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    Properly-tuned continuum and atomistic models for vibrational analysis of the silicon nanoplates

    , Article International Journal of Mechanical Sciences ; Volume 229 , 2022 ; 00207403 (ISSN) Azadbakht, J ; Nejat Pishkenari, H ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    The high computational costs of atomistic simulations for the investigation of nanostructures, despite their accuracy, necessitate efforts to develop efficient continuum models. Since the classical continuum mechanics assume the matter as continuous and ignore the size dependency of material properties, these theories fail to capture the behavior of materials at the nanoscale. Size-dependencies of nanostructures could result in the emergence of surface effects. This paper, for the first time, aims to develop and tune surface-enhanced continuum models to predict the vibrational properties of nanoplates which are inherently discrete at the nanoscale. Regarding this aim, we use a composite... 

    Design guidelines for a tunable SOI based optical isolator in a partially time-modulated ring resonator

    , Article IEEE Photonics Journal ; Volume 14, Issue 5 , 2022 ; 19430655 (ISSN) Zarif, A ; Mehrany, K ; Memarian, M ; Jamshidi, K ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2022
    Abstract
    In this paper, we present the design guidelines for a tunable optical isolator in an SOI-based ring resonator with two small time-modulated regions. By considering a physical model, the proper geometrical and modulation parameters are designed, based on a standard CMOS foundry process. The effect of the variation of the key parameters on the performance of the isolator is explained by two counter-acting mechanisms, namely the separation between the resonance frequencies of counter-rotating modes and energy transfer to the side harmonic. We show that there is a trade-off between these parameters to obtain maximum isolation. Consequently, by applying the quadrature phase difference one can... 

    Friction reduction of Al2O3, SiO2, and TiO2 nanoparticles added to non-Newtonian water based mud in a rotating medium

    , Article Journal of Petroleum Science and Engineering ; Volume 217 , 2022 ; 09204105 (ISSN) Misbah, B ; Sedaghat, A ; Rashidi, M ; Sabati, M ; Vaidyan, K ; Ali, N ; Omar, M. A. A ; Hosseini Dehshiri, S. S ; Sharif University of Technology
    Elsevier B.V  2022
    Abstract
    In drilling industry, energy consumption counts from 20 to 40 percent of total costs. Enhanced water-based mud (WBM) drilling fluids with nanoparticles can save energy in drilling processes. An in-house Taylor-Couette flow system (TCS) was developed at Australian University (AU) to study WBM enhanced by Al2O3, SiO2, and TiO2 nanoparticles. The TCS is really a practical tool to help well drillers with a rough idea of viscosity when nanoparticles are added. The TCS for sure cannot substitute advanced rheometry. The goal of the present experiment is to produce a rough estimate in field operation. Experimental results were examined with several rheology models in our previous publications. In... 

    Plasma-enhanced chemical vapor deposition for fabrication of yolk-shell SnO2@Void@C nanowires, as an efficient carbon coating technique for improving lithium-ion battery performance

    , Article Materials Science in Semiconductor Processing ; Volume 149 , 2022 ; 13698001 (ISSN) Habibi, A ; Mousavi, M. R ; Yasoubi, M ; Sanaee, Z ; Ghasemi, S ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    This manuscript describes the implementation of plasma-enhanced chemical vapor deposition (DC-PECVD) and vapor-liquid-solid (VLS) techniques to fabricate a yolk-shell SnO2@Void@C nanowire (NW) structure. SnO2 nanowires have been synthesized on the stainless steel mesh substrate through the VLS method. The PECVD-assisted growth of carbon nanolayer on the SnO2 and SiO2 coated SnO2 NWs has been performed to fabricate SnO2@C core-shell and SnO2@SiO2@C yolk-shell structures, respectively. A consequent silica etching process converted the SnO2@SiO2@C into SnO2@Void@C structure. The electrochemical performance of bare SnO2 NWs, SnO2 NWs @ C, and SnO2 @Void @ C coaxial NWs structures have been... 

    Effects of heat treatment and Y addition on the microstructure and mechanical properties of as-cast Mg–Si alloys

    , Article Materials Science and Engineering A ; Volume 859 , 2022 ; 09215093 (ISSN) Jamalpour, M ; Alizadeh, R ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    In Mg–Si alloys, both primary and eutectic Mg2Si particles normally appear with sharp edges, which can lead to weak mechanical properties as the result of stress concentration at the sharp corners of these brittle particles. Thus, it would be of great importance to modify the morphology of these particles. In this study, microstructure modification mechanisms after 0.5 wt% Y addition and heat treatment (HT) at 420 °C for 24 h are comprehensively studied in hypo-eutectic Mg–1Si and hyper-eutectic Mg–2Si alloys. Microstructural observations were performed using optical and scanning electron microscopy equipped with electron disperse spectroscopy, while phase analysis was done by X-ray... 

    Self-Powered humidity sensors based on sns2nanosheets

    , Article ACS Applied Nano Materials ; Volume 5, Issue 11 , 2022 , Pages 17123-17132 ; 25740970 (ISSN) Shooshtari, L ; Rafiefard, N ; Barzegar, M ; Fardindoost, S ; Irajizad, A ; Mohammadpour, R ; Sharif University of Technology
    American Chemical Society  2022
    Abstract
    With the advent of the Internet of Things (IoT), the development of self-powered sensors has received much attention. Introducing triboelectric nanogenerators (TENGs) as a power source that converts mechanical movement into electrical signals has been admired recently. Moreover, the monitoring of humidity has become enormously essential in several technological contexts from environment monitoring to biomedical applications, thus joining these two subjects provides a huge benefit in achieving self-powered humidity sensors. Here, in this research, facile, low-priced and self-powered humidity sensors are fabricated utilizing transition-metal dichalcogenides (TMD) nanosheets. Semi-vertical SnS2... 

    Design and fabrication of a micro-opto-mechanical-systems accelerometer based on intensity modulation of light fabricated by a modified deep-reactive-ion-etching process using silicon-on-insulator wafer

    , Article Journal of Vacuum Science and Technology B ; Volume 40, Issue 4 , 2022 ; 21662746 (ISSN) Gholamzadeh, R ; Gharooni, M ; Salarieh, H ; Akbari, J ; Sharif University of Technology
    AVS Science and Technology Society  2022
    Abstract
    Accelerometers that work based on intensity modulation of light are more sensitive, economically feasible, and have a simpler fabrication process compared to wavelength modulation. A micro-opto-electro-mechanical-system accelerometer based on intensity modulation of light is designed and fabricated. A movable shutter that is attached to the proof mass is designed to change the intensity of light. Moreover, the mechanical part is designed to improve the overall sensitivity and linear behavior in the measurement range. The designed accelerometer is fabricated by a deep-reactive-ion-etching (DRIE) process. The DRIE process used in this report is based on a Bosch-like process, which uses SF 6... 

    Selective fabrication of robust and multifunctional super nonwetting surfaces by diverse modifications of zirconia-ceria nanocomposites

    , Article Langmuir ; Volume 38, Issue 30 , 2022 , Pages 9195-9209 ; 07437463 (ISSN) Esmaeilzadeh, P ; Zandi, A ; Ghazanfari, M. H ; Khezrnejad, A ; Fatemi, M ; Molaei Dehkordi, A ; Sharif University of Technology
    American Chemical Society  2022
    Abstract
    The creation of surfaces with various super nonwetting properties is an ongoing challenge. We report diverse modifications of novel synthesized zirconia-ceria nanocomposites by different low surface energy agents to fabricate nanofluids capable of regulating surface wettability of mineral substrates to achieve selective superhydrophobic, superoleophobic-superhydrophilic, and superamphiphobic conditions. Surfaces treated with these nanofluids offer self-cleaning properties and effortless rolling-off behavior with sliding angles ≤7° for several liquids with surface tensions between 26 and 72.1 mN/m. The superamphiphobic nanofluid coating imparts nonstick properties to a solid surface whereby... 

    Syngas production through CO2 reforming of propane over highly active and stable mesoporous NiO-MgO-SiO2 catalysts: Effect of calcination temperature

    , Article Fuel ; Volume 322 , 2022 ; 00162361 (ISSN) Barzegari, F ; Kazemeini, M ; Rezaei, M ; Farhadi, F ; Keshavarz, A. R ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    In this contribution, NiO-MgO-SiO2 catalyst was prepared and calcined at different temperatures of 500, 600, 700 and 800 °C. The resulting samples were characterized by BET-BJH, XRD, TPX, CO-chemisorption, EDS and SEM analyses. These were employed toward syngas production via propane dry reforming. The increment in the calcination temperature from 500 to 800 °C decreased the basicity of the catalysts. In addition, the active surface area and Ni dispersion were gradually declined by increasing the calcination temperature from 600 to 700 °C due to active metal sintering during the activation process. The calcined sample at 600 °C displayed the highest propane and CO2 conversions of 93% and 78%... 

    Microstructural characterization and enhanced tensile and tribological properties of Cu-SiC nanocomposites developed by high-pressure torsion

    , Article Journal of Materials Research and Technology ; Volume 20 , 2022 , Pages 4038-4051 ; 22387854 (ISSN) Akbarpour, M. R ; Gharibi Asl, F ; Mousa Mirabad, H ; Kim, H. S ; Sharif University of Technology
    Elsevier Editora Ltda  2022
    Abstract
    In this study, an attempt has been made to fabricate Cu-SiC nanocomposites by flake powder metallurgy and high-pressure torsion processing techniques at room temperature. Pure Cu and a mixture of Cu and nano-sized SiC powders were mechanically milled separately for 3 h and then green compacts were prepared by uniaxial pressing under 1 GPa pressure. The green compacts experienced 6-turn high-pressure torsion under a pressure of 6 GPa to prepare bulk Cu and Cu-SiC samples. The microstructures of the consolidated samples were characterized using an X-ray diffractometer and a high resolution scanning/transmission electron microscope, and the mechanical properties were evaluated by microhardness,... 

    Enhanced singlet oxygen production under nanoconfinement using silica nanocomposites towards improving the photooxygenation’s conversion

    , Article Journal of Nanoparticle Research ; Volume 24, Issue 9 , 2022 ; 13880764 (ISSN) Tamtaji, M ; Kazemeini, M ; Sharif University of Technology
    Springer Science and Business Media B.V  2022
    Abstract
    In this contribution, the effect of physical immobilization of methylene blue (MB) into silica nanocomposites was investigated on the conversion and selectivity of the photooxygenation of anthracene and dihydroartemisinic acid (DHAA). Physically immobilized photocatalysts were synthesized through a developed Stöber method and were thoroughly characterized by UV–Vis, FTIR, XRD, XPS, SEM, TEM, HR-TEM, BET-BJH, and EDX analyses. Based on the TEM and UV–Vis results, it was determined that enhancement of the MB concentration as an organocatalyst for the Stöber reaction led to an increase in the size of the nanoparticles from 54 to 183 nm and a 21 nm blue shift in their UV–Vis spectra. Moreover,... 

    Gold nanorods for drug and gene delivery: An overview of recent advancements

    , Article Pharmaceutics ; Volume 14, Issue 3 , 2022 ; 19994923 (ISSN) Jahangiri Manesh, A ; Mousazadeh, M ; Taji, S ; Bahmani, A ; Zarepour, A ; Zarrabi, A ; Sharifi, E ; Azimzadeh, M ; Sharif University of Technology
    MDPI  2022
    Abstract
    Over the past few decades, gold nanomaterials have shown great promise in the field of nanotechnology, especially in medical and biological applications. They have become the most used nanomaterials in those fields due to their several advantageous. However, rod-shaped gold nanoparticles, or gold nanorods (GNRs), have some more unique physical, optical, and chemical properties, making them proper candidates for biomedical applications including drug/gene delivery, photothermal/photodynamic therapy, and theranostics. Most of their therapeutic applications are based on their ability for tunable heat generation upon exposure to near-infrared (NIR) radiation, which is helpful in both... 

    Hyperbranched polyethylenimine functionalized silica/polysulfone nanocomposite membranes for water purification

    , Article Chemosphere ; Volume 290 , 2022 ; 00456535 (ISSN) Vatanpour, V ; Jouyandeh, M ; Akhi, H ; Mousavi Khadem, S. S ; Ganjali, M. R ; Moradi, H ; Mirsadeghi, S ; Badiei, A ; Esmaeili, A ; Rabiee, N ; Habibzadeh, S ; Koyuncu, I ; Nouranian, S ; Formela, K ; Saeb, M. R ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    Hyperbranched polyethyleneimine functionalized silica (PEI-SiO2) nanoparticles with considerable hydrophilicity were synthesized and incorporated into a polysulfone (PSF)/dimethylacetamide (DMA)/polyvinylpyrrolidone (PVP) membrane casting solution in five different ratios to fabricate PEI-SiO2/PSF nanocomposite membranes using nonsolvent-induced phase separation. The hydrophilic PEI-SiO2 nanoparticles were characterized by TEM, FTIR, TGA, and XPS analyses. Morphology, water contact angles, mean pore sizes, overall porosity, tensile strengths, water flux, antifouling and the dye separation performances of the PEI-SiO2/PSF membranes were also studied. The PEI-SiO2 nanoparticles were uniformly... 

    Highly antifouling polymer-nanoparticle-nanoparticle/polymer hybrid membranes

    , Article Science of the Total Environment ; Volume 810 , 2022 ; 00489697 (ISSN) Vatanpour, V ; Jouyandeh, M ; Mousavi Khadem, S. S ; Paziresh, S ; Dehghan, A ; Ganjali, M. R ; Moradi, H ; Mirsadeghi, S ; Badiei, A ; Munir, M. T ; Mohaddespour, A ; Rabiee, N ; Habibzadeh, S ; Mashhadzadeh, A. H ; Nouranian, S ; Formela, K ; Saeb, M. R ; Sharif University of Technology
    Elsevier B.V  2022
    Abstract
    We introduce highly antifouling Polymer-Nanoparticle-Nanoparticle/Polymer (PNNP) hybrid membranes as multi-functional materials for versatile purification of wastewater. Nitrogen-rich polyethylenimine (PEI)-functionalized halloysite nanotube (HNT-SiO2-PEI) nanoparticles were developed and embedded in polyvinyl chloride (PVC) membranes for protein and dye filtration. Bulk and surface characteristics of the resulting HNT-SiO2-PEI nanocomposites were determined using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). Moreover, microstructure and... 

    Investigation into the effect of substrate material on microstructure and optical properties of thin films deposited via magnetron sputtering technique

    , Article Ceramics International ; Volume 48, Issue 5 , 2022 , Pages 6277-6286 ; 02728842 (ISSN) Mashaiekhy Asl, J ; Nemati, A ; Hadi, I ; Mirdamadi, S ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    This study aims at investigating the effect of the substrate material on growth mechanism and also microstructure of Ta2O5 thin films. For this purpose, atomic force microscopy, scanning electron microscopy, and interferometry analyses were implemented to reveal the influence of silicon wafer and amorphous BK7 glass substrates on the nucleation and growth mechanisms of Ta2O5 thin films deposited via the radio frequency magnetron sputtering technique. Results indicated that those films with finer morphologies had relatively higher nucleation densities. Compared with BK7 glass substrate, crystals formed on the silicon wafer were shown to be finer and had lower mean areas in more nucleation... 

    Synthesis mechanism and microstructure characterization of ZrB2–ZrC–SiC nanocomposite synthesized via magnesium boro/carbothermal reduction at low temperatures

    , Article Materials Chemistry and Physics ; Volume 280 , 2022 ; 02540584 (ISSN) Jafari, S ; Bavand Vandchali, M ; Mashhadi, M ; Nemati, A ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    In this study, magnesium boro/carbothermal reduction of zirconium silicate (ZrSiO4) was employed to synthesize zirconium-based composite nanopowders of ZrB2–SiC, ZrB2–ZrC–SiC, ZrC–SiC, and ZrC. For this aim, three different temperatures of 1200 °C, 1300 °C, and 1450 °C were selected as the supposed temperatures for synthesis. Elemental Mg and NaCl were also selected to assist reduction process. In addition, effects of different C/Zr ratios as well as using elemental boron and B4C as two different boron sources were investigated on the final produced phases. Subsequently, XRD and SEM/EDS analyses were carried out to elaborate microstructure and phase studies. Finally, STA carried out up to... 

    Multifunctional tetracycline-loaded silica-coated core-shell magnetic nanoparticles: antibacterial, antibiofilm, and cytotoxic activities

    , Article ACS Applied Bio Materials ; Volume 5, Issue 4 , 2022 , Pages 1731-1743 ; 25766422 (ISSN) Mazraeh, M ; Eshrati Yeganeh, F ; Yousefi, M ; Baniyaghoob, S ; Farasati Far, B ; Akbarzadeh, I ; Bigham, A ; Ashrafizadeh, M ; Rabiee, N ; Makvandi, P ; Saeb, M. R ; Sharif University of Technology
    American Chemical Society  2022
    Abstract
    In the current study, the physicochemical and biological properties of tetracycline-loaded core-shell nanoparticles (Tet/Ni0.5Co0.5Fe2O4/SiO2 and Tet/CoFe2O4/SiO2) were investigated. The antibacterial activity of nanoparticles alone and in combination with tetracycline was investigated against a number of Gram-positive and Gram-negative bacteria for determining minimum inhibitory concentration (MIC) values. The MIC of Tet/Ni0.5Co0.5Fe2O4/SiO2 nanoparticles turned out to be significantly higher than that of Tet/CoFe2O4/SiO2 nanoparticles. Furthermore, Tet/Ni0.5Co0.5Fe2O4/SiO2 nanoparticles exhibited potent antibiofilm activity against pathogenic bacteria compared to Tet/CoFe2O4/SiO2... 

    Partly semiconductor covered vane fast magnetron

    , Article IEEE Transactions on Plasma Science ; Volume 50, Issue 5 , 2022 , Pages 1179-1187 ; 00933813 (ISSN) Hashemi, S. M. A ; Hashemi, S. M. A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2022
    Abstract
    Alterations in the structure of a magnetron, e.g., the A6 relativistic magnetron, are proposed, which considerably increase the device's build-up speed. We cover the magnetron vane surfaces with semiconductor layers of nonzero electric conductivity, with an exact geometrical design. Semiconductor layers with considerable mechanical strength also provide excellent shielding for the vanes against the high-energy relativistic electrons' bombardment. The novel structure introduces several new free parameters to the magnetron design procedure and considerably increases the design flexibility. A multistage exact optimization procedure, performed by extensive computer simulations, shows that... 

    Ultra-compact all-optical reversible Feynman gate based on suspended graphene plasmonic waveguides

    , Article Optical and Quantum Electronics ; Volume 54, Issue 5 , 2022 ; 03068919 (ISSN) Safinezhad, A ; Eslami, M. R ; Jafari Jozani, K ; Rezaei, M. H ; Sharif University of Technology
    Springer  2022
    Abstract
    In this paper, we propose a reversible Feynman gate utilizing the interference effect for optical communications and computing. The plasmonic waveguides are created by placing a suspended graphene sheet, held by two SiO2 ridges, 10 nm above the Si ribs. The Finite-difference time-domain (FDTD) method is used to simulate the proposed gate in frequency and time domains. Simulation results show that high extinction ratios as much as (15.12 dB) and 13 dB are achievable at the wavelength of 10 μm for the output bits P and Q, respectively. The device is immune against ± 20% variations in the width of the Si ribs due to fabrication errors and its performance can be controlled by setting the... 

    Effect of mechanical nonlinearity on the electromagnetic response of a microwave tunable metamaterial

    , Article Journal of Physics D: Applied Physics ; Volume 55, Issue 20 , 2022 ; 00223727 (ISSN) Karimi Mahabadi, R ; Goudarzi, T ; Fleury, R ; Orazbayev, B ; Naghdabadi, R ; Sharif University of Technology
    IOP Publishing Ltd  2022
    Abstract
    Tunable metamaterials functionalities change in response to external stimuli. Mechanical deformation is known to be an efficient approach to tune the electromagnetic response of a deformable metamaterial. However, in the case of large mechanical deformations, which are usually required to fully exploit the potential of the tunable metamaterials, the linear elastic mechanical analysis is no longer suitable. Nevertheless, nonlinear mechanical analysis is missing in the studies of mechanically tunable metamaterials. In this paper, we study the importance of considering nonlinearity in mechanical behavior when analyzing the response of a deformable metamaterial and its effects on electromagnetic...