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Reducing ion migration in methylammonium lead tri-bromide single crystal via lead sulfate passivation
, Article Journal of Applied Physics ; Volume 127, Issue 18 , April , 2020 ; Parikh, N ; Kumari, H ; Pandey, M. K ; Kumar, M ; Prochowicz, D ; Kalam, A ; Tavakoli, M. M ; Yadav, P ; Sharif University of Technology
American Institute of Physics Inc
2020
Abstract
Surface passivation of organic-inorganic halide perovskites (OIHPs) is a crucial step to annihilate the surface defects and to control the deteriorated ion migration phenomenon. Here, we study the role of lead sulfate (PbSO4) as an effective passivator in OIHP single crystals (SCs). Using impedance spectroscopy, we evaluate the ion migration and electrical properties of lead sulfate-passivated methylammonium lead tri-bromide (MAPbBr3) SCs. We found that the low-frequency impedance response that is assigned to the ionic motion in the MAPbBr3 SC is strongly affected by the inorganic PbSO4 surface treatment. The activation energy corresponding to the ion migration of MAPbBr3 SC is increased...
Optimization of shot peening effective parameters on surface hardness improvement
, Article Metals and Materials International ; June , 2020 ; Unal, O ; Sharif University of Technology
Korean Institute of Metals and Materials
2020
Abstract
Abstract: Shot peening is well-known process for mechanical properties integrity in metallic materials. In present study influences of different shot peening treatments on the surface hardness of different carbon steels were investigated experimentally and then alternative approach by using artificial neural network is presented for hardness prediction of the shot peened surface. After modeling a comprehensive parametric investigations and sensitivity analysis were applied according to the influence of the related effective parameters on surface hardness improvements. Graphic Abstract: [Figure not available: see fulltext.] © 2020, The Korean Institute of Metals and Materials
Nanodiamond loaded with corrosion inhibitor as efficient nanocarrier to improve anticorrosion behavior of epoxy coating
, Article Journal of Industrial and Engineering Chemistry ; Volume 83 , 2020 , Pages 153-163 ; Shojaei, A ; Pirhady Tavandashti, N ; Sharif University of Technology
Korean Society of Industrial Engineering Chemistry
2020
Abstract
In the present study, thermally oxidized nanodiamond (OND) was first modified non-covalently with dodecylamine (DDA) as corrosion inhibitor. In this respect, reactive primary amine of DDA molecule with high isoelectric point (IEP) could interact easily with negative charge carboxylic acid groups of OND. Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) proved that OND nanoparticle was successfully functionalized by DDA up to approximately 5 wt% grafting contnet. Both OND and dodecylamine modified OND (DND) were loaded in epoxy (EP)/polyamine hardener matrix at the same concentration of 1 wt% and applied on mild steel substrate. Morphology of EP-DND and...
CaTiO3/α-TCP coatings on CP-Ti prepared via electrospinning and pulsed laser treatment for in-vitro bone tissue engineering
, Article Surface and Coatings Technology ; Volume 401 , 2020 ; Esfahani, H ; Sheikhi, M ; Mohammadi, M ; Sharif University of Technology
Elsevier B.V
2020
Abstract
In this study, the in-vitro bone regeneration ability of commercial pure titanium (CP-Ti) surface modified via electrospun polyvinylidene/hydroxyapatite (PVP/HA) masking and subsequent Nd-YAG pulsed laser treatment was investigated. The ratio of HA to PVP played a significant role in achieving a perfect homogenous mask on the CP-Ti. In the laser treatment process, the parameter of area scanning speed (ASS) had an important influence on the final surface morphology. A favorable range was defined for this parameter where these two conditions were satisfied: no PVP remaining and no severe substrate melting. Within a favorable range of ASS, as decreasing ASS exchanged the surface structure from...
Efficiency improvement of solar stills through wettability alteration of the condensation surface: An experimental study
, Article Applied Energy ; Volume 268 , 2020 ; Soltani Goharrizi, A ; Ayatollahi, S ; Feilizadeh, M ; Dashti, H ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
The condensation process is of great importance in many heat transfer devices in which a large amount of energy must be transferred. Furthermore, condensation is a crucial part of energy conversion and affects the energy efficiency of thermal desalination plants and solar stills. During the condensation process in solar stills, an essential part of the energy is transferred through the condensation surface to produce fresh water. Therefore, the condensation surface plays a significant role in the working efficiency of solar stills. The wettability of the condensation surface influences the condensation mechanism, which, in turn, affects the efficiency of solar stills. This study aims to...
A clustering approach to identify the time of a step change in shewhart control charts
, Article Quality and Reliability Engineering International ; Volume 24, Issue 7 , 2008 , Pages 765-778 ; 07488017 (ISSN) ; Alaeddini, A ; Akhavan Niaki, S. T ; Aryanezhad, M. B ; Sharif University of Technology
2008
Abstract
Control charts are the most popular statistical process control tools used to monitor process changes. When a control chart indicates an out-of-control signal it means that the process has changed. However, control chart signals do not indicate the real time of process changes, which is essential for identifying and removing assignable causes and ultimately improving the process. Identifying the real time of the change is known as the change-point estimation problem. Most of the traditional methods of estimating the process change point are developed based on the assumption that the process follows a normal distribution with known parameters, which is seldom true. In this paper, we propose...
Alumina - copper eutectic bond strength: Contribution of preoxidation, cuprous oxides particles, and pores
, Article 16th International Federation for Heat Treatment and Surface Engineering Congress, Brisbane, QLD, 30 October 2007 through 2 November 2007 ; Volume 32 , 2007 , Pages 90-97 ; 08832900 (ISSN) ; Kokabi, A. H ; Faghihi Sani, M. A ; Riazi, Z ; Sharif University of Technology
2009
Abstract
The influences of cupric oxide layer thickness, cuprous oxide particles, and pores on mechanical properties and microstructure of alumina-copper eutectic bond have been investigated. The furnace atmosphere in the first stage was argon gas with 2 × 10-6 atm oxygen partial pressure. In the second stage, the furnace atmosphere was same as the first stage unless that in cooling between 900-1000 °C, the hydrogen gas was purged in furnace atmosphere. Finally, in the last stage a vacuum furnace with 5 × 10 -8 atm pressure was chosen for bonding procedure. Peel strength of first stage specimens shows that cupric oxide layer with 320 ± 25 nm thick generates the maximum peel strength (13.1 ± 0.3...
Adhesion modification of polyethylenes for metallization using radiation-induced grafting of vinyl monomers
, Article Surface and Coatings Technology ; Volume 201, Issue 16-17 , 2007 , Pages 7519-7529 ; 02578972 (ISSN) ; Fathi, R ; Sheikh, N ; Sharif University of Technology
2007
Abstract
The present paper demonstrates the performance of the radiation grafting technique as a chemically based surface pretreatment method to adhesion modification of polyethylene surfaces toward the metallic layer. Gamma irradiation over a dose range of 4-10 kGy is used for grafting of vinyl monomers including acrylamide (AAm) and 1-vinyl-2-pyrrolidone (NVP) onto the surface of three different polyethylenes including low density polyethylene (LDPE) and two kinds of high density polyethylenes, namely HDPE-1 and HDPE-2. The grafting yield is evaluated based on the weight increase of the samples. It is found that the grafting yield is dominated by the crystallinity of the polyethylene, so that lower...
Increasing the interfacial adhesion in poly(methyl methacrylate)/carbon fibre composites by laser surface treatment
, Article Polymers and Polymer Composites ; Volume 14, Issue 6 , 2006 , Pages 585-589 ; 09673911 (ISSN) ; Mousavi, S. A. S ; Tilaki, R. M ; Frounchi, M ; Sharif University of Technology
Rapra Technology Ltd
2006
Abstract
The impact strength of poly(methyl methacrylate)/caibon (long) fibre composites for denture prosthesis applications was improved by fibre surface treatment. The carbon fibre surfaces were modified by Nd:YAG laser irradiation at 1064 nm wavelength. Laser light intensity was adjusted at 100 mj per pulse that only changed the fibre surface roughness and did not lead to fibre rupture, as verified by scanning electron microscopy. Increased surface roughness of the fibres improved the adhesion of poly(methyl methacrylate) to the fibre surface. Adhesion between the fibres and poly(methyl methacrylate) was evaluated by a tear-off method and by scanning electron microscopy. The results also suggest...
An investigation into the effect of various surface treatments on fatigue life of a tool steel
, Article Journal of Materials Processing Technology ; Volume 174, Issue 1-3 , 2006 , Pages 318-324 ; 09240136 (ISSN) ; Ghadbeigi, H ; Sharif University of Technology
2006
Abstract
The effects of nitriding, nitrocarburizing and shot peening on fatigue behavior of AISI D3 cold work tool steel were investigated. Five batches of fatigue specimens were manufactured according to the ASTM E466-96 standard. All specimens were quenched and tempered to a hardness of 50 HRC. One group of specimens was shot peened with an Almen intensity of 16 A, one group was nitrocarburized, one group was gas nitrided by single stage and another group was also nitrided by double stages. Rotating-bending fatigue tests were carried out. Our results showed that nitriding and nitrocarburizing treatments did not have a beneficial effect on the fatigue resistance of D3 tool steel. Fatigue test...
Decolorization of denim fabrics with cold plasmas in the presence of magnetic fields
, Article Plasma Processes and Polymers ; Volume 3, Issue 3 , 2006 , Pages 316-321 ; 16128850 (ISSN) ; Moazzenchi, B ; Shahidi, S ; Anvari, A ; Rashidi, A ; Sharif University of Technology
2006
Abstract
Denim jeans have consistently been fashionable around the world. This fabric inspired strong opinions from historians, teenagers, and movie stars, and has acquired different styles throughout the years. Most jeans today are stonewashed; this technique first become popular in 1970. Now, in addition to pumice stones, enzymes are used on the cotton fabrics to create the stonewashed look. Nowadays, plasma treatment is a cost-effective and environment-friendly process which is able to modify the properties of the fabric surface in order to achieve this effect. Plasma surface treatment changes the properties of the fabric up to a limited depth (several molecular layers), leaving the bulk...
Surface modification of exchange-coupled Co/NiO x magnetic bilayer by bias sputtering
, Article Applied Surface Science ; Volume 252, Issue 2 , 2005 , Pages 466-473 ; 01694332 (ISSN) ; Akhavan, O ; Moshfegh, A. Z ; Jafari, G. R ; Kavei, G ; Sharif University of Technology
Elsevier
2005
Abstract
We have investigated the effect of bias voltage on sheet resistance, surface roughness and surface coverage of Co/NiO x magnetic bilayer. In addition, interface topography and corrosion resistance of the Ta/Co/Cu/Co/NiO x /Si(1 0 0) system have been studied for Co layers deposited at an optimum bias voltage. Atomic force microscopy (AFM) and four point probe sheet resistance (Rs) measurement have been used to determine surface and electrical properties of the sputtered Co layer at different bias voltages ranging from 0 to -80 V. The Co/NiO x bilayer exhibits a minimum surface roughness and low sheet resistance value with a maximum surface coverage at Vb=-60 V resulted in a slight increase of...
Scattering of a Gaussian beam by a spherical dielectric object using the vectorial Gaussian beam tracing method
, Article ICCEA 2004 - 2004 3rd International Conference on Computational Electromagnetics and its Applications, Beijing, 1 November 2004 through 4 November 2004 ; 2004 , Pages 72-75 ; 0780385624 (ISBN); 9780780385627 (ISBN) ; Sharif University of Technology
2004
Abstract
Scattering of a Gaussian beam by a spherical dielectric object is studied using the vectorial Gaussian beam tracing method. Expansion to a few Gaussian beams with the smaller waists has been used to extend the method to a more generalized one. This method can be applied to a large variety of different shape objects and incident beam profiles. Numerical results of this computationally fast method show a good agreement with the results represented in the literature. © 2004 IEEE
Co surface modification by bias sputtering in Cu/Co(Vb)/NiO/ Si(100) magnetic multilayer structures
, Article Physica Status Solidi C: Conferences ; Volume 1, Issue 7 , 2004 , Pages 1744-1747 ; 16101634 (ISSN) ; Sangpour, P ; Sharif University of Technology
2004
Abstract
To investigate the Ta/Co/Cu/Co/NiO/Si(100) spin valve structure, fabrication and characterization of the Cu/Co/NiO/Si(100) system was studied for further understanding the structure. The system was grown by employing combinative DC sputtering-evaporation technique. Nickel oxide with a thickness of about 30 nm was deposited on Si(100) substrate using thermal evaporation technique.The cobalt film, then, with a thickness of about 3 nm was grown by DC sputtering under various applied negative bias voltages ranging from 0 to - 80 V. The optimum bias voltage (Vb = -60 V) for the growth of Co layer was determined by atomic force microscopy (AFM), four-point probe sheet measurement (Rs) and scanning...
Cold atmospheric plasma modification and electrical conductivity induction in gelatin/polyvinylidene fluoride nanofibers for neural tissue engineering
, Article Artificial Organs ; Volume 46, Issue 8 , 2022 , Pages 1504-1521 ; 0160564X (ISSN) ; Hosseini, E ; Ramazani Saadatabadi, A ; Atyabi, S ; Bakhshandeh, H ; Mohamadali, M ; Aidun, A ; Farasati Far, B ; Sharif University of Technology
John Wiley and Sons Inc
2022
Abstract
Background: This research follows some investigations through neural tissue engineering, including fabrication, surface treatment, and evaluation of novel self-stimuli conductive biocompatible and degradable nanocomposite scaffolds. Methods: Gelatin as a biobased material and polyvinylidene fluoride (PVDF) as a mechanical, electrical, and piezoelectric improvement agent were co-electrospun. In addition, polyaniline/graphene (PAG) nanoparticles were synthesized and added to gelatin solutions in different percentages to induce electrical conductivity. After obtaining optimum PAG percentage, cold atmospheric plasma (CAP) treatment was applied over the best samples by different plasma variable...