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11.
Mir Fazlollah Mousavi Mojtaba Shamsipur Siavash Riahi Mohammad Safy Rahmanifar 《Analytical sciences》2002,18(2):137-140
A new, simple, sensitive, low cost and rapid potentiometric method for direct determination of ultra trace amounts of sodium dodecyl sulfate (SDS) with a new DS(-)-selective electrode is reported. The electrode was prepared by electropolymerization of aniline in acidified DS- ion on the surface of a Pt electrode. The cyclic voltammetry (CV) was used for electropolymerization of polyaniline (PA) in the potential range of -200 to +1000 mV vs. Ag/AgCl. This sensor showed a Nernstian behavior (59.0 +/- 2.3 mV/decade) over a very wide linear range (1.0 x 10(-9)-3.0 x 10(-6) M) with a detection limit of 1.0 x 10(-9) M. The response time of the electrode was 15 s for 1.0 x 10(-7) M of analyte; the electrode can be used for 4 weeks without any major deviation. This electrode can be used in the pH range of 3.5-9.8. The selectivity of electrode to DS- over some organic, inorganic and anionic surfactants was investigated with the fixed primary ion method. The results show that the electrode is highly selective to DS- ion over other ions. The proposed electrode was applied to the determination of DS- in real samples. 相似文献
12.
Three couples of reversible redox peaks of the PW12O403? (PW12) anion, which are composed of two one‐electron and one two‐electron processes occur in the potential range from +0.25 to ?0.7 V in aqueous solutions. The electrocatalytic reduction of nitrite has been studied by the first redox couple of the PW12 anion at the surface of a carbon paste electrode. Cyclic voltammetric and chronoamperometric techniques were used to investigate the suitability of PW12 anion as a mediator for nitrite electrocatalytic reduction in aqueous solution with strongly acidic concentration of H2SO4. Results showed that H2SO4 1.00 M is the best medium for this purpose. In the optimum concentration of H2SO4, the electrocatalytic ability about 500 mV can be seen and the homogeneous second‐order rate constant (ks) for nitrite coupled catalytically to PW12 anion was calculated as 2.52×103 M?1 s?1 using the Nicholson–Shain method. According to our voltammetric experiments, the catalytic reduction peak current was linearly dependent on the nitrite concentration and the linearity range obtained was 3×10?5 to 1.00×10?3 M. The detection limit has been found to be 2.82×10?5 M (2σ). This method has been applied as a selective, simple, and precise method for determination of nitrite in real samples. 相似文献
13.
First, the basic concept of the vector derivative in geometric algebra is introduced. Second, beginning with the Fourier transform
on a scalar function we generalize to a real Fourier transform on Clifford multivector-valued functions
Third, we show a set of important properties of the Clifford Fourier transform on Cl3,0 such as differentiation properties, and the Plancherel theorem. Finally, we apply the Clifford Fourier transform properties
for proving an uncertainty principle for Cl3,0 multivector functions. 相似文献
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Relaxation of toroidal discharges is described by the principle of minimum energy dissipation together with the constraint
of conserved global helicity. The resulting Euler-Lagrange equation is solved in toroidal coordinates for an axisymmetric
torus by expressing the solutions in terms of Chandrasekhar-Kendall (C-K) eigenfunctions analytically continued in the complex
domain. The C-K eigenfunctions are obtained as hypergeometric functions that are solutions of scalar Helmholtz equation in
toroidal coordinates in the large aspect-ratio approximation. Equilibria are constructed by assuming the current to vanish
at the edge of plasma. For the m=0, n=0 (m and n are the poloidal and toroidal mode numbers respectively) relaxed states, the magnetic field, current, q (safety factor) and pressure profiles are calculated for a given value of aspect-ratio of the torus and for different values
of the eigenvalue λ
r
0. The new feature of the present model is that solutions allow for both tokamak as well as RFP-like behaviour with increase
in the values of λ
r
0, which is related directly to volt-sec in the experiment. 相似文献
16.
A. Pendashteh M. F. Mousavi M. A. Kiani S. H. Kazemi M. S. Rahmanifar 《Journal of the Iranian Chemical Society》2012,9(3):389-395
Micro and nanostructured ??-MnO2 are synthesized to investigate the size effect of cathode active materials in battery performance. MnSO4 and (NH4)2S2O8 were used as starting materials to prepare micro and nanostructured samples in the presence of stirring and ultrasonic irradiation, respectively. Structure optimization is done by changing values for temperature and manganese sulphate concentration. The MnO2 micro and nanoparticles are characterized by scanning electron microscopy and X-ray diffraction (XRD). The XRD results reveal that only ??-MnO2 is formed under the reaction conditions. Under the optimized conditions, manganese dioxide nanoparticles, with an average particle size of 56?nm, are obtained. Both micro and nanostructured MnO2 is used as the cathode active material in Li/MnO2 battery. Discharge profiles of stirrer-based cathode material (micro) and ultrasonic instrument-based one (nano) compared with each other in constant discharge currents of 50 and 100?mA?g?1. The results demonstrated that nanosized materials show higher specific capacities and energies. Electrochemical impedance spectroscopy is used to investigate the size effect of cathode material on battery resistance and the results show a copious decrease in total resistance. 相似文献
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S. Rasool Azari Mohammad S. Rahmanifar Maher F. El-Kady Abolhassan Noori Mir F. Mousavi Richard B. Kaner 《Journal of the Iranian Chemical Society》2017,14(12):2579-2590
Aqueous supercapacitors based on neutral solutions have the advantages of high-ionic conductivity, being environmentally friendly, safe, and low cost. However, the operating potential window for most aqueous electrolytes is far lower than that of organic electrolytes that are commonly used in commercial supercapacitors. In this work, we report on the fabrication of a wide potential window, high-energy aqueous asymmetric supercapacitor, without sacrificing power, by using a nanostructured LiMn2O4/reduced graphene oxide (LMO–rGO) nanocomposite. We synthesized the uniformly distributed LMO in the LMO–rGO nanocomposite using a co-precipitation route followed by a low-temperature hydrothermal treatment. In a three-electrode cell setup, the specific capacitance of the LMO–rGO nanocomposite electrode at 1 A/g (1.2 mA/cm2) is 268.75 F/g (258 mF/cm2), which shows a dramatic improvement over the sum of the specific capacitances of pristine LMO (162.5 F/g) and pure rGO (29.94 F/g) electrodes in their relative ratios, when used alone. This finding suggests a synergistic coupling of LMO and rGO in the nanocomposite. We also assembled the LMO–rGO nanocomposite, as the positive electrode, with activated carbon, as the negative electrode, into an asymmetric cell configuration. The device shows an ultra-wide potential window of 2.0 V in a neutral aqueous Li2SO4 electrolyte, with a maximum energy density of 29.6 Wh/kg (which approaches the commercial lead-acid batteries), power density of up to 7408 W/kg, and an excellent cycle life (5% loss after 6000 cycles). These findings confirm that an LMO–rGO nanocomposite is a promising material to meet the demands of real world energy storage. 相似文献
20.
Helane?MS?Costa Augusto?CV?Freitas Júnior Ian?PG?Amaral Izaura?Y?Hirata Patrícia?MG?Paiva Luiz?B?CarvalhoJr Vitor?Oliveira Ranilson?S?BezerraEmail author 《Chemistry Central journal》2013,7(1):166