فهرست مطالب

  • Volume:7 Issue:1, 2011
  • تاریخ انتشار: 1390/03/07
  • تعداد عناوین: 6
|
  • S. H. Tohidi Pages 7-13
    Incorporation of copper species into silica matrix was performed by the sol-gel method. Copper ions and copper particles were doped using two different copper sources; Cu(NO3)2.3H2O and copper particles chemically synthesized.The particles of copper metallic, cuprous and cupric oxide were prepared and the synthesis and characterizations of copper species were compared together. On the other hand, their structures were analyzed by furrier transformation infra red spectroscopy and X-ray diffraction at 200, 400 and 600°C. Three main region contain Rocking (R), Bending (B) and Stretching (S) were recognized on their vibration structure using furrier transformation infra red spectra. Also, the scanning electron micrographs and chemical analysis of Cu and CuO/SiO2 were performed by energy dispersive X-ray spectroscopy. Average sizes of particles were determinated about 50 nm for CuO/SiO2 and were analyzed about 200 nm by transmission electron microscopy for the particles of Cu/SiO2.
    Keywords: Synthesis, Charactrization, Sol, gel, Copper Species
  • R. Azimirad, M. Kargarian, O. Akhavan, A. Z. Moshfegh Pages 14-20
    Electrical, structural and morphological properties of Ni silicide films formed in Ni(Pt 4at.%)/Si(100) and Ni0.6Si0.4(Pt4at.%)/Si(100) structures at various annealing temperatures ranging from 200 to 1000 oC were studied. The Ni(Pt) and Ni0.6Si0.4(Pt) films with thickness of 15 and 25 nm were deposited by RF magnetron co-sputtering method, respectively. The annealing process of the structures was performed by using a long time annealing (LTA) procedure for 30 min. The samples were analyzed by four point probe sheet resistance (Rs) measurement, x-ray diffraction (XRD) and atomic force microscopy (AFM) techniques. It was found that the thermal stability as well as the surface morphology of “as-formed” Ni silicide nanolayers depends on annealing temperature. Ni silicide nanolayers formed in the Ni0.6Si0.4(Pt)/Si systems are more thermally stable as compared to those formed in the Ni(Pt)/Si systems during LTA procedure. It was also determined that the NiSi phase with Rs value of about 4 Ω/□ is formed in a wide temperature range from 400 to 900 oC. Indeed, the addition of Si during the Ni deposition restricts the agglomeration of NiSi layer and retards phase formation of NiSi2. According to AFM morphological analysis, NiSi layers formed in the Ni0.6Si0.4(Pt)/Si systems at high temperatures have low average surface roughness and can be used as a contact material in nanometric scale.
    Keywords: Nickel monosilicide (NiSi), Thermal stability, Surface roughness, Sputtering, Contact layer
  • D. Afzali*, Z. Biniaz, A. Mostafavi Pages 21-27
    The present article reports on the application of modified organo nanoclay as a green, easily prepared and stable solid sorbent for the preconcentration of trace cobalt ion in aqueous solution. The organo nanoclay was modified by adsorption of 5-(4-dimethyl amino-benzylidene) rhodanin reagent onto it. The sorption of Co2+ ions was quantitative in the pH range of 7.0 to 8.5, whereas quantitative desorption occurs instantaneously in 5.0 mL of 2.0 mol L-1 HNO3. The eluted solution was aspirated directly into the flame of atomic absorption spectrometry (FAAS). Linear range for determination of cobalt was maintained between 0.176 ng mL-1 to 15.0 μg mL-1 in initial solution. Relative standard deviation for ten replicated determination of 1.0 μg mL-1 of cobalt was ±2.34%. Detection limit was 0.1 ng mL-1 in initial solution (3Sbl, n=10) and preconcentration factor was 170. The sorption capacity of modified nanoclay for Co (II) was evaluated 0.56 mg per g of sorbent. The effects of the experimental parameters, including the sample pH, flow rates of sample and eluent solution, eluent type, breakthrough volume and interference ions were studied for preconcentration of Co2+. The proposed method was applied for determination of cobalt in water samples.
    Keywords: Nanoclay application, Cobalt determination, Preconcentration
  • A. Iranmanesh*, Y. Alizadeh Pages 28-34
    In this paper an algorithm for computing the Balaban and Randic indices of any simple connected graph was introduced. Also these indices were computed for IPR C80 fullerene isomers, Zigzag nanotubes and graphene by GAP program.
    Keywords: Balaban index, Randic index, IRP C80 Fullerene isomers, Zigzag nanotubes, Graphene, GAP program
  • F. Hosseinibalam, S. Hassanzadeh, O. Ghaffarpasand* Pages 35-47
    Langevin equation for a nano-particle suspended in a laminar fluid flow was analytically studied. The Brownian motion generated from molecular bombardment was taken as a Wiener stochastic process and approximated by a Gaussian white noise. Euler-Maruyama method was used to solve the Langevin equation numerically. The accuracy of Brownian simulation was checked by performing a series of simulations. Particles’ trajectories for an ensemble of 1000 particles were calculated and compiled by Lagrangian approach. Numerical simulation in cartesian coordinate were validated by exact solution of Einstein and good agreement was observed. Moreover, strong convergence of proposed method has been considered. The approximated scheme has strong order of convergence, 1.5. Langevin equations in cylindrical coordinate were also considered as stochastic differential equations (SDE) and in different SDE calculus were solved numerically by validated numerical method. A novel approach to simulating the Brownian motion as the Gaussian white noise is presented in cylindrical coordinates. Obtained results for different SDEs calculus were compared and suggested that there are no considerable differences between Ito and Stratonovich approaches in two phase flow systems.
    Keywords: Stochastic Differential Equation (SDE), Nano, Aerosol (NA), Laminar Fluid, Stratonovich, Ito
  • A. Mehrizad, P. Gharbani* Pages 48-53
    Catalytic and photocatalytic reactions of (2-chloroethyl) phenyl sulfide (2-CEPS), a mimic of bis (2-chloroethyl) sulfide (i.e. Sulfur mustard) were studied on the surfaces of titanium oxide. TiO2 nanoparticles (anatase, rutile and mixture of 80% anatase/20% rutile) along with bulk TiO2 were tested as reactive sorbents for reaction of 2-CEPS at room temperature (25±0.5°C). Reactions were monitored by GC-FID technique and reaction products were characterized by GC-MS. Data explores the role of hydrolysis and elimination reactions in the reaction of 2-CEPS on titanium oxide. In these reactions, 2-CEPS undergo photocatalytic reactions to yield (2-hydroxyethyl) phenyl sulfide, (2-ethoxyethyl) phenyl sulfide and vinyl phenyl sulfide. Also data reveals that the maximum decontamination of 2-CEPS was related to nano-TiO2 (80% anatase/ 20% rutile)/ UV.
    Keywords: Catalytic, Photocatalytic, Decontamination, Nano, TiO2, (2, Chloroethyl) phenyl sulfide