Loading...
Search for:
chemical-compound
0.011 seconds
Total 36 records
Storage of Information in Chemical Compounds
, M.Sc. Thesis Sharif University of Technology ; Shafiee, Afshin (Supervisor)
Abstract
Regarding the notable progress in communication and competition theories as well as natural sciences, the study of the concepts of information has displayed more attention in recent years.Information, entropy and energy are interrelated concepts. In one hand one can infer that entropy is a quantitation measure of information and on the other hand systems which carry information can accumulated energy.Here, we are going to survey the qualitation as well as quantitation aspects of information with concentration on the behavior of chemical agents as information processors
Estimation of the Compressive Strength of GGBFS based Alkali-Activated Concrete
, M.Sc. Thesis Sharif University of Technology ; Toufigh, Vahab (Supervisor)
Abstract
Ground granulated blast furnace slag (GGBFS) based alkali-activated concrete (GAAC) is one of the eco-friendly alternatives of traditional concrete, which uses industrial byproducts instead of ordinary Portland cement (OPC). Besides environmental benefits, substituting OPC concrete with GAAC has some economic advantages, while it successfully meets the concrete structural requirements in both mechanical and durability characteristics. Despite this fact, employing GAAC in the construction industry has been limited due to a lack of standard mix design code.This study aims to develop an accurate prediction model for the compressive strength of GAAC by employing the most appropriate machine...
Effect of Chemical Composition on Atomic Structure and Mechanical Properties of Mg-Zn Glass Alloys Using Molecular Dynamics Simulation
, M.Sc. Thesis Sharif University of Technology ; Tavakoli, Rohollah (Supervisor)
Abstract
In this research, Mg-Zn bulk metallic glasses have been investigated using molecular dynamics simulation. In order to study the structure of this alloy, coordination number, short and medium order of chemical range, Voronoi analysis, glass conversion temperature and atomic pair distribution function have been used. According to the results, the full icosahedral structure with IS connection type in comparison with other structures has an essential role in the stability of the system during cooling and creating medium-scale areas. The results show that the ability to form glass depends on the chemical composition and cooling rate. In this research, the cooling rate is considered to be 1011 K/s...
Triethylamine removal using biotrickling filter (BTF): effect of height and recirculation liquid rate on BTFs performance
, Article International Journal of Environmental Science and Technology ; Volume 14, Issue 8 , 2017 , Pages 1615-1624 ; 17351472 (ISSN) ; Sotoudeheian, S ; Bayat, R ; Sharif University of Technology
Center for Environmental and Energy Research and Studies
2017
Abstract
This study investigated the removal of triethylamine using a biotrickling filter. The influence of affecting parameters, such as height and recirculation liquid rate (VL) on contaminant removal efficiency, was examined in detail. The results demonstrated that in the constant empty bed residence time (EBRT), when VL was increased, the removal efficiency (RE) increased. Also, for a specific VL, increasing EBRT could also increase RE values. However, it seems that an increasing VL is a more cost-effective way to enhance RE as compared to an increasing EBRT. The obtained outcomes represented that for a constant EBRT, an increase in inlet loading (IL) could decrease RE. For lower ILs, the removal...
Terahertz time domain spectroscopy for mixture detection: A quantitative study
, Article 4th International Conference on Millimeter-Wave and Terahertz Technologies, MMWaTT 2016, 20 December 2016 through 22 December 2016 ; 2017 , Pages 17-19 ; 21570965 (ISSN); 9781509054145 (ISBN) ; Yahyaei, B ; Kouhanestani, M. K ; Mousavi, M ; Darbani, M. R ; Majde, A. E ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
Terahertz spectroscopy is a useful and an efficient method for detection of pure materials and also mixture compounds. In the present study the terahertz spectra of the α-lactose, high explosives RDX and also the binary mixture of mentioned materials has been obtained in the transition mode. The obtained spectra of the pure materials were in a very good agreement with literatures in the range of 0.1 to 1.5 terahertz. The spectra of mixture samples which show the specific fingerprint characters of each component, declare that terahertz spectroscopy can be used effectively for the detection of explosives and chemical compounds even in the mixture samples. © 2016 IEEE
Superhydrophobic surfaces with a dual-layer micro- and nanoparticle coating for drag reduction
, Article Energy ; Volume 125 , 2017 , Pages 1-10 ; 03605442 (ISSN) ; Moosavi, A ; Nouri Borujerdi, A ; Daeian, M. A ; Vafaeinejad, S ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
We propose a facile and cost effective method for fabricating superhydrophobic surfaces with significant drag reduction in a wide velocity range. A dual structure superhydrophobic aluminum surface with a hydrophobic Al2O3micro- and nanoparticle coating and also another superhydrophobic surface with a nanoparticle layer coating are fabricated. Then, the resulted drag from each of these surfaces is measured carefully in different velocities and compared with the drag of the as-received aluminum surface. Our results reveal that the surface with the dual structure experiences drag reduction in a wider velocity range compared with the nanoparticle coated sample. Drag reduction of the dual...
Supercritical synthesis and in situ deposition of PbS nanocrystals with oleic acid passivation for quantum dot solar cells
, Article Materials Chemistry and Physics ; Volume 156 , 2015 , Pages 163-169 ; 02540584 (ISSN) ; Simchi, A ; Aashuri, H ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Colloidal quantum dot solar cells have recently attracted significant attention due to their low-processing cost and surging photovoltaic performance. In this paper, a novel, reproducible, and simple solution-based process based on supercritical fluid toluene is presented for in situ growth and deposition PbS nanocrystals with oleic-acid passivation. A lead precursor containing sulfur was mixed with oleic acid in toluene and processed in a supercritical fluid condition at different temperatures of 140, 270 and 330 °C for 20 min. The quantum dots were deposited on a fluorine-doped tin oxide glass substrate inside the supercritical reactor. Transmission electron microscopy, X-ray diffraction,...
Spectrophotometric determination of sulfide based on peroxidase inhibition by detection of purpurogallin formation
, Article Ecotoxicology and Environmental Safety ; Volume 91 , 2013 , Pages 117-121 ; 01476513 (ISSN) ; Kariminia, H. R ; Roosta Azad, R ; Sharif University of Technology
2013
Abstract
This paper presents a new method for spectrophotometirc detection of sulfide applying fungal peroxidase immobilized on sodium alginate. The sensing scheme was based on decrease of the absorbance of the orange compound, purpurogallin produced from pyrogallol and H2O2 as substrates, due to the inhibition of peroxidase by sulfide. Absorbance of purpurogallin was detected at 420nm by using a spectrophotometer. The proposed method could successfully detect the sulfide in the concentration range of 0.6-7.0μM with a detection limit of 0.4μM. The kinetic parameters of Michaelis-Menten with and without sulfide were also calculated. Possible inhibition mechanism of peroxidase by sulfide was deduced...
Seasonal trends, chemical speciation and source apportionment of fine PM in Tehran
, Article Atmospheric Environment ; Volume 153 , 2017 , Pages 70-82 ; 13522310 (ISSN) ; Hosseini, V ; Zare Shahne, M ; Bigdeli, M ; Lai, A ; Schauer, J. J ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
Frequent air pollution episodes have been reported for Tehran, Iran, mainly because of critically high levels of fine particulate matter (PM2.5). The composition and sources of these particles are poorly known, so this study aims to identify the major components and heavy metals in PM2.5along with their seasonal trends and associated sources. 24-hour PM2.5samples were collected at a main residential station every 6 days for a full year from February 2014 to February 2015. The samples were analyzed for ions, organic carbon (including water-soluble and insoluble portions), elemental carbon (EC), and all detectable elements. The dominant mass components, which were determined by means of...
Reinforced polydiphenylamine nanocomposite for microextraction in packed syringe of various pesticides
, Article Journal of Chromatography A ; Volume 1222 , January , 2012 , Pages 13-21 ; 00219673 (ISSN) ; Ayazi, Z ; Es'haghi, A ; Aghakhani, A ; Sharif University of Technology
2012
Abstract
Reinforced polydiphenylamine (PDPA) nanocomposite was synthesized by oxidation of diphenylamine in 4molL-1 sulfuric acid solution containing a fixed amount of carbon nanotubes (CNTs) in the presence of cetyltrimethylammonium bromide (CTAB). The surface characteristic of PDPA and PDPA/CNT nanocomposites was investigated using scanning electron microscopy (SEM). The prepared PDPA/CNT nanocomposite was used as an extraction medium for microextraction in packed syringe (MEPS) of selected pesticides from aquatic environment. The effect of CNT doping level and the presence of surfactant on the extraction capability of nanocomposite was investigated and it was revealed that when 4% (w/w) of CNT in...
Prediction of standard enthalpy of combustion of pure compounds using a very accurate group-contribution-based method
, Article Energy and Fuels ; Volume 25, Issue 6 , April , 2011 , Pages 2651-2654 ; 08870624 (ISSN) ; Mirkhani, S. A ; Tofangchi Mahyari, A. R ; Sharif University of Technology
2011
Abstract
The artificial neural network-group contribution (ANN-GC) method is applied to estimate the standard enthalpy of combustion of pure chemical compounds. A total of 4590 pure compounds from various chemical families are investigated to propose a comprehensive and predictive model. The obtained results show the squared correlation coefficient (R 2) of 0.999 99, root mean square error of 12.57 kJ/mol, and average absolute deviation lower than 0.16% for the estimated properties from existing experimental values
Prediction of absolute entropy of ideal gas at 298 K of pure chemicals through GAMLR and FFNN
, Article Energy Conversion and Management ; Volume 52, Issue 1 , 2011 , Pages 630-634 ; 01968904 (ISSN) ; Bagheri, M ; Ghaniyari-Benis, S ; Aslebagh, R ; Kamaloo, E ; Sharif University of Technology
2011
Abstract
Thermodynamical optimization for energy conversion system can be performed by decreasing entropy generation. For calculation of entropy, we need to know entropy of ideal gases at 298 K as a reference point. Entropy is a thermodynamic quantity which is not easily measured and prediction of entropy by molecular structures for new designed molecules may be a challenge. An easy and accurate equation for prediction of absolute entropy of pure ideal gas at 298 K was introduced for the first time based on the quantitative structure property relationship (QSPR) approach. Thousand seven hundred pure chemical compounds and 3224 molecular descriptors were used for finding this easy equation by genetic...
Oxidative desulfurization of simulated light fuel oil and untreated kerosene
, Article Fuel Processing Technology ; Volume 90, Issue 3 , 2009 , Pages 435-445 ; 03783820 (ISSN) ; Kiaei, Z ; Sobati, M.A ; Sharif University of Technology
2009
Abstract
An experimental investigation was conducted on the oxidative desulfurization of model sulfur compounds such as dibenzothiophene and benzothiophene in toluene as a simulated light fuel oil with a mixture of hydrogen peroxide as the oxidant and various acids as the catalyst. The influences of various parameters including reaction temperature (T), acid to sulfur molar ratio (Acid/S), oxidant to sulfur molar ratio (O/S), type of acid, and the presence of sodium tungstate and commercial activated carbon as a co-catalyst on the fractional conversion of the model sulfur compounds were investigated. The experimental data obtained were used to determine the reaction rate constant of the model sulfur...
Optimization of carbohydrate productivity of Spirulina microalgae as a potential feedstock for bioethanol production
, Article International Journal of Environmental Science and Technology ; Volume 16, Issue 3 , 2019 , Pages 1303-1318 ; 17351472 (ISSN) ; Baghdadi, M ; Torang, A ; Sarkhosh, S ; Sharif University of Technology
Center for Environmental and Energy Research and Studies
2019
Abstract
The main goal of this research is to use the biomass productivity, carbohydrate content, and carbohydrate productivity as useful responses for optimization of macronutrients concentrations (K2HPO4, NaHCO3, and NaNO3) in cultivation of Spirulina microalgae as a feedstock for bioethanol production. In this study, individual and synergistic effects of medium components on the mentioned responses were investigated. The culture medium was optimized using central composite design for achieving the maximize biomass productivity (165 mg L−1 day−1 at K2HPO4: 438 mg L−1, NaHCO3: 15.92 g L−1, and NaNO3: 0.5 g L−1), carbohydrate content (42.0% of dry mass at K2HPO4: 192 mg L−1, NaHCO3: 5.71 g L−1, and...
Modeling and stability analysis of truncated high density lipoprotein (HDL) system using MARTINI coarse grain technique
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) ; Volume 3 A , November , 2013 ; 9780791856215 (ISBN) ; Rouhollahi, A ; Sohrabi, S ; Mehr, S. M. N ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2013
Abstract
Lipoproteins are biochemical compounds containing both proteins and lipids. These particles carry chemicals like cholesterol and triglycerides that are not soluble in aqueous solutions. This paper presents modeling of lipoprotein system using coarse grain molecular dynamics technique and stability analysis of this system in a water solution like blood. A high density lipoprotein (HDL) that consists of two annular monomers is modeled. Also there are lipid bilayers located in center of the rings, so the whole HDL and lipid bilayers are called lipoprotein system. First, all atom model is provided and then coarse-grain model is obtained using MARTINI technique. Modeling of the system in all atom...
MCM-41-SO3H as an efficient reusable nano-ordered heterogeneous catalyst for the synthesis of divers 1- & 5-substituted 1H-tetrazoles
, Article Scientia Iranica ; Volume 26, Issue 3 C , 2019 , Pages 1463-1473 ; 10263098 (ISSN) ; Eslami, M ; Ghadirian, N ; Sharif University of Technology
Sharif University of Technology
2019
Abstract
An improved and efficient method for the synthesis of 1- & 5-substituted 1Htetrazole derivatives was described in the presence of nano-ordered MCM-41-SO3H as an effective heterogeneous catalyst. This metal-free protocol, [2 + 3] cycloaddition of sodium azide to various nitriles or ethyl N-phenyl formimidate intermediate under mild reaction conditions, provides a wide range of 1H-tetrazoles in good to excellent yields. The catalyst was reused five times without significant loss of catalytic activity. © 2019 Sharif University of Technology. All rights reserved
MCM-41-SO3H as an efficient reusable nano-ordered heterogeneous catalyst for the synthesis of divers 1- & 5-substituted 1H-tetrazoles
, Article Scientia Iranica ; Volume 26, Issue 3 C , 2019 , Pages 1463-1473 ; 10263098 (ISSN) ; Eslami, M ; Ghadirian, N ; Sharif University of Technology
Sharif University of Technology
2019
Abstract
An improved and efficient method for the synthesis of 1- & 5-substituted 1Htetrazole derivatives was described in the presence of nano-ordered MCM-41-SO3H as an effective heterogeneous catalyst. This metal-free protocol, [2 + 3] cycloaddition of sodium azide to various nitriles or ethyl N-phenyl formimidate intermediate under mild reaction conditions, provides a wide range of 1H-tetrazoles in good to excellent yields. The catalyst was reused five times without significant loss of catalytic activity. © 2019 Sharif University of Technology. All rights reserved
Kinetic studies of Bisphenol A in aqueous solutions by enzymatic treatment
, Article International Journal of Environmental Science and Technology ; Volume 16, Issue 2 , 2019 , Pages 821-832 ; 17351472 (ISSN) ; Borghei, S. M ; Yaghmaei, S ; Sharif University of Technology
Center for Environmental and Energy Research and Studies
2019
Abstract
Bisphenol A (BPA), which is a major component in the production of various consumer products, is one of the most significant endocrine-disrupting chemicals. In this research, the biocatalytic elimination of Bisphenol A using laccase produced by Phanerochaete chrysosporium was examined and optimized. The response surface methodology was used to study the effect of independent variables such as pH, temperature, initial laccase activity, initial Bisphenol A concentration, and the interactive effects of each variable on the removal of Bisphenol A and residual enzyme activity. Based on response surface plots, the maximum Bisphenol A removal (93%) was detected at a pH value of 8, temperature...
Kinetic investigation of NDMA to UDMH hydrogenation on a pd/C catalyst
, Article Iranian Journal of Science and Technology, Transaction B: Engineering ; Volume 30, Issue 5 , 2006 , Pages 581-593 ; 03601307 (ISSN) ; Kazemeini, M ; Bozorgmehri, R ; Sharif University of Technology
2006
Abstract
Unsymmetrical dimethyl hydrazine (UDMH) is a strong propellant, which due to its very good physical properties and high power of repellency has been utilized as a liquid fuel for fighter jet engines for so many years. There are different methods for production of this material. One of the more efficient ones which results in higher yields compared to others is the catalytic hydrogenation of Nitroso Dimethylamine (NDMA). In this work hydrogenation of NDMA to UDMH on a 5% Pd/C in aqueous solution of NDMA was studied experimentally. Experiments were carried out in a Semi-batch three phase STR reactor under constant pressure and temperature in the range of 40 to 70°C, pressures of up to 15 bar...
Investigation of photocatalytic performance of TiO2 network and fiber geometries
, Article Desalination and Water Treatment ; Volume 57, Issue 50 , 2016 , Pages 23644-23650 ; 19443994 (ISSN) ; Sadrnezhaad, S. K ; Kheilnejad, A ; Sharif University of Technology
Taylor and Francis Inc
2016
Abstract
In typical photocatalytic processes slurry reactors are used in which catalyst particles have to be separated from the solution after the process ends which means much higher time and costs. Hence, immobilizing process is carried out on the catalyst to overcome this problem. In this work, fiber and network geometries were produced by particle precipitation on substrates. The obtained structures were characterized by XRD, SEM, and Brunauer–Emmett–Teller analyses. Photocatalytic performance of the samples was investigated by methyl orange degradation and also by hydrogen generation from water/methanol splitting. From the SEM images, the size range of the TiO2 particles in the network...