Method For Kinetic Analysis Research Articles

Effect of Humidity on Carbon Monoxide Desorption Kinetics

The kinetics of carbon monoxide desorption on a platinum catalyst under humidified conditions were investigated with the steady state isotropic transient kinetic analysis (SSITKA) method. The effect of the humidity level on desorption kinetics was quantified. The carbon monoxide (CO) desorption kinetic constant was calculated regardless of the gas flow rate. The kinetic constant dropped up to 58% with the increasing relative humidity. The negative effect of humidity in terms of CO poisoning for PEM fuel cells was determined.

Transesterification Kinetics of Waste Vegetable Oil in Supercritical Alcohols

The kinetic analysis method using the non-isothermal technique was proposed to determine the kinetic parameters for the transesterification reaction of waste vegetable oil (WVO) in supercritical alcohols. To investigate the transesterification of WVO, experiments have been carried out with WVO and alcohols at three molar ratios of 1:6, 1:12 and 1:18 for both supercritical ethanol (SCE) and supercritical methanol (SCM) at temperatures between 210 °C and 350 °C in a 25 mL batch reactor. The products were analyzed by gas chromatography mass spectrometry (GC-MS). To verify the effectiveness of the proposed kinetic analysis method, the experimental values were compared with the values calculated using the kinetic parameters obtained from this work. It was found that the proposed kinetic analysis method gave reliable kinetic parameters for the transesterification of WVO in supercritical alcohols. It was also seen that SCM was a better solvent than SCE for the transesterification of WVO.

A method for kinetic analysis and study of thermal quenching in thermoluminescence based on use of the area under an isothermal decay-curve

A method for kinetic analysis based on the use of the temperature-dependence of the area under an isothermal decay-curve is reported. The technique is not limited to use of areas corresponding to two measurement temperatures. The method is best suited to calculation of the activation energy in the case of first-order kinetics, and suitable limiting cases of general-order kinetics, and has been demonstrated using measurements made on quartz. In addition, the dependence of the area on the measurement temperature can be used to study thermal quenching. This has been illustrated using isothermal decay curves obtained from quartz and α-Al2O3:C. A key advantage of the method is that it can apply in cases which cannot easily be described by the Mott-Seitz model. Various results found using the method compare favourably with values obtained from conventional methods of kinetic analysis; from the literature, and are consistent with contemporary theory of stimulated luminescence.

A mass spectrometry method for quantitative and kinetic analysis of gas release from nuclear materials and its application to helium desorption from UO2 and fission gas release from irradiated fuel

A new system has been developed to determine absolute quantities of gas (mainly noble gases) released during thermal desorption in the range from 10−12 to 10−5 mol with a precision of few percent. The system is actually designed for simultaneous measurement of gaseous elements like He, Xe, Kr, thermally released from nuclear fuel samples and also allows the determination of the release kinetics as a function of time. This system, called Quantitative GAs MEasurement System (Q-GAMES), is based on the principle of collecting, purifying and spiking the sample gas in a “high-pressure” chamber, and continuous sampling of the gas for mass spectrometric analysis without sample depletion during the experiment. It is equipped with its own spike generator and with different gas purification systems. It is shown that this system fulfills the requirement to work with two existing very high-temperature gas desorption facilities for nuclear materials. This paper describes the Q-GAMES principle, the spiking system, its calibration, its operative mode, the different quantification techniques, as well as its technical data, in combination with some examples of typical application.

Reliability-based analysis and design of steel frames with different supports

Purpose – The behaviours of four indeterminate frame-support combinations namely Type I (with fixed supports), Type II (with pinned supports), Type III (with fixed-pinned supports) and Type IV (with fixed-roller supports) frames under the exposure conditions and loads as existing on site were simulated. Two categories of these combinations (I and II) were studied namely single storey-single bay and multiple storey-single bay frames, as illustrated in the case studies treated. A procedure for determining the probability of failure at different sections along the frame types, the range between the probability of failure bounds and the reliability ratings of the frame types were developed based on the kinetic method of plastic moment analysis, minimum weight design method, piecewise method of moment analysis and first order-second moment (FOSM) methods. The analysis results of the Category I frames showed that the Type I frame was most reliable (with the lowest probability of failure range of 0.3269), while the Type II frame was least reliable (with the highest probability of failure range of 0.4918). These results were consistent with those of the Category II frames. The paper aims to discuss these issues. Design/methodology/approach – Collapse mechanisms were generated for four frame-support types and the corresponding plastic moments were determined using both the kinematic plastic analyses and minimum weight design methods. The members were designed and the plastic moments were distributed at sections of constant interval along the frame length to generate corresponding envelopes. A similar process was carried out to determine the elastic moment variables due to the loads. The reliability index and the corresponding probability of failure at each frame section were determined. Then, the probabilities of failure bounds for the frames were then compared to determine the most reliable. Findings – It was observed that there existed a wide margin between the elastic and plastic moments indicating that design of steel structures at the elastic limit does not take full advantage of its strength. Hence, the design can be carried out beyond the elastic limit and within the safety margin given in equation (3). However, the safety of the entire frame is assessed on the basis of range of values between the highest and the lowest probability of failure bounds. The lower this range is (not exceeding 0.5 or 50 per cent), the more reliable the frame is. Research limitations/implications – The equations developed in this study can only be directly applied to multi storey-single bay frames. However, the reliability-based analysis and design procedure developed can be extended to other types of frames. Practical implications – A practical approach for analysing steel frames with different supports with the overall goal of producing safe and economical designs has been developed and presented in this paper. Originality/value – The procedure adopted is very original and can be backed up by existing literature. The piecewise method for analysing moments at various sections along a frame is also innovative. The whole concept can be adopted to determine the reliability of other types of frames such as multiple bay-multistorey frames with different support types.

The effect of polymer matrices on the thermal hazard properties of RDX-based PBXs by using model-free and combined kinetic analysis

In this paper, the decomposition reaction models and thermal hazard properties of 1,3,5-trinitro-1,3,5-triazinane (RDX) and its PBXs bonded by Formex P1, Semtex 1A, C4, Viton A and Fluorel polymer matrices have been investigated based on isoconversional and combined kinetic analysis methods. The established kinetic triplets are used to predict the constant decomposition rate temperature profiles, the critical radius for thermal explosion and isothermal behavior at a temperature of 82°C. It has been found that the effect of the polymer matrices on the decomposition mechanism of RDX is significant resulting in very different reaction models. The Formex P1, Semtex and C4 could make decomposition process of RDX follow a phase boundary controlled reaction mechanism, whereas the Viton A and Fluorel make its reaction model shifts to a two dimensional Avrami–Erofeev nucleation and growth model. According to isothermal simulations, the threshold cook-off time until loss of functionality at 82°C for RDX-C4 and RDX-FM is less than 500 days, while it is more than 700 days for the others. Unlike simulated isothermal curves, when considering the charge properties and heat of decomposition, RDX-FM and RDX-C4 are better than RDX-SE in storage safety at arbitrary surrounding temperature.

<b>Kinetic Analysis Method on Rehabilitation Trainings </b>

In this paper, we introduce kinetic analysis method whose motion images are acquired in rehabilitation training scenes. The rehabilitation trainings with kinetic analysis enable home trainings for improving and maintaining motility functions, which are needed by elderly humans. Our engineered approach is explained and results are shown by analyzing human motions in walking training scenes. In the future, we aim to incorporate with the training and evaluation programs which physical therapists are proposing.

Kinetics of the decomposition reaction of phosphorite concentrate

Apatite is the raw material, which is mainly used in phosphate fertilizer, and part are used in yellow phosphorus, red phosphorus, and phosphoric acid in the industry. With the decrease of the high grade phosphorite lump, the agglomeration process is necessary for the phosphorite concentrate after beneficiation process. The decomposition behavior and the phase transformation are of vital importance for the agglomeration process of phosphorite. In this study, the thermal kinetic analysis method was used to study the kinetics of the decomposition of phosphorite concentrate. The phosphorite concentrate was heated under various heating rate, and the phases in the sample heated were examined by the X-ray diffraction method. It was found that the main phases in the phosphorite are fluorapatiteCa5(PO4)3F, quartz SiO2,and dolomite CaMg(CO3)2.The endothermic DSC peak corresponding to the mass loss caused by the decomposition of dolomite covers from 600?C to 850?C. The activation energy of the decomposition of dolomite, which increases with the increase in the extent of conversion, is about 71.6~123.6kJ/mol. The mechanism equation for the decomposition of dolomite agrees with the Valensi equation and G-B equation.

Kinetics of the Chiral Disulfonimide‐Catalyzed Mukaiyama Aldol Reaction

Making progress: The kinetics of the disulfonimide-catalyzed Mukaiyama aldol reaction have been established by using the reaction progress kinetic analysis (RPKA) method. The reaction is first order with respect to catalyst and silyl ketene acetal, and has an order of 0.55 with respect to the aldehyde, which suggests the reversibility of the binding between the aldehyde and the actual catalyst.

High-throughput assay for temporal kinetic analysis of lytic coliphage activity

Plaque analysis allows the determination of phage titer and multiplicity of infection. Yet, this overnight assay provides only endpoint results, ignoring kinetic aspects. We introduce an alternative high-throughput and rapid method for kinetic analysis of lytic coliphage activity. Escherichia coli was infected with serial dilutions of MS2 coliphage, and bacterial growth was monitored using a multi-well plate reader providing within hours the equivalent data as obtained overnight. Additional information is yielded, including phage replication rate, progeny size per cycle, and viral propagation during bacterial growth. This method offers further insights into physicochemical mechanisms of lytic coliphage infection and temporal control. It also provides a virus–host interaction acumen.

Kinetic Analysis of Wind Turbine Blades

This paper using ANSYS software such as wind turbine blades and other key components of the kinetic analysis and research, the kinetic analysis method and finite element analysis software combine to validate the experimental data is reasonable. Specific contents are: wind turbine blade dynamics analysis. The wind turbine blades as slender cantilever, so you can use the ANSYS program flexible dynamic analysis modules. The module is used to calculate the alternating loads flexible body structural response, namely due to the coupling effect of making wind turbine blades load acceleration, deformation at any time are changing. Also changes with time of the blade root of force and torque, the forces and torques of the hub provides theoretical data for further analysis. In this paper, the key components that wind turbine blades for the kinetic analysis, the relevant conclusions. Wind generator system for future scientific design, blades and other key components of the failure prediction assessment provides theoretical support. Wind turbine blades rotate in the movement through the air to promote the flow of the wind energy into mechanical energy, electrical energy eventually [. Leaves the force in the system is particularly complex, by gravity, such as the formation aerodynamic pull, bend and other effects and coupling effects [. Leaves elongate resilient structure is characterized by large-scale, flexible. During operation, the fan blade damage resonance is an important reason, it is how to use the features to reduce structural failure of the fan so that the safe operation of wind power generation is one of key technologies [. Wind force generator is one of the most complex parts blades, due to its tangential short span long, flexible, and therefore prone to vibration, wind turbine blades are a variety of mechanical vibration occurs first site. Therefore, from the wind turbine operation and design considerations for wind turbine blades for stability margin analysis and linear stability analysis are important.

Stochastic Lindemann Kinetics for Unimolecular Gas-Phase Reactions

Lindemann, almost a century ago, proposed a schematic mechanism for unimolecular gas-phase reactions. Here, we present a new semiempirical method to calculate the effective rate constant in unimolecular gas-phase kinetics through a stochastic reformulation of Lindemann kinetics. Considering the rate constants for excitation and de-excitation steps in the Lindemann mechanism as temperature dependent empirical parameters, we construct and solve a chemical master equation for unimolecular gas-phase kinetics. The effective rate constant thus obtained shows excellent agreement with experimental data in the entire concentration range in which it is reported. The extrapolated values of the effective rate constant for very low and very high concentrations of inert gas molecules are in close agreement with values obtained using the Troe semiempirical method. Stochastic Lindemann kinetics, thus, provides a simple method to construct the full falloff curves and can be used as an alternative to the Troe semiempirical method of kinetic data analysis for unimolecular gas-phase reactions.

Catalytic Effect of CuCl on Pyrolysis of Five Kinds of Biomass

CuCl has been investigated with regard to its catalytic effects on pyrolysis of five biomass species, i.e., two kinds of typical forest waste (bamboo and fir wood), cellulose, xylan, and lignin by thermal analysis experiments. It shows that, with the presence of CuCl catalyst, the pyrolysis peaks shift to a lower temperature than those of a pure sample, and the maximum weight loss rate of two kinds of typical forest wastes was increased. The CuCl catalysis can also increase the amount of char residue. The activation energy and frequency factor of pyrolysis reaction for all samples were obtained by kinetic methods of analysis, the value of E and A of the mixture were higher than those of the sample (except lignin) in the absence of catalyst.

Cadmium (II)-selective electrode based on palm shell activated carbon modified with task-specific ionic liquid: kinetics and analytical applications

In this study, palm shell activated carbon modified with task-specific ionic liquid was used as a novel electrode component for the potentiometric determination of cadmium ions in water samples. The proposed potentiometric sensor has good operating characteristics, including relatively high selectivity towards the Cd (II) ion, a Nernstian response to Cd (II) ions in a working concentration range of 1.0 × 10−9–1.0 × 10−2 M, with a reasonable detection limit of 1 × 10−10 M and a slope of 30.90 ± 1.0 mV/decade. No significant changes in electrode potential were observed when the pH was varied over the range of 4–9. A direct technique based on the use of ion-selective electrode potentiometry has been developed in our laboratory for the study of reaction kinetics and kinetic methods of analysis by continuous monitoring of the rate of production or consumption of an ion. The apparent adsorption rate constant was estimated assuming pseudo-second-order kinetics. Additionally, the proposed electrode has been successfully used for the determination of the cadmium content in real samples without a significant interaction from other cationic or anionic species.

Dynamical Considerations for Kinetic Methods in Thermal Analysis

Popular kinetic methods of thermal analysis (TA) typically do not properly account for system dynamics (relaxation processes) that give rise to distributed reactivity, referred to here as “dispersive kinetics of the first kind”. In this work, new thermoanalytical relationships are put forth that allow more rigorous treatment of dispersive kinetics via the well-known Avrami-Erofe’ev (A–E) model, as it applies to both isothermal and non-isothermal (fixed heating/cooling rate) conditions. Simulated data is provided to highlight the errors that can arise from combining classical (non-dispersive, Arrhenius-based) kinetic treatments with the (dispersive) A–E mechanism. Lastly, “dispersive kinetics of the second kind” is discussed in the context of heating (cooling) a sample faster than it can thermalize. As shown by simulated data, doing so can impart dynamical effects even to conversions that would otherwise exhibit classical Arrhenius behavior.

Limitations of model-fitting methods for kinetic analysis: Polystyrene thermal degradation

In this paper, some clarifications regarding the use of model-fitting methods of kinetic analysis are provided in response to the lack of plot linearity and dispersion in the activation energy values for the thermal degradation of polystyrene found in the literature and some results proposing an nth order model as the most suitable one. In the present work, two model-fitting methods based on the differential and integral forms of the general kinetic equation are evaluated using both simulated and experimental data, showing that the differential method is recommended due to its higher discrimination power. Moreover, the intrinsic limitations of model-fitting methods are highlighted: the use of a limited set of kinetic models to fit experimental data and the ideal nature of such models. Finally, it is concluded that a chain scission model is more appropriate than first order.

Development and Validation of Kinetic Method for Quantitative Analysis of L-Ornithine-L-Aspartate

Development and Validation of Kinetic Method for Quantitative Analysis of L-Ornithine-L-Aspartate

A New Kinetics-Based Approach to Quantifying the Extent of Metastable → Stable Phase Transformation in Thermally-Grown Al2O3 Scales

A novel kinetics analysis method to quantifying the extent of metastable → stable Al2O3 phase-transformation in thermally-grown alumina scales is presented. This analysis involved assessing thermogravimetric data and the time dependence of the associated value of the instantaneous time exponent, n i . It was found that if there is θ → α transformation, the n i -value curve characteristically decreases to a minimum and then increases. The time corresponding to the minimum was defined as a transition time, t tr . It was found that after this t tr , the α phase was significantly established as a continuous layer and the overall scaling kinetics were greatly reduced. Furthermore, using a kinetics scenario for the θ and α co-formation, measured weight-gain kinetics could be well simulated from the initial co-formation stage to the steady-state single-α-phase-growing stage. Finally, it is shown that the transformation kinetics in the lateral direction can also be determined by this kinetics analysis method.

Clarifications regarding the use of model-fitting methods of kinetic analysis for determining the activation energy from a single non-isothermal curve

BackgroundThis paper provides some clarifications regarding the use of model-fitting methods of kinetic analysis for estimating the activation energy of a process, in response to some results recently published in Chemistry Central journal.FindingsThe model fitting methods of Arrhenius and Savata are used to determine the activation energy of a single simulated curve. It is shown that most kinetic models correctly fit the data, each providing a different value for the activation energy. Therefore it is not really possible to determine the correct activation energy from a single non-isothermal curve. On the other hand, when a set of curves are recorded under different heating schedules are used, the correct kinetic parameters can be clearly discerned.ConclusionsHere, it is shown that the activation energy and the kinetic model cannot be unambiguously determined from a single experimental curve recorded under non isothermal conditions. Thus, the use of a set of curves recorded under different heating schedules is mandatory if model-fitting methods are employed.

Phototrophic sulfide oxidation: environmental insights and a method for kinetic analysis

Previously, we presented data that indicated microbial sulfide oxidation would out-compete strictly chemical, abiotic sulfide oxidation reactions under nearly all conditions relevant to extant ecosystems (Luther et al., 2011). In particular, we showed how anaerobic microbial sulfide oxidation rates were several orders of magnitude higher than even metal catalyzed aerobic sulfide oxidation processes. The fact that biotic anaerobic sulfide oxidation is kinetically superior to abiotic reactions implies that nearly all anaerobic and sulfidic environments should host microbial populations that oxidize sulfide at appreciable rates. This was likely an important biogeochemical process during long stretches of euxinia in the oceans suggested by the geologic record. In particular, phototrophic sulfide oxidation allows the utilization of carbon dioxide as the electron acceptor suggesting that this process should be particularly widespread rather than relying on the presence of other chemical oxidants. Using the Chesapeake Bay as an example, we argue that phototrophic sulfide oxidation may be more important in many environments than is currently appreciated. Finally, we present methodological considerations to assist other groups that wish to study this process.