فهرست مطالب

Nanoscience and Nanotechnology - Volume:10 Issue:1, 2014
  • Volume:10 Issue:1, 2014
  • تاریخ انتشار: 1392/12/18
  • تعداد عناوین: 7
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  • M. H. Korayem*, R. N. Hefzabad Hefzabad, M. Taheri, Z. Mahmoodi Pages 1-12
    The theory of contact mechanics deals with stresses and deformations which arise when the surfaces of two solid bodies are brought into contact. In elastic deformation contact occurs over a finite area. A regular method for determining the dimensions of this area is Hertz Contact Model. Appearance of atomic force microscope results in introduction of Contact Mechanics into biology. Low elasticity modulus of biologic particles, causes large deformation against foreign forces, therefore to understand them, studying their behavior is essential. Here, in studying these particles we have used finite element which is a new tool in biology. In this paper indentation of three prostate cancer cells CL-1, CL-2 and LNCaP which have low elasticity modulus and are considered ductile materials was conducted using Hertz contact mechanics model. For modeling, in this section the contact equations of two spheres were used and simulated by using finite element method (FEM). The results of these two steps were compared with available experimental data on these cells to verify simulations and results. These results include force-displacement diagram which shows particles behavior against foreign load. In this presentation we tried to study the behavior of these cells through different methods and make a comparison. Using finite element approach in studying characteristics of these particles was new.
    Keywords: Nano, manipulation, Hertz contact mechanics model, Cancer cell, FE
  • A. Eliassi, M. Ranjbar Pages 13-26
    In this study, preparation of nano-sized gamma alumina with high specific surface area and high yield by thereaction between aluminum nitrate and sodium carbonate, without using any surfactant is reported. Bohemite (Aluminum oxyhydroxide) was prepared as a precursor by strict control of pH and reaction temperature. The gel produced was purified by washing followed by centrifugation. The specific thermal program was applied for calcination. This resulted in a leaf flower shaped gamma alumina in 91% yield, with 413 m2/g specific surface area and average pore volume 1.624 cm3/g. The flower like micro sheets of gamma alumina contained spherical particles with an average size of about 38 nanometers. Elemental analysis and FTIR spectra showed that sodium and carbonate ion impurities were completely removed from the prepared gamma alumina. X-ray diffraction pattern and TG/DTA analysis confirmed that bohemite and gamma alumina phase were formed. XRD, SEM and BET data of synthesized catalyst were compared with commercial catalyst. Dehydration of methanol was conducted by the synthesized gamma alumina. The catalyst evaluations were performed at different temperatures and different weights hourly space velocities. The commercial catalyst and the synthesized catalyst were compared in this work and the results showed that the performance of nanosized catalyst was better than the commercial one.
    Keywords: Nano sized, gamma alumina, Catalyst, DME, Methanol
  • F. Pourfayaz, Sh. Boroun, J. Babaei, B. Ebrahimi Hoseinzadeh Pages 27-34
    In order to evaluate the adsorption potential of multi-walled carbon nanotubes (MWCNTs) for benzene, toluene and xylenes (BTX), the adsorption capacities of benzene and toluene on two different MWCNTs were measured using a gas-chromatography (GC) and then compared with each other. Fourier transform infrared (FTIR) was employed to investigate the presence of functional groups on the carbon nanotubes surface. The MWCNTs were also characterized by Raman spectroscopy and scanning electron microscopy (SEM) techniques and their specific surface areas were determined using the Brunauer–Emmett–Teller (BET) method. FTIR spectra proved the presence of functional groups on the surface of both two different MWCNTs. Generally, the results revealed that the MWCNTs with larger specific surface area and higher crystallinity have higher adsorption capacities for both benzene and toluene. Moreover, as compared with conventional adsorbents like the activated carbon, the carbon nanotubes have the advantages such as selectivity to aromatic volatile organic compounds such as BTX.
    Keywords: Removal of BTX, MWCNTs, Nano, adsorbent, Adsorption capacity, Specific surface area
  • Z. Eslamifar Pages 35-44
    α-Amylase has been studied extensively from various sides. This enzyme is used in many industries. Many applications of this enzyme have encouraged us for greater attempts on the study of α-amylase and to search for more effective processes. In this investigation, the structure of nanotube - catalytic site of bacillus subtilis α- amylase was optimized by hyperchem 7.0 and then it was investigated with ab initio/hartree fock and density functional theory /B3LYP methods using the STO-3G, 3-21G and 6-31G basis sets for a physicochemical explanation of interactions within these nano biosystem. Then nuclear Magnetic Resonance (NMR) parameters and so charge, dipole moment, and stability energy were calculated on the optimized structure. We have found each of active atoms that indeed play an important role in imparting extra stability. In the current study, we have reported the NMR parameters of 8 atoms of catalytic site of bacillus subtilis alpha-amylasethe. Interesting finding of the present study is that in NMR shielding for each of active atoms, O8 and O14 had maximal shift in all of levels. In catalytic mechanism of this enzyme, O14 is adopting a chair structure leading to the easy cleavage of the glucoside bond (fixer for catalysis). This investigation suggests that nanotube interactions in this nano biosystems indeed play an important role in imparting extra stability of the catalytic site of the enzyme. Energy parameters in B3LYP level in different basis sets have more negative values than HF and have indicated the most stability in B3LYP6-31/G level and so dipole moment in this structure have observed that in HF3-21/G is maximum. The aim of this work was to discuss the aspects of the electronic structure of this nano biosystem to increase their advantages in practical applications.
    Keywords: Nanotube, catalytic site, Bacillus subtilis α, amylase, AB initio, DFT, NMR shielding, GIAO, CSGT, HF, B3LYP
  • M. Khorasani-Motlagh, H. Vahidi, M. Noroozifar Pages 45-54
    The perovskite-type oxides strontium-substituted lanthanum nickelate (LSNO) were prepared by a coprecipitation method in the present of octanoic acid as surfactant. The phase composition, morphology,lattice parameters and size of nanoparticles in these materials were characterized through Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) on the resultant powders at room temperature. This method produced oxides withnanoparticles following the orthorhombically distorted crystal structure. The LSNO were synthesized in homogeneous nanosize particles of about 53 nm.
    Keywords: Perovskite, type, Nanoparticles, Co, precipitation, Surfactant, XRD, SEM, EDX
  • M. Azadmand, K. Arzani, A. Nemati, N. Riahi Noori, T. Ebadzadeh Pages 51-60
    In this research the influence of adding SiC on microstructure and electrical properties of ZnO-based Nanocomposite varistors were investigated. SiC was added with amounts of 10-0 mass% to ZnO-based varistor composition. It is found that SiC allows reaching to high threshold voltage with formation of fine-grained ZnO.Another important effect of adding SiC is formation Zn2SiO4 (Willemite) on the surface of SiC grains. With this effects SiC had great influence on Varistor electrical properties. On the other hand relative density decreased with increasing percentage of SiC in the composition. Hence with adding SiC to the composition, the threshold voltage of varistors (VT) and non-linear coefficient (α) increased at first and then decreased with increaseing of porosity. Also Current leakage decreased at first and then increased with adding more SiC. Also ZnO powder size effect on the final properties was examined in this reasearch by using submicron size and Nano size ZnO powder. The best achieved electrical result was threshold voltage as large as 4220 V/cm and nonlinear coefficient α=44 that were gained by using of Nano ZnO powder and adding %4 SiC to the composition.
    Keywords: Electrical properties, Grain growth, Nanocomposite, SiC, Varistor, ZnO
  • S. Rahmani, M. Mahmoudifard, M. Safi Pages 61-66
    Ultraviolet waves, because of their short wavelength, have a high energy and considerable damaging effects on surfaces. Protection against ultraviolet radiations is one of the finishing treatments done on surfaces exposed to sunlight. The importance of this issue in relation to human health, due to complications such as skin burns and cancer, is doubled. Up to now, different materials such as zinc oxide, titanium oxide and Aluminum oxide nano-particles have been introduced as the ultraviolet absorbents. In this paper, the absorption of singlewalled carbon nano-tubes (SWCNTs) and multi-walled carbon nano-tubes (MWCNTs) was investigated and compared with common chemical absorbent materials. The results showed that carbon nano-tubes (CNTs),similar to other absorbents, have a specific absorption in this area. In addition, it was observed that the absorption of SWCNTs is comparable with other absorbents, and CNTs could be introduced as good substitutesfor ultraviolet absorbents in various applications.
    Keywords: Nano, particles, Single, walled carbon nano, tubes, Multi, walled carbon nano, tubes, Ultraviolet radiation, Absorption