Search for: surface-charge
Fabrication of multifunctional microfibrous and nanofibrous cellulose carriers and comparison of cell adhesion and spreading potential on them, Article Biointerface Research in Applied Chemistry ; Volume 10, Issue 3 , 2020 , Pages 5387-5391 ; Mohammadi, M ; Najafpour, G ; Golizadeh, M ; Haghighatnia, Y ; Karimi, A ; Sharif University of Technology
AMG Transcend Association 2020
Fibrous biomaterials have received much attention in tissue engineering and regenerative medicine due to their morphology, resembling extracellular matrix. In comparison to synthetic fibers, cellulose based fibers have interesting properties for cellular applications such as biodegradability, biocompatibility, simple preparation and their potential for chemical modification. Among cellulose derivatives, carboxymethyl cellulose and quaternized cellulose are the most important and valuable cellulose ethers which have anionic and cationic surface charge. In this research, we report the fabrication of multifunctional cellulose microfibrous and nanofibrous scaffolds and the comparison of adhesion...
Enhancement of surface adsorption-desorption rates in microarrays invoking surface charge heterogeneity, Article Sensors and Actuators, B: Chemical ; Volume 242 , 2017 , Pages 956-964 ; 09254005 (ISSN) ; Saidi, M. S ; Sadeghi, A ; Sharif University of Technology
Elsevier B.V 2017
This investigation is devoted to the influences of non-uniform wall characteristics on the surface adsorption-desorption rates in an electrokinetic microarray. Utilizing already explored electroosmotic and electrophoretic velocities, the species transport equations are solved by a finite-volume-based numerical approach. Uniform, sinusoidal, and pulse-like distributions of the zeta potential are considered in the analysis. The developed model is validated by comparing the results with those of two analytical solutions that are derived for limiting conditions. The results reveal that, in some cases, the surface charge heterogeneity can reduce the saturation time by more than 60%. The efficacy...
Carbon quantum dots modified anatase/rutile TiO2 photoanode with dramatically enhanced photoelectrochemical performance, Article Applied Catalysis B: Environmental ; Volume 269 , 2020 ; Chen, S ; Li, L ; Wang, J ; Zhang, Y ; Li, J ; Bai, J ; Xia, L ; Xu, Q ; Rahim, M ; Zhou, B ; Sharif University of Technology
Elsevier B.V 2020
TiO2 is a promising photoanode material for photoelectrochemical (PEC) water splitting, but its severe bulk recombination of photogenerated carriers, sluggish oxygen evolution reaction (OER) kinetics and poor visible light response are the main bottleneck problems. Here, the carbon quantum dots (CQDs) modified anatase/rutile TiO2 photoanode (CQDs/A/R-TiO2) was designed by growth of anatase TiO2 nanothorns on rutile TiO2 nanorods and further surface modification of CQDs. The results revealed that the A/R-TiO2 heterojunction significantly suppressed the bulk recombination of photogenerated carriers. With further incorporation of CQDs into A/R-TiO2, dramatical improvement of OER kinetics and...
M.Sc. Thesis Sharif University of Technology ; Asempour, Ahmad ; Ahmadian, Mohamadtaghi
Cancer is the second leading cause of death in the world, with a high annual cost of treatment. As the cancer progresses, the cancer cells in the bloodstream metastasize to other parts of the body, causing the disease to spread throughout the patient's body and disrupt organ functions. sepration of cancer cells in the bloodstream inhibits the growth of cancer. Cancer cells differ from healthy cells in some features, such as size, electrical charge and polarization. These features can be used to seprate cancer cells from healthy cells.In this study, cell surface electrical charge was used as a biomarker to seprate cancer cells. By passing blood flow through a chanal and applying an electrical...
Article Nano Letters ; Volume 16, Issue 9 , 2016 , Pages 5619-5630 ; 15306984 (ISSN) ; Saadati, M ; Jannesari, M ; Sharif University of Technology
American Chemical Society
A remote controllable working graphite nanostructured swimmer based on a graphene jet nanomotor has been demonstrated for the first time. Graphite particles with pyramidal-like morphologies were fabricated by the creation of suitable defects in wide high-purity graphite flakes followed by a severe sonication. The particles were able to be self-exfoliated in water after Na intercalation between the graphene constituents. The self-exfoliation resulted in jet ejection of graphene flakes from the end of the swimmers (with speeds as high as ∼7000 m/s), producing a driving force (at least ∼0.7 L (pN) where L (μm) is swimmer size) and consequently the motion of the swimmer (with average speed of...
Article Physics of Fluids ; Volume 29, Issue 12 , 2017 ; 10706631 (ISSN) ; Saidi, M. H ; Moosavi, A ; Sadeghi, A ; Sharif University of Technology
Semi-analytical solutions are obtained for the electrical potential, electroosmotic velocity, ionic conductance, and surface physicochemical properties associated with long pH-regulated nanochannels of arbitrary but constant cross-sectional area. The effects of electric double layer overlap, multiple ionic species, and surface association/dissociation reactions are all taken into account, assuming low surface potentials. The method of analysis includes series solutions which the pertinent coefficients are obtained by applying the wall boundary conditions using either of the least-squares or point matching techniques. Although the procedure is general enough to be applied to almost any...
M: XNi100- X (M = Ag, and Co) nanoparticles supported on CeO2 nanorods derived from Ce-metal organic frameworks as an effective catalyst for reduction of organic pollutants: Langmuir-Hinshelwood kinetics and mechanism, Article New Journal of Chemistry ; Volume 41, Issue 19 , 2017 , Pages 10948-10958 ; 11440546 (ISSN) ; Gholami, M. R ; Sharif University of Technology
Royal Society of Chemistry 2017
In this study, AgxNi100-x, and CoxNi100-x (x = 0, 20, 40, 60, 80, and 100) bimetallic nanoparticles were successfully decorated on the surface of CeO2 nanorods derived from Ce-metal organic frameworks (Ce-MOF). The as-synthesized products were characterized using different techniques including XRD, FE-SEM, EDX, TEM, ICP, and BET. The as-prepared nanocomposites showed remarkable catalytic activity towards the reduction of organic pollutants such as 4-nitrophenol (4-NP), and rhodamine-B dye (RhB) by NaBH4 solution, with high stability and reusability for five consecutive cycles. The obtained results indicated that among these nanocomposites, Ag80Ni20@CeO2, and Co60Ni40@CeO2 exhibited the best...
Surface electromagnetic waves supported by nano conducting layers with inhomogeneities in the conductivity profile, Article Optical and Quantum Electronics ; Volume 40, Issue 1 , 2008 , Pages 23-40 ; 03068919 (ISSN) ; Mehrany, K ; Sharif University of Technology
Conducting interfaces and nano conducting layers can support surface electromagnetic waves. Uniform charge layers of non-zero thickness and their asymptotic behavior toward conducting interfaces of infinitely small thicknesses, where the thin charge layer is modeled via a surface conductivity σ s , are already studied. Here, the possible effects of inhomogeneity in the conductivity profile of the thin conducting layers are investigated for the first time and a new approximate yet accurate enough analytical formulation for mode extraction in such structures is given. In order to rigorously analyze the structure and justify the proposed approximate formulation, the Galerkin's method with...
Wettability alteration of calcite rock from gas- repellent to gas-wet using a fluorinated nanofluid: A surface analysis study, Article Journal of Natural Gas Science and Engineering ; Volume 83 , 2020 ; Shafiei, Y ; Shayesteh, M ; Dehghan Monfared, A ; Ghazanfari, M. H ; Sharif University of Technology
Elsevier B.V 2020
Wettability alteration analysis form gas-repellent to gas-wet with the aid of chemical agents has been subjected of numerous studies. However, fundamental understanding of the effect of surface tension of liquid on repellency strength, the change in the intermolecular forces due to the adsorption of nanoparticles onto the rock surfaces, and exposure of treated rock in brine are not well discussed in the available literature. In this study, X-ray diffraction, Atomic Force Microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were applied to characterize the treated and fresh samples. Dynamic and static contact angle measurements were then combined with six methods...
Evaluation of cellular attachment and proliferation on different surface charged functional cellulose electrospun nanofibers, Article Carbohydrate Polymers ; Volume 207 , 2019 , Pages 796-805 ; 01448617 (ISSN) ; Karimi, A ; Gandomi Ravandi, S ; Vossoughi, M ; Khafaji, M ; Joghataei, M. T ; Faghihi, F ; Sharif University of Technology
Elsevier Ltd 2019
Fabrication and characterization of different surface charged cellulose electrospun scaffolds including cellulose acetate (CA), cellulose, carboxymethyl cellulose (CMC) and quaternary ammonium cationic cellulose (QACC) for biomedical applications have been reported in this research. Several instrumental techniques were employed to characterize the nanofibers. MTT assay and cell attachment studies were also carried out to determine the cytocompatibility, viability and proliferation of the scaffolds. Fabricated CA, cellulose, CMC and QACC nanofibers had 100–600 nm diameter, −9, −1.75, −12.8, + 22 mV surface potential, 2.5, 4.2, 7.2, 7 MPa tensile strength, 122, 320, 515, 482 MPa Young modules,...
Forbidden spatial frequencies in periodic structures composed of subwavelength nano conducting layers, Article 2006 International Conference on Nanoscience and Nanotechnology, ICONN 2006, Brisbane, 3 July 2006 through 6 July 2006 ; 2006 , Pages 474-477 ; 1424404533 (ISBN); 9781424404537 (ISBN) ; Rashidian, B ; Sharif University of Technology
Recently, electromagnetic slow wave propagation in Kronig-Penny photonic crystals composed of conducting interfaces constituted of extremely thin charge layers has been studied, where analytic expressions for Bloch wave numbers in terms of normalized frequency were derived, asymptotic behavior of electromagnetic slow wave propagation in these structures was investigated at different regimes, and the possibility of observing forbidden spatial frequencies was numerically demonstrated. In this manuscript, the existence and electromagnetic behavior of such waves together with the possibility of having forbidden spatial frequency are investigated by taking the finiteness of charge layer thickness...
Article 2006 International Conference on Nanoscience and Nanotechnology, ICONN 2006, Brisbane, 3 July 2006 through 6 July 2006 ; 2006 , Pages 501-504 ; 1424404533 (ISBN); 9781424404537 (ISBN) ; Rashidian, B ; Sharif University of Technology
Recently, a group of novel devices based on conducting interfaces has been proposed. These conducting interfaces can be implemented by using the inversion layer of MOS structures, trapped charges or depletion layer charges. It has been shown that these structures can support surface electromagnetic waves. In this paper, the coupling of surface electromagnetic waves supported by nano charge layers is analyzed and its asymptotic behavior toward conducting interfaces, where the thin charge layer of finite thickness is modeled via a surface conductivity σs, is numerically studied for the first time. The numerical results driven by coupled mode theory approach are justified by solving exact...
Experimental investigation on synergic effect of salinity and pH during low salinity water injection into carbonate oil reservoirs, Article Journal of Petroleum Science and Engineering ; Volume 202 , 2021 ; 09204105 (ISSN) ; Ayatollahi, S ; Sharifi, M ; Sharif University of Technology
Elsevier B.V 2021
Interaction between rock-fluid and fluid-fluid can have a significant effect on oil recovery. Changing the wettability of reservoir rock toward more water-wet or less oil-wet state is one of the expected mechanisms during low salinity water injection (LSWI). pH and salinity are of the most eminent factors of injection water controlling the wettability state of a crude oil/brine/rock system during any waterflooding operation. A small change in pH can affect the surface charges at the rock/water and oil/water interfaces leading to wettability alteration in a porous medium. In this study, the synergic effect of salinity and pH on the wettability state of carbonate rocks is evaluated through...
Wettability alteration in carbonates during "Smart Waterflood": Underling mechanisms and the effect of individual ions, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 487 , 2015 , Pages 142-153 ; 09277757 (ISSN) ; Mousapour, M. S ; Ayatollahi, S ; Vossoughi, M ; Beigy, A. H ; Sharif University of Technology
There are increasing evidences that adjusting the chemistry of the injecting water improves the oil recovery efficiency. However, the underlying mechanisms for this technique which is referred to as "smart waterflood" have not yet been thoroughly understood. It is needed to explore the role of individual ions through set of different tests, to find the right mechanisms behind "smart waterflood". This study is focused on the fluid/solid (carbonate) interactions through systematic wettability measurement. Contact angle measurements accompanied by spontaneous imbibition tests were employed to determine the role of individual monovalent and divalent ions in wettability alteration process by...
Mechanistic study of wettability alteration of oil-wet calcite: The effect of magnesium ions in the presence and absence of cationic surfactant, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 482 , October , 2015 , Pages 403-415 ; 09277757 (ISSN) ; Al Maamari, R. S ; Ayatollahi, S ; Mehranbod, N ; Sharif University of Technology
Over 60% of the world's discovered oil reserves are held in carbonate reservoirs, which are mostly naturally fractured. Conventional water flooding results in low oil recovery efficiency in these reservoirs as most of them are oil-wet. On account of negative capillary forces, injected brine cannot penetrate simply into an oil-wet matrix of fractured formations to force the oil out. Wettability alteration of the rock surface to preferentially more water-wet state has been extensively studied using both smart water and surfactants separately. This study aims to study the effects of Mg2+ as one of the most important wettability influencing ions on the wetting properties of oil-wet carbonate...
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
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...
Design of experiment, preparation, and in vitro biological assessment of human amniotic membrane extract loaded nanoparticles, Article Current Pharmaceutical Biotechnology ; Volume 21, Issue 3 , 2020 , Pages 256-267 ; Atyabi, F ; Khoshayand, M. R ; Mahbod, R ; Cohan, R. A ; Akbarzadeh, I ; Bakhshandeh, H ; Sharif University of Technology
Bentham Science Publishers 2020
Background: Human amniotic membrane grafting could be potentially useful in ocular surface complications due to tissue similarity and the presence of factors that reduce inflammation, vascu-larization, and scarring. However, considerations like donor-derived infectious risk and the requirement of an invasive surgery limit the clinical application of such treatments. Moreover, the quick depletion of bioactive factors after grafting reduces the efficacy of treatments. Therefore, in the current study, the possibility of nano delivery of the bioactive factors extracted from the human amniotic membrane to the ocular surface was investigated. Materials and Methods: Nanoparticles were prepared...