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    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 Azadi Tabar, M ; 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... 

    Extraction of hydroxyapatite nanostructures from marine wastes for the fabrication of biopolymer-based porous scaffolds

    , Article Marine Drugs ; Volume 18, Issue 1 , 2020 Gheysari, H ; Mohandes, F ; Mazaheri, M ; Dolatyar, B ; Askari, M ; Simchi, A ; Sharif University of Technology
    MDPI AG  2020
    Three-dimensional porous nanocomposites consisting of gelatin-carboxymethylcellulose (CMC) cross-linked by carboxylic acids biopolymers and monophasic hydroxyapatite (HA) nanostructures were fabricated by lyophilization, for soft-bone-tissue engineering. The bioactive ceramic nanostructures were prepared by a novel wet-chemical and low-temperature procedure from marine wastes containing calcium carbonates. The effect of surface-active molecules, including sodium dodecyl sulfate (SDS) and hexadecyltrimethylammonium bromide (CTAB), on the morphology of HA nanostructures is shown. It is demonstrated that highly bioactive and monophasic HA nanorods with an aspect ratio > 10 can be synthesized in... 

    An energy-efficient controller for wirelessly-powered communication networks

    , Article IEEE Transactions on Communications ; Volume 68, Issue 8 , August , 2020 , Pages 4986-5002 Movahednasab, M ; Makki, B ; Omidvar, N ; Pakravan, M. R ; Svensson, T ; Zorzi, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2020
    In a wirelessly-powered communication network (WPCN), an energy access point (E-AP) supplies the energy needs of the network nodes through radio frequency wave transmission, and the nodes store their received energy in their batteries for possible data transmission. In this paper, we propose an online control policy for energy transfer from the E-AP to the wireless nodes and for data transfer among the nodes. With our proposed control policy, all data queues of the nodes are stable, while the average energy consumption of the network is shown to be within a bounded gap of the minimum energy required for stabilizing the network. Our proposed policy is designed using a quadratic Lyapunov... 

    Thermo-hydro-mechanical modeling of fracturing porous media with two-phase fluid flow using X-FEM technique

    , Article International Journal for Numerical and Analytical Methods in Geomechanics ; Volume 44, Issue 18 , October , 2020 , Pages 2430-2472 Khoei, A. R ; Mortazavi, S. M. S ; Sharif University of Technology
    John Wiley and Sons Ltd  2020
    In this paper, a fully coupled thermo-hydro-mechanical model is presented for two-phase fluid flow and heat transfer in fractured/fracturing porous media using the extended finite element method. In the fractured porous medium, the traction, heat, and mass transfer between the fracture space and the surrounding media are coupled. The wetting and nonwetting fluid phases are water and gas, which are assumed to be immiscible, and no phase-change is considered. The system of coupled equations consists of the linear momentum balance of solid phase, wetting and nonwetting fluid continuities, and thermal energy conservation. The main variables used to solve the system of equations are solid phase... 

    Core flooding tests to investigate the effects of IFT reduction and wettability alteration on oil recovery during MEOR process in an Iranian oil reservoir

    , Article Applied Microbiology and Biotechnology ; Volume 97, Issue 13 , July , 2013 , Pages 5979-5991 ; 01757598 (ISSN) Rabiei, A ; Sharifinik, M ; Niazi, A ; Hashemi, A ; Ayatollahi, S ; Sharif University of Technology
    Microbial enhanced oil recovery (MEOR) refers to the process of using bacterial activities for more oil recovery from oil reservoirs mainly by interfacial tension reduction and wettability alteration mechanisms. Investigating the impact of these two mechanisms on enhanced oil recovery during MEOR process is the main objective of this work. Different analytical methods such as oil spreading and surface activity measurements were utilized to screen the biosurfactant-producing bacteria isolated from the brine of a specific oil reservoir located in the southwest of Iran. The isolates identified by 16S rDNA and biochemical analysis as Enterobacter cloacae (Persian Type Culture Collection (PTCC)... 

    Effects of low salinity water on calcite/brine interface: a molecular dynamics simulation study

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 537 , January , 2018 , Pages 61-68 ; 09277757 (ISSN) Koleini, M. M ; Fattahi Mehraban, M ; Ayatollahi, S ; Sharif University of Technology
    Elsevier B.V  2018
    Calcite is among the most abundant minerals organizing the oil reservoir formation and therefore its surface properties play a central role in the increase of the oil recovery efficiency. The effect of low-salinity water in carbonate rocks reveals that brine composition and salinity can improve the oil recovery in carbonates through wettability alteration. However, the specific mechanism for wettability changes that leads to improved oil recovery in calcite is not well understood. To obtain deeper insights at atomic level into the understanding the characteristics of the calcite-water interface, we performed classical molecular dynamics simulations in the presence of different ions in brine... 

    Synthesis of dimethyl ether over modified H-mordenite zeolites and bifunctional catalysts composed of Cu/ZnO/ZrO2 and modified H-mordenite zeolite in slurry phase

    , Article Catalysis Letters ; Volume 129, Issue 1-2 , 2009 , Pages 111-118 ; 1011372X (ISSN) Khandan, N ; Kazemeini, M ; Aghaziarati, M ; Sharif University of Technology
    Synthesis of dimethyl ether (DME) via methanol dehydration were investigated over various catalysts, and via direct CO hydrogenation over hybrid catalysts composed of Al-modified H-Mordenite zeolite and Cu/ZnO/ZrO 2. H-Mordenite zeolite exhibited the highest activity in dehydration of methanol. However, its selectivity toward dimethyl ether was rather low. For this reason, the H-Mordenite was modified. Modification of zeolites was performed by wet impregnation method and considered catalysts were characterized by AAS, XRD and NH3-TPD analyses. Results of catalytic tests indicated that H-Mordenite modified with 8 wt% aluminum oxide was the best catalyst for synthesis of dimethyl ether from... 

    Assessment of nitrate contamination in unsaturated zone of urban areas: the case study of Tehran, Iran

    , Article Environmental Geology ; Volume 57, Issue 8 , 2009 , Pages 1785-1798 ; 09430105 (ISSN) Joekar Niasar, V ; Ataie Ashtiani, B ; Sharif University of Technology
    Modeling fate of nitrogen in unsaturated and saturated zone is a complex process, which requires detailed geochemical data. Complexities of the process as well as data insufficiencies are two major issues, which make quantitative assessment of the problem more complicated. In this work, a lumped-parameter model (LPM) is proposed that has been evaluated for a data-limited case to study temporal and steady-state behavior of Nitrate and Ammonium in unsaturated zone. The concentration of components in the model are assumed as the depth-averaged concentrations, and dispersive fluxes have been neglected. The case study area is Tehran City aquifer, which is highly contaminated by domestic... 

    Microfluidic devices with gold thin film channels for chemical and biomedical applications: a review

    , Article Biomedical Microdevices ; Volume 21, Issue 4 , 2019 ; 13872176 (ISSN) Ghasemi Toudeshkchoui, M ; Rabiee, N ; Rabiee, M ; Bagherzadeh, M ; Tahriri, M ; Tayebi, L ; Hamblin, M. R ; Sharif University of Technology
    Springer New York LLC  2019
    Microfluidic systems (MFS) provide a range of advantages in biomedical applications, including improved controllability of material characteristics and lower consumption of reagents, energy, time and money. Fabrication of MFS employs various materials, such as glass, silicon, ceramics, paper, and metals such as gold, copper, aluminum, chromium and titanium. In this review, gold thin film microfluidic channels (GTFMFC) are discussed with reference to fabrication methods and their diverse use in chemical and biomedical applications. The advantages of gold thin films (GTF) include flexibility, ease of manufacture, adhesion to polymer surfaces, chemical stability, good electrical conductivity,... 

    Delafossite-alumina nanocomposite for enhanced catalytic wet peroxide oxidation of anionic pollutants

    , Article Journal of Hazardous Materials ; Volume 417 , 2021 ; 03043894 (ISSN) Nazari, P ; Nouri, O ; Xie, Z ; Setayesh, S. R ; Wei, Z ; Sharif University of Technology
    Elsevier B.V  2021
    Mass transfer efficiency and catalytic reactivity are the two major hurdles for heterogeneous catalytic wet peroxide oxidation (CWPO) technologies. To address these issues, nanocomposite CuFeO2/Al2O3 was synthesized and assessed as a novel catalyst for enhanced adsorption and oxidation of anionic pollutants (catechol and reactive red 195 (RR195)) in waters. With a positive charge on the nanocomposite by introducing Al2O3, the adsorption of anionic pollutants was promoted. The surface complexation reaction on CuFeO2/Al2O3, which fits well to the Langmuir isotherm, has engined the mass transfer of pollutants to the nanocatalyst that demonstrated 96.46% and 99.75% removal of catechol and RR195... 

    An efficient biosurfactant-producing bacterium pseudomonas aeruginosa MR01, isolated from oil excavation areas in south of Iran

    , Article Colloids and Surfaces B: Biointerfaces ; Volume 69, Issue 2 , 2009 , Pages 183-193 ; 09277765 (ISSN) Bagheri Lotfabad, T ; Shourian, M ; Roostaazad, R ; Rouholamini Najafabadi, A ; Adelzadeh, M. R ; Akbari Noghabi, K ; Sharif University of Technology
    A bacterial strain was isolated and cultured from the oil excavation areas in tropical zone in southern Iran. It was affiliated with Pseudomonas. The biochemical characteristics and partial sequenced 16S rRNA gene of isolate, MR01, was identical to those of cultured representatives of the species Pseudomonas aeruginosa. This bacterium was able to produce a type of biosurfactant with excessive foam-forming properties. Compositional analysis revealed that the extracted biosurfactant was composed of high percentages lipid (∼65%, w/w) and carbohydrate (∼30%, w/w) in addition to a minor fraction of protein (∼4%, w/w). The best production of 2.1 g/l was obtained when the cells were grown on...