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Facile synthesis, morphology and structure of Dy_2O_3 nanoparticles through electrochemical precipitation

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Rare Metals 2016年第8期35卷 637-642页

作者： Taher Yousefi Meisam Torab-Mostaedi Abolfazl Aghaei Hossein ghasemi-Mobtaker Nuclear Fuel Cycle Research School Nuclear Science and Technology Research Institute

The aim of this research was to introduce a new, facile and simple method for synthesis of Dy203 nanostructures at room temperature. For the first time, galvanostatic electrodeposition was used to synthesize Dy203 particles, and the influence of the current density on the structure and morphology of the product was studied. The samples were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM） and Brunauer-Emmett-Teller （BET）. The results show that the current density has little effect on the chemical composi- tion but great effect on the structure and morphology of the samples. The average size of the particles decreases as the applied current density increases. The grain size of as- prepared samples decreases from 500 to 70 nm when the current density increases from 0.5 to 6.0 ***-a. To obtain oxide product, the as-prepared samples were heat- treated at 1,000 ℃. The results show that the heat-treated samples have smaller particles. The XRD results show that the similar patterns are observed in the samples synthesized at different current densities, and the only difference from the JCPDS card is the ratio of peak intensities. With the increase in the current density, a decrease in the current efficiency is observed.

关键词： Dy203 Nanoparticle Electrodeposition Nanostructures Rare earth

Coupling system application in photocatalytic degradation of methylorange by TiO_2, TiO_2/SiO_2 and TiO_2/SiO_2/Ag

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Rare Metals 2015年第12期34卷 851-858页

作者： Hossein ghasemi Mobtaker Seyed Javad Ahmadi Shahram Moradi Dehaghi Taher Yousefi Nuclear Fuel Cycle Research School Nuclear Science and Technology Research Institute Faculty of Chemistry Tehran North Branch Islamic Azad University

Three different photocatalysts including TiO2, TiO2/SiO2 and TiO2/SiO2/Ag were synthesized via sol–gel growth method, in which colloidal silica was used as Si source, titanium tetra iso-propoxide (TTiP) as titanium source, Ag+ as dopant ion and hydroxypropyl cellulose (HPC) as dispersant. The purpose was to study the enhancement of photocatalytic activity of TiO2 by deposition on SiO2 colloids and also doping with Ag ion. The catalysts were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray fluorescence (XRF), Fourier transform infrared spectroscopy (FT-IR) and Brunauer–Emmett–Teller (BET) methods. It is confirmed that the major phase in all catalysts is anatase. Photocatalytic activity was studied in various conditions for degradation of methylorange (as a model pollutant) to evaluate the effect of some parameters on degradation efficiency. Studying the degradation process in various pH values reveals that the degradation is more efficient in acidic solution than alkaline condition. Coupling the photocatalytic process with some fields called electro-photochemical (EP), magnetic-photochemical (MP) and ultrasonic-photochemical (UP) was studied at two pH values which were compared with photochemical (P) alone. It is concluded that in most cases, the EP is the best coupled system and has the maximum efficiency. Liquid chromatography–mass spectrometry (LC–MS) analysis was used to check the complete decomposition of methylorange at the end of process.

关键词： Doping Electro-photochemical Magnetic-photochemical Ultrasonic-photochemical Sol–gel

Effect of Catalyst on the Formation of Silica Coating on Nickel Substrate by Sol-Gel Processing

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材料热处理学报 2004年第5B期25卷 1295-1298页

作者： Ali ghasemi F.Ashrafizadeh M.A.Golozar AH Ashrafi Materials Engineering Department Isfahan University of Technology Isfahan IranMaterials Engineering Department Isfahan University of Technology Isfahan IranMaterials Engineering Department Isfahan University of Technology Isfahan IranMaterials Engineering Department Isfahan University of Technology Isfahan Iran

In this research work silica coating was produced on nickel substrates by a sol-gel process. In order to increase the rate of hydrolysis and to reduce the rate of polymerization several acid catalysts including nitric acid-hydrochloric acid, acetic acid, hydrochloric acid and nitric acid were add to silica sol. Conversely, in order to control the rate of hydrolysis and to increase the rate of polymerization, basic catalyst of ammonia and ammonia hydroxyl were introduced in to the solution. Nickel specimens of known surface roughness were chemically cleaned and prepared by dipping in the sols. In order to produce a suitable silica coating the drying and firing cycles were optimized on these substrates. The structure and uniformity of the coatings produced were examined by scanning electron microscopy. Coatings composition was determined using glow discharge optical spectroscopy and EDAX microanalysis. Experimental result showed that hydrochloric acid, acetic acid, ammonia and acetic acid - ammonia are suitable catalytic agents for silica coating formation on nickel type substrate.

关键词：溶胶凝胶催化剂镍合金硅涂覆

Influence of initial microstructure and grain size on transformation of bainite to austenite in large size forgings

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Journal of Iron and Steel Research International 2018年第5期25卷 554-562页

作者： Emna Ben Fredj Hadi ghasemi Nanesa Mohammad Jahazi Jean-Benoit Morin Department of Mechanical Engineering Ecole deTechnologie Superieure Montreal QC H3C 1K3 Canada Finkl Steel-Sorel St-Joseph-de-Sorel QC J3R 3M8 Canada

The kinetics of austenite formation in the surface and center regions of a 40 t forged ingot of a high-strength medium- carbon low-alloy steel was studied using high-resolution dilatometry. The starting microstructures from the surface or center regions had different proportions of bainite and residual austenite as well as different prior austenite grain sizes. Two heating rates representing the actual heating rates in the surface （5℃ s -1） and center regions （0.5℃ s -1） of large size forged blocks were utilized. Dilatometric curves revealed only one transformation step of austenite formation at both heating rates independent of grain size or proportion of phases. Optical microscopy, field emission gun scanning electron microscopy and X-ray diffraction were used to study microstructure evolution and confirm the results obtained by dilatometry. The kinetic parameters for austenite formation were determined from the dilatometry data by Johnson-Mehl- Avrami-Kolmogorov （JMAK） equation. The JMAK coefficients were determined for each condition of the investigated steels. The calculations indicated that the nucleation and growth of austenite in the surface region were accelerated more than 10,000 times due to a significantly smaller average prior austenite grain size, stability of initial retained austenite, and accumulation of coarse carbides at the surface. The results were discussed in the framework of classical nucleation and growth theories using the kinetic parameters for austenite formation.

关键词： Large size ingot Medium-carbon low-alloy steel Initial microstructure Grain size Austenite formation

Biostratigraphy and Mass Extinction Pattern across the Cretaceous/Paleogene Boundary, Northern Alborz, Iran

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Open Journal of Geology 2013年第1期3卷 33-38页

作者： Masoud Asgharian Rostami Mohammad Vahidinia Ebrahim ghasemi-Nejad abbas Sadeghi Faculty of Science Department of Geology Ferdowsi University of Mashhad Mashhad Iran Faculty of Science Department of Geology Shahid Beheshti University Tehran Iran Faculty of Science Department of Geology University of Tehran Tehran Iran

High resolution sampling across the Cretaceous/Paleogene boundary (K/Pg) at the Galanderud section in northern Iran provides the most expanded and continuous section for us to consider biostratigraphy and the mass extinction pattern of Cretaceous planktic foraminifera. Based on planktic foraminifera, four biozones and five sub-biozones have been identified across the K/Pg boundary. These biozones include the Abathomphalus mayaroensis Biozone (Plummerita hantkeninoides subbiozone), the Guembelitria cretacea Biozone (including two sub-biozones: the Hedbergella holmdelensis and the Parvularugoglobigerina longiapertura), the Parvularugoglobigerina eugubina Biozone (including two subbiozones: the Parvularugoglobigerina Sabina and the Eoglobigerina simplicissima) and finely the Parasubbotina pseudobulloides Biozone. Planktic foraminiferal extinction occurred over a brief period, with 3% of the species disappearing in the late Maastrichtian, and 72% of the species becaming extinct at the K/Pg boundary. About 25% of the species survived into the early Danian. Extinction of 73% of the species at the K/Pg boundary is very compatible with the effect of a large asteroid impact.

关键词： Biostratigraphy Mass Extinction Pattern Cretaceous/Paleogene Boundary Northern Alborz Iran

Optimization of design parameters for controlled rocking steel braced dual-frames

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Earthquake Engineering and Engineering Vibration 2022年第4期21卷 1053-1068页

作者： Sobhan ghasemi M.Firoozi Nezamabadi Abdolreza S.Moghadam Mahmood Hosseini Department of Civil Engineering South Tehran BranchIslamic Azad UniversityTehranIran Structural Engineering Research Center International Institute of Earthquake Engineering and Seismology(IIEES)TehranIran

A controlled rocking concentrically steel braced frame(CR-CSBF)is introduced as an alternative to conventional methods to prevent major structural damage during large *** is equipped with elastic post-tensioned(PT)cables and replaceable devices or fuses to provide overturning resistance and dissipate energy,*** CR-CSBFs are not officially legalized in globally valid codes for new buildings,it is expected to be presented in them in the near *** main goal of this study is to determine the optimal design parameters consist of the yield strength and modulus of elasticity of the fuse,the initial force of the PT cable,and the gravity load on the rocking column,considering different heights of the frame,spanning ratios and ground motion types for dual-configuration *** time-history analyses are performed in *** study aims to define the optimal input variables as effective design parameters of CR-CSBFs by comparing four seismic responses consisting of story drift,roof displacement,roof acceleration and base shear,and also using the Euclidean metric optimization *** the previous research,this study is innovative and first of its *** results demonstrate that the optimal design parameters are variable for various conditions.

关键词： self-centering rocking steel braced frame design parameters optimization low damage

Efficient approaches of determining the motion of a spherical particle in a swirling fluid flow using weighted residual methods

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Particuology 2015年第6期13卷 68-74页

作者： Seiyed E. ghasemi M. Vatani D.D. Ganji Young Researchers and Elite Club Qaemshahr Branch Islamic Azad University Qaemshahr lran Department of Mechanical Engineering Babol University of Technology Babol lran

The motion of a spherical particle released in a swirling fluid flow is studied employing the least-squares method and method of moments. The governing equations are obtained and solved employing the two methods. The accuracy of the results is examined against the results of a fourth-order Runge-Kutta numer- ical method. The effects of various parameters, namely the initial radius, initial radial velocity, initial angular velocity, and drag-to-inertia ratio, on the non-dimensional velocity profiles and particle position distribution are considered. The results show that the radial velocity increases over time while the angular velocity decreases, and that an increase in the initial radial velocity increases the particle radial distance and angular velocity but decreases the radial velocity profile.

关键词： Spherical particle Swirling flow Radial velocity Angular velocity Least-squares method Method of moments

Effect of Pyrrole and N-Methylpyrrole Coatings on Corrosion Resistance of Mild Steel

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材料热处理学报 2004年第5B期25卷 1137-1141页

作者： Ali Ashrafi M.A.Golozar S.Mallakpour Ali ghasemi Department of Materials Engineering Isfahan University of Technology Isfahan 84154 Iran Organic Polymer Chemistry Research Laboratory College of Chemistry Isfahan University of Technology Isfahan 84156 Iran

Electrochemical polymerizations of various ratios of pyrrole and methylpyrrole monomers were performed in aqueous toluene-4-sulfinic acid sodium salt (T4SNa) electrolyte, using galvanostatic method. pH of electrolyte was adjusted by p-toluene sulfonic acid (PTSA). In order to prevent corrosion of mild steel substrates during coating deposition, specimens were pretreated in 0.5M oxalic acid solution, employing galvanostatic method. This would passivate the steel substrate and facilitate the coating process as well. Corrosion resistance of coated substrates was investigated in 1M NaCl solution using Tafel polarization technique. In addition, using scanning electron microscopy (SEM), morphological characterization of coatings produced, was investigated. Regarding the corrosion characteristics, results obtained revealed that the ratio of 1 to 1 (Pyrrole/Methylpyrrole) could play an important role.

关键词：导电聚合物电引发聚合吡咯耐蚀性低碳钢

Three-Dimensional Isogeometric Analysis of Flexoelectricity with MATLAB Implementation

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Computers, Materials & Continua 2020年第11期65卷 1157-1179页

作者： Hamid ghasemi Harold S.Park Xiaoying Zhuang Timon Rabczuk Department of Mechanical Engineering Arak University of TechnologyArak38181-41167Iran Department of Mechanical Engineering Boston UniversityBostonMA 02215USA Division of Computational Mechanics Ton Duc Thang UniversityHo Chi Minh CityVietnam Faculty of Civil Engineering Ton Duc Thang UniversityHo Chi Minh CityVietnam Department of Computer Engineering College of Computer and Information SciencesKing Saud UniversityRiyadhSaudi Arabia Institute of Structural Mechanics Bauhaus-Universität WeimarWeimarD-99423Germany

Flexoelectricity is a general electromechanical phenomenon where the electric polarization exhibits a linear dependency to the gradient of mechanical strain and vice *** truncated pyramid compression test is among the most common setups to estimate the flexoelectric *** present a three-dimensional isogeometric formulation of flexoelectricity with its MATLAB implementation for a truncated pyramid *** educational purposes,this paper presents a precise computational model to illustrate how the localization of strain gradients around pyramidal boundary shapes contributes in generation of electrical *** MATLAB code is supposed to help learners in the Isogeometric Analysis and Finite Elements Methods community to learn how to solve a fully coupled problem,which requires higher order approximations,*** complete MATLAB code which is available as source code distributed under a BSD-style license,is provided in the part of Supplementary Materials of the paper.

关键词： Flexoelectricity Isogeometric Analysis(IGA) MATLAB B-spline elements finite elements coupled electromechanical problem