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    Inter-symbol-interference reduction in indoor infrared systems by effective sampling

    , Article Proceedings - 2009 International Conference on Future Computer and Communication, ICFCC 2009, 3 April 2009 through 5 April 2009, Kuala Lumpar ; 2009 , Pages 42-46 ; 9780769535913 (ISBN) Hassanzadeh, M. R ; Mansouri Rad, M. M ; Sharif University of Technology
    A new and simple receiver structure for reducing the multipath inter-symbole interference (ISI) effect is proposed for infrared diffuse links. In this new method, bit-error rate (BER) performance of the system will be improved significantly without any essential change in the receiver structure. In our analysis, all major noise sources such as ambient light, signal shotnoise, dark current and thermal noise of the receiver are considered. © 2009 IEEE  

    Designing dual-band absorbers by graphene/metallic metasurfaces

    , Article IEEE Journal of Quantum Electronics ; Volume 55, Issue 2 , 2019 ; 00189197 (ISSN) Barzegar Parizi, S ; Khavasi, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    This paper presents a novel approach for designing dual-band absorbers based on graphene and metallic metasurfaces for terahertz and mid-infrared regimes, respectively. The absorbers are composed of a 2D array of square patches deposited on a dielectric film terminated by a metal plate. Using an analytical circuit model, we obtain closed-form relations for different parameters of the structure to achieve the dual-band absorber. Two absorption bands with an obtained absorptivity of 98% at 0.53 and 1.53 THz for the graphene-based structure and 7 and 25 THz for the metallic-based case are achieved. We demonstrate that the graphene-based absorber remains as the dual band for a wide range of the... 

    Zinc ferrite spinel-graphene in magneto-photothermal therapy of cancer

    , Article Journal of Materials Chemistry B ; Vol. 2, Issue. 21 , 2014 , p. 3306-3314 Akhavan, O ; Meidanchi, A ; Ghaderi, E ; Khoei, S ; Sharif University of Technology
    A magneto-photothermal therapy for cancer (in vitro photothermal therapy of prostate cancer cells and in vivo photothermal therapy of human glioblastoma tumors in the presence of an external magnetic field) was developed using superparamagnetic zinc ferrite spinel (ZnFe2O4)-reduced graphene oxide (rGO) nanostructures (with various graphene contents). In vitro application of a low concentration (10 μg mL-1) of the ZnFe 2O4-rGO (20 wt%) nanostructures under a short time period (∼1 min) of near-infrared (NIR) irradiation (with a laser power of 7.5 W cm-2) resulted in an excellent destruction of the prostate cancer cells, in the presence of a magnetic field (∼1 Tesla) used for localizing the... 

    Theoretical calculation of scattering efficiency of isotropic and anisotropic scattering particles employed in nanostructured solar cells

    , Article Journal of Optics (United Kingdom) ; Vol. 16, issue. 5 , 2014 ; ISSN: 20408978 Sasanpour, P ; Mohammadpour, R ; Sharif University of Technology
    Light scattering design in dye and quantum dot sensitized solar cells is one of the main concerns in enhancing their light harvesting efficiency, and also in improving their power conversion efficiency. Herein, we present a theoretical analysis to calculate the dependence of the light scattering efficiency in dye solar cells that have employed scattering agents with various sizes and morphologies incorporated in nanostructured photoanodes with different designs. Various isotropic and anisotropic nanostructures, including filled and hollow spheres, spherical voids, nanowires and hollow fibres in a size range of 100 nm to 900 nm, have been considered as scattering centres. The scattering... 

    Wrapping bacteria by graphene nanosheets for isolation from environment, reactivation by sonication, and inactivation by near-infrared irradiation

    , Article Journal of Physical Chemistry B ; Volume 115, Issue 19 , 2011 , Pages 6279-6288 ; 15206106 (ISSN) Akhavan, O ; Ghaderi, E ; Esfandiar, A ; Sharif University of Technology
    American Chemical Society  2011
    Bioactivity of Escherichia coli bacteria (as a simple model for microorganisms) and interaction of them with the environment were controlled by their capturing within aggregated graphene nanosheets. The oxygen-containing functional groups of chemically exfoliated single-layer graphene oxide nanosheets were reduced by melatonin as a biocompatible antioxidant. While each one of the graphene (oxide) suspension and melatonin solution did not separately show any considerable inactivation effects on the bacteria, aggregation of the sheets in the melatonin-bacterial suspension resulted in trapping the bacteria within the aggregated sheets, i.e., a kind of inactivation. The bacteria trapped within... 

    Design of mid-infrared ultra-wideband metallic absorber based on circuit theory

    , Article Optics Communications ; Volume 381 , 2016 , Pages 309-313 ; 00304018 (ISSN) Arik, K ; Abdollahramezani, S ; Farajollahi, S ; Khavasi, A ; Rejaei, B ; Sharif University of Technology
    Elsevier B.V  2016
    An ultra-broadband absorber of light is proposed by using periodic array of ultra-thin metallic ribbons on top of a lossless quarter-wavelength dielectric spacer placed on a metallic reflector. We propose a fully analytical circuit model for the structure, and then the absorber is duly designed based on the impedance matching concept. As a result, normalized bandwidth of 99.5% is realized by the proposed absorbing structure in mid-infrared regime. Performing a numerical optimization algorithm, we could also reach to normalized bandwidth of 103%  

    Graphene scaffolds in progressive nanotechnology/stem cell-based tissue engineering of the nervous system

    , Article Journal of Materials Chemistry B ; Volume 4, Issue 19 , 2016 , Pages 3169-3190 ; 20507518 (ISSN) Akhavan, O ; Sharif University of Technology
    Royal Society of Chemistry  2016
    Although graphene/stem cell-based tissue engineering has recently emerged and has promisingly and progressively been utilized for developing one of the most effective regenerative nanomedicines, it suffers from low differentiation efficiency, low hybridization after transplantation and lack of appropriate scaffolds required in implantations without any degrading in functionality of the cells. In fact, recent studies have demonstrated that the unique properties of graphene can successfully resolve all of these challenges. Among various stem cells, neural stem cells (NSCs) and their neural differentiation on graphene have attracted a lot of interest, because graphene-based neuronal tissue... 

    Site-specific protein conjugation onto fluorescent single-walled carbon nanotubes

    , Article Chemistry of Materials ; Volume 32, Issue 20 , 2020 , Pages 8798-8807 Zubkovs, V ; Wu, S. J ; Rahnamaee, S. Y ; Schuergers, N ; Boghossian, A. A ; Sharif University of Technology
    American Chemical Society  2020
    Semiconducting single-walled carbon nanotubes (SWCNTs) are among the few photostable optical emitters that are ideal for sensing, imaging, drug delivery, and monitoring of protein activity. These applications often require strategies for immobilizing proteins onto the nanotube while preserving the optical properties of the SWCNTs. Site-specific and oriented immobilization strategies, in particular, offer advantages for improving sensor and optical signaling responses. In this study, we demonstrate site-specific protein immobilization of a model of enhanced yellow fluorescent protein with a single engineered cysteine residue, using either single-stranded DNA or a pyrene-containing linker to... 

    ZrN fractal-graphene-based metamaterial absorber in the visible and near-IR regimes

    , Article Optik ; Volume 237 , 2021 ; 00304026 (ISSN) Baqir, M. A ; Choudhury, P. K ; Niaz Akhtar, M ; Sharif University of Technology
    Elsevier GmbH  2021
    The absorption characteristics of zirconium nitride (ZrN)-based metamaterial absorber of fractal geometry are studied. The proposed absorber is comprised of fractal metasurface at the top having subwavelength-sized periodic pattern of specially designed ZrN circular nano-discs arranged over silicon dioxide (SiO2) substrate. A tri-layer graphene, owing to its exhibiting better tunability, is introduced at the interface of metasurface and substrate. The bottom side of SiO2 is coated with silver nanolayer to block transmission. The absorptivity essentially depends on the kind of fractal design used in metasurface to configure the absorber. The obtained results exhibit the absorption... 

    Graphene nanomesh promises extremely efficient in vivo photothermal therapy

    , Article Small ; Volume 9, Issue 21 , 2013 , Pages 3593-3601 ; 16136810 (ISSN) Akhavan, O ; Ghaderi, E ; Sharif University of Technology
    Reduced graphene oxide nanomesh (rGONM), as one of the recent structures of graphene with a surprisingly strong near-infrared (NIR) absorption, is used for achieving ultraefficient photothermal therapy. First, by using TiO2 nanoparticles, graphene oxide nanoplatelets (GONPs) are transformed into GONMs through photocatalytic degradation. Then rGONMs functionalized by polyethylene glycol (PEG), arginine-glycine-aspartic acid (RGD)-based peptide, and cyanine 7 (Cy7) are utilized for in vivo tumor targeting and fluorescence imaging of human glioblastoma U87MG tumors having ανβ3 integrin receptors, in mouse models. The rGONM-PEG suspension (1 μg mL -1) exhibits about 4.2- and 22.4-fold higher NIR... 

    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... 

    Detection of addition of barley to coffee using near infrared spectroscopy and chemometric techniques

    , Article Talanta ; Volume 99 , 2012 , Pages 175-179 ; 00399140 (ISSN) Ebrahimi Najafabadi, H ; Leardi, R ; Oliveri, P ; Chiara Casolino, M ; Jalali Heravi, M ; Lanteri, S ; Sharif University of Technology
    Elsevier  2012
    The current study presents an application of near infrared spectroscopy for identification and quantification of the fraudulent addition of barley in roasted and ground coffee samples. Nine different types of coffee including pure Arabica, Robusta and mixtures of them at different roasting degrees were blended with four types of barley. The blending degrees were between 2 and 20 wt% of barley. D-optimal design was applied to select 100 and 30 experiments to be used as calibration and test set, respectively. Partial least squares regression (PLS) was employed to build the models aimed at predicting the amounts of barley in coffee samples. In order to obtain simplified models, taking into... 

    The use of a glucose-reduced graphene oxide suspension for photothermal cancer therapy

    , Article Journal of Materials Chemistry ; Volume 22, Issue 27 , 2012 , Pages 13773-13781 ; 09599428 (ISSN) Akhavan, O ; Ghaderi, E ; Aghayee, S ; Fereydooni, Y ; Talebi, A ; Sharif University of Technology
    RSC  2012
    A single-step green method for effective reduction and functionalization of graphene oxide (GO) by glucose was developed. Then, efficacy of the glucose-reduced GO sheets in photothermal therapy of LNCaP prostate cancer cells was investigated in vitro. The GO suspension reduced and functionalized by glucose in the presence of Fe catalyst showed a biocompatible property with an excellent near-infrared (NIR) photothermal therapy efficiency better than hydrazine-reduced GO, single-wall and multi-wall carbon nanotube suspensions which even showed some levels of toxicities. For complete destruction of the cancer cells at some time intervals of NIR irradiation (e.g., 0.5 and 12 min with a power... 

    Photo-destruction of cancer cells by NIR irradiation and graphene nano-sheets

    , Article Technical Proceedings of the 2011 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2011, 13 June 2011 through 16 June 2011, Boston, MA ; Volume 3 , 2011 , Pages 236-239 ; 9781439871386 (ISBN) Abdolahad, M ; Mohajerzadeh, S ; Janmaleki, M ; Akhavan, O ; Azimi, S ; Clean Technology and Sustainable Industries Organization (CTSI); European Patent Office; Greenberg Traurig; Innovation and Materials Science Institute; Jackson Walker L.L.P ; Sharif University of Technology
    The photo-thermal therapy using nano-materials has attracted great attention as an efficient strategy for the next generation of cancer treatments. Recently, photo-thermal therapy based on nano-materials that can be activated by a skin-penetrating NIR (Near Infra Red) irradiation has been suggested as a noninvasive, harmless, and highly efficient therapeutic technique. Graphene nano-layers synthesized by a bio-compatible method, with reduced toxicity, will be a suitable candidate for the photo-thermal therapeutic agent. A significant amount of heat is generated upon excitation with near-infrared light (NIR, 700-1100nm) which is transparent to biological species including skins. In this... 

    One-pot thermolysis synthesis of CuInS2 nanoparticles with chalcopyrite-wurtzite polytypism structure

    , Article Journal of Materials Science: Materials in Electronics ; Volume 26, Issue 11 , November , 2015 , Pages 8960-8972 ; 09574522 (ISSN) Vahidshad, Y ; Tahir, M. N ; Mirkazemi, S. M ; Iraji Zad, A ; Ghasemzadeh, R ; Tremel, W ; Sharif University of Technology
    Springer New York LLC  2015
    CuInS2 nanoparticles as the visible (wurtzite, 1.67 eV) or near infrared (chalcopyrite, 1.50 eV) light absorbing material in thin film solar cells, were synthesized using facile, one step heating up method by dissolving of CuCl, InCl3 and SC(NH2)2 as precursors in oleylamine (OLA) alone or in combination with oleic acid (OA) and 1-octadecene (ODE) as solvent. The phase, size, morphology, and size distribution were controlled by the coordination ability between solvent molecules and metal precursors, reaction temperature and time. The presence of higher amounts of thiourea or OA to OLA led to the formation of chalcopyrite phase in comparison to wurtzite structure. Also, higher reaction... 

    Morphological dependence of light backscattering from metallic back reflector films: Application in dye-sensitized solar cells

    , Article Physica Status Solidi (A) Applications and Materials Science ; Volume 212, Issue 4 , January , 2015 , Pages 785-790 ; 18626300 (ISSN) Sharifi, N ; Ghazyani, N ; Taghavinia, N ; Sharif University of Technology
    Wiley-VCH Verlag  2015
    Conventionally, a film of TiO2 particles of 300 nm size is employed in Dye-sensitized solar cells (DSCs) as the back reflector film to enhance the light harvesting. Perfect reflectance of silver in visible and near infrared motivates to investigate its potential as the material for the light back reflector film in DSCs. In this study, light back reflector films consisting of 300 nm-sized silver particles, as well as vacuum evaporated silver flat film, were fabricated and compared to 300 nm-sized rutile-type TiO2 particulate reflector film to study their optical aspects. Conventional TiO2 rutile-type particulate film demonstrates slightly lower performance... 

    Structural and optical properties of Fe and Zn substituted CuInS2 nanoparticles synthesized by a one-pot facile method

    , Article Journal of Materials Chemistry C ; Volume 3, Issue 4 , Nov , 2015 , Pages 889-898 ; 20507534 (ISSN) Vahidshad, Y ; Tahir, M. N ; Zad, A. I ; Mirkazemi, S. M ; Ghazemzadeh, R ; Tremel, W ; Sharif University of Technology
    Royal Society of Chemistry  2015
    We substitute indium present in the CuInS2 ternary compound by iron and zinc using a facile one-pot synthesis method. The quaternary compound of CuIn1-xMxS2 (M = Fe and Zn) was synthesized by dissolving CuCl, InCl3, FeCl3, Zn(ac)2 and SC(NH2)2 as precursors in 1-octadecene, oleylamine and oleic acid as non-coordinating, coordinating and capping agent solvents, respectively. Oleic acid, oleylamine and thiourea were used respectively as a hard Lewis base, borderline Lewis base (in comparison with oleic acid) and soft Lewis base to form appropriate complexes. The complex formation, structure, and... 

    Supercritical water in top-down formation of tunable-sized graphene quantum dots applicable in effective photothermal treatments of tissues

    , Article Carbon ; Volume 130 , April , 2018 , Pages 267-272 ; 00086223 (ISSN) Tayyebi, A ; Akhavan, O ; Lee, B. K ; Outokesh, M ; Sharif University of Technology
    Elsevier Ltd  2018
    Supercritical water was used for simultaneous fragmentation and reduction of graphene oxide (GO) sheets into water-dispersible graphene quantum dots (GQDs) with tunable sizes. Transmission electron microscopy (TEM) demonstrated that by increasing the temperature above the critical point of water, the average size and thickness of the GQDs were decreased and the size uniformity and production yield were increased. The results of thermal conductivity measurement of GQD nanofluids with different weight fractions indicated that the GQDs prepared at supercritical condition could enhance the thermal conductivity of water by 65% as compared to 35% for the GQDs synthesized at sub-critical... 

    High-performance UV‐Vis-NIR photodetectors based on plasmonic effect in Au nanoparticles/ZnO nanofibers

    , Article Applied Surface Science ; Volume 483 , 2019 , Pages 1110-1117 ; 01694332 (ISSN) Hosseini, Z. S ; Arab Bafrani, H ; Naseri, A ; Moshfegh, A. Z ; Sharif University of Technology
    Elsevier B.V  2019
    In this study, UV‐Vis-NIR photodetectors based on decorated ZnO nanofibers (NFs) with optimized coverage of Au nanoparticles (NPs) fabricated via combined simple electrospinning and sputtering techniques are introduced. The effect of different coverages of Au NPs resulted from different Au nominal layer thicknesses on the morphology and optical properties of the ZnO fibers are investigated through various characterization methods. It is discovered that 4 nm Au nominal thickness provides the highest UV on/off ratio (~460), responsivity (~332 A/W), detectivity (~2.93×10 11 Jones) as well as faster rise and decay times as compared to pure ZnO nanofibers. A broad spectral response from UV to NIR... 

    Hyperthermia response of PEGylated magnetic graphene nanocomposites for heating applications and accelerate antibacterial activity using magnetic fluid hyperthermia

    , Article Applied Physics A: Materials Science and Processing ; Volume 126, Issue 4 , 2020 Hatamie, S ; Shih, P. J ; Soufi Zomorod, M ; Heravi, P ; Ahadian, M. M ; Hatami, N ; Sharif University of Technology
    Springer  2020
    In this research work, graphene/cobalt nanocomposites are functionalized with polyethylene glycol (PEG) to be a platform for theranostics application and antibacterial activity. The non-covalent functionalization of PEG on the surfaces of nanocomposites improved their stability and diminished their cytotoxicity. The PEGylated nanocomposites are demonstrated to allow simultaneous administration of two cancer therapy methods such as magnetic fluids hyperthermia (MFH) which is carried out by converting magnetic energy into heat through ferromagnetic cobalt nanoparticles and heat generation through near-infrared optical absorption by the reduced graphene oxide. A concise simulation is carried...