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Writer: 

Journal: 

داخلی

Issue Info: 
  • End Date: 

    اسفند ماه 1379
Measures: 
  • Citations: 

    4
  • Views: 

    857
  • Downloads: 

    0
Keywords: 
Abstract: 

کراتینین عبارت از کراتین بدون آب است که به صورت محلول زائد توسط کلیه دفع می گردد. غلظت کراتینین در خون همچون اوره با کاهش فعالیت کلیه افزایش می یابد. با انسداد مجرای ادرار و در نفریت مزمن غلظت کراتینین ممکن است به نسبت بیش از مقدار اوره باشد. در اختلال رشدعضلانی مقدار کراتینین کاهش می یابد. اندازه گیری مقدار کراتینین در خون و ادرار جهت تشخیص بیماری های فوق در آزمایشگاههای تشخیص طبی رایج است. در این طرح دو نوع معرف کراتینین طراحی و ساخته شده است.یکی به روش kinetic که درمدت کمتر از دو دقیقه کراتینین را می توان توسط آن اندازه گیری نمود، دیگری معرف ساخته شده به روش End Point است که در آن چندین نمونه را در فرصت مناسب (پایان واکنش) می توان اندازه گیری نمود. این معرف طوری طراحی شده است که جواب مثبت کاذب نمی دهد و از دقت خیلی خوبی برخوردار است. ساخت این کیت ها جهت تامین نیاز آزمایشگاههای تشخیص طبی کشور می باشد.

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Journal: 

POLYOLEFINS JOURNALS

Issue Info: 
  • Year: 

    2021
  • Volume: 

    8
  • Issue: 

    2
  • Pages: 

    123-133
Measures: 
  • Citations: 

    0
  • Views: 

    42
  • Downloads: 

    14
Abstract: 

Bulk phase polymerization of propylene with a 4th generation of Ziegler-Natta catalyst was kinetically investigated by means of heat flow calorimetry. The assumptions and modifications on isothermal calorimetric method were demonstrated. Our calibration method showed that heat exchange with the reactor cover plate is not constant over time. Therefore, the dynamic of cover plate temperature was considered in the calorimetric method. The polymerization rate profiles depending on hydrogen and external electron donor concentration have been investigated. Normalized polymerization profiles (Rp/Rpmax) are plotted and expressed as an exponential function of time. Effects of hydrogen and external electron donor (ED) concentration on Rpmax and polymerization rate were investigated as well. The results showed that by increasing hydrogen concentration, initial polymerization rate (Rpmax) increased. Hydrogen increased productivity by increasing the initial polymerization rate, while it had no negative effect on the rates of decay or its effect was small. The ED concentration was optimized so that the catalyst deactivation rate was at its lowest level. Also, changes in the ratio of activation to inactivation with ED concentration were examined, and a proportional change was observed

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Issue Info: 
  • Year: 

    2013
  • Volume: 

    10
  • Issue: 

    4
  • Pages: 

    16-27
Measures: 
  • Citations: 

    0
  • Views: 

    479
  • Downloads: 

    255
Abstract: 

A series of experiments were carried out by mixture of methanol and water as feed of the methanol to propylene (MTP) process in temperature range of 623-823 K. The HZSM5 catalyst with the Si/Al ratio of 200 was applied for carrying out the experiments. A novel lumped kinetic scheme was proposed for methanol to propylene (MTP) process. The reactor was mathematically modeled by assumptions of being isothermal, fixed bed, plug flow and the hybrid genetic algorithm was applied for estimating the kinetic parameters. The temperature dependency of the kinetic parameters was determined, using the modified Arrhenius relation. A good agreement was observed between the experimental and the calculated data. Effect of temperature on propylene and ethylene selectivity was investigated. It was found that the propylene selectivity increases with temperature until 773.15 K, but after that it decreases.

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Issue Info: 
  • Year: 

    2020
  • Volume: 

    31
  • Issue: 

    3
  • Pages: 

    233-244
Measures: 
  • Citations: 

    0
  • Views: 

    555
  • Downloads: 

    314
Abstract: 

In this paper, conventional SAPO-34 and Cerium Hierarchical SAPO-34 zeolites are synthesized using a hydrothermal method for methanol-to-propylene (MTP) reaction. The Ce-H-SAPO-34 catalyst shows a slightly larger crystal size, bimodal pore size distribution (microporous and mesoporous) and lower surface acidity compared to conventional SAPO-34 catalysts. According to these physicochemical properties and the previously suggested reaction mechanisms on the conventional SAPO-34 catalyst, a new reaction network is introduced for Ce-H-SAPO-34 catalyst. This was based on the data collected from a catalytic micro reactor in the temperature range of 390-450° C and at atmospheric pressure. The lumped kinetic model and the reaction rate expression have been introduced by considering the reaction network. The parameters were then estimated based on the experimental data using genetic algorithms. Comparing the experiments with the predicted data suggests a good correlation between the experimental data and the model.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    20
Measures: 
  • Views: 

    166
  • Downloads: 

    69
Keywords: 
Abstract: 

MODEL-BASED LEAST SQUARES FITTING ANALYSIS OR HARD MODELING IS A SPECIFIC PART OF CHEMOMETRICS, WHICH IS BASED ON MATHEMATICAL RELATIONSHIPS FOR DESCRIBING THE MEASUREMENTS [1]. FURTHERMORE, MODEL-BASED ANALYSIS OF COUPLED EQUILIBRIUM-kinetic PROCESSES IS THE COMPUTATION OF THE CONCENTRATIONS OF ALL CHEMICAL SPECIES AS A FUNCTION OF THE PROGRESS OF AN INTERTWINED kineticEQUILIBRIUM CHEMICAL PROCESS. THIS MEANS EQUILIBRIUM PROCESSES HAVE BEEN DIRECTLY INCORPORATED INTO THE RATE LAWS [2]. IN THIS STUDY, WE DEMONSTRATE SEVERAL MODELS, THAT THEY CAN BE APPLIED TO NUMEROUS CHEMICAL MECHANISMS. THERE ARE SEVERAL DIFFERENT TYPES OF INTERTWINED kineticEQUILIBRIUM CHEMICAL PROCESSES THAT CAN BE MODELED, COMMON EXAMPLES, MODELED IN THIS WORK, INCLUDE CHARGE TRANSFER COMPLEX FORMATION REACTIONS, PH_DEPENDENT DEGRADATION OF CHEMICAL COMPOUNDS, kinetic OF COMPLEXATION REACTION AT VARIABLE PH AND TAUTOMERIZATION kineticS IN MICELLAR SOLUTIONS. ACTUALLY, WE HAVE RESTRICTED OURSELVES TO CHEMICAL REACTIONS WHERE BOTH EQUILIBRIUM AND kinetic PROCEDURES ARE LINKED WITH EACH OTHER. THE GOAL IS TO DEMONSTRATE HOW THE CONCENTRATIONS OF ALL REACTING SPECIES CAN BE COMPUTED AS A FUNCTION OF TIME FOR ANY REACTION MECHANISM USING THE kinetic DATA. IT IS RELATIVELY STRAIGHTFORWARD TO INCORPORATE AN APPROPRIATE ALGORITHM INTO A GENERAL NON-LINEAR LEAST-SQUARES ROUTINE FOR THE INVESTIGATED DATA. THE CALCULATIONS ARE BASED ON THE KNOWN INITIAL CONCENTRATIONS OF THE COMPONENTS AS WELL AS ALL ESTIMATED RATE AND EQUILIBRIUM CONSTANTS. AFTER THE DATA FITTING PROCESS, THE OPTIMAL PARAMETERS TOGETHER WITH AN ESTIMATE OF THEIR STANDARD DEVIATIONS HAVE BEEN OBTAINED. SUCH MODELS ALLOW THE FITTING OF THE RATE AS WELL AS THE EQUILIBRIUM CONSTANTS. MODEL-BASED ANALYSIS TOGETHER WITH THE POSSIBILITY OF CALCULATING AND INCORPORATING THE EQUILIBRIUM AND kinetic PARAMETERS INTO THE FITTING ALGORITHM HAS ALLOWED THE COMPLETE ANALYSIS OF COMPLEX REACTION MECHANISMS. THIS IS THE FIRST COMPREHENSIVE STUDY OF ALL OF THESE LINKED REACTIONS, THEIR kinetic CONSTANTS, AND THUS THEIR EQUILIBRIUM CONSTANTS. THIS STUDY OPENS UP A PROMISING NEW AVENUE FOR OBTAINING EQUILIBRIUM AND kinetic CONSTANTS, SIMULTANEOUSLY, USING THE SAME kinetic DATA.

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Issue Info: 
  • Year: 

    2021
  • Volume: 

    15
  • Issue: 

    3
  • Pages: 

    76-87
Measures: 
  • Citations: 

    0
  • Views: 

    27
  • Downloads: 

    7
Abstract: 

In this paper, a new lumped kinetic model for methanol to propylene process (MTP) over CeriumHierarchical SAPO-34 catalyst was developed based on data obtained from a micro catalytic reactor in the temperature range of 390–450°C and at atmospheric pressure, using appropriate reaction network. The Ce-HSAPO-34 zeolite was synthesized by hydrothermal method in the presence of nporopylamine as a mesoscale template and pore size modifier. The reaction rate equation has been introduced with consideration of reaction mechanism and the parameters were optimized on the experimental data by genetic algorithm. Comparing the experimental and predicted data showed that the predicted values from the presented model are well fitted to the experimental data.

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Issue Info: 
  • Year: 

    2021
  • Volume: 

    15
  • Issue: 

    4
  • Pages: 

    76-87
Measures: 
  • Citations: 

    0
  • Views: 

    30
  • Downloads: 

    7
Abstract: 

In this paper, a new lumped kinetic model for methanol to propylene process (MTP) over CeriumHierarchical SAPO-34 catalyst was developed based on data obtained from a micro catalytic reactor in the temperature range of 390–450°C and at atmospheric pressure, using appropriate reaction network. The Ce-HSAPO-34 zeolite was synthesized by hydrothermal method in the presence of nporopylamine as a mesoscale template and pore size modifier. The reaction rate equation has been introduced with consideration of reaction mechanism and the parameters were optimized on the experimental data by genetic algorithm. Comparing the experimental and predicted data showed that the predicted values from the presented model are well fitted to the experimental data.

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View 30

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Issue Info: 
  • Year: 

    2022
  • Volume: 

    12
  • Issue: 

    2
  • Pages: 

    115-125
Measures: 
  • Citations: 

    0
  • Views: 

    48
  • Downloads: 

    15
Abstract: 

The development of an appropriate kinetic model for cracking reactions is essential for simulation and process optimization. These results are to be potentially used for proper reactor design. The complexities of oil gas inlet combinations have led to an increase in the challenges while defining and depicting kinetics on an intrinsic scale. Hence, complicated chemical reaction circumstances are characterized by combining many possible pathways into more modest groups of comparable chemical substances. In addition, cracking kinetic demonstrations is frequently carried out in lumped forms. This is due to the complex nature of the feedstock, which is known to contain enormous hydrocarbon associated with series and parallel reaction networks. The representation of complicated compounds by consolidating a large chemical component into small amounts of apparent components has been generally utilized in industry to generate a straightforward approach to stoichiometry, thermodynamics, and kinetics. Considering the importance of this lumped method, this study focused on studying the development of a kinetic lump approach to solve kinetic problems and cracking mechanisms.

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Issue Info: 
  • Year: 

    2007
  • Volume: 

    26
  • Issue: 

    3
  • Pages: 

    133-140
Measures: 
  • Citations: 

    0
  • Views: 

    998
  • Downloads: 

    0
Abstract: 

kinetic study of dehydrogenation of isobutane to isobutene was investigated on Pt-Sn supported on g-Al2O3 as catalyst using a tubular quartz glass reactor at atmospheric pressure and a temperature range of 425-575 cc. Different rate models were extracted by considering different elementary reactions of a probable mechanism as rate controlling step and the experimental results. The adsorption and kinetic coefficients were obtained by the Levenberg-Marquardt non-linear regression applied to the reaction rate equations using the experimental results. Results from statistical investigation of the models and comparison of their error percentages indicate that a power law rate equation is in a good agreement with the experimental data obtained at 575°C.

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Issue Info: 
  • Year: 

    2003
  • Volume: 

    16
  • Issue: 

    1 (TRANSACTIONS A: BASICS)
  • Pages: 

    61-72
Measures: 
  • Citations: 

    0
  • Views: 

    347
  • Downloads: 

    0
Abstract: 

The relationship between velocity of chemical reactions with activities or concentrations of their reactants, temperature and pressure and the mechanisms through which the reactions proceed are of interest to many scientists and engineers. The purpose of this article is to introduce computer software that is developed for calculation, classification and collection of such data. The application of the software to the homogeneous and heterogeneous processes occurring in porous and non-porous media of flat, cylindrical or spherical geometry is tested. The software is capable of assisting the professional process design engineers as well as the general process kinetic investigators

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