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دسترسی آزاد مقاله
1 - Modeling of discharge processes in a new type of pulse-plasma ignition systems with a controlled spark gap
Farit Gizatullin Renat Salikhov Andrey LobanovThe results of computer and physical modeling of discharge processes in a new type of pulse-plasma ignition systems for gas turbine engines with a controlled switching spark gap are presented. A circuit design model of a pulse-plasma ignition system has been developed, چکیده کاملThe results of computer and physical modeling of discharge processes in a new type of pulse-plasma ignition systems for gas turbine engines with a controlled switching spark gap are presented. A circuit design model of a pulse-plasma ignition system has been developed, which makes it possible to evaluate the patterns of discharge processes in a semiconductor spark plug depending on the parameters of the discharge circuits - the capacitances of high-voltage and low-voltage storage capacitors, the inductance of the main discharge circuit. The results of computer simulation are confirmed experimentally, the increased efficiency of the ignition system with a controlled spark gap compared to the known circuit solutions containing two switching spark gaps is substantiated. پرونده مقاله -
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2 - The effect of powered needle-electrode geometry on the RF plasma jet
Sayyed-Jalal Pestehe Davood HassanpourAn atmospheric pressure plasma microjet device with a tapered ground electrode and dielectric barrier is developed. The effects of the powered electrode geometry and input power on the specifications of the launched RF plasma jets are investigated. Needle-powered electr چکیده کاملAn atmospheric pressure plasma microjet device with a tapered ground electrode and dielectric barrier is developed. The effects of the powered electrode geometry and input power on the specifications of the launched RF plasma jets are investigated. Needle-powered electrodes with different types, shapes, lengths, and diameters, such as perforated and un-perforated hollow cylindrical tubes with different inner and outer diameters or solid with flat tip and with sharp tip steel nail rods are examined. The effects of the discharge gap size on the launched jet lengths and widths are studied. The axial and radial components of the electric field are simulated at the device output nozzle by applying radiofrequency power to the needle electrode and their possible effects on the plasma plume generation are discussed. The variations of the launched microjet lengths and widths are investigated versus the working gas (argon) flow rates in two experiments with two different fixed input powers. It has been shown that there is an optimum flow rate to obtain maximum jet length with a suitable narrow width. The effects of nozzle diameter, how to inject gas into the system, and argon flow rates on the plasma plume characteristics are discussed through the Reynolds number. پرونده مقاله -
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3 - The effects of grounded electrode geometry on RF-driven cold atmospheric pressure plasma micro-jet
Davood Hassanpour Sayyed-Jalal PesteheAbstractWith the argument that two-electrode DBD-like systems are much more operational than single-electrode systems in biomedical applications, targets sensitive to temperature and electric shock, the effects of parameters associated with the geometry of the grounded چکیده کاملAbstractWith the argument that two-electrode DBD-like systems are much more operational than single-electrode systems in biomedical applications, targets sensitive to temperature and electric shock, the effects of parameters associated with the geometry of the grounded electrode such as its shape, size, and position it at the output of the atmospheric pressure RF plasma jet in two-electrode systems is investigated. By varying the position of the typical narrow ring grounded electrode on the dielectric tube toward the powered electrode, the ratio of the axial to radial electric field components depend on the externally applied potential to the plasma has been investigated and shown that the axial component of the electric field is maximized at certain position(s) of the grounded electrode. The analysis of the data indicates that there is an inverse relationship between the magnitude of the axial electric field in the plasma channel and the discharge ignition voltage, and a direct relationship with the plasma jet length. It is known that by increasing the width of the ground electrode until the full covering of dielectric, the jet length increases from the dielectric output to the neighborhood near the needle electrode, and reduces the discharge ignition threshold and consequently power consumption of the jet, but increasing its width to greater than the above values does not have a significant effect on jet output. It has also been shown that by tapering the dielectric end and fully covering it with its conical-shaped electrode, the output jet length increases and decreases its width. پرونده مقاله -
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4 - Electroanalysis of Trace Amount Hg2+ Ion in Water Samples Using Sensor Co3O4-CeO2-ZnO/CPE and Square Wave Anodic Stripping Voltammetry (SWASV) Method
Shahnaz DavoudiThis study describes the construction of a new electrochemical sensor and applies for determination of Hg2+ ion. This sensor was prepared using a new nanocomposite base on (Co3O4-CeO2-ZnO). Although the other methods (gas or liquid chromatographic, electrophoresis, flow چکیده کاملThis study describes the construction of a new electrochemical sensor and applies for determination of Hg2+ ion. This sensor was prepared using a new nanocomposite base on (Co3O4-CeO2-ZnO). Although the other methods (gas or liquid chromatographic, electrophoresis, flow injection) for measuring Hg2+ ion has advantages such as excellent accuracy and reproducibility, it has limitations such as long-time measure, high equipment cost. In this study, for determination Hg2+ ion we used a from sensor Co3O4-CeO2-ZnO/CPE and voltammetric method. The calibration curve was linear in the range of (0.03 to 35.0 µgL−1). The standard deviation of less than (3%), and detection limits (3S/m) of the method (0.09 nM) for Hg2+ ion were obtained for the proposed electrochemical sensor by Co3O4-CeO2-ZnO/CPE with (95%) confidence evaluated. Finally, Co3O4-CeO2-ZnO/CPE has been successfully applied for the determination of Hg2+ ion in water samples. The method introduced to measure Hg2+ ion in water samples was used and can be used for other samples. پرونده مقاله -
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5 - Electrochemical Determination of Thioridazine at Carbon Ionic Liquid Electrode
Mahzad Sakiani Abulhasan Fatemeh FarjamiIn this manuscript a simple, rapid, and sensitive electrochemical method for the direct determination of thioridazine (TR) was developed. The electrochemical behavior of TR was studied at carbon ionic liquid electrode (CILE). The cyclic voltammetric results showed that چکیده کاملIn this manuscript a simple, rapid, and sensitive electrochemical method for the direct determination of thioridazine (TR) was developed. The electrochemical behavior of TR was studied at carbon ionic liquid electrode (CILE). The cyclic voltammetric results showed that CILE remarkably improved electrocatalytic activity towards the oxidation of TR in slightly acidic solutions. It led to a significant enhancement of the anodic peak current for TR with three anodic peaks at 0.59V, 0.78V and 0.93V, respectively and could effectively accumulate the drug at the electrode surface. The electrocatalytic performance was further exploited as a sensitive detection scheme for the determination of TR by differential-pulse voltammetry (DPV). Under optimized conditions, the calibration linear range and detection limit were 0.25 to 100 𝜇M and 50 nM, respectively. The proposed method was successfully used to quantification of TR in pharmaceutical samples. Also the analytical performance of this sensor has been evaluated for detection of TR in human serum samples. پرونده مقاله -
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6 - Removal of Basic Dye Bromophenol Blue from aqueous solution by Electrocoagulation using Al – Fe Electrodes: Kinetics, Equilibrium and Thermodynamics Studies.
Abideen Adeogun B BabuElectrocoagulation (EC) in a batch cell with Al anode and Fe cathode in monopolar parallel (MP) connection was used for the removal of basic dye, Bromophenol Blue (BPB). The effects of current density, pH, temperature and initial dye concentration, on the process were i چکیده کاملElectrocoagulation (EC) in a batch cell with Al anode and Fe cathode in monopolar parallel (MP) connection was used for the removal of basic dye, Bromophenol Blue (BPB). The effects of current density, pH, temperature and initial dye concentration, on the process were investigated. Equlibrium data were analyzed using four model equations: Langmuir, Freudlinch, Temkin and DubininRadushkevich. Data obtained from the time dependent electrocoagulation removal of BPB were analyzed with pseudo-first-order, pseudo-second-order and Elovic kinetic models. The study showed that the process depend on current density, temperature, pH and initial dye concentration. The process attained equilibrium after 15 minutes at 30 oC, all the isotherm models fitted the data with R2 > 0.9. The maximum removal capacity Qm value of 166.50 mg g-1 was obtained for the study while the first order kinetic model best described the process based on the lower values of %SSE. The calculated thermodynamics parameters (∆Go, ∆Ho and ∆So) indicated that the process is spontaneous and endothermic in nature. پرونده مقاله -
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7 - Electrocatalytic properties of platinum and it's binary alloy with vanadium in oxygen reduction reaction(ORR)
Mohammad Yari Sajjad Sedaghat SherehjiniThe electrocatalysis of the oxygen reduction reaction (ORR) on carbon supportedPt-V (1:1) catalyst in polymer electrolyte fuel cells (PEFC) was investigated. Atan oxygen pressure of one atm an enhanced electrocatalytic property of Pt-V/Ccompared with Pt/C is revealed. T چکیده کاملThe electrocatalysis of the oxygen reduction reaction (ORR) on carbon supportedPt-V (1:1) catalyst in polymer electrolyte fuel cells (PEFC) was investigated. Atan oxygen pressure of one atm an enhanced electrocatalytic property of Pt-V/Ccompared with Pt/C is revealed. These results indicate the occurrence of adifferent electrocatalytic mechanism for the ORR on Pt/C and Pt-V/C. Anincrease of mass transport overpotentials is observed for the Pt-V/C catalyst, andthis was related to the presence of vanadium oxide. So the ORR activity of Pt-V/Cat oxygen pressure of one atm is higher than that of Pt/C. پرونده مقاله -
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8 - Polymeric Membrane Sensor for Potentiometric Determination of Tin(II) Ions
Hossein Aghaei Masood Giahi Majjid Arvand Mehran AghaeiTin(II)-ion-selective electrode consisting of dibenzo-18-crown-6 (DB18C6) as an ionophore inPVC matrix was developed. The influences of membrane composition, selectivity, response time,reversibility and temperature on the electrode performance were investigated. The ele چکیده کاملTin(II)-ion-selective electrode consisting of dibenzo-18-crown-6 (DB18C6) as an ionophore inPVC matrix was developed. The influences of membrane composition, selectivity, response time,reversibility and temperature on the electrode performance were investigated. The electrodeshowed a near Nernstian response for Sn2+ ions over a concentration range from 1.0× 10-6 1.0× 10-2 M with a slope of 27.5 ± 0.6 mV per concentration decade in a acidic solution (pH=1). Thelimit of detection was 8.0 × 10-7 M. It has a relatively fast response time and can be used for atleast 3 months without any divergence in potentials. The isothermal temperature coefficient of thiselectrode amounted to 0.0012 V/ °C. The stability constant (log Ks) of the Sn(II) DB18C6complex was determined at 25 °C by potentiometric titration in mixed aqueous solution. پرونده مقاله -
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9 - Construction of S?-Selective Electrode and Thermodynamic Study of the Ternary Aqueous Mixed Electrolyte System (SrCl2, KG, H20) Using Potentiometric Method
M. Kia A. Islamnezhad Sh. ShariatiIn order to preparing strontium ion selective electrode 6-(4- nitropheny1)-2-pheny14, 4- dipropy1-3, 5-diaza-bicyclo [3, 1, 0] hex-2-ene (NPDBH) was used as an ionophore. This electrode responds to Sr (II)ion with a sensitivity of 28.2 ± 0.5 mV/decade over the ra چکیده کاملIn order to preparing strontium ion selective electrode 6-(4- nitropheny1)-2-pheny14, 4- dipropy1-3, 5-diaza-bicyclo [3, 1, 0] hex-2-ene (NPDBH) was used as an ionophore. This electrode responds to Sr (II)ion with a sensitivity of 28.2 ± 0.5 mV/decade over the range 1.0 x 10-6 to 1.0 Mat pH 3.0-10.0. Thelimit of detection was 2.4 x 10-7 M. The influences of membrane composition, the pH of the testsolution, the temperature effect and the interfering ions on the electrode performance for the proposedelectrode were investigated. In the next step, electrolyte solution system SrCl2, KC1, H20 in the highconcentration range were thermodynamically investigated. The thermodynamic investigations wereperformed by evaluation of potentiometric experimental data, successfiffly. پرونده مقاله -
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10 - Application of a dioxime-PVC electrode to potentiometric studies of Cr(III) ion
H. Aghaie M. H. Felcri M. Arvand K. Zare M. AghaieA PVC membrane Cr(III) ion selective electrode has been constructed using 2H-1,4-benzothioazine-2,3(4H)dione dioxime (BTD) as membrane carrier. The influence of membrane composition on the electroderesponse was studied. The electrode exhibits a Nernstian response over a چکیده کاملA PVC membrane Cr(III) ion selective electrode has been constructed using 2H-1,4-benzothioazine-2,3(4H)dione dioxime (BTD) as membrane carrier. The influence of membrane composition on the electroderesponse was studied. The electrode exhibits a Nernstian response over a Cr(III) concentration range of 1.0 x10 6 to 1.0>< 10-1 M (r = 0.99) with a slope of 19.5 ± 0.5 mV per decade of concentration, and a detection limitof 8.9 x le M. The selectivity coefficient values as determined by separate solution method (SSM) indicateexcellent selectivity for Cr(III) ion over a large number of other ions. Applications of the proposed electrode tothe determination of Cr(III) in real samples and as an indicator for potentiometric titration of Cr(III) ion withEDTA, are reported. پرونده مقاله -
دسترسی آزاد مقاله
11 - Kinetic study on the electrodecolorization of C.I. Acid Yellow 23
N. Modirshahla M.A. Behnajady S. KooshaiianThe electrocoagulation (EC) is a simple and efficient method for the treatment of many water and wastewaters.The kinetics of decolorization of Acid Yellow 23 by EC using iron electrodes was studied. Theelectrodecolorization rate follows pseudo-first order kinetic with r چکیده کاملThe electrocoagulation (EC) is a simple and efficient method for the treatment of many water and wastewaters.The kinetics of decolorization of Acid Yellow 23 by EC using iron electrodes was studied. Theelectrodecolorization rate follows pseudo-first order kinetic with respect to the AY23 concentration havingkapp= 5.65 cm min-1 at T= 295 K. The rate equation is as follows:ln [AY23]t ln [AY23]0 = -kapp2336 cm t250 cmThe pseudo-first order rate constant (kapp) is sensitive to the operational parameters. The kapp is low in bothhighly acidic and basic conditions. For the optimum operating conditions in electrodecolorization of AY23, theactivation energy was 41.15 kJ mol-1, sludge volume was about 8 ml from 250 ml of the original AY23 solution.The electrical energy consumption required for this treatment was 7.74 × 10-4 kW h and the electrodeconsumption was 37.4 mg. پرونده مقاله -
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12 - Potentiometric Study on the Interaction of Hexadecyl Ttimethyl Ammonium Bromide (HTAB) with Urease Enzyme
Morteza KeshavarzIn this research, the interaction of hexadecyl trimahyl ammonium bromide (HTAB) with enzyme ureasehas been investigated comprehensively at different experimental conditions such as ionic strength, proteinconcentration using ion selective membrane electrode of surfactant چکیده کاملIn this research, the interaction of hexadecyl trimahyl ammonium bromide (HTAB) with enzyme ureasehas been investigated comprehensively at different experimental conditions such as ionic strength, proteinconcentration using ion selective membrane electrode of surfactants. The obtained binding isotherms frompotentiometnc studies have been analyzed by different theories such as Wyman binding potennal.Seatehard diagram, binding capacity concept and Hill equation. The results indicate the aggregation ofurease at concentrations more than I mg/m1 of protein. !mu-easing the ionic strength to I m41, causes todecrease the interaction with mase but increasing the ionic strength to more than I inftl again causes toincrease the interaction. Tlus issue can be due to stability of unease at ionic strength oil rn.M. increasingthe concentration of urease to 3 RIM causes to gradual and regular decreasing of interaction and at higherconcentrations, the intense increase in interaction is resulted. Increasing pH from 6.5 to 9.7 does not creategreat changes at binding isotherms that is due to slight change of dissociation &pee of acidic and basicgroups and third structure of urease at this limit. In all studied cases m comparison with similar case, itshows stronger interaction with urease. This issue is Justifiable according to longer hydrocarbon tail thatincreases its hydrophobic properly that indicates the special role of hydrophobic interactions in interactionsprocess of ionic surfatttuns with proteins. پرونده مقاله -
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13 - Chromium(III) ion selective electrode based on 2H-1,4-benzothioazine-2,3(4H)dione dioxime as a neutral carrier
M.H. Fekri M. Darvishpour E. BaghdarA poly(vinyl chloride) membrane based on a new a-dioxime derivative as membrane carrier was prepared andinvestigated as a Cr(III) selective electrode. The electrode exhibits a good potentiometric response for Cr(III)over a wide concentration range 1.0 x 10-6 to 1.0 x 10 چکیده کاملA poly(vinyl chloride) membrane based on a new a-dioxime derivative as membrane carrier was prepared andinvestigated as a Cr(III) selective electrode. The electrode exhibits a good potentiometric response for Cr(III)over a wide concentration range 1.0 x 10-6 to 1.0 x 10-1 M with a slope 19.5+0.5 mV/decade and low detectionlimit of 8.9 x 10-7 M. It has a fast response time < 15 s. The best performance was observed with the membrancehaving the PVC-ligand-acetophenone-oleic acid composition 6:1:13:1. The proposed electrode works well in awide p1-1 range 1.5-5.5. The proposed sensor was successfuly used for the determination of Cr(III) ions insamples and real samples and as indicator electrode in potentiometric titration of Cr(III) ion. The application ofthis electrode for Cr(III) determination in real samples is described. The results obtained with this procedure arein close agreement with those obtained using AA spectrophotometry. پرونده مقاله -
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14 - Fe (II) Ion-Selective Membrane Electrode based onTetra-Phenyl Porphyrin in PVC Matrix
N. Farahani H. AghaieFe2+ ion-selective membrane sensor has been fabricated from polyvinyl chloride (PVC) matrixmembrane containing neutral carrier tetra phenyl porphyrin (TPP) ionophore. The addition ofsodium tetraphenylborate (NaTPB) and the plasticizer DBP has been found to substantially چکیده کاملFe2+ ion-selective membrane sensor has been fabricated from polyvinyl chloride (PVC) matrixmembrane containing neutral carrier tetra phenyl porphyrin (TPP) ionophore. The addition ofsodium tetraphenylborate (NaTPB) and the plasticizer DBP has been found to substantiallyimprove the performance of the sensor. The best performance was obtained with the sensor havinga membrane of composition of TPP: NaTPB: DBP: PVC in the ratio 6:3:61:30 respectively. Thesensor shows a linear response over a wide concentration range of 1.0 x 10-6 to 1.0 x 10-2 M witha Nemstian slope of 29.4 ± 0.6 mV decade-1 and a detection limit of 9.6 x 10-7 M. It has aresponse time of <12 s and can be used for more than seven weeks without any measurabledivergences in its potentials. The proposed sensor could be used in a pH range of 3.0-5.0.Potentiometric selectivity coefficients determined by matched potential method (MPM) indicateexcellent selectivity for Fe2+ ion. پرونده مقاله -
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15 - A model for modified electrode with carbon nanotube composites using percolation theory in fractal space
H. Baheri H. AghaieWe introduce a model for prediction the behavior of electrodes which modified withcarbon nanotubes in a polymer medium. These kinds of polymer composites aredeveloped in recent years, and experimental data for its percolation threshold isavailable. We construct a model چکیده کاملWe introduce a model for prediction the behavior of electrodes which modified withcarbon nanotubes in a polymer medium. These kinds of polymer composites aredeveloped in recent years, and experimental data for its percolation threshold isavailable. We construct a model based on percolation theory and fractal dimensionsand using experimental percolation threshold for calculating the moments of currentdistribution function. پرونده مقاله -
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16 - Selective Membrane Electrode for Bromide Ion Based on Aza Pyrilium Ion Derivative as a new Ionophore.
Hossein Aghaie Karim Zare Ali Reza Abedin Mehran AghaieA highly selective electrode for Bromide ion based on aza pyrilium derivative as an excellentionophore is described.The sensor exhibits a good linear response with a slope of ( 60±1 ) mV per decadeover the concentration range of ( 1×10-3 9×10-6 M ) , چکیده کاملA highly selective electrode for Bromide ion based on aza pyrilium derivative as an excellentionophore is described.The sensor exhibits a good linear response with a slope of ( 60±1 ) mV per decadeover the concentration range of ( 1×10-3 9×10-6 M ) , and a detection limit of ( 3×10-6 M ) of Bromideions .The electrode response is independent of pH in the range of(4.0 9.5).Selectivity coefficientsdetermined by the matched potential method ( MPM ) . Indicate that the interference from inorganic andorganic anions is negligible. The proposed sensor shows a fast response time of approximately (20 s).Ithas been used as an indicator electrode in titration of Bromide with Ag +. پرونده مقاله -
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17 - Preparation and Application of Al3+ - Sensor Based On (2Z) — Methyl 2 — ((z) (p-tolylimino) -3-Ethyl —4-0xothiazolidin —5— Ylidene Acetate in PVC Matrix
J. Mofidi A. Islamnezhad F. Pour HojatAl3+-Potentiometric sensor, based on (2Z) -methyl 2- ((z) (p-tolylimino)-3-ethyl -4-oxothiazolidin -5- ylidene) Acetate (MTEOY) as a neutral ionophore, was successfully developed for the detectionof Al3+ in aqueous solutions. The electrode responds to Al3+ ion with a se چکیده کاملAl3+-Potentiometric sensor, based on (2Z) -methyl 2- ((z) (p-tolylimino)-3-ethyl -4-oxothiazolidin -5- ylidene) Acetate (MTEOY) as a neutral ionophore, was successfully developed for the detectionof Al3+ in aqueous solutions. The electrode responds to Al3+ ion with a sensitivity of 19.8 ± 0.1 mV/decade over the range 1.0 x 10-8- 1.0 x 10-1 mol LT' and in a pH range of 3.0-9.0. The electrodeshows a detection limit of 3.5 x 10 mo1 U'. The influence of membrane composition, the pH of thetest solution, and the interfering ions on the electrode performance was investigated. The proposedelectrode shows good discrimination of Al3+ ion from several cations. The effect of temperature onthe electrode response shows that the temperature higher than 50 °C deteriorates the electrodeperformance. The electrode was found to work well under laboratory conditions. This sensor not onlywas used in determination of AV. i n real samples but also was used to determination of Ali'concentration in the presence of certain interfering ions. پرونده مقاله -
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18 - N-phenylaza-15-crown-5 as Ionophore in PVC-Matrix for Fe2+ - Selective Sensor
M. Aghaie M. Giahi H. Aghaie M. PournaghdyThe preparation of polymer membrane selective to Iron(II) ion and its application to ion-selectiveelectrode is reported here. PVC membrane contains Ironselective N-phenylaza-15-crown-5 asionophore. The membrane electrode is highly selective to Iron(II) ion and exhibit g چکیده کاملThe preparation of polymer membrane selective to Iron(II) ion and its application to ion-selectiveelectrode is reported here. PVC membrane contains Ironselective N-phenylaza-15-crown-5 asionophore. The membrane electrode is highly selective to Iron(II) ion and exhibit good linearresponse over a wide concentration range of 1.0 × 10-2 to 1.0 × 10-6 M with Nernstian slope of29.2 ± 0.6 mV per decade. The detection limit of electrode is 2.5×10-6 M. It has a response time of<15 s and can be used for more than 2 months without any measurable divergence in potential.The proposed sensor shows fairly a good discriminating ability towards Fe2+ ion in comparison tosome hard and soft metals. The electrode was applied to the determination of Fe2+ ions in theferrous sulfate syrup. پرونده مقاله -
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19 - Chromium (III) ion selective electrode based on di(benzylamino)glyoxime
M. Kia H. Aghaie M. Arvand K. Zare M. AghaieA new poly(vinylchloride) membrane sensor for Cr3+ ions based on di (benzylamino)glyoxime asan ionophore was prepared. The electrode has a linear dynamic range 1×10-6-1×10-1 mol l-1,with aNernstian slope of 20.3 ± 0.5 mV per decade and a detection lim چکیده کاملA new poly(vinylchloride) membrane sensor for Cr3+ ions based on di (benzylamino)glyoxime asan ionophore was prepared. The electrode has a linear dynamic range 1×10-6-1×10-1 mol l-1,with aNernstian slope of 20.3 ± 0.5 mV per decade and a detection limit of 2×10-7. It has a fast responsetime of <15 s and can be used for at least 3 months without any considerable divergence inpotential. The proposed electrode revealed good sensitivity for Cr(III) over a wide variety of metalions and could be used in a pH range of 2-5.5. The proposed sensor was used for the determinationof Cr3+ ions in real samples such as tea leaves, coffee and cacao powder by direct potentiometry. پرونده مقاله -
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20 - Cu(II) Ion- Selective Membrane Electrode Based on bis(N-salicylidene-3,3'-diamino diphenyl) sulfone
M. Aghaie M. H. Fekri M. Giahi E. Baghdar S. FarhadiIn order to study the Cu(II) ion selective electrode, an optimized membrane was prepared by mixing of 30 mg of PVC powdered, 5 mg of considered ionophore, 60 mg of plasticizer and 5 mg of additive. The sensor showed a near Nernstian response for Cu(II) ions over a conce چکیده کاملIn order to study the Cu(II) ion selective electrode, an optimized membrane was prepared by mixing of 30 mg of PVC powdered, 5 mg of considered ionophore, 60 mg of plasticizer and 5 mg of additive. The sensor showed a near Nernstian response for Cu(II) ions over a concentration range from 1.0×0-6 1.0×0-2 M with a slope of 28.90.5 mV per concentration decade with a working pH range of 3.5-6.3. The limit of detection was 1.010-6 M. The response time of the electrode is about 15s and can be used for more than 2 month without any divergence in potential. The proposed sensor showed fairly a good discriminating ability towards Cu(II) ion in comparison to other ions. The practical application of the electrode was tested by using it as an indicator electrode to determine the end point in the potentiometric titration of Cu(II) with EDTA solution. پرونده مقاله -
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21 - (1E,2E) -bis (2-aminophenyl) N'1,N'2-dihydroxyethane bis (imidothioate) as a neutral carrier in ion-selective electrode for Ni(II) and it computational studies
M. H. Fekri M. DarvishpourA PVC membrane Ni(II) ion selective electrode has been constructed using (1E,2E)-bis(2-aminophenyl)N'1,N'2-dihydroxyethanebis as membrane carrier. The electrode exhibited a goodpotentiometric response for Ni(II) over a wide concentration range 1.0×10-4 to 1.0&time چکیده کاملA PVC membrane Ni(II) ion selective electrode has been constructed using (1E,2E)-bis(2-aminophenyl)N'1,N'2-dihydroxyethanebis as membrane carrier. The electrode exhibited a goodpotentiometric response for Ni(II) over a wide concentration range 1.0×10-4 to 1.0×10-1M with aslope of 29.4±0.5 mV/decade a and a working pH range of 6.5-9.0. It had a fast response time of≤20s. The best performance was observed with the membrane having 30.5% PVC, 3.0% ligand,61.0% acetophenone and 5.5% oleic acid composition.In this work, the ligand structure studied by ab initio HF calculations using a standard 6-31G* basisset and LanL2DZ. پرونده مقاله -
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22 - Application of a New Macrocyclic -PVC Electrode to Potentiometric Studies of Fe(III) Ion
R. Aminameli M. H. Fekri H. Shafie M. Darvishpour H. KhanmohammadiA PVC membrane Fe(III) ion selective electrode has been constructed using a new macrocyclic asmembrane carrier.The electrode exhibits a good potentiometric response for Fe(III) over a wideconcentration range 1.0×10-4 to 1.0×10-1M with a slope 19.4±0.5 چکیده کاملA PVC membrane Fe(III) ion selective electrode has been constructed using a new macrocyclic asmembrane carrier.The electrode exhibits a good potentiometric response for Fe(III) over a wideconcentration range 1.0×10-4 to 1.0×10-1M with a slope 19.4±0.5 mV/decade a and a working pHrange of 6.5-9.0. It has a fast response time ≤30s.The best performance was observed with themembrance having the 30.5% PVC,3.0% ligand, 61.0% acetophenone and 5.5% oleic acidcomposition. پرونده مقاله -
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23 - مقایسه اثر پلاسمای تخلیه سد دی الکتریک و پلاسما جت در ترمیم با فت تاندون
مریم امینی مهدی مومنی علیرضا جهاندیدههدف از این تحقیق مقایسه اثر پلاسما جت و پلاسمای تخلیه سد دی الکتریک بر روی ترمیم بافت تاندون می باشد. پارگی تاندون آشیل شایع است و در دهه اخیر بسیار افزایش پیدا کرده است از آنجا که ترمیم این نوع آسیب ها کند صورت می گیرد استفاده از روش های نوین مثل پلاسمای سرد امری ضروری چکیده کاملهدف از این تحقیق مقایسه اثر پلاسما جت و پلاسمای تخلیه سد دی الکتریک بر روی ترمیم بافت تاندون می باشد. پارگی تاندون آشیل شایع است و در دهه اخیر بسیار افزایش پیدا کرده است از آنجا که ترمیم این نوع آسیب ها کند صورت می گیرد استفاده از روش های نوین مثل پلاسمای سرد امری ضروری می باشد. پلاسماها را میتوان برحسب پیکربندی و گاز کاری طبقهبندی کرد. با توجه به این طبقه بندی پلاسما جت و پلاسمای تخلیه سد دی الکتریک دوگونه مهم پلاسما هستند که نقش مهمی در درمان ایفا کرده اند. در دو نوع پلاسما فاکتورهای ولتاژ و نوع الکترود در میزان ترمیم موثرند. به منظور دستیابی به بهترین شرایط ترمیم ، هر دونوع پلاسما در ولتاژها 5، 10و 15 کیلو ولت قرار گرفت و سپس الکترودها ی مس، استیل و روی را در هر دونوع پلاسما تعبیه شد. فاکتورهایی مانند طول ، طیف گسیلی ، دما و چگالی ، جریان محاسبه شد و دوزهای استاندارد بر روی بافت تابانده شد. نتایج نشان دادند روند ترمیم در هر دو پلاسما به یک صورت می باشد ولی میزان بهبودی متفاوت است. پلاسمای تخلیه سد دی الکتریک کاراتر از پلاسما جت می باشد. بیشترین میزان ترمیم در پلاسمای تخلیه سد دی الکتریک با ولتاژ اعمالی 15 کیلو ولت و با الکترود مس مشاهده شد که طیف نشری پلاسما نشان می دهد پیک های جدید اکسیژن و نیتروژن در این پلاسما وجود دارد که در دیگر ولتاژها و الکترودها این پیک ها یافت نشد. پرونده مقاله -
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24 - بررسی تأثیر فرآیند الکتروکینتیک به همراه آبشویی بر کیفیت زهآب در اصلاح یک خاک شور-سدیمی
محمد علی غلامی سفیدکوهی میثم رمضانی میر خالق ضیاء تبار احمدیشوری آب و خاک موضوعی است که به دلیل اهمیت آن در بسیاری از کشورها از آن به عنوان"مرگ سفید "یاد میشود. الکتروکینتیک یک روش فیزیکی برای استخراج نمکها اعم از ترکیبات شیمیایی آلی و معدنی از خاک میباشد. در این مطالعه الکترودها بهصورت افقی و به همراه فرآیند آبشویی در اصلاح چکیده کاملشوری آب و خاک موضوعی است که به دلیل اهمیت آن در بسیاری از کشورها از آن به عنوان"مرگ سفید "یاد میشود. الکتروکینتیک یک روش فیزیکی برای استخراج نمکها اعم از ترکیبات شیمیایی آلی و معدنی از خاک میباشد. در این مطالعه الکترودها بهصورت افقی و به همراه فرآیند آبشویی در اصلاح الکتروکینتیکی یک خاک شور-سدیمی استفاده شدند. بدین منظور الکترودهایی از جنس آلومینیوم مشبک شده و به عنوان آند و کاتد به ترتیب در بالا و پایین ستونهای خاک با چهار ارتفاع ۱۰، ۲۰، ۳۰ و ۴۵ سانتیمتر قرار گرفتند. سپس آبی معادل چهار برابر آب منفذی و با تناوب ۳۰ میلیمتر از بالای نمونهها وارد خاک شده و خصوصیات زهآب خروجی اندازهگیری و مورد تجزیهوتحلیل قرار گرفت. همچنین فرآیند آبشویی در هر یک از ارتفاعها به عنوان شاهد و بدون اعمال روش الکتروکینتیک انجام شد. نتایج نشان داد که در تیمارهای الکتروکینتیک هدایت الکتریکی لحظهای زهآب و شدتجریان الکتریکی عبور کرده از خاک بهصورت افزایشی-کاهشی تغییر کردهاند. همچنین اسیدیته زهآب خروجی نسبت به شاهد افزایش داشته و بین ۸/۶ تا ۹ متغیر بوده و دمای آن بین ۲۳ تا ۳۵ درجه سانتیگراد تغییر کرده است. اعمال جریان الکتریکی خروج کاتیونها را بهطور معنیداری (۰۵/۰p<) افزایش داده است (۲۵ درصد) و خروج آنیونها را به مقدار کمی (۲ درصد) کاهش داده است. همچنین فرایند الکتروکینتیک، نسبت خروج یون سدیم را به دو یون کلسیم و منیزیم بهطور متوسط ۵/۸ درصد در مقایسه با تیمارهای شاهد افزایش داده است. پرونده مقاله -
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25 - The Electrochemical Sensor for Selective Solid Phase Extraction of Pseudoephedrine Hydrochloride in a Real Sample
Morteza Omidinejad Mohammad Alimoradi Majid Ramezani Sattar EbrahimiIn the current study, a new technique was developed for quantification and qualification of pseudoephedrine hydrochloride (PSE) in a real sample, which was based on electrochemical sensors and molecular imprinted polymer (MIP). The carbon paste electrode (CPE) was modif چکیده کاملIn the current study, a new technique was developed for quantification and qualification of pseudoephedrine hydrochloride (PSE) in a real sample, which was based on electrochemical sensors and molecular imprinted polymer (MIP). The carbon paste electrode (CPE) was modified and optimized by a different ratio of MIP. MIP/CPE was used as the extraction and working electrode. Differential pulse voltammetry (DPV) method was utilized for measurement. The MIP (molecularly imprinted polymer) and NIP (non-imprinted polymer) were synthesized by various ratios of functional monomer (methacrylic acid) and cross-linker (ethylene glycol dimethacrylate) and template (pseudoephedrine hydrochloride). Some parameters such as pH, extraction time, MIP/CP ratio, stirring rate, and concentration of sample were optimized, and under these conditions, the oxidation peak current was proportional to the pseudoephedrine hydrochloride concentration over a range of 10-500 µM with the coefficient of determination 0.992 (R2). The limit of detection (LOD) was found about 0.274 µM and the limit of quantification (LOQ) was located about 0.825 µM. The relative standard deviation (RSD) was about 1.17%. The results indicated that the modified electrode had a specific ability in selective extraction of pseudoephedrine hydrochloride. پرونده مقاله -
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26 - Determination of Cobalt(II) by a New PVC Membrane Coated Graphite Electrode Based on 6-chloro-11- azabenzo[a]phenothiazin-5-one as a neutral ion carrier
Mohammad Reza Jalali Sarvestani Roya AhmadiCobalt has great biological effects on human beings and also other living organisms, hence its determination is very important. In this regard, a novel coated graphite electrode was designed for determination of Co2+ ions by exploiting 6-chloro-11- azabenzo[a]phenothiaz چکیده کاملCobalt has great biological effects on human beings and also other living organisms, hence its determination is very important. In this regard, a novel coated graphite electrode was designed for determination of Co2+ ions by exploiting 6-chloro-11- azabenzo[a]phenothiazin-5-one as a neutral ion carrier, for the first time. The foremost function was witnessed from the membrane composition of PVC (29%), Potassium tetrakis (4-chlorophenyl) borate (2%) as an ionic additive,6-chloro-11-azabenzo[a]phenothiazin-5-one (9%) as ionophore and Dioctylphthalate (60%) as Plasticizer. The linearity domain of the membrane sensor was from 5×10-7 to 1×10-2 Mol L-1 with the Nernstian slope value of 30.1 mV.Decade-1. The potential response of the designed electrode was also investigated in non-aqueous mediums and it was found out that the electrode is also able to be used in systems that are entailed of 20% of ethanol and acetone organic solvents. The response time and lifespan of the electrode was 5 S and 3 months respectively. The sensor selectivity was also evaluated by match potential method over other cations and it shows an eminent selectivity towards Co2+ over all of the inspected ions. The applicability of the electrode in the potentiometric titration with EDTA was also investigated. In the end, the proposed electrode was utilized for determination of Co2+ in four aqueous specimens as real samples. پرونده مقاله -
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27 - DNA Biosensor for Determination of 5-Fluorouracil based on Gold Electrode Modified with Au and Polyaniline Nanoparticles and FFT Square Wave Voltammetry
Parviz Norouzi Mohammad Amin Eshraghi Mehrnaz EbrahimiIn the present study, a new biosensor for 5-Fluorouracil was described using modified goldelectrode and Fast Fourier transform square wave voltammetry (FFT SWV). Calf thymus DNAimmobilization was on a gold electrode decorated with polyaniline and gold nanoparticles. The چکیده کاملIn the present study, a new biosensor for 5-Fluorouracil was described using modified goldelectrode and Fast Fourier transform square wave voltammetry (FFT SWV). Calf thymus DNAimmobilization was on a gold electrode decorated with polyaniline and gold nanoparticles. Theelectrochemical characteristics of the electrodes were investigated by cyclic voltammetry, andelectrochemical impedance spectroscopy. After interaction DNA with the analyte, a dramaticdecline in [Fe(CN)6]/[Fe(CN)6]]3-/4- signal was observed which could be used as the signal. Theimportant parameters of the detection system, such as, pH were optimized. The linear dynamicrange of the biosensor was1×10-9 to 1×10-6 M (r2=0.996) limits of detection of2.5×10−10 M. In addition to the wide linear range response, the proposed method demonstratedacceptable sensitivity, repeatability and long-term stability. Future experiments could be performedto examine several other effective factors so as to decrease the influence of the environment andinvestigate its application to FFTSWV detection. پرونده مقاله -
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28 - Electroanalytical Sensor Based on Molecularly Imprinted Polymer-Modified Screen- Printed Carbon Electrode for the Determination of Thyroxine
Solmaz KiaA susceptible voltammetric sensor for thyroxine is designed and generated by electropolymerization of molecularly imprinted polymer (MIP). Thyroxine selective molecularly imprinted polymer is synthesized by electropolymerization of the p-phenylenediamine‒resorcinol mixt چکیده کاملA susceptible voltammetric sensor for thyroxine is designed and generated by electropolymerization of molecularly imprinted polymer (MIP). Thyroxine selective molecularly imprinted polymer is synthesized by electropolymerization of the p-phenylenediamine‒resorcinol mixture directly on the screen-printed carbon electrode (SPCE) surface in the presence of the thyroxine molecules. Electropolymerization of monomers deposited a film on the electrode surface which blocked ferricyanide reduction. Elimination of the Thyroxine forms the cavities which caused a remarkably improved ferricyanide signal which was again blocked after the rebinding of thyroxine. The decrease of the ferricyanide peak of the MIP electrode depended linearly on the thyroxine concentration. Various factors affecting the current response of the electrode were studied and optimized. This sensor shows a linear response range of 1 × 10-8- 2 × 10-6M and a lower detection limit of 5 × 10-9 M. The sensor was successfully applied to the detection of thyroxine in human plasma samples. پرونده مقاله -
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29 - Design and preparation of Magnesium (II) selective electrode based on novel synthetic ligand and optimization by D-optimal method
Ahmad Adeli Razieh Sanavi Khoshnood S.Ali Beyramabadi Mehdi Pordel Ali MorsaliaThe utility of carbon as the base material for carbon paste electrodes has been considered for many years. In this work, we were applied MWCNT as a modifier and Schiff base chitosan and 5-nitro isatin as ionophore along with carbon. Prepared CPE shows a Nernstian respon چکیده کاملThe utility of carbon as the base material for carbon paste electrodes has been considered for many years. In this work, we were applied MWCNT as a modifier and Schiff base chitosan and 5-nitro isatin as ionophore along with carbon. Prepared CPE shows a Nernstian response of 29.567 mV per decade in a wide linear dynamic range of 1.0 × 10-5 to 1.0 ×10-1 M for Mg2+ ion. The optimization process had performed by Mixture design in design expert software. This present sensor has a short time of response of about 10 s. The applicable pH range was obtained 3.51-9.0 and Detection limit was calculated 1.4 ×10-5 M. Lastly, the prepared sensor was used in the indirect potentiometry (potentiometric titration) as an indicator or working electrode. The data obtained from the experiments showed that the electrode is usable in analytical applications. پرونده مقاله -
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30 - A Simple and an Effective Catalyst for Determination of Cefixime in Real Samples Using of Modified Carbon Paste Electrode with Cobalt Impregnated Zeolite
Samaneh Tajjedin Banafsheh NorouziCarbon paste electrode modified with cobalt impregnated zeolite was prepared by mixing of cobalt_zeolite (Co_Z) and graphite powder with different percent. The electrochemical oxidation of cefixime at such electrodes was investigated using the cyclic voltammetric and am چکیده کاملCarbon paste electrode modified with cobalt impregnated zeolite was prepared by mixing of cobalt_zeolite (Co_Z) and graphite powder with different percent. The electrochemical oxidation of cefixime at such electrodes was investigated using the cyclic voltammetric and amperometric techniques. It is not electrochemically active towards cefixime oxidation in 0.1 M phosphate buffer solution (pH=7) on a carbon paste electrode modified with zeolite. The presence of cobalt ions in the zeolite matrix, by soaking the electrode in an aqueous Co(NO3)2 solution, markedly enhances the electrocatalytic activity which was found to depend on the cobalt content. However, the electrocatalytic activity depends on different percent of Co_Z. Under the selected conditions, the anodic peak current was linearly dependent on the concentration of cefixime in the range 0.003–8 mM with the cyclic voltammetric method. The detection limit (S/N=3) was also estimated to be 2.98 μM. Finally, this method was applied for the determination of cefixime in tablet samples. پرونده مقاله -
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31 - High-Sensitive and Selective Liquid Membrane Electrode for Direct Determination of Trace Amounts of Chromium
Leila Hajiaghababaei Saeid Takalou Forogh AdhamiN-(2H-[1,2,4]thiadiazolo[2,3-a]pyridine-2-ylidene)benzamide was used as a selective sensing material in the PVC membrane to construction of a new chromium ion selective electrode. This liquid membrane electrode worked well with a Nernstian response of 19.7 ±0.4 m چکیده کاملN-(2H-[1,2,4]thiadiazolo[2,3-a]pyridine-2-ylidene)benzamide was used as a selective sensing material in the PVC membrane to construction of a new chromium ion selective electrode. This liquid membrane electrode worked well with a Nernstian response of 19.7 ±0.4 mV decade-1 of Cr(III) in a wide dynamic concentration range of 8.0× 10-6-1.0×10-1 M. The electrode had relatively short response time (about 5 s), and it was found to produce stable responses for more than 60 days. The effects of some factors such as internal solution, pH, life time and selectivity were investigated. The electrode has a useful working pH range of 3.5–8. Selectivity coefficients determined with match potential method. The selectivity coefficients indicate high selectivity towards Cr(III) ions. The practical utility of the Cr(III) ion sensor has been demonstrated by using it as an indicator electrode in potentiometric titration of Cr(III) with EDTA and for direct determination of Cr(III) in tea and Cocoa powder samples. پرونده مقاله -
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32 - Electerocoagulation of Blue and Mixed Azo Dyes and Application in Treating Simulated Textile Effluent
Elham Keshmirizadeh R. KhosraviThis study investigated the efficiency of electerocoagulation (EC) in removing color from synthetic and simulated textile wastewater. The study on decolorization of mixed dyes is a step toward an effective treatment of textile wastewater. Two representative reactive dye چکیده کاملThis study investigated the efficiency of electerocoagulation (EC) in removing color from synthetic and simulated textile wastewater. The study on decolorization of mixed dyes is a step toward an effective treatment of textile wastewater. Two representative reactive dye molecules were selected for the synthetic dye wastewater, a blue dye alone and mixed dye (black, blue, red, 1:1:1v/v). The EC technique showed satisfactory color (98 %) and chemical oxygen demand (85%) removal efficiency and reliable performance in treating both individual and mixed dye types. The removal efficiency and energy consumption data showed that, for a given pH and optimum current density:100A/m2, Fe or Al were used in treating the dyes with an initial concentration of 100-1200 mg/L, the energy cost in achieving above 98% color removal was on order of 0.73-1.27kWh/m3 wastewater in all systems, water recovery was 0.97. It was found that the operating parameters used for the synthetic dye wastewater were less effective for treatment of simulated textile wastewater. پرونده مقاله -
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33 - Color Removal from Simulated Textile Effluents Using Clean Electrocoagulation Technique
Elham Keshmirizadeh Roya Khosravi Sabereh MahdifarThe present work was directed toward the successful ability of electerocoagulation to remove color from synthetic and simulated textile effluent by aluminum/iron electrodes. Two representative reactive dyes were selected for the synthetic dye system, a black dye alone a چکیده کاملThe present work was directed toward the successful ability of electerocoagulation to remove color from synthetic and simulated textile effluent by aluminum/iron electrodes. Two representative reactive dyes were selected for the synthetic dye system, a black dye alone and mixed dye (black, blue, red, 1:1:1 vol/vol). Several important operating parameters such as electrode material, initial pH(3-9), current density(60-120 A/m2 ), operating time (6-40), initial dye concentration (100-1200 mg/L) and solution conductivity (applied conductivity is better than literature) were studied in an attempt to reach higher color removal efficiency (%98). The chemical oxygen demand decreased by more than %87. The results of this work are comparable with those of recent studies. The electrical energy consumption in the above conditions was on order of 1.2-3.2 kWh/m3 of wastewater and the water recovery was 0.97m3 /m3 of wastewater, in this research “water recovery” was introduced and calculated in order to show the more economically feasible recycling of treated water. However the operating parameters used for the synthetic dye were less effective for treatment of simulated textile wastewater. پرونده مقاله -
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34 - Mesalazine Modified Carbon Paste Electrode for Voltammetric Determination of Amlodipine
Mahzad Firouzi Mostafa NajafiIn this study, Mesalazine modified carbon paste electrode (MESA-CPE) was developed and utilized to investigate the electrochemical behavior and determination of amlodipine (AML).The electroanalytical responses were evaluated by cyclic voltammetry, chronoamperometry and چکیده کاملIn this study, Mesalazine modified carbon paste electrode (MESA-CPE) was developed and utilized to investigate the electrochemical behavior and determination of amlodipine (AML).The electroanalytical responses were evaluated by cyclic voltammetry, chronoamperometry and differential pulse voltammetry. The MESA/CPE showed good electrocatalytic activity with respect to the electrooxidation of AML with an over potential of 200 mV lower than that of the bare CPE. The sensor showed two linear dynamic ranges from 1.0 to 20.0 µM and 20.0 to 100.0 µM with a detection limit of 0.4 µM (S/N = 5). The MESA-CPE was applied for the determination of AML in some pharmaceutical formulations. پرونده مقاله -
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35 - Voltammetric Investigation of Thioridazine Using a Carbon Nanocomposite Electrode in Human Biological Samples
Elham Eslami Fatemeh FarjamiAn electrochemical method employing a carbon nanocomposite electrode was developed to measure thioridazine. The electrode has been designed by incorporation of montmorillonite nanoclay into the carbon ionic liquid electrode. Surface morphology of the electrodes was d چکیده کاملAn electrochemical method employing a carbon nanocomposite electrode was developed to measure thioridazine. The electrode has been designed by incorporation of montmorillonite nanoclay into the carbon ionic liquid electrode. Surface morphology of the electrodes was done using scanning electron microscopy. Adsorptive stripping voltammetry was applied as a very sensitive analytical method for the determination of sub-micromolar amounts of thioridazine. The optimized linear working range and detection limit (S/N=3) are 0.1-50 μM and 21nM, respectively. The nanocomposite electrode demonstrates several advantages such as simple preparation method, excellent activity in physiological conditions, low detection limit, long-term stability, and remarkable voltammetric reproducibility. As a result, it can find promising applications in blood serum and urine samples. پرونده مقاله -
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36 - Removal of Reactive Red 24 Dye by Clean Electrocoagulation Process using Iron and Aluminum Electrodes
Nasser M. Abu Ghalwa Alaa M. Saqer Nader B. FarhatIn this research, the efficiency of electrocoagulation treatment process using iron and aluminum electrodes to treat synthetic wastewater containing Reactive Red 24 (RR 24) was studied. The effects of parameters such as current density, pH, type of electrolyte, initial چکیده کاملIn this research, the efficiency of electrocoagulation treatment process using iron and aluminum electrodes to treat synthetic wastewater containing Reactive Red 24 (RR 24) was studied. The effects of parameters such as current density, pH, type of electrolyte, initial dye concentration, electrolyte concentration, temperature, and inter electrode distance on dye removal efficiency were investigated. The results showed that dye and chemical oxygen demand removals were 99.6% and 91.5% by using iron and were 97.9% and 83.8%, by using aluminum electrodes. The removal of dye exhibited pseudo first order with good correlation coefficients (0.955 and 0.990 for Fe and Al electrodes respectively. It can be concluded that electrocoagulation process by Iron electrode is very efficient and clean process for reactive dye removal from colored wastewater. پرونده مقاله -
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37 - Effect of Formaldehyde on Pulsed Electro-Plated Nickel-Alumina Nanocomposite Coatings
S Mirzamohammadi M Velashjerdi A AnbarzadehMetal-based nanocomposite coating prepared by plating method can exhibit unique mechanical, chemical, and physical features which have led to their extensive application in various high-tech industries. Nickel-based nanocomposite coatings can pose far lower pollution to چکیده کاملMetal-based nanocomposite coating prepared by plating method can exhibit unique mechanical, chemical, and physical features which have led to their extensive application in various high-tech industries. Nickel-based nanocomposite coatings can pose far lower pollution toward the environment and related staff as compared with chromium-based ones. In this research, a novel compound was developed to coat nickel-alumina nanocomposite by adding formaldehyde to the plating bath. The concentration of alumina nanoparticles (NPs) in the plating bath was 10 g/L. The nickel-alumina nanocomposite coatings were prepared by a pulsed electrical current under ultrasound turbulence in the plating bath. Two Ni bathes in combination with Watt’s compound were used with and without formaldehyde addition. Before plating, the zeta potential of alumina NPs was measured in the two different baths. After plating, the cross-section of the coatings and the alumina content participated in the coating, as well as the coating morphology, were analyzed by scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX). Based on the results, incorporation of formaldehyde into the Watt’s solution increased the zeta potential of the nanoparticles from -4.1 to +30.5 mV; consequently, the nanoparticle content of the coatings enhanced from 4.6 to 8.5 vol.%. پرونده مقاله -
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38 - Produce of Biodegradable Porous Mg-Zn Scaffold via Powder Metallurgy and Coated with Nano HAP Synthesized by Electrodeposition Process
Z.S. Seyedraoufi Sh. MirdamadiMg is considered promising degradable material for tissue engineering applications because of good biocompatibility, corrosion and mechanical properties. In the present work, biodegradable porous Mg-1 wt% Zn scaffold was produced by powder metallurgical process and then چکیده کاملMg is considered promising degradable material for tissue engineering applications because of good biocompatibility, corrosion and mechanical properties. In the present work, biodegradable porous Mg-1 wt% Zn scaffold was produced by powder metallurgical process and then nano hydroxyapatite (HAP) coating with composition of Ca10(PO4)6(OH)2 on the scaffold was synthesized by pulse electrodeposition and alkali treatment processes to increase the corrosion resistance of the substrate. The results showed that the as-deposited coating consists of HAP, CaHPO4.2H2O (DCPD) and Ca8H2(PO4)6.5H2O (OCP) with plate-like and needle-like morphologies and the post-treated coating was composed of needle-like structure of nano HAP developed almost perpendicularly to the substrate .Electrochemical tests indicated that the corrosion current density reduced from2.731×10-3 to 4.98×10-5 A.cm-2 and the corrosion potential of scaffold increased from -1.451 to -1.37 V. This study revealed that electrodeposition of HA coating is a useful approach to improve the corrosion resistance of porous Mg-Zn scaffold in SBF and to develop Mg-based degradable implants. پرونده مقاله -
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39 - Effect of the Number of Welding Passes on the Microstructure and Wear Behavior of St52 Plain Carbon Steel Coated with a High Chromium-Carbon Electrode
Mohsen Barmaki Kamran Amini Farhad GharaviThis study investigated the effect of the number of welding passes on the microstructure, hardness, and wear behavior of St52 plain carbon steel coated with an E10-UM-60R electrode in accordance with the DIN 8555 standard using SMAW method. An optical microscope (OM) an چکیده کاملThis study investigated the effect of the number of welding passes on the microstructure, hardness, and wear behavior of St52 plain carbon steel coated with an E10-UM-60R electrode in accordance with the DIN 8555 standard using SMAW method. An optical microscope (OM) and a scanning electron microscope (SEM) were used, and an EDS analysis was carried out to examine the microstructure. The Vickers micro hardness test and a reciprocating wear test were also used to examine the hardness and wear resistance. The results showed that the structure on the surface of the coated specimens is consisted of M7C3 carbides in the eutectic field (). In addition, the volume fraction of carbides increased in specimens that underwent two passes of welding relative to that in one pass-welded specimen. The reason for this was related to the decreased dilution of iron and increased dilution of chromium in the two-pass welded specimen and an increase in the volume fraction of M7C3 carbides. The increased percentage of carbides in the two-pass welded specimen increased the hardness and consequently the wear resistance relative to those in the one-pass welded specimen in a way that the surface hardness and weight loss in the wear test reached from 780 HV and 3.7 mg in the one-pass welded specimen to 910 HV and 2.5 mg in the two-pass welded specimen. Moreover, examining the wear surfaces indicated the occurrence of an adhesive wear mechanism in the specimens in a way that the adhesive wear rate decreased in the two-pass welded specimens. پرونده مقاله -
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40 - Investigation of the TiO2/SiC/SiO2 Coating Effect On the Wear Rate of Needle Graphite Electrode by using Electrical Discharge Machining
Hossein Alian Moghadam majid jabbari Saeed Daneshmand Saeid Rasouli Jazi Arezoo KhosraviNeedle graphite electrodes are one of the main parts used in electric arc furnaces. These electrodes have a significant impact on melt quality and product quality, and their consumption is one of the most important parameters of steel production cost in EAF furnaces. Th چکیده کاملNeedle graphite electrodes are one of the main parts used in electric arc furnaces. These electrodes have a significant impact on melt quality and product quality, and their consumption is one of the most important parameters of steel production cost in EAF furnaces. Therefore, reducing the consumption of needle graphite electrodes in these furnaces is very important. The main reasons for continuous use of needle graphite electrodes in arc furnaces are oxidation of the sidewalls and sublimation of their tips, and many solutions have been proposed to reduce them. In the present study, the effect of coating consisting of TiO2/SiC/SiO2 elements on the wear rate of the needle graphite electrode in the sublimation state is investigated using EDM (Electrical Discharge Machining- Spark device). For this purpose, the effect of voltage, current, pulse on time and pulse off time on the electrode wear rate are investigated and in this regard, Taguchi design method has been used to reduce the number of experiments. Based on the test results, TiO2/SiC/SiO2 coating reduces the wear rate of the needle graphite electrode due to sublimation. پرونده مقاله -
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41 - Investigating the effect of graphite electrodes structures on the synthesized graphene using electrochemistry method
Zahra Mehrvar Mohammad Ali Kiani Hani SayahiIn this study, a simple and efficient approach is reported to product graphene using electrochemical exfoliation of graphite electrodes, in acidic solutions. The electrolyte concentration, applied voltages, electrodes distance and preparation time were taken as control چکیده کاملIn this study, a simple and efficient approach is reported to product graphene using electrochemical exfoliation of graphite electrodes, in acidic solutions. The electrolyte concentration, applied voltages, electrodes distance and preparation time were taken as control parameters to optimize the produced graphene structures. The optimized graphene sample was prepared in a H2SO4 (0.5 M) at a bias of +10 V. The interlayer spaces, crystallite size and the average number of layers were determined by XRD. Surface morphology, layer thickness and characteristics of obtained samples were investigated by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and FTIR. The obtained results confirmed the graphene structures. پرونده مقاله -
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42 - A novel Sensor for Determination of Ascorbic Acid Based on Modified Carbon Paste Electrode
Sakineh BahmaniIn this study a new method for electrocatalytic oxidation and determination of ascorbic acid (AA) was developed. The proposed electrode was a zeolite-modified carbon paste electrode, which was doped with Ni (II) ions (Ni2+Y/ZMCPE). Ni (II) ions were doped in Y-zeolite f چکیده کاملIn this study a new method for electrocatalytic oxidation and determination of ascorbic acid (AA) was developed. The proposed electrode was a zeolite-modified carbon paste electrode, which was doped with Ni (II) ions (Ni2+Y/ZMCPE). Ni (II) ions were doped in Y-zeolite framework by ion-exchange mechanism and actd as catalyst to oxidize ascorbic acid. Then, electrocatalytic oxidation of ascorbic acid, using cyclic voltammetry and chronoamperometry techniques was investigated. The diffusion coefficient and current density of ascorbic acid were calculated as 1.491×10-4 cm2 s−1 and 5.17×103 respectively. A linear dynamic range for determination of ascorbic acid and detection limit using proposed modified electrode were 0.02– 4.10 mmolL−1 and 2.8×10−6mol L−1 respectively. پرونده مقاله -
دسترسی آزاد مقاله
43 - Calcium measurement using ion selective electrode based on a benzo-18-crown-6 as an ionophore
Shaghayegh Lovineh Arezoo GhaemiA new PVC based membrane using benzo-18-crown-6 as an ionophore has been developed as a calcium ion selective electrode. The electrode comprises of ionophore (4%), PVC (30%) and plasticizer (63%). The electrode shows a linear dynamic response in the concentration range چکیده کاملA new PVC based membrane using benzo-18-crown-6 as an ionophore has been developed as a calcium ion selective electrode. The electrode comprises of ionophore (4%), PVC (30%) and plasticizer (63%). The electrode shows a linear dynamic response in the concentration range of 1×10−5 M to 1×10−1 M with a Nernstian slope of 29.8 mV/decade and detection limit is 4.0×10−6 M. The proposed sensor shows reasonably good selectivity with respect to alkali, alkaline earth and transition metal ions. It can be used in the pH range of 5 to 12. The proposed electrode also was applied for the direct determination of Ca2+ cation in doubly distilled deionized water samples spiked with different concentrations of calcium. This electrode was also used for determination of Ca2+ in real samples with a very good recovery. پرونده مقاله -
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44 - مقایسه عملکرد دستگاه الکترود تراش بادی قابل حمل ساخته شده توسط گروه زیر و نمونه خارجی آن
رضا مزینانی زینب بهمن آبادی رضا راه چمنی مهدی مزینانیاین اختراع در ارتباط با دستگاههای جوش نقطهای طراحی شده است، که در صنایع مختلفی از جمله صنایع خودرو سازی کاربرد فراوانی دارد. در جوش نقطهای عملیات جوش کاری توسط الکترودهای از جنس آلیاژ مس انجام میشود که این الکترودها بعد از مدت محدودی کارکردن و تعداد مشخصی نقطه جوش، چکیده کاملاین اختراع در ارتباط با دستگاههای جوش نقطهای طراحی شده است، که در صنایع مختلفی از جمله صنایع خودرو سازی کاربرد فراوانی دارد. در جوش نقطهای عملیات جوش کاری توسط الکترودهای از جنس آلیاژ مس انجام میشود که این الکترودها بعد از مدت محدودی کارکردن و تعداد مشخصی نقطه جوش، پلیسه دار و دفرمه شده و حالت اولیه خود را از دست میدهند. به همین جهت فاقد کارایی لازم بوده و کیفیت اتصال جوشی بشدت افت میکند و در این صورت ایمنی محصول بشدت پایین خواهد آمد. دستگاه الکترود تراش قابل حمل این قابلیت را فراهم میکند بدون اینکه الکترودهای مسی از روی دستگاه نقطه جوش باز شود بصورت In- Line آنها را تراشیده و فرم دهی مجدد نموده. بدین ترتیب علاوه بر تضمین کیفیت و استحکام نقاط جوش، عمر مفید آنها تا 10 برابر افزوده خواهد شد. پرونده مقاله -
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45 - بررسی تجربی تاثیرپارامترهای فرایندجوشکاری مقاومتی برجسته براستحکام پیچشی اتصال مهره به ورق
نصر الله بنی مصطفی عرب امیر علی نقی زاده علی دهقانیجوشکاری امروزه ازمهمترین و رایجترین فرآیندهای اتصال فلزات (وبعضاًغیرفلزات) میباشد. ازمیان فرآیندهای موجودجوشکاری،فرآیند جوشکاری مقاومتی از حرارت و فشار بطور همزمان، برای اتصال قطعات فلزی استفاده می نماید. در این تحقیق ، تاثیر پارامترهای جوش مقاومتی برجسته روی ورق فلزی و چکیده کاملجوشکاری امروزه ازمهمترین و رایجترین فرآیندهای اتصال فلزات (وبعضاًغیرفلزات) میباشد. ازمیان فرآیندهای موجودجوشکاری،فرآیند جوشکاری مقاومتی از حرارت و فشار بطور همزمان، برای اتصال قطعات فلزی استفاده می نماید. در این تحقیق ، تاثیر پارامترهای جوش مقاومتی برجسته روی ورق فلزی و مهره جوش غیر همجنس و با ضخامت مختلف موردبررسی قرار گرفته است. از بین پارامترهای قابل تنظیم در جوش مقاومتی، سه پارامتر زمان جوشکاری، نیروی الکترود و جریان جوشکاری که بیشترین تاثیر را بر روی خواص جوش و کیفیت جوش دارند انتخاب و سایر پارامترها ثابت فرض شده است. به منظور ارزیابی استحکام مهره جوش از آزمون پیچش استفاده شده، و بوسیله گشتاور سنج (ترکمتر) دیجیتال، استحکام پیچشی اندازه گیری شده است. جهت انجام آزمایش ها از نرم افزار16Minitab با روش پاسخ سطح که جز روشهای طراحی آزمایش می باشد استفاده شده و در ادامه نتایج تجربی بدست آمده به کمک نرم افزار فوق، مورد تحلیل قرار گرفته تا تاثیر پارامترهای متغیر ذکر شده بر استحکام پیچشی جوش تعیین گردد. پرونده مقاله -
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46 - ارایه روشی حساس و گزینشپذیر برای اندازهگیری تترا بوتیل بنزوکینون در روغنهای خوراکی
هستی پورمددکار نوید نصیری زاده سعید جعفری محمد دهقانیحضور مقادیر کم ترشری بوتیل هیدروکینون یا محصول متابولیتی آن، تترا بوتیل بنزوکینون (TBQ)، بهدلیل تمایل زیاد به گروههای تیولدار پروتئینها یا دیواره سلولها ممکن است مانع تکثیر سلولی و بروز ناهنجاریهای بیولوژیک شوند. هدف از این پژوهش ساخت یک نانوحسگر الکتروشیمیایی بر چکیده کاملحضور مقادیر کم ترشری بوتیل هیدروکینون یا محصول متابولیتی آن، تترا بوتیل بنزوکینون (TBQ)، بهدلیل تمایل زیاد به گروههای تیولدار پروتئینها یا دیواره سلولها ممکن است مانع تکثیر سلولی و بروز ناهنجاریهای بیولوژیک شوند. هدف از این پژوهش ساخت یک نانوحسگر الکتروشیمیایی برپایه پلیمر قالب مولکولی برای شناسایی TBQ در نمونههای روغن خوراکی میباشد. این مطالعه از نوع متدولوژیک بوده و جامعه آماری شامل نمونههای روغن خوارکی حاوی TBQ است. تأثیر عوامل مختلف نظیر مقدار پلیمر قالب مولکولی و نانولولههای کربنی در ساخت الکترود کربن سرامیکی اصلاح شده و همچنین pH محلول پیش تغلیظ و زمان اقامت نانوحسگر تهیه شده در محلول پیش تغلیظ بر میزان جریان حاصل از اکسایش TBQ براساس روش سطح پاسخ بهینهسازی شد. برای تعیین مقدار TBQ موجود در نمونههای روغن از روش ولتامتری پالس تفاضلی استفاده شده است. مورفولوژی پلیمرهای قالب مولکولی و حسگر تهیه شده با میکروسکوپ الکترونی روبشی تشریح شد. شرایط بهینه برای جداسازی و اندازهگیری TBQ در روغن خوراکی شامل 10 میلیگرم نانولوله کربنی چند دیواره، 30 میلیگرم پلیمر قالب مولکولی برای تهیه الکترود کربن سرامیکی اصلاح شده بهعنوان نانوحسگر و مدت زمان 8 دقیقه در محلول حاوی بافر فسفات 1/0 مولار با 0/10=pH حاصل گردید. روش پیشنهادی قادر به شناسایی TBQ در نمونههای روغن در محدوده غلظتی 680-6 نانومولار با حد تشخیص 1/3 نانومولار میباشد. بر اساس نتایج بهدست آمده، روش پیشنهادی مبتنی بر حسگر تهیه شده میتواند بهعنوان ابزاری مناسب جهت اندازهگیری TBQ در نمونههای روغن خوراکی در صنایع و آزمایشگاههای تخصصی بهکار برده شود. پرونده مقاله -
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47 - The effect of saccharin on microstructure and corrosion behavior of nanocrystalline nickel thin films in alkaline solution
Behrooz Shayegh Nima ZaghianIn this study the effect of crystallite size reduction and microstructure on the electrochemical corrosion behavior of nanocrystalline nickel (NC Ni) were investigated using Tafel polarization and electrochemical impedance spectroscopy (EIS) measurements in 10 wt.% NaOH چکیده کاملIn this study the effect of crystallite size reduction and microstructure on the electrochemical corrosion behavior of nanocrystalline nickel (NC Ni) were investigated using Tafel polarization and electrochemical impedance spectroscopy (EIS) measurements in 10 wt.% NaOH. NC Ni coatings were produced by direct current electrodeposition using chloride baths in presence and absence of saccharin as a grain refining agent. The crystallite size of NC surface coatings was calculated and analyzed by X-ray diffractometry (XRD). Field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) were used to study coatings microstructure. The chemical composition of NC surfaces was determined using X-ray energy dispersive spectroscopy (EDS). Our results showed Saccharin decreased the crystallite size but increased the grain size. In addition, corrosion resistance of NC Ni in presence of saccharin increased, which is ascribed to the formation of more stable and protective film. The behavior of passive film growth and corrosion were discussed. پرونده مقاله -
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48 - Addition of Mo in the Zn based alloy coating in the citrate solution and investigation of its corrosion behavior
Mahdi Omidi Mahdi Yeganeh Arash Etemad Mohammad Reza Rostami Mohammad esmaeil ShafieIn this work, Zn-Co-Mo coatings were electrodeposited on mild steel substrate from a citrate solution at current densities of 5, 7.5 and 10 mA.cm-2 and pH values of 4.5, 5, and 5.5. The coated samples were studied by scanning electron microscope and potentiodynamic pola چکیده کاملIn this work, Zn-Co-Mo coatings were electrodeposited on mild steel substrate from a citrate solution at current densities of 5, 7.5 and 10 mA.cm-2 and pH values of 4.5, 5, and 5.5. The coated samples were studied by scanning electron microscope and potentiodynamic polarization. The corrosion behavior of the coatings was related to the molybdenum content and formation of local anodes and cathodes. According to the results, a distinct range of current and pH was recognized to provide high quality and corrosion resistant coatings. The percentage of molybdenum as an alloying element plays an important role in the improvement of the corrosion properties of the coating. The formed coating at pH of 5.5 with 13 wt. % Mo showed the lowest corrosion current density with a value of 0.5 µA.cm-2.The molybdenum coating also showed a passive-like behavior in the anodic region due to the presence of molybdenum in the coating composition. پرونده مقاله -
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49 - Effect of CTAB surfactant on microstructure and oxidation behavior of Ni-TiO2 Composite coating
Eisa Khoran Morteza Zanrahimi Hadi EbrahimifarSurface modification is very important in the component in industry due to wear and corrosion. In order to improve the corrosion behavior of steels, a protective coating can be deposited onto the surface. In this study Ni-TiO2 coatings were prepared on an AISI 430 stain چکیده کاملSurface modification is very important in the component in industry due to wear and corrosion. In order to improve the corrosion behavior of steels, a protective coating can be deposited onto the surface. In this study Ni-TiO2 coatings were prepared on an AISI 430 stainless steel substrate by electrocodeposition process in Watt’s plating bath containing TiO2 particles. Two types of coatings was produced; without CTAB and at presence of CTAB surfactant. Isothermal oxidation behavior of uncoated and two types of coated specimens were studied up to 250 h in 800 ºC. Also cyclic oxidation was studied for 100 cycles at 800 C. Scanning electron microscope (SEM) and X-ray systems were applied in order to investigate the formed phases and structures of composite coating before and after oxidation. Results showed coated specimens at presence of CTAB surfactant had lower mass gain compared to Ni-TiO2 coated and uncoated ones after isothermal and cyclic oxidation at 800 ºC. پرونده مقاله -
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50 - Fabrication of anodic aluminium oxide template and the generation of magnetic Co nanowires within it
masoud soltani Reihane Aliramezani saeid akhavan Zeinab Erfani Gahrouei mohammad noormohammadiAmong nanostructured materials, magnetic nanowires have been heeded because of their high shape anisotropy and their easy fabrication methods. Electrochemical deposition on the anodic aluminium oxide (AAO) is one of the best methods to grow different nanowires. In this چکیده کاملAmong nanostructured materials, magnetic nanowires have been heeded because of their high shape anisotropy and their easy fabrication methods. Electrochemical deposition on the anodic aluminium oxide (AAO) is one of the best methods to grow different nanowires. In this paper, the AAO was fabricated on the 1100 Al alloy substrate by hard anodizing in 0.3 M oxalic acid solution. Then, a barrier layer thinning process was carried out for the electrodeposition process. A pulsed electrodeposition process was used to fill the nano-pores. According to this method, cobalt nanowires were grown in the nano-holes. Structural, crystalline, and magnetic properties of the samples were evaluated using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM), respectively. The results showed that nanowires have a diameter of 87 nm and crystalline structure with crystalline plates in directions (100), (002), and (110). A coercivity value of 600 Oe was obtained for nanowires, which is several times larger than cobalt bulk. پرونده مقاله -
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51 - Effects of Active Material Particles Size Distribution on the Fabrication of TiNb2O7 Electrode Used in Lithium-Ion Batteries
Touraj Adhami Reza Ebrahimi-Kahrizsangi Hamid Reza Bakhsheshi Rad Somayeh Majidi Milad GhorbanzadehIn this study effect of active material particle size distribution (PSD) on TiNb2O7 electrodes and their performance were evaluated. To determine the effect of PSD, have focused on the performance of the electrode, which is mainly affected by the performance of individu چکیده کاملIn this study effect of active material particle size distribution (PSD) on TiNb2O7 electrodes and their performance were evaluated. To determine the effect of PSD, have focused on the performance of the electrode, which is mainly affected by the performance of individual particles and their interaction. For this purpose, TiNb2O7 was successfully synthesized by mechanochemical method and post-annealing, as an anode material for lithium-ion batteries. Phase identifications and microstructure characterization was carried out by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) to identify the phases and evaluate the morphology of the synthesized samples. The charging and discharging tests were conducted using a battery-analyzing device for evaluating the electrochemical properties of the fabricated anodes. Eventually, at faster charging rates, the electrochemical performance was found to be improved when smaller active material particle size distribution was used. Differences in particles size distributions resulted in variable discharge capacities so that the sample with particle size higher than 25 microns (>25 μm) showed a capacity of 19 mAh/g after 179 cycles, which had a lower capacity than their sample with particle size less than 25 microns (<25 μm). The final capacity of the sample with a particle size less than 25 microns is 72 mAh/g. پرونده مقاله -
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52 - Influences of Bath Stirring Rate on Synetics of Nano Composite Ni-SiC-Gr Coatings on St37 via Electrodeposition Process
M Rostami R Ebrahimi-Kahrizsangi A SaatchiIn this study, electrochemical deposition of Ni-SiC-Gr nano composites was studied. The Watts bath was used for electrodeposition. The SiC and graphite powders were suspended in the electrolyte and stirred. The effects of changes in bath stirring rate on the composite c چکیده کاملIn this study, electrochemical deposition of Ni-SiC-Gr nano composites was studied. The Watts bath was used for electrodeposition. The SiC and graphite powders were suspended in the electrolyte and stirred. The effects of changes in bath stirring rate on the composite coating were investigated. The X-Ray diffraction (XRD), scanning electron microscopy (SEM) and field emission scanning electron microscopy (FE-SEM) methods were used to characterize the micro structure of deposited layer. The results showed that the micro-hardness at the first stage increases with increases in stirring rate value. The coating that precipitated at 500 rpm showed maximum hardness. Analysis of microstructure with SEM showed a homogeneous and uniform distribution of elements in the coated layer. The optimum condition for electrodeposition were as: pH=4.2, current density= 4A/dm2, stirring rate =500 rpm and 45˚C. پرونده مقاله -
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53 - Comparative evaluation of niobium surface preparation methods for electrodeposition
H Nasiri Vatan M.R MohammadshafieeTo find a suitable treatment in the preparation of Nb surface for platinum electrodeposition, different methods such as thermal oxidation, anodic oxidation, mechanical roughening, and mechanical roughening with subsequent anodic etching were examined. X-ray photoelectro چکیده کاملTo find a suitable treatment in the preparation of Nb surface for platinum electrodeposition, different methods such as thermal oxidation, anodic oxidation, mechanical roughening, and mechanical roughening with subsequent anodic etching were examined. X-ray photoelectron spectroscopy was used to study the chemical composition of depth analysis of the surface. Moreover, in order to examine the morphology and surface roughness, the samples were analyzed by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The results showed that the most appropriate method for niobium surface preparation is mechanical roughening by shot blasting or abrading with emery and then anodic etching at the current density of 200 A/m2 for 40 min. in a solution containing 95% methanol, 2.5% hydrofluoric acid, and 2.5% hydrochloric acid at the temperature of 35 °C. پرونده مقاله -
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54 - An efficient platform based on cupper complex-multiwalled carbon nanotube nanocomposite modified electrode for the determination of uric acid
Mohammad Mehdi ForoughiA new voltammetric sensor for determination of uric acid (UA) by Cupper complex- multiwalled carbon nanotube (Cu-complex-CNT) nanocomposite modified carbon paste electrode (CPE) is reported. The electrocatalytic behavior of the Cu-complex-CNT nanocomposite modified CPE چکیده کاملA new voltammetric sensor for determination of uric acid (UA) by Cupper complex- multiwalled carbon nanotube (Cu-complex-CNT) nanocomposite modified carbon paste electrode (CPE) is reported. The electrocatalytic behavior of the Cu-complex-CNT nanocomposite modified CPE were studied in pH 2.0 phosphate buffer solution by chronoamperometry (CA) and cyclic voltammetry (CV) in the presence of uric acid. Due to the excellent electrocatalytic activity, enhanced electrical conductivity and high surface area of the Cu-complex-CNT, determination of uric acid with well-defined peaks was achieved at the Cu-complex-CNT modified electrode. The catalytic peak current obtained, was linearly dependent on the UA concentrations in the range of 0.66 – 350.0µM with sensitivity of 0.05 µA µM-1. The detection limits for UA were 0.075µM, The diffusion coefficient for the oxidation of UA at the modified electrode was calculated as (4.1±0.05) ×10−5 cm2 s−1. The proposed sensor was successfully examined for real sample analysis with urine and human serum and revealed stable and reliable recovery data. پرونده مقاله -
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55 - One-step cathodic electro-synthesis and characterization of dextran coated magnetite nanoparticles
Mustafa Aghazadeh Isa KarimzadehIn this research, a simple and efficient cathodic electrochemical deposition (CED) route was developed for the preparation of magnetite nanoparticles (NPs) in an aqueous media. The surface of magnetite NPs was also coated for the first time via an in situ procedure duri چکیده کاملIn this research, a simple and efficient cathodic electrochemical deposition (CED) route was developed for the preparation of magnetite nanoparticles (NPs) in an aqueous media. The surface of magnetite NPs was also coated for the first time via an in situ procedure during the CED process. In this method, initially, the Fe3O4 NPs (with size ~10 nm) were prepared from the Fe2+/Fe3+ chloride bath through CED process. Then, dextran as the coating agent was coated on the surface of Fe3O4 NPs during the CED process. The prepared NPs were characterized by different techniques such as XRD, FE-SEM, TEM, IR, TGA, DLS and VSM. The XRD results proved the pure magnetite i.e. Fe3O4 crystal phase of the prepared samples. Morphological observations through FE-SEM and TEM revealed particle morphology with nano-sizes of 8 nm and 12 nm for the naked and dextran coated NPs, respectively. The dextran coat on the surfaces of NPs was confirmed by FT-IR and DSC-TGA analyses. The average hydrodynamic diameters of 17 nm and 54 nm were measured from DLS analysis for the naked and dextran coated NPs, respectively. The magnetic analysis by VSM revealed that prepared NPs have superparamagnetic behavior i.e. Ms= 82.3 emu g–1, magnetization Mr= 0.71 emug–1 and Ce= 2.3 Oe for the naked NPs, and Ms= 43.1 emu g–1, Mr =0.47 emu g–1 and Ce=0.81Oe for the dextran coated NPs. These results implied that this electrochemical strategy can be recognized as an effective preparation method of polymer coated Fe3O4 NPs. پرونده مقاله -
دسترسی آزاد مقاله
56 - Electrochemical sensor based on SmHCF/multiwalled carbon nanotube modified glassy carbon electrode for dopamine
taher yousefi Ghasem Adollahi Mohammad hossein mashadizadeh ramin yavariSmHCF/(MWCNT) nano structures modified glassy carbon (GC) electrode was used as electrochemical sensor for the electro oxidation of dopamine. Our strategy was the combination of high electrocatalytic property of SmHCF to electroactive biomolecule and high conductivity, چکیده کاملSmHCF/(MWCNT) nano structures modified glassy carbon (GC) electrode was used as electrochemical sensor for the electro oxidation of dopamine. Our strategy was the combination of high electrocatalytic property of SmHCF to electroactive biomolecule and high conductivity, surface area and adhesive properties of carbon nanotubes. The presence of SmHCF nanoparticles and MWCNT were approved by Scanning electron microscopy (SEM) and cyclic voltammetry (CV). The electrocatalytic performance of GC, SmHCF-GC, MWCNT-GC and SmHCF-MWCNT-GC electrodes toward dopamine was compared and the results cleared the enhanced electrocatalytic activity of SmHCF-MWCNT-GC (lowering the potential of the oxidation process and increased oxidation current peak.) relative to others. This unique combination leads to improvement of the sensitivity of dopamine determination. The differential pulse voltammetry was used for quantitative determination of dopamine. The linear dynamic range relationship between oxidation peak currents and dopamine concentration was 2× 10-7 - 5× 10-6 (slope = 24.187 µAµM-1) with the detection limit of 6× 10-8 for DA. The sensitivity of the electrode was 24.187 µAµM-1 that it is very high relative to reported works. The relative standard deviation (RSD) of the reproducibility (5 modified electrodes), repeatability (successive 10 times), and stability (50 days) of the modified electrode were 3%, 3% and 2.5% respectively. The accuracy and selectivity of the modified electrode were indicated in the real sample as human serum samples and in the presence of possible interfering agents. Good selectivity and recovery were observed for modified electrode. پرونده مقاله -
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57 - An efficient platform based on cupper complex-multiwalled carbon nanotube nanocomposite modified electrode for the determination of uric acid
Mohammad Mehdi ForoughiA new voltammetric sensor for determination of uric acid (UA) by Cuppercomplex- multiwalled carbon nanotube (Cu-complex-CNT) nanocomposite modifiedcarbon paste electrode (CPE) is reported. The electrocatalytic behavior of theCu-complex-CNT nanocomposite modified CPE was چکیده کاملA new voltammetric sensor for determination of uric acid (UA) by Cuppercomplex- multiwalled carbon nanotube (Cu-complex-CNT) nanocomposite modifiedcarbon paste electrode (CPE) is reported. The electrocatalytic behavior of theCu-complex-CNT nanocomposite modified CPE was studied in pH 2.0 phosphatebuffer solution by chronoamperometry (CA) and cyclic voltammetry (CV) in thepresence of uric acid. Due to the excellent electrocatalytic activity, enhancedelectrical conductivity and high surface area of the Cu-complex-CNT, determinationof uric acid with well-defined peaks was achieved at the Cu-complex-CNT modifiedelectrode. The catalytic peak current obtained, was linearly dependent on theUA concentrations in the range of 0.66 – 350.0μM with sensitivity of 0.05 μAμM-1. The detection limits for UA were 0.075μM, The diffusion coefficient for theoxidation of UA at the modified electrode was calculated as (4.1±0.05) ×10−5 cm2s−1. The proposed sensor was successfully examined in real sample analysis withurine and human serum and revealed stable and reliable recovery data. پرونده مقاله -
دسترسی آزاد مقاله
58 - One-step Cathodic Electrochemical Synthesis and Characterization of Dextran Coated Magnetite Nanoparticles
Mustafa Aghazadeh Isa KarimzadehIn this research, a simple and efficient cathodic electrochemical deposition (CED) route wasdeveloped for the preparation of magnetite nanoparticles (NPs) in an aqueous media. Thesurface of magnetite NPs was also coated for the first time via an in situ procedure during چکیده کاملIn this research, a simple and efficient cathodic electrochemical deposition (CED) route wasdeveloped for the preparation of magnetite nanoparticles (NPs) in an aqueous media. Thesurface of magnetite NPs was also coated for the first time via an in situ procedure during theCED process. In this method, initially, the Fe3O4 NPs (with size ~10 nm) were prepared from theFe2+/Fe3+ chloride bath through CED process. Then, dextran as the coating agent was coatedon the surface of Fe3O4 NPs during the CED process. The prepared NPs were characterizedby different techniques such as XRD, FE-SEM, TEM, IR, TGA, DLS and VSM. The XRD resultsproved the pure magnetite i.e. Fe3O4 crystal phase of the prepared samples. Morphologicalobservations through FE-SEM and TEM revealed particle morphology with nano-sizes of 8nm and 12 nm for the naked and dextran coated NPs, respectively. The dextran coat on thesurfaces of NPs was confirmed by FT-IR and DSC-TGA analyses. The average hydrodynamicdiameters of 17 nm and 54 nm were measured from DLS analysis for the naked and dextrancoated NPs, respectively. The magnetic analysis by VSM revealed that prepared NPs havesuperparamagnetic behavior, i.e. Ms=82.3 emu g–1, magnetization Mr=0.71 emug–1 and Ce=2.3Oe for the naked NPs, and Ms=43.1 emu g–1, Mr=0.47 emu g–1 and Ce=0.81Oe for the dextrancoated NPs. These results implied that this electrochemical strategy can be recognized as aneffective preparation method of polymer coated Fe3O4 NPs. پرونده مقاله -
دسترسی آزاد مقاله
59 - Electrochemical sensor based on SmHCF/multiwalled carbon nanotube modified glassy carbon electrode for dopamine
NGhasem Abdollahi taher yousefi Mohammad Hossein Mashadizadeh Ramin YavariSmHCF/(MWCNT) nano structures modified glassy carbon (GC) electrode wasused as electrochemical sensor for the electro oxidation of dopamine. Ourstrategy was the combination of high electrocatalytic property of SmHCF toelectroactive biomolecule and high conductivity, sur چکیده کاملSmHCF/(MWCNT) nano structures modified glassy carbon (GC) electrode wasused as electrochemical sensor for the electro oxidation of dopamine. Ourstrategy was the combination of high electrocatalytic property of SmHCF toelectroactive biomolecule and high conductivity, surface area, and adhesiveproperties of carbon nanotubes. The presence of SmHCFnanoparticles andMWCNT was approved by Scanning electron microscopy (SEM) and cyclicvoltammetry (CV). The electrocatalytic performance of GC, SmHCF-GC, MWCNTGCand SmHCF-MWCNT-GC electrodes toward dopamine was compared andthe results cleared the enhanced electrocatalytic activity of SmHCF-MWCNT-GC(lowering the potential of the oxidation process and increased oxidation currentpeak.) relative to others. This unique combination leads to the improvement ofthe sensitivity of dopamine determination. The differential pulse voltammetrywas used for quantitative determination of dopamine. The linear dynamic rangerelationship between oxidation peak currents and dopamine concentration was2× 10-7 - 5× 10-6 (slope = 24.187 μAμM-1) with the detection limit of6× 10-8 forDA.The sensitivity of the electrode was 24.187 μAμM-1 that it is very high relativeto reported works. The relative standard deviation (RSD) of the reproducibility(5 modified electrodes), repeatability (successive 10 times), and stability (50days) of the modified electrode were 3%, 3% and 2.5% respectively. The accuracyand selectivity of the modified electrode were indicated in the real sample ashuman serum samples and in the presence of possible interfering agents. Goodselectivity and recovery were observed for the modified electrodes. پرونده مقاله -
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60 - Study the Percentage of Carbon and Ferrite in Layers of Steel (SA-516) by Strip Cladding with E316L
Ahmad Afsari Dara Fazel Jafar Karimisharifabadi Vahid MehrabiOne of the most important methods to reduce metal corrosion and improve erosion resistance is to use strip cladding with electro slag welding. Applying the strip electrode (E316l), cladding performed on the layer of steel (5A-516) with this process. With changes in the چکیده کاملOne of the most important methods to reduce metal corrosion and improve erosion resistance is to use strip cladding with electro slag welding. Applying the strip electrode (E316l), cladding performed on the layer of steel (5A-516) with this process. With changes in the thickness of cladding layers and the number of these layers, the percentages of ferrite and carbon in samples obtained by WRC equipment were analyzed. The optical microscopy is used to investigate the microstructure of different cladding layers in this research work. Hence, with the increase in the percentage of carbon, the sensitivity of stainless steel to grain boundary corrosion increases. With the reduction of ferrite percentage, the sensitivity to hot cracking increased too, so the overall results indicate that with an increase in the thickness of the first cladding layer, the amount of carbon in this layer increases, this phenomenon reduces the percentage of ferrite in it. Hence, by increasing the number of cladding layers, the amount of carbon percentage reduces considerably while the ferrite percentage reaches the desired amount. پرونده مقاله -
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61 - A strategy for degradation of 2,5-dichlorophenol using its photoelectrocatalytic oxidation on the TiO2/Ti thin film electrode
Ebrahim ZareiIn this work, the photoelectrocatalytic (PEC) degradation of 2,5-dichlorophenol can be used for its removal from aqueous solution. To study this activity, a TiO2 thin film modified titanium sheet (TiO2/Ti) was fabricated by anodizing Ti plates using a two electrode syst چکیده کاملIn this work, the photoelectrocatalytic (PEC) degradation of 2,5-dichlorophenol can be used for its removal from aqueous solution. To study this activity, a TiO2 thin film modified titanium sheet (TiO2/Ti) was fabricated by anodizing Ti plates using a two electrode system under the constant bias voltage of 20 V for 20 min in a solution of 0.2% (v/v) HF followed by calcination at 500 oC for 2 h. Then, the electrochemical properties of 2,5-dichlorophenol were compared on the surface of the TiO2/Ti and unmodified Ti electrodes. Consequently, the TiO2/Ti was applied for PEC degradation of 2,5-dichlorophenol. It was found that 2,5-dichlorophenol could be degraded more efficiently by this photoelectrocatalysis process than the sum of degradation obtained by photocatalytic (PC) and electrochemical (EC) oxidation so that the amount of 2,5-dichlorophenol degraded by PEC, PC and EC oxidation were equal to 51%, 39% and 5% respectively under the 0.4 V voltage in 60 min. The effect of various parameters was studied and the highest degradation percentage of 2,5-dichlorophenol was obtained at pH 6.0, the initial 2,5-dichlorophenol concentration of 7.0 mg L-1 and applied potential of 1.2 V. پرونده مقاله -
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62 - Formaldehyde measurement based on its electrocatalytic oxidation by Ni-TiO2 nanoparticles/chitosan modified carbon paste electrode as an effective method
Ebrahim Zarei Mohammad Reza Jamali Jaber BagheriIn this work, for the first time, a new and effective bulk modified carbon paste electrode (CPE) was prepared by TiO2 nanoparticles and chitosan and then Ni2+ ions were incorporated to this electrode by immersion of the modified electrode in nickel chloride solution. Th چکیده کاملIn this work, for the first time, a new and effective bulk modified carbon paste electrode (CPE) was prepared by TiO2 nanoparticles and chitosan and then Ni2+ ions were incorporated to this electrode by immersion of the modified electrode in nickel chloride solution. The values of electron transfer coefficient, charge-transfer rate constant and electrode surface coverage for Ni(II)/Ni(III) redox couple of the TiO2/chitosan modified carbon paste electrode (Ni-TiO2/CHIT/CPE) were found to be 0.66, 3.28 × 10-1 s-1 and 5.14 × 10-8 mol cm-2, respectively. The prepared Ni-TiO2/CHIT/CPE material was characterized by scanning electron microscopy and X‐ray diffractometry. The electrochemical behaviour of the Ni-TiO2/CHIT/CPE towards oxidation of formaldehyde was evaluated and proved. The effects of various factors on the efficiency of electrocatalytic oxidation of formaldehyde were optimized. Under the optimized condition, a calibration curve was obtained in the linear dynamic range of 2.80 × 10-4 to 2.50 × 10-2 mol L-1 with detection limit of 7.14 × 10-5 mol L-1 (3σ/slope) for formaldehyde determination. Also, the method was successfully applied for formaldehyde measurement in the real sample. پرونده مقاله -
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63 - Introducing Pt/ZnO as a new non carbon substrate electro catalyst for oxygen reduction reaction at low temperature acidic fuel cells
Rasol Abdullah Mirzaie Fatemeh HamediGas diffusion electrode was used for providing better conditions in fuel cell systems for oxygen reduction reaction (ORR). Because the slow kinetics of the oxygen reduction reaction at the proton exchange membrane fuel cell cathode restricts fuel cell efficiency. To thi چکیده کاملGas diffusion electrode was used for providing better conditions in fuel cell systems for oxygen reduction reaction (ORR). Because the slow kinetics of the oxygen reduction reaction at the proton exchange membrane fuel cell cathode restricts fuel cell efficiency. To this end, researchers have used platinum-coated carbon. In the present study, due to the reduction of carbon corrosion, Zinc oxide nanoparticles have been employed as a support material for platinum. The Pt/ZnO nanoparticles catalyst was made via a combined process of impregnation and seeding method. The microstructure of coating was characterized using scanning electron microscopy (SEM) which indicates that Pt nanoparticles are uniformly dispersed on the surface of ZnO. In order to investigate the chemical composition and crystalline phases of coating, X-ray analysis was carried out. Electrochemical Impedance Spectroscopy (EIS) was carried out for comparing the charge transfer effect during the ORR. The catalytic performance of the electrodes for ORR is evaluated through linear sweep voltammetry measurement. The O2 reduction current for Pt/ZnO alone is expectedly low due to the low electronic conductivity in ZnO. However, adding single-wall carbon nanotube (SWCNT) to the reaction layer improves the electrode performance. The prepared Pt/ZnO/SWCNT 30 wt. % electrode shows high catalytic activity for the ORR, which is probably attributed to conductivity changes caused by the addition of SWCNT. The electrochemical active surface area (ECSA) and durability investigation was studied by cyclic voltammetry in nitrogen saturated 0.5 M H2SO4. The results calculated from ECSA measurements were indicated that the degradation rate of optimized electrode is smaller than Pt/C electrode. پرونده مقاله -
دسترسی آزاد مقاله
64 - Evaluation of sodium dodecyl sulfate effects; the response of modified carbon paste electrode with nickel oxide nanoparticles in the presence of methanol
Banafsheh Norouzi Mehdi NorouziSynthesis of nickel oxide nanoparticles (NiO NPs) was carried out by Marrubium astranicum leaf extract. The average of particle sizes for NiO NPs was 40 nm. NiO NPs modified carbon paste electrodes in the absence (CPE/NiO NPs) and the presence of sodium dodecyl sulfate چکیده کاملSynthesis of nickel oxide nanoparticles (NiO NPs) was carried out by Marrubium astranicum leaf extract. The average of particle sizes for NiO NPs was 40 nm. NiO NPs modified carbon paste electrodes in the absence (CPE/NiO NPs) and the presence of sodium dodecyl sulfate (CPE/NiO NPs/SDS) were examined for the electrocatalytic oxidation of methanol in alkaline solutions. The cyclic voltammograms of modified electrodes showed the redox behavior of Ni(III)/Ni(II) couple. However, the presence of SDS at the surface of the electrode increased the efficiency of the catalyst. The values of charge transfer coefficients (α) for the CPE/NiO NPs and CPE/NiO NPs/SDS in the presence of methanol were estimated at about 0.63 and 0.84. Finally, the electrocatalytic oxidation of methanol at the surface of the CPE/NiO NPs/SDS was studied in the optimum conditions (30 min for immersion time in SDS solution, 0.01 M for SDS concentration and 0.4 M for methanol concentration). پرونده مقاله -
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65 - A Nickel Sublayer: An Improvement in the Electrochemical Performance of Platinum-Based Electrocatalysts as Anodes in Glucose Alkaline Fuel Cells
Behnam Moeini Masoumeh Ghalkhani Tahereh G. Avval Matthew R. Linford Rasol Abdullah MirzaiePlatinum–nickel electrocatalysts supported on the modified carbon paper (MCP) were prepared by electrodeposition. Here, various procedures were applied for the electrodeposition of nickel and platinum particles, separately or simultaneously, on the surface of the چکیده کاملPlatinum–nickel electrocatalysts supported on the modified carbon paper (MCP) were prepared by electrodeposition. Here, various procedures were applied for the electrodeposition of nickel and platinum particles, separately or simultaneously, on the surface of the MCP as an anode electrode for glucose alkaline fuel cells. The establishment of the best procedure for this fabrication is the main goal of this work. The obtained electrocatalysts were characterized by cyclic voltammetry, linear sweep voltammetry, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The results showed that the Pt/Ni electrocatalyst, electrodeposited from two separate solutions containing Ni and then Pt ions, has excellent electrocatalytic activity for the glucose oxidation reaction (GOR). On the other hand, the Pt/Ni/MCP electrode showed satisfactory repeatability when subjected to continuous cycling and less concentration polarization in the oxidation region of GOR (from -1 to 0.6 V vs. SCE). Also, the Pt/Ni/MCP electrode showed a significant increase in the exchange current density (0.95 mA cm-2) that accelerates the kinetics of the glucose oxidation reaction.These results indicate that modification of the catalyst layer structure in the present work is the most promising approach to achieve low-cost and efficient catalysts for use in glucose alkaline fuel cells. پرونده مقاله -
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66 - Electrochemical amperometric sensing of loratadine using NiO modified paste electrode as an amplified sensor
Neda Raeisi-Kheirabadi Alireza Nezamzadeh-Ejhieh Hamidreza AghaeiA modified carbon paste electrode with NiO nanoparticles showed an excellent electrocatalytic behavior towards loratadine in the voltammetric and chronoamperometric approaches. Typical plots of IC/IL vs. t1/2 were contracted, and an average rate constant of 185.5 &plusm چکیده کاملA modified carbon paste electrode with NiO nanoparticles showed an excellent electrocatalytic behavior towards loratadine in the voltammetric and chronoamperometric approaches. Typical plots of IC/IL vs. t1/2 were contracted, and an average rate constant of 185.5 ± 2.2 M−1 s−1 was obtained from the slope of the curve. The geometric surface area of the electrode was 0.0314 cm2, and an average D-value of (1.11×10−3 ± 1.16×10−4) m2 s−1 was obtained for the diffusion of loratadine (Lor) towards the electrode surface. When the effective surface area (0.245 cm2) was used in calculations, an average D-value of (1.83×10−5 ± 1.96×10−6) cm2 s−1 was obtained. ∆I response is the peak current difference of the electrode at a fixed time when Lor analyte was added, and it is in proportion to the loratadine concentration in the range of 20-1000 nM. The limit of detection (LOD) and the limit of quantification (LOQ) of the method were 1.4 and 4.7 nM Lor when the 3Sb/m and 10Sb/m criteria were used, respectively. پرونده مقاله -
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67 - A glassy carbon electrode modified with boron-doped graphene oxide/ polyaspartic acid for electrochemical determination of oxazepam
Maryam Behravan Hossein Aghaie Masoud Giahi Laleh MalekniaIn this study, the electrochemical determination of oxazepam in plasma samples was studied. The composite of graphene oxide/boron (B-RGO) was synthesized via the hydrothermal method and it was cast on the glassy carbon electrode (GCE). The polyaspartic acid (poly(ASP)) چکیده کاملIn this study, the electrochemical determination of oxazepam in plasma samples was studied. The composite of graphene oxide/boron (B-RGO) was synthesized via the hydrothermal method and it was cast on the glassy carbon electrode (GCE). The polyaspartic acid (poly(ASP)) was deposited on the B-RGO by electropolymerization to prepare the modified electrode named B-RGO/ poly(ASP)|GCE. The B-RGO and B-RGO/poly ASP were characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Electrochemical studies were performed by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and differential pulse voltammetry (DPV) methods. The experimental parameters affecting the reduction of oxazepam such as pH, preconcentration time, scan rate and other analysis conditions, and instrumental parameters were optimized. Under the optimal conditions, the linear range was obtained from 0.001 to 800 μM with a correlation coefficient of 0.998. The repeatability of the method for the electrode to electrode and one electrode were 4.3% and 4.9%, respectively. The limit of detection (LOD) of 0.3 nM and the limit of quantitation (LOQ) of 1 nM were obtained. The high efficiency of the developed electrode in the determination of oxazepam in the plasma sample was proved by using acceptable results and satisfactory relative recovery percentage (>90%). Based on our calculation, the heterogeneous electron transfer rate constant (ks) was 1.92 s-1. The interaction between oxazepam and modifier was single-layer and multi-layer adsorption, respectively in low and high concentrations. پرونده مقاله -
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68 - Comparative study on the electrocatalytic activity of dissimilar electrode combinations for the treatment of textile effluent by electrocoagulation process and their subsequent reuse
Jovitha David Asath Stephen Maria Riju Robin Sahaya Sebastian Jegathambal Palanichamy Parameswari KalivelThe synthetic dyes which are largely used in the textile industries pollute the total ecosystem. They can be treated using different technologies but in order to avoid secondary pollution and to carry out an eco-friendly technique, an electrocoagulation process has been چکیده کاملThe synthetic dyes which are largely used in the textile industries pollute the total ecosystem. They can be treated using different technologies but in order to avoid secondary pollution and to carry out an eco-friendly technique, an electrocoagulation process has been adopted. In this work, two sets of electrodes which act as the electrocatalysts for the process of electrocoagulation, with one set containing aluminium as an anode and the other with copper as anode has been used to contrast and compare the removal efficacies. The colour removal efficiency was observed as 98.42% for Al-Cu, and 95.12% for Cu-Al electrodes. The COD and BOD removal efficiency was found to be 89.74%, 86.1% for Al-Cu and 87.15%, 85.23% for Cu-Al electrodes. The cost for the treatment process was 3.31 US$/m3 and 0.22 US$/m3 for Al-Cu and Cu-Al electrodes respectively. The sludge was subjected to EDX, SEM, and XPS analysis which showed the formation of hydroxides and dissolution of an anode implying copper as the best anode material. The energy and electrode consumption, operating cost was minimum for copper than aluminium. Due to high COD and BOD removal, the treated water can be reused for agriculture and for fish growth. پرونده مقاله -
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69 - تعیین لوزارتان با استفاده از الکترود خمیر کربن اصلاحشده با چارچوب آلی-فلزی 101MIL- و روش آمپرولتسنجی تپ تفاضلی
مهزاد فیروزی مسعود گیاهی مصطفی نجفی سید سعید همامی سید حسین هاشمی موسویدر این پژوهش، ابتدا چارچوب آلی- فلزی 101MIL- تهیه و با طیف شناسی فروسرخ تبدیل فوریه، پراش پرتو ایکس و میکروسکوپ الکترونی پویشی شناسایی شد. سپس یک حسگر الکتروشیمیایی حساس بر پایه الکترود خمیر کربن اصلاحشده با چارچوب آلی- فلزی برای تعیین لوزارتان ساخته شد. بررسی رفتار ا چکیده کاملدر این پژوهش، ابتدا چارچوب آلی- فلزی 101MIL- تهیه و با طیف شناسی فروسرخ تبدیل فوریه، پراش پرتو ایکس و میکروسکوپ الکترونی پویشی شناسایی شد. سپس یک حسگر الکتروشیمیایی حساس بر پایه الکترود خمیر کربن اصلاحشده با چارچوب آلی- فلزی برای تعیین لوزارتان ساخته شد. بررسی رفتار الکتروشیمیایی لوزارتان در سطح الکترود خمیر کربن اصلاحشده با روشهای آمپرولت‎سنجی چرخه‎ای و آمپرزمان‎سنجی انجام گرفت. الکترود اصلاحشده فعالیت الکتروکاتالیستی خوبی برای اکسایش لوزارتان در بافر فسفات (8 =pH) نشان داد. تعیین غلظت لوزارتان با روش آمپرولت‎سنجی تپ تفاضلی نشان داد که بین غلظت لوزارتان و جریان پیک اکسایش آن دو رابطه خطی در بازه‎های 1 تا 10 و 10 تا 200 میکرو مولار وجود دارد. همچنین، حد تشخیص معادل با 7/0 میکرو مولار برای لوزارتان به دست آمد. اثر مزاحمت احتمالی برخی ترکیب ها بر پاسخ آمپرولت‎سنجی لوزارتان بررسی شد. در نهایت الکترود اصلاحشده برای تعیین لوزارتان در نمونههای زیستی و داروها به‎صورت موفقیتآمیز به کاربرده شد. پرونده مقاله -
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70 - اندازهگیری هم زمان دوپامین و تیروزین به روش الکتروشیمیایی با الکترود کربن شیشه ای اصلاح شده با نانوچندسازه تهیه شده ZIF-8@CO-TA
نازمریم ستوده شهره جهانی مریم کاظمی پور محمد مهدی فروغیروشهای متداول برای اندازهگیری هم زمان نمونههای زیستی، پزشکی و دارویی، وقتگیر، هزینهبر و پیچیده هستند و نیاز به آماده سازی نمونه دارند. بنابراین، روشهایی که با وجود ارزان قیمت بودن و سادگی، گزینشپذیری و حساسیت بسیار بالایی داشته باشند، موردتوجه هستند. در این چکیده کاملروشهای متداول برای اندازهگیری هم زمان نمونههای زیستی، پزشکی و دارویی، وقتگیر، هزینهبر و پیچیده هستند و نیاز به آماده سازی نمونه دارند. بنابراین، روشهایی که با وجود ارزان قیمت بودن و سادگی، گزینشپذیری و حساسیت بسیار بالایی داشته باشند، موردتوجه هستند. در این پژوهش، نانوچندسازه ای با چارچوب ایمیدازولات زئولیت، کبالت و تانوئیک اسید با نام اختصاری ZIF-8@CO-TA تهیه شد. ویژگیهای نانوچندسازه تهیه شده با طیفسنجی تبدیل فوریه فروسرخ (FTIR)، میکروسکوپ الکترونی روبشی (SEM) و میکروسکوپ الکترونی عبوری (TEM) بررسی شد. الکترود کربن شیشه ای اصلاح شده با این نانوچندسازه برای اندازه گیری هم زمان دوپامین و تیروزین، در pH برابر با 6 به وسیله روش های الکتروشیمیایی ولت آمپرسنجی تپی تفاضلی، ولت آمپرسنجی چرخه ای و زمان آمپر‎سنجی، به کارگرفته شد. در گستره 0/10 تا 0/140 میکرومولار با روش ولت آمپرسنجی تپی تفاضلی، حد تشخیص20/3 و 38/6 میکرومولار به ترتیب برای دوپامین و تیروزین به دست آمد. الکترود کربن شیشه ای اصلاح شده با این نانوچندسازه پایداری طولانی مدت مطلوبی را نشان داد. پرونده مقاله -
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71 - بهبود کارایی سلول خورشیدی حساسشده با رنگدانه N719 با بهکارگیری بسپارهای رسانای پلیپیرول/پلیآنیلین بهعنوان الکترود مقابل
مهسا مهدوی نیا غلامرضا کیانی ایوب کریم زادقویدلهدف از این پژوهش، ساخت سلول خورشیدی برپایه نانوساختار تیتانیم دی اکسید حساس شده با رنگدانه N719 و بهبود کارایی آن با به کارگیری ساختار هسته-پوسته پلی پیرول/پلی آنیلین به عنوان الکترود مقابل است. سلول های خورشیدی تهیه شده با الکترود مقابل بسپار با دو روش لایه نشانی چ چکیده کاملهدف از این پژوهش، ساخت سلول خورشیدی برپایه نانوساختار تیتانیم دی اکسید حساس شده با رنگدانه N719 و بهبود کارایی آن با به کارگیری ساختار هسته-پوسته پلی پیرول/پلی آنیلین به عنوان الکترود مقابل است. سلول های خورشیدی تهیه شده با الکترود مقابل بسپار با دو روش لایه نشانی چرخشی و قطره ای در ضخامت های متغیر، ساخته و ارزیابی شدند. افزون براین، تاثیر غلظت نانوسیم و نانوذره های تیتانیم دی اکسید، حاضر در فوتوآند بر کارایی سلول خورشیدی بررسی شد. مقدار جذب رنگدانه N719 با طیف نورسنج بررسی شد و بیشینه جذب در طول موج های 380 و 530 نانومتر به دست آمد. واکاوی ساختار فوتوآند و الکترود مقابل، با میکروسکوپ الکترونی روبشی نشان داد که ترکیب نانوذره ها و نانوسیم های تیتانیم دی اکسید با نسبت 1 به 9، موجب ایجاد ساختاری متخلخل با نسبت سطح به حجم بالا می شود که تأثیر بسز ایی در مقدار جذب رنگدانه و بازده سلول خورشیدی دارد. با توجه به اینکه سلول خورشیدی تهیه شده با روش لایه نشانی قطره ای، کارایی مطلوبی نداشت، تمرکز پژوهش در راستای نمونه تهیه شده با روش لایه نشانی چرخشی معطوف شد. نمونه سلول خورشیدی ساخته شده با الکترود مقابل پلی پیرول/پلی آنیلین با روش لایه نشانی چرخشی، ولتاژ مدار باز 71/0 ولت و عامل پرشدگی 38/57 را نشان می دهد که ولتاژ مدار باز و عامل پرشدگی نسبت به نمونه های مشابه، به ترتیب به مقدار 6/7 و 35 برابر بهبود یافته اند. پرونده مقاله -
دسترسی آزاد مقاله
72 - تهیه و شناسایی پلیایندول/ نانوذرههای نقره و استفاده از آن در طراحی حسگر الکتروشیمیایی ال-سیستئین
خدیجه قنبری زهرا بابایی سپیده بنیادیدر این پژوهش، یک حسگر الکتروشیمیایی مؤثر برای اندازهگیری سریع ال-سیستئین بر مبنای الکترود کربن شیشهای اصلاحشده با پلیایندول/ نانوذرههای نقره ارائهشده است. نانوفیبرهای پلی ایندول با روش ولتامتری چرخهای در سطح الکترود شیشهای کربن تهیه شدند. سپس، نانوذرههای نقره رو چکیده کاملدر این پژوهش، یک حسگر الکتروشیمیایی مؤثر برای اندازهگیری سریع ال-سیستئین بر مبنای الکترود کربن شیشهای اصلاحشده با پلیایندول/ نانوذرههای نقره ارائهشده است. نانوفیبرهای پلی ایندول با روش ولتامتری چرخهای در سطح الکترود شیشهای کربن تهیه شدند. سپس، نانوذرههای نقره روی این نانوفیبرها با روش اعمال پتانسیل ثابت نشانده شدند. ساختار ویژگیهای سطحی الکترود اصلاحشده با استفاده از تصاویر میکروسکوپ الکترونی روبشی، پراش پرتو ایکس و طیفسنجی تبدیل فوریه فروسرخ تأیید شد. بررسی الکتروشیمیایی نشان داد که پلیایندول/ نانوذرههای نقره کارایی بسیار خوبی نسبت به اکسایش الکتروکاتالیستی ال-سیستئین در محلول بافر فسفات (7 =pH) دارد. پاسخ الکترود کربن شیشهای/ پلیایندول/ نانوذرههای نقره نسبت به ال-سیستئین در گستره غلظتی 01/0 تا 10 میلی مولار خطی بود که حد تشخیص در نسبت نشانک/نوفه برابر با 3، 7/5 میکرومولار بهدست آمد. افزون براین، حسگر پایداری و تکرارپذیری خوبی را نشان داد. کاربرد حسگر پیشنهادی برای بررسی ال-سیستئین در سرم خون انسان موفقیتآمیز بود. پرونده مقاله -
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73 - تهیه یک کاتالسیت ساده و ارزان با الکترود خمیر کربن اصلاحشده با سدیم دودسیل سولفات دارای نیکل برای اکسایش الکتروکاتالیستی اتیلن گلیکول
بنفشه نوروزی زهرا شاکریدر این کار پژوهشی، سدیم دودسیل سولفات (SDS) به روش قطرهگذاری در سطح الکترود خمیر کربن قرار گرفت. سپس با قرار دادن الکترود اصلاحشده در محلول حاوی نیکل نیترات به مدت 5 دقیقه و روبش متوالی پتانسیل در محلول سدیم هیدروکسید، الکترود خمیر کربن اصلاحشده با SDS دارای نیکل (Ni چکیده کاملدر این کار پژوهشی، سدیم دودسیل سولفات (SDS) به روش قطرهگذاری در سطح الکترود خمیر کربن قرار گرفت. سپس با قرار دادن الکترود اصلاحشده در محلول حاوی نیکل نیترات به مدت 5 دقیقه و روبش متوالی پتانسیل در محلول سدیم هیدروکسید، الکترود خمیر کربن اصلاحشده با SDS دارای نیکل (Ni/SDS) تهیه شد. همچنین، با توجه به اهمیت بهکارگیری اتیلن گلیکول بهعنوان منبع پیشنهادی جایگزین هیدروژن و به دلیل سینتیک کند آن در سطح الکترودهای خمیر کربن اصلاحنشده، اکسایش آن در سطح الکترود اصلاحشده فوق بررسی شد. نتایج بهدست آمده بیانگر اکسایش الکتروکاتالیستی اتیلن گلیکول در سطح الکترود خمیر کربن اصلاحشده با Ni/SDS است. تأثیر عاملهای متفاوت بر مقدار کارایی الکترود اصلاحشده بررسی و شرایط بهینه تعیین شد. در پایان نیز ثابت سرعت واکنش شیمیایی بین مراکز ردوکس در سطح الکترود اصلاحشده و اتیلن گلیکول محاسبه شد. سادگی، ارزانی و حساسیت بالا ازجمله ویژگیهای برجسته این الکترود است. پرونده مقاله -
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74 - Increasing the Adsorption of Reinforcement Alumina Nanoparticles in Ni-alumina Nanocomposite Coatings by Using Methanol Organic Solvent
صادق میرزامحمدی حمید خورسند محمود محمود علی اف خضراییTo enhance the mechanical properties in Ni-alumina nanocomposite coatings, it is necessary to increase the amount of alumina nanoparticles participation in nickel matrix. The aim of this study is the compassion investigation of Ni-Al2O3 nanocomposite coatings’ emb چکیده کاملTo enhance the mechanical properties in Ni-alumina nanocomposite coatings, it is necessary to increase the amount of alumina nanoparticles participation in nickel matrix. The aim of this study is the compassion investigation of Ni-Al2O3 nanocomposite coatings’ embedded nanoparticles affected by methanol addition to the electrolyte. In this investigation the composition of electrolyte was modified by adding methanol organic solvent. The coating were produced by pulse current and under ultrasonic agitation .After the electroplating process, the coatings’ cross sectioned and the amount of incorporated alumina nanoparticles and the morphology of each coating was analyzed by Energy X-ray spectroscopy (EDX) coupled with an Scanning Electron Microscopy (SEM). The results showed that with adding the methanol organic solvent to the Watt’s solution the zeta potential of the nanoparticles increased from -4.1mV to +24.5mV and subsequently, the content of alumina reinforcement nanoparticles increased from 4.6vol. % to 11vol. %. It has been assumed that methanol surfactant may act as a surface agent that affected the hydrated layer on the nanoparticles and it promoted the co-deposition of nano alumina particles with nickel. پرونده مقاله -
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75 - Extraction of Sensory part of Ulnar Nerve Signal Using Blind Source Separation Method
Alireza Kashaninia S Nooreddin JafariA recorded nerve signal via an electrode is composed of many evokes or action potentials, (originated from individual axons) which may be considered as different initial sources. Recovering these primitive sources in its turn may lead us to the anatomic originations o چکیده کاملA recorded nerve signal via an electrode is composed of many evokes or action potentials, (originated from individual axons) which may be considered as different initial sources. Recovering these primitive sources in its turn may lead us to the anatomic originations of a nerve signal which will give us outstanding foresights in neural rehabilitations. Accordingly, clinical interests may be raised on extraction of sensory and motor components of the nerve signals in neural injuries. One example is to extract sensory fraction in sacral nerve to sense the bladder filling up in paraplegic or quadriplegic people [3]. Blind Source Separation (BSS) methods seem good solutions for extraction of the initial sources which are contributing in recorded mixed sources. Considering the nerve signal as a superposition of many axonal or fascicular signals, we have encouraged to try BSS methods to see whether it can recover the sensory and motor sources of a recorded nerve signal. Accordingly, both PCA and ICA techniques were examined in a case study (human left arm), in which the response of the ADM muscle to the Ulnar nerve stimulation were recorded in two points. The corresponded sensory signal was recorded on the pinkie at the same time (all recordings were done via surface electrodes). It was shown that ICA (supremely better than PCA) was able to separate initial sources (ADM recorded signals) into two signals so that one of them was most similar to the sensory (Pinkie) signal. The level of similarity was quantified via correlation analysis. As the result, it is concluded that ICA is capable of extracting Sensory and Motor signals in PNS. پرونده مقاله -
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76 - Iodide selective membrane electrode based on copper (Π)-bis-Nphenilsalicyldenaminato complex
Ali Benvidi Mehdi Elahizadeh Hamid Reza Zare, Rasoul VafazadehAn iodide ion-selective PVC membrane sensor based on copper (Π)-bis-Nphenilsalicyldenaminatocomplex as a novel sensing material is successfully developed. Theelectrode showed a good selectivity for iodide ion with respect to common inorganic anions. Thesensor exhibit چکیده کاملAn iodide ion-selective PVC membrane sensor based on copper (Π)-bis-Nphenilsalicyldenaminatocomplex as a novel sensing material is successfully developed. Theelectrode showed a good selectivity for iodide ion with respect to common inorganic anions. Thesensor exhibited a good linear response with slope of _58.6 ± 0.4 mV per decade over theconcentration range of 5.0 × 10-6 to 1.0 × 10-1 mol L-1, and a detection limit of 3.0 × 10-6 mol L-1of I– ion. The electrode response was independent of pH in the range of 3.0 - 10.0. The proposedsensor was applied as an indicator electrode in potentiometric titration of I– with Ag+ ion, and todetermine the iodide in sodium chloride salt. پرونده مقاله -
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77 - Utilization of electrodeposition on a graphite probe modified with palladium in determination of lead by graphite furnace atomic absorption spectrometry in water and environmental samples
Ahmad Rouhollahi Reza Moradkhani Hamid Shirkhanloo Jahan B. GhasemiIn this work a rapid and selective procedure for separation and preconcentration of lead(Pb2+) before determination by electrothermal atomic absorption spectrometry (ETAAS) wasdeveloped. The procedure is based on the electrodeposition on a graphite probe modified withpa چکیده کاملIn this work a rapid and selective procedure for separation and preconcentration of lead(Pb2+) before determination by electrothermal atomic absorption spectrometry (ETAAS) wasdeveloped. The procedure is based on the electrodeposition on a graphite probe modified withpalladium. The lead was deposited from acetate buffer solution at pH 5.5. Various parameters,such as pH of solutions, deposition potential, buffer concentration, stirrer speed, time ofdeposition and temperature program, were optimized. After optimization of the conditions,detection limit 17 ng L–1 by 3 σ, and enrichment factor 61 were achieved for 2 minelectrodeposition time and improved as deposition time was increased. Linearity of calibrationwas kept between 0.05-0.50 μg L–1 with a correlation coefficient of 0.9979 and suitableprecision, R.S.D. % = 5.1 (n = 8). Samples were digested completely in a closed microwavedigestion system using only perchloric acid, and interference owing to various cations was alsoinvestigated. The procedure was successfully applied to determine the presence of lead in rice,radish, okra, onion and water samples. پرونده مقاله -
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78 - اثر متغیرهای رسوب دهی بر فرایند رسوب الکتریکی پالسی کامپوزیت نانوساختار FeNi-WC
آمنه وحیدیان علی سعیدی محمد علی گلعذارنیاز روزافزون به مواد مغناطیسی در صنعت منجر به تولید کامپوزیت آلیاژهای مغناطیسی آهن-نیکل با ذرات سرامیکی شده است. در این تحقیق کامپوزیت نانوساختار FeNi-WC به روش رسوبدهی الکتریکی پالسی تولید شد. همچنین اثر عواملی چون pH و چگالی جریان و مقدار تقویت کننده بر ترکیب شیمیای چکیده کاملنیاز روزافزون به مواد مغناطیسی در صنعت منجر به تولید کامپوزیت آلیاژهای مغناطیسی آهن-نیکل با ذرات سرامیکی شده است. در این تحقیق کامپوزیت نانوساختار FeNi-WC به روش رسوبدهی الکتریکی پالسی تولید شد. همچنین اثر عواملی چون pH و چگالی جریان و مقدار تقویت کننده بر ترکیب شیمیایی و مورفولوژی نمونه ها مورد بررسی قرار گرفت. همچنین برای بررسی مورفولوژی از میکروسکوپ الکترونی روبشی (SEM)، و تعیین عناصر موجود و محاسبه درصد وزنی آنها از آنالیز پراش سنجی انرژی (EDS) و بررسی ساختار نمونه از پراش پرتو ایکس (XRD) استفاده گردید. نتایج نشان داد با افزایش pH، به مقدار کمی نیکل افزایش و آهن کاهش یافت و منجر به تغییر مورفولوژی از کروی به ستارهای گردید. به دلیل اهمیت صرفهجویی در انرژی اثر این متغیرها بر پارامترهای راندمانی چون بازده جریان و انرژی مصرفی ویژه نیز مطالعه شد. مشاهده شد که با افزایش pH، بازده جریان افزایش و انرژی مصرفی ویژه کاهش یافت. افزایش چگالی جریان نیز بازده جریان را کاهش و انرژی مصرفی ویژه را افزایش داد. به طور کلی در چگالی جریان های بیشتر (mA/cm2 100) و مقدار تقویت کننده کمتر (g/L 5) مورفولوژی یکنواخت تری مشاهده شد. پرونده مقاله -
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79 - بررسی شرایط عملیات حرارتی بر استحکام دهی فوم نیکلی تولید شده به روش رسوب دهی الکتروشیمیایی
اکرم صالحی فائزه برزگر احمد مولودیفوم های فلزی دسته ای از مواد نوین هستند که با توجه به وجود تخلخل در ساختار، خواص منحصر به فردی مانند نسبت سطح به حجم بالا، قابلیت جذب انرژی بالا و نسبت استحکام به وزن بالایی دارند. از میان فوم های فلزی، فوم های نیکلی یکی از پرکاربردترین مواد در ساخت انواع کاتالیست ها، ف چکیده کاملفوم های فلزی دسته ای از مواد نوین هستند که با توجه به وجود تخلخل در ساختار، خواص منحصر به فردی مانند نسبت سطح به حجم بالا، قابلیت جذب انرژی بالا و نسبت استحکام به وزن بالایی دارند. از میان فوم های فلزی، فوم های نیکلی یکی از پرکاربردترین مواد در ساخت انواع کاتالیست ها، فیلترها و صداخفه کن ها در صنایع مختلف هستند. در این تحقیق فوم نیکلی تخلخل باز به روش رسوب دهی الکتروشیمیایی بر روی زیر لایه ی پلیمری تولید شد. فوم های تولید شده به منظور حذف فوم پلی اورتانِ زیر لایه و افزایش داکتیلیتی تحت عملیات حرارتی تفجوشی در محیط خنثی، در دو دمای ℃ ۶۰۰ و ℃ ۱۰۰۰ قرار گرفتند. بررسی ریزساختار با میکروسکوپ الکترونی روبشی و همچنین آنالیز EDS نمونه ها پس از تفجوشی بیانگر نفوذ اتم های کربن در دمای ℃ ۶۰۰ و اکسیداسیون نمونه ها در دمای ℃ ۱۰۰۰ است. نتایج آزمون فشار نشان دادند که عملیات تفجوشی موجب داکتیل شدن فوم های نیکلی می شود. فرایند داکتیل شدن همراه با کاهش استحکام مسطح از MPa ۷۹/۴ به ۶/۳ و ۶۵/۱ بترتیب برای تفجوشی در دمای ℃ ۶۰۰ و ℃ ۱۰۰۰ است. نتایج بدست آمده، نشان دادند که علی رغم عدم تاثیر عملیات حرارتی بر کرنش چگالش فوم نیکلی، قابلیت جذب انرژی آن ها نیز از MJ/cm2 ۵۱/۱ به ۲۱/۱ و ۵۵/۰ بترتیب برای تفجوشی در دمای ℃ ۶۰۰ و ℃ ۱۰۰۰ کاهش می یابد. پرونده مقاله -
دسترسی آزاد مقاله
80 - تاثیر متغیرهای آبکاری الکتریکی پالسی و عملیات حرارتی بعدی بر خواص پوشش آلیاژی نانو ساختار کبالت-تنگستن
سمیه اباذری سیوندی سعید رستگاری شهرام خیراندیشپوشش آلیاژی نانو ساختار کبالت–تنگستن با استفاده از روش آبکاری الکتریکی پالسی با فرکانس Hz 200 از حمام سیتراتی در دمای °C 60 روی زیر لایه فولاد ساده کربنی تهیه گردید. در این تحقیق، تاثیر غلظت سولفات کبالت در حمام و سیکل کاری بر ساختار بلوری، اندازه کریستالیت، چکیده کاملپوشش آلیاژی نانو ساختار کبالت–تنگستن با استفاده از روش آبکاری الکتریکی پالسی با فرکانس Hz 200 از حمام سیتراتی در دمای °C 60 روی زیر لایه فولاد ساده کربنی تهیه گردید. در این تحقیق، تاثیر غلظت سولفات کبالت در حمام و سیکل کاری بر ساختار بلوری، اندازه کریستالیت، سختی و مقاومت به خوردگی پوشش مورد بررسی قرار گرفت. مورفولوژی سطحی و ترکیب پوششها با استفاده از میکروسکوپ الکترونی روبشی (SEM) و آنالیز EDS مورد بررسی قرار گرفت. اندازه دانه های کریستالی به کمک آنالیز پراش اشعه ایکس(XRD) و رابطه شرر محاسبه شد. میکروسختی پوششها با استفاده از دستگاه میکروسختیسنج ویکرز اندازهگیری شد. بررسی نتایج نشان میدهند پوشش آبکاری شده در غلظت سولفات کبالت mol/l2/0 و سیکل کاری %60 با چگالی جریان متوسط A/dm21 پوشش بهینه با سختی معادل Hv 758 بوده است. عملیات حرارتی پوشش آمورف حاصل از چگالی جریان A/dm24 در شرایط خلا بالا سبب کریستالی شدن پوشش میشود. مقدار سختی پوشش از Hv 436 قبل از عملیات حرارتی به Hv 1059 پس از عملیات حرارتی در دمای Cº 600 رسید. با افزایش دما تا Cº 600 ساختار پلی کریستال با ترکیبات فازی Co3W و CowO4 شکل گرفت که دلیل افزایش سختی در این دما است. عملیات حرارتی سبب بهبود مقاومت به خوردگی پوشش شده است. پوشش عملیات حرارتی شده در دمایCº 400 کمترین نرخ خوردگی را داشت. پرونده مقاله -
دسترسی آزاد مقاله
81 - اتصال آلیاژ آلومینیوم (АМГ6М) توسط دو فرآیند جوشکاری اصطکاکی-اغتشاشی و قوس الکترود تنگستن با گاز خنثی و مقایسه خواص مکانیکی و ریزساختاری آنها
علی اصغر ترابی تهمینه احمدی افشین شیرعلی محمدرضا خانزاده قره شیران مجید تقیانهدف از انجام این تحقیق بررسی امکان جایگزینی فرآیندجوشکاری قوس تنگستن گاز با فرآیندجوشکاری اصطکاکی اغتشاشی جهت اتصال آلیاژ آلومینیم (АМГ6М) میباشد. در این راستا پس از اعمال پارامترهای اولیه برای هر دو فرآیند جوشکاری ضمن دستیابی به پارامترهای بهینه، آزمونهایی مانند آزمون چکیده کاملهدف از انجام این تحقیق بررسی امکان جایگزینی فرآیندجوشکاری قوس تنگستن گاز با فرآیندجوشکاری اصطکاکی اغتشاشی جهت اتصال آلیاژ آلومینیم (АМГ6М) میباشد. در این راستا پس از اعمال پارامترهای اولیه برای هر دو فرآیند جوشکاری ضمن دستیابی به پارامترهای بهینه، آزمونهایی مانند آزمون کشش، خمش، رادیوگرافی، سختی سنجی، بررسی ساختاری و بررسی میزان اعوجاج بر روی نمونهها انجام گرفت. نتایج حاصل ازاین تحقیق نشان داد که اندازه دانه بدست آمده برای فلز جوش اصطکاکی اغتشاشی و قوس تنگستن گاز به ترتیب 6 و14 میکرون میباشد که درمقایسه با اندازه دانه درفلز پایه که برابر با 30 میکرون است، ریز شدهاند. استحکام کششی نهایی اتصال در جهت همراستای نورد و عمود بر خط جوش در مورد اتصالات جوش اصطکاکی اغتشاشی نسبت به اتصالات جوش قوس تنگستن گاز به مراتب بالاتر است؛Mpa 364 در مقابلMpa 278. افت سختی در ناحیه فلز جوش تقریبا در هر دو فرآیند جوشکاری اصطکاکی اغتشاشی و قوس تنگستن گاز در یک محدوده بوده است. میزان اعوجاج اندازهگیری شده در جوشکاری اصطکاکی اغتشاشی یک چهارم فرآیندجوشکاری قوس تنگستن گاز میباشد. نتیجه آزمایش خمش نمونه جوش اصطکاکی اغتشاشی از رویه مانند نتیجه آزمایش فلز پایه عاری از ترک میباشد. لذا به منظور افزایش خواص مکانیکی و متالورژیکی و همچنین کاهش اعوجاج اتصالات جوشی در سازه های آلومینیومی، فرایند جوشکاری اصطکاکی اغتشاشی گزینه مناسبی جهت جایگزینی با فرآیند جوشکاری قوس تنگستن گاز تشخیص داده شد. پرونده مقاله -
دسترسی آزاد مقاله
82 - بررسی تأثیر دانسیته جریان اعمالی بر خواص ترشوندگی پوشش سریم اکسید تولید شده به روش رسوبدهی الکتروشیمیایی
نوید احمدی زاده پوریا نجفی سیاردر این تحقیق پوشش سریم اکسید به روش رسوبدهی الکتروشیمیایی بر روی زیرلایه مس ایجاد شد. تأثیر دانسیته جریان اعمالی بر مورفولوژی، ساختار کریستالی، شیمی سطح، زبری سطح و رفتار ترشوندگی پوششها به ترتیب به وسیله میکروسکوپ الکترونی روبشی، آزمون تفرق اشعه ایکس، طیف سنجی تبدیل چکیده کاملدر این تحقیق پوشش سریم اکسید به روش رسوبدهی الکتروشیمیایی بر روی زیرلایه مس ایجاد شد. تأثیر دانسیته جریان اعمالی بر مورفولوژی، ساختار کریستالی، شیمی سطح، زبری سطح و رفتار ترشوندگی پوششها به ترتیب به وسیله میکروسکوپ الکترونی روبشی، آزمون تفرق اشعه ایکس، طیف سنجی تبدیل فوریه اشعه مادون قرمز، میکروسکوپ نیروی اتمی و اندازهگیری زاویه تماس آب بر روی پوششها بررسی شدند. نتایج حاصل نشان دادند که با افزایش دانسیته جریان اعمالی پوششهایی ضخیمتر با میزان ترک سطحی و زبری بیشتر تولید میشوند. همچنین صفحات کریستالی (۰۰۲) در پوششهای تولید شده در دانسیته جریانهای کمتر، رشد بیشتری داشتند و این پوششها دارای اندازه بلور بزرگتری بودند. با اعمال دانسیته جریانهای بیشتر، رفتار آبدوستی پوششهای سریا بیشتر شد. اگرچه در ابتدا پوششهای سریا رفتاری آبدوست داشتند اما پس از قرار گرفتن در معرض هوا و جذب هیدروکربن آبگریز شدند. پوششهای ساخته شده در دانسیته جریانهای بالاتر میزان جذب هیدروکربن بیشتری از خود نشان دادند. پرونده مقاله -
دسترسی آزاد مقاله
83 - بهینه سازی و تأثیرپارامترهای پالسی جوشکاری قوسی تنگستنی با گاز محافظ در روکش دهی فولادSt37 با الکترودNob73G2
محسن جهانیان نجف آبادی حمید غیور مسعود کثیریدر این پژوهش به بررسی ساختار میکروسکوپی و خواص سایش روکش ایجاد شده بر سطح فولاد ساده کربنی پرداخته شد. بدین منظور نمونه هایی از جنس فولاد ساده کربنی توسط روش جوشکاری قوس تنگستن تحت گاز محافظ (GTAW)با یک نوع الکترود بدون پوشش تجاری در دو حالت جریان پیوسته و پالس روکش کار چکیده کاملدر این پژوهش به بررسی ساختار میکروسکوپی و خواص سایش روکش ایجاد شده بر سطح فولاد ساده کربنی پرداخته شد. بدین منظور نمونه هایی از جنس فولاد ساده کربنی توسط روش جوشکاری قوس تنگستن تحت گاز محافظ (GTAW)با یک نوع الکترود بدون پوشش تجاری در دو حالت جریان پیوسته و پالس روکش کاری شدند. مقطع عرضی نمونه ها به وسیله ی میکروسکوپ نوری و میکروسکوپ الکترونی مورد بررسی قرار گرفت. به کمک آزمون سختی سنجی، مقدار سختی نمونه ها بررسی گردید.آزمون سایش پین روی دیسک به منظور بررسی مقاومت به سایش نمونه های روکش کاری جوش شده و فولاد ساده کربنی انجام شد. سطوح سایش توسط میکروسکوپ الکترونی مورد بررسی قرار گرفت. نتایج به دست آمده حاکی از آن است که، نمونه روکش کاری شده با تنظیمات صحیح پالس دارای بیشترین سختی سطحی و در نتیجه کمترین نرخ سایش است.جهت بهینه سازی شرایط جوشکاری و مشخص کردن نسبت تأثیرگذاری هرکدام از عوامل مورد استفاده در حالت پالسی بر میزان سختی، از روش طراحی آزمایش تاگوچی و استفاده از تحلیل نسبتS/N استفاده شد. در نهایت پس از تحلیل نتایج کلی مشخص گردید که در بین عوامل متغیر، جریان بیشینه و جریان کمینه، به ترتیب تأثیرگذارترین عوامل بر پاسخ در نظر گرفته شده می باشند. پرونده مقاله
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