Showing papers by "Anhui Normal University published in 2010"

Synthesis of porous NiO nanocrystals with controllable surface area and their application as supercapacitor electrodes

Abstract: We report a facile way to grow various porous NiO nanostructures including nanoslices, nanoplates, and nanocolumns, which show a structure-dependence in their specific charge capacitances. The formation of controllable porosity is due to the dehydration and re-crystallization of β-Ni(OH)2 nanoplates synthesized by a hydrothermal process. Thermogravimetric analysis shows that the decomposition temperature of the β-Ni(OH)2 nanostructures is related to their morphology. In electrochemical tests, the porous NiO nanostructures show stable cycling performance with retention of specific capacitance over 1000 cycles. Interestingly, the formation of nanocolumns by the stacking of β-Ni(OH)2 nanoslices/plates favors the creation of small pores in the NiO nanocrystals obtained after annealing, and the surface area is over five times larger than that of NiO nanoslices and nanoplates. Consequently, the specific capacitance of the porous NiO nanocolumns (390 F/g) is significantly higher than that of the nanoslices (176 F/g) or nanoplates (285 F/g) at a discharge current of 5 A/g. This approach provides a clear illustration of the process-structure-property relationship in nanocrystal synthesis and potentially offers strategies to enhance the performance of supercapacitor electrodes.

Facile Subsequently Light-Induced Route to Highly Efficient and Stable Sunlight-Driven Ag−AgBr Plasmonic Photocatalyst

Abstract: In this paper, we successfully fabricate a stable and highly efficient direct sunlight plasmonic photocatalyst Ag−AgBr through a facile hydrothermal and subsequently sunlight-induced route. The diffuse reflectance spectra of Ag−AgBr indicate strong absorption in both UV and visible light region. The obtained photocatalyst shows excellent sunlight-driven photocatalytic performance. It can decompose organic dye within several minutes under direct sunlight irradiation and maintain a high level even though used five times. In addition, both the scanning electron microscopy images and X-ray photoelectron spectroscopy dates reveal the as-prepared photocatalyst to be very stable. Moreover, the mechanism suggests that the high photocatalytic activity and excellent stability result from the super sensitivity of AgBr to light, the surface plasmon resonance of Ag nanoparticles in the region of visible light, and the complexation between Ag+ and nitrogen atom. Thus, the facile preparation and super performance of Ag−...

Large-scale synthesis of flowerlike ZnO nanostructure by a simple chemical solution route and its gas-sensing property

Abstract: A large-scale flowerlike ZnO nanostructure is prepared using a very simple solution method at near room temperature. The flowerlike ZnO nanostructure is self-assembled by thin and uniform nanosheets with a thickness of approximately 18 nm. X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used to characterize the structure and morphology. The possible growth mechanism is carefully discussed based on the reaction process. The as-prepared ZnO nanoflowers exhibit a good response and reversibility to some organic gases, such as ethanol and n-butanol. The responses to 100 ppm ethanol and n-butanol are 25.4 and 24.1, respectively, at a working temperature of 320 °C. In addition, the sensors exhibit a good response to acetone, 2-propanol, and methanol. The relationship between the gas-sensing properties and the microstructure of the as-prepared ZnO nanoflowers is also investigated.

Preparation and recognition properties of bovine hemoglobin magnetic molecularly imprinted polymers.

Abstract: A simple method for the preparation of core−shell micro/nanostructured magnetic molecularly imprinted polymers (MIPs) for protein recognition is described. Magnetic MIPs were synthesized by copolymering γ-aminopropyltrimethoxysilane and tetraethyl orthosilicate at the surface of Fe3O4 nanospheres, which were directly covalently bound with template molecule, bovine hemoglobin (BHb), through imine bond. Transmission electron microscopy and scanning electron microscopy images showed that the Fe3O4 nanospheres with diameter about 50−150 nm were coated with the MIPs layer with average thickness about 10 nm, which enabled the magnetic MIPs to have a sensitive and fast magnetic response. The proximity between the thickness of MIPs layer and the spatial size of BHb indicated that the imprinted sites almost situated at the surface of magnetic MIPs, leading a rapid adsorption saturation within 1 h. And the adsorption amounts of magnetic MIPs toward BHb were estimated to be 10.52 mg/g at pH 6.5, which was 4.6 times ...

Positive Feedback between Mycorrhizal Fungi and Plants Influences Plant Invasion Success and Resistance to Invasion

Abstract: Negative or positive feedback between arbuscular mycorrhizal fungi (AMF) and host plants can contribute to plant species interactions, but how this feedback affects plant invasion or resistance to invasion is not well known. Here we tested how alterations in AMF community induced by an invasive plant species generate feedback to the invasive plant itself and affect subsequent interactions between the invasive species and its native neighbors. We first examined the effects of the invasive forb Solidago canadensis L. on AMF communities comprising five different AMF species. We then examined the effects of the altered AMF community on mutualisms formed with the native legume forb species Kummerowia striata (Thunb.) Schindl. and on the interaction between the invasive and native plants. The host preferences of the five AMF were also assessed to test whether the AMF form preferred mutualistic relations with the invasive and/or the native species. We found that S. canadensis altered AMF spore composition by increasing one AMF species (Glomus geosporum) while reducing Glomus mosseae, which is the dominant species in the field. The host preference test showed that S. canadensis had promoted the abundance of AMF species (G. geosporum) that most promoted its own growth. As a consequence, the altered AMF community enhanced the competitiveness of invasive S. canadensis at the expense of K. striata. Our results demonstrate that the invasive S. canadensis alters soil AMF community composition because of fungal-host preference. This change in the composition of the AMF community generates positive feedback to the invasive S. canadensis itself and decreases AM associations with native K. striata, thereby making the native K. striata less dominant.

A facile solution chemical route to self-assembly of CuS ball-flowers and their application as an efficient photocatalyst

Abstract: Ball-flower shaped CuS structures have been synthesized by using mixed copper chloride and thiourea in a simple hydrothermal process employing poly(vinylpyrrolidone) (PVP) as the surfactant. The morphological investigations by field emission scanning electron microscope (FE-SEM) reveal that the ball-flower shaped nanostructures are monodispersed in large quantities. The ball-flower shaped morphologies are strongly dependent on the different ratios of copper chloride to thiourea, the reaction temperature and reaction time. The possible growth mechanism of the formation of ball-flower shaped CuS products is discussed in detail. In addition, the photocatalytic activity of ball-flower shaped CuS architectures has been tested by the degradation of rhodamine B (RhB) under UV light irradiation, showing that the as-prepared ball-flower shaped CuS structures exhibit high photocatalytic activity for the degradation of RhB.

Co9S8 nanotubes synthesized on the basis of nanoscale Kirkendall effect and their magnetic and electrochemical properties

Abstract: Polycrystalline Co9S8 nanotubes were successfully fabricated by using Co(CO3)0.35Cl0.20(OH)1.10 nanorod bunches as sacrificial hard templates through a hydrothermal route. The samples were characterized by means of XRD, XPS, SEM and TEM. The Co9S8 nanotubes were formed due to the nanoscale Kirkendall effect, which can be explained by the difference in diffusion rates between the cobalt source and the sulfur ion. Magnetic measurements indicate that the Co9S8 nanotubes show a paramagnetic property instead of a ferromagnetic property, which can be attributed to the tiny sizes of the component nanoparticles. The electrochemical properties of the Co9S8 nanotubes demonstrate that they deliver a large discharge capacity, which might find possible applications as an electrode material in lithium batteries.

Ag-Coated Fe3O4@SiO2 Three-Ply Composite Microspheres: Synthesis, Characterization, and Application in Detecting Melamine with Their Surface-Enhanced Raman Scattering

Abstract: Ag nanoparticles with average sizes of 20 nm were well-dispersed on the surfaces of Fe3O4@SiO2 composite microspheres through a simple wet-chemical method employing the Ag-mirror reaction. The as-synthesized Ag-coated Fe3O4@SiO2 three-ply composite microspheres are monodisperse and bifunctional, with ferromagnetic and surface-enhanced Raman scattering (SERS) properties. The products were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray analysis (EDX). SERS signals of typical analytes such as rhodamine 6G (Rh 6G) were observed on Ag nanoparticles from the Ag-coated Fe3O4@SiO2 microspheres, even though the concentration of the analyte was as low as 1 × 10−15 M (Rh 6G). The Ag-coated Fe3O4@SiO2 microspheres were applied to detecting melamine, and strong SERS signals were obtained with melamine concentration of 1 × 10−6 M. This work may provide a potential and unique technique to detect melamine.

Enzyme-free amperometric sensing of glucose using Cu-CuO nanowire composites

Abstract: A non-enzymatic amperometric glucose is reported that is based on an glassy carbon electrode modified with a Cu-CuO nanowire (NW) composite. The morphology and the composition of the nanowire were characterized by scanning electron microscopy and X-ray diffraction, respectively. The modified electrode efficiently catalyzes the oxidation of glucose at less-positive potential (0.30 V) in 0.10 M NaOH solution in the absence of any enzymes or redox mediators. The sensor was successfully used for the amperometric sensing of glucose. Linear response was obtained over the concentration range from 0.1 to 12 mM. The common interfering agents ascorbic acid and uric acid do not interfere with the determination of glucose. The modified electrode features high sensitivity, low working potential, excellent stability, and fast amperometric sensing of glucose. Thus it is promising for the future development of non-enzymatic glucose sensors.

The comprehensive evaluation of China’s urbanization and effects on resources and environment

Abstract: This paper constructs a comprehensive evaluation index system for the urbanization level in China in terms of four aspects of urbanization connotation: population, economy, society, and land. A comprehensive measurement is carried out for the Chinese urbanization between 1981 and 2006 based on the Entropy method. The results show that the comprehensive level of urbanization in China has a continuous increase with the major features of economic growth and a rapid evolution of the geographical landscape, followed by population urbanization and then social urbanization of health care standard; the distinguished evolutional characteristics can also be found in each of the subsystems. The integrated evolution of urbanization has a profound effect on the resources, energy and the environment, making the land resources and energy security situation under severe pressure. The environment pressure is also increased further.

One-pot synthesis and strong near-infrared upconversion luminescence of poly(acrylic acid)-functionalized YF3:Yb3+/Er3+ nanocrystals

Abstract: This paper describes the synthesis of new upconverting luminescent nanoparticles that consist of YF3:Yb3+/Er3+ functionalized with poly(acrylic acid) (PAA). Unlike the upconverting nanocrystals previously reported in the literature that emit visible (blue-green-red) upconversion fluorescence, these as-prepared nanoparticles emit strong near-infrared (NIR, 831 nm) upconversion luminescence under 980 nm excitation. Scanning electron microscopy, transmission electron microscopy, and powder X-ray diffraction were used to characterize the size and composition of the luminescent nanocrystals. Their average diameter was about 50 nm. The presence of the PAA coating was confirmed by infrared spectroscopy. The particles are highly dispersible in aqueous solution due to the presence of carboxylate groups in the PAA coating. By carrying out the synthesis in the absence of PAA, YF3:Yb3+/Er3+ nanorice materials were obtained. These nanorice particles are larger (∼700 nm in length) than the PAA-functionalized nanoparticles and show strong typical visible red (668 nm), rather than NIR (831 nm), upconversion fluorescence. The new PAA-coated luminescent nanoparticles have the pottential be used in a variety of bioanalytical and medical assays involving luminescence detection and fluorescence imaging, especially in vivo fluorescence imaging, due to the deep penetration of NIR radiation.

Syntheses, Structures, and Photoluminescence of Five New Metal−Organic Frameworks Based on Flexible Tetrapyridines and Aromatic Polycarboxylate Acids

Abstract: Solvothermal reactions of tetrakis(4-pyridyloxymethylene)methane (TPOM) with deprotonated 1,4-benzenedicarboxylate (H2bdc) or 5-hydroxyisophthalic acid (5-OH-H2bdc) in the presence of nitrates of cadmium, zinc, and cobalt in H2O or H2O/DMF produced five new complexes, namely, {[Cd2(TPOM)(bdc)2]·(H2O)5(DMF)}n (1), {[Zn2(TPOM)(bdc)2]·(H2O)4}n (2), {[Zn2(TPOM)(bdc)2]·(H2O)}n (3), {[Co2(TPOM)(5-OH-bdc)2(H2O)2]·(H2O)5}n (4), and {[Cd2(TPOM)(5-OH-bdc)2]·(H2O)2}n (5). These complexes were characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. Complex 1 reveals a 2-fold interpenetrating three-dimensional (3D) framework with pcu topology constructed from binuclear Cd clusters and TPOM ligands. In addition, the experiment of single-crystal-to-single-crystal (SC-SC) structural transformations upon guest exchange was tested. Zn complexes 2 and 3 possess different 3D frameworks and are prepared from TPOM and H2bdc under different reaction conditions. In complexes 4 and 5, TPOM and ...

Synthesis and Functionalization of Asymmetrical Benzo-Fused BODIPY Dyes

Abstract: A series of asymmetrical benzo-fused BODIPY dyes were synthesized from the Sonogashira coupling and nucleophilic substitution reactions on the 3-halogenated benzo-fused BODIPY, generated from readily available 3-halogeno-1-formylisoindoles in a two-step synthetic procedure. This novel BODIPY platform provides an easy path for the linking of BODIPY fluorophore to various desired functionalities as demonstrated in this work. Most of the resulting BODIPY dyes show long-wavelength absorption and fluorescence emission, with good fluorescence quantum yields and long fluorescence lifetimes.

Honeycomb-like Ni@C composite nanostructures: synthesis, properties and applications in the detection of glucose and the removal of heavy-metal ions

Abstract: Honeycomb-like Ni@C composite nanostructures have been successfully prepared via a simple two-step solution route. Homogeneous Ni nanospheres with an average diameter of ∼100 nm were first obtained via a DMF–water mixed solvothermal route; then honeycomb-like Ni@C composite nanostructures were prepared through the hydrothermal carbonization of glucose solutions with suitable amounts of Ni nanospheres. The as-obtained products were characterized by XRD, SEM, TEM, ED, EDS and Raman spectroscopy. It was found that the as-obtained honeycomb-like Ni@C composite nanostructures showed good electrochemical properties and could be used as an electrochemical sensor for the detection of glucose molecules. Furthermore, the honeycomb-like Ni@C composite nanostructures presented good capacities for selective adsorption of Pb2+, Cd2+ and Cu2+ ions in water, and could be easily separated from water and reused.

Enhancement in analytical hydrazine based on gold nanoparticles deposited on ZnO-MWCNTs films

Abstract: A good route (electrodeposition) for the fabrication of gold nanoparticles (nano-Au) attached on ZnO-MWCNTs films modified glassy carbon electrodes (GCE) was proposed. ZnO-MWCNTs films are favored for functioning as the biomimic membrane to immobilize nano-Au. The morphological characterization of nano-Au/ZnO-MWCNTs was examined by scanning electron microscopy (SEM). The performances of the nano-Au/ZnO-MWCNTs/GCE were characterized with cyclic voltammetry (CV), Nyquist plot (EIS) and typical amperometric response ( i – t ). The potential utility of electrodes constructed was demonstrated by applying them to the analytical determination of hydrazine concentration. The catalytic oxidation of hydrazine has a better result on the nano-Au/ZnO-MWCNTs/GCE because of the synergistic effect of nano-Au and ZnO-MWCNTs films. An optimized limit of detection of 0.15 μM was obtained at a signal to noise ratio of 3 and with a fast response time (within 3 s). Additionally, the nano-Au/ZnO-MWCNTs/GCE exhibited a wide linear range from 0.5 to 1800 μM and higher sensitivity. The ease of fabrication and high stability of the modified electrode are the promising features of the proposed sensor.

The complete mitochondrial genome of the yellow coaster, Acraea issoria (Lepidoptera: Nymphalidae: Heliconiinae: Acraeini): sequence, gene organization and a unique tRNA translocation event

Abstract: In this paper, the complete mitochondrial genome of Acraea issoria (Lepidoptera: Nymphalidae: Heliconiinae: Acraeini) is reported; a circular molecule of 15,245 bp in size. For A. issoria, genes are arranged in the same order and orientation as the complete sequenced mitochondrial genomes of the other lepidopteran species, except for the presence of an extra copy of tRNAIle(AUR)b in the control region. All protein-coding genes of A. issoria mitogenome start with a typical ATN codon and terminate in the common stop codon TAA, except that COI gene uses TTG as its initial codon and terminates in a single T residue. All tRNA genes possess the typical clover leaf secondary structure except for tRNASer(AGN), which has a simple loop with the absence of the DHU stem. The sequence, organization and other features including nucleotide composition and codon usage of this mitochondrial genome were also reported and compared with those of other sequenced lepidopterans mitochondrial genomes. There are some short microsatellite-like repeat regions (e.g., (TA)9, polyA and polyT) scattered in the control region, however, the conspicuous macro-repeats units commonly found in other insect species are absent.

Fabrication of CuO nanowalls on Cu substrate for a high performance enzyme-free glucose sensor

Abstract: Enzyme-free determination of glucose on an ordered CuO nanowall-based Cu substrate modified electrode is investigated. The structure and morphology of the CuO nanowalls were characterized by X-ray diffraction and scanning electron microscopy. The growth mechanism of the sample and the influence factor of the preparation process are discussed. The electrochemical study has shown that the CuO nanowalls exhibit a higher catalytic effect on the glucose than the CuO nanosphere without Cu substrate. This may be attributed to the special structure of the nanomaterials and the substrate of the electronic conductive Cu. The amperometric response showed that the CuO nanowall-modified glassy carbon electrode has a good response for glucose with a linear range of 0.05 μM to 10 μM with a sensitivity of 0.5563 μA μM−1 in pH 9.2 phosphate buffered solutions.

Long wavelength red fluorescent dyes from 3,5-diiodo-BODIPYs

Abstract: Amphiphilic and long wavelength red fluorescent dyes (4 and 7) were prepared from the Sonogashira coupling reactions of 3,5-diiodo-BODIPYs (1 and 6). One of these compounds, BODIPY 7, readily accumulated within human carcinoma HEp2 cells and was found to localize mainly within the endoplasmic reticulum (ER).

Syntheses, Structures, and Photochemical Properties of Six New Metal−Organic Frameworks Based on Aromatic Dicarboxylate Acids and V-Shaped Imidazole Ligands

Abstract: Solvothermal reactions of 4,4′-bis(imidazol-1-yl)diphenyl ether (BIDPE) with deprotonated 1,4-benzenedicarboxylic acid (H2bdc) in the presence of cadmium, zinc, cobalt, nickel, and manganese salts in H2O or H2O/DMF yielded six new complexes, namely, {[Co(BIDPE)(bdc)]2·(H2O)2(DMF)}n (1), {[Cd(BIDPE)(bdc)]4·(H2O)4(DMF)2}n (2), {[Zn(BIDPE)(bdc)]2·(H2O)2(DMF)}n (3), [Cd3(BIDPE)2(bdc)3]n (4), and [Ni(BIDPE)(bdc)(H2O)2]n (5), and [Mn(bdc)(BIDPE)(H2O)]n (6). These complexes were characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. Complexes 1 and 3 reveal a 2-fold interpenetrating three-dimensional (3D) framework constructed from BIDPE and H2bdc with Co and Zn salts; complexes 2 and 4 have the same staring materials but possess different 3D frameworks and are prepared from BIDPE and H2bdc under different reaction conditions. In complexes 5 and 6, BIDPE and H2bdc link Ni and Mn centers, respectively, to generate 2D → 2D interlocked sheets. The thermal stabilities and photoch...

Formation of single-crystal tellurium nanowires and nanotubes via hydrothermal recrystallization and their gas sensing properties at room temperature

Abstract: Single-crystal tellurium nanowires and nanotubes were selectively synthesized from tellurium powder through a hydrothermal recrystallization route. The nanowires have an average diameter of 40 nm and lengths of several micrometers, while the nanotubes have diameters of 100–200 nm and lengths of 1–2 µm. The morphologies of the as-obtained tellurium nanocrystals could be controlled by tuning the amount of hydrochloric acid added in the hydrazine hydrate solution. The experimental results demonstrated that tellurium powder could be dissolved and recrystallized in hydrazine hydrate solution under hydrothermal conditions. A dissolution–recrystallization mechanism was proposed for the conversion from tellurium powder to tellurium nanowires or nanotubes. The gas sensing properties of as-synthesized tellurium nanowires and nanotubes were investigated in detail, which revealed that the as-prepared tellurium nanowires and nanotubes, especially the tellurium nanowires, exhibited excellent sensitivity to NH3 at room temperature. The response times of the tellurium nanowires and nanotubes were 5 s and 18 s, and the recovery times were 720 s and 170 s, respectively, which are shorter than those reported for tellurium films. The as-prepared tellurium nanostructures could have potential applications in nanosensors.

The allelopathy and allelopathic mechanism of phenolic acids on toxic Microcystis aeruginosa.

Abstract: Cyanobacterial contamination of water has been a serious problem in recent years. Thus, the effective control of undesired cyanobacteria has become an urgent issue. We studied therefore the effects of ρ-coumaric acid and vanillic acid on toxic Microcystis aeruginosa and the allelopathic mechanisms. The results showed that the growth of toxic M. aeruginosa was significantly inhibited by ρ-coumaric acid and vanillic acid, with an EC50 of 0.26 ± 0.07 and 0.34 ± 0.05 mmol L−1, respectively. Our data also demonstrated that both ρ-coumaric acid and vanillic acid triggered the generation of superoxide anion radicals (O2 •−). The O2 •− might induce a lipid peroxidation which may change cell membrane penetrability, thereby leading to the eventual death of M. aeruginosa. Our current studies further provide evidence that some phenolic acids such as ρ-coumaric acid and vanillic acid may be a potential effective solution for aquatic management.

Addition of porous cuprous oxide to a Nafion film strongly improves the performance of a nonenzymatic glucose sensor

Abstract: The direct electrocatalytic oxidation of glucose in alkaline medium at an electrode modified with microcubes of porous cuprous oxide is reported. Compared to the glassy carbon electrode, a substantial increase in the efficiency of the electrocatalytic oxidation of glucose is observed starting at around +0.20 V (vs. Ag/AgCl). The pH dependence of the response was examined by cyclic voltammetry. This non-enzymatic amperometric sensor may be used for non-enzymatic detection of glucose with a high and reproducible sensitivity of 10.95 μA per mM at a potential of +0.40 V, with response times of <3 s, a linear range from 2.0 to 350 μM, and a detection limit of 1.3 μM. The porous microcubes are conveniently prepared, and display high sensitivity and repeatability.

Existence results for impulsive neutral stochastic functional integro-differential equations with infinite delays

Abstract: In this paper, we prove the existence of mild solutions for a class of impulsive neutral stochastic functional integro-differential equations with infinite delays in an abstract space by means of the Krasnoselskii-Schaefer type fixed point theorem.

Hierarchical ZnO micro/nanoarchitectures: hydrothermal preparation, characterization and application in the detection of hydrazine

Abstract: In the present work, we report the successful preparation of hierarchical ZnO micro/nanoarchitectures in one step by a simple hydrothermal route, using Zn(CH3COO)2·2H2O, hexamethylenetetramine (HMT) and NH3·H2O (5%) as the starting materials. The product was characterized by means of powder X-ray diffraction (XRD), energy dispersive X-ray spectrometry (EDS), transmission electron microscopy (TEM) and field emission scanning electron microscopy (SEM). The experiments showed that the morphology of ZnO could be controlled by the volume of NH3·H2O (5%). Using the hierarchical ZnO micro/nanoarchitecture, a simple amperometric sensor for the detection of hydrazine was fabricated. Cyclic voltammetry (CV) revealed that the hierarchical ZnO micro/nanoarchitecture exhibited a higher catalytic effect on hydrazine than normal, flower-like ZnO microstructures. The amperometric sensor was used in the detection of hydrazine with a detection limit of 0.25 μM over a wide linear detection range up to 200 μM, and with a high sensitivity of −15.86 μA mM−1, which is better than for other reported amperometric hydrazine sensors.