فهرست مطالب

Scientia Iranica - Volume:27 Issue:4, 2019
  • Volume:27 Issue:4, 2019
  • تاریخ انتشار: 1398/09/28
  • تعداد عناوین: 7
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  • Muhammad Abbasi *, Majid Nazir, Aziz Ur Rehman Aziz Rehman, SABAHAT SIDDIQUI SYED SHAH, Muhammad Shahid Pages 3375-3386

    A new series of 1-[(E)-3-phenyl-2-propenyl]piperazine derivatives (5a-m) as antibacterial agents was designed and synthesized. The synthetic strategy was initiated by coupling different anilines (1a-m) with bromoacetyl bromide (2) in aqueous basic medium to acquire different electrophiles, 3a-m, with good yields. These electrophiles were further reacted with 1-[(E)-3-phenyl-2-propenyl]piperazine (4) to yield the desired compounds, N-(substituted)-2-{4-[(E)-3-phenyl-2-propenyl]-1-perazinyl}acetamides (5a-m). The structures of these compounds were established from their IR, 1H-NMR, 13C-NMR, EI-MS and CHN analysis data. The bacterial biofilm inhibitory potential of these piperazine derivatives was tested against two pathogenic strains, Bacillus subtilus and Escherichia coli. Two compounds, 5d and 5h were identified as suitable antibacterial agents. The cytotoxicity of these molecules was profiled through hemolytic assay and it was inferred that all the compounds were nearly harmless for membrane of red blood cells.

    Keywords: 1-[(E)-3-Phenyl-2-propenyl]piperazine, Bromoacetyl bromide, Amides, Biofilm inhibition, Hemolysis
  • Barzin Safarkoopayeh, Alireza Abbasi *, Abdolhadi Mokarizadeh, Alireza Shayesteh, Mahnaz Najafi Pages 3387-3399
    A polyoxoniobate-based 3D framework [K8H30Nb6O31] (1), was prepared through hydrothermal method and characterized by single crystal X-ray diffraction, powder X-ray diffraction (PXRD), solid state UV-visible and thermogravimetric analysis (TGA). Structure and properties of 1 were investigated with various computational methods. QTAIM and NBO studies together with thermogravimetric analysis suggest strong interactions between potassium ion, Lindqvist hexaniobate and water molecules. Hirshfeld surfaces around the Nb6O198- reveal that the Lindqvist ion acts as a ɳ3 ligand for the alkali cations. One remarkable detail about the structure is the presence of an encaged potassium ion, surrounded by six water molecules and four potassium ions. The prepared polyoxoniobate (PONb) was tested in the removal of diazo dye pollutant in water. The result shows that 1 has good activity and stability during the dye removal process and can be recovered and reused at least for five cycles.
    Keywords: Polyoxoniobate, Dye Removal, X-ray structure, water pollutant, DFT Calculations, QTAIM
  • Mohammad Khademi *, Soheila Zandi Lak Pages 3401-3414
    In recent years, biofuels have attracted considerable attention as renewable and clean source of energy and have been playing the role of suitable alternatives to fossil fuels. One of the most attractive types of biofuels is Acetone-Butanol-Ethanol (ABE) which is produced in a batch fermentation process by the anaerobic bacterium Clostridium acetobutylicum and sugar-based substrate as feedstock. In this paper, optimization of this process was carried out according to a bi-objective function. A hybrid model of Multi-Objective Differential Evolution (MODE) algorithm and distinguished decision-making methods, namely Linear programming technique for Multidimensional Analysis of Preference (LINMAP), Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) and Shannon's entropy were applied to find the final optimal operating point. The initial concentration of substrate and the final operating time of the process were selected as decision variables to maximize two main objectives in terms of solvents yield and productivity. A Pareto optimal set presents a wide range of optimal operating points and a proper operating condition can be selected based on the necessities of the applicant. The best optimal point obtained by TOPSIS, according to the lowest value of deviation index, was also compared with the results of economic-based optimization.
    Keywords: ABE fermentation, Clostridium acetobutylicum, optimization, Multi-objective differential evolution, Decision-making method
  • Ali Esfandiari, Mohammad Kazemeini * Pages 3415-3430
    Core-Shell structures of Ag@Pt nanoparticles (NPs) dispersed upon reduced graphene oxide (rGO) support containing different Ag:Pt mass ratios synthesized through the ultrasonic treatment method. These applied to the oxygen reduction reaction (ORR) process in a Proton Exchange Membrane Fuel Cell (PEMFC). The morphology of as-prepared catalysts characterized through High Resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and induced coupled plasma atomic emission spectroscopy (ICP-OES) analyses. The ORR activities and stabilities of catalysts studied through electrochemical measurements of Cyclic Voltammetry (CV) and single cell tests, respectively. The results revealed, prepared Ag@Pt/rGO catalysts possessed a Core-Shell nanostructure and the one with the Ag:Pt mass ratio of 1:3 displayed the largest electrochemical surface area (of 77.6 m2 g-1) as well as; provided the highest stability compared with prepared electrodes containing other Ag:Pt ratios and the obtained commercial Pt/C material. The maximum power density for the MEA prepared with this electrocatalyst determined to be 55% higher than that of the commercial Pt/C evaluated through single cell techniques. Thus, the understudied material seemed to be a very promising cathode for utilizing in PEM fuel cells.
    Keywords: Core-Shell, Electrocatalyst, Oxygen Reduction, PEMFC, reduced graphene oxide
  • Saeid Sadeghnejad *, Mehrdad Manteghian, Hosein Ruzsaz Pages 3431-3446
    Optimizing the efficiency of WAG flooding projects can guarantee the success of these projects. Many operational constraints can indirectly affect the flooding efficiency. Their effects is not normally considered during routine optimizations. The main aim of this study is to find the influence of these constraints (e.g., maximum water-cut, maximum GOR, and minimum BHP during WAG process). Implementing a reservoir simulator coupled with a simulating-annealing (SA) enables us to discover the effects of these constraints during simulation optimizations. The developed optimizer is applied into a case study from an Iranian formation located in the Persian Gulf. The recovery factor of WAG flooding is compared with that of the conventional waterflooding and gas injection. Moreover, the optimization of individual and simultaneous WAG parameters are analyzed. Results indicate that a) operational constraints not also can alter the production mechanism but also they directly affect the ultimate recovery factor; b) the recovery factor of simultaneous optimization of all WAG parameters is higher than that of individual parameter optimization; c) irrespective to the manner of parameter optimization, WAG ratio (or the volume fraction of injected water to gas) remains almost constant during all optimizations, showing the influence of this parameter during WAG flooding scenarios.
    Keywords: Water-Alternating-Gas, EOR, optimization, Simulated annealing, Operational Constraints
  • Amideddin Nouralishahi *, Mohsen Bahaeddini, Ali Morad Rashidi, Shirin Mahinnezhad, Ali Fazeli Pages 3447-3455
    Abstract Activated carbon from walnut shell is studied for methane storage in this research. The samples are ‎synthesized by zinc chloride and phosphoric acid, as activating agents. The effect of physical ‎activation, after chemical activation steps, on the final structure of the samples and their total methane ‎storage is examined. The results show that physical activation has an improving effect on the total ‎capacity of the samples activated by phosphoric acid, however; it has a reverse effect on the ‎capacity of zinc chloride activated ones. The experimental data show that the best capacity is ‎obtained at impregnation ratios of 0.7 and 1.2 in the case of phosphoric acid and zinc chloride ‎activated samples, respectively. The best sample is the one activated by phosphoric acid with ‎impregnation ratio of 0.7 and subsequently physically activated by carbon dioxide. It has the BET ‎surface area of 1479 m2/g, average pore diameter of 4.2 nm, total pore volume of 0.84 cm3/g and ‎methane adsorption capacity of 159 cm3/g. The sample shows high stability during successive ‎adsorption/desorption cycles experiment. ‎
    Keywords: ANG, Activated Carbon, Methane, Nano-porous adsorbents
  • Anil Kumar, Avinash Thakur * Pages 3456-3467
    An environment-friendly reactive extraction method as a novel phase separation technique was postulated to extract lactic acid (LA) from aqueous solution by means of environmentally benign green solvents along with the synergistic mixture of extractants. Reactive extraction of LA has been carried by using synergistic mixture of extractants (trioctylamine (TOA), Aliquat336, and tridodecylamine (TDDA)), organic solvents, and non-toxic and biocompatible green solvents. From the different LA reactive extraction systems investigated, the system having sunflower oil, synergist extractant (TOA and Aliquat336) and Butan-2-ol were found to be the most favourable system. The LA distribution coefficient (KD=27.75±0.22) and extraction efficiency (η=97.17±0.54%) were obtained by a system consisting of LA concentration (0.05 [M]), TOA (15%, v/v), Aliquat336 (15%, v/v), solvent ratio (2.5, v/v), phase ratio (1:1, v/v), agitation speed (100 rpm), and stirring time (120 min). The main driving force for this research work on the LA reactive extraction from aqueous solution was to develop a suitable combination of extractants, organic solvents and natural solvents which possesses high affinity towards LA and also has less toxicity towards LA producing microbes.
    Keywords: Green solvents, Synergistic mixture of extractant, Distribution coefficient (KD), Reactive extraction, Lactic acid