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排序方式: 共有206条查询结果,搜索用时 15 毫秒
71.
Abdollah Salimi Roaya Zand‐Karimi Abdollah Noorbakhash Saied Soltanian 《Electroanalysis》2010,22(20):2434-2442
For the first time silicon nitride (Si3N4) nanoparticles was used for preparation electrochemical biosensor. GOx immobilized on the Si3N4 nanoparticles exhibits facile and direct electrochemistry. The surface coverage and heterogeneous electron transfer rate constant (ks) of immobilized GOx were 6.3×10?13 mol cm?2 and 47.4±0.3 s?1. The sensitivity, linear concentration range and detection limit of the biosensor for glucose detection were 38.57 µA mM?1 cm?2, 25 µM to 8 mM and 6.5 µM, respectively. This biosensor also exhibits good stability, reproducibility and long life time. These indicate Si3N4 nanoparticles is good candidate material for construction of third generation biosensor and bioelectronics devices. 相似文献
72.
In this research a novel osmium complex was used as electrocatalyst for electroreduction of oxygen and H2O2 in physiological pH solutions. Electroless deposition at a short period of time (60 s), was used for strong and irreversible adsorption of 1,4,8,12‐tetraazacyclotetradecane osmium(III) chloride (Os(III)LCl2) ClO4 onto single‐walled carbon nanotubes (SWCNTs) modified GC electrode. The modified electrode shows a pair of well defined and reversible redox couple, Os(IV)/Os(III) at wide pH range (1–8). The glucose biosensor was fabricated by covering a thin film of glucose oxidase onto CNTs/Os‐complex modified electrode. The biosensor can be used successfully for selective detection of glucose based on the decreasing of cathodic peak current of oxygen. The fabricated biosensor shows high sensitivity, 826.3 nA μM?1cm?2, low detection limit, 56 nM, fast response time <3 s and wide calibration range 1.0 μM–1.0 mM. The biosensor has been successfully applied to determination of glucose in human plasma. Because of relative low applied potential, the interference from electroactive existing species was minimized, which improved the selectivity of the biosensor. The apparent Michaelis‐Menten constant of GOx on the nanocomposite, 0.91 mM, exhibits excellent bioelectrocatalytic activity of immobilized enzyme toward glucose oxidation. Excellent electrochemical reversibility, high stability, technically simple and possibility of preparation at short period of time are of great advantages of this glucose biosensor. 相似文献
73.
Abdollah Salimi Mohadeseh Izadi Rahman Hallaj Saied Soltanian Hassan Hadadzadeh 《Journal of Solid State Electrochemistry》2009,13(3):485-496
A simple procedure was developed to prepare a glassy carbon electrode modified with carbon nanotubes and Ruthenium (III) complexes.
First, 25 μl of dimethyl sulfoxide–carbon nanotubes solutions (0.4 mg/ml) was cast on the surface of the glassy carbon electrode
and dried in air to form a carbon nanotube film at the electrode surface. Then, the glassy carbon/carbon nanotube-modified
electrode was immersed into a Ruthenium (III) complex solution (direct deposition) for a short period of time (10–20 s for
multiwalled carbon nanotubes and 20–40 s for single-walled carbon nanotubes). The cyclic voltammograms of the modified electrode
in aqueous solution shows a pair of well-defined, stable, and nearly reversible redox couple, Ru(III)/Ru(II), with surface-confined
characteristics. The attractive mechanical and electrical characteristics of carbon nanostructures and unique properties and
reactivity of Ru complexes are combined. The transfer coefficient (α), heterogeneous electron transfer rate constants (k
s), and surface concentrations (Γ) for the glassy carbon/single-walled carbon nanotubes/Ru(III) complex-, glassy carbon/multiwalled carbon nanotubes/Ru(III)
complex-, and glassy carbon/Ru(III) complex-modified electrodes were calculated using the cyclic voltammetry technique. The
modified electrodes showed excellent catalytic activity, fast response time, and high sensitivity toward the reduction of
nicotinamide adenine dinucleotide in phosphate buffer solutions at a pH range of 4–8. The catalytic cathodic current depends
on the nicotinamide adenine dinucleotide concentration. In the presence of alcohol dehydrogenase, the modified electrode exhibited
a response to addition of acetaldehyde. Therefore, the main product of nicotinamide adenine dinucleotide electroreduction
at the Ru(III) complex/carbon nanotube-modified electrode was the enzymatically active NADH. The purposed sensor can be used
for acetaldehyde determination. 相似文献
74.
A simple procedure has been used for preparation of modified glassy carbon electrode with carbon nanotubes and copper complex. Copper complex [Cu(bpy)2]Br2 was immobilized onto glassy carbon (GC) electrode modified with silicomolybdate, α-SiMo12O404− and single walled carbon nanotubes (SWCNTs). Copper complex and silicomolybdate irreversibly and strongly adsorbed onto GC electrode modified with CNTs. Electrostatic interactions between polyoxometalates (POMs) anions and Cu-complex, cations mentioned as an effective method for fabrication of three-dimensional structures. The modified electrode shows three reversible redox couples for polyoxometalate and one redox couple for Cu-complex at wide range of pH values. The electrochemical behavior, stability and electron transfer kinetics of the adsorbed redox couples were investigated using cyclic voltammetry. Due to electrostatic interaction, copper complex immobilized onto GC/CNTs/α-SiMo12O404− electrode shows more stable voltammetric response compared to GC/CNTs/Cu-complex modified electrode. In comparison to GC/CNTs/Cu-complex the GC/CNTs/α-SiMo12O404− modified electrodes shows excellent electrocatalytic activity toward reduction H2O2 and BrO3− at more reduced overpotential. The catalytic rate constants for catalytic reduction hydrogen peroxide and bromate were 4.5(±0.2) × 103 M−1 s−1 and 3.0(±0.10) × 103 M−1 s−1, respectively. The hydrodynamic amperommetry technique at 0.08 V was used for detection of nanomolar concentration of hydrogen peroxide and bromate. Detection limit, sensitivity and linear concentration range proposed sensor for bromate and hydrogen peroxide detection were 1.1 nM and 6.7 nA nM−1, 10 nM-20 μM, 1 nM, 5.5 nA nM−1 and 10 nM-18 μM, respectively. 相似文献
75.
Iridium oxide (IrOx) films formed electrochemically on the surface boron doped diamond electrode by potential cycling in the range −0.2 to 1.2 V from a saturated solution of alkaline iridium(III) solution. A strongly adherent deposit of iridium oxide is formed after 5–10 potential scans. The properties, stability and electrochemical behavior of iridium oxide layers were investigated by atomic force microscopy and cyclic voltammetry. The boron doped diamond (BDD) electrode modified with electrodeposition of a thin film, exhibited an excellent catalytic activity for oxidation of Hg(I) over a wide pH range. The modified electrode shows excellent analytical performance for Hg(I) amperometric detection. The detection limit, sensitivity, response time and dynamic concentration ranges are 3.2 nM, 77 nA μM−1, 100 ms and 5 nM–5 μM. These analytical parameters compare favorably with those obtained with modern analytical techniques and recently published electrochemical methods. 相似文献
76.
The increasing demand for low-cost and high performance coatings has promoted the development of chip epoxy-based coatings using inert fillers. Attention has been paid here on employing mixtures of DGEBA with barium carbonate as novel ceramic-based filler to produce a coating using 1,8-naphthalene diamine (1,8-NDA) as the crosslinking agent. A substantial increase in the Tg, from 85 to 100 °C, is observed for the optimum composition. The 1,8-NDA-cure of the epoxy composites showed an autocatalytic mechanism. At a specific conversion range the cure reaction of the composites will be controlled by a diffusion-control cure reaction rather than by Kamal autocatalytic model. Model-free isoconversional method is utilized to construct apparent activation energy dependence on conversion plot. The effect of diffusion control is described by an approach proposed by Chern and Poehlein. Greater diffusion control is observed as the cure temperature decreased. 相似文献
77.
The suitability of a xanthone derivative, 1-hydroxy-3-methyl-9H-xanthen-9-one (HMX) as a neutral ionophore for the preparation of a polyvinylchloride (PVC) membrane electrode for aluminum(III) ions was investigated. The prepared electrode exhibits a Nernstian response for Al3+ ions over a wide concentration range (1.0 × 10−6 to 1.6 × 10−1 M) with a limit of detection 6.0 × 10−7 M. It has a relatively fast response time and can be used for at least three months without any considerable divergence in potentials. The proposed membrane electrode revealed very good selectivity for Al3+ ions over a wide variety of other cations and could be used at a working pH range of 3.0-8.5. It was used as an indicator electrode in potentiometric titration of aluminum ions with EDTA and in the determination of Al3+ in different real samples. 相似文献
78.
Abdollah Shidfar Masoumeh Mohammadi 《Numerical Methods for Partial Differential Equations》2007,23(2):456-474
In this article, we consider a nonlinear partial differential system describing two‐phase transports and try to recover the source term and the nonlinear diffusion term when the state variable is known at different profile times. To this end, we use a POD‐Galerkin procedure in which the proper orthogonal decomposition technique is applied to the ensemble of solutions to derive empirical eigenfunctions. These empirical eigenfunctions are then used as basis functions within a Galerkin method to transform the partial differential equation into a set of ordinary differential equations. Finally, the validation of the used method has been evaluated by some numerical examples. © 2006 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 23: 456–474, 2007 相似文献
79.
Kavkhani Roya Pourzaki Mahtab Kianvash Abbas Hajalilou Abdollah Adli Reza Ghaffari 《Journal of Sol-Gel Science and Technology》2021,99(2):444-454
Journal of Sol-Gel Science and Technology - In this study, Mg–Mn–Al ferrite with a chemical composition of Mg0.8Mn0.2Al0.1Fe1.9O4 was synthesized via the sol–gel auto-combustion... 相似文献
80.