Artículos de revistas: "Detailed kinetics model"

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Mai, Tam V. T., Minh v. Duong, Hieu T. Nguyen y Lam K. Huynh. "Detailed kinetics of tetrafluoroethene ozonolysis". Physical Chemistry Chemical Physics 20, n.º 44 (2018): 28059–67. http://dx.doi.org/10.1039/c8cp05386c.

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The reaction mechanism was explored at the CCSD(T)/CBS//B3LYP/aug-cc-pVTZ level. Detailed kinetic analysis was firstly carried out using an ME/RRKM rate model with the inclusion of anharmonic and tunneling treatments. 1,3-Cycloaddition is found to be the rate-determining step. Calculated rate constants confirm the latest experimental data.

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Dai, Qian y Hua Ye Guan. "A New Skeletal Chemical Kinetic Mechanism of Ethanol Combustion for HCCI Engine Simulation". Advanced Materials Research 614-615 (diciembre de 2012): 381–84. http://dx.doi.org/10.4028/www.scientific.net/amr.614-615.381.

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According to the detailed chemical kinetic mechanism of ethanol proposed by the U．S．Lawrence Livermore Laboratory, this paper analyzes the main approach of ethanol oxidation. Based on the detailed chemical kinetics mechanism, a skeletal chemical reaction mechanism is presented by reaction path analysis．Thus a simplified model is constructed, which consists of 26 species and 26 reactions．And then the comparative studies were given between the simplified model and the detailed model．The simulation results show that simplified model and detailed model have good consistency.

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3

Keddam, Mourad, Polat Topuz y Özlem Aydin. "Simulation of boronizing kinetics of AISI 316 steel with an integral diffusion model". Materials Testing 63, n.º 10 (1 de octubre de 2021): 906–12. http://dx.doi.org/10.1515/mt-2021-0023.

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Abstract Boriding or boronizing is a type of surface property improvement process applied to metal or some non-metal materials by diffusion. The calculation of diffusion kinetics is also very important as it is a diffusion controlled process. Today, many researchers perform kinetic calculations by applying the Second Fick’s law to the Arrhenius equation. In this study, as an alternative to conventional kinetic calculations, the mathematical modeling of diffusion kinetics has been performed using the integral diffusion model. For the boronizing experiments, the pack-boronizing method was chosen and AISI 316 austenitic stainless steel was used. The experiments were carried out at three temperatures and for three times; Ekabor 2 was used as the boronizing agent. The detailed diffusion kinetics calculations were made using the data obtained from the experiments in the mathematical modeling.

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BROUWER, J., G. SACCHI, J. P. LONGWELL y A. F. SAROFIM. "A Turbulent Reacting Flow Model that Incorporates Detailed Chemical Kinetics". Combustion Science and Technology 101, n.º 1-6 (noviembre de 1994): 361–82. http://dx.doi.org/10.1080/00102209408951883.

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Huebner, W. F., D. C. Boice, I. Konno y P. D. Singh. "A Model of P/Tempel 2 With Dust and Detailed Chemistry". Symposium - International Astronomical Union 150 (1992): 449–50. http://dx.doi.org/10.1017/s0074180900090665.

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Pannala, Venkat R., Amadou K. S. Camara y Ranjan K. Dash. "Modeling the detailed kinetics of mitochondrial cytochrome c oxidase: Catalytic mechanism and nitric oxide inhibition". Journal of Applied Physiology 121, n.º 5 (1 de noviembre de 2016): 1196–207. http://dx.doi.org/10.1152/japplphysiol.00524.2016.

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Cytochrome c oxidase (CcO) catalyzes the exothermic reduction of O2 to H2O by using electrons from cytochrome c, and hence plays a crucial role in ATP production. Although details on the enzyme structure and redox centers involved in O2 reduction have been known, there still remains a considerable ambiguity on its mechanism of action, e.g., the number of sequential electrons donated to O2 in each catalytic step, the sites of protonation and proton pumping, and nitric oxide (NO) inhibition mechanism. In this work, we developed a thermodynamically constrained mechanistic mathematical model for the catalytic action of CcO based on available kinetic data. The model considers a minimal number of redox centers on CcO and couples electron transfer and proton pumping driven by proton motive force (PMF), and accounts for the inhibitory effects of NO on the reaction kinetics. The model is able to fit well all the available kinetic data under diverse experimental conditions with a physiologically realistic unique parameter set. The model predictions show that: 1) the apparent Km of O2 varies considerably and increases from fully reduced to fully oxidized cytochrome c depending on pH and the energy state of mitochondria, and 2) the intermediate enzyme states depend on pH and cytochrome c redox fraction and play a central role in coupling mitochondrial respiration to PMF. The developed CcO model can easily be integrated into existing mitochondrial bioenergetics models to understand the role of the enzyme in controlling oxidative phosphorylation in normal and disease conditions.

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Fiçicilar, Berker, İnci Eroğlu y Trung V. Nguyen. "A Five Layer One-Dimensional PEMFC Model with Detailed Electrode Kinetics". ECS Transactions 33, n.º 1 (17 de diciembre de 2019): 1515–27. http://dx.doi.org/10.1149/1.3484644.

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Dandy, David S. y Michael E. Coltrin. "A simplified analytical model of diamond growth in direct current arcjet reactors". Journal of Materials Research 10, n.º 8 (agosto de 1995): 1993–2010. http://dx.doi.org/10.1557/jmr.1995.1993.

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A simplified model of a direct current arcjet-assisted diamond chemical vapor deposition reactor is presented. The model is based upon detailed theoretical analysis of the transport and chemical processes occurring during diamond deposition, and is formulated to yield closed-form solutions for diamond growth rate, defect density, and heat flux to the substrate. In a direct current arcjet reactor there is a natural division of the physical system into four characteristic domains: plasma torch, free stream, boundary layer, and surface, leading to the development of simplified thermodynamic, transport, and chemical kinetic models for each of the four regions. The models for these four regions are linked to form a single unified model. For a relatively wide range of reactor operating conditions, this simplified model yields results that are in good quantitative agreement with stagnation flow models containing detailed multicomponent transport and chemical kinetics. However, in contrast to the detailed reactor models, the model presented here executes in near real-time on a computer of modest size, and can therefore be readily incorporated into process control models or global dynamic loop simulations.

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9

Kukshinov, N. V., S. N. Batura y M. S. Frantsuzov. "Validation of Methods for Calculating Hydrogen Combustion in a Supersonic Model Air Flow Using the Experimental Data of Beach — Evans — Schexnayder". Proceedings of Higher Educational Institutions. Маchine Building, n.º 11 (716) (noviembre de 2019): 36–45. http://dx.doi.org/10.18698/0536-1044-2019-11-36-45.

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This paper deals with numerical simulation of combustion of a hydrogen-air mixture in a supersonic flow. The simulation is based on solving the complete system of Navier-Stokes equations with closure using the turbulence model and detailed chemical kinetics. The mixing and combustion of a hydrogen-air fuel mixture is considered in the experimental formulation of Beach-Evans-Schexnayder. The effect of various kinetic mechanisms, turbulence models, TCI models, and boundary conditions on the solution is studied qualitatively and quantitatively. The relative errors of mass concentration of water for control sections are determined, and the methods’ boundaries are shown. Conclusions are drawn on the influence of turbulent mixing mechanisms and chemical kinetics on the combustion of hydrogen.

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10

Zhang, Pei, Siyan Liu, Dan Lu, Ramanan Sankaran y Guannan Zhang. "An out-of-distribution-aware autoencoder model for reduced chemical kinetics". Discrete & Continuous Dynamical Systems - S 15, n.º 4 (2022): 913. http://dx.doi.org/10.3934/dcdss.2021138.

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<p style='text-indent:20px;'>While detailed chemical kinetic models have been successful in representing rates of chemical reactions in continuum scale computational fluid dynamics (CFD) simulations, applying the models in simulations for engineering device conditions is computationally prohibitive. To reduce the cost, data-driven methods, e.g., autoencoders, have been used to construct reduced chemical kinetic models for CFD simulations. Despite their success, data-driven methods rely heavily on training data sets and can be unreliable when used in out-of-distribution (OOD) regions (i.e., when extrapolating outside of the training set). In this paper, we present an enhanced autoencoder model for combustion chemical kinetics with uncertainty quantification to enable the detection of model usage in OOD regions, and thereby creating an OOD-aware autoencoder model that contributes to more robust CFD simulations of reacting flows. We first demonstrate the effectiveness of the method in OOD detection in two well-known datasets, MNIST and Fashion-MNIST, in comparison with the deep ensemble method, and then present the OOD-aware autoencoder for reduced chemistry model in syngas combustion.</p>

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11

Pelucchi, Matteo, Carlo Cavallotti, Alberto Cuoci, Tiziano Faravelli, Alessio Frassoldati y Eliseo Ranzi. "Detailed kinetics of substituted phenolic species in pyrolysis bio-oils". Reaction Chemistry & Engineering 4, n.º 3 (2019): 490–506. http://dx.doi.org/10.1039/c8re00198g.

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12

Knox, Benjamin W. y Caroline L. Genzale. "Reduced-order numerical model for transient reacting diesel sprays with detailed kinetics". International Journal of Engine Research 17, n.º 3 (22 de febrero de 2015): 261–79. http://dx.doi.org/10.1177/1468087415570765.

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13

Yang, Shiyou, Rolf D. Reitz, Claudia O. Iyer y Jianwen Yi. "A Transport Equation Residual Model Incorporating Refined G-Equation and Detailed Chemical Kinetics Combustion Models". SAE International Journal of Engines 1, n.º 1 (6 de octubre de 2008): 1028–44. http://dx.doi.org/10.4271/2008-01-2391.

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14

Cheng, Chen, Fu Ting Bao, Yu Zhao y Hao Xu. "Premixed Combustion of a Fine AP/HTPB Composite Propellant Based on Detailed Chemical Kinetics". Applied Mechanics and Materials 390 (agosto de 2013): 320–26. http://dx.doi.org/10.4028/www.scientific.net/amm.390.320.

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A model for Premixed Ammonium Perchlorate (AP)/Hydroxyl-terminated Polybutadiene (HTPB) combustion based on detailed chemical kinetics was established on two-dimensional cylindrical coordinates using the Vorticity-Velocity formulation, finite difference methods and several essential mathematical algorithms. This model includes both solid and condensed phase combustion mechanisms and the detailed chemical kinetics of the gas phase with 37 species and 127 reactions. Results obtained from the model, such as temperature and burning rate, match data from experiments. It is found that the model established in the current study is reliable and accurate, and the Vorticity-Velocity approach combined with finite difference methods is capable of and efficient in dealing with premixed AP/HTPB combustion.

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15

NICOLAI, CHRISTOPHER y FREDERICK SACHS. "SOLVING ION CHANNEL KINETICS WITH THE QuB SOFTWARE". Biophysical Reviews and Letters 08, n.º 03n04 (diciembre de 2013): 191–211. http://dx.doi.org/10.1142/s1793048013300053.

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The ability to record the currents from single ion channels led to the need to extract the underlying kinetic model from such data. This inverse hidden Markov problem is difficult but led to the creation of a software suite called QuB utilizing likelihood optimization. This review presents the software. The software is open source and, in addition to solving kinetic models, has many generic database operations including report generation with publishable graphics, function fitting and scripting for new and repeated processing and AD/DA I/O. The core algorithms allow for constraints such as fixed rates or maintaining detailed balance in the model. All rate constants can be driven by a stimulus and the system can analyze nonstationary data. QuB also can analyze the kinetics of multichannel data where individual events cannot be discriminated, but the fitting algorithms utilize the signal variance as well as the mean to fit models. QuB can be applied to any data appropriately modeled with Markov kinetics and has been utilized to solve ion channels but also the movement of motor proteins, the sleep cycles in mice, and physics processes. [Formula: see text]Special Issue Comment: This is a review about the software QuB that can extract a model from the trajectory. It is connected with the review about treatments when solving single molecules,60 and the reviews about enzymes.61,62

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16

Kong, S. C. y R. D. Reitz. "Use of Detailed Chemical Kinetics to Study HCCI Engine Combustion With Consideration of Turbulent Mixing Effects". Journal of Engineering for Gas Turbines and Power 124, n.º 3 (19 de junio de 2002): 702–7. http://dx.doi.org/10.1115/1.1413766.

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Detailed chemical kinetics was used in an engine CFD code to study the combustion process in HCCI engines. The CHEMKIN code was implemented in KIVA such that the chemistry and flow solutions were coupled. The reaction mechanism consists of hundreds of reactions and species and is derived from fundamental flame chemistry. Effects of turbulent mixing on the reaction rates were also considered. The results show that the present KIVA/CHEMKIN model is able to simulate the ignition and combustion process in three different HCCI engines including a CFR engine and two modified heavy-duty diesel engines. Ignition timings were predicted correctly over a wide range of engine conditions without the need to adjust any kinetic constants. However, it was found that the use of chemical kinetics alone was not sufficient to accurately simulate the overall combustion rate. The effects of turbulent mixing on the reaction rates need to be considered to correctly simulate the combustion and heat release rates.

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17

Brock, Eric E. y Phillip E. Savage. "Detailed chemical kinetics model for supercritical water oxidation of C1 compounds and H2". AIChE Journal 41, n.º 8 (agosto de 1995): 1874–88. http://dx.doi.org/10.1002/aic.690410806.

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18

Wu, Hao, Fabian Paul, Christoph Wehmeyer y Frank Noé. "Multiensemble Markov models of molecular thermodynamics and kinetics". Proceedings of the National Academy of Sciences 113, n.º 23 (25 de mayo de 2016): E3221—E3230. http://dx.doi.org/10.1073/pnas.1525092113.

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We introduce the general transition-based reweighting analysis method (TRAM), a statistically optimal approach to integrate both unbiased and biased molecular dynamics simulations, such as umbrella sampling or replica exchange. TRAM estimates a multiensemble Markov model (MEMM) with full thermodynamic and kinetic information at all ensembles. The approach combines the benefits of Markov state models—clustering of high-dimensional spaces and modeling of complex many-state systems—with those of the multistate Bennett acceptance ratio of exploiting biased or high-temperature ensembles to accelerate rare-event sampling. TRAM does not depend on any rate model in addition to the widely used Markov state model approximation, but uses only fundamental relations such as detailed balance and binless reweighting of configurations between ensembles. Previous methods, including the multistate Bennett acceptance ratio, discrete TRAM, and Markov state models are special cases and can be derived from the TRAM equations. TRAM is demonstrated by efficiently computing MEMMs in cases where other estimators break down, including the full thermodynamics and rare-event kinetics from high-dimensional simulation data of an all-atom protein–ligand binding model.

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19

Babajimopoulos, A., D. N. Assanis, D. L. Flowers, S. M. Aceves y R. P. Hessel. "A fully coupled computational fluid dynamics and multi-zone model with detailed chemical kinetics for the simulation of premixed charge compression ignition engines". International Journal of Engine Research 6, n.º 5 (1 de octubre de 2005): 497–512. http://dx.doi.org/10.1243/146808705x30503.

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Modelling the premixed charge compression ignition (PCCI) engine requires a balanced approach that captures both fluid motion as well as low- and high-temperature fuel oxidation. A fully integrated computational fluid dynamics (CFD) and chemistry scheme (i.e. detailed chemical kinetics solved in every cell of the CFD grid) would be the ideal PCCI modelling approach, but is computationally very expensive. As a result, modelling assumptions are required in order to develop tools that are computationally efficient, yet maintain an acceptable degree of accuracy. Multi-zone models have been previously shown accurately to capture geometry-dependent processes in homogeneous charge compression ignition (HCCI) engines. In the presented work, KIVA-3V is fully coupled with a multi-zone model with detailed chemical kinetics. Computational efficiency is achieved by utilizing a low-resolution discretization to solve detailed chemical kinetics in the multi-zone model compared with a relatively high-resolution CFD solution. The multi-zone model communicates with KIVA-3V at each computational timestep, as in the ideal fully integrated case. The composition of the cells, however, is mapped back and forth between KTVA-3V and the multi-zone model, introducing significant computational time savings. The methodology uses a novel re-mapping technique that can account for both temperature and composition non-uniformities in the cylinder. Validation cases were developed by solving the detailed chemistry in every cell of a KIVA-3V grid. The new methodology shows very good agreement with the detailed solutions in terms of ignition timing, burn duration, and emissions.

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20

Haiman, Zachary B., Daniel C. Zielinski, Yuko Koike, James T. Yurkovich y Bernhard O. Palsson. "MASSpy: Building, simulating, and visualizing dynamic biological models in Python using mass action kinetics". PLOS Computational Biology 17, n.º 1 (28 de enero de 2021): e1008208. http://dx.doi.org/10.1371/journal.pcbi.1008208.

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Mathematical models of metabolic networks utilize simulation to study system-level mechanisms and functions. Various approaches have been used to model the steady state behavior of metabolic networks using genome-scale reconstructions, but formulating dynamic models from such reconstructions continues to be a key challenge. Here, we present the Mass Action Stoichiometric Simulation Python (MASSpy) package, an open-source computational framework for dynamic modeling of metabolism. MASSpy utilizes mass action kinetics and detailed chemical mechanisms to build dynamic models of complex biological processes. MASSpy adds dynamic modeling tools to the COnstraint-Based Reconstruction and Analysis Python (COBRApy) package to provide an unified framework for constraint-based and kinetic modeling of metabolic networks. MASSpy supports high-performance dynamic simulation through its implementation of libRoadRunner: the Systems Biology Markup Language (SBML) simulation engine. Three examples are provided to demonstrate how to use MASSpy: (1) a validation of the MASSpy modeling tool through dynamic simulation of detailed mechanisms of enzyme regulation; (2) a feature demonstration using a workflow for generating ensemble of kinetic models using Monte Carlo sampling to approximate missing numerical values of parameters and to quantify biological uncertainty, and (3) a case study in which MASSpy is utilized to overcome issues that arise when integrating experimental data with the computation of functional states of detailed biological mechanisms. MASSpy represents a powerful tool to address challenges that arise in dynamic modeling of metabolic networks, both at small and large scales.

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Karasavvas, Evgenios, Athanasios Scaltsoyiannes, Andy Antzaras, Kyriakos Fotiadis, Kyriakos Panopoulos, Angeliki Lemonidou, Spyros Voutetakis y Simira Papadopoulou. "One-Dimensional Heterogeneous Reaction Model of a Drop-Tube Carbonator Reactor for Thermochemical Energy Storage Applications". Energies 13, n.º 22 (12 de noviembre de 2020): 5905. http://dx.doi.org/10.3390/en13225905.

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Calcium looping systems constitute a promising candidate for thermochemical energy storage (TCES) applications, as evidenced by the constantly escalating scientific and industrial interest. However, the technologically feasible transition from the research scale towards industrial and highly competitive markets sets as a prerequisite the optimal design and operation of the process, especially corresponding reactors. The present study investigates for the first time the development of a detailed, one-dimensional mathematical model for the steady-state simulation of a novel drop-tube carbonator reactor as a core equipment unit in a concentrated solar power (CSP)-thermochemical energy storage integration plant. A validated kinetic mathematical model for a carbonation reaction (CaO(s) + CO2(g) → CaCO3(s)) focused on thermochemical energy storage conditions was developed and implemented for different material conditions. The fast gas–solid reaction kinetics conformed with the drop-tube reactor concept, as the latter is suitable for very fast reactions. Reaction kinetics were controlled by the reaction temperature. Varying state profiles were computed across the length of the reactor by using a mathematical model in which reactant conversions, the reaction rate, and the temperature and velocity of gas and solid phases provided crucial information on the carbonator’s performance, among other factors. Through process simulations, the model-based investigation approach revealed respective restrictions on a tailor-made reactor of 10 kWth, pointing out the necessity of detailed models as a provision for design and scale-up studies.

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22

Mohanty, Mohit Prakash, Bharati Brahmacharimayum y Pranab Kumar Ghosh. "Effects of phenol on sulfate reduction by mixed microbial culture: kinetics and bio-kinetics analysis". Water Science and Technology 77, n.º 4 (18 de diciembre de 2017): 1079–88. http://dx.doi.org/10.2166/wst.2017.630.

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Abstract Mixed microbial culture collected from the wastewater treatment plant of Indian Institute of Technology Guwahati (IITG) was further grown in anaerobic condition in presence of sulfate where lactate was added as a carbon source. Sulfate addition was increased stepwise up to 1,000 mg l−1 before phenol was added at increasing concentrations from 10 mg l−1 to 300 mg l−1. Kinetics of sulfate, phenol and chemical oxygen demand reduction were studied and experimental findings were analyzed using various bio-models to estimate the bio-kinetic coefficients. This is the first detailed report on kinetics and bio-kinetic studies of sulfate reduction in presence of phenol. Experimental results showed that there was no inhibition of sulfate reduction and microbial growth up to 100 mg l−1 phenol addition. However, inhibition to different degrees was observed at higher phenol addition. The experimental data of microbial growth and substrate consumption in presence of phenol fitted well to the Edward model (R2 = 0.85, root mean square error = 0.001011) with maximum specific growth rate = 0.052 h−1, substrate inhibition constant = 88.05 mg l−1 and half saturation constant = 58.22 mg l−1. The characteristics of the cultured microbes were determined through a series of analysis and microbial tests.

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23

Liu, Yushuai, Yannis Hardalupas y Alexander M. K. P. Taylor. "A detailed CO2(1B2) chemiluminescence chemical kinetics model for carbon monoxide and hydrocarbon oxidation". Fuel 323 (septiembre de 2022): 124363. http://dx.doi.org/10.1016/j.fuel.2022.124363.

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24

Haarlemmer, Geert y Tsilla Bensabath. "Comprehensive Fischer–Tropsch reactor model with non-ideal plug flow and detailed reaction kinetics". Computers & Chemical Engineering 84 (enero de 2016): 281–89. http://dx.doi.org/10.1016/j.compchemeng.2015.08.017.

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Goldschen-Ohm, Marcel P., Alexander Haroldson, Mathew V. Jones y Robert A. Pearce. "A nonequilibrium binary elements-based kinetic model for benzodiazepine regulation of GABAA receptors". Journal of General Physiology 144, n.º 1 (30 de junio de 2014): 27–39. http://dx.doi.org/10.1085/jgp.201411183.

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Ion channels, like many other proteins, are composed of multiple structural domains. A stimulus that impinges on one domain, such as binding of a ligand to its recognition site, can influence the activity of another domain, such as a transmembrane channel gate, through interdomain interactions. Kinetic schemes that describe the function of interacting domains typically incorporate a minimal number of states and transitions, and do not explicitly model interactions between domains. Here, we develop a kinetic model of the GABAA receptor, a ligand-gated ion channel modulated by numerous compounds including benzodiazepines, a class of drugs used clinically as sedatives and anxiolytics. Our model explicitly treats both the kinetics of distinct functional domains within the receptor and the interactions between these domains. The model describes not only how benzodiazepines that potentiate GABAA receptor activity, such as diazepam, affect peak current dose–response relationships in the presence of desensitization, but also their effect on the detailed kinetics of current activation, desensitization, and deactivation in response to various stimulation protocols. Finally, our model explains positive modulation by benzodiazepines of receptor currents elicited by either full or partial agonists, and can resolve conflicting observations arguing for benzodiazepine modulation of agonist binding versus channel gating.

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Wu, Dating y Hui Zhang. "Numerical investigation of the growth kinetics for macromolecular microsphere composite hydrogel based on the TDGL equation". Journal of Theoretical and Computational Chemistry 15, n.º 08 (diciembre de 2016): 1650064. http://dx.doi.org/10.1142/s0219633616500644.

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We present results of a detailed numerical investigation of the phase separation kinetic process of the macromolecular microsphere composite (MMC) hydrogel. Based on the Flory-Huggins-de Gennes-like reticular free energy, we use the time-dependent Ginzburg–Landau (TDGL) mesoscopic model (called MMC-TDGL model) to simulate the phase separation process. Domain growth is investigated through the pair correlation function. Then we obtain the time-dependent characteristic domain size, which reflects the growth kinetics of the MMC hydrogel. The results indicate that the growth law based on the MMC-TDGL equation is consistent with the modified Lifshitz–Slyozov theory.

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Karageorgos, Filippos F. y Costas Kiparissides. "Prediction of Viscoelastic Properties of Enzymatically Crosslinkable Tyramine–Modified Hyaluronic Acid Solutions Using a Dynamic Monte Carlo Kinetic Approach". International Journal of Molecular Sciences 22, n.º 14 (7 de julio de 2021): 7317. http://dx.doi.org/10.3390/ijms22147317.

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The present study deals with the mathematical modeling of crosslinking kinetics of polymer–phenol conjugates mediated by the Horseradish Peroxidase (HRP)-hydrogen peroxide (H2O2) initiation system. More specifically, a dynamic Monte Carlo (MC) kinetic model is developed to quantify the effects of crosslinking conditions (i.e., polymer concentration, degree of phenol substitution and HRP and H2O2 concentrations) on the gelation onset time; evolution of molecular weight distribution and number and weight average molecular weights of the crosslinkable polymer chains and gel fraction. It is shown that the MC kinetic model can faithfully describe the crosslinking kinetics of a finite sample of crosslinkable polymer chains with time, providing detailed molecular information for the crosslinkable system before and after the gelation point. The MC model is validated using experimental measurements on the crosslinking of a tyramine modified Hyaluronic Acid (HA-Tyr) polymer solution reported in the literature. Based on the rubber elasticity theory and the MC results, the dynamic evolution of hydrogel viscoelastic and molecular properties (i.e., number average molecular weight between crosslinks, Mc, and hydrogel mesh size, ξ) are calculated.

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28

Yu, Chunkan, Felipe Minuzzi y Ulrich Maas. "Numerical Simulation of Turbulent Flames based on a Hybrid RANS/Transported-PDF Method and REDIM Method". Eurasian Chemico-Technological Journal 20, n.º 1 (31 de marzo de 2018): 23. http://dx.doi.org/10.18321/ectj705.

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A hybrid RANS/Transported-PDF model for the simulation of turbulent reacting flows based on automatically reduced mechanisms for the chemical kinetics (reaction-diffusion manifold, REDIM) is presented in this work. For modelling of turbulent reacting flows, chemistry is a key problem and affects largely the accuracy. The PDF method has been widely used since the chemical source term is in a closed form, without any modelling. Despite of this advantage of PDF method, detailed chemical kinetics is not desired due to its heavy computational effort. From this aspect, the detailed chemical kinetics is simplified by the reaction-diffusion manifold (REDIM) method. The hybrid RANS/Transported-PDF model based on REDIM reduced kinetics is applied to simulate the Sandia piloted Flame E, which has a moderate degree of local extinction. The numerical results are validated through comparison with experimental data and show good qualitative and quantitative agreements.

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Muharam, Yuswan. "Detailed kinetic model of oxidation and combustion of n-heptane using an automatic generation of mechanisms". Jurnal Teknik Kimia Indonesia 5, n.º 1 (2 de octubre de 2018): 392. http://dx.doi.org/10.5614/jtki.2006.5.1.8.

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There is continued interest in developing a better understanding of the oxidation and combustion of large hydrocarbons, which are good representative for practical fuels used in automotive engines for a wide range of operating conditions. This interest is motivated by the need to improve the efficiency and performance of currently operating combustion systems, the fuel economy, and the need to reduce pollutant emission. Normal-heptane is one of these hydrocarbons. In this work a detailed chemical kinetic model for the oxidation and combustion of n-heptane has been automatically developed using a computer code called MOLEC. The model consisting of 486 species taking part in 2008 elementary reactions was used to reproduce experimental results of n-heptane oxidation in shock tubes. The experimental study of the ignition delay times of n-heptane/O2/Ar behind a reflected shock wave for equivalence ratios of 0.5-4.0 in a temperature range of 1300 K- 2000 K can be reproduced well by the model. Experimentally derived and numerically predicted ignition delays of n-heptane/air mixtures in a high-pressure shock tube in a wide range of temperatures, pressures, and equivalence ratios agree very well. Sensitivity analyses were performed for shock tube environment in an attempt to identify the most important reactions under the relevant conditions of study.Keywords: Modelling, Oxidation, Combustion, Kinetics, Fuels AbstrakDewasa ini di dunia muncul minat yang berkelanjutan dalam mengembangkan proses oksidasi dan pembakaran hidrokarbon panjang, yang merupakan representatif yang meyakinkan bagi bahan bakar praktis yang digunakan di dalam mesin kendaraan bermotor dalam rentang kondisi operasi yang Iebar. Keminatan ini dipicu oleh keinginan untuk meningkatkan efisiensi dan kinerja sistem pembakaran yang digunakan saat ini, ekonomi bahan bakar serta kebutuhan untuk mengurangi emisi polutan. Normal-heptane merupakan salah satu hidrokarbon ini. Di dalam riset ini sebuah model kinetika kimia detail untuk oksidasi dan pembakaran n-heptana dikembangkan secara otomatis dengan menggunakan sebuah kode komputer yang disebut MOLEC. Model yang terdiri dari 486 spesies yang berperan serta di dalam 2008 reaksi elementer digunakan untuk mereproduksi hasil hasil eksperimen oksidasi n-heptana di dalam shock tubes. Has il eksperimen ignition delay times n heptana/ O2/Ar di dalam shock tube untuk rasio ekuivalensi 0,5-4,0 pada rentang temperatur 1300 K- 2000 K dapat direproduksi dengan baik oleh model. Ignition delay campuran n-heptanal udara hasil eksperimen dan hasil perhitungan numeris di dalam shock tube bertekanan tinggi dalam rentang temperatur, tekanan, dan rasio ekuivalensi yang luas sangat bersesuaian satu sama lain. Analisis sensitivitas dilakukan dalam upaya mengidentifkasi reaksi-reaksi yang paling penting di dalam kondisi kajian yang relevan.Kata Kunci: Modeling, Oksidasi. Pembakaran, Kinetika, Bahan Bakar

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Yang, S. y R. D. Reitz. "Improved combustion submodels for modelling gasoline engines with the level set G equation and detailed chemical kinetics". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 223, n.º 5 (1 de mayo de 2009): 703–26. http://dx.doi.org/10.1243/09544070jauto1062.

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Five combustion submodels have been improved for modelling gasoline engines with the level set G equation and detailed chemical kinetics. These combustion submodels include a transport equation residual model, the introduction of a Damkohler criterion model for assessing the combustion regime of flame-containing cells, the precise calculation of ‘primary heat release’ based on the subgrid scale unburned or burned volumes of flame-containing cells, the modelling of flame front quenching in highly stratified mixtures, and a recently developed primary reference fuel (PRF) mechanism. In the transport equation residual model a fictitious species concept is introduced to account for the residual gases in the cylinder, which have a great effect on the laminar flame speed. The residual gases include carbon dioxide (CO2), water (H2O), and nitrogen (N2) remaining from the previous engine cycle or introduced using exhaust gas recirculation (EGR). This pseudo-species is described by a transport equation. The transport equation residual model differentiates between CO2 and H2O from the previous engine cycle or EGR and that which is from the combustion products of the current engine cycle. The Damkohler criterion model is based on a comparison between a laminar flame propagation timescale and the chemical kinetics timescale to determine whether the level set G-equation model or chemical kinetics should be used for assessing the combustion processes in flame-containing cells. The results from implementation of the Damkohler model range between the G-equation model and pure chemistry, depending on the conditions. The improved primary-heat-release calculation model precisely considers the chemical kinetics heat release in unburned regions of flame-containing cells and thus is thought to be physically reasonable. The simulation results show that the flame-front-quenching model effectively captures the flame quench phenomenon in highly stratified mixtures which are typical in gasoline direct-injection engines. Validation of the new PRF mechanism shows that the calculated ignition delay matches shock tube data very well over a wide range of conditions. The integrated model was used to simulate the combustion process in a gasoline turbocharged direct-injection engine, and the same set of combustion model parameters for both high loads and low loads were used. For both high-load and low-load operating conditions, good agreement with the experimental in-cylinder pressure, heat release rates, and mass fraction burned data was obtained.

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31

Tong, Fei, Mervin P. Hanson y Christopher J. Bardeen. "Analysis of reaction kinetics in the photomechanical molecular crystal 9-methylanthracene using an extended Finke–Watzky model". Physical Chemistry Chemical Physics 18, n.º 46 (2016): 31936–45. http://dx.doi.org/10.1039/c6cp04459j.

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In order to develop an improved description of the photomechanical response of 9-methylanthracene (9MA) microcrystals, a detailed study of its solid-state photochemical reaction kinetics is performed.

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32

Mazier, M. J. Patricia y Peter J. H. Jones. "Model-based compartmental analyses in nutrition research". Canadian Journal of Physiology and Pharmacology 72, n.º 4 (1 de abril de 1994): 415–22. http://dx.doi.org/10.1139/y94-061.

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Kinetic tracer studies have been used extensively in understanding digestion, absorption, and whole-body metabolism of nutrients. Optimal interpretation of changes in tracer levels over time and movement across body pools often requires sophisticated data analysis. The use of model-based compartmental analysis (MCA) can yield more detailed quantitative and predictive information concerning system dynamics, compared with direct stochastic approaches. With MCA, tracer and tracee data from both experimental and literature values are fit to a model that best approximates the system on the basis of experimental data at hand. The number of compartments of the model is determined by the shape of the curve fit to the tracee and tracer data and by literature information. On this basis, MCA can yield information about compartment numbers and sizes, fractional and net turnover, as well as catabolic and synthetic rates. PC-based MCA programs are now available. Whereas earlier editions required use of a programming language, the most recent versions being developed are completely menu driven. Model-based compartmental analyses thus represent important biotechnological advances permitting maximal interpretation of kinetic data in nutrition research.Key words: compartmental analysis, model, kinetics.

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33

Goltsov, Alexey, Maciej Swat, Kirill Peskov y Yuri Kosinsky. "Cycle Network Model of Prostaglandin H Synthase-1". Pharmaceuticals 13, n.º 10 (23 de septiembre de 2020): 265. http://dx.doi.org/10.3390/ph13100265.

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The kinetic model of Prostaglandin H Synthase-1 (PGHS-1) was developed to investigate its complex network kinetics and non-steroidal anti-inflammatory drugs (NSAIDs) efficacy in different in vitro and in vivo conditions. To correctly describe the complex mechanism of PGHS-1 catalysis, we developed a microscopic approach to modelling of intricate network dynamics of 35 intraenzyme reactions among 24 intermediate states of the enzyme. The developed model quantitatively describes interconnection between cyclooxygenase and peroxidase enzyme activities; substrate (arachidonic acid, AA) and reducing cosubstrate competitive consumption; enzyme self-inactivation; autocatalytic role of AA; enzyme activation threshold; and synthesis of intermediate prostaglandin G2 (PGG2) and final prostaglandin H2 (PGH2) products under wide experimental conditions. In the paper, we provide a detailed description of the enzyme catalytic cycle, model calibration based on a series of in vitro kinetic data, and model validation using experimental data on the regulatory properties of PGHS-1. The validated model of PGHS-1 with a unified set of kinetic parameters is applicable for in silico screening and prediction of the inhibition effects of NSAIDs and their combination on the balance of pro-thrombotic (thromboxane) and anti-thrombotic (prostacyclin) prostaglandin biosynthesis in platelets and endothelial cells expressing PGHS-1.

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CLAEYS, WENDIE L., LINDA R. LUDIKHUYZE y MARC E. HENDRICKX. "Formation kinetics of hydroxymethylfurfural, lactulose and furosine in milk heated under isothermal and non-isothermal conditions". Journal of Dairy Research 68, n.º 2 (mayo de 2001): 287–301. http://dx.doi.org/10.1017/s0022029901004745.

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A detailed kinetic study of hydroxymethylfurfural, lactulose and furosine formation was performed upon heating milk at temperatures between 90 °C and 140 °C. In case of prolonged heating, formation kinetics could be described by a fractional conversion model. Considering only the first phase of the model, kinetics could be simplified to a pseudo-zero order model. A first assessment of kinetic parameters was made by isothermal experiments. Data were analysed using both a 2-step linear and a 1-step non-linear regression method. Only for furosine, did the global 1-step regression approach seem to give better results than the individual 2-step regression approach. Next, the estimated parameters kref and Ea were re-evaluated under non-isothermal conditions by subjecting milk to a time variable temperature profile. Given the complexity of Maillard reaction, it seemed better to estimate kinetic parameters under non-isothermal conditions when using a simplified model. Formation of hydroxymethylfurfural, lactulose and furosine was characterized by an Ea value of 90·2 kJ/mol (k110 °C = 1·2 μmol/l, min), 99·1 kJ/mol (k110 °C = 51·5 mg/l, min) and 88·7 kJ/mol (k110 °C = 16·3 mg/100 g protein, min) respectively. Additionally, 90% joint confidence regions were constructed in order to obtain an accurate representation of the statistical confidence associated with the simultaneously estimated parameters.

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35

Sánchez-Monreal, Juan, Pablo A. García-Salaberri y Marcos Vera. "A mathematical model for direct ethanol fuel cells based on detailed ethanol electro-oxidation kinetics". Applied Energy 251 (octubre de 2019): 113264. http://dx.doi.org/10.1016/j.apenergy.2019.05.067.

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36

Xin, Jun, Ning Ding, Ming Chen y Zheng Xu. "Combustion simulation of a 1.9 L turbo-charged diesel engine with detailed chemical kinetics model". International Journal of Powertrains 5, n.º 4 (2016): 412. http://dx.doi.org/10.1504/ijpt.2016.081800.

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37

Xu, Zheng, Ning Ding, Ming Chen y Jun Xin. "Combustion simulation of a 1.9 L turbo-charged diesel engine with detailed chemical kinetics model". International Journal of Powertrains 5, n.º 4 (2016): 412. http://dx.doi.org/10.1504/ijpt.2016.10002673.

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38

Morton, R. H. "Delayed or accelerated oxygen uptake kinetics in the transition from prior exercise?" Journal of Applied Physiology 62, n.º 2 (1 de febrero de 1987): 844–46. http://dx.doi.org/10.1152/jappl.1987.62.2.844.

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Reported experimental findings are at variance with each other on the question as to whether O2 uptake (VO2) kinetics are delayed, advanced, or remain unaltered in the transition from prior exercise. Critical examination of these studies tend to suggest that not a great deal of reliance can be placed on their evidence in attempting to resolve the question. They seem to display a disregard for the theoretical properties of the VO2 kinetic model used; in some cases incorrect statistical inferences appear to have been made; most are mathematically incomplete; and the experimental designs have not been appropriately chosen so as to examine the whole question of altered VO2 kinetics. These points are detailed and discussed so that future designed experiments obtain sufficient reliable evidence with which to resolve the question.

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39

Beirow, Marcel, Ashak Mahmud Parvez, Max Schmid y Günter Scheffknecht. "A Detailed One-Dimensional Hydrodynamic and Kinetic Model for Sorption Enhanced Gasification". Applied Sciences 10, n.º 17 (3 de septiembre de 2020): 6136. http://dx.doi.org/10.3390/app10176136.

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Increased installation of renewable electricity generators requires different technologies to compensate for the associated fast and high load gradients. In this work, sorption enhanced gasification (SEG) in a dual fluidized bed gasification system is considered as a promising and flexible technology for the tailored syngas production for use in chemical manufacturing or electricity generation. To study different operational strategies, as defined by gasification temperature or fuel input, a simulation model is developed. This model considers the hydrodynamics in a bubbling fluidized bed gasifier and the kinetics of gasification reactions and CO2 capture. The CO2 capture rate is defined by the number of carbonation/calcination cycles and the make-up of fresh limestone. A parametric study of the make-up flow rate (0.2, 6.6, and 15 kg/h) reveals its strong influence on the syngas composition, especially at low gasification temperatures (600–650 °C). Our results show good agreement with the experimental data of a 200 kW pilot plant, as demonstrated by deviations of syngas composition (5–34%), lower heating value (LHV) (5–7%), and M module (23–32%). Studying the fuel feeding rate (22–40 kg/h), an operational range with a good mixing of solids in the fluidized bed is identified. The achieved results are summarized in a reactor performance diagram, which gives the syngas power depending on the gasification temperature and the fuel feeding rate.

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40

Adewale, Rasheed y Gabriel da Silva. "Kinetics of C5H4 isomer + H reactions and incorporation of C5H (x = 3 – 5) chemistry into a detailed chemical kinetic model". Combustion and Flame 227 (mayo de 2021): 227–37. http://dx.doi.org/10.1016/j.combustflame.2020.12.046.

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41

Rosero Chicaíza, David Camilo y Bibian A. Hoyos. "Reaction kinetic parameters for a distributed model of transport and reaction in Pd/Rh/CeZrO three-way catalytic converters". DYNA 86, n.º 210 (1 de julio de 2019): 216–23. http://dx.doi.org/10.15446/dyna.v86n210.78596.

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This paper presents a two-dimensional distributed model for the transport and reaction of combustion gases in channels of three-way catalytic converters, considering a detailed reaction kinetics with 16 chemical reactions in palladium and rhodium catalysts, and taking into account diffusive effects within the coating, to obtain a new set of reaction kinetic parameters that do not depend on the thickness of the coating. The model was solved using a finite volume method with a first order upwind scheme and simulations were conducted using computational fluid dynamics. The model with the new distributed reaction kinetic parameters, produced an excellent agreement with the experimental data of concentration at the end of the channels. Also, the model reproduced the most important concentration changes for the gas components in the specified temperature range and allowed simulations with excess oxygen and different thicknesses.

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42

Huys, Quentin J. M., Misha B. Ahrens y Liam Paninski. "Efficient Estimation of Detailed Single-Neuron Models". Journal of Neurophysiology 96, n.º 2 (agosto de 2006): 872–90. http://dx.doi.org/10.1152/jn.00079.2006.

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Biophysically accurate multicompartmental models of individual neurons have significantly advanced our understanding of the input–output function of single cells. These models depend on a large number of parameters that are difficult to estimate. In practice, they are often hand-tuned to match measured physiological behaviors, thus raising questions of identifiability and interpretability. We propose a statistical approach to the automatic estimation of various biologically relevant parameters, including 1) the distribution of channel densities, 2) the spatiotemporal pattern of synaptic input, and 3) axial resistances across extended dendrites. Recent experimental advances, notably in voltage-sensitive imaging, motivate us to assume access to: i) the spatiotemporal voltage signal in the dendrite and ii) an approximate description of the channel kinetics of interest. We show here that, given i and ii, parameters 1–3 can be inferred simultaneously by nonnegative linear regression; that this optimization problem possesses a unique solution and is guaranteed to converge despite the large number of parameters and their complex nonlinear interaction; and that standard optimization algorithms efficiently reach this optimum with modest computational and data requirements. We demonstrate that the method leads to accurate estimations on a wide variety of challenging model data sets that include up to about 104 parameters (roughly two orders of magnitude more than previously feasible) and describe how the method gives insights into the functional interaction of groups of channels.

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43

Lisik, Anna y Witold Musiał. "Conductomeric Evaluation of the Release Kinetics of Active Substances from Pharmaceutical Preparations Containing Iron Ions". Materials 12, n.º 5 (3 de marzo de 2019): 730. http://dx.doi.org/10.3390/ma12050730.

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The aim of this study was to verify the effect of the formulation on the release kinetics of active substances from preparations containing iron ions using in-line conductivity measurements. A simple, fast method was developed and may be applied for detailed evaluation of some kinetics factors obtained from the release data. Four different equations were used: zero-order equation, first-order equation, models: Korsmeyer–Peppas and Hixson–Crowell. Values of the determined half-time release for zero and first-order kinetic models ranged from 11.56 to 89.97 min. In the case of analysis according to these typical models, the values of the square root of the correlation coefficients were included between 0.9916 and 0.9995. The results transformed for the Hixson–Crowell model as constant release Ks, ranged between 0.0160 and 0.0437. The values of the respective calculated squares of the correlation coefficient ranged from 0.9933 to 0.9959. The determined release rate constants according to the Korsmeyer–Peppas model were between 0.0023 and 0.1630. The coefficients ‘n’ of the Korsmeyer–Peppas equation did not exceed 1.2 with the corresponding r2 values 0.9408–0.9960. Obtained results confirmed that the method is applicable for evaluation of selected drug compositions containing iron ions.

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44

Mathieu, Olivier, Sean P. Cooper, Sulaiman A. Alturaifi y Eric L. Petersen. "Assessing NO2-Hydrocarbon Interactions during Combustion of NO2/Alkane/Ar Mixtures in a Shock Tube Using CO Time Histories". Fuels 3, n.º 1 (4 de enero de 2022): 1–14. http://dx.doi.org/10.3390/fuels3010001.

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Modern gas turbines use combustion chemistry during the design phase to optimize their efficiency and reduce emissions of regulated pollutants such as NOx. The detailed understanding of the interactions during NOx and natural gas during combustion is therefore necessary for this optimization step. To better assess such interactions, NO2 was used as a sole oxidant during the oxidation of CH4 and C2H6 (the main components of natural gas) in a shock tube. The evolution of the CO mole fraction was followed by laser-absorption spectroscopy from dilute mixtures at around 1.2 atm. The experimental CO profiles were compared to several modern detailed kinetics mechanisms from the literature: models tuned to characterize NOx-hydrocarbons interactions, base-chemistry models (C0–C4) that contain a NOx sub-mechanism, and a nitromethane model. The comparison between the models and the experimental profiles showed that most modern NOx-hydrocarbon detailed kinetics mechanisms are not very accurate, while the base chemistry models were lacking accuracy overall as well. The nitromethane model and one hydrocarbon/NOx model were in relatively good agreement with the data over the entire range of conditions investigated, although there is still room for improvement. The numerical analysis of the results showed that while the models considered predict the same reaction pathways from the fuels to CO, they can be very inconsistent in the selection of the reaction rate coefficients. This variation is especially true for ethane, for which a larger disagreement with the data was generally observed.

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45

Robson, Joseph D., Nicolas Kamp, A. Sullivan y Hugh R. Shercliff. "Modelling Precipitate Evolution during Friction Stir Welding of Aerospace Aluminium Alloys". Materials Science Forum 519-521 (julio de 2006): 1101–6. http://dx.doi.org/10.4028/www.scientific.net/msf.519-521.1101.

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Two models to predict the microstructural evolution and post-weld properties of friction stir welds in aerospace aluminium alloys are presented. The first model is a develop- ment of an existing semi-empirical method for the prediction of hardness profiles after welding, calibrated using isothermal hardness data. Post-weld natural ageing is accounted for, and a new method that predicts natural ageing kinetics is introduced. Once calibrated, the model is shown to accurately predict weld hardness profiles. However, this model does not explicitly predict the microstructure and therefore cannot readily be extended to model other properties. It can also only be applied to alloys welded in peak or overaged conditions. The second model aims to explicitly predict the heterogeneous precipitate distributions obtained after welding for any initial condition. It is based on classical kinetic theory and the numerical framework of Kampmann and Wagner. Multiple nucleation sites and multiple phases are accounted for. This model provides detailed microstructural information required for prediction of complex properties.

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46

Chen, Timothy Bo Yuan, Ivan Miguel De Cachinho Cordeiro, Anthony Chun Yin Yuen, Wei Yang, Qing Nian Chan, Jin Zhang, Sherman C. P. Cheung y Guan Heng Yeoh. "An Investigation towards Coupling Molecular Dynamics with Computational Fluid Dynamics for Modelling Polymer Pyrolysis". Molecules 27, n.º 1 (4 de enero de 2022): 292. http://dx.doi.org/10.3390/molecules27010292.

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Building polymers implemented into building panels and exterior façades have been determined as the major contributor to severe fire incidents, including the 2017 Grenfell Tower fire incident. To gain a deeper understanding of the pyrolysis process of these polymer composites, this work proposes a multi-scale modelling framework comprising of applying the kinetics parameters and detailed pyrolysis gas volatiles (parent combustion fuel and key precursor species) extracted from Molecular Dynamics models to a macro-scale Computational Fluid Dynamics fire model. The modelling framework was tested for pure and flame-retardant polyethylene systems. Based on the modelling results, the chemical distribution of the fully decomposed chemical compounds was realised for the selected polymers. Subsequently, the identified gas volatiles from solid to gas phases were applied as the parent fuel in the detailed chemical kinetics combustion model for enhanced predictions of toxic gas, charring, and smoke particulate predictions. The results demonstrate the potential application of the developed model in the simulation of different polymer materials without substantial prior knowledge of the thermal degradation properties from costly experiments.

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47

Loew, Stephan, Alfred Fahr y Sylvio May. "Modeling the Release Kinetics of Poorly Water-Soluble Drug Molecules from Liposomal Nanocarriers". Journal of Drug Delivery 2011 (7 de junio de 2011): 1–10. http://dx.doi.org/10.1155/2011/376548.

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Liposomes are frequently used as pharmaceutical nanocarriers to deliver poorly water-soluble drugs such as temoporfin, cyclosporine A, amphotericin B, and paclitaxel to their target site. Optimal drug delivery depends on understanding the release kinetics of the drug molecules from the host liposomes during the journey to the target site and at the target site. Transfer of drugs in model systems consisting of donor liposomes and acceptor liposomes is known from experimental work to typically exhibit a first-order kinetics with a simple exponential behavior. In some cases, a fast component in the initial transfer is present, in other cases the transfer is sigmoidal. We present and analyze a theoretical model for the transfer that accounts for two physical mechanisms, collisions between liposomes and diffusion of the drug molecules through the aqueous phase. Starting with the detailed distribution of drug molecules among the individual liposomes, we specify the conditions that lead to an apparent first-order kinetic behavior. We also discuss possible implications on the transfer kinetics of (1) high drug loading of donor liposomes, (2) attractive interactions between drug molecules within the liposomes, and (3) slow transfer of drugs between the inner and outer leaflets of the liposomes.

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48

Koledina, K. F., I. M. Gubaydullin y S. N. Koledin. "Mathematical modeling and multiobjective optimization complex catalyst hydroalumination reaction of olefins with diisobutylaluminium hydride". Journal of Physics: Conference Series 2131, n.º 2 (1 de diciembre de 2021): 022015. http://dx.doi.org/10.1088/1742-6596/2131/2/022015.

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Abstract A mathematical model for the catalyst hydroalumination reaction of olefins with diisobutylaluminium hydride has been developed. In solving the direct kinetic problem applies multi-step method Gere variable order. When solving systems of ordinary differential equations in chemical kinetics, it is necessary to fulfill the balance relations at each sampling point. That ensures the fulfillment of the law of conservation of matter and the convergence of the numerical method. For the catalytic reaction of hydroalumination olefins in the presence of the organoaluminum compound diisobutylaluminum hydride, the problem of multicriteria optimization reaction conditions was solved based on a detailed kinetic model. The solutions found make it possible to optimally select the reaction conditions to achieve the maximum yield of target products, which can be based on the subsequent introduction of the laboratory reaction into production.

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49

Craig, Jonathan M., Andrew H. Laszlo, Henry Brinkerhoff, Ian M. Derrington, Matthew T. Noakes, Ian C. Nova, Benjamin I. Tickman, Kenji Doering, Noah F. de Leeuw y Jens H. Gundlach. "Revealing dynamics of helicase translocation on single-stranded DNA using high-resolution nanopore tweezers". Proceedings of the National Academy of Sciences 114, n.º 45 (16 de octubre de 2017): 11932–37. http://dx.doi.org/10.1073/pnas.1711282114.

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Enzymes that operate on DNA or RNA perform the core functions of replication and expression in all of biology. To gain high-resolution access to the detailed mechanistic behavior of these enzymes, we developed single-molecule picometer-resolution nanopore tweezers (SPRNT), a single-molecule technique in which the motion of polynucleotides through an enzyme is measured by a nanopore. SPRNT reveals two mechanical substates of the ATP hydrolysis cycle of the superfamily 2 helicase Hel308 during translocation on single-stranded DNA (ssDNA). By analyzing these substates at millisecond resolution, we derive a detailed kinetic model for Hel308 translocation along ssDNA that sheds light on how superfamily 1 and 2 helicases turn ATP hydrolysis into motion along DNA. Surprisingly, we find that the DNA sequence within Hel308 affects the kinetics of helicase translocation.

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50

Sierra Jimenez, Valentina, Carlos M. Ceballos Marín y Farid Chejne Janna. "Simulation of thermochemical processes in Aspen Plus as a tool for biorefinery analysis". CT&F - Ciencia, Tecnología y Futuro 11, n.º 2 (27 de diciembre de 2021): 27–38. http://dx.doi.org/10.29047/01225383.372.

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The development of tools for the synthesis, design, and optimization of biorefineries requires deep knowledge of the thermochemical processes involved in these schemes. For this project, three models from scientific literature were implemented to simulate the processes: fast pyrolysis in a fluidized bed, fixed-bed, and fluidized-bed gasification using the Aspen PlusTM software. These models allow the user to obtain performance, consumption, and cost parameters necessary for the design and optimization of biorefineries schemes. The fast pyrolysis model encompasses a detailed description of biomass decomposition and kinetics of the process (149 reactions). In the fixed-bed gasification process, seven reactions that model the process have been integrated into two equilibrium reactors that minimize the Gibbs free energy. The model used for fluidized bed gasification considers both hydrodynamic and kinetic parameters, as well as a kinetic model that considers the change in the combustion reaction rate of biomass with oxygen leading to a change in temperature. Due to the complexity and detail of all these models, it was necessary to use FORTRAN subroutines and iterative Excel macros linked to Aspen PlusTM. Finally, the results of each simulation were validated with data from the model sources, as well as experimental results from the literature.

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