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kinetics-parameter
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Total 42 records
The study on microbial polymers: Pullulan and PHB
, Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 28, Issue 1 , 2009 , Pages 13-21 ; 10219986 (ISSN) ; Sharif University of Technology
2009
Abstract
Microbial cells are producers of natural polymers present in plant cells. Production of pullulan (an extracellular microbial polysaccharide) by Aureobasidium pullularia pullulans (P. pullulans) was studied under fermentation conditions, and kinetic parameters were determined. Pullulan formation obeyed a growth and non-growth associated term. PHB (polyhydroxybutyrates) an intracellular biopolymer production by Rastonia eutropha (Alcaligen eutrophus), R. eutropha was studied under different culture media, including synthetic and natural carbon sources. Molasses as a natural carbon source in the culture media presented high efficiency in cell and biopolymer accumulation
Effective point kinetic parameters calculation in Tehran research reactor using deterministic and probabilistic methods
, Article Nuclear Science and Techniques ; Volume 28, Issue 12 , 2017 ; 10018042 (ISSN) ; Abbaspour, A ; Sharif University of Technology
Abstract
The exact calculation of point kinetic parameters is very important in nuclear reactor safety assessment, and most sophisticated safety codes such as RELAP5, PARCS, DYN3D, and PARET are using these parameters in their dynamic models. These parameters include effective delayed neutron fractions as well as mean generation time. These parameters are adjoint-weighted, and adjoint flux is employed as a weighting function in their evaluation. Adjoint flux calculation is an easy task for most of deterministic codes, but its evaluation is cumbersome for Monte Carlo codes. However, in recent years, some sophisticated techniques have been proposed for Monte Carlo-based point kinetic parameters...
Influence of external mass transfer limitation on apparent kinetic parameters of penicillin G acylase immobilized on nonporous ultrafine silica particles
, Article Journal of Bioscience and Bioengineering ; Volume 93, Issue 2 , 2002 , Pages 125-129 ; 13891723 (ISSN) ; Khorasheh, F ; Fazelinia, H ; Sharif University of Technology
Society of Fermentation and Bioengineering
2002
Abstract
Immobilization of enzymes on nonporous supports provides a suitable model for investigating the effect of external mass transfer limitation on the reaction rate in the absence of internal diffusional resistance. In this study, deacylation of penicillin G was investigated using penicillin acylase immobilized on ultrafine silica particles. Kinetic studies were performed within the low-substrate-concentration region, where the external mass transfer limitation becomes significant. To predict the apparent kinetic parameters and the overall effectiveness factor, knowledge of the external mass transfer coefficient, kLa, is necessary. Although various correlations exist for estimation of kLa, in...
Role of the nucleating agent masterbatch carrier resin in the nonisothermal crystallization kinetics of polypropylene
, Article Polymer Journal ; Volume 54, Issue 9 , 2022 , Pages 1127-1132 ; 00323896 (ISSN) ; Marouf, B. T ; Bagheri, R ; Sharif University of Technology
Springer Nature
2022
Abstract
The effect of the nucleating agent masterbatch carrier resin on the nonisothermal crystallization of a pipe-grade polypropylene block copolymer was investigated at three different cooling rates using differential scanning calorimetry (DSC). Bis(3,4-dimethylibenzylidene) sorbitol (DMDBS), a well-known, third-generation sorbitol derivative, was used as a nucleating agent in this study. Crystallization kinetic parameters obtained from DSC cooling curves showed that incorporation of a nucleating agent by means of a masterbatch increased the crystallization rate by approximately two times compared to that of the sample with the same concentration of nucleating agent without the use of a...
Some investigations on protease enzyme production kinetics using bacillus licheniformis BBRC 100053 and effects of inhibitors on protease activity
, Article International Journal of Chemical Engineering ; 2014 ; ISSN: 1687806X ; Yaghmaei, S ; Moghadam, N ; Sadeghein, B ; Sharif University of Technology
Abstract
Due to great commercial application of protease, it is necessary to study kinetic characterization of this enzyme in order to improve design of enzymatic reactors. In this study, mathematical modeling of protease enzyme production kinetics which is derived from Bacillus licheniformis BBRC 100053 was studied (at 37°C, pH 10 after 73 h in stationary phase, and 150 rpm). The aim of the present paper was to determine the best kinetic model and kinetic parameters for production of protease and calculating K i (inhibition constant) of different inhibitors to find the most effective one. The kinetic parameters K m (Michaelis-Menten constant) and V m (maximum rate) were calculated 0.626 mM and...
prediction of Polymeric Membrane Morphology Based on Phase Diagrams for MBR Applications
, M.Sc. Thesis Sharif University of Technology ; Sayf Kordi, Ali Akbar (Supervisor) ; Hemmati, Mahmoud (Supervisor) ; Rekabdar, Fatemeh (Co-Advisor)
Abstract
In this research, we have tried to predict the morphology of the membranes that were prepared by phase inversion method. In this research Polyvinylinedifluoride (PVDF) and dimethylacetamide (DMAc) was used as the polymer and solvent. The affect of titanium oxide (TiO2 ) and polyvinylpyrolidene (PVP) which are respectively an inorganic and an organic additive, on the morphology of the membranes was investigated. Ternary and Quadratic phase diagrams were drawn based on the Flory Huggins theory. The interaction between components was determined and the effect of interactions and molar volumes of polymer, solvent, non-solvent and additives on the binodal line was investigated. To predict...
Development of a software for calculation of kinetic parameters of PWR reactors
, Article International Conference on Nuclear Engineering, Proceedings, ICONE, 17 May 2010 through 21 May 2010, Xi'an ; Volume 2 , 2010 ; 9780791849309 (ISBN) ; Boroushaki, M ; Nuclear Engineering Division ; Sharif University of Technology
2010
Abstract
In this research, new software package for neutronic calculations, especially kinetic parameters of PWR reactors, has been developed. The program used to link the WIMS-D5, BORGES and CITVAP nuclear codes has been written in Visual C# programming language. This software was used for calculation of kinetic parameters of WER-1000 and NOK Beznau reaction The ration (βeff)i/(βeff)corewhich are an important input data for the reactivity accident analysis, were also calculated. The results were compared with final safety analysis report (FSAR) and published documents. Copyright
Impedance spectroscopy study of aluminum electrocrystallization from basic molten salt (AlCl3-NaCl-KCl)
, Article Electrochimica Acta ; Volume 52, Issue 17 , 2007 , Pages 5437-5443 ; 00134686 (ISSN) ; Gobal, F ; Danaee, I ; Mahjani, M. G ; Sharif University of Technology
2007
Abstract
Aluminum electrocrystallization is studied by means of electrochemical impedance spectroscopy (EIS). A model based on random birth and deterministic growth of monolayers is proposed, in which the edges are assumed to follow a propagation law. The high frequency impedance data show charge transfer reaction of AlCl4- reduction while the low frequency features signifies the growth mode of deposits. The inductive response observed in the course of polycrystalline deposition reflects the activation of electrode area while a capacitive loop appears in regular growth. Parameters of impedance model in this system can be calculated from the fitting of experimental data to the Faradaic impedance...
Kinetic Analysis of Pyrolysis Modelling of Non-Charring Polymers
, M.Sc. Thesis Sharif University of Technology ; Farhanieh, Bijan (Supervisor) ; Afshin, Hossein (Co-Advisor)
Abstract
In this research, modelling of pyrolysis in small-scale and a method for calculation of kinetic parameters; activation energy, pre-exponential factor, and model function, have been presented. Calculation of activation energy and frequency factor without any assumption on model function heve been done by presented method. Because, incorrect assumption on model function can be cause to error in estimated values of activation energy and frequency factor.For a bench-scale sample, the heat transfer and mass conservations equations influence the pyrolysis process. In this research for the investigation of kinetic parameter effects, a simple pyrolysis model was presented to predicting the mass flux...
Investigate Kinetic Parameters of L-Asparaginase Ii as Well as its Performance in Organic Reactions and Modifying the Enzyme Through Directed Evolution for Carrying Out Promiscuous Reactions
, M.Sc. Thesis Sharif University of Technology ; Kalhor, Hamid Reza (Supervisor)
Abstract
L-asparaginase II is an amidohydrolase which hydrolyzes L-asparagine to furnish L-aspartic acid and ammonia. The enzyme has played an important role for 40 years in treating cancer in persons with juvenile leukemias or lymphomas. Furthermore, the enzyme has become important in food industries and biosensors technology.In this study, the expression of recombinant L-asparaginase II in E. Coli was optimized and the purification of this enzyme from growth culture was carried out with nickel-charged affinity resin. Afterwards, the activity, and kinetic parameters of purified recombinant L-asparaginase II including Km, kcat, Vmax, and enzyme efficiency were measured.In the next step, random...
A new approach to estimate parameters of a lumped kinetic model for hydroconversion of heavy residue
, Article Fuel ; Vol. 134, issue , 2014 , pp. 343-353 ; Vafajoo, L ; Khorasheh, F ; Sharif University of Technology
Abstract
The effect of complexity level of a lumped kinetic model for heavy residue hydroconversion on estimated values of kinetic parameters was investigated in this work by imposing constraints for the parameter estimation algorithm of a complex six-lump kinetic model and deriving a simpler modified model from the complex model. Kinetic analysis was performed using available experimental data reported in the literature from a study on hydrocracking of Chinese Gudao vacuum residue in a bench-scale reactor using ammonium phosphomolybdate (APM) as a dispersed catalyst. The kinetic models also included coke formation reactions that had previously been ignored by most investigators due to the rather...
Spotlight on kinetic and equilibrium adsorption of a new surfactant onto sandstone minerals: A comparative study
, Article Journal of the Taiwan Institute of Chemical Engineers ; Volume 50 , May , 2015 , Pages 12-23 ; ISSN: 18761070 ; Ghazanfari, M. H ; Rashtchian, D ; Sharif University of Technology
Abstract
This paper presents a state of the art review of adsorption models for a new plant-based surfactant adsorption onto sandstone minerals. The adsorption data at both kinetic and equilibrium modes were obtained from batch experiments. Four adsorption kinetic models, five two-parameter, and six three-parameter equilibrium models were used for interpretation of the obtained data. Among the two and three-parameter isotherm models applied, the Jovanovic and the Khan isotherms showed the best fit, respectively. And the pseudo-second order model presented a better fit than other kinetic models. Finally, a computer-based modeling approach was developed and used for predicting the kinetics of...
Asphaltenes biodegradation under shaking and static conditions
, Article Fuel ; Vol. 117, issue. PART A , 2014 , pp. 230-235 ; ISSN: 00162361 ; Fazaelipoor, M. H ; Ayatollahi, S ; Niazi, A ; Sharif University of Technology
Abstract
In this study the biodegradability of asphaltenes was investigated using four bacterial consortia isolated from oil contaminated soils and sludge. The species in consortium 1 were identified as Pseudomonas aeruginosa and Pseudomonas fluorescens. Consortium 2 contained Citrobacter amalonaticus and Enterobacter cloacae. Consortium 3 contained only one species identified as Staphylococcus hominis, and the species in consortium 4 were identified as Bacillus cereus, and Lysinibacillus fusiformis. Spectrophotometry at 281 nm wavelength was applied to quantify asphaltenes biodegradation. The biodegradation tests were performed in flasks with the initial asphaltenes concentrations of 2, 4, 10, 20,...
Simulation and experimental studies of methane oxidative coupling reaction in a bench scale fixed bed reactor
, Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Volume 35, Issue 15 , Aug , 2013 , Pages 1418-1426 ; 15567036 (ISSN) ; Shahrokhi, M ; Pishvaie, M. R ; Zarrinpashneh, S ; Sharif University of Technology
2013
Abstract
Oxidative coupling of methane in a bench scale fixed bed tubular reactor over Mn-Na2WO4/SiO2 catalyst has been studied. Four kinetic models have been considered for oxidative coupling of methane reactions and compared through experimental data, and the best kinetic model has been selected. For removing the heat of reaction, a molten salt bath system surrounding the reactor tube has been proposed. Effects of different factors, such as CH4/O2 ratio, are investigated through experimental and simulation studies. A good agreement has been observed between simulation and experimental data. The reactor behaviors under isothermal and adiabatic conditions have also been simulated
Spotlight on kinetic and equilibrium adsorption of a new surfactant onto sandstone minerals: A comparative study
, Article Journal of the Taiwan Institute of Chemical Engineers ; Volume 50 , May , 2015 , Pages 12-23 ; 18761070 (ISSN) ; Ghazanfari, M. H ; Rashtchian, D ; Sharif University of Technology
Taiwan Institute of Chemical Engineers
2015
Abstract
This paper presents a state of the art review of adsorption models for a new plant-based surfactant adsorption onto sandstone minerals. The adsorption data at both kinetic and equilibrium modes were obtained from batch experiments. Four adsorption kinetic models, five two-parameter, and six three-parameter equilibrium models were used for interpretation of the obtained data. Among the two and three-parameter isotherm models applied, the Jovanovic and the Khan isotherms showed the best fit, respectively. And the pseudo-second order model presented a better fit than other kinetic models. Finally, a computer-based modeling approach was developed and used for predicting the kinetics of...
Comparison of the membrane morphology based on the phase diagram using PVP as an organic additive and TiO2 as an inorganic additive
, Article Polymer (United Kingdom) ; Volume 97 , 2016 , Pages 559-568 ; 00323861 (ISSN) ; Safekordi, A ; Tavakolmoghadam, M ; Rekabdar, F ; Hemmati, M ; Sharif University of Technology
Elsevier Ltd
Abstract
The morphology of symmetric and asymmetric membranes obtained by precipitation can be rationalized by thermodynamic and kinetic parameters. Such parameters which the former relates to thermodynamic effect and the latter controls the time of separation of the cast solution film immersing in the non-solvent bath from the glass plate were calculated as dimensionless parameters for further analysis. Phase diagram was used to consider the role of thermodynamic. The kinetic properties of the membranes could be investigated by the rate of mass transfer between solvent and non-solvent. By adding additives to the polymer solution the desire for becoming two phase and also viscosity of the solution...
Kinetic modelling of enzymatic biodiesel production from castor oil: Temperature dependence of the Ping Pong parameters
, Article Canadian Journal of Chemical Engineering ; Volume 94, Issue 3 , 2016 , Pages 512-517 ; 00084034 (ISSN) ; Kariminia, H. R ; Khorasheh, F ; Sharif University of Technology
Wiley-Liss Inc
2016
Abstract
Biodiesel is considered an alternative replacement for petroleum diesel, and enzymatic reaction is one method for biodiesel production. Understanding the kinetics of this reaction is important to achieve higher production rates. The kinetics of transesterification of castor oil using Novozym 435 was investigated in this study. The genetic algorithm was employed for estimation of kinetic parameters including Vmax, KmTG, and KmA in the Ping Pong kinetic model at different temperatures. In most enzymatic reactions that follow the Ping Pong mechanism, inhibition by alcohol has been taken into consideration. Here, we examined a competitive inhibition mechanism and found no inhibition effect at...
A sensitivity analysis of thermal lattices kinetic parameters with respect to the spectral weighting function using ultrafine BN method
, Article Progress in Nuclear Energy ; Volume 88 , 2016 , Pages 310-320 ; 01491970 (ISSN) ; Salehi, A. A ; Vosoughi, N ; Ayyoubzadeh, S. M ; Sharif University of Technology
Abstract
Accurate calculation of kinetic parameters is of utmost importance in the safety analysis of a nuclear reactor. In the current paper, two approaches are investigated to evaluate these parameters in energy phase space. In the first approach, these parameters are derived from an energy-continuous form of the forward and adjoint transport equations and then integrals with respect to the energy variable are replaced by weighted summations over the energy groups, while in the second approach these parameters are extracted from the multi-group forward equation and its associate adjoint equation in which their multigroup constants are weighted by forward spectrum. The difference of weighting...
Calculation and measurement of kinetics parameters of Tehran research reactor
, Article International Conference on Nuclear Engineering, Proceedings, ICONE, 12 July 2009 through 16 July 2009, Brussels ; Volume 5 , 2009 , Pages 223-228 ; 9780791843550 (ISBN) ; Vosoughi, N ; Gharib, M ; Ghofrani, M. B ; Sharif University of Technology
Abstract
Effective delayed neutron fraction βeff and neutron generation time Λare important factors in reactor physics calculation and transient analysis. In first stage of this research, these kinetics parameters have been calculated for two states of Tehran research reactor (TRR), i.e. cold (fuel, clad and coolant temperature 20°C) and hot (fuel, clad and coolant temperature 65, 49 and 44°C, respectively) using MTR-PC code. In second stage, these parameters have been measured with experimental method based on Inhour equation. For cold state, calculated βeff and Λ by MTR-PC are 0.008315 and 30.190 μsec, respectively. Same parameters in hot state are 0.008303 and 33.828 μsec, respectively. The...
Plant-wide simulation model for modified claus process based on simultaneous data reconciliation and parameter estimation
, Article Chemical Engineering Transactions ; Volume 57 , 2017 , Pages 997-1002 ; 22839216 (ISSN); 9788895608488 (ISBN) ; Rad, A ; Sharif University of Technology
Italian Association of Chemical Engineering - AIDIC
2017
Abstract
The modified Claus process is characterized by several problems, namely poor instrumentation and no precise kinetic model for predicting the behaviour of the reactors. Using operational data of an industrial plant, this paper proposes a general framework for development of a plant-wide simulation model for modified Claus process based on simultaneous data reconciliation and parameter estimation (DRPE) using Genetic algorithm (GA). HYSYS as a commercial process simulator that provides a high-level of accuracy as well as redundancy which all is favoured for DRPE has been utilized in this work. Building a communication framework between HYSYS and MATLAB, data pre-processing of raw measurement...