Loading...
Search for:
solution-concentration
0.006 seconds
Total 31 records
Simulation of Si concentration effect on the permeability for columnar dendrite structures during solidification of Al-Si alloy
, Article Materials and Design ; Volume 28, Issue 1 , 2007 , Pages 356-361 ; 02613069 (ISSN) ; Silk, J ; Sharif University of Technology
Elsevier Ltd
2007
Abstract
A numerical model has been developed for the determination of liquid flow permeability through columnar dendrite during growth and segregation in Al-Si mushy alloys. The model is inclusive of two stages, first numerical evolution of the dendrite shape during growth, and second numerical determination of the permeability. Simulation results shown which Si concentration by transform of dendrite shape dendrite could reduce of the interdendritic liquid permeability. © 2005 Elsevier Ltd. All rights reserved
Polyamide/polyacrylonitrile thin film composites as forward osmosis membranes
, Article Journal of Applied Polymer Science ; Volume 133, Issue 42 , 2016 ; 00218995 (ISSN) ; Abbaszadeh, M ; Mousavi, S. A ; Soltanieh, M ; Bakhshi, H ; Sharif University of Technology
John Wiley and Sons Inc
Abstract
Thin film composites (TFCs) as forward osmosis (FO) membranes for seawater desalination application were prepared. For this purpose, polyacrylonitrile (PAN) as a moderately hydrophilic polymer was used to fabricate support membranes via nonsolvent-induced phase inversion. A selective thin polyamide (PA) film was then formed on the top of PAN membranes via interfacial polymerization reaction of m-phenylenediamine and trimesoyl chloride (TMC). The effects of PAN solution concentration, solvent mixture, and coagulation bath temperature on the morphology, water permeability, and FO performance of the membranes and composites were studied. Support membranes based on low PAN concentrations (7 wt...
Solute dispersion by electroosmotic flow through soft microchannels
, Article Sensors and Actuators, B: Chemical ; Volume 255, Part 3 , February , 2018 , Pages 3585-3600 ; 09254005 (ISSN) ; Khorami, A ; Ashrafizadeh, S. N ; Sadeghi, A ; Sharif University of Technology
Elsevier B.V
2018
Abstract
We study the hydrodynamic dispersion (HD) by electroosmotic flow in soft microchannels. Considering a fully developed flow in a slit microchannel of low surface potential and adopting the Taylor dispersion theory, we derive analytical solutions for the solute concentration field and the effective dispersion coefficient. We also conduct numerical analyses to broaden the paper's scope to high surface potentials and to specify a criterion for the validity of the Debye-Hückel linearization in soft microconduits as well as to investigate the broadening of an analyte band from the time of injection. It is demonstrated that the effective dispersion coefficient of a neutral solute band is generally...
Hydrodynamic dispersion by electroosmotic flow of viscoelastic fluids within a slit microchannel
, Article Microfluidics and Nanofluidics ; Volume 22, Issue 1 , January , 2018 ; 16134982 (ISSN) ; Talebi, M ; Ashrafizadeh, S. N ; Sadeghi, A ; Sharif University of Technology
Springer Verlag
2018
Abstract
The biofluids being manipulated in lab-on-a-chip devices usually contain elastic macromolecules. Accordingly, for an accurate modeling of the relevant flow physics one should invoke viscoelastic constitutive equations. In this paper, attention is paid toward the hydrodynamic dispersion by the fully developed electroosmotic flow of PTT viscoelastic fluids in slit microchannels of low zeta potential. Adopting the Taylor–Aris approach, analytical solutions are derived for late-time solute concentration and effective dispersion coefficient. Finite element-based numerical simulations are also conducted to monitor the broadening of an analyte band from the moment of injection. Both approaches are...
Synthesis and morphology optimization of electrospun SiBNC nanofibers
, Article Ceramics International ; Volume 46, Issue 5 , 2020 , Pages 6052-6059 ; Mehdinavaz Aghdam, R ; Shahedi Asl, M ; Faghihi Sani, M. A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
SiBNC nanofibers were synthesized through the polymeric route by a one-pot synthesis approach. DMTA (dichloroboryl methyl trichlorosilyl amine) polymer was selected as pre-ceramic for SiBNC, which was shaped into nanofibers by electrospinning. Then, the nanofibers were cured in an inert atmosphere in order to obtain the final ceramic. By changing the curing atmosphere, the compound of final ceramic has been manipulated. In addition, the ceramic yield of DMTA as a preceramic was increased in the nitrogen atmosphere. The effects of applied voltage, solution concentration, and feeding rate on the morphology of final electrospun ceramic nanofibers were also investigated. Final ceramic remains...
Investigation of precursors concentration in spray solution on the optoelectronic properties of CuInSe2 thin films deposited by spray pyrolysis method
, Article Journal of Materials Science: Materials in Electronics ; 2020 ; Ghorashi, S. M. B ; Tajabadi, F ; Taghavinia, N ; Sharif University of Technology
Springer
2020
Abstract
Copper indium selenide CuInSe2(CISe) thin films were deposited by chemical spray pyrolysis (CSP) method of CuInS2(CIS) and subsequent selenization process. To study the effects of solution concentration, we prepared different precursors solution of CIS including different amount of indium salts from 0.025 to 0.100 M with In/Cu 1.25 and S/In 4. These results propose that solution concentration is critical for inflecting the morphological, optical, electrical, and electrochemical characteristics of solution-processed CISe films and device performance. The studied morphological properties of deposited samples were homogenous, crack-free with large grains in indium salt concentrations more than...
Optical concentration of gold nanoparticles as a new concept of analytical sensitivity
, Article Instrumentation Science and Technology ; 2020 ; Shokoufi, N ; Seyed Reihani, S. N ; Sharif University of Technology
Bellwether Publishing, Ltd
2020
Abstract
Concentration procedures have always been implemented when trace analysis of compounds in real matrices is contemplated. A variety of concentration strategies have been reported aiming at decreasing the limits of detection (LODs). The optical concentration of the substance in solution is one of the novel concepts for the enhancement of the analytical sensitivity. In this study, the optical concentration has been measured by the trapping of gold nanoparticles ((Formula presented.) nm) dispersed in water at low-concentrations at the focal volume of the laser beam. The influence of factors such as the time of gold nanoparticle trapping, the size of the nanoparticles, the intensity of the laser...
Investigation of precursors concentration in spray solution on the optoelectronic properties of CuInSe2 thin films deposited by spray pyrolysis method
, Article Journal of Materials Science: Materials in Electronics ; Volume 32, Issue 21 , 2021 , Pages 25748-25757 ; 09574522 (ISSN) ; Ghorashi, S. M. B ; Tajabadi, F ; Taghavinia, N ; Sharif University of Technology
Springer
2021
Abstract
Copper indium selenide CuInSe2(CISe) thin films were deposited by chemical spray pyrolysis (CSP) method of CuInS2(CIS) and subsequent selenization process. To study the effects of solution concentration, we prepared different precursors solution of CIS including different amount of indium salts from 0.025 to 0.100 M with In/Cu 1.25 and S/In 4. These results propose that solution concentration is critical for inflecting the morphological, optical, electrical, and electrochemical characteristics of solution-processed CISe films and device performance. The studied morphological properties of deposited samples were homogenous, crack-free with large grains in indium salt concentrations more than...
Theoretical study of diffusional release of a dispersed solute from a hollow cylindrical polymeric matrix
, Article Scientia Iranica ; Volume 28, Issue 3 , 2021 , Pages 1428-1435 ; 10263098 (ISSN) ; Tajsoleiman, T ; Abdekhodaie, M. J ; Sharif University of Technology
Sharif University of Technology
2021
Abstract
The present study proposes an exact solution for the release kinetic of a solute from inside a hollow cylindrical polymeric matrix into an infinite medium when the initial concentration of the solute (A) is greater than the solubility limit (Cs). A combination of analytical and numerical methods was used to calculate the solute concentration profile and the release rate. The model was developed for two different conditions including: (1) The release medium was flowing through the hollow cylinder in which the boundary layer may be neglected, and (2) The release medium inside the hollow cylinder was stagnant where the boundary layer needed to be considered. The results indicated that the...
Partially hydrolyzed crosslinked alginate-graff-polymethacrylamide as a novel biopolymer-based superabsorbent hydrogel having pH-responsive properties
, Article Macromolecular Research ; Volume 13, Issue 1 , 2005 , Pages 45-53 ; 15985032 (ISSN) ; Amini Fazl, M. S ; Hosseinzadeh, H ; Sharif University of Technology
Polymer Society of Korea
2005
Abstract
In this study, a series of highly swelling hydrogels based on sodium alginate (NaAlg) and polymethacrylamide (PMAM) was prepared through free radical polymerization. The graft copolymerization reaction was performed in a homogeneous medium and in the presence of ammonium persulfate (APS) as an initiator and N,N'-methylenebisacrylamide (MBA) as a crosslinker. The crosslinked graft copolymer, alginate-graft-polymethacrylamide (Alg-g-PMAM), was then partially hydrolyzed by NaOH solution to yield a hydrogel, hydrolyzed alginate-graft-polymethacrylamide (H-Alg-g-PMAM). During alkaline hydrolysis, the carboxamide groups of Alg-g-PMAM were converted into hydrophilic carboxylate anions. Either the...
On the inability of the moving interface model to predict isothermal solidification time during transient liquid phase (TLP) bonding of ni-based superalloys
, Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 53, Issue 1 , 2022 , Pages 126-135 ; 10735623 (ISSN) ; Ghasemi, A ; Salmasi, A ; Sharif University of Technology
Springer
2022
Abstract
Understanding diffusion-induced isothermal solidification time during transient liquid phase bonding is vital in producing intermetallic-free robust joints. The isothermal solidification completion time is overestimated by the existing analytical models, even by the closest one to the real bonding conditions, known as the moving interface model. It was found that the boride formation in the diffusion affected zone of Ni-based superalloy upon using B-containing filler metals is one of the reasons behind the inability of the moving interface model to predict the isothermal solidification completion time accurately, which has received scant attention in the literature. Moreover, simplified...
Multivariate curve resolution alternating least-squares as a tool for analyzing crude oil extracted asphaltene samples
, Article Energy and Fuels ; Volume 26, Issue 9 , 2012 , Pages 5663-5671 ; 08870624 (ISSN) ; Hemmateenejad, B ; Sedghamiz, T ; Khosousi, T ; Ayatollahi, S ; Seiedi, O ; Sayyad Amin, J ; Sharif University of Technology
ACS
2012
Abstract
Asphaltene deposition in the early stage of the oil reservoir life and later during any stimulation process emerges critical problems to the petroleum industry. Deposition of asphaltene aggregates raises strict problems in industries and demands markedly a practical and scientific knowledge of the mechanisms of aggregation and precipitation. Fluorescence emission spectroscopy has been widely used to illuminate the fundamental properties of crude oils and asphaltenes. It proposes analysis of some details of equilibrium, dynamic behavior, and aggregation composition of crude oil under specific condition. In this work, the fluorescence spectra of crude-oil extracted asphaltene samples were...
Electrodeposition of long gold nanotubes in polycarbonate templates as highly sensitive 3D nanoelectrode ensembles
, Article Electrochimica Acta ; Volume 75 , 2012 , Pages 157-163 ; 00134686 (ISSN) ; Ghorbani, M ; Dolati, A ; Sharif University of Technology
Elsevier
2012
Abstract
Electrodeposition of long and well-defined gold nanotubes in polycarbonate (PC) templates is still a major concern due to pore blockage problems. In the present study, we introduce a novel method for electrodeposition of long gold nanotubes within the pores of PC templates for the first time. In order to deposit gold atoms onto the pore walls preferentially, pore walls were functionalized with a coupling agent. Short and thin Ni nanotubes were then electrodeposited at the bottom of the pores. Gold nanotubes were subsequently electrodeposited at constant potentials and low solution concentrations. The morphology of nanotubes was characterized by electron microscopy and their formation...
A modified model on solute alloying element effect in Al-Mg alloys: Mechanical properties and dislocation density evolutions
, Article Materials and Design ; Volume 36 , 2012 , Pages 804-808 ; 02641275 (ISSN) ; Kazeminezhad, M ; Sharif University of Technology
2012
Abstract
A modified dislocation based model is introduced to explain the flow stress of Al-Mg alloys at different temperatures and strain rates considering solute alloying element concentration. The solute effect on flow stress is studied on the basis of storage and annihilation of dislocation. It is studied that how the increase of solute content can postpone the dislocation annihilation and how this can affect the storage phenomenon. It is found that the increasing of solute concentration can postpone the beginning of dislocation annihilation through deformation and also increase the critical strain that plateau occurs in plot of annihilation of dislocation versus shear strain. Thus, the plateau...
Fabrication of PLA/PEG/MWCNT electrospun nanofibrous scaffolds for anticancer drug delivery
, Article Journal of Applied Polymer Science ; Volume 132, Issue 3 , August , 2015 ; 00218995 (ISSN) ; Rad, L. R ; Irani, M ; Haririan, I ; Sharif University of Technology
John Wiley and Sons Inc
2015
Abstract
In the present study, polylactic acid (PLA)/polyethylene glycol (PEG)/multiwalled carbon nanotube (MWCNT) electrospun nanofibrous scaffolds were prepared via electrospinning process and their applications for the anticancer drug delivery system were investigated. A response surface methodology based on Box-Behnken design (BBD) was used to evaluate the effect of key parameters of electrospinning process including solution concentration, feeding rate, tip-collector distance (TCD) and applied voltage on the morphology of PLA/PEG/MWCNT nanofibrous scaffolds. In optimum conditions (concentration of 8.15%, feeding rate of 0.2 mL/h, voltage of 18.50 kV and TCD of 13.0 cm), the minimum experimental...
The Effects of Various Parameters on Wellbore Stability During Drilling Through Shale Formations
, Article Petroleum Science and Technology ; Volume 33, Issue 12 , 2015 , Pages 1275-1285 ; 10916466 (ISSN) ; Ghotbi, C ; Pishvaie, M. R ; Sharif University of Technology
Taylor and Francis Inc
2015
Abstract
Field evidence indicates that the thermal and chemical regimes in wellbore considerably affect the wellbore stability. This study presents a general coupled model for transport of solute, solvent and heat including their combined effects on the wellbore stability. Optimization of drilling fluid parameters is crucial for wellbore stability analysis particularly in high pressure-high temperature environments. The coupled effects of chemical potential and temperature gradients on fluid flow significantly change the pore pressure and stress around a borehole. The effects of various parameters such as mud weight, solute concentration gradient, shale properties, and temperature gradient on...
Computational-based approach for predicting porosity of electrospun nanofiber mats using response surface methodology and artificial neural network methods
, Article Journal of Macromolecular Science, Part B: Physics ; Volume 54, Issue 11 , 2015 , Pages 1404-1425 ; 00222348 (ISSN) ; Khodaparast Haghi, A ; Kasaei, S ; Hasanzadeh, M ; Sharif University of Technology
Taylor and Francis Inc
2015
Abstract
Comparative studies between response surface methodology (RSM) and artificial neural network (ANN) methods to find the effects of electrospinning parameters on the porosity of nanofiber mats is described. The four important electrospinning parameters studied included solution concentration (wt.%), applied voltage (kV), spinning distance (cm) and volume flow rate (mL/h). It was found that the applied voltage and solution concentration are the two critical parameters affecting the porosity of the nanofiber mats. The two approaches were compared for their modeling and optimization capabilities with the modeling capability of RSM showing superiority over ANN, having comparatively lower values of...
Photocatalytic reduction of graphene oxide nanosheets on TiO2 thin film for photoinactivation of bacteria in solar light irradiation
, Article Journal of Physical Chemistry C ; Volume 113, Issue 47 , 2009 , Pages 20214-20220 ; 19327447 (ISSN) ; Ghaderi, E ; Sharif University of Technology
Abstract
Graphene oxide platelets synthesized by using a chemical exfoliation method were deposited on anatase TiO2 thin films. Postannealing of the graphene oxide/TiO2 thin films at 400 °C in air resulted in partial formation of a Ti-C bond between the platelets and their beneath thin film. By using atomic force microscopy and X-ray photoelectron spectroscopy analyses, UV-visible light-induced photocatalytic reduction of the graphene oxide platelets of the annealed graphene oxide/TiO2. thin films immersed in ethanol was studied for the different irradiation times. After 4 h of photocatalytic reduction, the vertical space between the platelets decreased from about 1.1 to less than 0.8 nm and the...
Polyvinyl alcohol and polyvinyl alcohol/ polyvinyl pyrrolidone biomedical foams crosslinked by gamma irradiation
, Article Journal of Cellular Plastics ; Volume 53, Issue 4 , 2017 , Pages 359-372 ; 0021955X (ISSN) ; Frounchi, M ; Dadbin, S ; Sharif University of Technology
SAGE Publications Ltd
2017
Abstract
Foams for biomedical applications were made from polyvinyl alcohol, polyvinyl alcohol / polyvinyl pyrrolidone blend and their nanocomposites with nanoclay by clean processes. Air was entrapped into the aqueous polymer solutions during vigorous mixing and then the solutions were freeze-dried. The foams structure was stabilized by crosslinking via gamma irradiation without using any harmful chemicals. The hydrophilic biocompatible foams possessed interconnected open cell structure with remarkable capacity to absorb and retain water. The foams in wet state were soft and flexible. Desirable pore structure and higher water absorption was obtained at a solution concentration of 5 wt% for both...
Porous gelatin/poly(ethylene glycol) scaffolds for skin cells
, Article Soft Materials ; Volume 15, Issue 1 , 2017 , Pages 95-102 ; 1539445X (ISSN) ; Frounchi, M ; Dadbin, S ; Sharif University of Technology
Abstract
Biocompatible porous polymeric scaffolds provide a suitable environment for proliferation of stem cells in human body. In this research work, porous gelatin–poly(ethylene glycol), PEG, based scaffolds were prepared using combination of freeze-gelation and freeze-extraction methods. Effects of various parameters such as freezing temperature, cross-linking agent, concentrations of gelatin and PEG and their blending ratio on physical and mechanical properties, swelling ratio, porosity, pore size, and degradation rate of scaffolds were investigated. Also, proliferation of fibroblast skin cells on the scaffolds was examined by MTS assay to assess the suitability of the scaffolds in wound healing...