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    Room temperature catalytic aromatization of Hantzsch 1,4-dihydropyridines by sodium nitrite in the presence of acidic silica gel

    , Article Monatshefte fur Chemie ; Volume 137, Issue 2 , 2006 , Pages 197-200 ; 00269247 (ISSN) Hashemi, M. M ; Ghafuri, H ; Karimi Jaberi, Z ; Sharif University of Technology
    2006
    Abstract
    Various alkyl, aryl, and heterocyclic Hantzsch 1,4-dihydropyridines were converted to the corresponding pyridines in excellent yields and short times using sodium nitrite in the presence of a catalytic amount of acidic silica gel at room temperature. © Springer-Verlag 2006  

    Effect of silica nanoparticles on carbon dioxide separation performances of PVA/PEG cross-linked membranes

    , Article Chemical Papers ; Volume 75, Issue 7 , 2021 , Pages 3131-3153 ; 03666352 (ISSN) Rizwan Dilshad, M ; Islam, A ; Haider, B ; Sajid, M ; Ijaz, A ; Khan, R. U ; Khan, W. G ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2021
    Abstract
    Novel PVA/PEG cross-linked membranes were prepared with (0–20 wt. %) of silica nanoparticles. The presence of both the polymers and additive was confirmed by FTIR analysis. The thermal properties of the membranes were analyzed by TGA and DSC analysis. The morphological and mechanical properties of the membranes were studied by SEM analysis and tensile testing, respectively. The gas permeation performances of the membranes were examined using state-of-the-art gas permeability cell. It was found that permeability of all the gases increased with the increase of silica loading, whereas ideal selectivity of carbon dioxide with respect to nitrogen and methane increased up to 10 wt. % loading and... 

    Oxidation of benzylic methylene compounds to ketones with 4-aminoperoxybenzoic acid supported on silica gel in presence of oxygen or air

    , Article Monatshefte fur Chemie ; Volume 135, Issue 2 , 2004 , Pages 185-188 ; 00269247 (ISSN) Hashemi, M. M ; Ghazanfari, D ; Karimi Jaberi, Z ; Sharif University of Technology
    2004
    Abstract
    4-Aminoperoxybenzoic acid supported on silica gel in presence of oxygen or air was found to be a convenient and selective oxidant for the oxidation of benzylic methylene compounds to the corresponding ketones  

    Experimental evaluation of a solar-driven adsorption desalination system using solid adsorbent of silica gel and hydrogel

    , Article Environmental Science and Pollution Research ; Volume 29, Issue 47 , 2022 , Pages 71217-71231 ; 09441344 (ISSN) Zarei Saleh Abad, M ; Behshad Shafii, M ; Ebrahimpour, B ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2022
    Abstract
    Nowadays, the world is facing a shortage of fresh water. Utilizing adsorbent materials to adsorb air moisture is a suitable method for producing freshwater, especially combining the adsorption desalination system with solar energy devices such as solar collectors. The low temperature of solar collectors has caused some water to remain in the adsorbents in the desorption process and has reduced the possibility of using these systems. In this research, for the first time, an evacuated tube collector (ETC) is used as an adsorbent bed so that the temperature of the desorption process reaches higher values and as a result, more fresh water is expected to produced. In this study, two adsorption... 

    Comparison of hydrogen permeation and structural properties of a microporous silica membrane and a dense BaCe0.9Y0.1O3-δ (BCY) perovskite membrane

    , Article Results in Materials ; Volume 15 , 2022 ; 2590048X (ISSN) Amanipour, M ; Heidari, M ; Walberg, M ; Sharif University of Technology
    Elsevier B.V  2022
    Abstract
    Silica composite membranes and BaCe0.9Y0.1O3-δ (BCY) perovskite membranes were successfully synthesized to separate hydrogen in an equimolar mixture of H2, CH4, CO, and CO2 at temperature range of 500–900 °C and pressure difference of 1 bar. The phase structure of both membranes was characterized by X-ray diffraction (XRD). Thermogravimetric analysis (TGA) was used to evaluate phase stability of perovskite membrane. FESEM images confirmed graded structure of silica membrane and uniform, dense structure of perovskite membrane. H2 permeation in semi-dense silica layer deposited on alumina substrate indicated that permeation in top selective layer follows a diffusion mechanism which is based on... 

    Efficient and practical protocol for silylation of hydroxyl groups using reusable lithium perchlorate dispread in silica gel under neutral condition

    , Article Journal of Organometallic Chemistry ; Volume 691, Issue 5 , 2006 , Pages 817-820 ; 0022328X (ISSN) Azizi, N ; Yousefi, R ; Saidi, M. R ; Sharif University of Technology
    2006
    Abstract
    A very efficient and mild procedure for the trimethylsilylation of a wide variety of alcohols, including primary, allylic, benzylic, secondary, hindered secondary, tertiary, and phenols with hexamethyldisilazane on the surface of silica gel dispersed with LiClO4 in room temperature at few minutes in excellent yields under neutral conditions is reported. This procedure also allows the excellent selectivity under LP-SiO2 system for silylation of alcohols in the presence of amine and phenolic hydroxy groups. © 2005 Elsevier B.V. All rights reserved  

    Monitoring of microscopic behavior of nano-enhanced colloidal gas aphron in fractured and un-fractured non-uniform porous medium

    , Article Journal of Petroleum Science and Engineering ; Volume 210 , 2022 ; 09204105 (ISSN) Tabzar, A ; Ghazanfari, M. H ; Sharif University of Technology
    Elsevier B.V  2022
    Abstract
    The present article aimed to examine the pore-scale examination of a fluid capability to block pores and fractures deduced by return permeability and the blocking ability of a novel lightweight Colloidal Gas Aphron Nano-Fluid (CGANF) in heterogeneous fractured/un-fractured porous medium. Silica (S) and fumed silica (FS) nanoparticles, Sodium Dodecyl Sulfate (SDS) anionic surfactant, and Xanthan Gum (XG) bio-polymer were employed for following up CGANF bubbles' movements in incongruous micro-models’ inclusive crack. The transparent nature of the glass micro-model provides an intuition into the lenticular behavior of CGANF bubbles in the heterogeneous porous media. Differential pressure... 

    Investigation of the applicability of nano silica particles as a thickening additive for polymer solutions applied in EOR processes

    , Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Vol. 36, Issue. 12 , 2014 , Pages 1315-1324 ; ISSN: 15567036 Zeyghami, M ; Kharrat, R ; Ghazanfari, M. H ; Sharif University of Technology
    Abstract
    In past decades, many attempts have been made to use water-soluble polymers as a mobility control agent to improve sweep efficiency of enhanced oil recovery processes. However, sensitivity of the thickening behavior of these polymers to some harsh conditions, such as high salinity, has cast serious doubt on their applicability in reservoir conditions. By expansion of nanotechnology, scientists discovered that nanoparticles can be utilized as thickening and rheology control agents in many polymer solutions. In this study, hydrophilic fumed silica is added to hydrolyzed polyacrylamide and sulfonated polyacrylamide solutions. The effect of the addition of nano silica on the thickening and... 

    Investigating the rheological properties of nanofluids of water/hybrid nanostructure of spherical silica/MWCNT

    , Article Thermochimica Acta ; Volume 578 , 20 February , 2014 , Pages 53-58 ; ISSN: 00406031 Baghbanzadeh, M ; Rashidi, A ; Soleimanisalim, A. H ; Rashtchian, D ; Sharif University of Technology
    Abstract
    Regarding the importance of rheological properties of water based drilling fluids, the effects of silica nanospheres, multiwall carbon nanotubes (MWCNTs) and two types of their hybrid, i.e. H1 (80 wt.% silica nanosphere/20 wt.% MWCNT) and H2 (50 wt.% silica nanosphere/50 wt.% MWCNT) on the viscosity and density of distilled water were investigated. According to the results, viscosity and density of the nanofluids increased with the concentration, while they were reduced by increasing the temperature. At high concentrations, the least increase in the viscosity of distilled water by adding the nanomaterials is related to H2 (8.2% increase at 1.0 wt.%). Likewise, the optimum operating... 

    Effect of zircon content on chemical and mechanical behavior of silica-based ceramic cores

    , Article Ceramics International ; Vol. 40, issue. 1 PART A , January , 2014 , p. 1093-1098 Kazemi, A ; Faghihi-Sani, M. A ; Nayyeri, M. J ; Mohammadi, M ; Hajfathalian, M ; Sharif University of Technology
    Abstract
    In this work, the effect of zircon content on the mechanical and chemical behaviors of injection molded silica-based ceramic cores has been investigated. In order to simulate a casting process condition, the sintered samples at 1220 C were consequently heated up to 1430 C. Three point bending tests were carried out on all the prepared samples. The chemical resistance of the prepared cores was evaluated by leaching of samples in 43% KOH solution at its boiling point. Phase evolution and microstructure were investigated by XRD and SEM, respectively. Results showed that increasing zircon content led to an increase in MOR and decrease in leachability owing to the decrease in content of fused... 

    Investigation on cristobalite crystallization in silica-based ceramic cores for investment casting

    , Article Journal of the European Ceramic Society ; Volume 33, Issue 15-16 , 2013 , Pages 3397-3402 ; 09552219 (ISSN) Kazemi, A ; Faghihi Sani, M. A ; Alizadeh, H. R ; Sharif University of Technology
    2013
    Abstract
    In this work, cristobalite crystallization and its effects on mechanical and chemical behaviour of injection moulded silica-based ceramic cores were investigated. In order to simulate casting process condition, the sintered samples at 1220 °C were also heated up to 1430 °C. Flexural strength test was carried out on both sintered and heat treated samples. Chemical resistance of the cores was evaluated by leaching the samples inside 43. wt% KOH solution at its boiling point. Phase evolution and microstructure were investigated by thermal analyses (DTA and DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and optical microscopy (OM). Results showed that cristobalite was... 

    Adsorption isotherms and ideal selectivities of hydrogen sulfide and carbon dioxide over methane for the Si-CHA zeolite: Comparison of carbon dioxide and methane adsorption with the all-silica DD3R zeolite

    , Article Adsorption ; Volume 19, Issue 5 , 2013 , Pages 1045-1053 ; 09295607 (ISSN) Maghsoudi, H ; Soltanieh, M ; Bozorgzadeh, H ; Mohamadalizadeh, A ; Sharif University of Technology
    2013
    Abstract
    Adsorption isotherms of H2S, CO2, and CH4 on the Si-CHA zeolite were measured over pressure range of 0-190 kPa and temperatures of 298, 323, and 348 K. Acid gases adsorption isotherms on this type of zeolite are reported for the first time. The isotherms follow a typical Type-I shape according to the Brunauer classification. Both Langmuir and Toth isotherms describe well the adsorption isotherms of methane and acid gases over the experimental conditions tested. At room temperature and pressure of 100 kPa, the amount of CO2 adsorption for Si-CHA zeolite is 29 % greater than that reported elsewhere (van den Bergh et al. J Mem Sci 316:35-45 (2008); Surf Sci Catal 170:1021-1027 (2007)) for the... 

    Silica-supported DABCO-tribromide: A recoverable reagent for oxidation of alcohols to the corresponding carbonyl compounds

    , Article Scientia Iranica ; Volume 20, Issue 3 , 2013 , Pages 598-602 ; 10263098 (ISSN) Moghaddam, F. M ; Masoud, N ; Foroushani, B. K ; Saryazdi, S ; Ghonouei, N ; Daemi, E ; Sharif University of Technology
    2013
    Abstract
    In this study, 1,4-diazabicy lo[2.2.2] octane (DABCO) tribromide was immobilized on silica support by using 3-chloro propyl trimethoxy silane to obtain a silica-supported DABCO tribromide reagent. The synthesized reagent was characterized with elemental analysis, FT-IR spectroscopy, and thermo-gravimetric analysis (TGA). This reagent has been applied in the conversion of alcohol to corresponding carbonyl compounds. Alcohol oxidation reactions yield in 52-95%, and the reagent may be recycled five times with further bromine treatment  

    PEG-co-polyvinyl pyridine coated magnetic mesoporous silica nanoparticles for pH-responsive controlled release of doxorubicin

    , Article International Journal of Polymeric Materials and Polymeric Biomaterials ; Volume 64, Issue 11 , 2015 , Pages 570-577 ; 00914037 (ISSN) Pourjavadi, A ; Mazaheri Tehrani, Z ; Bennett, C ; Sharif University of Technology
    Taylor and Francis Inc  2015
    Abstract
    In the present work a pH responsive drug nanocarrier based on magnetic mesoporous silica nanoparticles (MMSN) and polyethylene glycol-co-polyvinyl pyridine (PEG-co-PVP) was prepared. The core-shell nanocarrier was formed due to electrostatic interaction between protonated polyvinyl pyridine and surface modified MMSN with carboxylate groups. This carrier was used for pH-controllable doxorubicin release. The maximum release was occurred at pH 5.5 (pH of endosomes). This carrier was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, UV-Vis spectrophotometer, scanning electron microscope, and high-resolution transmission electron microscope techniques. Also the... 

    A note on the synergistic effect of surfactants and nanoparticles on rising bubble hydrodynamics

    , Article Chemical Engineering and Processing - Process Intensification ; Volume 155 , 2020 Fayzi, P ; Bastani, D ; Lotfi, M ; Sharif University of Technology
    Elsevier B.V  2020
    Abstract
    Various mixtures of surfactants and nanosilica particles were investigated to assess their influence on rising bubble hydrodynamics. For this purpose, local velocities of rising bubbles were measured experimentally. Also, the effects of concentration of three types of surface-modified silica nanoparticles on density, viscosity, and surface tension of surfactant solutions were determined. Experimental results revealed that the simultaneous presence of nanoparticles and surfactant molecules led to the decrease of local velocities of rising bubbles. The presence of nanoparticles in surfactant solutions leads to a more reduction of bubble local velocity. This could be caused by the formation of... 

    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 Ghaleh, V.R ; 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... 

    https://www.sciencedirect.com/science/article/abs/pii/S0032386122006103

    , Article Polymer ; Volume 255 , 2022 ; 00323861 (ISSN) Mohammadi, A ; Shojaei, A ; Salkhi Khasraghi, S ; Karimzad Ghavidel, A ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    Present work illustrated that the performance of ultrafine silica (Si) particles was improved considerably by rational hybridization with nanodiamond (ND). For this, Si@ND hybrid particles synthesized by chemical hybridization were incorporated into styrene-butadiene rubber (SBR) up to 10 phr. Scanning electron microscopy revealed coarse flower-like clusters for Si@ND nanohybrids, while Si exhibited rigid agglomerates in SBR. Comparing with physical hybrid (Si&ND) and single Si particles, it was revealed that chemical hybrids synergistically improved tensile properties, like 100% and 135% improvements in tensile strength and elongation at break, respectively. Dynamic mechanical analysis of... 

    Processing and Characterization of Fracture Behavior of Hybrid Epoxy Nanocomposite Modified with Polycarbonate

    , M.Sc. Thesis Sharif University of Technology Amini NajafAbadi, Leila (Author) ; Bagheri, Reza (Supervisor)
    Abstract
    Epoxy resins have good mechanical and thermal properties, high chemical resistance and low shrinkage during cure but in spite of these good properties,they are brittle and this limits the usage of them. Adding a second, soft or rigid, phase has been always an effective strategy to improve the toughness of epoxy. Rigid phase used in resins are divided into organic and inorganic. The aim of this study is to increase epoxy toughness, maintaining mechanical properties and study effect of silica and polycarbonate on fracture toughness simultaneously. Mechanical properties including yield strength and elastic modulus are evaluated by pressure test. Additionally fracture toughness and three... 

    3D Stem Cell Culture and Differentiation Using Alginate Hydrogel Scaffolds Incorporated with Silicon-Based Nanoparticles

    , Ph.D. Dissertation Sharif University of Technology Hassani, Masoud (Author) ; Yaghmaei, Soheila (Supervisor) ; Arpanaei, Ayyoob (Co-Supervisor) ; Dolatshahi Pirouz, Alireza (Co-Supervisor)
    Abstract
    Bone is one of the most vital parts of the body for almost any functional movement. Due to its many involved diseases, traumas and injuries, bone maintenance and regeneration are of high importance. Engineering and design of complex tissues, with impeccable mimicry of the native ones, are always accounted as the solution to dysfunction of body organs due to aging, various diseases, etc. However, the inability to complete mimicry of the native tissue architecture and cell microenvironment are the main barriers to functional tissue regeneration. In this project, in order to design a suitable scaffold for bone regeneration, hydrogel nanocomposites with polysaccharide basis were developed by... 

    Febrication of Superhydrophobic Nanocomposites Containing Modified Silica Nanoparticles and Silicone Polymers and Evaluation of Their Application

    , M.Sc. Thesis Sharif University of Technology Samaili, Hamed (Author) ; Pourjavadi, Ali (Supervisor) ; Alamolhoda, Ali Asghar (Supervisor)
    Abstract
    Rehabilitation usually involves physical therapy, occupational therapy and counseling for the patient's morale to help to restore his power and performance. Considering the economic outlook and the costs of rehabilitation methods and due to the increasing prevalence of stroke and the need to recover the patients in a short period, only the use of robotic systems opens the door to the medical community. Since a large rehabilitation robots designed and built and each been used according to their advantages and shortcomings. In this project, the major shortcomings examined and exoskeleton designed on two major features including portability and covering shoulder workspace. Shoulder movement was...