be alleviated. Crown Copyright © 2009.


Ma H.,Shenzhen Polytechnic | Chan K.W.,Hong Kong Polytechnic University | Liu M.,South China University of Technology
IEEE Transactions on Industrial Informatics | Year: 2013

The intelligent control of power systems is one of the main tasks for realizing a smart grid. Because of the high-dimensional dynamics and discrete control of power systems, realizing an optimal control to support system voltages is a hard combinatorial optimization problem. In this paper, a new intelligent scheme based on a genetic learning progress for optimal voltage control is proposed. This learning control scheme combines the genetic algorithm (GA) with a memory which saves knowledge accumulated from past experiences. In each run of search by GA, past experiences in memory is exploited to speed up the searching of GA and improve the quality of the solutions while the knowledge in memory is also refined by the new solutions. With the help of this learning capability, a fast and self-healing voltage control is realized and the control performance can be improved gradually over time. A case study on the New England 39-bus power system showed that the purposed learning control can successfully prevent the system from voltage instability and at the same time a fast and adaptive system response is provided. © 2005-2012 IEEE.


Tian H.,Beijing Technology and Business University | Tian H.,South China University of Technology
Journal of Composite Materials | Year: 2012

Nanocomposite materials were prepared via glycerol plasticized soy protein as the matrix and in situ fabricated silica as thereinforcing phase. The silica nanoparticles were synthesized in the protein environment by sodium silicate as a precursor. The resulting composites were characterized by Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), tensile tests, and thermogravimetric analysis (TGA). The results revealed that silica particles were homogeneously dispersed in soy protein matrix at a nanometer scale with low silica addition (lower than 15%). Silica particles exhibited a high adhesion with protein matrix through hydrogen bonding and confined the motions of soy protein segments. The incorporation of silica as a reinforcing agent significantly improved the mechanical properties and thermal stability of soy protein plastics. © The 2011 Author(s).


Gu G.-Y.,Shanghai JiaoTong University | Zhu L.-M.,Shanghai JiaoTong University | Su C.-Y.,South China University of Technology | Su C.-Y.,Concordia University at Montréal
IEEE Transactions on Industrial Electronics | Year: 2014

This paper presents a modified Prandtl-Ishlinskii (P-I) (MPI) model for the asymmetric hysteresis description and compensation of piezoelectric actuators. Considering the fact that the classical P-I (CPI) model is only efficient for the symmetric hysteresis description, the MPI model is proposed to describe the asymmetric hysteresis nonlinearity of piezoceramic actuators (PCAs). Different from the commonly used approach for the development of asymmetric P-I models by replacing the classical play operator with complex nonlinear operators, the proposed MPI model still utilizes the classical play operator as the elementary operator, while a generalized input function is introduced to replace the linear input function in the CPI model. By this way, the developed MPI model has a relative simple mathematic format with fewer parameters to characterize the asymmetric hysteresis behavior of PCAs. The benefit for the developed MPI model also lies in the fact that an analytic inverse model of the CPI model can be directly applied for the inverse compensation of the asymmetric hysteresis nonlinearity represented by the developed MPI model in real-time applications. To validate the developed MPI model and the inverse hysteresis compensator, simulation, and experimental results on a piezoceramic actuated platform are presented. © 1982-2012 IEEE.


Shen M.,University of Texas at Austin | Shen M.,University of Illinois at Urbana - Champaign | Zhu X.-H.,South China University of Technology | Bard A.J.,University of Texas at Austin
Journal of the American Chemical Society | Year: 2013

We report here the electrochemistry, spectroscopy, and electrogenerated chemiluminescence (ECL) from a solution, film, and nanoparticles (NPs) of a red-emitting dithienylbenzothiadiazole molecular fluorophore [4,7-bis(4-(n-hexyl)-5-(3,5-di(1-naphthyl)phenyl)thiophen-2-yl)-2,1, 3-benzothiadiazole, 1a], which has a donor-acceptor-donor configuration. In addition, the quenching of the fluorescence of the organic NPs by KI was investigated. The 1a film and NPs exhibit two absorbance peaks at 350 and ∼504 nm that are red-shifted compared to those of 1a dissolved in solution (340 and 486 nm). Fluorescence quenching of 1a NPs does not follow a linear Stern-Volmer relationship; i.e., the fluorescence emission with excitation wavelength at either 350 or 504 nm decreased with increasing concentration of KI. Static quenching and heterogeneity related to the size distribution of the 1a NPs are proposed to explain the nonlinearity. A lifetime of 4.49 ± 0.04 ns was found for 1a organic NPs in water saturated with N2. After addition of KI, the fluorescence lifetime decreased to 3.1 ns. The fluorescence emission of 1a film/NPs is red-shifted (∼17 nm) compared with that of 1a solution in dichloromethane (DCM). Solution ECL was generated in DCM through an annihilation reaction, while film and NP ECL could be generated in water through oxidation with a coreactant, tri-n-propylamine (TPrA). A film of 1a with thickness of 100-900 nm was prepared by drop-casting 1a in DCM on fluorine-doped tin oxide, and the ECL of the 1a film was found in phosphate-buffered saline solution with TPrA. Both 1a in solution and the 1a film produce strong ECL (Ifilm = 0.14Isolution). The ECL spectrum of 1a in solution, produced by electron-transfer annihilation of the reduced and oxidized forms, consists of a single peak with maximum emission at about 637 ± 4 nm, ∼20 nm red-shifted from its fluorescence, while the ECL spectrum of 1a film produced by reaction with TPrA consists of a single peak with maximum emission at 642 ± 3 nm, a 10 nm red shift compared with the fluorescence of 1a film. Organic fluorescent 1a NPs were prepared by a reprecipitation method in water saturated with N2, and they were characterized by transmission electron microscopy, absorbance, fluorescence, and ECL. Strong ECL was also generated from the organic NPs in water by reduction with K2S2O8 coreactant. © 2013 American Chemical Society.


Leung C.W.T.,Hong Kong University of Science and Technology | Hong Y.,Hong Kong University of Science and Technology | Chen S.,Hong Kong University of Science and Technology | Zhao E.,Hong Kong University of Science and Technology | And 3 more authors.
Journal of the American Chemical Society | Year: 2013

Tracking the dynamics of mitochondrial morphology has attracted much research interest because of its involvement in early stage apoptosis and degenerative conditions. To follow this process, highly specific and photostable fluorescent probes are in demand. Commercially available mitochondria trackers, however, suffer from poor photostability. To overcome this limitation, we have designed and synthesized a fluorescent agent, tetraphenylethene- triphenylphosphonium (TPE-TPP), for mitochondrial imaging. Inherent from the mitochondrial-targeting ability of TPP groups and the aggregation-induced emission (AIE) characteristics of the TPE core, TPE-TPP possesses high specificity to mitochondria, superior photostability, and appreciable tolerance to environmental change, allowing imaging and tracking of the mitochondrial morphological changes in a long period of time. © 2012 American Chemical Society.


Wang T.,South China University of Technology | Lin B.,Minjiang University | Lin B.,Xiamen University
Renewable and Sustainable Energy Reviews | Year: 2014

China has become a net importer of natural gas as a result of rapidly increasing consumption in recent years. A production peak would exist since natural gas is an exhaustible resource. As conventional natural gas production peak approaches, the development of unconventional natural gas is attracting increasing attention. China's unconventional natural gas reserves are abundant, but exploration is still in its infancy stage. Thus, with the increasing quest for low-carbon development and China's natural gas price reform, studying the impacts of unconventional gas development on China's natural gas supply and price reform under different scenarios has practical significance. In this paper we predict China's natural gas production trends in different scenarios and forecast natural gas demand. This paper concludes that the exploitation of unconventional natural gas will greatly improve China's annual natural gas production, and delay the production peak year. This is important for China's natural gas supply security as it can decrease dependence on imported gas. Furthermore, as the cleanest fossil fuel, it will enable more time and space for renewable energy development given the many costs and controversies surrounding its development in China. © 2014 Elsevier Ltd.


Pan B.,Beihang University | Yu L.,Beihang University | Wu D.,Beihang University | Tang L.,South China University of Technology
Optics and Lasers in Engineering | Year: 2013

Lens distortion practically presents in a real optical imaging system causing non-uniform geometric distortion in the recorded images, and gives rise to additional errors in the displacement and strain results measured by two-dimensional digital image correlation (2D-DIC). In this work, the systematic errors in the displacement and strain results measured by 2D-DIC due to lens distortion are investigated theoretically using the radial lens distortion model and experimentally through easy-to-implement rigid body, in-plane translation tests. Theoretical analysis shows that the displacement and strain errors at an interrogated image point are not only in linear proportion to the distortion coefficient of the camera lens used, but also depend on its distance relative to distortion center and its magnitude of displacement. To eliminate the systematic errors caused by lens distortion, a simple linear least-squares algorithm is proposed to estimate the distortion coefficient from the distorted displacement results of rigid body, in-plane translation tests, which can be used to correct the distorted displacement fields to obtain unbiased displacement and strain fields. Experimental results verify the correctness of the theoretical derivation and the effectiveness of the proposed lens distortion correction method. © 2012 Elsevier Ltd. All rights reserved.


Xue-Tao X.,HKUST Fok Ying Tung Graduate School | Kai-Yi L.,University of Maine, France | Jia-Ying Z.,South China University of Technology
Biosensors and Bioelectronics | Year: 2015

A portable and sensitive quantitative DNA detection method based on personal glucose meters and isothermal circular strand-displacement polymerization reaction was developed. The target DNA triggered target recycling process, which opened capture DNA. The released target then found another capture DNA to trigger another polymerization cycle, which was repeated for many rounds, resulting in the multiplication of the DNA-invertase conjugation on the surface of Streptavidin-MNBs. The DNA-invertase was used to catalyze the hydrolysis of sucrose into glucose for PGM readout. There was a liner relationship between the signal of PGM and the concentration of target DNA in the range of 5.0 to 1000. fM, which is lower than some DNA detection method. In addition, the method exhibited excellent sequence selectivity and there was almost no effect of biological complex to the detection performance, which suggested our method can be successfully applied to DNA detection in real biological samples. © 2014 Elsevier B.V.


Zhao Z.,Hangzhou Normal University | Lam J.W.Y.,Hong Kong University of Science and Technology | Tang B.Z.,Hong Kong University of Science and Technology | Tang B.Z.,South China University of Technology
Soft Matter | Year: 2013

Fluorescent self-assembled organogels are interesting supramolecular soft materials with polymer-like structures and have received particular attention due to their fascinating properties and promising practical applications. However, most planar π-conjugated gelators are highly emissive in the solution state but become weak emitters when self-assembled. Recently, a novel phenomenon of aggregation-induced emission (AIE) has drawn increasing research interest and has been the subject of numerous investigations. This intriguing finding paves a new way for creating fluorescent organogels by utilizing gelators with AIE characteristics. This review focuses on the recent advances in fluorescent organogels with gelation-enhanced emission features. Various kinds of low molecular weight gelators consisting of typical AIE luminogens, conventional planar chromophores, and photoactive molecules are introduced and the mechanisms for the emission enhancement are discussed. This journal is © 2013 The Royal Society of Chemistry.


Chen Q.,Nanjing Southeast University | Huang S.,South China University of Technology
Materials Letters | Year: 2013

In this letter, inspired by multiscale structures of natural tissues, we propose a porous bioscaffold with structural hierarchy to optimize tissue regeneration. By describing its geometric model and performing mechanical analysis, Young's modulus and strength of the scaffold, which can be formulated with given parameters of the bottom level, are derived by an iterative method. Theoretical predictions on the two mechanical parameters by the present method are compared with others by the homogenization theory and power law; the comparison shows that they agree very well. The porous scaffold could be applied in future tissue engineering as a new biomaterial. © 2012 Elsevier B.V.


Lai C.-F.,National Ilan University | Chao H.-C.,National Ilan University | Lai Y.-X.,National Cheng Kung University | Wan J.,South China University of Technology
IEEE Wireless Communications | Year: 2013

With the increasing trend for hand-held devices, such as the intelligent mobile phone and tablet PC, users have an increasing demand for network media streaming service. However, in the course of streaming media, the unstable network bandwidth often causes frozen play or delay to degrade user experience. A cloudassisted real-time transcoding mechanism is proposed in this paper, which contains HTTP live streaming protocol, a coding mode transition state machine, and three bandwidth evaluations of error patterns. In the proposed mechanism, the variance in current network is able to be observed according to the bandwidth evaluation results; if different transcoding strategies are used in different modes, the appropriate media segment bit rate is able to be calculated, which is transcoded into the segment to meet the current bandwidth conditions, it makes the users can obtain appropriate media quality automatically through the HTTP redirection technique. Using cloud computing the user will take different transrating media clips into different transrators according to the users' needs, using this technology to increase the transrating efficiency to achieve real-time transrating. Finally, the peak signal-to-noise ratio (PSNR) and bandwidth utilization rate are analyzed as the reference index of improvement in media quality. According to the experimental results, the PSNR can be increased by about 2.8 dB in general network behavior, and the bandwidth utilization rate can be maintained above 80 percent during streaming. © 2013 IEEE.


Xue S.,Jilin University | Yao L.,Jilin University | Shen F.,Jilin University | Gu C.,Jilin University | And 2 more authors.
Advanced Functional Materials | Year: 2012

Highly efficient and fully solution-processed white organic light-emitting diodes (WOLEDs) based on fluorescent small molecules and a polar conjugated polymer as electron-injection material are reported. The emitting layer in the WOLEDs is a blend of new blue-, green-, and red-fluorescent small molecules, with a blending ratio of 100:0.4:0.8 (B/G/R) by weight, and a methanol/water soluble conjugated polymerpoly[(9,9-bis(30-(N,N-dimethylamino)propyl)-2,7- fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFN) acts as the electron-injection layer (EIL). All the organic layers are spin-coated from solution. The device exhibits pure white emission with a maximum luminous efficiency of 9.2 cd A -1 and Commission Internationale d'Eclairage Coordinates of (0.35, 0.36). PFN acting as the EIL material plays a key role in the improvement of the device performance when used in solution-processed small-molecule WOLEDs. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Nai S.E.,Institute for Infocomm Research | Ser W.,Nanyang Technological University | Yu Z.L.,South China University of Technology | Chen H.,Nanjing University of Aeronautics and Astronautics
IEEE Transactions on Signal Processing | Year: 2011

Based on worst-case performance optimization, the recently developed adaptive beamformers utilize the uncertainty set of the desired array steering vector to achieve robustness against steering vector mismatches. In the presence of large steering vector mismatches, the uncertainty set has to expand to accommodate the increased error. This degrades the output signal-to- interference-plus-noise ratios (SINRs) of these beamformers since their interference-plus-noise suppression abilities are weakened. In this paper, an iterative robust minimum variance beamformer (IRMVB) is proposed which uses a small uncertainty sphere (and a small flat ellipsoid) to search for the desired array steering vector iteratively. This preserves the interference-plus-noise suppression ability of the proposed beamformer and results in a higher output SINR. Theoretical analysis and simulation results are presented to show the effectiveness of the proposed beamformer. © 2010 IEEE.


Liu Z.,South China University of Technology | Wen F.,Queensland University of Technology | Ledwich G.,Queensland University of Technology
IEEE Transactions on Power Delivery | Year: 2011

Some uncertainties, such as the uncertain output power of a plug-in electric vehicle (PEV) due to its stochastic charging and discharging schedule, that of a wind generation unit due to the stochastic wind speed, and that of a solar generating source due to the stochastic illumination intensity, volatile fuel prices, and future uncertain load growth could lead to some risks in determining the optimal siting and sizing of distributed generators (DGs) in distribution system planning. Given this background, under the chance constrained programming (CCP) framework, a new method is presented to handle these uncertainties in the optimal siting and sizing of DGs. First, a mathematical model of CCP is developed with the minimization of the DGs' investment cost, operating cost, maintenance cost, network loss cost, as well as the capacity adequacy cost as the objective, security limitations as constraints, and the siting and sizing of DGs as optimization variables. Then, a Monte Carlo simulation-embedded genetic-algorithm-based approach is employed to solve the developed CCP model. Finally, the IEEE 37-node test feeder is used to verify the feasibility and effectiveness of the developed model and method, and the test results have demonstrated that the voltage profile and power-supply reliability for customers can be significantly improved and the network loss substantially reduced. © 2011 IEEE.


Li X.,South China University of Technology | Liu Q.,South China University of Technology | Yu Y.,South China University of Technology | Meng Y.,Sun Yat Sen University
Journal of Materials Chemistry A | Year: 2013

A series of hydroxide ion conductive poly(arylene ether) ionomers containing functionalized triphenyl methane groups and various backbones were prepared via polycondensation, chloromethylation, quaternization, and subsequent alkalization reaction. The structures of the poly(arylene ether)s (PAEs), chloromethylated poly(arylene ether)s (CMPAEs) and quaternized ammonium-substituted poly(arylene ether)s (QPAEs) were confirmed using 1H NMR and FT-IR techniques. Thermal stabilities of the PAEs, CMPAEs and QPAEs were evaluated by thermal gravimetric analysis (TGA). The water uptakes, swelling ratios, ion exchange capacities (IECs), hydroxide conductivities and chemical stabilities of the membranes derived from the synthesized ionomers were assessed as anion exchange membranes. The IEC of the ionomers ranged from 0.57 to 2.59 mmol g-1, which can be controlled by chloromethylation reaction conditions. The hydroxide conductivities of the QPAE membranes increase dramatically with increasing temperature. The QPAE-a membrane with an IEC value of 2.59 mmol g-1 displayed the highest hydroxide conductivities of 14.9 and 84.6 mS cm-1 at 20 °C and 80 °C, respectively. The hydroxide transport activation energy for the QPAE membranes ranged from 18.07 to 24.07 kJ mol-1. The first degradation temperatures of the QPAE membranes were around 185 °C. The tensile strength varied from 18 to 41 MPa at 25 °C. The QPAE membrane retained 86% of its mechanical properties and 83% of its hydroxide conductivity after being conditioned with 1 M NaOH at 60 °C for 120 h. In particular, QPAE-a retains 87% of its original IEC under very harsh conditions of 6 M NaOH at 60 °C for 168 h. These properties of the ionomer membranes demonstrate their potential as anion exchange membranes for alkaline fuel cells. © The Royal Society of Chemistry 2013.


Peng L.,South China University of Technology | Lin L.,Xiamen University | Li H.,South China University of Technology
Industrial Crops and Products | Year: 2012

A comprehensive experimental and kinetic investigation on the synthesis of methyl levulinate from glucose in methanol medium under mild conditions (≤473K) catalyzed by extremely low sulfuric acid (≤0.01molL-1) was performed in this study. Glucose was rapidly and almost quantitatively converted into methyl glucosides as a key and stable intermediate product, and a high methyl levulinate yield of ca. 50mol% can be achieved after the completion of reaction. Based on the detected compounds, a plausible reaction pathway for the acid-catalyzed conversion of glucose in methanol medium was proposed. The generation of methyl levulinate from glucose via methyl glucosides as a function of the process variables was modelled using a simplified first-order kinetic model, and a good fit between experimental data and the kinetic model was obtained. An advantage of this catalyst system is that negligible undesired dimethyl ether formed from the side reaction for the dehydration of methanol that was used as reaction medium, the equipment corrosion was slight, and less spent acid need to be addressed after the reaction. Overall, this catalytic strategy is efficient, economical and environmentally benign for the conversion of carbohydrates into high value-added chemicals and fuels. © 2012 Elsevier B.V.


Li M.,CAS Shanghai Institutes for Biological Sciences | Zeng T.,CAS Shanghai Institutes for Biological Sciences | Liu R.,South China University of Technology | Chen L.,CAS Shanghai Institutes for Biological Sciences
Briefings in Bioinformatics | Year: 2014

Identifying early warning signals of critical transitions during disease progression is a key to achieving early diagnosis of complex diseases. By exploiting rich information of high-throughput data, a novel model-free method has been developed to detect early warning signals of diseases. Its theoretical foundation is based on dynamical network biomarker (DNB), which is also called as the driver (or leading) network of the disease because components or molecules in DNB actually drive the whole system from one state (e.g. normal state) to another (e.g. disease state). In this article, we first reviewed the concept and main results of DNB theory, and then applied the new method to the analysis of type 2 diabetes mellitus (T2DM). Specifically, based on the temporal-spatial gene expression data of T2DM, we identified tissue-specific DNBs corresponding to the critical transitions occurring in liver, adipose and muscle duringT2DM development and progression. Actually, we found that there are two different critical states during T2DM development characterized as responses to insulin resistance and serious inflammation, respectively. Interestingly, a new T2DM-associated function, i.e. steroid hormone biosynthesis, was discovered, and those related genes were significantly dysregulated in liver and adipose at the first critical transition during T2DM deterioration. Moreover, the dysfunction of genes related to responding hormone was also detected in muscle at the similar period. Based on the functional and network analysis on pathogenic molecular mechanism of T2DM, we showed that most of DNB genes, in particular the core ones, tended to be located at the upstream of biological pathways, which implied that DNB genes act as the causal factors rather than the consequence to drive the downstream molecules to change their transcriptional activities. This also validated our theoretical prediction of DNB as the driver network. As shown in this study, DNB can not only signal the emergence of the critical transitions for early diagnosis of diseases, but can also provide the causal network of the transitions for revealing molecular mechanisms of disease initiation and progression at a network level. © The Author 2013. Published by Oxford University Press.


Mei S.-W.,Tsinghua University | Zhu J.-Q.,South China University of Technology
Zidonghua Xuebao/Acta Automatica Sinica | Year: 2013

Taking into account the connotation and engineering demand of smart grid, this paper summarizes and extracts several basic scientific issues of smart grid during its construction and development process, including prediction, energy storage, control, dispatching, planning, assessment, and their common engineering game theory. These basic scientific issues respectively belong to the mathematics, control science or their cross discipline. The solution of these issues not only is the precondition of the realization of smart grid, but also can promote the application perspective of mathematics and control science. Thus, it possesses a significant value in the theory and engineering research. Copyright © 2013 Acta Automatica Sinica. All rights reserved.


Wang X.,Cornell University | Wang X.,South China University of Technology | Yun J.-W.,Cornell University | Lei X.G.,Cornell University
Antioxidants and Redox Signaling | Year: 2014

Aims: Glutathione peroxidase (GPX) mimic ebselen and superoxide dismutase (SOD) mimic copper diisopropylsalicylate (CuDIPs) were used to rescue impaired glucose-stimulated insulin secretion (GSIS) in islets of GPX1 and(or) SOD1-knockout mice. Results: Ebselen improved GSIS in islets of all four tested genotypes. The rescue in the GPX1 knockout resulted from a coordinated transcriptional regulation of four key GSIS regulators and was mediated by the peroxisome proliferator-Activated receptor gamma coactivator 1 alpha (PGC-1α)-mediated signaling pathways. In contrast, CuDIPs improved GSIS only in the SOD1 knockout and suppressed gene expression of the PGC-1α pathway. Innovation: Islets from the GPX1 and(or) SOD1 knockout mice provided metabolically controlled intracellular hydrogen peroxide (H2O 2) and superoxide conditions for the present study to avoid confounding effects. Bioinformatics analyses of gene promoters and expression profiles guided the search for upstream signaling pathways to link the ebselen-initiated H2O2 scavenging to downstream key events of GSIS. The RNA interference was applied to prove PGC-1α as the main mediator for that link. Conclusion: Our study revealed a novel metabolic use and clinical potential of ebselen in rescuing GSIS in the GPX1-deficient islets and mice, along with distinct differences between the GPX and SOD mimics in this regard. These findings highlight the necessities and opportunities of discretional applications of various antioxidant enzyme mimics in treating insulin secretion disorders. Rebound Track: This work was rejected during standard peer review and rescued by Rebound Peer Review (Antioxid Redox Signal 16: 293-296, 2012) with the following serving as open reviewers: Regina Brigelius-Flohe, Vadim Gladyshev, Dexing Hou, and Holger Steinbrenner. Antioxid. Redox Signal. 20, 191-203. © Copyright 2014, Mary Ann Liebert, Inc. 2014.


Wang X.,South China University of Technology | Wang X.,Cornell University | Lei X.G.,Cornell University | Wang J.,South China University of Technology
Molecular and Cellular Endocrinology | Year: 2014

Evidence showed strong relations between malondialdehyde (MDA) levels and different pathological stages of diabetes. Here, an explicit system with freshly isolated islets and precisely controlled MDA gradient was employed to investigate the physiological effect of MDA on GSIS. Promoter analysis, pathway mapping, Q-PCR profiling, and siRNA verification were performed to clarify the intracellular signaling pathways. MDA at a moderately high level (5 and 10μM) promoted GSIS and accompanied with ATP/ADP ratio, cytosolic Ca2+ level, and key regulators (GK, GLUT2, PDX1, and UCP2) changes in islets. Both upstream (PI3K and p-AKT) and downstream (TCF7L2 and TCF7) factors of Wnt pathway showed greatest changes. Knockdown of TCF7L2 blocked the MDA-induced GSIS elevation. These results indicated that MDA acted as a signaling messenger and regulated islet GSIS mainly through Wnt pathway. Therefore, the elevated MDA level and up-regulated Wnt signaling pathway could be an etiological factor in the development of hyperinsulinemia and type 2 diabetes. © 2013.


Gan L.-Y.,King Abdullah University of Science and Technology | Zhao Y.-J.,South China University of Technology | Huang D.,University of Science and Arts of Iran | Schwingenschlogl U.,King Abdullah University of Science and Technology
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

First-principles calculations are used to explore the geometry, bonding, and electronic properties of MoS2/Ti2C and MoS 2/Ti2CY2 (Y = F and OH) semiconductor/metal contacts. The structure of the interfaces is determined. Strong chemical bonds formed at the MoS2/Ti2C interface result in additional states next to the Fermi level, which extend over the three atomic layers of MoS2 and induce a metallic character. The interaction in MoS 2/Ti2CY2, on the other hand, is weak and not sensitive to the specific geometry, and the semiconducting nature thus is preserved. The energy level alignment implies weak and strong n-type doping of MoS2 in MoS2/Ti2CF2 and MoS 2/Ti2C(OH)2, respectively. The corresponding n-type Schottky barrier heights are 0.85 and 0.26 eV. We show that the MoS 2/Ti2CF2 interface is close to the Schottky limit. At the MoS2/Ti2C(OH)2 interface, we find that a strong dipole due to charge rearrangement induces the Schottky barrier. The present interfaces are well suited for application in all-two-dimensional devices. © 2013 American Physical Society.


Cai W.,South China University of Technology | Lai T.,South China University of Technology | Du H.,Guizhou University | Ye J.,South China University of Technology
Sensors and Actuators, B: Chemical | Year: 2014

An exfoliated flexible graphite paper (e-FGP) with rough edges is proposed as a high performance working electrode for the electrochemical determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA). Scanning electron microscopy (SEM), cyclic voltammetry (CV), different pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) were applied to investigate the unique properties of the high performance electrode. The results demonstrate its excellent electrocatalytic activity toward the oxidation of AA, DA and UA with well-separated voltammetric peaks. The calibration curves in the range of 20-400 μM, 0.5-35 μM, 0.5-35 μM, and the detection limits (S/N = 3) of 2.0 μM, 0.01 μM, 0.02 μM were obtained for AA, DA and UA in neutral phosphate buffer solutions (PBS), respectively. This mechanically flexible sensor with good selectivity and remarkable sensitivity could be used to determine DA and UA in real human urine samples. © 2013 Elsevier B.V.


Liu H.,South China University of Technology | Liu H.,Guangdong Ocean University | Zhang T.,South China University of Technology
Robotics and Computer-Integrated Manufacturing | Year: 2013

A novel neural network-based robust finite-time control strategy is proposed for the trajectory tracking of robotic manipulators with structured and unstructured uncertainties, in which the actuator dynamics is fully considered. The controller, which possesses finite-time convergence and strong robustness, consists of two parts, namely a neural network for approximating the nonlinear uncertainty function and a modified variable structure term for eliminating the approximate error and guaranteeing the finite-time convergence. According to the analysis based on the Lyapunov theory and the relative finite-time stability theory, the neural network is asymptotically convergent and the controlled robotic system is finite time stable. The proposed controller is then verified on a two-link robotic manipulator by simulations and experiments, with satisfactory control performance being obtained even in the presence of various uncertainties and external disturbances. © 2012 Elsevier Ltd. All rights reserved.


Liu Z.,South China University of Technology | Wen F.,Zhejiang University | Wen F.,Queensland University of Technology | Ledwich G.,Queensland University of Technology
IEEE Transactions on Power Delivery | Year: 2013

With the progressive exhaustion of fossil energy and the enhanced awareness of environmental protection, more attention is being paid to electric vehicles (EVs). Inappropriate siting and sizing of EV charging stations could have negative effects on the development of EVs, the layout of the city traffic network, and the convenience of EVs' drivers, and lead to an increase in network losses and a degradation in voltage profiles at some nodes. Given this background, the optimal sites of EV charging stations are first identified by a two-step screening method with environmental factors and service radius of EV charging stations considered. Then, a mathematical model for the optimal sizing of EV charging stations is developed with the minimization of total cost associated with EV charging stations to be planned as the objective function and solved by a modified primal-dual interior point algorithm (MPDIPA). Finally, simulation results of the IEEE 123-node test feeder have demonstrated that the developed model and method cannot only attain the reasonable planning scheme of EV charging stations, but also reduce the network loss and improve the voltage profile. © 1986-2012 IEEE.


Xiong F.,CAS Chengdu Institute of Biology | Qian C.,South China University of Technology | Lin D.,South China University of Technology | Zeng W.,South China University of Technology | Lu X.,CAS Chengdu Institute of Biology
Organic Letters | Year: 2013

A Pd-catalyzed cascade oxidation/sp2 C-H bond acylation of azoarenes was developed in which readily available aryl methanes were used as the in situ generated acyl sources. This reaction provides a convenient access to ortho-acyl azoarenes under mild conditions. © 2013 American Chemical Society.


Deng Y.,CAS Institute of Theoretical Physics | Deng Y.,Henan Normal University | Cheng J.,South China University of Technology | Jing H.,Henan Normal University | And 2 more authors.
Physical Review Letters | Year: 2012

We propose an experimental scheme to create spin-orbit coupling in spin-3 Cr atoms using Raman processes. By employing the linear Zeeman effect and optical Stark shift, two spin states within the ground electronic manifold are selected, which results in a pseudospin-1/2 model. We further study the ground state structures of a spin-orbit-coupled Cr condensate. We show that, in addition to the stripe structures induced by the spin-orbit coupling, the magnetic dipole-dipole interaction gives rise to the vortex phase, in which a spontaneous spin vortex is formed. © 2012 American Physical Society.


Yang X.,South China University of Technology | Yang X.,University of Technology, Sydney | Zhang G.,University of Technology, Sydney | Lu J.,University of Technology, Sydney | Ma J.,University of Technology, Sydney
IEEE Transactions on Fuzzy Systems | Year: 2011

The support vector machine (SVM) has provided higher performance than traditional learning machines and has been widely applied in real-world classification problems and nonlinear function estimation problems. Unfortunately, the training process of the SVM is sensitive to the outliers or noises in the training set. In this paper, a common misunderstanding of Gaussian-function-based kernel fuzzy clustering is corrected, and a kernel fuzzy c-means clustering-based fuzzy SVM algorithm (KFCM-FSVM) is developed to deal with the classification problems with outliers or noises. In the KFCM-FSVM algorithm, we first use the FCM clustering to cluster each of two classes from the training set in the high-dimensional feature space. The farthest pair of clusters, where one cluster comes from the positive class and the other from the negative class, is then searched and forms one new training set with membership degrees. Finally, we adopt FSVM to induce the final classification results on this new training set. The computational complexity of the KFCM-FSVM algorithm is analyzed. A set of experiments is conducted on six benchmarking datasets and four artificial datasets for testing the generalization performance of the KFCM-FSVM algorithm. The results indicate that the KFCM-FSVM algorithm is robust for classification problems with outliers or noises. © 2006 IEEE.


Wang M.,South China University of Technology | Liu X.,Lakehead University | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2011

This paper is concerned with robust stabilization problem for a class of nonaffine pure-feedback systems with unknown time-delay functions and perturbed uncertainties. Novel continuous packaged functions are introduced in advance to remove unknown nonlinear terms deduced from perturbed uncertainties and unknown time-delay functions, which avoids the functions with control law to be approximated by radial basis function (RBF) neural networks. This technique combining implicit function and mean value theorems overcomes the difficulty in controlling the nonaffine pure-feedback systems. Dynamic surface control (DSC) is used to avoid the explosion of complexity in the backstepping design. Design difficulties from unknown time-delay functions are overcome using the function separation technique, the Lyapunov-Krasovskii functionals, and the desirable property of hyperbolic tangent functions. RBF neural networks are employed to approximate desired virtual controls and desired practical control. Under the proposed adaptive neural DSC, the number of adaptive parameters required is reduced significantly, and semiglobal uniform ultimate boundedness of all of the signals in the closed-loop system is guaranteed. Simulation studies are given to demonstrate the effectiveness of the proposed design scheme. © 2006 IEEE.


Hou Z.,South China University of Technology | Assouar B.M.,CNRS Jean Lamour Institute
Applied Physics Letters | Year: 2015

We report in this letter on a tunable solid acoustic metamaterial with negative elastic modulus by means of piezoelectric composite. The theoretical formulae for one-dimensional layer-stacked metamaterial embedding a piezoelectric material by means of external shunted inductors are presented. The acoustic band structure of the composite is calculated by the transfer matrix method. Results show that a band gap can be opened and tuned by the resonant behavior of the LC circuit. It is found further by the formulae that piezoelectric material with large piezoelectric constant and small elastic modulus will be beneficial for opening a wide band gap. The effective elastic constant of the system is also calculated by the unit-cell-boundary-averaging method. Result shows that the system behaves as an effective medium with a negative elastic modulus. This property is quite different from the typical solid metamaterial achieved by dispersing heavy inclusions coated with a soft layer into a matrix for which only the negative mass density can be obtained. © 2015 AIP Publishing LLC.


Oudich M.,CNRS Jean Lamour Institute | Assouar M.B.,CNRS Jean Lamour Institute | Hou Z.,South China University of Technology
Applied Physics Letters | Year: 2010

We demonstrate the waveguiding of Lamb waves in a locally resonant phononic crystal (LRPC) and we present an analysis of the guiding of elastic waves in straight and bent waveguides. The finite element method combined with the supercell technique was used to analyze the band gap and the dispersion relation of LRPC waveguides. Unlike the traditional phononic crystals, we show the possibility of guiding only one confined mode inside a LRPC waveguide. We discuss the confinement and the transmission of the guided mode as a function of the width of the waveguide based on both the band structure and the displacement field. © 2010 American Institute of Physics.


You L.,South China University of Technology | Zhao M.,South China University of Technology | Regenstein J.M.,Cornell University | Ren J.,South China University of Technology
Food Chemistry | Year: 2010

A two-stage in vitro digestion model system (a pepsin treatment for 2 h followed by a pancreatin treatment for 2 h, both at 37 °C) was used to simulate the process of human gastrointestinal (GI) digestion to determine the changes in antioxidant activities of loach peptide previously prepared by papain digestion. Results showed that the final GI digests contained 38.1% free amino acids, with short chain peptides (<500 Da) making up the rest of the biomass. Enzymatic breakdown of the GI digests increased their hydroxyl (12% increase), 2,2′-azinobis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) (5% increase) radical scavenging activity, the reducing power (77% increase) and the chelating ability of Cu2+ (12% increase), compared to the blank. The results showed that the digestion by gastrointestinal proteases can be used to produce antioxidant peptides, with the advantage that the peptides formed will resist physiological digestion in GI tract. © 2009 Elsevier Ltd. All rights reserved.


Pan Y.,South China University of Technology | Yuan B.,South China University of Technology | Li Y.,South China University of Technology | He D.,Tsinghua University
Chemical Communications | Year: 2010

Palladium nanoparticles deposited on a chromium terephthalate MIL-101 is a highly efficient multifunctional catalyst for the one-step synthesis of methyl isobutyl ketone, with significantly higher activity than palladium on traditional materials, such as metal oxides and zeolites. © 2010 The Royal Society of Chemistry.


Li X.,South China University of Technology | Yu Y.,South China University of Technology | Liu Q.,South China University of Technology | Meng Y.,Sun Yat Sen University
ACS Applied Materials and Interfaces | Year: 2012

A series of anion conductive aromatic ionomers, poly(arylene ether)s containing various polymer backbones and quaternary ammonium basic group functioned tetraphenyl methane moieties, were synthesized via nucleophilic substitution polycondensation, chloromethylation, quaternization, and the subsequent alkalization reactions. The structures of poly(arylene ether)s (PAEs), chloromethylated poly(arylene ether)s (CMPAEs), and quaternizated poly(arylene ether)s (QPAEs) ionomers were confirmed by 1H NMR technique. Their thermal stabilities were evaluated by thermo gravimetric analysis (TGA). The water uptakes, ion exchange capacities (IEC), hydroxide ion conductivities, mechanical properties, and chemical stabilities of the membranes derived from the synthesized ionomers were assessed as anion exchange membranes. The QPAEs membranes were tough and thermally stable up to 170 °C. The IEC of the ionomers varied from 0.21 to 2.38 meq g -1 which can be controlled by chloromethylation reaction conditions. The ion conductivities of QPAEs membranes increase dramatically with increasing temperature. The hydroxide ion transport activation energy, E a, of the QPAEs membranes varied from 13.18 to 42.30 kJ mol -1. The QPAE-d membrane with lower IEC value of 1.04 meq g -1, derived from copolymer CMPAE-d bearing sulfone/ketone structure, displayed the highest hydroxide ion conductivity of 75 mS cm -1 at 80 °C and showed strong tensile strength (29.2 MPa) at 25 °C. The QPAE-e membrane with IEC value of 1.09 meq g -1, derived from copolymer CMPAE-e bearing sulfone/ketone-ketone structure, demonstrated 68 mS cm -1 at 80 °C. The QPAE-d membrane kept 90% of mechanical properties and 82% of hydroxide ion conductivity after being conditioned with 1 M NaOH at 60 °C for 170 h. These properties of the ionomers membranes show their potential as an anion exchange membrane of alkaline fuel cells. © 2012 American Chemical Society.


Yu J.,Hangzhou Dianzi University | Tao D.,South China University of Technology | Li J.,Xiamen University | Cheng J.,CAS Shenzhen Institutes of Advanced Technology | Cheng J.,Chinese University of Hong Kong
Information Sciences | Year: 2014

How do we accurately browse a large set of images or efficiently annotate the images from an image library? Image clustering methods are invaluable tools for applications such as content-based image retrieval and image annotation. To perform these tasks, it is critical to have proper features to describe the visual and semantic content of images and to define an accurate distance metric to measure the dissimilarity between any two images. However, existing methods, which adopt the features of color histograms, edge direction histograms and shape context, lack the ability to describe semantic content. To solve this problem, we propose a new approach that utilizes user-provided pairwise constraints to describe the semantic relationship between two images. A Semantic Preserving Distance Metric Learning (SP-DML) algorithm is developed to explore the complementary characteristics of the visual features and pairwise constraints in a unified feature space. In this space, the learned distance metric can be used to measure the dissimilarity between two images. Specifically, the manifold structure adopted in SP-DML is revealed by the image's visual features. To integrate semantic contents in distance metric learning, SP-DML utilizes pairwise constraints to build semantic patches and align these patches to obtain the optimal distance metric for the new feature space. Experimental results in image clustering demonstrate that the performance of SP-DML is appealing. © 2014 Elsevier Inc. All rights reserved.


Li Z.,South China University of Technology | Xia Y.,Beijing Institute of Technology | Sun F.,Tsinghua University
IEEE Transactions on Fuzzy Systems | Year: 2014

In this paper, an adaptive fuzzy control is investigated for multilateral teleoperation of two cooperating robotic manipulators that manipulate an object with constrained trajectory/force in the presence of dynamics uncertainties and random network-induced delays. First, the interconnected dynamics that consist of two master robots and cooperating slave robots are formulated. To consider multiple stochastic delays in communication channels, Markov processes are used to model these random network-induced delays. The interconnected dynamics of the teleoperation are divided into a local master/slave position/force subsystem and a stochastic-delayed motion synchronization subsystem. Then, an adaptive fuzzy control strategy, which is based on linear matrix inequalities (LMIs) that combine adaptive update techniques, is proposed to suppress the dynamics uncertainties, the external disturbances, and the multiple stochastic delays in communication channels. The control approach ensures that the defined synchronization errors converge to zero. The stochastic stability in mean square of the closed-loop system is proved using LMIs based on Lyapunov-Krasovskii functional synthesis. The proposed controls are validated using extensive simulation studies. © 1993-2012 IEEE.


Pei L.,South China University of Technology | Gao H.,Sun Yat Sen University
Journal of Molecular Catalysis A: Chemical | Year: 2011

A novel fluorinated bis(β-ketoamino) copper complex was synthesized and characterized. Norbornene polymerizations with bis(β-ketoamino) copper complexes activated with methylaluminoxane (MAO) were investigated. The highest catalytic activity up to now reported for copper based systems in norbornene polymerization was achieved using fluorinated bis(β-ketoamino) copper/MAO. The influence of precursor structure including steric and electronic effects on catalytic activity for norbornene polymerization was evaluated in detail. Bulky steric substituents and strong electron-withdrawing groups can enhance catalytic activity of precursor for norbornene polymerization through a dissociative mechanism. The influences of polymerization parameters such as polymerization temperature and Al/Cu ratio on norbornene polymerization with bis(β-ketoamino) copper catalysts were also examined. Norbornene polymerization catalyzed by bis(β-ketoamino) copper complexes/MAO proceeded on Cu(I) species through a coordination/insertion mechanism to produce vinyl-addition polynorbornene. © 2011 Elsevier B.V.


Liu R.,South China University of Technology | Wang X.,Fudan University | Aihara K.,Tokyo University of Science | Chen L.,Tokyo University of Science | Chen L.,CAS Shanghai Institutes for Biological Sciences
Medicinal Research Reviews | Year: 2014

Many studies have been carried out for early diagnosis of complex diseases by finding accurate and robust biomarkers specific to respective diseases. In particular, recent rapid advance of high-throughput technologies provides unprecedented rich information to characterize various disease genotypes and phenotypes in a global and also dynamical manner, which significantly accelerates the study of biomarkers from both theoretical and clinical perspectives. Traditionally, molecular biomarkers that distinguish disease samples from normal samples are widely adopted in clinical practices due to their ease of data measurement. However, many of them suffer from low coverage and high false-positive rates or high false-negative rates, which seriously limit their further clinical applications. To overcome those difficulties, network biomarkers (or module biomarkers) attract much attention and also achieve better performance because a network (or subnetwork) is considered to be a more robust form to characterize diseases than individual molecules. But, both molecular biomarkers and network biomarkers mainly distinguish disease samples from normal samples, and they generally cannot ensure to identify predisease samples due to their static nature, thereby lacking ability to early diagnosis. Based on nonlinear dynamical theory and complex network theory, a new concept of dynamical network biomarkers (DNBs, or a dynamical network of biomarkers) has been developed, which is different from traditional static approaches, and the DNB is able to distinguish a predisease state from normal and disease states by even a small number of samples, and therefore has great potential to achieve "real" early diagnosis of complex diseases. In this paper, we comprehensively review the recent advances and developments on molecular biomarkers, network biomarkers, and DNBs in particular, focusing on the biomarkers for early diagnosis of complex diseases considering a small number of samples and high-throughput data (or big data). Detailed comparisons of various types of biomarkers as well as their applications are also discussed. © 2013 Wiley Periodicals, Inc.


Wen Y.,Guangdong Ocean University | Jiang H.,South China University of Technology
Tetrahedron Letters | Year: 2013

An efficient procedure for the synthesis of a series of 1-bromo-1,4-dienes by a simple Pd-catalyzed intermolecular tandem reaction of alkynes, CuBr 2, and allylic alcohol has been developed. The reaction proceeds smoothly under mild condition to give the corresponding products in good to excellent yields. © 2013 The Authors. Published by Elsevier Ltd. All rights reserved.


Li X.,South China University of Technology | Yu Y.,South China University of Technology | Meng Y.,Sun Yat Sen University
ACS Applied Materials and Interfaces | Year: 2013

A series of composite anion exchange membranes based on novel quaternized poly(arylene ether sulfone)/nanozirconia (QPAES/nano-ZrO2) composites are prepared using a solution casting method. The QPAES/nano-ZrO2 composite membranes are characterized by FTIR, X-ray diffraction (XRD), and scanning electron microscopy/energy-dispersive X-ray analysis (SEM/EDX). The ion exchange capacity (IEC), water uptake, swelling ratio, hydroxide ion conductivity, mechanical properties, thermal stability, and chemical stability of the composite membranes are measured to evaluate their applicability in fuel cells. The introduction of nano-ZrO2 induces the crystallization of the matrix and enhances the IEC of the composite membranes. The modification with nano-ZrO2 improves water uptake, dimension stability, hydroxide ion conductivity, mechanical properties, and thermal and chemical stabilities of the composite membranes. The QPAES/nano-ZrO2 composite membranes show hydroxide ion conductivities over 25.7 mS cm-1 at a temperature above 60 °C. Especially, the QPAES/nano-ZrO2 composite membranes with the nano-ZrO2 content above 7.5% display hydroxide ion conductivities over 41.4 mS cm-1 at 80 °C. The Ea values of the QPAES/nano-ZrO2 composite membranes with the nano-ZrO2 content above 5% are lower than 11.05 kJ mol-1. The QPAES/7.5% nano-ZrO2 composite membrane displays the lowest Ea value and the best comprehensive properties and constitutes a good potential candidate for alkaline fuel cells. © 2013 American Chemical Society.


Xiao Q.,South China University of Technology | Chen W.,Sun Yat Sen University
Journal of Alloys and Compounds | Year: 2015

Novel NIR luminescent nanomaterial, Sr2CeO4:Nd3+ was successfully prepared with Pechini method. The Sr2CeO4:Nd3+ nanophosphors had an orthorhombic crystal structure, and showed plate-like morphology with length of about 260 nm and width of about 130 nm. Upon UV light excitation, the Sr2CeO4:Nd3+ nanophosphors exhibited strong NIR emission for the first time. The possible mechanisms of energy transfer for Nd3+ doped Sr2CeO4 were briefly analyzed. The Sr2CeO4:Nd3+ nanophosphors may be poised to be exploited in near-infrared light amplified applications or used as a high efficiency laser material based on their peculiar optical properties. © 2015 Elsevier B.V. All rights reserved.


Song Q.,Tsinghua University | Liu W.,Tsinghua University | Li X.,Tsinghua University | Rao H.,China Southern Power Grid Co. | And 3 more authors.
IEEE Transactions on Power Electronics | Year: 2013

Modular multilevel converters (MMC) are considered a top converter alternative for voltage-source converter (VSC) high-voltage, direct current (HVDC) applications. Main circuit design and converter performance evaluation are always important issues to consider before installing a VSC-HVDC system. Investigation into a steady-state analysis method for an MMC-based VSC-HVDC system is necessary. This paper finds a circular interaction among the electrical quantities in an MMC. Through this circular interaction, a key equation can be established to solve the unknown circulating current. A new steady-state model is developed to simply and accurately describe the explicit analytical expressions for various voltage and current quantities in an MMC. The accuracy of the expressions is improved by the consideration of the circulating current when deriving all the analytical expressions. The model's simplicity is demonstrated by having only one key equation to solve. Based on the analytical expressions for the arm voltages, the equivalent circuits for MMC are proposed to improve the current understanding of the operation of MMC. The feasibility and accuracy of the proposed method are verified by comparing its results with the simulation and experimental results. © 1986-2012 IEEE.


Oudich M.,CNRS Jean Lamour Institute | Li Y.,South China University of Technology | Assouar B.M.,CNRS Jean Lamour Institute | Hou Z.,South China University of Technology
New Journal of Physics | Year: 2010

Using the finite element method, we have studied the acoustic properties of a novel phononic crystal (PC) structure constructed by periodically depositing single-layer or two-layer stubs on the surface of a thin homogeneous plate. Numerical results show that the extremely low frequency band gap (BG) of the Lamb waves can be opened by the local resonance (LR) mechanism. We found that the width of such a BG depends strongly on the height and the area of cross section of the stubs. The displacement field distribution of the oscillating modes is given to explain how the coupling of the modes induces the opening of the BG. The physics behind the opening of the LRBG in our phononic structures can be understood by using a simple 'spring-mass' model. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.


You L.,South China University of Technology | Zhao M.,South China University of Technology | Regenstein J.M.,Cornell University | Ren J.,South China University of Technology
Food Chemistry | Year: 2011

The in vitro antioxidant activity and in vivo anti-fatigue activity of loach peptide (LP) were determined. Results showed that LP contained the amino acids, which were expected to contribute to its antioxidant and anti-fatigue activities. LP could scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) (IC50 17.0±0.54mg/ml) and hydroxyl radicals (IC50 2.64±0.29mg/ml). It could chelate cupric ion and inhibit the lipid peroxidation in a linoleic acid emulsion system. It also prolonged the swimming time to exhaustion of mice by 20-28% compared to the control. It increased the levels of blood glucose (28-42% increase) and liver glycogen (2.3-3.0-fold increase). It decreased the levels of lactic acid and blood urea nitrogen by 10.9-27.5% and 8.6-17.5%, respectively. It also improved the endogenous cellular antioxidant enzymes in mice by increasing the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px). Therefore, LP can increase an endurance capacity and facilitate recovery from fatigue. © 2010 Elsevier Ltd.


LEDs have inspired a new generation of electronics, but there is still work ahead if we want luminescent materials to consume less energy and have longer lifespans. Certain inorganic metals seem promising, but they are rare, expensive to process, and potentially toxic. In Chem on October 13, researchers in China present an alternative: a group of metal-free phosphorescent molecules that efficiently and persistently glow different colors at room temperature and are potentially three times more efficient than a fluorescent organic LED. Phosphorescence from organic compounds has typically been observed at extremely low temperatures and in the absence of oxygen, which limits their scope for practical applications. Room-temperature phosphorescence (RTP) has been more of a challenge, given that oxygen and physical vibrations interfere with the ability of organic phosphorescent molecules to emit light. "Organic RTP systems are desirable, thanks to their wider availability and better tailorability, but are challenging to develop," says senior author Ben Zhong Tang, a chemist at the Hong Kong University of Science & Technology, and the South China University of Technology. "In this paper, we report pure organic RTP molecules with high efficiencies and long lifetimes that will help promote basic study and practical applications of RTP processes." Tang, Weijun Zhao, and Zikai He, graduate students at the Hong Kong University of Science & Technology, and colleagues overcame the challenge by modeling how organic RTP systems behave. On the basis of this information, they designed and synthesized five carbonyl-containing aromatic molecules that stay excited and emit light for up to 230 milliseconds. The molecules could also be tuned to glow blue to orange-red. Other groups looking at the problem had focused more on blocking the phosphors' nonradiative decays. The researchers hope that these engineered phosphors can be continually tweaked to meet the requirements for sensors and light-sensitive switches. "Based on our model or structural design principle, we will try to develop RTP systems with lifetime up to seconds and efficiency up to unity (100%)," Tang says. "In particular, we will work on the developments of RTP molecules and polymers with potential of finding high-tech applications in bioimaging, optical recording, anti-counterfeiting, and afterglow organic LEDs." Explore further: Toward ultimate light efficiency on the cheap More information: Chem, Zhao and He et al.: "Rational Molecular Design for Achieving Persistent and Efficient Pure Organic Room-Temperature Phosphorescence" www.cell.com/chem/fulltext/S2451-9294(16)30112-7 , dx.doi.org/10.1016/j.chempr.2016.08.010


Huang H.,South China University of Technology | Huang H.,Xiangtan University | Ji X.,South China University of Technology | Ji X.,Xiangtan University | And 2 more authors.
Chemical Society Reviews | Year: 2015

The transition metal-catalyzed C-H functionalization with hydroxylamine derivatives serving as both reactants and internal oxidants has attracted a lot of interest. These reactions obviate the need for external oxidants and therefore result in high reactivity and selectivity, as well as excellent functional group tolerance under mild reaction conditions, and moreover, water, methanol or carboxylic acid is generally released as the by-product, thus leading to reduced waste. This review focuses on the transition metal-catalyzed oxidative C-H functionalization of N-oxyenamine internal oxidants, with an emphasis on the scope and limitations, as well as the mechanisms of these reactions. This journal is © The Royal Society of Chemistry.


Weiqi W.,South China University of Technology | Shubin W.,South China University of Technology | Liguo L.,Guangzhou You Rui Bio Technology Ltd Company
Bioresource Technology | Year: 2013

Combination of liquid hot water pretreatment (LHWP) and wet disk milling (WDM) was investigated in this study to enhance the sugar recovery yield both in prehydrolyzate and enzymatic hydrolyzate. The results show that WDM with LHWP at 180 °C for 20. min produced maximum xylose and glucose yields of 91.62% and 88.12%, respectively, which are higher than that of dilute acid pretreatment or individual LHWP. Corresponding concentration of fermentation inhibitors such as acetic acid, HMF, and furfural in the prehydrolyzate are about 0.98, 0.07 and 0.78. g/L, respectively, which indicated that the detoxification may be not required in the next fermentation step. The acid-insoluble lignin recovery in the insoluble solid resulting from enzymatic hydrolysis, was 25.67/100. g raw material, representing 90.7% of acid-insoluble lignin in the eucalyptus biomass. It can be concluded that liquid hot water pretreatment combined with wet disk milling can be successfully applied to eucalyptus. © 2012.


Zhong M.-E.,Hunan Agricultural University | Zhou Z.,South China University of Technology
Solid State Ionics | Year: 2010

Pure olivine LiFePO4/C composite compounds are synthesized by carbothermal reduction (CTR) method using trigonal anhydrous FePO4 raw material. The physical and electrochemical properties of the prepared samples are investigated in comparison with those of a sample obtained from incompletely crystallized hydrous FePO4•2H2O. The olivine LiFePO4/C prepared with trigonal anhydrous FePO4 has a high discharge capacity of 142 mAh g- 1 at 0.1 C. The composite also displays a better rate capability, a higher discharge capacity and a more stable cycle-life than that synthesized with incompletely crystallized hydrous FePO4•2H2O. The improved electrochemical performance of trigonal anhydrous FePO4 synthesis samples originates mainly from the single-phase structure and small particle size. © 2010 Elsevier B.V. All rights reserved.


Zhang Z.,Rutgers University | Zhang Z.,South China University of Technology | Zhao Y.,Rutgers University | Gong Q.,Rutgers University | And 2 more authors.
Chemical Communications | Year: 2013

Microporous metal-organic frameworks (MOFs) have attracted tremendous attention because of their versatile structures and tunable porosity that allow almost unlimited ways to improve their properties and optimize their functionality, making them very promising for a variety of important applications, especially in the adsorption and separation of small gases and hydrocarbons. Numerous studies have demonstrated that MOFs with multifunctional groups, such as open metal sites (OMSs) and Lewis basic sites (LBSs), interact strongly with carbon dioxide and are particularly effective in its capture and separation from binary mixtures of CO2 and N2. In this feature article, we briefly review the current state of MOF development in this area, with an emphasis on the effect of multifunctional groups on the selectivity and capacity of MOFs for the CO2 capture from flue gas mixtures. © 2013 The Royal Society of Chemistry.


Chen C.X.,South China University of Technology | Wu S.P.,South China University of Technology | Fan Y.X.,Shen Zhen Zhen Hua Ferrite Ceramic Electronics Co.
Journal of Alloys and Compounds | Year: 2013

Orthorhombic Mg2GeO4 ceramics were synthesized by solid-state reaction method. When stoichiometric compositions were employed, the phase transition produced under low temperature and pure orthorhombic Mg 2GeO4 phase appeared at 1000 °C. B2O 3 was employed as sintering aid to lower the sintering temperature of Mg2GeO4 ceramics and improve their relative densities. The B2O3-doped Mg2GeO4 ceramics have a low sintering temperature of 1250 °C and a small negative τf value. Microwave dielectric properties of B2O 3-doped Mg2GeO4 ceramics were: εr= 6.76, Q. × f= 95,000 GHz and τf= -28.7 ppm/°C. They could be considered as promising candidate materials for microwave/millimeter-wave devices. © 2013 Elsevier B.V. All rights reserved.


Zhang Z.,Rutgers University | Zhang Z.,South China University of Technology | Li Z.,South China University of Technology | Li J.,Rutgers University
Langmuir | Year: 2012

In this work, a computational study is performed to evaluate the adsorption-based separation of CO 2 from flue gas (mixtures of CO 2 and N 2) and natural gas (mixtures of CO 2 and CH 4) using microporous metal organic framework Cu-TDPAT as a sorbent material. The results show that electrostatic interactions can greatly enhance the separation efficiency of this MOF for gas mixtures of different components. Furthermore, the study also suggests that Cu-TDPAT is a promising material for the separation of CO 2 from N 2 and CH 4, and its macroscopic separation behavior can be elucidated on a molecular level to give insight into the underlying mechanisms. On the basis of the single-component CO 2, N 2, and CH 4 isotherms, binary mixture adsorption (CO 2/N 2 and CO 2/CH 4) and ternary mixture adsorption (CO 2/N 2/CH 4) were predicted using the ideal adsorbed solution theory (IAST). The effect of H 2O vapor on the CO 2 adsorption selectivity and capacity was also examined. The applicability of IAST to this system was validated by performing GCMC simulations for both single-component and mixture adsorption processes. © 2012 American Chemical Society.


Li Z.,South China University of Technology | Ding L.,Harbin Institute of Technology | Gao H.,Harbin Institute of Technology | Duan G.,Harbin Institute of Technology | Su C.-Y.,South China University of Technology
IEEE Transactions on Fuzzy Systems | Year: 2013

In this paper, an adaptive fuzzy control scheme is proposed for hybrid motion/force of trilateral teleoperation systems with a dual-master-single-slave configuration under stochastic time-varying delays in communication channels. Different from previous works on bilateral teleoperation systems, this paper addresses dual-master trilateral control of a single holonomic-constrained robotic manipulator, where the communication delays are modeled as multiple Markov chains, and the motion/force controls are investigated under consideration of unsymmetric stochastic time-varying delays and system dynamical uncertainties. Using partial feedback linearization, the whole trilateral teleoperation system, which consists of both master and slave manipulator dynamics, is transformed into three subsystems. By integrating Markov jump systems to handle random delays, adaptive fuzzy control strategies are developed for the nonlinear teleoperators with modeling uncertainties and external disturbances by using the approximation property of the fuzzy logic systems (FLSs). It is proven that the trilateral teleoperation system is stochastically stable in mean square under specific linear matrix inequality (LMI) conditions, and all the signals of the resulting closed-loop system are uniformly bounded. The proposed scheme is validated by extensive simulations. © 1993-2012 IEEE.


Zhao J.,South China University of Technology | Wu B.,Harbin Institute of Technology | Ou J.,Dalian University of Technology
Journal of Structural Engineering (United States) | Year: 2012

In a previous study by the authors, the cyclic behavior of a novel type of pin-connected angle steel buckling-restrained brace (ABRB) was examined, and the failure mechanism in the core projection of the ABRB induced by an excessive bending effect caused by end rotation was discussed. In this paper, the occurrence mechanism of end rotation modes and the bending effect in the core projection of an ABRB are first investigated based on the previous test results, which shows that end rotation demands would be significantly increased with the presence of a gap and an additional bending effect could be observed if the end rotation demands were large enough to cause two-point contact at the core ends. Then, a new method to predict the flexural demand on pin-connected BRBs is proposed by considering the effect of the end rotation modes, clearance, initial eccentricity, and initial deflection of casing. The design criteria to prevent yielding of the core projection are presented and further verified by the previous test results. Furthermore, the effects of key influential parameters on the flexural demand on core projection are discussed based on the analytical results. It is found that such a bending effect can be significantly reduced by decreasing the gap or increasing the constrained length of the core stiffening segment. The C-mode end rotation with single curvature bending configuration is found to be generally the most unfavorable case for core projection design. Finally, several design recommendations are provided for pin-connected BRBs. © 2012 American Society of Civil Engineers.


He L.,South China University of Technology | He L.,Xiangtan University | Ling Z.,South China University of Technology
Applied Physics Letters | Year: 2011

Mn1.85Co0.3Ni0.85O4 thin films with single cubic spinel phase and compact surface were prepared by chemical solution deposition method on Al2 O3 substrates. Temperature dependent ac impedance spectroscopy was employed to analyze the contributions of grain boundary (GB) and grain to the conduction mechanism. The major characteristics (hopping type, resistance versus temperature behavior, and characteristic temperature T0) of the GB and grain were obtained. The hopping type of GB is nearest-neighbor-hopping (NNH), and that of grain might be a transition from variable-range-hopping to NNH. The GB shows dominating resistance while the grain shows stronger temperature dependence. © 2011 American Institute of Physics.


He Z.,South China University of Technology | Xiao B.,South China University of Technology | Liu F.,University of Massachusetts Amherst | Wu H.,South China University of Technology | And 5 more authors.
Nature Photonics | Year: 2015

Polymer solar cells are an exciting class of next-generation photovoltaics, because they hold promise for the realization of mechanically flexible, lightweight, large-area devices that can be fabricated by room-temperature solution processing. High power conversion efficiencies of ∼10% have already been reported in tandem polymer solar cells. Here, we report that similar efficiencies are achievable in single-junction devices by reducing the tail state density below the conduction band of the electron acceptor in a high-performance photoactive layer made from a newly developed semiconducting polymer with a deepened valence energy level. Control over band tailing is realized through changes in the composition of the active layer and the structure order of the blend, both of which are known to be important factors in cell operation. The approach yields cells with high power conversion efficiencies (∼9.94% certified) and enhanced photovoltage. © 2015 Macmillan Publishers Limited.


Sun Y.,South China University of Technology | Sun Y.,Xinjiang University | Jiang H.,South China University of Technology | Wu W.,South China University of Technology | And 2 more authors.
Organic Letters | Year: 2013

An efficient and convenient method was developed for the formation of 2-substituted benzothiazoles via a copper-catalyzed condensation of 2-aminobenzenethiols with nitriles. The developed method is applicable to a wide range of nitriles containing different functional groups furnishing excellent yields of the corresponding products. © 2013 American Chemical Society.


Tang C.-H.,South China University of Technology | Wang S.-S.,South China University of Technology | Huang Q.,Rutgers University
Food Research International | Year: 2012

Protein fibril assembly at acidic conditions has recently attracted increasing interests in the fields of biochemical and food science, however, the obtained knowledge about the assembly of the proteins with complex structure (e.g. plant 7S/11S globulins) is still limited. This study investigated the influence of NaCl addition (0-300. mM) on the fibril assembly of soy 7S globulins (β-conglycinin), induced by heating at 80 °C and pH 2.0, with the aim of confirming the improvement of their fibril assembly by electrostatic screening. The formed fibril formation was investigated by using Th T fluorescence and atomic force microscopy (AFM) techniques. Heat-induced structure changes were traced by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and circular dichroism spectroscopy (CD). The results indicated that the whole fibril assembly experienced protein dissociation/hydrolysis and subsequent fibrillization process, and increasing NaCl concentration progressively increased the amount of formed fibrils, and even fibril length. AFM analyses confirmed that the increase in NaCl concentration shortened the time at which the short fibrils were visually observed, and the morphology of formed fibrils, including height of fibrils, width at half-height, and coil periodicity, slightly varied with the added NaCl concentration. The CD analyses indicated that increasing NaCl concentration greatly favored formation of β-type secondary structure, as well as extensive disruption of tertiary and/or quaternary conformations. These results confirmed that the electrostatic screening greatly improved the heat-induced fibril assembly process of soy β-conglycinin at pH 2.0. The improvement of fibril formation was largely attributed to increased extent of conformational changes at higher ionic strength. These findings would provide important information about the fibril assembly of plant oligomeric globulins at acidic pH that have important implications for the development of protein protein-based fibrillar gels. © 2011 Elsevier Ltd.


Wei W.,South China University of Technology | Wu S.,South China University of Technology | Liu L.,Guangzhou You Rui Bio technology Ltd Company
Bioresource Technology | Year: 2012

Dilute sulfuric acid was used to pretreat eucalyptus chips prior to enzymatic hydrolysis. After both pretreatment and enzymatic hydrolysis processes. Attention is paid to sugar recovery. The maximum total sugars yield (combined xylose and glucose, 47.69. g/100. g raw material, representing 82% of total sugars in the eucalyptus biomass) was obtained at 160. °C, 0.75% acid concentration and 10. min residence time, which is consider to be the best reasonable conditions for the dilute acid pretreatment of eucalyptus, corresponding concentrations of acetic acid, HMF, and furfural in the prehydrolysate were about 2.01. g/L, 0.13. g/L and 1.37. g/L, respectively. Under this optimal pretreatment condition, the acid-insoluble lignin recovery in the insoluble solid resulting from enzymatic hydrolysis, was 22.7. g/100. g raw material, representing 80% of acid-insoluble lignin in the eucalyptus biomass. © 2012 Elsevier Ltd.


Wu Y.-N.,Zhao Qing University | Liao S.-J.,South China University of Technology | Guo H.-F.,Zhao Qing University | Hao X.-Y.,Zhao Qing University
Journal of Power Sources | Year: 2013

A high-performance, low platinum loading catalyst for the anodic oxidation of methanol, Pd@PtRu/C, is prepared by a two-step colloidal approach. The activity of the Pd@PtRu/C catalyst is 1.67 times and 1.81 times that of PtRu/C and PtRuPd/C catalysts, respectively. The catalysts are characterized by TEM, XPS, and XRD. The active components are dispersed on the surface of the carbon support very well, yielding a particle size of ca. 4.7 nm and a shell thickness of ca. 0.25 nm. The catalyst's high activity may be attributed to the high exposure and dispersion of PtRu, as well as the interaction of PtRu in the shell layer with Pd in the core, resulting from the catalyst's core-shell structure. © 2012 Elsevier B.V. All rights reserved.


Hu J.-F.,Jiangxi University of Science and Technology | Zhang X.-M.,South China University of Technology
Guangxue Jingmi Gongcheng/Optics and Precision Engineering | Year: 2012

To achieve the precise motion of a 3-RRR compliant parallel precision positioning stage, a closed-form exact motion model was established and the optimized design of structure parameters was investigated. The Castigliano's second theorem was applied to establishment of the closed-form compliance model for the precision positioning stage. According to the structural characteristics of compliant parallel mechanisms, the system was divided into three symmetrical motion sub-chains. Combining the compliance equations of flexure hinge with the force transmission relations of mechanisms, the stiffness model of each sub-chain was obtained, and the stiffness of the entire system was calculated by summing the stiffness of three sub-chains in the same coordinate system. The proposed stiffness model took the hinge flexibility as the independent variables in the closed form. According to the flexibility matrix, the Jacobian matrix to reflect the relationship between input displacement and output one could be derived. By comparing the kineamatic model between theoretical analysis and FEA, the results show that the errors are within 1.0%~9.5%, which illurastrates that the proposed kinematic model is correct and precise. According to the closed-form Jacobian matrix, its sensitivity to structureal parameters was analyzed, then the design variables with greater impact on the kinematic properties were chosen. By taking the maxmium workspace as a target and the hinge strength, maxmium input forces, geometric dimensions and input coupling as the constrains, an optimal model was proposed. The results show that the optimized structural parameters can obtain more output displacements, and the proposed model can meet the design requirement.


Li S.-Z.,South China University of Technology | Wu P.-X.,South China University of Technology | Wu P.-X.,The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters
Journal of Hazardous Materials | Year: 2010

Anionic surfactant modified Fe-pillared montmorillonites were prepared by Fe-hydrate solution and sodium dodecyl sulfate (SDS) solution. These organo-inorgano complex montmorillonites were divided into three types (CM1, CM2 and CM3) depending on different intercalation processes. X-ray diffraction spectra, the Fourier transform infrared (FTIR) spectra were used to analyze the structure of the raw and modified montmorillonites. X-ray photoelectron spectra of the simples have been studied to determine spectral characteristics to allow the identification of Fe(III) hydroxide. The specific surface area of the host montmorillonite (M0) is 73.2 m2/g, while for the modified montmorillonites it is 114.0 m2/g, 117.2 m2/g, and 115.8 m2/g, respectively. The mesopore volumes of the montmorillonites decrease after modification. Ions of copper and cobalt were selected as adsorbates to evaluate the adsorption performance of each montmorillonite. The adsorption data was analyzed by both Freundlich and Langmuir isotherm models and the data was well fit by the Langmuir isotherm model. The adsorption was efficient and significantly influenced by metal speciation, metal concentration, contact time, and pH. Higher adsorption capacity of the modified montmorillonites were obtained at pH 5-6. The results of desorption indicated that the metal ions were covalently bound to the modified montmorillonites. © 2009 Elsevier B.V. All rights reserved.


Huang Z.,Hong Kong Baptist University | Huang Z.,South China University of Technology | Bai F.,Hong Kong Baptist University
Nanoscale | Year: 2014

Minimization of helices opens a door to impose novel functions derived from the dimensional shrinkage of optical, mechanical and electronic devices. Glancing angle deposition (GLAD) enables one to deposit three-dimensional helical porous thin films (HPTFs) composed of separated spiral micro/nano-columns. GLAD integrates a series of advantageous features, including one-step deposition, wafer-scale production with mono-handedness of spirals, flexible engineering of spiral materials and dimensions, and the adaption to various kinds of substrates. Herein, we briefly review the fabrication of HPTFs by GLAD, specific growth mechanisms, physical properties in structures, mechanics and chiral optics, and the emerging applications in green energy. A prospective outlook is presented to illuminate some promising developments in enantioselection, bio-dynamic analyses, wirelessly-controlled drug delivery and mass production. © 2014 the Partner Organisations.


Chen L.,South China University of Technology | Chen H.,South China University of Technology | Luque R.,University of Cordoba, Spain | Li Y.,South China University of Technology
Chemical Science | Year: 2014

A novel synthesis strategy is developed to encapsulate palladium precursors through ligand design prior to MOF assembly, achieving uniformly distributed palladium NPs inside the cavities of MOFs. This strategy can avoid the different diffusion resistance between external and internal surfaces, and thus allow metal precursors to be easily deposited into the pores and evenly distributed within MOF networks. The embedded Pd NPs exhibited excellent shape-selectivity in olefin hydrogenation, as well as high catalytic efficiencies in aerobic oxidation of alcohols and reduction of nitrobenzene, showing significantly enhanced catalytic activity and stability as compared to those synthesized using a traditional impregnation method. The superior catalytic activity and stability came from the synergetic effects of nano-confinement and electron-donation offered by the MOF framework. © 2014 the Partner Organisations.


Liu H.,South China University of Technology | Li Y.,South China University of Technology | Jiang H.,South China University of Technology | Vargas C.,Rey Juan Carlos University | Luque R.,University of Cordoba, Spain
Chemical Communications | Year: 2012

An unprecedented synergistic effect, obtained for rationally designed Au-Pd alloy nanoparticles supported on an acidic metal-organic framework (MOF), in the aerobic oxidation of the primary C-H bonds in toluene and derivates is reported. © 2012 The Royal Society of Chemistry.


Wang M.,South China University of Technology | Cai Z.,Hong Kong Baptist University | Xu L.,South China University of Technology
Journal of Chromatography A | Year: 2011

Concurrent sample clean-up and enhancement in detection sensitivity for chiral capillary electrophoresis was demonstrated based on the coupling of salting-out extraction with acetonitrile stacking and the use of dimethyl-beta-cyclodextrin as the chiral selector for the sensitive and enantioselective separation of warfarin enantiomers in urine samples. By optimizing the pH of salting-out extraction, warfarin enantiomers can be efficiently extracted from the aqueous sample solution into a smaller volume organic solvent (acetonitrile) phase. The pressure injection of the enriched acetonitrile phase (containing ca. 1% NaCl) into the CE capillary at 10% capillary volume resulted in additional concentration of the warfarin enantiomers. The limit of detection for both warfarin enantiomers was as low as 1.5. ng/mL in urine sample. Our results show that the novel strategy offers improved sensitivity compared to conventional CE analysis, reaching a combined enrichment factor higher than 1000. Calibration curves of warfarin enantiomers in urine samples were found to be linear between 10 and 1000. ng/mL, and intra- and inter-day precision (N= 9) for both warfarin enantiomers in terms of migration time and peak area were found to be within the range of 0.1-0.8% and 1.0-6.7%, respectively. The recovery of warfarin enantiomers from urine was ca. 90%. © 2011 Elsevier B.V.


Liu H.,South China University of Technology | Li Y.,South China University of Technology | Luque R.,University of Cordoba, Spain | Jiang H.,South China University of Technology
Advanced Synthesis and Catalysis | Year: 2011

A water-tolerant bifunctional heterogeneous catalyst is able to effectively catalyse the selective hydrogenation of phenol to cyclohexanone in water at atmospheric pressure and room temperature with >99.9% selectivity to cyclohexanone at phenol conversions >99.9%. The catalyst was found to be highly active and reusable, giving identical activities and selectivities after >5 uses. Moreover, this reported simple bifunctional catalyst is also able to hydrogenate a range of substituted phenols in high yields under the investigated aqueous conditions. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Zhu X.-H.,South China University of Technology | Peng J.,South China University of Technology | Cao Y.,South China University of Technology | Roncali J.,University of Angers
Chemical Society Reviews | Year: 2011

This tutorial review presents some recent developments in the design, synthesis and implementation of organic solution-processable molecular fluorophores for non-doped electroluminescent light-emitting devices. After a brief presentation of the basic principles of operation and main characteristics of electroluminescent devices, some examples of active emitters representative of the main classes of non-doped molecular electrofluorophores will be discussed. Emphasis is placed on the relationships between the molecular structure and the electronic properties of molecular emitters, in which high photoluminescence efficiency, synthetic accessibility and processability are combined by design with additional functions such as hole and/or electron injection and transport. © 2011 The Royal Society of Chemistry.


Ying L.,South China University of Technology | Ho C.-L.,Hong Kong Baptist University | Wu H.,South China University of Technology | Cao Y.,South China University of Technology | And 2 more authors.
Advanced Materials | Year: 2014

White polymer light-emitting devices (WPLEDs) have become a field of immense interest in both scientific and industrial communities. They have unique advantages such as low cost, light weight, ease of device fabrication, and large area manufacturing. Applications of WPLEDs for solid-state lighting are of special interest because about 20% of the generated electricity on the earth is consumed by lighting. To date, incandescent light bulbs (with a typical power efficiency of 12-17 lm W-1) and fluorescent lamps (about 40-70 lm W-1) are the most widely used lighting sources. However, incandescent light bulbs convert 90% of their consumed power into heat while fluorescent lamps contain a small but significant amount of toxic mercury in the tube, which complicates an environmentally friendly disposal. Remarkably, the device performances of WPLEDs have recently been demonstrated to be as efficient as those of fluorescent lamps.Here, we summarize the recent advances in WPLEDs with special attention paid to the design of novel luminescent dopants and device structures. Such advancements minimize the gap (for both efficiency and stability) from other lighting sources such as fluorescent lamps, light-emitting diodes based on inorganic semiconductors, and vacuum-deposited small-molecular devices, thus rendering WPLEDs equally competitive as these counterparts currently in use for illumination purposes. Recent advances in white polymer light-emitting devices (WPLEDs) are summarized in terms of efficiency, stability and color quality, with special attention paid to the design of novel luminescent dopants and the device structure. Such advancements render WPLEDs as competitive as other lighting sources that are currently in use for illumination purposes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Yang X.,Xi'an Jiaotong University | Zhou G.,Xi'an Jiaotong University | Wong W.-Y.,Hong Kong Baptist University | Wong W.-Y.,Shenzhen University | Wong W.-Y.,South China University of Technology
Chemical Society Reviews | Year: 2015

Phosphorescent organic light-emitting devices (OLEDs) have attracted increased attention from both academic and industrial communities due to their potential practical application in high-resolution full-color displays and energy-saving solid-state lightings. The performance of phosphorescent OLEDs is mainly limited by the phosphorescent transition metal complexes (such as iridium(iii), platinum(ii), gold(iii), ruthenium(ii), copper(i) and osmium(ii) complexes, etc.) which can play a crucial role in furnishing efficient energy transfer, balanced charge injection/transporting character and high quantum efficiency in the devices. It has been shown that functionalized main-group element (such as boron, silicon, nitrogen, phosphorus, oxygen, sulfur and fluorine, etc.) moieties can be incorporated into phosphorescent emitters and their host materials to tune their triplet energies, frontier molecular orbital energies, charge injection/transporting behavior, photophysical properties and thermal stability and hence bring about highly efficient phosphorescent OLEDs. So, in this review, the recent advances in the phosphorescent emitters and their host materials functionalized with various main-group moieties will be introduced from the point of view of their structure-property relationship. The main emphasis lies on the important role played by the main-group element groups in addressing the key issues of both phosphorescent emitters and their host materials to fulfill high-performance phosphorescent OLEDs. © The Royal Society of Chemistry 2015.


Li J.,South China University of Technology | Yu Q.,South China University of Technology | Wei J.,Wushan Road 381 | Zhang T.,South China University of Technology
Cement and Concrete Research | Year: 2011

This study investigates the structural characteristics and hydration kinetics of modified basic oxygen furnace steel slag. The basic oxygen furnace steel slag (BOFS) was mixed with electric arc furnace steel slag (EAFS) in appropriate ratios and heated again at high temperature in the laboratory. The mineralogical and structural characteristics of both BOFS and modified steel slag (MSS) were characterized by X-ray diffraction, optical microscopy, scanning electron microscopy, Raman and Fourier transform infrared spectroscopies. The results show that modification increases alite content in MSS and decreases alite crystal size with the formation of C6AF2. One more obvious heat evolution peak appears in MSS's heat-flow rate curves in comparison to BOFS, becoming similar to that of typical Portland cement paste. As a result, its cementitious activity is much improved. © 2010 Elsevier Ltd. All rights reserved.


Yang X.,Xi'an Jiaotong University | Zhou G.,Xi'an Jiaotong University | Wong W.-Y.,Hong Kong Baptist University | Wong W.-Y.,South China University of Technology
Journal of Materials Chemistry C | Year: 2014

White polymer light-emitting diodes (WPLEDs) represent an intense research subject towards their potential applications in full-color displays, next-generation solid-state lighting sources and back-lighting of liquid-crystal displays due to their merits including low-cost fabrication, flexibility, large area and ease of construction etc. Unfortunately, WPLEDs generally show much poorer EL performance with respect to those made by the vacuum deposition strategy owing to the inherent disadvantages associated with the materials used, device structures and device fabrication processes etc., which has seriously restricted their practical applications. However, the performances of WPLEDs have been improved greatly in recent years, and can even realize some practical devices. In this review, the critical design tactics employed to achieve this goal are presented, which include developing high performance functional light emitters, maintaining a good charge injection/transport balance, introducing new functional layer, surface morphology engineering and employing novel device construction processes etc. In addition, the ongoing challenges and future perspectives of this research frontier are also highlighted. © 2014 The Royal Society of Chemistry.


He Z.,South China University of Technology | Zhong C.,South China University of Technology | Huang X.,CAS Suzhou Institute of Nano Technology and Nano Bionics | Wong W.-Y.,University of Hong Kong | And 5 more authors.
Advanced Materials | Year: 2011

Simultaneous enhancement of open-circuit voltage, short-circuit current density, and fill factor in highly efficient polymer solar cells by incorporating an alcohol/water-soluble conjugated polymer as cathode interlayer is domonstrated. When combined with a low-bandgap polymer PTB7 as the electron donor material, the power efficiency of the devices is improved to certified 8.370%. Due to drastic improvement in efficiency and easy utilization, this method opens new opportunities for PSCs from various material systems to improve towards 10% efficiency. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Liu D.,South China University of Technology | Sun D.-W.,South China University of Technology | Sun D.-W.,University College Dublin | Zeng X.-A.,South China University of Technology
Food and Bioprocess Technology | Year: 2014

During the past decade, hyperspectral imaging (HSI) has been rapidly developing and widely applied in the food industry by virtue of the use of chemometric techniques in which wavelength selection methods play an important role. This paper is a review of such variable selection methods and their limitations, describing the basic taxonomy of the methods and their respective advantages and disadvantages. Special attention is paid to recent developments in wavelength selection techniques forHSI in the field of food quality and safety evaluations. Typical and commonly usedmethods in HSI, such as partial least squares regression, stepwise regression and spectrum analysis, are described in detail. Some sophisticatedmethods, such as successive projections algorithm, uninformative variable elimination, simulated annealing, artificial neural network and genetic algorithm methods, are also discussed. Finally, new methods not currently used but that could have substantial impact on the field are presented. In short, this review provides an overview of wavelength selection methods in food-related areas and offers a thoughtful perspective on future potentials and challenges in the development of HSI systems. © Springer Science+Business Media New York 2013.


Pu H.,South China University of Technology | Kamruzzaman M.,University College Dublin | Sun D.-W.,South China University of Technology | Sun D.-W.,University College Dublin
Trends in Food Science and Technology | Year: 2015

There is a great interest in developing optical techniques that have the capability of predicting quality attributes, safety parameters and authenticity in real-time assessment. Recently, hyperspectral imaging technique has been widely used for rapid and non-destructive inspection of various food products. Although the technique is currently in an early development stage, its potential is promising. Due to the extensive time needed for the processing of the large volumes of data, hyperspectral imaging technique cannot be directly implemented in an online system. However, selecting some feature wavelengths from hyperspectral images can be useful to develop a multispectral imaging system, which can meet the speed requirement of industrial production. Indeed, the success of multispectral imaging heavily depends on the effectiveness of hyperspectral imaging (HSI) for providing the feature wavelengths. If the high dimensionality of hyperspectral data can be reduced properly in order to design/form a low-cost multispectral imaging sensor based on some selected feature wavelengths for certain applications, the technique would certainly be incomparable for process monitoring and real-time inspection. This review first introduces the fundamental steps for selecting feature wavelengths from hyperspectral data and then describes the feature wavelengths derived from hyperspectral imaging applications to make a more effective and efficient multispectral real-time imaging system. It is anticipated that this review can act as a basis for researchers and industry for further development of online multispectral inspection system for quality, safety and authenticity of muscles food. © 2015 Elsevier Ltd.


Huang H.,South China University of Technology | Ruckenstein E.,State University of New York at Buffalo
Journal of Physical Chemistry Letters | Year: 2013

The repulsive force between two electrically charged parallel plates immersed in an electrolyte solution is calculated by taking into account the hydration of ions and the volume exclusion entropy thus generated. The ion specificity, ignored in the traditional DLVO theory, is thus accounted for. It is found that the hydration of ions affects, under some conditions, the repulsive force between the two plates and that the sequence of its strength follows closely the famous Hofmeister series for the salting out (precipitation) of proteins. © 2013 American Chemical Society.


Zeng Y.,South China University of Technology | Liao S.,South China University of Technology | Dai J.,Huaqiao University | Fu Z.,South China University of Technology
Chemical Communications | Year: 2012

An air-stable photoresponsive viologen molecular system is constructed based on a three-fold accordion interpenetrating packing arrangement. The fluorescent modulation process is coupled with a photochromic reaction via energy and electron transfer between the adjacent donor and acceptor groups. © 2012 The Royal Society of Chemistry.


Fan C.,Hubei University | Li Y.,South China University of Technology | Yang C.,Hubei University | Wu H.,South China University of Technology | And 2 more authors.
Chemistry of Materials | Year: 2012

Two new phosphoryl/sulfonyl-substituted iridium complexes, POFIrpic and SOFIrpic, have been designed and synthesized on the basis of the structural frame of sky-blue FIrpic. The introduction of phosphoryl/sulfonyl moieties into the 5′-position of phenyl ring makes the emission peak blue-shift to the 460 nm, simultaneously the compounds maintain high photoluminescence quantum yields (PLQYs) of about 50% in solution. Single-layer blue and white polymer organic light-emitting diodes by full solution-process were fabricated with the following configuration: ITO/PEDOT:PSS/PVK:OXD-7:dopants/CsF/Al. The blue device based on POFIrpic shows a maximum current efficiency of 11.1 cd A-1, a maximum external quantum efficiency of 7.1%, which are the highest ever reported for blue PhOLEDs by full solution process. The white device with POFIrpic as blue component reveals a maximum current efficiency of 25 cd A -1, a maximum external quantum efficiency of 15%, and a good CRI value of 82. © 2012 American Chemical Society.


Huo B.,Zhejiang University | Zhao X.,China Europe International Business School | Zhao X.,South China University of Technology | Zhou H.,University of New Hampshire
Production and Operations Management | Year: 2014

Information sharing in supply chains has become an important topic over the past decade. This study uses data from 617 Chinese manufacturing firms to investigate the relationships among competitive environments, supply chain information sharing (SCIS), and supply chain performance. The results of structural equation modeling analysis show that (i) international competition is positively related to all three types of SCIS whereas local competition is not significantly related to any of the three types, (ii) internal information sharing is positively related to external information sharing with suppliers and customers, and (iii) internal information sharing and information sharing with customers are positively related to superior supply chain performance, whereas supplier information sharing is not significantly related to performance. The findings enhance our understanding of the relationships among competitive environment, SCIS, and supply chain performance in Chinese manufacturing settings. © 2013 Production and Operations Management Society.


Huang H.,South China University of Technology | Ruckenstein E.,State University of New York at Buffalo
Journal of Physical Chemistry B | Year: 2013

A negatively charged microparticle is immersed into an aqueous solution containing highly negatively charged nanoparticles and an electrolyte. Using a modified Poisson-Boltzmann equation which takes into account the van der Waals interactions between microparticle and nanoparticles and in which the latter are treated as macro-ions, it was found that there are conditions under which the concentration of nanoparticles close to the microparticle becomes larger (even much larger) than the bulk one and halos are formed around the latter particles. Halos are formed when the van der Waals attractive interactions between the microparticle and nanoparticles are stronger than the repulsive interactions between the same particles plus the repulsive interactions between the nanoparticles. © 2013 American Chemical Society.


Cheng J.-H.,South China University of Technology | Sun D.-W.,South China University of Technology | Sun D.-W.,University College Dublin
Trends in Food Science and Technology | Year: 2014

Quality analysis and evaluation for fish and other seafoods is playing an important role in providing products of superior quality in consideration of human health and international trade. Currently, it is necessary to look for effective and rapid techniques to monitor quality changes and safety indices due to the vulnerability and perishability of aquatic products. Hyperspectral imaging, as an emerging and innovative technique, combines typical computer vision and spectroscopy into one system. In recent years, hyperspectral imaging has been extensively studied and implemented as an alternative to traditional analytical methods and has proved its potential for simultaneously quantitative and qualitative determination of nematode contamination, measurement and visualization of physical and chemical constituents, recognition of fresh and treated samples as well as detection of microbial spoilage and economic adulteration in a rapid, objective and non-destructive way. In this review, the basic knowledge of hyperspectral imaging and its current research and potential industrial applications on quality inspection and evaluation of fish and other seafoods were discussed. In addition, some advantages, disadvantages and future trends of hyperspectral imaging applications were also presented. © 2014 Elsevier Ltd.


Li H.,Nanjing Institute of Technology | Luo Y.,South China University of Technology | Chen Y.,Utah State University
IEEE Transactions on Control Systems Technology | Year: 2010

In recent years, it is remarkable to see the increasing number of studies related to the theory and application of fractional order controller (FOC), specially PIλDμ controller, in many areas of science and engineering. Research activities are focused on developing new analysis and design methods for fractional order controllers as an extension of classical control theory. In this paper, a new tuning method for fractional order proportional and derivative (PD;mu; or FO-PD controller is proposed for a class of typical second-order plants. The tuned FO-PD controller can ensure that the given gain crossover frequency and phase margin are fulfilled, and furthermore, the phase derivative w. r. t. the frequency is zero, i.e., the phase Bode plot is flat at the given gain crossover frequency. Consequently, the closed-loop system is robust to gain variations. The FOC design method proposed in the paper is practical and simple to apply. Simulation and experimental results show that the closed-loop system can achieve favorable dynamic performance and robustness. © 2009 IEEE.


Marsili E.,University of Minnesota | Sun J.,South China University of Technology | Bond D.R.,University of Minnesota
Electroanalysis | Year: 2010

The ability of Geobacter sulfurreducens to utilize electrodes as electron acceptors provides a system for monitoring mechanisms of electron transfer beyond the cell surface. This study examined the physiology of extracellular electron transfer during many stages of growth, and in response to short- and long-term changes in electron acceptor potential. When G. sulfurreducens was grown on planar potentiostat-controlled electrodes, the magnitude of early cell attachment increased with initial cell density. However, the first cells to attach did not demonstrate the same electron transfer rates as cells grown on electrodes. For example, following initial attachment of fumarate-grown cells, the electron transfer rate was 2 mA/mg protein, but increased to nearly 8 mA/mg protein within 6 h of growth. Once attached, all biofilms grew at a constant rate (doubling every 6 h), and sustained a high specific electron transfer rate and growth yield, while current density was below 300 mA/cm2. Beyond this point, the rate of current increase slowed and approached a stable plateau. At all phases, slow scan rate cyclic voltammetry of G. sulfurreducens showed a similar well-defined sigmoidal catalytic wave, indicating the general model of electron transfer to the electrode was not changing. Short-term exposure to reducing potentials (3 h) did not alter these characteristics, but did cause accumulation of electrons which could be discharged at potentials above -0.1 V. Sustained growth at lower potentials (0.16 V) only slightly altered the pattern of detectable redox species at the electrode, but did eliminate this pattern of discharge from the biofilm. Single-turnover voltammetry of colonized electrodes showed at least 3 redox couples at potentials similar to other recent observations, with redox protein coverage of the electrode on the order of ca. 1 nmol/cm2. The consistent electrochemistry, growth rate, and growth yield of the G. sulfurreducens biofilm at all stages suggests an initial phase where cells must optimize attachment or electron transfer to a surface, and that after this point, the rate of electron production by cells (rate electrons are delivered to the external surface) remains rate limiting compared to the rate electrons can be transferred between cells, and to electrodes. © 2010 Wiley-VCH Verlag GmbH&Co.


Zhao L.-C.,Northwest University, China | Li S.-C.,Xi'an Jiaotong University | Ling L.,South China University of Technology
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2014

We investigate the solution in rational form for the Sasa-Satsuma equation on a continuous background which describes a nonlinear fiber system with higher-order effects including the third-order dispersion, Kerr dispersion, and stimulated inelastic scattering. The W-shaped soliton in the system is obtained analytically. It is found that the height of hump for the soliton increases with decreasing the background frequency in certain parameter regime. The maximum height of the soliton can be three times the background's height and the corresponding profile is identical with the one for the well-known eye-shaped rogue wave with maximum peak. The numerical simulations indicate that the W-shaped soliton is stable with small perturbations. Particularly, we show that the W-shaped soliton corresponds to a stable supercontinuum pulse by performing exact spectrum analysis. © 2014 American Physical Society.


Cheng J.-H.,South China University of Technology | Sun D.-W.,South China University of Technology | Sun D.-W.,University College Dublin
Food and Bioprocess Technology | Year: 2015

Microbial contamination during fish flesh spoilage process can easily induce food-borne outbreaks and consumer health problems. Hyperspectral imaging in the spectral range of 400–1000 nm was developed to measure the Escherichia coli (E. coli) loads in grass carp fish for evaluation and visualization of microbial spoilage. Partial least square regression (PLSR) model was conducted to build prediction models between the spectral data and the reference E. coli loads estimated by classical microbiological plating method. The PLSR model based on full wavelengths showed good performance on predicting E. coli loads with the residual predictive deviation (RPD) of 5.47 and determination coefficient of R2 P = 0.880. Six characteristic wavelengths were selected by the weighted regression coefficients from PLSR analysis and used to simplify the models. The simplified PLSR and multiple linear regression (MLR) models also presented good prediction capability. The better simplified MLR model (RPD = 5.22 and R2 P = 0.870) was used to transfer each pixel in the image for visualizing the spatial distribution of E. coli loads. The results demonstrated that hyperspectral imaging technique with multivariate analysis has the potential to rapidly and non-invasively quantify and visualize the E. coli loads in grass carp fish flesh during the spoilage process. © 2015, Springer Science+Business Media New York.


Huang H.,University of Hong Kong | Leung D.Y.C.,University of Hong Kong | Ye D.,South China University of Technology
Journal of Materials Chemistry | Year: 2011

A series of highly active Pt/TiO2 catalysts were prepared by impregnation and deposition precipitation methods with different reduction processes. Their catalytic activities were evaluated by catalytic decomposition of formaldehyde (HCHO) at room temperature. The effects of reduction treatment on structural properties and catalytic activity were studied. Reduced Pt/TiO2 catalysts showed large differences in structural properties (such as particle size, oxidation state, surface content and electronic property of Pt nanoparticles, and surface oxygen) and catalytic activity for HCHO oxidation compared with the unreduced ones. Nearly 100% HCHO conversion was achieved on the former. Especially, sodium borohydride reduced Pt/TiO 2 catalysts even with 0.1% Pt loading showed nearly complete oxidation of HCHO. Well-dispersed and negatively charged metallic Pt nanoparticles, and rich chemisorbed oxygen are probably responsible for their high catalytic activities. © 2011 The Royal Society of Chemistry.


He S.,Southern Medical University | Liu S.,South China University of Technology | Zhu H.,Southern Medical University
BMC Evolutionary Biology | Year: 2011

Background: An increasing number of long noncoding RNAs (lncRNAs) have been identified recently. Different from all the others that function in cis to regulate local gene expression, the newly identified HOTAIR is located between HoxC11 and HoxC12 in the human genome and regulates HoxD expression in multiple tissues. Like the well-characterised lncRNA Xist, HOTAIR binds to polycomb proteins to methylate histones at multiple HoxD loci, but unlike Xist, many details of its structure and function, as well as the trans regulation, remain unclear. Moreover, HOTAIR is involved in the aberrant regulation of gene expression in cancer. Results: To identify conserved domains in HOTAIR and study the phylogenetic distribution of this lncRNA, we searched the genomes of 10 mammalian and 3 non-mammalian vertebrates for matches to its 6 exons and the two conserved domains within the 1800 bp exon6 using Infernal. There was just one high-scoring hit for each mammal, but many low-scoring hits were found in both mammals and non-mammalian vertebrates. These hits and their flanking genes in four placental mammals and platypus were examined to determine whether HOTAIR contained elements shared by other lncRNAs. Several of the hits were within unknown transcripts or ncRNAs, many were within introns of, or antisense to, protein-coding genes, and conservation of the flanking genes was observed only between human and chimpanzee. Phylogenetic analysis revealed discrete evolutionary dynamics for orthologous sequences of HOTAIR exons. Exon1 at the 5' end and a domain in exon6 near the 3' end, which contain domains that bind to multiple proteins, have evolved faster in primates than in other mammals. Structures were predicted for exon1, two domains of exon6 and the full HOTAIR sequence. The sequence and structure of two fragments, in exon1 and the domain B of exon6 respectively, were identified to robustly occur in predicted structures of exon1, domain B of exon6 and the full HOTAIR in mammals. Conclusions: HOTAIR exists in mammals, has poorly conserved sequences and considerably conserved structures, and has evolved faster than nearby HoxC genes. Exons of HOTAIR show distinct evolutionary features, and a 239 bp domain in the 1804 bp exon6 is especially conserved. These features, together with the absence of some exons and sequences in mouse, rat and kangaroo, suggest ab initio generation of HOTAIR in marsupials. Structure prediction identifies two fragments in the 5' end exon1 and the 3' end domain B of exon6, with sequence and structure invariably occurring in various predicted structures of exon1, the domain B of exon6 and the full HOTAIR. © 2011 He et al; licensee BioMed Central Ltd.


Yang L.,Leibniz Institute for Solid State and Materials Research | Yang L.,South China University of Technology | Wang S.,Fudan University | Mao J.,Fudan University | And 6 more authors.
Advanced Materials | Year: 2013

Hierarchical MoS2/polyaniline nanowires, integrating MoS 2 nanosheets with conductive polyaniline, serve as prominent anode materials for Li-ion batteries, presenting high capacity and good cyclability. The polyaniline-hybrid structure and hierarchical features significantly promote the Li-storage performance as compared with the bare MoS2, indicating new opportunities for developing electrode nanomaterials. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Wang X.,South China University of Technology | Luo Z.,South China University of Technology | Xiao Z.,Shenyang Normal University
Carbohydrate Polymers | Year: 2014

β-Cyclodextrin (β-CD), which is widely used to increase the stability, solubility, and bioavailability of guests, can form host-guest inclusion complexes with a wide variety of organic molecules. In this study the β-CD/soybean lecithin inclusion complex was prepared. The effect of reaction parameters such as reaction temperature, reaction time and the molar ratio of β-CD/soybean lecithin on inclusion ratio were studied. The inclusion ratio of the product prepared under the optimal conditions of β-CD/soybean lecithin molar ratio 2:1, reaction temperature 60 C reaction time 2 h was 40.2%. The results of UV-vis, DSC, XRD and FT-IR spectrum indicated the formation of inclusion complex. The thermal stability experiment indicated that the thermal stability of soybean lecithin in inclusion complex was significantly improved compared with free soybean lecithin. © 2013 Elsevier Ltd. All rights reserved.


Yang T.,University of Akron | Yang T.,South China University of Technology | Wang M.,South China University of Technology | Duan C.,South China University of Technology | And 5 more authors.
Energy and Environmental Science | Year: 2012

Bulk heterojunction (BHJ) polymer solar cells (PSCs) that can be fabricated by solution processing techniques are under intense investigation in both academic institutions and industrial companies because of their potential to enable mass production of flexible and cost-effective alternative to silicon-based solar cells. A combination of novel polymer development, nanoscale morphology control and processing optimization has led to over 8% power conversion efficiencies (PCEs) for BHJ PSCs with a conventional device structure. Attempts to develop PSCs with an inverted device structure as required for achieving high PECs and good stability have, however, met with limited success. Here, we report that a high PCE of 8.4% under AM 1.5G irradiation was achieved for BHJ PSCs with an inverted device structure. This high efficiency was obtained through interfacial engineering of solution-processed electron extraction layer, leading to facilitate electron transport and suppress bimolecular recombination. These results provided an important progress for solution-processed PSCs, and demonstrated that PSCs with an inverted device structure are comparable with PSCs with the conventional device structure. This journal is © The Royal Society of Chemistry 2012.


Lu H.L.,University of Hong Kong | Huang G.Q.,University of Hong Kong | Yang H.D.,South China University of Technology
International Journal of Production Research | Year: 2011

This paper deals with an assembly job shop scheduling problem considering two phases of control: order review/release (ORR) and dispatching rules. Dispatching rules have been intensively used in earlier job shop research. Such rules determine the processing sequence of jobs waiting in the queues of corresponding machines. In recent years, ORR emerges as another option for job shop control and has received increasing attention. Such control determines when to release jobs to the shop floor. Different ORR mechanisms have been devised and are reported to bring several advantages such as reduced inventory cost of early finished orders, controlled and balanced shop load levels and shorter order flow time. Previous studies on ORR often assume a simplified job shop without assembly operations, while this research applies ORR to an assembly job shop. The aim of this research is to evaluate the ability of different combinations of ORR-dispatching rules in optimising due date and flow time related performance measures. Full factorial experiment has been designed for a simulated assembly job shop. Results show that both ORR and dispatching rules are highly relevant with respect to the due date and flow time related performance measures. Particularly, the incorporation of ORR control into the existing control of dispatching rules is highly important for better performance of assembly job shop control. © 2011 Taylor & Francis.


Xie F.,Guangzhou University | Yang R.,Guangzhou University | Zhang B.,South China University of Technology
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2011

Total ampere-turns of the primary and secondary windings of a transformer are taken as one of variables to analyze the bifurcation behaviors and the border colision phenomenon on voltage-mode-controlled flyback converter. Six operation modes which are separated by the two borderlines of capacitor voltage and the three borderlines of total ampere-turns are obtained. A class of explicit piecewise smooth discrete-time maps with six operation modes is derived to describe the dynamics of the system. The numerical calculations are carried out, the bifurcation diagrams and the maximal Lyapunov exponent spectrums with the control period as a parameter are obtained. Then, the paper particularly analyzes the stability and existence conditions of main periodic orbits. The structure of bifurcation diagrams and the characteristics of operation modes at the border collision points are studied too. Finally, PSIM simulation and experimental results testify the validity of theoretical analysis. © 2011 IEEE.


Lin F.,Courant Institute of Mathematical Sciences | Lin J.,South China University of Technology | Wang C.,University of Kentucky
Archive for Rational Mechanics and Analysis | Year: 2010

This paper is concerned with a simplified hydrodynamic equation, proposed by Ericksen and Leslie, modeling the flow of nematic liquid crystals. In dimension two, we establish both interior and boundary regularity theorems for such a flow under smallness conditions. As a consequence, we establish the existence of global (in time) weak solutions on a bounded smooth domain in ℝ which are smooth everywhere with possible exceptions of finitely many singular times. © 2009 Springer-Verlag.


Wang S.,Southwest University | Feng J.,South China University of Technology | Tse C.K.,Hong Kong Polytechnic University
IEEE Signal Processing Letters | Year: 2014

In this letter, a new class of cubature Kalman filters (CKF) based on a spherical simplex-radial rule is proposed to further improve accuracy and efficiency of the traditional CKF. The transformation group of the regular simplex and the moment matching method are utilized to compute the spherical and radial integrals, respectively. In addition, with the increase of the state dimension, the new CKF of the fifth degree uses fewer quadrature points than the traditional CKF with the same degree. Simulations on moments calculation and nonlinear state estimation show that the proposed CKFs can achieve higher accuracy and better efficiency than the traditional CKFs. © 2013 IEEE.


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.


Hong B.,South China University of Technology | Shen J.,Virginia Institute of Marine Science
Journal of Geophysical Research: Oceans | Year: 2013

Dissolved oxygen (DO) replenishment in the bottom waters of an estuary depends on physical processes that are significantly influenced by external forcings. The vertical exchange time (VET) is introduced in this study to quantify the physical processes that regulate the DO replenishment in the Chesapeake Bay. A 3-D numerical model was applied to simulate the circulation, VET, and DO. Results indicate that VET is a suitable parameter for evaluating the bottom DO condition over both seasonal and interannual timescales. The VET is negatively correlated with the bottom DO. Hypoxia (DO <2 mg L -1) will develop in the Bay when VET is greater than 23 days in summer if mean total DO consumption rate is about 0.3 g O2 m -3 d-1. This critical VET value may vary around 23 days when the total DO consumption rate changes. The VET volume (volume of water mass with VET >23 days) can account for 77% of variations of hypoxic volume in the main Bay. The VET cannot explain all the DO variations as it can only account for the contribution of physical processes that regulate DO replenishment. It is found that the short-term vertical exchange process is highly controlled by the wind forcing. The VET volume decreases when the high-speed wind events are frequent. The summertime VET volume is less sensitive to short-term variations (pulses) of river discharge. It is sensitive to the total amount of river discharge and the high VET volume can be expected in the wet year. Key Points Vertical transport time is used to quantify bottom DO replenishment processes Majority variations of bottom DO can be interpreted by vertical transport time Interannual variations of hypoxic volume and VTT volume are correlated. ©2013. American Geophysical Union. All Rights Reserved.


Zhong H.C.,Xiamen University of Technology | Wang H.,South China University of Technology | Ouyang L.Z.,South China University of Technology
International Journal of Hydrogen Energy | Year: 2014

Supersaturated Mg(Al) solid solutions with reduced lattice constants were successfully prepared by ball milling Mg and Al powder mixtures. The microstructure and phase transition were investigated by XRD. The results indicated that disproportionation of supersaturated Mg(Al) solid solution to MgH2 and Al was caused by hydrogenation, then equilibrium Mg(Al) solid solution formed after dehydrogenation, while the intermetallic compound Mg17Al12 reversibly decomposed to MgH2 and intermediate phase Al3Mg2 which could further decompose to MgH2 and Al by hydriding. These reversible phase transitions make Mg-Al alloys show an observably lowered de/hydriding enthalpy and activation energy in comparison with pure Mg. © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserver.


Guo X.,Dalian University of Technology | Zhang W.S.,Dalian University of Technology | Wang M.Y.,Chinese University of Hong Kong | Wei P.,South China University of Technology
Computer Methods in Applied Mechanics and Engineering | Year: 2011

Considering stress-related objective or constraint functions in structural topology optimization problems is very important from both theoretical and application perspectives. It has been known, however, that stress-related topology optimization problem is challenging since several difficulties must be overcome in order to solve it effectively. Traditionally, SIMP (Solid Isotropic Material with Penalization) method was often employed to tackle it. Although some remarkable achievements have been made with this computational framework, there are still some issues requiring further explorations. In the present work, stress-related topology optimization problems are investigated via a level set-based approach, which is a different topology optimization framework from SIMP. Numerical examples show that under appropriate problem formulations, level set approach is a promising tool for stress-related topology optimization problems. © 2011 Elsevier B.V.


Tang Z.,South China University of Technology | Wu X.,Beijing University of Chemical Technology | Guo B.,South China University of Technology | Zhang L.,Beijing University of Chemical Technology | Jia D.,South China University of Technology
Journal of Materials Chemistry | Year: 2012

To fully exhibit the potentials of the fascinating characteristics of graphene oxide (GO) in polymer, the achievement of strong interface interactions and fine dispersion of GO in the hybrids is essential. In the present work, the elastomeric hybrids consisting of GO sheets are fabricated by utilizing butadiene-styrene-vinyl pyridine rubber (VPR) as the host through co-coagulation process and in situ formation of an ionic bonding interface. The VPR/GO composites with a normal hydrogen bonding interface are also prepared. The mechanical properties and gas permeability of these hybrids with an ionic bonding interface are obviously superior to those of the composites with a hydrogen bonding interface. With the ionic interfacial bonding, inclusion of 3.6 vol% of GO in VPR generates a 21-fold increase in glassy modulus, 7.5-fold increase in rubbery modulus, and 3.5-fold increase in tensile strength. The very fine dispersion of GO and the strong ionic interface in the hybrids are responsible for such unprecedented reinforcing efficiency of GO towards VPR. This work contributes new insights on the preparation of GO-based polymer hybrids with high performance. © 2012 The Royal Society of Chemistry.


Liu J.,South China University of Technology | Wu Y.,Design Institute of Guangzhou Metro Corporation
Energy and Buildings | Year: 2010

In order to investigate dynamic characteristic of underfloor air supply terminal unit, an IFV900A hot-wire anemometer was used to measure the corresponding velocity field. Turbulence intensity and power spectrum density exponent of air velocity signal were analyzed. The result showed that the outlet velocity distribution of underfloor air supply terminal unit was uniform. With increment of height, the velocity distribution trends to be uniform. Two velocity attenuation regions appear during airflow development. Turbulence intensity changes obviously with height. It is lower than that of mechanical wind. Turbulence intensity goes up with the increment of jetting distance. Power spectrum density exponent trends to the value of natural wind with increase of jetting distance and decrease of wind velocity. The exponent value approaches to the value of typical natural wind for the air velocity is 0.5 m/s under high supply air rate. With airflow diffusion, the fluctuation characteristic of airflow varies obviously with the jetting direction. The fluctuation characteristic of airflow changes to that of natural wind with the increase of height which can improve comfort of indoor environment. © 2010 Elsevier B.V. All rights reserved.


Chiqian Zhang and his team analyzed the results of approximately 300 published works on the subject of silver nanoparticles and wastewater. Credit: MU College of Engineering Silver nanoparticles have a wide array of uses, one of which is to treat drinking water for harmful bacteria and viruses. But do silver nanoparticles also kill off potentially beneficial bacteria or cause other harmful effects to water-based ecosystems? A new paper from a team of University of Missouri College of Engineering researchers says that's not the case. In their paper, "Governing factors affecting the impacts of silver nanoparticles on wastewater treatment," recently published in Science of the Total Environment, Civil and Environmental Engineering Department doctoral students Chiqian Zhang and Shashikanth Gajaraj and Department Chair and Professor Zhiqiang Hu worked with Ping Li of the South China University of Technology to analyze the results of approximately 300 published works on the subject of silver nanoparticles and wastewater. What they found was while silver nanoparticles can have moderately or even significantly adverse effects in large concentrations, the amount of silver nanoparticles found in our wastewater at present isn't harmful to humans or the ecosystem as a whole. "If the concentration remains low, it's not a serious problem," Zhang said. Silver nanoparticles are used in wastewater treatment and found increasingly in everyday products in order to combat bacteria. In terms of wastewater treatment, silver nanoparticles frequently react with sulfides in biosolids, vastly limiting their toxicity. Zhang said many of the studies looked at high concentrations and added that if, over time, the concentration rose to much higher levels of several milligrams per liter or higher), toxicity could become a problem. But he explained that it would take decades or even longer potentially to get to that point. "People evaluate the toxicity in a small-scale system," he said. "But with water collection systems, much of the silver nanoparticles become silver sulfide and not be harmful." Explore further: Soil increasingly at risk from household products


Liu F.,South China University of Technology | Liu F.,Guangxi University | Zhang W.-G.,South China University of Technology | Fu J.-H.,South China University of Technology
Information Sciences | Year: 2012

In analyzing a multiple criteria decision-making problem, the decision maker may express her/his opinions as an interval fuzzy or multiplicative preference relation. Then it is an interesting and important issue to investigate the consistency of the preference relations and obtain the reliable priority weights. In this paper, a new consistent interval fuzzy preference relation is defined, and the corresponding properties are derived. The transformation formulae between interval fuzzy and multiplicative preference relations are further given, which show that two preference relations, consistent interval fuzzy and multiplicative preference relations, can be transformed into each other. Based on the transformation formula, the definition of acceptably consistent interval fuzzy preference relation is given. Furthermore a new algorithm for obtaining the priority weights from consistent or inconsistent interval fuzzy preference relations is presented. Finally, three numerical examples are carried out to compare the results using the proposed method with those using other existing procedures. The numerical results show that the given procedure is feasible, effective and not requisite to solve any mathematical programing. © 2011 Elsevier Inc. All rights reserved.


Li F.,South China University of Technology | Du T.C.,Chinese University of Hong Kong
Decision Support Systems | Year: 2014

Social networks have become increasingly popular in recent years. Among the many social networking tools, micro-blogging is one of the most unique and convenient because it is short, responsive, spontaneous and mobile. These properties allow micro-blogs to move beyond basic information sharing and make them a popular media for sharing opinions. In this study, we examine the persuasiveness of micro-blogs by developing a framework that first identifies opinion leaders and then analyzes their persuasiveness. To develop the framework, we download micro-blogs, blogger information and the relationships among them into a database, identify spammers, decompose communities into sub-nets, identify opinion leaders and conduct persuasiveness analyses. The results show the framework can identify opinion leaders and their opinions effectively. It was found that negative opinions are less persuasive than positive opinions, and positive opinion leaders are more aggressive in distributing positive messages than negative opinion leaders are in distributing negative messages. © 2014 Elsevier B.V.


Wei Z.,South-Central University for Nationalities | Yang Q.,South China University of Technology
Nonlinear Dynamics | Year: 2012

A generalized Sprott C system with only two stable equilibria is investigated by detailed theoretical analysis as well as dynamic simulation, including some basic dynamical properties, Lyapunov exponent spectra, fractal dimension, bifurcations, and routes to chaos. In the parameter space where the equilibria of the system are both asymptotically stable, chaotic attractors coexist with period attractors and stable equilibria. Moreover, the existence of singularly degenerate heteroclinic cycles for a suitable choice of the parameters is investigated. Periodic solutions and chaotic attractors can be found when these cycles disappear. © 2011 Springer Science+Business Media B.V.


Ning Y.,South China University of Technology | Yang Y.,South China University of Technology | Wang C.,South China University of Technology | Ngai T.,Chinese University of Hong Kong | Tong Z.,South China University of Technology
Chemical Communications | Year: 2013

Novel polymeric microspheres with a hierarchical porous structure are facilely fabricated using double Pickering emulsion templates. This unique hierarchical porous structure makes them excellent candidates for adsorption and catalyst scaffold materials. © The Royal Society of Chemistry 2013.


Zhang W.-G.,South China University of Technology | Fu J.,South China University of Technology | Li H.,Chinese University of Hong Kong | Xu W.,South China University of Technology
International Journal of Production Economics | Year: 2012

This paper investigates how to coordinate a one-manufacturer-two-retailers supply chain with demand disruptions by revenue-sharing contracts. Firstly, we study the coordination of the supply chain without demand disruptions and give the feasible revenue-sharing contracts, which assure the desirability of the chain partners and the legality of selling. Next, we discuss how the supply chain is coordinated under one demand disruption. In the case, we analyze the effects of demand disruptions on the centralized supply chain and derive the coordinating revenue-sharing contracts. We also extend the theoretical results to the case of two demand disruptions. We find that it is harmful for the chain partners to keep the original revenue-sharing contracts without demand disruptions when there are demand disruptions. It is necessary to adjust the original revenue-sharing contracts to demand disruptions. Finally, some numerical examples are given to illustrate the theoretical results. © 2012 Elsevier B.V. All rights reserved.


Chen Y.,Key Laboratory of Polymer Processing Engineering | Yuan D.,South China University of Technology | Xu C.,South China University of Technology | Xu C.,Guangxi University
ACS Applied Materials and Interfaces | Year: 2014

We prepared a biobased material, dynamically vulcanized polylactide (PLA)/natural rubber (NR) blend in which the cross-linked NR phase owned a continuous network-like dispersion. This finding breaks the traditional concept of a sea-island morphology formed after dynamic vulcanization of the blends. The scan electron microscopy and dissolution/swell experiments provided the direct proof of the continuous cross-linked NR phase. This new biobased PLA/NR blend material with the novel structure is reported for the first time in the field of dynamic vulcanization and shows promise for development for various functional applications. © 2014 American Chemical Society.


Gong X.,South China University of Technology | Wang Z.,Chinese University of Hong Kong | Ngai T.,Chinese University of Hong Kong
Chemical Communications | Year: 2014

Non-covalent intermolecular forces, such as van der Waals, electrostatic, steric, and hydrophobic interactions, have played essential roles in determining the association, aggregation, adhesion and sedimentation processes of colloidal particles, surfactant micelles, and macromolecules, in solutions and biological systems. These interaction forces, however, are normally weak (


Ning Y.,South China University of Technology | Wang C.,South China University of Technology | Ngai T.,Chinese University of Hong Kong | Tong Z.,South China University of Technology
Langmuir | Year: 2013

This work presents a facile approach to produce a novel type of Janus microspheres with dual anisotropy of porosity and magnetism based on Pickering-type double emulsion templates. A stable aqueous Fe3O 4 dispersion-in-oil-in-water (WF/O/W) double Pickering emulsion is first generated by using hydrophobic silica and hydrophilic mesoporous silica particles as stabilizers. Janus microspheres with multihollow structure possessing magnetite nanoparticles concentrated on one side of the microspheres are obtained after polymerization of the middle oil phase of the double emulsion under a magnetic field. The resultant Janus microspheres are characterized by optical microscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray analysis (EDX). Moreover, we have systematically investigated the influences of Fe3O4 particle concentration, hydrophobic silica particle content, and volume ratio of the inner water phase to middle oil phase (WF/O) on the double emulsion formation and consequently on the structure of the resulting Janus microspheres. Our results show that the distribution of the multihollow structures within the prepared microspheres can be accurately tailored by adjusting the ratio of WF/O. In addition, the obtained Janus microsphere can be fairly orientated under a magnetic field, making them a potential candidate for synthesizing Janus membrane. © 2013 American Chemical Society.


Li T.,South China University of Technology | Guthrie J.T.,University of Leeds
Bioresource Technology | Year: 2010

The decoloration treatment of textile dye effluents through biodegradation, using bacterial cells, has been studied as a possible means of solving some of the problems that are associated with the pollution of water sources by colorants. In this paper, the use of whole bacterial cells of Shewanella J18 143 for the reduction of aqueous solutions of selected mono-azo, metal-complex dyes, namely Irgalan Grey GLN, Irgalan Black RBLN and Irgalan Blue 3GL, was investigated. The effects of temperature, pH and dye concentration on colour removal were also investigated and shown to be important. The operative conditions for the removal of colour were 30 °C, at pH 6.8, with a final dye concentration of 0.12 g/L in the colour reduction system. This study provides an extension to the application of Shewanella strain J18 143 bacterial cells in the decoloration of textile wastewaters. Crown Copyright © 2010.


Zhou G.,RIKEN | Cichocki A.,RIKEN | Zhao Q.,RIKEN | Xie S.,South China University of Technology
IEEE Signal Processing Magazine | Year: 2014

A common thread in various approaches for model reduction, clustering, feature extraction, classification, and blind source separation (BSS) is to represent the original data by a lower-dimensional approximation obtained via matrix or tensor (multiway array) factorizations or decompositions. The notion of matrix/tensor factorizations arises in a wide range of important applications and each matrix/tensor factorization makes different assumptions regarding component (factor) matrices and their underlying structures. So choosing the appropriate one is critical in each application domain. Approximate low-rank matrix and tensor factorizations play fundamental roles in enhancing the data and extracting latent (hidden) components. © 1991-2012 IEEE.


Li F.,South China University of Technology | Du T.C.,Chinese University of Hong Kong
Decision Support Systems | Year: 2011

Online social blogs have gained popularity recently. They provide an effective channel for word-of-mouth (WoM) marketing to promote products or service. In WoM marketing, an opinion leader, who is normally more interconnected and has a higher social standing, can deliver product information, provide recommendations, give personal comments, and supplement professional knowledge that help companies to promote their products. Many theories have been put forward about social networks, but few address the issue of opinion leader identification. This study proposes a framework to identify opinion leaders using the information retrieved from blog content, authors, readers, and their relationships, which we call BARR for short. We first build ontology for a marketing product and then collect parameters from BARR to identify "hot topics" related to the product. These hot topics are then associated with information disseminators, or opinion leaders. Marketers can use BARR to track blogs written by opinion leaders and identify their opinions to form effective marketing strategies. © 2010 Elsevier B.V. All rights reserved.


Liu H.,Guangxi University | Liu J.,South China University of Technology
Journal of Applied Crystallography | Year: 2012

Stereographic projection is one of the most powerful research tools for crystallography in materials science. A new program for full operation of stereographic projections and in-depth exploration of crystallographic orientation relationships is described. It is specifically designed for materials researchers who are in need of tools for extensive crystallographic analysis. The difference from other popular commercial software for crystallography is that this program provides new options for users to plot and fully control stereographic projections of an arbitrary pole centre for an arbitrary crystal structure and to illustrate composite stereographic projections, which are necessary to explore the orientation relationships between two phases. The program is able to perform a range of essential crystallographic calculations. © 2012 International Union of Crystallography Printed in Singapore-all rights reserved.


Yang Y.,South China University of Technology | Tong Z.,South China University of Technology | Ngai T.,Chinese University of Hong Kong | Wang C.,South China University of Technology
ACS Applied Materials and Interfaces | Year: 2014

Effective removal of crude oils, petroleum products, organic solvents, and dyes from water is of significance in oceanography, environmental protection, and industrial production. Various techniques including physical and chemical absorption have been developed, but they suffer from problems such as low separation selectivity, a complicated and lengthy process, as well as high costs for reagents and devices. We present here a new material, termed nitrogen-rich carbon aerogels (NRC aerogels,) with highly porous structure and nitrogen-rich surfaces, exhibiting highly efficient separation of specific substances such as oils and organic pollutants. More importantly, we demonstrate that the fabricated NRC aerogels can also collect micrometer-sized oil droplets from an oil-water mixture with high efficiency that is well beyond what can be achieved by most existing separation methods, but is extremely important in practical marine oil-spill recovery because a certain amount of oils often shears into many micrometer-sized oil droplets by the sea wave, resulting in enormous potential destruction to marine ecosystem if not properly collected. Furthermore, our fabricated material can be used like a recyclable container for oils and chemicals cleanup because the oil/chemical-Absorbed NRC aerogels can be readily cleaned for reuse by direct combustion in air because of their excellent hydrophobicity and fire-resistant property. We demonstrate that they keep 61.2% absorption capacity even after 100 absorption/combustion cycles, which thus has the highest recyclability of the reported carbon aerogels. All these features make these fabricated NRC aerogels suitable for a wide range of applications in water purification and treatment. © 2014 American Chemical Society.


Liu Y.P.,South China University of Technology | Reddy J.N.,Texas A&M University
International Journal of Structural Stability and Dynamics | Year: 2011

A nonlocal Timoshenko curved beam model is developed using a modified couple stress theory and Hamilton's principle. The model contains a material length scale parameter that can capture the size effect, unlike the classical Timoshenko beam theory. Both bending and axial deformations are considered, and the Poisson effect is incorporated in the model. The newly developed nonlocal model recovers the classical model when the material length scale parameter and Poisson's ratio are both taken to be zero and the straight beam model when the radius of curvature is set to infinity. In addition, the nonlocal BernoulliEuler curved beam model can be realized when the normal cross-section assumption is restated. To illustrate the new model, the static bending and free vibration problems of a simply supported curved beam are solved by directly applying the formulas derived. The numerical results for the static bending problem reveal that both the deflection and rotation of the simply supported beam predicted by the new model are smaller than those predicted by the classical Timoshenko curved beam model. Also, the differences in both the deflection and rotation predicted by the current and classical Timoshenko model are very large when the beam thickness is small, but they diminish with the increase of the beam height. Similar trends are observed for the free vibration problem, where it is shown that the natural frequency predicted by the nonlocal model is higher than that by the classical model, and the difference between them is significantly large only for very thin beams. These predicted trends of the size effect at the micron scale agree with those observed experimentally. © 2011 World Scientific Publishing Company.


Liu S.-Q.,South China University of Technology | Hu B.-J.,South China University of Technology | Wang X.-Y.,China Research Institute of Radio Wave Propagation
IEEE Communications Letters | Year: 2012

In this letter, we consider hierarchical cooperative spectrum sensing based on two-threshold energy detection in cognitive radio networks. In order to solve the sensing failure problem in conventional two-threshold energy detection, soft combination of the observed energy value from different cognitive radio users is investigated. Encouraged by the performance gain of soft combination of energy falling between the two thresholds, we further propose a new softened hard combination scheme to reduce the communication overhead. Results show that the proposed method achieves a good tradeoff between sensing performance and communication overhead. © 2012 IEEE.


Wong A.,University of Toronto | Guo Y.,University of Toronto | Guo Y.,South China University of Technology | Parka C.B.,University of Toronto
Journal of Supercritical Fluids | Year: 2013

This study aims to elucidate the fundamental mechanisms of extensional stress-induced foaming phenomena by in situ observation of polypropylene foaming processes using a view-cell system. The foaming processes of polypropylene blown with supercritical carbon dioxide have been observed under static conditions as well as dynamic conditions where extensional strains were applied. A bubble growth-induced cell nucleation phenomenon, where existing cells triggered the generation of cells around them, was observed under static conditions due to the presence of crystals. In the dynamic cases, the applied extensional stresses caused foaming to occur in a more dispersed manner. The bubble growth-induced cell nucleation phenomenon was also observed, but it occurred at a later stage and the effect was less dominant. These fundamental understandings will provide guidance to improve processing strategies of plastic foaming processes. © 2013 Elsevier B.V. All rights reserved.


Zhao L.-C.,Northwest University, China | Ling L.,South China University of Technology
Journal of the Optical Society of America B: Optical Physics | Year: 2016

We study the relations between modulational instability and several well-known nonlinear excitations in a nonlinear fiber such as bright soliton, nonlinear continuous wave, Akhmediev breather, Peregrine rogue wave, and Kuznetsov-Ma breather. We present a quantitative correspondence between them based on the dominant frequency and propagation constant of each perturbation on a continuous-wave background. We especially demonstrate that rogue wave comes from modulational instability with the resonance perturbation on continuouswave background. The numerical simulations are performed to test these theoretical results. These results will deepen our understanding of rogue wave excitation and be helpful for controllable nonlinear wave excitations in nonlinear fiber and other nonlinear systems. © 2016 Optical Society of America.


Wu F.,Shantou University | Zhang X.,South China University of Technology
Robotics and Computer-Integrated Manufacturing | Year: 2014

In order to improve the comprehensive performance of solder joints inspection in three aspects, i.e. high recognition rate, detailed classification of defect types and fast inspection speed, a new detection and classification algorithm of the chip solder joints based on color grads and Boolean rules is developed in this paper. Firstly, the region features, evaluation features and color grads' features are defined and extracted based on the special solder joint image, which is acquired by a particular image acquisition system composed of a 3-CCD color digital camera and a 3-color (red, green, and blue) hemispherical LED array illumination. Secondly, the models of solder joint types are built based on extracted features and statistical characteristics of solder joint types. Thirdly, the detection and classification method is designed and presented using Boolean rules, then eight common solder joint types, including the acceptable solder joint, pseudo, no solder, lacked solder, excess solder, shifted, tombstone, and miss component, can be classified and detected by the proposed algorithm. Fourthly, the proposed algorithm is optimized to improve the inspection speed based on a parallel computing method. Finally, to evaluate the performance of the proposed method, 79 pieces of PCBs with defects were inspected by the commercial AOI system developed by the authors which integrates the proposed algorithm. Experiment and result analysis illustrates that the proposed method is better than other methods in three aspects, it can detect and classify properly all the eight common types of solder joints, its detailed classification, and high correct rate, which is up to 97.7%, are more useful to the quality control in the manufacturing process, and its inspection speed is faster, thus helping us to improve the efficiency of the manufacturing process. © 2014 Published by Elsevier Ltd. All rights reserved.


Lu C.,Ohio State University | Zhao J.,Ohio State University | Yang S.-T.,Ohio State University | Wei D.,Ohio State University | Wei D.,South China University of Technology
Bioresource Technology | Year: 2012

Concentrated cassava bagasse hydrolysate (CBH) containing 584.4. g/L glucose was studied for acetone-butanol-ethanol (ABE) fermentation with a hyper-butanol-producing Clostridium acetobutylicum strain in a fibrous bed bioreactor with gas stripping for continuous butanol recovery. With periodical nutrient supplementation, stable production of n-butanol from glucose in the CBH was maintained in the fed-batch fermentation over 263. h with an average sugar consumption rate of 1.28. g/L. h and butanol productivity of 0.32 ± 0.03. g/L. h. A total of 108.5. g/L ABE (butanol: 76.4. g/L, acetone: 27.0. g/L, ethanol: 5.1. g/L) was produced, with an overall yield of 0.32 ± 0.03. g/g glucose for ABE and 0.23 ± 0.01. g/g glucose for butanol. The gas stripping process generated a product containing 10-16% (w/v) of butanol, ∼4% (w/v) of acetone, a small amount of ethanol (<0.8%) and almost no acids, resulting in a highly concentrated butanol solution of ∼64% (w/v) after phase separation. © 2011 Elsevier Ltd.


Ling L.,South China University of Technology | Zhao L.-C.,Northwest University, China
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2013

We present a simple representation for arbitrary-order rogue wave solution and a study on the trajectories of them explicitly. We find that the trajectories of two valleys on whole temporal-spatial distribution all look "X" -shaped for rogue waves. Additionally, we present different types of high-order rogue wave structures, which could be helpful towards realizing the complex dynamics of rogue waves. © 2013 American Physical Society.


Ling L.,South China University of Technology | Zhao L.-C.,Northwest University, China | Guo B.,CAS Beijing Institute of Applied Physics And Computational Mathematics
Nonlinearity | Year: 2015

In this paper, we obtain a uniform Darboux transformation for multi-component coupled nonlinear Schrödinger (NLS) equations, which can be reduced to all previously presented Darboux transformations. As a direct application, we derive the single dark soliton and multi-dark soliton solutions for multi-component NLS equations with a defocusing case and a mixed focusing and defocusing case. Some exact single and two-dark solitons of three-component NLS equations are investigated explicitly. The results are meaningful for vector dark soliton studies in many physical systems, such as Bose-Einstein condensate, nonlinear optics, etc. © 2015 IOP Publishing Ltd & London Mathematical Society.


Jiang Z.-H.,South China University of Technology | Jiang Z.-H.,CAS Shanghai Institute of Optics and fine Mechanics | Zhang Q.-Y.,South China University of Technology
Progress in Materials Science | Year: 2014

Glass is considered a vitreous supercooled liquid that is in a thermodynamically metastable state between the molten liquid state and the crystalline state. Different glass structures are influenced by the thermal history of the cooling process. In 1932, Zachariasen established the continuous random network (CRN) paradigm for the structure of glass in which the random structure of glass is similar to that of liquid. Prior to Zachariasen, diffraction patterns observed by Lebedev indicated that glass structures are comprised of microcrystallites approximately 20 Å in size. According to the microcrystalline hypothesis, these microcrystallite domins are linked by amorphous interlayers. This debate on the predominant feature of glass structure (i.e. whether it exists in an ordered state) has lasted for more than half a century. Great efforts have been invested to develop a universal model to represent all glass structures. However, the concept of a universal structure model is incompatible with the fact that the vitreous state is in a thermodynamically metastable state because a specific structure can only arise in a thermodynamically stable state. To date, theories proposed on glass structures are based on various models rather than on the variability and diversity of glass structures in thermodynamically metastable states. The American Society for Testing and Materials (ASTM) International defines glass as "an inorganic product of fusion which has cooled to a rigid condition without crystallizing." Therefore, glass structures lie between a melt state and a glassy state which may have undetectable microcrystalline domains. The gradual transformation from glass to crystal is controlled by local fluctuations in the structural order, the formation of a nucleus, and crystal growth. A fuzzy mathematical method can distinguish between glass and crystal better than a logical criterion based on a quantitative volume limitation. Therefore, the controversy surrounding the aforementioned hypotheses by Zachariasen and Lebedev lies in the estimation of the degree of order or disorder, i.e., whether the structure of glass is more ordered ("microcrystallite" hypothesis) or more disordered ("random network" hypothesis). While whether or not glass is an ordered state has long been a topic of debate, the structure-properties relationships are not much addressed. In recent years, we propose a phase diagram model that effectively explains various glass structures. Based on infrared spectroscopy, Raman and nuclear magnetic resonance (NMR) measurements, as well as the physical properties of relevant compounds in phase diagrams (e.g. density and refractive index), we conclude that glasses and crystalline congruent compounds exhibit similar NMR data and spectral features in a phase diagram. Thus, it is reasonable to consider glass as a product of mixed melts of nearest-neighbor congruent compounds in a phase diagram. Most importantly, the properties of glass can be calculated via the lever rule by applying the additive properties that can predict the structural units of glass with mutually miscible or immiscible phases. Based on NMR data, we are capable of predicting glass properties by employing the phase diagram model using data on congruent compounds through the additive properties of several binary and ternary borate systems such as Li2O3-B2O3, Na 2O-B2O3, K2O3-B 2O3, BaO-B2O3, La2O 3-B2O3, Na2O-B2O 3-V2O5, Na2O-B2O 3-GeO2, Na2O-B2O3-MgO and K2O-B2O3-Al2O3. The authors also calculated the [BO4]/[B2O3] ratios in binary and ternary borate systems. The calculated results confirm the experimental data. Moreover, estimates based on the refractive index and density using the same model, are also well consistent with the experimental data. For some other glass systems where NMR could not be used, e.g., the Na 2O-CaO-SiO2 system, the refractive index and density calculated from the nearest congruent compounds match well with the experimental data. Further, this approach can be used to determine the relationship between glass compositions and properties in multi-component glass systems. This review summarizes the recent progress made in understanding glass structure and describes the technological developments driven by this new information. The review is organized as follows: Sections 1-4 introduce the classical approaches to understanding glass structure, outline the fundamental thermodynamic characteristics of glass, discuss the Krogh-Moe's structural model approach, summarize measurements of glasses using IR, Raman and NMR spectral measurements, and introduce the basics of the phase diagram structural model of glass. Section 5 presents a detailed description of the phase diagram structural model of glass, a universal analytical model from the thermodynamic perspective, the phase diagram, and spectral measurements that elucidate the new structural model of glass and its relevant novel physical and chemical properties. Section 6 discusses the phase diagram structural model of silicate glass and other oxide glass systems, as well as their properties. Finally, Section 7 discusses the universal character of the phase diagram structural model for glass from both the thermodynamic and phase diagram kinetic perspectives. The conclusions of this review are then summarized in Section 8, which include: (1) the vitreous state is in a thermodynamic metastable state, and a fuzzy mathematical method is better to distinguish glass from crystal than a logical criterion of quantitative volume limitation. Neither the "crystalline" hypothesis nor the "random network" hypothesis is a universal structural model for glass. (2) Glasses and crystalline congruent compounds in a phase diagram exhibit similar NMR data and spectral structures. (3) In a phase diagram structural approach, binary glass is considered to be a mixture of the melts of the two nearest congruent compounds in a binary phase diagram. The structures and properties of glass can be predicted and calculated from the properties of the two congruent compounds by applying the lever rule. (4) Ternary glass is composed of a mixture of the three nearest congruent compounds in a ternary phase diagram. The structures and properties of the resulting glass can be predicted and calculated from the characteristics of the three congruent compounds. (5) In addition to borate and silicate glasses, the phase diagram structure approach could be applied to chalcogenide, halogenide, and metallic glasses. © 2013 Elsevier Ltd. All rights reserved.


Deng G.,South China University of Technology | Tang C.,South China University of Technology | Li F.,South China University of Technology | Jiang H.,South China University of Technology | Chen Y.,CAS Institute of Chemistry
Macromolecules | Year: 2010

A strategy of constructing novel reversible polymer gels based on dynamic covalent chemistry. Covalent and reversible noncovalent interactions are two basic cross-linking forces to form three- dimensional networks in polymer gels. The networks based on covalent bonds in chemical gels are stable under ambient conditions owing to their robust and irreversible natures of the covalent bonds. Dynamic covalent chemistry offers an appealing prospect of constructing such materials. The chemical gel possesses self-healing property based on the reversible breaking and regenerating of acylhydrazone bonds. The dynamic polymer gels formed as well in other solvents such as ethanol, DMSO and CH 2Cl2. These gels were covalent cross-linked and revealed typical properties of chemical gels. The present discovery indicates that dynamic polymer gels may have a broad application as smart soft materials.


Guo X.,CAS Institute of Chemistry | Guo X.,University of Chinese Academy of Sciences | Zhang M.,CAS Institute of Chemistry | Ma W.,North Carolina State University | And 7 more authors.
Advanced Materials | Year: 2014

For the blend film of PBDTTT-C-T:PC71BM, the use of 1,8-diiodooctane as the solvent additive enriches the polymer at the top surface, so that a power conversion efficiency of 9.13% is recorded in the inverted polymer solar cell based on the blend, which is much higher than that of the device with conventional structure. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Xie Y.,South China University of Technology | Zhou J.,South China University of Technology | Jiang S.,University of Washington
Journal of Chemical Physics | Year: 2010

In this work, the parallel tempering Monte Carlo (PTMC) algorithm is applied to accurately and efficiently identify the global-minimum-energy orientation of a protein adsorbed on a surface in a single simulation. When applying the PTMC method to simulate lysozyme orientation on charged surfaces, it is found that lysozyme could easily be adsorbed on negatively charged surfaces with "side-on" and "back-on" orientations. When driven by dominant electrostatic interactions, lysozyme tends to be adsorbed on negatively charged surfaces with the side-on orientation for which the active site of lysozyme faces sideways. The side-on orientation agrees well with the experimental results where the adsorbed orientation of lysozyme is determined by electrostatic interactions. As the contribution from van der Waals interactions gradually dominates, the back-on orientation becomes the preferred one. For this orientation, the active site of lysozyme faces outward, which conforms to the experimental results where the orientation of adsorbed lysozyme is co-determined by electrostatic interactions and van der Waals interactions. It is also found that despite of its net positive charge, lysozyme could be adsorbed on positively charged surfaces with both "end-on" and back-on orientations owing to the nonuniform charge distribution over lysozyme surface and the screening effect from ions in solution. The PTMC simulation method provides a way to determine the preferred orientation of proteins on surfaces for biosensor and biomaterial applications. © 2010 American Institute of Physics.


Tang S.,Umeå University | Tan W.-Y.,South China University of Technology | Zhu X.-H.,South China University of Technology | Edman L.,Umeå University
Chemical Communications | Year: 2013

We demonstrate that non-ionic small molecules (SMs) can function as the doping and emissive compound in light-emitting electrochemical cells (LECs), and that high brightness and decent efficiency can be attained for such devices. It is plausible that the expansion of the LEC library, to include easy-to-purify and tunable non-ionic SM compounds, could represent a viable path towards improved LEC devices. This journal is © The Royal Society of Chemistry.


Cao D.,South China University of Technology | Meier H.,South China University of Technology | Meier H.,University of Mainz
Asian Journal of Organic Chemistry | Year: 2014

Since 2008 a new field of supramolecular chemistry has developed rapidly: the chemistry of pillar[n]arenes. These "younger brothers and sisters" of calixarenes are conveniently accessible and extremely guest-friendly. Guests from many different classes of organic compounds are welcome. Nevertheless, a high selectivity for the threading of guest molecules in the macrocyclic cavities can be achieved. The complex stability is characterized by association constants Ka between 10 and 1×108M-1. The rate constants of the threading vary over several orders of magnitude. The focus of this article lies on the preparation (sections2 and 3) and the structures (section4) of pillar[n]arenes (n=5-10) in solution and in the solid state. A further important point concerns the complexation and its selectivity (section5). Only some new or outstanding examples are discussed in section6 on self-assembly and aggregation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Luo H.,Leibniz University of Hanover | Efimov K.,Leibniz University of Hanover | Jiang H.,Leibniz University of Hanover | Feldhoff A.,Leibniz University of Hanover | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2011

Cleaning up their act: A novel CO2-stable and cobalt-free dual-phase membrane for oxygen separation from air has been developed that consists of 40 wt % NiFe2O4 and 60 wt % Ce 0.9Gd0.1O2-δ. This membrane shows a steady oxygen permeation flux over 100 h using CO2 as sweep gas at 1000 °C. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Su S.-J.,South China University of Technology | Su S.-J.,Yamagata University | Cai C.,Yamagata University | Kido J.,Yamagata University
Chemistry of Materials | Year: 2011

A series of host materials 1 - 7 containing various heterocyclic cores, like pyridine, pyrimidine, and pyrazine, were developed for RGB phosphorescent organic light-emitting diodes (OLEDs). Their energy levels can be tuned by the change of heterocyclic cores and their nitrogen atom orientations, and decrease of singlet - triplet exchange energy (ΔEST) was achieved with introducing one or two nitrogen atoms into the central arylene; this is also consistent with density functional theory calculations. Their carrier mobilities can also be tuned by the choice of heterocyclic cores, giving improved bipolarity compared with that without any heterocyclic cores. Due to the high triplet energy level of the developed host materials, well confinement of triplet excitons of blue emitter iridium(III) bis(4,6-(difluorophenyl) pyridinato-N,C2′) picolinate (FIrpic) was achieved except for 7 due to its low ET. In contrast, triplet energy can be well confined on green emitter fac-tris(2-phenylpyridine) iridium (Ir(PPy)3) and red emitter tris(1-phenylisoquinolinolato-C2,N)iridium(III) (Ir(piq)3) for all the hosts, giving comparable lifetime (τ), photoluminescent quantum efficiency (ηPL), and radiative and nonradiative rate constants (kr and knr). Highly efficient blue and green phosphorescent OLEDs were achieved for 2, exhibiting one of the highest ever efficiencies to date, especially at much brighter luminance for lighting applications. In comparison, the highest efficiencies hitherto were achieved for the red phosphorescent OLED based on 6, which can be attributed to its lower-lying LUMO level and the smallest ΔEST, giving improved electron injection and carrier balance. Different from the blue and green phosphorescent OLEDs based on FIrpic and Ir(PPy)3, the host materials with lower-lying LUMO levels seem to be better hosts for a red emitter Ir(piq)3, achieving improved efficiency and reduced efficiency roll-off at high current density. © 2010 American Chemical Society.


Ma H.,University of Washington | Yip H.-L.,University of Washington | Huang F.,University of Washington | Huang F.,South China University of Technology | Jen A.K.-Y.,University of Washington
Advanced Functional Materials | Year: 2010

The field of organic electronics has been developed vastly in the past two decades due to its promise for low cost, lightweight, mechanical flexibility, versatility of chemical design and synthesis, and ease of processing. The performance and lifetime of these devices, such as organic light-emitting diodes (OLEDs), photovoltaics (OPVs), and field-effect transistors (OFETs), are critically dependent on the properties of both active materials and their interfaces. Interfacial properties can be controlled ranging from simple wettability or adhesion between different materials to direct modifications of the electronic structure of the materials. In this Feature Article, the strategies of utilizing surfactant-modified cathodes, hole-transporting buffer layers, and self-assembled monolayer (SAM)-modified anodes are highlighted. In addition to enabling the production of high-efficiency OLEDs, control of interfaces in both conventional and inverted polymer solar cells is shown to enhance their efficiency and stability; and the tailoring of source-drain electrode-semiconductor interfaces, dielectric-semiconductor interfaces, and ultrathin dielectrics is shown to allow for high-performance OFETs. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA.


Meier H.,University of Mainz | Cao D.,South China University of Technology
Chemical Society Reviews | Year: 2013

The dimerization of anthracene by a [4π + 4π] cycloaddition is one of the oldest and best known reactions in photochemistry. In the series of tethered bichromophoric arenes, this reaction type could be extended to anthracene-naphthalene, naphthalene-naphthalene and recently even to anthracene-benzene and naphthalene-benzene systems. Cyclophanes, which can be regarded as twofold or multiple tethered systems, are not discussed here. The cycloisomerizations are performed by irradiation at the long-wavelength absorption (λ > 270 nm), whereas shorter wavelengths (λ < 270 nm) lead to cycloreversions, which can be also achieved by a thermal route. The systems represent therefore a P- and T-type photochromism, which can be used for optical or chiroptical switches. An acceleration of the switch is possible by a singlet energy transfer (light harvesting antenna effect) in dendritic compounds. In the past 5 to 10 years many applications of these switches were studied in the context of photonic devices, sensor techniques, lithographic processes, imaging techniques, data processing and data storage.


Liu H.-Y.,South China University of Technology | Mahmood M.H.R.,South China University of Technology | Mahmood M.H.R.,University of Education of Pakistan | Qiu S.X.,CAS South China Botanical Garden | Chang C.K.,Michigan State University
Coordination Chemistry Reviews | Year: 2013

Among metallocorroles, manganese corrole chemistry is one that has flourished prominently in recent years. Numerous manganese corroles have been reported in which the oxidation state of the central manganese ranges from +3 to +6. Manganese(III) corroles are the most common form of stable Mn-corrole complexes. High-valent manganese corroles exhibit quite different spectroscopic and electrochemical properties compared with manganese(III) corroles. (Imido)manganese(V) and (nitrido)manganese(V) corroles are stable enough to be well characterized by spectroscopy. (Oxo)manganese(V) corroles may be prepared by chemical or laser flash photolysis methods, and are important mechanistic probes for oxygen atom transfer reactions in the catalytic oxidation of alkenes. While various (oxo)manganese complexes have been synthesized and extensively studied, the factors controlling their reactivity are not completely understood, suggesting that manganese corrole-mediated oxidation reactions have room for further exploration. In this review, recent advances in the field of manganese corroles are summarized. © 2013 Elsevier B.V.


Wu J.,South China University of Technology | Yang Z.,South China University of Technology | Wu Q.,Danfoss Sanhua Hangzhou Micro Channel Heat Exchanger Co. | Zhu Y.,Parsons Brinckerhoff
Applied Energy | Year: 2012

At low ambient temperature, air-source heat pump water heater suffers from decrease of both heating capacity and coefficient of performance, and increase in compressor's pressure ratio and discharge temperature. A cascade air-source heat pump water heater with phase change material (PCM) for thermal storage application was designed to ensure the reliable operation under various weather conditions and enhance the system performance at low ambient temperature. Dynamic experiments were carried out under various operating conditions in accordance with China National Standard GB/T23137-2008. Transient operating characteristics were adopted to analyze the performance of cascade heat pump system. Dynamic performance of the heat pump water heater in single stage mode and cascade mode was compared and discussed. The heating COP values in single stage mode ranged from 1.5 to 3.05, while in cascade mode, the heating COP values ranged from 1.74 to 2.55. Based on the transient heating COP values, critical switching curve from single stage mode to cascade mode was founded for the code of the system controller. Furthermore, energy performance between water tanks with and without PCM was compared to clarify the contribution of PCM. © 2011 Elsevier Ltd.


Su S.-J.,South China University of Technology | Sasabe H.,Optoelectronic Industry and Technology Development Association | Pu Y.-J.,Yamagata University | Nakayama K.-I.,Yamagata University | And 2 more authors.
Advanced Materials | Year: 2010

(Figure Presented) A serles of 1,3,5-triazine-core-containing electron-transport materials (ETMs) are reported as an undoped electron-transport layer (ETL), whose energy levels can be tuned by introducing pyridine rings on the periphery of the molecule and also orientation of nitrogen. An unprecedented low operating voltage of 2.42 V, corresponding to the emitting photon energy (hv), was achieved for the fac-tris(2-phenylpyridine) iridium (lr(PPy)3) based green phosphorescent OLEDs at 100 cd m-2 without consumption of their efficiency. Moreover, the threshold voltage for electroluminescence can be even 0.1 - 0.2 V lower than the minimum value of hv/e. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Su S.-J.,South China University of Technology | Cai C.,Yamagata University | Takamatsu J.,Yamagata University | Kido J.,Yamagata University
Organic Electronics: physics, materials, applications | Year: 2012

A host material containing a triazine core and three phenylcarbazole arms, called 2,4,6-tris(3-(carbazol-9-yl)phenyl)-triazine (TCPZ), was developed for phosphorescent organic light-emitting diodes (OLEDs). Ultra-low driving voltages were achieved by utilizing TCPZ as the host due to its decreased singlet-triplet exchange energy (ΔE ST) and low-lying lowest unoccupied molecular orbital (LUMO) energy level. Interaction between the RGB triplet emitters and TCPZ were studied in both photoluminescent and electroluminescent processes. Transient photoluminescence (PL) measurement of the co-deposited film of fac-tris(2-phenylpyridine) iridium (Ir(PPy) 3):TCPZ exhibits a shoulder at 565 nm whose lifetime is about two times longer than that of the Ir(PPy) 3 triplet excitons and can be attributed to the triplet exciplex formed between Ir(PPy) 3 and TCPZ. Such exciplex was also found for the green phosphorescent OLED, giving the most efficient phosphorescent OLED with triplet exciplex emission hitherto. Different from the PL process, a broad featureless band with a maximum at 535 nm was found for the OLED based on an EML of iridium(III) bis(4,6-(di-fluorophenyl) pyridinato-N,C 2′)picolinate (FIrpic):TCPZ, which can be attributed to the emission from the singlet excited state of TCPZ formed by direct hole-electron recombination. A multi-emitting-layer white OLED was also fabricated by utilizing FIrpic and tris(1-phenylisoquinolinolato-C 2,N)iridium(III) (Ir(piq) 3) as the complementary triplet emitters and TCPZ as the host. Different from most of ever reported white OLEDs fabricated with blue/red complementary triplet emitters that exhibit color rendering index (CRI) lower than 70, a high CRI of 82 is achieved due to the combination of blue and red phosphorescence emissions from FIrpic and Ir(piq) 3, and the emerging green fluorescence emission from TCPZ. © 2012 Elsevier B.V. All rights reserved.


Su S.-J.,South China University of Technology | Cai C.,Yamagata University | Kido J.,Yamagata University
Journal of Materials Chemistry | Year: 2012

A series of three-carbazole-armed host materials containing various arylene cores, like benzene (1,3,5-tris(3-(carbazol-9-yl)phenyl)-benzene, TCPB), pyridine (2,4,6-tris(3-(carbazol-9-yl)phenyl)-pyridine, TCPY), and pyrimidine (2,4,6-tris(3-(carbazol-9-yl)phenyl)-pyrimidine, TCPM), were developed for red, green, and blue phosphorescent organic light-emitting diodes (OLEDs). An intramolecular charge transfer was observed for TCPY and TCPM with heterocyclic cores of pyridine and pyrimidine, giving bathochromic shifts in the photoluminescent spectrum and reduced energy band gaps in comparison with TCPB with a benzene core. In addition, lower energy singlet and triplet excited states, reduced lowest unoccupied molecular orbital (LUMO) energy level, smaller singlet-triplet exchange energy (ΔE ST), and improved bipolarity were also achieved with introducing heterocycles of pyridine and pyrimidine instead of benzene. In contrast to the slightly decreased triplet energy (E T), a significantly decreased ΔE ST was achieved by introducing heterocycles of pyridine and pyrimidine as the core, and the more nitrogen atoms in the central heterocycle, the smaller ΔE ST is achieved. Reduced driving voltages were achieved for the green and red phosphorescent OLEDs by utilizing TCPY and TCPM as the host due to their decreased ΔE ST and lower-lying LUMO energy level, proving that more carriers must be injected into the emitting layer through the host molecules rather than direct carrier trapping by the dopant. Moreover, improved efficiency and suppressed efficiency roll-off were also achieved for the green and red phosphorescent OLEDs based on TCPY and TCPM due to their improved bipolarity and thus improved carrier balance. © 2012 The Royal Society of Chemistry.


Cao D.,South China University of Technology | Peng J.,South China University of Technology | Hong Y.,South China University of Technology | Fang X.,South China University of Technology | And 2 more authors.
Organic Letters | Year: 2011

Double donor-acceptor (D-A) branched dyes (DBD) with a phenothiazine unit as electron donor and a 2-cyanoacrylic acid unit as electron acceptor were synthesized and used as sensitizers for solar cells (DSSCs). The conversion efficiency of the DSSCs amounts up to 4.22% (2.91% for the single D-A branched dye) under AM 1.5 G irradiation. The results show that the performance of DSSCs can be effectively enhanced by the cooperation of two donor-acceptor containing branches in one molecule of the dyes. © 2011 American Chemical Society.


Sun H.-T.,Soochow University of China | Sun H.-T.,Hokkaido University | Zhou J.,China Jiliang University | Zhou J.,Zhejiang University | Qiu J.,South China University of Technology
Progress in Materials Science | Year: 2014

Bismuth is one of the most thoroughly investigated main group elements, which has been regarded as 'the wonder metal' because of its diverse oxidation states and profound propensities to form bismuth clusters, resulting from the easy involvement in chemical combinations for the electrons in the p orbital. This peculiarity allows them to behave as smart optically active centers in diverse host materials. Remarkable progress in the research of bismuth activated photonic materials has been seen over the last ten years owing to their unique properties and important applications in areas of telecommunication, biomedicine, white light illumination and lasers. The aim of this review is to present a critical overview of the current state of the art in bismuth activated photonic materials, their features, advantages and limitations as well as the future research trends. We first shortly introduce the fundamental properties of bismuth element including principles of bismuth-related luminescence and characterization techniques available. This is followed by a detailed discussion on the recent progress in the synthesis and characterization of bismuth-activated photonic materials, with an emphasis on material systems emitting in the near-infrared (NIR) spectral region. Furthermore, we describe the representative achievements regarding their prospective applications in broadband NIR optical amplifiers, fiber lasers, bioimaging, and white light-emitting diodes. Finally, we point out what key scientific questions remain to be answered, and present our perspectives on future research trends in this exciting field of sciences. © 2014 Elsevier Inc. All rights reserved.


Wu J.,Soochow University of China | Zhou F.,South China University of Technology
Nonlinearity | Year: 2012

In this paper we investigate non-radial stationary solutions of a free boundary problem modelling tumour growth under the action of inhibitors. The model consists of two elliptic equations describing the concentration of nutrients and inhibitors, respectively, and a Stokes equation for the velocity of tumour cells and internal pressure. The ratio μ/γ of the proliferation rate μ and the cell-to-cell adhesiveness γ plays the role of the bifurcation parameter. We prove that in certain situations there exists a positive sequence such that for each (μ/γ) n(n even n *) there exist non-radial stationary solutions bifurcating from the radial stationary solution, while in the other situations there exists at most a finite number of bifurcation points. This is a remarkable difference from the corresponding inhibitor-free model where there always exist infinitely many branches of non-radial stationary bifurcation solutions. Our analysis also indicates that inhibitor supply may lower the ability of tumour invasion, and even make the tumour unaggressive and stable. © 2012 IOP Publishing Ltd & London Mathematical Society.


Xie Z.,Guangzhou Academy of Energy Testing and Inspection | Ma X.,South China University of Technology
Bioresource Technology | Year: 2013

The thermal characteristics and kinetics of paper sludge, rice straw and their blends were evaluated under combustion condition. The paper sludge was blended with rice straw in the range of 10-95. wt.% to investigate their co-combustion behaviour. There was significant interaction between rice straw and paper sludge in high temperature. The combustion of paper sludge and rice straw could be divided into two stages. The value of the activation energy obtained by the Friedman and the Ozawa-Flynn-Wall (OFW) first decreased and then increased with the conversion degree rising. The average activation energy did not monotonically decrease with increasing the percentage of rice straw in the blends. When the percentage of rice straw in the blends was 80%, the value of the average activation energy was the smallest, which was 139. kJ/mol obtained by OFW and 132. kJ/mol obtained by Friedman, respectively. © 2013 Elsevier Ltd.


Liu J.,Hong Kong Polytechnic University | Cheng K.W.E.,Hong Kong Polytechnic University | Zeng J.,South China University of Technology
IEEE Transactions on Industrial Electronics | Year: 2014

High frequency alternating current (HFAC) has already been applied in many power distribution systems due to outstanding merits. The circulation current control of the high frequency resonant inverter in parallel connection is more complicated than the low frequency counterpart. Methods from topology, modulation, and control perspectives have already been proposed; however, most of them are difficult to simultaneously accomplish the synchronization of magnitude and phase in high frequency circumstance. In this paper, a new modulation called as unified phase-shift modulation (PSM) is proposed to integrate the regulations of magnitude and phase. The unified PSM in steady state completely removes the modulation coupling between magnitude and phase so that the controllers of magnitude and phase can be independently accomplished without interactions. The operation scope of unified PSM is determined by zero voltage switching and total harmonic distortion of the resonant inverter. A prototype with two parallel inverters is established to verify the effectiveness with an operation frequency of 25 kHz and a full bridge output voltage of 40 V peak. The results of simulation and experiment prove that the unified PSM is superior over the existing PSM in HFAC circumstance. The controllers of magnitude and phase integrated by the proposed modulation can accomplish optimized output synchronization in the parallel single-stage resonant inverter. © 1982-2012 IEEE.


Peng Z.,JiShou University | Chen F.,South China University of Technology
International Journal of Polymeric Materials and Polymeric Biomaterials | Year: 2011

Hydrogels were synthesized from acetic acid lignin by chemical crosslinking with NCO-terminated polyurethane ionomers (IPUI). The swelling ratio of hydrogels increased with pH. The hydrogel prepared at the mass ratio of m AAL/mIPUI: 0.35:1 presented maximum swelling ratio in pH 6.8 buffer solutions. The results of thermogravimetric analysis demonstrated that the thermal stability of the hydrogels is improved by the introduction of lignin. The data of release experiments for ammonium sulfate suggests that the hydrogels can be used as coating materials to prepare a slow-release fertilizer. Copyright © 2011 Taylor & Francis Group, LLC.


Huang M.,South China University of Technology | Huang M.,National Engineering Research Center for Tissue Restoration and Reconstruction | Wang Y.,South China University of Technology | Wang Y.,National Engineering Research Center for Tissue Restoration and Reconstruction
Journal of Materials Chemistry | Year: 2012

Calcium phosphate (CP) microcapsules with a typical diameter of 5-10 μm were fabricated via a biomimetic mineralization process with yeast cells (YCs) as a template core modified with the self-assembling of poly(diallyldimethylammonium chloride) and poly(acrylic acid), followed by removal of the biotemplate with calcinations to obtain porous microcapsules. © 2012 The Royal Society of Chemistry.


Feng C.-H.,South China University of Technology | Li F.-B.,Guangdong Institute of Eco environmental and Soil Sciences | Mai H.-J.,South China University of Technology | Li X.-Z.,Hong Kong Polytechnic University
Environmental Science and Technology | Year: 2010

In this study, we proposed a new concept of utilizing the biological electrons produced from a microbial fuel cell (MFC) to power an E-Fenton process to treat wastewater at neutral pH as a bioelectro-Fenton (Bio-E-Fenton) process. This process can be achieved in a dual-chamber MFC from which electrons were generated via the catalyzation of Shewanella decolorationis S12 in its anaerobic anode chamber and transferred to its aerated cathode chamber equipped with a carbon nanotube (CNT)/γ-FeOOH composite cathode. In the cathode chamber, the Fenton's reagents including hydrogen peroxide (H2O 2) and ferrous irons (Fe2+) were in situ generated. This Bio-E-Fenton process led to the complete decolorization and mineralization of Orange II at pH 7.0 with the apparent first-order rate constants, k app = 0.212 h-1 and kTOC = 0.0827 h -1, respectively, and simultaneously produced a maximum power output of 230 mW m2 (normalized to the cathode surface area). The apparent mineralization current efficiency was calculated to be as high as 89%. The cathode composition was an importantfactor in governing system performance. When the ratio of CNT to γ-FeOOH in the composite cathode was 1:1, the system demonstrated the fastest rate of Orange II degradation, corresponding to the highest amount of H2O2 formed. © 2010 American Chemical Society.


Shen Y.,South China University of Technology | Shen Y.,Nanyang Technological University | Lua A.C.,Nanyang Technological University
Applied Catalysis B: Environmental | Year: 2015

Nickel and nickel-copper alloy supported on carbon nanotubes (CNTs) were examined as catalysts for hydrogen production by methane decomposition. The Ni/CNT and Ni-Cu/CNT catalysts were characterized using field emission scanning electron microscopy, energy dispersive X-ray microscopy, transmission electron microscopy and X-ray diffraction. The performance of the catalysts was dependent on the catalyst composition and reaction temperature. The Ni78Cu22/CNT catalyst exhibited the excellent catalytic performance with a stable methane conversion of 0.8 at 700°C, a carbon yield rate of 0.08gC/(mingNi) at 743°C and a carbon yield of 602gC/gNi at 700°C. Carbon materials with various morphologies, i.e., herringbone carbon nanofibers (CNFs), platelet CNFs, bamboo-shaped CNFs, branched CNFs, multi-branched CNFs and onion-like carbons, depending on the catalyst composition and reaction temperature, were obtained. The morphology of the produced carbon material was correlated with the growth mechanism of the carbon material on the catalyst. © 2014 Elsevier B.V.


You K.,Nanyang Technological University | Su W.,South China University of Technology | Fu M.,Zhejiang University | Xie L.,Nanyang Technological University
Automatica | Year: 2011

This paper investigates the attainability of the minimum average data rate for stabilization of linear systems via logarithmic quantization. It is shown that a finite-level logarithmic quantizer suffices to approach the well-known minimum average data rate for stabilizing an unstable linear discrete-time system under two basic network configurations. In particular, we derive explicit finite-level logarithmic quantizers and the corresponding controllers to approach the minimum average data rate. © 2010 Published by Elsevier Ltd.


Saidi W.A.,University of Pittsburgh | Feng H.,Pennsylvania State University | Feng H.,South China University of Technology | Fichthorn K.A.,Pennsylvania State University
Journal of Physical Chemistry C | Year: 2013

We use dispersion-corrected density functional theory (DFT) to resolve the role of polyvinylpyrrolidone (PVP) in the shape-selective synthesis of Ag nanostructures by probing the interaction of its 2-pyrrolidone (2P) ring with Ag(100) and Ag(111). We employ two different semiempirical methods for including van der Waals (vdW) interactions in DFT calculations: DFT+vdWsurf and DFT-D2. We find that DFT-D2, in its original parametrization, overestimates the Ag metal dispersion interaction and causes an unphysical herringbone-like reconstruction of Ag(100). This can be remedied in DFT-D2 by using modified vdW parameters for Ag that account for many-body screening effects. The results obtained using DFT-D2 with the modified parameters agree well with experiment and with DFT+vdWsurf results. We find that 2P binds more strongly to Ag(100) than Ag(111), consistent with experiment. We analyze the origins of the surface-sensitive binding and find that vdW attraction is stronger on Ag(111), but the direct chemical bonding of 2P is stronger on Ag(100). We also study the influence of strain on binding energies and find that tension tends to lower the vdW interaction with the surfaces, while increasing the direct chemical-bonding interaction, consistent with the d-band center model. Overall, our work indicates that strain has little impact on the structure-directing capabilities of PVP, which is consistent with the fact that strained, 5-fold twinned Ag nanowires have extensive {100} facets and relative small {111} facets. © 2012 American Chemical Society.


Wang N.F.,South China University of Technology | Zhang X.M.,South China University of Technology | Yang Y.W.,Nanyang Technological University
Applied Soft Computing Journal | Year: 2013

This work presents a new approach for interval-based uncertainty analysis. The proposed approach integrates a local search strategy as the worst-case-scenario technique of anti-optimization with a constrained multi-objective genetic algorithm. Anti-optimization is a term for an approach to safety factors in engineering structures which is described as pessimistic and searching for least favorable responses, in combination with optimization techniques but in contrast to probabilistic approaches. The algorithm is applied and evaluated to be efficient and effective in producing good results via target matching problems: a simulated topology and shape optimization problem where a 'target' geometry set is predefined as the Pareto optimal solution and a constrained multiobjective optimization problem formulated such that the design solutions will evolve and converge towards the target geometry set. © 2013 Elsevier B.V.


He Z.,South China University of Technology | He Z.,Australian National University | Zhou J.,South China University of Technology | Lu X.,Nanjing University of Technology | Corry B.,Australian National University
ACS Nano | Year: 2013

Biological protein channels have many remarkable properties such as gating, high permeability, and selectivity, which have motivated researchers to mimic their functions for practical applications. Herein, using molecular dynamics simulations, we design bioinspired nanopores in graphene sheets that can discriminate between Na+ and K+, two ions with very similar properties. The simulation results show that, under transmembrane voltage bias, a nanopore containing four carbonyl groups to mimic the selectivity filter of the KcsA K+ channel preferentially conducts K+ over Na+. A nanopore functionalized by four negatively charged carboxylate groups to mimic the selectivity filter of the NavAb Na + channel selectively binds Na+ but transports K + over Na+. Surprisingly, the ion selectivity of the smaller diameter pore containing three carboxylate groups can be tuned by changing the magnitude of the applied voltage bias. Under lower voltage bias, it transports ions in a single-file manner and exhibits Na+ selectivity, dictated by the knock-on ion conduction and selective blockage by Na+. Under higher voltage bias, the nanopore is K+- selective, as the blockage by Na+ is destabilized and the stronger affinity for carboxylate groups slows the passage of Na+ compared with K+. The computational design of biomimetic ion-selective nanopores helps to understand the mechanisms of selectivity in biological ion channels and may also lead to a wide range of potential applications such as sensitive ion sensors, nanofiltration membranes for Na+/K+ separation, and voltage-tunable nanofluidic devices. © 2013 American Chemical Society.


Wang N.F.,South China University of Technology | Tai K.,Nanyang Technological University
Computers and Structures | Year: 2010

In multiobjective design optimization problems, the designer may know that some objectives are harder to extremize than others or that some regions of the objective space are more desirable/important. Such useful information can be incorporated into the genetic algorithm optimization procedure by treating the more challenging/important objectives as constraints whose ideal values are adaptively improved/tightened during the procedure to guide the search. Employing this adaptive constraint strategy and a morphological representation of geometric variables, a genetic algorithm was developed and evaluated through special 'Target Matching' test problems which are simulated topology/shape optimization problems with multiple objectives and constraints. © 2010 Published by Elsevier Ltd. All rights reserved.


Al-Saidi W.A.,University of Pittsburgh | Feng H.,Pennsylvania State University | Feng H.,South China University of Technology | Fichthorn K.A.,Pennsylvania State University
Nano Letters | Year: 2012

We use density functional theory to resolve the role of polyvinylpyrrolidone (PVP) in the shape-selective synthesis of Ag nanostructures. At the segment level, PVP binds more strongly to Ag(100) than Ag(111) because of a surface-sensitive balance between direct binding and van der Waals attraction. At the chain level, correlated segment binding leads to a strong preference for PVP bind to Ag(100). Our study underscores differences between small-molecule and polymeric structure-directing agents. © 2011 American Chemical Society.


Xu J.,Northeast Normal University | Jing N.,South China University of Technology
Journal of Hazardous Materials | Year: 2012

In this study relative condition factor (RCF) and hepatosomatic index (HSI) as well as the available energy reserves of common carp (Cyprinus carpio) by 2,4-DNT semi-static bioassay were determined and linked to effects of enzymes in liver tissues. Fish were exposed at sublethal concentrations of 2,4-DNT (0.13μg/L, 0.1, 0.5, 1.0mg/L) for 7 and 15d. Based on the results, there was no significant change in all parameters measured in fish exposed to 2,4-DNT at environmental related concentration, but 2,4-DNT stress in fish exposed to higher concentrations reflected the significant changes of physiological and biochemical responses. 2,4-DNT stress resulted in EROD activity induction in the liver, and the levels of EROD activity ranged from 0.39- to 1.83-fold higher than control. For GK, Na +/K +-ATPase, and GST, these enzyme activity continued to decline after exposure to 0.1, 0.5 and 1.0mg/L 2,4-DNT, whereas the trend on GK and Na +/K +-ATPase was more obvious than GST. Through principal component analysis, effects by 2,4-DNT-stress in each test group were distinguished. Additionally, indications of a trade-off between metabolic cost of toxicant exposure and processes vital to the survival of the organism were seen at the enzyme activity level as well as on higher levels of biological organization. © 2012 Elsevier B.V.


Zhou B.,Hong Kong Polytechnic University | Chan K.W.,Hong Kong Polytechnic University | Yu T.,South China University of Technology | Chung C.Y.,Hong Kong Polytechnic University
IEEE Transactions on Power Systems | Year: 2013

This paper proposes a novel multiple group search optimizer (MGSO) to solve the highly constrained multiobjective power dispatch (MOPD) problem with conflicting and competing objectives. The algorithm employs a stochastic learning automata based synergistic learning to allow information interaction and credit assignment among multi-groups for cooperative search. An alternative constraint handling, which separates constraints and objectives with different searching strategies, has been adopted to produce a more uniformly-distributed Pareto-optimal front (PF). Moreover, two enhancements, namely space reduction and chaotic sequence dispersion, have also been incorporated to facilitate local exploitation and global exploration of Pareto-optimal solutions in the convergence process. Lastly, Nash equilibrium point is first introduced to identify the best compromise solution from the PF. The performance of MGSO has been fully evaluated and benchmarked on the IEEE 30-bus 6-generator system and 118-bus 54-generator system. Comparisons with previous Pareto heuristic techniques demonstrated the superiority of the proposed MGSO and confirm its capability to cope with practical multiobjective optimization problems with multiple high-dimensional objective functions. © 2013 IEEE.


He F.,South China University of Technology | Ye J.,South China University of Technology | Ye J.,National Engineering Research Center for Tissue Restoration and Reconstruction
Journal of Biomedical Materials Research - Part A | Year: 2012

The aim of this study was to investigate the in vitro degradation, cytocompatibility, and in vivo osteogenesis of poly(lactic-co-glycolic acid) (PLGA)/calcium phosphate cement (CPC) scaffold with unidirectional lamellar pore structure. CPC-based scaffold was fabricated by unidirectional freeze casting, and PLGA was used to improve the mechanical properties of the CPC-based scaffold, which covered the surface of the pore wall as coating. The in vitro degradation results demonstrated that the PLGA/CPC scaffold had good degradability. The degradation of PLGA film on the surface of the scaffold made the CPC matrix exposed, which facilitated cell response and osteogenesis. Rat bone mesenchymal stem cells (rMSCs) were seeded on the PLGA/CPC composite scaffold. Cell viability, proliferation, and differentiation on the PLGA/CPC composite scaffold were evaluated. The results showed that viable rMSCs attached on the surface of pore wall gradually penetrated into the internal pores of the scaffold as prolongation of culture time. In addition, the rMSCs seeded on the scaffold exhibited good proliferation and growing alkaline phosphatase activity. The scaffold was implanted in the defects in distal end of femora of New Zealand white rabbits. Histological evaluation indicated that the PLGA/CPC scaffold with unidirectional lamellar pore structure had good biocompatibility and effective osteogenesis. These results suggest PLGA/CPC composite scaffold with unidirectional lamellar pore structure is a promising scaffold for bone tissue engineering. © 2012 Wiley Periodicals, Inc.


Zhang G.,South China University of Technology | Hai J.,South China Institute of Environmental Sciences | Cheng J.,South China University of Technology
Waste Management | Year: 2012

The input and output samples from existing large-scale municipal solid waste incinerator (MSWI) were collected and analyzed for polychlorinated dibenzo-r{cyrillic}-dioxins and dibenzofurans (PCDD/Fs) in this study, aiming to evaluate PCDD/F characteristic and the corresponding mass balance through the whole system. The grate-type MSWI is equipped with semi-dry scrubber, activated carbon injection, and bag filter as air pollutant control devices (APCDs). Results showed that on the output side, the stack gas, bottom ash and fly ash presented their mean dioxin levels of 0.078ng I-TEQ/Nm 3, 12.94ng I-TEQ/kg and 858ng I-TEQ/kg, respectively, and showed large similarities in congener profiles. Instead, on the input side, the municipal solid waste (MSW) presented a mean dioxin level of 15.56ng I-TEQ/kg and a remarkable difference in congener profiles compared with those of the output. The dioxin mass balance demonstrated that the annual dioxin input value was around 5.38g I-TEQ/yr, lower than the total output value (7.62g I-TEQ/yr), signifying a positive dioxin balance of about 2.25g I-TEQ/yr. © 2012 Elsevier Ltd.


Chen S.Z.,South China University of Technology | Cheung N.C.,Hong Kong Polytechnic University | Chung Wong K.,Hong Kong Polytechnic University | Wu J.,South China University of Technology
IEEE Transactions on Energy Conversion | Year: 2010

An integral sliding-mode direct torque control (ISM-DTC) scheme with space-vector modulation for wind-energy conversion systems based on doubly-fed induction generators (DFIGs) under unbalanced grid voltage is proposed. The torque and power pulsations at twice the grid frequency caused by unbalanced grid voltage can be minimized by the proposed ISM-DTC scheme. Compared with existing control schemes of DFIGs under unbalanced grid voltage, the parametric uncertainties are included into the design procedure of sliding-mode controller, which guarantees the robustness of the controller. Because the torque and reactive power are directly controlled by the rotor voltage, the measurement, coordinate transformation, and symmetrical component extraction of rotor current are eliminated, which simplifies the structure of the controller. Simulation and hardware implementation results validate the effect and parametric robustness of the proposed ISM-DTC scheme. © 2010 IEEE.


Zhang G.,South China University of Technology | Zhang G.,Hong Kong Polytechnic University | Li W.,South China University of Technology | Xie K.,Hong Kong Polytechnic University | And 2 more authors.
Advanced Functional Materials | Year: 2013

Research is currently being carried out in the search for alternative electrode materials to replace the expensive and toxic RuO2-based electrode. As a typical example, nickel oxide or hydroxide has been widely studied but the results are far from satisfactory. Here, using a facile one-step anodization method, a hierarchical nickel compound (HNC) film with an interconnecting 3D nanoflake structure is obtained, providing large electrochemically active surface area and interconnecting nanoscale pore channels for ion transport. The HNC electrode demonstrates significantly improved capacitance, 70 times higher than the reported NiO-TiO2 nanotube array electrode with similar thickness. The charge/discharge kinetics are also superior, showing only a 24% capacitance reduction when the scan rate is increased by 50 times, as compared with the typical 70% capacitance reduction for pseudocapacitor electrodes under the same conditions. HNC exhibits an extraordinary excellent cycle life; capacitance increases to 115% after 4500 test cycles. Furthermore, because HNC is in intimate contact with the current collector, it is not necessary to use conducting agents or binders, which reduces the electrode weight and facilitates the electrode preparation process. The method is low cost, facile, scalable, additive free, and is promising for fabricating supercapacitor electrode with excellent performance. A hierarchical nickel compound (HNC) film is prepared using a facile, one-step, and binder-free method. The HNC demonstrates both large capacitance and superior rate capability. The capacitance reduction is only 24%, even when the scan rate is increased by 50 times. The HNC also exhibits an excellent cycle life. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Lu X.,Beijing Jiaotong University | Ling L.,South China University of Technology
Chaos | Year: 2015

Describing coherently coupled and orthogonally polarized waveguide modes in the Kerr medium, vector bright solitons associated with positive coherent coupling are studied in this paper. Some conserved quantities and infinitely many conservation laws are computed, and the existence of Lax pair indicates the integrability of the two-coupled nonlinear Schrödinger system with positive coherent coupling. Performing the iterative algorithm of Darboux transformation, we present formulas of one-, two-, and even N-soliton solutions. With appropriate choices of the phase parameters, collision mechanisms of vector bright solitons (of single-hump, double-hump, or flat-top profiles) are displayed, which show the elastic collision under the combined influences of group velocity dispersion, self-phase modulation, cross-phase modulation, and positive coherent coupling. © 2015 AIP Publishing LLC.


News Article | January 20, 2016
Site: phys.org

The dangers of UV light have prompted scientists to search for versatile materials that block UV and can withstand long radiation exposure times without falling apart. Now a group of researchers in China has developed a new method to create transparent, glass-based materials with UV-absorbing power and long lifetimes. The team demonstrated that the new glass effectively protects living cells and organic dyes, and believe it could also be developed as a transparent shield to protect electronics in space. They describe their results in Optical Materials Express. The researchers used a metal oxide —cerium (IV) oxide (CeO2)— well-known for its ability to absorb UV photons to craft the composite glass-based UV absorber. Other key features of the final composite material are the optical transparency of the glass and the material's ability to suppress the separation of photo-generated electrons and holes. The later feature slows down a light-induced reaction that would lead to the ultimate breakdown of the material under prolonged exposure to UV radiation. The method the team developed is based on the self-limited nanocrystallization of glass. "Self-limited nanocrystallization of glass can be achieved by taking advantage of the rigid environment of the solid-state matrix, rather than the conventional solution and vapor conditions to modulate the ionic migration kinetics," explained Shifeng Zhou, School of Materials Science and Engineering, South China University of Technology, Guangzhou, China. "It allows us to create glass-ceramics embedded with a CeO2:fluorine (F) nanostructure." The viscous glass matrix involved poses a considerable constraint for oxide (O2-) and F- ion diffusion, so the group gradually etches trifluorocerium (CeF3) by O2- ions within an oxide matrix until F—doped CeO2 is generated in a controllable manner. It's important to note that this technology is also routinely used to prepare other UV absorbers such as zinc oxide (ZnO) and titanium oxide (TiO2). "This work establishes an effective approach for the functionalization of glass," said Zhou. "And it allowed us to demonstrate the construction of a novel glass-based UV absorber." The group's innovative approach for fabricating the UV absorber has important implications "for the construction of novel glass materials with new functions via microstructure engineering," he added. Among the group's key discoveries was finding that the self-limited nanocrystallinization of glass is indeed an effective way to functionalize it. The special glass they created suppresses photocatalytic and catalytic activity, while boasting an extremely high UV-absorbing capacity. "Our glass shows excellent optical quality, and it can be easily fabricated either in bulk form or as a film," said Zhou. "It effectively protects organic dye and living cells from UV radiation damage." Potential applications for the group's work include radiation hardening of electronic devices, serving as a biological shield, and preserving cultural artifacts and relics. "In space, the high-energy radiation environment encountered by electronic equipment aboard spacecraft can be quite damaging," noted Zhou. "Fortunately, in the future, if you add a radiation-blocking coating onto the surface of the package - a transparent glass/polymer material - the device would be well protected, and its service lifetime may be prolonged." In terms of applications as biological shields and to preserve cultural artifacts and relics, the special glass can "protect cells from UV-induced damage," he added. Going forward, the group plans to focus their efforts on developing other novel and effective glass-based UV absorbers, using the self-limited nanocrystallization method. "We'll explore ways for large-scale fabrication of this type of film, which is extremely important for practical applications," said Zhou. "Our group will also further study the functionalization of glass based on its microstructure engineering, because we believe this fundamental research may have great significance for the glass industry." More information: B. Zheng, Z. Wang, Q. Guo, S. Zhou. "Glass Composite as Robust UV Absorber for Biological Protection," Optical Materials Express 6, 531-539 (2016). www.osapublishing.org/ome/abstract.cfm?uri=ome-6-2-531


News Article | January 22, 2016
Site: www.techtimes.com

Chinese scientists have discovered a special glass that can absorb and block dangerous ultraviolet rays. UV light can harm living cells, and out in space where radiation from the sun is even greater, sensitive electronics on board a spacecraft can suffer even more damage. Thus researchers from South China University of Technology in Guangzhou developed a method to create transparent and glass-based materials with the power and lifespan to absorb UV rays. They used cerium (IV) oxide (CeO2), a metal oxide with a renowned ability to absorb photons, to make the composite glass-based UV absorber. The material is optically transparent and can prevent the separation of photo-generated electrons and holes, which would hinder its own breakdown under prolonged UV radiation exposure. Author Shifeng Zhou highlighted the self-limited nanocrystallization of glass as the technique they used. “This work establishes an effective approach for the functionalization of glass,” the researcher said. The special glass they created, for instance boasts an extremely great UV-absorbing capability while suppressing photocatalytic and catalytic action. Chlorophyll is one natural example of a photocatalyst, but unlike it, a man-made photocatalyst creates great oxidation and electronic holes. “Our glass shows excellent optical quality, and it can be easily fabricated either in bulk form or as a film,” added Zhou, citing how it can protect living cells and organic dye from UV damage, for instance. This special glass not only serves as a biological shield, but also protects and preserves electronic devices and cultural artifacts from this form of radiation. In space, a radiation-blocking layer of transparent glass or polymer material on the surface of electronic equipment can protect them and prolong their service. The team intends to develop more new, effective glass-based UV-absorbing materials using this method and explore the functionalization of glass based on the wonders of its microstructure engineering. “[W]e believe this fundamental research may have great significant for the glass industry,” Zhou said. The team published its findings in the journal Optical Materials Express.


Wu S.,South China University of Technology | Wang R.,South China University of Technology | Wang Z.,South China University of Technology | Lin Z.,Georgia Institute of Technology
Nanoscale | Year: 2014

A facile one-step route was developed to synthesize crystalline CuGeO 3 nanowire/graphene composites (CGCs). Crystalline CuGeO3 nanowires were tightly covered and anchored by graphene sheets, forming a layered structure. Subsequently, CGCs were exploited as electrode materials for lithium ion batteries (LIBs). The reversible formation of Li2O buffer layer and elastic graphene sheets accommodated the volume change during the charge and discharge processes. CGC containing 37 wt% graphene exhibited a superior electrochemical performance, that is, a remarkable reversible capacity (1265 mA h g-1 for the first cycle), an outstanding cyclic performance (853 mA h g-1 after 50 cycles under a current density of 200 mA g-1), a high coulombic efficiency, and an excellent rate capability. Clearly, CGCs may stand out as a promising anode material for LIBs. © 2014 the Partner Organisations.


Hou X.-D.,South China University of Technology | Smith T.J.,Sheffield Hallam University | Li N.,South China University of Technology | Zong M.-H.,South China University of Technology
Biotechnology and Bioengineering | Year: 2012

Cholinium amino acids ionic liquids ([Ch][AA] ILs), a novel type of bio-ILs that can easily be prepared from renewable biomaterials, were investigated for pretreatment of rice straw by selective extraction of lignin from this abundant lignocellulosic biomass material. Of the eight ILs examined, most were demonstrated to be excellent pretreatment solvents. Upon pretreatment using these ILs, the initial saccharification rates of rice straw residues were substantially improved as well as the extent to which polysaccharides could be digested (>90% for cellulose and >60% for xylan). Enzymatic hydrolysis of pretreated rice straw by Trichoderma reesei cellulase/xylanase furnished glucose and xylose with the yields in excess of 80% and 30%, respectively. Detailed spectroscopic characterization showed that the enhancement of polysaccharides degestibility derived mainly from delignification rather than changes in cellulose crystallinity. The yields of fermentable reducing sugars were significantly improved after individual optimization of pretreatment temperature and duration. With [Ch][Lys] as the solvent, the sugar yields of 84.0% for glucose and 42.1% for xylose were achieved after pretreatment at 90°C for 5h. The IL [Ch][Lys] showed excellent reusability across five successive batches in pretreatment of rice straw. These bio-ILs performed as well as or better than previously investigated non-renewable ILs, and thus present a new and environmentally friendly way to pretreat lignocellulose for production of fermentable sugars and total utilization of the biomass. © 2012 Wiley Periodicals, Inc.


Fu X.,University of Arkansas | Fu X.,South China University of Technology | Naumov I.I.,University of Arkansas | Naumov I.I.,Carnegie Institution of Washington | Fu H.,University of Arkansas
Nano Letters | Year: 2013

Dipole collective behavior and phase transition in ferroelectric (FE) Pb(Zr0.5Ti0.5)O3 nanowires, caused by modulated electric fields, are reported. Our result also leads to the finding of a rather outstanding electromechanical d31 response in a 8.4 nm diameter PZT wire, which may potentially outperform bulk PMN-PT and PZN-PT. Moreover, we further demonstrate the existence of a new type of morphotropic phase boundary (MPB) that bridges two dissimilar structure phases of different order parameters. Microscopic insights for understanding the collective behavior and the structural phase within the new MPB are provided. © 2012 American Chemical Society.


Cheng J.,South China University of Technology | Huang G.,East China Normal University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

We propose a scheme to realize a transition from delocalization to localization of light waves via electromagnetically induced transparency. The system we suggested is a resonant cold atomic ensemble having N configuration, with a control field consisting of two pairs of laser beams with different cross angles, which produce an electromagnetically induced quasiperiodic waveguide (EIQPW) for the propagation of a signal field. By appropriately tuning the incommensurate rate or relative modulation strength between the two pairs of control-field components, the signal field can exhibit the delocalization- localization transition as it transports inside the atomic ensemble. The delocalization-localization transition point is determined and the propagation property of the signal field is studied in detail. Our work provides a way of realizing wave localization via atomic coherence, which is quite different from the conventional, off-resonant mechanism-based Aubry-Andre model, and the great controllability of the EIQPW also allows an easy manipulation of the delocalization-localization transition. © 2011 American Physical Society.


Chen M.,Huazhong University of Science and Technology | Wan J.,South China University of Technology | Gonzalez S.,University of British Columbia | Liao X.,Huazhong University of Science and Technology | Leung V.C.M.,University of British Columbia
IEEE Communications Surveys and Tutorials | Year: 2014

Recent years have witnessed the emergence of machine-to-machine (M2M) networks as an efficient means for providing automated communications among distributed devices. Automated M2M communications can offset the overhead costs of conventional operations, thus promoting their wider adoption in fixed and mobile platforms equipped with embedded processors and sensors/actuators. In this paper, we survey M2M technologies for applications such as healthcare, energy management and entertainment. In particular, we examine the typical architectures of home M2M networks and discuss the performance tradeoffs in existing designs. Our investigation covers quality of service, energy efficiency and security issues. Moreover, we review existing home networking projects to better understand the real-world applicability of these systems. This survey contributes to better understanding of the challenges in existing M2M networks and further shed new light on future research directions. © 2014 IEEE.


Hou X.-D.,South China University of Technology | Liu Q.-P.,South China University of Technology | Smith T.J.,Sheffield Hallam University | Li N.,South China University of Technology | Zong M.-H.,South China University of Technology
PLoS ONE | Year: 2013

Cholinium amino acid ionic liquids ([Ch][AA] ILs), which are wholly composed of renewable biomaterials, have recently been demonstrated to have very promising properties for applications in organic synthesis and biomass pretreatment. In this work, the toxicity of these ILs toward enzymes and bacteria was assessed, and the effect of the anion on these properties is discussed. The inhibitory potentials of this type of ILs to acetylcholinesterase were weaker approximately an order of magnitude than the traditional IL 1-butyl-3-methylimidazolium tetrafluoroborate. Additionally, the [Ch][AA] ILs displayed low toxicity toward the bacteria tested. Furthermore, the biodegradability of the [Ch][AA] ILs was evaluated via the closed bottle and CO2 headspace tests using wastewater microorganisms. All the ILs were classified as 'readily biodegradable' based on their high levels of mineralization (62-87%). The presence of extra carboxyl or amide groups on the amino acid side chain rendered the ILs significantly more susceptible to microbial breakdown. In addition, for most of the [Ch][AA] ILs, low toxicity correlated with good biodegradability. The low toxicity and high biodegradability of these novel [Ch][AA] make them promising candidates for use as environmentally friendly solvents in large-scale applications. © 2013 Hou et al.


Yang P.,South China University of Technology | Gao W.,Qatar Computing Research Institute
IJCAI International Joint Conference on Artificial Intelligence | Year: 2013

We study to incorporate multiple views of data in a perceptive transfer learning framework and propose a Multi-view Discriminant Transfer (MDT) learning approach for domain adaptation. The main idea is to find the optimal discriminant weight vectors for each view such that the correlation between the two-view projected data is maximized, while both the domain discrepancy and the view disagreement are minimized simultaneously. Furthermore, we analyze MDT theoretically from discriminant analysis perspective to explain the condition and reason, under which the proposed method is not applicable. The analytical results allow us to investigate whether there exist within-view and/or betweenview conflicts, and thus provides a deep insight into whether the transfer learning algorithm work properly or not in the view-based problems and the combined learning problem. Experiments show that MDT significantly outperforms the state-of-the-art baselines including some typical multi-view learning approaches in single- or cross-domain.


Zhu X.,South China University of Technology | Wang H.,South China University of Technology | Wang H.,Georgia Institute of Technology | Zheng L.-X.,South China University of Technology
Optics Express | Year: 2010

We report the existence and stability of solitons in kagome optical lattices with a defect in photorefractive crystal under focusing saturable nonlinearity. For different types of defects, solitons will exist in different gaps. For a positive defect, the solitons only exist in the semiinfinite gap and only stably exist in the low power region. For a negative defect, the solitons exist both in the semi-infinite gap and the first gap. With an increasing of the negative defect depth, the stable region in the semiinfinite will be narrowed, while solitons will be firstly unstable in the high power region of the first gap, and finally solitons will be not stable in the whole first gap. © 2010 Optical Society of America.


Hu X.,Georgia Institute of Technology | Hu X.,South China University of Technology | Tong Z.,South China University of Technology | Lyon L.A.,Georgia Institute of Technology
Journal of the American Chemical Society | Year: 2010

Multiresponsive poly(N-isopropylacrylamide-co-acrylic acid) (pNIPAm-AAc) microgels containing mechanically and thermodynamically decoupled poly(N-isopropylmethacrylamide) (pNIPMAm) cores have been prepared. To achieve this structure, pNIPMAm microgels were used as templates in the synthesis of an N,N′-(1,2-dihydroxyethylene)bisacrylamide (DHEA) cross-linked pNIPMAm inner shell. A pNIPAm-AAc outer shell was then added, resulting in "core/double-shell" microgels. Erosion of the inner shell via periodate-mediated cleavage of the 1,2-diol bond in DHEA produced multiresponsive core/shell microgels with independent cores. The striking structural changes and unique multiresponsivity achieved in microgels prepared via this approach illustrate the potential of multifunctional, multicomponent delivery vehicles that do not suffer from antagonistic interferences arising when different functional components are introduced within a single particle. © 2010 American Chemical Society.


Xu X.,South China University of Technology | Xu X.,Infinitus China Company Ltd | Yan H.,South China University of Technology | Chen J.,South China University of Technology | Zhang X.,South China University of Technology
Biotechnology Advances | Year: 2011

Mushrooms have been used as food or medicine for thousands of years. Due to low-fat content and absence of cholesterol, many mushrooms are excellent sources of protein. There are various mushroom proteins with interesting biological activities, such as lectins, fungal immunomodulatory proteins (FIP), ribosome inactivating proteins (RIP), ribonucleases, laccases, and other proteins, which have become popular sources of natural antitumor, antiviral, antimicrobial, antioxidative, and immunomodulatory agents. The aim of this review is to update the present status of bioactive proteins in mushrooms, and to discuss their biomedical potential and future prospectives. © 2011 Elsevier Inc.


Quan X.,South China University of Technology | Li R.,South China University of Technology | Tentzeris M.M.,Georgia Institute of Technology
IEEE Transactions on Antennas and Propagation | Year: 2013

A broadband circularly polarized (CP) antenna is developed with an omnidirectional radiation pattern in the horizontal plane. Four broadband CP rectangular loop elements are employed for broadband omnidirectional CP radiation. The four rectangular loop elements are first printed on a flexible thin dielectric substrate and then rolled into a hollow cylinder. A conducting cylinder is introduced inside the hollow cylinder for achieving desired omnidirectional CP performance. A feeding network consisting of four broadband baluns and an impedance matching circuit is designed to feed the four rectangular loop elements. The omnidirectional CP antenna has a circular cross section with diameter of 0.38 λ0. Experimental results show that the omnidirectional CP antenna has bandwidths of 41% (1.65-2.5 GHz) for axial ratio < 3 dB and 45% (1.58-2.5 GHz) for return loss 10 dB. The gain variation in the omnidirectional plane is less than 1 dB for the frequency range from 1.65 to 2.5 GHz. Good agreement is obtained between simulated and measured results. © 1963-2012 IEEE.


Li N.,South China University of Technology | Smith T.J.,Sheffield Hallam University | Zong M.-H.,South China University of Technology
Biotechnology Advances | Year: 2010

Nucleoside derivatives are a class of compounds that have attracted intense interest in biotechnology and medicine. Use of biocatalysts opens exciting opportunities for selective synthesis of many nucleoside derivatives, and such an approach offers simplicity, exquisite selectivity and environmentally benign processes. Here we reviewed current achievements in the biocatalytic transformation of nucleoside derivatives from the literature between 2000 and 2009. This article is arranged according to the types of reactions that can be employed to transform nucleoside derivatives, which include acylation, deacylation, glycosylation, halogenation and deamination. © 2010 Elsevier Inc. All rights reserved.


Li Y.,South China University of Technology | Gecevicius M.,South China University of Technology | Qiu J.,South China University of Technology | Qiu J.,Zhejiang University
Chemical Society Reviews | Year: 2016

Owing to the unique mechanism of photoelectron storage and release, long persistent phosphorescence, also called long persistent luminescence or long lasting afterglow/phosphorescence, plays a pivotal role in the areas of spectroscopy, photochemistry, photonics and materials science. In recent years, more research has focused on the manipulation of the morphology, operational wavebands and persistent duration of long persistent phosphors (LPPs). These desired achievements stimulated the growing interest in designing bio-labels, photocatalysts, optical sensors, detectors and photonic devices. In this review, we present multidisciplinary research on synthetic methods, afterglow mechanisms, characterization techniques, materials system, and applications of LPPs. First, we introduce the recent developments in LPPs for the synthesis of nanoparticles from the aspects of particle sizes, monodispersity and homogeneity based on the urgent application of bio-imaging. In the later sections, we present the possible mechanisms, which involve the variation of trap distribution during the trapping and de-trapping process, complicated photo-ionization reaction of trap site levels and impurity centers together with their corresponding migration kinetics of carriers. Meanwhile, we emphasize the characterization techniques of defects, used to qualitatively or quantitatively describe the types, concentrations and depths of the traps. This review article also highlights the recent advances in suggested LPPs materials with a focus on the LPPs' hosts and optically active centers as well as their control, tuning and intrinsic links. We further discuss the classification of LPPs based on the different emission and excitation wavebands from the ultraviolet to the near-infrared region along with an overview of the activation mode of afterglow. Afterwards, we provide an exhibition of new products towards diverse application fields, including solar energy utilization, bio-imaging, diagnosis, and photocatalysts. Finally, we summarize the current achievements, discuss the problems and provide suggestions for potential future directions in the aforementioned parts. © The Royal Society of Chemistry 2016.


Tang C.-H.,South China University of Technology | Chen L.,South China University of Technology | Foegeding E.A.,North Carolina State University
Journal of Agricultural and Food Chemistry | Year: 2011

The mechanical properties, water-holding capacities (WHC), and microstructures of emulsion gels, induced by glucono-δ-lactone (GDL), CaCl2, and microbial transglutaminase (MTGase) from unheated and heated soy protein isolate (SPI)-stabilized emulsions (at protein concentration 5%, w/v; oil volume fraction, 20%, w/v), were investigated and compared. The influence of thermal pretreatments (at 90 °C for 5 min) before and/or after emulsification was evaluated. Considerable differences in mechanical, water-holding, and microstructural properties were observed among various emulsion gels. The thermal pretreatment after emulsification increased the strength of the emulsion gels induced by GDL and CaCl2, whereas in the case of MTGase, thermal pretreatments before and/or after emulsification on the contrary greatly inhibited gel network formation. The application of the enzyme coagulant exhibited much higher potential to form SPI-stabilized emulsion gels with higher mechanical strength than that of the other two coagulants. The WHC of the emulsion gels seemed to be not directly related to their gel network strength. Confocal laser scanning microscope analyses indicated that the network microstructure of the formed emulsion gels, mainly composed of aggregated protein-stabilized oil droplets and protein aggregate clumps, varied with the type of applied coagulants and emulsions. The differences in microstructure were basically consistent with the differences in mechanical properties of the gels. These results could provide valuable information for the formation of cold-set soy protein-stabilized emulsion gels. © 2011 American Chemical Society.


Huang Z.,South China University of Technology | Xie F.,South China University of Technology | Ma Y.,AECOM Technology Corporation
Journal of Hazardous Materials | Year: 2011

A method was developed to recover the copper and iron from Printed Circuit Boards (PCB) manufacturing generated spent acid etching solution and waste sludge with ultrasonic energy at laboratory scale. It demonstrated that copper-containing PCB spent etching solution could be utilized as a leaching solution to leach copper from copper contained PCB waste sludge. It also indicated that lime could be used as an alkaline precipitating agent in this method to precipitate iron from the mixture of acidic PCB spent etching solution and waste sludge. This method provided an effective technique for the recovery of copper and iron through simultaneous use of PCB spent acid solution and waste sludge. The leaching rates of copper and iron enhanced with ultrasound energy were reached at 93.76% and 2.07% respectively and effectively separated copper from iron. Followed by applying lime to precipitate copper from the mixture of leachate and rinsing water produced by the copper and iron separation, about 99.99% and 1.29% of soluble copper and calcium were settled as the solids respectively. Furthermore the settled copper could be made as commercial rate copper. The process performance parameters studied were pH, ultrasonic power, and temperature. This method provided a simple and reliable technique to recover copper and iron from waste streams generated by PCB manufacturing, and would significantly reduce the cost of chemicals used in the recovery. © 2010 Elsevier B.V.


Guan Q.,University of Michigan | Guan Q.,South China University of Technology | Wei C.,South China University of Technology | Savage P.E.,University of Michigan
Physical Chemistry Chemical Physics | Year: 2012

The article reports the first quantitative kinetics model for supercritical water gasification (SCWG) of real biomass (algae) that describes the formation of the individual gaseous products. The phenomenological model is based on a set of reaction pathways that includes two types of compounds being intermediate between the algal biomass and the final gaseous products. To best correlate the experimental gas yields obtained at 450, 500 and 550°C, the model allowed one type of intermediate to react to gases more quickly than the other type of intermediate. The model parameters indicate that gas yields increase with temperature because higher temperatures favor production of the more easily gasified intermediate and the production of gas at the expense of char. The model can accurately predict the qualitative influence of the biomass loading and water density on the gas yields. Sensitivity analysis and reaction rate analysis indicate that steam reforming of intermediates is an important source of H 2, whereas direct decomposition of the intermediate species is the main source of CO, CO 2 and CH 4. © 2012 The Owner Societies.


Guan Q.,University of Michigan | Guan Q.,South China University of Technology | Savage P.E.,University of Michigan | Wei C.,South China University of Technology
Journal of Supercritical Fluids | Year: 2012

We report results from a systematic study of the gasification of the alga Nannochloropsis sp. in supercritical water at 450-550°C. The gaseous products were mainly H 2, CO 2, and CH 4, with lesser amounts of CO, C 2H 4, and C 2H 6. Higher temperatures, longer reaction times, higher water densities, and lower algae loadings provided higher gas yields. The algae loading strongly affected the H 2 yield, which more than tripled when the loading was reduced from 15 wt% to 1 wt%. The water density had little effect on the gas composition. The temporal variation of intermediate products indicated that some (e.g., alkanes) reacted quickly whereas others (aromatics) reacted more slowly. On the basis of this observation and the complete set of experimental results, we propose a global reaction network for algae SCWG that includes parallel primary pathways to each of these two types of intermediate products. The intermediate products then produce gases. © 2011 Elsevier B.V. All rights reserved.


Ma W.,North Carolina State University | Tumbleston J.R.,North Carolina State University | Wang M.,South China University of Technology | Gann E.,North Carolina State University | And 2 more authors.
Advanced Energy Materials | Year: 2013

Domain purity and interface structure are known to be critical for fullerene-based bulk heterojunction (BHJ) solar cells, yet have been very difficult to study. Using novel soft X-ray tools, we delineate the importance of these parameters by comparing high performance cells based on a novel naphtha[1,2-c:5,6-c]bis[1,2,5]thiadiazole (NT) material to cells based on a 2,1,3-benzothiadiazole (BT) analogue. BT-based devices exhibit ? 15 nm, mixed domains that differ in composition by at most 22%, causing substantial bimolecular recombination. In contrast, NT-based devices have more pure domains that are > 80 nm in size, yet the polymer-rich phase still contains at least 22% fullerene. Power conversion efficiency > 6% is achieved for NT devices despite a domain size much larger than the nominal exciton diffusion length due to a favourable trade-off in the mixed domain between exciton harvesting, charge transport, and bimolecular recombination. The miscibility of the fullerene with the NT and BT polymer is measured and correlated to the purity in devices. Importantly, polarized x-ray scattering reveals preferential face-on orientation of the NT polymer relative to the PCBM-rich domains. Such ordering has previously not been observed in fullerene-based solar cells and is shown here to be possibly a controlling or contributing factor to high performance. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Chang J.,South China University of Technology | Fu Y.,South China University of Technology | Luo Z.,Zhejiang University
Biomass and Bioenergy | Year: 2012

A novel route for DME production from biomass was proposed and tested in a bench scale experimental system. A Cu-Zn-Al/HZSM-5 (16.7 wt%) was developed for DME synthesis from the biomass-derived syngas. At 1113 K, atmospheric pressure, the feed rate of 0.6 kg biomass/h, ER of 0.28, and CO 2/biomass ratio of 0.327, 1.4 Nm 3 of raw gas kg -1 biomass with LHV of 8.36 MJ m -3 was produced. With reforming by the biogas addition of 0.54 Nm 3 kg -1 biomass, the yield of syngas increased to 2.5 Nm 3 from 1.4 Nm 3 of raw gas, and the ratio of H 2/CO was adjusted to 1.18. At ideal synthesis conditions, it was simulated based on kinetics equations for direct DME synthesis on Cu-Zn-Al/HZSM-5 catalyst that 78.5% of CO conversion and 379 g DME per kg biomass could be obtained. Gasification with CO 2 agent and sequent co-reforming with biogas supplies great potential for high efficient production of DME from biomass. © 2011 Elsevier Ltd.


Cui Y.,South China University of Technology | Li R.L.,South China University of Technology | Wang P.,ZTE Corporation
IEEE Transactions on Antennas and Propagation | Year: 2013

A novel broadband planar antenna is developed for mobile communication base stations. The antenna is composed of a pair of folded dipoles which are coupling fed by an L-shaped microstrip line. Both the dipoles and the coupling microstrip line are etched on the same substrate. The planar antenna achieves a bandwidth of 53% for return loss > 15 dB, covering the frequency range 1.65-2.85 GHz for 2G/3G/LTE applications. The antenna gain of the broadband antenna element is about 9 dBi. A ±45° dual-polarized planar antenna consisting of two broadband antenna elements is proposed, which achieves a bandwidth of about 50% and an isolation of 30 dB. Two 8-element antenna arrays are developed respectively for the broadband antenna and for the ±45° dual-polarized antenna. Both antenna arrays achieve a bandwidth of more than 58% (1.6-2.9 GHz). The antenna gains achieved for the both antenna arrays are higher than 15.5 dBi. The half-power beam widths in the horizontal plane for the antenna arrays are approximately 65±10°, suitable for base station applications. © 1963-2012 IEEE.


Cai W.,South China University of Technology | Jing N.,North Carolina State University
European Journal of Combinatorics | Year: 2012

An explicit computation is made for a Laplace-Beltrami type operator for Jack polynomials. As applications we obtain: combinatorial formula, determinantal formula and raising operator formula for Jack polynomials, as well as an iterative formula for the Littlewood-Richardson coefficients. One special case of our results implies Mimachi-Yamada's result on Jack polynomials of rectangular shapes. © 2011 Elsevier Ltd.


Cui Y.,South China University of Technology | Li R.L.,South China University of Technology | Wang P.,ZTE Corporation
IEEE Transactions on Antennas and Propagation | Year: 2013

A novel dual-broadband planar antenna is proposed for 2G/3G/LTE (4G) mobile communications. The proposed dual-broadband antenna consists of one element for the lower band and two elements for the upper band, making it possible to be arrayed without appearance of grating lobes in the upper band. The lower-band element comprises a pair of printed dipoles with a pair of parasitic elements for bandwidth enhancement. Two upper-band elements composed of two pairs of folded dipoles are nested inside the lower-band element, forming a compact arrayable antenna unit. The dual-broadband antenna achieves a bandwidth of 20% (800-980 MHz) for the lower band and a bandwidth of 60% (1540-2860 MHz) for the upper band. A dual-broadband antenna array that consists of 4 elements for the lower band and 8 elements for the upper band is developed for base station applications. The dual-broadband array achieves a bandwidth of 22% (780-980 MHz) for the lower band and a bandwidth of 68% (1470-3000 MHz) for the upper band, covering all the frequency bands for 2G/3G/LTE (4G) systems. Measured antenna gains for the array are ∼ 12 dBi for the lower band and ∼ 13.5 dBi for the upper band, suitable for potential applications in mobile communication base stations. © 2012 IEEE.


Liu Y.,Yulin Normal University | Yang Q.,South China University of Technology
International Journal of Bifurcation and Chaos | Year: 2011

Firstly, the dynamics of the Lü system having an invariant algebraic surface are analyzed. Secondly, by using the Poincaré compactification in ℝ 3, a global analysis of the system is presented, including the complete description of its dynamic behavior on the sphere at infinity. Lastly, combining analytical and numerical techniques, it is shown that for the parameter value b = 0, the system presents an infinite set of singularly degenerate heteroclinic cycles. The chaotic attractors for the Lü system in the case of small b > 0 are found numerically, hence the singularly degenerate heteroclinic cycles. © 2011 World Scientific Publishing Company.


Liu X.,Zhejiang University | Qiu J.,Zhejiang University | Qiu J.,South China University of Technology
Chemical Society Reviews | Year: 2015

Transfer of energy occurs endlessly in our universe by means of radiation. Compared to energy transfer (ET) in free space, in solid state materials the transfer of energy occurs in a rather confined manner, which is usually mediated by real or virtual particles, including not only photons, but also electrons, phonons, and excitons. In the present review, we discuss the recent advances in optical ET by resonance mediated with photons in solid materials as well as their nanoscale counterparts, with focus on the photoluminescence behavior pertaining to ET between optically active centers, such as rare earth (RE) ions. This review begins with a brief discussion on the classification of optical ET together with an overview of the theoretical formulations and experimental method for the examination of ET. We will then present a comprehensive discussion on the ET in practical systems in which normal photoluminescence, upconversion and quantum cutting resulted from ET involving metal ions, QDs, organic species, 2D materials and plasmonic nanostructures. Diverse ET systems are therefore simply categorized into cases of ion-ion interactions and non-ion interactions. Special attention has been paid to the progress in the manipulation of spatially confined ET in nanostructured systems including core-shell structures, as well as the ET in multiple exciton generation found in QDs and organic molecules, which behave quite similarly to resonance ET between metal ion centers. Afterwards, we will discuss the broad spectrum of applications of ET in the aforementioned systems, including solid state lighting, solar energy utilization, bio-imaging and diagnosis, and sensing. In the closing part, along with a short summary, we discuss further research focus regarding the problems and possible future directions of optical ET in solids. © The Royal Society of Chemistry 2015.


Liu Y.,South China University of Technology | Liu Y.,Yulin Normal University | Yang Q.,South China University of Technology
Nonlinear Analysis: Real World Applications | Year: 2010

The present work is devoted to giving new insights into a new Lorenz-like chaotic system. The local dynamical entities, such as the number of equilibria, the stability of the hyperbolic equilibria and the stability of the non-hyperbolic equilibrium obtained by using the center manifold theorem, the pitchfork bifurcation and the degenerate pitchfork bifurcation, Hopf bifurcations and the local manifold character, are all analyzed when the parameters are varied in the space of parameters. The existence of homoclinic and heteroclinic orbits of the system is also rigorously studied. More exactly, for b<2a>0 and c>0, we prove that the system has no homoclinic orbit but has two and only two heteroclinic orbits. © 2009 Elsevier Ltd. All rights reserved.


Wang X.,Hefei University of Technology | Liu G.,Hefei University of Technology | Zhang G.,South China University of Technology
Langmuir | Year: 2012

We have systematically investigated the effect of surface wettability on ion-specific adsorption of bovine serum albumin (BSA) by using quartz crystal microbalance with dissipation (QCM-D) and surface plasmon resonance (SPR). The changes in frequency (Δf) and resonance unit (ΔRU) show a nonmonotonous change of the adsorbed amount of BSA as a function of molar fraction of 1-dodecanethiol (xDDT) of the self-assembled monolayer at pH 3.8, while the amount of adsorbed protein gradually increases with the xDDT at pH 7.4. The small changes of dissipation (ΔD) indicate that BSA molecules form a quite rigid protein layer on the surfaces, which results in only a slight difference in the adsorbed mass between the mass-uptake estimations from the Sauerbrey equation and the Voigt model. The difference in the adsorbed mass between QCM-D and SPR measurements is attributed to the coupled water in the protein layer. On the other hand, specific anion effect is observed in the BSA adsorption at pH 3.8 with the exception of the surface at xDDT of 0%, but no obvious cation specificity can be observed at pH 7.4. The ΔD-Δf plots show that the BSA adsorption at pH 3.8 has two distinct kinetic processes. The first one dominated by the protein-surface interactions is an anion-nonspecific process, whereas the second one dominated by the protein structural rearrangements is an anion-specific process. At pH 7.4, the second kinetic process can only be observed at the relatively hydrophobic surfaces, and no cation specificity is observed in the first and second kinetic processes. © 2012 American Chemical Society.


Malek H.,Utah State University | Luo Y.,South China University of Technology | Chen Y.,University of California at Merced
Mechatronics | Year: 2013

First order plus time delay model is widely used to model systems with S-shaped reaction curve. Its generalized form is the model with a single fractional pole replacing the integer order pole, which is believed to better characterize the reaction curve. In this paper, using time delayed system model with a fractional pole as the starting point, fractional order controllers design for this class of fractional order systems is investigated. Integer order PID and fractional order PI and [PI] controllers are designed and compared for these class of systems. The simulation comparison between PID controller and fractional order PI and [PI] controllers show the advantages of the properly designed fractional order controllers. Experimental results on a heat flow platform are presented to validate the proposed design method in this paper. © 2013 Elsevier Ltd. All rights reserved.


Lin J.,South China University of Technology | Ding S.,South China Normal University
Mathematical Methods in the Applied Sciences | Year: 2012

In recent paper, we prove the well-posedness for the heat flow of harmonic maps with initial data u 0 ∈ W 1,n(R n,N) and for the hydrodynamic flow of nematic liquid crystals with initial data (v0,d0)∈L n(Rn)× W 1,n(R n,S 2). © 2011 John Wiley & Sons, Ltd.


Zeng X.,University of Manitoba | Zeng X.,South China University of Technology | Raghavan J.,University of Manitoba
Composites Part A: Applied Science and Manufacturing | Year: 2010

The role of tool-part interaction in process-induces warpage of a large composite structure was studied using a three-dimensional process model, developed by integrating sub-models that describe the evolution of cure and properties of composite as well as various physical phenomena encountered, during autoclave processing. The process model was implemented through user sub-routines interfaced with the finite element software, ABAQUS. The tool-part interaction during processing was modeled using contact elements. The predicted temperature and warpage of an aircraft part, using a frictional tool-part interface and experimentally measured cure-dependent tool-part interfacial friction coefficients, compared very well with experimental temperature and warpage, validating the 3-D process model. A comparison of predictions using various models for the tool-part interface suggests that the two components of tool-part interaction that contribute to warpage are change in shape of the tool and part, and process-induced stress caused by constrained deformation of the tool and the part. © 2010 Elsevier Ltd. All rights reserved.


Luo Y.,South China University of Technology | Luo Y.,Utah State University | Chen Y.,Utah State University
Automatica | Year: 2012

For all the stable first order plus time delay (FOPTD) systems, a fractional order proportional integral (FOPI) or a traditional integer order proportional integral derivative (IOPID) controller can be designed to fulfill a flat phase constraint and two design specifications simultaneously: gain crossover frequency and phase margin. In this paper, a guideline for choosing two feasible or achievable specifications, and a new FOPI/IOPID controller synthesis are proposed for all the stable FOPTD systems. Using this synthesis scheme, the complete feasible region of two specifications can be obtained and visualized in the plane. With this region as the prior knowledge, all combinations of two specifications can be verified before the controller design. Especially, it is interesting to compare the areas of these two feasible regions for the IOPID and FOPI controllers. This area comparison reveals, for the first time, the potential advantages of one controller over the other in terms of achievable performances. A simulation illustration is presented to show the effectiveness and the performance of the designed FOPI controller compared with the optimized integer order PI controller and the IOPID controller designed following the same synthesis for the FOPI in this paper. © 2012 Elsevier Ltd. All rights reserved.


Bai P.,South China Normal University | Tang T.,South China University of Technology | Tang B.,South China Normal University
Applied Thermal Engineering | Year: 2013

Three heat sinks with porous-coated parallel microchannels were fabricated by using a solid-state sintering method. The enhanced flow boiling of anhydrous ethanol in the porous-coated microchannels was systematically studied and compared to that of bare microchannels. The changes in pressure drop, flow boiling instability and flow boiling heat transfer performances caused by the introducing of porous coatings were discussed. The effect of particle size on pressure drop and heat transfer performance was also studied. The porous-coated microchannels showed significant mitigation of flow boiling instability, which was explained by the changes in bubble dynamics. Dramatic enhancement of flow boiling heat transfer in the porous-coated microchannels was obtained. The enhancement from porous coatings showed dependence on particle size and diminished with the increase of vapor quality. © 2013 Elsevier Ltd. All rights reserved.


Wang X.,Hefei University of Technology | Liu G.,Hefei University of Technology | Zhang G.,South China University of Technology
Langmuir | Year: 2011

Poly[(2-dimethylamino)ethyl methacrylate] (PDEM) is completely charged, partially charged, and uncharged at pH 4, 7, and 10, respectively. We have investigated the salt effects on the conformational change of PDEM chains grafted on a surface at different pH by using quartz crystal microbalance with dissipation (QCM-D) and surface plasmon resonance (SPR). The changes in frequency (Δf) and dissipation (ΔD) in QCM-D measurements demonstrate that the conformational behavior is governed by counterion condensation at pH 4 and 7 but by nonelectrostatic anion adsorption at pH 10. The addition of Na2SO4 induces more collapse of the grafted layer than that of NaClO3 at pH 4 and 7. However, they have a similar effect at pH 10. The shift of resonance unit (ΔRU) in SPR measurements reflects the changes of layer thickness and layer refractive index. At pH 4, ΔRU decreases with ionic strength in the presence of Na 2SO4, indicating the decrease of layer thickness or the chain collapse. However, ΔRU exhibits a minimum as the ionic strength increases in the case of NaClO3. This is because the effects of the layer thickness and refractive index are dominant in the low and high ionic strength regimes, respectively. At pH 7, ΔRU slightly varies with ionic strength in the case of either Na2SO4 or NaClO 3, indicating that the effects of the layer thickness and refractive index are comparable during the layer collapse. At pH 10, the shift in ΔRU suggests that the nonelectrostatic anion adsorption governs the conformational behavior of the PDEM chains. © 2011 American Chemical Society.


Yang H.,Hefei University of Technology | Xu J.,South China University of Technology | Pispas S.,National Hellenic Research Foundation | Zhang G.,Hefei University of Technology | Zhang G.,South China University of Technology
Macromolecules | Year: 2012

Copolymerization of ε-caprolactone and methyl methacrylate with (1-tert-butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino) phophoranylidenamino]-2,5,5-catenadi(phosphazene) (t-BuP 4) as the catalyst has been studied. Nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC) measurements indicate that the cyclic ester and vinyl monomer form a random copolymer. Thermogravimetric analysis (TGA) measurements demonstrate that such a random copolymer exhibits a decomposition temperature higher than those of the corresponding homopolymers. The present study reveals a hybrid copolymerization" i.e., a combination of vinyl polymerization and ring-opening polymerization, which makes the incorporation of cyclic and vinyl monomers into the same polymer chain possible. Hybrid copolymerization is expected to produce a number of new interesting polymers. © 2012 American Chemical Society.


Xiao X.,South China University of Technology | Xiao X.,South China Normal University | Zhang W.-D.,South China University of Technology
Journal of Materials Chemistry | Year: 2010

Self-assembled three-dimensional BiOI microspheres composed of nanoplatelets were synthesized at low temperature using ethanol-water mixed solvent as reaction media and NH3·H2O as pH adjustment. The as-prepared BiOI was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-vis diffuse reflectance spectroscopy, and nitrogen sorption. The possible formation mechanism for the architectures was discussed. It was found that mixed solvent and alkali play key roles in the formation of BiOI microspheres. The photocatalytic activity of the as-prepared sample was evaluated by degradation of phenol in aqueous solution under visible light irradiation. The BiOI microspheres show much higher photocatalytic activity than the random BiOI platelets. The total organic carbon measurement after the degradation process indicated that phenol was effectively mineralized over the BiOI microspheres. In addition, the BiOI microspheres are stable during the reaction and can be used repeatedly. The high catalytic performance of the BiOI microspheres comes from their narrow band gap, high surface area and high surface-to-volume ratio. © The Royal Society of Chemistry 2010.


Xue Y.,South China University of Technology | Jin L.,Terminals of Guangdong Higher Education Institutes
Conference Proceedings - IEEE International Conference on Systems, Man and Cybernetics | Year: 2010

In this paper, a naturalistic 3D acceleration-based activity dataset, the SCUT-NAA dataset, is created to assist researchers in the field of acceleration-based activity recognition and to provide a standard dataset for comparing and evaluating the performance of different algorithms. The SCUT-NAA dataset is the first publicly available 3D acceleration-based activity dataset and contains 1278 samples from 44 subjects (34 males and 10 females) collected in naturalistic settings with only one tri-axial accelerometer located alternatively on the waist belt, in the trousers pocket, and in the shirt pocket. Each subject was asked to perform ten activities. Benchmark evaluations of the dataset are provided based on FFT coefficients, DCT coefficients, time-domain features, and AR coefficients for the different accelerometer locations. ©2010 IEEE.


Xiang X.,South China University of Technology | Li X.,South China Normal University | Li W.,South China University of Technology | Li W.,South China Normal University
Journal of Power Sources | Year: 2013

Lithium-rich layered oxide, Li[Li0.131Ni0.304Mn 0.565]O2 with uniform particle size, is prepared through co-precipitation of metal hydroxide with synergistic dispersion of polyvinylpyrrolidone and ethylene glycol and subsequent solid reaction with lithium hydroxide. The crystal structure and morphology of the prepared sample is characterized with X-ray diffraction and scanning electron microscope. It is found that the prepared sample is a solid solution of Li2MnO 3 and LiNi0.5Mn0.5O2, with uniform particle size of about 230 nm. Charge/discharge tests indicate that the prepared sample exhibits improved elevated-temperature discharge capacity and cycling stability. In the region of 3.0-4.8 V, the prepared sample delivers initially a 0.1 C (1 C = 263 mAh g-1) capacity of 256 mAh g-1 at 50°C and 205 mAh g-1 at 25°C, and the 0.1 C capacity at 25°C retains 178 mAh g-1 after 60 cycles. The capacity decay mechanism is understood in detail through dQ/dV analyses. © 2012 Elsevier B.V. All rights reserved.


Hou S.,South China University of Technology | Ou Z.,South China Normal University | Chen Q.,Nankai University | Wu B.,South China Normal University
Biosensors and Bioelectronics | Year: 2012

A novel acetylcholinesterase (AChE)/choline oxidase (ChOx) bienzyme amperometric acetylcholine biosensor based on gold nanoparticles (AuNPs) and multi-walled carbon nanotubes (MWCNTs) has been successfully developed by self-assembly process in combination of sol-gel technique. A thiolated aqueous silica sol containing MWCNTs and ChOx was first dropped on the surface of a cleaned Pt electrode, and then AuNPs were assembled with the thiolated sol-gel network. Finally, the alternate deposition of poly (diallyldimethylammonium chloride) (PDDA) and AChE was repeated to assemble different layers of PDDA-AChE on the electrode for optimizing AChE loading. Among the resulting biosensors, the biosensor based on two layers of PDDA-AChE multilayer films showed the best performance. It exhibited a wide linear range, high sensitivity and fast amperometric response, which were 0.005-0.4. mM, 3.395 μA/mM, and within 15. s, respectively. The biosensor showed long-term stability and acceptable reproducibility. More importantly, this study could provide a simple and effective multienzyme immobilization platform for meeting the demand of the effective immobilization enzyme on the electrode surface. © 2011 Elsevier B.V.


He Q.,South China University of Technology | Wang S.,South China University of Technology | Tong M.,Chongqing University | Liu Y.,Chongqing University
Energy Conversion and Management | Year: 2012

In this article, a new sort of nanofluid phase change materials (PCMs) is developed by suspending a small amount of TiO2 nanoparticles in saturated BaCl2 aqueous solution. Its thermal conductivities, supercooling degree, latent heat, specific heat, and rheological behaviors of the nanofluids PCMs were investigated. The experimental results show that with volume fraction is 1.130%, the thermal conductivities of nanofluids PCMs is enhanced by 12.76% at -5 °C, the supercooling degree is reduced by 84.92%. The latent heat and specific heat are slightly decreased with suspending nanoparticles. The viscosity increased with the increasing volume fraction, which will have no effect on the cool storage system. The higher thermal performances of nanofluids PCMs indicate that they are suitable for the industries low temperature energy storage. © 2012 Elsevier Ltd. All rights reserved.


Lu R.,Hangzhou Dianzi University | Li Z.,South China University of Technology | Su C.-Y.,South China University of Technology | Su C.-Y.,Concordia University at Montréal | Xue A.,Hangzhou Dianzi University
IEEE Transactions on Industrial Electronics | Year: 2014

This paper describes a novel development of a lower limber exoskeleton for physical assistance and rehabilitation. The developed exoskeleton is a motorized leg device having a total of 4 DOF with hip, knee, and ankle actuated in the sagittal plane. The exoskeleton applies forces and learns the impedance parameters of both robot and human. An adaptive control scheme by incorporating learning control approaches into the exoskeleton system is developed to help the leg movement on a desired periodic trajectory and handle periodic uncertainties with known periods. The proposed control approach does not require a muscle model and can be proven to yield asymptotic stability for a nonlinear muscle model and an exoskeleton model in the presence of bounded nonlinear disturbances (e.g., spasticity and fatigue). The performance of the controller is demonstrated through closed-loop experiments on human subjects. The experiments illustrate the ability of the exoskeleton to enable the leg shank to track single and multiple period trajectories with different periods and ranges of motion. © 2013 IEEE.


Wan J.,South China University of Technology | Jones J.D.,Liberty University
Enterprise Information Systems | Year: 2013

The Warfield version of systems science supports a wide variety of application areas, and is useful to practitioners who use the work program of complexity (WPOC) tool. In this article, WPOC is applied to information technology service management (ITSM) for managing the complexity of projects. In discussing the application of WPOC to ITSM, we discuss several steps of WPOC. The discovery step of WPOC consists of a description process and a diagnosis process. During the description process, 52 risk factors are identified, which are then narrowed to 20 key risk factors. All of this is done by interviews and surveys. Root risk factors (the most basic risk factors) consist of 11 kinds of common 'mindbugs' which are selected from an interpretive structural model. This is achieved by empirical analysis of 25 kinds of mindbugs. (A lesser aim of this research is to affirm that these mindbugs developed from a Western mindset have corresponding relevance in a completely different culture: the Peoples Republic of China.) During the diagnosis process, the relationships among the root risk factors in the implementation of the ITSM project are identified. The resolution step of WPOC consists of a design process and an implementation process. During the design process, issues related to the ITSM application are compared to both e-Government operation and maintenance, and software process improvement. The ITSM knowledge support structure is also designed at this time. During the implementation process, 10 keys to the successful implementation of ITSM projects are identified. © 2013 Copyright Taylor and Francis Group, LLC.


Tao D.,South China University of Technology | Jin L.,South China University of Technology | Liu W.,China University of Petroleum - East China | Li X.,Chinese Academy of Sciences
IEEE Transactions on Multimedia | Year: 2013

With the rapid development of the cloud computing and mobile service, users expect a better experience through multimedia computing, such as automatic or semi-automatic personal image and video organization and intelligent user interface. These functions heavily depend on the success of image understanding, and thus large-scale image annotation has received intensive attention in recent years. The collaboration between mobile and cloud opens a new avenue for image annotation, because the heavy computation can be transferred to the cloud for immediately responding user actions. In this paper, we present a scheme for image annotation on the cloud, which transmits mobile images compressed by Hamming compressed sensing to the cloud and conducts semantic annotation through a novel Hessian regularized support vector machine on the cloud. We carefully explained the rationality of Hessian regularization for encoding the local geometry of the compact support of the marginal distribution and proved that Hessian regularized support vector machine in the reproducing kernel Hilbert space is equivalent to conduct Hessian regularized support vector machine in the space spanned by the principal components of the kernel principal component analysis. We conducted experiments on the PASCAL VOC'07 dataset and demonstrated the effectiveness of Hessian regularized support vector machine for large-scale image annotation. © 1999-2012 IEEE.


Wu Z.,South China University of Technology | Goshtasby A.,Wright State University
IEEE Transactions on Image Processing | Year: 2012

Advances in image acquisition systems have made it possible to capture high-resolution images of a scene, recording considerable scene details. With increased resolution comes increased image size and geometric difference between multiview images, complicating image registration. Through Voronoi subdivision, we subdivide large images into small corresponding regions, and by registering small regions, we register the images in a piecewise manner. Image subdivision reduces the geometric difference between regions that are registered and simplifies the correspondence process. The proposed method is a hierarchical one. While previous methods use the same block size and shape at a hierarchy, the proposed method adapts the block size and shape to the local image details and geometric difference between the images. This adaptation makes it possible to keep geometric difference between corresponding regions small and simplifies the correspondence process. Implementational details of the proposed image registration method are provided, and experimental results on various types of images are presented and analyzed. © 1992-2012 IEEE.


Chen K.,Nanjing University of Aeronautics and Astronautics | Yang L.,South China University of Technology
International Journal of Production Research | Year: 2014

This paper considers a supply chain in which a buyer purchases finished items from a contracting supplier to satisfy a stochastic market demand, where the suppliers production is subject to random yield. We assume that the buyer can make up the shortage by sourcing from an emergency backup supplier. We develop two Stackelberg game models, i.e. buyer-Stackelberg (BS) model and supplier-Stackelberg (SS) model, and find that the decentralised BS model results in a higher stocking factor of suppliers input than the decentralised SS model. Compared with BS model, the buyer in SS model performs more explicit order plan, and we find that only when the actual yield of the supplier is insufficient, the buyer would use emergency backup sourcing to make up the shortage. When the manufacturing operation of the supplier is in the good state, the buyer only orders a certain amount and has some leftover. When the actual yield of the supplier is moderate, the buyer uses up every item produced from the supplier regardless of the yield rate. Comparing both channel structures, SS operation is a more effective way of controlling both inventory cost and backup sourcing cost, and it can be beneficial for each player as well as for the whole channel. Finally, we develop the coordination mechanism for each channel to investigate the issues of risk handling and risk sharing for uncertain demand and uncertain yield. © 2014 Taylor & Francis.


Kong Y.-D.,South China University of Technology | Chu Q.-X.,South China University of Technology | Chu Q.-X.,State Key Laboratory of Millimeter Waves
IEEE Transactions on Antennas and Propagation | Year: 2011

High-order split-step unconditionally-stable finite-difference time-domain (FDTD) methods in three-dimensional (3-D) domains are presented. Symmetric operator and uniform splitting are adopted simultaneously to split the matrix derived from the classical Maxwell's equations into four sub-matrices. Accordingly, the time step is divided into four sub-steps. In addition, high-order central finite-difference operators based on the Taylor central finite-difference method are used to approximate the spatial differential operators first, and then the uniform formulation of the proposed high-order schemes is generalized. Subsequently, the analysis shows that all the proposed high-order methods are unconditionally stable. The generalized form of the dispersion relations of the proposed high-order methods is carried out. Moreover, the effects of the mesh size, the time step and the order of schemes on the dispersion are illustrated through numerical results. Specifically, the normalized numerical phase velocity error (NNPVE) and the maximum NNPVE of the proposed second-order scheme are lower than that of the alternating direction implicit (ADI) FDTD method. Furthermore, the analysis of the accuracy of the proposed methods is presented. In order to demonstrate the efficiency of the proposed methods, numerical experiments are presented. © 2006 IEEE.


Wang W.,South China University of Technology | Yang H.,South China University of Technology | Li G.,South China University of Technology | Li G.,University of Oxford
CrystEngComm | Year: 2013

The growth of c-plane GaN films on La0.3Sr 1.7AlTaO6 (LSAT) (111) substrates has been carried out by molecular beam epitaxy (MBE) at various substrate temperatures. GaN grown at 750 °C shows poor crystallinity with an up to 8 nm thick interim layer between LSAT and GaN, mainly due to the severe interfacial reaction between the substrate and the film. On the contrary, an atomically abrupt interface has been observed when GaN was grown at a lower temperature of 500 °C. This low-temperature grown GaN exhibits high crystallinity with a very smooth surface and strong band-edge emission, which we attribute to the well-controlled oxygen atom evaporation from LSAT substrate surface thanks to the low temperature growth. On the one hand, it avoids the severe interfacial reaction that takes place in the case of high-temperature epitaxial growth; on the other hand, it conserves the crystalline structure of the substrate surface, and consequently takes good advantage of the small lattice mismatch between GaN and LSAT. Considering the advantages of LSAT over sapphire, and the device-ready film quality of GaN achieved on LSAT, this work exhibits a promising future for high-performance light emitting diodes on this unconventional substrate. © 2013 The Royal Society of Chemistry.


Tao D.,South China University of Technology | Jin L.,South China University of Technology | Wang Y.,South China University of Technology | Li X.,CAS Xi'an Institute of Optics and Precision Mechanic
IEEE Transactions on Industrial Informatics | Year: 2014

With the rapid development of the intelligent sensing and the prompt growing industrial safety demands, human behavior recognition has received a great deal of attentions in industrial informatics. To deploy an utmost scalable, flexible, and robust human behavior recognition system, we need both innovative sensing electronics and suitable intelligence algorithms. Wireless sensor networks (WSNs) open a novel way for human behavior recognition, because the heavy computation can be immediately transferred to a network server. In this paper, a new scheme for human behavior recognition on WSNs is proposed, which transmits activities' signals compressed by Hamming compressed sensing to the network server and conducts behavior recognition through a collaboration between a new dimension reduction algorithm termed rank preserving discriminant analysis (RPDA) and a nearest neighbor classifier. RPDA encodes local rank information of within-class samples and discriminative information of the between-class under the framework of Patch Alignment Framework. Experiments are conducted on the SCUT Naturalistic 3D Acceleration-based Activity (SCUT NAA) dataset and demonstrate the effectiveness of RPDA for human behavior recognition. © 2005-2012 IEEE.


Li Z.,South China University of Technology | Su C.-Y.,South China University of Technology | Su C.-Y.,Concordia University at Montréal
IEEE Transactions on Neural Networks and Learning Systems | Year: 2013

In this paper, adaptive neural network control is investigated for single-master-multiple-slaves teleoperation in consideration of time delays and input dead-zone uncertainties for multiple mobile manipulators carrying a common object in a cooperative manner. Firstly, concise dynamics of teleoperation systems consisting of a single master robot, multiple coordinated slave robots, and the object are developed in the task space. To handle asymmetric time-varying delays in communication channels and unknown asymmetric input dead zones, the nonlinear dynamics of the teleoperation system are transformed into two subsystems through feedback linearization: local master or slave dynamics including the unknown input dead zones and delayed dynamics for the purpose of synchronization. Then, a model reference neural network control strategy based on linear matrix inequalities (LMI) and adaptive techniques is proposed. The developed control approach ensures that the defined tracking errors converge to zero whereas the coordination internal force errors remain bounded and can be made arbitrarily small. Throughout this paper, stability analysis is performed via explicit Lyapunov techniques under specific LMI conditions. The proposed adaptive neural network control scheme is robust against motion disturbances, parametric uncertainties, time-varying delays, and input dead zones, which is validated by simulation studies. © 2012 IEEE.


Zhu R.,South China University of Technology | Berakdar J.,Martin Luther University of Halle Wittenberg
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

We study the pump current and noise properties in an adiabatically modulated magnetic nanowire with double domain walls (DWs). The modulation is brought about by applying a slowly oscillating magnetic and electric fields with a controllable phase difference. The pumping mechanism resembles the case of the quantum dot pump with two-oscillating gates. The pump current, shot noise, and heat flow show peaks when the Fermi energy matches with the spin-split resonant levels localized between the DWs. The peak height of the pump current is an indicator for the lifetime of the spin-split quasistationary states between the DWs. For sharp DWs, the energy absorption from the oscillating fields results in sideband formations observable in the pump current. The pump noise carries information on the correlation properties between the nonequilibrium electrons and the quasiholes created by the oscillating scatterer. The ratio between the pump shot noise and the heat flow serves as an indicator for quasiparticle correlation. © 2010 The American Physical Society.


Wei D.Q.,Guangxi Normal University | Luo X.S.,Guangxi Normal University | Zhang B.,South China University of Technology
Physica A: Statistical Mechanics and its Applications | Year: 2012

In recent years several global blackouts have drawn a lot of attention to security problems in electric power transmission systems. Here we analyze the cascading failure in complex power networks based on the local preferential redistribution rule of the broken node's load, where the weight of a node is correlated with its link degree k as kβ. It is found that there exists a threshold α* such that cascading failure is induced and enhanced when the value of tolerance parameter is smaller than the threshold. It is also found that the larger β is the more robust the power network is. © 2011 Elsevier B.V. All rights reserved.


Zhang X.Y.,South China University of Technology | Zhang X.Y.,State Key Laboratory of Millimeter Waves | Chan C.H.,State Key Laboratory of Millimeter Waves | Xue Q.,State Key Laboratory of Millimeter Waves | Hu B.-J.,South China University of Technology
IEEE Transactions on Industrial Electronics | Year: 2012

This paper presents a novel approach to design RF tunable bandstop filters with constant absolute bandwidth. The filters are based on a doublet configuration which is attractive for high-order filter designs. In the doublet, two varactor-tuned resonators, arranged in a mirror-symmetrical manner, are coupled to a main transmission line. A novel coupling scheme is utilized between the resonators and the main line. Theoretical analysis indicates that, as the resonant frequency varies, the coupling coefficient within the fixed coupling region can be inherently changed to desirable values to meet the requirement of constant absolute bandwidth. Using the coupling scheme, constant absolute bandwidth can be obtained without extra circuits to control the coupling strengths. For demonstration, first-order and high-order filters are designed. Comparisons of experimental and simulated results are presented to verify the theoretical predications. © 2011 IEEE.


Jiang Z.,Ningbo University of Technology | Jiang Z.-J.,South China University of Technology | Tian X.,Ningbo University of Technology | Chen W.,Ningbo University of Technology
Journal of Materials Chemistry A | Year: 2014

Amine functionalized holey graphene (AFHG), synthesized by the hydrothermal reaction of GO and ammonia and the subsequent KOH etching, has been used as a metal-free catalyst for the oxygen reduction reaction (ORR). It shows that AFHG is highly active for the ORR and exhibits higher electrocatalytic activity than graphene, nitrogen-doped graphene (NG) and amine functionalized graphene (AFG), which could be demonstrated from its higher current density and more positive half-wave and onset potentials for the ORR. Although AFHG also exhibits a slightly higher overpotential towards ORR, it is indeed more kinetically facile than the commercial JM Pt/C 40 wt%. Its higher electrochemical performance could be attributed to the presence of the electron donating group (e.g. amine) and a large number of holes in its sheet plate and the porous structure in its randomly stacked solid, which provide AFHG with higher electrical conductivity, more active edge N atoms and easier accessibility to oxygen, respectively. The stability measurements show that AFHG is more stable than graphene, NG, AFG and the JM Pt/C 40 wt% and exhibits higher immunity towards methanol crossover and CO poisoning than the JM Pt/C 40 wt%. Over 10 h of the ORR, AFHG loses only <7% of its original activity in the absence of methanol or CO, and the introduction of methanol or CO has no effect on its oxygen reduction activity, which makes it highly desirable as a metal-free catalyst for the ORR. © 2013 The Royal Society of Chemistry.


Jiang Z.-J.,South China University of Technology | Jiang Z.,Ningbo University of Technology
ACS Applied Materials and Interfaces | Year: 2014

Nitrogen-doped holey graphene hollow microspheres (NHGHSs), synthesized through a template sacrificing method, were utilized as an anode material for lithium ion batteries (LIBs). Because of their specific microspherical hollow structure comprising nitrogen-doped holey graphene (NHG), the NHGHSs can exhibit reversible capacities of ∼1563 mAh g-1 at a low rate of 0.5 C and ∼254 mAh g-1 at a high rate of 20 C, which are significantly higher than the discharge capacity of the pristine graphene and other graphene-based carbonaceous materials. These, along with their good cycling stability, clearly demonstrate the great potential of using the NHGHSs as the anode material for LIBs of both high energy and power densities. We believe that the high specific surface area, holey structure of nitrogen-doped graphene, specific microspherical hollow structure, and increased interlayer spacing between the NHG nanosheets in their hollow walls are the main origins of their high electrochemical performance. © 2014 American Chemical Society.


Jiang Z.-J.,South China University of Technology | Jiang Z.,Ningbo University of Technology
Journal of Materials Chemistry A | Year: 2014

Nitrogen-doped hollow graphene microspheres (NHGSs), synthesized through a procedure involving the calcination of graphene-oxide-wrapped amine-functionalized mesoporous silica nanoparticles (AFMSNs) and the subsequent removal of the AFMSNs via HF etching, have been employed as an electrocatalyst for the oxygen reduction reaction (ORR). It has been shown that these NHGSs are highly active toward ORR and exhibit higher electrocatalytic activity than graphene, nitrogen-doped graphene (NG), hollow graphene microspheres (HGSs), and JM Pt/C 40 wt%, and a comparable overpotential to JM Pt/C 40 wt%. Their high electrocatalytic activity could be attributed to the N-doped graphitic structure, which produces more active sites for the ORR, allowing the easier adsorption of oxygen and the subsequent reduction; and the specific microspherical hollow structure, which promotes the exposure of more surface area accessible to electrolytes, thereby allowing an easier diffusion of electrolytes into and out of the electrode catalyst layers. Their low overpotential for the ORR can be attributed to the specific microspherical hollow structure, which reduces the overpotential contribution from the mass transport limitation. The stability measurements show that NHGSs also exhibit a much higher stability than graphene, NG, HGSs, and JM Pt/C 40 wt%, and are immune to the methanol crossover and CO poisoning effects, which all together makes NHGSs highly attractive as an electrocatalyst for the ORR. This journal is © the Partner Organisations 2014.

Loading South China University of Technology collaborators
Loading South China University of Technology collaborators