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Scientia Iranica - Volume:28 Issue: 3, May-Jun 2021

Scientia Iranica
Volume:28 Issue: 3, May-Jun 2021

  • Transactions on Nanotechnology (F)
  • تاریخ انتشار: 1400/04/15
  • تعداد عناوین: 8
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  • E. Sarvestani, G. R. Khayati * Pages 1871-1883
    Unique chemical and physical properties of silver nanoparticles (AgNPs) enhances its usages in various categories such as medical utilities. Due to the high dependency of AgNPs properties to the size, this study is an attempt to employ gene expression programing (GEP) for constructing a quantitative model for estimating the size of AgNPs in montmorillonite/chitosan bionanocomposites that prepared by chemical approach. Generalization capabilities, fault tolerance, noise tolerance, high parallelism, nonlinearity and significant information processing characteristics are the main advantages of GEP. Accordingly, the practical parameters including reaction temperature, AgNO3 concentration, weight of montmorillonite in aqueous AgNO3/chitosan solution (WMMT) and the percentage of chitosan are selected as input parameters through GEP modeling. The accuracy of proposed models are investigated by statistical indicators including mean absolute percentage error (MAPE), root relative squared error (RRSE), root mean square error (RMSE) and correlation coefficient (R2). Finally, the best model is selected by R2 = 0.987, RMSE = 0.100, RRSE = 0.146 and MAPE = 0.221. The sensitivity analysis confirmed that the percentage of chitosan, concentration of AgNO3, WMMT and reaction temperature are the most effecting parameters on the size of AgNPs, respectively.
    Keywords: Silver nanoparticle, gene expression programming, Montmorillonite, Chitosan, Bionanocomposites, sensitivity analysis
  • M.H. Khazaei Feizabad, G. R. Khayati *, S. Pouresterabadi Pages 1884-1895
    The carbon nanotubes (CNTs) were produced by mechanical milling of Hexane in the presence of two different catalysts (amorphous and crystalline Fe) at Ar atmosphere. Raman spectroscopy, Fourier-transform infrared spectroscopy, transmission electron microscopy, high-resolution scanning electron microscopy, Brunauer–Emmett–Teller (BET) and thermal analysis were employed to characterize the CNTs. The results showed that the amorphous catalyst induced more structural defects in CNTs respect to the crystalline catalyst. The ratio of single wall to multiwall CNTs of prepared samples were about 0.31 and 7.3 for crystalline and amorphous catalyst, respectively. Moreover, the BET results confirmed the higher adsorption capacity of the sample prepared by amorphous catalyst due to their higher structural defects.
    Keywords: carbon nanotubes, Mechanical milling, Amorphous catalyst, Crystalline catalyst, Hexane
  • M. Sohail *, U. Nazir, Y. M. Chu, W. Al Kouz, P. Thounthong Pages 1896-1907

    A numerical examination is conducted for the magnetohydrodynamics steady Carreau fluid flow on the transport of thermal energy and mass specie comprising nanoparticles with gyrotactic microorganisms through heated disk. The role of thermophoresis and Brownian motion are added in this flow problem. Governing equations are achieved by using the boundary layer theory in view of a coupled system of PDEs involving boundary conditions. The highly non-linear system of ODEs is generated using the concept of the transformation approach. Since the system of transformed equations is highly nonlinear, so, an approximate solution is estimated via optimal homotopy method. The role of prominent parameters on velocity, thermal energy, mass specie and motile density microorganisms examined graphically. Additionally, graphical observations regarding mass specie, thermal energy and velocities are discussed briefly. It has estimated that the motion of fluid particles is diminished because of the intensity of the magnetic field while mass specie and fluid temperature rise versus enhancement the values of the magnetic field.

    Keywords: Brownian diffusion, Heat, mass transport, Carreau fluid, Bioconvective process, Rotating heated disk, Boundary layer analysis
  • A. H.A. Jalaukhan, B. Ghanbari Shohany *, R. Etefagh Pages 1908-1916
    In this paper, SnO2-pure and SnO2/GO thin films with different concentrations of graphene oxide (0, 1, 2, 3 and 4 g/ml) were synthesized using spin coating method. The synthesized thin films were used to study the structural, morphology, chemical, optical and photocatalytic degradation of Methyl Orange (MO) under UV light irradiation by X-ray diffraction (XRD) spectroscopy, field emission scanning electron microscopy (FESEM), Raman spectroscopy, Ultraviolet–visible spectroscopy and UV light respectively. The XRD results of graphene oxide show that the peak is very sharp with high intensity, which indicates a very good crystallinity of the GO structure. The band gape value of SnO2/GO thin films increase by increasing of GO concentration. Under UV light irradiation, the photocatalytic activity of synthesized samples was measured using Methyl Orange dye. The obtained results indicate that by adding graphene oxide concentration, the photocatalytic activity of the tin oxide thin film increases.
    Keywords: SnO2, GO, spin coating method, Optical properties, photo catalytic activity
  • S. Jabeen *, T. Hayat, A. Alsaedi Pages 1917-1925
    In present research, we concentrated on the characterization of Walters-B nanofluid flow to investigate the irreversibility mechanism. Energy equation incorporated with radiation effects and heat generation phenomena. Influence of activation energy is discussed using modified Arrhenius energy term along binary chemical reaction. The consequences of thermophoresis, Brownian motion and viscous dissipation on fluids velocity, temperature of fluid particles and concentration of involved chemical species. Set of ordinary differential equations are obtained by implementing appropriate similarity variables. Governing mathematical model is solved using homotopy analysis method. Flow behavior is analyzed through Nusselt number, coefficient of drag force and mass transfer rate.
    Keywords: viscous dissipation, Walters-B nanofluid, entropy generation, thermal radiation, MHD, Heat generation, absorption, Activation energy
  • Sh. Akhter, M. Ashraf * Pages 1926-1938
    Recent trend in advanced nanotechnology has developed the thermal consequences of nanoparticles due to increasing significance in various engineering and thermal extrusion systems. In this continuation, two-dimensional flow of viscous nanoliquid in the presence of gyrotactic micro-organisms encountered by a porous stretched surface is addressed numerically. The novel aspects of Brownian diffusion and thermophoresis are studied by using Buongiorno model. The thermal radiation impact is imposed in the energy equation. A set of pertinent transformations has been suggested to transform the governing non-linear partial differential equations into system of non-linear ordinary differential equations. A famous numerical method, finite difference technique, is engaged to acquire the numerical solution of modeled dimensionless equations. The flow analysis for effects of numerous prominent parameters on velocity, temperature, concentration and motile micro-organisms profiles is presented graphically. In the presence of thermal radiation, velocity profiles detract with augment of bioconvection Rayleigh number and buoyancy ratio parameter, while opposite trend is observed for boosting the Grashoff number. The porous medium as well as the radiation enhance the fluid temperature.
    Keywords: Bioconvection flow, viscous fluid, Gyrotactic microorganisms, Porous medium
  • O. Malekan, M. M. Bagheri Mohagheghi *, M. Adelifard Pages 1939-1952
    In this paper, the synthesis processes of perovskite active films of CH3NH3PbI3 (MAPbI3) have been studied for perovskite hybrid solar cells by spin and dip coating in ambient atmosphere, and without glove box to reduce production cost for technological applications. The morphology and structural, electrical and optical properties of perovskite films have been investigated by X-ray Diffraction (XRD), Field-Emission Scanning Electron Microscopes (FE-SEM), Atomic Force Microscopes (AFM) and Ultraviolet–visible spectroscopy (UV-Vis). A precursor solution of lead Iodide (PbI2) with Dimethylformamide (DMF) solvent by spin coating at two stages (a) R=4500 rpm and (b) R=6000 rpm, and methyl ammonium iodide (CH3NH3I) with isopropanol solvent by dip coating, have been prepared for active perovskite layer (CH3NH3PbI3).
    Keywords: Perovskite solar cells, Methyl ammonium lead iodide, CH3NH3PbI3, Thin films
  • A. Olad *, M. Anarchi, R. Nosrati Pages 1953-1961
    The silica/zeolite-A nanocomposite additive was loaded at different values (1 - 4% wt) into polyvinyl acetate matrix to improve its wood adhesive properties. The silica nanoparticles were prepared by calcination method using rice husk as source material. X-ray diffraction analysis, FTIR spectroscopy, and SEM techniques were used for the characterization of the nanocomposite. The thermal stability and adhesion properties of modified polyvinyl acetate were evaluated by thermogravimetric analysis (TGA) method and measuring the shear strength of wood joints respectively. According to the results, the addition of silica/zeolite-A nanocomposite into polyvinyl acetate in dry condition and elevated temperatures was led to the enhanced shear strength of wood joints. However, in wet conditions, improvement of shear strength which was obtained by the addition of silica/zeolite-A nanocomposite was lower than that of the dry condition. Additionally, the thermal stability of polyvinyl acetate was affected by silica/zeolite-A nanocomposite. Polyvinyl acetate containing silica/zeolite-A nanocomposite additive showed better stability in water with respect to the pristine polyvinyl acetate.
    Keywords: Wood, adhesive, polyvinyl acetate, silica, zeolite-A, Nanocomposite