para-Sulfonatocalix[6]arene-modified silver nanoparticles electrodeposited on glassy carbon electrode: Preparation and electrochemical sensing of methyl parathion

In this paper, a new electrochemical sensor, based on modified silver nanoparticles, was fabricated using one-step electrodeposition approach. The para-sulfonatocalix[6]arene-modified silver nanoparticles coated on glassy carbon electrode (pSC₆-Ag NPs/GCE) was characterized by attenuated total reflection IR spectroscopy (ATR-IR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), etc. The pSC₆ as the host are highly efficient to capture organophosphates (OPs), which dramatically facilitates the enrichment of nitroaromatic OPs onto the electrochemical sensor surface. The combination of the host-guest supramolecular structure and the excellent electrochemical catalytic activities of the pSC₆-Ag NPs/GCE provides a fast, simple, and sensitive electrochemical method for detecting nitroaromatic OPs. In this work, methyl parathion (MP) was used as a nitroaromatic OP model for testing the proposed sensor. In comparison with Ag NPs-modified electrode, the cathodic peak current of MP was amplified significantly. Differential pulse voltammetry was used for the simultaneous determination of MP. Under optimum conditions, the current increased linearly with the increasing concentration of MP in the range of 0.01-80 μM, with a detection limit of 4.0 nM (S/N = 3). The fabrication reproducibility and stability of the sensor is better than that of enzyme-based electrodes. The possible underlying mechanism is discussed.     

Transition metal complexes as linkages for assembly of supertetrahedral T4 clusters

Tn clusters are usually connected into frameworks by sulfur bridges. A new type of T4 compounds in which the clusters are linked by both sulfur bridges and transition metal complexes are described.     

Theoretical study of the inhibitive properties of a group of benzimidazoles

In this work, a group of benzimidazoles, namely benzimidazole (BIM), 2‐hexyl benzimidazole (2‐HBIM), and 2‐benzyl chloride benzimidazole (2‐ClBBIM), have been studied using density functional theory (DFT) at the level of B3LYP with the 6‐31G (d) and 6‐311G (d, p) base sets in order to elucidate the different inhibition efficiencies and reactive sites of these compounds as corrosion inhibitors. Based on the calculated results, the studied molecules interact with Fe‐atoms mainly in their stable pyridine‐N protonated forms. It is found that the inhibition efficiencies of the stable protonated molecules involved in this study have a certain relation with some parameters, such as the highest occupied molecular orbital energy (E_HOMO) and the global hardness (η). The results indicate that the C (7) atoms, as the reactive sites, receive electrons from Fe‐atoms, benzene ring denote electrons to vacant orbital of Fe‐atoms. Additionally, Fukui indices and the orbital analyses suggest that 2‐ClBBIM has the highest reaction activity among the three molecules, the efficiency order of three inhibitors is found to be 2‐ClBBIM > 2‐HBIM > BIM, which accords with experimental results. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Synthesis, electrochemical, and gas sensitivity performance of polyaniline/MoO3 hybrid materials

Hybrid material of polyaniline with molybdenum trioxide (MoO ₃ ) xerogel obtained by ion exchange of (NH ₄ ) ₆ Mo ₇ O ₂₄ ·4H ₂ O was synthesized via polymerization of the monomer by ammonium peroxydisulfate/HCl oxidant system. The properties of MoO ₃ and hybrid material were investigated through thermogravimetry, X-ray diffraction, scanning electron microscopy, charge–discharge test, cyclic voltammetry, electrochemical impedance spectroscopy, and gas sensing experiments. Results show that hybrid material exhibits higher capacity, more excellent cycling reversibility, and better sensitivity to ethanol gas than MoO ₃ xerogel.     

Electrochemical Behavior of Herbal Antitumor Drug Aloe‐Emodin at Carbon‐Coated Nickel Magnetic Nanoparticles Modified Glassy Carbon Electrode

The electrochemical behavior of aloe‐emodin (AE), an important herbal antitumor drug, was investigated at a carbon‐coated nickel magnetic nanoparticles modified glassy carbon electrode (CNN/GCE). A couple of well‐defined redox peaks was obtained. Some electrochemical parameters of AE at a CNN/GCE, such as the charge number, exchange current density, standard heterogeneous rate constant, were measured. The square wave voltammetry (SWV) response of AE was linear with the concentration over two concentration intervals viz. 6.24×10^?9?1.13×10^?6 M and 1.13×10^?6?1.23×10^?5 M, with a detection limit of 2.08 nM. A fast, simple and sensitive detection and analysis of AE was developed.     

Solvothermal synthesis of well-defined TiO(2) mesoporous nanotubes with enhanced photocatalytic activity

High efficiency TiO(2) photocatalyst in porous nanotubes were prepared by solvothermal alcoholysis of TiOSO(4) in the presence of carbon nanotube template.     

Effect of isothermal annealing on degree of crystallinity and mechanical properties of poly(l‐lactide‐co‐glycolide)

We investigated the effect of isothermal annealing on the degree of crystallinity and mechanical properties of a random copolymer‐poly(l‐lactide‐co ‐glycolide) (PLLGA)‐with monomer molar ratios of 85/15 (PLLGA85/15) by performing polarizing optical microscopy, differential scanning calorimetry, and X‐ray diffraction, and studying the tensile properties. Isothermal annealing of PLLGA at 130 °C was conducted to improve the degree of crystallinity of the copolymer; the maximum degree of crystallinity (44.5%) was achieved after 60 min of annealing. The crystal size/perfection was observed to increase with annealing time. The highest tensile strength of 65.8 MPa was achieved after 80 min of annealing. However, the degree of crystallinity and tensile strength can only reach to certain extent. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Development of fluorescent FeIII sensor based on chalcone

In this paper, 4-dimethylamino 2,5-dihydroxy chalcone (DMADHC), which exhibits excited state intramolecular charge transfer (ICT) characteristics, was synthesized and characterized. A sensitive optochemical sensor for Fe³⁺ ion was developed using DMADHC as fluorescence receptor. The fluorescence of DMADHC was gradually quenched with the addition of Fe³⁺ ion, which attributed to the formation of 1:1 complex between DMADHC and Fe³⁺ ion. The sensor exhibited excellent selectivity for Fe³⁺ ion over a large number of cation ions such as alkali, alkaline earth and transitional metal ions with a linear range of 3.984×10⁻⁷-1.135×10⁻⁵ and a limit of detection of 8.223×10⁻⁸ mol/L. On this basis, the sensor was preliminary applied to the determination of the content of iron ions in multi-vitamin tablet with satisfied results and the recoveries were in the 95-100% interval, and precision (n=5) was better than 5%.     

Visualizing electronic chirality and Berry phases in graphene systems using photoemission with circularly polarized light

Electronic chirality near the Dirac point is a key property of graphene systems, which is revealed by the spectral intensity patterns as measured by angle-resolved photoemission spectroscopy under various polarization conditions. Specifically, the strongly modulated circular patterns for monolayer (bilayer) graphene rotate by ±90° (±45°) in changing from linearly to circularly polarized light; these angles are directly related to the phases of the wave functions and thus visually confirm the Berry's phase of π (2π) around the Dirac point. The details are verified by calculations.     

Combining clustering and classification for remote-sensing images using unlabeled data

A joint clustering and classification approach is proposed.This approach exploits unlabeled data for efficient clustering,which is applied in the classification with support vector machine(SVM) in the case of small-size training samples.The proposed method requires no prior information on data labels,and yields better cluster structures.Through cluster assumption and the notions of support vectors,the most confident k cluster centers and data points near the cluster boundaries are labeled and used to train a reliable SVM classifier.Our method gains better estimation of data distributions and mitigates the unrepresentative problem of small-size training samples.The data set collected from Landsat Thematic Mapper(Landsat TM-5) validates the effectiveness of the proposed approach.