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surface-modification
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Surface Modification of Hemodialysis Membrane for Enhancement of Their Performance
, M.Sc. Thesis Sharif University of Technology ; MoosavI, Abbas (Supervisor) ; Abdekhodaie, Mohammad Jafar (Supervisor)
Abstract
A new technique for surface modification of flat sheet hemodialysis membranes has been investigated. This new strategy presents a dynamic surface modification for membranes in order to assess the hydrophilicity, antifouling, and biocompatibility effects of two functional monomers on dialysis membrane. PSF membranes containing polyvinylpyrrolidone were prepared via phase inversion technique. Afterward, free radical polymerization combined with surface polymerization used to introduce acrylic acid and 2-hydroxyethyl methacrylate onto polysulfone membrane surface. Various monomer concentrations were selected to obtain an optimum condition. Field emission scanning electron microscope (FE-SEM),...
Surface Modification of Polysulfone Membrane by Plasma Treatment for CO2/CH4 Separation
, M.Sc. Thesis Sharif University of Technology ; Soltanieh, Mohammad (Supervisor)
Abstract
Low frequency (LF) O2 plasma was used to modify the surface of polysulfone (PSF) gas separation membranes. The effect of treatment time and plasma power input on the membranes was also investigated. Pure CO2 and CH4 gas permeation measurements were performed before and after plasma treatment. The results showed the increase of permeability of the treated membranes due to surface ablation and surface polarization. However, the CO2/CH4 permselectivity of the treated membranes varied from 7.7 to 45.3 depending on the treatment conditions. Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy determined the introduction of oxygen containing polar groups on the surface...
Effect of Surface Treatment and Tool Rotational Speed in Aluminum to Polymeric Composite Joint Produced Using Friction Stir/Adhesive Hybrid Process
, M.Sc. Thesis Sharif University of Technology ; Movahedi, Mojtaba (Supervisor)
Abstract
Today because of increasing use of fuel, environmental problems and problems due to heavy structures in different industries it is important to use structures with high specific strength. Using different materials in structures like polymers accompanying aluminum could be useful. Polymers are light, heat insulating and have a high corrosion resistance. Polypropylene is one of the useful polymers which can have high impact energy and strength via adding Elastomer and Talc powder, relatively. One of the common ways in joining metal to polymer uses adhesive. It has variety of benefits such as low distortion in joining, different materials joints and having joints with complex geometry. Welding...
The stability and surface activity of environmentally responsive surface-modified silica nanoparticles: the importance of hydrophobicity
, Article Journal of Dispersion Science and Technology ; Volume 41, Issue 9 , 2020 , Pages 1299-1310 ; Mohammadi, A ; Sharif University of Technology
Taylor and Francis Inc
2020
Abstract
In this study, the effect of hydrophobicity of environmentally responsive surface-modified silica nanoparticles on the stability and surface activity of the nanoparticles is examined. To this end, n-propyl, n-hexyl, or n-octyl chains and methoxy poly(ethylene glycol) chains at various quantities were coated covalently on the surface of silica nanoparticles to regulate the hydrophobicity of the responsive nanoparticles. Various experimental tools such as stability analysis, interfacial-tension and contact-angle measurements, and emulsion formation were performed to investigate the effect of hydrophobicity. It became evident that the presence of the hydrophobic agents influences considerably...
Synthesis of methyltriethoxysilane-modified calcium zinc phosphate nanopigments toward epoxy nanocomposite coatings: Exploring rheological, mechanical, and anti-corrosion properties
, Article Progress in Organic Coatings ; Volume 171 , 2022 ; 03009440 (ISSN) ; Alibakhshi, E ; Labani Motlagh, A ; Ramazani S. A., A ; Ghaderi, M ; Ramezanzadeh, B ; Mahdavian, M ; Arjmand, M ; Sharif University of Technology
Elsevier B.V
2022
Abstract
In this study, the effects of unmodified calcium zinc phosphate (UCZP) and modified calcium zinc phosphate (MCZP) nanopigments (NPs) on the rheological, mechanical, and corrosion protection performance (CPP) of the epoxy (EP) coatings were investigated. Transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were used to study morphology and overall chemical structure of synthesized calcium zinc phosphate (CZP) NPs, respectively. The grafting of methyltriethoxysilane (MTES) molecules on the surface of CZP was assessed using Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and...
Surface modification of polysulfone ultrafiltration membranes by free radical graft polymerization of acrylic acid using response surface methodology
, Article Journal of Polymer Research ; Volume 26, Issue 9 , 2019 ; 10229760 (ISSN) ; Asadollahi, M ; Mousavi, S. A ; Bastani, D ; Aghaeifard, F ; Sharif University of Technology
Springer Netherlands
2019
Abstract
In this research, polysulfone (PSf) ultrafiltration (UF) membranes were prepared by a phase inversion method. Surface modification of the PSf membranes was carried out via grafting of acrylic acid as a hydrophilic monomer by free radical graft polymerization initiated by redox reaction. A central composite design (CCD) of response surface methodology (RSM) was applied to design the experiments. The process variables were acrylic acid concentration (CAA), redox system contact time (T1), and acrylic acid polymerization time (T2), while the contact angle (CA), pure water flux (PWF), and flux recovery ratio (FRR) were considered as the responses. Analysis of variance (ANOVA) demonstrated that...
Surface modification for titanium implants by hydroxyapatite nanocomposite
, Article Caspian Journal of Internal Medicine ; Volume 3, Issue 3 , 2012 , Pages 460-465 ; 20086164 (ISSN) ; Solati Hashjin, M ; Nik, S. N ; Nemati, A ; Sharif University of Technology
2012
Abstract
Background: Titanium (Ti) implants are commonly coated with hydroxyapatite (HA). However, HA has some disadvantages such as brittleness, low tensile strength and fracture toughness. It is desirable to combine the excellent mechanical properties of ZrO 2 and the chemical inertness of Al 2O 3 with respect to the purpose of this project which was coating Ti implants with HA-ZrO 2-Al 2O 3 to modify the surface of these implants by adding ZrO 2 and Al 2O 3 to HA. The purpose of this study was to evaluate the efficacy of hydroxyapatite coating nonocomposite. Methods: From September 2009 to January2011, functionally graded HA-Al 2O 3-ZrO 2 and HA coatings were applied on Ti samples. HA-Al 2O 3-ZrO...
Surface chemistry of atmospheric plasma modified polycarbonate substrates
, Article Applied Surface Science ; Volume 257, Issue 23 , September , 2011 , Pages 9836-9839 ; 01694332 (ISSN) ; Taghavinia, N ; Sharif University of Technology
2011
Abstract
Surface of polycarbonate substrates were activated by atmospheric plasma torch using different gas pressure, distance from the substrates, velocity of the torch and number of treatments. The modifications were analyzed by contact angle measurements, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and UV-vis spectrophotometry. Plasma treatment caused the surface characteristics to become more hydrophilic as measured by the water contact angle, which decreased from 88° to 18°. The decrease in contact angle was mainly due to oxidation of the surface groups, leading to formation of polar groups with hydrophilic property. XPS results showed an increase in the intensity of...
Supramolecular polycaprolactone nanocomposite based on functionalized hydroxyapatite
, Article Journal of Bioactive and Compatible Polymers ; Volume 27, Issue 5 , January , 2012 , Pages 467-480 ; 08839115 (ISSN) ; Shokrollahi, P ; Atai, M ; Omidian, H ; Bagheri, R ; Sharif University of Technology
SAGE
2012
Abstract
Arms bearing ureido-pyrimidinone functional groups with self-association capability (through quadruple hydrogen bonds) were successfully grafted onto hydroxyapatite nanoparticles. The supramolecularly modified nanoparticles (nHApUPy) exhibited enhanced colloidal stability compared to the original hydroxyapatite nanoparticles and were uniformly dispersed in supramolecular polycaprolactone in PCL(UPy)2/HApUPy nanocomposites at different filler loadings. The combined atomic force microscopy, mechanical, and rheological analyses confirmed a high degree of compatibility of HApUPy nanoparticles with the polymer matrix. The temperature dependence of the supramolecular structure in PCL(UPy)2/HApUPy...
Superparamagnetic iron oxide nanoparticles (SPIONs): Development, surface modification and applications in chemotherapy
, Article Advanced Drug Delivery Reviews ; Volume 63, Issue 1-2 , January–February , 2011 , Pages 24-46 ; 0169409X (ISSN) ; Sant, S ; Wang, B ; Laurent, S ; Sen, T ; Sharif University of Technology
2011
Abstract
At present, nanoparticles are used for various biomedical applications where they facilitate laboratory diagnostics and therapeutics. More specifically for drug delivery purposes, the use of nanoparticles is attracting increasing attention due to their unique capabilities and their negligible side effects not only in cancer therapy but also in the treatment of other ailments. Among all types of nanoparticles, biocompatible superparamagnetic iron oxide nanoparticles (SPIONs) with proper surface architecture and conjugated targeting ligands/proteins have attracted a great deal of attention for drug delivery applications. This review covers recent advances in the development of SPIONs together...
Study of cemented carbonitrides with nickel as binder: Experimental investigations and computer calculations
, Article International Journal of Refractory Metals and Hard Materials ; Volume 31 , 2012 , Pages 164-170 ; 02634368 (ISSN) ; Abachi, P ; Parvin, N ; Pourazrang, K ; Sharif University of Technology
2012
Abstract
Cobalt is the most common binder in cemented carbides industry. However, there are some interests in use of alternatives. The similarity in properties has made nickel the first choice. In the present work, the effect of initial composition on modern hardmetals containing transition metal carbides/carbonitrides that are called "cemented carbonitrides" with nickel as binder was investigated. Change in quantity of additive carbides and tungsten to carbon (C/W) weight ratio through applying metallic tungsten powder in primary powder mixture had some effects on final hardness, transverse rupture strength, and microstructure of studied alloys. Addition of vanadium carbide not more than 0.2 wt.%,...
Specific targeting delivery to MUC1 overexpressing tumors by albumin-chitosan nanoparticles conjugated to DNA aptamer
, Article International Journal of Pharmaceutics ; Volume 515, Issue 1-2 , 2016 , Pages 607-615 ; 03785173 (ISSN) ; Mohammadi, A ; Atyabi, F ; Nabavi, S. M ; Ebrahimi, S. M ; Shahmoradi, E ; Shiri Varnamkhasti, B ; Ghahremani, M. H ; Dinarvand, R ; Sharif University of Technology
Elsevier B.V
2016
Abstract
Chitosan-coated human serum albumin nanoparticles were functionalized by MUC1 aptamer to obtain a selective drug carrier toward cancers overexpressing MUC1. The negative charges of albumin nanoparticles were shifted to positive charges by surface modification with chitosan, and MUC1 was conjugated through an acrylate spacer. The cytotoxicity of targeted nanoparticles was significantly more than non-aptamer nanoparticles, and also the chitosan-coated nanoparticles had more cytotoxic effects than the negatively charged albumin nanoparticles. The IC50 of targeted nanoparticles was 28 and 26% of free paclitaxel in MCF7 and T47D cells at 48 h, respectively. Confocal laser scanning electron...
Smoothing and coverage improvement of SnO2 electron transporting layer by NH4F treatment: Enhanced fill factor and efficiency of perovskite solar cells
, Article Solar Energy ; Volume 228 , 2021 , Pages 253-262 ; 0038092X (ISSN) ; Zamani Meymian, M. R ; Mohamadkhani, F ; Taghavinia, N ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Surface modification of SnO2 electron transporting layer (ETL) plays a critical role in the performance of SnO2-based planar perovskite solar cells (PSC). Here, we show how long-time NH4F-based water bath treatment of SnO2 layer makes smoothing and morphological improvements and enhances the device performance. Recently it was shown that short-time NH4F treatment (2 sec) with spin coating method reduces interface traps by improving surface chemistry. Here we observe the smoothing of SnO2 films as a result of long-time NH4F treatment, which could be a result of a slight etching-deposition process. Absorption and resistivity measurements indicate that SnO2 etching process is involved in...
Simultaneous dual-functional photocatalysis by g-C3N4-based nanostructures
, Article ACS ES and T Engineering ; Volume 2, Issue 4 , 2022 , Pages 564-585 ; 26900645 (ISSN) ; Zaker Moshfegh, A ; Habibi Yangjeh, A ; Sillanpää, M ; Sharif University of Technology
American Chemical Society
2022
Abstract
Heterogeneous photocatalytic reactions have experienced many efforts in developing new materials to tackle environmental and energy crises through utilizing appropriate photocatalysts in wastewater treatment, H2 generation, organic transformations, CO2 reduction, N2 photofixation, and biomass conversion. While these processes are addressed in the literature separately, a recent innovative viewpoint is to employ a photocatalytic system to achieve simultaneously two or more functions. The challenging point is that the combination of two functions in one photocatalytic system requires a novel design and engineering of an appropriate semiconductor photocatalyst with special characteristics for...
Removal of fluoride from wastewater by natural and modified nano clinoptilolite zeolite
, Article Journal of Water and Environmental Nanotechnology ; Volume 5, Issue 3 , 2020 , Pages 270-282 ; Charkhi, A ; Kazemeini, M ; Yousefi, T ; Sharif University of Technology
Iranian Environmental Mutagen Society
2020
Abstract
In this study adsorption of fluoride ion from high-fluorine solutions (<2000 ppm) using the natural and modified ground clinoptilolite is investigated. These low-cost adsorbents are carefully characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray fluorescence (XRF), thermos-gravimetry (TGA) and differential scanning calorimeter analysis (DSC). In order to enhance the fluoride removal capacity of natural zeolite, it is milled into nano-powders and modified using hexadecyltriammoniumions (HDTMA+). The kinetic, equilibrium, and thermodynamic of fluoride adsorption are measured and described by the well-known...
Recent advances in the modification of carbon-based quantum dots for biomedical applications
, Article Materials Science and Engineering C ; Volume 120 , 2021 ; 09284931 (ISSN) ; Sedighi, O ; Tabatabaei Rezaei, N ; Abedini, A. A ; Malek Khachatourian, A ; Toprak, M. S ; Seifalian, A ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Carbon-based quantum dots (CDs) are mainly divided into two sub-groups; carbon quantum dots (CQDs) and graphene quantum dots (GQDs), which exhibit outstanding photoluminescence (PL) properties, low toxicity, superior biocompatibility and facile functionalization. Regarding these features, they have been promising candidates for biomedical science and engineering applications. In this work, we reviewed the efforts made to modify these zero-dimensional nano-materials to obtain the best properties for bio-imaging, drug and gene delivery, cancer therapy, and bio-sensor applications. Five main surface modification techniques with outstanding results are investigated, including doping, surface...
Recent advances in the modification of carbon-based quantum dots for biomedical applications
, Article Materials Science and Engineering C ; Volume 120 , 2021 ; 09284931 (ISSN) ; Sedighi, O ; Tabatabaei Rezaei, N ; Abedini, A. A ; Malek Khachatourian, A ; Toprak, M. S ; Seifalian, A ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Carbon-based quantum dots (CDs) are mainly divided into two sub-groups; carbon quantum dots (CQDs) and graphene quantum dots (GQDs), which exhibit outstanding photoluminescence (PL) properties, low toxicity, superior biocompatibility and facile functionalization. Regarding these features, they have been promising candidates for biomedical science and engineering applications. In this work, we reviewed the efforts made to modify these zero-dimensional nano-materials to obtain the best properties for bio-imaging, drug and gene delivery, cancer therapy, and bio-sensor applications. Five main surface modification techniques with outstanding results are investigated, including doping, surface...
Polymer matrix nanocomposites for heavy metal adsorption: a review
, Article Journal of the Iranian Chemical Society ; Volume 17, Issue 6 , 31 January , 2020 , Pages 1259-1281 ; Keikavousi Behbahan, A ; Sharif University of Technology
Springer
2020
Abstract
Heavy metals belong to a group of lethal environmental pollutants. Ongoing efforts targeted at safeguarding public health have led to considerable attention being focused on methods that allow efficient extraction of these toxic substances. Polymer nanocomposites (PNCs) with their special characteristics are a class of adsorbents that demonstrate high potential for use in heavy metal extraction. As this process of removal is predominantly governed by adsorption, various parameters in PNCs’ chemical structure, as well as the metal solutions, can have a significant effect on the adsorption process. Herein, this review undertakes a survey of recently developed PNCs and their metal adsorption...
Photocatalytic reforming of biomass-derived feedstock to hydrogen production
, Article Research on Chemical Intermediates ; Volume 48, Issue 5 , 2022 , Pages 1793-1811 ; 09226168 (ISSN) ; Naseri, A ; Abdollahi, N ; Samadi, M ; Moshfegh, A ; Sharif University of Technology
Springer Science and Business Media B.V
2022
Abstract
Worldwide energy and environmental issues are forcing researchers to develop a green approach to produce a clean energy. However, traditional methods in reforming of fossil fuels to produce hydrogen (H2) are causing CO2 emission. Hydrogen is therefore an indirect greenhouse gas with a global warming potential. Hydrogen with high specific energy density can be considered as an efficient energy carrier as compared to fossil fuels. But hydrogen production from water splitting reaction has low efficiency, which limits its generation by green approach. For addressing this issue, different chemical hole scavengers have been applied, which is causing further environmental and economic problems. By...
On the functionality of the polypyrrole nanostructures for surface modification of Co-free Li-rich layered oxide cathode applied in lithium-ion batteries
, Article Journal of Electroanalytical Chemistry ; Volume 914 , 2022 ; 15726657 (ISSN) ; Khatiboleslam Sadrnezhaad, S ; Voznyy, O ; Sharif University of Technology
Elsevier B.V
2022
Abstract
Co-free Li-rich manganese nickel oxide (LMNO) materials are emerging as an up-and-coming candidate for high-energy–density cathodes. However, they suffer from severe cycling capacity fading and poor performance rates. Herein, the surface functionalization of an LMNO cathode is designed by polypyrrole (PPy) nanostructure coating. We found that PPy nanoparticles@LMNO cathode exhibits high-capacity retention and enhanced rate capabilities, delivering a discharge capacity as high as 191 mAh g−1, with capacity retention of 96%, after ∼ 200 cycles at a current density of 20 mA g−1. The results indicate that the intercalation and doping pseudocapacitance can be varied depending on the synthesis...