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Synthesis and characterization of molybdenum (VI) complex immobilized on polymeric Schiff base-coated magnetic nanoparticles as an efficient and retrievable nanocatalyst in olefin epoxidation reactions
, Article Applied Organometallic Chemistry ; Volume 34, Issue 3 , 2020 ; Bagherzadeh, M ; Sharif University of Technology
John Wiley and Sons Ltd
2020
Abstract
In this study, a new polymeric functionalized magnetic nanocatalyst containing a molybdenum Schiff base complex was prepared using a few consecutive steps. Poly (methylacrylate)-coated magnetic nanoparticles were synthesized via radical polymerization of methyl acrylate onto modified magnetic nanoparticles followed by the amidation of the methyl ester groups with hydrazine. Polymeric functionalization efficiently provides the advantage that more catalytic units can be grafted on the surface of magnetic nanoparticles. The functionalization process was continued with salicylaldehyde which introduced Schiff base groups on to the surface of the polymeric support. In the final step, the desired...
Immobilized Manganese-porphyrin and Molybdenum-Schiff Base Complexes on Functionalized Magnetic Nanoparticles as Efficient Recyclable Nanocatalysts in Hydrocarbon and Sulfide Oxidation Reactions
, Ph.D. Dissertation Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
In this thesis, functionalized Fe3O4 nanoparticles have been utilized as a support for immobilization of homogeneous catalysts. The catalytic activity of the supported heterogeneous nanocatalysts was investigated in hydrocarbon and sulfide oxidation reactions. In the first part of this research, imidazole functionalized Fe3O4 nanoparticles (Fe3O4@SiO2-Im) were used as a support to anchor manganese porphyrin complex, [MnT(4-OMeP)P]OAc; via axial ligation. Catalytic application of the immobilized manganese porphyrin was studied in oxidation of alkenes and sulfides. To find suitable reaction conditions, the effect of different parameters such as solvent and temperature on immobilization process...
Synthesis, characterization and catalytic activity of supported vanadium Schiff base complex as a magnetically recoverable nanocatalyst in epoxidation of alkenes and oxidation of sulfides
, Article Journal of Organometallic Chemistry ; Volume 897 , 2019 , Pages 200-206 ; 0022328X (ISSN) ; Bahjati, M ; Mortazavi Manesh, A ; Sharif University of Technology
Elsevier B.V
2019
Abstract
A new magnetically separable nanocatalyst was successfully synthesized by immobilizing of vanadyl acetylacetonate complex, [VO(acac)2], onto silica coated magnetite nanoparticles previously functionalized with 3-aminopropyltriethoxysilane (3-APTES) and reacted by 5-bromosalicylaldehyde to form Schiff base moiety. The obtained nanocatalyst was characterized by elemental analysis (CHN), FT-IR spectroscopy, Powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), inductively coupled plasma optical emission spectrometry (ICP-OES) and thermogravimetric analysis (TGA). Eventually, the resulting nanoparticles were used as catalyst for epoxidation of alkenes and...
Manganese(III) porphyrin anchored onto magnetic nanoparticles via “Click” reaction: An efficient and reusable catalyst for the heterogeneous oxidation of alkenes and sulfides
, Article Inorganic Chemistry Communications ; Volume 107 , 2019 ; 13877003 (ISSN) ; Hosseini, M ; Mortazavi Manesh, A ; Sharif University of Technology
Elsevier B.V
2019
Abstract
Oxidation of a variety of organic compounds, using Mn-porphyrin, mesotetrakis(4-hydroxyphenyl)porphyrinatomanganese(III), supported onto functionalized silica-coated magnetic nanoparticles via “Click” reaction has been investigated. The heterogeneous catalyst was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), FT-IR spectroscopy, inductively coupled plasma optical emission spectroscopy (ICP/OES) and energy-dispersive X-ray spectroscopy (EDX). Thermogravimetric analysis (TGA) demonstrated that the prepared catalyst was thermally stable to almost 300 °C, exhibiting high thermostability of the nanocatalyst over a broad range of temperatures. This...
A new model in correlating the activity coefficients of aqueous electrolyte solutions with ion pair formation
, Article Fluid Phase Equilibria ; Volume 261, Issue 1-2 , December , 2007 , Pages 313-319 ; 03783812 (ISSN) ; Taghikhani, V ; Ghotbi, C ; Sharif University of Technology
2007
Abstract
In this work, the Ion Pair Modified Ghotbi-Vera Mean Spherical Approximation (IP-MGV-MSA) model was proposed to correlate the mean ionic activity coefficients (MIAC) for a number of symmetric and asymmetric aqueous electrolyte solutions at 25 °C. The new model is based on the recently proposed MGV-MSA model by Mortazavi-Manesh et al. In the IP-MGV-MSA model, the effects arising from the ion pair formation in the electrolyte solution was taken into account. Also, in the proposed model, while the cation diameter as well as the relative permittivity of water was considered to be dependent on electrolyte concentration, the anion diameter was independent of electrolyte concentration. The results...
Modification of the GV-MSA model in obtaining the activity and osmotic coefficients of aqueous electrolyte solutions
, Article Fluid Phase Equilibria ; Volume 240, Issue 2 , 2006 , Pages 167-172 ; 03783812 (ISSN) ; Taghikhani, V ; Ghotbi, C ; Sharif University of Technology
2006
Abstract
In this work a modified form of the Ghotbi-Vera Mean Spherical Approximation model (MGV-MSA) has been used to correlate the mean ionic activity coefficients (MIAC) for a number of symmetric and asymmetric aqueous electrolyte solutions at 25 °C. In the proposed model the hard sphere as well as the electrostatic contributions to the MIAC and the osmotic coefficient of the previously GV-MSA model has been modified. The results of the proposed model for the MIAC of the electrolyte solutions studied in this work are used to directly calculate the values of the osmotic coefficients without introducing any new adjustable parameter. In the MGV-MSA model the cation diameter as well as the relative...
A new model for predicting activity coefficients in aqueous solutions of amino acids and peptides
, Article Journal of Chemical Thermodynamics ; Volume 35, Issue 1 , 2003 , Pages 101-112 ; 00219614 (ISSN) ; Ghotbi, C ; Taghikhani, V ; Sharif University of Technology
2003
Abstract
A new two-parameter model based on the perturbation of a hard-sphere reference has been developed to correlate the activity coefficients of several amino acids and simple peptides in aqueous solutions. The hard-sphere equation of state used as the reference in the model was proposed recently by Ghotbi and Vera. The perturbation terms coupled with the reference hard-sphere equation of state are attributed to the dispersion forces and the dipole-dipole interactions. The Lennard-Jones and Keesom potential functions are used to represent the dispersion and dipole-dipole interactions, respectively. The results of the new model are compared with those obtained by other models. It is shown that the...
Synthesis of dipyroromethanes in water and investigation of electronic and steric effects in efficiency of olefin epoxidation by sodium periodate catalyzed by manganese tetraaryl and trans disubstituted porphyrin complexes
, Article Journal of Porphyrins and Phthalocyanines ; Volume 23, Issue 6 , 2019 , Pages 671-678 ; 10884246 (ISSN) ; Adineh Jonaghani, M ; Amini, M ; Mortazavi Manesh, A ; Sharif University of Technology
World Scientific Publishing Co. Pte Ltd
2019
Abstract
Condensation of pyrrole with various aldehydes in the presence of BF3•etherate as an acid catalyst in water provides good yield of some dipyrromethanes. Prolongation of the reaction time with aldehydes substituted by electron-donating (mesityl) or electron-withdrawing (2,6-dichlorophenyl) groups on the ortho positions of the phenyl did not lead to decomposition or scrambling. Manganese trans disubstituted porphyrin complexes which derive from various dipyrromethanes and manganese tetraaryl porphyrin complexes including various substituents with different steric and electronic properties show good catalytic activity in epoxidation of alkenes by NaIO4 in the presence of imidazole (ImH). The...
Packet loss replacement in VoIP using a low-order recursive linear prediction method
, Article Canadian Conference on Electrical and Computer Engineering, 8 May 2011 through 11 May 2011 ; May , 2011 , Pages 000292-000295 ; 08407789 (ISSN) ; 9781424497898 (ISBN) ; Ghorshi, S ; Mortazavi, M ; Pasha, S ; Sharif University of Technology
2011
Abstract
In real-time packet-based communication systems, one major problem is misrouted or delayed packets which results in degraded perceived voice quality. If packets are not available on time, the packet is known as lost packet. The easiest task of a network terminal receiver is to replace silence for the duration of lost speech segments. In a high quality communication system, to avoid quality reduction due to packet loss, a suitable method and/or algorithm is needed to replace the missing segments of speech. In this paper, we introduce a low order recursive linear prediction method for replacement of lost speech segment. In this method a normalized least mean square (NLMS) as an adaptive filter...
A simple 2-step purification process of α-amylase from bacillus subtilis: optimization by response surface methodology
, Article International Journal of Biological Macromolecules ; Volume 192 , 2021 , Pages 64-71 ; 01418130 (ISSN) ; Naderi-Manesh, H ; Roostaazad, R ; Yeganeh, S ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Purification of extracellular α-amylase from Bacillus subtilis was carried out via fractional precipitation by acetone and ion exchange chromatography. These steps provide fast precipitation as well as purification of α-amylase to improve enzyme purity, activity and stability. Compared with two-phase methods in which the yield was less than 1, this method resulted in a yield of more than 3. Moreover, 95% of acetone was recovered that enhanced the economy of the downstream process. Using the data provided by 2D electrophoresis, purification was done by a single step ion exchange chromatography. The enzyme exhibited a molecular mass (SDS-PAGE) of 50KD and the pI of 5. Maximum “yield” and...
Perception and Communication of Seismic Risk: Design and Implementation of a Functional Tool
, Article Natural Hazards Review ; Volume 19, Issue 2 , 2018 ; 15276988 (ISSN) ; Mahsuli, M ; Mortazavi, S. M. S ; Sharif University of Technology
American Society of Civil Engineers (ASCE)
2018
Abstract
A web-based system is designed and implemented as a risk communication tool to incentivize the public to take seismic risk mitigation measures. Risk denotes the expected monetary and social losses herein. The objective of this system is to raise the awareness of two audience groups, the general public and decision makers, about significant seismic risk in Iran. To address the general public, the system employs the notion of risk perception to put the results of sophisticated earthquake engineering risk analyses into perspective. The system also treats the epistemic uncertainty of user input due to the public's lack of technical knowledge through the notion of entropy in information theory....
Using RLS adaptive algorithm for packet loss replacement in VOIP
, Article Proceedings of the 2011 International Conference on Image Processing, Computer Vision, and Pattern Recognition, IPCV 2011, 18 July 2011 through 21 July 2011 ; Volume 2 , July , 2011 , Pages 753-756 ; 9781601321916 (ISBN) ; Ghorshi, S ; Mortazavi, M ; Sharif University of Technology
2011
Abstract
In this paper, a low order recursive linear prediction method and recursive least square as an adaptive filter (LP-RLS) are introduced to predict the speech and the excitation signals. In real-time packet-based communication systems, one major problem is misrouted or delayed packets which results in degraded perceived voice quality. If packets are not available on time, the packet is known as lost packet. The easiest task of a network terminal receiver is to replace silence for the duration of lost speech segments. In a high quality communication system, to avoid quality reduction due to packet loss, a suitable method and/or algorithm is needed to replace the missing segments of speech. The...
Reconstruction of tomographic medical images using Kalman filter approach
, Article Proceedings of the 2011 International Conference on Image Processing, Computer Vision, and Pattern Recognition, IPCV 2011, 18 July 2011 through 21 July 2011 ; Volume 1 , July , 2011 , Pages 236-240 ; 9781601321916 (ISBN) ; Ghorshi, S ; Mortazavi, M ; Sharif University of Technology
2011
Abstract
Medical images contain information about vital organic tissues inside of human body and are widely used for diagnoses of disease or for surgical purposes. Image reconstruction is essential for medical images for some applications such as suppression of noise or de-blurring the image to provide images with better quality and contrast. In this paper Kalman filter technique is introduced for medical image reconstruction. This technique is operated in time domain unlike the filtered back projection which operates in frequency domain. Results indicated that as the number of projection increases in both the collected ray sum corrupted by noise and by blurring the quality of reconstructed image...
Evaluation of transformer core contribution to partial discharge electromagnetic waves propagation
, Article International Journal of Electrical Power and Energy Systems ; Volume 83 , 2016 , Pages 40-48 ; 01420615 (ISSN) ; Saniei, M ; Vakilian, M ; Mortazavi, S. S ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
Accurate Partial Discharge (PD) measurement requires the expansion of the measurement frequency range to Ultra High Frequency (UHF) band. For this it is needed to implement modern techniques when monitoring an important element of power system, such as power transformer. Different kind of experimental models, such as insulation defect models, and the complete transformer windings models are used to simulate the partial insulation failure situations which occur in a real transformer. However, since in these models, some kind of simplifications are employed which may result in an electromagnetic waves (EM) propagation pattern different from what exists in a real transformer and encounter...
Audio-visual speech recognition techniques in augmented reality environments
, Article Visual Computer ; Vol. 30, issue. 3 , March , 2014 , pp. 245-257 ; ISSN: 01782789 ; Ghorshi, S ; Mortazavi, M ; Sharif University of Technology
2014
Abstract
Many recent studies show that Augmented Reality (AR) and Automatic Speech Recognition (ASR) technologies can be used to help people with disabilities. Many of these studies have been performed only in their specialized field. Audio-Visual Speech Recognition (AVSR) is one of the advances in ASR technology that combines audio, video, and facial expressions to capture a narrator's voice. In this paper, we combine AR and AVSR technologies to make a new system to help deaf and hard-of-hearing people. Our proposed system can take a narrator's speech instantly and convert it into a readable text and show the text directly on an AR display. Therefore, in this system, deaf people can read the...
Using augmented reality and automatic speech recognition techniques to help deaf and hard of hearing people
, Article ACM International Conference Proceeding Series ; 2012 ; 9781450312431 (ISBN) ; Ghorshi, S ; Mortazavi, M ; Sharif University of Technology
2012
Abstract
Recently, many researches show Augmented Reality (AR) and Automatic Speech Recognition (ASR) can help people with disabilities. In this paper we implement an innovative system for helping deaf people by combining AR, ASR, and AVSR technologies. This system can instantly take narrator's speech and converts it into readable text and shows it directly on AR display. We show that our system's accuracy becomes over 85 percent on average, by using different ASR engines near using an AVSR engine in different noisy environments. We also show in a survey that more than 90 percent of deaf people on average need such system as assistant in portable devices, near using only text or only sign-language...
Combining augmented reality and speech technologies to help deaf and hard of hearing people
, Article Proceedings - 2012 14th Symposium on Virtual and Augmented Reality, SVR 2012 ; 2012 , Pages 174-181 ; 9780769547251 (ISBN) ; Ghorshi, S ; Mortazavi, M ; Sharif University of Technology
2012
Abstract
Augmented Reality (AR), Automatic Speech Recognition (ASR) and Text-to-Speech Synthesis (TTS) can be used to help people with disabilities. In this paper, we combine these technologies to make a new system for helping deaf people. This system can take the narrator's speech and convert it into a readable text and show it directly on AR display. To improve the accuracy of the system, we use Audio-Visual Speech Recognition (AVSR) as a backup for the ASR engine in noisy environments. In addition, we use the TTS system to make our system more usable for deaf people. The results of testing the system show that its accuracy is over 85 percent on average in different places. Also, the result of a...
Investigating the features of a pentagon array for studying Extensive Air Showers
, Article Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment ; Volume 962 , 2020 ; Rastegarzadeh, G ; Mortazavi Moghaddam, S ; Sharif University of Technology
Elsevier B.V
2020
Abstract
We used a method to evaluate angular accuracy for air showers direction recorded by a pentagon array of scintillation detectors. This is achieved by using the coincidences between the air showers recorded by the two sub-arrays. Also, using the CORSIKA code the angular precision of this array and the effect of inherent error on it is obtained at different energies of the primary particles and at different zenith angles. © 2020 Elsevier B.V
Optimal energy sharing for cooperative relaying in a random access network with energy harvesting nodes
, Article IEEE Transactions on Green Communications and Networking ; Volume 5, Issue 1 , 2021 , Pages 231-242 ; 24732400 (ISSN) ; Ashtiani, F ; Mirmohseni, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
In this article, we consider an energy harvesting cooperative network comprised of two data sources and one relay. All nodes transmit based on a predefined slotted Aloha protocol in a random access environment. The main challenge we study is to find how the relay node must share its energy between two sources to optimize their QoS metrics, i.e., throughput and average transmission delay (ATD), separately. Thus, according to our multi-source scenario, we encounter a multi-objective optimization problem (MOOP). Since the relay does not prioritize between two sources, in order to solve the MOOP, we optimize equal-weight linear aggregation of the QoS metrics of two sources. Interestingly, we...
Degradation of humic acids through heterogeneous catalytic ozonation with bone charcoal
, Article Reaction Kinetics, Mechanisms and Catalysis ; Volume 100, Issue 2 , 2010 , Pages 471-485 ; 18785190 (ISSN) ; Asgari, Gh ; Hashemian, S. J ; Moussavi, G ; Sharif University of Technology
2010
Abstract
Catalytic ozonation has recently been used as a new means of contaminant removal from water and wastewater. In this study, bone charcoal (BC), a new catalyst prepared under laboratory conditions, was used to catalyze the ozonation of humic substances (HS) in aqueous solutions. The catalytic effect of bone charcoal and the relevant parameters of this ozonation process (solution pH, temperature, scavenger effect, humic acids concentration and BC dosage) were investigated. In the catalytic ozonation experiments, the degradation kinetics was investigated. The reaction rate and the rate constant were determined. The results showed that using a BC catalyst in the ozonation of HS produced a 1.43-...