فهرست مطالب

  • Volume:3 Issue:2, 2009
  • تاریخ انتشار: 1388/06/11
  • تعداد عناوین: 9
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  • Dorranian, Golian, Shahbaz Tahmasebi, Rashidian Page 6
    Nonlinear optical properties of yellow disperse 211 doped polymethyl-methacrylate (PMMA) solution in acetone is studied experimentally employing different optical techniques. The effects of thickness of sample as well as its concentration effects are investigated in detail. Experiments are performed using the second harmonic of a continuous Nd-Yag laser beam at 532 nm wavelength and 20 mW power. The effect of nonlinear refractive index of liquid films is obtained by measuring the profile of propagated beam through the samples and their nonlinear refractive index is found to be negative. The optical limiting behavior of samples is investigated by measuring the samples transmission.The third order nonlinearity χ3 is measured using Z-scan data. The nonlinear absorption coefficient is calculated using open aperture Z-scan data while its nonlinear refractive index is measured using the closed aperture Zscan data. Real and imaginary parts of the third-order nonlinear optical susceptibility χ3 are changed significantly with thickness and concentration.
  • Bahar, Majd, Abdi Page 12
    In this study the effects of different intensities of AC (2.7 mT and 3.5 mT) and DC (3.7 mT and 4.5 mT) magnetic fields and exposure times (30, 60 and 90 min) on germination and primary growth of lentil seeds have been investigated. The treated and untreated seeds were cultivated under an identical condition of the water-bedded Petridishin a temperature, lighting and relative humidity. Growth indices were measured every day at the same time for a week. It was found that the magnetic fields have no effect on the percentage of germination rates of the treated lentil seeds compared with that of the untreated seeds. The length of roots were increased about 16-31 % in ACmagnetic field intensities of 2.7 mT and 3.5 mT and 10-13 % in DC magnetic field intensities of 3.7 mT and 4.5 mT different in exposure times compared with controls. The stem’s length were increased about 29-35 % in 2.7 mT and decreased about 3-15 %, in higher intensities of 3.5 mT, 3.7 mT and 4.5 mT compared with controls. According to the results, magnetic fields can affect the early growth of lentil seeds and these effects are altered with different intensities and times of exposure.
  • Motaghi, Shahidi, Wiener Page 17
    In this paper, the effect of low temperature plasma treatment on the natural dyeing properties of wool is studied.Madder was used as a natural dye and copper sulfate (CuSO4) and ferrous sulfate (FeSO4) as a metal mordant. Iron and copper were used as an electrode, in DC Magnetron Plasma Sputtering System. For natural dyeing, first some of wool samples were treated with mentioned mordant, and some of them were sputtered with Copper and Iron metal particles, using plasma sputtering treatment. Then all of the wool samples were dyed with madder. The color strength of plasma treated and untreated samples were analyzed using reflective spectrophotometer. Washing and light fastness were investigated and the results show that, the color strength and fastness of dyed wool samples are improved after plasma treatment. As a result, it can be concluded that the low temperature plasma treatment could improve the natural dyeing on wool. So it is a good candidate to substitute with mordant treatment.
  • Golnabi, Matloob, Bahar, Sharifian Page 24
    In this study one of the most important physical parameters identifying conductance of liquid solutions is investigated.Electrical conductivities of pure, distilled, municipal, industrial and river water liquids along with those of different electrolyte solutions are computed at room temperature (25 °C). Obtained results for ultra pure, pure distilled, municipal, industrial, well and river water liquids with different impurities are compared at such a given temperature.A similar study is performed for different electrolytes and related results. In addition electrical conductivity of water liquid is compared with that of a typical NaCl electrolyte solution and interesting results for differences in conductance values are discussed.
  • Yousefi, Kamaluddin, Kavosh Page 29
    ZnO nanowires are fabricated on p-type silicon substrates without using a catalyst. A simple horizontal doubletube system along with chemical vapor diffusion of the precursor, based on Fick''s first law, is used to grow the ZnO nanowires. The substrates were placed in different temperature zones, and ZnO nanowires with different diameters were obtained. In addition to the nanowires, ZnO nanodiscs with different diameters were obtained on another substrate, which was placed at a lower temperature than the other substrates. The electrical property of the ZnO nanowires and nanodiscs are characterized by a simple DC circuit.
  • Eshraghi, Cho, Mok Kim, Sasada Page 33
    Measurements of the high frequency electromagnetic interference (EMI) of a pulse tube cryocooler are made in a typical laboratory environment using laboratory-made current transformers. The inverter makes high frequency EMI which could cause severe interference with SQUID operation inside the Pulse Tube cryocooler. By coveringthe power lines, which include a neutral line, of the valve motor with a copper mesh cover, as a ground line, one order decrease in the magnitude of the EMI noise is successfully obtained. This paper describes one example to show how to observe and reduce conducted high frequency noise currents in a precision experimental system.
  • Kouhi, Yaghobi Page 37
    The lithium atom effect on the optical and structural properties of the Li@C60 molecule are investigated using PPP (Pariser-Parr-Pople) and SSH (Su-Schrieffer-Heeger) models. In addition the movement of lithium atom effect on mentioned properties of Li@C60 is calculated using the HF-CI-SOS (Sum-Over-State) and SSH methods. Our calculationsindicated that the Na atom effect on the (first) polarizability and the bonds length of C60 is dramatic. This study proposes such a novel way to synthesize and design new NLO materials by using the alkali atom
  • Ghorannevis, Kato, Kaneko, Hatakeyama Page 42
    This paper describes experimental research on synthesis of single walled carbon nanotubes (SWNTs) from nonmagnetic catalysts with plasma chemical vapor deposition (PCVD). Nonmagnetic metal particles were found to have catalytic activity for the growth of SWNTs under a specific plasma condition. An actinometry method based on optical emission spectroscopy (OES) measurements was also used to determine the molar fraction of monoatomic hydrogen and carbon species produced in plasma. We found that Methane conversion is remarkably promoted using plasma which enhances growth of SWNTs over nonmagnetic catalysts. It is well known that metals such as Au, Ag,and Pt have low adsorption and dissociation for catalytic reactions. Hence external forces such as methanehydrogen discharge is required for high dissociation of hydrocarbons. Plasma–catalyst reaction system is able to generate desired reactants for SWNTs growth from nonmagnetic catalysts.