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A self-healing and bioactive coating based on duplex plasma electrolytic oxidation/polydopamine on AZ91 alloy for bone implants

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Journal of Magnesium and Alloys 2023年第2期11卷 592-606页

作者： Safoora Farshid Mahshid Kharaziha masoud Atapour Department of Materials Engineering Isfahan University of TechnologyIsfahan84156-83111Iran

Magnesium(Mg) alloys are well-known in biomedical materials owing to their elastic module near to bone, biocompatibility and biodegradation properties. Nevertheless, poor corrosion resistance hinders their biomedical applications. Besides, it is necessary to endow Mg alloys with bioactive property, which is crucial for temporary bone implants. Here, a self-healing, corrosion resistant and bioactive duplex coating of plasma electrolytic oxidization(PEO)/polydopamine(PDA) is applied on AZ91 substrate using PEO and subsequent electrodeposition process. Moreover, the role of different electrodeposition times(60 s, 120 s) and dopamine concentrations(1 and 1.5 mg/ml) to improve corrosion resistance, bioactivity, biocompatibility and self-healing property and its mechanism are investigated. The results indicate that the PEO coating is efficiently sealed by the PDA, depending on the electrodeposition parameters. Noticeably, electrodeposition for 120 s in dopamine concentration of 1 mg/ml(120T-1C) results in the formation of uniform and crack-free PDA coating. Duplex PEO/PDA coatings reveal high bioactivity compared to PEO coating, owing to electrostatic interaction between PDA top-layer and calcium and phosphate ions as well as high hydrophilicity of coatings. In addition, duplex PEO/PDA coatings also show improved and more stable protective performance than the PEO and bare alloy, depending on the PDA deposition parameters. Noticeably, the corrosion current density of the 120T-1C decreases one orders of magnitude compared to PEO. In addition, the presence of a broad passivation region in the anodic polarization branch shows durable self-healing property via Zipper-like mechanism, demonstrating the duplex coating could preserve promising corrosion ***, the cytocompatibility of duplex coated samples is also confirmed via interaction with MG63 cells. In summary, the PEO/PDA coating with great corrosion protection, self-healing ability, bioactivity and bioco

关键词： Magnesium alloy Plasma electrolytic oxidation Polydopamine Self-healing Bioactivity Orthopedic applications

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Permeation properties of CO2 and CH4 in asymmetric polyethersulfone/ polyesterurethane and polyethersulfone/polyetherurethane blend membranes

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Chinese Journal of Chemical Engineering 2017年第12期25卷 1750-1759页

作者： Shadi Hasanajili masoud Latifzadeh Mahmoud Bahmani Chemical and Petroleum Engineering School Shiraz University 71248-51154 Shiraz lran

The transport performances of carbon dioxide and methane were studied in polyethersulfone, polyethersulfone/polyeterurethane(PES–ETPU) and polyethersulfone/polyestherurethane(PES–ESPU) blend membranes separately with different compositions. The variations in the structural characteristics of PES membrane after incorporation of ESPU and ETPU were investigated by different techniques. Additionally, the effect of pressure and composition on the permeance of CO_2, CH_4 and ideal selectivity of CO_2/CH_4 were checked on the *** results revealed that the morphology of the blend membranes was affected by two opposite factors: thermodynamic enhancement and kinetic hindrance. The membranes with denser sponge layers were formed at lower ratio of PU/PES, while more porous structure with enlarged macrovoids membranes were observed at higher PU content. The results indicated that adding PU to PES membrane, caused permeance improvement of the gases with nearly no change and/or reduction in ideal selectivity of CO_2/CH_4. Moreover, PES–ETPU membranes showed higher permeability and less CO_2/CH_4 selectivity in comparison with PES–ESPU samples. For PES–ESPU membrane containing 1.5% ESPU, CO_2 permeance at 10 bar was improved up to 20% with almost no change in CO_2/CH_4 selectivity with respect to PES. Finally, response surface methodology was used to evaluate the effects of the operating parameters on the permeance and ideal selectivity.

关键词： Absorption Membranes Size distribution RSM Polyethersulfone Polyurethane

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Effect of geofoam as cover material in cut and cover tunnels on the seismic response of ground surface

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Earthquake Engineering and Engineering Vibration 2022年第1期21卷 67-80页

作者： Sadri Shadabi masoud Rabeti Moghadam Mansour Parvizi Department of Civil Engineering Faculty of EngineeringYasouj UniversityYasouj 0098Iran

In recent years,special attention has been given to the effects of underground spaces and structures on the seismic response of adjacent ***,to the best of the authors′knowledge,no method has yet been considered to reduce these effects in technical *** present study aims to investigate the role of geofoam as the cover material in cut and cover tunnels on the seismic response of the ground *** this purpose,a numerical study was performed using FLAC 2D,a finite difference software,and verified against previous *** effects of parameters such as the geofoam type,thickness of the geofoam blocks and interfaces between the blocks,on the ground surface amplification pattern were *** studies demonstrate that the geofoam has a strong potential to attenuate the seismic horizontal movements of the ground *** the thickness of the geofoam blocks is decreased,its attenuation ability is *** was also determined that the interface between the geofoam blocks plays a key role in the attenuation of the aboveground seismic *** on the results,it was concluded that geofoam is a proper material to attenuate seismic amplifications at the ground surface,induced by underground tunnels.

关键词： cut and cover tunnel ground surface seismic response amplification ratio geofoam attenuation

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Numerical modeling and experimental validation of microstructure in gray cast iron

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International Journal of Minerals,Metallurgy and Materials 2012年第10期19卷 908-914页

作者： masoud Jabbari Parviz Davami Naser Varahram Department of Mechanical Engineering Technical University of DenmarkKgs.Lyngby 2800Denmark Department of Materials Science and Engineering Sharif University of TechnologyTehran 11365Iran

To predict the amount of different phases in gray cast iron by a finite difference model （FDM） on the basis of cooling rate （R）, the volume fractions of total y phase, graphite, and cementite were calculated. The results of phase composition were evaluated to find a proper correlation with cooling rate. More trials were carried out to find a good correlation between the hardness and phase composition. New proposed formulas show that the hardness of gray cast iron decreases as the amount of graphite phase increases, and increases as the amount of cementite inereases. The,qe fnrrnulas are develoned to correlate the nhase volume fraction to hardness. The results are compared with exverimental data and show reasonable agreement.

关键词： cast iron cooling microstructure mechanical properties finite difference method

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Gas–liquid flow mass transfer in a T-shape microreactor stimulated with 1.7 MHz ultrasound waves

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Chinese Journal of Chemical Engineering 2017年第9期25卷 1143-1152页

作者： Mona Akbari masoud Rahimi Mahboubeh Faryadi CFD Research Center Chemical Engineering Department Razi University

This paper describes the application of ultrasound waves on hydrodynamics and mass transfer characteristics in the gas–liquid flow in a T-shape microreactor with a diameter of 800 μm. A 1.7 MHz piezoelectric transducer(PZT) was employed to induce the vibration in this microreactor. Liquid side volumetric mass transfer coefficients were measured by physical and chemical methods of CO_2 absorption into water and Na OH solution. The approach of absorption of CO_2 into a 1 mol·L^(-1) Na OH solution was used for analysis of interfacial areas. With the help of a photography system, the fluid flow patterns inside the microreactor were analyzed. The effects of superficial liquid velocity, initial concentration of Na OH, superficial CO_2 gas velocity and length of microreactor on the mass transfer rate were investigated. The comparison between sonicated and plain microreactors(microreactor with and without ultrasound) shows that the ultrasound wave irradiation has a significant effect on kLa and interfacial area at various operational conditions. For the microreactor length of 12 cm, ultrasound waves improved kLa and interfacial area about 21% and 22%, respectively. From this study, it can be concluded that ultrasound wave irradiation in microreactor has a great effect on the mass transfer rate. This study suggests a new enhancement technique to establish high interfacial area and kLa in microreactors.

关键词： Ultrasound waves Microreactor Gas–liquid flow Mass transfer Absorption

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Pseudo-in-situ stir casting: a new method for production of aluminum matrix composites with bimodal-sized B_4C reinforcement

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International Journal of Minerals,Metallurgy and Materials 2016年第8期23卷 981-990页

作者： Mohammad Raei masoud Panjepour Mahmood Meratian Department of Materials Engineering Isfahan University of Technology

A new method was applied to produce an Al-0.5wt%Ti-0.3wt%Zr/5vol%B_4C composite via stir casting with the aim of characterizing the microstructure of the resulting composite. For the production of the composite, large B4 C particles（larger than 75 μm） with no pre-heating were added to the stirred melt. Reflected-light microscopy, X-ray diffraction, scanning electron microscopy, field-emission scanning electron microscopy, laser particle size analysis, and image analysis using the Clemex software were performed on the cast samples for microstructural analysis and phase detection. The results revealed that as a consequence of thermal shock, B_4 C particle breakage occurred in the melt. The mechanism proposed for this phenomenon is that the exerted thermal shock in combination with the low thermal shock resistance of B_4 C and large size of the added B_4 C particles were the three key parameters responsible for B_4 C particle breakage. This breakage introduced small particles with sizes less than 10 μm and with no contamination on their surfaces into the melt. The mean particle distance measured via image analysis was approximately 60 μm. The coefficient of variation index, which was used as a measure of particle distribution homogeneity, showed some variations, indicating a relatively homogeneous distribution.

关键词： metal matrix composites particle-reinforced composites boron carbide casting thermal shock

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Introducing a proper hydrogen liquefaction concept for using wasted heat of thermal power plants-case study: Parand gas power plant

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Chinese Journal of Chemical Engineering 2021年第12期34卷 187-196页

作者： Hamed Rezaie Azizabadi masoud Ziabasharhagh Mostafa Mafi Faculty of Mechanical Engineering K.N.Toosi University of TechnologyTehranIran Department of Mechanical Engineering Imam Khomeini International UniversityQazvinIran

A hydrogen liquefaction concept with an innovative configuration and a capacity of 4 kg·s^(-1)(345.6 t·d^(-1))is *** concept involves an ammonia absorption refrigeration system for the pre-cooling of hydrogen and MR streams from 25℃ to-30℃.The ammonia absorption refrigeration system is fed by exhaust gases of the Pa rand gas power plant that are normally dissipated to the environment with a temperature of 546℃.The simulation is performed by Aspen HYSYS V9.0,using two separate equations of state for simulating hydrogen and MR streams to gain more accurate results especially for ortho-para *** show that conversion enthalpy estimated by Aspen HYSYS,fits very well to the experimental *** the important independent variables and composition of MRs are done using trial and error procedure,a functional and straightforward method for complicated *** minimum temperature limit in the cooling section is lowered,and an ortho-para converter is implemented in this *** proposed concept performs well from energy aspects and leads to COP and SEC equal to 0.271 and 4.54 kW·h·kg^(-1),*** main advantage of this study is in the low SEC,eliminating the losses of the distribution network,and improving the ability of the hydrogen liquefaction for energy storage in off-peak times.

关键词： Hydrogen Liquefaction Absorption refrigeration Waste treatment Mixed-refrigerant Ortho-para conversion

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Partially decoupling and collar bonding of the encapsulated rebar rockbolts to improve their performance in seismic prone deep underground excavations

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International Journal of Mining Science and Technology 2019年第3期29卷 409-418页

作者： Reza masoudi Mostafa Sharifzadeh masoud Ghorbani Department of Mining & Metallurgical Engineering Curtin UniversityWestern Australian School of Mines (WASM)Australia Department of Mining Metallurgy and Petroleum EngineeringAmirkabir University of Technology (Tehran Polytechnic)TehranIran

Rockbolt is widely employed all over the world as an effective ground reinforcement element in order to secure the underground *** encapsulated rebar or rebar rockbolt is most popular and commonly used as reinforcement in a ground support system because of its accessibility,cost effectiveness and easy *** elements in a seismic condition such as rock burst have to dissipate the energy release of the dynamic impact via their deformation and ultimate load capacity,knowing that the former is more *** other words,achieving early stiff behaviour along with large deformation capacity in rockbolts are the goals for new development in rock *** rockbolts are expensive while some of them have large deformation capability with low ultimate load *** this paper,modifications were made on encapsulation of rebar rockbolts to utilise it effectively as a yielding reinforcement in seismic *** a sufficient decoupled length in the shank of rebar rockbolts which industry has regularly been using to control the bulking of the stress fractured ground,improves the deformation capacity of the ***,leaving a collar bonding underneath of the bearing pad and plate removes the weaknesses of the head anchorage of *** the dynamic performance of the bolt is improved by these easily applicable *** behaviour and performance of encapsulated rockbolts have been discussed first,then the effects of modifications are *** proposed modification of the rebars is not only cost effective but also easy to apply in the field and improves the performance of reinforcements in seismic prone zones.

关键词： Rockbolt Tunnel support Collar bonding Seismic rock support Tunnelling

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Amberlyst-15 as a recyclable heterogeneous catalyst for synthesis of N-tert-butylamides via Ritter-type reaction

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Chinese Chemical Letters 2012年第3期23卷 293-296页

作者： masoud Mokhtary Gholamreza Goodarzi Department of Chemistry Rasht BranchIslamic Azad UniversityRashtIran Department of Chemistry Amol BranchIslamic Azad UniversityAmolIran

Highly efficient method for the preparation of N-tert-butylamides by reaction of nitriles with tert-butylacetate is described using Amberlyst-15 as a recyclable heterogeneous *** amidation of benzonitrile in the prese... 详细信息

关键词： Modified Ritter reaction Amberlyst-15 Nitrites tert-Butylacetate N-tert-Butylamides

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Experimental study on the effects of artificial bed roughness on turbidity currents over abrupt bed slope change

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International Journal of Sediment Research 2020年第3期35卷 256-268页

作者： Sara Baghalian masoud Ghodsian Civil and Environmental Engineering Tarbiat Modares University Civil and Environmental Engineering and Water Engineering Research Institute Tarbiat Modares University

A series of experimental observations are presented in the current study to discuss the effects of artificial bed roughness on the turbidity current flowing in a rectangular channel with an abrupt change in bed *** this purpose,two different types of elements,sinusoidal and trapezoidal,with various heights and arrangements are considered as artificial bed roughness.A Vectrino velocity meter was used to measure the velocity and sediment concentration *** effects of inlet sediment concentration on front velocity,body velocity,unit discharge,sediment concentration,and suspended load transport rate also were *** equations were developed for estimation of the velocity of a turbidity current over smooth and rough *** unexpected experimental results showed that unlike the effect of roughness height,a change in the roughness arrangement has no significant influence on the velocity of a turbidity ***,the effect of bed roughness on the front velocity of a denser current is more significant.

关键词： Experimental analysis Turbidity current Bed roughness Slope break Velocity profile Concentration profile

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