Sharif University of TechnologyScientia Iranica1026-309824320170601On the oscillatory frequency of the carbon nanotube-based nanothermometers16151625413910.24200/sci.2017.4139ENR. AnsariDepartment of Mechanical Engineering, University of Guilan, Rasht, P.O. Box 3756, IranM. DaliriDepartment of Mechanical Engineering, University of Guilan, Rasht, P.O. Box 3756, IranM. HosseinzadehDepartment of Mechanical Engineering, University of Guilan, Rasht, P.O. Box 3756, Iran.Journal Article20150618Electromechanical nanothermometers are instruments that work on the basis of the van der Waals (vdW) potential energy and interaction force of their constituent carbon nanotubes (CNTs). The CNT-based nanothermometers have two different congurations: telescope and shuttle congurations. In this article, based on the Lennard-Jones potential function together with the continuum approximation, first, the vdW potential energy and interaction force for a telescope conguration with nite CNTs are derived, which have not been obtained in the previous research studies. Thereafter, by employing the interaction force, the equation of motion between constituent CNTs is solved. Subsequently, a new semi-analytical expression is obtained which enables one to precisely evaluate the oscillation frequency. By employing the given formulae, effects of<br />dierent system parameters on the vdW interactions and oscillation frequency are shown.https://scientiairanica.sharif.edu/article_4139_9698ec79273993c1fa416aa9c152ff4d.pdfSharif University of TechnologyScientia Iranica1026-309824320170601Retracted: Thermally-aware circuit modeling and performance analysis of single-walled carbon nanotube bundle as VLSI interconnects16261634414010.24200/sci.2017.4140ENJournal Article20151013Temperature-dependent delay, power dissipation, and Power Delay Product (PDP) are analyzed in a single-walled carbon nanotube (SWCNT) bundle interconnect. Thermally-aware circuit model for a metallic SWCNT bundle is presented. The results are compared with those of the currently used copper interconnects at 22 nm technology node. It is seen that delay, power dissipation, and PDP of SWCNT bundle interconnect increase with a rise in temperature from 300 K to 450 K at dierent interconnect lengths from 100 m to 1000 m. It is also observed that with rise in temperature, SWCNT bundle has a lower delay than that of copper for all interconnect lengths, whereas the reverse is true for power dissipation. In addition, with rise in temperature from 300 K to 450 K, for interconnect lengths at 100 m and 400 m, SWCNT bundle has lower PDP compared to copper interconnects, whereas the reverse is true for interconnect lengths at 700 m and 1000 m. Moreover, relative average improvement in delay, power, and PDP using thermally-aware resistance model is estimated in comparison with temperatureindependent resistance model of an SWCNT bundle. Based on simulation results, the thermally-aware resistance model of a SWCNT bundle achieved improvement in accuracy<br />of delay, power, and PDP estimation of about 22.44%, 7.59%, and 31.96%, respectively, on average.Sharif University of TechnologyScientia Iranica1026-309824320170601An analytical solution for bending, buckling, and free vibration of FG nanobeam lying on Winkler-Pasternak elastic foundation using different nonlocal higher order shear deformation beam theories16351653414110.24200/sci.2017.4141ENV. RefaeinejadSmart Structures and New Advanced Materials Laboratory, Department of Mechanical Engineering, University of Zanjan, Zanjan,
Iran.O. RahmaniSmart Structures and New Advanced Materials Laboratory, Department of Mechanical Engineering, University of Zanjan, Zanjan,
Iran.S.A.H. HosseiniSmart Structures and New Advanced Materials Laboratory, Department of Mechanical Engineering, University of Zanjan, Zanjan,
IranJournal Article20151224In the present study, various Higher-order Shear Deformation beam Theories (HSDTs) are applied in order to achieve the exact analytical solution to bending, buckling, and free vibration of Functionally Graded (FG) nanobeam lying on the Winkler and Pasternak elastic foundations. HSDTs are those in which the effect of transverse shear strain is included. The displacement field of these theories involves a quadratic variation<br />of transverse shear strains and stresses; hence, this hypothesis leads to the diminishing of transverse shear stresses at the top and bottom surfaces of a beam. Thus, necessarily, there is no need to use a shear correction factor in the HSDTs. Nanobeam has been made of FG materials in which the properties of these materials are changed through the thickness direction of nanobeam according to the power-law distribution. Hamilton's principle is used to derive the equation of motions and the related boundary conditions of simply<br />supported nanobeam. The present study shows that the stability and vibration behaviors of FG nanobeam are extremely dependent on the Winkler and Pasternak elastic foundation, gradient index, aspect ratio, and nonlocal parameter. The obtained results of the present study might be useful in the advanced field of micro/nano electromechanical systems.https://scientiairanica.sharif.edu/article_4141_b8db5364ea91c666d2bf8ba2e685f6b3.pdfSharif University of TechnologyScientia Iranica1026-309824320170601Evaluation of physical and mechanical properties of B-tri-calcium phosphate/poly-3-hydroxybutyrate nanocomposite scaffold for bone tissue engineering application16541668414210.24200/sci.2017.4142ENSh. ShahiDepartment of Material Engineering, Shahreza Branch, Islamic Azad University, Shahreza, Isfahan, IranS. KarbasiBiomaterials Group, Advance Medical Technology Department, Isfahan University of Medical Sciences, Isfahan, IranJournal Article20160610One of the major challenges facing researchers of tissue engineering is the scaold design with desirable physical and mechanical properties for growth and proliferation of cells and tissue formation. In this paper, rstly, -tricalcium phosphate (-TCP) nanopowders with particle size of 50-70 nm were synthesized using a simple sol-gel route with calcium nitrate and potassium dihydrogenphosphate as calcium and phosphorus<br />precursors, respectively. Then, the porous ceramic scaold containing 40, 50, and 60 wt% of n-TCP was prepared by the polyurethane sponge replication method. The scaffolds were coated with P3HB for 30 sec and 1 min in order to increase the scaold's mechanical properties. XRD, XRF, SEM, TEM, and FT-IR were used in order to study the phase and element structure, morphology, particle size, and determination of functional groups respectively. Based on the results of compressive strength and porosimetry tests, the most appropriate type of scaold is 50 wt% of n-TCP immersed for 30 sec in P3HB with 75% porosity in 200-600 m, with a compressive strength of 1.09 MPa and a compressive modulus of 33 MPa, which can be utilized in bone tissue engineering.https://scientiairanica.sharif.edu/article_4142_06671d7f7c6dd6c04beabbce8c699f30.pdfSharif University of TechnologyScientia Iranica1026-309824320170601Petahertz-frequency plasmons in graphene nanopore and their application to nanoparticle sensing16691677414310.24200/sci.2017.4143ENB. FotouhiDepartment of Electrical & Computer Engineering, Tarbiat Modares University, Tehran, Iran.V. AhmadiDepartment of Electrical & Computer Engineering, Tarbiat Modares University, Tehran, Iran.M. AbasifardDepartment of Electrical & Computer Engineering, Tarbiat Modares University, Tehran, IranV. FaramarziDepartment of Electrical & Computer Engineering, Tarbiat Modares University, Tehran, Iran.Journal Article20160617The Surface Plasmon Resonance (SPR) properties in the petahertz (1015 Hz) frequency range for monolayer graphene nanosheet and graphene nanopore are investigated using discrete dipole approximation method. We calculate graphene refractive indices by using rst-principle density functional theory. The near-field enhancement made by plasmon in these structures is studied by employing nite-dierence-time-domain method. For graphene nanosheets, energy of the SPR peak drops with increase in the sheet length. Also, for graphene nanopores smaller than 5 nm in length, increasing the pore diameter decreases energy of the SPR peak and for some length values like 6 nm, this energy value is raised. For larger sheets (e.g., 8 nm), SPR peak is rather unchanged by variations of the pore diameter. The SPR is used to detect nanoscale objects such as gold, silver, copper, rhodium, and aluminium oxide. If nanoscale particles are inserted into the graphene nanopore, 0.195 to 0.474 eV shift in the SPR spectra appears. Type of the presented nanoparticle can be clearly determined by measuring the energy shifts in the SPR spectra. Our results show that petahertz-frequency plasmon in graphene nanopore can be used as a nanoscale-object detection methodology.https://scientiairanica.sharif.edu/article_4143_289fd8fbb52e203abcc17e9cbe553bb6.pdfSharif University of TechnologyScientia Iranica1026-309824320170601Enhanced electro-oxidation of urea based on nickel nanoparticle decorated reduced graphene oxide/PEDOT:PSS composite16781685414410.24200/sci.2017.4144ENM. Mazloum-ArdakaniDepartment of Chemistry, Faculty of Science, Yazd University, Yazd, P.O. Box 89195-741, Iran.F. FarbodDepartment of Chemistry, Faculty of Science, Yazd University, Yazd, P.O. Box 89195-741, IranL. HosseinzadehDepartment of Chemistry, Faculty of Science, Yazd University, Yazd, P.O. Box 89195-741, IranJournal Article20160621A facile two-step systematic plan of action was used to prepare nanocomposite of Reduced Graphene Oxide (RGO) doped poly(3,4-ethylenedioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) decorated with nickel nanoparticles (Ni NPs) onto a Glassy Carbon Electrode (GCE). Composites of PEDOT:PSS and RGO were prepared by mixing each component solution and were fabricated as a benecial substrate for Ni NPs. Ni NPs were electrodeposited on the PEDOT-RGO support by applying constant potential into nickel ions solutions. Then, Ni/PEDOT-RGO/GCE was employed as an efficient electrocatalyst for electrooxidation of urea. The electrocatalytic properties of Ni NPs/PEDOT-RGO modied glassy carbon electrode toward the oxidation of urea<br />were analyzed by Cyclic Voltammetry (CV) and chronoamperometry (CA). Such studies evidenced the high electrocatalytic activity of Ni NPs and mixed PEDOT-RGO, which is mainly ascribed to the good electrochemical activity of PEDOT-RGO composites and the well-dispersed Ni NPs on the surface of PEDOT-RGO composite.https://scientiairanica.sharif.edu/article_4144_3c9f0f9563e9f57accf9cd9b39aed0f2.pdfSharif University of TechnologyScientia Iranica1026-309824320170601Natural convection and entropy generation of ultrafine atmospheric aerosols in the presence of hydrodynamic partial slip and thermal radiation due to solar energy16861705414510.24200/sci.2017.4145ENO. GhaffarpasandDepartment of Physics, University of Isfahan, Isfahan 81746, IranJournal Article20160921Combined eects of hydrodynamic partial slip, thermal radiation due to solar energy, and nanoparticles volume fraction on natural convection and entropy generation of atmospheric ultrane aerosols sample enclosed within a two-sided lid-driven cavity are studied numerically in the present contribution. Partial slip eect is taken into<br />account along the two horizontal moving walls, and thermal radiation is considered through Rosseland approximation. The governing equations are solved using an accurate finite volume method based on SIMPLE algorithm. The impact of Brownian motion of nanoparticles is also considered in this study, whereby KKL (Koo-Kleinstreuer-Li) correlation is utilized for simulating the eective thermal conductivity and viscosity of nano<br />uid. The heatline visualization technique is also utilized to study the energy flux within the cavity. A comprehensive study is conducted on the controlling parameters, including partial slip coecient ( = 0 5), radiation parameter (Rd = 0 2), and nanoparticles volume fraction ( = 0 4%), which influence the <br />ow and heat transfer characteristics. Results show that the partial slip usually eliminates the effect of mechanical forces provoked by the moving lids. Moreover, thermal radiation homogenizes the medium<br />thermally, which results in decreasing the average entropy generation. It is also observed that the eect of carbon-black nanoparticles on the atmospheric heat transfer manifests a wide variety of fashions mainly dependent on the presence or absence of thermal radiation due to solar energy.https://scientiairanica.sharif.edu/article_4145_17b18ba5209da4c182a3ea1c644028ed.pdfSharif University of TechnologyScientia Iranica1026-309824320170601Copper-doped and copper-free bioactive glass nanopowders cytotoxicity and antibacterial activity assessment17061716414610.24200/sci.2017.4146ENSh. Soltani-DehnaviDepartment of New Science and Technology Campus (Biomaterial Group), Semnan University, Semnan, P.O. Box 35131-19111,
IranM. Mehdikhani-NahrkhalajiDepartment of Biomedical Engineering, Faculty of Engineering, University of Isfahan, Isfahan, P.O. Box 81746-13441, IranM. RafieniaBiosensor Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.A. DoostmohammadiDepartment of Materials, Faculty of Engineering, Shahrekord University, Shahrekord, IranJournal Article20160229The purpose of this study is to evaluate the antibacterial activity and cytotoxicity of copper-doped (Cu45SBG) and copper-free bioactive glass (45SBG) nanopowders. The antibacterial eect was studied using Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria. The BG nanopowders were synthesized by the sol-gel<br />technique. They were characterized by various techniques and their cytotoxicity was evaluated by MTT assay. Chemical compositions of BGs were as the same as the predicted compositions. The size of the BGs with an amorphous structure was measured to be around 100 nm. Both BG nanopowders have no antibacterial eect on broth concentrations less than 12.5 mg/ml. They demonstrated similar antibacterial activity on E. coli with<br />Minimum Bactericidal Concentration (MBC) of 12.5 mg/ml. Cu45SBG nanopowders with the MBC of 25 mg/ml were more ecient on S. aureous bacteria than 45SBG nanopowders with the MBC of 50 mg/ml. Compared to 45SBG, Cu45SBG showed much more cytotoxicity. 45SBG demonstrated similar cells viability to the control. It was concluded that to overcome cytotoxic eect, Cu content of BGs nanopowders must be lower than the amount used in this research. Therefore, 45SBG nanopowders with considerable antibacterial activity could be used as a good candidate for biomedical applications.https://scientiairanica.sharif.edu/article_4146_20aa7a324744ce07a1026f6206c1914e.pdfSharif University of TechnologyScientia Iranica1026-309824320170601Synthesis and antimicrobial properties of ZnO/PVA, CuO/PVA, and TiO2/PVA nanocomposites17171723414710.24200/sci.2017.4147ENR. EtefaghDepartment of Physics, University of Guilan, Rasht 41335, IranS.M. RozatiDepartment of Physics, University of Guilan, Rasht 41335, IranE. AzhirDepartments of Physics, Ferdowsi University of Mashhad, Mashhad, Iran.N. ShahtahmasebiDepartments of Physics, Ferdowsi University of Mashhad, Mashhad, Iran.A.S. HosseiniDepartments of Physics, Ferdowsi University of Mashhad, Mashhad, Iran.Journal Article20160406In this paper, zinc oxide (ZnO), copper oxide (CuO), and titanium oxide (TiO2) nanoparticles were prepared using sol-gel method. The structural properties of these nanoparticles were characterized using X-Ray Diraction (XRD) and Transmission Electron Microscopy (TEM). SEM images revealed that the average sizes of zinc oxide, copper oxide, and titanium oxide nanoparticles are about 37 nm, 86 nm, and 50 nm, respectively. Then, nanocomposites of metal oxide were produced by Polyvinyl Alcohol (PVA). The antibacterial activities of zinc oxide, copper oxide, and titanium oxide nanocomposites against human pathogenic bacteria, mainly Escherichia coli HB101 (gram-negative), have been studied using drop test during the time periods of 15 minutes, 30 minutes, 1 hour, 2 hours, 12 hours, and 24 hours of generated reviews. According to the results obtained with the nanocomposite, zinc oxide nanoparticles exhibit the highest antibacterial properties.https://scientiairanica.sharif.edu/article_4147_905ee85512a7e540d84718b40766e20c.pdfSharif University of TechnologyScientia Iranica1026-309824320170601First-principles study of strain-induced charge polarization in a molybdenum disulfide monolayer17241733414810.24200/sci.2017.4148ENN. SalamiDepartment of Physics, Yasooj Branch, Islamic Azad University, Yasooj, IranA.A. ShokriDepartment of Physics, Tehran Payame-Noor University, Tehran, P.O. Box 19395-3697, IranJournal Article20160607In the presence of elastic planar strain distributions, electronic properties of molybdenum disulde (MoS2) monolayer are investigated within Density Functional Theory (DFT) calculations as implemented in SIESTA package. Three types of planar strain are considered with some dierent intensity values, and uniaxial strain along the armchair and zigzag directions as well as biaxial strain. We present a systematic study of the strained MoS2 monolayer by focusing on the calculation of Total Density Of State (TDOS), Partial Density Of State (PDOS), electron charge density, and electrostatic potential using post processing tools. In most cases, the states due to Mo atoms have dominant association in the TDOS close to the Fermi level of MoS2 monolayer under strain. As a consequence of the strain, S atom takes electron from Mo atom and becomes negatively charged. In addition, the tensile and compressive strains introduce the charge polarization in twoopposite directions per three types of strain for both sheets, which is in line with the experimental study. As another important result, the strain-induced charge polarization is proportional to the intensity value of strain.https://scientiairanica.sharif.edu/article_4148_54ca9b639eca5bde002b186b906bbbce.pdf