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Effect of Wetting-Drying Cycles on Redistribution of Lead in Some Semi-Arid Zone Soils Spiked with a Lead Salt

Pedosphere 2012年第3期22卷 304-313页

作者： H.KHODAVERDILOO M.RAHMANIAN S.REZAPOUR S.GHORBANI DASHTAKI H.HADI F.X.HAN Department of Soil science Urmia UniversityUrmia 57135-165 (Iran) Department of Soil science Shahrekord UniversityShahrekord 88186/34141 (Iran) Department of Agronomy and Plant Breeding Urmia UniversityUrmia 57135-165 (Iran) Department of Chemistry and Biochemistry JacksonState UniversityJacksonMS 39217-0510 (USA)

Mobility and bioavailability of lead （Pb） could be affected considerably by soil physicochemical properties; however, less is known about the effect of Pb levels and aging time. This study was conducted to evaluate the effects of Pb levels and wetting-drying （WD） cycles on distribution and bioavailability of Pb in three semi-arid zone soils treated with different levels of Pb（NO3）2. Wetting-drying cycles simulated the actual field irrigation in the semi-arid soils. A soil with a long history of Pb contamination was also taken as a reference soil. The soils were spiked with various levels of Pb and incubated under WD cycles for 160 d. Sequential extractions and batch sorption experiments were performed to assess the fractionation of Pb in the spiked soils. Redistribution index （Uts） and reduced partitioning parameter （IR） were applied to semi-quantify the distribution of Pb in the spiked soils. A small amount of Pb sorbed was desorbed by the soils, indicating a strong and irreversible binding of Pb in the studied soils. Contribution of carbonate-bound （Car） and residual （Res） Pb fl＇actions to the total Pb of the soils was more than 97%. The Car, soluble plus exchangeable （SE）, and organic matter-bound （OMB） fractions of Pb were transferred to the Res fraction under the WD cycles. The IR and Uts values were influenced by Pb loading levels and WD; therefore, the Pb lability and/or redistribution pattern could semi-quantitatively be assessed via these parameters. At the end of the experiment, the Ia and Uts values for the Pb salt-spiked soils did not show the quasi- equilibrium state. The lability of Pb in the soils decreased with increasing incubation time and showed a strong dependence on Pb levels and soil chemical composition. WD cycles significantly affected the overall lability of Pb in soils through influencing the redistribution of Pb among solid-phase components.

关键词： bioavailability heavy metals mobility redistribution index reduced partitioning parameter

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Selective methanation of carbon monoxide in hydrogen rich stream over Ni/CeO_2 nanocatalysts

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Journal of Rare Earths 2015年第6期33卷 619-628页

作者： Behzad Nematollahi Mehran Rezaei Ebrahim Nemati Lay Catalyst and Advanced Materials Research Laboratory Chemical Engineering Department Faculty of Engineering University of Kashan Institute of Nanoscience and Nanotechnology University of Kashan

In the present work, selective methanation of carbon monoxide in hydrogen rich stream was investigated over Ni/CeO2 nanocatalysts. The obtained results revealed that increasing in nickel loading decreased the BET surface area, pore vohune and nickel dispersion. The 25%Ni/CeO2 with a NiO crystal size of 12 nm exhibited the highest activity in CO methanation reaction and reached to maximum CO conversion and CH4 selectivity at temperatures above 230 ℃. The catalytic results revealed that CO selective methanation well progressed at lower temperatures while CO2 methanation was completely suppressed until CO conversion reached to maximum value.

关键词： methanation nickel cerium oxide high surface area carbon monoxide rare earths

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Functionalization of nitrogen-doped graphene quantum dot:A sustainable carbon-based catalyst for the production of cyclic carbonate from epoxide and CO_(2)

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Journal of Environmental sciences 2023年第4期126卷 408-422页

作者： Zahra Eshaghi Gorji Abbas Ali Khodadadi Siavash Riahi Timo Repo Yadollah Mortazavi Marianna Kemell Catalysis and Nanostructured Materials Research Laboratory School of Chemical EngineeringCollege of EngineeringUniversity of TehranTehran ***Iran Department of Chemistry University of HelsinkiHelsinki 00014Finland Institute of Petroleum Engineering School of Chemical EngineeringCollege of EngineeringUniversity of TehranTehran ***Iran

A series of organic compounds were successfully immobilized on an N-doped graphene quantum dot (N-GQD) to prepare a multifunctional organocatalyst for coupling reaction between CO_(2)and propylene oxide (PO).The simultaneous presence of halide ions in conjunction with acidic-and basic-functional groups on the surface of the nanoparticles makes them highly active for the production of propylene carbonate (PC).The effects of variables such as catalyst loading,reaction temperature,and structure of substituents are *** proposed catalysts were characterized by different techniques,including Fourier transform infrared spectroscopy (FTIR),field emission scanning electron microscopy/energy dispersive X-ray microanalysis (FESEM/EDX),thermogravimetric analysis (TGA),elemental analysis,atomic force microscopy (AFM),and ultraviolet–visible (UV-Vis) *** optimal reaction conditions,3-bromopropionic acid (BPA) immobilized on N-GQD showed a remarkable activity,affording the highest yield of 98%at 140℃ and 106Pa without any co-catalyst or *** new metal-free catalysts have the advantage of easy separation and reuse several *** on the experimental data,a plausible reaction mechanism is suggested,where the hydrogen bonding donors and halogen ion can activate the epoxide,and amine functional groups play a vital role in CO_(2)adsorption.

关键词： Heterogeneous organocatalyst CO_(2) Propylene carbonate N-doped graphene quantum dot Nanomaterials

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Propane catalytic cracking on pretreated La-ZSM-5 zeolite during calcination for light olefins production

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Journal of Rare Earths 2017年第6期35卷 542-550页

作者： Roya Pouria Leyla Vafi Ramin Karimzadeh Department of Chemical Engineering Tarbiat Modares University Jalal AlAhmad Highway P.O. Box 14155-4838 Tehran Iran

The purpose of this study was to increase light olefins yield and selectivity in catalytic cracking of propane. Pretreatment of ZSM-5 zeolite was performed during calcination. First, lanthanum was loaded on the catalyst by wet impregnation method and then the effect of parameters, such as temperature（400–800 oC）, time（120–480 min） and type of stream, on La-ZSM-5 zeolite was examined during calcination using central composite design（CCD） method. Based on the proposed models, the optimized condition for maximizing selectivity of light olefins for air stream was 680 oC and 310 min and for the nitrogen stream was 735 oC and 173 min that under these conditions, selectivity amount increased 24% for nitrogen stream and 19% for air stream as compared with H-ZSM-5 catalyst. The synthesized catalysts were characterized by X-ray diffraction（XRD） and temperature-programmed desorption（TPD） techniques. According to the results of NH3-TPD, as the temperature increased, the number of strong acid sites（specially Bronsted acid sites） reduced and resulted in increased production of light olefins as well as catalyst stability. Accordingly, stability of the samples calcined with nitrogen stream was higher than the samples calcined with the air stream.

关键词： calcination cracking selectivity zeolite calcined impregnation programmed lanthanum loaded propane

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Manufacturing of cast A356 matrix composite reinforced with nano- to micrometer-sized SiC particles

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Rare Metals 2017年第1期36卷 46-54页

作者： Reza Taherzadeh Mousavian Rasoul Azari Khosroshahi Sasan Yazdani Dermot Brabazon Faculty of Materials Engineering Sahand University of Technology Tabriz 65175-4171 Iran Advanced Processing Technology Research Centre School of Mechanical and Manufacturing Engineering Dublin City University Dublin 9 Ireland

In this study, large micron-sized Si C particles were fragmented via ball-milling process in the presence of iron and nickel powders, separately, to fabricate composite powders of Fe–Si C and Ni–Si C. Continuous fracturing of brittle Si C powders leads to the formation of multi-modalsized Si C powders with size of from 50 nm to slightly higher than 10 lm after 36-h ball milling. The milled powders were then incorporated into the semisolid melt of A356 aluminum alloy to ease the incorporation of fine Si C particles by using iron and nickel as their carrier *** final as-cast composites were then extruded at 500 °C with a reduction ratio of 9:1. Lower-sized composite powders with slight agglomeration are obtained for the36-h milled Ni–Si C mixture compared to that of Fe–Si C powders, leading to incorporation of Si C particles into the melt with a lower size and suitable distribution for the Ni–Si C mixture. It is found that lower-sized composite particles could release the fine Si C particles into the melt more easily, while large agglomerated composite particles almost remain in its initial form, resulting in sites of stress concentration and low-strength aluminum matrix composites. Ultimate tensile strength(UTS) and yield strength(YS) values of 243 and 135 MPa, respectively, are obtained for the aluminum matrix composite in which nickel acts as the carrier of fine ceramic particles.

关键词： Aluminum matrix composite Semisolid casting Extrusion Ni Fe

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Mechanical properties and in vivo biodegradability of Mg-Zr-Y-Nd-La magnesium alloy produced by a combined severe plastic deformation

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Rare Metals 2021年第3期40卷 651-662页

作者： A.Torkian G.Faraji M.S.Pedram School of Mechanical Engineering College of EngineeringUniversity of TehranTehran 11155-4563Iran Department of Veterinary Surgery and Radiology Faculty of Veterinary MedicineUniversity of Tehran14199-63111Iran

Permanent implants are going to be replaced by the implementation of biodegradable magnesium-based implants in fixation of internal bone fractures because of many concerns associated with conventional ***,biodegradable magnesium-based biomaterials exhibit higher biodegradation rate and low mechanical properties which are the main *** work aims to almost overcome both disadvantageous by grain refining of a WE43 magnesium alloy containing 93.04 wt% Mg,4.12 wt% Y,2.15 wt% Nd,0.43 wt% Zr,and 0.26 wt%*** this study,the consequences of combined severe plastic deformation(SPD) on the mechanical properties,microstructure,and in vivo degradation behavior of WE43 magnesium alloy were *** do so,WE43 magnesium alloy was chosen and processed through multipass equal channel angular pressing(ECAP) at 330℃ for up to four passes followed by an extrusion *** results showed that higher strength and hardness with minimum ductility less was obtained in the sample processed via two-pass ECAP followed by *** vivo biodegradation experiments showed higher degradation rate for the unprocessed coarse-grained(CG) WE43 *** two-pass ECAP and extruded sample with ultrafine-grained(UFG) structure exhibited the lowest in vivo biodegradation rate besides appropriate mechanical *** may be concluded that the WE43 magnesium alloy processed via two-pass ECAP and extrusion could be a very promising candidate for biodegradable implants from both mechanical and biocorrosion viewpoints.

关键词： Implant Severe plastic deformation WE43 Grain refinement Hardness Mechanical properties

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Mechanical and Microstructural Properties of Ultra-fine Grained AZ91Magnesium Alloy Tubes Processed via Multi Pass Tubular Channel Angular Pressing(TCAP)

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Journal of Materials science & Technology 2014年第2期30卷 134-138页

作者： G.Faraji P.Yavari S.Aghdamifar M.Mosavi Mashhadi Department of Mechanical Engineering University College of EngineeringUniversity of Tehran Department of Mechanical and Aerospace Engineering Science and Research BranchIslamic Azad University

Ultra-fine grained （UFG） cylindrical tubes were produced via recently developed tubular channel angular pressing （TCAP） process through different passes from as-cast AZ91 magnesium alloy. The microstructure and mechanical properties of processed tube through one to four passes of TCAP process at 200℃ were investigated. Microhardness of the processed tube was increased to 98.5 HV after one pass from an initial value of 67 Hr. An increase in the number of passes from one to higher number of passes has no more effect on the microhardness. Yield and ultimate strengths were increased by 4.3 and 1.4 times compared to those in as-cast condition. Notable increase in the strength was achieved after one pass of TCAP while higher number of passes has no more effect. Microstructural investigation shows notable decrease in the grain size to around 500 nm from the primary value of - 150 μm. Dissolution and distribution of hard MglTAI12 phase in the grain boundaries of dynamically recrystallized UFG AZ91 with a mean grain size of - 500 nm was an interesting issue of TCAP processing at 200 ℃ compared to other severe plastic deformation processes.

关键词： Severe plastic deformation Tubular channel angular pressing AZ91 Grain refinement Mechanical behaviour

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Josephson current versus potential strength of the interface in ferromagnetic superconductors

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Chinese Physics B 2014年第5期23卷 537-541页

作者： Hamidreza Emamipour Department of Physics Ilam University

Based on the scattering theory, we calculate the Josephson current in a junction between two ferromagnetic super-conductors as a function of the interface potential z. We consider the ferromagnetic superconductor （FS） in three different Cooper pairing states： spin singlet s-wave pairing （SWP） state, spin triplet opposite spin pairing （OSP） state, and spin triplet equal spin pairing （ESP） state. We find that the critical Josephson current as a function of z shows clear differences among the SWP, OSP, and ESP states. The obtained results can be used as a useful tool for determining the pair symmetry of the ferromagnetic superconductors.

关键词： ferromagnetic superconductors spin singlet s-wave pairing state spin triplet opposite spin pairingstate spin triplet equal spin pairing state

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An investigation on multilayer shape memory polymers under finite bending through nonlinear thermo-visco-hyperelasticity

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Applied Mathematics and Mechanics(English Edition) 2023年第1期44卷 73-88页

作者： A.BAKHTIYARI M.BAGHANI S.SOHRABPOUR School of Mechanical Engineering College of EngineeringUniversity of TehranTehran ***Iran Department of Mechanical Engineering Sharif University of TechnologyTehran ***Iran

This study presents a semi-analytical solution to describe the behavior of shape memory polymers(SMPs) based on the nonlinear thermo-visco-hyperelasticity which originates from the concepts of internal state variables and rational *** method is developed for the finite bending of multilayers in a dual-shape memory effect(SME) *** layer number and layering order are investigated for two different SMPs and a hyperelastic *** addition to the semi-analytical solution,the finite element simulation is performed to verify the predicted results,where the outcomes demonstrate the excellent accuracy of the proposed solution for predicting the behavior of the multilayer *** this method has a much lower computational cost than the finite element method(FEM),it can be used as an effective tool to analyze the SMP behavior under different conditions,including different materials,different geometries,different layer numbers,and different layer arrangements.

关键词： smart material shape memory polymer(SMP) semi-analytical solution thermo-visco-hyperelasticity finite strain bending

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Full Polysaccharide Crosslinked-chitosan and Silver Nano Composites, for Use as an Antibacterial Membrane

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Chinese Journal of Polymer science 2016年第8期34卷 949-964页

作者： Hossein Ghasemzadeh Mahdieh Sheikhahmadi Fatemeh Nasrollah Department of chemistry Imam Khomeini International University

Full polysaccharide crosslinked-chitosan membranes were prepared by crosslinking of chitosan with chitosan dialdehyde followed by reduction with sodium borohydride. Partially oxidized chitosan, generated from periodate oxidation of chitosan, was used as a crosslinker. The modulus values and elongation at break were increased with increasing the crosslinker weight ratio. The rheological measurements showed that depolymerization of chitosan can take place rapidly in the presence of the oxidizing agent. The weight reduction of crosslinked-chitosan membrane after 12 h, at pH = 4 and pH = 2 was found to be 85.0% and 90.0%, respectively. The structure of the crosslinked-chitosan and the silver nanocomposite were confirmed by FTIR spectroscopy, scanning electron microscopy （SEM）, and thermogravimetric analysis （TGA）. Transmission electron microscopy （TEM） reveals the presence of well-separated Ag nanoparticles with diameters in the range of 4-10 nm. The silver ion loading increases with increasing the silver ion concentration, and decreasing the crosslink density. The MBC/MIC ratio of 2.0, 2.0, and 1.0 was achieved for E. coli, S. aureus, and P. aeruginosa, respectively.

关键词： Silver nanocomposites Chitosan Crosslinking Antibacterial effects.

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