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    Cyto and genotoxicities of graphene oxide and reduced graphene oxide sheets on spermatozoa

    , Article RSC Advances ; Vol. 4, issue. 52 , May , 2014 , pp. 27213-27223 ; ISSN: 20462069 Hashemi, E ; Akhavan, O ; Shamsara, M ; Rahighi, R ; Esfandiar, A ; Tayefeh, A. R ; Sharif University of Technology
    Concentration-dependent cyto and genotoxicities of graphene oxide (GO) and reduced GO (rGO) sheets on spermatozoa were studied. rGO sheets with various surface chemical states were achieved using hydrazine (N2H 4) hydrothermal (HT) reactions and green tea polyphenols (GTPs). Although 0.1 μg mL-1 graphene could not change sperm viability and kinetic parameters, <40% and 20% of spermatozoa were viable and progressively motile, after 2 h incubation with 400 μg mL-1 GO or rGO, respectively. All the graphene nanomaterials induced concentration- dependent reductions of adenosine triphosphate and NAD+/NADH produced by spermatozoa for motility and metabolic activity. While GO, N 2H4-rGO, and HT-rGO... 

    Determination of Diffusion Coefficients of the Multi-components Gas-crude Oil Systems Considering Oil Swelling Effects at High Pressure High Temperature Conditions

    , M.Sc. Thesis Sharif University of Technology Rostami, Keyvan (Author) ; Ghazanfari, Mohammad Hossein (Supervisor)
    gas injection method is one of the common methods of EOR, which has a long history. In gas injection, molecular entry gas mixing is the controlling factor of oil play. Therefore, the exact value of this coefficient becomes an important requirement for the simulation and modeling of oil reservoirs, which can only be determined by laboratory consumption methods. In this research, the pressure decay method is used as a common laboratory method to determine the penetration coefficient of methane, nitrogen and gas enriched with intermediate compounds in crude oil of one of Iran's oil reservoirs. In most of the available records in the investigation of the mentioned gas diffusion coefficient in... 

    Cytotoxicity of protein corona-graphene oxide nanoribbons on human epithelial cells

    , Article Applied Surface Science ; Volume 320 , 30 November , 2014 , Pages 596-601 ; ISSN: 01694332 Mbeh, D. A ; Akhavan, O ; Javanbakht, T ; Mahmoudi, M ; Yahia, L ; Sharif University of Technology
    Graphene oxide nanoribbons (GONRs) were synthesized using an oxidative unzipping of multi-walled carbon nanotubes. The interactions of the GONRs with various concentrations of fetal bovine serum or human plasma serum indicated that the GONRs were functionalized substantially by the albumin originated from the two different protein sources. Then, concentration-dependent cytotoxicity of the protein-functionalized GONRs on human epithelial cells was studied. Although the GONRs with concentrations ≤50 μg/mL did not exhibit significant cytotoxicity on the cells (with the cell viability >85%), the concentration of 100 μg/mL exhibited significant cytotoxicity including prevention of cell... 

    Influence of heavy nanocrystals on spermatozoa and fertility of mammals

    , Article Materials Science and Engineering C ; Volume 69 , 2016 , Pages 52-59 ; 09284931 (ISSN) Akhavan, O ; Hashemi, E ; Zare, H ; Shamsara, M ; Taghavinia, N ; Heidari, F ; Sharif University of Technology
    Elsevier Ltd 
    In recent years, quantum dots (QDs) have been widely used in upcoming nanotechnology-based solar cells, light-emitting diodes and even bioimaging, due to their tunable optical properties and excellent quantum yields. But, such nanostructures are currently constituted by heavy elements which can threat the human health and living environment. Hence, in this work, the in vivo effects of CdTe nanocrystals (NCs) (as one of the promising QDs) on spermatozoa of male mice and subsequently on fertility of female mice were investigated, for the first time. To do this, CdTe NCs were synthesized through an environment-friendly (aqueous-based solution) method. The sperm cells presented a high potential... 

    Experimental investigation of constant and concentration-dependent diffusivity of a hydrocarbon solvents-heavy oil system: A comparative study

    , Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Volume 34, Issue 3 , 2011 , Pages 235-245 ; 15567036 (ISSN) Nasirahmadi, E ; Kharrat, R ; Ghazanfari, M. H ; Rashtchian, D ; Sharif University of Technology
    This work is concerned with the experimental investigation of mass transfer, which occurs during diffusion of hydrocarbon solvents in heavy oil based on constant and concentration-dependent diffusion coefficient. Here, a series of free fall diffusion experiments have been conducted in sealed test tubes at fixed temperatures. Pentane, hexane, and octane were used as solvents and were placed on heavy oil in tubes. The diffusivity of heavy oil into solvents was monitored by a digital camera. The image analysis technique was applied to extract concentration profiles in diffusion zones of solvents by means of calibration curves. Fick's second law was used to obtain both constant and... 

    Adverse effects of graphene incorporated in TiO 2 photocatalyst on minuscule animals under solar light irradiation

    , Article Journal of Materials Chemistry ; Volume 22, Issue 43 , 2012 , Pages 23260-23266 ; 09599428 (ISSN) Akhavan, O ; Ghaderi, E ; Rahimi, K ; Sharif University of Technology
    The adverse effect of graphene-titanium oxide composite films (containing sheet-like surface morphology) on Caenorhabditis elegans nematodes (as a model for minuscule animals) was investigated in a solar light-induced photocatalytic process. X-ray photoelectron spectroscopy demonstrated photocatalytic reduction of the chemically exfoliated graphene oxide sheets included in the TiO 2 film. Furthermore, formation of TiC and Ti-O-C bonds in the composite film (obtained through annealing at 450 °C in air) resulted in a substantial delay in the recombination rate of the photoexcited electron-hole pairs and more efficient photocatalytic processes. The composite film showed a type of... 

    Nontoxic concentrations of PEGylated graphene nanoribbons for selective cancer cell imaging and photothermal therapy

    , Article Journal of Materials Chemistry ; Volume 22, Issue 38 , 2012 , Pages 20626-20633 ; 09599428 (ISSN) Akhavan, O ; Ghaderi, E ; Emamy, H ; Sharif University of Technology
    Reduced graphene oxide nanoribbons functionalized by amphiphilic polyethylene glycol (rGONR-PEG) were applied to attach arginine-glycine-aspartic acid (RGD)-based peptide and cyanine dye 3 (cy3) for targeting ανβ3 integrin receptors on human glioblastoma cell line U87MG and its selective fluorescence imaging, respectively. The rGONR-PEG suspension with a concentration of 100 μg mL -1 showed ∼14 and 2.4-fold higher near infrared (NIR) absorption at 808 nm than GONR (with dimensions of ∼80 nm × 1 μm) and rGO-PEG sheets (with lateral dimensions of ∼2 μm), respectively. The rGONR-PEG-cy3-RGD exhibited highly efficient NIR photothermal therapy performance (concentrations ≥1.0 μg mL-1 resulted in... 

    Adaptive fuzzy backstepping approach for temperature control of continuous stirred tank reactors

    , Article Fuzzy Sets and Systems ; Volume 160, Issue 12 , 2009 , Pages 1804-1818 ; 01650114 (ISSN) Salehi, S ; Shahrokhi, M ; Sharif University of Technology
    In this paper, an adaptive fuzzy controller, based on backstepping technique, has been proposed for temperature control of a general class of continuous stirred tank reactors (CSTRs). Using the observability concept, an adaptive fuzzy controller using temperature measurement has been designed. A fuzzy logic system is used to estimate the concentration dependent terms and other unknown system parameters appearing in the control law. It is shown that the closed loop system is asymptotically stable and influences of minimum approximation error and external disturbance on the L2 norm of the output tracking error can be attenuated arbitrarily. The performance of the proposed controller has been... 

    On the adsorption behavior of a fluorochemical onto carbonate rock with the application of wettability alteration to a gas wetting condition

    , Article Journal of Molecular Liquids ; Volume 326 , 2021 ; 01677322 (ISSN) Shayesteh, M ; Azadi Tabar, M ; Shafiei, Y ; Fakhroueian, Z ; Ghazanfari, M. H ; Sharif University of Technology
    Elsevier B.V  2021
    In this study, some new aspects of adsorption of a fluorochemical onto carbonate rocks as a wettability alteration agent to a gas wetting condition with the potential application for reduction of condensate blockage in gas condensate reservoirs are presented. To achieve this, kinetics, equilibrium, and thermodynamic of the adsorption process besides contact angle, imbibition, and characterization tests are investigated. Results of adsorption experiments revealed that kinetics behavior of the utilized fluorochemical–calcite system obeyed the pseudo-second order kinetics model. There was no change in adsorption after about 20 h. Also, the intraparticle diffusion mechanism was not the only rate... 

    Improvement of polymer flooding using in-situ releasing of smart nano-scale coated polymer particles in porous media

    , Article Energy Exploration and Exploitation ; Volume 30, Issue 6 , 2012 , Pages 915-940 ; 01445987 (ISSN) Ashrafizadeh, M ; Ramazani, S. A. A ; Sadeghnejad, S ; Sharif University of Technology
    The main purpose of this paper is modeling and simulation of in-situ releasing of smart nano-sized core-shell particles at the water-oil interface during polymer flooding. During the polymer flooding process, when these nano-particles reach the water-oil interface, migrate to the oil phase and the hydrophobic layer of them dissolves in this phase. After dissolution of this protective nano-sized layer, the hydrophilic core containing a water-soluble ultra high molecular weight polymer diffuses back into the water phase and with dissolving in this phase, dramatically increases viscosity of flooding water in the neighborhood of the water-oil interface. In this study, two different...