scholarly journals Assessing the impact of substrate-level enzyme regulations limiting ethanol titer in Clostridium thermocellum using a core kinetic model

2022 ◽  
Author(s):  
Charles Foster ◽  
Veda Sheersh Boorla ◽  
Satayakam Dash ◽  
Saratram Gopalakrishnan ◽  
Tyler B. Jacobson ◽  
...  
Keyword(s):  
Kinetic Model ◽  
Clostridium Thermocellum ◽  
Substrate Level ◽  
The Impact

scholarly journals Constrained Parameter Estimation for a Mechanistic Kinetic Model of Cobalt–Hydrogen Electrochemical Competition during a Cobalt Removal Process

Entropy ◽  
2021 ◽  
Vol 23 (4) ◽  
pp. 387
Author(s):  
Yiting Liang ◽  
Yuanhua Zhang ◽  
Yonggang Li
Keyword(s):  
Parameter Estimation ◽  
Kinetic Model ◽  
Model Parameters ◽  
Hydrogen Ions ◽  
Removal Process ◽  
Cobalt Removal ◽  
Estimation Scheme ◽  
Zinc Hydrometallurgy ◽  
The Impact ◽  
Parameter Estimation Scheme

A mechanistic kinetic model of cobalt–hydrogen electrochemical competition for the cobalt removal process in zinc hydrometallurgical was proposed. In addition, to overcome the parameter estimation difficulties arising from the model nonlinearities and the lack of information on the possible value ranges of parameters to be estimated, a constrained guided parameter estimation scheme was derived based on model equations and experimental data. The proposed model and the parameter estimation scheme have two advantages: (i) The model reflected for the first time the mechanism of the electrochemical competition between cobalt and hydrogen ions in the process of cobalt removal in zinc hydrometallurgy; (ii) The proposed constrained parameter estimation scheme did not depend on the information of the possible value ranges of parameters to be estimated; (iii) the constraint conditions provided in that scheme directly linked the experimental phenomenon metrics to the model parameters thereby providing deeper insights into the model parameters for model users. Numerical experiments showed that the proposed constrained parameter estimation algorithm significantly improved the estimation efficiency. Meanwhile, the proposed cobalt–hydrogen electrochemical competition model allowed for accurate simulation of the impact of hydrogen ions on cobalt removal rate as well as simulation of the trend of hydrogen ion concentration, which would be helpful for the actual cobalt removal process in zinc hydrometallurgy.

Kinetics of Tropomyosin Denaturation as a Predictive Model for Verifying Thermal Processing of Beef Products

2006 ◽  
Vol 69 (10) ◽  
pp. 2447-2453 ◽  
Author(s):  
FUR-CHI CHEN ◽  
Y.-H. PEGGY HSIEH ◽  
ROGER C. BRIDGMAN ◽  
AGNES KILONZO-NTHENGE
Keyword(s):  
Kinetic Model ◽  
Thermal Denaturation ◽  
Mathematic Model ◽  
Heating Time ◽  
Enzyme Linked Immunosorbent Assay ◽  
Meat Industry ◽  
Dot Blot ◽  
Quality Control Tool ◽  
Beef Products ◽  
The Impact

An enzyme-linked immunosorbent assay (ELISA) was developed to study thermal denaturation of tropomyosin (Tm) using the time-temperature requirements for cooked beef. The ELISA employed a monoclonal antibody (MAb 2C9) raised against bovine Tm for quantifying residual Tm in muscle extracts. The specificity of MAb 2C9 to bovine Tm was demonstrated by Western blot and the analytical validity of ELISA was confirmed by dot blot. Thermal denaturation of Tm, in the temperature range between 54.4 and 70.0°C, showed first-order dependency. Kinetic parameters of Tm denaturation were derived from isothermal heating of beef muscle extract at 54.4, 57.2, 60.0, and 62.8°C. Temperature dependency of the rate constant (k) was demonstrated by Arrhenius plot; the activation energy (Ea) of Tm denaturation was determined to be 484 kJ·mol−1.A mathematic model describing the impact of the heating time-temperature on Tm denaturation was developed. Predicted Tm from the integrated time-temperature model agreed closely with the measured Tm in dynamically heat-processed beef samples. Percent errors between the measured and the predicted values ranged from −5.1 to 5.3%. The kinetic model provides an accurate and reproducible prediction of the impact of actual heating time-temperature on residual Tm in cooked beef. The MAb-based ELISA and kinetic model developed in this study have the potential to be adapted by the meat industry as a quality control tool.

scholarly journals Methanol formation from CO2catalyzed by Fe3S4{111}: formate versus hydrocarboxyl pathways

2016 ◽  
Vol 188 ◽  
pp. 161-180 ◽  
Author(s):  
A. Roldan ◽  
N. H. de Leeuw
Keyword(s):  
Kinetic Model ◽  
Carbon Capture ◽  
Reaction Network ◽  
Selective Reduction ◽  
Small Organic Molecules ◽  
Methanol Formation ◽  
Wide Range ◽  
Reaction Constant ◽  
The Impact ◽  
Formate Intermediate

Carbon capture and utilisation is one of the most promising techniques to minimize the impact of the increasing amount of carbon dioxide in the atmosphere. Recently, the mineral greigite was shown to be capable of catalysing CO2conversion, leading to useful small organic molecules. Here, we have carried out a systematic study of the adsorption and selective reduction of CO2on the Fe3S4{111} surface. We have considered both formate and hydrocarboxyl key intermediates, leading to different reaction pathwaysviaEley–Rideal and Langmuir–Hinshelwood mechanisms, and we have built a kinetic model considering the wide range of intermediates in the reaction network. Our results show that the mechanism to produce formic acid takes placeviaformate intermediate mostly on FeAsites, while methanol is formedviahydrocarboxyl intermediates on FeBsites. From the kinetic model, we have derived a reaction constant comparison and determined the limiting step rates. The overall process takes place under very mild conditions, requiring only a small energy input that might come from a chemiosmotic potential.

Modelling of catalytic hydrocracking and fractionation of refinery vacuum residue

2014 ◽  
Vol 68 (12) ◽  
Author(s):  
Eduard Manek ◽  
Juma Haydary
Keyword(s):  
Kinetic Model ◽  
Residence Time ◽  
Aspen Plus ◽  
Vacuum Distillate ◽  
Operating Conditions ◽  
Vacuum Residue ◽  
Yield Model ◽  
Conversion Model ◽  
The Impact ◽  
Kinetics Of

AbstractThe main objective of this work was to create a kinetic model of refinery vacuum residue hydrocracking and to monitor the impact of the operating conditions on the product yields. Data and yield measurements were gathered from a residual hydrocracking unit (RHC). Reaction temperature ranged from 401°C to 412°C at the pressure of 18–20 MPa. A simplified kinetic yield model was applied; where the feed and each product fraction are represented by one lump (reactant or product of cracking) represented by the number of pseudo-components. The product fractions were determined by fractional distillation of the output mixture from the reactor. The kinetic model includes eight reaction steps and the following six fractions: vacuum residue, vacuum distillate, gas oil, kerosene, naphtha, and gas. In addition, a model for hydrodesulphurisation has been proposed. The average relative deviation between model and experimental yields was 5.36 %, and that for the sulphur conversion model was 1.04 %. An Excel file with the kinetic model was implemented in the Aspen Plus program using a user-defined model of the reactor. This model allows to input/output data between the Aspen Plus and Excel programs. The Excel subroutine calculates the reaction kinetics of cracking from the set temperature and residence time, and distributes the products into 30 pseudo-components created in the Aspen Plus program. The remaining part of the RHC unit was simulated in the Aspen Plus environment. The effects of the reaction conditions such as temperature and residence time on the conversion of the feed and on the distillation curves of the output mixture from the reactor were investigated. The model was verified by comparison of the distillation curves of simulated and real products.

scholarly journals A kinetic model for runaway electrons in the ionosphere

2006 ◽  
Vol 24 (9) ◽  
pp. 2391-2401 ◽  
Author(s):  
G. Garcia ◽  
F. Forme
Keyword(s):  
Kinetic Model ◽  
Electric Field ◽  
Current Density ◽  
Acoustic Waves ◽  
Large Field ◽  
Total Current ◽  
Runaway Electrons ◽  
Direction Parallel ◽  
Total Current Density ◽  
The Impact

Abstract. Electrodynamic models and measurements with satellites and incoherent scatter radars predict large field aligned current densities on one side of the auroral arcs. Different authors and different kinds of studies (experimental or modeling) agree that the current density can reach up to hundreds of µA/m2. This large current density could be the cause of many phenomena such as tall red rays or triggering of unstable ion acoustic waves. In the present paper, we consider the issue of electrons moving through an ionospheric gas of positive ions and neutrals under the influence of a static electric field. We develop a kinetic model of collisions including electrons/electrons, electrons/ions and electrons/neutrals collisions. We use a Fokker-Planck approach to describe binary collisions between charged particles with a long-range interaction. We present the essential elements of this collision operator: the Langevin equation for electrons/ions and electrons/electrons collisions and the Monte-Carlo and null collision methods for electrons/neutrals collisions. A computational example is given illustrating the approach to equilibrium and the impact of the different terms (electrons/electrons and electrons/ions collisions on the one hand and electrons/neutrals collisions on the other hand). Then, a parallel electric field is applied in a new sample run. In this run, the electrons move in the z direction parallel to the electric field. The first results show that all the electron distribution functions are non-Maxwellian. Furthermore, runaway electrons can carry a significant part of the total current density, up to 20% of the total current density.

Numerical Simulation of Multilayer Composites Failure under Dynamic Loading

2015 ◽  
Vol 756 ◽  
pp. 408-413 ◽  
Author(s):  
Sergey A. Zelepugin ◽  
Aleksey S. Zelepugin
Keyword(s):  
Kinetic Model ◽  
High Velocity ◽  
High Velocity Impact ◽  
The Finite Element Method ◽  
Depth Of Penetration ◽  
Sharp Drop ◽  
Composite Target ◽  
Velocity Impact ◽  
Relaxation Of Stresses ◽  
The Impact

The processes of high-velocity interaction of a projectile with a metal-intermetallic laminate (MIL) composite target were numerically investigated in axisymmetrical geometry using the finite element method. To simulate the failure of the material under high velocity impact, we applied the active-type kinetic model determining the growth of microdamages, which continuously changes the properties of the material and induce the relaxation of stresses. To simulate the brittle-like failure of the intermetallic material under high velocity impact, we modified the kinetic model of failure and included the possibility of failure above Hugoniot elastic limit in the shock wave and sharp drop in strength characteristics if the failure begins. The results show that the depth of penetration depends on the thicknesses of intermetallic and titanium alloy layers. The Al3Ti/Ti-6-4 MIL composite target withstands the impact loading in the case of the ratio about 4/1.

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