Search for: methyl-esters
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    Characterization and determination of fatty acids in fish oil using gas chromatography-mass spectrometry coupled with chemometric resolution techniques

    , Article Journal of Chromatography A ; Volume 1024, Issue 1-2 , 2004 , Pages 165-176 ; 00219673 (ISSN) Jalali Heravi, M ; Vosough, M ; Sharif University of Technology
    Elsevier  2004
    Characterization and determination of a complex mixture of fatty acid methyl esters was performed for commercial fish oil using two-dimensional GC-MS data coupled with resolution techniques. Various principle component analysis methods such as significant factor analysis and fixed size moving window evolving factor analysis were used for the number of factors, zero concentration and selective regions. Then, the convoluted chromatograms were resolved into pure chromatograms and mass spectra using heuristic evolving latent projections (HELP) method. Fatty acids of C16:1ω7, C18:4ω3, C18:1ω11, C18:1ω9, C18:0, C20:2ω6, C20:1ω9, C 22:1ω11, C22:1ω9 and C24:1ω9 were resolved and identified by using... 

    Novel approach for liquid-liquid phase equilibrium of biodiesel (canola and sunflower) + glycerol + methanol

    , Article Industrial and Engineering Chemistry Research ; Vol. 53, issue. 2 , 2014 , pp. 855-864 ; ISSN: 08885885 Hakim, M ; Abedini Najafabadi, H ; Pazuki, G ; Vossoughi, M ; Sharif University of Technology
    In this study, a novel experimental approach was used to overcome the lack of phase equilibrium information to obtain data that is more applicable to industrial situations. Liquid-liquid equilibrium (LLE) data, tie-lines, and phase boundaries were carried out for two systems of canola oil methyl esters (containing 1 wt % KOH) + glycerol + methanol and sunflower oil methyl esters (containing 1 wt % KOH) + glycerol + methanol at three different temperatures (303.15, 313.15, and 323.15 K). The quality of data was also ascertained using Othmer-Tobias correlations. The experimental LLE data was also correlated by the nonrandom two-liquid (NRTL) and the Wilson-NRF Gibbs free energy models. The... 

    Enzymatic synthesis of amoxicillin with immobilized penicillin G acylase

    , Article Scientia Iranica ; Volume 17, Issue 1 C , 2010 , Pages 106-113 ; 10263098 (ISSN) Alemzadeh, I ; Borghei, G ; Vafi, L ; Roostaazad, R ; Sharif University of Technology
    The synthesis of amoxicillin with immobilized penicillin G acylase (PGA) in aqueous medium was investigated. The parameters studied were: time course of amoxicillin production, concentration of substrates: hydroxyphenylglycine methyl ester (HPGM) and 6-aminopeicillanic acid (6-APA) and the. effect of enzyme (PGA) content and pH, under variable and constant conditions and temperature variations. In the study of two substrate concentration on amoxicillin production, impressive results were obtained for a 1/3 ratio of 6-amino penicillanic acid (6-APA) and hydroxyl-phenylglycine methyl ester (HPGM). The. synthesis of amoxicillin was preferable at constant pH rather than a variable one. Other... 

    Highly efficient Michael addition reaction of amines catalyzed by silica-supported aluminum chloride

    , Article Synthetic Communications ; Volume 39, Issue 6 , 2009 , Pages 1109-1119 ; 00397911 (ISSN) Saidi, M. R ; Pourshojaei, Y ; Aryanasab, F ; Sharif University of Technology
    Aliphatic and aromatic amines undergo smooth nucleophilic addition to α,β-unsaturated compounds in the presence of a catalytic amount of silica-supported aluminum chloride at 60°C and under solvent-free conditions to produce the corresponding β-amino compounds in excellent yields. This method is simple and convenient and works efficiently under mild conditions. This catalyst can used again without losing its activity three times. Copyright © Taylor & Francis Group, LLC  

    Azahomofullerenes as new n-type acceptor materials for efficient and stable inverted planar perovskite solar cells

    , Article ACS Applied Materials and Interfaces ; Volume 13, Issue 17 , 2021 , Pages 20296-20304 ; 19448244 (ISSN) Chavan, R. D ; Prochowicz, D ; Bończak, B ; Fiałkowski, M ; Tavakoli, M. M ; Yadav, P ; Patel, M. J ; Gupta, S. K ; Gajjar, P. N ; Hong, C. K ; Sharif University of Technology
    American Chemical Society  2021
    Fullerene derivatives with a strong electron-accepting ability play a crucial role in enhancing both the performance and stability of perovskite solar cells (PSCs). However, most of the used fullerene molecules are based on [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), which limits the device performance due to difficulties in preparing high-quality and uniform thin films. Herein, solution-processable azahomofullerene (AHF) derivatives (abbreviated as AHF-1 and AHF-2) are reported as novel and effective electron-transport layers (ETLs) in p-i-n planar PSCs. Compared to the control PCBM ETL-based PSCs, the devices based on AHFs exhibit higher photovoltaic performances, which is... 

    Effects of physicochemical characteristics of magnetically recoverable biocatalysts upon fatty acid methyl esters synthesis from oils

    , Article Renewable Energy ; Volume 116 , 2018 , Pages 613-622 ; 09601481 (ISSN) Esmaeilnejad Ahranjani, P ; Kazemeini, M ; Singh, G ; Arpanaei, A ; Sharif University of Technology
    Elsevier Ltd  2018
    This study reports the importance of physicochemical characteristics of the core-shell structured polymer-coated Fe3O4 cluster@SiO2 nanocomposite particles for designing the biocatalysts used for transesterification of soybean oil. To demonstrate this issue, two different types of polymer molecules such as polyethylenimine (PEI) and polyacrylic acid (PAA) each with two different molecular weights are employed. The highest fatty acid methyl esters (FAMEs) synthesis yield values are achieved by the lipases immobilized onto the low- and high-molecular-weight PEI-coated particles as compared to those of the low- and high-molecular-weight PAA-coated particles (i.e., ∼64.8% and ∼73.1% versus... 

    Interactions of coinage metal clusters with histidine and their effects on histidine acidity; Theoretical investigation

    , Article Organic and Biomolecular Chemistry ; Volume 10, Issue 47 , Oct , 2012 , Pages 9373-9382 ; 14770520 (ISSN) Javan, M. J ; Jamshidi, Z ; Tehrani, Z. A ; Fattahi, A ; Sharif University of Technology
    Understanding the nature of interaction between metal nanoparticles and biomolecules such as amino acids is important in the development and design of biosensors. In this paper, binding of M3 clusters (M = Au, Ag and Cu) with neutral and anionic forms of histidine amino acid was studied using density functional theory (DFT-B3LYP). It was found that the interaction of histidine with M3 clusters is governed by two major bonding factors: (a) the anchoring N-M and O-M bonds and (b) the nonconventional N-H⋯M and O-H⋯M hydrogen bonds. The nature of these chemical bonds has been investigated based on quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analyses. In the next... 

    Second-order calibration for the determination of fatty acids in pomegranate seeds by vortex-assisted extraction-dispersive liquid-liquid micro-extraction and gas chromatography-mass spectrometry

    , Article RSC Advances ; Volume 5, Issue 15 , 2015 , Pages 11633-11643 ; 20462069 (ISSN) Ahmadvand, M ; Sereshti, H ; Parastar, H ; Sharif University of Technology
    Multivariate curve resolution-alternating least squares (MCR-ALS) as a second-order calibration algorithm was proposed for the simultaneous analysis of eighteen fatty acid methyl esters (FAMEs) in a standard mixture and pomegranate seed sample using vortex-assisted extraction-dispersive liquid-liquid microextraction (VAE-DLLME), followed by gas chromatography-mass spectrometry (GC-MS). The chemometric resolution, identification and quantification of the target FAMEs in the standard mixture and real sample (i.e., the pomegranate seed) were carried out successfully in the presence of some uncalibrated interferences. The lack of fit (LOF) and reverse match factor (RMF) were used for the... 

    Effects of short term and long term Extremely Low Frequency Magnetic Field on depressive disorder in mice: Involvement of nitric oxide pathway

    , Article Life Sciences ; Volume 146 , 2016 , Pages 52-57 ; 00243205 (ISSN) Madjid Ansari, A ; Farzam Pour, S ; Sadr, A ; Shekarchi, B ; Majid Zadeh, A. K ; Sharif University of Technology
    Elsevier Inc 
    Aims Previous reports on the possible effects of Extremely Low Frequency Magnetic Fields (ELF MF) on mood have been paradoxical in different settings while no study has yet been conducted on animal behavior. In addition, it was shown that ELF MF exposure makes an increase in brain nitric oxide level. Therefore, in the current study, we aimed to assess the possible effect(s) of ELF MF exposure on mice Forced Swimming Test (FST) and evaluate the probable role of the increased level of nitric oxide in the observed behavior. Main methods Male adult mice NMRI were recruited to investigate the short term and long term ELF MF exposure (0.5 mT and 50 Hz, single 2 h and 2 weeks 2 h a day). Locomotor... 

    Green biodiesel production from various plant oils using nanobiocatalysts under different conditions

    , Article Bioenergy Research ; Volume 13, Issue 2 , 2020 , Pages 552-562 Esmaeilnejad Ahranjani, P ; Kazemeini, M ; Arpanaei, A ; Sharif University of Technology
    Springer  2020
    The lipase-immobilized polyethyleneimine (PEI)- and polyacrylic acid (PAA)–coated magnetic silica nanocomposite particles (L-PEI-MS and L-PAA-MS, respectively) were prepared and applied at various transesterification reaction conditions. The reactions were carried out with soybean, sunflower, canola, and palm oils along with methanol or ethanol in the solvent-free and n-hexane systems. The highest fatty acid methyl ester (FAME) and fatty acid ethyl ester (FAEE) synthesis yields were obtained from the transesterification of palm oil, i.e., almost 7.7–10.2% higher than other oils. At the constant reaction conditions, the application of ethanol leads to higher (6.0–8.7%) reaction yields in... 

    Direct transesterification of wet microalgae to biodiesel using phosphonium carboxylate ionic liquid catalysts

    , Article Biomass and Bioenergy ; Volume 150 , 2021 ; 09619534 (ISSN) Malekghasemi, S ; Kariminia, H. R ; Plechkova, N. K ; Ward, V. C. A ; Sharif University of Technology
    Elsevier Ltd  2021
    In this study, four types of tetrabutylphosphonium carboxylate ionic liquids (ILs) were synthesized and used for a one-pot transesterification of wet Chlorella vulgaris (C. vulgaris) microalgae into fatty acid methyl esters (FAME) in the presence of methanol, as well as refined oils (sunflower, canola, and corn oil). The resulting process removed the need for complete drying and lipid extraction steps typically needed for biodiesel production from microalgae. The leading candidate ionic liquid catalyst, tetrabutylphosphonium formate ([P4444][For]), was further optimized using response surface methodology to minimize material consumption, increase water compatibility, reduce processing time... 

    The role of co-solvents in improving the direct transesterification of wet microalgal biomass under supercritical condition

    , Article Bioresource Technology ; Volume 193 , October , 2015 , Pages 90-96 ; 09608524 (ISSN) Abedini Najafabadi, H ; Vossoughi, M ; Pazuki, G ; Sharif University of Technology
    Elsevier Ltd  2015
    In this research, direct conversion of wet algal biomass into biodiesel using supercritical methanol was studied. In this process, microalgal lipids simultaneously was extracted and converted to biodiesel under high pressure and temperature conditions without using any catalyst. Several experiments have been performed to optimize the methanol amount and it has been revealed that the best performance was achieved by using methanol/wet biomass ratio of 8:1. The effect of using various co-solvents in increasing the efficiency of the supercritical process was investigated. It has been shown that hexane was the most effective co-solvent and its optimal ratio respect to wet biomass was 6:1. The...