فهرست مطالب

  • Volume:14 Issue:3, 2018
  • تاریخ انتشار: 1397/07/02
  • تعداد عناوین: 6
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  • S. Basirjafari* Pages 177-185
    In this paper, numerical results obtained and explained from an exact formula in relation to sound pressure load due to the presence of liquid inside the finite-length non-rigid carbon nanotubes (CNTs), which is coupled with the dynamic equations of motion for the CNT. To demonstrate the accuracy of this work, the obtained formula has been compared to what has been used by other researchers. For this purpose, the solution of the modified complex Helmholtz equation was derived by considering the non-rigidity of the CNT and the wave reflections at the open ends of the CNT for three different liquids with or without considering the relaxation time. The results showed that neglecting the non-rigidity of CNT would cause a decrease on the pressure fluctuations and the pressure associated with the viscosity force of the liquid in the liquid-filled CNT, at both axi-symmetric, and asymmetric cases. Also, it is showed that the viscous liquid in a CNT is a dispersive medium for sound wave propagation and ignoring the energy loss in the liquid in the high frequency analysis and ignoring the non-rigidity of the CNT would cause errors in the prediction of the sound pressure load exerted on the finite-length liquid-filled CNT
    Keywords: Finite, length liquid, filled CNT, Viscosity force, Modified complex Helmholtz equation, Non, rigidity, Sound pressure load
  • T. Bhunia* Pages 187-195
    High strength and elastic biodegradable membranes are of great demand in modern technology. Similar membranes have been developed by irradiating different weight poly (vinyl alcohol) (PVA) – hydroxypropyl guar gum (HPG) blends and followed by combining with ex situ nanosilica. Polarized light microscopic (PLM) study indicates that electron beam irradiation produced crosslinks and developed crystallinity in PVA-HPG matrix. Atomic force microscopic analysis shows that 1 wt.% nanosilica produced finer dispersion in both high and low molecular weight PVA-HPG matrix resulting nearly 4.5 times higher mechanical strength and controlled swelling-deswelling property e.g., low molecular weight PVA with 1wt% nanosilica content show swelling ratio 3.5. Greater nanosilica and PVA-HPG interaction was observed in low molecular PVA-HPG composite membranes than high molecular weight PVA-HPG composite membranes which finally showed better efficacy towards drug retention and elution under physiological condition
    Keywords: Polymer, Irradiation, Membrane, Nanosilica, drug delivery
  • S. Jafarirad*, M. Kordi, M. Kosari-Nasab Pages 197-206
    The use of plant extract in the biosynthesis of nanoparticles (NPs) can be an eco-friendly approach and have been suggested as a possible alternative to classic methods namely physical and chemical procedures. This study was designed to examine the structural chemistry of silver nanoparticles (AgNPs) using both conventional heating and microwave irradiation methods.To our knowledge, this is the first report that proposes a structural chemistry during synthesis of biogenic silver nanoparticles using Artemisia fragrans extracts. The as-synthesized AgNPs by both approaches were characterized using UV-vis, FTIR, XRD, SEM, EDX, DLS with zeta potential analysis and antioxidant activity. Characterization data revealed that AgNPs produced by microwave irradiation (900 W) and conventional heating (100ºC) have average size of 18.06 (zeta potential, -46) and 60.08 nm (zeta potential, -39), respectively. The synthesis of such biogenic AgNPs using eco-friendly reagents in minimum time open the road for decreasing cytotoxicity of the AgNPs without risking interference of toxic chemical agents. In addition, this eco-friendly synthesis with green approach is a new, cheap, and convenient technique suitable for both commercial production and health related applications of AgNPs
    Keywords: Nanoparticles, Structural chemistry, Synthesis, Bio, nano structure
  • S. Sahmani *, M. Mohammadi Aghdam Pages 207-227
    The main purpose of the present investigation is to analyze more comprehensively the size-dependent nonlinear free vibration response of multilayer functionally graded graphene platelet-reinforced composite (GPLRC) nanobeams. As a consequence, both of the hardening stiffness and softening stiffness of size effect are taken into consideration by implementation of the nonlocal strain gradient elasticity theory within the framework of the third-order shear deformation beam theory. The graphene platelet (GPL) nanofillers are dispersed uniformly or in accordance with three different functionally graded patterns based on a layerwise change of their weight fraction through the individual layers. Halpin-Tsai micromechanical scheme is utilized to estimate the effective material properties of multilayer functionally graded GPLRC nanobeams. With the aid of the Hamilton's principle, the non-classical governing differential equations of motion are derived. After that, an improved perturbation technique in conjunction with the Galerkin method is employed to achieve an explicit analytical solution for nonlocal strain gradient nonlinear frequency of multilayer functionally graded GPLRC nanobeams. It is indicated that at zero vibration amplitude, the pattern of GPL dispersion has no influence on the significance of the size dependencies. However, by taking the large vibration amplitude into account, both of the nonlocality and strain gradient size effects on the nonlinear frequency of O-GPLRC and X-GPLRC nanobeams are minimum and maximum, respectively
    Keywords: Nanostructures, Nanocomposites, Nonlinear dynamics, Graphene nanoplatelet, Nonlocal strain gradient elasticity
  • P. Saberi, E. Kashi* Pages 229-239
    Nowadays, in addition to materials and components of asphalt mixtures that are bitumen, aggregates and mineral fillers, other materials known as additives or modifiers are also used. These compounds include wide range of organic, inorganic, industrial, and natural materials used in order to reduce deficiencies, to improve the physical properties and to modify some mechanical properties of bitumen and asphalt mixtures. In the present study, the effect of the oxide shell of hot rolled steel with different percentages of bitumen 70- 60 was investigated by tests of penetration, softening point, kinematic viscosity, and elasticity property. RTFO was performed to determine the viscosity and penetration degree after aging modeling. According to the percentages of additives used in the test (3%, 4% and 5%), results indicate that use of oxide shell increases viscosity, reduces the penetration degree, reduces gum plasticity of bitumen, increases softening point, and improves aging properties in bitumen samples prepared by one of wastes produced by steel factories
    Keywords: Asphalt additives, Oxide shell, Bitumen properties, Aging, Viscosity
  • R. Shabani*, Z. Lakhaiy Rizi, R. Moosavi Pages 241-249
    Significant effects of magnetic iron oxide (Fe3O4) nanoparticles on the potentiometric behavior of carbon paste electrode for bio determination of Isoniazid aromatic drug (INH) were studied. The electrochemical performance of modified Fe3O4/CPE was investigated. The constructed Fe3O4/CPE showed high precision, sensitivity and selectivity, for successfully determination of ultra-trace concentration of INH samples. In this research, pH effects, optimal condition for electrode and interfering Ions, on electrode response were investigated. The best potential response for Fe3O4/CPE was obtained with electrode composition of 0.012 g magnetic NPs, 0.006 g silicon oil and 0.060 g graphite powder at pH 6.5 and showed such a low detection limit as 3.09×10−13 mol L−1 INH
    Keywords: Isoniazid, magnetic nanoparticles, Fe3O4, CPE, Potentiometric sensor