فهرست مطالب

  • Volume:10 Issue:3, 2014
  • تاریخ انتشار: 1393/07/14
  • تعداد عناوین: 7
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  • A. H. Korayem, A. K. Hoshiar, N. N. Ashtiani, M. H. Korayem* Pages 133-144
    With the rise in the use of AFM (Atomic Force Microscope), we have witnessed a growing use of atomic microscope based nanorobots in the precise displacement of various particles. There are certain limitations to the application of nanorobots in the moving of nanoparticles. One of the most important of these limitations is the lack of an appropriate image feedback concurrent with the displacing process; thus, the design of a graphical interface is essential in this regard. In this paper, the displacement of a cylindrical nanoparticle in a straight path, and in the air medium, has been simulated by means of a virtual reality graphical interface. This simulation is actually aimed at eliminating the previously stated limitation through the use of a graphical interface. The procedure has been presented in seven stages and the relevant diagrams of each stage have been extracted. Then, the obtained diagrams have been interpreted and discussed. In the end, by using the experimental results and the existing simulations for spherical particles, the presented results have been validated.
    Keywords: Nanoparticles displacement process, Cylindrical nanoparticles, AFM nanorobot, Virtual reality
  • V. Jafari, A. Allahverdi* Pages 145-152
    Colloidal nanosilica is currently being produced by various methods which are mainly high energy intensive and/or not environmentally friendly. It is therefore essential to develop new energy efficient and environmentally friendly technologies. This paper introduces a new ultrasound assisted route based on alkali leaching of silica fume for synthesis of colloidal silica nanoparticles. The effects of sonication time on the particle size distribution of the colloidalnanosilica are studied via dynamic light scattering (DLS). The results show that the shape and size of nanoparticles are strongly depended on the ultrasonic time. DLS results show that average diameter of the produced colloidal nanosilicadecreases sharply from 337.10 nm to 93.27 nm during the first 5 minutes of sonication. Continued sonication up to 30 minutes, however, shows relatively slight decrease in average diameter of the colloidal nanosilica. Further, the produced colloidal nanosilica is characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometry (XRD) and Fourier transform infrared (FTIR) spectroscopy.
    Keywords: Nanoparticles, Nanosilica, Colloid, Silica fume, Ultrasound
  • M. A. Safi, A. Ghozatloo*, A. A. Hamidi, M. Shariaty, Niassar Pages 153-162
    The objective of the present study is the synthesis of MWCNT-TiO2 hybrid nanostructures by solvothermal synthesis method with TiCl4 as precursor. The heat transfer enhancement due to the use of MWCNT-TiO2 nanofluid was investigated. As-prepared hybrid materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that MWCNTs were uniformly decorated with anatase nanocrystals. The heat transfer performance of the plate heat exchanger (PHE) was investigated using MWCNT-TiO2 nanofluid at various volume flow rates, a wide range of concentrations and inlet temperatures. The performance is discussed in terms of heat transfer coefficient ratio. The results showed that the heat transfer coefficient of the nanofluid was more than that of the base fluid (Distilled Water). The heat transfer coefficient was enhanced with increasing the nanofluid concentration from 0.02 to 0.08 wt.% and volume flow rate from 2 to 3.5 LPM. Conversely, the heat transfer coefficient decreased with increasing the nanofluid inlet temperature from 36 to 60oC.
    Keywords: Nanofluids, Plate heat exchanger, Heat transfer, Hybrid
  • H. Tashakori, B. Khoshnevisan, F. Kanjouri*, Z. S. Naghavi Pages 163-170
    In this paper, we have used density functional perturbation theory (DFPT) and Pseudo-potential method to calculate the phonon spectrum, phonon density of states (DOS), specific heat capacity and mechanical properties of (5,5) armchair and (9,0) zigzag Single Wall Carbon Nanotubes (SWCNTs). Our calculations show that Young’s modulusfor (5,5) and (9,0) nanotubesare higher than 1TPa. We have also shown that the value of compressive Young’s modulus for (5,5) nanotube isgreater thanthat for (9,0) nanotube while thevalue of tensile Young’s modulus for (9,0) nanotubeisgreater than that for(5,5) nanotube. The result of our calculations shows that thespecific heat capacity of (5,5) and (9,0) nanotubes coincides, therefore we may conclude that thespecific heat capacity of nanotubes is independent of their chirality. Furthermore we have found that the atoms in the armchair nanotubes are positioned as close as possible in the direction of the nanotube axis, therefore they could have more resistant against compressive pressure
    Keywords: Single, walled carbon nanotubes, Mechanical properties, Young's modulus
  • S. Abbasian, M. Taghizadeh* Pages 171-180
    H-ZSM-5 nano-zeolites were synthesized by hydrothermal method using tetrapropylammonium hydroxide (TPAOH) as a template in the presence of various TPABr concentrations. The effect of different TPABr/TPAOH molar ratios was studied on the catalytic performance of dehydration of methanol to dimethyl ether (DME) in a fixed bed reactor under the same operating conditions (T=300°C, P=1 atm, and WHSV=26 h−1). The prepared catalysts were characterized by XRD, SEM, BET and NH3-TPD. The characterization results showedthat the crystal sizes of the catalysts enlarge by increasing the concentration of TPABrin the synthesis reaction mixture. It was observed that H-form zeolite catalysts were active and selective for DME synthesis. These catalysts showed a high methanol conversion and also very high DME selectivity. It was found that by addition of up to 10 mole% TPABr in the synthesis reaction mixture, no significant effect was observed on the physical and chemical properties and catalytic activity of prepared catalysts.
    Keywords: Methanol dehydration, Dimethyl ether (DME), H, ZSM, 5 nano, zeolite, Hydrothermal method, Mixed template
  • S. Shams*, Sh. Pourseyedi, H. Hashemipour Rafsanjani Pages 181-186
    Silver nano-particles have different biological applications due to their compatibility. Chemical methods usually result in remaining some amounts of toxic reactions on the nano-particles. For this reason, the use of plants as sustainable and accessible resources in preparation of compatible nano particles has attracted a lot of attention in the recent years. This research investigated the green synthesis of Silver nano-particles using Meliaazedarach plants.The analysis of Ultraviolet–visible spectroscopyshowed the green synthesis of nanoparticles in plants. X-ray diffraction was used to confirm the crystalline nature of the particles. Fouriertransform infrared spectroscopyspectroscopywas performed to analyzethe functional groupin the process of green synthesis, the role of different functional groups such as hydroxyl, amine and alkyl groups were indicated in the synthetic process.Then, proteinscapped on the silver nano-particles were analyzed usingSodium dodecyl sulfate -PAGE. Regarding this, the possibility of extracted protein role in the stabilization of nano-particles requires more analysis.
    Keywords: Green synthesis, Melia azedarach, Silver nano, particles, SDS, PAGE
  • A. A. Saki*, M. Abbasinezhad, A. A. Rafati Pages 187-196
    The 440 fertile eggs, in a completely randomized design were divided into 11 treatments with four replicates and 10 eggs per each replicate. Treatments including: (T1; control; without injection), (2; injected with 0.3 ml saline 9.0%; sham control), (T3, T4 and T5) 25, 75, 125 ppm Fe-Nano, (T6, T7 and 8) 50, 100, 150 ppm Fe-Nano-Alimet chelate, (T9, T10 and T11) 50, 100, 150 ppm Fe-Aliment chelate. On 1 th day of incubation, 0.3 ml solution in ovo was injected into the egg yolk sac. Higher hatchability was found in controls, 25 ppm Fe- Nano, 100 ppm Fe-Nano-Alimet chelate and all levels of Fe-Alimet chelate treatments than other treatments.The egg weight was higher significantly in sham control, 25 and 75 ppm Fe-Nano, all levels of Fe-Nano-Alimet chelate and 150 ppm Fe-Aliment chelate treatments. There was significant increase in chick weight in controls, 25 and 75 ppm Fe-Nano, 100 ppm Fe-Nano-Alimet chelate and 150 ppm Fe-Aliment chelate in comparison with other treatments. Also chick body weight to egg weight ratio in controls, 25ppm Fe Nano and 100ppm Fe- Nano-Alimet chelate was higher than in other treatments. Level of 25 ppm of Fe-Nano has shown the highest relative liver weight. Serum Fe content and liver was higher by using 25 ppm Fe-Nano, 100 ppm Fe-Nano- Alimet chelate and 150 ppm Fe-Aliment chelate than other treatments. By applying two treatments of 100 ppm Fe-Nano-Alimet chelate and 150 ppm Fe-Aliment chelate, chickens blood hemoglobin increased significantly compared with the other treatments. These results suggest that 25 ppm Fe-Nano, 100 ppm Fe-Nano-Alimet chelate and 150 ppm Fe-Alimet chelate improved embryonic growth and development.
    Keywords: Broiler chicken, Chelate, hatchability, In ovo, Iron nanoparticles, Methionine