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.
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.
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.
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.
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.