Entity

Time filter

Source Type


Samavati V.,University of Tehran | Manoochehrizade A.,Islamic Azad University at Ahvaz
Carbohydrate Polymers | Year: 2013

Ultrasonic technology was applied for polysaccharide extraction from the leaves of Dodonaea viscosa and response surface methodology (RSM) was used to optimize the effects of processing parameters on polysaccharide extraction yield. Three independent variables were extraction time (X1), extraction temperature (X2) and ultrasonic power (X3), respectively. The statistical analysis indicated the independent variables (X1, X2, X3), the quadratic terms (X 11 and X33) and the interaction terms (X1X 2, X1X3, X2X3) had significant effects on the yield of polysaccharides (P < 0.05). The optimal extraction conditions of D. viscosa leaf were determined as follows: extraction time 50.54 min, extraction temperature 85 °C and ultrasonic power 400 W. Under these conditions, the experimental yield of polysaccharides was 9.455 ± 0.24%, which was agreed closely with the predicted value (9.398%). The evaluation of anti-oxidant activity suggested that the polysaccharide exhibited significant protection against DPPH and hydroxyl radicals and could be explored as a nutraceutical agent. Crown Copyright © 2013 Published by Elsevier Ltd. All rights reserved. Source


Sajedi F.,Islamic Azad University at Ahvaz
Construction and Building Materials | Year: 2012

In this experimental work 24 mixes were prepared. Each mix was made using binder contents 380 and 500 kg/m 3. All the made mixes are classified into three groups as OPC, OPC-slag and slag mortars. Each group includes eight mixes and the specimens were cured in different curing regimes after casting and demoulding, i.e. under room temperature (ac), in water without heating (wc), room temperature after heating 60°C for duration 20 h (WH/ac) and in water after heating like as mentioned (WH/wc). The results showed that the highest strength is related to the OPC-slag mortars as 80 MPa for OSM380-wc. For all groups of mortars, there could rarely be strength loss at later ages. The results proved that WH/ac is the optimum curing regime for all groups of mortars in duration of 3-7 days, whereas the optimum curing regime is not the same in duration of 28-90 days. It was proved that higher strength could be achieved for OPC and OPC-slag mortars using lower binder content provided the specimens are cured in water without heating. This reality is reversed for slag mortars; namely for slag mortars the highest strengths could be only achieved using more slag content and water curing without heating. For SM500-wc the strengths obtained at 28 and 90 days were as 18 and 26 MPa, respectively. © 2012 Elsevier Ltd. All rights reserved. Source


Mafi Gholami R.,Islamic Azad University at Ahvaz | Mousavi S.M.,Tarbiat Modares University | Borghei S.M.,Sharif University of Technology
Journal of Industrial and Engineering Chemistry | Year: 2012

The present study examines the biorecovery of heavy metals from a spent refinery catalyst obtained from one of the oil refineries in Iran using Aspergillus niger. Bioleaching experiments were carried out in batch cultures using A. niger in the one-step process to mobilize Co, Mo and Ni from hazardous spent catalysts. Response surface methodology (RSM) was applied for the design and analysis of experiments with the optimization of pH, temperature, inoculum percentage, pulp density and rotation speed during the bioleaching of the metals. Experiments were designed as per the central composite design (CCD) technique. Three cubic mathematical models were derived for prediction of the responses. In process optimization, maximal values of Co, Mo and Ni recoveries were achieved as 71%, 69% and 46%, respectively, with a pH of 5.0, a temperature of 31°C, a pulp density of 2. g/L, a rotation speed of 115. rpm, and using a 12% inoculum. © 2011 The Korean Society of Industrial and Engineering Chemistry. Source


Samavati V.,Iran University of Science and Technology | Manoochehrizade A.,Islamic Azad University at Ahvaz
International Journal of Biological Macromolecules | Year: 2013

The effects of extraction temperature, extraction time, the ratio of water to raw material, and number of extraction on extraction yield of crude polysaccharides from the leaves of Malva sylvestris (MSLCP) were optimized by statistical analysis using response surface methodology. The response surface methodology (RSM) was used to optimize MSLCP extraction yield by implementing the CCD design. The experimental data obtained were fitted to a second-order polynomial equation using multiple regression analysis and also analyzed by appropriate statistical methods (ANOVA). Statistical analysis of the results showed that the linear and quadratic terms of these four variables had significant effects. The optimal conditions for higher extraction yield of MSLCP were extraction temperature: 90. °C, extraction time: 4. h, number of extraction: 2 and the ratio of water to raw material: 21. Under these conditions, the experimental yield was 8.377. ±. 0.38%, which is well in close agreement with the value predicted by the model 8.608%. The results demonstrated that MSLCP had strong scavenging activities in vitro on DPPH and hydroxyl radicals. Overall, MSLCP may have potential applications in the medical and food industries. © 2013 Elsevier B.V. Source


Sanaeishoar T.,Islamic Azad University | Tavakkoli H.,Islamic Azad University | Mohave F.,Islamic Azad University at Ahvaz
Applied Catalysis A: General | Year: 2014

LaMnO3 perovskite nanoparticles were prepared using a sol-gel method. The physical and chemical properties of the catalyst were determined using X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Energy dispersive X-ray spectroscopy, BET method and Fourier transform infrared spectroscopy. The XRD results indicated that the LaMnO 3 has a good crystalline phase at 600 C. The BET surface area of the mesoporous perovskite materials (LaMnO3) was 475 m2/g and the average width of the pores was 8.7 nm. The experimental data revealed that the LaMnO3 particles were nano-sized. This perovskite-type oxide as a green and reusable catalyst showed excellent catalytic activity for the synthesis of imidazo[1,2-a]pyridines. LaMnO3 catalyst could be recovered and reused in five reaction cycles, giving a total TON = 2790 and TOF = 372. The products were prepared under solvent-free conditions without any additives. Principal features of this simple method include non-hazardous reaction conditions, low catalyst loading and excellent yields. © 2013 Published by Elsevier B.V. Source

Discover hidden collaborations