Method For Kinetic Analysis Research Articles

Independent parallel pyrolysis kinetics of model components in sewage sludge analyzed by BPM neural network.

Analyzing the kinetic behavior of sewage sludge pyrolysis is essential for the design of efficient reactors to produce biofuel and syngas. To understand the complex pyrolysis process of sewage sludge, we pyrolyzed six model components (i.e., cellulose, hemicellulose, lignin, protein, soluble sugars, and lipid) using a thermogravimetric analyzer. The effects of the heating rate on the pyrolysis process were examined at four different heating rates (5, 15, 25, and 50 °C/min). As temperature increased, the derivative thermogravimetric peaks shifted to higher temperature zones. The temperature ranges of the maximum mass loss rate for cellulose, hemicellulose, lignin, protein, soluble sugars, and lipid were within 326.1-368.0 °C, 288.7-315.5 °C, 375.1-429.4 °C, 291.9-308.0 °C, 251.0-314.1 °C, and 410.8-454.1 °C, respectively. The apparent activation energies of the model components were obtained using non-isothermal kinetic analysis methods (Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose). In addition, a back-propagation artificial neural network with a momentum algorithm (BPM) was developed to predict the relationship between the pyrolysis experiment and the activation value. The best BPM model (BPM5) for predicting the cellulose pyrolysis was identified.

Modeling the Temperature Effect on the Growth of Uropathogenic Escherichia coli in Sous-Vide Chicken Breast.

Uropathogenic Escherichia coli (UPEC) is known to cause 65-75% of human urinary tract infection (UTI) cases. Poultry meat is a reservoir of UPEC, which is suspected to cause foodborne UTIs. In the present study, we aimed to determine the growth potential of UPEC in ready-to-eat chicken breasts prepared by sous-vide processing. Four reference strains isolated from the urine of UTI patients (Bioresource Collection and Research Center [BCRC] 10,675, 15,480, 15,483, and 17,383) were tested by polymerase chain reaction assay for related genes to identify their phylogenetic type and UPEC specificity. A cocktail of these UPEC strains was inoculated into sous-vide cooked chicken breast at 103-4 colony-forming unit (CFU)/g and stored at 4°C, 10°C, 15°C, 20°C, 30°C, and 40°C. Changes in the populations of UPEC during storage were analyzed by a one-step kinetic analysis method using the U.S. Department of Agriculture [USDA] Integrated Pathogen Modeling Program-Global Fit [IPMP-Global Fit]. The results showed that the combination of the no lag phase primary model and the Huang square-root secondary model fitted well with the growth curves to obtain the appropriate kinetic parameters. This combination for predicting UPEC growth kinetics was further validated using it to study additional growth curves at 25°C and 37°C, which showed that the root mean square error, bias factor, and accuracy factor were 0.49-0.59 (log CFU/g), 0.941-0.984, and 1.056-1.063, respectively. In conclusion, the models developed in this study are acceptable and can be used to predict the growth of UPEC in sous-vide chicken breast.

Preparation of a Transient Thermal Expansion Rock Cracking Agent by Deposition Method and Its Nonisothermal Kinetics Study with Isoconversional Procedure and DAEM.

Cracking agents are indispensable and important products for national energy exploitation and large-scale infrastructure construction. Transient thermal expansion rock cracking agent is a new cracking agent product with excellent performance that has just appeared in recent years. However, it is still prepared by mechanical ball milling, which is considered not the best choice among traditional methods for preparing energetic materials. In this paper, a transient thermal expansion rock splitting agent was prepared by the chemical deposition method using carbon black and calcium peroxide as raw materials. The TG/DTG results show that the mass loss of the sample can be divided into four stages with the increase of temperature. It is worth noting that the mass loss of the TG curve of the sample during the entire thermal decomposition process is 93.385%, and the instantaneous weight loss is 78.07% (β = 15 °C/min). Kinetic analysis of the thermal decomposition process of the samples was performed using an isotransformation program and a distributed activation energy model (DAEM). The activation energy E α of the thermal decomposition of the sample was iteratively calculated. The results show that the a-E a curve of the sample can be divided into two stages. The pyrolysis kinetics of the first stage was successfully analyzed by the DAEM method and its thermal conversion behavior was predicted. The thermal decomposition behavior of the second stage was analyzed by a traditional kinetic analysis method.

Electrocatalysis of Selective Chlorine Evolution Reaction: Fundamental Understanding and Catalyst Design

<p>The electrochemical chlorine evolution reaction (CER) is an important electrochemical reaction and has been widely used in chlor–alkali electrolysis, on-site generation of ClO<sup>−</sup>, and Cl<sub>2</sub>-mediated electrosynthesis. Although precious metal-based mixed metal oxides (MMOs) have been used as CER catalysts for more than half a century, they intrinsically suffer from a selectivity problem between the CER and parasitic oxygen evolution reaction (OER). Hence, the design of selective CER electrocatalysts is critically important. In this review, we provide an overview of the fundamental issues related to the electrocatalysis of the CER and design strategies for selective CER electrocatalysts. We present experimental and theoretical methods for assessing the active sites of MMO catalysts and the origin of the scaling relationship between the CER and the OER. We discuss kinetic analysis methods to understand the kinetics and mechanisms of CER. Next, we summarize the design strategies for new CER electrocatalysts that can enhance the reactivity of MMO-based catalysts and overcome their scaling relationship, which include the doping of MMO catalysts with foreign metals and the development of non-precious metal-based catalysts and atomically dispersed metal catalysts.</p>

Fusion calorimetric experiments and QSPR modeling to inversely explore the accuracy of thermodynamic methods: A case study of the apparent activation energies of 18 aromatic nitro compounds

The choice of thermodynamic analysis method will directly affect the accuracy of thermal hazard assessment. In this work, two advanced calorimetric experiments were used to obtain the pyrolysis parameters of 18 aromatic nitro compounds under dynamic and adiabatic conditions, aiming at the inherent thermal risk and explosion characteristics of aromatic nitro compounds in important chemical processes. The multiple linear regression (MLR) and artificial neural network (ANN) models corresponding to six typical thermodynamic analysis methods (FWO, Kissinger, Starink, Friedman, Townsend, and TMRad) were constructed by using the apparent activation energy (Ea) calculated by fitting as the basic sample data and combining with quantitative structure-property relationship (QSPR). Two kinds of parameters in internal and external validation were used as the main indexes to judge the accuracy and reliability of different kinetic analysis methods applied to aromatic nitro compounds. This study is expected to provide theoretical support and technical guidance for the chemical industry in the thermal hazard assessment process of nitro compounds.

Elucidating Electrocatalytic Oxygen Reduction Kinetics via Intermediates by Time-Dependent Electrochemiluminescence.

Facile evaluation of oxygen reduction reaction (ORR) kinetics for electrocatalysts is critical for sustainable fuel-cell development and industrial H2 O2 production. Despite great success in ORR studies using mainstream strategies, such as the membrane electrode assembly, rotation electrodes, and advanced surface-sensitive spectroscopy, the time and spatial distribution of reactive oxygen species (ROS) intermediates in the diffusion layer remain unknown. Using time-dependent electrochemiluminescence (Td-ECL), we report an intermediate-oriented method for ORR kinetics analysis. Owing to multiple ultrasensitive stoichiometric reactions between ROS and the ECL emitter, except for electron transfer numbers and rate constants, the potential-dependent time and spatial distribution of ROS were successfully obtained for the first time. Such exclusively uncovered information would guide the development of electrocatalysts for fuel cells and H2 O2 production with maximized activity and durability.

Elucidating Electrocatalytic Oxygen Reduction Kinetics via Intermediates by Time‐Dependent Electrochemiluminescence

AbstractFacile evaluation of oxygen reduction reaction (ORR) kinetics for electrocatalysts is critical for sustainable fuel‐cell development and industrial H2O2 production. Despite great success in ORR studies using mainstream strategies, such as the membrane electrode assembly, rotation electrodes, and advanced surface‐sensitive spectroscopy, the time and spatial distribution of reactive oxygen species (ROS) intermediates in the diffusion layer remain unknown. Using time‐dependent electrochemiluminescence (Td‐ECL), we report an intermediate‐oriented method for ORR kinetics analysis. Owing to multiple ultrasensitive stoichiometric reactions between ROS and the ECL emitter, except for electron transfer numbers and rate constants, the potential‐dependent time and spatial distribution of ROS were successfully obtained for the first time. Such exclusively uncovered information would guide the development of electrocatalysts for fuel cells and H2O2 production with maximized activity and durability.

Investigation of zeolite H-β effect on pyrolysis of polystyrene by multiple kinetic analysis methods.

For studying the effects of H-β zeolite on the pyrolysis of polystyrene (PS), non-isothermal thermogravimetric measurements were conducted in N2 under 5, 10, 15, and 20K/min. The results show that the addition of 10 ~ 30 wt.% H-β zeolite can significantly decrease the initial pyrolysis temperature of PS, indicative of the catalytic effect of zeolite used. Through kinetic analysis of the pyrolysis of PS blends, the isoconversional activation energies are calculated to be 121.8 ~ 191.9, 92.1 ~ 173.8, and 116.7 ~ 192.4kJ/mol for the PS blends with zeolite loading of 10, 20, and 30 wt.%, respectively. Meanwhile, the pyrolysis degradation functions are determined through the Master-plots method integrated with a recently developed compensation-effect method to follow chemical reaction mechanism with the reaction order of 0.9, 1.0, and 0.6 for PS/zeolite blends of 10, 20, and 30 wt.% loading, and their pre-exponential factors are respectively calculated to be 6.18 × 108 ~ 5.71 × 1011, 2.36 × 106 ~ 9.23 × 1011, and 8.38 × 107 ~ 1.11 × 1012min-1. Our work may provide some insights for how to better describe experimental results with theoretical predications and necessary information for performing any potential pyrolysis designs.

Кинетика отжига деформационных дефектов в модельном сплаве Zr – Sn – Fe – Cr

The work is devoted to the study of annealing of deformation defects in the Zr – 1,4 wt. % Sn – 0,2 wt. % Fe – 0,1 wt. % Cr model alloy. The final stage of thermomechanical treatment of the alloy is cold deformation up to 25 %, heating up to 400 °C and holding at this temperature for 3 hours. The study was performed by differential scanning calorimetry (DSC) in the temperature range from room temperature to 620 – 680 °C at a heating rate of 2 – 5 °C/min. The alloy structure before and after DSC was studied by transmission electron microscopy. Two stages of annealing of deformation defects were recorded, which are interpreted as polygonization and primary recrystallization of the alloy. By the method of model kinetic analysis, it was found that the activation energy of the first stage is 127 kJ/mol, the activation energy of the second stage is 146 kJ/mol. Avrami – Erofeev equation is used as kinetic equation.

Insight into kinetic and Thermodynamic Analysis methods for lignocellulosic biomass pyrolysis

Pyrolysis is particularly attractive because it can convert lignocellulosic biomass into bio-oil, gases and solid charcoal in an efficient and environmentally friendly way. Determining the kinetic and thermodynamic parameters is fundamental to elucidate the reaction mechanisms and optimize biomass pyrolysis processes. The applicability and accuracy of kinetic and thermodynamic methods are systematically studied by analyzing theoretically simulated processes which simulate biomass pyrolysis processes and using statistical analyses. In terms of activation energy calculation, the Friedman method is capable of providing accurate activation energies, whereas the KAS and FWO isoconversional methods lead to some systematic errors in the resultant activation energies. The accuracy of the Kissinger method for estimating the frequency factor is dependent on the variation degree of kinetic parameters with conversion. The conventional method for determining thermodynamic parameters is based on the conversion rate peak temperature, which has no theoretical basis. Therefore, the concept of effective thermodynamic parameters is proposed, which are dependent on conversion and heating rate. And the thermodynamic analysis of the simulated processes is comprehensively investigated. Results revealed that the accuracy of the resulting thermodynamic parameters from the conventional method is dependent on the variation degree of kinetic parameters with conversion. It is expected that this study will provide an analysis framework and methodological guideline for the kinetic and thermodynamic analyses of biomass pyrolysis.

Unravelling the Mechanism of Nickel Mediated Cross‐Electrophile‐ Electrophile Coupling Between Katritzky Salts and Acid Chlorides

AbstractModern nickel‐mediated cross‐electrophile coupling reactions devoid of organometallic nucleophiles have garnered a great deal of interest due to their ability to enhance functional group compatibility. Despite the recent advances in the field, various mechanistic pathways, such as radical chain and sequential oxidative addition, in addition to finding the active nickel species and reductant, render the reaction complex. Although the reduction of Ni(II) complexes by heterogeneous Mn could produce either Ni(I) or Ni(0) species, the latter is more generally proposed as an active species. Likewise, Ni(I) mediated reduction of pyridinium salts is commonly invoked to generate the transient alkyl radicals. In stark contrast, we present a comprehensive mechanistic examination and experimental evidence for the intermediacy of Ni(I) species, a synergistic reduction of pyridinium salts by Ni(I) and Mn. Using a combination of kinetic analysis, control experiments, and spectroscopic methods, the rate‐limiting reductive alkylation and resting state Ni(II) species have been identified.

Influence of Agitator Shape on Characteristics and Grinding Efficiency of Attritor Mill

Grinding is a unit of operation of a pure mechanical process. An attritor is a grinder able to be used for fine or selective grinding. However, few studies have reported on the optimum design for the attritor. The attritor’s grinding characteristics and grinding effect depend not only on the operating conditions, but also on the geometry of the agitator. Therefore, we investigated the effect of the agitator shape on the grinding efficiency from the viewpoint of experiments, kinetic analysis, and discrete element method (DEM) simulations. We conducted grinding experiments with two different agitators. One was Agitator A, a traditional design with two pairs of 90° staggered mixing arms at the middle and bottom of the mixing shaft. The other was Agitator B, with a lower mixing arm inclined by 10° along the horizontal direction. We found that the grinding rate constant of Agitator B was approximately 40% greater than that of Agitator A. Although the size distribution of the particles was relatively dispersed after grinding with Agitator B, the distribution was concentrated mainly within two ranges (<0.5 mm and 2–4 mm) with Agitator A. These results and an elemental analysis of each size fraction suggested that the dominating grinding mode in Agitator A was surface grinding, whereas in Agitator B, it was bulk grinding. In terms of the influence of the agitator shape, the DEM simulation results showed that the kinetic energy of the grinding media in Agitator B was 0.0046 J/s, i.e., larger than the 0.0035 J/s obtained for Agitator A. A collision energy analysis showed that the dominating collision was between the media and wall in the tangential direction for both models. The collision energy of the media in Agitator B was larger than that of that in Agitator A. The results from the DEM simulation can help us evaluate the experimental results and infer the reasons why the grinding rate constant in Agitator B is larger than that in Agitator A.

Effect of Cooling Rate and High N Content on the Precipitation and Growth of AlN Inclusions in Fe–23Mn–2Al–0.08 V High‐Manganese Nonmagnetic Steel

Industrial experiments are carried out to investigate the precipitation and growth of AlN in Fe–23Mn–2Al–0.08 V steel with nitrogen content up to 80–92 ppm. AlN inclusions can be precipitated before solidification. The morphologies of AlN are mainly divided into hexagonal and needle‐like shapes. With the cooling rate decreasing from 36.66 to 0.71 K s−1, the equivalent diameters of typical AlN increase from 7.56 to 24.20 μm, and the total amount decreases from 203.01 to 60.00 mm−2. The relationship between the cooling rate and the number density is obtained: . The element segregation analyzed by electronic probe microanalyzer shows that aluminum concentration is low in interdendritic regions but high in dendrites. Aluminum segregation is very weak, and there is almost no nitrogen segregation. Thermodynamic calculation shows that AlN can precipitate before solidification with the nitrogen content higher than 58 ppm. The predicted results of AlN growth by kinetic analysis method can well reveal the growth trend. The nitrogen content (≥58 ppm) has a negligible effect on the size of AlN when the cooling rates are 3.02 and 0.71 K s−1, while the cooling rate has a significant effect on the size of AlN.

Thermal Degradation Behavior of Thiol-ene Composites Loaded with a Novel Silicone Flame Retardant.

A novel silicone flame retardant PMDA was synthesized and blended with a commercial thiol–ene (TE) to obtain a flame-retardant TE (FRTE) composite. The cone calorimeter measurement showed the incorporation of PMDA improved the flame retardancy of the TE composite at concentrations of 5 wt%. The thermal stability and degradation mechanism of FRTE in nitrogen was studied by thermogravimetric analysis. The degradation behaviour of TE containing a PMDA flame retardant was found to be changed. The kinetics of thermal degradation was evaluated by Kissinger method and Flynn–Wall–Ozawa method. The results showed that the activation energies of the FRTE degradation were higher than those of neat TE. However, the degradation mechanism of the TE matrix was not changed by the incorporation of flame-retardant PMDA. In this study, the flame-retardant mechanism of PMDA flame-retardant TE polymer was explained by using two kinetic analysis methods.

Fluoroalkylated-GAP copolymers (GAP-FP) as promising energetic binders

The development of a novel energetic block copolymer of glycidyl azide polymer (GAP) and fluoropolymer (FP) using a boron trifluoride-tetrahydrofuran complex/diol initiator system is reported herein. Well-defined compositions of the GAP-FP copolymers in two different GAP to FP ratios (1:1 and 1:3) were synthesized by tailoring the desired molecular weights of each block in the copolymer, demonstrating the synthetic versatility of such a copolymer system. The resultant GAP-FP copolymers represent a unique hybrid binder system with tunable energy releasing and oxidizing potentials intended for metallized formulations. Thermogravimetric analysis showed that the carbonaceous residue usually formed from the decomposition of GAP could be reduced significantly by the copolymerization with FP. Isoconversional method of kinetic analysis of the GAP-FP copolymers revealed an increasing dependence of the effective activation energy on the extent of conversion. The increasing dependence suggested a mechanism of the competing reactions that were found to be between the reactions of FP triggered oxidation and intermolecular crosslinking of the polyimine intermediates formed from GAP decomposition that ultimately resulted in the reduction of the carbonaceous residue.

ВЛИЯНИЕ ОКСИДА АЗОТА НА КИНЕТИЧЕСКИЕ СВОЙСТВА ФЕРМЕНТОВ АНТИОКСИДАНТНОЙ ЗАЩИТЫ КРОВИ ПРИ ЭКСПЕРИМЕНТАЛЬНОЙ ТЕРМИЧЕСКОЙ ТРАВМЕ

Combined thermal trauma (CTT), including thermal inhalation exposure and burns of the skin, is often found in victims entering burn centers. The aim of the study was to study the peculiarities of regulation of antioxidant protection enzymes in the blood during experimental CTT under the influence of NO. The experiment was carried out on 30 white male rats of the Wistar line. The animals were divided into 3 groups of equal numbers: 1 – intact rats; 2 – control – animals with CTT; 3 – experimental – animals with CTT who received inhalation NO. Rats under anesthesia were subjected to contact burn (20% of the body surface) and thermal inhalation exposure. The animals were removed from the experiment after CTT for 10 days. The activity of superoxide dimsutase (SOD), catalase, glutathione reductase (GR) and glucose-6-phosphate dehydrogenase (Gl-6-fDh) was determined in red blood cells. Inhalation-external exposure to NO during CTT was carried out daily for 10 days for 10 minutes. Kinetic parameters of the enzymatic reaction were calculated. Statistical processing of the results was carried out using Statistica 6.0 (Statsoft Inc., USA). It was shown that against the background of a decrease in the activity of antioxidant enzymes in the blood during CTT, the greatest inhibition was noted for catalase. The kinetic method of analysis for the first time established the nature of enzyme inhibition in CTT: for SOD and catalase in erythrocytes – two-parametrically consistent, for GR and Gl-6–fDh - catalytic. Inhalations of NO during CTT activated SOD, catalase, GR and Gl-6-fDh.

Novel method for kinetic analysis applied to transport by the uniporter OCT2.

The kinetics of solute transport shed light on the roles these processes play in cellular physiology, and the absolute values of the kinetic parameters that quantitatively describe transport are increasingly used to model its impact on drug clearance. However, accurate assessment of transport kinetics is challenging. Although most carrier-mediated transport is adequately described by the Michaelis-Menten equation, its use presupposes that the rates of uptake used in the analysis of maximal rates of transport (Jmax) and half-saturation constants (Kt) reflect true unidirectional rates of influx from known concentrations of substrate. Most experimental protocols estimate the initial rate of transport from net substrate accumulation determined at a single time point (typically between 0.5 and 5 min) and assume it reflects unidirectional influx. However, this approach generally results in systematic underestimates of Jmax and overestimates of Kt; the former primarily due to the unaccounted impact of efflux of accumulated substrate, and the latter due to the influence of unstirred water layers. Here, we describe the bases of these time-dependent effects and introduce a computational model that analyzes the time course of net substrate uptake at several concentrations to calculate Jmax and Kt for unidirectional influx, taking into account the influence of unstirred water layers and mediated efflux. This method was then applied to calculate the kinetics of transport of 1-methyl-4-phenylpryridinium and metformin by renal organic cation transporter 2 as expressed in cultured Chinese hamster ovary cells.NEW & NOTEWORTHY Here, we describe a mathematical model that uses the time course of net substrate uptake into cells from several increasing concentrations to calculate unique kinetic parameters [maximal rates of transport (Jmax) and half-saturation constants (Kt)] of the process. The method is the first to take into consideration the common complicating factors of unstirred layers and carrier-mediated efflux in the experimental determination of transport kinetics.

Insights into the decomposition kinetics of groundnut shell: An advanced isoconversional approach

In this work, the thermal decomposition kinetics of groundnut shell is investigated using a novel isoconversional approach. It combines the mathematical deconvolution approach with the isoconversional kinetic analysis methods. The thermogravimetric data of groundnut shells at six different heating rates ranging from 5 to 40 K min−1 has been used to make kinetic and thermodynamic predictions for the pyrolysis process. Extensive results on effective activation energy, pre-exponential factor, reaction mechanism, free energy change, entropy change and enthalpy of the process are discussed in detail. Groundnut pyrolysis is envisioned to occur via the independent decomposition of three pseudocomponents, i.e., cellulose, hemicellulose, and lignin. The estimated values of activation energy for each pseudocomponent show a weak dependence on conversion. The model predicts average activation energy of 126.17, 125.41, and 80.04 kJ mol−1 for the first, second, and third pseudocomponent. The decomposition of cellulose and hemicellulose is observed to follow first and second-order kinetics respectively. The lignin decomposition is governed by a three-dimensional diffusion-based model. The work demonstrates an efficient, novel strategy for identifying the prominent independent reactions occurring in the overall decomposition process of biomass. The kinetic and thermodynamic results presented here are crucial for designing pyrolysis reactors with groundnut shells as the potential feedstock.

Research on fault diagnosis method of deep transfer learning driven by simulation data

Sufficient labeled fault samples are the key to ensuring the performance of deep learning diagnostic models. However, in practical engineering applications, machinery and equipment operate normally most of the time, and it is difficult to collect enough fault data. In contrast, through the kinetics analysis method, simulation data sets of various fault types can be easily obtained. However, there is a difference in distribution between simulation data and real data. The deep learning diagnosis model trained directly with simulation data lacks versatility and cannot be applied to fault diagnosis of real data. To this end, this paper proposes a simulation data-driven deep transfer learning fault diagnosis method, which applies the fault diagnosis knowledge in the simulation data to the real data fault diagnosis task. The effectiveness of the method is verified by experiments on the two-stage planetary gearbox in the Drivetrain Diagnostics Simulator (DDS) test bench.

Tartramide Ligands for Copper‐Catalyzed N‐Arylation at Room Temperature

AbstractReadily accessible tartramide ligands have been demonstrated to promote copper‐catalysed N‐arylation under mild conditions. In addition, the coupling protocol employs cheap and readily available pre‐catalyst, ligand, and base (NaOH), and overcomes many current limitations often associated with Ullmann coupling: it can be run with low catalyst loadings, does not require the use of excess amine, operates at room temperature, is fully homogeneous, and displays improved tolerance to air and moisture. Detailed kinetic studies using reaction progress kinetic analysis (RPKA) methods have provided insight into the factors influencing the reaction rate in terms of impact of ligand structure, reactant/catalyst dependence and catalyst (in)stability. These kinetic insights have been used in a quality‐by‐design approach for further optimization of the reaction protocol. The reaction scope was extended to 22 examples, showing broad applicability for a wide range of substituted aryl iodides with both primary and secondary amines.magnified image