فهرست مطالب

  • Volume:10 Issue:2, 2014
  • تاریخ انتشار: 1393/02/24
  • تعداد عناوین: 7
|
  • E. Esmaeili*, A. M. Rashidi, Kh. Jafari-Jozani Pages 67-78
    In the present study, PtRuCe/MWNTs nanocatalysts synthesized via polyol process technique are applied as anode electro-catalyst in methanol electro-oxidation reaction (MOR). To characterize the nanocatalysts, TEM, XRD, EDS and XPS are investigated. Cyclic voltammetry and choronoamperometry are used to evaluate the electro-catalytic activity and stability of the catalysts in methanol electro-oxidation, respectively. Further addition of the Ce promoter to MWNTs-supported PtRu nanocatalyst shows the highest activity and the lowest onset potential in MOR at Ce to Pt molar ratio of 0.7. A significant enhancement of the forward anodic peak in cyclic voltammetry experiments is observed for the Ce-promoted PtRu catalyst with cerium to platinum molar ratio of 0.7, i.e. 349 mA/cm2.mgPt, in comparison with 182 mA/cm2.mgPt and 251 mA/cm2.mgPt, respectively, corresponding to Pt/MWNTs and PtRu(1:1)/MWNTs nanocatalysts. Furthermore, the chronoamperommetry results present a remarkable improvement in the final current density of PtRuCe/MWNTs (6.1 mA/cm2), compared to the un-promoted catalysts, having a decreasing propensity, i.e. PtRu/MWNTs (3.7 mA/cm2) and Pt/MWNTs (2.05 mA/cm2.mgcat). The improved performance of PtRuCe/MWNTs may be attributed to the formation of highly-dispersed Pt nanoparticles on the support, followed by a significant enhancement of bifunctional mechanism, as a result of cerium incorporation.
    Keywords: Multi, walled carbon nanotubes, Bi, functional mechanism, Fuel cells, Methanol electrooxidation
  • S. Olyaee*, Z. Dashtban Pages 79-96
    The drawing of frequency-path (F-P) models of optical beams is an approach for nonlinearity analysis in nano-metrology systems and sensors based on the laser interferometers. In this paper, the frequency-path models of four nano-metrology laser interferometry systems are designed, analyzed and simulated, including conventional and modified two- and three-longitudinal-mode laser interferometers. The frequency-path model can be used for nonlinearity error analysis resulting from imperfect alignment of optical head and non-ideal laser polarization states. The number of active F-P element in these systems is calculated by multiplying the number of frequency and paths. The number of active F-P elements for conventional and modified two-mode laser interferometer is 4, and this is 6 for conventional and modified three-mode laser interferometer. The output interference terms can be calculated from the active F-P elements which is 10 for conventional and modified two-mode interferometer and is 21 for conventional and modified three-mode one. The interference terms include optical power, ac interference, dc interference, and ac reference. These terms are also investigated in zero (fixed target), low (2mm/s), and high (20mm/s) target velocities using frequency spectrum of photocurrents.
    Keywords: Frequency, path model, Interference terms, Heterodyne interferometer, Nano, metrology, Frequency spectrum
  • P. Parsia*, M. Khaleghi, M. Madani Pages 97-102
    Today, rocky monuments are being exposed to different physical, chemical and biological factors and therefore going to be ruined. One of physical destructive factors is growing of fungus and lichens on the rocks. This research aims to make use of silver nano-particles produced through microbial method in order to prevent growth and progression of fungus detached from rocky surfaces in Meymand historic village. In the first step, some parts of destructed rocky surfaces and grown lichens on rocky monuments in the village were taken as samples and transferred to lab. After isolation of the fungus from the samples, Identification of all samples were done to the genus level by means of conventional mycological methods, morphology on YGC medium and study of microscopic by means of slide culture. Then the effect of silver nano-particles produced by Pseudomonas sp1 on the fungal isolations was studied. Based on what observed, it was proved that nanoparticles produced by Pseudomonas sp1 affected about 68.42% on fungal isolations screened from Meymand rocky and historic village and hindered their growth; therefore growth of fungus on historic rocky surfaces can be prevented by means of such particles in order to protect cultural heritages of the society.
    Keywords: Antifungal effect, Meymand historic village, Silver nano, particles
  • A. Zamzamian* Pages 103-110
    fluids for various industrial applications because of their excellent thermal performance. This study analytically and experimentally examines the effects of nanoparticle dispersion on the entropy generation of EG–Al2O3 nanofluid flows through a helical pipe as a heat exchanger under constant wall heat flux thermal boundary condition in laminar regime. It is found that adding nanoparticles improves the thermal performance of EG–Al2O3 flow with Re numbers less than 3700. On the other hand the results shows that adding the 5% by volume Al2O3 nanoparticles in the EG in Dean numbers less than 100 can decrease the entropy generation by 4.511%. Also it is shown that adding nanoparticles leads to increase entropy generation in the cases that fluid flow (pressure drop) irreversibility is dominant. Moreover, optimum conditions of radius ratio and Dean Numberfor laminar nanofluid flow are obtained
    Keywords: Thermodynamic optimization, Nanofluid, Helical coil, Entropy generation, Laminar flow
  • M. Yeganeh*, M. Saremi Pages 111-116
    The idea of smart corrosion inhibition is basis on either inhibitor consumption where it is needed or reducing harmful matrix interaction with it. In addition, applying corrosion inhibitor in a coating causes many problems such as loss of inhibition capability, coating degradation, or both. A useful technique to overcome this problem is applying of inert host systems of nanometer dimensions as nanocontainers, which is loaded by corrosion inhibitors. In this research, Mesoporous silica nanocontainer powders were applied as corrosion inhibitor hosts. Then, these powders were dispersed in the polypyrrole matrix and the release and protection properties of these composite coatings with and without inhibitor were studied in 0.03 M NaCl. Results showed that in higher pHs and chloride media, the release content of corrosion inhibitor is higher. The substrates were protected in the presence of corrosion inhibitor release from mesoporous silica in the chloride media comparedto the coatings without inhibitor
    Keywords: Mesoporous silica, Corrosion inhibitor, Polypyrrole, EIS
  • M. Kianpour, R. Sabbaghi-Nadooshan* Pages 117-126
    Application of quantum-dot is a promising technology for implementing digital systems at nano-scale. Quantum-dot Cellular Automata (QCA) is a system with low power consumption and a potentially high density and regularity. Also, QCA supports the new devices with nanotechnology architecture. This technique works based on electron interactions inside quantum-dots leading to emergence of quantum features and decreasing the problem of future integrated circuits in terms of size. In this paper, we will successfully design, implement and simulate a new 2-input and 3-input XOR gate (exclusive OR gate) based on QCA with the minimum delay, area and complexities. Then, we will use XOR gates presented in this paper, in 2-bit, 4-bit and 8-bit controllable inverter in QCA. Being potentially pipeline, the QCA technology calculates with the maximum operating speed. We can use this controllable inverter in the n-bit adder/subtractor and reversible gate.
    Keywords: Exclusive OR(XOR) gate, Inverter, Majority gate, Quantum, dot Cellular Automata(QCA)
  • S. Shams*, Sh. Pourseyedi, H. Hashemipour Rafsanjani Pages 127-132
    Nano world daily. In this paper the Lens culinaris seed extract was assessed for thegreen synthesis of silvernanoparticlesat temperature of 25◦C. The nanoparticles were characterized using Inductively CoupledPlasma spectrometry (ICP), X-ray diffraction (XRD) and Transmission electron microscopy (TEM). Thenthe antimicrobial activities of these nanoparticles were investigated. P. aeruginosa and S aureus were used as representatives of Gram-negative and Gram-positive bacteria, respectively. Percentage conversion of metal ion to metal nanoparticles were more than 95% after 60 days of the reaction. XRD was used to confirm the crystalline nature of the particles. Silver nanoparticles were mostly spherical with range in size from 5-25 nm. Ag nanoparticles synthesized with extract were exhibited a strong antibacterial activity against bothP.aeruginosa and S.aureus.This process is completely green and eco-friendly compatible.
    Keywords: Silver nanoparticles, ICP, TEM, XRD, Antimicrobial