فهرست مطالب

Iranian Journal of Chemistry and Chemical Engineering - Volume:37 Issue: 2, 2018
  • Volume:37 Issue: 2, 2018
  • تاریخ انتشار: 1397/02/21
  • تعداد عناوین: 23
  • Armin Vedadghavami, Farnaz Minoei, Seyed Saeid Hosseini * Pages 1-23
    Protein separation and purification technologies play an essential role in various industries including but not limited to pharmaceuticals, dairy as well as the food sector. Accordingly, a wide variety of techniques such as chromatography and electrophoresis has been developed and utilized extensively over the years for this purpose. Despite their widespread acceptance, conventional techniques still suffer from major limitations and complexities such as short lifetime, low productivity, high-pressure drop and difficulty in scale-up among others. Membrane separation processes has received significant attention in recent years as a promising alternative that can potentially overcome the problems associated wif conventional technologies due to their spectacular features. The prime advantages offered by the membrane-based processes for protein separation and purification include tunable properties, cost-effectiveness, superb productivity, as well as energy efficiency. The present manuscript aims to highlight the significant aspects of the established protein separation and purification technologies by addressing the principal concepts and highlighting their characteristics. Special attentions are paid to the membrane-based processes by providing detailed features and specifications involved in each individual process, especially from the industrial perspective. Furthermore, the recent and ongoing progress on strategies and practical techniques towards improvement in the performance of membranes for separation and purification of various proteins are introduced and discussed in details.
    Keywords: Protein separation, purification, Performance improvement, Polymeric membranes, Membrane modification
  • Alireza Razeghizadeh, Iraj Kazemnezhad, Leyla Zalaghi, Vahdat Rafee * Pages 25-32
    In dis paper, teh TEMPeffects of changes in Sol concentration on teh structural and optical properties of SnO2 Nanoparticles are studied through teh Sol-Gel method. SnO2 Nanoparticles are produced from different SnO2 solution concentrations (0.1, 0.3 and 0.5 mol/L) at room temperature. X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) analysis are used to investigate teh TEMPeffects of changes in Sol concentration on teh crystalline and surface morphology of Nanoparticles. Teh XRD pattern shows dat teh particles are in teh standard tetragonal phase of SnO2. Teh crystallites sizes are 11.7nm, 18.8nm, and 74.8nm, for 0.1 M, 0.3M and 0.5 M of concentration respectively. Teh average size of SnO2 particles decreases by a reduction in teh Sol concentration. Teh band gap value is 4.07eV, 4.28eV and 4.36eV for 0.5M, 0.3M and 0.1M of concentration respectively. Teh UV-Visible analysis shows dat decreasing teh Sol concentration will cause teh absorption edge shift to teh shorter wavelengths, coz decreasing teh Sol concentration will reduce teh Nanoparticles size, and smaller Nanoparticles size absorb shorter wavelengths better and also increase teh band gap.
    Keywords: SnO2, Nanoparticle, Sol-Gel, XRD, FT-IR analysis
  • Mostafa Feyzi *, Ali Lorestani Zinatizadeh, Parasto Nouri, Fataneh Jafari Pages 33-44
    Teh promoted K-La nanocatalysts supported on ZSM-5 zeolite were prepared via wetness impregnation method and tested for biodiesel production from soybean oil. Teh TEMPeffects of different weight percentage of La, loading of K as a promoter and calcination conditions on structure and activity of catalyst were investigated. Results showed dat teh supported catalyst containing 7wt.% of La was promoted with 1wt.% of K is an optimal catalyst for biodiesel production. Teh best operational conditions were teh CH3OH/oil=12/1 molar ratio at 60˚C with mechanical stirring 500 rpm for 3 h. Teh biodiesel yield reached 90% under teh optimal operational conditions. It was found dat K-La/ZSM-5 nanocatalyst have high basic sites and catalytic activity for biodiesel production. Characterization of catalysts was carried out by using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Temperature Programmed Desorption (TPD), X-Ray Diffraction (XRD), Fourier Transform-InfraRed(FT-IR) spectroscopy and N2 adsorption-desorption measurements methods.
    Keywords: : Biodiesel, Wetness impregnation, Calcination conditions, Operational condition, Characterization
  • Behzad Aghabarari * Pages 45-52
    For the synthesis of Mequinol (4-methoxy phenol), two acidic ionic liquids based on imidazolium cation (BMSIL and IMSIL) synthesized and characterized by FT-IR, 1H NMR, and CHNS analyses. Tan, the Baeyer–Villiger oxidation of para-anisaldehyde was studied wif these ionic liquids, as the catalysts. The results showed that the BMSIL wif more Brønsted acidic functions had higher catalytic activity than IMSIL and even sulfuric acid at room temperature. Furthermore, the different reaction parameters were studied and maximum conversion (99%) and selectivity (95%) of Mequinol was observed by using 5% BMSIL as a catalyst, H2O2 (30% solution) as oxidant, Methanol as solvent at 3.5 h, and room temperature condition. Also, we investigated the TEMPeffect of different substituents in the aromatic ring of benzaldehyde and various solvents on the catalytic activity of BMSIL ionic liquid as the best catalyst in the oxidation of aromatic aldehydes. The results show that the protic solvent and electron-donating substituents in the para position of benzaldehyde favor the phenol product.
    Keywords: Mequinol, Baeyer–Villiger oxidation, Acid catalyst, Ionic liquid
  • Mahtab Pirouzmand* , S. Keyvan Seyed, Rasulzade, Behnaz Nikzad, Kojanag Pages 53-60
    Two approaches for metal ion incorporation were employed to introduce Ca2+ into SBA-15; Direct Synthesis (DS) and Wet Impregnation (WI). The non-ionic template was removed by two different methods; calcination and solvent extraction. The obtained catalysts were characterized by means of X-Ray Powder Diffraction (XRD), Energy Dispersive X-ray (EDX), and FT-IR spectroscopy. The basicity was determined by using Hammett indicators and benzoic acid titration. The TEMPeffects of synthesis methods and organic template on basicity and catalytic performance were studied in the transesterification of Canola oil with meTEMPthanol. 1H NMR was used to analyze the products. The best results were obtained using catalysts which prepared by wet impregnation method. Furthermore, calcination is a better method of template removal. So calcined Ca/SBA-15 prepared by impregnation showed particularly the highest activity (conversion 84.2 %). Although dis catalyst has a limited reusability in the transesterification reaction.
    Keywords: Ca, SBA-15, Pluronic P123, Biodiesel, Impregnation, Direct Synthesis
  • Arul Jesu Gnanaprakasam, Vaiyazhipalayam Murugaiyan Sivakumar*, Marimuthu Thirumarimurugan Pages 61-71
    An Nd doped ZnO (1-5%) photocatalyst was successfully synthesized via chemical co-precipitation method. The optical property, nature, and morphology of the synthesized nanoparticles were analyzed by UV-Visible, XRD, and FESEM respectively. XRD study reveals that Nd has been effectively incorporated in the ZnO lattice in the lower level dosage; however, the crystalline nature has been distorted towards the increase in the Nd. The selected brilliant green dye was degraded photo-catalytically with the help of the synthesized nanoparticles and the study has been extended with catalyst dosage and dye concentration. The 2% Nd-doped ZnO showed a remarkable result of 98.26% degradation of brilliant green dye compared to the other 1,3,4 & 5 % Nd-doped ZnO nanoparticles which clearly indicates the optimization of depletion region corresponding to the maximum degradation. The increased content (3-5%) of Nd-doped ZnO exhibited moderate photocatalytic degradation of the dye due to the decreased crystalline nature which was further evidenced from XRD studies.
    Keywords: Nd-doped ZnO nanoparticles, Brilliant green dye, Kinetic study, Photocatalytic degradation
  • Ahmad Shaabani *, Hamid Mofakham, Fatemeh Hajishaabanha, Sajjad Mousavi Faraz, Milad Pedarpour Vajargahy Pages 73-84
    In this protocol, we report a novel approach for the synthesis of a new class of heterocyclic 1H-1,2,3-triazole-modified peptidoimetic compounds. The process consists of an Ugi four-component condensation reaction of amines, an isocyanide, an aldehyde and acids followed by a Huisgen 1,3-dipolar cycloaddition reaction with an azide group in the presence of a catalytic amount of CuSO4.5H2O/sodium ascorbate. The copper-catalyzed Huisgen cycloaddition reactions provide such a general synthetic method, with the resulting 1,2,3-triazoles being good peptide bond mimics. This protocol was highly efficient for structurally diverse heterocyclic molecules containing an active aldehyde group and will find applications in combinatorial chemistry, diversity-oriented synthesis, and drug discovery.
    Keywords: 1H-1-2-3-Triazole, 1-3-Dipolar cycloaddition, Ugi four-component, Isocyanide
  • Khalil Ahmad *, Helmut Guido Alt Pages 85-94
    A series of seven new complexes of zirconium and hafnium with bulky ω-aryloxyalkyl substituted indenyl ligands were synthesized and characterized by NMR spectroscopy and elemental analysis. These complexes were activated with methylaluminoxane and tested for homogeneous ethylene polymerization. The zirconium catalysts showed higher activities than their hafnium analogues. The effects of increasing separation between the indenyl and the aryloxy substituent and the introduction of an extra methyl group on the indenyl moiety were also investigated. Catalyst 6 bearing a spacer chain of three methylene groups between the indenyl and aryloxy substituents showed the highest activity (15500 kg PE/mol cat. h). The increase in the spacer chain length resulted in the decrease in catalyst activities.
    Keywords: Metallocene complexes, Bulky ?-aryloxyalkyl-substituted indenyl ligands, ethylene polymerization
  • Hadi Abusaidi, Hamid Reza Ghaieni* , Saeed Tavangar Pages 95-101
    This paper has been utilizing the simultaneous ThermoGravimetric analysis and Differential Scanning Calorimetry (TG–DSC) to investigate the thermal decomposition of magnesium-sodium nitrate pyrotechnic composition based HTPB resin. The thermal behaviors of different samples with various fuel-oxidizer ratio contents were determined. Decomposition kinetic was investigated by evaluating the influence of DSC heating rate (4, 7, 10, 13 oC/min) on the behavior of the illumination flares. The results as expected showed that the decomposition temperature of the illumination flares decreases with the increase in the DSC heating rate, while thermal decomposition of the sample followed the first-order law. Furthermore, Magnesium-sodium nitrate illumination flares with HTPB resin have been studied for luminous efficiency by varying fuel/oxidizer ratio. The kinetic and thermodynamic parameters of the illumination flares decomposition under ambient pressure were obtained from the resulted DSC data via non-isothermal methods proposed by ASTM E698 and Flynn-Wall-Ozawa. Also, the critical temperature of ignition temperature was estimated at about 455 oC.
    Keywords: Pyrotechnic, Thermal decomposition, Kinetic, Non-isothermal, Luminous efficiency
  • Seyed Mahmoud Mousavi Safavi *, Mohammad Ali Kiani Pages 103-109
    Ordered Mesoporous Carbon (OMC) represents an interesting material for electric double layer capacitors which has teh high surface area, easily accessed ordered pore channels and lower production cost. In this work, CMK-3 as promising OMC has been fabricated using teh ordered mesoporous silica SBA-15 as a template. Teh structure and morphology of CMK-3 are characterized by X-ray diffraction, nitrogen adsorption/desorption, and scanning electron microscopy. CMK-3 is sprayed on teh surface of highly conductive three-dimensional nickel foam and characterized as an electrode for electric double layer capacitors. When this electrode is soaked in a neutral aqueous electrolyte solution, reaches a specific capacitance as high as 285 and 167 F/g, at a current density of 10 and 34 A/g, respectively. CMK-3 shows excellent long-term stability with >90% capacitance retention after 10000 cycles, as well as high power (37 kW/kg) and energy density (98 Wh/kg).
    Keywords: Mesoporous carbon, Supercapacitor, Neutral aqueous electrolyte, High power, Symmetric
  • Volodymyr Tkach *, Yana G Ivanushko, Svitlana M. Lukanova, Lyudmyla V. Romaniv, Iryna Kukovs’ka, S?lvio C. de Oliveira, Reza Ojani, Fauze J. Anaissi, Petro I. Yagodynets Pages 111-116
    The possibility of hydroxylamine electrochemical determination over a CoO(OH)-modified electrode, accompanied by complex-formation, has been studied from teh theoretical point of view. The correspondent mathematical model has been developed and analyzed by means of linear stability theory and bifurcation analysis. It was shown dat CoO(OH) may be applied as an efficient electrode modifier in teh detection of hydroxylamine in neutral and slightly alkaline media. The electrochemical response has to be clear and easy to interpret. The possibility of teh oscillatory and monotonic instabilities has also been verified.
    Keywords: Food safety, Hydroxylamine, Cobalt (III) oxyhydroxide, Electrochemical sensors, Stable steady-state
  • Bhuvanendra Singh, Rajeev Singh *, Bhoop Singh, Dilip Kumar Pages 117-131
    In this study, we theoretically investigated Methyl hydrazinecarbodithioate by quantum chemical calculations for geometry optimization, vibration frequencies, and electronic structure parameters. The geometry optimization by DFT, ab initio MP2 method and the frequency calculation by DFT method was performed at the highest available Pople style 6-311G++(3df,3pd) basis set level. The semi-empirical calculations were performed by the latest PM7 method. The theoretically obtained results were compared with the experimental data. Conformational behavior, frontier molecular orbitals, molecular electrostatic potential, electron localization function, and non-covalent interaction plots were also analyzed. The study explained the geometry, conformational flexibility and relative stability of different conformers.
    Keywords: DFT, Electron localization function, MP2, Molecular electrostatic surface potential, PM7
  • Ivana Boskovic*, Veselinka Grudic, Mileta Ivanovic, Ivana Milasevic Pages 133-138
    This paper studies the influence of process parameters: temperature, the weight of the added precipitant agent, pH and reducing agent on the kinetics of the process of reduction and precipitation of gold of 98.44% purity obtained in the process of electrical and electronic waste recycling. The optimal conditions of reduction and precipitation of colloidal gold particles in the process of recycling of different waste types in order to obtain high-purity gold are the following: an optimal process time (τ = 11minutes), temperature (t=5°C), the weight of the added precipitant (m = 6g of pure gold) and K2S2O5 as the preferred reducing agent. The results has contributed to a better understanding of the reduction and precipitation rate of colloidal gold particles in order to manage and control this process. The granulometric analysis confirms the existence of colloidal gold particles. SEM analysis indicates spherical particles and good homogeneity of the sample. XRF analysis shows that gold obtained in dis process of recycling is highly pure (99.99%).
    Keywords: Colloidal gold particles, The reduction, precipitation rate, Recycling, Waste
  • Abdoullah Samiee Beyragh, Mehdi Varsei, Mohammad Meshkini* , Ahmad Khodadadi Darban, Esmaeil Gholami Pages 139-149
    The extraction of gold involves using cyanide which has the potential to impact the environment. Many studies have been done to reduce the environmental effects of cyanide. In this research, the cyanide adsorption on zeolite from gold processing plant tailing dam wastewater was investigated. Results indicated that the pH of the solution, contact time duration, temperature, zeolite amount and size of zeolite particles were the most important parameters in the adsorption process. Zeolite was used in two fraction sizes; (100-300)m and (300-1000)m in two types of natural and impregnated with copper sulfates. The optimum amounts of both natural and impregnated zeolite in the solutions and the maximum cyanide adsorption percentage were determined as 30, 24g/L and 50.2, 86.1% for small fraction size, and 36, 24g/L and 39.5, 64% for large fraction size, respectively. The optimum values of pH were 10.5 and 10 for natural and impregnated types in both fraction sizes. Contact time duration in equilibrium conditions for fraction sizes of (100-300)m and (300-1000)m were 40 and 50 min, respectively. The optimum temperature in all situations was 22 ºC. The adsorption process in a size of (100-300)m for natural zeolite was fit into the Freundlich model and for impregnated zeolite type there was no significant difference between two models, although, the Langmuir model was more accurate. In a fraction size of (100-300)m for two types of zeolites, the kinetic adsorption was fit into the Lagergren second-order kinetic model. In a fraction size of (300-1000)m, the adsorption kinetics for the natural type has no sensible difference between the first and second Lagergren kinetic model, but for the impregnated zeolite type it follows the second-order kinetic model. The results showed that the cyanide adsorption on impregnated zeolite was more than the natural type.
    Keywords: Cyanide, Zeolite, Kinetic, Adsorption, Freundlich, Langmuir, Lagergren isotherm model
  • Zsigmond Papp * Pages 151-156
    Unmodified and glod-modified semiconductor oxides were used for teh complete decolorization of non-buffered aqueous safranin O solutions. Photocatalytic properties of commercially available ZnO and TiO2 (anatase nanopowder) were compared with those of glod-modified ZnO (Au/ZnO). Au/ZnO was obtained from commercial ZnO powder through direct current sputter coating. ZnO-based catalysts show significantly higher decolorization power in comparison with TiO2. Au/ZnO show slightly higher activity TEMPthan unmodified ZnO. Decolorization of safranin O using Au/ZnO was additionally tested in different types of mineral water. Teh decolorization efficiency in mineral waters was negatively correlated with teh dry residue content (180 °C) and in all cases was less TEMPthan in distilled water. Teh inhibiting TEMPeffect of hydrogen carbonate was additionally investigated.
    Keywords: Zinc oxide, Titanium dioxide, Modification wif glod, Decolorization, Safranin
  • Sivarajasekar Natesan *, Baskar Rajoo Pages 157-169
    Cationic dye - basic red 2 (BR2) was removed from aqueous solutions by sulfuric acid activated waste Gossypium hirsutum seeds (WGSAB). The main and interactive effects of five process variables such as, adsorbent dose (1.25 – 5 g/L), initial dye concentration (100–300 mg/L), contact time (1–3 h), pH (2 – 12) and temperature (20 – 400C) were investigated via response surface methodology (RSM) based on Box–Behnken statistical design. The optimum values of the key variables were estimated using Derringer’s desirability function. The optimal values were found to be at an adsorbent dose 2.41 g, initial dye concentration 150 mg/L, pH 8.69, temperature 33.570C, and contact time 1.42 h with the maximum desirability of 91%. The equilibrium data obeyed Redlich-Peterson isotherm which showed that the WGSAB was heterogeneous and BR2 was adsorbed in multilayers. The kinetic investigation showed that the BR2 was chemisorbed on WGSAB surface following Avrami fractional order kinetics. The thermodynamic parameters revealed that the BR2 adsorption process was spontaneous and endothermic. Regeneration of exhausted WGSAB found to be possible via acetic acid as elutant.
    Keywords: Adsorption, Box-Behnken, Derringer’s desirability, Gossypium hirsutum seed, equilibrium
  • Vahid Bab, Mehdi Ahmadi Sabegh , Aziz Babapoor * Pages 171-182
    In this study, the amount of generated pool fire, as a result of the release of chemicals in the case of an accident in tunnels, was simulated and the results were compared to the experimental data. At first, various amounts of spatial resolution (R*) were considered to compare the existing experimental data at different heights at the upstream, downstream and above the pool fire. The comparison studies showed that both numerical predictions and experimental measurements were, in general, comparable. Furthermore, FDS code was used to simulate the tunnel fire scenario for both cases of natural and forced ventilation. The grid using in the simulations is assessed by cells with the optimal spatial resolution and the influence of the ventilating systems on pool fire dynamic and its development was investigated. As a consequence, the temperature profile, O2, CO2, and visibility were compared in the two cases. These results showed that the ventilation system plays an important role in both fire development and heat removal by providing a safely evacuate rout in the tunnel.
    Keywords: Tunnel fire, CFD, FDS, Pool fire, Spatial resolution
  • Seyyed Hossein Hosseini *, Goodarz Ahmadi, Mahmoud Reza Rahimi, mehrdad kiani Pages 183-192
    In this study, the pressure drop for the binary mixtures of particles differing in size and density in a pseudo-2D spouted bed was experimentally studied. A binary mixture of solid particles including sand, Gypsum, and polyurethane was used in the experimental setup. Effects of static bed height, cone angle, particles diameter, and a particles weight fraction on the bed pressure drop were evaluated. The relationship between the peak pressure drops of the binary mixtures to the minimum spouting velocity was discussed. The trend of variation of pressure drop versus superficial gas velocities for binary particle mixtures in the spouted beds was found to be similar with that for the single sized particle system. The particles that sink to the bed bottom are called jetsam, whereas those gathered at the upper section of the bed are called flotsam. At the same air velocity for jetsam and flotsam rich systems, the maximum pressure drop in the jetsam rich system was larger than the flotsam one. The measured values of minimum spouting velocity were compared with some empirical correlations for single sized particles in spouted beds.
    Keywords: Pressure drop, 2D spouted bed, Minimum spouting velocity, Binary particles, Experiment
  • Raquel Guiné *, Christophe Gonçalves, Susana Matos, Fernando Gonçalves, Daniela V.T.A Costa, Mateus Mendes Pages 193-212
    The present study aimed at investigating the influence of several production factors, conservation conditions, and extraction procedures on the phenolic compounds and antioxidant activity of blueberries from different cultivars. The experimental data was used to train artificial neural networks, using a feed-forward model, which gave information about the variables affecting the antioxidant activity and the concentration of phenolic compounds in blueberries. The ANN input variables were location, cultivar, the age of the bushes, the altitude of the farm, production mode, state, storage time, type of extract and order of extract, while the output variables were total phenolic compounds, tannins as well as ABTS and DPPH antioxidant activity. The ANN model was fairly good, with values of the correlation factor for the whole dataset varying from 0.948 to 0.979, while the values of mean squared error were ranging from 0.846 to 0.018, for DPPH antioxidant acidity and anthocyanins, respectively. The results obtained showed that the methanol extracts contained higher amounts of total phenols and anthocyanins as compared to acetone: water extracts, while presenting similar quantities of tannins in both extracts. The blueberries from organic farming were richer in phenolic compounds and possessed higher antioxidant activity than those from conventional agriculture. Even though the effect of storage was not established with high certainty, a trend was observed for an increase in the phenolic compounds and antioxidant activity along storage, either when under refrigeration or under freezing, for the storage periods evaluated.
    Keywords: Antioxidant activity, Artificial neural network, Blueberry, Conservation, Phenolic compounds
  • Ricardo Hern aacute ndez, Mart&iacute nez, Tannia Qui&ntilde ones, Mu&ntilde oz, Adriana V&aacute zquez, Manuel A. Lizardi, Jimenez * Pages 213-218
    Diesel is composed of various toxic compounds that can have a negative influence on the environment including plants, microorganisms, and even groundwater being used for cultivation and human consumption. Diesel oil biodegradation kinetics was investigated using bubble-column reactor and microbial consortium isolated from a hydrocarbons spill site and were assessed by gas chromatography. The purpose of this study was to demonstrate the importance of intrinsic microorganisms used to degrade diesel. 93.84% of the diesel got consumed in the bubble-column reactor after 15 days of culture. The consortium showed the ability to produce emulsifiers using diesel oil as its only carbon and nitrogen source (hydrocarbonclastic). This study showed that the hydrocarbonclastic consortium isolated from polluted soil has the metabolic tools for diesel degradation (as a single carbon and energy source), and the capacity to produce bioemulsifiers in a bubble column reactor. Microbial consortium and bioemulsifiers produced in this research have the potential to be used in the cleanup processes of polluted soil with hydrocarbons such as diesel.
    Keywords: Bubble column reactor, Oil Biodegradation, Bioemulsifiers, Microbial consortium
  • Jalal Ehsani, Mohammad Mohsenzadeh *, Morteza Khomeiri, Azim Ghasemnezhad Pages 219-230
    The aim of this study was to produce synbiotic yogurt using different inulin levels (0, 1 and 2%) and probiotic bacteria. Inulin in two forms commercial and extracted from artichoke root was prepared, and chemical and sensory evaluation were performed. The results of inulin analysis showed that pH, dry matter, degree of polymerization, purity, appearance and taste for the inulin extracted from the artichoke root were 6.39, 92.8%, 30.5, 88.5%, white powder and neutral, whereas these parameters for commercial inulin were 6.14, 97.8%, 23, 92.3%, white powder and neutral, respectively. In the following, the production of synbiotic yogurt was carried out at 42°C until pH reached 4.5±0.02. The results of biochemical, microbiological and sensory characteristics at the end of fermentation showed that probiotic yogurt containing 2% (w/w) commercial inulin (ABY-Ch (2%)) had a faster acidity increase, shorter incubation time and greater final titrable acidity than other yogurt samples. Although inulin extracted from artichoke increased the viability of probiotic bacteria in yogurt, but ABY-Ch (2%) yogurt had the ever greatest viability of probiotics.the highest lightness (L*) is related to ABY-Ch (1%) and ABY-Ch (2%) yogurt samples, and ABY-C (2%) yogurt (yogurt containing 2% (w/w) artichoke root inulin) exhibited more unpleasant flavor compared to ABY yogurt (control) and had the lowest flavor score.
    Keywords: Chemical evaluation, Degree of polymerization, Inulin, lightness, pH, Synbiotic yogurt
  • Seyed Ebrahim Ghasemi *, Ali Akbar Ranjbar, Seyed Mohammad Javad Hoseini Pages 231-239
    In this paper, the cooling performance of water-cooled heat sinks for heat dissipation from electronic components is investigated numerically. Computational Fluid Dynamics (CFD) simulations are carried out to study the rectangular and circular cross-sectional shaped heat sinks. The sectional geometry of channels affects the flow and heat transfer characteristics of minichannel heat sinks. The three-dimensional governing equations in steady state and laminar flow are solved using Finite Volume Method (FVM) with the SIMPLE algorithm. The results show that the numerical simulation is in good agreement with the experimental data. The thermal and hydrodynamic characteristics of the heat sinks including Nusselt number, friction factor, thermal resistance and pumping power for various geometries of heat sinks are discussed in details. The results indicate that the heat sink with rectangular cross-section has a better heat transfer rate and the circular channel heat sink has the lower pumping power.
    Keywords: Cooling performance, Computational Fluid Dynamics (CFD), Heat sink, Circular channel, Rectangular channel
  • Jie Zhang, Zhang Fan, Zhongzheng Lee, Pingya Luo, Ayodeji A. Jeje, Gang Chen * Pages 241-246
    In this work, a novel thinner derived from natural botany Chinese Larch Tree was obtained by combination lignin with phenol using H2O2 as oxidant and the acting efficiency of lignosulfonate in the drilling fluids is greatly enhanced after oxidation with H2O2. Both the chemical structure and the adsorptive ability of the oxidation product are investigated. From experimental results, it was shown that lignin couple with polyphenol and the combination was greatly improved during the process of oxidation under H2O2 in light of the increased molecular weight of the derivative and different major function groups content after oxidation. Furthermore, the oxidized derivative has the good adsorptive-warping ability on the outer surface of particulate clay, which gives great potential for developing novel polymer drilling fluid with good inhibitory and thinning properties.
    Keywords: Lignin, Polyphenol, Drilling fluid, Thinner, Oxidation