Search for: sugar--sucrose
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    Optimization of HFDS production from date syrup

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 21, Issue 2 , 2008 , Pages 127-134 ; 1728-144X (ISSN) Jamshidi Mokhber, M ; Alemzadeh, I ; Vossoughi, M ; Sharif University of Technology
    Materials and Energy Research Center  2008
    Fructose is utilized as a common sweetener in many food industries. Today, a large amount of HFCS (high fructose corn syrup, an equilibrium mixture of glucose and fructose) is produced by glucose isomerase, immobilized enzymes from corn starch. There are a lot of date palms in Iran. Date is a favorable source of carbohydrates, and a suitable source for HFDS (high fructose date syrup) production. In this investigation, date syrup properties were first determined and the operational conditions for glucose isomerase application were optimized respectively. Ion exchange chromatography has been utilized for carbohydrate separation. Fructose obtained from chromatographic column reached 90 %... 

    Two-stage fungal leaching of vanadium from uranium ore residue of the leaching stage using statistical experimental design

    , Article Annals of Nuclear Energy ; Volume 56 , 2013 , Pages 48-52 ; 03064549 (ISSN) Gharehbagheri, H ; Safdari, J ; Roostaazad, R ; Rashidi, A ; Sharif University of Technology
    In this investigation, bioleaching of vanadium from uranium ore residue of the leaching stage was studied by Aspergillus niger in a two-step process at 30 °C and 150 rpm. The first step was initiated by growth of fungi in the absence of mine waste. Using response surface methodology, three factors were surveyed for fungal growth: initial pH, sucrose concentration and spore population. Also concentrations of oxalic, citric, and gluconic acids were measured as response in this step. During 30 days, maximum productions of these acids were 3265, 11578, and 7988 mg/l, respectively. Initial pH and sucrose concentration were significant factors for oxalic and citric acid production; however, for... 

    Sintering of Al2O3-SiC composite from sol-gel method with MgO, TiO2 and Y2O3 addition

    , Article Ceramics International ; Volume 37, Issue 5 , 2011 , Pages 1681-1688 ; 02728842 (ISSN) Mohammad Rahimi, R ; Rezaie, H. R ; Nemati, A ; Sharif University of Technology
    Al2O3-SiC composite ceramics were prepared by pressureless sintering with and without the addition of MgO, TiO2 and Y2O3 as sintering aids. The effects of these compositional variables on final density and hardness were investigated. In the present article at first α-Al2O3 and β-SiC nano powders have been synthesized by sol-gel method separately by using AlCl 3, TEOS and saccharose as precursors. Pressureless sintering was carried out in nitrogen atmosphere at 1600 °C and 1630 °C. The addition of 5 vol.% SiC to Al2O3 hindered densification. In contrast, the addition of nano MgO and nano TiO2 to Al 2O3-5 vol.% SiC composites improved densification but Y2O3 did not have positive effect on... 

    Fungal leaching of hazardous heavy metals from a spent hydrotreating catalyst

    , Article World Academy of Science, Engineering and Technology ; Volume 76 , 2011 , Pages 726-731 ; 2010376X (ISSN) Gholami, R. M ; Borghei, S. M ; Mousavi, S. M ; Sharif University of Technology
    In this study, the ability of Aspergillus niger and Penicillium simplicissimum to extract heavy metals from a spent refinery catalyst was investigated. For the first step, a spent processing catalyst from one of the oil refineries in Iran was physically and chemically characterized. Aspergillus niger and Penicillium simplicissimum were used to mobilize Al/Co/Mo/Ni from hazardous spent catalysts. The fungi were adapted to the mixture of metals at 100-800 mg L -1 with increments in concentration of 100 mg L -1. Bioleaching experiments were carried out in batch cultures. To investigate the production of organic acids in sucrose medium, analyses of the culture medium by HPLC were performed at... 

    Electrochemical oxidation of saccharose on copper (hydr)oxide-modified electrode in alkaline media

    , Article Cuihua Xuebao/Chinese Journal of Catalysis ; Volume 31, Issue 11 , 2010 , Pages 1351-1357 ; 02539837 (ISSN) Jafarian, M ; Rashvand Avei, M ; Danaee, I ; Gobal, F ; Mahjani, M. G ; Sharif University of Technology
    A stable copper (hydr)oxide-modified electrode was prepared in 0.5 mol/L NaOH solution by cyclic voltammetry in the range of -250 to 1000 mV. It can be used for electrochemical studies in the range of -250 to 1000 mV without interfering peaks because there is no oxidation of copper. During an anodic potential sweep, the electro-oxidation of saccharose on Cu occurred by the formation of CuIII and this reaction also occurred in the early stages of the reversed cycle until it is stopped by the negative potentials. A mechanism based on the electro-chemical generation of CuIII active sites and their subsequent consumption by saccharose was proposed, and the rate law and kinetic parameters were... 

    Artificial neural network aided estimation of the electrochemical signals of monosaccharides on gold electrode

    , Article Carbohydrate Research ; Volume 343, Issue 8 , 2008 , Pages 1359-1365 ; 00086215 (ISSN) Gobal, F ; Sadeghpour Dilmaghani, A ; Sharif University of Technology
    Artificial neural networks were used to predict the oxidation peaks potentials of 7 monosaccharides under linear sweep voltammetry regime. Two sets of descriptors, one based on molecular properties calculated through DFT and another based on simple geometric distributions of hydroxyl groups and asymmetric carbon atoms along molecular chains, were employed to introduce the molecules to networks. Relatively, simple networks of (3,3,1) and (3,3,3,1) structures with the number of epochs not exceeding 15 through training process were capable of correctly predicting the peaks positions with R values in the range of 0.97-0.99. © 2008 Elsevier Ltd. All rights reserved  

    Bioleaching kinetics of a spent refinery catalyst using Aspergillus niger at optimal conditions

    , Article Biochemical Engineering Journal ; Volume 67 , 2012 , Pages 208-217 ; 1369703X (ISSN) Amiri, F ; Mousavi, S. M ; Yaghmaei, S ; Barati, M ; Sharif University of Technology
    Elsevier  2012
    The kinetics of bioleaching of Mo, Ni, and Al from spent hydrocracking catalyst, using Aspergillus niger was studied. The four most effective bioleaching variables were selected in accordance with the Plackett-Burman design and were further optimized via central composite design (CCD). The optimal values of the variables for maximum multi-metal bioleaching were as follows: particle size 150-212. μm, sucrose 93.8. g/L, pulp density 3%. w/v, and pH 7. The maximum metal recoveries corresponding to these conditions were 99.5 ± 0.4% Mo, 45.8 ± 1.2% Ni, and 13.9 ± 0.1% Al. The relatively low Ni extraction was attributed to the precipitation of Ni in the presence of oxalic acid. Under the optimal... 

    Enhancement of bioleaching of a spent Ni/Mo hydroprocessing catalyst by Penicillium simplicissimum

    , Article Separation and Purification Technology ; Volume 80, Issue 3 , August , 2011 , Pages 566-576 ; 13835866 (ISSN) Amiri, F ; Mousavi, S. M ; Yaghmaei, S ; Sharif University of Technology
    Statistically based experimental designs were applied to screen and optimize the bioleaching of spent hydrocracking catalyst by Penicillium simplicissimum. Eleven factors were examined for their significance on bioleaching using a Plackett-Burman factorial design. Four significant variables (pulp density, sucrose, NaNO3, and yeast extract concentrations) were selected for the optimization studies. The combined effect of these variables on metal bioleaching was studied using a central composite design (CCD). Second-order polynomials were established to identify the relationship between the recovery percent of the metals and the four significant variables. The optimal values of the variables... 

    Synthesis and characterization of Al2O3-SiC nano composite by sol-gel method and the effect of tio2 on sintering

    , Article Journal of Nano Research ; Volume 13 , 2011 , Pages 7-19 ; 16625250 (ISSN) Rezaie, H. R ; Mohammad Rahimi, R ; Nemati, A ; Samadani, M ; Sharif University of Technology
    In the present article, α-Al2O3 nano powder was synthesized by a simple aqueous sol-gel method by using AlCl3 as precursor. It was shown that the gel calcined at 1000°C, 1100 °Cand 1200 °Cresulted in the formation of a crystalline ?-Al2O3 nano powder. In continue TEOS and saccharose was used to prepare SiO2 xerogels containing carbon nano particles. The conversion of the gel to β-SiC nano powders was accomplished by carbothermal reduction at 1500°Cfor 1 h in argon atmosphere. In second pace alumina matrix composites with nano particles of 5 vol% SiC were prepared with the addition of TiO 2 as sintering aid and densified by pressureless sintering method at 1600°Cand 1630°C for 2 h in nitrogen... 

    Synthesis, characterization and swelling behavior of chitosan-sucrose as a novel full-polysaccharide superabsorbent hydrogel

    , Article Journal of Applied Polymer Science ; Volume 109, Issue 4 , 15 August , 2008 , Pages 2648-2655 ; 00218995 (ISSN) Pourjavadi, A ; Aghajani, V ; Ghasemzadeh, H ; Sharif University of Technology
    A novel full-polysaccharide hydrogel was prepared by crosslinking of chitosan with periodate-oxidized sucrose. A tetraaldehyde molecule is synthesized via periodate oxidation of sucrose and then applied as a crosslinking agent to form a new hydrogel network. A mechanism for the superabsorbent hydrogel formation via reductive N-alkylation was also suggested. The structure of the hydrogel was confirmed by FTIR spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). It is shown that crosslinking of chitosan can improve its thermal stability. The effects of crosslinker concentration, pH, and inorganic salt on the swelling behavior of the hydrogel were studied. The... 

    Kinetics of organic removal in fixed-bed aerobic biological reactor

    , Article Bioresource Technology ; Volume 99, Issue 5 , 2008 , Pages 1118-1124 ; 09608524 (ISSN) Borghei, S. M ; Sharbatmaleki, M ; Pourrezaie, P ; Borghei, G ; Sharif University of Technology
    The process kinetics of a lab-scale upflow aerobic immobilized biomass (UAIB) reactor using simulated sugar-manufacturing wastewater as feed was investigated. The experimental unit consisted of a 22 l reactor filled with high porosity pumice stone. The UAIB reactor was tested under different organic loads and different hydraulic retention times (HRT) and the substrate loading removal rate was compared with prediction of Stover-Kincannon model, second-order model and the first order substrate removal model. After obtaining steady-state conditions, organic loading rate was increased from 750 to 4500 g COD/m3 day to resemble wastewater from sugar production lines, and hydraulic retention time... 

    DFT study of the interaction of cytidine and 2′-deoxycytidine with Li+, Na+, and K+: effects of metal cationization on sugar puckering and stability of the N-glycosidic bond

    , Article Carbohydrate Research ; Volume 344, Issue 6 , 2009 , Pages 771-778 ; 00086215 (ISSN) Aliakbar Tehrani, Z ; Fattahi, A. R ; Pourjavadi, A ; Sharif University of Technology
    Density functional theory (DFT) calculations were performed at the B3LYP level with a 6-311++G(d,p) basis set to systematically explore the geometrical multiplicity and binding strength for complexes formed by Li+, Na+, and K+ with cytidine and 2′-deoxycytidine. All computational studies indicate that the metal ion affinity (MIA) decreases from Li+ to Na+ and K+ for cytosine nucleosides. For example, for cytidine the affinity for the above metal ions are 79.5, 55.2, and 41.8 and for 2′-deoxycytidine, 82.8, 57.4, and 42.2 kcal/mol, respectively. It is also interesting to mention that linear correlations between calculated MIA values and the atomic numbers (Z) of the above metal ions were... 

    An inhomogeneous theoretical model for analyzing the temporal response of high concentration erbium-doped fiber laser

    , Article Solid State Lasers and Amplifiers III, Strasbourg, 8 April 2008 through 10 April 2008 ; Volume 6998 , 2008 ; 0277786X (ISSN); 9780819471963 (ISBN) Keyvaninia, S ; Karvar, M ; Bahrampour, A ; Sharif University of Technology
    In this paper the gain dynamics of an erbium-doped fiber laser (EDFL) with an inhomogeneous active medium in the presence of ion pairs is modeled. A two-level model for single ions and a three-level model for ion pairs are employed to write the propagation and rate equations of inhomogeneous laser medium. The governing equations are an uncountable system of partial differential equations (PDEs). By employing the moment method, the system of PDEs is converted to a finite system of ordinary differential equations (ODEs). The Solution of the system of ODEs is used to analyze the output power of a high concentration EDFL. As it expected, theoretical results show that the threshold pumping power...