فهرست مطالب

Theoretical and Applied Physics - Volume:4 Issue:4, 2011
  • Volume:4 Issue:4, 2011
  • تاریخ انتشار: 1390/04/30
  • تعداد عناوین: 8
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  • A. A. Ashkarran Page 1
    Ag-doped TiO2 nanoparticles were synthesized by combination of two bottom-up and top-down methods and the products were characterized by X-Ray diffraction (XRD), Brunauer Emmett Teller (BET), X-ray photoelectron spectroscopy (XPS) and ultra violet-visible absorption spectroscopy (UV-Vis). The visible light antibacterial activities were successfully demonstrated for the inactivation of Escherichia coli (E-coli) bacteria. The results revealed that the Ag/TiO2 nanoparticles extended the light absorption spectrum toward the visible region and significantly enhanced the inactivation of E-coli bacteria under visible light irradiation. 0.15 g Ag/TiO2 nanoparticles exhibited highest antibacterial activity. The significant enhancement in the antibacterial properties of Ag/TiO2 nanoparticles under visible light irradiation can be ascribed to the effect of doped noble metal Ag by acting as electron traps in TiO2 band gap.
  • A. A. Mehmandoost-Khajeh-Dad, M. Mahjour-Shafiei, M. Khaghani Page 9
    Development of a Doppler broadening positron spectroscopy setup is reported. The setup consists of an HPGe detector with energy resolution of 2.1 keV at 411.8 keV in coincidence with a NaI detector. The stability of the electronic devices was extensively studied. Finally, the relative positron-electron momentum distribution for commercial Al was measured. The comparison between our data and other’s data reveals a very good agreement.
  • A. Rajaee, M. Shahriari, A. Kamali Asl, S. H. Hosseini Page 13
    Performance of a single photon emission imaging system (SPECT) is determined more by the collimator than any other components. In high energy septal penetration and parallax error increases and the quality of image decreases. For reduction of the artifacts, high-z materials with high density such as depleted Uranium, Gold and Tungsten can be used instead of lead. In this work, the effect of collimator material has been evaluated. Also the dimensions (Septa thickness, Hole length, MTF (Modulation Transfer Function), Septal penetration and hole pattern) of the collimators has been investigated. MCNP Monte Carlo code has been used for our simulations. In order to benchmark, the HEGP and UHEGP collimators of GE Company are selected and FWHM values of the collimators calculated and compared with GE Company reported data. The effect of three materials (Tungsten, depleted Uranium and Gold) instead of lead has been investigated. The comparison showed good agreement between the simulation results and GE reported data. Performance of the collimator improved by increasing the atomic number of the collimator material. The collimators made of Uranium, Gold, Tungsten and Lead have better performance respectively with the same geometry. All results showed that, in addition to collimator dimensions, the effect of material has great influence on the quality of the image and collimator performance.
  • L. Nikzad, M. R. Vaezi, A. R. Mirhabibi, J. Javadpour Page 19
    Recently, reduction in research costs and less practicing experimental procedure are greatly desired. To obtain this purpose experimental design technique is necessary. In this study, Taghuchi experimental design was used to investigate rheological properties of graphite suspension and green tapes considering 5 variables in 4 levels. These variables are graphite content, graphite flake size, binder content, dispersant and plasticizer content. The binder has the greatest effect on green tape properties so in this paper we study effect of binder on properties of slips and tapes.After investigating rheological properties the tapes were characterized by measuring density, tensile strength plus the critical fracture strain.
  • F. Torkashvand, G. Darvish, E. Darabi Page 25
    We numerically analyze the band gap properties of a two dimensional (2D) photonic crystal created by a square lattice of GaAs rods with different radii in air back ground by plane wave expansion method. Two cross sections for rods (circular and hexagonal) are considered and the absolute band gap width is maximized with respect to theshape, radius of rods and rotation angle of the lattice.
  • L. Gholamzadeh, A. Ghasemizad, S. Ghaseminejad Page 29
    By using the OK1 code with some corrections, the energy deposition profile and irradiation non-uniformity of lead (Pb) beams are studied onto a direct-drive fuel pellet, in mono-layer diamond pellet structure and an aluminum mono-layer pellet structure using 12- beams and 120- beams irradiation schemes. The root-mean-square (RMS) nonuniformityvalue becomes σRMS= 5.70 %, 4.46% in a diamond mono-layer pellet structure and σRMS= 10.72 %, 6.94% in an aluminum mono-layer pellet structure for the 12-beams and 120-beams system, respectively. The maxiumum of deposited energy value is 6.9960×104 J in diamond mono-layer pellet structure and this value is 5.1393×104J in an aluminum mono-layer pellet structure in the 3.89 mm of pellet radius for the 12-beams systems. As a result, the RMS and PTV non-uniformities are decreased with increasing of the total beam numbers and these values are low at the Bragg peak layer. The RMS non-uniformity for diamond mono-layer pellet structure was lower than that for aluminum mono-layer pellet structure.
  • F. Sheikhehi, M. Hantehzadeh, M. Naseri Page 39
    A secure quantum report with authentication based on GHz states and entanglement swapping is proposed. The protocol lets authorized parties Bob and Charlie use N groups three particle GHz states to send their secret reports to their boss (Alice). Here, entanglement swapping of GHz states and Bell state measurement is employed by thecommunicators. It will be shown that using this method guarantees the honesty of the protocol, and scheme is secure not only against the intercept-and-resend attack but also against disturbance attack.
  • L. Farhang Matin, M. Bagheri, O. R. Safiyary Page 45
    Single shock in reaction-diffusion models on the Bethe lattice with nearest neighbor interaction is introduced. The evolution equation of the system can be solved through the full interval method in closed form exactly. Comparing the results of analytical and numerical approaches is studies. The stationary and dynamics solution of such modelsare discussed. It is shown that in the stationary configuration, all sites are occupied.