排序方式: 共有45条查询结果,搜索用时 15 毫秒
1.
Vahideh Masoumi Ali Mohammadi Mohsen Amini Mohammad Reza Khoshayand Rasoul Dinarvand 《Journal of Solid State Electrochemistry》2014,18(6):1763-1771
In this work, polyaniline, polypyrrole, and polyaniline/polypyrrole composite fibers were synthesized in the absence and presence of oxidized multiwalled carbon nanotubes using electrochemical cyclic voltammetry with CF3COOH as dopant. Thermal stability of these fibers was studied by differential scanning calorimetry. Then, headspace solid-phase microextraction process coupled with gas chromatography and flame ionization detector was used for comparing extraction capability of benzaldehyde from aqueous solution. Since polyaniline fiber showed better extraction efficiency than the other fibers, its preparation conditions including acid concentration, aniline concentration, scan rate, and amount of multiwalled carbon nanotubes were studied by means of the “one-factor-at-a-time method”. The analytical performance of polyaniline fibers were investigated to determine benzaldehyde from the aqueous solution. The morphology and texture of polyaniline fibers were examined by field emission scanning electron microscopy and Fourier transform infrared spectroscopy analyses. The attained results revealed that the perfect conditions for acid concentration, aniline concentration, scan rate, and multiwalled carbon nanotubes content were 0.5 M, 0.2 M, 25 mV s?1, and 0.02 wt%, respectively. The limit of detection for the proposed polyaniline fiber was 15 ng ml?1. 相似文献
2.
M.M. Rashidi G. Domairry S. Dinarvand 《Communications in Nonlinear Science & Numerical Simulation》2009,14(3):708-717
In this work, the homotopy analysis method (HAM), one of the most effective method, is implemented for finding approximate solutions of the Burger and regularized long wave (RLW) equations. Comparisons are made between the results of the proposed method and homotopy perturbation method (HPM). It illustrates the validity and the great potential of the homotopy analysis method in solving nonlinear partial differential equations. 相似文献
3.
Mohammad Mehdi Rashidi Saeed Dinarvand 《Nonlinear Analysis: Real World Applications》2009,10(4):2346-2356
The similarity transform for the steady three-dimensional problem of a condensation film on an inclined rotating disk gives a system of nonlinear ordinary differential equations which are analytically solved by applying a newly developed method namely the homotopy analysis method (HAM). The analytic solutions of the system of nonlinear ordinary differential equations are constructed in the series form. The convergence of the obtained series solutions is carefully analyzed. The velocity and temperature profiles are shown and the influence of the Prandtl number on the heat transfer and the Nusselt number is discussed in detail. The validity of our results is verified by numerical results. 相似文献
4.
Mohammad Reza Ganjali Zahra Memari Farnoush Faridbod Rassoul Dinarvand Parviz Norouzi 《Electroanalysis》2008,20(24):2663-2670
The increase use of ion sensors in the fields of environmental, agricultural, and medical analysis is stimulating analytical chemists to develop new sensors for fast, accurate, reproducible, and selective determination of various ions. In this study a new samarium membrane sensor was constructed and for the first time, it was applied as a probe in indirect determination of hyoscine, homatropine, and tramadol drugs in their pharmaceutical formulation. The proposed membrane sensor was constructed based on a membrane containing 2% sodium tetraphenyl borate (NaTPB) as an anionic additive, 63% dibutyl phthalate (DBP) as solvent mediator, 5% ionophore, and 30% poly(vinyl chloride) (PVC). The proposed Sm(III) electrode exhibits a Nernstian response of 19.35±0.2 mV per decade of samarium concentration, and has a lower detection limit of 1.0×10?7 M. The linear range of the sensors was 1.0×10?7–1.0×10?1 M. It works well in the pH range of 3.0–8.0. 相似文献
5.
Norouzi P Ganjali MR Daneshgar P Dinarvand R Moosavi-Movahedi AA Saboury AA 《Analytica chimica acta》2007,590(1):74-80
In this work a novel method for the fast monitoring of lidocaine in flow-injection systems has been developed. The fast Fourier transform continuous cyclic voltammetry (FFTCV) at gold microelectrode in flowing solution system was used for determination of lidocaine in its pharmaceutical formulation. The presented technique was very simple, precise, accurate, time saving and economical, compared with all of the previously reported methods. The recommended technique demonstrated some advantages over other reported methods. Firstly, there was no need for the oxygen removal from the test solution. Secondly, a picomolar detection limit was achieved, and additionally, the method was fast enough for the determination of any such compound, in a wide variety of chromatographic methods. The method was linear across the concentration range of 240-1.1 × 105 pg mL−1 (r = 0.996) with a limit of detection and quantitation 117.3 and 240 pg mL−1, respectively. As a conclusion this system offers the requisite accuracy, sensitivity, precision and selectivity to assay lidocaine in injections. 相似文献
6.
Large deviations for random walks in a mixing random environment and other (non‐Markov) random walks
F. Rassoul‐Agha 《纯数学与应用数学通讯》2004,57(9):1178-1196
We extend a recent work by S. R. S. Varadhan [8] on large deviations for random walks in a product random environment to include more general random walks on the lattice. In particular, some reinforced random walks and several classes of random walks in Gibbs fields are included. © 2004 Wiley Periodicals, Inc. 相似文献
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We have studied the influence of cascaded second-order effects on the spectral density of a second-harmonic pulse generated in thin KDP and beta-barium borate crystals by an intense femtosecond pulse. A noticeable evolution of spectral density is recorded for any value of phase mismatch. This evolution is in good agreement with the solution of the nonlinear propagation equation and allows a simple direct measurement of the effective susceptibility of the studied crystals. 相似文献
9.
Bahareh Feyzi Barnaji Hamid Salehzadeh Behzad Darbasizadeh Rassoul Dinarvand Abdollah Salimi Ali Mohammadi 《Electroanalysis》2019,31(9):1719-1727
In the present work, the oxidation of acetaminophen in the absence and presence of eflornithine was electrochemically investigated by means of cyclic voltammetry at a glassy carbon electrode (GCE). Our results indicate that N‐acetyl‐p‐benzoquinone imine (NAPQI) produced from two‐electron electrochemical oxidation of acetaminophen participates in a Michael addition reaction with eflornithine via an ECE mechanism. This fact was used for the determination of eflornithine using differential pulse voltammetry (DPV) technique on the surface of β‐Cyclodextrin modified glassy carbon (β‐CD/GC) electrode. β‐CD/GC electrode was prepared through an electrodeposition procedure and characterized by Fourier‐transform infrared spectroscopy (FT‐IR), Cyclic Voltammetry (CV), Field Emission Scanning Electron Microscopy (FESEM) and Energy‐dispersive X‐ray spectroscopy (EDS) techniques. Under optimum conditions, the β‐CD/GC electrode showed a good linearity as a function of the eflornithine concentration over the range from 5 to 100 μM with detection limit and quantification limit of 1.94 and 5.8 μM, respectively. Finally, the proposed protocol was confirmed to be successful in determination of eflornithine in human urine samples with good recovery, ranging from 97.2 % to 104.8 %. 相似文献
10.
Saeed Shahrokhian Fatemeh Ghorbani-Bidkorbeh Ali Mohammadi Rasoul Dinarvand 《Journal of Solid State Electrochemistry》2012,16(4):1643-1650
A mixture of multi-walled carbon nanotube/graphite paste electrode modified with a salophen complex of cobalt was prepared
and was applied for the study of the electrochemical behavior of 6-mercaptopurine (MP) using cyclic and differential pulse
voltammetry (DPV). An excellent electrocatalytic activity toward the oxidation of MP was achieved, which led to a considerable
lowering in the anodic overpotential and remarkable increase in the response sensitivity in comparison with unmodified electrode.
Utilizing DPV method, a linear dynamic range of 1–100 μM with detection limit of 0.1 μM was obtained in phosphate buffer of
pH 3.0. The electrochemical detection system was very stable, and the reproducibility of the electrode response, based on
the six measurements during 1 month, was less than 3.0% for the slope of the calibration curves of MP. The electrochemical
method as a simple, sensitive, and selective method was developed for the determination of MP in pharmaceutical dosage form
and human plasma without any treatments. 相似文献