Showing papers by "University of Tabriz published in 2000"
TL;DR: In this paper, a series of electrochemical measurements, including corrosion potential and corrosion current has been made on polyaniline-coated iron samples in various environments, and the results showed that polyanILine can offer some degrees of protection in the corrosive environments.
167 citations
TL;DR: In this paper, NiPCNF films have been deposited on the surface of an aluminum electrode by a simple electroless dipping method and the cyclic voltammogram of the resulting surface modified Al electrode prepared under optimum conditions, shows a well-behaved redox couple due to the NiIIFeIII/II(CN)5NO]0/−1 system.
117 citations
TL;DR: In this article, the authors determined the thresholds (the onset of decline) for leaf expansion (CL) and transpiration (CT) responses to soil water deficit in chickpea (Cicer arietinum L.) and evaluated their importance to crop performance under rainfed conditions.
80 citations
TL;DR: In this paper, the copper complex with Schiff bases obtained by condensation of 5-phenylazo salicylaldehyde with di-or tri-amines has been synthesized and characterized by their infrared spectra and elemental analysis.
66 citations
TL;DR: In this paper, the electrocatalytic ability of polypyrrole films with ferrocyanide incorporated was demonstrated by oxidation of ascorbic acid at the optimized pH of 4 in a glycine buffer.
Abstract: Functionalized polypyrrole films were prepared by incorporation of Fe(CN)63− as doping anion during the electropolymerization of pyrrole at a glassy carbon electrode from aqueous solution. The electrochemical behavior of the Fe(CN)63−/Fe(CN)64− redox couple in polypyrrole was studied by cyclic voltammetry. An obvious surface redox reaction was observed and dependence of this reaction on the solution pH was illustrated. The electrocatalytic ability of polypyrrole film with ferrocyanide incorporated was demonstrated by oxidation of ascorbic acid at the optimized pH of 4 in a glycine buffer. The catalytic effect for mediated oxidation of ascorbic acid was 300 mV and the bimolecular rate constant determined for surface coverage of 4.5 × 10−8 M cm−2 using rotating disk electrode voltammetry was 86 M−1 s−1. Furthermore, the catalytic oxidation current was linearly dependent on ascorbic acid concentration in the range 5 × 10−4–1.6 × 10−2 M with a correlation coefficient of 0.996. The plot of ip versus v1/2 confirms the diffusion nature of the peak current ip.
55 citations
TL;DR: In this article, a new modified electrode was prepared by electrodeposition of caffeic acid (CFA) at the surface of an activated glassy carbon electrode, which was used to investigate the redox properties of this electrode at various solution pH values and at various scan rates.
Abstract: A new modified electrode was prepared by electrodeposition of caffeic acid (CFA) at the surface of an activated glassy carbon electrode Cyclic voltammetry was used to investigate the redox properties of this electrode at various solution pH values and at various scan rates The pH dependence of the electrode response was found to be 585 mV/pH, which is very close to the expected Nernstian value The electrode was also employed to study electrocatalytic oxidation of reduced nicotinamide adenine dinucleotide (NADH), using cyclic voltammetry, chronoamperometry and rotating disk voltammetry as diagnostic techniques It was found that the modified electrode exhibits potent and persistent electrocatalytic properties toward NADH oxidation in phosphate buffer solution (pH 70) with a diminution of the overpotential of about 450 mV compared to the process at an unmodified electrode The electrocatalytic current increases linearly with NADH concentration in the range tested from 005 to 10 mM The apparent charge transfer rate constant and transfer coefficient for electron transfer between the electrode surface and immobilized CFA were calculated as 112 s−1 and 043, respectively The heterogeneous rate constant for oxidation of NADH at the CFA-modified electrode surface was also determined and found to be about 3 × 103 M−1 s−1 Finally, the diffusion coefficient of NADH was calculated as 324 × 10−6 cm2 s−1 for the experimental conditions, using chronoamperometric results
52 citations
01 Jan 2000
TL;DR: In this article, the thermal infrared imagery is used for detecting topographic features related to geothermal activities and thermal anomalies in the area around the volcanism fields, where the geothermal gradients may be significantly higher than the average value.
Abstract: Publisher Summary Geothermal energy is one of the alternative energy sources that can be used in various ways, including electric power generation and local heating systems. Active faulting, recent volcanic activity, and high surface elevation along the Alpine–Himalayan mountain belt characterize the Azerbaijan plateau. In Azerbaijan most hydro-thermal convention systems are developed in areas related to Plio–Quatemary volcanism and these systems are associated with surface activities, such as hot springs, fumaroles, hydrothermal alteration, and anomalously high surface temperatures. The volcanic activity of the East–Northeast zone had begun in Eocene time and had continued into Plio–Quatemary with the phases of folding Miocene, Pliocene, and Pleistocene times. Geothermal systems in Azerbaijan can therefore be found in regions with a normal or slightly above normal geothermal gradient and especially in regions around the volcanism fields where the geothermal gradients may be significantly higher than the average value. The thermal infrared imagery is used for detecting topographic features related to geothermal activities and thermal anomalies. The difference in temperature between the hotter zones and shallow colder zones generate a conductive flow of heat from the former toward the later zones with a tendency to create uniform conditions that often happen with natural phenomena but are seldom actually attained.
52 citations
TL;DR: In this paper, the electrochemical oxidation of 4-tert-butylcatechol (I) and 3,4-dihydroxybenzaldehyde (II) in methanol at various pH values has been studied using cyclic voltammetry and controlled-potential coulometry.
48 citations
TL;DR: The results indicated that different geographic regions require specific sampling procedures in order to capture the range of genetic variation observed in T. urartu populations.
Abstract: Genetic variation and its distribution within and among 23 populations of Triticum urartu collected from Syria, Lebanon, Turkey, Armenia, and Iran was estimated using isozyme markers at eight polymorphic loci. The number of alleles per locus (A= 1.21), percentage polymorphic loci (P= 20.1%), and mean gene diversity (He= 0.024) were relatively low. In a population from Lebanon, a high number of alleles per locus (A= 2.13) and percentage polymorphic loci (P= 87.5%) was found. On average, genetic variation among populations (GST= 0.407) was smaller than within-population variation (0.593). However, different patterns of genetic structure were found among various geographic regions. Interpopulation variation was highest for the Iranian populations (0.89) followed by the Turkish populations (0.66). A reverse pattern was observed for the Syrian (0.11) and for the Lebanese (0.13) populations. The Armenian populations exhibited similar interpopulation and within-population variation. Principal component and cluster analyses resulted in distinct grouping of the geographically proximal populations, with the exception of the two Iranian populations. The Turkish populations were different from the neighboring Armenian populations compared to other countries. The populations from southern Syria and those from Lebanon also exhibited a high degree of genetic diversity. The two most heterozygous loci, Mdh-2 and Pgi-2, separated the populations along the first and second principal components, respectively. Most of the rare alleles were scattered sporadically throughout the geographic regions. Rare alleles with high frequencies were found in the Turkish and Armenian populations. These results indicated that different geographic regions require specific sampling procedures in order to capture the range of genetic variation observed in T. urartu populations.
42 citations
TL;DR: In this article, the use of aluminum substrate as an electrode and the modification of its surface by means of the thin film of nickel pentacyanonitrosylferrate (NiPCNF) was developed.
Abstract: The use of aluminum substrate as an electrode and the modification of its surface by means of the thin film of nickel pentacyanonitrosylferrate (NiPCNF) was developed. The modification conditions of aluminum surface including the electroless deposition of metallic nickel on the electrode surface from NiCl2+NH4Cl solution and chemical derivatization of deposited nickel to NiPCNF film in solution of 10 mM sodium pentacyanonitrosylferrate (PCNF)+0.5 M NaNO3+0.03 M HNO3 are described. The modified Al electrode prepared under optimum conditions, shows a well-defined redox couple due to [NiIIFeIII/II(CN)5NO]0/–1 system. The effect of pH and radius of the hydrated alkali-metal cation of supporting electrolyte on the electrochemical characteristics of the modified electrode were studied in detail. Diffusion coefficients of alkali-metal cations in the film (D),transfer rate constant for electron (ks) and transfer coefficient (α) were calculated. The electrocatalytic activity of the modified electrode on the oxidation of hydrogen peroxide and ascorbic acid was demonstrated as a typical example of applications.
40 citations
TL;DR: Pitzer et al. as mentioned in this paper measured the osmotic coefficients of calcium chloride and calcium nitrate in ethanol using the isopiestic method at 298 K. The molality range covered in this study correspond to about 0.1 − 2.3 ǫ kg − 1 for CaCl 2 and 0.3 − 3 ǔ kg −1 for Ca(NO 3 ) 2.
TL;DR: In this paper, anodic stripping voltammetry (ASV) was developed in dichloromethane, using the differential pulse technique to strip the amalgamated copper from the hanging mercury drop electrode (HMDE).
TL;DR: In this paper, aqueous solutions of several polymer + salt systems are presented at (25, 35, and 45) °C. The polymers used are poly(ethylene glycol) of two molar masses, 2000 and 4000, and the salts...
Abstract: Densities for aqueous solutions of several polymer + salt systems are presented at (25, 35, and 45) °C. The polymers used are poly(ethylene glycol) of two molar masses, 2000 and 4000, and the salts...
TL;DR: Comparison of the NLO properties of two dentate with three dentate salicylaldiminine-based ligands reveals that the presence of -NO2 and -OCH3 groups as R1 and R2 substituents enhance the second-order nonlinear optic properties of these type ligands.
TL;DR: In this article, Horner et al. synthesized 2-(2-Furyl)pyrrole, 2,5-bis[2-furyl]ethenyl]furan, and 2-[2-(2]-2]-thenyl]-5]-2-(thienyl)etyl]-furan via Horner, Witig and cyclization methods and they were electropolymerized oxidatively.
TL;DR: Using fuzzy decision-making procedure, the regions with more priorities are more connected to the distribution net, while the maximum consumption criterion is also reasonably respected.
TL;DR: A highly sensitive spectrophotometric method is described for the determination of trace amounts of osmium(VIII), based on its catalytic effect on the oxidation of carminic acid by hydrogen peroxide.
TL;DR: In this article, differential pulse polarography (DP) was used for the determination of ferric, ferrous and total iron in a mixture and successfully applied to the speciation of iron in rocks.
TL;DR: In this article, the Wigner fuction of a cavity field can be reconstructed from the spontaneous emission spectrum in driven three-level atomic systems, where the driving field is the quantized field inside a cavity.
Abstract: We show that the Wigner fuction of a cavity field can be constructed from the spontaneous emission spectrum in driven three-level atomic systems. We consider two configurations, the upper- and lower-level couplings, in which the driving field is the quantized field inside a cavity. In the proposed method, the Wigner function of the driving field is recovered in a straightforward manner, without much mathematical manipulation of the experimental data, from the spontaneous emission spectra.
01 Oct 2000
TL;DR: In this paper, the p-q theory is combined with the instantaneous positive sequence extraction of load current and utility voltage to suppress reactive power, current harmonics, three-phase imbalance and neutral current cancellation simultaneously in 3-phase 4-wire distribution systems.
Abstract: This paper presents a new control strategy for parallel active filters. The instantaneous positive sequence extraction of load current and utility voltage is combined with the p-q theory. This method is able to control a four leg active filter for compensation of reactive power, current harmonics, three-phase imbalance and neutral current cancellation simultaneously in 3-phase 4-wire distribution systems. The presented method can operate in harmonic polluted and/or imbalance utility voltage case. The simulation results prove the considerable ability of control strategy to suppress the above-mentioned subjects with a very fast dynamic response. This method is also usable in 3-wire systems.
TL;DR: A modified discrete adaptive control system with neural estimator and neural controller based on the model presented by Etxebarria is presented and the effect of adding a momentum term to the learning rule of the neural network is studied.
TL;DR: Direct nucleophilic displacement of halide X (X=Cl or I) takes place when the compounds (Me3Si)3CSiRR′X with R=Me, R′=(C6H4Me-p), CH2CH R=Bu, R'=Cl, or R=Ph, R '=Ph) are treated with solutions of KOCN, KSCN, KCN, or NaN3 in CH3CN or MeOH, and H2O in DMSO, or CH 3CN.
TL;DR: The method, which estimates the rotor position angles and rotating speeds at several conditions by measuring the instantaneous values of stator voltages and currents, is an extended Kalman filter (EKF).
TL;DR: In this paper, the anisotropic (Nd,MM) 2 (Fe,Co,Ni) 14 B-type magnets were produced using the binary alloy sintering method (MM denotes a Misch-metal).
TL;DR: In this paper, the phase identification studies showed decomposition of strontium hexaferrite into Fe 2 O 3 and Sr 7 Fe 10 O 22 and the reduction of the resultant Fe 2O 3 during reaction with hydrogen.
TL;DR: In this paper, the macroscopic conductivity becomes isotropic for large scales and anisotropy vanishes with a scaling exponent which is computed exactly for arbitrary values of d and decimation numbers b = 2,3,4 and 5.
Abstract: Restoration of macroscopic isotropy has been investigated in ( d +1)-simplex fractal conductor networks via exact real-space renormalization group transformations. Using some theorems of fixed-point theory, it has been shown very rigoroursly that the macroscopic conductivity becomes isotropic for large scales and anisotropy vanishes with a scaling exponent which is computed exactly for arbitrary values of d and decimation numbers b =2,3,4 and 5.
TL;DR: In this paper, a p-type uncooled Hg 1− x Cd x Te photoconductor was realized which can be used in the 2-6 μm spectral region with a maximum detectivity occurring at 5 μm.
TL;DR: A competitive neural network architecture is used as an intelligent fault diagnosis system to detect the fault sources in different subsystems or elements of a plant or any other device and it is shown that the fourth procedure is more convenient for human type decision-making.
TL;DR: A Novel Method for the Synthesis of 4H-PYRAN-4-ONE DERIVATIVES is described in this article, where the authors present a novel method for the SYNTHESIS of four-homing programs.
TL;DR: In this paper, TsiSiBr3 reacts with 0.1 M NaOR/ROH (R=Me, Et, iPr) to give the substitution and elimination products, and (Me3Si)2CHSi(C6H4OMe-p)OG(OR).
Abstract: The Compounds TsiSiXX′X″ [Tsi[dbnd](Me3Si)3,C; X[dbnd]X′[dbnd]X″=Br X=(C6H4OMe-p), X′=X″[dbnd]Cl X=Bu, X′=X″=Cl; X′=Me, X″=F) synthesised and reacted with boiling NaOR/ROH (R=Me, Et, iPr) have been shown to give the products of type (Me3,Si)2CHSiYZOR(Y=OR, X Z=OR, X′). It is suggested that the reaction proceeds through an elimination, analogous to E2 elimination of alkyl halides, involving cynchronous attack of RO− at an SiMe,3 group, libration of X−, and formation of (Me3Si)2C[dbnd]SiYZ. The compound TsiSiBr3 reacts with 0.1 M NaOR/ROH to give the substitution and elimination products, TsiSiBr2(OR), TsiSiBr(OR)2, and (Me3Si)2CHSi(OR)3. The compounds TsiSi(C6H4OMe-p)Cl2, TsiSiBuCl2. and TsiSi(C6H4OMe-p)MeF react analogouly to give (Me3Si)2CHSi-(C6H4OMe-p)(OR)2, (Me3Si)2CHSi(C6H4OMe-p)OG(OR), (Me3Si)2CHSi Bu(OR)2, (Me3Si)CH2SiBu(OR2) and (Me3Si)2CHSi(C6H4OMe-p)MeOR