The Study of Electrochemical Behavior of Dopamine at Nano—gold Modified Carbon Fiber Electrode

In the field of detection of neurotransmitters carbon fiber ultramicroelectrode has attracted extensive attention due to its specific features such as particular steady state diffusion profiles and very small IR drop values as well as the ability to work in living organism1. Carbon fiber microelectrodes have been used successfully to detect dopamine in vivo2,3. The electrochemical behavior of dopamine at nano-gold modified carbon fiber electrode was studied in this paper. The electrochemica…     

Ion Recognition and Analytical Application of a Fibroin Modified Electrode

A novel fibroin modified electrode with ion recognition was reported. The membrane with isoelectric point of pH 4.5, was modified on graphite and carbon fiber electrodes. The pH-responsive ion recognition of the modified electrode was investigated by use of some neurocompounds. The fibroin carbon fiber electrode has been used for in-vivo determination.     

Carbon Fiber-gold/mercury Dual-electrode Detection for Capillary Electrophoresis

Capillary electrophoresis (CE) has become a useful and powerful separation technique and has many applications. Electrochemical detection (ED) has been shown to be one of the most sensitive detection techniques available for use in CE. Dual-electrode detection can expand the applicability of CE-ED1-5, the materials such as gold/mercury1,3, carbon fiber2, Pt4 and Au3,5 have been used for the two electrodes in dual-electrodes. As is well known, the electrochemical response of different c…     

Polymeric bilayer modified microelectrodes for in-vivo determination of neurotransmitter dopamine

A composite polymer carbon fiber electrode modified with Nafion and cellulose acetate is described.The modified electrode discriminates against both anionic reactants and big molecular organic compounds.The bilayer configuration is prepared in two steps.First,the carbon fiber electrode is coated with Nafion,then followed by air evaporation of the solvent,the electrode is dipped in a cellulose acetate solution and hydrolyzed for a selected time.The permeability of the film is explored by use of rotating disk electrode measurements.Parameters affecting the film electrochemistry are investigated.The resulting electrodes show high selectivity and stability in body fluids.For in-vivo voltammetry,the composite polymer modified electrode has been used for detection of the oxidative current of neurotransmitter dopamine in rat brain,while it inhabits the oxidation of anionic neurotransmitter metabolites and some electroactive compounds.     

Photostability Study of Nanoporous TiO2 Film Electrodes in Basic Solutions

The nanoporous TiO2 film electrodes have been prepared by a sol-gel deposition process The photostability of the electrodes in basic solutions has been studied. The results show that the photostability of the electrodes decreases rapidly in strong basic solutions with or without methanol. The reaction of holes to O^2- produces active O^2- atoms and the products O^2- atomsoxidize Ti^3 to Ti^4 on TiO2 film surface and subsurface. This results in the TiO2 film electrodes unstable in basic solutions both without methanol and with too low concentration.     

Electrochemical studies of tetraphenylporphyrin and vanadyl porphyrin

The electrochemical reductions and oxidations of tetraphenylporphyrin (TPP) and vanadyl por-phyrin (TPP-VO) were investigated in dimethylformamide at platinum,glass carbon and microdisk electrodes.A new eleetrode reaction mechanism of TPP and TPP-VO is proposed.The kinetic parameters have also been determined.In addition,the theory of molecular hybrid orbitals is used to explain the reduction and oxidation regularity of the transition metal porphyrms     

Poly(ethylene terephthalate)/carbon black composite fibers prepared by electrospinning

Poly(ethylene terephthalate)(PET)/carbon black(CB) composite fibers with improved mechanical properties in tensile modulus and tensile strength are prepared by eletrospinning. Stable dispersions suitable for electrospinning are obtained by dispersing melt pre-compounded PET/CB composites in hexafluoroisopropanol. The fiber morphology and CB dispersion are investigated by FESEM and TEM. The addition of CB has no obvious effect on fiber diameter, and the average fiber diameters for all the samples are around 2-3 μm. CB in the fibers is in the form of submicron-sized clusters. The thermal properties of the PET/CB composite fibers are evaluated by DSC, showing almost unchanged melting temperature and crystallinity. Uniaxial tensile tests are used to measure the mechanical properties of the PET/CB composite fiber mats. The fiber mats containing 1 wt%-8.5 wt% CB have significantly improved tensile modulus compared to neat PET fiber mat, showing reinforcing effect of CB. The electrical conductivity of the fiber mats has also been tested.     

Enzymatic surface modification of Kevlar fibers

Horseradish peroxidase catalyzed grafting of acrylamide (AM) onto Kevlar fibers has been studied. The modified fiber has been characterized with scanning electron microscopy (SEM), elemental analysis and the grafting yield. From the SEM micrographs, the surface of the grafted Kevlar fiber is rougher than that of the untreated fiber, and the elemental analysis indicated that the nitrogen content of the treated fibers is higher than that of the untreated fiber. All the results suggested that AM must have been grafted onto the Kevlar surface through HRP-mediated radical initiated grafting reaction. The probably mechanism of HRP catalyzed grafting of AM onto Kevlar surface is proposed.     

Breakthrough in carbon nanotube growth: unique alloy nanocatalysts lead to the chirality specified tubes

<正>Since Dr.Iijima reported his observation of tubular carbon under transmission electron microscopy(TEM)in 1991,carbon nanotubes(CNTs)have attracted intensive attention.A single-walled CNT(SWNT)is a seamless cylinder formed by rolling a piece of graphene,the honeycombstructured sp2 carbon.This unique structure endows SWNTs     

LiFePO4 doped with magnesium prepared by hydrothermal reaction in glucose solution

Lithium iron phosphate （LiFePO4） doped with magnesium was hydrothermally synthesized from commercial LiOH, FeSO4, H3PO4 and MgSO4 with glucose as carbon precursor in aqueous solution. The samples were characterized by X-ray powder diffraction, scanning electron microscopy and constant charge-discharge cycling. The results show that the synthesized powders have been in situ coated with carbon precursor produced from caramel reaction of glucose. At ambient temperature （28±2℃）, the electrochemical performances of LiFePO4 prepared exhibit the high discharge capacity of 135 mAh g^-1 at 5C and good capacity retention of 98% over 90 cycles. The excellent electrochemical performances should be correlated with the intimate contact between carbon and LiFePO4 primary and secondary particles, resulting from the in situ formation of carbon precursor/carbon, leading to the increase in conductivity of LiFePO4.     

Determination of Water Diffusion Coefficients and Dynamics in Adhesive/Carbon Fiber Reinforced Epoxy Resin Composite Joints

To determinate the water diffusion coefficients and dynamics in adhesive/carbon fiber reinforced epoxy resin composite joints,energy dispersive X-ray spectroscopy analysis(EDX)is used to establish the content change of oxygen in the adhesive in adhesive/carbon fiber reinforced epoxy resin composite joints.As water is made up of oxygen and hydrogen,the water diffusion coefficients and dynamics in adhesive/carbon fiber reinforced epoxy resin composite joints can be obtained from the change in the content of oxygen in the adhesive during humidity aging,via EDX analysis.The authors have calculated the water diffusion coefficients and dynamics in the adhesive/carbon fiber reinforced epoxy resin composite joints with the aid of both energy dispersive X-ray spectroscopy and elemental analysis.The determined results with EDX analysis are almost the same as those determined with elemental analysis and the results also show that the durability of the adhesive/carbon fiber reinforced epoxy resin composite joints subjected to silane coupling agent treatment is better than those subjected to sand paper burnishing treatment and chemical oxidation treatment.     

Electrochemical behavior of hemoglobin in neutral surfactants with different poly(ethylene oxide) unit lengths adsorbed on an electrode

The direct electron transfer and adsorption behavior of hemoglobin(Hb) in a series of surfactants with different poly(ethylene oxide)(PEO) unit lengths on a glassy carbon electrode have been studied.With a surfactant of appropriate PEO unit length,the surfactant film-modified electrode exhibited a more stable adsorption state with a larger surface coverage of Hb and a more positive formal potential,which can be attributed to the effect of hydrogen bonding between proteins and surfactants.The electrochemical behavior of surfactants with different PEO unit lengths is discussed in detail.Moreover,UV-visible spectroscopy demonstrated that the structure of Hb was not destroyed in the surfactant films.The electrocatalytic activity of hydrogen peroxide on three neutral surfactant-modified electrodes has also been investigated.     

INVESTIGATIONS ON THE CRYSTALLINE MORPHOLOGIES OF POLYPHENYLENE SULFIDE AND THE CARBON FIBRE SURFACE EFFECTS

By the use of polarized light microscopy, chemical etching and scanning electron micro-scopy, the erystalline morphologies of polyphenylene sulfide (PPS) have been studied. Thecrystalline morphologies of PPS are greatly affected by the curing conditions. Either gra-phite fibres and carbon fibres, or glass fibres, possess the ability of inducing the transcry-stallization of PPS at different degrees. The corrosive resistance of PPS resin is not onlyrelated with its chemical structure, but also with its aggregation structure, and furthermorewith the "interface effects" of carbon fibres in the composites.     

ELECTRODEPOSITION OF POLYMERS ON CARBON FIBERS

Styrene-co-maleic anhydride, vinyl acetate-co-maleic anhydride, methyl methacrylate-co-maleic anhydride copolymers were deposited on the surface of carbon fibers by an electrodcposition technique. The anion-free radical mechanism of this process and the physical adhesion to the surface were preliminarily confirmed. The adhesion at fiber-resin matrix interface in carbon fiber reinforced plastics was improved by the electrodeposited polymer interlayer and the shear failure occurred mainly in the matrix. Interlaminar shear strength of the unidirectional carbon fiber reinforced epoxy composite is increased from about 600 kg/cm~2 to 1000 kg/cm~2 by electrodeposition of polymers and the strength loss of the composite which has been immersed in boiling water for 100 hrs is decreased.     

STUDY ON THE MICROSTRUCTURE AND PROPERTY OF PET FIBER BY LASER RAMAN MICROSCOPE

In this paper, the microstructure change of one step-draw PET fiber has been studied byvarious methods, such as, Laser Raman Microscope, Wide-angle X-ray, Density-gradient andPolarizing Microscope. The computer has been used to resolve overlapped bands in the Ramanspectra. Then the band changes have been correlated with trans, gauche and stressed trans-conformations indicated by a conformational index. Based on these indices, the relationshipbetween the conformation change of glycol units in the fiber structure and the macromechanicalproperties of fiber is expounded.     

A new insight into the stability of nanofiber electrodes used in proton exchange membrane fuel cells

The nanofiber electrodes have been considered as promising candidates for commercial proton exchange membrane fuel cells due to their high catalyst utilization and enhanced mass transport efficiency. However, for the first time our research determined that the nanofiber electrodes were restricted by the poor chemical stability of the polymer carriers. To gain further insight into the durability of nanofiber electrodes, both cyclic voltammetry aging tests and Fenton's tests were conducted. Similar to previous reports, our research demonstrated that nanofiber electrodes showed remarkable stability in the cyclic voltammetry aging process. However, Fenton's tests indicated that nanofibers in the electrodes would decompose easily while being attacked by reactive oxygen species such as HO· or HOO·, which greatly limits their practicability and reliability. The different performances under the two tests also demonstrated that the cyclic voltammetry aging protocols, which have been applied extensively, cannot well mirror the real operating conditions of fuel cells.     

原位化学沉积法制备碳/聚苯胺复合材料作为超级电容器材料的研究

Polyaniline （PA） film was chemically deposited onto the surface of activated carbon （AC） uniformly. Chemical deposition was carried out in 0.1 mol/L aniline plus 0.5 mol/L H2SO4 solution adopting V2O5·nH2O coated on the surface of activated carbon as oxidant. The surface morphologies and structures of the composite materials were characterized by scanning electron microscopy and FT-IR spectra. The electrochemical properties of the composite material electrodes were studied by cyclic voltammetry and constant current charge/discharge tests in 1 molFL H2SO4 solutions. The specific capacitance of composite materials was exhibited as high as 237.5 F/g at a current density of 1.0 A/g compared with a value of 120 F/g for pure carbon electrode. Good power characteristic and good stability of composite electrodes were also demonstrated.     

Determination of isoniazid and hydrazine by capillary electrophoresis with amperometric detection at a Pt-particle modified carbon fiber microelectrode

Capillary electrpphoresis (CE)/electrochemical detection (EC) for the simultane-ous determination of hydrazine and isoniazid has been developed.The electrochemical method uses a novel modified electrode dispersed with ultrafine platinum particles on the surface of a 30μm carbon fiber microelectrode.The unique characteristic of the Pt-particles modified carbon fiber microelectrode is its excellent stability.The current measurement for hydrazine is more sensitive than that of isoniazid.Selective determination of trace amount of free hydrazine in isoniazid and its formulation can be achieved at applied potential of 0.5V.     

氧化钴和氮掺杂碳纳米管纳米复合物的催化与容量性质(英文)

The nanocomposites based on cobalt oxide and nitrogen-doped carbon nanofibers (N-CNFs) with cobalt oxide contents of 10–90 wt% were examined as catalysts in the CO oxidation and supercapacity electrodes. Depending on Со3О4 content, such nanocomposites have different morphologies of cobalt oxide nanoparticles, distributions over the bulk, and ratios of Со3+/Co2+ cations. The 90%Со3О4-N-CNFs nanocomposite showed the best activity because of the increased concentration of defects in N-CNFs. The capacitance of electrodes containing 10%Со3О4-N-CNFs was 95 F/g, which is 1.7 times higher than electrodes made from N-CNFs.     

Phase Transformation Mechanism of Graphite-Turbostratic Graphite in the Course of Mechanical Grinding

IntroductionSome industrially- widely- used carbon materi-als,such as Pan- based carbon fiber,glassy car-bon,carbon black and carbon film,have a tur-bostratic graphitic structure[1— 4] . This structure isbased on the same hexagonal plane of the carbonatoms as graphitic crystalline. The difference be-tween atoms lies in the random translations and ro-tations which destroy the character of three dimen-sional ordering. Turbostratic graphite materials aremostly composed of non graphitic carbon. …