Method For Kinetic Analysis Research Articles

Thermal decomposition analysis of 2,2-di-(tert-butylperoxy)butane in non-isothermal condition by DSC and GC/MS

The thermal decomposition characteristics and the thermal safety parameters of 2,2-di(tert-butylperoxy)butane (DBPB) was investigated by differential scanning calorimetry (DSC). The apparent activation energy (Ea) was evaluated by three different kinetic analysis methods based on the DSC experimental results. By the method of Malek, Zhuravlev-Lesokhin-Tempelman (Z-L-T) equation was the most probable mechanism function of DBPB decomposition. Furthermore, for the safety of storage and transportation, the self-accelerating decomposition temperature (SADT) of 50 kg standard packaged 50% w.t. DBPB solution was calculated by Semenov model. And the decomposition products were separated and identified by gas chromatograph/mass spectrometer (GC/MS). The decomposition process of DBPB was inferred which may help us to interpret the decomposition mechanism of di-functional peroxides. Finally, the findings of this study could do a contribution to preventing the thermal hazardous accidents, which would happen during DBPB chemical process, transportation and storage.

The Thermal Investigation, Thermokinetic Analysis and Antimicrobial Activity of Two New Energetic Materials Obtained from Nucleophilic Substitution of Nitro Pyridine Ring

2-Chloro-3 and 5-dinitropyridine were put into reaction with hydrazine and 3-aminopyrazole to obtain two new highly nitrogenous energetic substances. These energetic substances are; N(3,5-dinitropyridyn-2-yl) hydrazine (I), and N(3,5-dinitropyridyn-2-yl)3-aminopyrazole (II). These substances were characterized with element analysis, mass spectroscopy, IR spectroscopy, 1HNMR and 13CNMR methods. Besides, the substances were analyzed with TG and thermal decomposition mechanisms were interpreted. Apart from these, isothermal and thermal kinetic analysis methods were used to reveal out the activation energies and Arrhenius pre-exponential factors. Thermodynamic parameters of decomposition reactions were measured by using these values. Nitrofuroxane ring was concluded to be the sub-product in thermal decomposition reactions. Gaussian 09 software algorithms were used to measure the standard formation enthalpy values of the two energetic substances. Using these values, the reaction enthalpy value of the thermal decomposition reaction according to Hess's law and the result obtained was compared with the value obtained from the differential scanning calorimetry method. Experimental and theoretical results were observed to be similar. In addition to these, antimicrobial effects of the highly nitrogenous energetic substances were measured for 5 different bacteria and their antifungal effects were measured for one type of fungus. As they were highly nitrogenous, the bacteria were found to be using the nitrogen in these substances for nutritional purpose.

Real-Time Monitoring of Fluorescence in Situ Hybridization Kinetics

We present a novel method for real-time monitoring and kinetic analysis of fluorescence in situ hybridization (FISH). We implement the method using a vertical microfluidic probe containing a microstructure designed for rapid switching between probe solution and nonfluorescent imaging buffer. The FISH signal is monitored in real time during the imaging buffer wash, during which signal associated with unbound probes is removed. We provide a theoretical description of the method as well as a demonstration of its applicability using a model system of centromeric probes (Cen17). We demonstrate the applicability of the method for characterization of FISH kinetics under conditions of varying probe concentration, destabilizing agent (formamide) content, volume exclusion agent (dextran sulfate) content, and ionic strength. We show that our method can be used to investigate the effect of each of these variables and provide insight into processes affecting in situ hybridization, facilitating the design of new assays.

A Novel Method of Kinetic Analysis and Its Application to Pulverized Coal Combustion under Different Oxygen Concentrations

Currently, many efforts have been made to improve the approach to build kinetic models. Based on mathematical algorithms, a novel method (named DIM method) of kinetic analysis was introduced in detail. A formula combining differential and integral was deduced and applied to the determination of the mechanism function f(α). Subsequently, multivariable linear regression was conducted to simultaneously obtain the apparent activation energy E, pre-exponential factor A, and oxygen concentration exponent n. In the application of pulverized coal combustion under different oxygen concentrations (3%, 5%, 10%, 15%, and 21%), E, A, and n were calculated as 258,164 J/mol, 6.660 × 1017 s−1, and 3.326, respectively, and the mechanism function f(α) was determined as the Avrami-Erofeev equation. A validation was performed under a 7% oxygen concentration, which shows that the DIM method has a higher accuracy. This work can provide a reference for the study of kinetic analysis.

Thermal decomposition kinetics of basic carbonate cobalt nanosheets obtained from spent Li-ion batteries: Deconvolution of overlapping complex reactions

Abstract A new non-isothermal method of kinetic analysis was employed to investigate the thermal decomposition kinetic modeling of the basic carbonate cobalt nanosheets (n-BCoC) synthesized from spent lithium-ion batteries (LIBs). Fraser–Suzuki function was applied to deconvoluting overlapping complex processes from the overall differential thermal curves obtained under the linear heating rate conditions, followed by the kinetic analysis of the discrete processes using a new kinetic analysis method. Results showed that the decomposition of n-BCoC in air occurred through two consecutive reactions in the 136–270 °C temperature intervals. Decomposition started by hydroxide component (Co(OH)2) decomposition until to 65% and simultaneously carbonate phase decarbonation began. The process was continued by CO2 evolution and finally carbonate cobalt nanosheets have been produced. The reaction mechanism of the whole process can be kinetically characterized by two successive reactions: a phase boundary contracting reaction followed by an Avrami–Erofeev equation. Mechanistic information obtained by the kinetic study was in good agreement with FT-IR (Fourier transform infrared spectroscopy) and SEM (scanning electron microscopy) results.

A modified kinetic analysis method of cellulose pyrolysis based on TG–FTIR technique

The pyrolysis characteristics of cellulose was investigated using TGA and TG–FTIR. An modified reaction model was proposed to study cellulose pyrolysis. In this model, the active cellulose (E=137 kJ/mol) and dehydrocellulose (E=91.3 kJ/mol) were formed by parallel mechanism. The degradation of the active cellulose was followed by two competitive pathways, this is, one that formed levoglucosan (E=159.2 kJ/mol) and another that formed furan and some low molecular weight products (E=203.5 kJ/mol). The random scission model was used to describe the kinetics of cellulose pyrolysis. The same kinetic parameters were used for different linear heating rates (10–100 °C/min) and isothermal segment conditions. By successfully modeling non-isothermal and isothermal segment data, the model was proved to be credible in describing cellulose pyrolysis.

Homotopy perturbation method for kinetic analysis of thermal inactivation of jack bean urease

In this work, theoretical modeling and determination of molar concentration of the native and denatured jack bean urease (EC 3.5.1.5) are presented. A three-reaction kinetic model of thermal inactivation of urease is analyzed using homotopy perturbation method. The obtained analytical solutions are used to study the kinetics of thermal inactivation of the enzyme as applied in biotechnology. From the results, it is established that the molar concentration of native enzyme decreases as the time increases while the molar concentration of the denatured enzyme increases as the time increases. The time taken to reach the maximum value of the molar concentration of native enzyme is the same as the time taken to reach the minimum value of the molar concentration of the denature enzyme. The molar concentration of the denatured enzyme reaches the steady state value when reaction time is less than or equal to 5s. Also, the molar concentration of the denatured enzyme becomes zero when rate constant of dissociation reaction of the native form of the enzyme into a denatured form, is less than or equal to 0.01 s−1. The analytical solutions are verified with numerical solutions using Runge–Kutta with shooting method and good agreements are established between the solutions. The information given in this theoretical investigation will assist in the kinetic analysis of the experimental results over handling rate constants and molar concentrations.

Sintering activation energy MoSi2-WSi2-Si3N4 ceramic

The activation energy of sintering process was calculated based on dilatometric studies of shrinkage processes (Mo,W)Si2 + Si3N4 composite ceramic. (Mo,W)Si2 powders was obtained by solid-phase solutions of 70 wt% MoSi2 and 30 wt% WSi2 by SHS in the ISMAN RAS. The concentration rate Si3N4 was from 1 to 15 wt.%. The sintering was carried out to 1850°C in Ar atmosphere the heating rate of 5, 10, 12 and 15°C/min by the way of dilatometer tests. Based on the differential kinetic analysis method (Friedman’s method), the sintering process activation energy of (Mo,W)Si2 + Si3N4 were calculated. The two-stage sintering process and the dependence of the activation energy on the Si3N4 content was shown. Average value of 370 kJ/mol for Q was obtained.

Multistep pyrolysis behavior of core-shell type hyperbranched azide copolymer: Kinetics and reaction mechanism via experiment and simulation

As an attractive new energetic fuel, core–shell type hyperbranched azide copolymer (POG) have been investigated with regard to its pyrolysis kinetics and mechanism. Through Asymmetric Double Sigmoidal (Asym2sig) function deconvolution, POG pyrolysis profiles could be separated into two reactions well (the first and second step). Based on reasonable kinetics analysis methods, mechanism functions of the first and second step reactions were constructed to n-th order reaction model of f1(α1) = (1 − α1)1.05 and 3D diffusion model of f2(α2) = 1.95(1 − α2)2/3[1 − (1 − α2)1/3]−0.54. The gaseous products and residual morphology in different pyrolytic steps are identified by TG-FTIR-MS and SEM. Through molecular simulation, the intermediate reactions between the first and second step were successfully captured, and then the detailed pyrolysis mechanism of POG was established. In the initial stage of POG pyrolysis, thermal cracking of N3 generates nitrenes and releases N2 (fitting n-th order model). Next, the intermolecular crosslinking and intramolecular cyclization reactions of nitrenes form a new cross-linked layer on the outside of hyperbranched polyether core of POG (PEHO-c), delaying the decomposition of inner PEHO-c. Furthermore, pyrolysis of cross-linked layer and PEHO-c is gradually performed by 3D diffusion model from outside to inside, which is very suitable for 3D core-shell structure of POG.

A Complex Semi-automatic Method for Kinetic and Two-dimensional Kinematic Motion Analysis for Posture and Movement Investigation

A Complex Semi-automatic Method for Kinetic and Two-dimensional Kinematic Motion Analysis for Posture and Movement Investigation

Growth of non-toxigenic Clostridium botulinum mutant LNT01 in cooked beef: One-step kinetic analysis and comparison with C. sporogenes and C. perfringens

The objective of this study was to investigate the growth kinetics of Clostridium botulinum LNT01, a non-toxigenic mutant of C. botulinum 62A, in cooked ground beef. The spores of C. botulinum LNT01 were inoculated to ground beef and incubated anaerobically under different temperature conditions to observe growth and develop growth curves. A one-step kinetic analysis method was used to analyze the growth curves simultaneously to minimize the global residual error. The data analysis was performed using the USDA IPMP-Global Fit, with the Huang model as the primary model and the cardinal parameters model as the secondary model.The results of data analysis showed that the minimum, optimum, and maximum growth temperatures of this mutant are 11.5, 36.4, and 44.3 °C, and the estimated optimum specific growth rate is 0.633 ln CFU/g per h, or 0.275 log CFU/g per h. The maximum cell density is 7.84 log CFU/g. The models and kinetic parameters were validated using additional isothermal and dynamic growth curves. The resulting residual errors of validation followed a Laplace distribution, with about 60% of the residual errors within ±0.5 log CFU/g of experimental observations, suggesting that the models could predict the growth of C. botulinum LNT01 in ground beef with reasonable accuracy.Comparing with C. perfringens, C. botulinum LNT01 grows at much slower rates and with much longer lag times. Its growth kinetics is also very similar to C. sporogenes in ground beef. The results of computer simulation using kinetic models showed that, while prolific growth of C. perfringens may occur in ground beef during cooling, no growth of C. botulinum LNT01 or C. sporogenes would occur under the same cooling conditions. The models developed in this study may be used for prediction of the growth and risk assessments of proteolytic C. botulinum in cooked meats.

A simple and precise differential incremental isoconversional method to kinetic analysis of heterogeneous processes under arbitrary temperature programs

A simple and precise linear differential incremental isoconversional (model-free) method for kinetic analysis of heterogeneous processes using thermoanalytical data recorded at arbitrary temperature programs has been suggested. This method has been applied to simulated data corresponding to a single-step process and to a complex process consisting in two consecutive reactions, and experimental data corresponding to thermal degradation of high density polyethylene (HDPE). The obtained results are consistent with those from other isoconversional methods (advanced isoconversional method suggested by Vyazovkin, iterative method suggested by Budrugeac and differential isoconversional method suggested by Friedman).

Cartilage/chondrocyte research and osteoarthritis. New approach to osteoarthritis of knee joints by 3D kinematic analysis.

Osteoarthritis of the knee joints is a disease in which the number of patients is said to be 10 million. The pathomechanism is still unknown, and various researches has been performed. Total knee replacement is a representative treatment. It aims to restore the knee joint function as much as possible. However, the postoperative knee function and the ideal design of implant is not clarified. The latest three-dimensional kinetic analysis method is a completely different approach from the molecular biology queried in this book. It has surprisingly suggested the possibility to elucidate these problems and I would like to introduce some of the results in this chapter.

Preparation and thermoluminescent dosimetry features of high sensitivity LiF:Mg,Ce phosphor

Thermoluminescence (TL) kinetics and dosimetry features of newly produced LiF doped with Mg and Ce were investigated. Different contents of Mg (0–1 mol%) and Ce (0–2 mol%) were introduced in host material by melting method. The most TL sensitivity of the fabricated phosphor was obtained at 0.7 and 0.05 mol% concentrations of Mg and Ce impurities, respectively. The optimum pre-irradiation annealing regime of the synthesized LiF-based material was found at 350 °C for 10 min. Kinetic parameters of LiF:Mg,Ce dosimeter were obtained using different methods of computerized glow curve deconvolution (CGCD), initial rise (IR) and isothermal decay (ID). A good conformity are observed between the results obtained from different kinetic analysis methods. Other TL features such as fading, dose response and reusability were also examined.

An alternative approach to kinetic analysis of temperature-programmed reaction data.

To date, kinetic computations have been carried out efficiently for a great variety of physico-chemical processes including crystallization, melting and solid–solid transitions. However, appropriate methods for the kinetic analysis of chemical reactions, especially multi-staged reactions, are currently lacking. Here we report on an alternative way of treating temperature-programmed reaction data using the reduction of iron(iii) oxide as an example. The main principle in the suggested approach is to take into account every stage of the studied process, resulting in a system of kinetic differential equations. Kinetic parameters (activation energy and preexponential factors) are optimized for each of the stages, and cubic splines are used to approximate the conversion functions that reflect changes in reaction-specific surface area throughout the process. The applicability of the suggested method has been tested on temperature-programmed reduction (TPR) data for iron(iii) oxide samples produced from the original Fe2O3 powder by annealing it at 600, 700 and 800 °C. Results of kinetic analysis obtained at different temperature regimes demonstrate the good stability and performance of the method. Peculiarities of iron(iii) oxide reduction have been revealed, depending on the stage and heating rate. The influence of material morphology on the reduction kinetics has been assessed by comparing preexponential factors corresponding to the first reduction stage. This approach allows a comparison of the structural characteristics of the materials based on the kinetic analysis of the TPR data. Using optimized conversion functions, the initial particle size distribution has been reproduced. Theoretically found particle size distribution was found to correlate well with the experimental distribution obtained via laser diffraction.

Kinetic analysis methods applied to single motor protein trajectories.

Molecular motors convert chemical or electrical energy into mechanical displacement, either linear or rotary. Under ideal circumstances, single-molecule measurements can spatially and temporally resolve individual steps of the motor, revealing important properties of the underlying mechanochemical process. Unfortunately, steps are often hard to resolve, as they are masked by thermal noise. In such cases, details of the mechanochemistry can nonetheless be recovered by analyzing the fluctuations in the recorded traces. Here, we expand upon existing statistical analysis methods, providing two new avenues to extract the motor step size, the effective number of rate-limiting chemical states per translocation step, and the compliance of the link between the motor and the probe particle. We first demonstrate the power and limitations of these methods using simulated molecular motor trajectories, and we then apply these methods to experimental data of kinesin, the bacterial flagellar motor, and F1-ATPase.

SsDNA hybridization facilitated by T7 ssDNA binding protein (gp2.5) rapidly initiates from the strand terminus or internally followed by a slow zippering step

The hybridization of two complementary ssDNA is essential for molecular biology and biological physics. T7 ssDNA binding protein (gp2.5) can rapidly facilitate this hybridization, but the mechanism and kinetic process remain unknown. As determined by fluorescence resonance energy transfer (FRET) and rapid kinetic analysis methods, gp2.5 binding coiling ssDNA to form gp2.5-ssDNA complex is the rate-limiting step for the entire DNA hybridization process. Afterward, the hybridization initiates from either the terminus or the internal part of ssDNA at a nucleation rate of 0.45 s−1. The remaining DNA strands are hybridized in a zippering mode at a rate of 0.07 s−1, limited by the dissociation of gp2.5 from ssDNA. The gp2.5-faciliated hybridization rate constant (74 μM−1s−1) is much higher than the spontaneous hybridization rate (1.7 μM−1s−1) in the absence of gp2.5. These hybridization mechanism and kinetic process are different from those by other ssDNA binding proteins, such as T4 gp32, Escherichia coli SSB protein and recA protein. Compare with E. coli SSB, the relatively slower association of gp2.5 to ssDNA and faster dissociation of gp2.5 from ssDNA are probably the major reasons to facilitate the rapid hybridization. This study provides valuable insights into the molecular mechanism of the recombination and repair processes and proposes a basis for improvement in their associated biotechnologies.

Kinetic validation of the LiMAx test during 10 000 intravenous 13C-methacetin breath tests

The maximal liver function capacity (LiMAx) test, a novel 13C-methacetin breath test, has proven clinical validity in determining hepatic metabolic capacity. In contrast to prior 13C-methacetin breath test protocols, the LiMAx test is performed by intravenous body-weight-adjusted substrate administration. Furthermore, the DOB kinetics (delta over baseline of the time-dependent exhaled 13CO2/12CO2 ratio) are measured online at the bedside with a high time resolution in order to determine the maximum DOB. The aim of this study was to analyze the recorded DOB kinetics in a large population for further refinement of the test protocol. Two new methods of kinetic analysis are proposed in this article: the time dependency of the DOB kinetics and the time interval until half of the DOB maximum. A total of 10 100 LiMAx tests on 8483 patients performed during routine clinics at eight centers were available. The kinetic analysis revealed a specific pattern of DOB kinetics depending upon LiMAx result. In addition, potential co-factors for DOB kinetics, such as weight, height, gender and age, were analyzed, yielding a potential influence of gender and smoking behavior. Both the specific patterns and the proposed kinetic analysis have the potential to further improve the sensitivity and specificity of the test and its clinical applicability by shortening its duration.

Radioligand binding analysis of \u03b12 adrenoceptors with [11C]yohimbine in brain in vivo: Extended Inhibition Plot correction for plasma protein binding

We describe a novel method of kinetic analysis of radioligand binding to neuroreceptors in brain in vivo, here applied to noradrenaline receptors in rat brain. The method uses positron emission tomography (PET) of [11C]yohimbine binding in brain to quantify the density and affinity of α2 adrenoceptors under condition of changing radioligand binding to plasma proteins. We obtained dynamic PET recordings from brain of Spraque Dawley rats at baseline, followed by pharmacological challenge with unlabeled yohimbine (0.3 mg/kg). The challenge with unlabeled ligand failed to diminish radioligand accumulation in brain tissue, due to the blocking of radioligand binding to plasma proteins that elevated the free fractions of the radioligand in plasma. We devised a method that graphically resolved the masking of unlabeled ligand binding by the increase of radioligand free fractions in plasma. The Extended Inhibition Plot introduced here yielded an estimate of the volume of distribution of non-displaceable ligand in brain tissue that increased with the increase of the free fraction of the radioligand in plasma. The resulting binding potentials of the radioligand declined by 50–60% in the presence of unlabeled ligand. The kinetic unmasking of inhibited binding reflected in the increase of the reference volume of distribution yielded estimates of receptor saturation consistent with the binding of unlabeled ligand.

Single‐Molecule Monitoring of the Structural Switching Dynamics of Nucleic Acids through Controlling Fluorescence Blinking

AbstractSingle‐molecule fluorescence resonance energy transfer (smFRET) is a powerful tool to investigate the dynamics of biomolecular events in real time. However, it requires two fluorophores and can be applied only to dynamics that accompany large changes in distance between the molecules. Herein, we introduce a method for kinetic analysis based on control of fluorescence blinking (KACB), a general approach to investigate the dynamics of biomolecules by using a single fluorophore. By controlling the kinetics of the redox reaction the blinking kinetics or pattern can be controlled to be affected by microenvironmental changes around a fluorophore (rKACB), thereby enabling real‐time single‐molecule measurement of the structure‐changing dynamics of nucleic acids.