Search for: separation-techniques
0.009 seconds
Total 21 records

    A novel approach for microparticle separation based on dielectrophoresis method

    , Article Biomedical Physics and Engineering Express ; Volume 5, Issue 3 , 2019 ; 20571976 (ISSN) Rafiefard, N ; Sasanpour, P ; Fardindoost, S ; Irajizad, A ; Sharif University of Technology
    Institute of Physics Publishing  2019
    A novel approach for particles size separation based on dielectrophoresis (DEP) method is introduced and analyzed both computationally and experimentally. The proposed technique has been utilized for the separation of polystyrene (PS) particles with 8, 6 and 2 μm diameters passing through microchannels with planar electrodes. The performance of the technique has been computationally analyzed using the finite element method (FEM). Considering the structure of the planar electrodes, we propose an approach based on applying an electric potential between one of the global electrodes, and a needle touched the top of the cell suspension. Results of both simulation and experiment show that by... 

    Influence of additives on the morphology of PVDF membranes based on phase diagram: thermodynamic and experimental study

    , Article Journal of Applied Polymer Science ; Volume 135, Issue 21 , 2018 ; 00218995 (ISSN) Mohsenpour, S ; Khosravanian, A ; Sharif University of Technology
    John Wiley and Sons Inc  2018
    In the present study, the morphology of asymmetric poly(vinylidene fluoride) blend membranes which were prepared by the phase inversion method is rationalized by comparing two non-dimensional number represent thermodynamic and kinetic properties of the prepared membrane. These two parameters change phase diagram and demixing rate between solvent and nonsolvent. TiO2 nanoparticles and polyvinylpyrrolidone were used as additives. Hansen solubility parameters of the components are calculated by Van Krevelen method. Furthermore, kinetic and thermodynamic properties of the prepared solutions are determined by drawing phase diagrams and controlling mass transfer rate during precipitation of... 

    Comments on the " A comparative study of chelating and cationic ion exchange resins for the removal of palladium (II) complexes from acidic chloride media"

    , Article Journal of Hazardous Materials ; Volume 229-230 , 2012 , Pages 461-462 ; 03043894 (ISSN) Alahyari, S. A ; Khanchi, A. R ; Outokesh, M ; Tayebi, A ; Sharif University of Technology

    Spiral microchannel with stair-like cross section for size-based particle separation

    , Article Microfluidics and Nanofluidics ; Volume 21, Issue 7 , 2017 ; 16134982 (ISSN) Ghadami, S ; Kowsari Esfahan, R ; Saidi, M. S ; Firoozbakhsh, K ; Sharif University of Technology
    Springer Verlag  2017
    Particle separation has a variety of applications in biology, chemistry and industry. Among them, circulating tumor cells (CTCs) separation has drawn significant attention to itself due to its high impact on both cancer diagnosis and therapeutics. In recent years, there has been growing interest in using inertial microfluidics to separate micro/nano particles based on their sizes. This technique offers label-free, high-throughput and efficient separation and can be easily fabricated. However, further improvements are needed for potential clinical applications. In this study, a novel inertial separation technique using spiral microchannel having stair-like cross section is introduced. The... 

    Improvement of size-based particle separation throughput in slanted spiral microchannel by modifying outlet geometry

    , Article Electrophoresis ; Volume 41, Issue 5-6 , February , 2020 , Pages 353-359 Mihandoust, A ; Maleki Jirsaraei, N ; Rouhani, S ; Safi, S ; Alizadeh, M ; Sharif University of Technology
    Wiley-VCH Verlag  2020
    The inertial microfluidic technique, as a powerful new tool for accurate cell/particle separation based on the hydrodynamic phenomenon, has drawn considerable interest in recent years. Despite numerous microfluidic techniques of particle separation, there are few articles in the literature on separation techniques addressing external outlet geometry to increase the throughput efficiency and purity. In this work, we report on a spiral inertial microfluidic device with high efficiency (>98%). Herein, we demonstrate how changing the outlet geometry can improve the particle separation throughput. We present a complete separation of 4 and 6 μm from 10 μm particles potentially applicable to... 

    Separation of speech sources in under-determined case using SCA and time-frequency methods

    , Article 2008 International Symposium on Telecommunications, IST 2008, Tehran, 27 August 2008 through 28 August 2008 ; 2008 , Pages 533-538 ; 9781424427512 (ISBN) Mahdian, R ; Babaiezadeh, M ; Jutten, C ; Sharif University of Technology
    This paper presents a new algorithm for Blind Source Separation (BSS) of Instantaneous speech mixtures in under-determined case. A demixing algorithm which exploits the sparsity of speech signals in the short time Fourier transform (STFT) domain is proposed. This algorithm combines the modified k-means clustering procedure involved in the Line Orientation Separation Technique (LOST) with Smoothed l0-norm minimization (SL0) method. First procedure along with a transformation into a sparse domain tries to estimate the mixing matrix, and the second method tries to extract the sources from the mixtures. Simulation results are presented and compared to the Degenerate Unmixing Estimation Technique... 

    Separability in asymmetric phase-covariant cloning

    , Article Physics Letters, Section A: General, Atomic and Solid State Physics ; Volume 336, Issue 4-5 , 2005 , Pages 278-289 ; 03759601 (ISSN) Rezakhani, A. T ; Siadatnejad, S ; Ghaderi, A. H ; Sharif University of Technology
    Elsevier  2005
    Here, asymmetric phase-covariant quantum cloning machines are defined and trade-off between qualities of their outputs and its impact on entanglement properties of the outputs are studies. In addition, optimal families among these cloners are introduced and also their entanglement properties are investigated. An explicit proof of optimality is presented for the case of qubits, which is based on the no-signaling condition. Our optimality proof can also be used to derive an upper bound on trade-off relations for a more general class of optimal cloners which clone states on a specific orbit of the Bloch sphere. It is shown that the optimal cloners of the equatorial states, as in the case of... 

    Synthesis and characterization of new biopolymeric microcapsules containing DEHPA-TOPO extractants for separation of uranium from phosphoric acid solutions

    , Article Journal of Microencapsulation ; Volume 28, Issue 4 , 2011 , Pages 248-257 ; 02652048 (ISSN) Outokesh, M ; Tayyebi, A ; Khanchi, A ; Grayeli, F ; Bagheri, G ; Sharif University of Technology
    A novel microcapsule adsorbent for separation of uranium from phosphoric acid solutions was developed by immobilizing the di(2-ethylhexyl) phosphoric acid-trioctyl phosphine oxide extractants in the polymeric matrix of calcium alginate. Physical characterization of the microcapsules was accomplished by scanning electron microscopy and thermogravimetric techniques. Equilibrium experiments revealed that both ion exchange and solvent extraction mechanisms were involved in the adsorption of ions, but the latter prevailed in a wider range of acid concentration. According to the results of kinetics study, at low acidity level, the rate controlling step was slow chemical reaction of ions with the... 

    Assessment of the co-elution problem in gas chromatography-mass spectrometry using non-linear optimization techniques

    , Article Chemometrics and Intelligent Laboratory Systems ; Volume 101, Issue 1 , 2010 , Pages 1-13 ; 01697439 (ISSN) Jalali Heravi, M ; Parastar, H ; Sharif University of Technology
    Multivariate curve resolution based on the minimization of an objective function (MCR-FMIN) defined directly from the non-fulfillment of constraints was applied for the first time as a deconvolution method to separate co-eluted gas chromatographic-mass spectrometric (GC-MS) signals. Simulated and real (standard real mixture and limon oil) GC-MS data were used to evaluate the feasibility of this method. The MCR-FMIN solutions have been obtained based on the rotation of principal component analysis (PCA) solutions using the non-linear optimization algorithms. Calculation of the initial values of R rotation matrix using model free analysis methods such as fixed-size moving window-evolving... 

    Rapid and tunable selective adsorption of dyes using thermally oxidized nanodiamond

    , Article Journal of Colloid and Interface Science ; Volume 524 , 2018 , Pages 52-64 ; 00219797 (ISSN) Molavi, H ; Shojaei, A ; Pourghaderi, A ; Sharif University of Technology
    In the present study, capability of nanodiamond (ND) for the adsorption of anionic (methyl orange, MO) and cationic (methylene blue, MB) dyes from aqueous solution was investigated. Employing fourier transform infrared (FTIR) spectroscopy, Boehm titration method and zeta potential, it was found that the simple thermal oxidation of ND at 425 °C, increased the content of carboxylic acid of ND and accordingly the zeta potential of ND decreased considerably. Therefore, a series of oxidized NDs (OND) at various oxidation times and as-received untreated ND (UND) was used as adsorbents of MO and MB. The adsorption experiments exhibited that UND had large adsorption capacity, very fast adsorption... 

    A continuous flow microfluidic device based on contactless dielectrophoresis for bioparticles enrichment

    , Article Electrophoresis ; Volume 39, Issue 3 , 2018 , Pages 445-455 ; 01730835 (ISSN) Rahmani, A ; Mohammadi, A. A ; Kalhor, H. R ; Sharif University of Technology
    Wiley-VCH Verlag  2018
    In recent years, applications of dielectrophoresis-based platforms have been recognized as effective and dependable approach to separate cells and bioparticles, suspended in different carrier fluids, based on particle size and electrical properties. In this study, a microfluidic device was fabricated by an unprecedented electrode pattern, and several experiments were performed to enrich samples including either of yeast, Escherichia coli, or latex particles. A chemical deposition-based method was employed for fabrication of microelectrodes, inducing nonuniform electric field required for dielectrophoresis-based separation. One major advantage of our employed method is low fabrication cost,... 

    Separation of phenolic glycolipids in mycobacterium bovis BCG by reversed-phase high performance liquid chromatography

    , Article Pakistan Journal of Pharmaceutical Sciences ; Volume 22, Issue 2 , 2009 , Pages 145-149 ; 1011601X (ISSN) Salimi, M ; Pourabdi, L ; Zakeri, M ; Abdipour, N ; Sharif University of Technology
    A crude phenolic glycolipid extract from Mycobacterium bovis BCG was fractionated by column chromatography. A reversed-phase high performance liquid chromatography (HPLC) method with UV detection at 275nm was developed for simultaneous detection and separation of phenolic glycolipids (PGLs) in Mycobacterium bovis BCG. This analysis provides a good resolution. Different solvent systems and columns for HPLC were compared. A system composed of acetonitrile-water in the ratio of 0→80% at a flow rate of 0.8 mL/min and C8 analytical column were found to be optimum for HPLC of the phenolic glycolipids. This simple method is therefore appropriate to purify these compounds present in M. bovis extract... 

    A new nonlinear sparse component analysis for a biologically plausible model of neurons

    , Article Neural Computation ; Volume 31, Issue 9 , 2019 , Pages 1853-1873 ; 08997667 (ISSN) Heidarieh, S. M ; Jahed, M ; Ghazizadeh, A ; Sharif University of Technology
    MIT Press Journals  2019
    It is known that brain can create a sparse representation of the environment in both sensory and mnemonic forms (Olshausen & Field, 2004). Such sparse representation can be combined in downstream areas to create rich multisensory responses to support various cognitive and motor functions. Determining the components present in neuronal responses in a given region is key to deciphering its functional role and connection with upstream areas. One approach for parsing out various sources of information in a single neuron is by using linear blind source separation (BSS) techniques. However, applying linear techniques to neuronal spiking activity is likely to be suboptimal due to inherent and... 

    Simultaneous separation of H2S and CO2 from natural gas by hollow fiber membrane contactor using mixture of alkanolamines

    , Article Journal of Membrane Science ; Volume 377, Issue 1-2 , July , 2011 , Pages 191-197 ; 03767388 (ISSN) Hedayat, M ; Soltanieh, M ; Mousavi, S. A ; Sharif University of Technology
    In the present work we studied the use of a membrane contactor system for simultaneous absorption of H2S and CO2 from a gas mixture similar to natural gas. MDEA solution and mixtures of MDEA/DEA and MDEA/MEA were used as absorbent liquid. PVDF and PSf hollow fiber membranes were used in the membrane contactor modules. Design of experiments were carried out by Taguchi method in a manner that a systematical investigation of the effect of operational parameters (temperature, pressure, gas and liquid flow rates, absorbent concentration and acid gas content of the feed), in addition to the effect of membrane material and absorbent liquid, was implemented on process performance parameters... 

    Automated trace determination of earthy-musty odorous compounds in water samples by on-line purge-and-trap-gas chromatography-mass spectrometry

    , Article Journal of Chromatography A ; Volume 1136, Issue 2 , 2006 , Pages 170-175 ; 00219673 (ISSN) Salemi, A ; Lacorte, S ; Bagheri, H ; Barceló, D ; Sharif University of Technology
    An automated technique based on purge-and-trap coupled to gas chromatography with mass spectrometric detection has been developed and optimized for the trace determination of five of the most important water odorants; 2-isopropyl-3-methoxypyrazine, 2-isobutyl-3-methoxypyrazine, 2-methylisoborneol, 2,4,6-trichloroanisole and geosmin. The extraction method was absolutely solvent-free. Analytes were purged from 20 ml of water sample containing sodium chloride at room temperature by a flow of He and trapped on a Tenax sorbent. The desorption step was performed with helium and temperature programming and desorbed analytes were directly transferred to a gas chromatograph coupled to a mass... 

    Applying ultrasonic fields to separate water contained in medium-gravity crude oil emulsions and determining crude oil adhesion coefficients

    , Article Ultrasonics Sonochemistry ; Volume 70 , 2021 ; 13504177 (ISSN) Sadatshojaie, A ; Wood, D. A ; Jokar, S. M ; Rahimpour, M. R ; Sharif University of Technology
    Elsevier B.V  2021
    Separating produced water is a key part of production processing for most crude oils. It is required for quality reasons, and to avoid unnecessary transportation costs and prevent pipework corrosion rates caused by soluble salts present in the water. A complicating factor is that water is often present in crude oil in the form of emulsions. Experiments were performed to evaluate the performance of ultrasonic fields in demulsifying crude oil emulsions using novel pipe-form equipment. A horn-type piezoelectric ultrasonic transducer with a frequency of 20 kHz and power ranging from 80 W to 1000 W was used for experimental purposes. The influences of the intensity of ultrasonic fields,... 

    Prediction of the selectivity coefficient of ionic liquids in liquid-liquid equilibrium systems using artificial neural network and excess Gibbs free energy models

    , Article Particulate Science and Technology ; Volume 28, Issue 4 , 2010 , Pages 379-391 ; 02726351 (ISSN) Dehnavi, S. M ; Pazuki, G ; Goodarznia, I ; Vossoughi, M ; Sharif University of Technology
    In this work, the selectivity coefficients of ionic liquids in liquid-liquid systems were correlated and predicted by the NRTL, UNIQUAC, and Wilson-NRF Gibbs free energy models and also by an artificial neural network system. The three thermodynamic models need six binary interaction parameters between solvent(1)-solvent(2), solvent(1)-ionic liquid, and solvent(2)-ionic liquid pairs in obtaining the selectivity of ionic liquid in liquid-liquid systems. Also, the selectivity coefficients of ionic liquids were modeled using an artificial neural network system. In the proposed neural network system, temperature, molecular weight of ionic liquid, molecular weight of solvents, and mole fractions... 

    Characterization of volatile components of Iranian saffron using factorial-based response surface modeling of ultrasonic extraction combined with gas chromatography-mass spectrometry analysis

    , Article Journal of Chromatography A ; Volume 1216, Issue 33 , 2009 , Pages 6088-6097 ; 00219673 (ISSN) Jalali Heravi, M ; Parastar, H ; Ebrahimi Najafabadi, H ; Sharif University of Technology
    The volatile components of Iranian saffron were extracted using ultrasonic solvent extraction (USE) technique and then were separated and detected by gas chromatography-mass spectrometry (GC-MS). Variables affecting the extraction procedure were screened by using a 25-1 fractional factorial design and among them; sample amount, solvent volume, solvent ratio and extraction time were optimized by applying a rotatable central composite design (CCD). The optimum values of factors were: 2.38 g sample, 29.04 mL solvent, 69.23% MeOH solvent ratio and 71.8 min for the extraction time. Forty constituents were identified for Iranian saffron by GC-MS representing 90% of the total peak area. The major... 

    Development of a method for analysis of Iranian damask rose oil: combination of gas chromatography-mass spectrometry with Chemometric techniques

    , Article Analytica Chimica Acta ; Volume 623, Issue 1 , 8 August , 2008 , Pages 11-21 ; 00032670 (ISSN) Jalali Heravi, M ; Parastar, H ; Sereshti, H ; Sharif University of Technology
    Gas chromatography-mass spectrometry (GC-MS) combined with Chemometric resolution techniques were proposed as a method for the analysis of volatile components of Iranian damask rose oil. The essential oil of damask rose was extracted using hydrodistillation method and analyzed with GC-MS in optimized conditions. A total of 70 components were identified using similarity searches between mass spectra and MS database. This number was extended to 95 components with concentrations higher than 0.01% accounting for 94.75% of the total relative content using Chemometric techniques. For the first time in this work, an approach based upon subspace comparison is used for determination of the chemical... 

    A novel needle trap sorbent based on carbon nanotube-sol-gel for microextraction of polycyclic aromatic hydrocarbons from aquatic media

    , Article Analytica Chimica Acta ; Volume 683, Issue 2 , January , 2011 , Pages 212-220 ; 00032670 (ISSN) Bagheri, H ; Ayazi, Z ; Aghakhani, A ; Sharif University of Technology
    A new type of composite material based on carbon nanotubes (CNTs) and sol-gel chemistry was prepared and used as sorbent for needle trap device (NTD). The synthesized composite was prepared in a way to disperse CNTs molecules in a sol-gel polymeric network. CNT/silica composites with different CNT doping levels were successfully prepared, and the extraction capability of each composite was evaluated. Effects of surfactant and the oxidation duration of CNTs on the extraction efficiency of synthesized composites were also investigated. The applicability of the synthesized sorbent was examined by developing a method based on needle trap extraction (NTE) and gas chromatography mass spectrometry...