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Synergistic effect of cobalt and copper on a nickel-based modified graphite electrode during methanol electro-oxidation in NaOH solution

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Chinese Journal of Catalysis 2015年第11期36卷 1867-1874页

作者： Tayebe Rostami majid jafarian Somaieh Miandari Mohammad G.Mahjani Fereydoon Gobal K.N.图什理工大学化学系谢里夫理工大学化学系

The electrocatalytic oxidation of methanol was studied over Ni, Co and Cu binary or ternary alloys on graphite electrodes in a NaOH solution （0.1 mol/L）. The catalysts were prepared by cycling the graphite electrode in solutions containing Ni, Cu and Co ions at cathodic potentials. The synergistic effects and catalytic activity of the modified electrodes were investigated by cyclic voltammetry （CV）, chronoamperometry CCA） and electrochemical impedance spectroscopy （EIS）. It was found that, in the presence of methanol, the modified Ni-based ternary alloy electrode （G/NiCuCo） exhibited a significantly higher response for methanol oxidation compared to the other samples. The anodic peak currents showed a linear dependency on the square root of the scan rate, which is a characteristic of a diffusion controlled process. During CA studies, the reaction exhibited Cottrellin behavior and the diffusion coefficient of methanol was determined to be 6.25× 10-6 cm2/s and the catalytic rate constant, K, for methanol oxidation was found to be 40×107 cm3/Cmol.s）. EIS was used to investigate the catalytic oxidation of methanol on the surface of the modified electrode.

关键词： Methanol electro-oxidation Electrocatalysis Synergistic effect Nickel Modified electrode

碱性介质中(氢)氧化铜修饰电极电催化氧化蔗糖(英文)

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催化学报 2010年第11期31卷 1351-1357页

作者： majid jafarian Mehdi RASHVAND AVEI Iman DANAEE Fereydoon GOBAL Mohammad G.MAHJANI Department of Chemistry K.N.Toosi University of Technology Abadan Faculty of Petroleum Engineering Petroleum University of Technology Department of Chemistry Sharif University of Technology

A stable copper(hydr)oxide-modified electrode was prepared in 0.5 mol/L NaOH solution by cyclic voltammetry in the range of -250 to 1 000 *** can be used for electrochemical studies in the range of -250 to 1000 mV without interfering peaks because there is no oxidation of *** an anodic potential sweep,the electro-oxidation of saccharose on Cu occurred by the formation of CuⅢ and this reaction also occurred in the early stages of the reversed cycle until it is stopped by the negative potentials.A mechanism based on the electro-chemical generation of CuⅢ active sites and their subsequent consumption by saccharose was proposed,and the rate law and kinetic parameters were *** charge transfer resistance from theoretical and impedance studies was used to verify the *** chronoamperometry regimes,the reaction followed Cottrellian *** transfer of up to 21 electrons was observed in further investigations of the electro-oxidation of saccharose on a(hydr)oxide Cu rotating disk electrode.

关键词： saccharose copper(hydr)oxide equivalent circuit electrocatalytic oxidation mechanism

Simplifi ed dynamic analysis to evaluate liquefaction-inducedlateral deformation of earth slopes: a computational fluid dynamics approach

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Earthquake Engineering and Engineering Vibration 2014年第3期13卷 555-568页

作者： Yaser jafarian Ali Ghorbani Omid Ahmadi International Institute of Earthquake Engineering and Seismology P.O. Box 19395-3913 Tehran Iran Faculty of Engineering University of Guilan Rasht Iran

Lateral deformation of liquefiable soil is a cause of much damage during earthquakes, reportedly more than other forms of liquefaction-induced ground failures. Researchers have presented studies in which the liquefied soil is considered as viscous fluid. In this manner, the liquefied soil behaves as non-Newtonian fluid, whose viscosity decreases as the shear strain rate increases. The current study incorporates computational fluid dynamics to propose a simplified dynamic analysis for the liquefaction-induced lateral deformation of earth slopes. The numerical procedure involves a quasi-linear elastic model for small to moderate strains and a Bingham fluid model for large strain states during liquefaction. An iterative procedure is considered to estimate the strain-compatible shear stiffness of soil. The post-liquefaction residual strength of soil is considered as the initial Bingham viscosity. Performance of the numerical procedure is examined by using the results of centrifuge model and shaking table tests together with some field observations of lateral ground deformation. The results demonstrate that the proposed procedure predicts the time history of lateral ground deformation with a reasonable degree of precision.

关键词： liquefaction lateral ground deformation simplified dynamic analysis computational fluid dynamics

Shaking table tests on the liquefaction-induced uplift displacement of circular tunnel structure

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Underground Space 2023年第3期10卷 182-198页

作者： Saber Nokande Yaser jafarian Abdolhosein Haddad Department of Civil Engineering Semnan UniversitySemnan 35131-19111Iran International Institute of Earthquake Engineering and Seismology(IIEES) Tehran 19537-14453Iran Deltares Boussinesqweg 1DelftSouth Hollands 2629 HVNetherlands

Underground structures are susceptible to float and move upward during earthquakes when located in a liquefiable soil *** are examples of this phenomenon in past major earthquake *** this study,the uplift of circular tunnels in a liquefiable sand layer was investigated with a series of shaking table *** research has focused on the buried depth of the tunnel,tunnel diameter,tunnel weight,liquefaction extent,uplift mechanism,and factor of safety against liquefaction-induced *** to the test results,the shallow buried depth,larger diameter,and lower weight can intensify the tunnel uplift,so the displacement in post-liquefaction time continues at the same rate as during the shaking *** to the shear-induced dilation,pore water pressure generation around the tunnel was reduced compared with that of the free *** excess pore water pressure dissipation in the soil overlying the uplifted tun-nel was significant,which leads to suction in the soil ***,the acceleration response of overlying soil with the uplifted tunnel was similar to that of the free ***,the soil acceleration response around the tunnel without uplift was similar to the base motion.

关键词： Liquefaction Tunnel uplift Underground structures Shaking table test Circular tunnel

Changes in climatic conditions drive variations in arbuscular mycorrhizal fungi diversity and composition in semi-arid oak forests

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Journal of Forestry Research 2024年第5期35卷 106-119页

作者： Nahid jafarian Javad Mirzaei Reza Omidipour Yahya Kooch Department of Forest Science Faculty of AgricultureIlam UniversityIlam 69315-516Iran Department of Range and Watershed Management Faculty of AgricultureIlam UniversityIlam 69315-516Iran Faculty of Natural Resources and Marine Sciences Tarbiat Modares UniversityNoor 46417-76489MazandaranIran

Arbuscular mycorrhizal fungi(AMF)play a vital role in plant productivity and ecosystem ***,their responses to abiotic factors(i.e.,climate,physiography,and soil properties)are unknown,especially across climatic gradients and slope aspects in arid and semi-arid *** this study,using 60 composite soil samples,direct and indirect effects of climate factors and slope aspects on AMF diversity,composition and spore density were *** findings indicate that climate has a more direct influ-ence on soil properties(P<0.001)in comparison to slope aspect(P=0.449).In contrast,climate significantly affected AMF diversity and composition,with the highest diversity in dryer *** pH had the highest correlation with different facets of AMF *** equation modeling(SEM)indicated that only a small part of the variation in AMF diversity and spore density could be explained by climate characteristics,slope aspect and soil *** on SEM results,climate was the most important determinant of AMF diversity and spore density;slope aspect had a less critical *** outputs suggest that variations in AMF diversity are derived by the direct effects of climate and the indirect effect of soil chemical *** addition,with increasing dryness,sporulation and AMF diversity increased.

关键词： AMF diversity and composition Physiographic factors Semi-arid ecosystems Zagros forest

Monotonic triaxial experiments to evaluate steady-state and liquefaction susceptibility of Babolsar sand

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第10期14卷 739-750页

作者： Yaser jafarian Ali GHORBANI Siavash SALAMATPOOR Sina SALAMATPOOR International Institute of Earthquake Engineering and Seismology Faculty of Engineering University of Guilan International Branch University of Guilan

In this study,drained and undrained triaxial tests under isotropic and anisotropic consolidations were conducted on reconstituted samples of Babolsar sand,which underlies a densely populated,seismic region of the southern coast of the Caspian Sea,Mazandaran,*** was demonstrated that the sand experienced all possible states of liquefiable soil: flow failure,limited flow,and *** steady-state and flow liquefaction lines of this sand were presented and compared with previously tested *** is shown that the initial stress anisotropy can affect the potential of volume change and pore pressure *** steady-state line(SSL),however,remains identical for the isotropically and anisotropically consolidated specimens under drained and undrained *** tests data were then analyzed in order to investigate the liquefaction susceptibility of this sand in terms of parameters such as the state parameter,relative state parameter index,and lateral earth pressure ratio at failure.

关键词： Triaxial test Sand Steady-state Liquefaction susceptibility

A novel approach to determine residual stress field during FSW of AZ91 Mg alloy using combined smoothed particle hydrodynamics/neuro-fuzzy computations and ultrasonic testing

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Journal of Magnesium and Alloys 2021年第4期9卷 1311-1335页

作者： A.R.Eivani H.Vafaeenezhad H.R.jafarian J.Zhou School of metallurgy and materials engineering iran university of science and technology^nartnaktehraniran department of biomechanical engineering delft university of technologymekehveg 22628 cd delftthe netherlands

The faults in welding design and process every so often yield defective parts during friction stir welding(FSW).The development of numerical approaches including the finite element method(FEM)provides a way to draw a process paradigm before any physical *** is not practical to simulate all possible designs to identify the optimal FSW practice due to the inefficiency associated with concurrent modeling of material flow and heat dissipation throughout the *** study intends to develop a computational workflow based on the mesh-free FEM framework named smoothed particle hydrodynamics(SPH)which was integrated with adaptive neuro-fiizzy inference system(ANFIS)to evaluate the residual stress in the FSW *** integrated SPH and ANFIS methodology was established and the well-trained ANIS was then used to predict how the FSW process depends on its *** verify the SPH calculation,an itemized FSW case was performed on AZ91 Mg alloy and the induced residual stress was measured by ultrasonic *** suggested methodology can efficiently predict the residual stress distribution throughout friction stir welding of AZ91 alloy.

关键词： Friction stir welding(FSW) Smoothed particle hydrodynamics(SPH) Adaptive neuro-fuzzy inference system(ANFIS) Ultrasonic Residual stress

Diffusion bonding of Al 7075 and Mg AZ31 alloys:Process parameters, microstructural analysis and mechanical properties

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Transactions of Nonferrous Metals Society of China 2016年第7期26卷 1843-1851页

作者： Seyyed Salman SEYYED AFGHAHI Mojtaba jafarian Moslem PAIDAR Morteza jafarian Department of Engineering Faculty of Materials Science and EngineeringImam Hossein University Young Researchers and Elite Club Science and Research Branch Islamic Azad University Department of Material Engineering South Tehran Branch Islamic Azad University

Al 7075 and Mg AZ31 alloys were joined by diffusion bonding method. Joining process was performed in pressure range of 10-35 MPa at temperatures of 430-450 ℃ for 60 min under a vacuum of 13.3 MPa. The microstructure evaluation, phase analysis and distribution of elements at the interface were done using scanning electron microscopy （SEM）, energy-dispersive X-ray spectroscopy （EDS） and X-ray diffraction （XRD）. The pressure of 25 MPa was determined as the optimum pressure in which the minimum amount of plastic deformation takes place at the joint. Different reaction layers containing intermetallic compounds, such as Al12Mg17, Al3Mg2 andα（Al） solid solution, were observed, in interfacial transition zone （ITZ）. Thickness of layers was increased with increasing the operating temperature. According to the results, diffusion of aluminum atoms into magnesium alloy was more and the interface movement towards the Al alloy was observed. The maximum bond strength of 38 MPa was achieved at the temperature of 440 ℃ and pressure of 25 MPa. Fractography studies indicated that the brittle fracture originated from Al3Mg2 phase.

关键词： Al 7075 alloy Mg AZ31 alloy diffusion bonding intermetallic compounds interfacial transition zone microstructure mechanical properties

A comparative study of the electrooxidation of C1 to C3 aliphatic alcohols on Ni modified graphite electrode

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Science China Chemistry 2012年第9期55卷 1819-1824页

作者： jafarian M. MIRZAPOOR A. DANAEE I. SHAHNAZI Sangachin A.A. GOBAL F. Departement of Chemistry K.N.Toosi University of TechnologyTehranIran Abadan Faculty of Petroleum Engineering Petroleum University of TechnologyAbadanIran Departement of Chemistry Sharif University of TechnologyTehranIran

Nickel modified graphite electrodes （G/Ni） prepared by galvanostatic deposition were examined for their redox process and electrocatalytic activities towards the oxidation of methanol, ethanol, 1-propanol and 2-propanol in alkaline solutions. The methods of cyclic voltammetry （CV）, ehronoamperometry （CA） and impedance spectroscopy （EIS） were employed. In CV studies, the electrochemical response, peak current varied in the order of MeOH 〉 EtOH 〉 1-PrOH 〉 2-PrOH. Under the CA regime, a higher catalytic rate constant obtained for methanol oxidation was in agreement with CV measurements. Lower charge transfer resistance was obtained for low carbon alcohols oxidation and significantly higher exchange current density was obtained for methanol oxidation.

关键词： alcohols electrocatalytic nickel modified electrode equivalent circuit