摘要：
A graphene oxide (GO) film coated glassy carbon electrode (GCE) was fabricated for sensitive determination of 4-nitrophenol (4-NP). The GO-based sensor was characterized by scanning electron microscope, atomic force microscopy and electrochemical impedance spectroscopy. The electrochemical behaviors of 4-NP at the GO-film coated GCE were investigated in detail. In 0.1 M acetate buffer with a pH of 4.8, 4-NP yields a very sensitive and well-defined reduction peak at the GO-modified GCE. It is found that the GO film exhibits obvious electrocatalytic activity toward the reduction of 4-NP since it not only increases the reduction peak current but also lowers the reduction overpotential. Based on this, an electrochemical method was proposed for the direct determination of 4-NP. Various kinetic parameters such as transfer electron number, transfer proton number and standard heterogeneous rate constant were calculated, and various experimental parameters were also optimized. Under the optimal conditions, the reduction peak current varies linearly with the concentration of 4-NP ranging from 0.1 to 120 mu M, and the detection limit is 0.02 mu M at the signal noise ratio of 3. Moreover, the fabricated sensor presented high selectivity and long-term stability. This electrochemical sensor was further applied to determine 4-NP in real water samples, and it showed great promise for simple, sensitive, and quantitative detection of 4-NP. (C) 2011 Elsevier B.V. All rights reserved.
期刊：
Computer Vision and Image Understanding,2016年150:109-125 ISSN：1077-3142
通讯作者：
Peng, Xiaojiang
作者机构：
Hengyang Normal Univ, Coll Comp Sci & Technol, Hengyang, Peoples R China.;Swiss Fed Inst Technol, Comp Vis Lab, Zurich, Switzerland.;Chinese Acad Sci, Shenzhen Inst Adv Technol, Shenzhen, Peoples R China.;INRIA, LEAR Team, Grenoble, France.;[Peng, Xiaojiang] College of Computer Science and Technology, Hengyang Normal University, Hengyang, China
通讯机构：
[Peng, Xiaojiang] Hengyang Normal Univ, Coll Comp Sci & Technol, Hengyang, Peoples R China.;[Peng, Xiaojiang] Chinese Acad Sci, Shenzhen Inst Adv Technol, Shenzhen, Peoples R China.;[Peng, Xiaojiang] INRIA, LEAR Team, Grenoble, France.
关键词：
Action recognition;Bag of visual words;Fusion methods;Feature encoding
摘要：
Video based action recognition is one of the important and challenging problems in computer vision research. Bag of visual words model (BoVW) with local features has been very popular for a long time and obtained the state-of-the-art performance on several realistic datasets, such as the HMDB51, UCF50, and UCF101. BoVW is a general pipeline to construct a global representation from local features, which is mainly composed of five steps; (i) feature extraction, (ii) feature pre-processing, (iii) codebook generation, (iv) feature encoding, and (v) pooling and normalization. Although many efforts have been made in each step independently in different scenarios, their effects on action recognition are still unknown. Meanwhile, video data exhibits different views of visual patterns , such as static appearance and motion dynamics. Multiple descriptors are usually extracted to represent these different views. Fusing these descriptors is crucial for boosting the final performance of an action recognition system. This paper aims to provide a comprehensive study of all steps in BoVW and different fusion methods, and uncover some good practices to produce a state-of-the-art action recognition system. Specifically, we explore two kinds of local features, ten kinds of encoding methods, eight kinds of pooling and normalization strategies, and three kinds of fusion methods. We conclude that every step is crucial for contributing to the final recognition rate and improper choice in one of the steps may counteract the performance improvement of other steps. Furthermore, based on our comprehensive study, we propose a simple yet effective representation, called hybrid supervector, by exploring the complementarity of different BoVW frameworks with improved dense trajectories. Using this representation, we obtain impressive results on the three challenging datasets; HMDB51 (61.9%), UCF50 (92.3%), and UCF101 (87.9%).
摘要：
A unique 4-fold interpenetrated (10,3)-b copper(II) framework exhibits reversible dehydration and rehydration in a single-crystal-to-single-crystal (SC-SC) process, and the dehydrated material can encapsulate CH(3)OH molecules, again in a SC-SC fashion, and shows selective adsorption of H(2) and CO(2) over N(2).
摘要：
Well-dispersed Pd nanoparticles were facilely anchored on graphene oxide (Pd/GO) via a one-pot chemical reduction of the Pd2+ precursor without any surfactants and templates. The morphology and composition of the Pd/GO nanocomposite were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FUR) and energy dispersive analysis of X-ray (EDX). The stepwise fabrication process of the Pd/GO modified electrode and its electrochemical sensing performance towards paracetamol was evaluated using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The experimental results indicate that the as-synthesized Pd nanoparticles are relatively uniform in size (5-10 nm) without large aggregation and uniformly distributed in the carbon matrix with the overall Pd content of 28.77 wt% in Pd/GO. Compared with the GO modified electrode, the Pd/GO modified electrode shows a better electrocatalytic activity to the oxidation of paracetamol with lower oxidation potential and larger peak current, so the Pd/GO nanocomposite can be used as an enhanced sensing platform for the electrochemical determination of paracetamol. The kinetic parameters of the paracetamol electro-oxidation at Pd/GO electrode were studied in detail, and the determination conditions were optimized. Under the optimal conditions, the oxidation peak current is linear to the paracetamol concentration in the ranges of 0.005-0.5 mu M and 0.5-80.0 mu M with a detection limit of 2.2 nM. Based on the high sensitivity and good selectivity of the Pd/GO modified electrode, the proposed method was successfully applied to the determination of paracetamol in commercial tablets and human urines, and the satisfactory results confirm the applicability of this sensor in practical analysis. (C) 2013 Elsevier B.V. All rights reserved.
摘要：
A new kind of nanocomposite based on silver nanoparticles (AgNPs)/graphene oxide (GO) was conveniently achieved through a green and low-cost synthesis approach using glucose as a reducing and stabilizing agent, and the synthetic procedure can be easily used for the construction of a disposable electrochemical sensor on glassy carbon electrode (GCE). The nanocomposite was detailedly characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR) and electrochemical impedance spectroscopy (EIS). The experimental results demonstrated that the nanocomposite possessed the specific features of both silver nanoparticles and graphene, and the intrinsic high specific area and the fast electron transfer rate ascribed to the nanohybrid structure could improve its electrocatalytic performance greatly. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed to evaluate the electrochemical properties of AgNPs/GO/GCE towards tryptophan, and the AgNPs/GO film exhibited a distinctly higher activity for the electro-oxidation of tryptophan than GO film with tenfold enhancement of peak current. The oxidation mechanism and the kinetic parameters were investigated, and analysis operation conditions were optimized. Under the selected experimental conditions, the oxidation peak currents were proportional to tryptophan concentrations over the range of 0.01 mu M to 50.0 mu M and 50.0 mu M to 800.0 mu M, respectively. The detection limit was 2.0 nM (S/N=3). Moreover, the proposed method is free of interference from tyrosine and other coexisting species. The resulting sensor displays excellent repeatability and long-term stability; finally it was successfully applied to detect tryptophan in real samples with good recoveries, ranging from 99.0% to 103.0%. (C) 2012 Elsevier B.V. All rights reserved.
关键词：
geometric phase;metamaterial;photonic spin Hall effect
摘要：
The photonic spin Hall effect (SHE) in the reflection and refraction at an interface is very weak because of the weak spin-orbit interaction. Here, we report the observation of a giant photonic SHE in a dielectric-based metamaterial. The metamaterial is structured to create a coordinate-dependent, geometric Pancharatnam-Berry phase that results in an SHE with a spin-dependent splitting in momentum space. It is unlike the SHE that occurs in real space in the reflection and refraction at an interface,which results from the momentum-dependent gradient of the geometric Rytov-Vladimirskii-Berry phase. We theorize a unified description of the photonic SHE based on the two types of geometric phase gradient, and we experimentally measure the giant spin-dependent shift of the beam centroid produced by the metamaterial at a visible wavelength. Our results suggest that the structured metamaterial offers a potential method of manipulating spin-polarized photons and the orbital angular momentum of light and thus enables applications in spin-controlled nanophotonics.
关键词：
spin Hall effect of light;spin Hall shift;geometric phase;weak measurements
摘要：
The spin Hall effect (SHE) of light, as an analogue of the SHE in electronic systems, is a promising candidate for investigating the SHE in semiconductor spintronics/valleytronics, high-energy physics and condensed matter physics, owing to their similar topological nature in the spin-orbit interaction. The SHE of light exhibits unique potential for exploring the physical properties of nanostructures, such as determining the optical thickness, and the material properties of metallic and magnetic thin films and even atomically thin two-dimensional materials. More importantly, it opens a possible pathway for controlling the spin states of photons and developing next-generation photonic spin Hall devices as a fundamental constituent of the emerging spinoptics. In this review, based on the viewpoint of the geometric phase gradient, we give a detailed presentation of the recent advances in the SHE of light and its applications in precision metrology and future spin-based photonics.
期刊：
JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY,2010年10(8):4868-4874 ISSN：1533-4880
通讯作者：
Yuan, Yali
作者机构：
[Yuan, Yali; Deng, Jian] Univ S China, Sch Chem & Chem Engn, Hengyang 421001, Peoples R China.;[Ding, Jianqiang] Zhenhai Ctr Dis Control & Prevent, Ningbo 315200, Peoples R China.;[Xu, Jinsheng] Hengyang Normal Univ, Dept Chem & Mat Sci, Hengyang 421008, Peoples R China.;[Guo, Jianbo] Univ S China, Sch Publ Hlth, Hengyang 421001, Peoples R China.
通讯机构：
[Yuan, Yali] Univ S China, Sch Chem & Chem Engn, Hengyang 421001, Peoples R China.
会议主办单位：
(1) School of Chemistry and Chemical Engineering, University of South China, Hengyang 421001, China; (2) Zhenhai Center for Disease Control and Prevention, Ningbo 315200, China; (3) Department of Chemistry and Materials Science, Hengyang Normal University, Hengyang 421008, China; (4) School of Public Health, University of South China, Hengyang 421001, China
摘要：
A highly sensitive and mercury-free method for determination of bisphenol A (BPA) was established using a glassy carbon electrode that was modified with carboxylated multi-walled carbon nanotubes. A sensitive oxidation peak is found at 550 mV in linear sweep voltammograms at pH 7. Based on this finding, trace levels of bisphenol A can be determined over a concentration range that is linear from 10 nM to 104 nM, the correlation coefficient being 0.9983, and the detection limit (S/N = 3) being 5.0 nM. The method was successfully applied to the determination of BPA in food package. A new electrochemical method was developed for the determination of bisphenol A based on carboxylated multi-walled carbon nanotubes modified electrode.
期刊：
GREEN CHEMISTRY,2012年14(5):1268-1271 ISSN：1463-9262
通讯作者：
Wang, Deping
作者机构：
[Yu, Jiangxi; Li, Junhua; Zhang, Fuxing; Wang, Deping; Kuang, Daizhi] Hengyang Normal Univ, Dept Chem & Mat Sci, Hengyang 421008, Peoples R China.;[Yu, Jiangxi; Li, Junhua; Zhang, Fuxing; Kuang, Daizhi] Hengyang Normal Univ, Coll Hunan Prov, Key Lab Funct Organometall Mat, Hengyang 421008, Peoples R China.
通讯机构：
[Wang, Deping] Hengyang Normal Univ, Dept Chem & Mat Sci, Hengyang 421008, Peoples R China.
摘要：
6,7-Dihydroquinolin-8(5H)-one oxime (L3) was found to serve as a superior ligand for the CuI-catalyzed N-arylation of imidazoles with aryl iodides, bromides, and electron-deficient chlorides in water. Moreover, the CuI/L3 catalyst system enabled the coupling reactions to take place smoothly with high yields under a low catalyst loading (0.1-1 mol% CuI and 0.2-2 mol% L3).
关键词：
Electronic band structure;Graphene;Doping;Density-functional theory
摘要：
A pathway to open the band gap of graphene by p-n codoping is presented according to the first principles study. Two models are used: Lithium adsorbed on Boron-doped graphene (BC) and Boron-Nitrogen (B/N) codoping into graphene. The stability of Lithium adsorbed on BC is firstly analyzed, showing that the hollow site is the most stable configuration, and there is no energy barrier from some metastable configurations to a stable one. After the p-n codoping, the electronic structures of graphene are modulated to open a band gap with width from 0.0 eV to 0.49 eV, depending on the codoping configurations. The intrinsic physical mechanism responsible for the gap opening is the combination of the Boron atom acting as hole doping and Nitrogen (Lithium) as electron doping. (C) 2011 Elsevier B.V. All rights reserved.
摘要：
Assembly reactions of 5-(isonicotinamido) isophthalic acid (H(2)INAIP) with Ln(2)O(3) or Ln(NO3)(3)center dot 6H(2)O together with NaOH in the presence of AgNO3 result in formation of two series of new 4d-4f heterometallic coordination polymers {[LnAg(INAIP)(2)]center dot 3H(2)O}(n)[Ln = Nd (1), Sm (2), Eu (3), Gd (4), Tb (5)] and {[LnAg(INAIP)(2)(H2O)]center dot xH(2)O}(n) [Ln = La (6), Pr (7), Nd (8), x = 0; Dy (9), Er (10), x = 1]. The results of single-crystal X-ray diffraction analysis indicate that 1-5 are isomorphous and have 2-fold interpenetrated 3D structure with 3-nodal net Point (Schlafli) symbol for net: (4.6(2))(4)(4(4).6(6).8(15).10(3)), while 6-10 are isostructural with similar non-interpenetrating 3D frameworks containing 2D lanthanide-carboxylate bilayers. The results indicate that the reaction conditions have great influence on the structure of the resulting complexes in this system. Furthermore, 3 and 5 show intense red and green fluorescent emissions, respectively, and the emission bands of Nd(III) were observed in the near IR region for 1. The magnetic properties of 1-5, 9 and 10 were investigated.
摘要：
Assembly reactions of pyridyl-and carboxylate-containing ligand 5-(isonicotinamido)isophthalic acid (H(2)INAIP) with corresponding metal salts result in formation of six new coordination polymers, namely {[Mn(INAIP)(DMF)]center dot 0.5DMF}(n) (1), {[Mn(INAIP)(H2O)(2)]center dot 4H(2)O}(n) (2), {[Co(INAIP)(H2O)]center dot 2H(2)O}(n) (3), {[Co(INAIP)(bpy)(0.5)]}(n) (4), {[Co(INAIP)(Him)(H2O)]center dot H2O}(n) (5), and {[Cu(INAIP)(Him)(H2O)]center dot H2O}(n) (6) (DMF N,N-dimethylformamide, bpy - 4,4'-bipyridine, Him imidazole). The results of single-crystal X-ray diffraction analysis indicate that 1 is a two-fold interpenetrated three-dimensional (3D) framework with sra topology, complexes 2, 5 and 6 have two-dimensional (2D) network structure with (6,3) topology, while 3 and 4 have infinite 2D bi-layer structure with different topologies. Complex 3 exhibits a 4-connected network with the Schlafli symbol (4(3).6(3)), and 4 displays a (4,5)-connected net with Schlafli symbol (4(3).5(2).6)(4(3).5(5).6(2)). The magnetic and adsorption properties of the complexes were investigated.
通讯机构：
[Wang, Xin-Wen] Hengyang Normal Univ, Dept Phys & Elect Informat Sci, Hengyang 421008, Peoples R China.
摘要：
The cross-Kerr nonlinearity (XKNL) effect can induce efficient photon interactions in principle with which photonic multiqubit gates can be performed using far fewer physical resources than linear optical schemes. Unfortunately, it is extremely challenging to generate giant cross-Kerr nonlinearities. In recent years much effort has been made to perform multiqubit gates via weak XKNLs. However, the required nonlinearity strengths are still difficult to achieve in an experiment. We here propose an XKNL-based scheme for realizing a two-photon polarization-parity gate, a universal two-qubit gate, in which the required strength of the nonlinearity could be orders of magnitude weaker than those required for previous schemes. The scheme utilizes a ring cavity fed by a coherent state as a quantum information bus which interacts with a path mode of the two polarized photons (qubits). The XKNL effect makes the bus pick up a phase shift dependent on the photon number of the path mode. Even when the potential phase shifts are very small they can be effectively measured using photon-number resolving detectors, which accounts for the fact that our scheme can work in the regime of tiny XKNL. The measurement outcome reveals the parity (even parity or odd parity) of the two polarization qubits.
