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    Foamability and compressive properties of AlSi7-3 vol.% SiC-0.5 wt.% TiH2 powder compact

    , Article Materials Letters ; Volume 62, Issue 10-11 , 2008 , Pages 1561-1564 ; 0167577X (ISSN) Esmaeelzadeh, S ; Simchi, A ; Sharif University of Technology
    This paper presents experimental results on the foaming behavior and compressive properties of AlSi7-3 vol.% SiC metal foam. Elemental powders of Al, Si, SiC and TiH2 were mixed, hot compacted and foamed at 750, 780 and 810 °C. It was shown that the addition of fine SiC particles (mean diameter of 3 μm) increases the melt expansion and improves the stability of AlSi7 foam. A less drainage in the cell structure was also noticed. Meanwhile, large irregular cells in the macrostructure and a slight degradation of the mechanical properties under compressive load were observed. © 2007 Elsevier B.V. All rights reserved  

    A 32kb 90nm 10T-cell sub-threshold SRAM with improved read and write SNM

    , Article 2013 21st Iranian Conference on Electrical Engineering ; May , 2013 ; 9781467356343 (ISBN) Hassanzadeh, S ; Zamani, M ; Hajsadeghi, K ; Sharif University of Technology
    The constraints of power saving have compelled SRAM designers to consider sub-threshold area as a viable choice. The biggest barrier of this progress is the stability of SRAM's cells and the correct operations. In this paper a 10T cell structure has been proposed with 90% read and 50% write SNM improvement in comparison to the conventional 6T cell. The hold SNM value is about the 6T cell SRAM. Also using differential read method in the proposed structure causes high read performance and using simpler sense amplifier. The symmetric configuration of this structure helps the SRAM has simpler layout and lower transistor mismatch. Using 90nm TSMC CMOS, 32kb 10T cell SRAM in sub-threshold area is... 

    Endothelial cells morphology in response to combined wss and biaxial cs: introduction of effective strain ratio

    , Article Cellular and Molecular Bioengineering ; Volume 13, Issue 6 , 2020 , Pages 647-657 Pakravan, H. A ; Saidi, M. S ; Firoozabadi, B ; Sharif University of Technology
    Springer  2020
    Introduction: Endothelial cells (ECs) morphology strongly depends on the imposed mechanical stimuli. These mechanical stimuli include wall shear stress (WSS) and biaxial cyclic stretches (CS). Under combined loading, the effect of CS is not as simple as pure CS. The present study investigates the morphological response of ECs to the realistic mechanical stimuli. Methods: The cell population is theoretically studied using our previous validated model. The mechanical stimuli on ECs are described using four parameters; WSS magnitude (0 to 2.0 Pa), WSS angle (− 50° to 50°), and biaxial CS in two perpendicular directions (0 to 10%). The morphology of ECs is reported using four parameters; average... 

    Effect of ceramic particle addition on the foaming behavior, cell structure and mechanical properties of P/M AlSi7 foam

    , Article Materials Science and Engineering A ; Volume 424, Issue 1-2 , 2006 , Pages 290-299 ; 09215093 (ISSN) Esmaeelzadeh, S ; Simchi, A ; Lehmhus, D ; Sharif University of Technology
    The effects of SiC addition on the foaming behavior and compressive properties of AlSi7 metal foams were studied. Elemental powders of Al, Si, SiC and TiH2 were mixed, hot compacted and foamed at temperatures between 750 and 810 °C. The role of SiC volume fraction up to 10 vol.% and its particle size (3, 8 and 16 μm) was investigated. It was found that the foaming behavior of AlSi7 alloy, i.e. the maximum foam expansion and its stability, depends on the size and volume fraction of SiC particles. Increasing the amount of the ceramic particles and/or decreasing the particle size leads to less melt drainage whilst the cell structure becomes non-uniform. This is attributed to the effect of the... 

    Effect of two steps annealing on the microstructure and dynamic strain aging behavior of Al-6Mg alloy

    , Article Materials Science and Engineering A ; Volume 798 , 2020 Saadat, Z ; Khani Moghanaki, S ; Kazeminezhad, M ; Goodarzi, M ; Ghiasi Afjeh, S. M. B ; Sharif University of Technology
    Elsevier Ltd  2020
    The microstructure of cold rolled Al–6Mg alloy is investigated after two steps annealing at different coupled temperatures of 250–320 °C and 320–400 °C for various times. Dynamic strain aging behavior in terms of serrated flow and strain rate sensitivity is investigated. The effect of three microstructural features, cell structure, recovered and recrystallized microstructures, on the strain rate sensitivity is elucidated. Two steps annealing process is utilized to capture the effect of recovery and precipitation phenomena on recrystallization and dynamic strain aging behaviors. The results show that the negative strain rate sensitivity of cold rolled specimen increases to positive values in... 

    Fabrication of granulated NaY zeolite nanoparticles using a new method and study the adsorption properties

    , Article Powder Technology ; Volume 231 , November , 2012 , Pages 1-6 ; 00325910 (ISSN) Charkhi, A ; Kazemeini, M ; Ahmadi, S. J ; Kazemian, H ; Sharif University of Technology
    NaY zeolite nanoparticles were synthesized and shaped into the uniform spherical granules using a developed novel and simple two-step granulation technique. First, the alginate/nanozeolite or alginate/nanozeolite-bentonite spherical hybrid was successfully fabricated, and then the alginate was decomposed by calcinations resulting uniform spherical granules. To improve the mechanical stability of the prepared granules, bentonite was added as an inorganic binder at different ratios of 20wt.% to 40wt.%. Moreover, the effect of binder on the ion exchange properties of the prepared granules was studied. Increasing of binder content from 20wt.% to 40wt.% linearly enhanced the mechanical stability... 

    Dye-sensitized solar cells based on a single layer deposition of TiO 2 from a new formulation paste and their photovoltaic performance

    , Article Solar Energy ; Volume 86, Issue 9 , 2012 , Pages 2654-2664 ; 0038092X (ISSN) Mohammadi, M. R ; Louca, R. R. M ; Fray, D. J ; Welland, M. E ; Sharif University of Technology
    A new strategy for enhancing the efficiency and reducing the production cost of TiO 2 solar cells by design of a new formulated TiO 2 paste with tailored crystal structure and morphology is reported. The conventional three- or four-fold layer deposition process was eliminated and replaced by a single layer deposition of TiO 2 compound. Different TiO 2 pastes with various crystal structures, morphologies and crystallite sizes were prepared by an aqueous particulate sol-gel process. Based on simultaneous differential thermal (SDT) analysis the minimum annealing temperature to obtain organic-free TiO 2 paste was determined at 400°C, being one of the lowest crystallization temperatures of TiO 2... 

    A new structure to increase the photostability of CdTe quantum dot sensitized solar cells

    , Article Journal of Physics D: Applied Physics ; Volume 44, Issue 4 , January , 2011 ; 00223727 (ISSN) Samadpour, M ; Iraji zad, A ; Taghavinia, N ; Molaei, M ; Sharif University of Technology
    In this paper a new cell structure is introduced to reduce the rate of CdTe corrosion in quantum dot sensitized solar cells (QDSSCs) using I -/I- 3 electrolyte. In this cell, one electrode is a titania nanorod that was sensitized with CdTe quantum dots as the working electrode. A thin gold layer is sputtered on the electrode to act as a protective layer against the I-/I- 3 corrosive electrolyte and to passivate the CdTe surface traps which are the main recombination centres in a QDSSC. In addition, a Schottky barrier formed at the interface of Au and CdTe prevents direct electron recombination from the CdTe conduction band with I- 3 ions. The mechanism of charge transfer and quantum dot... 

    The effects of recombination lifetime on efficiency and JV characteristics of InxGa1-xN/GaN quantum dot intermediate band solar cell

    , Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 42, Issue 9 , July , 2010 , Pages 2353-2357 ; 13869477 (ISSN) Es'Haghi Gorji, N ; Movla, H ; Sohrabi, F ; Hosseinpour, A ; Rezaei, M ; Babaei, H ; Sharif University of Technology
    We introduce a new third generation of solar cell structure which inserts different-sized quantum dots in the active region of a pin structure. Generating an intermediate band in the bandgap of the host material makes a good overlap with a part of solar spectrum. The effect of the recombination mechanisms on efficiency and currentvoltage characteristics of this intermediate band solar cell is calculated. We deduce that the increase in recombination lifetime of the excited carriers can improve the characteristics of this structure. This result can be a route which helps us to take the effect on solar cell characteristics into consideration  

    A mechanical model for morphological response of endothelial cells under combined wall shear stress and cyclic stretch loadings

    , Article Biomechanics and Modeling in Mechanobiology ; Volume 15, Issue 5 , 2016 , Pages 1229-1243 ; 16177959 (ISSN) Pakravan, H. A ; Saidi, M. S ; Firoozabadi, B ; Sharif University of Technology
    Springer Verlag 
    The shape and morphology of endothelial cells (ECs) lining the blood vessels are a good indicator for atheroprone and atheroprotected sites. ECs of blood vessels experience both wall shear stress (WSS) and cyclic stretch (CS). These mechanical stimuli influence the shape and morphology of ECs. A few models have been proposed for predicting the morphology of ECs under WSS or CS. In the present study, a mathematical cell population model is developed to simulate the morphology of ECs under combined WSS and CS conditions. The model considers the cytoskeletal filaments, cell–cell interactions, and cell–extracellular matrix interactions. In addition, the reorientation and polymerization of... 

    PLGA/TiO2 nanocomposite scaffolds for biomedical applications: Fabrication, photocatalytic, and antibacterial properties

    , Article BioImpacts ; Volume 11, Issue 1 , 2021 , Pages 45-52 ; 22285652 (ISSN) Pelaseyed, S. S ; Madaah Hosseini, H. R ; Nokhbedehghan, Z ; Samadikuchaksaraei, A ; Sharif University of Technology
    Tabriz University of Medical Sciences  2021
    Introduction: Porous 3D scaffolds synthesized using biocompatible and biodegradable materials could provide suitable microenvironment and mechanical support for optimal cell growth and function. The effect of the scaffold porosity on the mechanical properties, as well as the TiO2 nanoparticles addition on the bioactivity, antimicrobial, photocatalytic, and cytotoxicity properties of scaffolds were investigated. Methods: In the present study, porous scaffolds consisting poly (lactide-co-glycolide) (PLGA) containing TiO2 nanoparticles were fabricated via air-liquid foaming technique, which is a novel method and has more advantages due to not using additives for nucleation compared to former... 

    Modification of rock/fluid and fluid/fluid interfaces during MEOR processes, using two biosurfactant producing strains of Bacillus stearothermophilus SUCPM#14 and Enterobacter cloacae: A mechanistic study

    , Article Colloids and Surfaces B: Biointerfaces ; Vol. 117 , May , 2014 , pp. 457-465 ; ISSN: 09277765 Sarafzadeh, P ; Zeinolabedini Hezave, A ; Mohammadi, S ; Niazi, A ; Ayatollahi, S ; Sharif University of Technology
    During any microbial enhanced oil recovery process, both cells and the metabolic products of bacteria govern the tertiary oil recovery efficiency. However, very accurate examination is needed to find the functionality of these tiny creatures at different reservoir conditions. In this regard, the effect of cell structure on ultimate microbial recovery efficiency which is the most dominant mechanism based on the microorganism types (gram-negative or gram-positive) was systematically investigated. At the first stage, possible different active mechanisms using Bacillus stearothermophilus SUCPM#14 strain were tested using specially designed injection protocol, in situ and ex situ core flooding... 

    Chitosan-gelatin sheets as scaffolds for muscle tissue engineering

    , Article Artificial Cells, Nanomedicine and Biotechnology ; Volume 43, Issue 2 , Nov , 2015 , Pages 124-132 ; 21691401 (ISSN) Hajiabbas, M ; Mashayekhan, S ; Nazaripouya, A ; Naji, M ; Hunkeler, D ; Rajabi Zeleti, S ; Sharifiaghdas, F ; Sharif University of Technology
    Informa Healthcare  2015
    Hydrogels made of natural polymers [chitosan (CS) and gelatin (G)] have been prepared having mechanical properties similar to those of muscle tissues. In this study, the effect of polymer concentration and scaffold stiffness on the behavior of seeded muscle-derived cells (MDCs) on the CS-G hydrogel sheets has been evaluated. Both variables were found to be important in cell viability. Viability was assessed by observation of the cell morphology after 1 day as well as a 14-day MTT assay. The CS-G hydrogels were characterized using Fourier transform infrared (FTIR) analysis, which revealed evidences of strong intermolecular interactions between CS and G. Hydrogel samples with intermediate... 

    Physical, morphological, and biological studies on PLA/nHA composite nanofibrous webs containing equisetum arvense herbal extract for bone tissue engineering

    , Article Journal of Applied Polymer Science ; Volume 134, Issue 39 , 2017 ; 00218995 (ISSN) Khakestani, M ; Jafari, S. H ; Zahedi, P ; Bagheri, R ; Hajiaghaee, R ; Sharif University of Technology
    A series of herbal extract incorporated into poly(lactic acid) (PLA) composite nanofibrous scaffolds were successfully prepared by using electrospinning technique. Equisetum arvense extract (EE) and nanohydroxyapatite (nHA) in different quantities were loaded into PLA solution to fabricate composite nanofibrous webs under various electrospinning conditions. Uniform nanofibers were obtained with an average diameter of 157 ± 47 nm in the case of those containing the herbal extract. Characterization of the webs was carried out by means of Fourier transform infrared (FTIR) spectroscopy, field emission-scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), and... 

    Cell shape affects nanoparticle uptake and toxicity: An overlooked factor at the nanobio interfaces

    , Article Journal of Colloid and Interface Science ; Volume 531 , 2018 , Pages 245-252 ; 00219797 (ISSN) Farvadi, F ; Ghahremani, M. H ; Hashemi, F ; Hormozi Nezhad, M. R ; Raoufi, M ; Zanganeh, S ; Atyabi, F ; Dinarvand, R ; Mahmoudi, M ; Sharif University of Technology
    Academic Press Inc  2018
    Hypothesis: It is now being increasingly accepted that cells in their native tissue show different morphologies than those grown on a culture plate. Culturing cells on the conventional two-dimensional (2D) culture plates does not closely resemble the in vivo three-dimensional (3D) structure of cells which in turn seems to affect cellular function. This is one of the reasons, among many others, that nanoparticles uptake and toxicology data from 2D culture plates and in vivo environments are not correlated with one another. In this study, we offer a novel platform technology for producing more in vivo-like models of in vitro cell culture. Experiments: The normal fibroblast cells (HU02) were... 

    Fully-coupled mathematical modeling of actomyosin-cytosolic two-phase flow in a highly deformable moving Keratocyte cell

    , Article Journal of Biomechanics ; Volume 67 , January , 2018 , Pages 37-45 ; 00219290 (ISSN) Nikmaneshi, M. R ; Firoozabadi, B ; Saidi, M. S ; Sharif University of Technology
    Elsevier Ltd  2018
    Interaction between intracellular dynamics and extracellular matrix (ECM) generally occurred into very thin fragment of moving cell, namely lamellipodia, enables all movable cells to crawl on ECM. In fast-moving cells such as fish Keratocytes, Lamellipodia including most cell area finds a fan-like shape during migration, with a variety of aspect ratio function of fish type. In this work, our purpose is to present a novel and more complete two-dimensional continuum mathematical model of actomyosin-cytosolic two-phase flow of a self-deforming Keratocyte with circular spreaded to steady fan-like shape. In the new approach, in addition to the two-phase flow of the F-actin and cytosol, the... 

    Natural compounds for skin tissue engineering by electrospinning of nylon-Beta vulgaris

    , Article ASAIO Journal ; Volume 64, Issue 2 , 2018 , Pages 261-269 ; 10582916 (ISSN) Ranjbarvan, P ; Mahmoudifard, M ; Kehtari, M ; Babaie, A ; Hamedi, S ; Mirzaei, S ; Soleimani, M ; Hosseinzadeh, S ; Sharif University of Technology
    Lippincott Williams and Wilkins  2018
    Natural compounds containing polysaccharide ingredients have been employed as candidates for treatment of skin tissue. Herein, for the first time, electrospinning setup was proposed to fabricate an efficient composite nanofibrous structure of Beta vulgaris (obtained from Beet [Chenopodiaceae or Amaranthaceae]) belonged to polysaccharides and an elastic polymer named nylon 66 for skin tissue engineering. Both prepared scaffolds including noncomposite and composite types were studied by Scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectroscopy, mechanical assay, and contact angle. Scanning electron microscope examinations have approved the uniform and homogeneous... 

    Injectable chitosan/κ-carrageenan hydrogel designed with au nanoparticles: A conductive scaffold for tissue engineering demands

    , Article International Journal of Biological Macromolecules ; Volume 126 , 2019 , Pages 310-317 ; 01418130 (ISSN) Pourjavadi, A ; Doroudian, M ; Ahadpour, A ; Azari, S ; Sharif University of Technology
    Elsevier B.V  2019
    Scaffolds for tissue engineering of specific sites such as cardiac, nerve, and bone tissues need a comprehensive design of three dimensional materials that covers all aspects of chemical composition and physical structures, required for regeneration of desired cells. Hydrogels, possessing highly hydrated and interconnected structures, are promising materials for tissue engineering applications. Improvement of an injectable hydrogel from biocompatible polysaccharides and poly‑N‑isopropyl acryl amide enriched with Au nanoparticles are the main goal of this study. Two main enhancements in this study are included mixture design of the components and addition of Au nanoparticles to access a... 

    Bioinspired nanofiber scaffold for differentiating bone marrow-derived neural stem cells to oligodendrocyte-like cells: Design, fabrication, and characterization

    , Article International Journal of Nanomedicine ; Volume 15 , 2020 , Pages 3903-3920 Boroojeni, F. R ; Mashayekhan, S ; Abbaszadeh, H. A ; Ansarizadeh, M ; Khoramgah, M. S ; Rahimi Movaghar, V ; Sharif University of Technology
    Dove Medical Press Ltd  2020
    Background: Researchers are trying to study the mechanism of neural stem cells (NSCs) differentiation to oligodendrocyte-like cells (OLCs) as well as to enhance the selective differentiation of NSCs to oligodendrocytes. However, the limitation in nerve tissue acces-sibility to isolate the NSCs as well as their differentiation toward oligodendrocytes is still challenging. Purpose: In the present study, a hybrid polycaprolactone (PCL)-gelatin nanofiber scaffold mimicking the native extracellular matrix and axon morphology to direct the differentiation of bone marrow-derived NSCs to OLCs was introduced. Materials and Methods: In order to achieve a sustained release of T3, this factor was... 

    Silica nanoparticle surface chemistry: An important trait affecting cellular biocompatibility in two and three dimensional culture systems

    , Article Colloids and Surfaces B: Biointerfaces ; Volume 182 , 2019 ; 09277765 (ISSN) Hasany, M ; Taebnia, N ; Yaghmaei, S ; Shahbazi, M. A ; Mehrali, M ; Dolatshahi Pirouz, A ; Arpanaei, A ; Sharif University of Technology
    Elsevier B.V  2019
    Great advantages bestowed by mesoporous silica nanoparticles (MSNs) including high surface area, tailorable pore diameter and surface chemistry, and large pore volume render them as efficient tools in biomedical applications. Herein, MSNs with different surface chemistries were synthesized and investigated in terms of biocompatibility and their impact on the morphology of bone marrow-derived mesenchymal stem cells both in 2D and 3D culture systems. Bare MSNs (BMSNs) were synthesized by template removing method using tetraethylorthosilicate (TEOS) as a precursor. The as-prepared BMSNs were then used to prepare amine-functionalized (AMSNs), carboxyl-functionalized (CMSNs) and polymeric...