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Carboxymethyl cellulose-based functional film integrated with chitosan-based carbon quantum dots for active food packaging applications
, Article Progress in Organic Coatings ; Volume 166 , 2022 ; 03009440 (ISSN) ; Rhim, J. W ; Bagheri, R ; Pircheraghi, G ; Lotfali, E ; Sharif University of Technology
Elsevier B.V
2022
Abstract
A chitosan-based carbon quantum dots (CQDs) with multifunctional properties were synthesized using a hydrothermal process. The CQDs were spherical with an average size of 7.8 ± 2.4 nm. The CQD showed strong antioxidant activity, potent antibacterial activity against E. coli and L. monocytogenes, and antifungal activity against A. niger and P. chrysogenum. In addition, the prepared CQD showed negligible cytotoxicity against L929 cells even at a concentration of 500 μg/mL. Carboxymethyl cellulose (CMC)-based functional films were fabricated by adding various amounts of CQD. The CQDs were evenly dispersed in the polymer matrix to form a highly transparent UV-blocking film. The addition of CQD...
Boundary drag force acting on an impenetrable nano-particle
, Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010, Istanbul ; Volume 3 , 2010 , Pages 469-473 ; 9780791849170 (ISBN) ; Kebriai, M. H ; Meigounpoury, M. R ; Sharif University of Technology
2010
Abstract
Flow over nano spheres is a fundamental problem encountered in many engineering technical problems and the motion of nano-particles is important in many technical areas, for example nano-organizms motion in aqueous media, super hydrophobic spray for coating materials, nano-capsules for detecting cancer, and additive nano-particles in oil and fuel for automotive engines. In this paper computations are performed to determine the steady flow forces acting on the stationary nano-tube for Reynolds numbers in the range of 0.1
Biphasic TiO2 nanoleafed nanorod electrode for dye-sensitized solar cell
, Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 123 , 2020 ; Sadrnezhaad, S. K ; Sharif University of Technology
Elsevier B.V
2020
Abstract
The thin-film of hierarchical rutile/anatase TiO2 nanorod/nanoleafs on fluorine-doped tin oxide glass was prepared via a facile method. For this purpose, the hydrothermal method was used for the synthesis of rutile-phase nanorods on the TiO2 seeded FTO, and aqueous chemistry was applied for growing anatase-phase nanoleafs on the nanorods. The structural, morphological, and optical properties of coating characterized, and the thin-film utilized as the photoelectrode for dye-sensitized solar cell. The energy conversion efficiency of the newly developed nanostructure was higher than that of TiO2 nanorod thin-film by 40%. This increase could be ascribed to: (1) superior specific surface area...
Bioinspired TiO2/chitosan/HA coatings on Ti surfaces: Biomedical improvement by intermediate hierarchical films
, Article Biomedical Materials (Bristol) ; Volume 17, Issue 3 , 2022 ; 17486041 (ISSN) ; Ahmadi Seyedkhani, S ; Eslami Saed, A ; Sadrnezhaad, S. K ; Seza, A ; Sharif University of Technology
Institute of Physics
2022
Abstract
The most common reasons for hard-tissue implant failure are structural loosening and prosthetic infections. Hence, in this study, to overcome the first problem, different bioinspired coatings, including dual acid-etched, anodic TiO2 nanotubes array, anodic hierarchical titanium oxide (HO), micro- and nanostructured hydroxyapatite (HA) layers, and HA/chitosan (HA/CS) nanocomposite, were applied to the titanium alloy surfaces. X-ray diffraction and FTIR analysis demonstrated that the in situ HA/CS nanocomposite formed successfully. The MTT assay showed that all samples had excellent cell viability, with cell proliferation rates ranging from 120% to 150% after 10 days. The HO coating...
Biodegradation behavior of polymethyl methacrylate−bioactive glass 45S5 composite coated magnesium in simulated body fluid
, Article Transactions of Nonferrous Metals Society of China (English Edition) ; Volume 32, Issue 7 , 2022 , Pages 2216-2228 ; 10036326 (ISSN) ; Jafari, H ; Pishbin, F ; Mohammadi, R ; Simchi, A ; Sharif University of Technology
Nonferrous Metals Society of China
2022
Abstract
The biodegradation behavior of Mg, coated by polymethyl methacrylate as well as polymethyl methacrylate (PMMA)−bioactive glass (BG) composite was investigated. Electrophoretic deposition and dip coating techniques were adopted to prepare composite coating using a suspension of different percentages of the above two chemical materials. The deposited coatings were characterized using SEM, EDS, FTIR, and water contact angle measurements. Biodegradation behavior study of the coated Mg was performed using linear polarization, impedance spectroscopy, and immersion tests in simulated body fluid. The compact and homogeneous composite coating was developed as evidenced by electron microscopy results....
Bed mixing and leachate recycling strategies to overcome pressure drop buildup in the biofiltration of hydrogen sulfide
, Article Bioresource Technology ; Volume 109 , 2012 , Pages 26-30 ; 09608524 (ISSN) ; Torkian, A ; Aslani, H ; Dehghanzadeh, R ; Sharif University of Technology
2012
Abstract
The effects of leachate recycling and bed mixing on the removal rate of H 2S from waste gas stream were investigated. The experimental setup consisted of an epoxy-coated three-section biofilter with an ID of 8cm and effective bed height of 120cm. Bed material consisted of municipal solid waste compost and PVC bits with an overall porosity of 54% and dry bulk density of 0.456gcm -3. Leachate recycling had a positive effect of increasing elimination capacity (EC) up to 21gSm -3 bedh -1 at recycling rates of 75mld -1, but in the bed mixing period EC declined to 8g Sm -3bedh -1. Pressure drop had a range of zero to 18mm H 2Om -1 in the course of leachate recycling. Accumulation of sulfur reduced...
Axisymmetric time-harmonic response of a transversely isotropic substrate-coating system
, Article International Journal of Engineering Science ; Volume 45, Issue 2-8 , 2007 , Pages 272-287 ; 00207225 (ISSN) ; Eskandari, M ; Sharif University of Technology
2007
Abstract
By virtue of a method of displacement potentials, an analytical treatment of the response of a transversely isotropic substrate-coating system subjected to axisymmetric time-harmonic excitations is presented. In determination of the corresponding elastic fields, infinite line integrals with singular complex kernels are encountered. Branch points, cuts, and poles along the path of integration are accounted for exactly, and the physical phenomena pertinent to wave propagation in the medium are also highlighted. For evaluation of the integrals at the singular points, an accurate analytical residual theory is presented. Comparisons with the existing numerical solutions for a two-layered...
Axisymmetric time-harmonic response of a surface-stiffened transversely isotropic half-space
, Article Meccanica ; Volume 52, Issue 1-2 , 2017 , Pages 183-196 ; 00256455 (ISSN) ; Samea, P ; Ahmadi, S. F ; Sharif University of Technology
Abstract
This study deals with the elastodynamic response of a surface-stiffened transversely isotropic half-space subjected to a buried time-harmonic normal load. The half-space is reinforced by a Kirchhoff thin plate on its surface. By virtue of a displacement potential function and appropriate time-harmonic Green’s functions of transversely isotropic half-spaces, a robust solution corresponding to two plate-medium bonding assumptions, namely (a) frictionless interface, and (b) perfectly bonded interface is obtained for the first time. All elastic fields of the problem are expressed explicitly in the form of semi-infinite line integrals. Results of some limiting cases including isotropic materials,...
A two-step spin-spray deposition processing route for production of halide perovskite solar cell
, Article Thin Solid Films ; Volume 616 , 2016 , Pages 754-759 ; 00406090 (ISSN) ; Alizadeh, A. H ; Moshaii, A ; Gharibzadeh, S ; Alizadeh, A ; Mohammadpour, R ; Fathi, D ; Sharif University of Technology
Elsevier B.V
Abstract
We report on fabrication of halide perovskite solar cells using a two-step spin-spray coating rout. The applied method is one of the most straight forward procedures for fabricating uniform stoichiometry and crystalline perovskite cells. To fabricate a high quality perovskite layer, various concentrations of methyl-ammonium iodide (CH3NH3I) were sprayed on a spin coated PbI2 layer using a simple airbrush gun. The characterization results indicate that the size of cuboid perovskite morphology depends on the concentration of methylammonium iodide in the spray procedure. The photovoltaic performance of the fabricated solar cells has been measured and a high dependency on the cuboid sizes was...
A two-level undercut-profile substrate for chemical-solution-based filamentary coated conductors
, Article IEEE Transactions on Applied Superconductivity ; Volume 26, Issue 3 , 2016 ; 10518223 (ISSN) ; Lundeman, J. H ; Hansen, J. B ; Mishin, O. V ; Zhao, Y ; Mohajeri, R ; Grivel, J. C ; Sharif University of Technology
Abstract
A recently developed two-level undercut-profile substrate (2LUPS), containing two levels of plateaus connected by a curved wall with an undercut profile, enables self-forming filaments in a coated conductor during physical line-of-sight deposition of buffer and superconducting layers. In the present study, the 2LUPS concept is applied to a commercial cube-textured Ni-5at.%W tape, and the surface of the 2LUPS coated with two Gd2Zr2O7 buffer layers using chemical solution deposition is examined. Except for narrow regions near the edge of upper plateaus, the plateaus are found to be covered by strongly textured Gd2Zr2O7 buffer layers after dip coating and sintering
Atmospheric corrosion evaluation of silver coating using simulating technique test
, Article European Corrosion Conference: Long Term Prediction and Modelling of Corrosion, EUROCORR 2004, Nice, 12 September 2004 through 16 September 2004 ; 2004 ; Afshar, A ; Sharif University of Technology
2004
Abstract
A standard simulating technique test was investigated to assess the atmospheric corrosion behavior of silver coating. The rates of formation of corrosion products were measured in the simulating atmospheres of 100% humidity containing SO 2,H 2S and a complex atmosphere consist of SO 2,H 2S and NO 2 gases ,based on the mass increase method. The concentrations of corrosive gases were chosen according to real world conditions. XRD, SEM and EDS were used to examine the morphology and to determine the composition of the corrosion products under different experimental conditions. Results revealed the formation of Ag 2SO 4 and Ag 2S on the silver coating surfaces in the SO 2 and H 2S containing...
A thermoelasticity solution of sandwich structures with functionally graded coating
, Article Composites Science and Technology ; Volume 67, Issue 6 , 2007 , Pages 1073-1080 ; 02663538 (ISSN) ; Haftbaradaran, H ; Asghari, M ; Sharif University of Technology
2007
Abstract
An exact thermoelasticity solution for a two-dimensional thick composite consisting of homogeneous and functionally graded layers is presented. The thermomechanical properties of functionally graded layers are assumed to vary exponentially through the thickness while the Poisson's ratio is taken to be constant. The heat transfer problem is solved under steady state condition accounting for the heat convection. Utilizing the stress function the governing equation reduces to a fourth order inhomogeneous partial differential equation which is solved exactly using Fourier series method. A comparative study is done between two sandwich structures with homogeneous and functionally graded coatings,...
A study on the mechanism of electrodeposition of Ni/SiC composite coatings using impedance technique
, Article ECS Transactions ; Volume 41, Issue 44 , 2012 , Pages 47-57 ; 19385862 (ISSN) ; 9781607683452 (ISBN) ; Dolati, A ; Electrodeposition; Sensor ; Sharif University of Technology
2012
Abstract
Ni/SiC nanocomposite coatings were electrodeposited using Watts type bath and different SiC particle size. The electrodeposition behavior of Ni/SiC nanoelectrocomposites was studied using electrochemical techniques such as impedance spectroscopy (EIS) and voltammetry. In this study it was shown that SiC particles modify the EIS diagram and voltammograms as well as surface morphology of electrodeposited layers. Experimental results showed that SiC particles not only affect the formation of intermediate species and decrease charge transfer resistance but also increase the nucleation sites for nickel electrodeposition and thus affect the microstructure of electrodeposited Ni/SiC nanocomposites....
A study of the electrophoretic deposition of Bioglass® suspensions using the Taguchi experimental design approach
, Article Journal of the European Ceramic Society ; Volume 30, Issue 14 , October , 2010 , Pages 2963-2970 ; 09552219 (ISSN) ; Simchi, A ; Ryan, M. P ; Boccaccini, A. R ; Sharif University of Technology
2010
Abstract
This paper presents a study of the Taguchi design method to optimise the rate of electrophoretic deposition (EPD) of Bioglass® particles from aqueous suspensions. The effect of Bioglass® concentration, pH and electric field was investigated. An orthogonal array of L16 type with mixed levels of the control factors was utilized. Multivariate analysis of variance (MANOVA) and regression analysis based on the partial least-square method were used to identify the significant factors affecting the deposition rate and its stability during constant-voltage EPD. It was found that the pH of the suspension significantly influences the deposition rate whereas the applied electric field has the smallest...
A study of the electrophoretic deposition of bioactive glass-chitosan composite coating
, Article Ceramics International ; Volume 38, Issue 1 , January , 2012 , Pages 471-476 ; 02728842 (ISSN) ; Afshar, A ; Sharif University of Technology
2012
Abstract
Bioactive glass is coated on implant's surface to improve corrosion resistance and osseointegration, when placed in the body. Bioactive glass particles were synthesized through a sol-gel process and deposited along with chitosan to form a composite coating on a stainless steel substrate using electrophoretic deposition technique. Stable suspensions of chitosan-bioactive glass were prepared using bioactive glass particles (<1 μm) and 0.5 g/l chitosan solution. The influence of ethanol-water ratio on deposition yield was investigated. For all process conditions, best results were achieved with suspension of 30 vol% water in ethanol-water containing 2 g/l bioactive glass. FTIR studies showed...
A single layer deposition of Li-doped mesoporous TiO2beads for low-cost and efficient dye-sensitized solar cells
, Article New Journal of Chemistry ; Volume 45, Issue 5 , 2021 , Pages 2470-2477 ; 11440546 (ISSN) ; Nouri, E ; Mohsenzadegan, N ; Mohammadi, M. R ; Martinez Chapa, S. O ; Sharif University of Technology
Royal Society of Chemistry
2021
Abstract
Herein, we report a new strategy for improving the efficiency and reducing the fabrication cost of dye-sensitized solar cells (DSCs) by elimination of the three- or four-fold layer deposition of TiO2. This is performed by replacing a single layer deposition of mesoporous TiO2 beads, with sub-micrometer size, high surface area and tunable pore size, synthesized by a combination of sol-gel and solvothermal methods. Furthermore, superior electronic properties gained by a reduction in electronic trap states are achieved through doping of pristine TiO2 beads with lithium. The beads have a spherical shape with monodispersed texture consisting of anatase-TiO2 nanocrystals and ultra-fine pores. The...
A simple route to synthesize zirconia antistatic thin films on glass substrates and their application to polymer-based composites
, Article Materials Chemistry and Physics ; Volume 244 , 1 April , 2020 ; Dolati, A ; Afshar, A ; Palardy, G ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In this study, zirconia antistatic coatings were synthesized by a simple dip coating sol-gel route on glass substrates, then applied to polymer-based composites to potentially improve their dust or water repellent capabilities. The coating solution contained a precursor (ZrCl4), solvent (isopropanol) and coupling agent. FTIR spectra confirmed ZrO2 and ZrO compounds in both solution and antistatic coating. FE-SEM images indicated ZrO2 fibers’ thickness was controlled by changing ZrCl4 concentration (150 g–15 g ZrCl4/l) or relative humidity (20%–60%) during coating drying. Fibers grew thicker when decreasing the former or increasing the latter. The surface electrical resistivity for all...
A simple and fast method for comparison of corrosion inhibition powers between pairs of pyridine derivative molecules
, Article Corrosion ; Volume 61, Issue 8 , 2005 , Pages 778-783 ; 00109312 (ISSN) ; Arshadi, M. R ; Parsafar, Gh. A ; Sharif University of Technology
National Assoc. of Corrosion Engineers International
2005
Abstract
Ab initio quantum chemical calculations at the density functional theory (DFT) level were performed on eight pyridine derivative molecules as corrosion inhibitors for iron in an acidic solution. In this regard, the geometry of the molecules were optimized using the B3LYP/6-31G method first, and then interactions of these optimized structures with the iron atom were explored using the B3LYP/LANL1MB method. Two modes of adsorption were considered, i.e., planar adsorption (P) via the pyridine ring and vertical adsorption (V) through a nitrogen atom. The interaction energy was minimized through the variation of the inhibitor molecule-iron atom distance. These minimum energy values, along with...
A proposal for distributed humidity sensor based on the induced LPFG in a periodic polymer coated fiber structure
, Article Optics and Laser Technology ; Volume 117 , 2019 , Pages 126-133 ; 00303992 (ISSN) ; Esmailzadeh Noghani, F ; Bahrampour, A ; Bahrampour, A. R ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
In this paper, a distributed relative humidity (RH) or moisture sensor is proposed. The proposed structure is a single mode telecommunication optical fiber coated by humidity sensitive and insensitive polymers periodically. The polymer coated fiber is surrounded by a high Young's modulus material such as stainless steel mesh. The swelling of the coated Humidity Sensitive Polymers (HSPs) as a result of moisture absorption induces fiber gratings in the single mode fiber. Depending on the coating period relative to the light wavelength, the induced fiber grating can be Fiber Bragg Grating (FBG) or Long Period Fiber Grating (LPFG). The light reflected by the induced FBG or losses due to the...
Application of sol-gel technique to synthesis of copper-cobalt spinel on the ferritic stainless steel used for solid oxide fuel cell interconnects
, Article Journal of Power Sources ; Vol. 266, issue , 2014 , pp. 79-87 ; ISSN: 03787753 ; Askari, M ; Ghorbanzadeh, M ; Sharif University of Technology
Abstract
The conductive CuCo2O4 spinel coating is applied on the surface of the AISI 430 ferritic stainless steel by the dip-coating sol-gel process and it is evaluated in terms of the microstructure, oxidation resistance and electrical conductivity. The results show that the CuCO2O 4 coating forms a double-layer scale consisting of a Cr, Fe-rich subscale and Cu-Co spinel top layer after 500 h in air at 800 °C. This scale is protective, acts as an effective barrier against Cr migration into the outer oxide layer and alleviates the cathode Cr-poisoning. The oxidation resistance is significantly enhanced by the protective coating with a parabolic rate constant of 5.8 × 10-13 gr2 cm-4 s -1, meanwhile...