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High performance Graphene-MnO2-polyaniline (Graphene/MnO2/PANI) nanocomposite was synthesized by hydrothermal process. The structure and morphology of Graphene/MnO2/PANI nanocomposite were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). The electrochemical properties of composite were evaluated by constant current charge–discharge, cyclic voltammetry and AC impedance, respectively. The results show that the prepared Graphene/MnO2/PANI nanocomposite exhibits greatly enhanced specific capacitance (305 F g−1) as compared to that of pristine graphene (155 F g−1) and MnO2/PANI (240 F g−1) in 1 M Na2SO4 solution. In addition, the capacity of the Graphene/MnO2/PANI nanocomposite still maintains 90 % after 1000 charge–discharge cycles at a current density of 1 A g−1, exhibiting potential applications in electrode materials for supercapacitors.

High performance actived carbon–MnO2–polyaniline (AC/MnO2/PANI) composite was synthesized via a two-step method. AC/MnO2 was firstly obtained by a chemical co-precipitation procedure, and then exposed to an in situ polymerization process of aniline under acidic conditions to form the AC/MnO2/PANI composite. The structures and morphologies of the products were characterized by X-ray powder diffraction, scanning electron microscopy, and Fourier-transform infrared spectroscopy. Results show that the AC/MnO2/PANI hybrid exhibits better capacitance than that of pure AC and the AC/MnO2 electrodes.

The s-triazine herbicide, atrazine, has been well acknowledged as an important source causing contamination of soil, water, and sediment. Functional bacteria are one of the critical candidates for removing residual atrazine from contaminated environments. Here, seven bacterial strains showing atrazine-degrading ability were isolated from long-term atrazine-contaminated corn field and identified based on 16S rRNA gene sequencing. Among these bacterial isolates, a bacterium, later designated as Arthrobacter sp. C3, was found to be capable of completely degrading 25 mg/l atrazine. The high-performance liquid chromatography-mass spectrometry (HPLC-MS) analysis indicated that the atrazine was dechlorinated to hydroxyatrazine, a non-phytotoxic compound. The functional gene, trzN, which participates in the first step of atrazine degradation was successfully amplified and showed high similarity to the known trzN genes from different bacterial genera. Based on the HPLC-MS and the functional gene analysis, the functional bacterium C3 was speculated to degrade atrazine via dechlorination, which detoxified the herbicide. This study suggested a great potential of Arthrobacter sp. C3 to be used in indigenous bioremediation of atrazine in field.

In this research, we explored a rapid assessment of silver nanoparticles (Ag-NPs) neurotoxicity at a single-cell level. Traditional nanotoxicity assays on large cell-populations may hide the important heterogeneity of individual cells often found in neuronal cells. The development in the area of new nanomaterial discoveries is far ahead of the development of advanced tools to measure these materials’ toxicity. Development of alternative approaches to assess nanomaterials toxicity rapidly, reliably, and accurately is desirable. Here, we present a chip-based, cell-integrated microwell-array device for rapid assessment of neurotoxicity of Ag-NPs by monitoring the exocytosis function of a PC12 cell. Results presented here confirm the dose-dependent toxicity of Ag-NPs and the immediate alteration of their exocytosis function when exposed to NPs.

A facet-dependent electrochemiluminescence (ECL) behavior was found for nanostructured ZnO with different dominant exposing planes. The ECL spectrum of nanostructured ZnO was recorded by the emission scan mode with a fluorescence spectrometer and applied to investigate the difference of surface state for different crystal planes. Electronic structure calculations based on density functional theory were used to study the effect of crystal plane on the band structure and density of states. It revealed that the ECL emission was originated primarily from the recombination of electrons from Zn 4s and the hole from O 2p, which could be utilized to study the physical and chemical properties of surface structures of as-prepared nanostructured ZnO. A physical model was suggested to elucidate the differences of ECL spectra. A concept was proposed that the energy released as photons during ECL process of nanocrystalline semiconductor materials will be correlated with the energy level of active sites located at different crystal planes.

A glassy carbon electrode modified with poly (3-methylthiophene) (P3MT) and coated with multiwall carbon nanotubes (MWNTs) film was fabricated and used for highly selective and sensitive determination of hydroquinone and catechol. The electrode combines the advantages of using P3MT and MWNTs, and exhibits a dramatic electro-catalytic effect on the oxidation of hydroquinone and catechol. This resulted in a marked enhancement of the current response. The peaks for hydroquinone and catechol are separated by about 101 mV in pH 6.4 phosphate buffer which enables simultaneous determination of both via cyclovoltammetry. Good linear relationships between the peak current and concentration were observed for single solution of hydroquinone (or catechol) by differential pulse voltammetry. The detection limits are 12 nmol L−1 and 40 nmol L−1 (at an S/N of 3). When simultaneously changing the concentration of both hydroquinone and catechol, the linear responses are in the range from 0.5 to 200 µmol L−1 for hydroquinone, and from 0.5 to 150 µmol L−1 for catechol, and the detection limits are 50 nmol L−1 (S/N = 3) for both hydroquinone and catechol. This method is simple, rapid, and accurate.

A composite film of DNA/poly(3-methylthiophene) (P3MT) modified glassy carbon electrode (GCE) has been fabricated by electro-deposition method. P3MT film was first electropolymerized at the GCE and the DNA layer was then immobilized on the P3MT layer by electrochemical method. The voltammetric behavior of 8-hydroxy-2′-deoxyguanosine (8-OH-dG) at the composite film modified electrode was studied. The effects of scan rates, pH and the interference of uric acid (UA) on the voltammetric behavior and detection of 8-OH-dG were also discussed. The experimental results suggest that the electrochemical behavior of 8-OH-dG at the composite film modified electrode was greatly improved due to the combination of the advantages of P3MT and DNA. In 0.1 M pH 7.0 phosphate buffer solution (PBS), the anodic peak currents of 8-OH-dG were linear with the 8-OH-dG concentration in two intervals, viz. 0.28–4.2 µM and 4.2–19.6 µM. The detection limit of 56 nM 8-OH-dG could be estimated (S/N = 3). This proposed composite film modified electrode shows excellent reproducibility and stability. It may have the potential application for the detection of 8-OH-dG in human urine.

A novel glucose biosensor was constructed by immobilizing the glucose oxidase (GOD) on a hydroxyapatite (HAp)/Nafion composite film modified glassy carbon electrode (GCE) and applied to the highly selective and sensitive determination of glucose. With the cooperation of HAp and Nafion, the composite film played an important role in enhancing the stability and sensitivity of the biosensor. The results demonstrate that the GOD adsorbed onto the HAp/Nafion composite film exhibits a pair of well-defined nearly reversible redox peaks and fine catalysis to the oxidation of glucose companied with the consumption of dissolved oxygen. On the basis of the decrease of the reduction current of dissolved oxygen at the applied potential of −0.80 V (vs. SCE) upon the addition of glucose, the concentration of glucose could be detected sensitively and selectively. The decreased reduction current was linear with the concentration of glucose in the range of 0.12–2.16 mM. The detection limit and sensitivity were 0.02 mM (S/N = 3) and 6.75 mA·M−1, respectively. All the results demonstrate that HAp/Nafion composite film provides a novel and efficient platform for the immobilization of enzymes and realizes the direct electrochemistry. The composite materials should have potential applications in the fabrication of third-generation biosensors.

The temperature distribution of typical n-type polycrystalline silicon thin film transistors under self-heating (SH) stress is studied by finite element analysis. From both steady-state and transient thermal simulation, the influence of device power density, substrate material, and channel width on device temperature distribution is analyzed. This study is helpful to understand the mechanism of SH degradation, and to effectively alleviate the SH effect in device operation.