Afrand M.,Islamic Azad University at Najafabad
Applied Thermal Engineering | Year: 2017
In this paper, an experimental investigation on the effects of hybrid nano-additives, composed of magnesium oxide (MgO) and functionalized multi-walled carbon nanotubes (FMWCNTs), on the thermal conductivity of ethylene glycol (EG) is presented. The experiments performed at temperatures ranging from 25 °C to 50 °C and the solid volume fraction range of 0–0.6%. The measurements revealed that the thermal conductivity of nanofluids significantly enhances with an increase in the percentage of the solid volume fraction. Moreover, the thermal conductivity of EG considerably increased with increasing temperature, while thermal conductivity of hybrid nanofluid slightly enhanced. The thermal conductivity measurements showed that the maximum enhancement of thermal conductivity of nanofluid is 21.3%, which occurred at solid volume fraction of 0.6% and temperature of 25 °C. Finally, efforts were made to provide an accurate correlation for estimating the thermal conductivity at various temperatures and concentrations. Deviation analysis of the thermal conductivity ratio was performed. The comparison between experimental results and correlation outputs showed a good agreement. © 2016 Elsevier Ltd
Heidari A.,Shahrekord University |
Tavakoli D.,Islamic Azad University at Najafabad
Construction and Building Materials | Year: 2013
Waste material recycling through using in concrete manufacturing not only provides a promising resource to produce a high quality concrete, but also helps to properly encounter the problem of waste disposal. It is a good option for use in concrete because waste ground ceramic has a highly resistant structure and cannot be processed by any recycling system and because it is produced in large quantities. Thus, this study focused on two different phases: in the first phase, the use of waste ground ceramic as a pozzolan in concrete was investigated. Concrete samples with 10-40% of ground ceramic powder substitution were made. In the second phase of the study, the simultaneous effect of using 0.5-1% of nano-SiO2 and from 10% to 25% of ground ceramic powder was determined. In all cases, compressive strength and water absorption tests were performed. The results show that adding ground ceramic up to 20% does not have a significantly negative effect on the compressive strength of concrete. Furthermore, using any amount of ground ceramic in the concrete reduces its water absorption capacity. In addition, using nano-SiO2 and pozzolan simultaneously leads to improved compressive strength and a reduced water absorption capacity. Therefore, nano-SiO2 can improve the effects of ground ceramic powder on the properties of concrete. © 2012 Elsevier Ltd. All rights reserved.
Mehrabanian M.,Islamic Azad University at Najafabad
International journal of nanomedicine | Year: 2011
Nanohydroxyapatite (n-HA)/nylon 6,6 composite scaffolds were produced by means of the salt-leaching/solvent casting technique. NaCl with a distinct range size was used with the aim of optimizing the pore network. Composite powders with different n-HA contents (40%, 60%) for scaffold fabrication were synthesized and tested. The composite scaffolds thus obtained were characterized for their microstructure, mechanical stability and strength, and bioactivity. The microstructure of the composite scaffolds possessed a well-developed interconnected porosity with approximate optimal pore size ranging from 200 to 500 μm, ideal for bone regeneration and vascularization. The mechanical properties of the composite scaffolds were evaluated by compressive strength and modulus tests, and the results confirmed their similarity to cortical bone. To characterize bioactivity, the composite scaffolds were immersed in simulated body fluid for different lengths of time and results monitored by scanning electron microscopy and energy dispersive X-ray microanalysis to determine formation of an apatite layer on the scaffold surface.
Jamalian M.,Islamic Azad University at Najafabad
Journal of Magnetism and Magnetic Materials | Year: 2015
The goal of this study was to investigate the structural, magnetic and microwave properties of Sn4+-Tb4+ substituted strontium ferrite with chemical formula of SrFe12-x(SnTb)x/2O19(x=0-2)(in the step of 0.5) nanoparticles prepared by the sol-gel method. In order to study the formation of hexaferrite phase, X-ray diffraction analysis was carried out and it was discovered that a single magnetoplumbite was formed. A field emission scanning microscopy was hired to explore the morphology and particle size of nanopowders. Fourier-transform infrared was employed to confirm different bond modes which were structured. A vibrating-sample magnetometer was used to investigate the magnetic characteristics of the prepared samples. The results showed that with an increase in substitutions, Sn-Tb, magnetization and remanence were increased along with a decrease in coercivity. A vector network analyzer was utilized to scrutinize the microwave properties. The resultant data showed a striking achievement with high reflection loss value and a wide bandwidth in the range of 20-26 GHz. © 2014 Elsevier B.V. All rights reserved.
Karimipour A.,Islamic Azad University at Najafabad
International Journal of Thermal Sciences | Year: 2015
Forced convection heat transfer of water-Ag, water-Cu and water-Al2O3 nanofluid in a microchannel is studied numerically by using lattice Boltzmann method. Temperature of microchannel walls is higher than that of the inlet fluid. Effects of change in nanoparticles volume fraction and slip coefficient are investigated. Slip velocity, temperature jump and velocity and temperature profiles are presented at different cross sections. Moreover, a correlation is developed to predict nanofluid Nusselt number through the microchannel. As a result, higher value of slip coefficient corresponds to less Nusselt number and more slip velocity and temperature jump. © 2015 Elsevier Masson SAS.
Hassanzadeh-Tabrizi S.A.,Islamic Azad University at Najafabad
Advanced Powder Technology | Year: 2012
Cerium-doped yttrium aluminum garnet (YAG:Ce) powder was synthesized by the Pechini method with aluminum nitride, yttrium nitride, citric acid and ethylene glycol as the starting materials. Structure, morphology and luminescence spectra were investigated by using X-ray diffraction, thermogravimetric and differential thermal analysis, scanning electron microscopy, Fourier transform infrared spectroscopy and photoluminescence spectroscopy measurements. The pure YAG phase was formed after heat treatment at 800 °C for 3 h and no intermediate phase was observed. The average size of the particles was about 70 nm. The photoluminescence spectrum of the crystalline YAG:Ce phosphors showed the green-yellow emission with 5d → 4f transition as the most prominent group. The increase of the ethylene glycol:citric acid molar ratio, resulted in a powder with smaller particle size and better luminescence properties. © 2011 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.
Mirdamadi A.,Islamic Azad University at Najafabad
ARYA Atherosclerosis | Year: 2013
BACKGROUND: Several studies have emphasized thrombosis associated with thrombocytopenia as a potentially fatal complication of heparin. A number of agents are used for this condition. As a new oral, reversible direct thrombin inhibitor, dabigatran has been approved for short-term thromboprophylaxis after elective hip and knee replacement surgery. We present a case of dabigatran administration in a patient with femoral fracture. CASE REPORT: A 67-year-old woman referred to the orthopedic ward of Shariati Hospital (Isfahan, Iran) due to femoral fracture following an accident. Immediately after surgery, she was found to be suffering from deep vein thrombosis (DVT) in her lower extremity despite sufficient prophylaxis by enoxaparin. Laboratory data showed severe thrombocytopenia. Considering the clinical history, an initial diagnosis of heparin-induced thrombocytopenia was made. Doppler ultrasound confirmed the diagnosis. Heparin was thus replaced with dabigatran which increased platelet count to the normal range and improved DVT. CONCLUSION: Dabigatran can be a life-saving treatment in heparin-induced thrombocytopenia. However, it is contraindicated in patients with renal dysfunction since it may cause potentially catastrophic results.
Buchheit M.,Aspire Academy for Sports Excellence |
Rabbani A.,Islamic Azad University at Najafabad
International Journal of Sports Physiology and Performance | Year: 2014
The aim of the current study was to examine the relationship between performance of the Yo-Yo Intermittent Recovery Test Level 1 (Yo-YoIR1) and the 30-15 Intermittent Fitness Test (30-15IFT) and to compare the sensitivity of both tests to training. Fourteen young soccer players performed both tests before and after an 8-wk training intervention, which included 6 sessions/wk: 2 resistance training sessions, 2 high-intensity interval training sessions after technical training (4 sets of 3:30 min of generic running and small-sided games [4v4] during the first and second 4-wk periods, respectively [90-95% maximal HR], interspersed with 3 min at 60-70% maximal HR), and 2 tactical-only training sessions. There was a large correlation between 30-15IFT and Yo-YoIR1 (r = .75, 90% confidence limits [CL] 0.57;0.86). While within-test percentage changes suggested a greater sensitivity to training for the Yo-YoIR1 (+35%, 90%CL 24;45) than for the 30-15IFT (+7%; 4;10), these changes were similarly rated as almost certain (with chances for greater/similar/lower values after training of 100/0/0 for both tests) and moderate, ie, standardized difference, ES = +1.2 90%CL (0.9;1.5) for Yo-YoIR1 and ES = +1.1 (0.7;1.5) for 30-15IFT. The difference in the change between the 2 tests was clearly trivial (0/100/0, ES = -0.1, 90%CL -0.1;-0.1). Both tests might evaluate slightly different physical capacities, but their sensitivity to training is almost certainly similar. These results also highlight the importance of using standardized differences instead of percentage changes in performance to assess the actual training effect of an intervention. © 2014 Human Kinetics, Inc.
Hassanzadeh-Tabrizi S.A.,Islamic Azad University at Najafabad
Journal of the European Ceramic Society | Year: 2012
YAG:Eu nanopowder was synthesized through a sol-gel method. A master sintering curve was used as a practical approach to analyze the sintering behavior of the synthesized powder. The effect of MgO doping on sintering of the synthesized nanopowders was evaluated. An amorphous nanopowder was synthesized and crystallized to YAG after heat-treatment via a solid-state reaction. MgO improved the sintering rate of the YAG nanopowders and suppressed grain boundary mobility. The activation energy for sintering decreased from 917 to 837. kJ/mol by adding MgO to the nanopowders. The results of this study can be used to predict the densification of YAG:Eu nanopowder. © 2012 Elsevier Ltd.
Hooshmand R.A.,University of Isfahan |
Soltani S.,Islamic Azad University at Najafabad
IEEE Transactions on Power Systems | Year: 2012
Due to increasing neutral current and power losses resulting from phase unbalancing in distribution networks, the act of phase balancing has been a matter of interest in recent years. In this paper, a new method for phase arrangement of laterals and the distribution transformers is presented based on bacterial foraging (BF) oriented by particle swarm optimization (PSO) algorithm (BF-PSO). The algorithm is proposed for radial and meshed distribution networks in the presence of unbalanced loads. The objective function of this problem includes the neutral current of the supporting feeder, the rephasing cost, the voltage drop, and the line losses. Since these objectives do not have similar units and the same variation ranges, the four objectives are fuzzified and then integrated as the fuzzy multi-objective function. In order to prove the efficiency of the BF-PSO algorithm, its performance is compared with bacterial foraging, genetic and immune algorithms. To evaluate the proposed method, it is applied to feeder No. 3062 in Ahwaz, Iran. The simulation results confirm the efficiency of the method for the reduction of system costs and network phase balancing. © 2006 IEEE.