Showing papers by "Henan University of Technology published in 2015"

Finite-Time Cluster Synchronization of T–S Fuzzy Complex Networks With Discontinuous Subsystems and Random Coupling Delays

Abstract: This paper is concerned with the cluster synchronization in finite time for a class of complex networks with nonlinear coupling strengths and probabilistic coupling delays. The complex networks consist of several clusters of nonidentical discontinuous systems suffered from uncertain bounded external disturbance. Based on the Takagi–Sugeno (T–S) fuzzy interpolation approach, we first obtain a set of T–S fuzzy complex networks with constant coupling strengths. By developing some novel Lyapunov functionals and using the concept of Filippov solution, some new analytical techniques are established to derive sufficient conditions ensuring the cluster synchronization in a setting time. In particular, this paper extends the pinning control strategies for networks with continuous-time dynamics to discontinuous networks. Numerical simulations demonstrate that the theoretical results are effective and the T–S fuzzy approach is important for relaxed results.

Finite-time synchronization of coupled discontinuous neural networks with mixed delays and nonidentical perturbations

Abstract: This paper is concerned with the finite-time synchronization in an array of coupled neural networks with discontinuous activation functions, discrete and unbounded distributed delays (mixed delays), and norm-bounded nonidentical perturbations. Under the framework of Filippov solution, we first derive some general sufficient conditions to guarantee the global existence of the solutions to the neural networks with discontinuous activation functions and mixed delays. Then, by designing simple controller, applying some new analytical techniques, and constructing some new Lyapunov–Krasovskii functionals, several sufficient conditions are derived to ensure the finite-time synchronization of the considered networks. Moreover, the setting time is also estimated for the network under study with bounded delays or without delays. In sharp contrast to the existed results which can only finite-timely synchronize or stabilize the non-delayed systems, the theoretical results of this paper are more general and rigorous. Finally, numerical simulations are provided to illustrate the effectiveness of the theoretical analysis.

N-doped ordered mesoporous carbons prepared by a two-step nanocasting strategy as highly active and selective electrocatalysts for the reduction of O2 to H2O2

Abstract: A new, two-step nanocasting method was developed to prepare N-doped ordered mesoporous carbon (NOMC) electrocatalysts for the reduction of O2 to H2O2. Our strategy involves the sequential pyrolysis of two inexpensive and readily available N and C precursors, i.e. aniline and dihydroxynaphthalene (DHN), inside the pores of a SBA-15 hard silica template to obtain N-doped graphitic carbon materials with well-ordered pores and high surface areas (764 and 877 m2g−1). By tuning the ratio of carbon sources to silica template, it was possible to achieve an optimal filling of the pores of the SBA-15 silica and to minimise carbon species outside the pores. These NOMC materials displayed outstanding electrocatalytic activity in the oxygen reduction reaction, achieving a remarkably enhanced kinetic current density compared to state-of-the-art N-doped carbon materials (−16.7 mA cm−2 at −0.35 V vs. Ag/AgCl in a 0.1 M KOH solution as electrolyte). The NOMC electrocatalysts showed high selectivity toward the two-electron reduction of oxygen to hydrogen peroxide and excellent long-term stability.

Effects of different milling processes on whole wheat flour quality and performance in steamed bread making

Abstract: In recent years there has been growing interest in whole grain products. However, few studies have analyzed the influence of whole wheat flour on the quality of Chinese steamed bread. This study determined the influence of different milling processes on the physicochemical properties and steamed bread quality of whole wheat flour. A medium hard red wheat, soft white wheat and Canada hard wheat was used as raw materials. The milling processes including three entire grain grinding and four bran recombining processes. The wheat flour ground by roller mill was used as a control. Results showed that whole wheat flour made from entire grain grinding processes had higher viscosity values but lower particle size than bran recombining processes. Appropriate processes can improve the farinograph characteristics of whole wheat flour. Chinese steamed bread of whole wheat flour obtained from bran recombining had larger height/diameter ratio, specific volume than that from entire grain grinding processes. Ultrafine entire grain grinding process especially when using white wheat improved the color of steamed bread. The texture differences of steamed bread between whole wheat flour and flour were significant. Steamed bread of red wheat from heat-treated bran recombining (HTBR) process got the highest sensory score.

A novel acetylcholinesterase biosensor based on ionic liquids-AuNPs-porous carbon composite matrix for detection of organophosphate pesticides

Abstract: A novel acetylcholinesterase (AChE) biosensor, based on honeycomb-like hierarchically ion liquids ([BSmim]HSO4)-AuNPs-porous carbon composite modified boron-doped diamond (BDD) electrode, was developed for the detection of organophosphate pesticides. The surface morphology of the prepared [BSmim]HSO4-AuNPs-porous carbon composite was characterized by scanning electron microscopy and transmission electron microscopy. The [BSmim]HSO4-AuNPs-porous carbon modified BDD electrode was confirmed by cyclic voltammogram and electrochemical impedance spectroscopy. For the oxidation of thiocholine, hydrolysis product of acetylthiocholine, the peak current at AChE/[BSmim]HSO4-AuNPs-porous carbon/BDD electrode is more than 4.5 times that at AChE/BDD electrode. The inhibition of dichlorvos is linearly proportional to its concentration in the range of 10−10–10−6 g/L (4.5 × 10−13–4.5 × 10−9 M), with the detection limit of 6.61 × 10−11 g/L (2.99 × 10−13 M) (calculated for 10% inhibition). The proposed biosensor provided an efficient and promising platform for the immobilization of AChE and exhibited higher sensitivity and acceptable stability for the detection of organophosphate pesticides.

Enhancement of magnetism by structural phase transition in MoS2

Abstract: The magnetic properties of 2H phase of MoS2 (2H-MoS2) and 1T phase of MoS2 (1T-MoS2) were investigated both experimentally and theoretically. Lithium (Li) intercalation method was used to prepare single-layer MoS2 sheets. It was found that pristine MoS2 (2H-MoS2) exhibited weak diamagnetism. After exfoliating by Li intercalation, the crystal structure transformed from 2H to 1T phase, and the magnetism was significantly enhanced from diamagnetism to paramagnetism accordingly. With further annealing in argon atmosphere, the 2H phase recovered gradually from 1T phase, and the magnetism decreased correspondingly. Using crystal field theory and combining the results of first principle calculation, we conclude that the enhanced magnetism can be attributed to the Mo atoms of 1T-MoS2.

Basic Ionic Liquid Supported on Mesoporous SBA-15 Silica as an Efficient Heterogeneous Catalyst for Biodiesel Production

Abstract: In the present study, SBA-15 silica-supported basic ionic liquid was prepared through grafting of 4-butyl-1,2,4-triazolium hydroxide onto SBA-15 silica using 3-chloropropyltriethoxysilane as a coup...

An acetylcholinesterase biosensor based on ionic liquid functionalized graphene–gelatin-modified electrode for sensitive detection of pesticides

Abstract: Ionic liquid functionalized graphene (IL-GR) was synthesized through epoxide ring-opening reaction. A highly sensitive acetylcholinesterase (AChE) biosensor based on IL-GR and Gelatin (Gel) modified glassy carbon electrode (GCE) has been successfully developed. IL-GR was homogeneously dispersed in Gel and dropped on the surface of GCE. Glutaraldehyde (GA) was used as cross-linker to immobilize the AChE on IL-GR–Gel modified GCE. The IL-GR–Gel nanocomposite with excellent conductivity and biocompatibility offered an extremely hydrophilic surface for AChE adhesion. It effectively promoted the electron transfer rate of electrode interface and facilitated the access of substrates to the active centers. The modified electrode was used for the electrochemical detection of carbaryl and monocrotophos after adsorbing AChE on the biocompatible matrix. Under optimum conditions, the biosensor detected carbaryl and monocrotophos ranging from 1.0 × 10−14 to 1.0 × 10−8 M and from 1.0 × 10−13 to 5.0 × 10−8 M. The detection limits for carbaryl and monocrotophos were 5.3 × 10−15 M and 4.6 × 10−14 M, respectively. The developed biosensor exhibited many advantages such as high sensitivity, acceptable stability and low cost, thus providing a promising tool for analysis of enzyme inhibitors.

Synthesis of Mn3O4 nanoparticles/nitrogen-doped graphene hybrid composite for nonenzymatic glucose sensor

Abstract: Through a simple method, a new kind of Mn3O4 nanoparticles (Mn3O4NPs) decorated nitrogen-doped graphene (N-GR) was synthesized firstly, and then a Mn3O4NPs/N-GR modified carbon paste electrode (CPE) was fabricated. Several techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and electrochemistry, were performed to characterize Mn3O4NPs/N-GR. A large amount of N on the graphene surface (about 9.86% of atomic ratio) was detected by XPS. Mn3O4 nanoparticles (50–80 nm) homogeneously coated on N-GR. Mn3O4NPs/N-GR/CPE was used for sensitive non-enzymatic glucose sensing, which exhibited the response current of glucose ca. 10-fold higher than that of pure CPE. Under the optimum determination conditions, Mn3O4NPs/N-GR/CPE provided glucose with a broader detection range of 2.5–529.5 μM with a low detection limit (1.0 μM, S/N = 3). This novel method was successfully used to determine glucose in human urine sample.

Effect of degradation methods on the structural properties of citrus pectin

Abstract: The molecular mass and its distribution of citrus pectin degraded by different methods were investigated. The primary structure and nanostructure of the degraded products were also identified. The results indicated that acid (80 °C, 12 h), ultrasound-assisted acid (25 °C, 2.5 h) and ultrasound (25 °C, 1.5 h) degraded pectins had equivalent molecular mass. The molecular mass distribution of ultrasound-assisted acid and ultrasound degraded pectins were less polydisperse than that of acid degraded pectin. According to HPLC, IR and NMR analysis, the main chain of ultrasound degraded pectin could be preserved. By contrast, acid degraded pectin was completely free of neutral sugar-side chains. Furthermore, the esterification level of ultrasound-assisted acid and ultrasound degraded pectins was considerably lower than that of original pectin, whereas that of the acid degraded pectin was nearly equal to zero. AFM analysis indicated that the morphology of original pectin was different from that of degraded pectins. The length of linear chains of degraded pectins was shorter and density of branches was lower, compared with that of original pectin. The results indicated that the ultrasound degradation method has the advantage of being timesaving, milder and environment-friendly.

Generating project risk response strategies based on CBR

Abstract: A new pragmatic CBR-based method for generating project risk response strategies is proposed.The most similar historical cases can be retrieved using the method.The inapplicable strategies are revised to support the generation of the candidate strategy set.The desirable project risk response strategies are generated through the expert's evaluations.Case problem on risk response of the subway project is solved based on this study. Risk response is an important work in project risk management (PRM). To generate project risk response strategies, retrieving and reusing information and knowledge of the similar historical cases is important, while research concerning this issue is still relatively scarce. Taking the risk response of the subway project in S city, China as a case problem, this paper proposes a pragmatic method for generating project risk response strategies based on the case-based reasoning (CBR). The procedure of the method include the five parts: first, representing the target case and the historical cases; second, retrieving the available historical cases by judging whether the risks involved in each historical case cover or are the same as those in the target case; third, retrieving the similar historical cases by measuring the similarity between each available historical case and the target case; fourth, revising the inapplicable risk response strategies involved in the similar historical cases by analyzing the response relation between each strategy and each risk of the current project; and generating the desirable risk response strategies by evaluating each candidate risk response strategy set. To illustrate the use of the proposed method, an empirical analysis of generating the risk response strategies for the subway station project is given. The proposed method can support project managers to make the better decision in PRM.

Mechanically Tough, Thermally Rearranged (TR) Random/Block Poly(benzoxazole-co-imide) Gas Separation Membranes

Abstract: Insufficient mechanical properties are one of the major obstacles for the commercialization of ultrahigh permeability thermally rearranged (TR) membranes in large-scale gas separation applications. The incorporation of preformed benzoxazole/benzimidazole units into o-hydroxy copolyimide precursors, which themselves subsequently thermally rearrange to form additional benzoxazole units, were prepared for the first time. Using commercially available monomers, mechanically tough membranes prepared from random and block TR poly(benzoxazole-co-imide) copolymers (TR-PBOI) were investigated for gas separation. The effects of the chemical structures, copolymerization modes, and thermal holding time of o-hydroxy copolyimides on the molecular packing and properties, including gas transport, for the resulting TR-PBOI membranes have been examined in detail. After treatment at 400 °C, tough TR-PBOI membranes exhibited tensile strengths of 71.4–113.9 MPa and elongation at break of 5.1–16.1%. Moreover, they presented hig...

Effect of ozone treatment on deoxynivalenol and quality evaluation of ozonised wheat.

Abstract: Deoxynivalenol (DON) is the secondary metabolite of Fusarium graminearum, which is always found in Fusarium head blight of wheat. In this study, gaseous ozone was used to treat both DON solution and scabbed wheat to investigate the effectiveness of ozone treatment on DON degradation and the effect of ozone on the quality parameters of wheat. It was found that gaseous ozone had a significant effect on DON reduction in solution, when 10 mg l(-1) gaseous ozone was used to treat a 1 μg ml(-1) of DON solution, the degradation rate of DON was 93.6% within 30 s. Lower initial concentrations of DON solution treated with higher concentrations of ozone, and longer times showed higher DON degradation rates. Gaseous ozone was effective against DON in scabbed wheat. The degradation rate of DON increased with ozone concentration and processing time. The correlation between the time and degradation rate was y = -1.1926x(2) + 11.427x - 8.7787. In the process of ozone oxidation, a higher moisture content of wheat was more sensitive than that of lower moisture content to ozone under the same conditions. All samples were treated with different concentrations of ozone for 4 h to investigate the effect of ozone on wheat quality. No significant detrimental changes in the starch pasting properties of wheat were observed after all the samples were treated with ozone within 4 h. On the other hand, there was a slight rise in the dough development time and stability time, which meant the quality of flour improved after ozone treatment.

Monolayer MoS2 quantum dots as catalysts for efficient hydrogen evolution

Abstract: Monolayer MoS2 quantum dots (QDs) with lateral size around 3 nm were prepared through an effective multi-exfoliation based on lithium (Li) intercalation. The effects of the number of exfoliation on the microstructures and electrocatalytic activities of hydrogen evolution reaction (HER) for MoS2 nanosheets were examined. The lateral size of the nanosheets decreases rapidly with increasing the number of exfoliation. The obtained monolayer MoS2 QDs exhibit improved HER catalytic activities with a low overpotential of approximately 120 mV and a relatively small Tafel slope of 69 mV dec−1. Both the ultrathin structure and the abundance of exposed active edge sites make monolayer MoS2 QDs a promising HER electrocatalyst for practical application.