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silicones
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Dissimilar gas tungsten arc weld-brazing of Al/steel using Al-Si filler metal: microstructure and strengthening mechanisms
, Article Journal of Alloys and Compounds ; Volume 749 , 15 June , 2018 , Pages 121-127 ; 09258388 (ISSN) ; Abbasi, M ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
In this paper gas tungsten arc welding (GTAW) was applied to dissimilar lap joining of Al6061 and Zn-coated galvanized low carbon steels using Al-5 wt% Si filler metal. The joining mechanism was based on a hybrid brazing/welding mechanism. Three factors contributed to the joint strength including (i) low heat input rate of GTAW process which reduce the intermetallic compound layer growth during joining, (ii) the special role of Si in the filler metal which was able to change the nature of reaction layer from predominantly η-Al5Fe2 phase to predominately less brittle Al-Fe-Si phase and (iii) the flux-like action of Zn-coating which ensures complete wetting of steel surface by Al melt. It was...
Integer-forcing message recovering in interference channels
, Article IEEE Transactions on Vehicular Technology ; Volume 67, Issue 5 , May , 2018 , Pages 4124-4135 ; 00189545 (ISSN) ; Hejazi, M ; Makki, B ; Nasiri Kenari, M ; Svensson, T ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
In this paper, we propose a scheme referred to as integer-forcing message recovering (IFMR) to enable receivers to recover their desirable messages in interference channels. Compared to the state-of-the-art integer-forcing linear receiver (IFLR), our proposed IFMR approach needs to decode considerably less number of messages. In our method, each receiver recovers independent linear integer combinations of the desirable messages each from two independent equations. We propose an efficient polynomial-time algorithm to sequentially find the equations and integer combinations with maximum rates and analyze its complexity. We evaluate the performance of our scheme and compare the results with the...
A high-performance polydimethylsiloxane electrospun membrane for cell culture in lab-on-a-chip
, Article Biomicrofluidics ; Volume 12, Issue 2 , April , 2018 ; 19321058 (ISSN) ; Saidi, M. S ; Kashaninejad, N ; Nguyen, N. T ; Sharif University of Technology
American Institute of Physics Inc
2018
Abstract
Thin porous membranes are important components in a microfluidic device, serving as separators, filters, and scaffolds for cell culture. However, the fabrication and the integration of these membranes possess many challenges, which restrict their widespread applications. This paper reports a facile technique to fabricate robust membrane-embedded microfluidic devices. We integrated an electrospun membrane into a polydimethylsiloxane (PDMS) device using the simple plasma-activated bonding technique. To increase the flexibility of the membrane and to address the leakage problem, the electrospun membrane was fabricated with the highest weight ratio of PDMS to polymethylmethacrylate (i.e., 6:1...
Performance optimization of a plasmonic coupler based on a lossy transmission line
, Article Journal of Nanophotonics ; Volume 12, Issue 2 , May , 2018 ; 19342608 (ISSN) ; Faez, R ; Sharif University of Technology
SPIE
2018
Abstract
The modal analysis of a lossy coupled plasmonic waveguide consisting of two graphene sheets sandwiched among three SiO 2 layers is presented. This analysis extracts even and odd complex propagation constants in addition to even and odd characteristic impedances at various Fermi levels. It is shown that the first even mode is lossless in theory, but other modes are very lossy. Taking into account the losses, first, the transmission line (RLCG) model, including self and mutual elements, is constructed for various Fermi levels and frequencies. Then, the length of a lossy plasmonic directional coupler based on the coupled plasmonic waveguide is designed for a variety of Fermi levels. The...
Engineering of mature human induced pluripotent stem cell-derived cardiomyocytes using substrates with multiscale topography
, Article Advanced Functional Materials ; Volume 28, Issue 19 , 2018 ; 1616301X (ISSN) ; Garbern, J. C ; Behzadi, S ; Hill, M. J ; Tresback, J. S ; Heydari, T ; Ejtehadi, M. R ; Ahmed, N ; Copley, E ; Aghaverdi, H ; Lee, R. T ; Farokhzad, O. C ; Mahmoudi, M ; Sharif University of Technology
Wiley-VCH Verlag
2018
Abstract
Producing mature and functional cardiomyocytes (CMs) by in vitro differentiation of induced pluripotent stem cells (iPSCs) using only biochemical cues is challenging. To mimic the biophysical and biomechanical complexity of the native in vivo environment during the differentiation and maturation process, polydimethylsiloxane substrates with 3D topography at the micrometer and sub-micrometer levels are developed and used as cell-culture substrates. The results show that while cylindrical patterns on the substrates resembling mature CMs enhance the maturation of iPSC-derived CMs, sub-micrometer-level topographical features derived by imprinting primary human CMs further accelerate both the...
Constrained groove pressing, cold-rolling, and post-deformation isothermal annealing: Consequences of their synergy on material behavior
, Article Materials Chemistry and Physics ; Volume 206 , 2018 , Pages 85-93 ; 02540584 (ISSN) ; Jandaghi, M. R ; Heidarzadeh, A ; Jandaghi, M. M ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Stress-relieved Al-Mn-Si specimens were constrained groove pressed (CGPed) and in the following, cold-rolled under different strains of 0.47, 0.8 and 1.27. Dual strained sheets were isothermally heat treated at 150, 250, and 350 °C. Microstructure survey revealed that generated shear-bands by CGP acted as talent sites for further strain-induced grain boundary migration (SIGBM) during annealing. SEM micrographs pointed out that coarse particles (1 μm <) had not preferential positions within the aluminum matrix and often comminuted into fine dispersoids (0.5 μm >) under heavy strains. Assessment of the softening fraction (Rrec) depicted that greater accumulated strains along with higher...
A comparative evaluation of the additional impact of nanometer-sized tetravalent oxides on the performance of doloma-magnesia ceramic refractories
, Article Ceramics International ; Volume 44, Issue 2 , 2018 , Pages 2058-2064 ; 02728842 (ISSN) ; Gheisari Dehsheikh, H ; Karamian, E ; Nemati, A ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
In this research study, a comparative evaluation of the additional impact of nanometer-sized tetravalent oxides [Zirconia (ZrO2), Titania (TiO2), and Silica (SiO2)] on the properties and performance of Doloma-Magnesia (MgO-CaO) ceramic refractories, with an emphasis on their hydration resistance improvement, has been done. For this purpose, from 0 to 2.5 wt% ZrO2, TiO2, and SiO2 nanometer-sized particles have been added to the Doloma-Magnesia compositions. After formulation and mixing of the starting materials, the pressed samples (at 150 MPa) were tempered (at 250 °C for 12 h) and fired in a shuttle furnace (at 1650 °C for 3 h). The physical, mechanical, and thermo-mechanical properties of...
Effect of precipitation hardening heat treatment on mechanical and microstructure features of dissimilar friction stir welded AA2024-T6 and AA6061-T6 alloys
, Article Journal of Manufacturing Processes ; Volume 31 , 2018 , Pages 214-220 ; 15266125 (ISSN) ; Jashnani, H. R ; Paidar, M ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
The friction stir welding of AA2024-T6 to AA6061-T6 plates with a 4 mm thickness has been studied at constant traverse and rotational speeds of 1000 rpm and 100 mm/min, respectively. The position of alloys and the effects of precipitation hardening heat treatment in retreating and advancing side in the friction stir welding were analyzed. The tool with taper threaded pin was used for welding. Macro and microstructural analysis were investigated by using Optical and Field Emission-Scanning Electron Microscopes (FE-SEM) to check out the welded joints. Micro-hardness and Tensile tests were also done to study mechanical attributes of the joints. Microstructural analysis revealed some grain...
Supersolidus liquid phase sintering of Al6061/SiC metal matrix composites
, Article Powder Metallurgy ; Volume 52, Issue 1 , 2009 , Pages 28-35 ; 00325899 (ISSN) ; Simchi, A ; Sharif University of Technology
2009
Abstract
The aim of the present work is to study the effect of reinforcement content and sintering temperature on the densification and microstructural development during sintering of Al6061/SiC composite compacts. Prealloyed Al6061 powder was mixed with various amounts of SiC particles up to 27 vol.-% and compacted at 350 MPa. Sintering was carried out in a dry nitrogen atmosphere at 580-620°C. It was shown that the presence of SiC particles retards the densification of the prealloyed powder during solid phase sintering and liquid phase sintering. This effect is particularly noticeable at SiC fractions higher than ∼9 vol.-%, at which continuous networks of the hard particles are formed. Increasing...
Effect of bonding temperature on microstructure development during TLP bonding of a nickel base superalloy
, Article Journal of Alloys and Compounds ; Volume 469, Issue 1-2 , 2009 , Pages 270-275 ; 09258388 (ISSN) ; Ekrami, A ; Kokabi, A. H ; Sharif University of Technology
2009
Abstract
The effect of bonding temperature on microstructure of a transient liquid phase (TLP)-bonded GTD-111 nickel base superalloy, using a Ni-Si-B interlayer, was investigated. At low bonding temperatures microstructure of the joint centerline is controlled by B diffusion. However, at high bonding temperature effect of base metal alloying elements on the joint microstructure development was more pronounced. Effects of bonding temperature on the formation of secondary precipitates in diffusion-affected zone and isothermal solidification time were also analyzed. It was found that above a critical temperature, formation of borides in diffusion-affected zone is suppressed and the time required for...
Finite-element analysis of platinum-based cone microelectrodes for implantable neural recording
, Article 2009 4th International IEEE/EMBS Conference on Neural Engineering, NER '09, Antalya, 29 April 2009 through 2 May 2009 ; 2009 , Pages 395-398 ; 9781424420735 (ISBN) ; Frounchi, J ; Jahed, N ; Tinati, M. A ; National Institutes of Health, NIH; National Institute of Neurological Disorders and Stroke, NINDS; National Science Foundation, NSF ; Sharif University of Technology
2009
Abstract
There have been significant advances in fabrication of high-density microelectrode arrays using silicon micromachining technology in neural signal recording systems. The interface between microelectrodes and chemical environment brings great interest to researchers working on extracellular stimulation. This interface is quite complex and must be modeled carefully to match experimental results. Computer simulation is a method to increase the knowledge about these arrays and to this end the finite element method provides a strong environment for investigation of relative changes of the electrical field extension surrounding an electrode positioned in chemical environment. In this paper FEM...
Improved adhesion of NiTi wire to silicone matrix for smart composite medical applications
, Article Materials and Design ; Volume 30, Issue 9 , 2009 , Pages 3667-3672 ; 02641275 (ISSN) ; Hassanzadeh Nemati, N ; Bagheri, R ; Sharif University of Technology
2009
Abstract
Recent uses of intelligent composites in biomedical appliances aggrandize the necessity of bonding-strength improvement in NiTi/silicone matrix interface. SEM micrographs and pull-out tests are employed to determine the strength of the NiTi/silicone bonds in a flexible composite piece. Greater adhesion strengths are obtained due to the presence of thin oxide layer, surface roughness and frictional forces between the embedded-wires and the contacting phase. Effect of curing treatment on phase transformation temperatures of the wires is determined by electrical resistivity (ER) measurements. Results show that the curing treatment shifts the transition points of the wires towards higher...
Influence of SiC nanoparticles and saccharin on the structure and properties of electrodeposited Ni-Fe/SiC nanocomposite coatings
, Article Journal of Alloys and Compounds ; Volume 484, Issue 1-2 , 2009 , Pages 540-544 ; 09258388 (ISSN) ; Vaezi, M. R ; Nikzad, L ; Yazdani, B ; Sadrnezhaad, S. K ; Sharif University of Technology
2009
Abstract
In this study, Ni-Fe/SiC nanocomposite coatings with smooth and crack-free surface were successfully prepared by means of the conventional electrodeposition in the presence of saccharin in electrolyte. The goal of this work was to investigate the effect of SiC nanoparticles and saccharin on the structure and properties of permalloy nanocomposite coatings. The nanocomposite coatings were characterized using optical and scanning electron microscopy, energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD) technique. The significant variation in the crystallographic texture of the coatings was observed due to the addition of SiC nanoparticles and saccharin in the electrodeposition...
Analysis of the effect of reinforcement particles on the compressibility of Al-SiC composite powders using a neural network model
, Article Materials and Design ; Volume 30, Issue 5 , 2009 , Pages 1518-1523 ; 02641275 (ISSN) ; Sanjari, M ; Simchi, A ; Sharif University of Technology
2009
Abstract
A neural network (ANN) model was developed to predict the densification of composite powders in a rigid die under uniaxial compaction. Al-SiC powder mixtures with various reinforcement volume fractions (0-30%) and particle sizes (50 nm to 40 μm) were prepared and their compressibility was studied in a wide range of compaction pressure up to 400 MPa. The experimental results were used to train a back propagation (BP) learning algorithm with two hidden layers. A sigmoid transfer function was developed and found to be suitable for analyzing the compressibility of composite powders with the least error. The trained model was used to study the effect of reinforcement particle size and volume...
An investigation on microstructure evolution, mechanical properties, and strain aging of Mg-1.8Zn-0.7Si-0.4Ca biomedical alloy processed by equal channel angular pressing
, Article Journal of Materials Engineering and Performance ; Volume 28, Issue 8 , 2019 , Pages 5207-5219 ; 10599495 (ISSN) ; Karimi Taheri, K ; Karimi Taheri, A ; Shaeri, M. H ; Sharif University of Technology
Springer New York LLC
2019
Abstract
The influence of equal channel angular pressing (ECAP) on microstructure and mechanical behavior, as well as, strain aging during ECAP and post-ECAP of Mg-1.8Zn-0.7Si-0.4Ca biomedical alloy was examined. The alloy in solid solution heat-treated condition was processed by ECAP with route BC at 350 and 400 °C. The specimens ECAPed at 350 °C were aged at 125 and 150 °C for different times. The hardness and shear punch test results indicated that performing ECAP at 350 °C for 4 passes increases the hardness and shear strength of the alloy from 48 HV and 110 MPa to 71 HV and 188 MPa, respectively. It was revealed that the average grain size of the alloy decreases from 78 µm to about 3 µm after 4...
Supported PtxPd1-x bimetallic nanoparticles on ionic liquid-functionalized SiO2@graphene oxide nanocomposite and its application as an effective multiphasic catalyst
, Article Applied Catalysis A: General ; Volume 579 , 2019 , Pages 30-43 ; 0926860X (ISSN) ; Giannakis, S ; Gholami, M. R ; Sharif University of Technology
Elsevier B.V
2019
Abstract
In this work, PtxPd1-x (x = 0, 0.5, and 1)nanoparticles (NPs)were synthesized on the surface of SiO2@graphene oxide which covered by 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6)ionic liquid (IL)layer. FT-IR spectroscopy, zeta potential, CHN elemental analysis, XRD, XPS, SEM, EDX, TEM, TGA, BET, and ICP-AES techniques were applied for the characterization of the multiphasic catalyst. The as-prepared nanocomposite was used as an effective heterogeneous catalyst for the oxidation of cyclohexene by molecular oxygen, as a green oxidant. Different experimental conditions such as oxygen pressure, reaction time, reaction temperature and amount of catalyst were investigated in this...
Low-overhead thermally resilient optical network-on-chip architecture
, Article Nano Communication Networks ; Volume 20 , 2019 , Pages 31-47 ; 18787789 (ISSN) ; Koohi, S ; Hessabi, S ; Sharif University of Technology
Elsevier B.V
2019
Abstract
Integrated silicon photonic networks have attracted a lot of attention in the recent decades due to their potentials for low-power and high-bandwidth communications. However, these promising networks, as the future technology, are drastically susceptible to thermal fluctuations, which may paralyze wavelength-based operation of these networks. In this regard, precise addressing of thermally induced faults in optical networks-on-chip (ONoCs), as well as revealing practical methods to tackle this challenge will be a break-even point toward implementation of this technology. In this paper, thermal variation is investigated through analyzing on-chip power distribution, which is addressed by power...
A numerical study of dust deposition effects on photovoltaic modules and photovoltaic-thermal systems
, Article Renewable Energy ; Volume 135 , 2019 , Pages 437-449 ; 09601481 (ISSN) ; Hakkaki Fard, A ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
Dust deposition on the surface of solar systems is one of the main parameters that significantly affects the performance of such systems. In this study, the effect of dust deposition density on the performance of photovoltaic modules (PV) and photovoltaic-thermal systems (PVT) is numerically investigated. Accordingly, all layers of a monocrystalline silicon PV module for both systems are simulated. Moreover, the effect of various system parameters on the performance of both clean and dusty PV module and PVT system are studied. The studied parameters included: solar radiation intensity, ambient temperature, coolant inlet temperature, and coolant inlet velocity. The obtained results indicate...
Effect of interphase zone on the overall elastic properties of nanoparticle-reinforced polymer nanocomposites
, Article Journal of Composite Materials ; Volume 53, Issue 9 , 2019 , Pages 1261-1274 ; 00219983 (ISSN) ; Jam, J. E ; Arab, B ; Firouz Abadi, R. D ; Sharif University of Technology
SAGE Publications Ltd
2019
Abstract
In the current work, the effect of interphase region on the mechanical properties of polymer nanocomposites reinforced with nanoparticles is studied. For this purpose, a closed-form interphase model as a function of radial distance based on finite-size representative volume element is suggested to estimate the mechanical properties of particle-reinforced nanocomposites. The effective Young’s and shear moduli of thermoplastic polycarbonate-based nanocomposites for a wide range of sizes and volume fractions of silicon carbide nanoparticles are investigated using the proposed interphase model and molecular dynamics simulations. In order to investigate the effect of particle size, several unit...
The effects of thymus plant extracts on single breast cancer cell morphology in the microfluidic channel
, Article 2018 IEEE EMBS Conference on Biomedical Engineering and Sciences, IECBES 2018, 3 December 2018 through 6 December 2018 ; 2019 , Pages 647-651 ; 9781538624715 (ISBN) ; Mansor, M. A ; Alsadat Rad, M ; Soo-Beng Khoo, A ; Ahmad, M ; Marzuki, M ; Physiological Measurement; Sarawak Convention Bureau ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
Microfluidics based systems could be useful for drug discovery as they allow for miniaturization and could potentially be run as multiple parallel cell based assays. Such miniaturization allows assays at single cell level and reduces the amount of test material needed, which, in the case of natural product extracts, simplifies the preparation. Thyme species extracts have been reported to show some promising anti-cancer effects. In the present work, we used a microfluidics based system to study the effects of Thymus kotschyanusm Boiss plant extract on two human breast cancer cells lines which are MDA-MB-231 and MCF-7. For better understanding a single cancer cell death mechanism and a flow...