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    Pore network-scale visualization of the effect of brine composition on sweep efficiency and speed of oil recovery from carbonates using a photolithography-based calcite microfluidic model

    , Article Journal of Petroleum Science and Engineering ; Volume 208 , 2022 ; 09204105 (ISSN) Mohammadi, M ; Nikbin Fashkacheh, H ; Mahani, H ; Sharif University of Technology
    Elsevier B.V  2022
    Abstract
    A novel photolithography-based technique was developed to fabricate a quasi-2D heterogeneous calcite micromodel of representative elementary volume size. The effect of brine-chemistry on the mobilization of capillarity and heterogeneity trapped oil after high salinity water injection was evaluated by using diluted seawater, and seawater modified with calcium, sulphate, and silica nanoparticles. Preliminary brine screening was performed based on modified contact angle experiments under dynamic salinity alteration. The main findings are that the chemical composition of brine impacts both the ultimate oil recovery and its speed. The highest and fastest oil recovery was obtained with diluted... 

    Enhanced electromagnetic wave dissipation features of magnetic Ni microspheres by developing core-double shells structure

    , Article Ceramics International ; Volume 48, Issue 1 , 2022 , Pages 446-454 ; 02728842 (ISSN) Zhang, B ; Mahariq, I ; Tran, N ; Mahmoud, M. Z ; Akhtar, M. N ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    Readily oxidization of magnetic particles is a common drawback of these type of materials which reduce their electromagnetic wave dissipation performance. In this study, the magnetic core-double shells structured (Ni/SiO2/Polyaniline) composite has been developed for protection of the core from oxidation and in consequent improvement the complex permittivity. Solvothermal and in-situ polymerization methods were utilized for decorating Ni micro-particles with SiO2 and conductive polyaniline polymer respectively. All physico-chemical, magnetic and electromagnetic features were evaluated via XRD, FTIR, XPS, FESEM, VSM and VNA analysis. The double shells composite possesses significant... 

    Effect of collision on self-assembly of nanoparticles in zirconia microparticle suspension

    , Article Journal of Dispersion Science and Technology ; Volume 43, Issue 6 , 2022 , Pages 787-795 ; 01932691 (ISSN) Jiryaei, Z ; Saidi, M. H ; Sharif University of Technology
    Taylor and Francis Ltd  2022
    Abstract
    Nanoparticle halo mechanism is a stabilization method for microparticle suspensions. This study investigates suspension pH and nanoparticles–microparticles collision effects on the stabilization of an aqueous binary suspension. The long-term turbidity measurements show that for the nanosilica suspension stability is directly correlated with pH values; however, in the cases of zirconia and binary suspensions, it is not a monotonic function of pH. It is shown that for binary suspension, the halo mechanism is the primary method affecting the stability of the suspension. The suspension is best-stabilized at pH = 5 that is associated with high halo mechanism efficiency, while increased repulsive... 

    Aperiodic perforated graphene in optical nanocavity absorbers

    , Article Materials Science and Engineering B: Solid-State Materials for Advanced Technology ; Volume 276 , 2022 ; 09215107 (ISSN) Bidmeshkipour, S ; Akhavan, O ; Salami, P ; Yousefi, L ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    Aperiodic perforated graphene layers were synthesized and used in fabrication of optical nanocavity absorbers. Chemical vapor deposition-grown graphene (Gr) layers were exposed to oxygen plasma etching to obtain the perforated graphene (pGr). The fabricated pGr/SiO2 (68 nm)/Ag (150 nm) nanocavity could present significant higher optical absorption, especially at around 530 nm wavelength region, as compared to a benchmark Gr/SiO2 (68 nm)/Ag (150 nm) sample. The effect of pore size of the pGr layer on the absorption property of the nanocavity has been studied by both experimental and numerical methods. The dependence of the absorption property of the nanocavity on the incident angles of... 

    Role of precursors and coating polymers in sol-gel chemistry toward enhanced selectivity and efficiency in solid phase microextraction

    , Article Analytica Chimica Acta ; Volume 742 , 2012 , Pages 45-53 ; 00032670 (ISSN) Bagheri, H ; Piri Moghadam, H ; Ahdi, T ; Sharif University of Technology
    Elsevier  2012
    Abstract
    To evaluate the selectivity and efficiency of solid phase microextraction (SPME) fiber coatings, synthesized by sol-gel technology, roles of precursors and coating polymers were extensively investigated. An on-line combination of capillary microextraction (CME) technique and high performance liquid chromatography (HPLC) was set up to perform the investigation. Ten different fiber coatings were synthesized in which five of them contained only the precursor and the rests were prepared using both the precursor and coating polymer. All the coatings were chemically bonded to the inner surface of copper tubes, intended to be used as the CME device and already functionalized by self-assembly... 

    Synthesis of some new 1,4-distyrylbenzenes using immobilized palladium nanoparticles on silica functionalized morpholine as a recyclable catalyst

    , Article Synthesis ; Issue 10 , 2011 , Pages 1609-1615 ; 00397881 (ISSN) Niknam, K ; Gharavi, A ; Nezhad, M. R. H ; Panahi, F ; Sharbati, M. T ; Sharif University of Technology
    Abstract
    Some new 1,4-distyrylbenzene derivatives were synthesized by using immobilized palladium nanoparticles on silica-bonded N-propyl morpholine (PNP-SBNPM) as a heterogeneous catalyst. These one-pot reactions afforded a range of stereoselective, symmetrical (E)-1,4-distyrylbenzene derivatives with high yields (78-90%). The green catalyst system is recyclable and allows facile product isolation. The recycled catalyst could be reused six times without appreciable loss of catalytic activity  

    Immobilization of synthesized phenyl-enriched magnetic nanoparticles in a fabricated Y–Y shaped micro-channel containing microscaled hedges as a microextraction platform

    , Article Analytica Chimica Acta ; Volume 1136 , 2020 , Pages 51-61 Rezvani, O ; Hedeshi, M. H ; Bagheri, H ; Sharif University of Technology
    Elsevier B.V  2020
    Abstract
    In this survey, a reliable and applicable Y–Y shaped micro–channel in a microfluidic device was designed and manufactured. A number of micro–scaled hedges were precisely fabricated inside the micro–channel to facilitate the immobilization of synthesized core–shell Fe3O4@SiO2 magnetic nanoparticles (MNPs), functionalized by triethoxyphenylsilane (TEPS) by sol-gel technique. Both sample and reagents were introduced into the microfluidic device by a syringe pump to perform the extraction and desorption steps. The functionalized MNPs were characterized by transmission electron microscopy, X-ray diffraction spectroscopy and Fourier transform infrared spectroscopy. By adopting the strategy of... 

    Simultaneous separation of H2S and CO2 from CH4 by a high silica CHA-type zeolite membrane

    , Article Journal of Membrane Science ; Vol. 470, issue , 2014 , pp. 159-165 ; ISSN: 03767388 Maghsoudi, H ; Soltanieh, M ; Sharif University of Technology
    Abstract
    A high silica CHA-type membrane was synthesized by the in-situ crystallization method on a disk like α-alumina porous support to separate both acid (H2S, CO2) gases from methane. The membrane showed a permeance of 3.39×10-8mol/m2sPa for pure CO2with CO2/CH4 ideal selectivity of 21.6 at 303K and 100kPa pressure difference across the membrane. The membrane was also tested with N2 and O2 pure gases indicating a small O2/N2 selectivity of 1.2-1.4, which shows that this type of membrane is not suitable for O2/N2 separation. The membrane performance was also analyzed by binary (CO2-CH4) and ternary (H2S-CO2-CH4) gas mixtures, with compositions near the real sour natural gas (CO2: 2.13mol%, H2S:... 

    Thermophysical and rheological behavior of polystyrene/silica nanocomposites: Investigation of nanoparticle content

    , Article Materials and Design ; Volume 32, Issue 8-9 , 2011 , Pages 4537-4542 ; 02641275 (ISSN) Vaziri, H. S ; Omaraei, I.A ; Abadyan, M ; Mortezaei, M ; Yousefi, N ; Sharif University of Technology
    Abstract
    In this work, solvent blending in combination with extruding are applied to provide polystyrene/silica nanocomposite specimens. Transmission electron microscope (TEM) and scanning electron microscope (SEM) show same nanoparticle dispersion in PS matrix in low to high filler loadings. Differential scanning calorimetry (DSC), dynamic mechanical thermal analyzer (DMTA) and thermogravimetric analyzer (TGA) were used to study the thermophysical characteristic of the nanocomposites in solid state. In addition, the melt state rheological behavior of the samples was investigated under constant and zero shear rates. Interestingly, different behaviors were detected in nanocomposites in low and high... 

    Influence of nano-SiO2 addition on microstructure and mechanical properties of cement mortars for ferrocement

    , Article Transportation Research Record ; Issue 2141 , 2010 , Pages 15-20 ; 03611981 (ISSN) Hosseini, P ; Booshehrian, A ; Farshchi, S ; Sharif University of Technology
    Abstract
    Because of their unique physical and chemical properties, nanoparticles have been gaining increasing attention and have been used in many fields to fabricate new materials with novel functions. If nanoparticles are integrated with cement-based building materials, the new materials might possess some outstanding properties. Ferrocement is a type of thin-wall reinforced concrete commonly constructed of hydraulic cement mortar reinforced with closely spaced layers of continuous and relatively small-sized wire mesh. The low level of technical skill required to make ferrocement and the ready availability of its materials make ferrocement suitable for a wide variety of applications. This study... 

    Study of molecular conformation and activity-related properties of lipase immobilized onto core-shell structured polyacrylic acid-coated magnetic silica nanocomposite particles

    , Article Langmuir ; Volume 32, Issue 13 , 2016 , Pages 3242-3252 ; 07437463 (ISSN) Esmaeilnejad Ahranjani, P ; Kazemeini, M ; Singh, G ; Arpanaei, A ; Sharif University of Technology
    American Chemical Society 
    Abstract
    A facile approach for the preparation of core-shell structured poly(acrylic acid) (PAA)-coated Fe3O4 cluster@SiO2 nanocomposite particles as the support materials for the lipase immobilization is reported. Low- or high-molecular-weight (1800 and 100 000, respectively) PAA molecules were covalently attached onto the surface of amine-functionalized magnetic silica nanoacomposite particles. The successful preparation of particles were verified by scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA), zeta potential measurement, and Fourier-transform infrared (FTIR) techniques. Once lipase is covalently... 

    Pulsed-laser annealing of NiTi shape memory alloy thin film

    , Article Journal of Materials Science and Technology ; Volume 25, Issue 1 , 2009 , Pages 135-140 ; 10050302 (ISSN) Sadrnezhaad, S. K ; Rezvani, E ; Sanjabi, S ; Ziaei Moayed, A. A ; Sharif University of Technology
    Abstract
    Local annealing of amorphous NiTi thin films was performed by using an Nd:YAG 1064 nm wavelength pulsed laser beam. Raw samples produced by simultaneous sputter deposition from elemental Ni and Ti targets onto unheated Si (100) and Silica (111) substrates were used for annealing. Delicate treatment with 15.92 W/mm2 power density resulted in crystallization of small spots; while 16.52 and 17.51 W/mm2 power densities caused ablation of the amorphous layer. Optical microscopy, scanning electron microscopy, X-ray diffraction and atomic force microscopy were performed to characterize the microstructure and surface morphology of the amorphous/crystallized spot patterns  

    Fabrication and characterization of graphene-based carbon hollow spheres for encapsulation of organic corrosion inhibitors

    , Article Chemical Engineering Journal ; Volume 352 , 2018 , Pages 909-922 ; 13858947 (ISSN) Haddadi, S. A ; Ramazani, S. A. A ; Mahdavian, M ; Taheri, P ; Mol, J. M. C ; Sharif University of Technology
    Elsevier B.V  2018
    Abstract
    In this work, we synthesized carbon hollow spheres (CHSs) using the silica templating method, encapsulated 2-mercaptobenzimidazole (MBI) inhibitor in the CHSs and evaluated their corrosion inhibition performance upon exposure of mild steel to a saline solution containing the released inhibitor. The effects of silica template surface modification on the CHS structure was evaluated, while the structure and morphology of the synthesized CHS was analyzed using field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), Raman spectroscopy and X-ray diffraction (XRD) spectroscopy. Furthermore, thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy... 

    Synthesis and characterization of CaO-P2O5-SiO2-Li2O-Fe2O3 bioactive glasses: The effect of Li2O-Fe2O3 content on the structure and in-vitro bioactivity

    , Article Journal of Non-Crystalline Solids ; 2018 ; 00223093 (ISSN) Arabyazdi, S ; Yazdanpanah, A ; Ansari Hamedani, A ; Ramedani, A ; Moztarzadeh, F ; Sharif University of Technology
    Elsevier B.V  2018
    Abstract
    CaO-P2O5-SiO2-Li2O-Fe2O3 magnetic bioactive glasses were prepared through an optimized sol-gel method. This study was emphasized on the effects of magnetic content addition on the bioactive glass properties. As the need arises, we study synthesized magnetic bioactive glass physical, rheological, and biocompatible properties. The morphology and composition of these glasses were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The particle size was also determined using a laser particle size analyzer (LPSA). The thermal measurements were put through using Differential thermal analysis (DTA). In order to evaluate the... 

    Monolithic dye sensitized solar cell with metal foil counter electrode

    , Article Organic Electronics ; Volume 57 , June , 2018 , Pages 194-200 ; 15661199 (ISSN) Behrouznejad, F ; Taghavinia, N ; Ghazyani, N ; Sharif University of Technology
    Elsevier B.V  2018
    Abstract
    Monolithic dye-sensitized solar cells are conventionally fabricated using carbon composite layer as the counter electrode. In the current research, the brittle carbon composite layer is replaced with a metal foil, aiming to decrease the device series resistance and using less catalyst material in counter electrode. This metallic structure has also an advantage of mechanical strength and decreases the fabrication complexity. The counter electrode is prepared by electrodepositing Cr film followed by electrodepositing Pt nanoparticles on a metal foil. As the porous spacer layer, different composite layers of SiO2, TiO2, and Al2O3 are investigated and the best results are obtained for TiO2... 

    Effects of physicochemical characteristics of magnetically recoverable biocatalysts upon fatty acid methyl esters synthesis from oils

    , Article Renewable Energy ; Volume 116 , 2018 , Pages 613-622 ; 09601481 (ISSN) Esmaeilnejad Ahranjani, P ; Kazemeini, M ; Singh, G ; Arpanaei, A ; Sharif University of Technology
    Elsevier Ltd  2018
    Abstract
    This study reports the importance of physicochemical characteristics of the core-shell structured polymer-coated Fe3O4 cluster@SiO2 nanocomposite particles for designing the biocatalysts used for transesterification of soybean oil. To demonstrate this issue, two different types of polymer molecules such as polyethylenimine (PEI) and polyacrylic acid (PAA) each with two different molecular weights are employed. The highest fatty acid methyl esters (FAMEs) synthesis yield values are achieved by the lipases immobilized onto the low- and high-molecular-weight PEI-coated particles as compared to those of the low- and high-molecular-weight PAA-coated particles (i.e., ∼64.8% and ∼73.1% versus... 

    Grand canonical Monte Carlo and molecular dynamics simulations of the structural properties, diffusion and adsorption of hydrogen molecules through poly(benzimidazoles)/nanoparticle oxides composites

    , Article International Journal of Hydrogen Energy ; Volume 43, Issue 5 , 2018 , Pages 2803-2816 ; 03603199 (ISSN) Khosravanian, A ; Dehghani, M ; Pazirofteh, M ; Asghari, M ; Mohammadi, A. H ; Shahsavari, D ; Sharif University of Technology
    Elsevier Ltd  2018
    Abstract
    Comprehensive structural/molecular simulations have been undertaken to study the poly(benzimidazoles) (PBI) membrane combined with four different nano-oxide materials (ZnO, Al2O3, SiO2 and TiO2) for purification and production of hydrogen from natural gases. Composite membranes were built with different amounts of nano-oxide materials to investigate the influence of nano-oxide content on the PBI membrane performance. Several structural characterizations such as FFV, WAXD and also a thermal one (glass transition temperature) were done to study the structural properties of all simulated membrane cells. Moreover, MSD and adsorption isotherms tasks were used to estimate the diffusivity and... 

    Rapid formation of hydroxyapatite nanostrips via microwave irradiation

    , Article Journal of Alloys and Compounds ; Volume 469, Issue 1-2 , 2009 , Pages 391-394 ; 09258388 (ISSN) Arami, H ; Mohajerani, M ; Mazloumi, M ; Khalifehzadeh, R ; Lak, A ; Sadrnezhaad, S. K ; Sharif University of Technology
    2009
    Abstract
    Hydroxyapatite (HAp) nanostrips were rapidly obtained during a mild microwave heating method. Applying microwave irradiation to Ca(NO3)2·4H2O/CTAB/Na2HPO4 precursor solution, the HAp precipitation process was occurred directly and without common crystallographic transformations including dissolution and slow recrystallization. The cationic surfactant CTAB was used as a soft template to modify nucleation and growth process. TEM investigations showed that the fabricated nanostrips had a width and length of about 10 and 55 nm, respectively. The X-ray diffraction pattern revealed that the fabricated well-crystallized and high purity hydroxyapatite nanostrips had a pattern similar to the bone... 

    SiO 2 -covered graphene oxide nanohybrids for in situ preparation of UHMWPE/GO(SiO 2 ) nanocomposites with superior mechanical and tribological properties

    , Article Journal of Applied Polymer Science ; Volume 136, Issue 31 , 2019 ; 00218995 (ISSN) Haddadi, S. A ; Saadatabadi, A. R ; Kheradmand, A ; Amini, M ; Ramezanzadeh, M ; Sharif University of Technology
    John Wiley and Sons Inc  2019
    Abstract
    The modified Hummer technique was used in the preparation of graphene oxide (GO) nanosheets, and then SiO 2 decorated GO [GO(SiO 2 )] nanosheets were synthesized via the sol–gel method. Then, ultrahigh-molecular-weight polyethylene (UHMWPE) nanocomposites loaded with 0.5, 1, 1.5, and 2 wt % of GO(SiO 2 ) were prepared using magnesium ethoxide/GO(SiO 2 )-supported Ziegler–Natta catalysts via the in situ polymerization. Morphological study of the prepared polymer powders was assessed using field-emission scanning electron microscopy, which showed that GO(SiO 2 ) nanohybrids have been uniformly dispersed and distributed into the UHMWPE matrix. Also, the neat UHMWPE and its nanocomposites were... 

    The effects of stabilizers on the thermal and the mechanical properties of rammed earth at various humidities and their environmental impacts

    , Article Construction and Building Materials ; Volume 200 , 2019 , Pages 616-629 ; 09500618 (ISSN) Toufigh, V ; Kianfar, E ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    The overall behavior of rammed earth (RE) as a low embodied energy construction method can be enhanced by using stabilizers. Several studies have been performed on cement and lime stabilized RE. However, studies on other additives, especially the sustainable ones, are limited. In this research, the effect of stabilizers including cement, pozzolan, microsilica, fiberglass, guar gum and phase change material (PCM) was evaluated on the performance of RE mixtures. The mixtures were assessed by considering the durability, shrinkage, thermal conductivity, mechanical properties and their sensitivity to the humidity. Then, the correlations were determined between the mechanical properties and the...