Determination of kinetic parameters for biomass combustion.
Álvarez, A; Pizarro, C; García, R; Bueno, J L; Lavín, A G
2016-09-01
The aim of this work is to provide a wide database of kinetic data for the most common biomass by thermogravimetric analysis (TGA) and differential thermogravimetry (DTG). Due to the characteristic parameters of DTG curves, a two-stage reaction model is proposed and the kinetic parameters obtained from model-based methods with energy activation values for first and second stages in the range 1.75·10(4)-1.55·10(5)J/mol and 1.62·10(4)-2.37·10(5)J/mol, respectively. However, it has been found that Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose model-free methods are not suitable to determine the kinetic parameters of biomass combustion since the assumptions of these two methods were not accomplished in the full range of the combustion process. PMID:27233095
Stochastic Chemical Kinetics with Energy Parameters
Fayolle, Guy; Pirogov, Serguei
2011-01-01
Abstact: We introduce new models of energy redistribution in stochastic chemical kinetics with several molecule types and energy parameters. The main results concern the situations when there are product form measures. Using a probabilistic interpretation of the related Boltzmann equation, we find some invariant measures explicitly and prove convergence to them.
Kinetic Parameters of Thermal Degradation of Polymers
Institute of Scientific and Technical Information of China (English)
朱新生; 程嘉祺
2003-01-01
The derivative expressions between activation energy (E) and the temperature at the maximum mass loss rate(Tmax) and between activation energy (E) and exponent (N) were deduced in the light of Arrhenius theory. It was found that the increase of activation energy results in the decrease of exponent and the increase of Tmax. The kinetic parameters were involved in the analysis of the thermal degradation of several polymers. The degradation kinetics of these polymers well complied with the prediction of the derivative expressions for the polymer degradation with single mechanism dominated.
Stochastic Chemical Kinetics with Energy Parameters
Fayolle, Guy; Malyshev, Vadim A.; Pirogov, Serguei
2004-01-01
International audience Abstact: We introduce new models of energy redistribution in stochastic chemical kinetics with several molecule types and energy parameters. The main results concern the situations when there are product form measures. Using a probabilistic interpretation of the related Boltzmann equation, we find some invariant measures explicitly and prove convergence to them. Résumé : Nous introduisons de nouveaux modèles de réseaus de cinétique chimique, avec plusieurs types d...
Data assimilation for kinetic parameters uncertainty analysis
International Nuclear Information System (INIS)
Several years ago, the OECD/NEA Nuclear Science Committee (NSC) established the Expert Group on Uncertainty Analysis in Modeling (UAM-LWR) after thorough discussions of the demands from nuclear research, industry, safety and regulation to provide the best estimate predictions of nuclear systems parameters with their confidence bounds. UAM objectives include among others, the quantification of uncertainties of neutronic calculations with respect to their value for the multi-physics analysis. Since the kinetics parameters and their uncertainties are of particular interest for these studies the deterministic approaches for analysis of uncertainties in nuclear reactor kinetic parameters (neutron generation lifetime and delayed neutron effective fraction) have been developed in frame of the UAM-LWR. The approach uses combination of generalization of perturbation theory to reactivity analysis, and the Generalized Perturbation Theory (GPT) for sensitivity computation. It has been applied to the UAM complementary fast neutron SNEAK test case that has unique set of experimental data for βeff. In this example, the covariance matrices of nuclear data have been derived from COMMARA library by Bayesian adjustment upon the set of the fast neutron integral benchmarks with the BERING code package. Then, the kinetic parameters uncertainties with their correlations have been applied to simplified model of a reactivity insertion transient where relative uncertainty of power peak was taken as figure of merit. The results demonstrate that the uncertainties due to nuclear data impact significantly the energy release in a coupled transient modeling. It was also found that such uncertainties become higher if the correlations between uncertainties of different lumped parameters are taken into account. (author)
Calculation of Kinetic Parameters of TRIGA Reactor
Energy Technology Data Exchange (ETDEWEB)
Snoj, Luka; Kavcic, Andrej; Zerovnik, Gasper; Ravnik, Matjaz [' Jozef Stefan' Institute, Jamova 39, SI-1000 Ljubljana (Slovenia)
2008-10-29
Modern Monte Carlo transport codes in combination of fast computer clusters enable very accurate calculations of the most important reactor kinetic parameters. Such are the effective delayed neutron fraction, {beta}{sub eff}, and mean neutron generation time, {lambda}. We calculated the {beta}{sub eff} and {lambda} for various realistic and hypothetical annular TRIGA Mark II cores with different types and amount of fuel. It can be observed that the effective delayed neutron fraction strongly depends on the number of fuel elements in the core or on the core size. E.g., for 12 wt. % uranium standard fuel with 20 % enrichment, {beta}{sub eff} varies from 0.0080 for a small core (43 fuel rods) to 0.0075 for a full core (90 fuel rods). It is interesting to note that calculated value of {beta}{sub eff} strongly depends also on the delayed neutron nuclear data set used in calculations. The prompt neutron life-time mainly depends on the amount (due to either content or enrichment) of {sup 235}U in the fuel as it is approximately inversely proportional to the average absorption cross-section of the fuel. E.g., it varies from 28 {mu}s for 30 wt. % uranium content fuelled core to 48 {mu}s for 8.5 wt. % uranium content LEU fuelled core. The results are especially important for pulse mode operation and analysis of the pulses. (authors)
Estimation of Kinetic Parameters in an Automotive SCR Catalyst Model
DEFF Research Database (Denmark)
Åberg, Andreas; Widd, Anders; Abildskov, Jens;
2016-01-01
A challenge during the development of models for simulation of the automotive Selective Catalytic Reduction catalyst is the parameter estimation of the kinetic parameters, which can be time consuming and problematic. The parameter estimation is often carried out on small-scale reactor tests, or p...
Kinetic and Thermodynamic Parameters for Uncatalyzed Esterification of Carboxylic Acid
Directory of Open Access Journals (Sweden)
Kehinde S. Bankole
2014-06-01
Full Text Available A fundamental study on uncatalyzed esterification of various biomass-derived aliphatic carboxylic acids with stoichiometric amount of ethanol has been investigated in an isothermal batch reactor, with the objective to convert carboxylic acids to corresponding ethyl esters and to determine both the kinetic and thermodynamic parameters. The effects of temperature on the conversion of carboxylic acid, kinetic and thermodynamic parameters have been investigated. Temperature was found to have significant effect on the rate of reaction and conversion of carboxylic acid. A simple second order reversible kinetic model was developed to determine the kinetic and thermodynamic parameters. The thermodynamic and kinetic parameters varied for uncatalyzed esterification reaction of both short-chain and long-chain carboxylic acids considered. The predicted data from the kinetic model were correlated with experimental data and the two sets of data agreed reasonably well for the uncatalyzed esterification systems. It was observed that the Van’t Hoff plot for uncatalyzed esterification of linoleic acid was non-linear curve, whereas for the Arrhenius and Eyring plots, they were linear. Additional experiments to assess the catalytic and corrosion effects of several metallic substances revealed Inconel 625 alloy, nickel wire and stainless steel materials were susceptible to corrosion problem with uncatalyzed esterification reaction at elevated reaction temperatures. However, tantalum and grade-5 titanium materials were corrosion resistance metals, suitable for similar reaction conditions and this can encourage the design of a flow reactor system. Although, uncatalyzed esterification of carboxylic acids at elevated reaction temperature is still at laboratory scale. It is our hope that the estimated kinetic and thermodynamic parameters would be the guiding tools for reactor scale-up, thus providing a new perspective into the conversion of biomass-derived carboxylic
Directory of Open Access Journals (Sweden)
Nader Frikha
2011-01-01
Full Text Available Problem statement: The determination of reaction kinetics is of major importance, as for industrial reactors optimization as for environmental reasons or energy limitations. Although calorimetry is often used for the determination of thermodynamic parameters alone, the question that arises is: how can we apply the Differential Scanning Calorimetry for the determination of kinetic parameters. The objective of this study consists to proposing an original methodology for the simultaneous determination of thermodynamic and kinetic parameters, using a laboratory scale Differential Scanning Calorimeter (DSC. The method is applied to the dichromate-catalysed hydrogen peroxide decomposition. Approach: The methodology is based on operating of experiments carried out with a Differential Scanning Calorimeter. The interest of this approach proposed is that it requires very small quantities of reactants (about a few grams to be implemented. The difficulty lies in the fact that, using such microcalorimeters, the reactants temperature cannot directly be measured and a particular calibration procedure has thus to be developed, to determine the media temperature in an indirect way. The proposed methodology for determination of kinetics parameters is based on resolution of the coupled heat and mass balances. Results: A complete kinetic law is proposed. The Arrhenius parameters are determined as frequency factor k0 = 1.39×109 s−1 and activation energy E = 54.9 kJ mol−1. The measured enthalpy of reaction is ΔrH=−94 kJ mol−1. Conclusion: The comparison of the results obtained by such an original methodology with those obtained using a conventional laboratory scale reactor calorimetry, for the kinetics determination of, shows that this new approach is very relevant.
Determining crystal growth kinetic parameters using optical fibre sensors
Boerkamp, M.; Lamb, D. W.; Lye, P. G.
2012-12-01
The capability of an 'intrinsic exposed core optical fibre sensor' (IECOFS) as a monitoring device of scale formation has been evaluated. The IECOFS has been used to measure kinetics parameters of calcium carbonate heterogeneous crystal growth such as the activation energy, the crystal growth rate and the induction time. The IECOFS was able to evaluate crystal growth inhibition through the use of chemical inhibitors.
Kinetic parameters and TL mechanism in cadmium tetra borate phosphor
Energy Technology Data Exchange (ETDEWEB)
Annalakshmi, O. [Radiological Safety Division, Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Jose, M.T., E-mail: mtj@igcar.gov.in [Radiological Safety Division, Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Sridevi, J. [Central Leather Research Institute, Council of Scientific and Industrial Research, Chennai 600 020, Tamilnadhu (India); Venkatraman, B. [Radiological Safety Division, Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Amarendra, G. [Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Mandal, A.B. [Central Leather Research Institute, Council of Scientific and Industrial Research, Chennai 600 020, Tamilnadhu (India)
2014-03-15
Polycrystalline powder samples of cadmium tetra borate were synthesized by a simple solid state sintering technique and gamma irradiated sample showed a simple Thermoluminescence (TL) glow peak around 460 K. The TL kinetic parameters of gamma irradiated phosphor were determined by initial rise (IR), isothermal decay (ID), peak shape (PS), variable heating rate (VHR) and glow curve de-convolution method. The kinetic parameters such as activation energy (E), frequency factor (s) and order of kinetics (b) were calculated by IR, ID, PS and VHR methods are in the order of ∼1.05 eV, 10{sup 9}–10{sup 12} s{sup −1} and 1.58, respectively. From the results of TL and PL emission studies carried out on the phosphor revealed that the defect centers related to TL is different from that for PL. EPR measurements were carried out to identify the defect centers formed in cadmium tetra borate phosphor on gamma irradiation. Based on EPR studies the mechanism for TL process in cadmium tetra borate is proposed in this paper -- Highlights: • Polycrystalline powder samples of undoped cadmium tetra borate synthesized. • Cadmium tetra borate phosphor exhibits a dosimetric peak at 458 K. • Kinetic parameters of the trap responsible for TL evaluated. • TL mechanism is proposed from TL to EPR correlation studies.
Thermoluminescent kinetics parameters of inorganic dust from camomile
Energy Technology Data Exchange (ETDEWEB)
Furetta, C.; Cruz Z, E. [ICN-UNAM, A.P. 70-543, 04510 Mexico D.F. (Mexico); Favalli, A. [European Commission, Joint Research Centre, Institute for the Protection and Security of Citizen, TP800, Via E. Fermi 21020, Ispra VA (Italy); Gomez R, J.M. [CIEMAT, Av. Complutense 22, 28040 Madrid (Spain); Kitis, G. [Nuclear Physics Laboratory, University of Thessaloniky (Greece)
2006-07-01
The poly mineral dust extracted from camomile herb was exposed to gamma radiation. The glow curves from these poly minerals show a large, single TL peak, centred at about 440 K. Because the large structure of the glow curves, it seems that the TL signal could be produced by a trap distribution instead of a single level. The thermoluminescent kinetic parameters of the glow curves have been accurately analysed using the Computerized Glow Curve Deconvolution (CGCD) applied at different steps during fading experiment at room temperature (RT). Deconvolution has been performed using a continuous distribution of trapping levels, uniformly distributed, including one additional peak in the high temperature region. This peak has been modelled with second-order kinetics. (Author)
Reactivity and kinetic parameters determination in a multiplicative non-stationary system
International Nuclear Information System (INIS)
A revision of several methods used for solving kinetic equations of a neutronic system is considered. Firstly, kinetic equations in general form are analized, before to revise more important aproximations: point-kinetic method; adiabatic; cuasistatic; eigenvalue equations; nodal, modal and systhesis methods; and variational principles for obtaining kinetic equations. Perturbation theory is used to obtain these parameters, with differents eigenvalue equations representatives of the parameter to be calculated. Also, experimental methods have been included in this work, because of importance the parameters can be measured, and related with those obtained by calculations. Finally, adjoint kinetic equations are resolved to obtain the importance function used in weighted reactivity and kinetic parameters determinations. (author)
ENZYPLOTW: A USEFUL TOOL TO CALCULATE ENZYME KINETIC PARAMETERS
Directory of Open Access Journals (Sweden)
F.A Leone
2006-07-01
Full Text Available Assays of enzyme activity are among the most frequently employed procedures in biochemistry. They are used to estimate the amount of a given enzyme in a cell or tissue, to quantify kinetic parameters or to investigate a catalytic mechanism. The purpose of enzyme kinetics obtained under steady-state conditions is to estimate KM and VM values by fitting initial rate (v and substrate concentration (S values to the Michaelis-Menten equation, permitting a convenient graphical representation and an accurate estimation of KM and VM. However, there is no ideal assay for any particular enzyme and, since the assay of enzyme activity is essentially a kinetic measurement, various pitfalls await the unwary investigator. Despite difficulties consequent to intrinsic enzyme properties, kinetic parameters can be estimated accurately when steady-state conditions (<10% variation in substrate concentration during activity assay and initial rate measurements (catalytic enzyme concentration are guaranteed.EnzyplotW is an application developed for use on any Intel-based computer running Windows 98 or later, and uses a non-linear regression method to fit steady-state kinetic data for Michaelian enzymes. EnzyplotW can be employed not only for educational purposes but also in routine laboratory work, and includes three important features: teaching students how to obtain and recognize sound data for the best estimation of kinetic parameter values; aid the investigator at the bench in gauging the limitations of the various equivalent plots of the Michaelis-Menten equation used to estimate KM and VM; and allow the student to manipulate the mathematical formula of the corresponding plot to comprehend the qualitative and quantitative issues that govern the relationship between substrate
Kinetic parameters of silicon uptake by rice cultivars
Directory of Open Access Journals (Sweden)
Priscila Oliveira Martins
2012-02-01
Full Text Available Silicon is considered an important chemical element for rice, because it can improve tolerance to biotic and abiotic stress. However, in many situations no positive effect of silicon was observed, probably due to genetic factors. The objective of this research was to monitor Si uptake kinetics and identify responses of rice cultivars in terms of Si uptake capacity and use. The experiment was carried out in a greenhouse of the São Paulo State University (UNESP, Brazil. The experiment was arranged in a completely randomized, factorial design with three replications. that consisted of two rice cultivars and two Si levels. Kinetic parameters (Vmax, Km, and Cmin, root morphology variables, dry matter yield, Si accumulation and levels in shoots and roots, uptake efficiency, utilization efficiency, and root/shoot ratio were evaluated. Higher Si concentrations in the nutrient solution did not increase rice dry matter. The development of the low-affinity silicon uptake system of the rice cultivar 'Caiapó' was better than of 'Maravilha'.
Khonde, Ruta Dhanram; Chaurasia, Ashish Subhash
2015-04-01
The present study provides the kinetic model to describe the pyrolysis of sawdust, rice-husk and sugarcane bagasse as biomass. The kinetic scheme used for modelling of primary pyrolysis consisting of the two parallel reactions giving gaseous volatiles and solid char. Estimation of kinetic parameters for pyrolysis process has been carried out for temperature range of 773-1,173 K. As there are serious issues regarding non-convergence of some of the methods or solutions converging to local-optima, the proposed kinetic model is optimized to predict the best values of kinetic parameters for the system using three approaches—Two-dimensional surface fitting non-linear regression technique, MS-Excel Solver Tool and COMSOL software. The model predictions are in agreement with experimental data over a wide range of pyrolysis conditions. The estimated value of kinetic parameters are compared with earlier researchers and found to be matching well.
Correlating thermodynamic and kinetic parameters with amorphous stability
DEFF Research Database (Denmark)
Graeser, Kirsten A; Patterson, James E; Zeitler, J Axel;
2009-01-01
stability of amorphous drugs for a larger sample set (12 drugs). The relaxation time, fragility index and configurational thermodynamic properties (enthalpy, entropy and Gibbs free energy) were calculated and correlated to the actual stability behaviour, obtained for 12 drugs. Below the glass transition...... temperature the relaxation time and fragility showed no correlation with the observed physical stability. All drugs were calculated to be 'fragile'. However, variation in the fragility index existed, with values spanning from 8.9 to 21.3, manifesting themselves as differences in the temperature dependencies......Poor physical stability is one of the single most important factors limiting the widespread use of the amorphous state in pharmaceutics. The purpose of this study is to move away from the case study approach by investigating thermodynamic and kinetic parameters as potential predictors of physical...
The kinetic parameters of carbonaceous materials activated with potassium hydroxide
Energy Technology Data Exchange (ETDEWEB)
Yong, Z.; Han, B.X.
2000-07-01
On the basis of microspore formation in carbonaceous materials, the activation energy for the potassium hydroxide activation of Chinese petroleum coke and coal has been deduced theoretically as dB(O)/dt = A exp(-E(a)) is an element of/RT), where is an element of is the formation energy for the metastable solid formed at the activation temperature. The kinetic parameters (frequency factor, A, and apparent activation energy, E(a) were calculated from this equation as being 5.319 mg/(g min), 36.51 kJ/mol and 6.64 mg/(g min), 49.46 kJ/mol, respectively, for the two carbonaceous materials studied.
Directory of Open Access Journals (Sweden)
Baker Syed
2011-01-01
Full Text Available Abstract In systems biology, experimentally measured parameters are not always available, necessitating the use of computationally based parameter estimation. In order to rely on estimated parameters, it is critical to first determine which parameters can be estimated for a given model and measurement set. This is done with parameter identifiability analysis. A kinetic model of the sucrose accumulation in the sugar cane culm tissue developed by Rohwer et al. was taken as a test case model. What differentiates this approach is the integration of an orthogonal-based local identifiability method into the unscented Kalman filter (UKF, rather than using the more common observability-based method which has inherent limitations. It also introduces a variable step size based on the system uncertainty of the UKF during the sensitivity calculation. This method identified 10 out of 12 parameters as identifiable. These ten parameters were estimated using the UKF, which was run 97 times. Throughout the repetitions the UKF proved to be more consistent than the estimation algorithms used for comparison.
Generation of a library of two-group diffusion and kinetics parameters for DYN3D
International Nuclear Information System (INIS)
A library of two-group diffusion and kinetics parameters has been generated for the neutron kinetics code DYN3D for analysis of reactivity initiated accidents for the WWER-440 reactors, based on the MAGRU approximation methodology for the diffusion and kinetics parameters. The accuracy of this methodology has been tested and the conclusion is that it is not adequate. A new approximation methodology, based on interpolation for the most widely varying parameters, i.e. the moderator temperature and density, and on approximation for all other independent parameters, is presented. The methodology of calculation of the kinetics parameters using primary data from ENDF-B/VI is described in detail (Authors)
Electrochemical evaluation of glutathione S-transferase kinetic parameters.
Enache, Teodor Adrian; Oliveira-Brett, Ana Maria
2015-02-01
Glutathione S-transferases (GSTs), are a family of enzymes belonging to the phase II metabolism that catalyse the formation of thioether conjugates between the endogenous tripeptide glutathione and xenobiotic compounds. The voltammetric behaviour of glutathione (GSH), 1-chloro-2,4-dinitrobenzene (CDNB) and glutathione S-transferase (GST), as well as the catalytic conjugation reaction of GSH to CDNB by GST was investigated at room temperature, T=298.15K (25°C), at pH6.5, for low concentration of substrates and enzyme, using differential pulse (DP) voltammetry at a glassy carbon electrode. Only GSH can be oxidized; a sensitivity of 0.14nA/μM and a LOD of 6.4μM were obtained. The GST kinetic parameter electrochemical evaluation, in relation to its substrates, GSH and CDNB, using reciprocal Michaelis-Menten and Lineweaver-Burk double reciprocal plots, was determined. A value of KM~100μM was obtained for either GSH or CDNB, and Vmax varied between 40 and 60μmol/min per mg of GST.
Calculating the parameters of reactor kinetics with increased accuracy
International Nuclear Information System (INIS)
The procedure of reactor kinetics equation solution with high accuracy and the program realizing this procedure are described. The method is based on approximation of reactor neutron flux density and concentration of nuclei-precursors of delayed neutrons on the final time interval by the polynomial of the 3d type. This approach permits to by-pass multiple limitations of different numerical methods applied before to solve the same problem (restriction in value of a time step due to possibility of stability loss, in condition of completeness of a set of point kinetics equations, in value of the induced error on every time step). Calculations of reactor kinetics for different variants of reactivity representation are carried out
Comparison of Seven Kinetic Equations for K Release and Application of Kinetic Parameters
Institute of Scientific and Technical Information of China (English)
L(U) Xiao-Nan; XU Jian-Ming; MA Wan-Zhu; LU Yun-Fu
2007-01-01
Corn field experiments with two treatments, NP and NPK, where N in the form of urea, P in the form of calcium phosphate, and K in the form of KC1 were applied at rates of 187.5, 33.3, and 125 kg ha-1, respectively, on soils derived from Quaternary red clay were conducted in the hilly red soil region of Zhejiang Province, China. Plant grains and stalks were collected for determination of K content. Seven equations were used to describe the kinetics of K release from surface soil samples taken before the corn experiments under electric field strengths of 44.4 and 88.8 V cm-1 by means of electro-ultrafiltration (EUF) and to determine if their parameters had a practical application. The second-order and Elovich equations excellently described K release; the first-order, power function, and parabolic diffusion equations also described K release well; but the zero-order and exponential equations were not so good at reflecting K release. Five reference standards from the field experiments, including relative grain yield (yield of the NP treatment/yield of the NPK treatment), relative dry matter yield (dry matter of the NP treatment/dry matter of the NPK treatment), quantity of K uptake in the NP treatment (no K application), soil exchangeable K, and soil HNO3-soluble K, were used to test the effectiveness of equation parameters obtained from the slope or intercept of these equations. Correlations of the ymax (the maximum desorbable quantity of K) in the second-order equation and the constant b in the first-order and E lovich equations to all five reference standards were highly significant (P ≤ 0.01). The constant a in the power function equation was highly significant (P ≤ 0.01) for four of the five reference standards with the fifth being significant (P ≤ 0.05). The constant b in the parabolic equation was also significantly correlated (P ≤ 0.05) to the relative grain yield and soil HNO3-solublc K. These suggested that all of these parameters could be used to
Mechanism and Kinetic Parameters of Thermal Decomposition of Cobalt Dichloride Hexahydrate
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
The thermal decomposition of the cobalt dichloride hexahydrate and its kinetics were studied by TG and DTG technique under the non-isothermal condition with nitrogen atnosphere.The non-isothermal kinetic data and kinetic parameters were evaluated by means of integral and differential methods.The most probable mechanism functions of the thermal decomposition reaction for the first stage are:f(α)=(1-α)2 and g(α)=(1-α)-1-1.
Parameter Estimates in Differential Equation Models for Chemical Kinetics
Winkel, Brian
2011-01-01
We discuss the need for devoting time in differential equations courses to modelling and the completion of the modelling process with efforts to estimate the parameters in the models using data. We estimate the parameters present in several differential equation models of chemical reactions of order n, where n = 0, 1, 2, and apply more general…
International Nuclear Information System (INIS)
Kinetic parameters of transformation of americium and plutonium physicochemical forms have been estimated and the prognosis of fixing and remobilization of these nuclides in podsol soils have been made on that basis in the work. (authors)
Institute of Scientific and Technical Information of China (English)
刘平乐; 邹丽珊; 罗和安; 王良芥; 郑金华
2004-01-01
A modified genetic algorithm of multiple selection strategies, crossover strategies and adaptive operator is constructed, and it is used to estimate the kinetic parameters in autocatalytic oxidation of cyclohexane. The influences of selection strategy, crossover strategy and mutation strategy on algorithm performance are discussed. This algorithm with a specially designed adaptive operator avoids the problem of local optimum usually associated with using standard genetic algorithm and simplex method. The kinetic parameters obtained from the modified genetic algorithm are credible and the calculation results using these parameters agree well with experimental data. Furthermore, a new kinetic model of cyclohexane autocatalytic oxidation is established and the kinetic parameters are estimated by using the modified genetic algorithm.
Parameter Optimization of Nitriding Process Using Chemical Kinetics
Özdemir, İ. Bedii; Akar, Firat; Lippmann, Nils
2016-09-01
Using the dynamics of chemical kinetics, an investigation to search for an optimum condition for a gas nitriding process is performed over the solution space spanned by the initial temperature and gas composition of the furnace. For a two-component furnace atmosphere, the results are presented in temporal variations of gas concentrations and the nitrogen coverage on the surface. It seems that the exploitation of the nitriding kinetics can provide important feedback for setting the model-based control algorithms. The present work shows that when the nitrogen gas concentration is not allowed to exceed 6 pct, the Nad coverage can attain maximum values as high as 0.97. The time evolution of the Nad coverage also reveals that, as long as the temperature is above the value where nitrogen poisoning of the surface due to the low-temperature adsorption of excess nitrogen occurs, the initial ammonia content in the furnace atmosphere is much more important in the nitriding process than is the initial temperature.
k-Cone analysis: determining all candidate values for kinetic parameters on a network scale.
Famili, Iman; Mahadevan, Radhakrishnan; Palsson, Bernhard O
2005-03-01
The absence of comprehensive measured kinetic values and the observed inconsistency in the available in vitro kinetic data has hindered the formulation of network-scale kinetic models of biochemical reaction networks. To meet this challenge we present an approach to construct a convex space, termed the k-cone, which contains all the allowable numerical values of the kinetic constants in large-scale biochemical networks. The definition of the k-cone relies on the incorporation of in vivo concentration data and a simplified approach to represent enzyme kinetics within an established constraint-based modeling approach. The k-cone approach was implemented to define the allowable combination of numerical values for a full kinetic model of human red blood cell metabolism and to study its correlated kinetic parameters. The k-cone approach can be used to determine consistency between in vitro measured kinetic values and in vivo concentration and flux measurements when used in a network-scale kinetic model. k-Cone analysis was successful in determining whether in vitro measured kinetic values used in the reconstruction of a kinetic-based model of Saccharomyces cerevisiae central metabolism could reproduce in vivo measurements. Further, the k-cone can be used to determine which numerical values of in vitro measured parameters are required to be changed in a kinetic model if in vivo measured values are not reproduced. k-Cone analysis could identify what minimum number of in vitro determined kinetic parameters needed to be adjusted in the S. cerevisiae model to be consistent with the in vivo data. Applying the k-cone analysis a priori to kinetic model development may reduce the time and effort involved in model building and parameter adjustment. With the recent developments in high-throughput profiling of metabolite concentrations at a whole-cell scale and advances in metabolomics technologies, the k-cone approach presented here may hold the promise for kinetic
Brito, Paula; Antunes, Fernando
2014-10-01
The lack of kinetic data concerning the biological effects of reactive oxygen species is slowing down the development of the field of redox signaling. Herein, we deduced and applied equations to estimate kinetic parameters from typical redox signaling experiments. H2O2-sensing mediated by the oxidation of a protein target and the switch-off of this sensor, by being converted back to its reduced form, are the two processes for which kinetic parameters are determined. The experimental data required to apply the equations deduced is the fraction of the H2O2 sensor protein in the reduced or in the oxidized state measured in intact cells or living tissues after exposure to either endogenous or added H2O2. Either non-linear fittings that do not need transformation of the experimental data or linearized plots in which deviations from the equations are easily observed can be used. The equations were shown to be valid by fitting to them virtual time courses simulated with a kinetic model. The good agreement between the kinetic parameters estimated in these fittings and those used to simulate the virtual time courses supported the accuracy of the kinetic equations deduced. Finally, equations were successfully tested with real data taken from published experiments that describe redox signaling mediated by the oxidation of two protein tyrosine phosphatases, PTP1B and SHP-2, which are two of the few H2O2-sensing proteins with known kinetic parameters. Whereas for PTP1B estimated kinetic parameters fitted in general the present knowledge, for SHP-2 results obtained suggest that reactivity towards H2O2 as well as the rate of SHP-2 regeneration back to its reduced form are higher than previously thought. In conclusion, valuable quantitative kinetic data can be estimated from typical redox signaling experiments, thus improving our understanding about the complex processes that underline the interplay between oxidative stress and redox signaling responses.
Preparation of bilinear weighted kinetics parameters for WWER-440 reactivity measurement
International Nuclear Information System (INIS)
A practical procedure for the computation of bilinear weighted core kinetics parameters of WWER-440 reactors, intended to be used in experimental reactivity determination by the inverse kinetics method is described. The results from its application are benchmarked against those obtained on the basis of a many-group fine-mesh two dimensional solution of the core boundary problem The sensitivity of core kinetics parameters and of the resultant experimental reactivity values to the variation of primary delayed neutron data is evaluated. The AER kinetics parameters benchmark is solved and the results are commented. Statistical data about calculated and measured reactivity effects during the start-up tests of units 1-4 of the Kozloduy NPP presented and discussed (Authors)
Investigation of transfer parameters from the radiochromium on erythrocyte kinetic
International Nuclear Information System (INIS)
This study analyzes and interprets results of destruction and survival data from 51Cr labeled red cells to the more common and realistic situations for diagnostic applications in clinical and nuclear hematology. The destructive process and the deviation of the cell system from the equilibrium state can be conveniently studied in terms of the disappearance rate of labeled red blood cells, using some transfer parameters. The investigation was concentrated on selection and study of a mathematical model to describe significantly the elimination process and to improve and simplify the computational analysis of data in chromium erythrokinetics from patients and normal individuals for control. (author)
Kumar, B Shiva; Venkateswarlu, Ch
2014-08-01
The complex nature of biological reactions in biofilm reactors often poses difficulties in analyzing such reactors experimentally. Mathematical models could be very useful for their design and analysis. However, application of biofilm reactor models to practical problems proves somewhat ineffective due to the lack of knowledge of accurate kinetic models and uncertainty in model parameters. In this work, we propose an inverse modeling approach based on tabu search (TS) to estimate the parameters of kinetic and film thickness models. TS is used to estimate these parameters as a consequence of the validation of the mathematical models of the process with the aid of measured data obtained from an experimental fixed-bed anaerobic biofilm reactor involving the treatment of pharmaceutical industry wastewater. The results evaluated for different modeling configurations of varying degrees of complexity illustrate the effectiveness of TS for accurate estimation of kinetic and film thickness model parameters of the biofilm process. The results show that the two-dimensional mathematical model with Edward kinetics (with its optimum parameters as mu(max)rho(s)/Y = 24.57, Ks = 1.352 and Ki = 102.36) and three-parameter film thickness expression (with its estimated parameters as a = 0.289 x 10(-5), b = 1.55 x 10(-4) and c = 15.2 x 10(-6)) better describes the biofilm reactor treating the industry wastewater.
Correlations of kinetic parameters in biomass pyrolysis with solid residue yield and lignin content
Hashimoto, Kenji; Hasegawa, Isao; Hayashi, Junichi; Mae, Kazuhiro
2011-01-01
A kinetic analysis of the pyrolysis of various types of biomass (trunk, bark, leaf, shell, herbage, food dregs, and polysaccharide) as well as synthetic biomass consisting of cellulose and lignin was performed using thermogravimetric analysis data. The reaction rates of biomass pyrolysis were found to be expressed simply by a single nth-order reaction model. The kinetic parameters (frequency factor k0, activation energy E, and reaction order n) were estimated first by differentiating the ther...
Reaction Kinetic Parameters and Surface Thermodynamic Properties of Cu2O Nanocubes
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Xingxing Li
2015-07-01
Full Text Available Cuprous oxide (Cu2O nanocubes were synthesized by reducing Cu(OH2 in the presence of sodium citrate at room temperature. The samples were characterized in detail by field-emission scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray powder diffraction, and N2 absorption (BET specific surface area. The equations for acquiring reaction kinetic parameters and surface thermodynamic properties of Cu2O nanocubes were deduced by establishment of the relations between thermodynamic functions of Cu2O nanocubes and these of the bulk Cu2O. Combined with thermochemical cycle, transition state theory, basic theory of chemical thermodynamics, and in situ microcalorimetry, reaction kinetic parameters, specific surface enthalpy, specific surface Gibbs free energy, and specific surface entropy of Cu2O nanocubes were successfully determined. We also introduced a universal route for gaining reaction kinetic parameters and surface thermodynamic properties of nanomaterials.
Fuzzy Stochastic Petri Nets for Modeling Biological Systems with Uncertain Kinetic Parameters.
Liu, Fei; Heiner, Monika; Yang, Ming
2016-01-01
Stochastic Petri nets (SPNs) have been widely used to model randomness which is an inherent feature of biological systems. However, for many biological systems, some kinetic parameters may be uncertain due to incomplete, vague or missing kinetic data (often called fuzzy uncertainty), or naturally vary, e.g., between different individuals, experimental conditions, etc. (often called variability), which has prevented a wider application of SPNs that require accurate parameters. Considering the strength of fuzzy sets to deal with uncertain information, we apply a specific type of stochastic Petri nets, fuzzy stochastic Petri nets (FSPNs), to model and analyze biological systems with uncertain kinetic parameters. FSPNs combine SPNs and fuzzy sets, thereby taking into account both randomness and fuzziness of biological systems. For a biological system, SPNs model the randomness, while fuzzy sets model kinetic parameters with fuzzy uncertainty or variability by associating each parameter with a fuzzy number instead of a crisp real value. We introduce a simulation-based analysis method for FSPNs to explore the uncertainties of outputs resulting from the uncertainties associated with input parameters, which works equally well for bounded and unbounded models. We illustrate our approach using a yeast polarization model having an infinite state space, which shows the appropriateness of FSPNs in combination with simulation-based analysis for modeling and analyzing biological systems with uncertain information. PMID:26910830
EQUILIBRIUM AND KINETIC PARAMETERS FOR THE SEDIMENTATION OF TARTARIC SALTS IN YOUNG WINES
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Ecaterina Covaci
2015-06-01
Full Text Available In young wines potassium hydrogen tartrate is always present in supersaturating concentration and crystallizes spontaneously. The aim of this study is to obtain kinetic parameters, which explain the stability of young wines during the stabilization treatments. The kinetic and equilibrium parameters were evaluated and discussed. The heating factor has a decisive influence on the reaction rate of potassium hydrogen tartrate precipitation in young wines. An increase of temperature leads to a decrease in efficiency of stabilization process and to an enhancement of the activation energy of the system. According to the obtained experimental results, the optimal regime for production and stabilization of young wines has been established.
Kinetics parameters of a slurry remediation process in rotating drum bioreactors
Energy Technology Data Exchange (ETDEWEB)
Esquivel-Rios, I.; Rodriguez-Meza, M. A.; Barrera-Cortes, J.
2009-07-01
The knowledge of biotransformation pollution dynamics in any systems is important for design and optimization purposes of biochemical processes involved. this is focus to the determination of kinetics parameters such as the maximum specific growth rate ({mu}MAX), saturation constant (Ks), biomass yield (YX/S; X: biomass, S: substrate) and oxygen consumption (YO{sub 2}/S; O{sub 2}: oxygen). Several approximations, based on Monod equation, have been developed for estimating kinetics parameters in terms of concentration and type of substrate, bioprocess type and microflora available. (Author)
Institute of Scientific and Technical Information of China (English)
Haozhong HUANG; Wanhua SU
2008-01-01
The micro-genetic algorithm (μGA) as a highly effective optimization method, is applied to calibrate to a newly developed reduced chemical kinetic model (40 species and 62 reactions) for the homogeneous charge compression ignition (HCCI) combustion of n-heptane to improve its autoignition predictions for different engine operating conditions. The seven kinetic parameters of the calibrated model are determined using a combination of the Micro-Genetic Algorithm and the SENKIN program of CHEMKIN chemical kinetics software package. Simulation results show that the autoignition predictions of the calibrated model agree better with those of the detailed chemical kinetic model (544 species and 2 446 reactions) than the original model over the range of equivalence ratios from 0.1-1.3 and temperature from 300-3 000 K. The results of this study have demonstrated that the μGA is an effective tool to facilitate the calibration of a large number of kinetic parameters in a reduced kinetic model.
Evaluation of Anaerobic Biofilm Reactor Kinetic Parameters Using Ant Colony Optimization.
Satya, Eswari Jujjavarapu; Venkateswarlu, Chimmiri
2013-09-01
Fixed bed reactors with naturally attached biofilms are increasingly used for anaerobic treatment of industry wastewaters due their effective treatment performance. The complex nature of biological reactions in biofilm processes often poses difficulty in analyzing them experimentally, and mathematical models could be very useful for their design and analysis. However, effective application of biofilm reactor models to practical problems suffers due to the lack of knowledge of accurate kinetic models and uncertainty in model parameters. In this work, an inverse modeling approach based on ant colony optimization is proposed and applied to estimate the kinetic and film thickness model parameters of wastewater treatment process in an anaerobic fixed bed biofilm reactor. Experimental data of pharmaceutical industry wastewater treatment process are used to determine the model parameters as a consequence of the solution of the rigorous mathematical models of the process. Results were evaluated for different modeling configurations derived from the combination of mathematical models, kinetic expressions, and optimization algorithms. Analysis of results showed that the two-dimensional mathematical model with Haldane kinetics better represents the pharmaceutical wastewater treatment in the biofilm reactor. The mathematical and kinetic modeling of this work forms a useful basis for the design and optimization of industry wastewater treating biofilm reactors. PMID:24065871
Gomez, M Victoria; Rodriguez, Antonio M; de la Hoz, Antonio; Jimenez-Marquez, Francisco; Fratila, Raluca M; Barneveld, Peter A; Velders, Aldrik H
2015-10-20
Conventional methods to determine the kinetic parameters for a certain reaction require multiple, separate isothermal experiments, resulting in time- and material-consuming processes. Here, an approach to determine the kinetic information within a single nonisothermal on-flow experiment is presented, consuming less than 10 μmol of reagents and having a total measuring time of typically 10 min. This approach makes use of a microfluidic NMR chip hyphenated to a continuous-flow microreactor and is based on the capabilities of the NMR chip to analyze subnanomole quantities of material in the 25 nL detection volume. Importantly, useful data are acquired from the microreactor platform in specific isothermal and nonisothermal frames. A model fitting the experimental data enables rapid determination of kinetic parameters, as demonstrated for a library of isoxazole and pyrazole derivatives. PMID:26383715
MCNP5 study on kinetics parameters of coupled fast-thermal system HERBE
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Pešić Milan P.
2011-01-01
Full Text Available New validation of the well-known Monte Carlo code MCNP5 against measured criticality and kinetics data for the coupled fast-thermal HERBE System at the Reactor B critical assembly is shown in this paper. Results of earlier calculations of these criticality and kinetics parameters, done by combination of transport and diffusion codes using two-dimension geometry model are compared to results of new calculations carried out by the MCNP5 code in three-dimension geometry. Satisfactory agreements in comparison of new results with experimental data, in spite complex heterogeneous composition of the HERBE core, are achieved confirming that MCNP5 code could apply successfully to study on HERBE kinetics parameters after uncertainties in impurities in material compositions and positions of fuel elements in fast zone were removed.
Hardee, John R.; Delgado, Bryan; Jones, Wray
2011-01-01
The kinetic parameters for the conversion of alpha-D-glucose to beta-D-glucose were measured using a blood glucometer. The reaction order, rate constant, and Arrhenius activation energy are reported for the noncatalyzed reaction and turnover number and Michaelis constant are reported for the reaction catalyzed by porcine kidney mutarotase. The…
Parameter analysis of the neutron point kinetics equations with feedback temperature effects
International Nuclear Information System (INIS)
Highlights: • Mathematical models describing the point reactor kinetics equations of Nuclear Power Plants. • Block diagram model for kinetic equations solution using VisSim environment. • Comparison between both analytical and numerical solutions. • Neutron flux density and reactor reactivity are analyzed. • Efficient control is performed for Nuclear Power Plants. - Abstract: The paper presents a solution technique for modeling point nuclear kinetic equations based on one group of delayed neutrons and temperature feedback. Explicit and implicit solutions for point kinetic equations are used for this purpose. Analytical treatment is conducted. Mathematical models describing neutron density and reactor reactivity are deduced. Also, Matlab Simulink and VisSim environments are used to achieve the implicit solution. Using of graphical user interface allows a quick experimentation with alternative values of performance parameters such as initial reactivity, initial neutron flux density, temperature coefficient of reactivity and reciprocal of thermal capacity of reactor. Moreover, implicit solutions of dynamic equations governing point nuclear kinetic equations provide exact handling of the device performance. Proposed mathematical models and block diagram simulation results are validated against published work and full agreements are obtained. Several performance parameters are tuned to enhance the performance of these point nuclear kinetic equations through the presented methodology. The resultant performance characteristics and comparison among investigated models are presented in this work. The obtained results confirm that the implicit solution showed less accurate representation of the studied point nuclear kinetic equations compared to mathematical models. Furthermore, the effect of control rod on the neutron flux density was discussed
Karuppusamy, S.; Dinesh Babu, K.; Nirmal Kumar, V.; Gopalakrishnan, R.
2016-05-01
The bulk acenaphthene crystal was grown in a single-wall ampoule by vertical Bridgman technique. X-ray diffraction analysis confirmed the orthorhombic crystal system of title compound with space group Pcm21. Thermal behavior of compound was studied using thermogravimetry—differential scanning calorimetry analysis. Thermal kinetic parameters like activation energy, frequency factor, Avrami exponent, reaction rate and degree of conversion were calculated using Kissingers and Ozawa methods under non-isothermal condition for acenaphthene crystal and reported for the first time. The calculated thermal kinetic parameters are presented. Dielectric studies were performed to calculate the dielectric parameters such as dielectric constant, dielectric loss, AC conductivity, and activation energy from Arrhenius plot.
Effect of temperature on kinetic parameters of decomposition reaction of calcium carbonate
Institute of Scientific and Technical Information of China (English)
CHEN Hongwei; CHEN Jiangtao; WEI Riguang; SUO Xinliang
2013-01-01
In order to investigate the influence of temperature on behavior of calcium carbonate decomposition,especially on kinetic parameters of the decomposition reaction,the analytically pure calcium carbonate was calcined on a self-built large dose thermogravimetric analyzer.The results indicated that,with an increase in the reaction temperature,the reactivity index of calcium carbonate decomposition increased at stage state while the kinetic parameters decreased at stage state.Moreover,both the reaction indices and the kinetic parameters can be divided into three stages and the temperature turning points in different stages were the same.The phase boundary reaction (cylindrical symmetry) theory was more suitable for calcium carbonate calcination under N2 atmosphere.The change trend of the logarithm of reaction activation with temperature was similar as that of the pre-exponential factor.There existed good liner relationship and kinetic compensation effect between them.The isokinetic temperature of the CaCO3 calcination was 842 ℃ and the reaction rate constant was 0.104 9 min-1 derived by the compensation coefficients.
Thermoluminescence kinetic parameters of different amount La-doped ZnB2O4
International Nuclear Information System (INIS)
The kinetic parameters of 1%, 2%, 3% and 4% La-doped ZnB2O4 phosphors (i.e. ZnB2O4:0.01La, ZnB2O4:0.02La, ZnB2O4:0.03La and ZnB2O4:0.04La) synthesized by nitric acid method have been calculated. Thermoluminescence (TL) glow curves of ZnB2O4:La phosphors after beta-irradiation showed a very well defined main peak having the maximum temperature at around 200 °C and a shoulder peak at around 315 °C with a constant heating rate of 5 °C/s. The kinetic parameters of ZnB2O4:La phosphors TL glow peaks (i.e. order of kinetics (b), activation energies (Ea) and frequency factors (s)) have been determined and evaluated by Computerized Glow Curve Deconvolution (CGCD), and Peak Shape (PS) methods using the glow curve data. From the results, it can conclude that the values of Ea obtained with these methods for ZnB2O4:La phosphors are consistent with each other, but the s values differ considerably. - Highlights: • Calculation of TL kinetic parameters for La-doped ZnB2O4. • La-doped ZnB2O4 was synthesized by nitric acid method. • Well defined main peak at about 200 °C
International Nuclear Information System (INIS)
This paper reports on the influence of calcining temperature (800 and 1000 deg. C) on the pozzolanic activation of sugar cane straw (SCS). The reaction kinetics of SCS ash-lime mixtures were inferred from physicochemical characteristics (X-ray diffraction patterns and thermogravimetry analysis. The fitting of a kinetic-diffusive model to the experimental data (fixed lime versus time) allowed the computing of the kinetic parameters (reaction rate constant) of the pozzolanic reaction. Results obtained confirm that the sugar cane straw ash (SCSA) calcined at 800 and 1000 deg. C have properties indicative of very high pozzolanic activity. No influence of calcining temperature on the pozzolanic activity was observed. Also, no crystalline compounds during the pozzolanic reaction were identified up to 90 days of reaction. Environmental durability and strength of the consequential mortars remain to be assessed
Parameter estimation for whole-body kinetic model of FDG metabolism
Institute of Scientific and Technical Information of China (English)
CUI Yunfeng; BAI Jing; CHEN Yingmao; TIAN Jiahe
2006-01-01
Based on the radioactive tracer [18F]2-fluoro-2-deoxy-D-glucose (FDG), positron emission tomography (PET), and compartment model, the tracer kinetic study has become an important method to investigate the glucose metabolic kinetics in human body.In this work, the kinetic parameters of three-compartment and four-parameter model for the FDG metabolism in the tissues of myocardium, lung, liver, stomach, spleen, pancreas, and marrow were estimated through some dynamic FDG-PET experiments. Together with published brain and skeletal muscle parameters, a relatively complete whole-body model was presented. In the liver model, the dual blood supply from the hepatic artery and the portal vein to the liver was considered for parameter estimation, and the more accurate results were obtained using the dual-input rather than the single arterial-input. The established whole-body model provides the functional information of FDG metabolism in human body. It can be used to further investigate the glucose metabolism, and also be used for the simulation and visualization of FDG metabolic process in human body.
Kinetic parameter calculation as function of burn-up of candu reactor
International Nuclear Information System (INIS)
Kinetic parameter calculation as function of burn-up of candu reactor. Kinetic marameter calculation as function of burp-up of CANDU reactor with Canflex fuel type-CANDU has been done. This type of fuel is currently being develop, so kinetic parameter such as effective delay neutron fraction (.......), delay neutron decay constant ( .... ) and prompt neutron generation time ( ...... ) are very important for analysis of reactor operation safety. WIMS-CRNL code was used to generate macroscopic cross section and reaction rate based on transport theory. Fast and thermal neutron velocity and macroscopic cross section fission product of the unit cell were determined by KINETIC Code. The result of calculation showed that the value of effective delay neutron fraction was 7,785616 x 10-3 at the beginning of operation at burn-up of 0 MWD/T and after the reactor operated at burn-up of 7,2231 x 10-3 MWD/T was 4,962766 x 10-3, or reduced by 36%. The value of prompt generation time was 9,982703 x 10-4 s at the beginning of operation at burn-up of 0 MWD/T and 8,965416 x 10-4 s after the reactor operated at burn-up of 7,2231 x 103 MWD/T, or reduced by 10%. The result of calculation showed that the values of effective delay neutron fraction and prompt neutron generation time are still great enough
Sutton, Jonathan E.; Guo, Wei; Katsoulakis, Markos A.; Vlachos, Dionisios G.
2016-04-01
Kinetic models based on first principles are becoming common place in heterogeneous catalysis because of their ability to interpret experimental data, identify the rate-controlling step, guide experiments and predict novel materials. To overcome the tremendous computational cost of estimating parameters of complex networks on metal catalysts, approximate quantum mechanical calculations are employed that render models potentially inaccurate. Here, by introducing correlative global sensitivity analysis and uncertainty quantification, we show that neglecting correlations in the energies of species and reactions can lead to an incorrect identification of influential parameters and key reaction intermediates and reactions. We rationalize why models often underpredict reaction rates and show that, despite the uncertainty being large, the method can, in conjunction with experimental data, identify influential missing reaction pathways and provide insights into the catalyst active site and the kinetic reliability of a model. The method is demonstrated in ethanol steam reforming for hydrogen production for fuel cells.
Kinetic parameters of soil β-glucosidase response to environmental temperature and moisture regimes
Yulan Zhang; Lijun Chen; Zhijie Wu; Caixia Sun
2011-01-01
Soil β-glucosidase participates in the final step of cellulose biodegradation. It is significant in the soil C cycle and is used as an indicator of the biological fertility of soil. However, the response of its kinetic parameters to environmental temperature and moisture regimes is not well understood. This study tested the β-glucosidase response in the main agricultural soils (black soil, albic soil, brown soil, and cinnamon soil) of Northeast China. Incubation tests were conducted to measur...
Prediction of radiation inactivation of presonicated a-amylase in terms of kinetic parameters
International Nuclear Information System (INIS)
Full text: In-vitro radiation inactivation of enzyme amylase denies display of optimum enzyme function owing to alterations in active site. Certain extent of enzyme activity seems to be protected in case of radiation inactivated enzyme, prior-exposed to ultrasonic frequencies. The present investigation, exploring trends of changes in kinetic parameters and its dependence on ultrasonic frequencies and gamma doses, will be discussed to highlight the functional status of active site under situation
Flow of kinetic parameters in a typical swimming pool type research reactor
International Nuclear Information System (INIS)
Calculations were performed to estimate the variation in kinetic parameters (delayed neutron fraction and prompt neutron generation time) in different core configurations of a typical swimming pool type research reactor. Pakistan research Reactor-1 (PARR-1) was employed for this study. The effect due to burnup of the core was also studied. Calculations were performed with the help of computer codes WIMSD/4 and CITATION. Precursors yield was modified according to the neutron flux averaging only. This is the simple way to calculate the precursor yield for a particular core. The kinetic parameters are different for different core configurations. The βeff decreases with 1.33 x 10-6/% burnup whereas prompt neutron generation time increases with 6.42 x 10-8 s/% burnup. The results were compared with safety analysis report and with published values and were found in good agreement. This study provides the confidence to understand the change in the kinetic parameters of research reactors with core change and also with burnup of the core
Application of the exact distribution pjk in the determination of kinetic parameters in a reactor
International Nuclear Information System (INIS)
In this report one distribution of neutron counts obtained by a detector placed in a reactor is studied in order to be used in the determination of reactor kinetic parameters such as β/Λ and reactivities. The parameters accuracy from this new method is compared with the Feynman and Mogilner method, based too in Reactor Neutron Noise Analysis. These three methods have been applied to JEN-2 reactor and the better accuracy and faster collection of experimental data give some interest to the new method which only requires a good footing code. (Author) 68 refs
Energy Technology Data Exchange (ETDEWEB)
Passalia, Claudio; Alfano, Orlando M. [INTEC - Instituto de Desarrollo Tecnologico para la Industria Quimica, CONICET - UNL, Gueemes 3450, 3000 Santa Fe (Argentina); FICH - Departamento de Medio Ambiente, Facultad de Ingenieria y Ciencias Hidricas, Universidad Nacional del Litoral, Ciudad Universitaria, 3000 Santa Fe (Argentina); Brandi, Rodolfo J., E-mail: rbrandi@santafe-conicet.gov.ar [INTEC - Instituto de Desarrollo Tecnologico para la Industria Quimica, CONICET - UNL, Gueemes 3450, 3000 Santa Fe (Argentina); FICH - Departamento de Medio Ambiente, Facultad de Ingenieria y Ciencias Hidricas, Universidad Nacional del Litoral, Ciudad Universitaria, 3000 Santa Fe (Argentina)
2012-04-15
Highlights: Black-Right-Pointing-Pointer Indoor pollution control via photocatalytic reactors. Black-Right-Pointing-Pointer Scaling-up methodology based on previously determined mechanistic kinetics. Black-Right-Pointing-Pointer Radiation interchange model between catalytic walls using configuration factors. Black-Right-Pointing-Pointer Modeling and experimental validation of a complex geometry photocatalytic reactor. - Abstract: A methodology for modeling photocatalytic reactors for their application in indoor air pollution control is carried out. The methodology implies, firstly, the determination of intrinsic reaction kinetics for the removal of formaldehyde. This is achieved by means of a simple geometry, continuous reactor operating under kinetic control regime and steady state. The kinetic parameters were estimated from experimental data by means of a nonlinear optimization algorithm. The second step was the application of the obtained kinetic parameters to a very different photoreactor configuration. In this case, the reactor is a corrugated wall type using nanosize TiO{sub 2} as catalyst irradiated by UV lamps that provided a spatially uniform radiation field. The radiative transfer within the reactor was modeled through a superficial emission model for the lamps, the ray tracing method and the computation of view factors. The velocity and concentration fields were evaluated by means of a commercial CFD tool (Fluent 12) where the radiation model was introduced externally. The results of the model were compared experimentally in a corrugated wall, bench scale reactor constructed in the laboratory. The overall pollutant conversion showed good agreement between model predictions and experiments, with a root mean square error less than 4%.
Performances of Different Algorithms for Tracer Kinetics Parameters Estimation in Breast DCE-MRI
Directory of Open Access Journals (Sweden)
Roberta Fusco
2014-07-01
Full Text Available Objective of this study was to evaluate the performances of different algorithms for tracer kinetics parameters estimation in breast Dynamic Contrast Enhanced-MRI. We considered four algorithms: two non-iterative algorithms based on impulsive and linear approximation of the Arterial Input Function respectively; and two iterative algorithms widely used for non-linear regression (Levenberg-Marquardt, LM and VARiable PROjection, VARPRO. Per each value of the kinetic parameters within a physiological range, we simulated 100 noisy curves and estimated the parameters with all algorithms. Sampling time, total duration and noise level have been chosen as in a typical breast examination. We compared the performances with respect to the Cramer-Rao Lower Bound (CRLB. Moreover, in order to gain further insight we applied the algorithms to a real breast examination. Accuracy of all the methods depends on the specific value of the parameters. The methods are in general biased: however, VARPRO showed small bias in a region of the parameter space larger than the other methods; moreover, VARPRO approached CRLB and the number of iterations were smaller than LM. In the specific conditions analyzed, VARPRO showed better performances with respect to LM and to non-iterative algorithms
Calculation of parameters from glow curves for the mixed-order kinetics
Energy Technology Data Exchange (ETDEWEB)
Pavlovic, M B [Vinca Institute of Nuclear Sciences, PO Box 522, 11001 Belgrade (Serbia and Montenegro); Faculty of Electrical Engineering, PO Box 816, 11000 Belgrade (Serbia and Montenegro); Vejnovic, Z [Institute of Security, Kraljice Ane bb 11000 Belgrade (Serbia and Montenegro); Davidovic, M [Vinca Institute of Nuclear Sciences, PO Box 522, 11001 Belgrade (Serbia and Montenegro); Faculty of Electrical Engineering, PO Box 816, 11000 Belgrade (Serbia and Montenegro)
2005-12-07
A new method for the calculation of parameters is proposed. The method is based on determination of the glow curve maximum and effective values of the half-width and part of the half-width on the higher temperature side. A relation between the symmetry factor as a function of the corresponding constant {alpha} = n{sub 0}/(h+n{sub 0}) and the correction factor {delta} is obtained. An approximate symmetry factor function is derived, which enables analytical calculation of the parameters: activation energy E, constant {alpha}, and pre-exponential factor s{sup (h)}. An iterative procedure is developed for more precise calculation of these parameters. The new method is checked for some characteristic values of the parameters. The connection between the models of general and mixed-order kinetics has been described theoretically.
An Evaluation of Kinetic Parameters of Cadmium and Copper Biosorption by Immobilized Cells
Directory of Open Access Journals (Sweden)
Nelly Georgieva
2007-10-01
Full Text Available Bioremediation is the use of living organisms to reduce or eliminate environmental hazards resulting from the accumulation of toxic chemicals and other hazardous wastes. This technology is based on the utilization of microorganisms to transform organic and inorganic compounds. The filamentous yeast Trichosporon cutaneum strain R57, immobilized and free cells was cultivated as batch culture on a liquid medium in the presence of various concentrations of cadmium and copper ions. The simultaneous uptake and accumulation of Cd2+ and Cu2+ ions by Tr. cutaneum cells depending on the initial concentration of Cd2+ and Cu2+ in the medium were studied. The potential use of the free and immobilized cells of Trichosporon cutaneum to remove cadmium and copper ions, from aqueous solutions was evaluated. Two important physicochemical aspects for the evaluation of the sorption process as a unit operation are the equilibrium of sorption and the kinetics. The Cd2+ and Cu2+ ions biosorption capacities of all tested adsorbent were presented as a function of the initial concentration of metal ions within the aqueous biosorption medium. The individual, as well as bicomponent sorption kinetics of copper and cadmium ions by immobilised cells of Trichosporon cutaneum R57 is presented. A second order kinetic model obtains kinetic parameters for the copper and cadmium ions.
Optimization of kinetic parameters for the degradation of plasmid DNA in rat plasma
Chaudhry, Q. A.
2014-12-01
Biotechnology is a rapidly growing area of research work in the field of pharmaceutical sciences. The study of pharmacokinetics of plasmid DNA (pDNA) is an important area of research work. It has been observed that the process of gene delivery faces many troubles on the transport of pDNA towards their target sites. The topoforms of pDNA has been termed as super coiled (S-C), open circular (O-C) and linear (L), the kinetic model of which will be presented in this paper. The kinetic model gives rise to system of ordinary differential equations (ODEs), the exact solution of which has been found. The kinetic parameters, which are responsible for the degradation of super coiled, and the formation of open circular and linear topoforms have a great significance not only in vitro but for modeling of further processes as well, therefore need to be addressed in great detail. For this purpose, global optimization techniques have been adopted, thus finding the optimal results for the said model. The results of the model, while using the optimal parameters, were compared against the measured data, which gives a nice agreement.
Association between plasma zinc concentration and zinc kinetic parameters in premenopausal women.
Yokoi, Katsuhiko; Egger, Norman G; Ramanujam, V M Sadagopa; Alcock, Nancy W; Dayal, Hari H; Penland, James G; Sandstead, Harold H
2003-11-01
The objective of this study was to measure relationships between plasma zinc (Zn) concentrations and Zn kinetic parameters and to measure relationships of Zn status with taste acuity, food frequency, and hair Zn in humans. The subjects were 33 premenopausal women not taking oral contraceptives and dietary supplements containing iron and Zn. Main outcomes were plasma Zn concentrations, Zn kinetic parameters based on the three-compartment mammillary model using 67Zn as a tracer, electrical taste detection thresholds, and food frequencies. Lower plasma Zn was significantly (P rate constants from the lesser peripheral pool to the central pool and from the central pool to the greater peripheral pool. The break points in the plasma Zn-Zn kinetics relationship were found between 9.94 and 11.5 micromol/l plasma Zn. Smaller size of the lesser peripheral pool was associated with lower frequency of beef consumption and higher frequency of bran breakfast cereal consumption. Hypozincemic women with plasma Zn low Zn status. PMID:12865259
Hybrid Differential Evolution for Estimation of Kinetic Parameters for Biochemical Systems
Institute of Scientific and Technical Information of China (English)
ZHAO Chao; XU Qiaoling; LIN Siming; LI Xuelai
2013-01-01
Determination of the optimal model parameters for biochemical systems is a time consuming iterative process.In this study,a novel hybrid differential evolution(DE)algorithm based on the differential evolution technique and a local search strategy is developed for solving kinetic parameter estimation problems.By combining the merits of DE with Gauss-Newton method,the proposed hybrid approach employs a DE algorithm for identifying promising regions of the solution space followed by use of Gauss-Newton method to determine the optimum in the identified regions.Some well-known benchmark estimation problems are utilized to test the efficiency and the robustness of the proposed algorithm compared to other methods in literature.The comparison indicates that the present hybrid algorithm outperforms other estimation techniques in terms of the global searching ability and the convergence speed.Additionally,the estimation of kinetic model parameters for a feed batch fermentor is carried out to test the applicability of the proposed algorithm.The result suggests that the method can be used to estimate suitable values of model parameters for a complex mathematical model.
Directory of Open Access Journals (Sweden)
Christley Scott
2010-07-01
Full Text Available Abstract Background Stochastic effects can be important for the behavior of processes involving small population numbers, so the study of stochastic models has become an important topic in the burgeoning field of computational systems biology. However analysis techniques for stochastic models have tended to lag behind their deterministic cousins due to the heavier computational demands of the statistical approaches for fitting the models to experimental data. There is a continuing need for more effective and efficient algorithms. In this article we focus on the parameter inference problem for stochastic kinetic models of biochemical reactions given discrete time-course observations of either some or all of the molecular species. Results We propose an algorithm for inference of kinetic rate parameters based upon maximum likelihood using stochastic gradient descent (SGD. We derive a general formula for the gradient of the likelihood function given discrete time-course observations. The formula applies to any explicit functional form of the kinetic rate laws such as mass-action, Michaelis-Menten, etc. Our algorithm estimates the gradient of the likelihood function by reversible jump Markov chain Monte Carlo sampling (RJMCMC, and then gradient descent method is employed to obtain the maximum likelihood estimation of parameter values. Furthermore, we utilize flux balance analysis and show how to automatically construct reversible jump samplers for arbitrary biochemical reaction models. We provide RJMCMC sampling algorithms for both fully observed and partially observed time-course observation data. Our methods are illustrated with two examples: a birth-death model and an auto-regulatory gene network. We find good agreement of the inferred parameters with the actual parameters in both models. Conclusions The SGD method proposed in the paper presents a general framework of inferring parameters for stochastic kinetic models. The method is
Berezovska, Ganna; Mostarda, Stefano; Rao, Francesco
2012-01-01
Molecular simulations as well as single molecule experiments have been widely analyzed in terms order parameters, the latter representing candidate probes for the relevant degrees of freedom. Notwithstanding this approach is very intuitive, mounting evidence showed that such description is not accurate, leading to ambiguous definitions of states and wrong kinetics. To overcome these limitations a framework making use of order parameter fluctuations in conjunction with complex network analysis is investigated. Derived from recent advances in the analysis of single molecule time traces, this approach takes into account of the fluctuations around each time point to distinguish between states that have similar values of the order parameter but different dynamics. Snapshots with similar fluctuations are used as nodes of a transition network, the clusterization of which into states provides accurate Markov-State-Models of the system under study. Application of the methodology to theoretical models with a noisy orde...
Institute of Scientific and Technical Information of China (English)
XIONG CaiQiao; XIA ZhiNing; HUANG Rui; CHEN Hua; XU Pan
2008-01-01
A novel plug-plug kinetic capillary electrophoresis method was established, which can be used to si-multaneously determine the kinetic parameters kon and koff in interaction systems. The method is comparatively simple and some restrictions in conventional ppKCE methods can be effectively avoided, The requirements for resolution and detection sensitivity in this method are much lower than those of conventional ppKCE, The successful determination of the kinetic parameters and the binding constant Kb between citalopram and BSA showed availability of this method, The results were confirmed by us-ing the time ratio method. The application field of kinetic capillary electrophoresis can be expanded with this new method,
Institute of Scientific and Technical Information of China (English)
2008-01-01
A novel plug-plug kinetic capillary electrophoresis method was established, which can be used to si-multaneously determine the kinetic parameters kon and koff in interaction systems. The method is comparatively simple and some restrictions in conventional ppKCE methods can be effectively avoided. The requirements for resolution and detection sensitivity in this method are much lower than those of conventional ppKCE. The successful determination of the kinetic parameters and the binding constant Kb between citalopram and BSA showed availability of this method. The results were confirmed by us-ing the time ratio method. The application field of kinetic capillary electrophoresis can be expanded with this new method.
Calculation of kinetics parameters for the Dalat Nuclear Reactor (DNR) using MCNP5
International Nuclear Information System (INIS)
The determination of kinetics parameters takes an important role in the safety operation of a nuclear reactor, thus the calculation of these parameters is essential. This paper presents the application of Monte-Carlo method in order to perform the above-mentioned purpose. Two types of calculated kinetics parameters for the Dalat reactor are the effective delayed neutron fraction (βeff ) and the prompt neutron generation time (lp). The calculations were performed for the fuel loading patterns of 104 high-enriched uranium (HEU) fuel assemblies and 92 low-enriched uranium (LEU) fuel assemblies. The effective delayed neutron fractions were calculated by prompt method, and the calculated results are 0.80 ± 0.02% for HEU and 0.75 ± 0.03% for LEU fuel loading pattern. The prompt neutron generation times were calculated by 1/v method, and the calculated results are 95.01 ± 1.96 (µs) for HEU and 92.31 ± 2.64 (µs) for LEU fuel loading pattern. The comparison of (βeff/lp) ratio between the calculation and previous measurement shows a good agreement. (author)
Rebutini, Vanessa Z; Pereira, Gleber; Bohrer, Roberta C D; Ugrinowitsch, Carlos; Rodacki, André L F
2016-09-01
Rebutini, VZ, Pereira, G, Bohrer, RCD, Ugrinowitsch, C, and Rodacki, ALF. Plyometric long jump training with progressive loading improves kinetic and kinematic swimming start parameters. J Strength Cond Res 30(9): 2392-2398, 2016-This study was aimed to determine the effects of a plyometric long jump training program on torque around the lower limb joints and kinetic and kinematics parameters during the swimming jump start. Ten swimmers performed 3 identical assessment sessions, measuring hip and knee muscle extensors during maximal voluntary isometric contraction and kinetic and kinematics parameters during the swimming jump start, at 3 instants: INI (2 weeks before the training program, control period), PRE (2 weeks after INI measurements), and POST (24-48 hours after 9 weeks of training). There were no significant changes from INI to PRE measurements. However, the peak torque and rate of torque development increased significantly from PRE to POST measurements for both hip (47 and 108%) and knee (24 and 41%) joints. There were significant improvements to the horizontal force (7%), impulse (9%), and angle of resultant force (19%). In addition, there were significant improvements to the center of mass displacement (5%), horizontal takeoff velocity (16%), horizontal velocity at water entrance (22%), and peak angle velocity for the knee (15%) and hip joints (16%). Therefore, the plyometric long jump training protocol was effective to enhance torque around the lower limb joints and to control the resultant vector direction, to increase the swimming jump start performance. These findings suggest that coaches should use long jump training instead of vertical jump training to improve swimming start performance.
Gas phase NMR spectra of N,N-dimethylnitrosamine. Environmental effects on kinetic parameters
Chauvel, J. Paul; Leung, Doris Y.; True, Nancy S.
1984-04-01
Gas phase 1H NMR spectra of N,N-dimethylnitrosamine are consistent with first order chemical exchange rate constants which are ca. 25 times faster than those observed in neat liquids at corresponding temperatures. The associated kinetic parameters: Eact(∞), 20.5(1.1) kcal mol -1, Δ H‡, 19.7(1.0) kcal mol -1 and Δ G‡, 21.1(0.4) kcal mol -1 are approximately 2.5 kcal mol -1 lower than the most recently reported values for the neat liquid. The observed phase dependence is consistent with a process proceeding via a freely rotating transition state.
Effects of metformin on cell kinetic parameters of MCF-7 breast cancer cells in vitro.
Topcul, Mehmet; Cetin, Idil
2015-01-01
In this study, the antiproliferative effects of the metformin was evaluated on MCF-7 Cells (human breast adenocarcinoma cell line). For this purpose cell kinetic parameters including cell proliferation assay, mitotic index and labelling index analysis were used. 30 μM, 65 μM and 130 μM Metformin doses were applied to cells for 24, 48 and 72 hours. The results showed that there was a significant decrease in cell proliferation, mitotic index and labelling index for all experimental groups (p<0.05) for all applications. PMID:25824763
Claudio Milton Montenegro Campos; Marco Antonio Calil Prado; Erlon Lopes Pereira
2014-01-01
This study evaluated the treatment of wastewater from coffee wet processing (WCWP) in an anaerobic treatment system at a laboratory scale. The system included an acidification/equalization tank (AET), a heat exchanger, an Upflow Anaerobic Sludge Blanket Reactor (UASB), a gas equalization device and a gas meter. The minimum and maximum flow rates and volumetric organic loadings rate (VOLR) were 0.004 to 0.037 m 3 d -1 and 0.14 to 20.29 kgCOD m -3 d -1 , respectively. The kinetic parameters mea...
The strong prognostic value of KELIM, a model-based parameter from CA 125 kinetics in ovarian cancer
DEFF Research Database (Denmark)
You, Benoit; Colomban, Olivier; Heywood, Mark;
2013-01-01
Unexpected results were recently reported about the poor surrogacy of Gynecologic Cancer Intergroup (GCIG) defined CA-125 response in recurrent ovarian cancer (ROC) patients. Mathematical modeling may help describe CA-125 decline dynamically and discriminate prognostic kinetic parameters....
Classical nucleation theory of homogeneous freezing of water: thermodynamic and kinetic parameters.
Ickes, Luisa; Welti, André; Hoose, Corinna; Lohmann, Ulrike
2015-02-28
The probability of homogeneous ice nucleation under a set of ambient conditions can be described by nucleation rates using the theoretical framework of Classical Nucleation Theory (CNT). This framework consists of kinetic and thermodynamic parameters, of which three are not well-defined (namely the interfacial tension between ice and water, the activation energy and the prefactor), so that any CNT-based parameterization of homogeneous ice formation is less well-constrained than desired for modeling applications. Different approaches to estimate the thermodynamic and kinetic parameters of CNT are reviewed in this paper and the sensitivity of the calculated nucleation rate to the choice of parameters is investigated. We show that nucleation rates are very sensitive to this choice. The sensitivity is governed by one parameter - the interfacial tension between ice and water, which determines the energetic barrier of the nucleation process. The calculated nucleation rate can differ by more than 25 orders of magnitude depending on the choice of parameterization for this parameter. The second most important parameter is the activation energy of the nucleation process. It can lead to a variation of 16 orders of magnitude. By estimating the nucleation rate from a collection of droplet freezing experiments from the literature, the dependence of these two parameters on temperature is narrowed down. It can be seen that the temperature behavior of these two parameters assumed in the literature does not match with the predicted nucleation rates from the fit in most cases. Moreover a comparison of all possible combinations of theoretical parameterizations of the dominant two free parameters shows that one combination fits the fitted nucleation rates best, which is a description of the interfacial tension coming from a molecular model [Reinhardt and Doye, J. Chem. Phys., 2013, 139, 096102] in combination with the activation energy derived from self-diffusion measurements [Zobrist
Institute of Scientific and Technical Information of China (English)
Panusit Sungsuk; Sasiporn Chayaporn; Sasithorn Sunphorka; Prapan Kuchonthara; Pornpote Piumsomboon; Benjapon Chalermsinsuwan
2016-01-01
The aim of this study is to determine the effect of the main chemical components of biomass:cel ulose, hemicel-lulose and lignin, on chemical kinetics of biomass pyrolysis. The experiments were designed based on a simplex-lattice mixture design. The pyrolysis was observed by using a thermogravimetric analyzer. The curves obtained from the employed analytical method fit the experimental data (R2 N 0.9). This indicated that this method has the potential to determine the kinetic parameters such as the activation energy (Ea), frequency factor (A) and re-action order (n) for each point of the experimental design. The results obtained from the simplex-lattice mixture design indicated that cellulose had a significant effect on Ea and A, and the interaction between cellulose and lignin had an important effect on the reaction order, n. The proposed models were then proved to be useful for predicting pyrolysis behavior in real biomass and so could be used as a simple approximation for predicting the overall trend of chemical reaction kinetics.
Effect of diet-induced obesity on kinetic parameters of amino acid uptake by rat erythrocytes.
Picó, C; Pons, A; Palou, A
1992-11-01
The effects of cafeteria diet-induced obesity upon in vitro uptake of L-Alanine, Glycine, L-Lysine, L-Glutamine, L-Glutamic acid, L-Phenylalanine and L-Leucine by isolated rat erythrocytes have been studied. The total Phe and Leu uptakes followed Michaelis-Menten kinetics. The Glu uptake was fitted to diffusion kinetics. The uptakes of Ala, Gly, Lys and Gln were best explained by a two-component transport: one saturable and one diffusion. Obesity increased the Km value for Ala, Gln and Leu, and the Vmax value for Ala, but decreased the Vmax for Lys. Kinetic parameters of Phe uptake were unaffected by obesity. In addition, the pseudo-first order rate constant (Vmax/Km) for Ala, Gly, Gln, Lys and Leu uptake decreased as a result of cafeteria diet-induced obesity. The Kd value for Ala, Gly, Gln and Glu decreased and that of Lys increased as result of obesity. These adaptations could, at least in part, explain alterations in amino acid distribution between blood cells and plasma related to overfeeding or obesity.
Determination of the kinetic parameters of Be O using isothermal decay method
Energy Technology Data Exchange (ETDEWEB)
Azorin N, J.; Torijano C, E. [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 Mexico D. F. (Mexico); Azorin V, C.; Rivera M, T., E-mail: azorin@xanum.uam.mx [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria 694, Col. Irrigacion, 11500 Mexico D. F. (Mexico)
2015-10-15
Full text: Most of the existing methods for obtaining the frequency factors make use of the trap depth (activation energy) making some assumptions about the order of the kinetics. This causes inconsistencies in the reported values of trapping parameters due that the values of the activation energy obtained by different methods differ appreciably among them. Then, it is necessary to use a method independent of the trap depth making use of the isothermal luminescence decay method. The trapping parameters associated with the prominent glow peak of Be O (280 degrees C) are reported using isothermal luminescence decay method. As a check, the trap parameters are also calculated by glow curve shape (Chen s) method after isolating the prominent glow peak by thermal cleaning technique. Our results show a very good agreement between the trapping parameters calculated by the two methods. Isothermal luminescence decay method was used for determining the trapping parameters of Be O. Results obtained applying this method are in good agreement with those obtained using other methods, except in the value of the frequency factor. (Author)
Comment on teaching the flux and transport parameters of Maxwellian gas within the kinetic theory
International Nuclear Information System (INIS)
Within the kinetic theory of an ideal gas, the flux of particles having a number density n, and average velocity ν-bar impinging on a plane from one side, is sometimes written in textbooks as nν-bar/6 and sometimes as nν-bar/4. The validity of each expression is worked out here with emphasis on their effect on the pre-factor for the expressions of the transport parameters such as viscosity, diffusion coefficient and heat conductivity. It is shown that nν-bar/4 is valid in equilibrium while only when there are gradients, effectively the flux becomes nν-bar/6. For the correct derivation of the transport parameters the introduction of a distribution function for the collision times or mean free paths is essential. A methodology is suggested on how to teach this subject to undergraduate and graduate students. (author)
Institute of Scientific and Technical Information of China (English)
WU Jian; LI Zhong; LUO He-an
2006-01-01
Beckmann rearrangement mechanism of cyclohexanone oxime, based on the characteristic of self-catalyzed reaction and polymorphism was proposed. According to the suggested mechanism, the basic approach was the rearrangement of OXH+ while the SO3 acts as dehydrating agent and OXSO3 can turn to CPLSO3 ultimately. Considering self-catalyzed reaction between OXSO3 and CPLH+ , kinetic model for Beckmann rearrangement was established. Corresponding parameters were estimated by using float genetic algorithm (GA) and simulation results agree well with the experimental data below -19.3℃. Industrial equipment was simulated and analyzed. Effects of key process parameters such as molar ratio of sulfuric acid to oxime and circulation ratio on the residual oxime are also discussed. The results show that the caprolactam exists as CPLH+ finally in oleum and the minimum molecular ratio of sulfuric acid to oxime can be 0.5 theoretically.
Directory of Open Access Journals (Sweden)
Dessy Ariyanti
2013-03-01
Full Text Available Whey is the liquid remaining after milk has been curdled and strained. It is a by-product of the manufacture of cheese or casein and has several commercial uses. In environmental point of view, whey is kind of waste which has high pollution level due to it’s contain high organic compound with BOD and COD value 50 and 80 g/L respectively. On the other side, whey also contain an amount of lactose (4.5%-5%; lactose can be used as carbon source and raw material for producing ethanol via fermentation using yeast strain Kluyveromyces marxianus. The objective of this research is to investigate the ethanol production kinetics from crude whey through fermentation using Kluyveromyces marxianus and to predict the model kinetics parameter. The yeast was able to metabolize most of the lactose within 16 h to give 8.64 g/L ethanol, 4.43 g/L biomass, and remain the 3.122 g/L residual lactose. From the results presented it also can be concluded that common kinetic model for microbial growth, substrate consumption, and product formation is a good alternative to describe an experimental batch fermentation of Kluyveromyces marxianus grown on a medium composed of whey. The model was found to be capable of reflecting all batch culture phases to a certain degree of accuracy, giving the parameter value: μmax, Ks, YX/S, α, β : 0.32, 10.52, 0.095, 1.52, and 0.11 respectively. © 2013 BCREC UNDIP. All rights reserved(Selected Paper from International Conference on Chemical and Material Engineering (ICCME 2012Received: 27th September 2012; Revised: 29th November 2012; Accepted: 7th December 2012[How to Cite: D. Ariyanti, H. Hadiyanto, (2013. Ethanol Production from Whey by Kluyveromyces marxianus in Batch Fermentation System: Kinetics Parameters Estimation. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (3: 179-184. (doi:10.9767/bcrec.7.3.4044.179-184][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.7.3.4044.179-184 ] View in |
Local field potentials in primate motor cortex encode grasp kinetic parameters.
Milekovic, Tomislav; Truccolo, Wilson; Grün, Sonja; Riehle, Alexa; Brochier, Thomas
2015-07-01
Reach and grasp kinematics are known to be encoded in the spiking activity of neuronal ensembles and in local field potentials (LFPs) recorded from primate motor cortex during movement planning and execution. However, little is known, especially in LFPs, about the encoding of kinetic parameters, such as forces exerted on the object during the same actions. We implanted two monkeys with microelectrode arrays in the motor cortical areas MI and PMd to investigate encoding of grasp-related parameters in motor cortical LFPs during planning and execution of reach-and-grasp movements. We identified three components of the LFP that modulated during grasps corresponding to low (0.3-7Hz), intermediate (~10-~40Hz) and high (~80-250Hz) frequency bands. We show that all three components can be used to classify not only grip types but also object loads during planning and execution of a grasping movement. In addition, we demonstrate that all three components recorded during planning or execution can be used to continuously decode finger pressure forces and hand position related to the grasping movement. Low and high frequency components provide similar classification and decoding accuracies, which were substantially higher than those obtained from the intermediate frequency component. Our results demonstrate that intended reach and grasp kinetic parameters are encoded in multiple LFP bands during both movement planning and execution. These findings also suggest that the LFP is a reliable signal for the control of parameters related to object load and applied pressure forces in brain-machine interfaces. PMID:25869861
Energy Technology Data Exchange (ETDEWEB)
Guo, Shuanbao; Xu, Pengcheng; Yu, Haitao; Cheng, Zhenxing; Li, Xinxin, E-mail: xxli@mail.sim.ac.cn
2015-03-10
Highlights: • Sensing material can be comprehensively optimized by using gravimetric cantilever. • Kinetic-thermodynamic model parameters are quantitatively extracted by experiment • Sensing-material performance is synergistically optimized by extracted parameters. - Abstract: A novel method is explored for comprehensive design/optimization of organophosphorus sensing material, which is loaded on mass-type microcantilever sensor. Conventionally, by directly observing the gas sensing response, it is difficult to build quantitative relationship with the intrinsic structure of the material. To break through this difficulty, resonant cantilever is employed as gravimetric tool to implement molecule adsorption experiment. Based on the sensing data, key kinetic/thermodynamic parameters of the material to the molecule, including adsorption heat −ΔH°, adsorption/desorption rate constants K{sub a} and K{sub d}, active-site number per unit mass N′ and surface coverage θ, can be quantitatively extracted according to physical–chemistry theories. With gaseous DMMP (simulant of organophosphorus agents) as sensing target, the optimization route for three sensing materials is successfully demonstrated. Firstly, a hyper-branched polymer is evaluated. Though suffering low sensitivity due to insufficient N′, the bis(4-hydroxyphenyl)-hexafluoropropane (BHPF) sensing-group exhibits satisfactory reproducibility due to appropriate −ΔH°. To achieve more sensing-sites, KIT-5 mesoporous-silica with higher surface-area is assessed, resulting in good sensitivity but too high −ΔH° that brings poor repeatability. After comprehensive consideration, the confirmed BHPF sensing-group is grafted on the KIT-5 carrier to form an optimized DMMP sensing nanomaterial. Experimental results indicate that, featuring appropriate kinetic/thermodynamic parameters of −ΔH°, K{sub a}, K{sub d}, N′ and θ, the BHPF-functionalized KIT-5 mesoporous silica exhibits synergistic
The role of test parameters on the kinetics and thermodynamics of glass leaching. [None
Energy Technology Data Exchange (ETDEWEB)
Jantzen, C M
1988-01-01
The relative durabilities of nuclear waste, natural, and ancient glasses have been assessed by standard laboratory leach tests. Different test conditions result in different glass surface areas (SA), leachant volumes (V), and test durations (t). Leachate concentrations are known to be a parabolic function of the kinetic test parameter SAV/center dot/t. Based on durability experiments of glass monoliths at low (SAV)/center dot/ glass durability has been shown to be a logarithmic function of the thermodynamic hydration free energy, ..delta..G/sub hyd/. The thermodynamic hydration free energy, ..delta..G/sub hyd/, can be calculated from glass composition and solution pH. In the repository environment high effective glass surface areas to solution volume ratios may occur as a result of slow groundwater flow rates. The application of hydration thermodynamics to crushed glass, high (SAV)/center dot/t, durability tests has been demonstrated. The relative contributions of the kinetic test parameters, (SAV)/center dot/t, and the thermodynamic parameter, ..delta..G/sub hyd/, have been shown to define a plane in ..delta..G/sub hyd/-concentration-(SAV)/center dot/t space. At constant test conditions, e.g. constant (SAV/center dot/t, the intersection with this surface indicates that all /delta G//sub hyd/-concentration plots should have similar slopes and predict the same relative durabilities for various glasses as a function of glass composition. Using this approach, the durability of nuclear waste glasses has been interpolated to be -- 10/sup 6/ years and no less than 10/sup 3/ years. 28 refs., 24 figs.
Morin, José A.; Ibarra, Borja; Cao, Francisco J.
2016-05-01
Single-molecule manipulation experiments of molecular motors provide essential information about the rate and conformational changes of the steps of the reaction located along the manipulation coordinate. This information is not always sufficient to define a particular kinetic cycle. Recent single-molecule experiments with optical tweezers showed that the DNA unwinding activity of a Phi29 DNA polymerase mutant presents a complex pause behavior, which includes short and long pauses. Here we show that different kinetic models, considering different connections between the active and the pause states, can explain the experimental pause behavior. Both the two independent pause model and the two connected pause model are able to describe the pause behavior of a mutated Phi29 DNA polymerase observed in an optical tweezers single-molecule experiment. For the two independent pause model all parameters are fixed by the observed data, while for the more general two connected pause model there is a range of values of the parameters compatible with the observed data (which can be expressed in terms of two of the rates and their force dependencies). This general model includes models with indirect entry and exit to the long-pause state, and also models with cycling in both directions. Additionally, assuming that detailed balance is verified, which forbids cycling, this reduces the ranges of the values of the parameters (which can then be expressed in terms of one rate and its force dependency). The resulting model interpolates between the independent pause model and the indirect entry and exit to the long-pause state model
Kinetic parameter estimation and fluctuation analysis of CO at SnO 2 single nanowires
Tulzer, Gerhard
2013-07-12
In this work, we present calculated numerical values for the kinetic parameters governing adsorption/desorption processes of carbon monoxide at tin dioxide single-nanowire gas sensors. The response of such sensors to pulses of 50 ppm carbon monoxide in nitrogen is investigated at different temperatures to extract the desired information. A rate-equation approach is used to model the reaction kinetics, which results in the problem of determining coefficients in a coupled system of nonlinear ordinary differential equations. The numerical values are computed by inverse-modeling techniques and are then used to simulate the sensor response. With our model, the dynamic response of the sensor due to the gas-surface interaction can be studied in order to find the optimal setup for detection, which is an important step towards selectivity of these devices. We additionally investigate the noise in the current through the nanowire and its changes due to the presence of carbon monoxide in the sensor environment. Here, we propose the use of a wavelet transform to decompose the signal and analyze the noise in the experimental data. This method indicates that some fluctuations are specific for the gas species investigated here. © 2013 IOP Publishing Ltd.
Determination of kinetic parameters of Phlomis bovei de Noé using thermogravimetric analysis.
Yahiaoui, Meriem; Hadoun, Hocine; Toumert, Idir; Hassani, Aicha
2015-11-01
This paper reports the pyrolysis study of Phlomis bovei biomass by thermogravimetric experiments in order to determine the thermal degradation behavior and kinetic parameters. The weight losses were found to occur in three stages. In the DTG thermograms, an increase of the heating rate tended to delay thermal degradation processes towards higher temperatures. The average values of activation energy and pre-exponential factor calculated from Ozawa-Flynn-Wall, Kissinger-Akahira-Sunose and Kissinger methods are 134.83, 134.06, 223.31kJ/mol and 4.1610(13), 1.1810(10), 2.8110(11)/s, respectively. The three-pseudo-component method shows that the activation energy increases with increasing the heating rate for hemicellulose and cellulose while the activation energy of the lignin decreased with an increase of the heating rate. Predicted results and experimental data exhibit similar tendencies and the three pseudo-components model with n different from unity 1 is recommended as the most suitable for prediction of kinetic behavior of Phlomis bovei de Noé.
Does Vibration Warm-up Enhance Kinetic and Temporal Sprint Parameters?
Cochrane, D J; Cronin, M J; Fink, P W
2015-08-01
The aim of this study was to investigate the efficacy of vibration warm-up to enhance sprint performance. 12 males involved in representative team sports performed 4 warm-up conditions in a randomised order performed at least 24 h apart; VbX warm-up (VbX-WU); Neural activation warm-up (Neu-WU); Dynamic warm-up (Dyn-WU) and Control (No VbX). Participants completed 5 m sprint at 30 s, 2:30 min and 5 min post warm-up where sprint time, kinetics, and temporal components were recorded. There was no significant (p>0.05) main effect or interaction effect between the split sprint times of 1 m, 2.5 m, and 5 m. There was a condition effect where vertical mean force was significantly higher (p0.05) main and interaction effects in sprint kinetic and temporal parameters existed. Overall, all 4 warm-up conditions produced comparable results for sprint performance, and there was no detrimental effect on short-duration sprint performance using VbX-WU. Therefore, VbX could be useful for adding variety to the training warm-up or be included into the main warm-up routine as a supplementary modality.
A new multi-wavelength model-based method for determination of enzyme kinetic parameters
Indian Academy of Sciences (India)
Mohammad-Hossein Sorouraddin; Kaveh Amini; Abdolhossein Naseri; Javad Vallipour; Jalal Hanaee; Mohammad-Reza Rashidi
2010-09-01
Lineweaver–Burk plot analysis is the most widely used method to determine enzyme kinetic parameters. In the spectrophotometric determination of enzyme activity using the Lineweaver–Burk plot, it is necessary to find a wavelength at which only the substrate or the product has absorbance without any spectroscopic interference of the other reaction components. Moreover, in this method, different initial concentrations of the substrate should be used to obtain the initial velocities required for Lineweaver–Burk plot analysis. In the present work, a multi-wavelength model-based method has been developed and validated to determine Michaelis–Menten constants for some enzyme reactions. In this method, a selective wavelength region and several experiments with different initial concentrations of the substrate are not required. The absorbance data of the kinetic assays are fitted by non-linear regression coupled to the numeric integration of the related differential equation. To indicate the applicability of the proposed method, the Michaelis–Menten constants for the oxidation of phenanthridine, 6-deoxypenciclovir and xanthine by molybdenum hydroxylases were determined using only a single initial concentration of the substrate, regardless of any spectral overlap.
Nagaya, Yasunobu
2014-06-01
The methods to calculate the kinetics parameters of βeff and Λ with the differential operator sampling have been reviewed. The comparison of the results obtained with the differential operator sampling and iterated fission probability approaches has been performed. It is shown that the differential operator sampling approach gives the same results as the iterated fission probability approach within the statistical uncertainty. In addition, the prediction accuracy of the evaluated nuclear data library JENDL-4.0 for the measured βeff/Λ and βeff values is also examined. It is shown that JENDL-4.0 gives a good prediction except for the uranium-233 systems. The present results imply the need for revisiting the uranium-233 nuclear data evaluation and performing the detailed sensitivity analysis.
Measuring the kinetic parameters of saltating sand grains using a high-speed digital camera
Zhang, Yang; Wang, Yuan; Jia, Pan
2014-06-01
A high-speed digital camera is used to record the saltation of three sand samples (diameter range: 300-500, 200-300 and 100-125 μm). This is followed by an overlapping particle tracking algorithm to reconstruct the saltating trajectory and the differential scheme to abstract the kinetic parameters of saltating grains. The velocity results confirm the propagating feature of saltation in maintaining near-face aeolian sand transport. Moreover, the acceleration of saltating sand grains was obtained directly from the reconstructed trajectory, and the results reveal that the climbing stage of the saltating trajectory represents an critical process of energy transfer while the sand grains travel through air.
Evaluation of kinetic parameters and redox mechanism of quinoxaline at glassy carbon electrode
Directory of Open Access Journals (Sweden)
Aleksić Mara M.
2014-01-01
Full Text Available The electrochemical behavior of a biologically important heterocyclic compound quinoxaline (QUI was investigated by cyclic voltammetry (CV in solutions of differing pH, using a glassy carbon electrode (GCE. The reduction of QUI occurs as a quasi-reversible reaction in acid medium, reaching reversibility in alkaline solutions. The kinetic parameters of the electrode process such as αnα, diffusion coefficient (D and heterogeneous rate constant (ks, were evaluated and discussed. Redox mechanism of QUI was proposed on the basis of experimental results. Reduction process involves a transfer of two electrons and two protons at the pyrazine ring of QUI forming a dihydro-derivative. In acid solutions, the product of QUI reduction undergoes irreversible oxidation in a one-electron process. The electrode processes was found to be diffusion controlled. [Projekat Ministarstva nauke Republike Srbije, br. 172033
Energy Technology Data Exchange (ETDEWEB)
Aceves, S; Dibble, R; Flowers, D; Smith, J R; Westbrook, C K
1999-07-19
This paper uses the HCT (Hydrodynamics, Chemistry and Transport) chemical kinetics code to analyze natural gas HCCI combustion in an engine. The HCT code has been modified to better represent the conditions existing inside an engine, including a wall heat transfer correlation. Combustion control and low power output per displacement remain as two of the biggest challenges to obtaining satisfactory performance out of an HCCI engine, and these are addressed in this paper. The paper considers the effect of natural gas composition on HCCI combustion, and then explores three control strategies for HCCI engines: DME (dimethyl ether) addition, intake heating and hot EGR addition. The results show that HCCI combustion is sensitive to natural gas composition, and an active control may be required to compensate for possible changes in composition. The three control strategies being considered have a significant effect in changing the combustion parameters for the engine, and should be able to control HCCI combustion.
Determination Of Enzyme Kinetic Parameters on Sago Starch Hydrolysis By Linearized Graphical Methods
International Nuclear Information System (INIS)
Amyloglucosidase (E.C. 3.2.1.3) from Aspergillus niger was used to hydrolyze the sago (Metro xylon sagu) starch into reducing sugars. The experiment was conducted at constant temperature, 55 degree Celsius; pH, 4.5 and enzyme amount, 0.2 U/ ml, respectively. In this investigation, the substrate concentration was varied ranging from 1.0 - 7.0 g/ L. The obtained data were then fixed into linearized plots namely Lineweaver-Burk and Langmuir models to calculate enzyme kinetic parameters, Km and Vmax. Both of the Km and Vmax (mM, mol/min) values from each plot were: Lineweaver-Burk (26.53, 3.31) and Langmuir (13.52, 2.35). Among the linearized models, Km and Vmax values acquired from Langmuir plot was chosen. (author)
International Nuclear Information System (INIS)
Highlights: • Among the kinetic parameters, the most important ones are βeff and Λ. • Several methods including the Rossi-α and Feynman-α techniques, slope fit and MCNPX code have been investigated. • The Monte Carlo MCNPX code was used to simulate a geometrical model of the TRIGA core. • The results of the methods have been validated. - Abstract: In this study, noise analysis techniques including Feynman-α (variance-to-mean) and Rossi-α (correlation) and dynamic method such as slope fit method have been used to calculate effective delayed neutron fraction (βeff) and neutron reproduction time (Λ) in Accelerator Driven Subcritical TRIGA reactor. The obtained results have been compared with MCNPX code results. The relative difference between MCNPX code with Feynman-α and Rossi-α techniques and slope fit method for βeff are approximately −5.4%, 1.2%, and −10.6%, −14.8%, respectively, and also for Λ is approximately 2.1%. According to results, the noise methods can been considered ideal for detection with high efficiency and zero dead time and in the slope fit method, the decay of the delayed neutrons has been neglected and only the prompt neutrons have been taken into account. In addition, quantities simulated in the current study are validated against both the reference data and the results of MCNPX code. Therefore, the purpose of this study is to simulate the commonly used experimental methods by MCNPX code and investigate the convergence as well as accuracy of the computational results for different analysis methods in calculation of the kinetic parameters in an Accelerator Driven Subcritical TRIGA reactor
Yazici, A N
2003-01-01
In this paper, the thermal bleaching curves (TBCs) of specific optical absorption bands of LiF : Mg,Ti were measured as a function of temperature. The TBCs obtained were analysed to extract the kinetic parameters (the thermal activation energy (E) and the frequency factor (s)) of some TL glow peaks of LiF : Mg,Ti on the basis of the developed first-order kinetic model over a specified temperature region.
de Andrade, Rafael Ramos; Rivera, Elmer Ccopa; Atala, Daniel I P; Filho, Rubens Maciel; Filho, Francisco Maugeri; Costa, Aline C
2009-08-01
The accurate description of the kinetics and robust modeling of biotechnological processes can only be achieved by incorporating reliable methodologies to easily update the model when there are changes in operational conditions. The purpose of this work is to provide a systematic approach with which to perform model parameters screening and updating in biotechnological processes. Batch experiments are performed to develop a mechanistic model, considering the effect of temperature on the kinetics, and further experiments (batch fermentations using sugar cane molasses from a different harvest) are used to validate the effectiveness of screening before parameters updating. The reduction in the number of kinetic parameters to be re-estimated enabled by the screening procedure reduces significantly the complexity of the optimization, which makes the updating procedure to be significantly quicker, while resulting in accurate performance of the updated model. PMID:19125302
International Nuclear Information System (INIS)
This work presents a theoretical study of reactor kinetics focusing on the methodology of calculation and the experimental measurements of the so-called kinetic parameters. A comparison between the methodology based on the Dulla's formalism and the classical method is made. The objective is to exhibit the dependence of the parameters on subcriticality level and perturbation. Two different slab type systems were considered: thermal one and fast one, both with homogeneous media. One group diffusion model was used for the fast reactor, and for the thermal system, two groups diffusion model, considering, in both case, only one precursor's family. The solutions were obtained using the expansion method. Also, descriptions of the main experimental methods of measurements of the kinetic parameters are presented in order to put a question about the compatibility of these methods in subcritical region. (author)
Yue, Ping; Zhang, Qiang; Wang, Runyuan; Li, Yaohui; Wang, Sheng
2015-09-01
A deep understanding of turbulence structure is important for investigating the characteristics of the atmospheric boundary layer, especially over heterogeneous terrain. In the present study, turbulence intensity and turbulent kinetic energy (TKE) parameters are analyzed for different conditions with respect to stability, wind direction and wind speed over a valley region of the Loess Plateau of China during December 2003 and January 2004. The purpose of the study is to examine whether the observed turbulence intensity and TKE parameters satisfy Monin-Obukhov similarity theory (MOST), and analyze the wind shear effect on, and thermal buoyancy function of, the TKE, despite the terrain heterogeneity. The results demonstrate that the normalized intensity of turbulence follows MOST for all stability in the horizontal and vertical directions, as well as the normalized TKE in the horizontal direction. The shear effect of the wind speed in the Loess Plateau region is strong in winter and could enhance turbulence for all stability conditions. During daytime, the buoyancy and shear effect together constitute the generation of TKE under unstable conditions. At night, the contribution of buoyancy to TKE is relatively small, and mechanical shearing is the main production form of turbulence.
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Z. R. Yelebe
2014-03-01
Full Text Available This paper addresses the challenge of estimating various kinetic parameters for the design of an optimized enzyme catalysed batch bioreactor of high efficiency and yield. Mathematical models were developed to describe the batch reaction time in relation to the substrate, enzyme and product concentration. The results obtained from the plots generated were: 35.50gmol/l.hr for the velocity of reaction of the enzymes (Vmax, 0.10049hr-1 for the maximum specific growth rate (µmax 826.45gmol/l for the Michaelis-Menten constant (Km, 0.005402577 for maintenance coefficient (Ms, 10.104kgCx/kgCs for yield of cell weight per unit weight of substrate (Ycx/CS, 0.05436kgCp/kgCs for yield of product weight per unit weight of substrate utilized (Ycp/CS and 0.01416 for endogenous decay coefficient (Kd for the design of the batch biochemical reactor. Hence, they are useful parameters for predicting the most appropriate batch reaction conditions and the efficiency of the bioreactor. The mathematical model predictions showed that it can be considered as a good complimentary tool to real system since the simulation results of the mathematical model agrees with experimental data reported in literature.
Bayesian inference of biochemical kinetic parameters using the linear noise approximation
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Finkenstädt Bärbel
2009-10-01
Full Text Available Abstract Background Fluorescent and luminescent gene reporters allow us to dynamically quantify changes in molecular species concentration over time on the single cell level. The mathematical modeling of their interaction through multivariate dynamical models requires the deveopment of effective statistical methods to calibrate such models against available data. Given the prevalence of stochasticity and noise in biochemical systems inference for stochastic models is of special interest. In this paper we present a simple and computationally efficient algorithm for the estimation of biochemical kinetic parameters from gene reporter data. Results We use the linear noise approximation to model biochemical reactions through a stochastic dynamic model which essentially approximates a diffusion model by an ordinary differential equation model with an appropriately defined noise process. An explicit formula for the likelihood function can be derived allowing for computationally efficient parameter estimation. The proposed algorithm is embedded in a Bayesian framework and inference is performed using Markov chain Monte Carlo. Conclusion The major advantage of the method is that in contrast to the more established diffusion approximation based methods the computationally costly methods of data augmentation are not necessary. Our approach also allows for unobserved variables and measurement error. The application of the method to both simulated and experimental data shows that the proposed methodology provides a useful alternative to diffusion approximation based methods.
Re-examination of safety parameters using kinetic theory of nano-granular flows
International Nuclear Information System (INIS)
The origin of the kinetic theory of granular flow was originally credited to Bagnold. By using a very primitive expression of the particle collision frequency, he derived an expression for the repulsive pressure of the particles in uniform shear flows. His repulsive pressure was proportional to the square of the velocity gradient and the particle diameter and directly proportional to the particle density. This theory was later extended by Savage and Gidaspow. Such theories provide insight on the dependence of the viscosity, and various moduli (elastic, non elastic, viscous...) in terms of the granular temperature and the associated shear-rates. Until recently, such parameters were difficult to measure because of the lack of specifically designed equipment. This challenge was successfully taken up and resolved by P. Marchal of ENSIC who designed a new rheometer for powders. This equipment can put in evidence the importance of the granular temperature on the elastic and viscous behaviors of the granular flows. Such rheological behavior is important in risk analysis for nanopowders, because as the nanopowder may be subjected to process shear rates and stresses, its structural and topological changes, in terms of the transformation of agglomerates into primary nanoparticles, have strong impacts on emission factors of nanosized particles that can be released in the environment or into a workplace from such dense-phase nanopowder processes. Such transformation can be analyzed by studying the nano-granular rheological signature of the system. Such risk assessment approach using these new fundamental rheological safety parameters is described in this paper.
Feitkenhauer, H; Schnicke, S; Müller, R; Märkl, H
2001-12-01
Phenolic compounds are pollutants in many wastewaters, e.g. from crude oil refineries, coal gasification plants or olive oil mills. Phenol removal is a key process for the biodegradation of pollutants at high temperatures because even low concentrations of phenol can inhibit microorganisms severely. Bacillus thermoleovorans sp. A2, a recently isolated thermophilic strain (temperature optimum 65 degrees C), was investigated for its capacity to degrade phenol. The experiments revealed that growth rates were about four times higher than those of mesophilic microorganisms such as Pseudomonas putida. Very high specific growth rates of 2.8 h(-1) were measured at phenol concentrations of 15 mg/l, while at phenol concentrations of 100-500 mg/l growth rates were still in the range of 1 h(-1). The growth kinetics of the thermophilic Bacillus thermoleovorans sp. A2 on phenol as sole carbon and energy source can be described using a three-parameter model developed in enzyme kinetics. The yield coefficient Yx/s of 0.8-1 g cell dry weight/g phenol was considerably higher than cell yields of mesophilic bacteria (Yx/s 0.40-0.52 g cell dry weight/g phenol). The highest growth rate was found at pH 6. Bacillus thermoleovorans sp. A2 was found to be insensitive to hydrodynamic shear stress in stirred bioreactor experiments (despite possible membrane damage caused by phenol) and flourished at an ionic strength of the medium of 0.25(-1) mol/l (equivalent to about 15-60 g NaCl/l). These exceptional properties make Bacillus thermoleovorans sp. A2 an excellent candidate for technical applications.
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Zaanoun, I.
2014-09-01
Full Text Available The present study investigated the Kinetic parameter determination of edible argan oil (coldpressed from roasted argan kernels and cosmetic argan oil (cold-pressed from unroasted argan kernels under the Rancimat test conditions. The physicochemical parameters of edible and cosmetic argan oil immediately after preparation and after accelerated oxidation test Rancimat at different temperatures 90 °C, 100 °C, 110 °C, 120 °C, 130 °C and 140 °C were determined and compared. The natural logarithms of the kinetic rate constant (kvalue varied linearly with respect to temperature. An increasing rate of oxidation could be observed as temperature increased. On the basis of the Arrhenius equation and the activated complex theory, frequency factors A, activation energies Ea, Q10 numbers, activation enthalpies ΔH, and activation entropies ΔS for oxidative stability of the vegetable oils were calculated. The accelerated oxidation and Kinetic parameters have shown that edible argan oil can be stored much better than cosmetic oil.En presente estudio se determinaron los parámetros cinéticosde aceites de argán comestible (prensado en frío a partir de granos tostados de argán y cosmético (prensado en frío a partir de granos de argán sin tostar bajo las condiciones del método Rancimat. Se determinó y comparó los parámetros físico-químicos de aceites de argán comestible y cosmético inmediatamente después de la preparación y después de la oxidación acelerada mediante Rancimat a temperaturas de 90 °C, 100 °C, 110 °C, 120 °C, 130 °C y 140 °C Los logaritmos naturales de la constante de velocidad cinética (valor k variaron linealmente con respecto a la temperatura. Se pudo observar un valor creciente de la oxidación conel aumento de la temperatura. Se calculó para la estabilidad oxidativa de los aceites vegetalesy sobre la base de la ecuación de Arrhenius y la teoría del complejo activado, la frecuencia de los factores A, energ
Computer controlled automated assay for comprehensive studies of enzyme kinetic parameters.
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Felix Bonowski
Full Text Available Stability and biological activity of proteins is highly dependent on their physicochemical environment. The development of realistic models of biological systems necessitates quantitative information on the response to changes of external conditions like pH, salinity and concentrations of substrates and allosteric modulators. Changes in just a few variable parameters rapidly lead to large numbers of experimental conditions, which go beyond the experimental capacity of most research groups. We implemented a computer-aided experimenting framework ("robot lab assistant" that allows us to parameterize abstract, human-readable descriptions of micro-plate based experiments with variable parameters and execute them on a conventional 8 channel liquid handling robot fitted with a sensitive plate reader. A set of newly developed R-packages translates the instructions into machine commands, executes them, collects the data and processes it without user-interaction. By combining script-driven experimental planning, execution and data-analysis, our system can react to experimental outcomes autonomously, allowing outcome-based iterative experimental strategies. The framework was applied in a response-surface model based iterative optimization of buffer conditions and investigation of substrate, allosteric effector, pH and salt dependent activity profiles of pyruvate kinase (PYK. A diprotic model of enzyme kinetics was used to model the combined effects of changing pH and substrate concentrations. The 8 parameters of the model could be estimated from a single two-hour experiment using nonlinear least-squares regression. The model with the estimated parameters successfully predicted pH and PEP dependence of initial reaction rates, while the PEP concentration dependent shift of optimal pH could only be reproduced with a set of manually tweaked parameters. Differences between model-predictions and experimental observations at low pH suggest additional protonation
Kinetic parameters for nutrient enhanced crude oil biodegradation in intertidal marine sediments
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Arvind K Singh
2014-04-01
Full Text Available Availability of inorganic nutrients, particularly N and P, is often a primary control on crude oil hydrocarbon degradation in marine systems. Nevertheless, there is a paucity of information on fundamental kinetic parameters for nutrient enhanced crude oil biodegradation that can be used to model the fate of crude oil in bioremediation programmes that use inorganic nutrient addition to stimulate oil biodegradation. Here we report fundamental kinetic parameters (Ks and qmax for nitrate- and phosphate-stimulated crude oil biodegradation under nutrient limited conditions and with respect to crude oil, under conditions where N&P are not limiting. Crude oil degradation was limited by both N&P availability. When N was added alone maximum rates of CO2 production measured were 3.94±0.46 µmol CO2 /g wet sediment/day. However when the same levels of N were added in the presence of 0.5% P w/w of oil (1.6 μmol P/g wet sediment maximum rates of measured CO2 production more than doubled (11.52±0.72 µmol CO2 /g wet sediment/day. Ks and qmax estimates for N (in the form of sodium nitrate when P was not limiting were 1.57±0.56 µmol/g wet sediment and 10.57±0.63 µmol CO2 /g wet sediment/day respectively. The corresponding values for P were 80 nmol/g wet sediment and 8.76±1.15 µmol CO2 /g wet sediment/day. The qmax values with respect to N and P were not significantly different (P< 0.05. Analysis of bacterial 16S rRNA genes indicated that Alcanivorax spp. were selected in these marine sediments with increasing inorganic nutrient concentration, whereas Cycloclasticus spp. were more prevalent at lower inorganic nutrient concentrations. These data suggest that simple empirical estimates of the proportion of nutrients added relative to crude oil concentrations may not be sufficient to guarantee successful crude oil bioremediation in oxic beach sediments. The data we present also help define the maximum rates and hence timescales required for bioremediation
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Ruth Alfaro-Cuevas-Villanueva
2014-01-01
Full Text Available The sorption of cadmium (Cd and lead (Pb by calcium alginate beads (CAB from aqueous solutions in batch systems was investigated. The kinetic and thermodynamic parameters, as well as the sorption capacities of CAB in each system at different temperatures, were evaluated. The rate of sorption for both metals was rapid in the first 10 minutes and reached a maximum in 50 minutes. Sorption kinetic data were fitted to Lagergren, pseudo-second-order and Elovich models and it was found that the second-order kinetic model describes these data for the two metals; comparing kinetic parameters for Cd and Pb sorption a higher kinetic rate (K2 for Pb was observed, indicating that the interaction between lead cations and alginate beads was faster than for cadmium. Similarly, isotherm data were fitted to different models reported in literature and it was found that the Langmuir-Freundlich (L-F and Dubinin-Radushkevich (D-R models describe the isotherms in all cases. CAB sorption capacity for cadmium was 27.4 mg/g and 150.4 mg/g for lead, at 25°C. Sorption capacities of Cd and Pb increase as temperature rises. According to the thermodynamic parameters, the cadmium and lead adsorption process was spontaneous and endothermic. It was also found that pH has an important effect on the adsorption of these metals by CAB, as more were removed at pH values between 6 and 7.
Efficient uranium(VI) biosorption on grapefruit peel. Kinetic study and thermodynamic parameters
International Nuclear Information System (INIS)
The uranium(VI) biosorption by grapefruit peel was studied from aqueous solutions. Batch experiments was conducted to evaluate the effect of contact time, initial uranium(VI) concentration, initial pH, adsorbent dose, salt concentration and temperature. The equilibrium process was well described by the Langmuir, Redlich-Peterson and Koble-Corrigan isotherm models, with maximum sorption capacity of 140.79 mg g-1 at 298 K. The pseudo second order model and Elovish model adequately describe the kinetic data in comparison to the pseudo first order model and the process involving rate-controlling step is much complex involving both boundary layer and intra-particle diffusion processes. The effective diffusion parameter Di and Df values were estimated at different initial concentration and the average values were determined to be 1.167 x 10-7 and 4.078 x 10-8 cm2 s-1. Thermodynamic parameters showed that the biosorption of uranium(VI) onto grapefruit peel biomass was feasible, spontaneous and endothermic under studied conditions. The physical and chemical properties of the adsorbent were determined by SEM, TG-DSC, XRD and elemental analysis and the nature of biomass-uranium (VI) interactions was evaluated by FTIR analysis, which showed the participation of COOH, OH and NH2 groups in the biosorption process. Adsorbents could be regenerated using 0.05 mol L-1 HCl solution at least three cycles, with up to 80% recovery. Thus, the biomass used in this work proved to be effective materials for the treatment of uranium (VI) bearing aqueous solutions. (author)
Lizama, H M; Suzuki, I
1989-11-01
Rate equations and kinetic parameters were obtained for various reactions involved in the bacterial oxidation of pyrite. The rate constants were 3.5 muM Fe per min per FeS(2) percent pulp density for the spontaneous pyrite dissolution, 10 muM Fe per min per mM Fe for the indirect leaching with Fe, 90 muM O(2) per min per mg of wet cells per ml for the Thiobacillus ferrooxidans oxidation of washed pyrite, and 250 muM O(2) per min per mg of wet cells per ml for the T. ferrooxidans oxidation of unwashed pyrite. The K(m) values for pyrite concentration were similar and were 1.9, 2.5, and 2.75% pulp density for indirect leaching, washed pyrite oxidation by T. ferrooxidans, and unwashed pyrite oxidation by T. ferrooxidans, respectively. The last reaction was competitively inhibited by increasing concentrations of cells, with a K(i) value of 0.13 mg of wet cells per ml. T. ferrooxidans cells also increased the rate of Fe production from Fe plus pyrite. PMID:16348054
Calculation of kinetic parameters for mixed TRIGA cores with Monte Carlo
Energy Technology Data Exchange (ETDEWEB)
Snoj, Luka, E-mail: luka.snoj@ijs.s [Reactor Physics Division, Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); Kavcic, Andrej [Nuclear Training Centre, Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); Zerovnik, Gasper; Ravnik, Matjaz [Reactor Physics Division, Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia)
2010-02-15
Modern Monte Carlo transport codes in combination with fast computer clusters enable very accurate calculations of the most important reactor kinetic parameters. Such are the effective delayed neutron fraction, beta{sub eff}, and mean neutron generation time, LAMBDA. We calculate beta{sub eff} and LAMBDA for various realistic and hypothetical annular TRIGA Mark II cores with different types and amount of fuel. It is observed that the effective delayed neutron fraction strongly depends on the number of fuel elements in the core or on the core size. beta{sub eff} varies for 12 wt.% uranium standard fuel with 20% enrichment from 0.0080 for a small core (43 fuel rods) to 0.0070 for a full core (90 fuel rods). It is found that calculated value of beta{sub eff} strongly depends also on the nuclear data set used in calculations. The prompt neutron lifetime mainly depends on the amount (due to either content or enrichment) of {sup 235}U in the fuel as it is approximately inversely proportional to the average absorption cross-section. It varies from 28 mus for 30 wt.% uranium content fuelled core to 48 mus for 8.5 wt.% uranium content LEU fuelled core. Description of the calculation method and detailed results are presented in the paper.
Ghosh, Abir; Bandyopadhyay, Dipankar; Sharma, Ashutosh
2016-09-01
Detachment of a surface from a viscoelastic layer, such as a film of glue, engenders bridges between the surfaces until separation. Such surface instabilities arising during contact and detachment of viscoelastic films with rigid contactors have been theoretically explored by linear stability analysis and nonlinear simulations. The contact instabilities of viscoelastic materials are found to manifest in either a 'critical' or a 'dominant' mode in which the former is preferred when the contactor is slowly brought near the film while the latter manifests when the film is 'hard-pressed' against it. The nonlinear analysis considers the movement of contactor during adhesion-debonding cycle, which uncovers that the kinetic parameters can overshadow the thermodynamically predicted area of contact, average force for pull-off, energy of contactor-film separation, and pathways of debonding. Three distinct pathways of debonding - peeling, catastrophic column collapse, and column coalescence, are found to manifest with the variation in the ratio of the elastic to viscous compliances of the viscoelastic film. The study also reveals that in the dominant mode of instability, a smaller length scale with a larger area contact between the contactor and film can develop patterns having aspect ratio ∼10 times larger than the same obtained from elastic film. PMID:27254253
A study of line widths and kinetic parameters of ions in the solar corona
Zhao, G Q; Wang, C B
2014-01-01
Solar extreme-ultraviolet (EUV) lines emitted by highly charged ions have been extensively studied to discuss the issue of coronal heating and solar wind acceleration. Based on observations of the polar corona by the SUMER/SOHO spectrometer, this paper investigates the relation between the line widths and kinetic parameters of ions. It is shown that there exists a strongly linear correlation between two variables $(\\sigma/\\lambda)^2$ and $M^{-1}$, where $\\sigma$, $\\lambda$ and $M$ are the half-width of the observed line profile at $1/\\sqrt{e}$, the wavelength and the ion mass, respectively. The Pearson product-moment correlation coefficients exceed 0.9. This finding tends to suggest that the ions from a given height of polar corona have a common temperature and a common non-thermal velocity in terms of existing equation. The temperature and non-thermal velocity are obtained by linear least-square fit. The temperature is around $2.8$ MK at heights of 57$''$ and 102$''$. The non-thermal velocity is typical 21.6...
Trapani, Daniele Di; Mannina, Giorgio; Torregrossa, Michele; Viviani, Gaspare
2010-01-01
Over the last decade new technologies are emerging even more for wastewater treatment. Among the new technologies, a recent possible solution regards Moving Bed Biofilm Reactors (MBBRs) that represent an effective alternative to conventional processes. More specifically such systems consist in the introduction of plastic elements inside the aerobic reactor as carrier material for the growth of attached biomass. Recently, one of the mostly used alternatives is to couple the Moving Bed Biofilm Reactor (MBBR) process with the conventional activated sludge process, and the resulting process is usually called HMBBR (Hybrid MBBR). In the MBBR process the biofilm grows attached on small plastic elements that are kept in constant motion throughout the entire volume of the reactor. Indeed, in such a system, a competition between the two biomasses, suspended and attached, can arise for the availability of the substrates, leading, as a consequence, to a modification in the biokinetic parameters of the two biomasses, compared to that of a pure suspended or attached biomass process. This paper presents the first results of a study aimed at estimating the kinetic heterotrophic constants in a HMBBR pilot plant using respirometric techniques. The pilot plant was built at the Acqua dei Corsari (Palermo) wastewater treatment plant and consisted of two parallel lines realized in a pre-anoxic scheme, in one of which the carrier material was added to the aerobic reactor with a filling ratio of 30%. PMID:20371934
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Claudio Milton Montenegro Campos
2014-10-01
Full Text Available This study evaluated the treatment of wastewater from coffee wet processing (WCWP in an anaerobic treatment system at a laboratory scale. The system included an acidification/equalization tank (AET, a heat exchanger, an Upflow Anaerobic Sludge Blanket Reactor (UASB, a gas equalization device and a gas meter. The minimum and maximum flow rates and volumetric organic loadings rate (VOLR were 0.004 to 0.037 m 3 d -1 and 0.14 to 20.29 kgCOD m -3 d -1 , respectively. The kinetic parameters measured during the anaerobic biodegradation of the WCWP, with a minimal concentration of phenolic compounds of 50 mg L - ¹, were: Y = 0.37 mgTVS (mgCODremoved -1 , Kd = 0.0075 d-1 , Ks = 1.504mg L -1 , μmax = 0.2 d -1 . The profile of sludge in the reactor showed total solids (TS values from 22,296 to 55,895 mg L -1 and TVS 11,853 to 41,509 mg L -1 , demonstrating a gradual increase of biomass in the reactor during the treatment, even in the presence of phenolic compounds in the concentration already mentioned.
Kinetic parameters and tissue distribution of 5-oxo-L-prolinase determined by a fluorimetric assay.
Weber, P; Jäger, M; Bangsow, T; Knell, G; Piechaczek, K; Koch, J; Wolf, S
1999-01-13
5-Oxo-L-prolinase (5-OPase) catalyses the hydrolysis of 5-oxo-L-proline to glutamate with concomitant stoichiometric cleavage of ATP to ADP, a reaction which is known to be part of the gamma-glutamyl cycle-an interrelated series of reactions involved in the synthesis and metabolism of glutathione. As recent studies indicate, this cyclic pathway plays a crucial role in the regulation of amino acid transport. Apparently, the intermediate product 5-oxo-L-proline functions as a second messenger molecule that upregulates the activity of certain amino acid transport systems. Thus, the degradation of 5-oxo-L-proline by 5-OPase leads to the downregulation of this stimulus. In this study, a new sensitive fluorimetric assay for 5-OPase activity was established which is based on the derivatization of glutamate with o-phthaldialdehyde in the presence of thiols and subsequent separation of the products by HPLC. The method is suitable for the screening of chromatography fractions as well as for the determination of the kinetic parameters Km and Vmax of purified 5-OPase. Additionally, it can be used for the measurement of enzyme activity in crude cell extracts and evaluation of tissue distribution.
Institute of Scientific and Technical Information of China (English)
Qinghai Hu; Zhongjin Xiao; Xinmei Xiong; Gongming Zhou; Xiaohong Guan
2015-01-01
Although surface complexation models have been widely used to describe the adsorption of heavy metals,few studies have verified the feasibility of modeling the adsorption kinetics,edge,and isotherm data with one pH-independent parameter.A close inspection of the derivation process of Langrnuir isotherm revealed that the equilibrium constant derived from the Langmuir kinetic model,Ks-kinetic,is theoretically equivalent to the adsorption constant in Langrnuir isotherm,Ks-Langmuir.The modified Langmuir kinetic model (MLK model) and modified Langmuir isotherm model (MLI model) incorporating pH factor were developed.The MLK model was employed to simulate the adsorption kinetics of Cu(Ⅱ),Co(Ⅱ),Cd(Ⅱ),Zn(Ⅱ) and Ni(Ⅱ) on MnO2 at pH 3.2 or 3.3 to get the values of Ks-kinetic.The adsorption edges of heavy metals could be modeled with the modified metal partitioning model (MMP model),and the values of Ks-Langrnuir were obtained.The values of Ks-kinetic and Ks-Langrnuir are very close to each other,validating that the constants obtained by these two methods are basically the same.The MMP model with Ks-kinetic constants could predict the adsorption edges of heavy metals on MnO2 very well at different adsorbent/adsorbate concentrations.Moreover,the adsorption isotherms of heavy metals on MnO2 at various pH levels could be predicted reasonably well by the MLI model with the Ks-kinetic constants.
Fonseca, Rodney W.; Pfefferkorn, Lisa L.; Holcombe, James A.
1994-12-01
Three of the methods available for the determination of kinetic parameters for atom formation in ETAAS were compared. In the approach of mcnally and holcombe [ Anal. Chem. 59, 1015 (1987)], Arrhenius-type plots are used to extract activation energy values while an approximation of the order of release is obtained by studying the alignment of the absorption maxima at increasing analyte concentrations. In the method of rojas and olivares [ Spectrochim. Acta47B, 387 (1992)], plots are prepared for different orders of release, with the correct order yielding a longer linear region from whose slope the activation energy is calculated. The method of yan et al. [ Spectrochim. Acta48B, 605 (1993)] uses a single absorption profile for the calculations. Activation energy and the order of release are obtained from the slope and intercept, respectively, on their graph. All three methods assume linear heating rate, constant activation energies, and furnace isothermality. The methods were tested with the same experimental data sets for Cu, Au and Ni using a spatially isothermal cuvette. Since intensive mathematical treatments commonly have deleterious effects on the uncertainty of the final result, the methods were compared using both the original data and a smoothed version of it. In general, the three methods yielded comparable results for the metals studied. However, choosing the most linear plot to determine the correct order of release when using Rojas and Olivares' method was sometimes subjective, and McNally and Holcombe's method provided only estimates for the orders of release that were neither zero nor unity.
International Nuclear Information System (INIS)
The effects of using different low enriched uranium fuels, having same uranium density, on the kinetic parameters of a material test research reactor were studied. For this purpose, the original aluminide fuel (UAlx-Al) containing 4.40 gU/cm3 of an MTR was replaced with silicide (U3Si-Al and U3Si2-Al) and oxide (U3O8-Al) dispersion fuels having the same uranium density as of the original fuel. Simulations were carried out to calculate prompt neutron generation time, effective delayed-neutron fraction, core excess reactivity and neutron flux spectrum. Nuclear reactor analysis codes including WIMS-D4 and CITATION were used to carry out these calculations. It was observed that both the silicide fuels had the same prompt neutron generation time 0.02% more than that of the original aluminide fuel, while the oxide fuel had a prompt neutron generation time 0.05% less than that of the original aluminide fuel. The effective delayed-neutron fraction decreased for all the fuels; the decrease was maximum at 0.06% for U3Si2-Al followed by 0.03% for U3Si-Al, and 0.01% for U3O8-Al fuel. The U3O8-Al fueled reactor gave the maximum ρexcess at BOL which was 21.67% more than the original fuel followed by U3Si-Al which was 2.55% more, while that of U3Si2-Al was 2.50% more than the original UAlx-Al fuel. The neutron flux of all the fuels was more thermalized, than in the original fuel, in the active fuel region of the core. The thermalization was maximum for U3O8-Al followed by U3Si-Al and then U3Si2-Al fuel.
Cui, Yunfeng; Bai, Jing
2005-01-01
Liver kinetic study of [18F]2-fluoro-2-deoxy-D-glucose (FDG) metabolism in human body is an important tool for functional modeling and glucose metabolic rate estimation. In general, the arterial blood time-activity curve (TAC) and the tissue TAC are required as the input and output functions for the kinetic model. For liver study, however, the arterial-input may be not consistent with the actual model input because the liver has a dual blood supply from the hepatic artery (HA) and the portal vein (PV) to the liver. In this study, the result of model parameter estimation using dual-input function is compared with that using arterial-input function. First, a dynamic positron emission tomography (PET) experiment is performed after injection of FDG into the human body. The TACs of aortic blood, PV blood, and five regions of interest (ROIs) in liver are obtained from the PET image. Then, the dual-input curve is generated by calculating weighted sum of both the arterial and PV input curves. Finally, the five liver ROIs' kinetic parameters are estimated with arterial-input and dual-input functions respectively. The results indicate that the two methods provide different parameter estimations and the dual-input function may lead to more accurate parameter estimation.
Institute of Scientific and Technical Information of China (English)
LI Xianqing; DONG Peng; XIAO Xianming; MI Jingkui; TANG Yongchun; XIAO Zhongyao; LIU Dehan; SHEN Jiagui; YANG Yunfeng; WANG Yan
2008-01-01
In a thermal simulation experiment of gold tubes of closed-system, calculating with the KINETICS and GOR-ISOTOPE KINETICS software, kinetic parameters of gas generation and methane carbon isotopic fractionation from Triassic-Jurassic hydrocarbon source rocks in the Kuqa depression of Tarim Basin are obtained. The activation energies of methane generated from Jurassic coal, Jurassic mudstone and Triassic mudstone in the Kuqa Depression are 197-268 kJ/mol, 180-260 kJ/mol and 214-289 kJ/mol, respectively, and their frequency factors are 5.265×1013s-1, 9.761×1011 s-1 and 2.270×1014 s-1. This reflects their differences of hydrocarbon generation behaviors. The kinetic parameters of methane carbon isotopic fractionation are also different in Jurassic coal, Jurassic mudstone and Triassic mudstone, whose average activation energies are 228 kJ/mol, 205 kJ/mol and 231 kJ/mol, respectively. Combined with the geological background, the origin of natural gas in the Yinan-2 gas pool is discussed, and an accumulation model of natural gas is thus established. The Yinan-2 gas is primarily derived from Jurassic coal-bearing source rocks in the Yangxia Sag. Main gas accumulation time is 5-0 Ma and the corresponding Ro is in the range from 1.25%-1.95%. The loss rate of natural gas is 25%-30%.
Schiemann, Martin; Geier, Manfred; Shaddix, Christopher R.; Vorobiev, Nikita; Scherer, Viktor
2014-07-01
In this study, the char burnout characteristics of two German coals (a lignite and a high-volatile bituminous coal) were investigated using two different experimental configurations and optical techniques in two distinct laboratories for measurement of temperature and size of burning particles. The optical diagnostic hardware is quite different in the two systems, but both perform two-color pyrometry and optical sizing measurements on individual particles burning in isolation from each other in high-temperature laminar flows to characterize the char consumption kinetics. The performance of the specialized systems is compared for two different combustion atmospheres (with 6.6 and 12 vol.% O2) and gas temperatures between 1700 and 1800 K. The measured particle temperatures and diameters are converted to char burning rate parameters for several residence times during the course of the particles' burnout. The results confirm that comparable results are obtained with the two configurations, although higher levels of variability in the measured data were observed in the imaging-based pyrometer setup. Corresponding uncertainties in kinetics parameters were larger, and appear to be more sensitive to systematic measurement errors when lower oxygen contents are used in the experiments. Consequently, burnout experiments in environments with sufficiently high O2 contents may be used to measure reliable char burning kinetics rates. Based on simulation results for the two coals, O2 concentrations in the range 10%-30% are recommended for kinetic rate measurements on 100 μm particles.
Fagton de Mattos Negrão; Anderson de Moura Zanine; Luciano da Silva Cabral; Alexandre Lima de Souza; Guilherme Ribeiro Alves; Daniele de Jesus Ferreira; Carlos Clayton Oliveira Dantas; Aline Lehmkuhl
2014-01-01
This experiment was conducted to evaluate the protein and carbohydrate fractions, and to estimate the in situ rumen degradation kinetic parameters of Brachiaria decumbens grass silage with inclusion of rice bran. Five rice bran inclusion levels were tested: 0, 10, 20, 30 and 40% of the natural matter, distributed into a completely randomized design with five replications. The brachiaria grass was obtained at 60 days of regrowth by cutting the forage at 10 cm from the soil and ensiling it in 1...
DEFF Research Database (Denmark)
Sayar, N.A.; Chen, B.H.; Lye, G.J.;
2009-01-01
In this paper we have used a proposed mathematical model, describing the carbon-carbon bond format ion reaction between beta-hydroxypyruvate and glycolaldehyde to synthesise L-erythrulose, catalysed by the enzyme transketolase, for the analysis of the sensitivity of the process to its kinetic par....... (C) 2009 Elsevier B.V. All rights reserved....
How is the Monoclonal Antibodies Kinetic Affected by Changes of Their Physical Parameters?
Delgado-Correal, Camilo; Lizarazo-Pérez, Heidy Alexandra
2010-01-01
The study of monoclonal antibodies (MAb) is a field of great interest to science medicine, for example, anti-TNF agents (infliximab and adalimumab) represent an important tool for the management of autoimmune and inflammatory disorders. In this work we focus on the physical description of the transport kinetics of MAb in a fluid with laminar flow and parabolic profile. To simulate the kinetics of the MAb, standard equations were solved numerically (using The Verlet algorithm) to calculate the motion of a particle with a spherically symmetric inside of parabolic laminar flow, in order to find the time evolution of the antibody velocity in blood plasma in function of the increase of the radius, mass and density of the MAb, and the fluid pressure in blood vessels. In the case of we fixed the value of the antibody density, their kinetics increased when the pressure in the vessels increased. When we fixed the pressure in the vessels we found: if we reduce the antibody radius their kinetics increased, and when we i...
Kinetic parameters for plasma β-endorphin in lean and obese Zucker rats
International Nuclear Information System (INIS)
To determine plasma clearance kinetics for β-endorphin (BE) by empirical compartmental analysis, a bolus of radioactive labeled 125I-BE was rapidly injected into a carotid artery catheter of unanesthetized lean (L) and obese (O) Zucker rats. The plasma disappearance of 125I was followed over a 3-h period. A 3-component exponential equation provided the best fit for plasma data. Plasma transit times were very short (10 s); however, plasma fractional catabolic rate was much slower. Plasma mean residence time was similar for both groups (50 min) as was recycle time (1.3 min). These data suggest that BE plasma disappearance kinetics are similar in L and O rats
International Nuclear Information System (INIS)
The induction kinetics of micronuclei polychromated eritrocites (EPC-MN) which is produced by busulfan and compared with that produced by the ionizing radiation, allows to make inferences over the pharmacokinetics and pharmacodynamics of busulfan. Observing two induction mechanisms of MN, this one early at low doses and other later at high doses, this last is presented to a critical dose being very sheer and associated with an increase of the cytotoxicity. The data suggest the transformation or dependence between these two types of leisures, which to determine the narrow therapeutical margin of busulfan. The pharmacokinetic parameters determined in the early mechanisms kinetics indicate a latency period, a time of effective activity and of half life 5.7, 5.2 and 2.6 h respectively. (Author)
A comparison of region-based and pixel-based CEUS kinetics parameters in the assessment of arthritis
Grisan, E.; Raffeiner, B.; Coran, A.; Rizzo, G.; Ciprian, L.; Stramare, R.
2014-03-01
Inflammatory rheumatic diseases are leading causes of disability and constitute a frequent medical disorder, leading to inability to work, high comorbidity and increased mortality. The gold-standard for diagnosing and differentiating arthritis is based on patient conditions and radiographic findings, as joint erosions or decalcification. However, early signs of arthritis are joint effusion, hypervascularization and synovial hypertrophy. In particular, vascularization has been shown to correlate with arthritis' destructive behavior, more than clinical assessment. Contrast Enhanced Ultrasound (CEUS) examination of the small joints is emerging as a sensitive tool for assessing vascularization and disease activity. The evaluation of perfusion pattern rely on subjective semi-quantitative scales, that are able to capture the macroscopic degree of vascularization, but are unable to detect the subtler differences in kinetics perfusion parameters that might lead to a deeper understanding of disease progression and a better management of patients. Quantitative assessment is mostly performed by means of the Qontrast software package, that requires the user to define a region of interest, whose mean intensity curve is fitted with an exponential function. We show that using a more physiologically motivated perfusion curve, and by estimating the kinetics parameters separately pixel per pixel, the quantitative information gathered is able to differentiate more effectively different perfusion patterns. In particular, we will show that a pixel-based analysis is able to provide significant markers differentiating rheumatoid arthritis from simil-rheumatoid psoriatic arthritis, that have non-significant differences in clinical evaluation (DAS28), serological markers, or region-based parameters.
Directory of Open Access Journals (Sweden)
Şeyda Taşar
2015-12-01
Full Text Available The pyrolysis process, which is applied for the aim of producing energy and raw materials which are implemented for the chemical industry from biomass sources, is a thermal conversion process. Determination of the pyrolysis kinetic parameters are important In order to suitable equipment and process design. In this target, in the study the pyrolysis of peanut shells was conducted in a muffle furnace at static atmosphere with temperatures ranging from 300-700 °C. The effects of various parameters on the rate of thermal decomposition rate and the solid yield were determined. The parameters of interest were temperature 300-700 °C, particle size 4-50 mesh, pelletizing, and pelletizing pressure 1.103-5.103 kgf/cm2. Regression coefficients for the total decomposition step were obtained using the thermographs were obtained as a result of the pyrolysis of the peanut shells, and 20 different theoretical model equations that represented the degradation by the Coast-Redfern method. According to regression coefficients of the theoretical model equations, we determined the kinetic model that best represented the degradation. Using this model to represent the degradation, the activation energy (Ea and Arhenius frequency factor ln(A for the total reaction were calculated to be 38.245 kJ/mol and 8.124, respectively.
Model description and kinetic parameter analysis of MTBE biodegradation in a packed bed reactor
DEFF Research Database (Denmark)
Waul, Christopher Kevin; Arvin, Erik; Schmidt, Jens Ejbye
2008-01-01
A dynamic modeling approach was used to estimate in-situ model parameters, which describe the degradation of methyl tert-butyl ether (MTBE) in a laboratory packed bed reactor. The measured dynamic response of MTBE pulses injected at the reactor's inlet was analyzed by least squares and parameter...
Kinetic parameters of oscillating reaction of amino acid-BrO-3-Mn2+-H2SO4-acetone system
Institute of Scientific and Technical Information of China (English)
LI Zongxiao; YUAN Chunlan; NIE Fei
2005-01-01
The oscillating behavior of thirteen amino acids [leucine (Leu), threonine (Thr), arginine (Arg), lysine (Lys), histidine (His), alanine (Ala), glutamine (Glu), glycine (Gly), methionine (Met), cystine (Cys), tryptophan (Trp), serine (Ser) and tyrosine (Tyr)] in amino acid--Mn2+-H2SO4-acetone system is studied by using a potentiometric determination. With the help of the oscillatory induction period and oscillation period obtained by the oscillating wave, and Arrhenius equation, the kinetic parameters [the apparent activation energy (E) and pre-exponential constant (A)] and rate constant (k) of the above-mentioned oscillating reaction are estimated.
Directory of Open Access Journals (Sweden)
Enitan S. Balogun
2012-04-01
Full Text Available Biosorption and bioaccumulation of Lead ions (Pb(II by Trichoderma longibrachiatum were investigated in a batch system. The effects of some important parameters such as pH, initial metal concentration, temperature and inoculum concerntration on biosorption capacity were also studied. The maximum biosorption capacity of Trichoderma longibrachiatum was at 25 ppm of lead, showed 100 % removal at pH 7 and 25 oC after fifteen days. Biosorption equilibrium was established in 150 minutes. The process fitted well into pseudo second order kinetic model and was best explained by Langmuir isotherm.
Directory of Open Access Journals (Sweden)
Marzieh Aghababaie
2014-09-01
Results: Second order model for Xmax, μmax, P and K was significant but product formation parameters were almost constant. The optimum values of temperature and pH for attaining maximum biomass, maximum specific growth rate, and maximum acid production were obtained at 44 °C and 5.7, respectively. Conclusions: The attained empirical mathematical correlations of RSM alongside the kinetic equations could be used to determine growth conditions under predefined temperature and pH in the fermentation process. Keywords: Lactobacillus bulgaricus, Richards model, Response surface methodology, Lactic acid production, Luedeking-Piret model
Directory of Open Access Journals (Sweden)
Kadam R
2008-01-01
Full Text Available Aldehyde oxidase activity containing fractions from rabbit, guinea pig, rat and mouse livers were obtained by heat treatment and ammonium sulfate precipitation. Aldehyde oxidase activity was observed in rabbit and guinea pig livers, while aldehyde oxidase activity was absent in rat and mouse liver fractions. Enzyme kinetic parameters, K m and V max , were determined for the oxidation of benzaldehyde to benzoic acid by rabbit and guinea pig liver fractions, by spectrophotometric method, with potassium ferricyanide as the electron acceptor. The K m values obtained for both animal liver fractions were in the range of 10.3-19.1 µM.
Directory of Open Access Journals (Sweden)
Fagton de Mattos Negrão
2014-03-01
Full Text Available This experiment was conducted to evaluate the protein and carbohydrate fractions, and to estimate the in situ rumen degradation kinetic parameters of Brachiaria decumbens grass silage with inclusion of rice bran. Five rice bran inclusion levels were tested: 0, 10, 20, 30 and 40% of the natural matter, distributed into a completely randomized design with five replications. The brachiaria grass was obtained at 60 days of regrowth by cutting the forage at 10 cm from the soil and ensiling it in 10-L experimental silo bags, which were opened after 40 days. The degradability profiles for DM, CP, NDF and of the feeds for each animal utilized made it possible to obtain the estimates of the parameters analyzed. The contents of total carbohydrates (TCH, fibrous carbohydrates and fraction A+B1 of the TCH decreased linearly as the rice bran levels were elevated. Fraction A of the protein was increased linearly by 0.64% for every 1% of rice bran added to the silage. For nitrogenous fractions B3 and C, there was a decrease of 0.11 and 0.40% for each 1% of rice bran added to the silage, respectively. For the rumen degradability parameters of the dry matter, fractions A and I had estimated increases of 0.54 and 0.04% for every 1% inclusion of rice bran. For the degradation rate of fraction B (c, treatments had no effect. Fractions A and I of the crude protein degradability parameters increased by 0.22 and 0.72%, respectively, with inclusion of 1% rice bran. Inclusion levels of rice bran had no effect on fraction D, on the degradation rate of fraction B (c or lag time (L estimated for neutral detergent fiber. Inclusion of 10 and 20% rice bran in the brachiaria grass silage improves protein and carbohydrate fractions and rumen degradation kinetic parameters of dry matter, crude protein and neutral detergent fiber.
Ma, Ying-Shih; Sung, Chi-Fanga; Lin, Jih-Gaw
2010-06-15
To establish an efficient oxidation process for carbofuran degradation, the effects of some operating parameters such as dosages of H(2)O(2), Fe(2+) and initial carbofuran concentrations were observed during carbofuran degradation by the ultrasound process, Fenton process and a combined ultrasound/Fenton process. The degradation kinetics of carbofuran was also examined based on the experimental data. The results show that more than 99% of the carbofuran was degraded by the ultrasound/Fenton process within short reaction time periods. Increased dosages of H(2)O(2) and Fe(2+) enhanced the degradation of carbofuran in the ultrasound and Fenton oxidation processes, but initial carbofuran concentrations decreased carbofuran degradation in both the Fenton and ultrasound/Fenton processes. The degradation kinetics of carbofuran by the three oxidation processes was found to be in accordance with first-order reaction kinetics. The results provide fundamental information about the treatment of carbofuran wastewater and/or other pesticides by the ultrasound/Fenton oxidation process.
Kiernan, D; Walsh, M; O'Sullivan, R; O'Brien, T; Simms, C K
2014-01-01
Inverse Dynamic calculations are routinely used in joint moment and power estimates during gait with anthropometric data often taken from published sources. Many biomechanical analyses have highlighted the need to obtain subject-specific anthropometric data (e.g. Mass, Centre of Mass, Moments of Inertia) yet the types of imaging techniques required to achieve this are not always available in the clinical setting. Differences in anthropometric sets have been shown to affect the reactive force and moment calculations in normal subjects but the effect on a paediatric diplegic cerebral palsy group has not been investigated. The aim of this study was to investigate the effect of using different anthropometric sets on predicted sagittal plane moments during normal and diplegic cerebral palsy gait. Three published anthropometric sets were applied to the reactive force and moment calculations of 14 Cerebral Palsy and 14 Control subjects. Statistically significant differences were found when comparing the different anthropometric sets but variability in the resulting sagittal plane moment calculations between sets was low (0.01-0.07 Nm/kg). In addition, the GDI-Kinetic, used as an outcome variable to assess whether differences were clinically meaningful, indicated no clinically meaningful difference between sets. The results suggest that the effects of using different anthropometric sets on the kinetic profiles of normal and diplegic cerebral palsy subjects are clinically insignificant.
A robust methodology for kinetic model parameter estimation for biocatalytic reactions
DEFF Research Database (Denmark)
Al-Haque, Naweed; Andrade Santacoloma, Paloma de Gracia; Lima Afonso Neto, Watson;
2012-01-01
parameters, which are strongly correlated with each other. State-of-the-art methodologies such as nonlinear regression (using progress curves) or graphical analysis (using initial rate data, for example, the Lineweaver-Burke plot, Hanes plot or Dixon plot) often incorporate errors in the estimates and rarely....... The parameter estimation problem is decomposed into five hierarchical steps, where the solution of each of the steps becomes the input for the subsequent step to achieve the final model with the corresponding regressed parameters. The model is further used for validating its performance and determining...
Determination of kinetic parameters in Tl dosemeters of LiF: Mg, Cu, P + PTFE developed in the ININ
International Nuclear Information System (INIS)
The objective of this work, is the one of determining the kinetic parameters of the dosemeter of LiF: Mg, Cu, P + Ptfe; starting from the curves Tl obtained at being irradiated with alpha radiation (α), beta (β) and gamma (γ). As like to compare its sensitivity with each radiation type, considering the sensitivity of the TLD-100 as the unit. In the Chapter 1, the fundamental structure of the matter is described, making emphasis in the different radiation types, and their interaction with this. In the Chapter 2, the units are described but used in the dosimetry of the radiation. In the Chapter 3, the basic concepts of the phenomenon of Tl are described and those are explained characteristic of the deconvolution method to determine the kinetics of the one phenomenon. In the Chapter 4, the methodology is detailed that was used in the elaboration of this thesis work, describing the material Tl that were considered like reference, as well as the sources of ionizing radiation, with those that the dosemeters were irradiated and the equipment in the one that the curves Tl was obtained. Reference is made to the software used to carry out the deconvolution of the curves Tl that were obtained in the one experimental development. In the Chapter 5, the obtained results of this study are presented, showing the tables of homogenization of dosemeters and the reading of the same one; they are observed the curves Tl obtained to different radiation doses (alpha, beta and gamma), the intensity Tl in function of the dose. Also they are tabulated, the obtained results in the kinetic parameters of the three different study materials (TLD-100H, USA; TLD-100, USA and LiF: Mg, Cu, P + Ptfe developed in the l.N.l.N). They are analyzed shortly for each material Tl their sensitivity to the ionizing radiation as well as their kinetic parameters. The obtained results showed that the Tl dosemeters of LiF: Mg,Cu,P + Ptfe, they presented a bigger sensitivity that the TLD-100 when being
Energy Technology Data Exchange (ETDEWEB)
Huang, J.-W. [Department of Styling and Cosmetology, Tainan University of Technology, 529 Chung Cheng Road, Yung Kang City 710, Taiwan (China)], E-mail: jw.huang@msa.hinet.net; Chang, C.-C. [Department of International Business Management, Tainan University of Technology, 529 Chung Cheng Road, Yung Kang City 710, Taiwan (China); Kang, C.-C. [R and D Center, Hi-End Polymer Film Co., Ltd., 15-1 Sin Jhong Road, Sin Ying City 730, Taiwan (China); Yeh, M.-Y. [Department of Chemistry, National Cheng Kung University, No. 1, University Road, Tainan City 701, Taiwan (China); Sustainable Environment Research Centre, National Cheng Kung University, Taiwan (China)
2008-02-05
Blend of Nylon 6 and poly(ethylene-co-glycidyl methacrylate) (PEGMA) were prepared by a twin-screw extruder. Morphology observed with scanning electron microscopies (SEM) show PEGMA is well dispersed in Nylon 6 matrix. Isothermal and nonisothermal crystallization of the blend was investigated by differential scanning calorimeter (DSC) and crystallization kinetics was described by Avrami and Tobin models. Equilibrium melting temperatures were estimated from linear Hoffman-Weeks relationship. All analyses showed that the reaction between PEGMA and Nylon 6 reduced the molecular mobility and reduced the crystallization rate. Expand K{sub g} and U* in the Hoffman-Lauritzen equation by Vyazovkin's method demonstrated that Nylon 6/PEGMA had higher K{sub g} and U* values and provided another supportive evidence to the above interpretation.
Choi, H W; Kim, Y H; Rim, Y H; Yang, Y S
2013-06-28
The formation of crystalline LiNbO3 (LN) from LN glass has been studied by means of differential scanning calorimetry and in situ synchrotron X-ray diffraction. The LN glass with no glass former was prepared by the polymerized complex method. The isothermal kinetics of the crystallization process is described using the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation and the Avrami exponent n is found to be ~2.0, indicating that the crystallization mechanism is diffusion-controlled growth with a decreasing nucleation rate. The effective activation energy of crystallization calculated from isothermal measurements is 6.51 eV. It is found that the LN glass directly transforms into a rhombohedral LN crystal without any intermediate crystalline phase and most crystal grains are confined within the size of ~40 nm irrespective of different isothermal temperatures. Application of JMAK theory to the non-isothermal thermoanalytical study of crystallization of LN glass is discussed.
Choi, H W; Kim, Y H; Rim, Y H; Yang, Y S
2013-06-28
The formation of crystalline LiNbO3 (LN) from LN glass has been studied by means of differential scanning calorimetry and in situ synchrotron X-ray diffraction. The LN glass with no glass former was prepared by the polymerized complex method. The isothermal kinetics of the crystallization process is described using the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation and the Avrami exponent n is found to be ~2.0, indicating that the crystallization mechanism is diffusion-controlled growth with a decreasing nucleation rate. The effective activation energy of crystallization calculated from isothermal measurements is 6.51 eV. It is found that the LN glass directly transforms into a rhombohedral LN crystal without any intermediate crystalline phase and most crystal grains are confined within the size of ~40 nm irrespective of different isothermal temperatures. Application of JMAK theory to the non-isothermal thermoanalytical study of crystallization of LN glass is discussed. PMID:23677338
Directory of Open Access Journals (Sweden)
Metre Anand V.
2015-03-01
Full Text Available In the present study the esterification of palm fatty acid distillate (PFAD, a by-product from palm oil industry, in the presence of super phosphoric acid (SPA catalyst was studied. The effects of various physico-chemical parameters such as temperature, PFAD to methanol molar ratio and amount of catalyst on the conversion of biodiesel were investigated. The percent conversion of FFA and properties of the biodiesel were determined following standard methodologies. Percent conversion of biodiesel was found to increase with the increase in PFAD to methanol molar ratio and at 1:12 molar ratio and 70°C temperature 95% conversion was achieved. Thermodynamic parameters were also evaluated in terms of Gibbs free energy, enthalpy and entropy at different molar ratio and temperatures. Both pseudo first and second order irreversible kinetics were applied to a wide range of experimental data. However, according to regression coefficient (R2 the second order described better experimental behavior of kinetic data.
Energy Technology Data Exchange (ETDEWEB)
Paratte, J.M. [Laboratory for Reactor Physics and Systems Behaviour (LRS), Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland); Frueh, R. [Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Kasemeyer, U. [Laboratory for Reactor Physics and Systems Behaviour (LRS), Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland); Kalugin, M.A. [Kurchatov Institute, 123182 Moscow (Russian Federation); Timm, W. [Framatome-ANP, D-91050 Erlangen (Germany); Chawla, R. [Laboratory for Reactor Physics and Systems Behaviour (LRS), Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland); Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)
2006-05-15
Measurements in the CROCUS reactor at EPFL, Lausanne, are reported for the critical water level and the inverse reactor period for several different sets of delayed supercritical conditions. The experimental configurations were also calculated by four different calculation methods. For each of the supercritical configurations, the absolute reactivity value has been determined in two different ways, viz.: (i) through direct comparison of the multiplication factor obtained employing a given calculation method with the corresponding value for the critical case (calculated reactivity: {rho} {sub calc}); (ii) by application of the inhour equation using the kinetic parameters obtained for the critical configuration and the measured inverse reactor period (measured reactivity: {rho} {sub meas}). The calculated multiplication factors for the reference critical configuration, as well as {rho} {sub calc} for the supercritical cases, are found to be in good agreement. However, the values of {rho} {sub meas} produced by two of the applied calculation methods differ appreciably from the corresponding {rho} {sub calc} values, clearly indicating deficiencies in the kinetic parameters obtained from these methods.
Institute of Scientific and Technical Information of China (English)
LiZhong; ShuWenli; 等
1996-01-01
The parameter identification model of large scale chromatography separation process is proposed.The phase equilibrium constants and lumped mass transfer coefficients of sugar and reducing sugar adsorption on D1,D2 and D3 resins as well as the axial dispersion coefficients of the fluid through packed columns are determined by means of the pulse-response experiment technique with an inert substance as a tracer and the chromatography measuring technique.The elution curve calculated from these parameters is good agreement with the experimental elution curve.The sensitivity analysis of these parameters is carried out ,and the result shows that the elution curves of chromatography separation are more sensitive to the variations of the phase equilibrium relationship than to the variation of the axial dispersion as well as the lumped mass transfer coefficients.
Sensitivity analysis of large system of chemical kinetic parameters for engine combustion simulation
Energy Technology Data Exchange (ETDEWEB)
Hsieh, H; Sanz-Argent, J; Petitpas, G; Havstad, M; Flowers, D
2012-04-19
In this study, the authors applied the state-of-the art sensitivity methods to downselect system parameters from 4000+ to 8, (23000+ -> 4000+ -> 84 -> 8). This analysis procedure paves the way for future works: (1) calibrate the system response using existed experimental observations, and (2) predict future experiment results, using the calibrated system.
Kinetic Modeling and Parameter Estimation in a Tower Bioreactor for Bioethanol Production
Rivera, Elmer Ccopa; da Costa, Aline Carvalho; Lunelli, Betânia Hoss; Maciel, Maria Regina Wolf; Filho, Rubens Maciel
In this work, a systematic method to support the building of bioprocess models through the use of different optimization techniques is presented. The method was applied to a tower bioreactor for bioethanol production with immobilized cells of Saccharomyces cerevisiae. Specifically, a step-by-step procedure to the estimation problem is proposed. As the first step, the potential of global searching of real-coded genetic algorithm (RGA) was applied for simultaneous estimation of the parameters. Subsequently, the most significant parameters were identified using the Placket-Burman (PB) design. Finally, the quasi-Newton algorithm (QN) was used for optimization of the most significant parameters, near the global optimum region, as the initial values were already determined by the RGA global-searching algorithm. The results have shown that the performance of the estimation procedure applied in a deterministic detailed model to describe the experimental data is improved using the proposed method (RGA-PB-QN) in comparison with a model whose parameters were only optimized by RGA.
Pitakpoolsil, Wipawan; Hunsom, Mali
2014-01-15
The possibility of using commercial chitosan flakes as an adsorbent for the removal of pollutants from biodiesel wastewater was evaluated. The effect of varying the adsorption time (0.5-5 h), initial wastewater pH (2-8), adsorbent dose (0.5-5.5 g/L) and mixing rate (120-350 rpm) on the efficiency of pollutant removal was explored by univariate analysis. Under the derived optimal conditions, greater than 59.3%, 87.9% and 66.2% of the biological oxygen demand (BOD), chemical oxygen demand (COD) and oil & grease, respectively, was removed by a single adsorption. Nevertheless, the remaining BOD, COD and oil & grease were still higher than the acceptable Thai government limits for discharge into the environment. When the treatment was repeated, a greater than 93.6%, 97.6% and 95.8% removal of the BOD, COD and oil & grease, respectively, was obtained. The reusability of commercial chitosan following NaOH washing (0.05-0.2 M) was not suitable, with less than 40% efficiency after just one recycling and declining rapidly thereafter. The adsorption kinetics of all pollutant types by the commercial chitosan flakes was controlled by a mixed process of diffusion and adsorption of the pollutants during the early treatment period (0-1.5 h) and then solely controlled by adsorption after 2 h.
The kinetic Sunyaev-Zel'dovich signal from inhomogeneous reionization: a parameter space study
Mesinger, Andrei; Spergel, David
2011-01-01
[ABRIDGED] Inhomogeneous reionization acts as a source of arcminute-scale anisotropies in the cosmic microwave background (CMB), the most important of which is the kinetic Sunyaev-Zel'dovich (kSZ) effect. Observational efforts with the Atacama Cosmology Telescope (ACT) and the South Pole Telescope (SPT) are poised to detect this signal for the first time. Indeed, recent SPT measurements place a bound on the dimensionless kSZ power spectrum around a multipole of l=3000 of P_tot < 2.8 (6) micro K^2 at 95% C.L., by ignoring (allowing) correlations between the thermal Sunyaev-Zel'dovich (tSZ) effect and the cosmic infrared background (CIB). To interpret these and upcoming observations, we compute the kSZ signal from a suite of ~ 100 reionization models using the publicly available code 21cmFAST. Our physically motivated reionization models are parameterized by the ionizing efficiency of high-redshift galaxies, the minimum virial temperature of halos capable of hosting stars, and the ionizing photon mean free p...
Kinetic Parameters Estimation of MgO-C Refractory by Shrinking Core Model
Institute of Scientific and Technical Information of China (English)
B.Hashemi; Z.A.Nemati; S.K. Sadrnezhaad; Z.A.Moghimi
2006-01-01
Kinetics of oxidation of MgO-C refractories was investigated by shrinking core modeling of the gas-solid reactions taking place during heating the porous materials to the high temperatures. Samples containing 4.5～17 wt pct graphite were isothermally oxidized at 1000～1350℃. Weight loss data was compared with predictions of the model. A mixed 2-stage mechanism comprised of pore diffusion plus boundary layer gas transfer was shown to generally control the oxidation rate. Pore diffusion was however more effective, especially at graphite contents lower than 10 wt pct under forced convection blowing of the air. Model calculations showed that effective gas diffusion coefficients were in the range of 0.08 to 0.55 cm2/s. These values can be utilized to determine the corresponding tortuosity factors of 6.85 to 2.22. Activation energies related to the pore diffusion mechanism appeared to be around (46.4±2)kJ/mol. The estimated intermolecular diffusion coefficients were shown to be independent of the graphite content, when the percentage of the graphite exceeded a marginal value of 10.
Chaudhari, C. V.; Mondal, R. K.; Dubey, K. A.; Grover, V.; Panicker, L.; Bhardwaj, Y. K.; Varshney, L.
2016-08-01
A transparent, elastomeric, grafted matrix for several potential applications was synthesized by single-step simultaneous radiation grafting of methacrylic acid onto ethylene vinyl acetate (EVA). CuSO4 was found to be the most suitable homo-polymerization inhibitor among different inhibitors tried. The grafting kinetics was found to be a strong function of dose rate (D) and monomer content (M) and an equation relating grafting rate Rg=Kg [M]1.13D0.23 was deduced. Crystallinity of the grafted matrices as assessed from XRD and DSC measurements indicated decrease in crystalline content with increase in grafting yield, suggesting crystalline domain of EVA get disrupted on grafting. Elastic modulus increased linearly with the increase in grafting yield, though elongation at break decreased precipitously from 900% to 30% at even ~9% grafting. Thermo-gravimetric analysis showed three step weight loss of the grafted EVA matrix. The grafting of MAA resulted in increase in surface energy mainly due to enhanced polar component.
Orbán, Csaba; Pérez-García, Esther; Bajnok, Anna; McBean, Gethin; Toldi, Gergely; Blanco-Fernandez, Alfonso
2016-05-01
Nanosecond pulsed electric field (nsPEF) is a novel method to increase cell proliferation rate. The phenomenon is based on the microporation of cellular organelles and membranes. However, we have limited information on the effects of nsPEF on cell physiology. Several studies have attempted to describe the effects of this process, however no real time measurements have been conducted to date. In this study we designed a model system which allows the measurement of cellular processes before, during and after nsPEF treatment in real time. The system employs a Vabrema Mitoplicator(TM) nsPEF field generating instrument connected to a BD Accuri C6 cytometer with a silicon tube led through a peristaltic pump. This model system was applied to observe the effects of nsPEF in mammalian C6 glioblastoma (C6 glioma) and HEK-293 cell lines. Viability (using DRAQ7 dye), intracellular calcium levels (using Fluo-4 dye) and scatter characteristics were measured in a kinetic manner. Data were analyzed using the FACSKin software. The viability and morphology of the investigated cells was not altered upon nsPEF treatment. The response of HEK-293 cells to ionomycin as positive control was significantly lower in the nsPEF treated samples compared to non-treated cells. This difference was not observed in C6 cells. FSC and SSC values were not altered significantly by the nsPEF treatment. Our results indicate that this model system is capable of reliably investigating the effects of nsPEF on cellular processes in real time. © 2016 International Society for Advancement of Cytometry. PMID:26990601
Mainz Organics Mechanism (MOM): description and sensitivity to some estimated kinetic parameters
Taraborrelli, Domenico; Cabrera Perez, David; Sander, Rolf; Pozzer, Andrea
2015-04-01
Despite decades of reasearch, global atmospheric chemistry models still have significant biases compared to the estimated distribution and evolution of tropospheric ozone and hydroxyl radical. The gas-phase oxidation of volatile organic compounds (VOC) is acknowledged to play an important role among the processes affecting tropospheric ozone, methane lifetime and aerosol evolution. Thus, chemical mechanisms of very diverse complexity have been developed for the major VOCs. However, all mechanisms present shortcomings such as neglection or lumping of intermediates and estimate of many rate constants and product distributions. Here, we present a VOC oxidation mechanism of intermediate complexity called the Mainz Organics Mechanism (MOM). With about 400 species and 1500 reactions, it represents the oxidation of about 20 primarily emitted VOCs comprising small alkanes and alkenes, isoprene, pinenes and monocyclic aromatic compounds. The development protocol significantly borrows from the Master Chemical Mechanism (MCM). However, MOM distinguishes itself for a number of features. First, the structure activity relationship for estimating the rate constants involving hydroxyl radical is site-specific and dependent on temperature. Second, the alkyl nitrate yields are considered to be dependent on temperature, pressure and molecular structure. RO2 + HO2 reaction kinetics is consistent with the recent direct studies of \\chem{OH}-reformation. Isoprene chemistry includes the latest experimental advancements with respect to OH-recycling and alkyl nitrate chemistry. Pinenes chemistry is largely the one by the MCM but with some modifications according to the work of the Leuven's group. Finally, the chemistry of the aromatics is also borrowed from the MCM but with additional photolysis of ortho-nitrophenols leading to \\chem{HONO} formation. The sensitivity of the model to the temperature and pressure dependence of estimated \\chem{OH} rate constants and alkyl nitrate yields will
Directory of Open Access Journals (Sweden)
Mannerstrom Henrik
2011-01-01
Full Text Available We propose a Markov chain approximation of the delayed stochastic simulation algorithm to infer properties of the mechanisms in prokaryote transcription from the dynamics of RNA levels. We model transcription using the delayed stochastic modelling strategy and realistic parameter values for rate of transcription initiation and RNA degradation. From the model, we generate time series of RNA levels at the single molecule level, from which we use the method to infer the duration of the promoter open complex formation. This is found to be possible even when adding external Gaussian noise to the RNA levels.
Particle Size Effect on TL Emission of ZnS Nanoparticles and Determination of Its Kinetic Parameters
Directory of Open Access Journals (Sweden)
L. Robindro Singh
2012-01-01
Full Text Available Nanoparticles have large surface area, and most of the ions are lying on its surface. Could these surface ions be contributed in thermoluminescence emission or enhanced nonradiative transition? In view of this, we have prepared small sizes of ZnS nanoparticles at low temperature and made two samples, one as-prepared (size ~3 nm and the other heat-treated at 1073 K (size ~32 nm. Characterization of the samples shows that the prepared phosphors are pure. Thermoluminescence (TL glow curves could not be recorded in both samples without irradiation. Even for higher dose of γ-radiation the as-prepared samples could not show TL signal, but 1073 K heat-treated sample shows the TL signal. This may be due to the fact that smaller particles have large surface area compared to bigger particles, the surface ions may produce the nonradiative transitions. The kinetic parameters of the TL glow curves are evaluated by the conventional methods and compared with curve fitting computerised glow curve deconvolution (CGCD technique. The variations in both techniques are found only ±0.02. The shape factor of all the glow curves ~0.48, and these TL glow curves could be fitted with order of kinetics 1.5.
Helbling, Damian E; Johnson, David R; Honti, Mark; Fenner, Kathrin
2012-10-01
The objective of this work was to identify relevant wastewater treatment plant (WWTP) parameters and underlying microbial processes that influence the biotransformation of a diverse set of micropollutants. To do this, we determined biotransformation rate constants for ten organic micropollutants in batch reactors seeded with activated sludge from ten diverse WWTPs. The estimated biotransformation rate constants for each compound ranged between one and four orders of magnitude among the ten WWTPs. The biotransformation rate constants were tested for statistical associations with various WWTP process parameters, amoA transcript abundance, and acetylene-inhibited monooxygenase activity. We determined that (i) ammonia removal associates with oxidative micropollutant biotransformation reaction rates; (ii) archaeal but not bacterial amoA transcripts associate with both ammonia removal and oxidative micropollutant biotransformation reaction rates; and (iii) the activity of acetylene-inhibited monooxygenases (including ammonia monooxygenase) associates with ammonia removal and the biotransformation rate of isoproturon, but does not associate with all oxidative micropollutant biotransformations. In combination, these results lead to the conclusion that ammonia removal and amoA transcript abundance can potentially be predictors of oxidative micropollutant biotransformation reactions, but that the biochemical mechanism is not necessarily linked to ammonia monooxygenase activity. PMID:22938719
Zarghami, V.; Mohammadi, M. R.; Fray, D. J.
2012-11-01
The morphological manipulation, structural characterization, and optical properties of different cadmium selenide (CdSe) nanostructures are reported. Two different CdSe nanostructures, i.e., nanorods and nanoparticles, were grown by controlling the concentration of precursors (i.e., cadmium nitrate and selenium dioxide) in ethanolamine solvent. By manipulating the kinetic parameter of the process (i.e., growth rate) under constant growth driving force (i.e., degree of supersaturation), the morphology of CdSe nanostructures can be tailored from nanorods to nanoparticles. The optical properties of CdSe nanostructures were investigated using ultraviolet-visible (UV-vis) spectroscopy. The absorption edge of the samples showed a blue-shift. CdSe nanostructures prepared under optimized conditions showed good microstructural and optical properties for solar cell applications.
DEFF Research Database (Denmark)
Tofts, P.S.; Brix, G; Buckley, D.L.;
1999-01-01
We describe a standard set of quantity names and symbols related to the estimation of kinetic parameters from dynamic contrast-enhanced T(1)-weighted magnetic resonance imaging data, using diffusable agents such as gadopentetate dimeglumine (Gd-DTPA). These include a) the volume transfer constant K......(trans) (min(-1)); b) the volume of extravascular extracellular space (EES) per unit volume of tissue v(e) (0 ...-limited conditions K(trans) equals the blood plasma flow per unit volume of tissue; under permeability-limited conditions K(trans) equals the permeability surface area product per unit volume of tissue. We relate these quantities to previously published work from our groups; our future publications will refer...
International Nuclear Information System (INIS)
The objective of the present work was to establish pharmacokinetic parameters of the C Mitomycin (MMC) in vivo, comparing its kinetics of induction of polychromatic micro nucleate erythrocytes (EPGMN) with that of the gamma radiation. The used doses were of 0.75; 1.5 and 3. 0 μmoles/kg of MMC. It was observed that the MMC produces MN in the first cycle of cellular division and it is independent of the cytotoxic effect. This agent requires of a relatively long period of latency that is not compatible with her great reactivity, for what the pharmacokinetic values obtained in fact reflect the time that takes the processing of leisure in the DNA and the subsequent induction of ruptures that produce MN. (Author)
Dosimetric and kinetic parameters of lithium cadmium borate glasses doped with rare earth ions
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J. Anjaiah
2014-10-01
Full Text Available Thermoluminescence (TL characteristics of X-ray irradiated pure and doped with four different rare earth ions (viz., Pr3+, Nd3+, Sm3+ and Eu3+ Li2O–Cdo–B2O3 glasses have been studied in the temperature range 303–573 K; the pure glass has exhibited single TL peak at 466 K. When this glass is doped with different rare earth ions no additional peaks are observed but the glow peak temperature of the existing glow peak shifted gradually towards higher temperatures with gain in intensity of TL light output. The area under the glow curve is found to be maximum for Eu3+ doped glasses. The trap depth parameters associated with the observed TL peaks have been evaluated using Chen's formulae. The possible use of these glasses in radiation dosimetry has been described. The result clearly showed that europium doped cadmium borate glass has a potential to be considered as the thermoluminescence dosimeter.
Magnetic Properties and Kinetics Parameters of Electroless Magnetic Loss CoFeB Films
Institute of Scientific and Technical Information of China (English)
LIU Chang-hui; HE Hua-hui; SHEN Xiang; LI Hai-hua
2008-01-01
Electroless CoFeB films with good soft magnetic properties were fabricated on polyester plastic substrate from sodium tartarate as a complexing agent. The plating rate of electroless CoFeB films is a function of concentration of sodium tetrahydroborate, pH of the plating bath, plating temperature and the metallic ratio. The estimated regression coefficient b0-b3 confidence interval, residual error r and confidence interval rint were confirmed by a computer program. The optimal composition of the plating bath was obtained and the dynamic electromagnetic parameters of films were measured in the 2-10 GHz range. At 2 GHz, the μ′, μ″ of the electroless CoFeB films were 304 and 76.6, respectively, as the concentration of reducer is 1 g/L. Magnetic hysteresis loop of the deposited CoFeB films show a remanence close to the saturation magnetization and coercivity of about 55.7-127.4 A/m. The loops along the hard axis display low anisotropic field Hk of 2 388-3 582 A/m.
Liu, Xiaowei; Zhang, Tuqiao; Zhou, Yongchao; Fang, Lei; Shao, Yu
2013-11-01
Photoactivation of peroxymonosulfate (PMS) with UV (254nm) irradiation was used to generate the SO4(-)-based advanced oxidation process, which was adopted to degrade atenolol (ATL) in water. The second-order reaction rate constants of ATL with HO and SO4(-) were determined, and the effects of operational parameters (dose of PMS, solution pH, HCO3(-), humic acids (HA), and N2 bubbling) were evaluated as well. Finally the main transformation intermediates were identified and possible degradation pathways were proposed. The results showed that there was a linear positive correlation between the degradation rate of ATL and specific dose of PMS (1-16M PMS/M ATL). Increasing solution pH from 3 to 9 promoted elimination of ATL due to the pH-dependent effect of PMS photodecomposition, while further pH increase from 9 to 11 caused slowing down of degradation because of apparent conversion of HO to SO4(-). 1-8mM HCO3(-) exerted no more than 5.3% inhibition effect on ATL destruction, suggesting HCO3(-) was a weak inhibitor. Absorption (or complexation) and photosensitized oxidation induced by HA improved ATL degradation during the first minute of degradation process, whereas photon competition and radical scavenging effects became the leading role afterward. Bubbling with nitrogen enhanced the degradation rate due to the stripping of dissolved oxygen. Hydroxylation of aromatic ring, cleavage of ether bond, oxidation of primary and secondary amine moieties, and dimerization were involved in the degradation mechanism of ATL by UV/PMS.
Energy Technology Data Exchange (ETDEWEB)
Bunting, Bruce G [ORNL
2012-10-01
The automotive and engine industries are in a period of very rapid change being driven by new emission standards, new types of after treatment, new combustion strategies, the introduction of new fuels, and drive for increased fuel economy and efficiency. The rapid pace of these changes has put more pressure on the need for modeling of engine combustion and performance, in order to shorten product design and introduction cycles. New combustion strategies include homogeneous charge compression ignition (HCCI), partial-premixed combustion compression ignition (PCCI), and dilute low temperature combustion which are being developed for lower emissions and improved fuel economy. New fuels include bio-fuels such as ethanol or bio-diesel, drop-in bio-derived fuels and those derived from new crude oil sources such as gas-to-liquids, coal-to-liquids, oil sands, oil shale, and wet natural gas. Kinetic modeling of the combustion process for these new combustion regimes and fuels is necessary in order to allow modeling and performance assessment for engine design purposes. In this research covered by this CRADA, ORNL developed and supplied experimental data related to engine performance with new fuels and new combustion strategies along with interpretation and analysis of such data and consulting to Reaction Design, Inc. (RD). RD performed additional analysis of this data in order to extract important parameters and to confirm engine and kinetic models. The data generated was generally published to make it available to the engine and automotive design communities and also to the Reaction Design Model Fuels Consortium (MFC).
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Raposo, Maria, E-mail: mfr@fct.unl.pt; Monteiro Timóteo, Ana Rita; Ribeiro, Paulo A. [CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, UNL, Campus de Caparica, 2829-516 Caparica (Portugal); Ferreira, Quirina [CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, UNL, Campus de Caparica, 2829-516 Caparica (Portugal); Instituto de Telecomunicações, Instituto Superior Técnico, University of Lisbon, Av. Rovisco Pais, P-1049-001 Lisboa (Portugal); Botelho do Rego, Ana Maria [Centro de Química-Física Molecular and IN, Complexo Interdisciplinar, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisboa (Portugal)
2015-09-21
Photo induced birefringent materials can be used to develop optical and conversion energy devices, and consequently, the study of the variables that influences the creation and relaxation of birefringence should be carefully analyzed. In this work, the parameters of birefringence creation and relaxation kinetics curves obtained on layer-by-layer (LBL) films, prepared from azo-polyectrolyte poly[1-[4-(3-carboxy-4 hydroxyphenylazo) benzene sulfonamido]-1,2-ethanediyl, sodium salt] (PAZO) and poly(allylamine hydrochloride)(PAH), are related with the presence of counterions and the degree of ionization of the polyelectrolytes. Those kinetics curves obtained on PAH/PAZO LBL films, prepared from PAH solutions with different pHs and maintaining the pH of PAZO solution constant at pH = 9, were analyzed taking into account the films composition which was characterized by X-ray photoelectron spectroscopy. The creation and relaxation birefringence curves are justified by two processes: one associated to local mobility of the azobenzene with a characteristic time 30 s and intensity constant and other associated with polymeric chains mobility with the characteristic time and intensity decreasing with pH. These results allow us to conclude that the birefringence creation process, associated to local mobility of azobenzenes is independent of the degree of ionization and of number of counterions or co-ions present while the birefringence creation process associated to mobility of chains have its characteristic time and intensity dependent of both degree of ionization and number of counterions. The birefringence relaxation processes are dependent of the degree of ionization. The analysis of the films composition revealed, in addition, the presence of a protonated secondary or tertiary amine revealing that PAZO may have positive charges and consequently a zwitterionic behavior.
Raposo, Maria; Ferreira, Quirina; Monteiro Timóteo, Ana Rita; Ribeiro, Paulo A.; do Rego, Ana Maria Botelho
2015-09-01
Photo induced birefringent materials can be used to develop optical and conversion energy devices, and consequently, the study of the variables that influences the creation and relaxation of birefringence should be carefully analyzed. In this work, the parameters of birefringence creation and relaxation kinetics curves obtained on layer-by-layer (LBL) films, prepared from azo-polyectrolyte poly[1-[4-(3-carboxy-4 hydroxyphenylazo) benzene sulfonamido]-1,2-ethanediyl, sodium salt] (PAZO) and poly(allylamine hydrochloride)(PAH), are related with the presence of counterions and the degree of ionization of the polyelectrolytes. Those kinetics curves obtained on PAH/PAZO LBL films, prepared from PAH solutions with different pHs and maintaining the pH of PAZO solution constant at pH = 9, were analyzed taking into account the films composition which was characterized by X-ray photoelectron spectroscopy. The creation and relaxation birefringence curves are justified by two processes: one associated to local mobility of the azobenzene with a characteristic time 30 s and intensity constant and other associated with polymeric chains mobility with the characteristic time and intensity decreasing with pH. These results allow us to conclude that the birefringence creation process, associated to local mobility of azobenzenes is independent of the degree of ionization and of number of counterions or co-ions present while the birefringence creation process associated to mobility of chains have its characteristic time and intensity dependent of both degree of ionization and number of counterions. The birefringence relaxation processes are dependent of the degree of ionization. The analysis of the films composition revealed, in addition, the presence of a protonated secondary or tertiary amine revealing that PAZO may have positive charges and consequently a zwitterionic behavior.
Energy Technology Data Exchange (ETDEWEB)
La Fontaine, M; Bradshaw, T [University of Wisconsin, Madison, Wisconsin (United States); Kubicek, L [University of Florida, Gainesville, Florida (United States); Forrest, L [University of Wisconsin-Madison, Madison, Wisconsin (United States); Jeraj, R [University of Wisconsin, Madison, WI (United States)
2014-06-15
Purpose: Regions of poor perfusion within tumors may be associated with higher hypoxic levels. This study aimed to test this hypothesis by comparing measurements of hypoxia from Cu-ATSM PET to vasculature kinetic parameters from DCE-CT kinetic analysis. Methods: Ten canine patients with sinonasal tumors received one Cu-ATSM PET/CT scan and three DCE-CT scans prior to treatment. Cu-ATSM PET/CT and DCE-CT scans were registered and resampled to matching voxel dimensions. Kinetic analysis was performed on DCE-CT scans and for each patient, the resulting kinetic parameter values from the three DCE-CT scans were averaged together. Cu-ATSM SUVs were spatially correlated (r{sub spatial}) on a voxel-to-voxel basis against the following DCE-CT kinetic parameters: transit time (t{sub 1}), blood flow (F), vasculature fraction (v{sub 1}), and permeability (PS). In addition, whole-tumor comparisons were performed by correlating (r{sub ROI}) the mean Cu-ATSM SUV (SUV{sub mean}) with median kinetic parameter values. Results: The spatial correlations (r{sub spatial}) were poor and ranged from -0.04 to 0.21 for all kinetic parameters. These low spatial correlations may be due to high variability in the DCE-CT kinetic parameter voxel values between scans. In our hypothesis, t{sub 1} was expected to have a positive correlation, while F was expected to have a negative correlation to hypoxia. However, in wholetumor analysis the opposite was found for both t{sub 1} (r{sub ROI} = -0.25) and F (r{sub ROI} = 0.56). PS and v{sub 1} may depict angiogenic responses to hypoxia and found positive correlations to Cu-ATSM SUV for PS (r{sub ROI} = 0.41), and v{sub 1} (r{sub ROI} = 0.57). Conclusion: Low spatial correlations were found between Cu-ATSM uptake and DCE-CT vasculature parameters, implying that poor perfusion is not associated with higher hypoxic regions. Across patients, the most hypoxic tumors tended to have higher blood flow values, which is contrary to our initial hypothesis. Funding
Directory of Open Access Journals (Sweden)
Muhammad Atta
2014-01-01
Full Text Available In this study kinetic parameters, effective delayed neutron fraction and prompt neutron generation time have been investigated at different burn-up stages for research reactor's equilibrium core utilizing low enriched uranium high density fuel (U3Si2-Al fuel with 4.8 g/cm3 of uranium. Results have been compared with reference operating core of Pakistan research Reactor-1. It was observed that by increasing fuel burn-up, effective delayed neutron fraction is decreased while prompt neutron generation time is increased. However, over all ratio beff/L is decreased with increasing burn-up. Prompt neutron generation time L in the understudy core is lower than reference operating core of reactor at all burn-up steps due to hard spectrum. It is observed that beff is larger in the understudy core than reference operating core of due to smaller size. Calculations were performed with the help of computer codes WIMSD/4 and CITATION.
International Nuclear Information System (INIS)
In the framework of the European 5FP MUSE measurements are performed to investigate the neutronic behavior of the fast subcritical core MASURCA coupled with the GENEPI accelerator. The aim is to examine the applicability of different techniques for the determination of the main kinetic parameters characterizing the assembly such as the delayed neutron fraction, the mean neutron lifetime and the reactivity (expressed in dollars). When applying the pulsed neutron source analysis, the reactivity (in dollars) together with the ratio of the mean neutron lifetime l and the effective delayed neutron fraction βeff is derived. Although these first results are very promising, further measurements are needed to qualify the method at larger subcritical levels which are representative for future ADS. From Rossi-alpha distributions, recorded with the pulsed neutron source in operation, the α decay constant was easily derived due to good statistics on the correlated signal resulting from the strong intensity of the neutron pulse. These measurements also pointed out that one should avoid locating the detectors in the shielding where neutron thermalization will perturb the measurements. The measurement of Rossi-alpha distributions, recorded with the accelerator turned off, showed that the analysis of the obtained distributions is still feasible for deep subcritical levels where deteriorated statistics occur. A more elaborated measurement campaign is scheduled in the following year to more thoroughly answer the applicability issue of the different measurement techniques for ADS. (author)
Comparison of dual-echo DSC-MRI- and DCE-MRI-derived contrast agent kinetic parameters.
Quarles, C Chad; Gore, John C; Xu, Lei; Yankeelov, Thomas E
2012-09-01
The application of dynamic susceptibility contrast (DSC) MRI methods to assess brain tumors is often confounded by the extravasation of contrast agent (CA). Disruption of the blood-brain barrier allows CA to leak out of the vasculature leading to additional T(1), T(2) and T(2) relaxation effects in the extravascular space, thereby affecting the signal intensity time course in a complex manner. The goal of this study was to validate a dual-echo DSC-MRI approach that separates and quantifies the T(1) and T(2) contributions to the acquired signal and enables the estimation of the volume transfer constant, K(trans), and the volume fraction of the extravascular extracellular space, v(e). To test the validity of this approach, DSC-MRI- and dynamic contrast enhanced (DCE) MRI-derived K(trans) and v(e) estimates were spatially compared in both 9L and C6 rat brain tumor models. A high degree of correlation (concordance correlation coefficients >0.83, Pearson's r>0.84) and agreement was found between the DSC-MRI- and DCE-MRI-derived measurements. These results indicate that dual-echo DSC-MRI can be used to simultaneously extract reliable DCE-MRI kinetic parameters in brain tumors in addition to conventional blood volume and blood flow metrics.
Hartogensis, O.K.; Debruin, H.A.R.
2005-01-01
The Monin-Obukhov similarity theory (MOST) functions fepsi; and fT, of the dissipation rate of turbulent kinetic energy (TKE), ¿, and the structure parameter of temperature, CT2, were determined for the stable atmospheric surface layer using data gathered in the context of CASES-99. These data cover
Energy Technology Data Exchange (ETDEWEB)
Zhang, X.; Wren, J.C. [Department of Chemistry, University of Western Ontario, 1151 Richmond St, London, Ontario, N6A 5B7 (Canada); Betova, I. [Department of Chemistry, Technical University of Sofia, 1000 Sofia (Bulgaria); Bojinov, M., E-mail: martin@uctm.edu [Department of Physical Chemistry, University of Chemical Technology and Metallurgy, 1756 Sofia (Bulgaria)
2011-07-01
Highlights: > The passive state of carbon steel is described using the Mixed-Conduction Model for oxide films. > Kinetic parameters are estimated by comparison of the model to EIS and XPS data. > The passive film is intermediate between magnetite and maghemite. > Relevance of film growth and dissolution reactions for corrosion is discussed. - Abstract: The unambiguous interpretation of electrochemical impedance spectra of complex systems such as passive metals and alloys in terms of an unique kinetic model is often hampered by the large number of adjustable modeling parameters. In this paper, a combination of in situ electrochemical data and ex situ surface analytical information is employed to validate the estimates of kinetic and transport parameters of the passive state of carbon steel. For the purpose, electrochemical impedance spectroscopic and X-ray photoelectron spectroscopic data for the oxidation of carbon steel in mildly alkaline solutions are quantitatively compared with the predictions of the Mixed-Conduction Model for oxide films that represent the passive oxide as an intermediate phase between magnetite and maghemite. Estimates of the kinetic rate constants at the film interfaces, as well as the diffusion coefficients and field strength in the film are obtained and their relevance for the corrosion mechanism of carbon steel is discussed.
Navarro, F; Harouna, S; Calvo, M; Pérez, M D; Sánchez, L
2015-07-01
Lactoferrin is a protein with important biological functions that can be obtained from milk and by-products derived from the dairy industry, such as whey. Although bovine lactoferrin has been extensively studied, ovine lactoferrin is not quite as well known. In the present study, the effect of several heat treatments in 3 different media, over a temperature range from 66 to 75°C, has been studied on lactoferrin isolated from sheep milk. Denaturation of lactoferrin was determined by measuring its immunoreactivity with specific polyclonal antibodies. Kinetic and thermodynamic parameters obtained indicate that lactoferrin denatures by heat more rapidly in whey than in phosphate buffer or milk. The value of activation energy found for the denaturation process of lactoferrin when treated in whey is higher (390kJ/mol) than that obtained in milk (194kJ/mol) or phosphate buffer (179kJ/mol). This indicates that a great amount of energy is necessary to start denaturation of ovine lactoferrin, probably due to the interaction of this protein with other whey proteins. The changes in the hydrophobicity of lactoferrin after heat treatments were determined by fluorescence measurement using acrylamide. The decrease in the hydrophobicity constant was very small for the treatments from 66 to 75°C, up to 20min, which indicates that lactoferrin conformation did not experienced a great change. The results obtained in this study permit the prediction of behavior of ovine lactoferrin under several heat treatments and show that high-temperature, short-time pasteurization (72°C, 15 s) does not cause loss of its immunoreactivity and, consequently, would not affect its conformation and biological activity.
Directory of Open Access Journals (Sweden)
Aline B. Denis
2016-01-01
Full Text Available This study aimed to analyze the kinetic parameters of two monomers using attenuated total reflectance Fourier transform infrared (ATR-FTIR: 2,2-bis-[4-(2-hydroxy-3-methacryloxypropyl-1-oxy-phenyl] propane (Bis-GMA and triethylene glycol dimethacrylate (TEGDMA. The following were calculated to evaluate the kinetic parameters: maximum conversion rate (Rpmax, time at the maximum polymerization rate (tmax, conversion at Rpmax, and total conversion recorded at the maximum conversion point after 300 s. Camphorquinone (CQ and phenyl propanedione (PPD were used in this study as photoinitiators, whereas N,N-dimethyl-p-toluidine (DMPT amine was used as a coinitiator. LED apparatus and halogen lamp were used in turn to evaluate the effect that light source had on the monomer kinetics. The mass concentration ratio for the three resin preparations was 0.7 : 0.3 for Bis-GMA and TEGDMA: R1 (CQ + DMPT, R2 (PPD + DMPT, and R3 (PPD + CQ + DMPT. The PPD association with the CQ photoinitiator altered the polymerization kinetics compared to a resin containing only the CQ photoinitiator. The light sources exhibited no significant differences for tmax of R1 and R3. Resins containing only the PPD initiator exhibited a higher tmax than those containing only CQ. However, the Rpmax decreased for resins containing the PPD photoinitiator.
Energy Technology Data Exchange (ETDEWEB)
Sepulveda M, F. [ESFM-IPN, 07738 Mexico D.F. (Mexico); Azorin N, J.; Rivera M, T. [UAM-I, 09340 Mexico D.F. (Mexico); Furetta, C.; Sanipoli, C. [Physics Department, Universita di Roma ' ' La Sapienza' ' , Piazzale A. Moro 2, 00185 Roma (Italy)
2004-07-01
The thermoluminescent curves induced by the beta radiation in the perovskite KMgF{sub 3} were investigated activated with lanthanum. The classic methods were used to determine the kinetic parameters (the kinetic order b, the activation energy E and the frequency of escape intent s) associated with the peaks of the thermoluminescent curve (Tl) in the KMgF{sub 3} activated with lanthanum after the irradiation with beta rays. The method is based on the position of the thermoluminescent peaks, obtained of the temperature change of the peak in the maximum emission caused by the change in the heating rapidity to which the samples were measured. In this work, the samples in form of pellets were re cooked previously at 400 C during one hour before irradiating them with beta particles. The Tl measures were made with a Tl reader system using three different heating rapidities and storing the glow curves. To calculate the depth of the E traps and the frequency factor s, the parameters of the glow curve were determined experimentally of the shame of the glow curve by means of the mensuration of the shame of the maximum temperature of the peak, T{sub M} like a function of the heating rapidity. The results indicate that the values of the kinetic parameters are very near among if when they are obtained indistinctly of anyone of the different methods. (Author)
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Nandipati, Giridhar; Setyawan, Wahyu; Heinisch, Howard L.; Roche, Kenneth J.; Kurtz, Richard J.; Wirth, Brian D.
2015-07-01
Object kinetic Monte Carlo (OKMC) simulations have been performed to investigate various aspects of cascade aging in bulk tungsten and to determine the sensitivity of the results to the kinetic parameters. The primary focus is on how the kinetic parameters affect the initial recombination of defects in the first few ns of a simulation. The simulations were carried out using the object kinetic Monte Carlo (OKMC) code KSOME (kinetic simulations of microstructure evolution), using a database of cascades obtained from results of molecular dynamics (MD) simulations at various primary knock-on atom (PKA) energies and directions at temperatures of 300, 1025 and 2050 K. The OKMC model was parameterized using defect migration barriers and binding energies from ab initio calculations. Results indicate that, due to the disparate mobilities of SIA and vacancy clusters in tungsten, annealing is dominated by SIA migration even at temperatures as high as 2050 K. For 100 keV cascades initiated at 300 K recombination is dominated by annihilation of large defect clusters. But for all other PKA energies and temperatures most of the recombination is due to the migration and rotation of small SIA clusters, while all the large SIA clusters escape the cubic simulation cell. The inverse U-shape behavior exhibited by the annealing efficiency as a function of temperature curve, especially for cascades of large PKA energies, is due to asymmetry in SIA and vacancy clustering assisted by the large difference in mobilities of SIAs and vacancies. This annealing behavior is unaffected by the dimensionality of SIA migration persists over a broad range of relative mobilities of SIAs and vacancies.
Energy Technology Data Exchange (ETDEWEB)
Nichita, E., E-mail: Eleodor.nichita@uoit.ca [University of Ontario Institute of Technology, 2000 Simcoe Str. North, Oshawa, ON, Canada L1H 7K4 (Canada); Serghiuta, D.; Podobed, S. [Canadian Nuclear Safety Commission, 280 Slater Street, P.O. Box 1046 Station B, Ottawa, ON, Canada K1P 5S9 (Canada)
2015-05-15
Highlights: • CANDU-type-lattice kinetics parameters are calculated using different adjoint-weighting approximations at different burnups. • Fine-group space-dependent adjoint weighting is the most accurate method of calculating the kinetics parameters. • Two-group lattice-homogenized adjoint weighting overestimates the effective delayed-neutron fraction by approximately 5%. • Fine-group lattice-homogenized adjoint weighting overestimates the effective delayed neutron fraction only by approximately 2%. - Abstract: Modern analysis of nuclear reactor transients uses space-time reactor kinetics methods. In the Canadian nuclear industry, safety analysis calculations use almost exclusively the Improved Quasistatic (IQS) flux factorization method. The IQS method, like all methods based on flux factorization, relies on calculating effective point kinetics parameters, which dominate the time behavior of the flux, using adjoint-weighted integrals. The accuracy of the adjoint representation influences the accuracy of the effective kinetics parameters. Routine full core calculations are not performed using detailed models and transport theory, but rather using a cell-homogenized model and two-group diffusion theory. This work evaluates the effect of homogenization and group condensation at different burnups, for three fuel types: natural-uranium (NU) fuel, low-void reactivity (LVR) fuel and Advanced CANDU Reactor (ACR) fuel. Results show that the use of a two-group lattice-homogenized adjoint consistently overestimates the effective delayed neutron fraction by approximately 5% for all three fuel types and over a wide burnup range. The use of a two-group lattice-homogenized adjoint also introduces errors in the effective neutron generation time, but these are at most 1.3% (and their sign changes with burnup). Errors tend to vary with burnup by approximately 1% (of the individual parameter value). If a 69-group lattice-homogenized adjoint is used, the errors drop to
Gonzalez-Gil, G.; Kleerebezem, R.; Lettinga, G.
2002-01-01
This report presents a new approach to studying the metabolic and kinetic properties of anaerobic sludge from single batch experiments. The two main features of the method are that the methane production is measured on-line with a relatively cheap system, and that the methane production data can be
Energy Technology Data Exchange (ETDEWEB)
Nandipati, Giridhar, E-mail: giridhar.nandipati@pnnl.gov [Pacific Northwest National Laboratory, Richland, WA (United States); Setyawan, Wahyu; Heinisch, Howard L. [Pacific Northwest National Laboratory, Richland, WA (United States); Roche, Kenneth J. [Pacific Northwest National Laboratory, Richland, WA (United States); Department of Physics, University of Washington, Seattle, WA 98195 (United States); Kurtz, Richard J. [Pacific Northwest National Laboratory, Richland, WA (United States); Wirth, Brian D. [University of Tennessee, Knoxville, TN (United States)
2015-07-15
A study has been performed using object kinetic Monte Carlo (OKMC) simulations to investigate various aspects of cascade aging in bulk tungsten (W) and to determine its sensitivity to the kinetic parameters. The primary focus is on how the kinetic parameters affect the intracascade recombination of defects. Results indicate that, due to the disparate mobilities of SIA and vacancy clusters, annealing is dominated by SIA migration even at 2050 K. It was found that for 100 keV cascades initiated at 300 K, recombination is dominated by the annihilation of large defect clusters, while for all the other primary knock-on atom (PKA) energies and temperatures, recombination is primarily due to the migration and rotation of small SIA clusters, while the large SIA clusters escape the simulation cell. The annealing efficiency exhibits an inverse U-shaped curve behavior with increasing temperature, especially at large PKA energies, caused by the asymmetry in SIA and vacancy clustering assisted by the large differences in their mobilities. This behavior is unaffected by the dimensionality of SIA migration, and it persists over a broad range of relative mobilities of SIAs and vacancies.
International Nuclear Information System (INIS)
Nowadays, a collaborative effort to improve the prediction accuracy of some kinetic parameters has been recommended. In special, a target accuracy of ±3% (1 s.d.) was requested for βeff calculations, in way that βeff values must be measured with an experimental error of less than 3%. In such a way, the Reactor Physics Group at IPEN/MB-01 Research Reactor has been compiled an experimental data bank of kinetic parameters, including βeff, Λ, βeff /Λ and others, based on noise analyses techniques. The implemented techniques are: Power Spectral Densities (PSD) using current-type detectors, Rossi-α and Feynman-α techniques. All these techniques provided βeff values with uncertainties within the target accuracy. In order to conclude this data bank, in this work we have been performed PSD measurements using pulse-type detectors. The main advantage of this technique is that it is possible to eliminate some electronic modules, needed in the current-mode experiments, which are sources of parasitic noises. Furthermore, this technique can explain an anomalous behavior reported in current-mode measurements, which is a non-observation of a theoretical predicted plateau above 200 Hz, approximately. Once completed, the kinetic parameters data bank should provide valuable information to determine whether or not the currently data libraries are sufficiently accurate to predict these measured parameters. Further, we intend to submit a proposal for the first international benchmark related to βeff measurements, to the International Reactor Physics Experiment Evaluation Project (IRPhEP, NEA data bank). (author)
Energy Technology Data Exchange (ETDEWEB)
Kuramoto, Renato Yoichi Ribeiro; Santos, Adimir dos; Jerez, Rogerio; Diniz, Ricardo [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mails: ryrkuram@ipen.br; asantos@ipen.br
2007-07-01
Nowadays, a collaborative effort to improve the prediction accuracy of some kinetic parameters has been recommended. In special, a target accuracy of {+-}3% (1 s.d.) was requested for {beta}{sub eff} calculations, in way that {beta}{sub eff} values must be measured with an experimental error of less than 3%. In such a way, the Reactor Physics Group at IPEN/MB-01 Research Reactor has been compiled an experimental data bank of kinetic parameters, including {beta}{sub eff}, {lambda}, {beta}{sub eff} /{lambda} and others, based on noise analyses techniques. The implemented techniques are: Power Spectral Densities (PSD) using current-type detectors, Rossi-{alpha} and Feynman-{alpha} techniques. All these techniques provided {beta}{sub eff} values with uncertainties within the target accuracy. In order to conclude this data bank, in this work we have been performed PSD measurements using pulse-type detectors. The main advantage of this technique is that it is possible to eliminate some electronic modules, needed in the current-mode experiments, which are sources of parasitic noises. Furthermore, this technique can explain an anomalous behavior reported in current-mode measurements, which is a non-observation of a theoretical predicted plateau above 200 Hz, approximately. Once completed, the kinetic parameters data bank should provide valuable information to determine whether or not the currently data libraries are sufficiently accurate to predict these measured parameters. Further, we intend to submit a proposal for the first international benchmark related to {beta}{sub eff} measurements, to the International Reactor Physics Experiment Evaluation Project (IRPhEP, NEA data bank). (author)
Aghilinategh, Nahid; Rafiee, Shahin; Gholikhani, Abolfazl; Hosseinpur, Soleiman; Omid, Mahmoud; Mohtasebi, Seyed S; Maleki, Neda
2015-11-01
In the study, the effectiveness of intermittent (IMWD) and continuous (CMWD) microwave drying and hot air drying (HAD) treatments on apple slices were compared in terms of drying kinetics (moisture diffusivity and activation energy) and critical physicochemical quality attributes (color change, rehydration ratio, bulk density, and total phenol content (TPC) of the final dried product. The temperature, microwave power, air velocity, and pulse ratio (PR) applied in the experiments were 40-80°C, 200-600 W, 0.5-2 m/s, and 2-6, respectively. Results showed that IMWD and CMWD more effective than HAD in kinetic parameters and physicochemical quality attributes. Also, results indicated CMWD had the lowest and highest drying time and effective diffusivity. The exponential model for estimating IMWD activation energy, considering absolute power (1/P) and pulse ratio were also represented. The color change in apple slices dried by HAD showed the highest change. PMID:26788293
Rafael Silva; Gizilene M. Carvalho; Muniz, Edvani C.; Adley F. Rubira
2010-01-01
The thermal degradation of miscible and immiscible poly (3-hidroxy butyrate) PHB/ poly (ethylene terephthalate) sulphonated (PETs) blends was investigated using thermogravimetric analyses. Model-free kinetic analysis, Vyazovkin and Flynn-Wall-Ozawa's methods, were used to determine the apparent activation energy in the whole interval of degradation of the pure polymers, immiscible blends, and miscible blends. The thermal stability of both polymers in their blends is higher when compared to th...
Directory of Open Access Journals (Sweden)
José L. Gómez
2005-01-01
Full Text Available A new method for determining the intrinsic parameters of reaction in processes involving a high initial rate has been developed. The usefulness of this alternative, which consists of determining several sets of apparent parameters at different times and then extrapolating these to time zero, is demonstrated proved by the linear dependence obtained between the apparent parameters and the reaction time. The method permitted the values of the intrinsic parameters (enzyme specific activity and Michaelis-Menten constants of both substrates to be obtained for the system under study and was checked with experimental reaction rate data for the soybean peroxidase/phenol/hydrogen peroxide system.
Owhondah, Raymond O; Walker, Mark; Ma, Lin; Nimmo, Bill; Ingham, Derek B; Poggio, Davide; Pourkashanian, Mohamed
2016-06-01
Biochemical reactions occurring during anaerobic digestion have been modelled using reaction kinetic equations such as first-order, Contois and Monod which are then combined to form mechanistic models. This work considers models which include between one and three biochemical reactions to investigate if the choice of the reaction rate equation, complexity of the model structure as well as the inclusion of inhibition plays a key role in the ability of the model to describe the methane production from the semi-continuous anaerobic digestion of green waste (GW) and food waste (FW). A parameter estimation method was used to investigate the most important phenomena influencing the biogas production process. Experimental data were used to numerically estimate the model parameters and the quality of fit was quantified. Results obtained reveal that the model structure (i.e. number of reactions, inhibition) has a much stronger influence on the quality of fit compared with the choice of kinetic rate equations. In the case of GW there was only a marginal improvement when moving from a one to two reaction model, and none with inclusion of inhibition or three reactions. However, the behaviour of FW digestion was more complex and required either a two or three reaction model with inhibition functions for both ammonia and volatile fatty acids. Parameter values for the best fitting models are given for use by other authors. PMID:26961220
Rubin, Yoram; Cushey, Mark A.; Wilson, Amy
1997-11-01
This paper presents a concise methodology for estimating the moments of the breakthrough curves for tracers and reactive solutes in heterogeneous aquifers. Under some conditions these are also the temporal or travel time moments between a source and a given destination downstream. The temporal moments of tracers as well as instantaneously or kinetically sorbing solutes, characterized by linear isotherms, are expressed in terms of a few parameters which characterize the chemical reactions and the spatial distribution and correlation structure of the hydraulic conductivity. The chemical reaction parameters are assumed to be homogeneous. The estimated moments can also be made conditional to field measurements. Applications for the case of uniform mean flow are presented, but the general approach can be applied for other flow regimes such as injection-pumping well doublets. Physical and chemical nonequilibrium processes are represented by mobile-immobile domains and two-site models, respectively. The estimated temporal moments can be used for both predictive purposes as well as for interpretation of field experiments. These two objectives are pursued in this paper. A significant advantage of the solution is that it does not require the assumptions of Gaussianity or log Gaussianity of the travel times. Throughout the discussion the combined and relative effects of the mass transfer and kinetic parameters and the spatial variability of the conductivity on the travel time moments are evaluated.
DEFF Research Database (Denmark)
Steffansen, Bente; El-Sayed, F
membrane transporters. The aim was therefore to investigate if addition of E1S to the growth medium of Caco-2 cells before but not during the influx study, change the kinetic parameters of transporter-mediated influx of taurine and glutamate by respective TAUT and EAAT transporters. The results show that 4...... days pretreatment with E1S change the concentration dependent influx curves and Km for transporter mediated taurine and Km and Jmax for glutamate influx although the effects on Km and Jmax are not significant....
Barbero, N; Cauteruccio, S; Thakare, P; Licandro, E; Viscardi, G; Visentin, S
2016-10-01
Peptide nucleic acids (PNAs) are among the most interesting and versatile artificial structural mimics of nucleic acids and exhibit peculiar and important properties (i.e. high chemical stability, and a high resistance to cellular enzymes and nucleases). Despite their unnatural structure, they are able to recognize and bind DNA and RNA in a very high, specific and selective manner. One of the most popular, easy and reliable method to measure the stability of PNA-DNA hybrid systems is the melting temperature but the thermodynamic data are obtained using a big quantity of materials failing to provide information on the kinetics of the interaction. In the present work, the PNA decamer 6, with the TCACTAGATG sequence of nucleobases, and the corresponding fluorescent PNA-FITU (fluorescein isothiourea) decamer 8 were synthesized with standard manual Boc-based chemistry. The interaction of the PNA-FITU with parallel and antiparallel DNA has been studied by stopped-flow fluorescence, which is proposed as an alternative technique to obtain the kinetic parameters of the binding. The great advantage of using the stopped-flow technique is the possibility of studying the kinetics of the PNA-DNA duplex formation in a physiological environment. In particular, fluorescence stopped-flow technique has been exploited to compare the affinity of two PNA-DNA duplexes since it can discriminate between parallel and antiparallel DNA binding.
Fouchard, Swanny; Pruvost, Jérémy; Degrenne, Benoit; Titica, Mariana; Legrand, Jack
2009-01-01
Chlamydomonas reinhardtii is a green microalga capable of turning its metabolism towards H2 production under specific conditions. However this H2 production, narrowly linked to the photosynthetic process, results from complex metabolic reactions highly dependent on the environmental conditions of the cells. A kinetic model has been developed to relate culture evolution from standard photosynthetic growth to H2 producing cells. It represents transition in sulfur-deprived conditions, known to lead to H2 production in Chlamydomonas reinhardtii, and the two main processes then induced which are an over-accumulation of intracellular starch and a progressive reduction of PSII activity for anoxia achievement. Because these phenomena are directly linked to the photosynthetic growth, two kinetic models were associated, the first (one) introducing light dependency (Haldane type model associated to a radiative light transfer model), the second (one) making growth a function of available sulfur amount under extracellular and intracellular forms (Droop formulation). The model parameters identification was realized from experimental data obtained with especially designed experiments and a sensitivity analysis of the model to its parameters was also conducted. Model behavior was finally studied showing interdependency between light transfer conditions, photosynthetic growth, sulfate uptake, photosynthetic activity and O2 release, during transition from oxygenic growth to anoxic H2 production conditions.
Energy Technology Data Exchange (ETDEWEB)
Dill, Eric D.; Folmer, Jacob C.W.; Martin, James D. [NCSU
2013-12-05
A series of simulations was performed to enable interpretation of the material and physical significance of the parameters defined in the Kolmogorov, Johnson and Mehl, and Avrami (KJMA) rate expression commonly used to describe phase boundary controlled reactions of condensed matter. The parameters k, n, and t_{0} are shown to be highly correlated, which if unaccounted for seriously challenge mechanistic interpretation. It is demonstrated that rate measurements exhibit an intrinsic uncertainty without precise knowledge of the location and orientation of nucleation with respect to the free volume into which it grows. More significantly, it is demonstrated that the KJMA rate constant k is highly dependent on sample size. However, under the simulated conditions of slow nucleation relative to crystal growth, sample volume and sample anisotropy correction affords a means to eliminate the experimental condition dependence of the KJMA rate constant, k, producing the material-specific parameter, the velocity of the phase boundary, v_{pb}.
Energy Technology Data Exchange (ETDEWEB)
Bell, J.E.; Leone, A.; Bell, E.T.
1986-05-01
A glucosyltransferase, forming a predominantly al-6 linked glucan, was partially purified from the culture filtrate of S. mutans GS-5. The kinetic properties of the enzyme, assessed using the transfer of /sup 14/C glucose from sucrose into total glucan, were studied at pH values from pH 3.5 to 6.5. From the dependence of km on pH, a group with pKa = 5.5 must be protonated to maximize substrate binding. From plots of V/sub max/ vs pH two groups, with pKa's of 4.5 and 5.5 were indicated. The results suggest the involvement of either two carboxyl groups (one protonated, one unprotonated in the native enzyme) or a carboxyl group (unprotonated) and some other protonated group such as histidine, cysteine. Chemical modification studies showed that Diethylyrocarbonate (histidine specific) had no effect on enzyme activity while modification with p-phydroxy-mercuribenzoate or iodoacetic acid (sulfhydryl reactive) and carbodimide reagents (carboxyl specific) resulted in almost complete inactivation. Activity loss was dependent upon time of incubation and reagent concentration. The disaccharide lylose, (shown to be an inhibitor of the enzyme with similar affinity to sucrose) offers no protection against modification by the sulfhydryl reactive reagents.
Enitan S. Balogun; John B. Durosanya; Sarafadeen O. Kareem; Abideen I. Adeogun
2012-01-01
Biosorption and bioaccumulation of Lead ions (Pb(II)) by Trichoderma longibrachiatum were investigated in a batch system. The effects of some important parameters such as pH, initial metal concentration, temperature and inoculum concerntration on biosorption capacity were also studied. The maximum biosorption capacity of Trichoderma longibrachiatum was at 25 ppm of lead, showed 100 % removal at pH 7 and 25 oC after fifteen days. Biosorption equilibrium was established in 150 minutes. The proc...
Wibowo, Scheling; Grauwet, Tara; Santiago, Jihan Santanina; Tomic, Jovana; Vervoort, Liesbeth; Hendrickx, Marc; Van Loey, Ann
2015-11-15
In view of understanding colour instability of pasteurised orange juice during storage, to the best of our knowledge, this study reports for the first time in a systematic and quantitative way on a range of changes in specific quality parameters as a function of time and as well as temperature (20-42 °C). A zero-order (°Brix, fructose, glucose), a first-order (vitamin C), a second-order (sucrose) and a fractional conversion model (oxygen) were selected to model the evolution of the parameters between parentheses. Activation energies ranged from 22 to 136 kJ mol(-1), HMF formation being the most temperature sensitive. High correlations were found between sugars, ascorbic acid, their degradation products (furfural and HMF) and total colour difference (ΔE(∗)). Based on PLS regression, the importance of the quality parameters for colour degradation was ranked relatively among each other: the acid-catalysed degradation of sugars and ascorbic acid degradation reactions appeared to be important for browning development in pasteurised orange juice during ambient storage.
International Nuclear Information System (INIS)
The effectiveness of the VVER-1000 reactor scram system is analyzed using ionization chamber currents with different sets of kinetic parameters with allowance for the isotopic composition in the calculation of these parameters. The most “correct, aesthetically acceptable” results are obtained using the eight-group constants of the ROSFOND (BNAB-RF) library. The difference between the maximum and minimum values of the scram system effectiveness calculated with different sets of kinetic parameters slightly exceeds 2β. The problems of introducing corrections due to spatial effects are not considered in this study.
Energy Technology Data Exchange (ETDEWEB)
Zizin, M. N., E-mail: zizin@adis.vver.kiae.ru [Russian Research Centre Kurchatov Institute (Russian Federation); Zizina, S. N.; Kryakvin, L. V.; Pitilimov, V. A.; Tereshonok, V. A. [JSC VNIIAES (Russian Federation)
2011-12-15
The effectiveness of the VVER-1000 reactor scram system is analyzed using ionization chamber currents with different sets of kinetic parameters with allowance for the isotopic composition in the calculation of these parameters. The most 'correct, aesthetically acceptable' results are obtained using the eight-group constants of the ROSFOND (BNAB-RF) library. The difference between the maximum and minimum values of the scram system effectiveness calculated with different sets of kinetic parameters slightly exceeds 2{beta}. The problems of introducing corrections due to spatial effects are not considered in this study.
Jayasudha, S.; Madhukumar, K.; Nair, C. M. K.; Nair, Resmi G.; Anandakumar, V. M.; Elias, Thayal Singh
2016-02-01
Nanostructured SrSO4:Eu phosphors with high thermoluminescence (TL) emission temperatures have been synthesized through a controlled chemical precipitation method. Structural analysis and TL studies under both γ-ray and X-ray excitations were done. The phosphors were characterized using Powder X-ray diffraction, X-ray photoelectron spectroscopy, SEM, TEM, thermogravimetry, UV-VIS and photoluminescence studies. The average crystallite size estimated using PXRD data is found to be around 40 nm. XPS and PL studies reveal that Eu2 + ions are the luminescence emission centres in the phosphor. The phosphor is found to be highly TL sensitive to both γ-rays and X-rays with very high emission temperature which is not reported so far. The emission behaviour is suitable for environmental radiation dosimetry applications. The TL glow curve shows well-defined isolated high temperature emission peak at 312 °C under 2 Gy γ-excitation and 284 °C for low energy diagnostic X-ray irradiation and 271 °C for high energy therapeutic X-rays. Chen's peak shape method is applied to obtain the kinetic parameters behind the TL emission. The TL mechanism is found to follow second order kinetics, suggesting the probability of re-trapping of charge carriers.
Energy Technology Data Exchange (ETDEWEB)
Marozzi, C.A.; Chialvo, A.C. [Universidad Nacional del Litoral, Santiago del Estero, Santa Fe (AR). Programa de Electroquimica Aplicada e Ingenieria Electroquimica (PRELINE), Facultad de Ingenieria Quimica; Canto, M.R.; Costanza, V. [Instituto de Desarrollo Tecnologico para la Industria Quimica (INTEC), Universidad Nacional del Litoral-Consejo Nacional de Investigaciones Cientificas y Tecnicas, Gueemes, Santa Fe (Argentina)
2005-11-01
The use of the voltammetric response j{sup vol}({eta}) of a potentiodynamic sweep at a slow scan rate v{sub s} in place of a steady state polarization curve j{sup ss}({eta}) for the determination of the kinetic parameters of the hydrogen evolution reaction is analyzed. It is proposed to consider j{sup vol}({eta},v{sub s}){approx_equal}j{sup ss}({eta}) when the condition 0.99{<=}j{sup vol}({eta},v{sub s})/j{sup ss}({eta}){<=}1.01 is verified in the overpotentials range {eta} {<=} -0.05 V. It has been also established a simple relationship between the maximum admissible scan rate v{sub s} {sup max} and the equilibrium polarization resistance R{sub p}. Finally, the application of this criterion on different electrodes is described and discussed. (author)
Calculation of Reactor Kinetic Parameters with Monte Carlo Method%反应堆动态参数的蒙特卡罗计算研究
Institute of Scientific and Technical Information of China (English)
王冠博; 刘汉刚; 王侃; 刘永康; 曾和荣; 杨鑫
2012-01-01
Basic conceptions of kinetic parameters, including effective delayed neutron fraction (βeff), effective neutron generation time (Aeff) and a eigenvalue, and Monte Carlo calculation methods for these values are systematically introduced in this paper. Βeff is obtained with a "Prompt Method". Perturbation method is chosen to obtain Aeff. And then a eigenvalue is obtained by two ways, (I) prompt neutron density attenuation, in other words "direct simulation of time evolvement", (ii) indirect method using the result of kp and neutron generation time. Linear fitting is used to get the critical ac eigenvalues which match well with experimental ones. And uncertainties of kinetic parameters with different methods using Monte Carlo method are also analyzed.%介绍缓发中子有效份额(βeff)、有效中子代时间(∧eff)和α本征值的概念及其蒙特卡罗程序计算方法.采用Prompt Method方法计算得到βeff;微扰法得到∧eff；采用瞬发中子密度衰减直接拟合法和间接求解法得到α本征值；将各种反应性状态下的α拟合得到临界α本征值,并与实验测量的α,值进行比对,结果符合很好；并对动态参数蒙特卡罗程序计算的各种方法进行不确定度分析.
Directory of Open Access Journals (Sweden)
Y. Rudich
2005-04-01
Full Text Available Aerosols and clouds play central roles in atmospheric chemistry and physics, climate, air pollution, and public health. The mechanistic understanding and predictability of aerosol and cloud properties, interactions, transformations, and effects are, however, still very limited. This is due not only to the limited availability of measurement data, but also to the limited applicability and compatibility of model formalisms used for the analysis, interpretation, and description of heterogeneous and multiphase processes. To support the investigation and elucidation of atmospheric aerosol and cloud surface chemistry and gas-particle interactions, we present a comprehensive kinetic model framework with consistent and unambiguous terminology and universally applicable rate equations and parameters. It allows to describe mass transport and chemical reactions at the gas-particle interface and to link aerosol and cloud surface processes with gas phase and particle bulk processes in systems with multiple chemical components and competing physicochemical processes. The key elements and essential aspects of the presented framework are: a simple and descriptive double-layer surface model (sorption layer and quasi-static layer; straightforward flux-based mass balance and rate equations; clear separation of mass transport and chemical reactions; well-defined rate parameters (uptake and accommodation coefficients, reaction and transport rate coefficients; clear distinction between gas phase, gas-surface, and surface-bulk transport (gas phase diffusion correction, surface and bulk accommodation; clear distinction between gas-surface, surface layer, and surface-bulk reactions (Langmuir-Hinshelwood and Eley-Rideal mechanisms; mechanistic description of concentration and time dependencies; flexible inclusion/omission of chemical species and physicochemical processes; flexible convolution/deconvolution of species and processes; and full compatibility with traditional
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
A comparative study on the photosynthetic parameters among intergeneric progenies derived from Oryza sativa L.×Sorghum vulgare L., its maternal parent Gui 630 and commercial 3-line hybrid rice Shanyou 63 in pot experiment in greenhouse was conducted. The morphological and photosynthetic characters of canopy leaves and chlorophyll fluorescence kinetic parameters including Fv/Fm, Fv/F0, photochemical quenching coefficient and non-photochemical coefficient of canopy leaves of 3 varieties were measured. The results showed the progeny, Yuanyou 1, derived from an intergeneric cross of rice and sorghum possesses better canopy spatial architecture with thicker, heavier and bigger canopy leaf than its maternal parent Gui 630. Higher photosynthetic rate due to higher chlorophyll content, higher primary energy transformation efficiency, potential of PSII and non-photochemical quenching coefficient (qE) were also measured in Yuanyou 1. These explain partly why the intergeneric progeny has higher biomass production, and better tolerance to adverse conditions and higher field yields even under stress conditions.
Boller, A J; Thomas, P J; Cavanaugh, C M; Scott, K M
2015-01-01
The cosmopolitan, bloom-forming diatom, Skeletonema costatum, is a prominent primary producer in coastal oceans, fixing CO2 with ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) that is phylogenetically distinct from terrestrial plant RubisCO. RubisCOs are subdivided into groups based on sequence similarity of their large subunits (IA-ID, II, and III). ID is present in several major oceanic primary producers, including diatoms such as S. costatum, coccolithophores, and some dinoflagellates, and differs substantially in amino acid sequence from the well-studied IB enzymes present in most cyanobacteria and in green algae and plants. Despite this sequence divergence, and differences in isotopic discrimination apparent in other RubisCO enzymes, stable carbon isotope compositions of diatoms and other marine phytoplankton are generally interpreted assuming enzymatic isotopic discrimination similar to spinach RubisCO (IB). To interpret phytoplankton δ(13) C values, S. costatum RubisCO was characterized via sequence analysis, and measurement of its KCO2 and Vmax , and degree of isotopic discrimination. The sequence of this enzyme placed it among other diatom ID RubisCOs. Michaelis-Menten parameters were similar to other ID enzymes (KCO2 = 48.9 ± 2.8 μm; Vmax = 165.1 ± 6.3 nmol min(-1 ) mg(-1) ). However, isotopic discrimination (ε = [(12) k/(13) k - 1] × 1000) was low (18.5‰; 17.0-19.9, 95% CI) when compared to IA and IB RubisCOs (22-29‰), though not as low as ID from coccolithophore, Emiliania huxleyi (11.1‰). Variability in ε-values among RubisCOs from primary producers is likely reflected in δ(13) C values of oceanic biomass. Currently, δ(13) C variability is ascribed to physical or chemical factors (e.g. illumination, nutrient availability) and physiological responses to these factors (e.g. carbon-concentrating mechanisms). Estimating the importance of these factors from δ(13) C measurements requires an accurate ε-value, and a mass
Bisetti, Fabrizio; El Morsli, Mbark
2014-01-01
The effects of an electric field on the collision rates, energy exchanges and transport properties of electrons in premixed flames are investigated via solutions to the Boltzmann kinetic equation. The case of high electric field strength, which results in high-energy, non-thermal electrons, is analysed in detail at sub-breakdown conditions. The rates of inelastic collisions and the energy exchange between electrons and neutrals in the reaction zone of the flame are characterised quantitatively. The analysis includes attachment, ionisation, impact dissociation, and vibrational and electronic excitation processes. Our results suggest that Townsend breakdown occurs for E/N = 140 Td. Vibrational excitation is the dominant process up to breakdown, despite important rates of electronic excitation of CO, CO2 and N2 as well as impact dissociation of O2 being apparent from 50 Td onwards. Ohmic heating in the reaction zone is found to be negligible (less than 2% of peak heat release rate) up to breakdown field strengths for realistic electron densities equal to 1010 cm-3. The observed trends are largely independent of equivalence ratio. In the non-thermal regime, electron transport coefficients are insensitive to mixture composition and approximately constant across the flame, but are highly dependent on the electric field strength. In the thermal limit, kinetic parameters and transport coefficients vary substantially across the flame due to the spatially inhomogeneous concentration of water vapour. A practical approach for identifying the plasma regime (thermal versus non-thermal) in studies of electric field effects on flames is proposed.
Bisetti, Fabrizio
2014-01-02
The effects of an electric field on the collision rates, energy exchanges and transport properties of electrons in premixed flames are investigated via solutions to the Boltzmann kinetic equation. The case of high electric field strength, which results in high-energy, non-thermal electrons, is analysed in detail at sub-breakdown conditions. The rates of inelastic collisions and the energy exchange between electrons and neutrals in the reaction zone of the flame are characterised quantitatively. The analysis includes attachment, ionisation, impact dissociation, and vibrational and electronic excitation processes. Our results suggest that Townsend breakdown occurs for E/N = 140 Td. Vibrational excitation is the dominant process up to breakdown, despite important rates of electronic excitation of CO, CO2 and N2 as well as impact dissociation of O2 being apparent from 50 Td onwards. Ohmic heating in the reaction zone is found to be negligible (less than 2% of peak heat release rate) up to breakdown field strengths for realistic electron densities equal to 1010 cm-3. The observed trends are largely independent of equivalence ratio. In the non-thermal regime, electron transport coefficients are insensitive to mixture composition and approximately constant across the flame, but are highly dependent on the electric field strength. In the thermal limit, kinetic parameters and transport coefficients vary substantially across the flame due to the spatially inhomogeneous concentration of water vapour. A practical approach for identifying the plasma regime (thermal versus non-thermal) in studies of electric field effects on flames is proposed. © 2014 Taylor & Francis.
Directory of Open Access Journals (Sweden)
Raziyeh Zandipak
2016-02-01
Full Text Available Background: Among different pollutants released into the environment, dyes are considered as one of the most dangerous contaminants. In recent years, magnetic nanomaterials have attracted much attention for their dye removal capacity. The aim of this study was to explore the adsorption kinetics of an anionic dye (Reactive Orange 13 (RO by NiFe2O4 nanoparticles (NiFe2O4 NPs under various conditions. Methods: NiFe2O4 nanoparticles (NiFe2O4 NPs were prepared and characterized by X-ray diffraction (XRD, transmission electronic microscopy (TEM, pHpzc and BET methods. The adsorption characteristics of the NiFe2O4 NPs adsorbent were examined using Reactive Orange 13 as an adsorbate. The influences of parameters including pH, dose of adsorbent and contact time were investigated to find the optimum adsorption conditions. Results: Decreasing solution pH and increasing contact time were favorable for improving adsorption efficiency. The kinetic and isotherm data of RO adsorption on NiFe2O4 NPs were well fitted by pseudo-second-order and Langmuir models, respectively. Conclusion: The maximal adsorption capacity of RO was 243.9 mg g-1 at 25◦C and pH 3.0 and the adsorption of RO on the NiFe2O4 NPs follows a monolayer coverage model. NiFe2O4 NPs might be an effective and potential adsorbent for removing anionic dyes from aqueous solutions.
International Nuclear Information System (INIS)
Reliable 15N tracer substances for tracer kinetic determination of whole-body protein parameters in very small preterm infants are still a matter of intensive research, especially after some doubts have been raised about the validity of [15N]glycine, a commonly used 15N tracer. Protein turnover, synthesis, breakdown, and further protein metabolism data were determined by a paired comparison in four preterm infants. Their post-conceptual age was 32.2 +/- 0.8 weeks, and their body weight was 1670 +/- 181 g. Tracer substances applied in this study were a [15N]amino acid mixture (Ia) and [15N]glycine (Ib). In a second group of three infants with a post conceptual age of 15N-labeled 32.0 +/- 1.0 weeks and a body weight of 1,907 +/- 137 g, yeast protein hydrolysate (II) was used as a tracer substance. A three-pool model was employed for the analysis of the data. This model takes into account renal and fecal 15N losses after a single 15N pulse. Protein turnovers were as follows: 11.9 +/- 3.1 g kg-1 d-1 (Ia), 16.2 +/- 2.5 g kg-1 d-1 (Ib), and 10.8 +/- 3.0 g kg-1 d-1 (II). We were able to demonstrate an overestimation of the protein turnover when Ib was used. There was an expected correspondence in the results obtained from Ia and II. The 15N-labeled yeast protein hydrolysate is a relatively cheap tracer that allows reliable determination of whole-body protein parameters in very small preterm infants
Directory of Open Access Journals (Sweden)
A. M. Rodrigues
2013-01-01
Full Text Available Crystallization kinetics parameters of a stoichiometric glass with the composition Li1.5Al0.5Ge1.5(PO43 were investigated by subjecting parallelepipedonal samples (3 × 3 × 1.5 mm to heat treatment in a differential scanning calorimeter at different heating rates (3, 5, 8 and 10 °C/min. The data were analyzed using Ligero's and Kissinger's methods to determine the activation energy (E of crystallization, which yielded, respectively, E = 415 ± 37 kJ/mol and 378 ± 19 kJ/mol. Ligero's method was also employed to calculate the Avrami coefficient (n, which was found to be n = 3.0. A second set of samples were heat-treated in a tubular furnace at temperatures above the glass transition temperature, Tg, to induce crystallization. The X-ray diffraction analysis of these samples indicated the presence of LiGe2(PO43 which displays a NASICON-type structure. An analysis by optical microscopy revealed the presence of spheric crystals located primarily in the volume, in agreement with the crystallization mechanism predicted by the Avrami coefficient.
Huang, Limao; Liu, Jingyong; He, Yao; Sun, Shuiyu; Chen, Jiacong; Sun, Jian; Chang, KenLin; Kuo, Jiahong; Ning, Xun'an
2016-10-01
Thermodynamics and kinetics of sewage sludge (SS) and water hyacinth (WH) co-combustion as a blend fuel (SW) for bioenergy production were studied through thermogravimetric analysis. In CO2/O2 atmosphere, the combustion performance of SS added with 10-40wt.% WH was improved 1-1.97 times as revealed by the comprehensive combustion characteristic index (CCI). The conversion of SW in different atmospheres was identified and their thermodynamic parameters (ΔH,ΔS,ΔG) were obtained. As the oxygen concentration increased from 20% to 70%, the ignition temperature of SW decreased from 243.1°C to 240.3°C, and the maximum weight loss rate and CCI increased from 5.70%·min(-1) to 7.26%·min(-1) and from 4.913%(2)·K(-3)·min(-2) to 6.327%(2)·K(-3)·min(-2), respectively, which corresponded to the variation in ΔS and ΔG. The lowest activation energy (Ea) of SW was obtained in CO2/O2=7/3 atmosphere. PMID:27416513
Becker, P; Abu-Reesh, I; Markossian, S; Antranikian, G; Märkl, H
1997-08-01
A thermostable lipase was produced in continuous cultivation of a newly isolated thermophilic Bacillus sp. strain IHI-91 growing optimally at 65 degrees C. Lipase activity decreased with increasing dilution rate while lipase productivity showed a maximum of 340 U l-1 h-1 at a condition rate of 0.4 h-1. Lipase productivity was increased by 50% compared to data from batch fermentations. Up to 70% of the total lipase activity measured was associated to cells and by-products or residual substrate. Kinetic and stoichiometric parameters for the utilisation of olive oil were determined. The maximal biomass output method led to a saturation constant Ks of 0.88 g/l. Both batch growth data and a washout experiment yielded a maximal specific growth rate, mu max, of 1.0 h-1. Oxygen uptake rates of up to 2.9 g l-1 h-1 were calculated and the yield coefficient, Y X/O, was determined to be 0.29 g dry cell weight/g O2. From an overall material balance the yield coefficient, Y X/S, was estimated to be 0.60 g dry cell weight/g olive oil.
Institute of Scientific and Technical Information of China (English)
KatsuyoshiShimizu; 唐建军; 陈欣
2002-01-01
A comparative study on the photosynthetic parameters among intergeneric progenies derived from Oryza sativa L.× Sorghum vulgare L. , its maternal parent Gui 630 and commercial 3-line hybrid rice Shanyou 63 in pot experiment in greenhouse was conducted. The morphological and photosynthetic characters of canopy leaves and chlorophyll fluorescence kinetic pm'mneters including Fv/Fm, Fv/F0, photochemical quenching coefficient and non-photochemical coefficient of canopy leaves of 3 varieties were measured. The results showed the progeny, Yuanyou 1, derived from an intergeneric cross of rice and sorghum possesses better canopy spatial architecture with thicker, heavier and bigger canopy leaf than its maternal parent Gui 630.Higher photosynthetic rate due to higher chlorophyll content, higher primary energy transformation efficiency,potential of PSII and non-photochemieal quenching coefficient (qE) were also measured in Yuanyou 1. These explain partly why the intergeneric progeny has higher biomass production, and better tolerance to adverse conditions and higher field yields even under stress conditions.
Indian Academy of Sciences (India)
Santosh Kumar Verma; Kallol K Ghosh
2013-07-01
Reverse micelles (RMs) of sodium 1,4-bis(2-ethylhexyl)sulphosuccinate (AOT) in nonpolar organic solvents are widely known to have very high solubilization power for water. The method is applied to the hydrolysis of -nitrophenyl acetate (PNPA) catalysed by -chymotrypsin (-CT) in AOT/isooctane/buffer RMs. The increase in -CT activity and stability was an optimum at wo ([H2O]/[AOT]) = 10, z [Isooctane]/[AOT]) = 5. Three typical surfactants were selected based on their head group charges: a non-ionic surfactant Triton-X 100 and two zwitterionic sulphobetaine surfactants of the type CH2+1N+Me2 (CH2)3 SO$^{−}_{3}$ (n = 10; SB3-10, n = 16; SB3-16). The kinetic parameters (such as cat and M) of the -CT at 27°C were determined and compared in the absence and presence of three surfactants. The effect of chain length of zwitterionic surfactant (SB3-10 and SB3-16) on the enzymatic efficacy of -CT as a function of mixed surfactant addition has been investigated in AOT/isooctane RMs at pH 7.75.
Kitahama, Yasutaka; Sakaguchi, Yoshio
2008-01-17
We investigated the quantum beats, the oscillation between singlet and triplet states of radical pairs induced by the microwave field resonant to one of the component radicals. They were observed as the alternation of the yields of the component radicals by a nanosecond time-resolved optical absorption with the X-band (9.15 GHz) resonant microwave pulse. This technique was applied to the photochemical reaction of benzophenone, benzophenone-d(10), and benzophenone-carbonyl-(13)C in a sodium dodecylsulfate micellar solution with a step-by-step increase of the resonant microwave pulse width. The yields of the component radicals showed alternation with an increase of the microwave pulse width. This indicates that the radical pair retains spin coherence in the micellar solution. The magnetic isotope effect on the amplitude of the quantum beat was observed. The MW effect on the quantum beat of BP-(13)C decreases from 80% to 60% of that of BP by irradiation of the pi-pulse MW due to spin-locking. The kinetic parameters were also determined using the X- or Ku-band (17.44 GHz) region. They are almost similar to each other except for the intersystem recombination rate in the system of BP-(13)C, which may be slightly higher than those in other systems.
Tan, R. P.; Carrey, J.; Respaud, M.
2014-12-01
Understanding the influence of dipolar interactions in magnetic hyperthermia experiments is of crucial importance for fine optimization of nanoparticle (NP) heating power. In this study we use a kinetic Monte Carlo algorithm to calculate hysteresis loops that correctly account for both time and temperature. This algorithm is shown to correctly reproduce the high-frequency hysteresis loop of both superparamagnetic and ferromagnetic NPs without any ad hoc or artificial parameters. The algorithm is easily parallelizable with a good speed-up behavior, which considerably decreases the calculation time on several processors and enables the study of assemblies of several thousands of NPs. The specific absorption rate (SAR) of magnetic NPs dispersed inside spherical lysosomes is studied as a function of several key parameters: volume concentration, applied magnetic field, lysosome size, NP diameter, and anisotropy. The influence of these parameters is illustrated and comprehensively explained. In summary, magnetic interactions increase the coercive field, saturation field, and hysteresis area of major loops. However, for small amplitude magnetic fields such as those used in magnetic hyperthermia, the heating power as a function of concentration can increase, decrease, or display a bell shape, depending on the relationship between the applied magnetic field and the coercive/saturation fields of the NPs. The hysteresis area is found to be well correlated with the parallel or antiparallel nature of the dipolar field acting on each particle. The heating power of a given NP is strongly influenced by a local concentration involving approximately 20 neighbors. Because this local concentration strongly decreases upon approaching the surface, the heating power increases or decreases in the vicinity of the lysosome membrane. The amplitude of variation reaches more than one order of magnitude in certain conditions. This transition occurs on a thickness corresponding to approximately
Energy Technology Data Exchange (ETDEWEB)
Miyakawa, H. [Sasebo College of Technology, Nagasaki (Japan); Shiraishi, F. [Kyushu Institute of Technology, Fukuoka (Japan)
1998-05-10
The effect of nonuniform activity distribution in a porous support on the apparent kinetic parameters, Vm{sup app} and Km{sup app}, of a packed-bed immobilized enzyme reactor has been theoretically investigated. Vm{sup app} and Km{sup app} increase with the increase of external diffusional resistance, regardless of the type of nonuniform activity distribution. As the external diffusional resistance becomes significant, the apparent kinetic parameters became less dependent on the substrate concentration at the reactor inlet. Like the case of diffusional resistance or electrostatic field, the nonuniform activity distribution had a significant effect on Km{sup app}. 7 refs., 3 figs.
DEFF Research Database (Denmark)
Sales-Cruz, Mauricio; Heitzig, Martina; Cameron, Ian;
2011-01-01
In this chapter the importance of parameter estimation in model development is illustrated through various applications related to reaction systems. In particular, rate constants in a reaction system are obtained through parameter estimation methods. These approaches often require the application...... of optimisation techniques coupled with dynamic solution of the underlying model. Linear and nonlinear approaches to parameter estimation are investigated. There is also the application of maximum likelihood principles in the estimation of parameters, as well as the use of orthogonal collocation to...... generate a set of algebraic equations as the basis for parameter estimation.These approaches are illustrated using estimations of kinetic constants from reaction system models....
Energy Technology Data Exchange (ETDEWEB)
Salloum, Maher N.; Shugard, Andrew D.; Kanouff, Michael P.; Gharagozloo, Patricia E.
2013-03-01
Modeling of reacting flows in porous media has become particularly important with the increased interest in hydrogen solid-storage beds. An advanced type of storage bed has been proposed that utilizes oxidation of uranium hydride to heat and decompose the hydride, releasing the hydrogen. To reduce the cost and time required to develop these systems experimentally, a valid computational model is required that simulates the reaction of uranium hydride and oxygen gas in a hydrogen storage bed using multiphysics finite element modeling. This SAND report discusses the advancements made in FY12 (since our last SAND report SAND2011-6939) to the model developed as a part of an ASC-P&EM project to address the shortcomings of the previous model. The model considers chemical reactions, heat transport, and mass transport within a hydride bed. Previously, the time-varying permeability and porosity were considered uniform. This led to discrepancies between the simulated results and experimental measurements. In this work, the effects of non-uniform changes in permeability and porosity due to phase and thermal expansion are accounted for. These expansions result in mechanical stresses that lead to bed deformation. To describe this, a simplified solid mechanics model for the local variation of permeability and porosity as a function of the local bed deformation is developed. By using this solid mechanics model, the agreement between our reacting bed model and the experimental data is improved. Additionally, more accurate uranium hydride oxidation kinetics parameters are obtained by fitting the experimental results from a pure uranium hydride oxidation measurement to the ones obtained from the coupled transport-solid mechanics model. Finally, the coupled transport-solid mechanics model governing equations and boundary conditions are summarized and recommendations are made for further development of ARIA and other Sandia codes in order for them to sufficiently implement the model.
Study on Kinetic Parameters of Degradating Phenol by Photosynthetic Bacteria%光合细菌降解苯酚的动力学参数研究
Institute of Scientific and Technical Information of China (English)
刘宏芳
2011-01-01
苯酚是炼焦（油）、塑料、化工等行业生产过程中的主要污染物。随着经济的快速发展,各类含酚废水已经严重威胁着人类的生存环境。利用微生物处理含酚废水是一种经济有效且无二次污染的方法。本文主要研究了光合细菌-沼泽红假单胞菌降解含酚废水的动力学参数。实验结果表明,沼泽红假单胞菌对含酚废水具有很好的降解性能,正常状态下,该菌最大比生长速率μmax为8.00 mg/g.h,半速率常数Ks为247.92 mg/L,产率系数Y为5.88 mg/mg,内源呼吸系数Kd为0.29 d-1。%Phenol is the significant raw material or midst substance of coking plant,oil refining,plastic and medicine composing etc.More and more waste water containing phenol without treatment is threatening the environment heavily with the rapid development of economy.The method of microorganism biodegradation is economic and effective to treat with phenol waste water without second pollution.The kinetic parameters of the degradation of the phenol were studied with Rhodopseudomonas palustri.The experimental results show that Rhodopseudomonas palustris had excellent biodegradability for phenol wastewater.Under normal conditions,μmax is 8.00 mg/g·h,Ks is 247.92 mg/L,Y is 5.88 mg/mg and Kd is 0.29 d-1.
Cristiane Mita; Vanessa Hitomi Sugahara; Jo I Wu; Pedro Manoel Oliveira Janeiro Neves; Dalva Tomoe Miyagui; Geni Varéa-Pereira; Danieli Cristina Sassá; Evelyn Kamogawa
2008-01-01
Entomopathogenic fungus Beauveria bassiana is currently used as a biocontrol agent for agricultural pests. The infection process involves extracellular enzymes such as proteases and chitinases that degrade the cuticle of the insects. The objective of this work was to evaluate kinetic parameters of pH, temperature, ionic concentration and time of reaction on chitinases activity. The fungus B. bassiana CG432 was cultivated on coffee berry borer Hypothenemus hampei (Ferrari) and the conidia grow...
Energy Technology Data Exchange (ETDEWEB)
Gallegos, A.A. [CICATA-IPN, Legaria 694, Col. Irrigacion, 11500 Mexico D.F. (Mexico); Khaidukov, N.M. [Kurnakov Institute of General and Inorganic Chemistry, Moscow (Russian Federation); Azorin, J. [UAM-I, 09340 Mexico D.F. (Mexico)
2005-07-01
In this work the K{sub 2}Y doped materials with percentages of 0.01 and 0.2 of F{sub 5} and, 0.8 and 0.99 of Tb{sup 3+} were studied to determine the kinetic parameters (activation energy and frequency factor) of TL peaks with the purpose of comparing those sensitive qualities of the materials at the doping with TR and their candidacy for tests of TL dosimetry (linearity of the response with the absorbed dose and the reproducibility of the measures of the dose). The samples were irradiated with a beta source of {sup 90} Sr/{sup 90} Y, to ambient temperature, giving its a dose of 236.6 mGy, later the kinetic parameters with different experimental procedures were determined: isothermal decay to ambient temperature and erased of peaks not desired to greater temperature than the ambient. The glow curves (TL curves) were obtained with an TL analyzer Harshaw 4000, with interface to CPU for the handling of the data of the curves, which were treated with the curve form method and the models of: Chen first approach and Chen modified, corrected Lushchik approach and Grossweiner approach, to calculate the kinetic parameters of the sample. (Author)
Energy Technology Data Exchange (ETDEWEB)
Alca Ruiz, F.
1982-07-01
In this report one distribution of neutron counts obtained by a detector placed in a reactor is studied in order to be used in the determination of reactor kinetic parameters such as {beta}/{lambda} and reactivities. The parameters accuracy from this new method is compared with the Feynman and Mogilner method, based too in Reactor Neutron Noise Analysis. These three methods have been applied to JEN-2 reactor and the better accuracy and faster collection of experimental data give some interest to the new method which only requires a good footing code. (Author) 68 refs.
Kalenchuk, A. N.; Bogorodskii, S. E.; Bogdan, V. I.
2016-10-01
Comparative studies on the temperature dependence of the dehydrogenation of cis- and trans-isomers of perhydro- m-terphenyl are performed in a flow catalytic reactor. Rate constants and equilibrium constants of all elementary acts of this reaction are calculated on basis of experimental data using the KINET 0.8 program for the mathematical modeling of the kinetics of complex reactions. The resulting data indicate that perhydro- m-terphenyl cis- and trans-isomers structural differences have no appreciable effect on dehydrogenation.
Energy Technology Data Exchange (ETDEWEB)
Manjunatha, H.; Mahesh, K.C. [Chemistry Research Centre, S.S.M.R.V. Degree College, Jayanagar, Bangalore 560041 (India); Suresh, G.S., E-mail: sureshssmrv@yahoo.co.i [Chemistry Research Centre, S.S.M.R.V. Degree College, Jayanagar, Bangalore 560041 (India); Venkatesha, T.V. [Department of Chemistry, Kuvempu University, Jnanasahyadri, Shankaraghatta 577451 Shimoga (India)
2011-01-01
In this work, we report a basic study on the mechanism of lithium ion de-insertion/insertion process from/into LiMn{sub 2}O{sub 4} cathode material in aqueous Li{sub 2}SO{sub 4} solution using electrochemical impedance spectroscopy (EIS). An equivalent circuit distinguishing the kinetic parameters of lithium ion de-insertion/insertion is used to simulate the experimental impedance data. The fitting results are in good agreement with the experimental results and the parameters of the kinetic process of Li{sup +} de-insertion and insertion in LiMn{sub 2}O{sub 4} at different potentials during charge and discharge are obtained using the same circuit. The results indicate that the de-insertion/insertion behavior of lithium ions at LiMn{sub 2}O{sub 4} cathode in Li{sub 2}SO{sub 4} aqueous solution is similar to that reported in the organic electrolytes. The charge transfer resistance (R{sub ct}), warburg resistance, double layer capacitance and chemical diffusion coefficient (D{sub Li}{sup +}) vary with potentials during de-insertion/insertion processes. R{sub ct} is lowest at the CV peak potentials and the important kinetic parameter, D{sub Li}{sup +} exhibits two distinct minima at potentials corresponding to CV peaks during de-insertion-insertion and it was found to be between 10{sup -8} and 10{sup -10} cm{sup 2} s{sup -1}during lithium de-insertion/insertion processes.
Song, Chengjie; Wang, Liping; Ren, Jie; Lv, Bo; Sun, Zhonghao; Yan, Jing; Li, Xinying; Liu, Jingjing
2016-02-01
The photodegradation of diethyl phthalate (DEP) by UV/H2O2 and UV/TiO2 is studied. The DEP degradation kinetics and multiple crucial factors effecting the clearance of DEP are investigated, including initial DEP concentration ([DEP]0), initial pH values (pH0), UV light intensity, anions (Cl(-), NO(3-), SO4 (2-), HCO3 (-), and CO3 (2-)), cations (Mg(2+), Ca(2+), Mn(2+), and Fe(3+)), and humic acid (HA). Total organic carbon (TOC) removal is tested by two treatments. And, cytotoxicity evolution of DEP degradation intermediates is detected. The relationship between molar ratio ([H2O2]/[DEP] or [TiO2]/[DEP]) and degradation kinetic constant (K) is also studied. And, the cytotoxicity tests of DEP and its degradation intermediates in UV/H2O2 and UV/TiO2 treatments are researched. The DEP removal efficiency of UV/H2O2 treatment is higher than UV/TiO2 treatment. The DEP degradation fitted a pseudo-first-order kinetic pattern under experimental conditions. The K linearly related with molar ratio in UV/H2O2 treatment while nature exponential relationship is observed in the case of UV/TiO2. However, K fitted corresponding trends better in H2O2 treatment than in TiO2 treatment. The Cl(-) is in favor of the DEP degradation in UV/H2O2 treatment; in contrast, it is disadvantageous to the DEP degradation in UV/TiO2 treatment. Other anions are all disadvantageous to the DEP degradation in two treatments. Fe(3+) promotes the degradation rates significantly. And, all other cations in question inhibit the degradation of DEP. HA hinders DEP degradation in two treatments. The intermediates of DEP degradation in UV/TiO2 treatment are less toxic to biological cell than that in UV/H2O2 treatment.
A.M. Rodrigues; J. L. Narváez-Semanate; A. A. Cabral; A. C. M. Rodrigues
2013-01-01
Crystallization kinetics parameters of a stoichiometric glass with the composition Li1.5Al0.5Ge1.5(PO4)3 were investigated by subjecting parallelepipedonal samples (3 × 3 × 1.5 mm) to heat treatment in a differential scanning calorimeter at different heating rates (3, 5, 8 and 10 °C/min). The data were analyzed using Ligero's and Kissinger's methods to determine the activation energy (E) of crystallization, which yielded, respectively, E = 415 ± 37 kJ/mol and 378 ± 19 kJ/mol. Ligero's method ...
Energy Technology Data Exchange (ETDEWEB)
De Micco, G., E-mail: demiccog@cab.cnea.gov.ar [Comision Nacional de Energia Atomica (C.N.E.A.), Avenida Bustillo 9500, 8400 San Carlos de Bariloche (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina); Universidad Nacional de Cuyo, Instituto Balseiro, Avenida Bustillo 9500, 8400 San Carlos de Bariloche (Argentina); Carignan, M. [Comision Nacional de Energia Atomica (C.N.E.A.), Avenida Bustillo 9500, 8400 San Carlos de Bariloche (Argentina); Canavesio, C.A. [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina); Bohe, A.E. [Comision Nacional de Energia Atomica (C.N.E.A.), Avenida Bustillo 9500, 8400 San Carlos de Bariloche (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina); Universidad Nacional del Comahue, Centro Regional Universitario Bariloche, 8400 San Carlos de Bariloche (Argentina)
2012-09-10
Highlights: Black-Right-Pointing-Pointer Kinetics of chlorination of MoO{sub 3} was studied by thermogravimetry. Black-Right-Pointing-Pointer The starting temperature for the reaction is determined at about 770 K. Black-Right-Pointing-Pointer An average activation energy of 211 kJ mol{sup -1} for the chlorination was determined. Black-Right-Pointing-Pointer A reaction order of 1 with respect to chlorine partial pressure was obtained. Black-Right-Pointing-Pointer A complete reaction rate equation was formulated for two MoO{sub 3} sample morphologies. - Abstract: In this work the kinetics of the chlorination of molybdenum trioxide has been studied by thermogravimetry between 798 and 873 K. The starting temperature for the reaction of MoO{sub 3} with chlorine is determined at about 770 K. The influence of gaseous flow rate, sample mass, temperature, and chlorine partial pressure in the reaction rate is analyzed for two MoO{sub 3} samples having different particle size and morphology. The experimental conditions for chemical control of the reaction rate were established for both types of samples. An average activation energy of 211 kJ mol{sup -1} and a reaction order of 1 with respect to chlorine partial pressure were determined for the chlorination of MoO{sub 3} with gaseous chlorine. A complete rate equation was formulated that describes the reaction evolution of each type of solid.
Romero-González, Jaime; Gardea-Torresdey, Jorge L; Peralta-Videa, José R; Rodríguez, Elena
2005-01-01
This investigation reveals the capability of Agave lechuguilla for trivalent and hexavalent chromium removal from aqueous solutions. Experimentation included pH profile, time dependence, adsorption capacity (K(F) and Q(L)), adsorption intensity (n and R(L)) and saturation capacity (q(s)) studies. Batch experiments were conducted at 22( composite function)C to characterize and model the adsorption equilibrium as well as biomass adsorption rates. pH 4 was the optimum for Cr(III) binding, while Cr(VI) optimum binding was at pH 2. Time profile experiments indicated that the adsorption of Cr(VI) by lechuguilla biomass was time-dependent and that of Cr(III) was not. Kinetic models demonstrated that a pseudo-second order reaction model best described the kinetic data for Cr(VI). The adsorption isotherms showed that the binding pattern for Cr(VI) followed the Freundlich isotherm model, while that for Cr(III) followed the Langmuir isotherm. PMID:18365089
Sau, Sujay P.; Kumar, Pawan; Sharma, Pawan K.; Hrdlicka, Patrick J.
2012-01-01
Triplex forming oligonucleotides (TFOs) are the most commonly used approach for site-specific targeting of double stranded DNA (dsDNA). Important parameters describing triplex formation include equilibrium binding constants (K eq) and association/dissociation rate constants (k on and k off). The ‘fluorescent intercalator displacement replacement’ (FIDR) assay is introduced herein as an operationally simple approach toward determination of these parameters for triplexes involving TC-motif TFOs...
Directory of Open Access Journals (Sweden)
Jens B. Hafke
2013-07-01
Full Text Available Apart from a few using cut aphid stylets, no attempts have been made thus far to measure in vivo sucrose-uptake properties of sieve elements. We investigated the kinetics of sucrose uptake by single sieve elements and phloem parenchyma cells in Vicia faba plants. To this end, microelectrodes were inserted into free-lying phloem cells in the main vein of the youngest fully-expanded leaf, half-way along the stem, in the transition zone between the autotrophic and heterotrophic part of the stem, and in the root axis. A top-to-bottom membrane potential gradient of sieve elements was observed along the stem (-130 mV to -110 mV, while the membrane potential of the phloem parenchyma cells was stable (approx. -100 mV. In roots, the membrane potential of sieve elements dropped abruptly to -55 mV. Bathing solutions having various sucrose concentrations were administered and sucrose/H+-induced depolarisations were recorded. Data analysis by nonlinear least-square data fittings as well as by linear Eadie-Hofstee (EH -transformations pointed at biphasic Michaelis-Menten kinetics (2 MM, EH: Km1 1.2-1.8 mM, Km2 6.6-9.0 mM of sucrose uptake by sieve elements. However, Akaike’s Information Criterion (AIC favoured single MM kinetics. Using single MM as the best-fitting model, Km values for sucrose uptake by sieve elements decreased along the plant axis from 1 to 7 mM. For phloem parenchyma cells, higher Km values (EH: Km1 10 mM, Km2 70 mM as compared to sieve elements were found. In preliminary patch-clamp experiments with sieve-element protoplasts, small sucrose-coupled proton currents (-0.1 to -0.3 pA/ pF were detected in the whole-cell mode. In conclusion (a Km values for sucrose uptake measured by electrophysiology are similar to those obtained with heterologous systems, (b electrophysiology provides a useful tool for in-situ determination of Km values, (c As yet, it remains unclear if one or two uptake systems are involved in sucrose uptake by sieve
Energy Technology Data Exchange (ETDEWEB)
Basurto G, B.S
2002-07-01
The objective of this work, is the one of determining the kinetic parameters of the dosemeter of LiF: Mg, Cu, P + Ptfe; starting from the curves Tl obtained at being irradiated with alpha radiation ({alpha}), beta ({beta}) and gamma ({gamma}). As like to compare its sensitivity with each radiation type, considering the sensitivity of the TLD-100 as the unit. In the Chapter 1, the fundamental structure of the matter is described, making emphasis in the different radiation types, and their interaction with this. In the Chapter 2, the units are described but used in the dosimetry of the radiation. In the Chapter 3, the basic concepts of the phenomenon of Tl are described and those are explained characteristic of the deconvolution method to determine the kinetics of the one phenomenon. In the Chapter 4, the methodology is detailed that was used in the elaboration of this thesis work, describing the material Tl that were considered like reference, as well as the sources of ionizing radiation, with those that the dosemeters were irradiated and the equipment in the one that the curves Tl was obtained. Reference is made to the software used to carry out the deconvolution of the curves Tl that were obtained in the one experimental development. In the Chapter 5, the obtained results of this study are presented, showing the tables of homogenization of dosemeters and the reading of the same one; they are observed the curves Tl obtained to different radiation doses (alpha, beta and gamma), the intensity Tl in function of the dose. Also they are tabulated, the obtained results in the kinetic parameters of the three different study materials (TLD-100H, USA; TLD-100, USA and LiF: Mg, Cu, P + Ptfe developed in the l.N.l.N). They are analyzed shortly for each material Tl their sensitivity to the ionizing radiation as well as their kinetic parameters. The obtained results showed that the Tl dosemeters of LiF: Mg,Cu,P + Ptfe, they presented a bigger sensitivity that the TLD-100 when
Cong, Jiawei; Yun, Binfeng; Cui, Yiping
2013-08-26
By introducing the frequency tuning sensitivity, an analytical model based on equivalent LC circuit is developed for the relative frequency tuning range of THz semiconductor split-ring resonator (SRR). And the model reveals that the relative tuning range is determined by the ratio of the kinetic inductance to the geometric inductance (RKG). The results show that under the same carrier density variation, a larger RKG results in a larger relative tuning range. Based on this model, a stacked SRR-dimer structure with larger RKG compared to the single SRR due to the inductive coupling is proposed, which improves the relative tuning range effectively. And the results obtained by the simple analytical model agree well with the numerical FDTD results. The presented analytical model is robust and can be used to analyze the relative frequency tuning of other tunable THz devices.
THERMODYNAMIC AND KINETIC PARAMETERS OF MIXTURES DESULFURIZING THE MADE WITH CaO, MgO, SiO2 AND CaF2
Directory of Open Access Journals (Sweden)
Felipe Nylo de Aguiar
2012-09-01
Full Text Available This paper presents an analysis of the kinetics and thermodynamics of marble residue mixtures utilisation on desulfurization of pig iron. The desulfurization was carried out using lime, marble residue, fluorite and pig iron. Different mixtures of these materials were added into a bath of pig iron at 1,450°C. Metal samples were collected via vacuum samplers at times of 5, 10, 15, 20 and 30 minutes, in order to check the variation of sulfur content. Based on the results of chemical analysis of the metal and the desulfurizer mixture, the sulfide capacity of mixtures, the sulfur partition coefficient and the sulfur mass transport coefficient values were calculated.The results show the technical feasibility of using marble waste as desulfurizer agent.
Institute of Scientific and Technical Information of China (English)
詹美礼; 孙孝安; 戴爽; 盛金昌; 罗玉龙
2015-01-01
A special relationship exists between overland flow erosion and kinetic parameter. In order to set up the quantitative relationship, kinetic mechanism of slope erosion process,slope velocity and sand transport rate and other elements were measured for different slopes than and different rainfall intensity conditions through the overland flow model experiments of artificial rainfall. In view of the contrast between the standard deviation,coefficient of variation and the coefficient of determination,the kinetic parameters of sand transport and erosion of high correlation were selected. Experiments results show that linear rate equation of shear stress has good simulation results describing the change process of gully erosion sediment transport.%坡面流侵蚀量与水动力学参数具有特殊关系，为建立侵蚀量与坡面流流速、剪切力和断面单位能量间的定量关系，通过室内人工降雨坡面流模型试验，针对不同坡比、不同降雨强度条件进行了坡面流流速、产沙率等要素的系统试验测量。利用参数分析法，通过标准差、变异系数和决定系数之间的对比评价，优选出与侵蚀输沙相关程度较高的动力学参数。结果表明：坡面流剪切力线性关系式用于描述坡面流输沙的变化过程具有较好的模拟效果。
Investigation of MA Content Effect on Kinetic Parameter in ADS Core%MA 含量对 ADS 堆芯动力学参数的影响研究
Institute of Scientific and Technical Information of China (English)
罗润; 宋洪兵; 赵福宇
2016-01-01
The effective delayed neutron fraction (βef ),mean neutron generation time (Λ)and reactivity feedback coefficient (α)are the most important parameters in nuclear reactor kinetics.In this study,Monte Carlo method was applied to calculate the kinetic parameters of accelerator driven sub-critical system (ADS)cores,and the effect of mi-nor actinides (MA)content on these parameters was analyzed.The different contents of MA in the fuel were investigated to determine its effect on the kinetic parameters.The results show that when the content of MA reaches 5% in the fuel,theβef andΛ decrease by about 18% and 31%,respectively.With the increase of MA content from 0% to 5%,the average value of Doppler feedback coefficientαD varies from -0.56 pcm/K to-0.36 pcm/K,and the average value of coolant feedback coefficient αC varies from-2.1 1 pcm/K to -1.73 pcm/K.%有效缓发中子份额(βef )、平均中子代时间(Λ)和反应性反馈系数(α)是核反应堆动力学中至关重要的参数。本文采用蒙特卡罗方法计算了加速器驱动的次临界系统(ADS)堆芯的动力学参数,并分析了次锕系核素(MA)装载量对这些参数的影响。通过在燃料中添加不同含量的 MA,来研究其对 ADS堆芯动力学参数的影响。结果表明,当 MA 在燃料中的含量从0%增加到5%时,βef 和Λ的值分别降低了18%和31%,多普勒反馈系数平均值αD 由-0.56 pcm/K 变化到-0.36 pcm/K,冷却剂反馈系数平均值αC 由-2.11 pcm/K变化到-1.73 pcm/K。
Báez, María E; Fuentes, Edwar; Espinoza, Jeannette
2013-07-01
Atrazine sorption was studied in six Andisol and Ultisol soils. Humic and fulvic acids and humin contributions were established. Sorption on soils was well described by the Freundlich model. Kf values ranged from 2.2-15.6 μg(1-1/n)mL(1/n)g⁻¹. The relevance of humic acid and humin was deduced from isotherm and kinetics experiments. KOC values varied between 221 and 679 mLg⁻¹ for these fractions. Fulvic acid presented low binding capacity. Sorption was controlled by instantaneous equilibrium followed by a time-dependent phase. The Elovich equation, intraparticle diffusion model, and a two-site nonequilibrium model allowed us to conclude that (i) there are two rate-limited phases in Andisols related to intrasorbent diffusion in organic matter and retarded intraparticle diffusion in the organo-mineral complex and that (ii) there is one rate-limited phase in Ultisols attributed to the mineral composition. The lower organic matter content of Ultisols and the slower sorption rate and mechanisms involved must be considered to assess the leaching behavior of atrazine. PMID:23711282
Directory of Open Access Journals (Sweden)
Borikar, D. K.
2006-01-01
Full Text Available The electrodeposition of nickel from nickel sulphate bath was studied in ammonia medium. The electrolytic conditions for nickel deposition was optimized at room temperature. The effect of acetone on current efficiency, morphology, stability and particle size of deposited nickel powder was studied. The effect of organic additive Tribenzyl ammonium chloride (TBAC on the morphology of nickel powder was also studied. The kinetics of electrodeposition was studied and the results were utilized in developing mathematical model. During electrodeposition the current efficiency was found to increase with increase in acetone concentration up to 15% V/V in bath solution. On further increase of acetone concentration in bath solution current efficiency decreases. The stability of the electrowon deposited nickel powder was found to be in the range of 85 to 89 %. Powder morphology was found to be dentritic, porous and irregular. The morphology was also found to be underdeveloped dentritic to rounded aggregate as the concentration of organic additive TBAC increases. The average particle size of the deposited powder was found to be decreasing as the concentration of the acetone increases. The average size of the particle is in the range of 13-16 m.
E Varani; M Balducelli; Severi, S; A Patroncini; A Shoheib; Vecchi, G.; GR Lucchi; Aquilina, M.; C Corbelli; Casanova, R.; A Maresta
2007-01-01
Background: The aim of the present study was to evaluate which of theclinico-angiographic parameters of acute ischemic extension and efficacy ofreperfusion in AMI treated with primary PCI are predictive of infarct size andone month left ventricular ejection fraction (LVEF).Patients and Method: Thirty-five patients with first AMI treated withprimary PCI underwent two rest 99mTc-sestamibi gated SPECT, 4-6 days and 30-40days after PCI. Clinical, electrocardiographic, angiographic and scintigraph...
Bisdas, Sotirios; Konstantinou, George N.; Sherng Lee, Puor; Thng, Choon Hua; Wagenblast, Jens; Baghi, Mehran; San Koh, Tong
2007-10-01
The objective of this work was to evaluate the feasibility of a two-compartment distributed-parameter (DP) tracer kinetic model to generate functional images of several physiologic parameters from dynamic contrast-enhanced CT data obtained of patients with extracranial head and neck tumors and to compare the DP functional images to those obtained by deconvolution-based DCE-CT data analysis. We performed post-processing of DCE-CT studies, obtained from 15 patients with benign and malignant head and neck cancer. We introduced a DP model of the impulse residue function for a capillary-tissue exchange unit, which accounts for the processes of convective transport and capillary-tissue exchange. The calculated parametric maps represented blood flow (F), intravascular blood volume (v1), extravascular extracellular blood volume (v2), vascular transit time (t1), permeability-surface area product (PS), transfer ratios k12 and k21, and the fraction of extracted tracer (E). Based on the same regions of interest (ROI) analysis, we calculated the tumor blood flow (BF), blood volume (BV) and mean transit time (MTT) by using a modified deconvolution-based analysis taking into account the extravasation of the contrast agent for PS imaging. We compared the corresponding values by using Bland-Altman plot analysis. We outlined 73 ROIs including tumor sites, lymph nodes and normal tissue. The Bland-Altman plot analysis revealed that the two methods showed an accepted degree of agreement for blood flow, and, thus, can be used interchangeably for measuring this parameter. Slightly worse agreement was observed between v1 in the DP model and BV but even here the two tracer kinetic analyses can be used interchangeably. Under consideration of whether both techniques may be used interchangeably was the case of t1 and MTT, as well as for measurements of the PS values. The application of the proposed DP model is feasible in the clinical routine and it can be used interchangeably for measuring
Energy Technology Data Exchange (ETDEWEB)
Bisdas, Sotirios [Department of Diagnostic and Interventional Radiology, Johann Wolfgang GoeUniversity Hospital, 60590 Frankfurt (Germany); Konstantinou, George N [401 General Military Hospital, Athens (Greece); Lee, Puor Sherng [Department of Oncologic Imaging National Cancer Centre, 169610 Singapore (Singapore); Thng, Choon Hua [Department of Oncologic Imaging National Cancer Centre, 169610 Singapore (Singapore); Wagenblast, Jens [Department of Otorhinolaryngology, Johann Wolfgang GoeUniversity Hospital, 60590 Frankfurt (Germany); Baghi, Mehran [Department of Otorhinolaryngology, Johann Wolfgang GoeUniversity Hospital, 60590 Frankfurt (Germany); Koh, Tong San [Center for Modeling and Control of Complex Systems, Nanyang Technological University, 639798 Singapore (Singapore)
2007-10-21
The objective of this work was to evaluate the feasibility of a two-compartment distributed-parameter (DP) tracer kinetic model to generate functional images of several physiologic parameters from dynamic contrast-enhanced CT data obtained of patients with extracranial head and neck tumors and to compare the DP functional images to those obtained by deconvolution-based DCE-CT data analysis. We performed post-processing of DCE-CT studies, obtained from 15 patients with benign and malignant head and neck cancer. We introduced a DP model of the impulse residue function for a capillary-tissue exchange unit, which accounts for the processes of convective transport and capillary-tissue exchange. The calculated parametric maps represented blood flow (F), intravascular blood volume (v{sub 1}), extravascular extracellular blood volume (v{sub 2}), vascular transit time (t{sub 1}), permeability-surface area product (PS), transfer ratios k{sub 12} and k{sub 21}, and the fraction of extracted tracer (E). Based on the same regions of interest (ROI) analysis, we calculated the tumor blood flow (BF), blood volume (BV) and mean transit time (MTT) by using a modified deconvolution-based analysis taking into account the extravasation of the contrast agent for PS imaging. We compared the corresponding values by using Bland-Altman plot analysis. We outlined 73 ROIs including tumor sites, lymph nodes and normal tissue. The Bland-Altman plot analysis revealed that the two methods showed an accepted degree of agreement for blood flow, and, thus, can be used interchangeably for measuring this parameter. Slightly worse agreement was observed between v{sub 1} in the DP model and BV but even here the two tracer kinetic analyses can be used interchangeably. Under consideration of whether both techniques may be used interchangeably was the case of t{sub 1} and MTT, as well as for measurements of the PS values. The application of the proposed DP model is feasible in the clinical routine and it
Melvin Samuel S; Evy Alice Abigail M; Ramalingam Chidambaram
2015-01-01
Biosorption is a promising alternative method to replace the existing conventional technique for Cr(VI) removal from the industrial effluent. In the present experimental design, the removal of Cr(VI) from the aqueous solution was studied by Aspergillus niger MSR4 under different environmental conditions in the batch systems. The optimum conditions of biosorption were determined by investigating pH (2.0) and temperature (27°C). The effects of parameters such as biomass dosage (g/L), initial Cr...
Poggio, D; Walker, M; Nimmo, W; Ma, L; Pourkashanian, M
2016-07-01
This work proposes a novel and rigorous substrate characterisation methodology to be used with ADM1 to simulate the anaerobic digestion of solid organic waste. The proposed method uses data from both direct substrate analysis and the methane production from laboratory scale anaerobic digestion experiments and involves assessment of four substrate fractionation models. The models partition the organic matter into a mixture of particulate and soluble fractions with the decision on the most suitable model being made on quality of fit between experimental and simulated data and the uncertainty of the calibrated parameters. The method was tested using samples of domestic green and food waste and using experimental data from both short batch tests and longer semi-continuous trials. The results showed that in general an increased fractionation model complexity led to better fit but with increased uncertainty. When using batch test data the most suitable model for green waste included one particulate and one soluble fraction, whereas for food waste two particulate fractions were needed. With richer semi-continuous datasets, the parameter estimation resulted in less uncertainty therefore allowing the description of the substrate with a more complex model. The resulting substrate characterisations and fractionation models obtained from batch test data, for both waste samples, were used to validate the method using semi-continuous experimental data and showed good prediction of methane production, biogas composition, total and volatile solids, ammonia and alkalinity. PMID:27156366
Poggio, D; Walker, M; Nimmo, W; Ma, L; Pourkashanian, M
2016-07-01
This work proposes a novel and rigorous substrate characterisation methodology to be used with ADM1 to simulate the anaerobic digestion of solid organic waste. The proposed method uses data from both direct substrate analysis and the methane production from laboratory scale anaerobic digestion experiments and involves assessment of four substrate fractionation models. The models partition the organic matter into a mixture of particulate and soluble fractions with the decision on the most suitable model being made on quality of fit between experimental and simulated data and the uncertainty of the calibrated parameters. The method was tested using samples of domestic green and food waste and using experimental data from both short batch tests and longer semi-continuous trials. The results showed that in general an increased fractionation model complexity led to better fit but with increased uncertainty. When using batch test data the most suitable model for green waste included one particulate and one soluble fraction, whereas for food waste two particulate fractions were needed. With richer semi-continuous datasets, the parameter estimation resulted in less uncertainty therefore allowing the description of the substrate with a more complex model. The resulting substrate characterisations and fractionation models obtained from batch test data, for both waste samples, were used to validate the method using semi-continuous experimental data and showed good prediction of methane production, biogas composition, total and volatile solids, ammonia and alkalinity.
Sau, Sujay P.; Kumar, Pawan; Sharma, Pawan K.; Hrdlicka, Patrick J.
2012-01-01
Triplex forming oligonucleotides (TFOs) are the most commonly used approach for site-specific targeting of double stranded DNA (dsDNA). Important parameters describing triplex formation include equilibrium binding constants (Keq) and association/dissociation rate constants (kon and koff). The ‘fluorescent intercalator displacement replacement’ (FIDR) assay is introduced herein as an operationally simple approach toward determination of these parameters for triplexes involving TC-motif TFOs. Briefly described, relative rate constants are determined from fluorescence intensity changes upon: (i) TFO-mediated displacement of pre-intercalated and fluorescent ethidium from dsDNA targets (triplex association) and (ii) Watson–Crick complement-mediated displacement of the TFO and replacement with ethidium (triplex dissociation). The assay is used to characterize triplexes between purine-rich dsDNA targets and TC-motif TFOs modified with six different locked nucleic acid (LNA) monomers, i.e. conventional and C5-alkynyl-functionalized LNA and α-L-LNA pyrimidine monomers. All of the studied monomers increase triplex stability by decreasing the triplex dissociation rate. LNA-modified TFOs form more stable triplexes than α-L-LNA-modified counterparts owing to slower triplex dissociation. Triplexes modified with C5-(3-aminopropyn-1-yl)-LNA-U monomer Z are particularly stable. The study demonstrates that three affinity-enhancing features can be combined into one high-affinity TFO monomer: conformational restriction of the sugar ring, expansion of the pyrimidine π-stacking surface and introduction of an exocyclic amine. PMID:22855561
Sau, Sujay P; Kumar, Pawan; Sharma, Pawan K; Hrdlicka, Patrick J
2012-11-01
Triplex forming oligonucleotides (TFOs) are the most commonly used approach for site-specific targeting of double stranded DNA (dsDNA). Important parameters describing triplex formation include equilibrium binding constants (K(eq)) and association/dissociation rate constants (k(on) and k(off)). The 'fluorescent intercalator displacement replacement' (FIDR) assay is introduced herein as an operationally simple approach toward determination of these parameters for triplexes involving TC-motif TFOs. Briefly described, relative rate constants are determined from fluorescence intensity changes upon: (i) TFO-mediated displacement of pre-intercalated and fluorescent ethidium from dsDNA targets (triplex association) and (ii) Watson-Crick complement-mediated displacement of the TFO and replacement with ethidium (triplex dissociation). The assay is used to characterize triplexes between purine-rich dsDNA targets and TC-motif TFOs modified with six different locked nucleic acid (LNA) monomers, i.e. conventional and C5-alkynyl-functionalized LNA and α-L-LNA pyrimidine monomers. All of the studied monomers increase triplex stability by decreasing the triplex dissociation rate. LNA-modified TFOs form more stable triplexes than α-L-LNA-modified counterparts owing to slower triplex dissociation. Triplexes modified with C5-(3-aminopropyn-1-yl)-LNA-U monomer Z are particularly stable. The study demonstrates that three affinity-enhancing features can be combined into one high-affinity TFO monomer: conformational restriction of the sugar ring, expansion of the pyrimidine π-stacking surface and introduction of an exocyclic amine. PMID:22855561
Institute of Scientific and Technical Information of China (English)
刘娟; 李居强; 崔振山; 阮立群
2012-01-01
通过引入动态再结晶的演化速率,分析了基于Avrami方程的经典动态再结晶动力学模型的不足,提出了一种新的具有单参数的动态再结晶动力学模型,反映了动态再结晶过程缓慢 快速-缓慢的特点.采用Gleeble-1500热模拟试验机,对典型的具有动态再结晶特性的材料镁合金AZ31B进行了热压缩实验,通过进行参数回归得到了其动态再结晶动力学模型,并与实验结果相对比,验证了该模型的正确性.进一步将稳态变形条件下获得的微观组织演化模型改写成分步叠加形式,与动态再结晶晶粒尺寸模型相结合,应用到非稳态条件的晶粒预测,模拟与实验的对比表明计算结果和定量金相法所获得的结果基本一致,说明了非稳态变形过晶粒的叠加预测方法的合理性.%Dynamic recrystallization (DRX) is considered as one of the most important mi-crostructural evolution mechanisms to obtain fine metallurgical structures, eliminate defects and improve mechanical properties of products. Although the DRX kinetics models proposed by researchers have some differences in parameters and forms, they are all based on the Avrami function describing the relationship between dynamically recrystallized volume fraction and strain or time. Avrami equation is in the form of exponential function and the kinetics curve of DRX exhibits different when the exponent is assumed to be different (between 1 and 2). Under these conditions, however, the exponential function cannot exactly describe the "slow-rapid-slow" property of the development speed of DRX process. By introducing the velocity of development of DRX process, which is referred to as the variation of the dynamically recrystallized volume fraction with strain, namely, the first partial derivative of the dynamically recrystallized volume fraction to strain, a new kinetics model of DRX was proposed in comparison with the classical kinetics model of DRX. The new model
Directory of Open Access Journals (Sweden)
Luciano da Silva Cabral
2011-09-01
Full Text Available This study aimed to validate the estimates of the ruminal degradation of total carbohydrates (TC, ruminal and total digestion of fibrous carbohydrates (FC and microbial nitrogen flow in the abomasum evaluated by in vitro gas production technique (IVGP. Six ruminally and abomasally cannulated steers arranged in a double 3 × 3 latin square were used to measure described parameters with indigestible neutral detergent fiber (INDF utilization as marker. Total and fibrous carbohydrates degraded in the rumen were estimated through digestion rates obtained for fibrous (FC and non fibrous carbohydrates (NFC using in vitro gas production technique, corrected for its respective ruminal and postruminal passage rates. The estimation of the total digestion of FC was done by the sum of ruminal and post-ruminal digestion of these compounds. The microbial nitrogen flow in the abomasum was estimated by the calculating the microbial efficiency of bacteria that ferment FC and NFC, utilizing the microbial growth rate obtained by the ruminal digestion rate for carbohydrate fractions in IVGP. The utilization of the in vitro gas production technique allows obtaining accurate estimates of the ruminal digestion of total carbohydrates, total and ruminal digestion of fiber carbohydrates and microbial protein flow in the abomasum.
International Nuclear Information System (INIS)
The author has studied the kinetics of heparin and heparin fractions after intravenous administration in humans and in this thesis the results of this study are reported. Basic knowledge about the physico-chemical properties of heparin and its interactions with proteins resulting in anticoagulant and lipolytic effects are discussed in a review (chapter II), which also comprises some clinical aspects of heparin therapy. In chapter III the kinetics of the anticoagulant effect are described after intravenous administration of five commercial heparin preparations. A mathematical model is presented that fits best to these kinetics. The kinetics of the anticoagulant and lipolytic effects after intravenous injection of various 35S-radiolabelled heparin fractions and their relationship with the disappearance of the radiolabel are described in chapter IV. Chapter V gives a description of the kinetics of two radiolabels after injection of in vitro formed complexes consisting of purified, 125I-radiolabelled antithrombin III and various 35S-radiolabelled heparin fractions. (Auth.)
Energy Technology Data Exchange (ETDEWEB)
Gonzalez M, P. R. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Cruz Z, E.; Furetta, C., E-mail: pedro.gonzalez@inin.gob.mx [UNAM, Instituto de Ciencias Nucleares, Apdo. Postal 70-543, 04510 Mexico D. F. (Mexico)
2015-10-15
Full text: The characterization of new thermoluminescent materials used in radiation dosimetry, require the determination of kinetic parameters, which are associated with the number and shape of the peaks representing brightness curves. The most important parameters are: energy or depth of the traps (E), the frequency factor (s) and order kinetics (b). These are necessary to predict the stability of the thermoluminescent information saved after the effect of irradiation on the material. In this paper, the results of the determination of kinetic parameters of CaF{sub 2} doped with Tm{sup 3+} ions are presented, after being irradiated with gamma rays of {sup 60}Co. The methods used for the determination of kinetic parameters were: initial growth of thermoluminescent signal, Chen method of type general order and by deconvolution of the brightness curve. The results showed that the brightness curve of CaF{sub 2} has three peaks, the main peak at 491 K and two smaller peaks, one at 431 and another at 573 K. The dosimetric peak (491 K) has general order kinetics. (Author)
Kinetic distance and kinetic maps from molecular dynamics simulation
Noe, Frank
2015-01-01
Characterizing macromolecular kinetics from molecular dynamics (MD) simulations requires a distance metric that can distinguish slowly-interconverting states. Here we build upon diffusion map theory and define a kinetic distance for irreducible Markov processes that quantifies how slowly molecular conformations interconvert. The kinetic distance can be computed given a model that approximates the eigenvalues and eigenvectors (reaction coordinates) of the MD Markov operator. Here we employ the time-lagged independent component analysis (TICA). The TICA components can be scaled to provide a kinetic map in which the Euclidean distance corresponds to the kinetic distance. As a result, the question of how many TICA dimensions should be kept in a dimensionality reduction approach becomes obsolete, and one parameter less needs to be specified in the kinetic model construction. We demonstrate the approach using TICA and Markov state model (MSM) analyses for illustrative models, protein conformation dynamics in bovine...
Directory of Open Access Journals (Sweden)
Adriana Parada Dias da Silveira
2004-04-01
Full Text Available The mechanisms that determine greater P absorption by mycorrhizal plants are still not completely clear, and are attributed, in part, to an increase in the number of absorption sites promoted by the hyphae, and/or to a greater affinity of the colonized hypha or root carriers to P. The effect of mycorrhizae formed by Glomus etunicatum on the kinetic parameters of P absorption by the roots and on P influx in bean plants of the IAC-Carioca cultivar was evaluated, in two distinct plant development periods: at the onset of flowering and at the pod-filling stage (35 and 50 days after sowing, respectively. A mixture of sand and silica (9:1 was utilized as substrate and irrigated with nutrient solution. The kinetics assay was performed by the method of 32P depletion from the solution (depletion curve, using intact plants. Mycorrhization promoted greater growth and P absorption by bean plants, which was more conspicuously observed at the pod-filling stage. Mycorrhizal plants showed higher values of maximum ion uptake rate (Vmax and net P influx at the flowering stage. Lower minimum ion concentration (Cmin and Michaelis-Menten constant (Km values were verified in mycorrhizal plants at the pod-filling stage. Mycorrhizal plants also presented higher net P influx per plant, in both stages. Cmin was the kinetic parameter more intimately related to P absorption, and a significant correlation was obtained between this parameter and shoot P content and accumulation in bean plants.Os mecanismos envolvidos na maior absorção de P pela planta micorrizada ainda não estão totalmente esclarecidos, atribuindo-se, em parte, ao aumento no número de sítios de absorção promovido pela hifa e/ou maior afinidade dos carregadores da hifa ou da raiz colonizada ao P. Avaliou-se o efeito da micorriza formada por Glomus etunicatum nos parâmetros cinéticos da absorção radicular de P e no influxo de P em feijoeiro, cultivar IAC-Carioca, em duas épocas do ciclo da planta
Institute of Scientific and Technical Information of China (English)
C.S. Chang
2007-01-01
@@ The ITER relevant edge plasmas in the present day experiments are in the kinetic regime,with the pedestalions in the long-mean-free-path banans collisionality regime and the pedestal electrons in the banana-plateau regime.
DEFF Research Database (Denmark)
2009-01-01
A kinetic interface for orientation detection in a video training system is disclosed. The interface includes a balance platform instrumented with inertial motion sensors. The interface engages a participant's sense of balance in training exercises.......A kinetic interface for orientation detection in a video training system is disclosed. The interface includes a balance platform instrumented with inertial motion sensors. The interface engages a participant's sense of balance in training exercises....
Kinetic properties of fractal media
Chumak, Oleg V
2016-01-01
Kinetic processes in fractal stellar media are analyzed in terms of the approach developed in our earlier paper (Chumak, Rastorguev, 2016) involving a generalization of the nearest neighbor and random force distributions to fractal media. Diffusion is investigated in the approximation of scale-dependent conditional density based on an analysis of the solutions of the corresponding Langevin equations. It is shown that kinetic parameters (time scales, coefficients of dynamic friction, diffusion, etc.) for fractal stellar media can differ significantly both qualitatively and quantitatively from the corresponding parameters for a quasi-uniform random media with limited fluctuations. The most important difference is that in the fractal case kinetic parameters depend on spatial scale length and fractal dimension of the medium studied. A generalized kinetic equation for stellar media (fundamental equation of stellar dynamics) is derived in the Fokker-Planck approximation with the allowance for the fractal properties...
Erbium hydride decomposition kinetics.
Energy Technology Data Exchange (ETDEWEB)
Ferrizz, Robert Matthew
2006-11-01
Thermal desorption spectroscopy (TDS) is used to study the decomposition kinetics of erbium hydride thin films. The TDS results presented in this report are analyzed quantitatively using Redhead's method to yield kinetic parameters (E{sub A} {approx} 54.2 kcal/mol), which are then utilized to predict hydrogen outgassing in vacuum for a variety of thermal treatments. Interestingly, it was found that the activation energy for desorption can vary by more than 7 kcal/mol (0.30 eV) for seemingly similar samples. In addition, small amounts of less-stable hydrogen were observed for all erbium dihydride films. A detailed explanation of several approaches for analyzing thermal desorption spectra to obtain kinetic information is included as an appendix.
Institute of Scientific and Technical Information of China (English)
Jaya Sre Varsihini C; Devlina Das; Nilanjana Das
2014-01-01
Response surface methodology (RSM) employing 5-level Box-Behnken design was used to optimize the biosorption of ce-rium(III) onto biowaste materials of animal and plant origin viz. prawn carapace (PC) and corn style (CS). Various process parame-ters viz. pH (A:3.0-9.0), biomass dosage (B:0.05-0.35 g/L), initial metal concentration (C:50-350 mg/L), contact time (D:2-6 h) and temperature (E:20-60 °C) were chosen for optimization. A log transformation was suggested by the Box-Cox plot in the present case. A low p-value of<0.0001 validated the significance of the model. Maximum Ce(III) uptake of 218.3 mg/g for PC and 180.2 mg/g for CS was noted under optimum conditions. Among the equilibrium isotherms, Freundlich model was found to be the best fit-ted one suggesting a heterogeneous mode of biosorption on PC whereas Langmuir model showed the best fit suggesting homogene-ous mode of cerium biosorption on CS. This was further confirmed by scanning electron microscopy (SEM). Kinetic studies showed better applicability of pseudo-first order model suggesting physisorption as phenomena underlying the process. Film-diffusion was suggested by the non-linearity of the Boyd plot. Thermodynamic studies showed that the process was endothermic and spontaneous. FTIR analysis confirmed a major involvement of the participation of amide, amines, ketones and primary alcohol groups during Ce(III) biosorption. EDAX analysis confirmed the major participation of carbon group during Ce(III) biosorption. This was the first report on parameter optimization of Ce(III) biosorption onto biowaste materials using 5-level Box-Behnken experimental design which might be helpful for the recovery of Ce(III) from aqueous environment.
Stochastic Optimization Based Study of Dimerization Kinetics
Talukder, Srijeeta; Metzler, Ralf; Banik, Suman K; Chaudhury, Pinaki
2013-01-01
We investigate the potential of numerical algorithms to decipher the kinetic parameters involved in multi-step chemical reactions. To this end we study a dimerization kinetics of protein as a model system. We follow the dimerization kinetics using a stochastic simulation algorithm and combine it with three different optimization techniques (Genetic Algorithm, Simulated Annealing and Parallel Tempering) to obtain the rate constants involved in each reaction step. We find good convergence of the numerical scheme to the rate constants of the process. We also perform a sensitivity test on the reaction kinetic parameters to see the relative effects of the parameters for the associated profile of the monomer/dimer distribution.
Institute of Scientific and Technical Information of China (English)
阳海; 周硕林; 尹明亮; 皮露露; 曾健; 易兵
2013-01-01
采用TiO2光催化技术对克百威的降解进行了研究,并系统地考察了催化剂用量,溶液初始pH值,底物浓度,活性氧物种和各种阴阳离子对其降解动力学的影响.用Langmuir-Hinshelwood动力学模型对克百威的光催化降解进行了研究,结果表明,克百威在弱碱性条件下降解速率最快,OH对克百威降解贡献比约为93.4％,h+和其他ROSs的贡献则相对较小.而水溶液中的阴离子BrO3-和S2O82对克百威的光催化降解有促进作用,I则有明显的抑制作用,并且水溶液中的K+,Ca2+,Na+,Mg2+和Cu2+等金属阳离子对克百威的降解也均体现了一定程度的抑制作用.%Photocatalytic degradation of carbofuran has been investigated in TiO2 aqueous solution under UV irradiation. The effects of various parameters such as catalyst amount, pH value, concentration of carbofuran, reactive oxidative species (ROSs), different anions and metal cations on photocatalytic degradation kinetics were studied. The degradation of carbofuran follows pseudo first-order kinetics by using Langmuir-Hinshelwood model. The results indicated that the weak alkaline solution was favor for the degradation of carbofuran. The ·OH radical is responsible for the major degradation of carbofuran, and its contribution is about 93.4%, while the other ROSs play a minor contribution to the degradation. Additionally, the anions of BrO3- and S2O82- accelerate the degradation rate of carbofuran, while I- anion inhibits degradation reaction obviously. The photocatalytic degradation reactions were also inhibited to some extent when K+, Ca2+, Na+, Mg2+ and Cu2+ cations were added to aqueous solution.
Kuby, S A; Roy, R N
1976-05-01
A systematic study has been made of the pH- and temperature-dependency of the steady-state kinetic parameters of the stabilized two-subunit enzyme species of glucose-6-phosphate dehydrogenase, in the absence of superimposed association-dissociation reactions. The Vmax(app) data obtained in several buffers between pH 5 and 10 and at 18-32 degrees C lead to the postulate that at least two sets of protonic equilibria may govern the catalysis (one near pH 5.7 AT 25 DEGREES C and another near pH 9.2); furthermore, two pathways for product formation (i.e., two Vmax's) appear to be required to explain the biphasic nature of the log Vmax(app) vs. pH curves, with Vmax(basic) greater than Vmax(acidic + neutral). Of the several buffers explored, either a uniform degree of interaction or a minimal degree of buffer species interaction could be assessed from the enthalpy changes associated with the derived values for ionization constants attributed to the protonic equilibria in the enzyme-substrates ternary complexes for the case of Tris-acetate-EDTA buffers, at constant ionic strength. With the selection of this buffer at 0.1 (T/2) and at 25 and 32 degrees C, a self-consistent kinetic mechanism has emerged which allows for the random binding of the two fully ionized substrates to the enzyme via two major pathways, and product formation by both E-A--B- and HE-A--B-. As before (Kuby et al. Arch. Biochem, Biophys. 165, 153-178, 1974), a quasi-equilibrium is presumed, with rate-limiting steps (k + 5 and k + 5') at the interconversion of the ternary complexes. Values for the two sets of protonic equilibria defined by this mechanism (viz., pKk, pKH2 for the first ionizations, and pKk', pKH' for the second) could then be estimated. From their numerical values (e.g., at 25 degrees C: pKK = 5.7 PKH2 = 5.2; and pKK' = 9.1, PKH' = 8.2) and from the values for delta H degrees ioniz (e.g., delta H degrees pKK APPROXIMATELY 5.1 KCAL/MOL; DELTA H degrees pKK' APPROXIMATELY 11 KCAL/MOL), A
Institute of Scientific and Technical Information of China (English)
朱红青; 郭艾东; 屈丽娜
2012-01-01
The level of spontaneous combustion danger of coal can be characterized by characteristic temperature or thermal dynamic parameters. In fact, there are often only coal industry parameters in hand, so it is necessary to study the relationship between the parameters characterizing the coal spontaneous combustion danger and the industrial parameters. In order to establish and analyze the relationship, different coal samples were studied through thermo-gravimetric experiments based on a non-isothermal experimental method. The relationships among coal kinetics parameters, characteristic temperatures and volatile under 10 ℃/min heating rate were obtained, the relationships of a volatile and coal oxidation characteristics were revealed. The experimental results show that with the volatile part growing up, the coal combustion temperature characteristics are lower, and the thermal dynamic parameters are lower, and the coal is more esay to be lit, so the risk of coal spontaneous combustion is higher.%通过煤的热动力学参数和特征温度可以表征煤自燃危险程度.而在实际情况中,这些数据缺少,往往只有煤的工业参数.因此,研究工业参数与表征煤自燃危险参数的关系十分必要.为了分析和建立该关系,基于非等温试验方法对不同煤样进行热重试验分析,得出8个煤样在10℃/min升温速率下的反应动力学参数与煤工业分析参数的关系,揭示挥发分与煤的氧化特性、特征温度的关系.试验结果表明:8个煤样的挥发分排序F3＞F8＞F4 ＞F7＞F2＞F1＞F5＞F6,各特征温度排序基本满足T3＜T8＜T4＜T7＜T2＜T1＜T5＜T6,热动力学参数活化能排序E3＜E8＜E4＜E7＜E2 ＜E1 ＜E5 ＜E6,且挥发分与特征温度点、活化能成非成线性关系,由此可以看出挥发分越高,煤燃烧特征温度值越低,热动力学参数值越小,煤越易被点燃,煤的自燃危险性越高.
NOORDMAN, WH; BLOKZIJL, W; ENGBERTS, JBF; BLANDAMER, MJ
1995-01-01
Kinetic data are reported for the spontaneous hydrolysis of 1-benzoyl-1,2,4-triazole in aqueous solutions at ambient-pressure and 298.2 K, in aqueous solutions containing added ethanol, propanol and sodium chloride. Kinetic-data are also reported for the same reaction in aqueous mixtures of sodium c
Noordman, Wouter H.; Blokzijl, Wilfried; Engberts, Jan B.F.N.; Blandamer, Michael J.
1995-01-01
Kinetic data are reported for the spontaneous hydrolysis of 1-benzoyl-1,2,4-triazole in aqueous solutions at ambient pressure and 298.2 K, in aqueous solutions containing added ethanol, propanol and sodium chloride. Kinetic data are also reported for the same reaction in aqueous mixtures of sodium c
Oxidative desulfurization: Kinetic modelling
Energy Technology Data Exchange (ETDEWEB)
Dhir, S.; Uppaluri, R. [Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam (India); Purkait, M.K. [Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam (India)], E-mail: mihir@iitg.ernet.in
2009-01-30
Increasing environmental legislations coupled with enhanced production of petroleum products demand, the deployment of novel technologies to remove organic sulfur efficiently. This work represents the kinetic modeling of ODS using H{sub 2}O{sub 2} over tungsten-containing layered double hydroxide (LDH) using the experimental data provided by Hulea et al. [V. Hulea, A.L. Maciuca, F. Fajula, E. Dumitriu, Catalytic oxidation of thiophenes and thioethers with hydrogen peroxide in the presence of W-containing layered double hydroxides, Appl. Catal. A: Gen. 313 (2) (2006) 200-207]. The kinetic modeling approach in this work initially targets the scope of the generation of a superstructure of micro-kinetic reaction schemes and models assuming Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) mechanisms. Subsequently, the screening and selection of above models is initially based on profile-based elimination of incompetent schemes followed by non-linear regression search performed using the Levenberg-Marquardt algorithm (LMA) for the chosen models. The above analysis inferred that Eley-Rideal mechanism describes the kinetic behavior of ODS process using tungsten-containing LDH, with adsorption of reactant and intermediate product only taking place on the catalyst surface. Finally, an economic index is presented that scopes the economic aspects of the novel catalytic technology with the parameters obtained during regression analysis to conclude that the cost factor for the catalyst is 0.0062-0.04759 US $ per barrel.
Oxidative desulfurization: kinetic modelling.
Dhir, S; Uppaluri, R; Purkait, M K
2009-01-30
Increasing environmental legislations coupled with enhanced production of petroleum products demand, the deployment of novel technologies to remove organic sulfur efficiently. This work represents the kinetic modeling of ODS using H(2)O(2) over tungsten-containing layered double hydroxide (LDH) using the experimental data provided by Hulea et al. [V. Hulea, A.L. Maciuca, F. Fajula, E. Dumitriu, Catalytic oxidation of thiophenes and thioethers with hydrogen peroxide in the presence of W-containing layered double hydroxides, Appl. Catal. A: Gen. 313 (2) (2006) 200-207]. The kinetic modeling approach in this work initially targets the scope of the generation of a superstructure of micro-kinetic reaction schemes and models assuming Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) mechanisms. Subsequently, the screening and selection of above models is initially based on profile-based elimination of incompetent schemes followed by non-linear regression search performed using the Levenberg-Marquardt algorithm (LMA) for the chosen models. The above analysis inferred that Eley-Rideal mechanism describes the kinetic behavior of ODS process using tungsten-containing LDH, with adsorption of reactant and intermediate product only taking place on the catalyst surface. Finally, an economic index is presented that scopes the economic aspects of the novel catalytic technology with the parameters obtained during regression analysis to conclude that the cost factor for the catalyst is 0.0062-0.04759 US $ per barrel. PMID:18541367
Kreuzer, Hans Jürgen
1986-01-01
This monograph deals with the kinetics of adsorption and desorption of molecules physisorbed on solid surfaces. Although frequent and detailed reference is made to experiment, it is mainly concerned with the theory of the subject. In this, we have attempted to present a unified picture based on the master equation approach. Physisorption kinetics is by no means a closed and mature subject; rather, in writing this monograph we intended to survey a field very much in flux, to assess its achievements so far, and to give a reasonable basis from which further developments can take off. For this reason we have included many papers in the bibliography that are not referred to in the text but are of relevance to physisorption. To keep this monograph to a reasonable size, and also to allow for some unity in the presentation of the material, we had to omit a number of topics related to physisorption kinetics. We have not covered to any extent the equilibrium properties of physisorbed layers such as structures, phase tr...
Kinetic distance and kinetic maps from molecular dynamics simulation.
Noé, Frank; Clementi, Cecilia
2015-10-13
Characterizing macromolecular kinetics from molecular dynamics (MD) simulations requires a distance metric that can distinguish slowly interconverting states. Here, we build upon diffusion map theory and define a kinetic distance metric for irreducible Markov processes that quantifies how slowly molecular conformations interconvert. The kinetic distance can be computed given a model that approximates the eigenvalues and eigenvectors (reaction coordinates) of the MD Markov operator. Here, we employ the time-lagged independent component analysis (TICA). The TICA components can be scaled to provide a kinetic map in which the Euclidean distance corresponds to the kinetic distance. As a result, the question of how many TICA dimensions should be kept in a dimensionality reduction approach becomes obsolete, and one parameter less needs to be specified in the kinetic model construction. We demonstrate the approach using TICA and Markov state model (MSM) analyses for illustrative models, protein conformation dynamics in bovine pancreatic trypsin inhibitor and protein-inhibitor association in trypsin and benzamidine. We find that the total kinetic variance (TKV) is an excellent indicator of model quality and can be used to rank different input feature sets. PMID:26574285
Energy Technology Data Exchange (ETDEWEB)
Westbrook, C.K.; Pitz, W.J. [Lawrence Livermore National Laboratory, CA (United States)
1993-12-01
This project emphasizes numerical modeling of chemical kinetics of combustion, including applications in both practical combustion systems and in controlled laboratory experiments. Elementary reaction rate parameters are combined into mechanisms which then describe the overall reaction of the fuels being studied. Detailed sensitivity analyses are used to identify those reaction rates and product species distributions to which the results are most sensitive and therefore warrant the greatest attention from other experimental and theoretical research programs. Experimental data from a variety of environments are combined together to validate the reaction mechanisms, including results from laminar flames, shock tubes, flow systems, detonations, and even internal combustion engines.
A Comprehensive Enzyme Kinetic Exercise for Biochemistry
Barton, Janice S.
2011-01-01
This article describes a comprehensive treatment of experimental enzyme kinetics strongly coupled to electronic data acquisition and use of spreadsheets to organize data and perform linear and nonlinear least-squares analyses, all in a manner that promotes development of important reasoning skills. Kinetic parameters are obtained for the stable…
International Nuclear Information System (INIS)
Recently, the in vivo processes of platelet function and the reaction and interaction of platelets with components of the blood vessel wall and artificial surfaces have received increasing attention. In this article the focus is placed on two aspects of platelet function and kinetics as revealed by 111In-labelled platelets. First the interaction of platelets with foreign prosthetic surfaces is discussed and some interesting facets of platelet functions that have come to light, are pointed out. Secondly, experiences with the development and refinement of an improved technique, namely the dual-isotope subtraction method, which increases the sensitivity of platelet imaging and allows the detection of relatively small areas of platelet deposition with accuracy, are described
Numerical optimisation for model evaluation in combustion kinetics
Fischer, Marc; Jiang, Xi
2015-01-01
Numerical optimisation related to the estimation of kinetic parameters and model evaluation is playing an increasing role in combustion as well as in other areas of applied energy research. The present work aims at presenting the current probability-based approaches along applications to real problems of combustion chemical kinetics. The main methods related to model and parameter evaluation have been explicated. An in-house program for the systematic adjustment of kinetic parameters to exper...
Directory of Open Access Journals (Sweden)
Maria Célia Lopes Torres
2004-06-01
Full Text Available Este estudo teve como objetivos avaliar a indução da Glutationa S-Transferase, com extratos de vegetais, e caracterizar os parâmetros cinéticos desta enzima. Foram obtidos os extratos aquoso, etanólico e hexanólico de vegetais, amplamente consumidos no Brasil, como berinjela (Solanum melongena L., couve-flor (Brassica oleracea L., couve (Brassica oleracea L., brócolis (Brassica oleracea L., couve-de-bruxelas (Brassicaoleraea L., cebola (Allium cepa L., alho (Allium sativum L.; vegetais que apresentam gosto amargo, como jiló (Solanum gilo Raddi, guariroba (Syagrus oleracea Becc., mostarda (Brassica nigra L., carqueja (Cacalia spp., e de plantas relacionadas, na cultura popular, como curadoras de determinadas doenças, como a babosa (Aloe vera L.. A atividade da enzima foi determinada usando como substrato o 1 cloro 2, 4 dinitrobenzeno, na presença dos extratos vegetais. A mistura da reação, sem a presença do extrato, foi considerada controle. Das amostras de vegetais avaliadas, a berinjela, a couve e o brócolis apresentaram maior indução na atividade da GST, sendo o extrato etanólico o mais eficaz. A enzima apresentou um Vmax de 0,016 abs. min-1/unidade da enzima e um Km de 0,323mM. O baixo valor de Km encontrado indica uma alta especificidade da enzima pelo substrato 1 cloro 2, 4 dinitrobenzeno e a atividade máxima da enzima foi na faixa de pH entre 6,5 e 7,0.This study was done to evaluate induction Glutathione S-Transferase, with vegetable extracts, and characterize its kinetics parameters. The aqueous, alcoholic, and hexanoic extracts were obtained from vegetables widely consumed in Brazil: eggplant (Solanum melongena L., cauliflower (Brassica oleracea L., cauli leaves (Brassica oleracea L., broccoli (Brassica oleracea L., Brussels sprout (Brassicaoleraea L., onions (Allium cepa L., garlic (Allium sativum L.; and bitter tasting vegetable such as jiló (Solanum gilo Raddi, guariroba (Syagrus oleracea Becc., black mustard
Directory of Open Access Journals (Sweden)
Fauze A. Aouada
2009-01-01
Full Text Available In this paper, the effects of acrylamide (AAm, methylcellulose (MC contents, pH and ionic strength on kinetic, network and hydrophilic properties of polyacrylamide and methylcellulose hydrogels were investigated. The hydrogels were characterized by evaluating of network [average molecular weight between crosslinks (M C, crosslink density (q and the number of elastically effective chains (Ve], and kinetic parameters [diffusional exponent (n, diffusion constant (k and diffusion coefficient (D]. Such properties were controlled by adjusting of the AAm, MC contents, pH and ionic strength factors. Due to high hydrophilicity and fast water-uptake, the PAAm-MC hydrogels can be considered as materials for potential applications in agricultural fields, mainly in controlled release of water or pesticides.
BENAK, H; ENGBERTS, JBFN; BLANDAMER, MJ
1992-01-01
Over the range 288.15 less-than-or-equal-to T/K less-than-or-equal-to 333.15, the first-order rate constant for the neutral hydrolysis of 1-benzoyl-3-phenyl-1,2,4-triazole in aqueous solutions (pH ca. 4) decreases when either ethanol or propan-1-ol is added. The kinetic data are analysed in terms of
Crystallization Kinetics within a Generic Modeling Framework
DEFF Research Database (Denmark)
Meisler, Kresten Troelstrup; von Solms, Nicolas; Gernaey, Krist V.;
2014-01-01
A new and extended version of a generic modeling framework for analysis and design of crystallization operations is presented. The new features of this framework are described, with focus on development, implementation, identification, and analysis of crystallization kinetic models. Issues related...... to the modeling of various kinetic phenomena like nucleation, growth, agglomeration, and breakage are discussed in terms of model forms, model parameters, their availability and/or estimation, and their selection and application for specific crystallization operational scenarios under study. The advantages...... of employing a well-structured model library for storage, use/reuse, and analysis of the kinetic models are highlighted. Examples illustrating the application of the modeling framework for kinetic model discrimination related to simulation of specific crystallization scenarios and for kinetic model parameter...
Institute of Scientific and Technical Information of China (English)
胡春平; 颜学峰
2009-01-01
A new version of differential evolution(DE)algorithm,in which immurle concepts and methods are applied to determine the parameter setting.named immune self-adaptive difierential evolution(ISDE),iS proposed to improve the performance of the DE algorithm.During the actual operation.ISDE seeks the optimal parameters arising from the evolutionary process.which enable ISDE to alter the algorithm for different optimization problems and improve the performance Of ISDE bv the control parameters'self-adaptation.The performance of the proposed method is studied with the use of nine benchmark problems and compared with original DE algorithm and other well-known self-adaptive DE algorithms.The experiments conducted show that the ISDE clearly outperforms the othcr DE algorithms in all benchmark functions.Furthermore.ISDE iS applied to develop the kinetic model for homogeneous mercury (Hg) oxidation in tlue gas,and satistactory results are obtained.
Directory of Open Access Journals (Sweden)
Cristiane Mita
2008-07-01
Full Text Available Entomopathogenic fungus Beauveria bassiana is currently used as a biocontrol agent for agricultural pests. The infection process involves extracellular enzymes such as proteases and chitinases that degrade the cuticle of the insects. The objective of this work was to evaluate kinetic parameters of pH, temperature, ionic concentration and time of reaction on chitinases activity. The fungus B. bassiana CG432 was cultivated on coffee berry borer Hypothenemus hampei (Ferrari and the conidia grown on insect were used to prepare the inoculum containing 108conídia/mL. These conidia were inoculated at 1% (v/v in culture liquid medium containing D-glucose (10g, yeast extract (5g, NaNO3 (1,58g, Na2HPO4.7H2O (1,05g, KCl (1g, MgSO4.7H2O (0,6g and KH2PO4 (0,36g per liter. The cultivation was carried at 28°C and 180rpm during 5 days. Culture fluid was obtained by filtration and centrifugation at 8.000g, and the chitinases were isolated and concentrated by ultrafiltration using 10 and 100kDa cut off membranes under nitrogen pressure. Chitinase activity was detected and quantified using N-acetylglucosamine released by hydrolysis of colloidal chitin at 40 to 60ºC, at 50, 100 and 200 mM ionic concentrations of buffers sodium acetate (pH 4.0 to 6.0; sodium phosphate (pH 6.0 to 8.0; and Glycine-NaOH (pH 8.0 to 10.0 during 60 minutes. Maximum chitinase activity was at 45ºC and pH 5.5, and was also high at pH 6.0 and pH 8.5 using 50mM buffer. The chitinase activity increased and was stable during an hour at optimum conditions of the reaction, shown the stable nature of this enzyme.Beauveria bassiana é um fungo entomopatogênico utilizado no controle biológico de insetos-praga que infestam produtos agrícolas. O mecanismo de infecção envolve a produção de enzimas extracelulares, como proteases e quitinases que degradam a cutícula dos insetos. O objetivo deste trabalho foi avaliar parâmetros cinéticos de pH, temperatura, concentração iônica e tempo de
Kinetics of tetrataenite disordering
Energy Technology Data Exchange (ETDEWEB)
Dos Santos, E., E-mail: edisanfi@cbpf.br [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro (Brazil); Gattacceca, J.; Rochette, P. [Centre Européen de Recherche et d’Enseignement des Géosciences de l’Environnement, UM34, CNRS/Aix-Marseille University, Aix-en-Provence (France); Fillion, G. [Laboratoire National des Champs Magnétiques Intenses (LNCMI), CNRS, UJF, 38042 Grenoble (France); Scorzelli, R.B. [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro (Brazil)
2015-02-01
Tetrataenite is a chemically ordered L1{sub 0}-type Fe{sub 50}Ni{sub 50} alloy detected for the first time in 1977 by {sup 57}Fe Mössbauer spectroscopy studies in iron meteorites. The thermal history of meteorites, in particular short thermal events like those associated to hypervelocity impacts, can be constrained by tracing the presence of tetrataenite or its disordering into taenite. The knowledge of the disordering kinetics of tetrataenite, that is associated with changes in its magnetic properties, is still very fragmentary so that the time–temperature history of these meteorites cannot be constrained in details. Furthermore, knowledge of disordering kinetics is important due to potential technological application of tetrataenite as a rare-earth free strong magnet. Thus, this work provides the first time–temperature data for disordering reaction of tetrataenite. We have shown that disordering is not an instantaneous process but is a kinetic limited reaction. It was shown that disordering may take place at any temperature above the order–disorder transition for L{sub 10} superstructure phase (∼320 °C) when the appropriate time-scale is considered. This result means that the apparent Curie point for tetrataenite is not an absolute property in the sense that any estimate of this parameter should be referred to a given time-scale. - Highlights: • The first time–temperature data for tetrataenite disordering reaction is provided. • Previous works does not give a complete picture of tetrataenite disordering. • Apparent Curie temperature of tetrataenite should be referred to a time-scale. • Tetrataenite can be used as a probe to detect thermal/shock events recorded in meteorites.
Saffman-Taylor fingers with kinetic undercooling
Gardiner, Bennett P. J.
2015-02-23
© 2015 American Physical Society. The mathematical model of a steadily propagating Saffman-Taylor finger in a Hele-Shaw channel has applications to two-dimensional interacting streamer discharges which are aligned in a periodic array. In the streamer context, the relevant regularization on the interface is not provided by surface tension but instead has been postulated to involve a mechanism equivalent to kinetic undercooling, which acts to penalize high velocities and prevent blow-up of the unregularized solution. Previous asymptotic results for the Hele-Shaw finger problem with kinetic undercooling suggest that for a given value of the kinetic undercooling parameter, there is a discrete set of possible finger shapes, each analytic at the nose and occupying a different fraction of the channel width. In the limit in which the kinetic undercooling parameter vanishes, the fraction for each family approaches 1/2, suggesting that this "selection" of 1/2 by kinetic undercooling is qualitatively similar to the well-known analog with surface tension. We treat the numerical problem of computing these Saffman-Taylor fingers with kinetic undercooling, which turns out to be more subtle than the analog with surface tension, since kinetic undercooling permits finger shapes which are corner-free but not analytic. We provide numerical evidence for the selection mechanism by setting up a problem with both kinetic undercooling and surface tension and numerically taking the limit that the surface tension vanishes.
Stochastic optimization-based study of dimerization kinetics
Indian Academy of Sciences (India)
Srijeeta Talukder; Shrabani Sen; Ralf Metzler; Suman K Banik; Pinaki Chaudhury
2013-11-01
We investigate the potential of numerical algorithms to decipher the kinetic parameters involved in multi-step chemical reactions. To this end, we study dimerization kinetics of protein as a model system. We follow the dimerization kinetics using a stochastic simulation algorithm and combine it with three different optimization techniques (genetic algorithm, simulated annealing and parallel tempering) to obtain the rate constants involved in each reaction step. We find good convergence of the numerical scheme to the rate constants of the process. We also perform a sensitivity test on the reaction kinetic parameters to see the relative effects of the parameters for the associated profile of the monomer/dimer distribution.
Kinetic comparisons of mesophilic and thermophilic aerobic biomass
Vogelaar, J.C.T.; Klapwijk, A.; Temmink, H.; Lier, van J.B.
2003-01-01
Kinetic parameters describing growth and decay of mesophilic (30degreesC) and thermophilic (55degreesC) aerobic biomass were determined in continuous and batch experiments by using oxygen uptake rate measurements
Kinetic parameters describing growth and decay of mesophilic (30degreesC) and therm
An improved evaluation method for fault tree kinetic analysis
International Nuclear Information System (INIS)
By means of the exclusive sum of products of a fault tree, the improved method uses the basic event parameters direct in the synthetic evaluation and makes the fault tree kinetic analysis more simple. This paper provides a reasonable evaluation method for the kinetic analysis of basic events which has parameters of the synthetic distribution, too
Institute of Scientific and Technical Information of China (English)
孙新; 曾卫东; 张志金; 贾志强; 徐建伟
2015-01-01
对TC17合金在820和860℃下进行等温锻造，随后在相同温度下进行热处理10 min~8 h，利用定量金相法研究变形量、热处理温度等工艺参数对片状α相静态球化的影响规律。结果表明：随着变形量的增加，在随后热处理过程中片状α相更容易发生晶界分离而形成球化组织，球化速率明显提高。温度影响扩散过程，对静态球化有促进作用，且在应变较低时影响更为明显。在球化率随热处理时间增大的同时，球化速率逐渐减小至常值， JMAK方程可以用来描述TC17合金静态球化的规律。%The isothermal compression of TC17 alloy at 820 and 860℃, andsubsequently annealing for 10 min−8 h were conducted, and the effects of deformation degree, annealing temperature and annealing time on static globularization of TC17 titanium alloy were investigated. The results show that the deformation degree greatly influences the boundary splitting, so that the static globularization kinetics ofα phase increases with increasing deformation degrees. As a thermally activated process, the diffusivity of solutes is determined by annealing temperature. Thus, the static globularization can be accelerated by increasing the temperature, especially when the strain is low. Meanwhile, globularization ratio increases while static globularization kinetics decrease to a constant with increasing the annealing time. The JMAK equation can be used to describe the static globularization kinetics.
Directory of Open Access Journals (Sweden)
Miguel A Rosa
2010-01-01
Full Text Available Se estimaron parámetros cinéticos del mecanismo de biodegradación aeróbica de efluentes lácteos, empleando técnicas de simulación, estimación de parámetros y análisis sensitivo, disponibles en el software Aquasim v 2.1b. Se utilizó un reactor tanque agitado discontinuo de 4 litros de capacidad con inyección de aire permanente. El consumo de sustrato se representó considerando cinética de primer orden en un caso y del tipo de Monod en el otro. Se obtuvo un elevado valor de la constante de Monod, K S, lo cual limitó el análisis a la primera alternativa. Los valores hallados de los parámetros de respiración endógena k d y síntesis celular Y, fueron similares en ambos casos, mientras que el análisis sensitivo determinó parámetros de Monod no identificables. Se concluye que para este caso resulta válida una cinética de primer orden para representar el consumo de sustrato y se destaca la importancia de esta herramienta para efectuar el análisis.The kinetic constants of an aerobic biodegradation mechanism of dairy wastewaters were estimated using techniques of simulation, estimation of parameters and sensitivity analysis, available in the software Aquasim v 2.1b. A discontinuous, agitated reactor, of 4 liters capacity with a permanent air injection was used. Two kinetic models, Monod and first order were considered to represent substrate consumption as a function of time. Due to a high value of Monod's constant, K S, the data analysis was restricted to the first kinetic proposed. The values obtained for the parameters of endogenous breathing k d and cellular synthesis Y, were similar, whereas the sensitivity analysis revealed non-identifying Monod parameters. The importance of this software to carry out the analysis shown above and the validation of the first order kinetic for representing the substrate consumption are two of the most important conclusions of this work.
Determining anaerobic degradation kinetics from batch tests.
Moreda, Iván López
2016-01-01
Data obtained from a biomethane potential (BMP) test were used in order to obtain the parameters of a kinetic model of solid wastes anaerobic degradation. The proposed model considers a hydrolysis step with a first order kinetic, a Monod kinetic for the soluble organic substrate degradation and a first order decay of microorganisms. The instantaneous release of methane was assumed. The parameters of the model are determined following a direct search optimization procedure. A 'multiple-shooting' technique was used as a first step of the optimization process. The confidence interval of the parameters was determined by using Monte Carlo simulations. Also, the distribution functions of the parameters were determined. Only the hydrolysis first order constant shows a normal distribution. PMID:27191569
Sulfide toxicity kinetics of a uasb reactor
Directory of Open Access Journals (Sweden)
D. R. Paula Jr.
2009-12-01
Full Text Available The effect of sulfide toxicity on kinetic parameters of anaerobic organic matter removal in a UASB (up-flow anaerobic sludge blanket reactor is presented. Two lab-scale UASB reactors (10.5 L were operated continuously during 12 months. The reactors were fed with synthetic wastes prepared daily using glucose, ammonium acetate, methanol and nutrient solution. One of the reactors also received increasing concentrations of sodium sulfide. For both reactors, the flow rate of 16 L.d-1 was held constant throughout the experiment, corresponding to a hydraulic retention time of 15.6 hours. The classic model for non-competitive sulfide inhibition was applied to the experimental data for determining the overall kinetic parameter of specific substrate utilization (q and the sulfide inhibition coefficient (Ki. The application of the kinetic parameters determined allows prediction of methanogenesis inhibition and thus the adoption of operating parameters to minimize sulfide toxicity in UASB reactors.
Directory of Open Access Journals (Sweden)
Alario F.
2006-12-01
Full Text Available Cet article est une synthèse du travail fait en commun entre la Division Informatique et Mathématiques Appliquées DIMAet la division Cinétique et Catalyse de l'Institut Français du Pétrole. On y expose une nouvelle approche mathématique pour la validation d'un formalisme cinétique : la déshydrocyclisation du n-heptane. This article is an overview of the work carried out together by the DIMAand the Cinétique et Catalysedivision of the Institut Français du Pétrole. It is a new mathematical approach to validate a kinetic formalization : the n-heptane dehydrocyclization.
Chemical and Biological Kinetics
Emanuel', N. M.
1981-10-01
Examples of the application of the methods and ideas of chemical kinetics in various branches of chemistry and biology are considered and the results of studies on the kinetics and mechanisms of autoxidation and inhibited and catalysed oxidation of organic substances in the liquid phase are surveyed. Problems of the kinetics of the ageing of polymers and the principles of their stabilisation are discussed and certain trends in biological kinetics (kinetics of tumour growth, kinetic criteria of the effectiveness of chemotherapy, problems of gerontology, etc.) are considered. The bibliography includes 281 references.
Hydrogen electrode reaction: A complete kinetic description
Energy Technology Data Exchange (ETDEWEB)
Quaino, P.M. [Programa de Electroquimica Aplicada e Ingenieria Electroquimica (PRELINE), Facultad de Ingenieria Quimica, Universidad Nacional del Litoral, Santiago del Estero 2829, 3000 Santa Fe (Argentina); Gennero de Chialvo, M.R. [Programa de Electroquimica Aplicada e Ingenieria Electroquimica (PRELINE), Facultad de Ingenieria Quimica, Universidad Nacional del Litoral, Santiago del Estero 2829, 3000 Santa Fe (Argentina); Chialvo, A.C. [Programa de Electroquimica Aplicada e Ingenieria Electroquimica (PRELINE), Facultad de Ingenieria Quimica, Universidad Nacional del Litoral, Santiago del Estero 2829, 3000 Santa Fe (Argentina)]. E-mail: achialvo@fiqus.unl.edu.ar
2007-09-15
The kinetic description of the hydrogen electrode reaction (HER) in the whole range of overpotentials (-0.2 < {eta} (V) < 0.40) is presented. The Volmer-Heyrovsky-Tafel mechanism was solved considering simultaneously the following items: (i) the diffusional contribution of the molecular hydrogen from and towards the electrode surface, (ii) the forward and backward reaction rates of each elementary step and (iii) a Frumkin type adsorption for the reaction intermediate. In order to verify the descriptive capability of the kinetic expressions derived, an experimental study of the HER was carried out on a rotating platinum disc electrode in acid solution. From the correlation of these results the elementary kinetic parameters were evaluated and several aspects related to the kinetic mechanism were discussed. Finally, the use of these kinetic expressions to interpret results obtained on microelectrodes is also analysed.
Oxidation kinetics of aluminum diboride
International Nuclear Information System (INIS)
The oxidation characteristics of aluminum diboride (AlB2) and a physical mixture of its constituent elements (Al+2B) were studied in dry air and pure oxygen using thermal gravimetric analysis to obtain non-mechanistic kinetic parameters. Heating in air at a constant linear heating rate of 10 °C/min showed a marked difference between Al+2B and AlB2 in the onset of oxidation and final conversion fraction, with AlB2 beginning to oxidize at higher temperatures but reaching nearly complete conversion by 1500 °C. Kinetic parameters were obtained in both air and oxygen using a model-free isothermal method at temperatures between 500 and 1000 °C. Activation energies were found to decrease, in general, with increasing conversion for AlB2 and Al+2B in both air and oxygen. AlB2 exhibited O2-pressure-independent oxidation behavior at low conversions, while the activation energies of Al+2B were higher in O2 than in air. Differences in the composition and morphology between oxidized Al+2B and AlB2 suggested that Al2O3–B2O3 interactions slowed Al+2B oxidation by converting Al2O3 on aluminum particles into a Al4B2O9 shell, while the same Al4B2O9 developed a needle-like morphology in AlB2 that reduced oxygen diffusion distances and increased conversion. The model-free kinetic analysis was critical for interpreting the complex, multistep oxidation behavior for which a single mechanism could not be assigned. At low temperatures, moisture increased the oxidation rate of Al+2B and AlB2, but both appear to be resistant to oxidation in cool, dry environments. - Graphical abstract: Isothermal kinetic data for AlB2 in air, showing a constantly decreasing activation energy with increasing conversion. Model-free analysis allowed for the calculation of global kinetic parameters despite many simultaneous mechanisms occurring concurrently. (a) Time–temperature plots, (b) conversion as a function of time, (c) Arrhenius plots used to calculate activation energies, and (d) activation energy
Ozone mass transfer and kinetics experiments
Energy Technology Data Exchange (ETDEWEB)
Bollyky, L.J.; Beary, M.M.
1981-12-01
Experiments were conducted at the Hanford Site to determine the most efficient pH and temperature levels for the destruction of complexants in Hanford high-level defense waste. These complexants enhance migration of radionuclides in the soil and inhibit the growth of crystals in the evaporator-crystallizer. Ozone mass transfer and kinetics tests have been outlined for the determination of critical mass transfer and kinetics parameters of the ozone-complexant reaction.
Ozone mass transfer and kinetics experiments
International Nuclear Information System (INIS)
Experiments were conducted at the Hanford Site to determine the most efficient pH and temperature levels for the destruction of complexants in Hanford high-level defense waste. These complexants enhance migration of radionuclides in the soil and inhibit the growth of crystals in the evaporator-crystallizer. Ozone mass transfer and kinetics tests have been outlined for the determination of critical mass transfer and kinetics parameters of the ozone-complexant reaction
Fractal-like adsorption kinetics of Pb2+ in rocks
Institute of Scientific and Technical Information of China (English)
XU Longjun; ZHOU Zhengguo; LIU Chenglun; XIAN Xuefu
2008-01-01
The adsorption kinetics of Pb2+ in rocks has been studied using ion selective electrodes and atomic absorption spectrophotometer. The results showed that the adsorption process is a fractal-like reaction. The adsorption rate was relatively high before 30 minutes, and then dropped. The saturated adsorption capacity (a) of Pb2+ and kinetic parameters (b, α , D and k) increased with increasing initial concentrations of Pb2+. These parameters (except a) decreased while Na+ was present in the solution. Furthermore, the smaller the rocks were in grain size, the bigger these kinetic parameters would be, though the parameter a was almost constant.
Energy Technology Data Exchange (ETDEWEB)
Jeong, K.Y.; Kaufman, F.
1982-05-13
The Arrhenius A values of 10 related H-abstraction reactions are calculated by using the thermochemical kinetics version of transition-state (TS) theory. Methanol and halomethanols are used as reference compounds for the transition state, and their entropies are corrected for spin, external and internal rotation, and changes of vibration frequencies on the basis of various assumed transition-state geometries. Standard halomethanol entropies are estimated in several ways by bond and group additivity and by analogy. Tunneling corrections are calculated on the basis of a triatomic bond energy-bond order (BEBO) model of the transition state. A sensitivity analysis on transition-state bond lengths and angles shows weak dependence on length and favors a bent (approx.150-165/sup 0/) C...H...O geometry. The principal result shows good agreement on average between theoretical and experimental A values, A/sup th//A/sup exptl/ = 1.14 +/- 0.71 for 150/sup 0/ angle, but with larger than expected deviations, i.e., roughly a factor of 4 (X2 to X1/2) at the single standard deviation level. No physical explanations (dipole, van der Waals interactions, tunneling effects) could be found to rationalize the experimental trends.
Gorban, A. N.; Karlin, I. V.
2003-01-01
Nonlinear kinetic equations are reviewed for a wide audience of specialists and postgraduate students in physics, mathematical physics, material science, chemical engineering and interdisciplinary research. Contents: The Boltzmann equation, Phenomenology and Quasi-chemical representation of the Boltzmann equation, Kinetic models, Discrete velocity models, Direct simulation, Lattice Gas and Lattice Boltzmann models, Minimal Boltzmann models for flows at low Knudsen number, Other kinetic equati...
Kinetic Modeling of Esterification of Ethylene Glycol with Acetic Acid
International Nuclear Information System (INIS)
The reaction kinetics of the esterification of ethylene glycol with acetic acid in the presence of cation exchange resin has been studied and kinetic models based on empirical and Langmuir approach has been developed. The Langmuir based model involving eight kinetic parameters fits experimental data much better compared to empirical model involving four kinetic parameters. The effect of temperature and catalyst loading on the reaction system has been analyzed. Further, the activation energy and frequency factor of the rate constants for Langmuir based model has been estimated.
Institute of Scientific and Technical Information of China (English)
汪量子; 姚栋; 王侃
2012-01-01
A method of using iterated fission probability to estimate the adjoint fluence during particles simulation, and using it as the weighting function to calculate kinetics parameters βell and A in Monte Carlo codes, was introduced in this paper. Implements of this method in continuous energy Monte Carlo code MCNP and multi-group Monte Carlo code MCMG are both elaborated. Verification results show that, with regardless additional computing cost, using this method, the adjoint fluence accounted by MCMG matches well with the result computed by ANISN, and the kinetics parameters calculated by MCNP agree very well with benchmarks. This method is proved to be reliable, and the function of calculating kinetics parameters in Monte Carlo codes is carried out effectively, which could be the basement for Monte Carlo codes' utility in the analysis of nuclear reactors' transient behavior.%文章介绍了在蒙特卡罗程序中,使用反复裂变几率的统计结果作为共轭通量的估计,并作为权重函数计算动力学参数βeff和Λ的方法,阐释了在连续能量蒙特卡罗程序MCNP和多群蒙特卡罗程序MCMG中实现这种方法的过程.数值校验结果表明:在几乎不带来附加计算量的同时,在MCMG中使用该方法统计得到的共轭通量与ANISN的共轭通量计算结果符合较好,在MCNP中使用该方法计算得到的中子动力学参数与基准测量结果符合较好.在蒙特卡罗程序中实现了高效率计算中子动力学参数的功能,为蒙特卡罗程序进一步用于反应堆动态行为的分析奠定了基础.
Directory of Open Access Journals (Sweden)
A.R.G.F. Bezerra
2005-08-01
Full Text Available Parâmetros cinéticos da degradação ruminal de alguns alimentos utilizados para ruminantes de zoológicos foram estimados mediante incubação in vitro com líquido ruminal de audade (Ammotragus lervia, cervo sambar (Cervus unicolor, elande (Taurotragus oryx, bovino (Bos taurus, bubalino (Bubalus bubalis, caprino (Capra hircus e ovino (Ovis aries. Os parâmetros cinéticos foram estimados pela técnica da produção de gás, cujos dados foram ajustados pelos modelos de um e de duplo compartimento. Não foram detectadas diferenças nos parâmetros cinéticos que permitissem agrupar os alimentos (fibrosos × não fibrosos e os animais (domésticos × silvestres. O modelo de duplo compartimento foi o mais adequado para a estimação dos parâmetros cinéticos da degradação ruminal. Inóculo microbiano oriundo de ruminantes domésticos não é recomendado para estimar parâmetros cinéticos da degradação ruminal de alimentos utilizados para ruminantes silvestres de zoológicos.The estimation of the ruminal kinetic parameters of pumpkin, potato-sweet, beet, broccoli, carrot, alfalfa hay, alfalfa pellet and bean, currently used for feeding wild and domestic ruminants raised in the Rio de Janeiro Zoo, was made through in vitro incubation of the feedstuffs together with ruminal fluid obtained from aoudad (Ammotragus lervia, sambar deer (Cervus unicolor, eland (Taurotragus oryx, cattle (Bos taurus, buffalo (Bubalus bubalis, goat (Capra hircus and sheep (Ovis aries. The gas production technique was used to obtain gas profiles, and the data were fitted by the mono or double compartmental model. The kinetic parameters were discrepant among both, animals and feedstuffs, and the double compartmental model gave the best estimation. Ruminal inocula from domestic ruminants can not be used to estimate the kinetic parameters of ruminal degradation of feedstuffs for wild ruminants.
Extracting kinetic information from literature with KineticRE.
Freitas, Ana Alão; Costa, Hugo; Rocha, Miguel; Rocha, Isabel
2015-01-01
To better understand the dynamic behavior of metabolic networks in a wide variety of conditions, the field of Systems Biology has increased its interest in the use of kinetic models. The different databases, available these days, do not contain enough data regarding this topic. Given that a significant part of the relevant information for the development of such models is still wide spread in the literature, it becomes essential to develop specific and powerful text mining tools to collect these data. In this context, this work has as main objective the development of a text mining tool to extract, from scientific literature, kinetic parameters, their respective values and their relations with enzymes and metabolites. The approach proposed integrates the development of a novel plug-in over the text mining framework @Note2. In the end, the pipeline developed was validated with a case study on Kluyveromyces lactis, spanning the analysis and results of 20 full text documents. PMID:26673933
On fast reactor kinetics studies
Energy Technology Data Exchange (ETDEWEB)
Seleznev, E. F.; Belov, A. A. [Nuclear Safety Inst. of the Russian Academy of Sciences IBRAE (Russian Federation); Matveenko, I. P.; Zhukov, A. M.; Raskach, K. F. [Inst. for Physics and Power Engineering IPPE (Russian Federation)
2012-07-01
The results and the program of fast reactor core time and space kinetics experiments performed and planned to be performed at the IPPE critical facility is presented. The TIMER code was taken as computation support of the experimental work, which allows transient equations to be solved in 3-D geometry with multi-group diffusion approximation. The number of delayed neutron groups varies from 6 to 8. The code implements the solution of both transient neutron transfer problems: a direct one, where neutron flux density and its derivatives, such as reactor power, etc, are determined at each time step, and an inverse one for the point kinetics equation form, where such a parameter as reactivity is determined with a well-known reactor power time variation function. (authors)
Energy Technology Data Exchange (ETDEWEB)
Morales R, P.; Vallarino K, T.; Cruz V, V.; Delgadillo H, A. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)
2003-07-01
The objective of the present work was to establish pharmacokinetic parameters of the C Mitomycin (MMC) in vivo, comparing its kinetics of induction of polychromatic micro nucleate erythrocytes (EPGMN) with that of the gamma radiation. The used doses were of 0.75; 1.5 and 3. 0 {mu}moles/kg of MMC. It was observed that the MMC produces MN in the first cycle of cellular division and it is independent of the cytotoxic effect. This agent requires of a relatively long period of latency that is not compatible with her great reactivity, for what the pharmacokinetic values obtained in fact reflect the time that takes the processing of leisure in the DNA and the subsequent induction of ruptures that produce MN. (Author)
Kinetics of yttrium oxide carbochlorination
Energy Technology Data Exchange (ETDEWEB)
Gaviria, J.P., E-mail: gaviriaj@cab.cnea.gov.ar [Division Cinetica Quimica - Complejo Tecnologico Pilcaniyeu - Centro Atomico Bariloche - Comision Nacional de Energia Atomica, Av. Bustillo km 9500 (8400), S.C. de Bariloche, Rio Negro (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (Argentina); Fouga, G.G. [Division Cinetica Quimica - Complejo Tecnologico Pilcaniyeu - Centro Atomico Bariloche - Comision Nacional de Energia Atomica, Av. Bustillo km 9500 (8400), S.C. de Bariloche, Rio Negro (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (Argentina); Bohe, A.E. [Division Cinetica Quimica - Complejo Tecnologico Pilcaniyeu - Centro Atomico Bariloche - Comision Nacional de Energia Atomica, Av. Bustillo km 9500 (8400), S.C. de Bariloche, Rio Negro (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (Argentina); Centro Regional Universitario Bariloche - Universidad Nacional del Comahue (Argentina)
2011-04-20
Research highlights: {yields} Chlorination kinetics of Y{sub 2}O{sub 3}-C system was studied by thermogravimetry. {yields} The influence of carbon content, flow rate, sample mass and pCl{sub 2} were evaluated. {yields} Reaction proceeds through three successive stages until the formation of YCl{sub 3}(l). {yields}STAGE I is the formation of YOCl(s) and is under chemical control for T < 700 {sup o}C. {yields}STAGE I follows a nucleation and growth model. Kinetics parameters were obtained. - Abstract: The chlorination kinetics of the Y{sub 2}O{sub 3}-sucrose carbon system was studied by thermogravimetry. This work is a continuation of a previous one in which the reaction stages and the stoichiometry of each reaction have been determined. The influence of carbon content, total flow rate, sample initial mass and chlorine partial pressure was evaluated. The effect of carbon content on the reactive mixture was studied between 6.7 and 70% (carbon mass/total mass). The results showed that the reaction rate of each stage is strongly increased as the carbon content increases and the range of occurrence of the stages depends on the amount of carbon in the solid reactive mixture. The formation reaction of YOCl (STAGE I) is chemically controlled for temperatures lower than 700 {sup o}C with average effective activation energies of 165 {+-} 6 and 152 {+-} 7 kJ/mol for 8.7 and 16.7%C, respectively. The formation of the YOCl follows a nucleation and growth mechanism, with a combination of continuous nucleation and site saturation, and anisotropic growth controlled by diffusion. The kinetics of STAGE I can be expressed by the following global rate equation that includes the variables analyzed: (d{alpha})/(dt) =k{sub 0}Bexp(-(Ea)/(R{sub g}T) )pCl{sub 2}{l_brace}n(1-{alpha})[-ln(1-{alpha})]{r_brace}{sup (n-1)/n} where k{sub 0}B = 1.9 x 10{sup 4}, n = 1.20 for 8.7%C, and k{sub 0}B = 8.4 x 10{sup 3}, n = 1.14 for 16.7%C. STAGES II and III correspond to the YOCl carbochlorination to
Kinetic study of biological hydrogen production by anaerobic fermentation
Energy Technology Data Exchange (ETDEWEB)
Sangeetha, R. [Annamalai Univ., Chidambaram (India). Dept. of Chemical Engineering; Karunanithi, T. [Annamalai Univ., Tamilnadu (India). Dept. of Chemical Engineering
2009-07-01
This study examined the kinetics of batch biohydrogen production from glucose. Clostridium pasteurianum was used to produce biohydrogen by dark anaerobic fermentation. The initial substrate concentration, initial pH and temperature were optimized for biohydrogen production. The maximum production of hydrogen under optimum conditions was found to be 5.376 l/l. The kinetic parameters were determined for the optimized medium and conditions in the batch reactor. The by product was expressed as total acidic equivalent. This presentation discussed the logistic equation that was used to model the growth of the organism and described how the kinetic parameters were calculated. The Leudeking piret kinetic model was used to express the hydrogen production and substrate use because it combines both growth associated and non associated contributions. It was concluded the production of biohydrogen can be predicted well using the logistic model for cell growth kinetics and the logistic incorporated Leudeking Piret model for product and substrate utilization kinetics.
Introduction to chemical kinetics
Soustelle, Michel
2013-01-01
This book is a progressive presentation of kinetics of the chemical reactions. It provides complete coverage of the domain of chemical kinetics, which is necessary for the various future users in the fields of Chemistry, Physical Chemistry, Materials Science, Chemical Engineering, Macromolecular Chemistry and Combustion. It will help them to understand the most sophisticated knowledge of their future job area. Over 15 chapters, this book present the fundamentals of chemical kinetics, its relations with reaction mechanisms and kinetic properties. Two chapters are then devoted to experimental re
Principles of chemical kinetics
House, James E
2007-01-01
James House's revised Principles of Chemical Kinetics provides a clear and logical description of chemical kinetics in a manner unlike any other book of its kind. Clearly written with detailed derivations, the text allows students to move rapidly from theoretical concepts of rates of reaction to concrete applications. Unlike other texts, House presents a balanced treatment of kinetic reactions in gas, solution, and solid states. The entire text has been revised and includes many new sections and an additional chapter on applications of kinetics. The topics covered include quantitative rela
SKIN KINETICS AND DERMAL CLEARANCE
Directory of Open Access Journals (Sweden)
Prakash Shashi
2012-08-01
Full Text Available Availability of several therapeutic and cosmetic formulations for topical application has made the research on skin kinetics as a topic of current interest. Topical formulations are typically meant for local effect although there is always a chance that the low molecular weight chemicals are easily transported across the skin layer and make it available in the systemic circulation. Thus there is a major concern about the transport of chemical moieties following the topical application of cosmetics and therapeutic formulations and the real time measurement of the molecules in the skin layer has become obligatory. It is well known that the properties of both drug and the excipients have identical role in determining the skin permeability of chemical moieties. In the last decade several investigations have been carried out in this filed using several in vitro and in vivo models. This review provides a brief account on the basics of skin kinetics, parameters assessed, various techniques and methods adapted in skin kinetic studies. Moreover, we have also discussed about the micro-environment inside the skin layer and the possible mechanism of drug depot formation, skin metabolism and clearance of molecules from the skin layers.
Fribrinolysis Kinetics and Its Application
Institute of Scientific and Technical Information of China (English)
WEI Wenning; YANG Rui; GUO Tao; YANG Yan; HU Yu
2007-01-01
A new, convenient, and rapid method for kinetic measurement of human fibrinolysis was established. The alteration of absorbance (A) in the process of blood coagulation and lyses was automatically scanned and recorded using a UV2000 spectrophotometer connected to a computer. The parameters of human fibrinolysis kinetics were established. Urokinase at 20 U/mL was the optimal concentration used. There was significant difference in fibrinolysis kinetics and plasma plasminogen concentration between 22 normal subjects and 27 patients with acute myeloblastic leukemia (P＜0.05 and ＜0.01 respectively). The coefficience of variation was (5.24±1.51)%. This method could also be used to measure the plasma fibrinogen concentration at the same time. It was concluded that this method was stable and was capable of providing dynamic, direct experimental data and multiparemeters for clinicians. It was also valuable in evaluating the anti- and pro-fibrinolytic capcity of patients' plasmas, allowing for monitoring of therapy, choice of drugs and adjustment of drug concentrations.
Inflationary dynamics of kinetically-coupled gauge fields
DEFF Research Database (Denmark)
Ferreira, Ricardo J. Z.; Ganc, Jonathan
2015-01-01
We investigate the inflationary dynamics of two kinetically-coupled massless U(1) gauge fields with time-varying kinetic-term coefficients. Ensuring that the system does not have strongly coupled regimes shrinks the parameter space. Also, we further restrict ourselves to systems that can be quant...
Kinetics of the Exothermic Decomposition Reaction of s-Tripicryaminotrinitrobenzene
Institute of Scientific and Technical Information of China (English)
ZHAO Feng-qi; HU Rong-zu; GAO Hong-xu; LUO Yang; GAO Sheng-li; SONG Ji-rong; SHI Qi-zhen
2007-01-01
The kinetic parameters of the exothermic decomposition reaction of s-Tripicryaminotrinitrobenzene under linear temperature rise condition are studied by means of DSC. The results show that the empirical kinetic model function in difs-1, respectively. The critical temperature of thermal explosion of the compound is 267.36 ℃.
A STUDY ON THE CRYSTALLIZATION KINETICS OF NYLON 1010
Institute of Scientific and Technical Information of China (English)
CHEN Shouxi
1997-01-01
The kinetic behavior of isothermal and nonisothermal crystallization of nylon-1010has been studied by means of dilatometry and differential scanning calorimetry, respectively. The isothermal and nonisothermal process can be described by Avrami equation and Ozawa equation, respectively. From the experimental results the kinetic parameters of crystallization and crystalline mechanism for isothermal and nonisothermal measurements are discussed.
Hot forming recrystallization kinetics in steel
Directory of Open Access Journals (Sweden)
J. Kliber
2010-01-01
Full Text Available The theory of kinetics of static recrystallization of steel during hot forming links the phenomenon to certain critical strain, grain size, strain rate, activation energy and temperature. The basic description is provided by the Avrami equation. An overview of equations used was compiled and comments on selected parameters prepared.
Hot forming recrystallization kinetics in steel
J. Kliber; Fabík, R.; Vitez, I.; Drozd, K.
2010-01-01
The theory of kinetics of static recrystallization of steel during hot forming links the phenomenon to certain critical strain, grain size, strain rate, activation energy and temperature. The basic description is provided by the Avrami equation. An overview of equations used was compiled and comments on selected parameters prepared.
Swanson, Donald Gary
2008-01-01
Developed from the lectures of a leading expert in plasma wave research, Plasma Kinetic Theory provides the essential material for an introductory course on plasma physics as well as the basis for a more advanced course on kinetic theory. Exploring various wave phenomena in plasmas, it offers wide-ranging coverage of the field. After introducing basic kinetic equations and the Lenard–Balescu equation, the book covers the important Vlasov–Maxwell equations. The solutions of these equations in linear and quasilinear approximations comprise the majority of kinetic theory. Another main topic in kinetic theory is to assess the effects of collisions or correlations in waves. The author discusses the effects of collisions in magnetized plasma and calculates the different transport coefficients, such as pressure tensor, viscosity, and thermal diffusion, that depend on collisions. With worked examples and problem sets that enable sound comprehension, this text presents a detailed, mathematical approach to app...
Oxidation kinetics of aluminum diboride
Whittaker, Michael L.; Sohn, H. Y.; Cutler, Raymond A.
2013-11-01
The oxidation characteristics of aluminum diboride (AlB2) and a physical mixture of its constituent elements (Al+2B) were studied in dry air and pure oxygen using thermal gravimetric analysis to obtain non-mechanistic kinetic parameters. Heating in air at a constant linear heating rate of 10 °C/min showed a marked difference between Al+2B and AlB2 in the onset of oxidation and final conversion fraction, with AlB2 beginning to oxidize at higher temperatures but reaching nearly complete conversion by 1500 °C. Kinetic parameters were obtained in both air and oxygen using a model-free isothermal method at temperatures between 500 and 1000 °C. Activation energies were found to decrease, in general, with increasing conversion for AlB2 and Al+2B in both air and oxygen. AlB2 exhibited O2-pressure-independent oxidation behavior at low conversions, while the activation energies of Al+2B were higher in O2 than in air. Differences in the composition and morphology between oxidized Al+2B and AlB2 suggested that Al2O3-B2O3 interactions slowed Al+2B oxidation by converting Al2O3 on aluminum particles into a Al4B2O9 shell, while the same Al4B2O9 developed a needle-like morphology in AlB2 that reduced oxygen diffusion distances and increased conversion. The model-free kinetic analysis was critical for interpreting the complex, multistep oxidation behavior for which a single mechanism could not be assigned. At low temperatures, moisture increased the oxidation rate of Al+2B and AlB2, but both appear to be resistant to oxidation in cool, dry environments.
Saffman-Taylor fingers with kinetic undercooling
Gardiner, Bennett P J; Dallaston, Michael C; Moroney, Timothy J
2015-01-01
The mathematical model of a steadily propagating Saffman-Taylor finger in a Hele-Shaw channel has applications to two-dimensional interacting streamer discharges which are aligned in a periodic array. In the streamer context, the relevant regularisation on the interface is not provided by surface tension, but instead has been postulated to involve a mechanism equivalent to kinetic undercooling, which acts to penalise high velocities and prevent blow-up of the unregularised solution. Previous asymptotic results for the Hele-Shaw finger problem with kinetic undercooling suggest that for a given value of the kinetic undercooling parameter, there is a discrete set of possible finger shapes, each analytic at the nose and occupying a different fraction of the channel width. In the limit in which the kinetic undercooling parameter vanishes, the fraction for each family approaches 1/2, suggesting that this 'selection' of 1/2 by kinetic undercooling is qualitatively similar to the well-known analogue with surface tens...
A kinetic model for predicting biodegradation.
Dimitrov, S; Pavlov, T; Nedelcheva, D; Reuschenbach, P; Silvani, M; Bias, R; Comber, M; Low, L; Lee, C; Parkerton, T; Mekenyan, O
2007-01-01
Biodegradation plays a key role in the environmental risk assessment of organic chemicals. The need to assess biodegradability of a chemical for regulatory purposes supports the development of a model for predicting the extent of biodegradation at different time frames, in particular the extent of ultimate biodegradation within a '10 day window' criterion as well as estimating biodegradation half-lives. Conceptually this implies expressing the rate of catabolic transformations as a function of time. An attempt to correlate the kinetics of biodegradation with molecular structure of chemicals is presented. A simplified biodegradation kinetic model was formulated by combining the probabilistic approach of the original formulation of the CATABOL model with the assumption of first order kinetics of catabolic transformations. Nonlinear regression analysis was used to fit the model parameters to OECD 301F biodegradation kinetic data for a set of 208 chemicals. The new model allows the prediction of biodegradation multi-pathways, primary and ultimate half-lives and simulation of related kinetic biodegradation parameters such as biological oxygen demand (BOD), carbon dioxide production, and the nature and amount of metabolites as a function of time. The model may also be used for evaluating the OECD ready biodegradability potential of a chemical within the '10-day window' criterion.
The kinetic modelling from domestic ores using software tools
Krstev, Aleksandar; Krstev, Boris; Gocev, Zivko; Golomeov, Blagoj; Golomeova, Mirjana; Zendelska, Afrodita
2013-01-01
To improve kinetic models, many first - order flotation kinetics models with distributions of flotation rate constants were redefined so that they could all be represented by the same set of three model parameters. As a result, the width of the distribution become independent of its mean, and parameters of the model and the curve fitting errors, became virtually the same, independent of the chosen distribution function. In our case, investigations of the chalcopyrite ores are carried out usin...
Kinetic simulating experiment on the secondary hydrocarbon generation of kerogen
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
The kinetic parameters of generation have been obtained for different hydrocarbon classes, including methane, C2-C5 gas hydrocarbons, C6-C13 light hydrocarbons and C13+ heavy hydrocarbons, and vitrinite reflectance (Ro) by the kinetic simulating experiment of kerogen cracking. Then, combined with the detailed geology of Sichuan Basin, the effective gas-generating intensity of the Lower Cambrian source rock is approximately estimated by applying these parameters.
Directory of Open Access Journals (Sweden)
Bruno Botelho Saléh
2009-01-01
Full Text Available O objeto desta pesquisa foi à obtenção e avaliação dos parâmetros cinéticos do reator anaeróbio de manta de lodo (UASB-Upflow Anaerobic Sludge Blanket na remoção da carga orgânica poluidora dos despejos da atividade laticinista. O sistema com suas principais unidades foi composto de tratamento preliminar (caixa de areia e flotadores,tanque de contato (TC, reator UASB, filtro anaeróbio (FAB e lodo ativo em batelada (LAB. Os TDH’s (tempos de detenção hidráulicos e a temperatura adotados para o reator UASB foram de 44, 35, 30, 26 e 20h após a fase de estabilização do sistema, com temperatura média de 24,8ºC ± 1,8ºC. O volume do reator era de 394 L. A partir dos dadosDQOT (mg L-1, Sólidos Totais Fixos e Voláteis (mg L-1, Temperatura (°C, Vazão (L dia-1 e Perfil de Lodo no reator (Sólidos Voláteis Totais em mg L-1, monitorados durante todo o período de pesquisa na estação-piloto, em cada um dos tempos de detenção hidráulicos(TDH’s no reator UASB, foi conduzido o estudo para obtenção dos parâmetros cinéticos: coeficiente de crescimento ‘Y’ (mg DQO mg SVT-1 d-1, coeficiente de decaimento ‘Kd’ (d-1, taxa máxima de crescimento ‘μmáx’ (d-1 e concentração de substrato limitante ‘Ks’ (mg DQO L-1. Os parâmetros cinéticos determinados se basearam em estudos de regressão linear para determinação de Y, Kd, μmáx e Ks, respectivamente, dando, assim, respaldo técnico-científicoaos dados físico-químicos levantados durante a operacionalização do sistema.The goal of this research was to obtain and withdraw the kinetic parameters from an Upflow Anaerobic Sludge Blanket – UASB in removing the organic load from the waste by-product of a dairy activity. The treatment system was composed of a Sand Interceptor (Grit Chamber, Grease Intercept Chambers, Stirred Contact Tank (CT, a UASB reactor, Anaerobic Filter (AF, and Batch Activated Sludge System (BASS. The HRT (Hydraulic Retention Time and
Modelling heart rate kinetics.
Directory of Open Access Journals (Sweden)
Maria S Zakynthinaki
Full Text Available The objective of the present study was to formulate a simple and at the same time effective mathematical model of heart rate kinetics in response to movement (exercise. Based on an existing model, a system of two coupled differential equations which give the rate of change of heart rate and the rate of change of exercise intensity is used. The modifications introduced to the existing model are justified and discussed in detail, while models of blood lactate accumulation in respect to time and exercise intensity are also presented. The main modification is that the proposed model has now only one parameter which reflects the overall cardiovascular condition of the individual. The time elapsed after the beginning of the exercise, the intensity of the exercise, as well as blood lactate are also taken into account. Application of the model provides information regarding the individual's cardiovascular condition and is able to detect possible changes in it, across the data recording periods. To demonstrate examples of successful numerical fit of the model, constant intensity experimental heart rate data sets of two individuals have been selected and numerical optimization was implemented. In addition, numerical simulations provided predictions for various exercise intensities and various cardiovascular condition levels. The proposed model can serve as a powerful tool for a complete means of heart rate analysis, not only in exercise physiology (for efficiently designing training sessions for healthy subjects but also in the areas of cardiovascular health and rehabilitation (including application in population groups for which direct heart rate recordings at intense exercises are not possible or not allowed, such as elderly or pregnant women.
Kinetics of phase transformations
International Nuclear Information System (INIS)
This volume contains papers presented at the Materials Research Society symposium on Kinetics of Phase Transformations held in Boston, Massachusetts from November 26-29, 1990. The symposium provided a forum for research results in an exceptionally broad and interdisciplinary field. Presentations covered nearly every major class of transformations including solid-solid, liquid-solid, transport phenomena and kinetics modeling. Papers involving amorphous Si, a dominant topic at the symposium, are collected in the first section followed by sections on four major areas of transformation kinetics. The symposium opened with joint sessions on ion and electron beam induced transformations in conjunction with the Surface Chemistry and Beam-Solid Interactions: symposium. Subsequent sessions focused on the areas of ordering and nonlinear diffusion kinetics, solid state reactions and amorphization, kinetics and defects of amorphous silicon, and kinetics of melting and solidification. Seven internationally recognized invited speakers reviewed many of the important problems and recent results in these areas, including defects in amorphous Si, crystal to glass transformations, ordering kinetics, solid-state amorphization, computer modeling, and liquid/solid transformations
Irreversible processes kinetic theory
Brush, Stephen G
2013-01-01
Kinetic Theory, Volume 2: Irreversible Processes deals with the kinetic theory of gases and the irreversible processes they undergo. It includes the two papers by James Clerk Maxwell and Ludwig Boltzmann in which the basic equations for transport processes in gases are formulated, together with the first derivation of Boltzmann's ""H-theorem"" and a discussion of this theorem, along with the problem of irreversibility.Comprised of 10 chapters, this volume begins with an introduction to the fundamental nature of heat and of gases, along with Boltzmann's work on the kinetic theory of gases and s
Adsorption kinetics of methyl violet onto perlite.
Doğan, Mehmet; Alkan, Mahir
2003-01-01
This study examines adsorption kinetics and activation parameters of methyl violet on perlite. The effect of process parameters like contact time, concentration of dye, temperature and pH on the extent of methyl violet adsorption from solution has been investigated. Results of the kinetic studies show that the adsorption reaction is first order with respect to dye solution concentration with activation energy of 13.2 kJ mol(-1). This low activation energy value indicates that the adsorption reaction is diffusion controlled. The activation parameters using Arrhenius and Eyring equations have been calculated. Adsorption increases with increase of variables such as contact time, initial dye concentration, temperature and pH.
Comparative study of gyrokinetic, hybrid-kinetic and fully kinetic wave physics for space plasmas
Told, Daniel; Muller, Florian; Astfalk, Patrick; Jenko, Frank
2016-01-01
A set of numerical solvers for the linear dispersion relations of the gyrokinetic, the hybrid-kinetic, and the fully kinetic model is employed to study the physics of the kinetic Alfv\\'en wave and the fast magnetosonic mode in these models. In particular, we focus on parameters that are relevant for solar wind oriented applications (using a homogeneous, isotropic background), which are characterized by wave propagation angles averaging close to 90{\\deg}. It is found that the gyrokinetic model, while lacking high-frequency solutions and cyclotron effects, faithfully reproduces the fully kinetic Alfv\\'en wave physics close to, and sometimes significantly beyond, the boundaries of its range of validity. The hybrid-kinetic model, on the other hand, is much more complete in terms of high-frequency waves, but owing to its simple electron model it is found to severely underpredict wave damping rates even on ion spatial scales across a large range of parameters, despite containing full kinetic ion physics.
Oxidation and hydrolysis kinetic studies on UN
Rao, G. A. Rama; Mukerjee, S. K.; Vaidya, V. N.; Venugopal, V.; Sood, D. D.
1991-11-01
The reaction of oxygen and water vapour with UN microspheres containing 0.78 and 10.9 mol% UO 2 as impurity was studied under non-isothermal heating conditions in a thermobalance under different partial pressures of oxygen, a fixed pressure of water vapour in argon, and in air. Uranium mononitride was ultimately converted to U 3O 8, with the formation of UO 2 and U 2N 3 as intermediates. The end product of pyrohydrolysis was UO 2. The kinetic parameters were evaluated and the mechanism of the reaction was suggested. Different kinetic models were used to explain the oxidation behaviour of UN.
Kinetic modeling in pre-clinical positron emission tomography
Energy Technology Data Exchange (ETDEWEB)
Kuntner, Claudia [AIT Austrian Institute of Technology GmbH, Seibersdorf (Austria). Biomedical Systems, Health and Environment Dept.
2014-07-01
Pre-clinical positron emission tomography (PET) has evolved in the last few years from pure visualization of radiotracer uptake and distribution towards quantification of the physiological parameters. For reliable and reproducible quantification the kinetic modeling methods used to obtain relevant parameters of radiotracer tissue interaction are important. Here we present different kinetic modeling techniques with a focus on compartmental models including plasma input models and reference tissue input models. The experimental challenges of deriving the plasma input function in rodents and the effect of anesthesia are discussed. Finally, in vivo application of kinetic modeling in various areas of pre-clinical research is presented and compared to human data.
Computer prediction system on solid/solid reaction kinetics
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
A computer software system of kinetic predication of solid/solid reaction, KinPreSSR, was developed using Visual C++ and FoxPro. It includes two main modules, REACTION and DIFFUSION. KinPreSSR deals with the kinetics on the diffusion in solids as well as solid/solid reactions. The REACTION module in KinPreSSR was mainly described, which has organized the commonly recognized kinetic models, parameters, and employed both numerical and graphical methods for data analyses. The proper combination between the kinetic contents and the analytical methods enables users to use KinPreSSR for the evaluation and prediction of solid/solid reactions interested. As an example to show some of functions of KinPreSSR, the kinetics analysis for the reaction between SrCO3 and TiO2 powders to form SrTiO3 with a series of kinetic data from isothermal measurements was demonstrated.
Experimental Studies on Turbulence Kinetic Energy in Confined Vortex Flows
Institute of Scientific and Technical Information of China (English)
L.Yan; G.H.Vatistas; 等
2000-01-01
Turbulence kinetic energies in confined vortex flows have been studied.The studies were based on the experiments performed in a vortex chamber,In the experiments,a Laser Doppler Anemometry(LDA) was used to perform flow measurements inside the vortex chamber,which provided the data for the kinetic energy analysis.The studies concentrated on the influences of the contraction ratio and the inlet air flow rate on the kinetic energy,and analyzed the characteristics of the kinetic energy in the confined vortex flows,including the distributions of the tangential component,radial component and total turbulence kinetic energy,In the paper,both the experimental techniques and the experimental results were presented.Based on a similarity analyis and the experimental data,an empirical scaling formula was proposed so that the tangential component of the turbulence kinetic energy was dependent only on the parameter of the contraction ratio.
Cluster kinetics model for mixtures of glassformers.
Brenskelle, Lisa A; McCoy, Benjamin J
2007-10-14
For glassformers we propose a binary mixture relation for parameters in a cluster kinetics model previously shown to represent pure compound data for viscosity and dielectric relaxation as functions of either temperature or pressure. The model parameters are based on activation energies and activation volumes for cluster association-dissociation processes. With the mixture parameters, we calculated dielectric relaxation times and compared the results to experimental values for binary mixtures. Mixtures of sorbitol and glycerol (seven compositions), sorbitol and xylitol (three compositions), and polychloroepihydrin and polyvinylmethylether (three compositions) were studied. PMID:17935407
Parameter identification of thermophilic anaerobic degradation of valerate
DEFF Research Database (Denmark)
Flotats, X.; Ahring, Birgitte Kiær; Angelidaki, Irini
2003-01-01
identification was done optimizing the sum of the multiple determination coefficients for all measured state variables and for all experiments simultaneously. The estimated values of kinetic parameters and stoichiometric coefficients were characterized by the parameter correlation matrix, the confidence interval......The considered mathematical model of the decomposition of valerate presents three unknown kinetic parameters, two unknown stoichiometric coefficients, and three unknown initial concentrations for biomass. Applying a structural identifiability study, we concluded that it is necessary to perform...
Kinetic equations: computation
Pareschi, Lorenzo
2013-01-01
Kinetic equations bridge the gap between a microscopic description and a macroscopic description of the physical reality. Due to the high dimensionality the construction of numerical methods represents a challenge and requires a careful balance between accuracy and computational complexity.
SRD 17 NIST Chemical Kinetics Database (Web, free access) The NIST Chemical Kinetics Database includes essentially all reported kinetics results for thermal gas-phase chemical reactions. The database is designed to be searched for kinetics data based on the specific reactants involved, for reactions resulting in specified products, for all the reactions of a particular species, or for various combinations of these. In addition, the bibliography can be searched by author name or combination of names. The database contains in excess of 38,000 separate reaction records for over 11,700 distinct reactant pairs. These data have been abstracted from over 12,000 papers with literature coverage through early 2000.
Parameter estimation in food science.
Dolan, Kirk D; Mishra, Dharmendra K
2013-01-01
Modeling includes two distinct parts, the forward problem and the inverse problem. The forward problem-computing y(t) given known parameters-has received much attention, especially with the explosion of commercial simulation software. What is rarely made clear is that the forward results can be no better than the accuracy of the parameters. Therefore, the inverse problem-estimation of parameters given measured y(t)-is at least as important as the forward problem. However, in the food science literature there has been little attention paid to the accuracy of parameters. The purpose of this article is to summarize the state of the art of parameter estimation in food science, to review some of the common food science models used for parameter estimation (for microbial inactivation and growth, thermal properties, and kinetics), and to suggest a generic method to standardize parameter estimation, thereby making research results more useful. Scaled sensitivity coefficients are introduced and shown to be important in parameter identifiability. Sequential estimation and optimal experimental design are also reviewed as powerful parameter estimation methods that are beginning to be used in the food science literature.
Electrochemical kinetics theoretical aspects
Vetter, Klaus J
1967-01-01
Electrochemical Kinetics: Theoretical Aspects focuses on the processes, methodologies, reactions, and transformations in electrochemical kinetics. The book first offers information on electrochemical thermodynamics and the theory of overvoltage. Topics include equilibrium potentials, concepts and definitions, electrical double layer and electrocapillarity, and charge-transfer, diffusion, and reaction overvoltage. Crystallization overvoltage, total overvoltage, and resistance polarization are also discussed. The text then examines the methods of determining electrochemical reaction mechanisms
Institute of Scientific and Technical Information of China (English)
QIN Yan; LIU Haihua; HUANG Zhixiong; MEI Qilin
2007-01-01
Several kinetic models for unsaturated polyester cure reaction and some existing parameter estimation techniques of these models were introduced. Correlated kinetic parameters and kinetic equations of the autocatalytic empirical kinetic model of LPSMC system were determined by using isothermal DSC to scan the system which was thickened by crystalline polymer (PEG-MAH). Through using a serial curing degree of the system to validate the model, the experimental results were basically identical with the predictions of the autocatalytic empirical kinetic model. This model could provide a theoretical reference to the determination of molding techniques of low pressure SMC.
KINETICS OF HYDROLYSIS OF TRIBUTYRIN BY LIPASE
Directory of Open Access Journals (Sweden)
SULAIMAN AL-ZUHAIR
2006-06-01
Full Text Available Kinetics of the enzymatic hydrolysis of tributyrin using lipase has been investigated. The initial rate of reaction was determined experimentally at different substrate concentration by measuring the rate of butyric acid produced. Michaels-Menten kinetic model has been proposed to predict the initial rate of hydrolysis of tributyrin in micro-emulsion system. The kinetic parameters were estimated by fitting the data to the model using three methods, namely, the Lineweaver-Burk, Edie-Hofstee and Hanes methods. The Michaels-Menten model with the constant predicted by Edie-Hofstee and Hanes methods predicted the initial rate of reaction at various substrate concentrations better than the model with the constant predicted Lineweaver-Burk method, especially at high substrate concentrations.
Kinetics of solid state phase transformations: Measurement and modelling of some basic issues
Indian Academy of Sciences (India)
S Raju; E Mohandas
2010-01-01
A brief review of the issues involved in modelling of the solid state transformation kinetics is presented. The fact that apart from the standard thermodynamic parameters, certain path variables like heating or cooling rate can also exert a crucial influence on the kinetic outcome is stressed. The kinetic specialties that are intrinsic to phase changes proceeding under varying thermal history are enumerated. A simple and general modelling methodology for understanding the kinetics of non-isothermal transformations is outlined.
Institute of Scientific and Technical Information of China (English)
卢峥嵘; 赵萌; 沐万孟; 张涛; 江波
2009-01-01
In this paper,the optimal inulin fructotransferase-producing medium and fermentation kinetic parameters of Arthrobacter ureafaciens SK -8.001 were studied. The recipes of optimal media included 2. 5% inulin,0. 3% NaN0_3,0. 1% yeast extract,0. 01% MgSO_4,0. 04% KH_2P0_4,0. 001% FeSO_4·7H_2O. The maximum enzyme activity reached 19. 85 U/mL,which was 2. 04 fold higher than in initial media. The study on the fermentation process in the optimal media suggested the right time to add inducers into the media was 12 h or 66th hours during the fermentation. The cell growth kinetic model for SK-8.001 in batch fermentation was X (t) = 9. 356 05/ [1 + exp~((4.4222-0.1102l)) ].%对1株产菊糖果糖转移酶(inulin fructotransferase)的金黄色节杆菌(Arthrobacter ureafaciens)SK-8.001的产酶培养基进行了优化,同时对其在分批发酵过程中培养基组分变化和菌体生长动力学进行了研究.所得到的改进型产酶培养基配方为25 g/L菊糖,3 g/L NaNO_3,1g/L酵母膏,0.1 g/L MgSO_4,0.4g/L KH_2PO_4,0.01g/LFeSO_4·7H_2O.在此培养基中的最高酶活达到19.85 U/mL,较初始培养基提高了2.04倍.对在此培养基中Sk-8.001的发酵过程研究发现发酵12 h和66 h是较为理想的诱导物添加时刻.得到SK-8.001在优化培养基中分批培养的菌体生长动力学模型为:X(t)=9.356 05/[1+exp~((4.4222-0.1102:))].
Supramolecular polymer transformation: a kinetic study.
Baram, Jonathan; Weissman, Haim; Rybtchinski, Boris
2014-10-16
Investigation of supramolecular kinetics is essential for elucidating self-assembly mechanisms. Recently, we reported on a noncovalent system involving a bolaamphiphilic perylene diimide dimer that is kinetically trapped in water but can rearrange into a different, more ordered assembly in water/THF mixtures ( Angew. Chem. Int. Ed. 2014 , 53 , 4123 ). Here we present a kinetic mechanistic study of this process by employing UV-vis spectroscopy. The transformation exhibits a rapid decrease in the red-shifted absorption band, which is monitored in order to track the kinetics at different temperatures (15-50 °C) and concentrations. Fitting the data with the 1D KJMA (Kolmogorov-Johnson-Mehl-Avrami) model affords the activation parameters. The latter as well as seeding experiments indicates that the transformation occurs without the detachment of covalent units, and that hydration dynamics plays a significant role in nucleation, with entropic factors being dominant. Switching off the transformation, and the formation of off-pathway intermediates were observed upon heating to temperatures above 55 °C. These insights into kinetically controlled supramolecular polymer transformations provide mechanistic information that is needed for a fundamental understanding of noncovalent processes, and the rational design of noncovalent materials. PMID:25238603
Kinetic Initial Conditions for Inflation
Handley, W J; Lasenby, A N; Hobson, M P
2014-01-01
We consider the classical evolution of the inflaton field $\\phi(t)$ and the Hubble parameter $H(t)$ in homogeneous and isotropic single-field inflation models. Under an extremely broad assumption, we show that the universe generically emerges from an initial singularity in a non-inflating state where the kinetic energy of the inflaton dominates its potential energy, $\\dot{\\phi}^2 \\gg V(\\phi)$. In this kinetically-dominated regime, the dynamical equations admit simple analytic solutions for $\\phi(t)$ and $H(t)$, which are independent of the form of $V(\\phi)$. In such models, these analytic solutions thus provide a simple way of setting the initial conditions from which to start the (usually numerical) integration of the coupled equations of motion for $\\phi(t)$ and $H(t)$. We illustrate this procedure by applying it to spatially-flat models with polynomial and exponential potentials, and determine the background evolution in each case; generically $H(t)$ and $|\\phi(t)|$ as well as their time derivatives decrea...
The models of cosmological inflation in the context of kinetic approximation
Fomin, I.
2016-07-01
In this work the building of models of cosmological inflation with approximate linear dependence of the scalar field kinetic energy on the state parameter is considered. The key parameters of cosmological perturbations are also calculated.
Kinetic Study and Thermal Decomposition Behavior of Lignite Coal
Directory of Open Access Journals (Sweden)
Mehran Heydari
2015-01-01
Full Text Available A thermogravimetric analyzer was employed to investigate the thermal behavior and extract the kinetic parameters of Canadian lignite coal. The pyrolysis experiments were conducted in temperatures ranging from 298 K to 1173 K under inert atmosphere utilizing six different heating rates of 1, 6, 9, 12, 15, and 18 K min−1, respectively. There are different techniques for analyzing the kinetics of solid-state reactions that can generally be classified into two categories: model-fitting and model-free methods. Historically, model-fitting methods are broadly used in solid-state kinetics and show an excellent fit to the experimental data but produce uncertain kinetic parameters especially for nonisothermal conditions. In this work, different model-free techniques such as the Kissinger method and the isoconversional methods of Ozawa, Kissinger-Akahira-Sunose, and Friedman are employed and compared in order to analyze nonisothermal kinetic data and investigate thermal behavior of a lignite coal. Experimental results showed that the activation energy values obtained by the isoconversional methods were in good agreement, but Friedman method was considered to be the best among the model-free methods to evaluate kinetic parameters for solid-state reactions. These results can provide useful information to predict kinetic model of coal pyrolysis and optimization of the process conditions.
Multiple alternative substrate kinetics.
Anderson, Vernon E
2015-11-01
The specificity of enzymes for their respective substrates has been a focal point of enzyme kinetics since the initial characterization of metabolic chemistry. Various processes to quantify an enzyme's specificity using kinetics have been utilized over the decades. Fersht's definition of the ratio kcat/Km for two different substrates as the "specificity constant" (ref [7]), based on the premise that the important specificity existed when the substrates were competing in the same reaction, has become a consensus standard for enzymes obeying Michaelis-Menten kinetics. The expansion of the theory for the determination of the relative specificity constants for a very large number of competing substrates, e.g. those present in a combinatorial library, in a single reaction mixture has been developed in this contribution. The ratio of kcat/Km for isotopologs has also become a standard in mechanistic enzymology where kinetic isotope effects have been measured by the development of internal competition experiments with extreme precision. This contribution extends the theory of kinetic isotope effects to internal competition between three isotopologs present at non-tracer concentrations in the same reaction mix. This article is part of a special issue titled: Enzyme Transition States from Theory and Experiment.
International Nuclear Information System (INIS)
The physiological characteristics of man depend on the intake, metabolism and excretion of stable elements from food, water, and air. The physiological behavior of natural radionuclides and radionuclides from nuclear weapons testing and from the utilization of nuclear energy is believed to follow the pattern of stable elements. Hence information on the normal physiological processes occurring in the human body plays an important role in the assessment of the radiation dose received by man. Two important physiological parameters needed for internal dose determination are the pulmonary function and the water balance. In the Coordinated Research Programme on the characterization of Asian population, five participants submitted data on these physiological characteristics - China, India, Japan, Philippines and Viet Nam. During the CRP, data on other pertinent characteristics such as physical and dietary were simultaneously being collected. Hence, the information on the physiological characteristics alone, coming from the five participants were not complete and are probably not sufficient to establish standard values for the Reference Asian Man. Nonetheless, the data collected is a valuable contribution to this research programme
Adolph, H W; Maurer, P; Schneider-Bernlöhr, H; Sartorius, C; Zeppezauer, M
1991-11-01
1. The steady-state parameters kcat and Km and the rate constants of hydride transfer for the substrates isopropanol/acetone; (S)-2-butanol, (R)-2-butanol/2-butanone; (S)-2-pentanol, (R)-2-pentanol/2-pentanone; 3-pentanol/3-pentanone; (S)-2-octanol and (R)-2-octanol have been determined for the native Zn(II)-containing horse-liver alcohol dehydrogenase (LADH) and the specific active-site-substituted Co(II)LADH. 2. A combined evaluation of steady-state kinetic data and rate constants obtained from stopped-flow measurements, allowed the determination of all rate constants of the following ordered bi-bi mechanism: E in equilibrium E.NAD in equilibrium E.NAD.R1R2 CHOH in equilibrium E.NADH.R1R2CO in equilibrium E.NADH in equilibrium E. 3. On the basis of the different substrate specificities of LADH and yeast alcohol dehydrogenase (YADH), a procedure has been developed to evaluate the enantiomeric product composition of ketone reductions. 2-Butanone and 2-pentanone reductions revealed (S)-2-butanol (86%) and (S)-2-pentanol (95%) as the major products. 4. The observed enantioselectivity implies the existence of two productive ternary complexes; E.NADH.(pro-S) 2-butanone and E.NADH.(pro-R) 2-butanone. All rate constants describing the kinetic pathways of the system (S)-2-butanol, (R)-2-butanol/2-butanone have been determined. These data have been used to estimate the expected enantiomer product composition of 2-butanone reductions using apparent kcat/Km values for the two different ternary-complex configurations of 2-butanone. Additionally, these data have been used for computer simulations of the corresponding reaction cycles. Calculated, simulated and experimental data were found to be in good agreement. Thus, the system (S)-2-butanol, (R)-2-butanol/2-butanone is the first example of a LADH-catalyzed reaction for which the stereochemical course could be described in terms of rate constants of the underlying mechanism. 5. The effects of Co(II) substitution on the
Rein, Guillermo; Lautenberger, Chris; Fernandez-Pello, Carlos; Torero, Jose; URBAN, David
2006-01-01
In this work, the kinetic parameters governing the thermal and oxidative degradation of flexible polyurethane foam are determined using thermogravimetric data and a genetic algorithm. These kinetic parameters are needed in the theoretical modeling of the foam’s smoldering behavior. Experimental thermogravimetric mass-loss data are used to explore the kinetics of polyurethane foam and to propose a mechanism consisting of five reactions. A lumped model of solid mass-loss based on...
Bonitz, Michael
2016-01-01
This book presents quantum kinetic theory in a comprehensive way. The focus is on density operator methods and on non-equilibrium Green functions. The theory allows to rigorously treat nonequilibrium dynamics in quantum many-body systems. Of particular interest are ultrafast processes in plasmas, condensed matter and trapped atoms that are stimulated by rapidly developing experiments with short pulse lasers and free electron lasers. To describe these experiments theoretically, the most powerful approach is given by non-Markovian quantum kinetic equations that are discussed in detail, including computational aspects.
Drying kinetics of some building materials
Moropoulou, A.; M Karoglou; Giakoumaki, A.; Krokida, M. K.; Maroulis, Z. B.; G.D. Saravacos
2005-01-01
Moisture is one of the most deteriorating factors of buildings. The deteriorating effect of moisture occurs mainly during the drying phase, and not in the wetting phase. Appropriate parameters of the drying kinetics are required for the building materials. Environmental factors, such as air temperature, air humidity, and air velocity affect drying. An experimental air dryer of controlled drying air conditions was used to investigate the drying performance of 4 stone materials, 2 bricks and 7 ...
Hot forming recrystallization kinetics in steel
Kliber, Jiří; Fabík, Richard; Vitez, Ivan; Drozd, Kamil
2009-01-01
The theory of kinetics of static recrystallization of steel during hot forming links the phenomenon to certain critical strain, grain size, strain rate, activation energy and temperature. The basic description is provided by the Avrami equation. An overview of equations used was compiled and comments on selected parameters prepared. Teorija kinetike statičke rekristalizacije čelika tijekom vrućeg oblikovanja ovu pojavu povezuje s kritičnom deformacijom, veličinom zrna, brzinom deform...
Kinetic Theory of the Overlapping Phase Transformations
Valencia-Morales, E.; Galeano-Alvarez, N. J.; Vega-Leyva, J.; Villar, C. E.; Hernandez-Ruiz, J.
2003-01-01
Often a number of precipitation processes in steels and alloys occur simultaneously (they have the same origin in time) albeit at different rates. Consequently, isothermic transformations are accompanied, in this case, by the occurrence of second processes of precipitation that influence the changes of the macroscopic parameter chosen for the kinetic study while first processes are occurring. In this context a set-up is presented that addresses the issue of characterization of nucleation and ...
Kinetics of Dyes Adsorbed by Chitosan
Institute of Scientific and Technical Information of China (English)
CHEN Liang; CHEN Dong-hui; GAO Liang
2002-01-01
A study on adsorption of Acidic Blue RAWL and Cationic Blue X-GRRL dyes by chitosan have been conducted.The adsorption kinetic parameters including adsorption rate K and effective diffusing coefficient D'i under the optimal pH ranges have been determined. Analysis through the enthalpy calculation reveals a substantial thermodynamic difference between the adsorption processes of the two dyes, which helps to understand the adsorption mechanism by chitosan.
Directory of Open Access Journals (Sweden)
Edenio Detmann
2009-01-01
Full Text Available Objetivou-se neste experimento avaliar a cinética de degradação ruminal dos capins setária (Setaria anceps Stapf, hemarthria (Hemarthria altissima [Poir] Stapf. & Hubbard, angola (Brachiaria purpurascens [Raddi] Henr. e acroceres (Acroceras macrum Stapf. adubados com 0, 100, 200, 300 ou 400 kg de N/ha e colhidos aos 28, 42, 56 ou 70 dias de idade. Os resultados foram avaliados por intermédio de análise de fatores. Após redução e avaliação da variação conjunta total das variáveis, optou-se pela adoção de três fatores, que englobaram 86,4% da variação total: o primeiro fator (Fator 1 associou-se ao volume de gás oriundo das frações de lenta e de rápida degradação e à taxa de degradação da fração rapidamente degradável (Vf1, Vf2 e k2; o segundo fator (Fator 2 associou-se à taxa de degradação de lenta digestão e à latência (k1 e L; e o terceiro fator (Fator 3, por sua vez, associou-se à digestibilidade in vitro da matéria seca (DIVMS. Os parâmetros da cinética de degradação foram influenciados pelas idades de corte. A digestibilidade in vitro da matéria seca reduziu com o avançar da idade das plantas. A adubação nitrogenada não promoveu respostas evidentes nos parâmetros avaliados. O capim-hemarthria se destacou dos demais em virtude de maior digestibilidade.The objective of this experiment was to evaluate the effects of levels 0, 100, 200, 300 and 400 kg of nitrogen/ha and cutting ages of 28, 42, 56 and 70 days on the kinetic parameters of ruminal degradation of carbohydrate of the following tropical forages: Setaria grass (Setaria anceps Stapf, Limpo grass (Hemarthria altissima [Poir] Stapf. & Hubbard, California grass (Brachiaria purpurascens [Raddi] Henr. and Nilo grass (Acroceras macrum Stpaf. The results were submitted to a factor analysis. After reduction and evaluation of the combined variation from the total variables, three factors comprising 86.44% of the total variation were considered
A comparative study of kinetics of nuclear reactors
Directory of Open Access Journals (Sweden)
Obaidurrahman Khalilurrahman
2009-01-01
Full Text Available The paper deals with the study of reactivity initiated transients to investigate major differences in the kinetics behavior of various reactor systems under different operating conditions. The article also states guidelines to determine the safety limits on reactivity insertion rates. Three systems, light water reactors (pressurized water reactors, heavy water reactors (pressurized heavy water reactors, and fast breeder reactors are considered for the sake of analysis. The upper safe limits for reactivity insertion rate in these reactor systems are determined. The analyses of transients are performed by a point kinetics computer code, PKOK. A simple but accurate method for accounting total reactivity feedback in kinetics calculations is suggested and used. Parameters governing the kinetics behavior of the core are studied under different core states. A few guidelines are discussed to project the possible kinetics trends in the next generation reactors.
Empiricism or self-consistent theory in chemical kinetics?
International Nuclear Information System (INIS)
To give theoretical background for mechanochemical kinetics, we need first of all to find a possibility to predict the kinetic parameters for real chemical processes by determining rate constants and reaction orders without developing strictly specialized and, to a great extent, artificial models, i.e. to derive the kinetic law of mass action from 'first principles'. However, the kinetic law of mass action has had only an empirical basis from the first experiments of Gulberg and Waage until now, in contrast to the classical law of mass action for chemical equilibrium rigorously derived in chemical thermodynamics from equilibrium condition. Nevertheless, in this paper, an attempt to derive the kinetic law of mass action from 'first principles' is made in macroscopic formulation. It has turned out to be possible owing to the methods of thermodynamics of irreversible processes that were unknown in Gulberg and Waage's time
Thermal Decomposition Kinetics of Ni(Ⅱ) Complex with Norfloxacin
Institute of Scientific and Technical Information of China (English)
无
1999-01-01
The thermal decomposition of the [Ni(NFA)2(NO3)2]*2H2O (NFA=C16H18FN3O3, norfloxacin) and its kinetics were studied under the non-isothermal condition in nitrogen by TG-DTG and DTA methods. The intermediate and residue for each decomposition were identified from TG curve. The Achar method and the Madhusudanan-Krishnan-Ninan (MKN) method were used to analyze the non-isothermal kinetic data. The possible reaction mechanisms were investigated by comparing the kinetic parameters. The kinetic equation for the third stage and the mathematical expressions for the kinetic compensation effects of the third stage were obtained.
Modeling chemical kinetics graphically
A. Heck
2012-01-01
In literature on chemistry education it has often been suggested that students, at high school level and beyond, can benefit in their studies of chemical kinetics from computer supported activities. Use of system dynamics modeling software is one of the suggested quantitative approaches that could h
Kinetics and Catalysis Demonstrations.
Falconer, John L.; Britten, Jerald A.
1984-01-01
Eleven videotaped kinetics and catalysis demonstrations are described. Demonstrations include the clock reaction, oscillating reaction, hydrogen oxidation in air, hydrogen-oxygen explosion, acid-base properties of solids, high- and low-temperature zeolite reactivity, copper catalysis of ammonia oxidation and sodium peroxide decomposition, ammonia…
International Nuclear Information System (INIS)
A normalized form of the point kinetics equations, a prompt jump approximation, and the Nordheim-Fuchs model are used to model nuclear systems. Reactivity feedback mechanisms considered include volumetric expansion, thermal neutron temperature effect, Doppler effect and void formation. A sample problem of an excursion occurring in a plutonium solution accidentally formed in a glovebox is presented
Relativistic kinetic momentum operators
International Nuclear Information System (INIS)
In the framework of the quantum theory in the relativistic configuration r-space the kinetic momenta, corresponding to the half of the non-Euclidean distance in the Lobachevsky velocities space, are introduced. These operators, coinciding up to the constant factor with the generators of translations of the r-space, are the exterior derivatives of the noncommutative differential calculus
Parameter identification of thermophilic anaerobic degradation of valerate
DEFF Research Database (Denmark)
Flotats, X; Ahring, Birgitte Kiær; Angelidaki, Irini
2002-01-01
Mathematical model of the decomposition of valerate presents 3 unknown kinetic parameters, 2 unknown stoichiometric coefficients and 3 unknown initial concentrations for biomass. Applying a structural identifiability study, it is concluded that it is necessary to perform simultaneous batch experi...
Energy Technology Data Exchange (ETDEWEB)
Sharma, Priyamvada; Hemkar, Shalini; Khandelwal, C. L.; Sharma, P. D. [Univ. of Rajasthan, Jaipur (India)
2012-02-15
The kinetics of ruthenium(III) chloride catalyzed oxidation of butanone and uncatalyzed oxidation of cyclohexanone by cerium(IV) in sulphuric acid medium have been studied. The kinetic rate law(I) in case of butanone conforms to the proposed mechanism. Kinetics and activation parameters have been evaluated conventionally. Kinetically preferred mode of reaction is via ketonic and not the enolic forms.
Biosorption Parameter Estimation with Genetic Algorithm
Yung-Tse Hung; Eui Yong Kim; Xiao Feng; Khim Hoong Chu
2011-01-01
In biosorption research, a fairly broad range of mathematical models are used to correlate discrete data points obtained from batch equilibrium, batch kinetic or fixed bed breakthrough experiments. Most of these models are inherently nonlinear in their parameters. Some of the models have enjoyed widespread use, largely because they can be linearized to allow the estimation of parameters by least-squares linear regression. Selecting a model for data correlation appears to be dictated by the ea...
IMPORTANCE OF KINETIC MEASURES IN TRAJECTORY PREDICTION WITH OPTIMAL CONTROL
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Ömer GÜNDOĞDU
2001-02-01
Full Text Available A two-dimensional sagittally symmetric human-body model was established to simulate an optimal trajectory for manual material handling tasks. Nonlinear control techniques and genetic algorithms were utilized in the optimizations to explore optimal lifting patterns. The simulation results were then compared with the experimental data. Since the kinetic measures such as joint reactions and moments are vital parameters in injury determination, the importance of comparing kinetic measures rather than kinematical ones was emphasized.
Kinetics and mechanism of synthetic CoS oxidation process
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Štrbac N.
2006-01-01
Full Text Available The results of investigation of kinetics and mechanism for synthetic a-CoS oxidation process are presented in this paper. Based on experimental data obtained using DTA and XRD analysis and constructed PSD diagrams for Co-S-O system, mechanism of synthetic a-CoS oxidation process is suggested. Characteristic kinetic parameters were obtained for experimental isothermal investigations of desulfurization degree using Sharp method.
A Kinetic Model for the Energy Transfer in Phycobilisomes
Suter, Georg W.; Holzwarth, Alfred R.
1987-01-01
A kinetic model for the energy transfer in phycobilisome (PBS) rods of Synechococcus 6301 is presented, based on a set of experimental parameters from picosecond studies. It is shown that the enormous complexity of the kinetic system formed by 400-500 chromophores can be greatly simplified by using symmetry arguments. According to the model the transfer along the phycocyanin rods has to be taken into account in both directions, i.e., back and forth along the rods. The corresponding forward ra...
Unravelling the Maillard reaction network by multiresponse kinetic modelling
Martins, S.I.F.S.
2003-01-01
The Maillard reaction is an important reaction in food industry. It is responsible for the formation of colour and aroma, as well as toxic compounds as the recent discovered acrylamide. The knowledge of kinetic parameters, such as rate constants and activation energy, is necessary to predict its extent and, consequently, to optimise it. Each of the chapters presented in this thesis can be seen as a necessary step to succeed in applying multiresponse kinetic modelling in a complex reaction, su...
HCCI in a CFR engine: experiments and detailed kinetic modeling
Energy Technology Data Exchange (ETDEWEB)
Flowers, D; Aceves, S; Smith, R; Torres, J; Girard, J; Dibble, R
1999-11-05
Single cylinder engine experiments and chemical kinetic modeling have been performed to study the effect of variations in fuel, equivalence ratio, and intake charge temperature on the start of combustion and the heat release rate. Neat propane and a fuel blend of 15% dimethyl-ether in methane have been studied. The results demonstrate the role of these parameters on the start of combustion, efficiency, imep, and emissions. Single zone kinetic modeling results show the trends consistent with the experimental results.
Evaluation of reliability of Coats-Redfern method for kinetic analysis of non-isothermal TGA
Institute of Scientific and Technical Information of China (English)
R. Ebrahimi-Kahrizsangi; M. H. Abbasi
2008-01-01
A critical examination was made on the reliability of kinetic parameters of nonisothermal thermoanalytical rate measurement by the widely applied Coats-Redfern(CR) equation. For this purpose, simulated TGA curves were made for reactions with different kinetic models, including chemical, diffusion (Janders) and mixed mechanism at different heating rates. The results show that, for reactions controlled kinetically by one mechanism, all solid state reaction models show linear trends by use of CR method and this method can not distinct the correct reaction model. For reactions with mixed mechanism, the CR method shows nonlinear trends and the reaction models and kinetic parameters can not be extracted from CR curves. The overall conclusion from this comparative appraisal of the characteristics of the CR approach to kinetic analysis of TGA data is that the CR approach is generally unsuitable for determination of kinetic parameters.
Kinetics of the Thermal Decomposition of Wangjiatan Siderite
Institute of Scientific and Technical Information of China (English)
FENG Zhili; YU Yongfu; LIU Genfan; CHEN Wen
2011-01-01
The thermal decomposition processes of Wangjiatan siderite samples were studied in nitrogen by thermogravimetric(TG) analysis. The mechanism of thermal decomposition of the siderite obeyed an Fn kinetic law and the n-order was between 1.16 and 1.29. The results from non-isothermal experiments show that the size of particles has an obvious effect on the logarithm of pre-exponential factor in kinetics parameter of the thermal decomposition of Wangjiatan siderite. A linear relationship is shown between the size of particles and the logarithm of pre-exponential factor. An F1 kinetic model containing size factor describes the thermal decomposition of Wangjiatan siderite well.
Adsorption kinetics of propane on energetically heterogeneous activated carbon
Ismail, Azhar Bin
2014-11-01
The modeling of the adsorption isotherms and kinetics of the adsorbent+adsorbate pair is essential in simulating the performance of a pressurized adsorption chiller. In this work, the adsorption kinetics is analyzed from data measured using a magnetic suspension balance. The Statistical Rate Theory describes the Dubinin-Astakhov (DA) equation and extended to obtain an expression for transient analysis. Hence both the experimental excess equilibria data and the adsorption kinetics data may then be fitted to obtain the necessary parameters to fit the curves. The results fit the data very well within 6% of the error of regression. © 2014 Elsevier Ltd.
ASSESSMENT OF KINETIC PROCESSES OF HARDENING OF BUILDING MATERIALS
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P. V. Voronov
2010-12-01
Full Text Available Problem statement. Kinetic processes are of huge importance when producing building units and operating them as well. However, both technological and operation parameters are determined by the structure of a material under study.Results and conclusions. Kinetics with asymptotic approximation at hardening of building materials is analyzed. The validity of use of new kinetic equation is proved, characterizing harden composite systems and taking into consideration structural and topological peculiarities of new solid-like phase formation directly effecting the evolution of the processes. Results of research of change of strength at solidification a cement-sandy solution with various additives are submitted.
A Review of Kinetic Modeling Methodologies for Complex Processes
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de Oliveira Luís P.
2016-05-01
Full Text Available In this paper, kinetic modeling techniques for complex chemical processes are reviewed. After a brief historical overview of chemical kinetics, an overview is given of the theoretical background of kinetic modeling of elementary steps and of multistep reactions. Classic lumping techniques are introduced and analyzed. Two examples of lumped kinetic models (atmospheric gasoil hydrotreating and residue hydroprocessing developed at IFP Energies nouvelles (IFPEN are presented. The largest part of this review describes advanced kinetic modeling strategies, in which the molecular detail is retained, i.e. the reactions are represented between molecules or even subdivided into elementary steps. To be able to retain this molecular level throughout the kinetic model and the reactor simulations, several hurdles have to be cleared first: (i the feedstock needs to be described in terms of molecules, (ii large reaction networks need to be automatically generated, and (iii a large number of rate equations with their rate parameters need to be derived. For these three obstacles, molecular reconstruction techniques, deterministic or stochastic network generation programs, and single-event micro-kinetics and/or linear free energy relationships have been applied at IFPEN, as illustrated by several examples of kinetic models for industrial refining processes.
Institute of Scientific and Technical Information of China (English)
张灵; 杨晓兰; 白婧; 廖娟; 刘红博; 廖飞
2011-01-01
Objective:To establish a method based on analysis of the changes of kinetic parameters to characterize an inhibitor of glutathione-S-transferase (glutathione-S-transferases,GST). Methods:The acidic GST isozyme was purified from the porcine liver via anion-exchange chromatography and affinity chromatography. The reaction of glutathione (glutathione, GSH) and 1 -chloro-2,4-dini-trobenzene( 1, - chloro- 2,4- dinitrobenzene,CDNB) gave S-(2,4 -dinitrobenzyl) -glutathione (GS-DNB) as a candidate inhibitor. Michaelis-Menten constant(Km) and maximal reaction rate(Vm) were estimated to determine the inhibition constant (Ki) of GS-DNB. Results: Specific activity of GST was increased by more than 146 times with overall activity yield of about 30%. GST followed random bi-substrate kinetics and had Km of 42 |xmol/L for GSH,and Km of 0.86 mmol/L for CDNB. The competitive Ki of GS-DNB was (21 ± 1)μmol/L (n=2) against CDNB,and (17 ± 1) μmol/L (ra=2) against GSH. Conclusion:GS-DNB is an effective competitive inhibitor of GST;the estimation of Ki from responses of Km and Vm to inhibitor concentrations can be a conventional method to screen GST inhibitors.%目的:测定谷胱甘肽-S-转移酶(Glutathione-S-transferases,GST)动力学参数变化,建立表征其抑制剂的方法.方法:从猪肝经阴离子交换层析和亲和层析制备GST酸性同工酶,用还原型谷胱甘肽(Glutathione,GSH)和1-氯-2,4-二硝基苯(1,-chloro-2,4-dinitrobenzene,CDNB)合成S-(2,4-二硝基苯基)-谷胱甘肽(GS-DNB)为候选抑制剂,以GSH与CDNB为底物测定GST在GS-DNB作用下的米氏常数(Km)和最大反应速度(Vm),从而确定GS-DNB对GST的抑制常数(Ki).结果:此GST被纯化146倍以上,活性总收率近30％.该GST对GSH和CDNB的Km分别为42 μmol/L和0.86 mmol/L,属于随机双底物动力学模型.GS-DNB对CDNB竞争性Ki为(21±1)μmol/L (n=2)；对GSH竞争性Ki为(17±1)μmol/L (n=2).结论:产物GS-DNB是GST的高亲和力竞争性抑制剂；测定GST动力学
Kinetics model for lutate dosimetry
International Nuclear Information System (INIS)
The use of compartmental analysis to predict the behavior of drugs in the organism is considered the better option among numerous methods employed in pharmacodynamics. A six compartments model was developed to determinate the kinetic constants of 177Lu-DOTATATO biodistribution using data from one published study with 67 patients treated by PRRT (Peptide receptor radionuclide therapy) and followed by CT during 68,25 hours. The compartmental analysis was made using the software AnaComp®. The influence of the time pos-injection over the dose assessment was studied taking into account the renal excretion management by aminoacid coinfusion, whose direct effects persist in the first day. The biodistribution curve was split in five sectors: 0-0.25h; 0-3.25h; 3.25-24.25h; 24.25-68.25h and 3.25-68.25h. After the examination of that influence, the study was concentrated in separate the biodistribution curve in two phases. Phase 1: governed by uptake from the blood, considering the time pos-injection until 3.25h and phase 2: governed by renal excretion, considering the time pos-injection from 3.25h to 68.25h. The model considered the organs and tissues superposition in the CT image acquisition by sampling parameters as the contribution of the the activity concentration in blood and relation between the sizes of the whole body and measured organs. The kinetic constants obtained from each phase (1 and 2) were used in dose assessment to patients in 26 organs and tissues described by MIRD. Dosimetry results were in agreement with the available results from literature, restrict to whole body, kidneys, bone marrow, spleen and liver. The advantage of the proposed model is the compartmental method quickness and power to estimate dose in organs and tissues, including tumor that, in the most part, were not discriminate by voxels of phantoms built using CT images. (author)
A steady-state kinetic analysis of the prolyl-4-hydroxylase mechanism.
Soskel, N T; Kuby, S A
1981-01-01
Published kinetic data by Kivirikko, et al. on the prolyl-4-hydroxylase reaction have been re-evaluated using the overall steady-state velocity equation in the forward and reverse directions for an ordered ter ter kinetic mechanism. Qualitatively, the published data for prolyl-4-hydroxylase appear to fit the predicted patterns for this kinetic mechanism. More kinetic data are needed to confirm these results and to quantitate the kinetic parameters but, tentatively, the order of substrate addition would appear to be alpha-ketoglutarate, oxygen, and peptide; and the order of product release would be hydroxylated peptide (or collagen), carbon dioxide, and succinate.
Kinetic Actviation Relaxation Technique
Béland, Laurent Karim; El-Mellouhi, Fedwa; Joly, Jean-François; Mousseau, Normand
2011-01-01
We present a detailed description of the kinetic Activation-Relaxation Technique (k-ART), an off-lattice, self-learning kinetic Monte Carlo algorithm with on-the-fly event search. Combining a topological classification for local environments and event generation with ART nouveau, an efficient unbiased sampling method for finding transition states, k-ART can be applied to complex materials with atoms in off-lattice positions or with elastic deformations that cannot be handled with standard KMC approaches. In addition to presenting the various elements of the algorithm, we demonstrate the general character of k-ART by applying the algorithm to three challenging systems: self-defect annihilation in c-Si, self-interstitial diffusion in Fe and structural relaxation in amorphous silicon.
Directory of Open Access Journals (Sweden)
V.G. Morozov
2009-01-01
Full Text Available We present a kinetic theory of radiative processes in many-component plasmas with relativistic electrons and nonrelativistic heavy particles. Using the non-equilibrium Green's function technique in many-particle QED, we show that the transverse field correlation functions can be naturally decomposed into sharply peaked (non-Lorentzian parts that describe resonant (propagating photons and off-shell parts corresponding to virtual photons in the medium. Analogous decompositions are obtained for the longitudinal field correlation functions and the correlation functions of relativistic electrons. We derive a kinetic equation for the resonant photons with a finite spectral width and show that the off-shell parts of the particle and field correlation functions are essential to calculate the local radiating power in plasmas and recover the results of vacuum QED. The plasma effects on radiative processes are discussed.
International Nuclear Information System (INIS)
We study a recently proposed running kinetic inflation model in which the inflaton potential becomes flat due to rapid growth of the kinetic term at large inflaton field values. As concrete examples, we build a variety of chaotic inflation models in supergravity with e.g. quadratic, linear, and fractional-power potentials. The power of the potential generically increases after inflation, and the inflaton is often massless at the potential minimum in the supersymmetric limit, which leads to many interesting phenomena. First, the light inflaton mass greatly relaxes severe thermal and non-thermal gravitino problems. Secondly, the kination epoch is naturally present after inflation, which may enhance the gravity waves. Thirdly, since the inflaton is light, it is likely coupled to the Higgs sector for successful reheating. The inflaton and its superpartner, inflatino, may be produced at the LHC. Interestingly, the inflatino can be dark matter, if it is the lightest supersymmetric particle
Flocculation Kinetics of Chitosan
Institute of Scientific and Technical Information of China (English)
陈亮; 林志艳; 陈东辉
2003-01-01
Under the various conditions, the experiments of flocculation of bentonite solution with chitosan were carried out. And the flocculation kinetics was studied by the changes of floc size along with time. The results show that hydraulic gradient G (s-1) plays a key role in growing up of floc size and both of molecular weight and initial turbidity of bentonite solution influence the floc size in steady state and the time needed for steady floc size.
Faleiros A.C.; Rabelo T.N.; Thim G.P.; Oliveira M.A.S.
2000-01-01
The kinetic model for change of phases developed by M. Avrami at the end of the thirties has been used to describe the temporal behavior of phase changes. Until today this model is studied and adapted to include broader hypotheses. However, the mathematical format presented by M. Avrami is difficult to be understood by beginners. The purpose of this work is to clarify the mathematical treatment of Avrami's work, going straightforward to the arguments that led to his main results.
Directory of Open Access Journals (Sweden)
A.C. Faleiros
2000-07-01
Full Text Available The kinetic model for change of phases developed by M. Avrami at the end of the thirties has been used to describe the temporal behavior of phase changes. Until today this model is studied and adapted to include broader hypotheses. However, the mathematical format presented by M. Avrami is difficult to be understood by beginners. The purpose of this work is to clarify the mathematical treatment of Avrami's work, going straightforward to the arguments that led to his main results.
Thermal Decomposition Kinetics of Lead 2,4,6-Trinitroresorcinate Monohydrate
Institute of Scientific and Technical Information of China (English)
HU Rong-zu; YAO Pu; LI Jing; CHEN San-ping; GAO Sheng-li; ZHAO Feng-qi; SONG Ji-rong; SHI Qi-zhen; CHEN Pei; LUO Yang; ZHAO Hong-an
2004-01-01
The non-isothermal decomposition of lead 2,4,6-trinitroresorcinate monohydrate, Pb (TNR) · H2O. was investigated by means of TG-DTA, DSC and IR. The thermal decomposition mechanism and the dissociated kinetics were also investigated. The kinetic parameters were obtained from the analysis of the DSC curves by integral and differential methods. The most probable kinetic model function of the dehydration reaction of Pb(TNR) · H2O was suggested by the comparison of the kinetic parameters.
Drying kinetics of some building materials
Directory of Open Access Journals (Sweden)
A. Moropoulou
2005-06-01
Full Text Available Moisture is one of the most deteriorating factors of buildings. The deteriorating effect of moisture occurs mainly during the drying phase, and not in the wetting phase. Appropriate parameters of the drying kinetics are required for the building materials. Environmental factors, such as air temperature, air humidity, and air velocity affect drying. An experimental air dryer of controlled drying air conditions was used to investigate the drying performance of 4 stone materials, 2 bricks and 7 plasters. Drying kinetics was examined at 4 air temperatures, 6 air humidities, and 3 air velocities. A first-order kinetics model was obtained, in which the drying time constant was a function of the drying conditions, and the equilibrium material moisture content was described by the Oswin equation. The parameters of the proposed model were found to be affected strongly by the material and the drying air conditions. The results obtained are very useful in selecting the appropriate plaster to protect existing historic buildings.
Non-isothermal Kinetics of the Dehydration Process of Na2MoO4·2H20
Institute of Scientific and Technical Information of China (English)
张建军; 张秀芳; 武克忠; 任宁; 周雪; 刘晓地
2004-01-01
The dehydration process of Na2MoO4·2H2O and its kinetics have been studied by TG-DTG. Using Malek method, SB(m,n) was defined as the kinetic model of the dehydration process. The corresponding kinetic and thermodynamic parameters were obtained.
Yuki, Dai; Kikuchi, Akira; Miura, Naoki; Kakehi, Aoi; Onozawa, Masahiro
2013-11-01
This study investigated the relationship between plasma and saliva cotinine kinetics after smoking one cigarette and the relationship between cotinine kinetics and estimated nicotine intake, which was calculated as mouth level exposure (MLE) of nicotine, from smoking two test cigarettes with different nicotine yields. This study was conducted in 16 healthy adult Japanese smokers, who did not have null nor reduced-activity alleles of CYP2A6, with a quasi-randomized crossover design of smoking a low-tar cigarette or a high-tar cigarette. Saliva cotinine showed similar concentration profiles to plasma cotinine, and all of the calculated pharmacokinetic parameters of cotinine showed the same values in plasma and saliva. The Cmax and AUC of cotinine showed almost the same dose-responsiveness to the estimated MLE of nicotine between plasma and saliva, but the tmax and t1/2 of cotinine were not affected by the estimated MLE of nicotine in either plasma or saliva. The results show that saliva cotinine kinetics reflects plasma cotinine kinetics, and measurement of saliva cotinine concentration gives the same information as plasma cotinine on the nicotine intake. Thus, saliva cotinine would be a good and less-invasive exposure marker of cigarette smoke, reflecting the plasma cotinine concentration and kinetics.
Institute of Scientific and Technical Information of China (English)
杨永茂; 王平; 张艳; 孟宪丽; 陈瑛; 邱一行
2012-01-01
Objective To study the effects of severe acute pancreatitis (SAP) on absorption kinetic parameters of rhubarb free anthraquinones. Methods Eleven healthy Beagle dogs were randomly divided into the normal group (n =6) and the SAP group (n=5). The SAP animal model was prepared by surgery through portal vein blood channel building to collect blood from normal dogs and dogs with SAP. The free anthraquinones (20 mg/kg) was given by gastrogavage. The concentrations of five anthraquinones (aloe emodin, rhein, emod-in, chrysophanol, and physcion) in the blood plasma of the portal vein and the femoral artery were determined u-sing high performance liquid chromatography (HPLC). The kinetic parameters were calculated using MAT-LAB2007B Software. The half life (t1/2Ka), the absorption peak time (Tmax), the peak concentration (Cmax), the area under the curve [ AUC(0-∞)], and the mean residence time (MRT) were calculated using the statistical moment method. The transport velocity of corresponding medicines from the gastrointestinal tract to the blood (ka) was calculated. Results There was no difference in the chemical composition absorption type of the portal vein and the femory artery beween the two groups. Aloe emodin could be detected in the portal vein of each animal at each time point, and they were in the quantitative range. Rhein could be detected in the portal vein of each animal at each time point, and they were lower than the quantitative limit at few time points. Emodin and chrysophanol could be detected in the portal vein of partial animals at each time point, and most of them were higher than the quantitative limit. Physcion could be detected only in the portal vein of less animals at few time points. Rhein could be detected in the femoral artery at most time points, but the rhein plasma concentration at most time points were lower than the quantitative limit. Lower concentration of aloe emodin, emodin, and chrysophanol could be detected in the femoral artery at
Thermodynamically consistent model calibration in chemical kinetics
Directory of Open Access Journals (Sweden)
Goutsias John
2011-05-01
Full Text Available Abstract Background The dynamics of biochemical reaction systems are constrained by the fundamental laws of thermodynamics, which impose well-defined relationships among the reaction rate constants characterizing these systems. Constructing biochemical reaction systems from experimental observations often leads to parameter values that do not satisfy the necessary thermodynamic constraints. This can result in models that are not physically realizable and may lead to inaccurate, or even erroneous, descriptions of cellular function. Results We introduce a thermodynamically consistent model calibration (TCMC method that can be effectively used to provide thermodynamically feasible values for the parameters of an open biochemical reaction system. The proposed method formulates the model calibration problem as a constrained optimization problem that takes thermodynamic constraints (and, if desired, additional non-thermodynamic constraints into account. By calculating thermodynamically feasible values for the kinetic parameters of a well-known model of the EGF/ERK signaling cascade, we demonstrate the qualitative and quantitative significance of imposing thermodynamic constraints on these parameters and the effectiveness of our method for accomplishing this important task. MATLAB software, using the Systems Biology Toolbox 2.1, can be accessed from http://www.cis.jhu.edu/~goutsias/CSS lab/software.html. An SBML file containing the thermodynamically feasible EGF/ERK signaling cascade model can be found in the BioModels database. Conclusions TCMC is a simple and flexible method for obtaining physically plausible values for the kinetic parameters of open biochemical reaction systems. It can be effectively used to recalculate a thermodynamically consistent set of parameter values for existing thermodynamically infeasible biochemical reaction models of cellular function as well as to estimate thermodynamically feasible values for the parameters of new
Directory of Open Access Journals (Sweden)
Fernanda Maria Pagane Guereschi Ernandes
2009-01-01
Full Text Available A levana é um exopolissacarídeo sintetizado por vários microrganismos durante a fermentação de um meio de cultura à base de sacarose, extrato de levedura e sais minerais. Este biopolímero pode ser usado tanto na área de alimentos, como estabilizante, espessantee fixador de cor e sabor, quanto na farmacêutica, como hipocolesterolêmico e anticarcinogênico. O artigo teve como objetivo analisar a influência da temperatura e do pH, em relação a diferentes tempos de fermentação, no desenvolvimento celular e na produção de levana, por fermentação submersa. O microrganismo utilizado foi Zymomonas mobilis CCT 4494, incubado num meio de cultura quimicamente definido, acrescido de 200,0 g L-1 de sacarose. Amostras do caldo de fermentação foram recolhidas a cada 24h, durante o período de 96h, para posteriormente serem submetidas aos métodos analíticos:pH, biomassa, teores de açúcares redutores e de açúcares redutores totais e da formação de levana. Observou-se que os rendimentos obtidos de biomassa e do biopolímero sintetizado, em 24h, foram superiores àqueles obtidos em 48, 72 e 96h de fermentação.Levan is an exopolysaccharide synthesized by several microorganisms during fermentation of a culture medium containing sucrose, yeastextract and minerals. This biopolymer has applications in the food segment as stabilizers, thickeners, as carriers for flavor and fragrances, as well as in the pharmaceutical segment as ahypocholesterolemic agent and for exhibiting antitumor activity. This work aimed to analyze the kinetic parameters for levan production. The microorganism used was Zymomonas mobilis CCT 4494, incubated in a synthetic medium containing 200.0 g L-1 of sucrose, in a rotary shaker at 200 rpm and 30°C. Samples were taken every 24h, during aperiod of 96h, in order to determine variations of pH, biomass, reducing sugar, total reducing sugar and levan formation. It was observed that yields of biomass and synthesized
Chemical, physical, and theoretical kinetics of an ultrafast folding protein.
Kubelka, Jan; Henry, Eric R; Cellmer, Troy; Hofrichter, James; Eaton, William A
2008-12-01
An extensive set of equilibrium and kinetic data is presented and analyzed for an ultrafast folding protein--the villin subdomain. The equilibrium data consist of the excess heat capacity, tryptophan fluorescence quantum yield, and natural circular-dichroism spectrum as a function of temperature, and the kinetic data consist of time courses of the quantum yield from nanosecond-laser temperature-jump experiments. The data are well fit with three kinds of models--a three-state chemical-kinetics model, a physical-kinetics model, and an Ising-like theoretical model that considers 10(5) possible conformations (microstates). In both the physical-kinetics and theoretical models, folding is described as diffusion on a one-dimensional free-energy surface. In the physical-kinetics model the reaction coordinate is unspecified, whereas in the theoretical model, order parameters, either the fraction of native contacts or the number of native residues, are used as reaction coordinates. The validity of these two reaction coordinates is demonstrated from calculation of the splitting probability from the rate matrix of the master equation for all 10(5) microstates. The analysis of the data on site-directed mutants using the chemical-kinetics model provides information on the structure of the transition-state ensemble; the physical-kinetics model allows an estimate of the height of the free-energy barrier separating the folded and unfolded states; and the theoretical model provides a detailed picture of the free-energy surface and a residue-by-residue description of the evolution of the folded structure, yet contains many fewer adjustable parameters than either the chemical- or physical-kinetics models.
FY2014 Parameters for Helions and Gold Ions in Booster, AGS, and RHIC
Energy Technology Data Exchange (ETDEWEB)
Gardner, C. J. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.
2014-08-15
The nominal parameters for helions (helion is the bound state of two protons and one neutron, the nucleus of a helium-3 atom) and gold ions in Booster, AGS, and RHIC are given for the FY2014 running period. The parameters are found using various formulas to derive mass, helion anomalous g-factor, kinetic parameters, RF parameters, ring parameters, etc..
Kinetics and thermodynamics of fast particles in solids
Kashlev, Yurii
2012-01-01
Kinetics and Thermodynamics of Fast Particles in Solids examines the kinetics and non-equilibrium statistical thermodynamics of fast charged particles moving in crystals in different modes. It follows a line of research very different from traditional ways of constructing a theory of radiation effects, which gives a purely mechanistic interpretation of particle motion. In contrast, this book takes into account the thermodynamic forces due to separation of the thermodynamic parameters of the subsystem of particles (""hot"" atoms) on the parameters of the thermostat (electrons and lattice), in a
Diffusion kinetics of metal recovery biosorption processes
International Nuclear Information System (INIS)
The uptake of heavy metals and radionuclides by alginate beads was studied to determine kinetic and mass transport parameters of this biosorption process. The kinetics of cadmium and uranyl ion uptake by calcium alginate were assessed using a mathematical expression derived for evaluation of hyperbolic type biosorption isotherms. Removal efficiencies were evaluated under varying solution conditions of initial solute concentration, pH, temperature and the presence of selected cations. The maximum rate of sorption was found to be 241.7 and 978.8 mg/L/min for uranium and cadmium, respectively. Based upon Fick's Second Law, a quantitative description of the mass transfer mechanism for these biosorption processes was developed, and diffusion coefficients determined for the sorption of UO2+2 and Cd2+ by calcium alginate gel beads
Kinetic Analysis of Mica Tape Curing Process
Directory of Open Access Journals (Sweden)
Radek Polansky
2008-01-01
Full Text Available Curing program of thermoset insulating materials and its responsible setting has the key importance for assurance of high quality and reliability of electrical devices. It is possible to determine parameters of this program (temperature and time of curing by several ways in practise. There is mostly focused on methods based on kinetic analysis. The result comparison of selected methods of kinetic analysis and residual enthalpy measurement is the main aim of the paper. Two insulating tapes were chosen for the purpose of this study. These tapes correspond in their composition (glass fabric, mica and epoxy binder, but they differ in curing agent type. Simultaneous thermal analysis (STA was used during the measurements. Monitored results demonstrate the advantages and disadvantages of particular methods.
Reaction kinetics of bond rotations in graphene
Skowron, Stephen T.
2016-04-12
The formation and healing processes of the fundamental topological defect in graphitic materials, the Stone-Wales (SW) defect, are brought into a chemical context by considering the rotation of a carbon-carbon bond as chemical reaction. We investigate the rates and mechanisms of these SW transformations in graphene at the atomic scale using transmission electron microscopy. We develop a statistical atomic kinetics formalism, using direct observations obtained under different conditions to determine key kinetic parameters of the reactions. Based on the obtained statistics we quantify thermally and irradiation induced routes, identifying a thermal process of healing with an activation energy consistent with predicted adatom catalysed mechanisms. We discover exceptionally high rates for irradiation induced SW healing, incompatible with the previously assumed mechanism of direct knock-on damage and indicating the presence of an efficient nonadiabatic coupling healing mechanism involving beam induced electronic excitations of the SW defect.
The measurement of mechanical parameters in machines
Rayevskii, N P
1965-01-01
The Measurement of Mechanical Parameters in Machines is a translation from the Russian version and presents methods used in the U.S.S.R. for measuring mechanical properties. This book discusses different indicators and accepted methods of measuring separate parameters. This text also explains the metrological characteristics of mechanical parameters that can be determined by applying the equations of motion, usually represented as equations of kinetic energy or as a Lagrangian equation. The electrical methods of measuring machines and recording results are noted, and the kinds of methods pref
Reaction Kinetics of Nanostructured Silicon Carbide
Wallis, Kendra; Zerda, T. W.
2006-10-01
Nanostructured silicon carbide (SiC) is of interest particularly for use in nanocomposites that demonstrate high hardness as well as for use in semiconductor applications. Reaction kinetics studies of solid-solid reactions are relatively recent and present a method of determining the reaction mechanism and activation energy by measuring reaction rates. We have used induction heating to heat quickly, thus reducing the error in reaction time measurements. Data will be presented for reactions using silicon nanopowder (melting point of silicon. Using the well-known Avrami-Erofeev model, a two-parameter chi- square fit of the data provided a rate constant (k) and parameter (n), related to the reaction mechanism, for each temperature. From these data, an activation energy of 138 kJ/mol was calculated. In addition, the parameter n suggests the reaction mechanism, which will also be discussed. Experiments are continuing at higher temperatures to consider the liquid- solid reaction as well.
Directory of Open Access Journals (Sweden)
Edenio Detmann
2001-02-01
of a non-linear model in the process parameter estimation of the solid transit kinetics of bovine at pasture, using different sequences of fecal sampling. Five F1 Limousin X Nellore steers, fistulated in esophagus and rumen on Brachiaria decumbens grazing and concentrate supplemented during the rainy season period were used. The experiment was developed in three experimental periods; in a randomized completely blocks design. Chromium mordant, produced from extrusa samples, was used as marker. The double exponential time-dependent model was adjusted to the curves of fecal excretion of marker, and the following sample sequences were used: SEQ 1 - 22 samples (complete sample sequence; SEQ 2 and SEQ 3 - 17 samples (reduction of collection points in the ascendant and descendent phases of the curve, respectively; and SEQ 4 and SEQ 5 - 13 and 10 fecal samples (reduction of the number of samples in the whole profile of the curve. The reduced sequences were produced starting from the omission of specific points of the complete sample sequence (SEQ 1. The comparison among the estimates of the kinetic parameters and fecal excretion; the descriptive analysis of the necessary number of iterations to the convergence of the model and of the determination coefficient; and the evaluation of lack of fitness showed no differences among the sequences. However, the residual analysis pointed improvements in the graphic behavior and runs of signal profile of the residues with the reduction of the number of collections in SEQ 4 and SEQ 5. In function of small efficiency loss, evaluated from the residual variance, observed in SEQ 5, the employment of 13 fecal collections (SEQ 4 for evaluation of the fecal excretion curve of the marker in similar studies was recommended.
Size dependence of adsorption kinetics of nano-MgO: a theoretical and experimental study
Energy Technology Data Exchange (ETDEWEB)
Wang, Shuting; Wen, Yanzhen; Cui, Zixiang; Xue, Yongqiang, E-mail: xyqlw@126.com [Taiyuan University of Technology (China)
2016-01-15
Nanoparticles present tremendous differences in adsorption kinetics compared with corresponding bulk particles which have great influences on the applications of nanoparticles. A size-dependent adsorption kinetic theory was proposed, the relations between adsorption kinetic parameters, respectively, and particle size of nano-adsorbent were derived theoretically, and the influence mechanism of particle size on the adsorption kinetic parameters was discussed. In experiment, nanoscale magnesium oxide (nano-MgO) with different diameters between 11.5 and 41.4 nm with narrow size distribution and low agglomeration were prepared, and the kinetic parameters of adsorption of benzene on nano-MgO in aqueous solution were obtained. Then the influence regularities of the particle size on the adsorption kinetic parameters were obtained. The experimental results are consistent with the nano-adsorption kinetic theory. With particle size decreasing, the adsorption rate constant increases; the adsorption activation energy and the adsorption pre-exponential factor decrease. Furthermore, the logarithm of adsorption rate constant, the adsorption activation energy, and the logarithm of adsorption pre-exponential factor are linearly related to the reciprocal of particle diameter, respectively. The mechanism of particle size influence on the kinetic parameters is that the activation energy is influenced by the molar surface enthalpy of nano-adsorbent, the pre-exponential factor by the molar surface entropy, and the rate constant by both the molar surface enthalpy and the molar surface entropy.
Stochastic Electrochemical Kinetics
Beruski, O
2016-01-01
A model enabling the extension of the Stochastic Simulation Algorithm to electrochemical systems is proposed. The physical justifications and constraints for the derivation of a chemical master equation are provided and discussed. The electrochemical driving forces are included in the mathematical framework, and equations are provided for the associated electric responses. The implementation for potentiostatic and galvanostatic systems is presented, with results pointing out the stochastic nature of the algorithm. The electric responses presented are in line with the expected results from the theory, providing a new tool for the modeling of electrochemical kinetics.
Kinetics of catalytic cracking with short contact times
Energy Technology Data Exchange (ETDEWEB)
Hagelberg, P.; Eilos, I. [Neste Engineering Oy, P.O. Box 310, FIN-06101 Porvoo (Finland); Hiltunen, J.; Lipiaeinen, K.; Niemi, V.M. [Fortum Oil and Gas Oy, P.O. Box 310, FIN-06101 Porvoo (Finland); Aittamaa, J.; Krause, A.O.I. [Department of Chemical Technology, Helsinki University of Technology, P.O. Box 6100, FIN-02015 HUT (Finland)
2001-01-10
A novel isothermal pulse reactor was used to study the kinetics of gas oil cracking on a FCC equilibrium catalyst with short contact times. The feed was a lighter gas oil than typically used in FCC-units. Experiments were carried out by varying the catalyst-to-oil ratio, volume of the oil pulse, temperature and residence time. After each hydrocarbon pulse the catalyst was regenerated by introducing several oxygen/nitrogen pulses through the catalyst bed. The amounts of carbon monoxide and carbon dioxide formed were measured and the amount of coke on the catalyst was calculated. The reproducibility of the experiments was excellent. A kinetic model that included five lumps, namely, gas oil, gasoline, liquefied petroleum gas (LPG), dry gas and coke with five cracking reactions was developed first and its kinetic parameters were determined from the experimental results. The data could be best described by the model wherein the rate of cracking of gas oil to gasoline and to LPG were both approximated as second order dependency and the rate of cracking of gas oil to dry gas and to coke as first order dependency on the gas oil concentration. The five-lump model was further enlarged by dividing the gasoline fraction into paraffins, olefins, naphthenes and aromatics resulting in an eight-lump model with eight reactions. In addition, changes in the activity of the catalyst during one experiment was accounted for by using two exponential activity functions, one for catalytic cracking reactions and the other for coke formation. The formation of dry gas was considered to be the product of a thermal reaction only. The kinetic parameters of the Arrhenius' law and the deactivation parameters were estimated by a non-linear regression program. In the five-lump model 12 parameters and in the eight-lump model 18 parameters (rate coefficients, activation energies and deactivation parameters) were obtained. The kinetic parameters of the Arrhenius' law were statistically
Extending ITC to Kinetics with kinITC.
Dumas, Philippe; Ennifar, Eric; Da Veiga, Cyrielle; Bec, Guillaume; Palau, William; Di Primo, Carmelo; Piñeiro, Angel; Sabin, Juan; Muñoz, Eva; Rial, Javier
2016-01-01
Isothermal titration calorimetry (ITC) has long been used for kinetic studies in chemistry, but this remained confined to enzymatic studies in the biological field. In fact, the biological community has long had the tendency of ignoring the kinetic possibilities of ITC considering it solely as a thermodynamic technique, whereas surface plasmon resonance is seen as the kinetic technique par excellence. However, the primary signal recorded by ITC is a heat power which is directly related to the kinetics of the reaction. Here, it is shown how this kinetic signal can be recovered by using kinITC, the kinetic extension of ITC. The theoretical basis of kinITC is detailed for the most common situation of a second-order reaction A+B Ω C characterized by kinetic parameters kon, koff. A simplified kinITC-ETC method based upon the determination of an "Equilibration Time Curve" (ETC) is presented. The ETC is obtained by automatic determination of the "effective end" of each injection. The method is illustrated with experimental results with a comparison to Surface Plasmon Resonance (SPR) data. kon values were obtained in a wide range, from 10(3) to 0.5×10(6) M(-1) s(-1). All procedures were implemented in the program AFFINImeter (https://www.affinimeter.com/).
Extending ITC to Kinetics with kinITC.
Dumas, Philippe; Ennifar, Eric; Da Veiga, Cyrielle; Bec, Guillaume; Palau, William; Di Primo, Carmelo; Piñeiro, Angel; Sabin, Juan; Muñoz, Eva; Rial, Javier
2016-01-01
Isothermal titration calorimetry (ITC) has long been used for kinetic studies in chemistry, but this remained confined to enzymatic studies in the biological field. In fact, the biological community has long had the tendency of ignoring the kinetic possibilities of ITC considering it solely as a thermodynamic technique, whereas surface plasmon resonance is seen as the kinetic technique par excellence. However, the primary signal recorded by ITC is a heat power which is directly related to the kinetics of the reaction. Here, it is shown how this kinetic signal can be recovered by using kinITC, the kinetic extension of ITC. The theoretical basis of kinITC is detailed for the most common situation of a second-order reaction A+B Ω C characterized by kinetic parameters kon, koff. A simplified kinITC-ETC method based upon the determination of an "Equilibration Time Curve" (ETC) is presented. The ETC is obtained by automatic determination of the "effective end" of each injection. The method is illustrated with experimental results with a comparison to Surface Plasmon Resonance (SPR) data. kon values were obtained in a wide range, from 10(3) to 0.5×10(6) M(-1) s(-1). All procedures were implemented in the program AFFINImeter (https://www.affinimeter.com/). PMID:26794354
Institute of Scientific and Technical Information of China (English)
ZHANG Zhiying; WU Shizhen; DU Yinghua; CAO Zhenlin
1991-01-01
The non-isothermal crystallization kinetics of poly(ethylene terephthalate) (PET) modified by poly (ethlene glycol) (PEG) were determined by DSC. The dual linear regression method was used to evaluate the relationship between the reciprocal of t1/2 ( the half life of crystallization ) and the appropriate temperature variable. The parameters such as the activation energy (Ed) for transport,the equilibrium melting temperature (T0m),the nucleation parameter (ψ),the maximum crystallization temperature (Tc, max ) , and the kinetic crystallizability (G) for the copolyesters were obtained. The influence of the PEG content in PET chains on the parameters characterizing crystallization kinetics and crystallization thermodynamics was discussed.
Kinetics of pressure induced structural phase transitions—A review
Indian Academy of Sciences (India)
N V Chandra Shekar; K Govinda Rajan
2001-02-01
The current status of experimental as well as theoretical advances in the understanding of kinetics of structural phase transitions is reviewed. A brief outline of the classification of phase transitions and classical ideas in the theory of kinetics of phase change is presented first. High pressure experimental techniques developed for studying the kinetics of structural transitions are reviewed and the salient features of each technique is brought out. The experimental technique using the diamond anvil cell (DAC) and image processing gets special mention as it promises to impart a new direction to this field. The usefulness of kinetic parameters in understanding the mechanism of a phase transition is examined. Typical examples from the literature are provided to give a flavour for these kind of studies. In conclusion, several open questions are raised which could pave way for future work in this area.
[The kinetic theory of the aging of living systems].
Viktorov, A A; Kholodnov, V A
2013-01-01
Kinetic theory of aging of living systems is proposed. Theory is based on the concept of continuous adaptation of biological system (BS) from its birth to changing conditions of environment (ENV). Adaptation rate as rate of risk of destructions accumulation in BS is studied as competition between two simultaneous processes: BS destruction and recombination of damages defined by kinetics of autocatalytic chemical reactions. Kinetic theory assumes critical phenomenon: failure of adaptation when intensity of ENV impact becomes higher some critical level. Choice of parameters of kinetic mathematical model and accounting dependence of ENV impact intensity on time allows describing the following results observed in medical practice: child mortality, depletion of adaptive reserves, slowing the rate of aging of long-living persons, damped harmonic oscillations of biological response at pulse toxic intervention and to estimate risks of disease and death. PMID:24003729
Electron transfer kinetics at polarized nanoscopic liquid/liquid interfaces.
Cai, Chenxin; Mirkin, Michael V
2006-01-11
Rapid kinetics of electron transfer (ET) reactions across the interface between water and 1,2-dichloroethane were measured by steady-state voltammetry at nanopipet electrodes (50- to 400-nm orifice radius). The origins of previously reported imperfect voltammetric responses of ET reactions at micropipets were investigated. Several new experimental systems were explored, and two of them yielded high-quality voltammograms suitable for kinetic experiments. The determined standard rate constants were compared to those measured previously at polarized and nonpolarized liquid/liquid interfaces. The effect of the interfacial dimensions on the magnitude of the apparent ET rate constant is discussed. A new approach to ET kinetic measurements based on the use of the scanning electrochemical microscope with a nanopipet tip and a metallic substrate has been developed and employed to check the validity of determined kinetic parameters. PMID:16390144
Kinetic Modelling of Macroscopic Properties Changes during Crosslinked Polybutadiene Oxidation
Audouin, Ludmila; Coquillat, Marie; Colin, Xavier; Verdu, Jacques; Nevière, Robert
2008-08-01
The thermal oxidation of additive free hydroxyl-terminated polybutadiene (HTPB) isocyanate crosslinked rubber bulk samples has been studied at 80, 100 and 120 °C in air. The oxidation kinetics has been monitored by gravimetry and thickness distribution of oxidation products was determined by FTIR mapping. Changes of elastic shear modulus G' during oxidation were followed during oxidation at the same temperatures. The kinetic model established previously for HTPB has been adapted for bulk sample oxidation using previously determined set of kinetic parameters. Oxygen diffusion control of oxidation has been introduced into the model. The mass changes kinetic curves and oxidation products profiles were simulated and adequate fit was obtained. Using the rubber elasticity theory the elastic modulus changes were simulated taking into account the elastically active chains concentration changes due to chain scission and crosslinking reactions. The reasonable fit of G' as a function of oxidation time experimental curves was obtained.
Thermal Characterization and Decomposition Kinetics of Free Anthraquinones from Rhubarb
Institute of Scientific and Technical Information of China (English)
Li Ming ZHANG; Xia LI; Yu Jie DAI
2006-01-01
The thermal behaviour of aloe-emodin, chrysophanol and physcion and their kinetics have been investigated under non-isothermal conditions by means of differential thermal analysis (DTA) and thermogravimetry (TG). The thermal characteristics have been determined using the DTA and TG-DTG curves. The non-isothermal kinetic data were analyzed by means of the Achar method and the Madhusudanan-Krishnan-Ninan (MKN) method. The possible reaction mechanisms have been investigated by comparing the kinetic parameters. The kinetic equation for aloe-emodin, chrysophanol and physcion can be expressed as dα/dt=Aexp(-E/RT)1/3(1-α)[-In(1-α)]-2. The activation energy E (kJ mol-1) of the three free anthraquinones are 78.09, 89.54,and 107.5 and their lnA/s-1 are 22.98, 36.85 and 43.60, respectively.
Non-Isothermal Desolvation Kinetics of Erythromycin A Acetone Solvate
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
The desolvation of erythromycin acetone solvate was investigated under non-isothermal conditions by a thermogravimetric analyzer. This paper emphasized the kinetic analysis of non-isothermal TG-DTA data by Achar method and Coats-Redfern method to fit various solid-state reaction models, and to achieve kinetic parameters of desolvation. The mechanism of thermal desolvation was evaluated using the kinetic compensation effect. The results show that kinetics of desolvation of erythromycin acetone solvate was compatible with the mechanism of a two-dimensional diffusion controlled and was best expressed by Valensi equation. Corresponding to the integral method and the differential method, the activation energy of desolvation of erythromycin acetone solvate was estimated to be 51.26-57.11 kJ/mol, and the pre-exponential factor was 8.077 × 106 s-1-4.326 × 107 s-1,respectively.
Moment equations for chromatography based on Langmuir type reaction kinetics.
Miyabe, Kanji
2014-08-22
Moment equations were derived for chromatography, in which the reaction kinetics between solute molecules and functional ligands on the stationary phase was represented by the Langmuir type rate equation. A set of basic equations of the general rate model of chromatography representing the mass balance, mass transfer rate, and reaction kinetics in the column were analytically solved in the Laplace domain. The moment equations for the first absolute moment and the second central moment in the real time domain were derived from the analytical solution in the Laplace domain. The moment equations were used for predicting the chromatographic behavior under hypothetical HPLC conditions. The influence of the parameters relating to the adsorption equilibrium and to the reaction kinetics on the chromatographic behavior was quantitatively evaluated. It is expected that the moment equations are effective for a detailed analysis of the influence of the mass transfer rates and of the Langmuir type reaction kinetics on the column efficiency.
Energy Technology Data Exchange (ETDEWEB)
Seery, D.J.; Freihaut, J.D.; Proscia, W.M. (United Technologies Research Center, East Hartford, CT (USA)); Howard, J.B.; Peters, W.; Hsu, J.; Hajaligol, M.; Sarofim, A. (Massachusetts Inst. of Tech., Cambridge, MA (USA)); Jenkins, R.; Mallin, J.; Espindola-Merin, B. (Pennsylvania State Univ., University Park, PA (USA)); Essenhigh, R.; Misra, M.K. (Ohio State Univ., Columbus, OH (USA))
1989-07-01
This report contains results of a coordinated, multi-laboratory investigation of coal devolatilization. Data is reported pertaining to the devolatilization for bituminous coals over three orders of magnitude in apparent heating rate (100 to 100,000 + {degree}C/sec), over two orders of magnitude in particle size (20 to 700 microns), final particle temperatures from 400 to 1600{degree}C, heat transfer modes ranging from convection to radiative, ambient pressure ranging from near vacuum to one atmosphere pressure. The heat transfer characteristics of the reactors are reported in detail. It is assumed the experimental results are to form the basis of a devolatilization data base. Empirical rate expressions are developed for each phase of devolatilization which, when coupled to an awareness of the heat transfer rate potential of a particular devolatilization reactor, indicate the kinetics emphasized by a particular system reactor plus coal sample. The analysis indicates the particular phase of devolatilization that will be emphasized by a particular reactor type and, thereby, the kinetic expressions appropriate to that devolatilization system. Engineering rate expressions are developed from the empirical rate expressions in the context of a fundamental understanding of coal devolatilization developed in the course of the investigation. 164 refs., 223 figs., 44 tabs.
Theory of Square-wave Voltammetry of Kinetically Controlled Two-step Electrode Reactions
Lovrić, Milivoj; Komorsky-Lovrić, Šebojka
2012-01-01
An influence of electron transfer kinetics on square-wave voltammograms of two-step electrode reaction is investigated theoretically. A phenomenon of “kinetic burden” of potential inversion is described for the case of equal kinetic parameters. A linear relationship between standard rate constant and the difference between standard potentials of the second and the first charge transfers is demonstrated for the reactions with thermodynamically unstable intermediate. (doi: 10.5562/cca2126)
Parameter estimation in tree graph metabolic networks.
Astola, Laura; Stigter, Hans; Gomez Roldan, Maria Victoria; van Eeuwijk, Fred; Hall, Robert D; Groenenboom, Marian; Molenaar, Jaap J
2016-01-01
We study the glycosylation processes that convert initially toxic substrates to nutritionally valuable metabolites in the flavonoid biosynthesis pathway of tomato (Solanum lycopersicum) seedlings. To estimate the reaction rates we use ordinary differential equations (ODEs) to model the enzyme kinetics. A popular choice is to use a system of linear ODEs with constant kinetic rates or to use Michaelis-Menten kinetics. In reality, the catalytic rates, which are affected among other factors by kinetic constants and enzyme concentrations, are changing in time and with the approaches just mentioned, this phenomenon cannot be described. Another problem is that, in general these kinetic coefficients are not always identifiable. A third problem is that, it is not precisely known which enzymes are catalyzing the observed glycosylation processes. With several hundred potential gene candidates, experimental validation using purified target proteins is expensive and time consuming. We aim at reducing this task via mathematical modeling to allow for the pre-selection of most potential gene candidates. In this article we discuss a fast and relatively simple approach to estimate time varying kinetic rates, with three favorable properties: firstly, it allows for identifiable estimation of time dependent parameters in networks with a tree-like structure. Secondly, it is relatively fast compared to usually applied methods that estimate the model derivatives together with the network parameters. Thirdly, by combining the metabolite concentration data with a corresponding microarray data, it can help in detecting the genes related to the enzymatic processes. By comparing the estimated time dynamics of the catalytic rates with time series gene expression data we may assess potential candidate genes behind enzymatic reactions. As an example, we show how to apply this method to select prominent glycosyltransferase genes in tomato seedlings. PMID:27688960
Chemical kinetics of gas reactions
Kondrat'Ev, V N
2013-01-01
Chemical Kinetics of Gas Reactions explores the advances in gas kinetics and thermal, photochemical, electrical discharge, and radiation chemical reactions. This book is composed of 10 chapters, and begins with the presentation of general kinetic rules for simple and complex chemical reactions. The next chapters deal with the experimental methods for evaluating chemical reaction mechanisms and some theories of elementary chemical processes. These topics are followed by discussions on certain class of chemical reactions, including unimolecular, bimolecular, and termolecular reactions. The rema
Chemical Kinetics on Extrasolar Planets
Moses, Julianne I
2013-01-01
Chemical kinetics plays an important role in controlling the atmospheric composition of all planetary atmospheres, including those of extrasolar planets. For the hottest exoplanets, the composition can closely follow thermochemical-equilibrium predictions, at least in the visible and infrared photosphere at dayside (eclipse) conditions. However, for atmospheric temperatures < ~2000 K, and in the uppermost atmosphere at any temperature, chemical kinetics matters. The two key mechanisms by which kinetic processes drive an exoplanet atmosphere out of equilibrium are photochemistry and transport-induced quenching. We review these disequilibrium processes in detail, discuss observational consequences, and examine some of the current evidence for kinetic processes on extrasolar planets.
Adsorption analysis equilibria and kinetics
Do, Duong D
1998-01-01
This book covers topics of equilibria and kinetics of adsorption in porous media. Fundamental equilibria and kinetics are dealt with for homogeneous as well as heterogeneous particles. Five chapters of the book deal with equilibria and eight chapters deal with kinetics. Single component as well as multicomponent systems are discussed. In kinetics analysis, we deal with the various mass transport processes and their interactions inside a porous particle. Conventional approaches as well as the new approach using Maxwell-Stefan equations are presented. Various methods to measure diffusivity, such
KINETICS OF SLURRY PHASE FISCHER-TROPSCH SYNTHESIS
Energy Technology Data Exchange (ETDEWEB)
Dragomir B. Bukur; Gilbert F. Froment; Tomasz Olewski
2006-09-29
This report covers the fourth year of a research project conducted under the University Coal Research Program. The overall objective of this project is to develop a comprehensive kinetic model for slurry-phase Fischer-Tropsch synthesis (FTS) employing iron-based catalysts. This model will be validated with experimental data obtained in a stirred-tank slurry reactor (STSR) over a wide range of process conditions. The model will be able to predict molar flow rates and concentrations of all reactants and major product species (water, carbon dioxide, linear 1- and 2-olefins, and linear paraffins) as a function of reaction conditions in the STSR. During the fourth year of the project, an analysis of experimental data collected during the second year of this project was performed. Kinetic parameters were estimated utilizing product distributions from 27 mass balances. During the reporting period two kinetic models were employed: a comprehensive kinetic model of Dr. Li and co-workers (Yang et al., 2003) and a hydrocarbon selectivity model of Van der Laan and Beenackers (1998, 1999) The kinetic model of Yang et al. (2003) has 24 parameters (20 parameters for hydrocarbon formation, and 4 parameters for the water-gas-shift (WGS) reaction). Kinetic parameters for the WGS reaction and FTS synthesis were estimated first separately, and then simultaneously. The estimation of these kinetic parameters employed the Levenberg-Marquardt (LM) method and the trust-region reflective Newton large-scale (LS) method. A genetic algorithm (GA) was incorporated into estimation of parameters for FTS reaction to provide initial estimates of model parameters. All reaction rate constants and activation energies were found to be positive, but at the 95% confidence level the intervals were large. Agreement between predicted and experimental reaction rates has been fair to good. Light hydrocarbons are predicted fairly accurately, whereas the model underpredicts values of higher molecular weight
Amyloplast Sedimentation Kinetics in Corn Roots
Leopold, A. C.; Sack, F.
1985-01-01
Knowledge of the parameters of amyloplast sedimentation is crucial for an evaluation of proposed mechanisms of root graviperception. Early estimates of the rate of root amyloplast sedimentation were as low as 1.2 micron/min which may be too slow for many amyloplasts to reach the vicinity of the new lower wall within the presentation time. On this basis, Haberlandt's classical statolith hypothesis involving amyloplast stimulation of a sensitive surface near the new lower wall was questioned. The aim was to determine the kinetics of amyloplast sedimentation with reference to the presentation time in living and fixed corn rootcap cells as compared with coleoptiles of the same variety.
Modeling Biodegradation Kinetics on Benzene and Toluene and Their Mixture
Directory of Open Access Journals (Sweden)
Aparecido N. Módenes
2007-10-01
Full Text Available The objective of this work was to model the biodegradation kinetics of toxic compounds toluene and benzene as pure substrates and in a mixture. As a control, Monod and Andrews models were used. To predict substrates interactions, more sophisticated models of inhibition and competition, and SKIP (sum kinetics interactions parameters model were applied. The models evaluation was performed based on the experimental data from Pseudomonas putida F1 activities published in the literature. In parameter identification procedure, the global method of particle swarm optimization (PSO was applied. The simulation results show that the better description of the biodegradation process of pure toxic substrate can be achieved by Andrews' model. The biodegradation process of a mixture of toxic substrates is modeled the best when modified competitive inhibition and SKIP models are used. The developed software can be used as a toolbox of a kinetics model catalogue of industrial wastewater treatment for process design and optimization.
Electrochemical kinetics of gold dissolving in alkaline thiourea solution
Institute of Scientific and Technical Information of China (English)
CHAI Li-yuan; WANG Yun-yan
2006-01-01
Kinetic parameters of the electrode reactions were measured by investigating steady-state current-potential behaviors. The results show that the apparent transfer coefficient of anodic process is 0.058 2, diffusion coefficient of thiourea gold complex is 6.04 × 10-6 cm2/s,anodic reaction order of thiourea is 2. 018 3, and anodic reaction order of OH- is 0. 016 6. The theoretical kinetics equation of gold dissolving in alkaline thiourea solution is deduced,which indicates that anodic reaction order of thiourea is 2, and anodic reaction order of OH- is 0. The theoretical values of the kinetic parameters are consistent with experimental values very well. The correctness of the mechanism is further demonstrated using apparent transfer coefficient according to the electrochemical dynamic equation of multi-electron reaction.
Enzyme kinetics in drug metabolism: fundamentals and applications.
Nagar, Swati; Argikar, Upendra A; Tweedie, Donald J
2014-01-01
Enzymes are protein catalysts that lower the energy barrier for a reaction and speed the rate of a chemical change. The kinetics of reactions catalyzed by enzymes, as well as several mechanisms underlying the kinetics, have been comprehensively studied and written in textbooks (1, 2). The importance of quantitative evaluation of enzymatic processes has been recognized in many fields of study, including biochemistry, molecular biology, and pharmaceutical sciences to name a few. In pharmaceutical sciences, the applications of enzyme kinetics range from hit finding efforts for new chemical entities on a pharmacological target to concentration effect relationships to large-scale biosynthesis. The study of the science of drug metabolism has two principal concepts-rate and extent. While understanding disposition pathways and identification of metabolites provides an insight into the extent of metabolism, kinetics of depletion of substrates (endogenous or exogenous) and formation of metabolites deals with the rate of metabolism. The current textbook specifically focuses on kinetics of drug-metabolizing enzymes, detailing specific enzyme classes, and discusses kinetics as they apply to drug transporters. This textbook also outlines additional factors that contribute to the kinetics of reactions catalyzed by these proteins such as variability in isoforms (pharmacogenomics) and experimental factors including key concepts such as alterations of substrate concentrations due to binding. Applications of these approaches in predicting kinetic parameters and alternative approaches for enzymes (systems biology) and transporters are also discussed. The final section focuses on real-life examples (case studies) to try and exemplify the applications of enzyme kinetic principles. This chapter provides a brief overview outlining some key concepts within each of the sections and the chapters within this textbook.
Institute of Scientific and Technical Information of China (English)
LI Minhui; WANG Xiaogong; LIU Deshan; ZHOU Qixiang
1991-01-01
The phase transition kinetics of thermotropic liquid crystalline aromatic-aliphatic regular copolyester:(X) were studied by DSC. By means of Kissinger's method the kinetic equation and parameters including activation energy, rate order and preexponential factor for phase transition from nematic to isotropic were obtained. The activation energy from crystal to nematic was also presented.
Energy Technology Data Exchange (ETDEWEB)
Fondeur, F
2006-03-08
The Dubinin-Astashov (DA) isotherm parameters for U, Pu, Sr and Np have been updated to include additional data obtained since the original derivation. The DA isotherms were modified to include a kinetic function derived by Rahn to describe sorbate loading from the beginning of sorption up to steady state. The final functions describe both kinetic and thermodynamic sorption.
Measurement of Enzyme Kinetics by Use of a Blood Glucometer: Hydrolysis of Sucrose and Lactose
Heinzerling, Peter; Schrader, Frank; Schanze, Sascha
2012-01-01
An alternative analytical method for measuring the kinetic parameters of the enzymes invertase and lactase is described. Invertase hydrolyzes sucrose to glucose and fructose and lactase hydrolyzes lactose to glucose and galactose. In most enzyme kinetics studies, photometric methods or test strips are used to quantify the derivates of the…
Hot Deformation Kinetics of Magnesium Alloy AZ31
Institute of Scientific and Technical Information of China (English)
WANG Lingyun; HUANG Guangjie; FAN Yonge; LU Zhiwen; PAN Fusheng
2006-01-01
The flow stress at elevated temperatures for magnesium alloy AZ31 was studied using isothermal compression testing. The effect of deformation parameters on the flow stress was studied as well. The kinetics of elevated temperature deformation was expressed by means of some empirical rate equations. The activation parameter has been calculated. A mechanism for the dynamic softening of AZ31 alloy in a hot deformation experiment was identified to be the dynamic recrystallization.
Thermodynamic and kinetic characterization of a zirconium chelate
International Nuclear Information System (INIS)
The chemical preparation, composition and characteristics of a zirconium complex with hemateine was studied. Hematein is the common name of an organic compound containing hydroxy-aromatic and hydroxyquinonic groups. The stability constant of this complex was determined spectrophotometrically. Other thermodynamic parameters for the complex formation were also determined; the effect of temperature on these parameters was examined. Reaction kinetics was investigated, as well as the charge of reacting species for the formation of the activated complex. (C.L.B.)
Kinetic inductance magnetometer.
Luomahaara, Juho; Vesterinen, Visa; Grönberg, Leif; Hassel, Juha
2014-09-10
Sensing ultra-low magnetic fields has various applications in the fields of science, medicine and industry. There is a growing need for a sensor that can be operated in ambient environments where magnetic shielding is limited or magnetic field manipulation is involved. To this end, here we demonstrate a new magnetometer with high sensitivity and wide dynamic range. The device is based on the current nonlinearity of superconducting material stemming from kinetic inductance. A further benefit of our approach is of extreme simplicity: the device is fabricated from a single layer of niobium nitride. Moreover, radio frequency multiplexing techniques can be applied, enabling the simultaneous readout of multiple sensors, for example, in biomagnetic measurements requiring data from large sensor arrays.
Ruan, Zhongyuan; Iñiguez, Gerardo; Karsai, Márton; Kertész, János
2015-11-01
Diffusion of information, behavioral patterns or innovations follows diverse pathways depending on a number of conditions, including the structure of the underlying social network, the sensitivity to peer pressure and the influence of media. Here we study analytically and by simulations a general model that incorporates threshold mechanism capturing sensitivity to peer pressure, the effect of "immune" nodes who never adopt, and a perpetual flow of external information. While any constant, nonzero rate of dynamically introduced spontaneous adopters leads to global spreading, the kinetics by which the asymptotic state is approached shows rich behavior. In particular, we find that, as a function of the immune node density, there is a transition from fast to slow spreading governed by entirely different mechanisms. This transition happens below the percolation threshold of network fragmentation, and has its origin in the competition between cascading behavior induced by adopters and blocking due to immune nodes. This change is accompanied by a percolation transition of the induced clusters.
Ruan, Zhongyuan; Karsai, Marton; Kertesz, Janos
2015-01-01
Diffusion of information, behavioural patterns or innovations follows diverse pathways depending on a number of conditions, including the structure of the underlying social network, the sensitivity to peer pressure and the influence of media. Here we study analytically and by simulations a general model that incorporates threshold mechanism capturing sensitivity to peer pressure, the effect of `immune' nodes who never adopt, and a perpetual flow of external information. While any constant, non-zero rate of dynamically-introduced innovators leads to global spreading, the kinetics by which the asymptotic state is approached show rich behaviour. In particular we find that, as a function of the density of immune nodes, there is a transition from fast to slow spreading governed by entirely different mechanisms. This transition happens below the percolation threshold of fragmentation of the network, and has its origin in the competition between cascading behaviour induced by innovators and blocking of adoption due ...
Kinetic Studies of the Solvolysis of Two Organic Halides
Duncan, J. A.; Pasto, D. J.
1975-01-01
Describes an undergraduate organic chemistry laboratory experiment which utilizes the solvolysis of organic halides to demonstrate first and second order reaction kinetics. The experiment also investigates the effect of a change of solvent polarity on reaction rate, common-ion and noncommon-ion salt effects, and the activation parameters of a…
Extraction kinetics and properties of proanthocyanidins from pomegranate peel
With an objective of developing a safe and efficient method to extract proanthocyanidins products from pomegranate peel for use in nutraceuticals or as food additives, the effects of extraction parameters on the production efficiency, product properties, and extraction kinetics were systematically s...
Kinetic Analysis of the Thermal Processing of Silica and Organosilica
Kappert, Emiel J.; Bouwmeester, H.J.M.; Benes, N.E.; Nijmeijer, A.
2014-01-01
The incorporation of an organic group into sol–gel-derived silica causes significant changes in the structure and properties of these materials. Therefore, the thermal treatment of organosilica materials may require a different approach. In the present paper, kinetic parameters (activation energy, p
Ensemble Kinetic Modeling of Metabolic Networks from Dynamic Metabolic Profiles
Directory of Open Access Journals (Sweden)
Gengjie Jia
2012-11-01
Full Text Available Kinetic modeling of metabolic pathways has important applications in metabolic engineering, but significant challenges still remain. The difficulties faced vary from finding best-fit parameters in a highly multidimensional search space to incomplete parameter identifiability. To meet some of these challenges, an ensemble modeling method is developed for characterizing a subset of kinetic parameters that give statistically equivalent goodness-of-fit to time series concentration data. The method is based on the incremental identification approach, where the parameter estimation is done in a step-wise manner. Numerical efficacy is achieved by reducing the dimensionality of parameter space and using efficient random parameter exploration algorithms. The shift toward using model ensembles, instead of the traditional “best-fit” models, is necessary to directly account for model uncertainty during the application of such models. The performance of the ensemble modeling approach has been demonstrated in the modeling of a generic branched pathway and the trehalose pathway in Saccharomyces cerevisiae using generalized mass action (GMA kinetics.
Dimensional enhancement of kinetic energies
DEFF Research Database (Denmark)
Schleich, W.P.; Dahl, Jens Peder
2002-01-01
Simple thermodynamics considers kinetic energy to be an extensive variable which is proportional to the number N of particles. We present a quantum state of N noninteracting particles for which the kinetic energy increases quadratically with N. This enhancement effect is tied to the quantum centr...... centrifugal potential whose strength is quadratic in the number of dimensions of configuration space....
Dimensional enhancement of kinetic energies
Schleich, W. P.; Dahl, Jens Peder
2002-01-01
Simple thermodynamics considers kinetic energy to be an extensive variable which is proportional to the number, N, of particles. We present a quantum state of N non-interacting particles for which the kinetic energy increases quadratically with N. This enhancement effect is tied to the quantum centrifugal potential whose strength is quadratic in the number of dimensions of configuration space.
Kinetic competition during glass formation
Energy Technology Data Exchange (ETDEWEB)
Perepezko, J.H., E-mail: perepezk@engr.wisc.edu [University of Wisconsin-Madison, Department of Materials Science and Engineering, 1509 University Ave., Madison, WI 53706 (United States); Santhaweesuk, C.; Wang, J.Q. [University of Wisconsin-Madison, Department of Materials Science and Engineering, 1509 University Ave., Madison, WI 53706 (United States); Imhoff, S.D. [Los Alamos National Laboratory, Materials Science and Technology Div., Los Alamos, NM 87545 (United States)
2014-12-05
Highlights: • The kinetics of glass formation has been elucidated in an Fe and Au-base alloy. • A critical cooling rate range should be considered for glass formation. • Wedge casting, calorimetry and upquenching data are used to model TTT curves. - Abstract: For vitrification of an alloy melt during cooling there is a kinetic competition with the nucleation and growth of metastable and stable crystalline phases. Many of the measures of glass forming ability (GFA) attempt to capture some of the features of the kinetic competition, but the GFA metrics are static measures and the kinetic processes are dynamic in nature. In fact, the critical cooling rate for glass formation should be viewed in terms of a critical cooling rate range to acknowledge the stochastic nature of crystal nucleation behavior. Direct measurements of the critical cooling rate range confirm this behavior and also provide useful input for kinetics analysis. Usually kinetics analyses are based upon crystallization behavior that is measured either isothermally or upon heating to temperatures near the crystallization onset, T{sub x} and the results are extrapolated to much higher temperatures. This practice is based upon a number of assumptions about transport behavior in the undercooled liquid. With rapid up-quenching of amorphous samples, the high temperature crystallization behavior can be measured and used to refine the kinetics analysis and provide useful insight on the kinetic competition and glass forming ability.
Kinetic competition during glass formation
International Nuclear Information System (INIS)
Highlights: • The kinetics of glass formation has been elucidated in an Fe and Au-base alloy. • A critical cooling rate range should be considered for glass formation. • Wedge casting, calorimetry and upquenching data are used to model TTT curves. - Abstract: For vitrification of an alloy melt during cooling there is a kinetic competition with the nucleation and growth of metastable and stable crystalline phases. Many of the measures of glass forming ability (GFA) attempt to capture some of the features of the kinetic competition, but the GFA metrics are static measures and the kinetic processes are dynamic in nature. In fact, the critical cooling rate for glass formation should be viewed in terms of a critical cooling rate range to acknowledge the stochastic nature of crystal nucleation behavior. Direct measurements of the critical cooling rate range confirm this behavior and also provide useful input for kinetics analysis. Usually kinetics analyses are based upon crystallization behavior that is measured either isothermally or upon heating to temperatures near the crystallization onset, Tx and the results are extrapolated to much higher temperatures. This practice is based upon a number of assumptions about transport behavior in the undercooled liquid. With rapid up-quenching of amorphous samples, the high temperature crystallization behavior can be measured and used to refine the kinetics analysis and provide useful insight on the kinetic competition and glass forming ability
Kinetics model development of cocoa bean fermentation
Kresnowati, M. T. A. P.; Gunawan, Agus Yodi; Muliyadini, Winny
2015-12-01
Although Indonesia is one of the biggest cocoa beans producers in the world, Indonesian cocoa beans are oftenly of low quality and thereby frequently priced low in the world market. In order to improve the quality, adequate post-harvest cocoa processing techniques are required. Fermentation is the vital stage in series of cocoa beans post harvest processing which could improve the quality of cocoa beans, in particular taste, aroma, and colours. During the fermentation process, combination of microbes grow producing metabolites that serve as the precursors for cocoa beans flavour. Microbial composition and thereby their activities will affect the fermentation performance and influence the properties of cocoa beans. The correlation could be reviewed using a kinetic model that includes unstructured microbial growth, substrate utilization and metabolic product formation. The developed kinetic model could be further used to design cocoa bean fermentation process to meet the expected quality. Further the development of kinetic model of cocoa bean fermentation also serve as a good case study of mixed culture solid state fermentation, that has rarely been studied. This paper presents the development of a kinetic model for solid-state cocoa beans fermentation using an empirical approach. Series of lab scale cocoa bean fermentations, either natural fermentations without starter addition or fermentations with mixed yeast and lactic acid bacteria starter addition, were used for model parameters estimation. The results showed that cocoa beans fermentation can be modelled mathematically and the best model included substrate utilization, microbial growth, metabolites production and its transport. Although the developed model still can not explain the dynamics in microbial population, this model can sufficiently explained the observed changes in sugar concentration as well as metabolic products in the cocoa bean pulp.
DEFF Research Database (Denmark)
Villadsen, John
2015-01-01
his chapter predicts the specific rates of reaction by means of a mathematical expression, the kinetics of the reaction. This expression can be derived through a mechanistic interpretation of an enzymatically catalyzed reaction, but it is essentially of empirical nature for cell reactions....... The models can be used in mass balances for design of processes under process conditions not yet studied experimentally. The value of the predictive kinetic model depends on the quality of the experimental data on which the model is based, and well-founded kinetic models for enzyme reactions have...... a considerable predictive power. This is also true for cell reaction models, when the model is used in its proper context. The chapter first discusses the kinetics for enzymatically catalyzed reactions (“enzyme reactions”). The kinetics can be derived from a mechanistic model. Then, the chapter derives empirical...
Application of Discrete Lumped Kinetic Modeling on Vacuum Gas Oil Hydrocracking
Institute of Scientific and Technical Information of China (English)
Han Longnian; Fang Xiangchen; Peng Chong; Zhao Tao
2013-01-01
The kinetic model of vacuum gas oil (VGO) hydrocracking based on discrete lumped approach was investigated, and some improvement was put forward at the same time in this article. A parallel reaction scheme to describe the conver-sion of VGO into products (gases, gasoline, and diesel) proposed by Orochko was used. The different experimental data were analyzed statistically and then the product distribution and kinetic parameters were simulated by available data. Fur-thermore, the kinetic parameters were correlated based on the feed property, reaction temperature, and catalyst activity. An optimization code in Matlab 2011b was written to ifne-tune these parameters. The model had a favorable ability to predict the product distribution and there was a good agreement between the model predictions and experiment data. Hence, the ki-netic parameters indeed had something to do with feed properties, reaction temperature and catalyst activity.
Local operators in kinetic wealth distribution
Andrecut, M.
2016-05-01
The statistical mechanics approach to wealth distribution is based on the conservative kinetic multi-agent model for money exchange, where the local interaction rule between the agents is analogous to the elastic particle scattering process. Here, we discuss the role of a class of conservative local operators, and we show that, depending on the values of their parameters, they can be used to generate all the relevant distributions. We also show numerically that in order to generate the power-law tail, an heterogeneous risk aversion model is required. By changing the parameters of these operators, one can also fine tune the resulting distributions in order to provide support for the emergence of a more egalitarian wealth distribution.
Institute of Scientific and Technical Information of China (English)
邹立强; 刘伟; 刘军平; 刘成梅
2012-01-01
以蘑菇多酚氧化酶（PPO）为原料，研究不同浓度的柠檬酸处理对PPO相对酶活性、动力学参数（米氏常数K～最大反应速率Vmax）、褐变测量参数的影响。结果表明：随着柠檬酸浓度的增加，PPO的相对酶活性逐渐降低，当柠檬酸浓度达到70mmol／L时，PPO的相对酶活性仅为原酶活性的1％；随着底物邻苯二酚浓度的增加，柠檬酸处理的PPO反应速率逐渐提高，当邻苯二酚浓度为15mmol／L时，反应速率达到最大值。随着柠檬酸浓度的增大，PPO的Vmax基本不变，而Vmax逐渐降低，经Lineweaver．Burk作图得出0、20、40mmol／L柠檬酸处理PPO的Vmax分别为578．4、437．8、111．6U／min。表明柠檬酸是PPO与底物邻苯二酚反应的非竞争抑制剂。对褐变测量参数影响表明，随着处理的柠檬酸浓度的增大，L＋（亮度）、a＊（红值）变化较小，而西。（黄值）急剧下降，40、70mmol／L柠檬酸处理后扫。分别降为原酶活性的57．5％和13．7％；Hue、Chroma、褐变指数（BI）也明显降低；这与PPO的相对酶活性和Vmax变化一致，表明相对酶活性、Vmax与b＊、Hue、Chroma、BI有直接的相关性。%The effect of different concentrations of citric acid treatment on the relative activity, kinetic parameters （gm and Vmax） and browning parameters （Hue, Chroma and BI） of polyphenol oxidase （PPO） from mushroom. The results showed that the relative activity of PPO decreased gradually with increasing citric acid concentration and was only 1% of its original activity at 70 mmol/L. In the presence of citric acid, the reaction rate of PPO showed a gradual increase with increasing concentration of catechol, the substrate and reached its maximum level at a substrate concentration of 15 mmol/L. However, the Km remained basically unchanged despite an increase in citric acid concentration, while the Vmax gradually decreased. Lineweaver-Burk plots
Kinetics of niobium carbide precipitation in ferrite
International Nuclear Information System (INIS)
The aim of this study is to develop a NbC precipitation modelling in ferrite. This theoretical study is motivated by the fact it considers a ternary system and focus on the concurrence of two different diffusion mechanisms. An experimental study with TEP, SANS and Vickers micro-hardening measurements allows a description of the NbC precipitation kinetics. The mean radius of the precipitates is characterized by TEM observations. To focus on the nucleation stage, we use the Tomographic Atom Probe that analyses, at an atomistic scale, the position of the solute atoms in the matrix. A first model based on the classical nucleation theory and the diffusion-limited growth describes the precipitation of spherical precipitates. To solve the set of equations, we use a numerical algorithm that furnishes an evaluation of the precipitated fraction, the mean radius and the whole size distribution of the particles. The parameters that are the interface energy, the solubility product and the diffusion coefficients are fitted with the data available in the literature and our experimental results. It allows a satisfactory agreement as regards to the simplicity of the model. Monte Carlo simulations are used to describe the evolution of a ternary alloy Fe-Nb-C on a cubic centred rigid lattice with vacancy and interstitial mechanisms. This is realized with an atomistic description of the atoms jumps and their related frequencies. The model parameters are fitted with phase diagrams and diffusion coefficients. For the sake of simplicity, we consider that the precipitation of NbC is totally coherent and we neglect any elastic strain effect. We can observe different kinetic paths: for low supersaturations, we find an expected precipitation of NbC but for higher supersaturations, the very fast diffusivity of carbon atoms conducts to the nucleation of iron carbide particles. We establish that the occurrence of this second phenomenon depends on the vacancy arrival kinetics and can be related
Kinetics of the reversible reaction of struvite crystallisation.
Crutchik, D; Garrido, J M
2016-07-01
The crystallisation of struvite could be a sustainable and economical alternative for recovering phosphorus from wastewater streams with high phosphate concentrations. Knowledge regarding the kinetics and thermodynamics that are involved in the crystallisation of struvite is the key to determine the optimal conditions for obtaining an efficient process. This study was conducted in a continuous stirred batch reactor. Different sets of experiments were performed in which struvite was either dissolved (undersaturated) or precipitated (oversaturated). These experiments were conducted at different temperatures (25, 30 and 35 °C) and pH values (8.2, 8.5 and 8.8) to determine the kinetics of struvite precipitation and dissolution. Struvite crystallisation was modelled as a reversible reaction. The kinetic rate parameters of struvite precipitation were 1.03·10(-4), 1.25·10(-4) and 1.54·10(-4) mol m(-2) min(-1) at 25, 30 and 35 °C, respectively. Similar kinetic rate parameters were determined for struvite dissolution. Struvite heterogeneous crystallisation can be represented by a first-order kinetic model that fitted well the experimental data. PMID:27085317
Free radical kinetics of irradiated durum wheat
Korkmaz, M.; Polat, M.
2000-04-01
In the present work, a detailed ESR investigation of characteristic features and kinetic behaviors at three different temperatures of free radicals produced in a species of durum wheat cultivated in Turkey and irradiated at doses of up to 5 kGy by a γ source, is reported. Unirradiated wheat samples exhibit a weak, single-line ESR signal originating from a radical of unknown structure called radical III in this work. Irradiation produces two more radicals identified as hydroxyalkyl (I) and aldehydalkyl (II) radicals beside radical III. The radicals (I, II and III) follow complicated kinetics. Species I and II initially decay very fast after the irradiation followed by slower decay. Radical half-life times depend on whether they were induced in the crystalline or amorphous fractions of the wheat starch. Activation energy values of the radicals were found to follow the order Ea(III)> Ea(II)> Ea(I). ESR parameters of the radical species were determined by simulating experimental spectra recorded following the irradiation. Room temperature dose-response curves and variations of different spectral parameters between 120 and 390 K were also studied.
Optimal Bayesian Experimental Design for Combustion Kinetics
Huan, Xun
2011-01-04
Experimental diagnostics play an essential role in the development and refinement of chemical kinetic models, whether for the combustion of common complex hydrocarbons or of emerging alternative fuels. Questions of experimental design—e.g., which variables or species to interrogate, at what resolution and under what conditions—are extremely important in this context, particularly when experimental resources are limited. This paper attempts to answer such questions in a rigorous and systematic way. We propose a Bayesian framework for optimal experimental design with nonlinear simulation-based models. While the framework is broadly applicable, we use it to infer rate parameters in a combustion system with detailed kinetics. The framework introduces a utility function that reflects the expected information gain from a particular experiment. Straightforward evaluation (and maximization) of this utility function requires Monte Carlo sampling, which is infeasible with computationally intensive models. Instead, we construct a polynomial surrogate for the dependence of experimental observables on model parameters and design conditions, with the help of dimension-adaptive sparse quadrature. Results demonstrate the efficiency and accuracy of the surrogate, as well as the considerable effectiveness of the experimental design framework in choosing informative experimental conditions.
Kuzovkov, V. N.; Popov, A. I.; Kotomin, E. A.; Moskina, A. M.; Vasilchenko, E.; Lushchik, A.
2016-07-01
We analyzed carefully the experimental kinetics of the low-temperature diffusion-controlled F, H center recombination in a series of irradiated alkali halides and extracted the migration energies and pre-exponential parameters for the hole H centers. The migration energy for the complementary electronic F centers in NaCl was obtained from the colloid formation kinetics observed above room temperature. The obtained parameters were compared with data available from the literature.
Osmotic dehydration of red cabbage in sugar beet molasses: Mass transfer kinetics
Filipčev Bojana V.; Lević Ljubinko B.; Koprivica Gordana B.; Mišljenović Nevena M.; Kuljanin Tatjana A.
2009-01-01
The paper describes a study of osmotic dehydration of red cabbage in sugar beet molasses of different concentrations (40, 60 and 80%) at 50°C and under atmospheric pressure. The best results were obtained at the sugar beet molasses of 80% as an osmotic medium. The most important kinetic parameters of the process were determined: water loss, solid uptake, weight reduction, normalized solid content and normalized moisture content. The kinetic parameters were determined after 1, 3 and 5 hours. M...
Kinetics of dehydrogenation of MgH{sub 2} and AlH{sub 3}
Energy Technology Data Exchange (ETDEWEB)
Gabis, I., E-mail: igor.gabis@gmail.com [Physics Department of St. Petersburg State University, St. Petersburg (Russian Federation); Dobrotvorskiy, M.; Evard, E.; Voyt, A. [Physics Department of St. Petersburg State University, St. Petersburg (Russian Federation)
2011-09-15
Kinetics of dehydrogenation was studied using isothermal barometry, TDS and SEM methods. Two stages of the decomposition process are considered: incubation preceding the formation of metallic nuclei on the surface of the particle and hydrogen evolution via these metallic regions serving as facilitating channels for desorption. Duration of the first stage depends on the temperature of the sample. Relationship with material's electronic band structure is discussed. Kinetics of the second stage is controlled by two reactions: desorption of the hydrogen molecules from the surface and shift of the metal-hydride interphase in the bulk. Physical mechanisms of decomposition with detailed reaction kinetics are proposed and kinetic parameters are evaluated.
Similarities and Differences Between Freundlich Kinetic Equation and Two—Constant Equation
Institute of Scientific and Technical Information of China (English)
ZHANGZENGQIANG; ZHANGYIPING
1999-01-01
A mathematical expression of Freundlich kinetic equation,lnS=A'+B'lnt,is presented,and the physical meanings of its parameters are indicated.Although the Freundlich kinetic equation and the two-constant equation are the same in the form,the derivation of the Freundlich kinetic equation is precise,while the derivation of the two-constant equation has some contradictions and is unreasonable,And it is suggested that the Freundlich kinetic equation should have prority over the two-constant equation to be used.
Kinetic Model of Hypophosphite Oxidation on a Nickel Electrode in D2O Solution
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Kinetic model of hypophosphite oxidation on a nickel electrode was studied in D2Osolution in order to reach a better understanding of the oxidation mechanism. In the model the electrooxidation of hypophosphite undergo a H abstraction of hypophosphite from the P-H bond to form the phosphorus-centered radical PHO2-, which subsequently is electrochemically reacted with water to form the final product, phosphite. The kinetic equations were derived, and the kinetic parameters were obtained from a comparison of experimental results and the kinetic equations. The process of hypophosphite electrooxidation could be well simulated by this model
Thermoluminescence glow curve involving any extent of retrapping or any order of kinetics
Indian Academy of Sciences (India)
Jai Prakash
2013-09-01
Adirovitch set of equations has been modified to explain the mechanisms involved in thermoluminescence (TL) glow curve. A simple model is proposed which explains the occurrence of TL glow curve involving any extent of retrapping or any order of kinetics. It has been observed that the extents of recombination and simultaneous rewrapping decide the order of kinetics involved. TL decay parameters, order of kinetics and initial concentration of trapped electrons per unit volume are evaluated easily and conveniently. It has been observed that retrapping increases with increasing order of kinetics.
Kwon, Yoo Jung; Park, Soo Jin; Jefferson, John; Kim, Kyoung
2013-06-01
[Purpose] This study investigated the effect of open and closed kinetic chain exercise on the dynamic balance ability of healthy young adults. [Subjects] Thirty-three healthy adults participated in this study. [Methods] Subjects were randomly assigned to either an open kinetic chain exercise group (n=17) or a closed kinetic chain exercise group (n=16). Both the open kinetic chain and closed kinetic chain exercise groups performed 3 sets of exercises 3 times per week for 6 weeks. Dynamic balance was measured at the beginning and end of the 6-week training period, including anterior-posterior, medial-lateral, and total displacement of the center of pressure. [Results] Both exercise groups showed improvement in balance parameters but the improvement was only statistically significant in the closed kinetic chain group. [Conclusion] Closed kinetic chain exercise appears to be more effective at improving of dynamic balance ability than open kinetic chain exercise within a 6-week training period. PMID:24259825
Kinetics of the thermal degradation of Erica arborea by DSC: Hybrid kinetic method
Cancellieri, Dominique; Rossi, Jean Louis; 10.1016/j.tca.2005.07.013
2008-01-01
The scope of this work was the determination of kinetic parameters of the thermal oxidative degradation of a Mediterranean scrub using a hybrid method developed at the laboratory. DSC and TGA were used in this study under air sweeping to record oxidative reactions. Two dominating and overlapped exothermic peaks were recorded in DSC and individualized using an experimental and numerical separation. This first stage allowed obtaining the enthalpy variation of each exothermic phenomenon. In a second time, a model free method was applied on each isolated curve to determine the apparent activation energies. A reactional kinetic scheme was proposed for the global exotherm composed of two independent and consecutive reactions. In fine mean values of enthalpy variation and apparent activation energy previously determined were injected in a model fitting method to obtain the reaction order and the preexponential factor of each oxidative reaction. We plan to use these data in a sub-model to be integrated in a wildland ...
Kinetic properties of cyanase.
Anderson, P M; Little, R M
1986-04-01
Cyanase is an inducible enzyme in Escherichia coli that catalyzes the hydrolysis of cyanate. Bicarbonate is required for activity, perhaps as a substrate, and the initial product of the reaction is carbamate, which spontaneously breaks down to ammonia and bicarbonate [Anderson, P. M. (1980) Biochemistry 19, 2882]. The purpose of this study was to characterize the kinetic properties of cyanase. Initial velocity studies showed that both cyanate and bicarbonate act as competitive substrate inhibitors. A number of monovalent anions act as inhibitors. Azide and acetate appear to act as competitive inhibitors with respect to cyanate and bicarbonate, respectively. Chloride, bromide, nitrate, nitrite, and formate also inhibit, apparently as the result of binding at either substrate site. Malonate and several other dicarboxylic dianions at very low concentrations display "slow-binding", reversible inhibition which can be prevented by saturating concentrations of either substrate. The results are consistent with a rapid equilibrium random mechanism in which bicarbonate acts as a substrate, bicarbonate and cyanate bind at adjacent anion-binding sites, and both substrates can bind at the other substrate anion binding site to give a dead-end complex.
International Nuclear Information System (INIS)
Highlights: ► We have studied the coupling among gas, plasma and surface in the divertor region. ► A one-dimensional PIC-DSMC model has been developed. ► Profiles of density and temperature of all the species involved have been provided. ► MAR processes are effective in a region smaller than 1.5 mm from the divertor plate. ► For regions more distant, the ionization of atoms, produced by MAR, starts to occur. - Abstract: The coupled dynamics and kinetics between gas and plasma in the divertor region is studied by means of a one-dimensional Particle in Cell-Direct Simulation Monte Carlo (PIC-DSMC) model. In particular, the collision-induced vibrational excitation/relaxation of H2 molecules and particle–surface interaction (vibrational relaxation and recombinative desorption) have been considered in detail to estimate the importance of plasma volumetric recombination by molecular assisted reaction (MAR). Spatially resolved results show that MAR processes are effective very close to the divertor plate in a region smaller than 1.5 mm from the divertor plate. For regions more distant the ionization of atoms, produced by MAR, starts to make molecular assisted recombination an ineffective reaction.
Marklof, Jens
2010-03-01
One of the central challenges in kinetic theory is the derivation of macroscopic evolution equations--describing, for example, the dynamics of an electron gas--from the underlying fundamental microscopic laws of classical or quantum mechanics. An iconic mathematical model in this research area is the Lorentz gas, which describes an ensemble of non-interacting point particles in an infinite array of spherical scatterers. In the case of a disordered scatterer configuration, the classical results by Gallavotti, Spohn and Boldrighini-Bunimovich-Sinai show that the time evolution of a macroscopic particle cloud is governed, in the limit of small scatterer density (Boltzmann-Grad limit), by the linear Boltzmann equation. In this lecture I will discuss the recent discovery that for a periodic configuration of scatterers the linear Boltzmann equation fails, and the random flight process that emerges in the Boltzmann-Grad limit is substantially more complicated. The key ingredient in the description of the limiting stochastic process is the renormalization dynamics on the space of lattices, a powerful technique that has recently been successfully applied also to other open problems in mathematical physics, including KAM theory and quantum chaos. This lecture is based on joint work with Andreas Strömbergsson, Uppsala.
Kinetics of methane oxidation in selected mineral soils
Walkiewicz, A.; Bulak, P.; Brzeziñska, M.; Włodarczyk, T.; Polakowski, C.
2012-10-01
The kinetic parameters of methane oxidation in three mineral soils were measured under laboratory conditions. Incubationswere preceded by a 24-day preincubationwith 10%vol. of methane. All soils showed potential to the consumption of added methane. None of the soils, however, consumed atmospheric CH4. Methane oxidation followed the Michaelis-Menten kinetics, with relatively low values of parameters for Eutric Cambisol, while high values for Haplic Podzol, and especially for Mollic Gleysol which showed the highest methanotrophic activity and much lower affinity to methane. The high values of parameters for methane oxidation are typical for organic soils and mineral soils from landfill cover. The possibility of the involvement of nitrifying microorganisms, which inhabit the ammonia-fertilized agricultural soils should be verified.
Thermal analysis and combustion kinetic of heavy oils
Energy Technology Data Exchange (ETDEWEB)
Santos, R.G. [Centre for Petroleum Studies, State University of Campinas(Brazil); Vargas, J.A.V.; Trevisan, O.V. [Department of Petroleum Engineering, Faculty of Mechanical Engineering, State University of Campinas (Brazil)
2011-07-01
In the oilfield sector, a thermal method named in-situ combustion (ISC) is used as an enhanced recovery method. ISC consists of the injection of gas into the reservoir, a combustion front is created producing heat which reduces the oil viscosity. For this method to be successful, understanding of the thermal and kinetic parameters involved is required; the aim of this paper is to evaluate those parameters for different crude oils. Experiments were conducted using accelerating rate calorimetry on Brazilian heavy oil samples under a heat-wait-seek-mode. Results showed that accelerating rate calorimetry is efficient in resolving the three main regions of reaction of the oil and that between 200 degree C and 300 degree C oxygen addition reactions are dominant while bond scission reactions dominate from 350 degree C. This study demonstrated that accelerating rate calorimetry is an efficient method to determine thermal and kinetic parameters of oxidation reaction of heavy oil.
Intrinsic kinetics and devolatilization of wheat straw during torrefaction
DEFF Research Database (Denmark)
Shang, Lei; Ahrenfeldt, Jesper; Holm, Jens Kai;
2013-01-01
Torrefaction is a mild thermal treatment (200–300 °C) in an inert atmosphere, which is known to increase the energy density of biomass by evaporating water and a proportion of volatiles. In this work, the degradation kinetics and devolatilization of wheat straw was studied in a thermogravimetric...... analyzer by coupling with a mass spectrometer. The kinetic parameters obtained by applying a two-step reaction in series model and taking initial dynamic heating period into account can accurately describe the experimental results with different heating programs. Activation energies and pre......-exponential parameters obtained for the two steps are: 71.0 and 76.6 kJ mol−1, 3.48 × 104 and 4.34 × 103 s−1, respectively. The model and these parameters were also proven to be able to predict the residual mass of wheat straw in a batch scale torrefaction reactor. By analyzing the gas products in situ, the formation...
Droplet Growth Kinetics in Various Environments
Raatikainen, T. E.; Lathem, T. L.; Moore, R.; Lin, J. J.; Cerully, K. M.; Padro, L.; Lance, S.; Cozic, J.; Anderson, B. E.; Nenes, A.
2012-12-01
The largest uncertainties in the effects of atmospherics aerosols on the global radiation budget are related to their indirect effects on cloud properties (IPCC, the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, 2007). Cloud formation is a kinetic process where the resulting cloud properties depend on aerosol properties and meteorological parameters such as updraft velocity (e.g. McFiggans et al., Atmos. Chem. Phys., 6, 2593-2649, 2006). Droplet growth rates are limited by the water vapor diffusion, but additional kinetic limitations, e.g., due to organic surface films, slow solute dissociation or highly viscous or glassy aerosol states have been hypothesized. Significant additional kinetic limitations can lead to increased cloud droplet number concentration, thus the effect is similar to those of increased aerosol number concentration or changes in vertical velocity (e.g. Nenes et al., Geophys. Res. Lett., 29, 1848, 2002). There are a few studies where slow droplet growth has been observed (e.g. Ruehl et al., Geophys. Res. Lett., 36, L15814, 2009), however, little is currently known about their global occurrence and magnitude. Cloud micro-physics models often describe kinetic limitations by an effective water vapor uptake coefficient or similar parameter. Typically, determining aerosol water vapor uptake coefficients requires experimental observations of droplet growth which are interpreted by a numerical droplet growth model where the uptake coefficient is an adjustable parameter (e.g. Kolb et al., Atmos. Chem. Phys., 10, 10561-10605, 2010). Such methods have not been practical for high time-resolution or long term field measurements, until a model was recently developed for analyzing Droplet Measurement Technologies (DMT) cloud condensation nuclei (CCN) counter data (Raatikainen et al., Atmos. Chem. Phys., 12, 4227-4243, 2012). Model verification experiments showed that the calibration aerosol droplet size can be predicted accurately
Kinetic Study on Pyrolysis of Oil Palm Frond
Soon, V. S. Y.; Chin, B. L. F.; Lim, A. C. R.
2016-03-01
The pyrolysis of oil palm frond is studied using thermogravimetric analysis (TGA) equipment. The present study investigates the thermal degradation behaviour and determination of the kinetic parameters such as the activation energy (EA ) and pre-exponential factor (A) values of oil palm frond under pyrolysis condition. The kinetic data is produced based on first order rate of reaction. In this study, the experiments are conducted at different heating rates of 10, 20, 30, 40 and 50 K/min in the temperature range of 323-1173 K under non-isothermal condition. Argon gas is used as an inert gas to remove any entrapment of gases in the TGA equipment.
Gas-Kinetic BGK Scheme for Three Dimensional Magnetohydrodynamics
Institute of Scientific and Technical Information of China (English)
Huazhong
2010-01-01
The gas-kinetic theory based flux splitting method has been successfully proposed for solving one- and two-dimensional ideal magnetohydrodynamics by Xu et al.[J. Comput. Phys., 1999; 2000], respectively. This paper extends the kinetic method to solve three-dimensional ideal magnetohydrodynamics equations, where an adaptive parameter η is used to control the numerical dissipation in the flux splitting method.Several numerical examples are given to demonstrate that the proposed method can achieve high numerical accuracy and resolve strong discontinuous waves in three dimensional ideal MHD problems.
Effects of Substrate Permeation on Kinetics of Phenol Biodegradation
Institute of Scientific and Technical Information of China (English)
冀秀玲; 张金利; 李Wei; 韩振亭; 王一平
2003-01-01
Based on the theory of substrate permeation through the cytoplasmic membrane,and considering the effect of initial concentration of substrate,a new kinetic model of phenol degradation process was proposed,Comparing with the widely used Haldane model,which is greatly dependent on the initial phenol concentration,our model can be used to simulate the phenol degradation process in a wide range of initial phenol concentration by using only one set of model parameters ,Therefore,this new kinetic model has much more potential applications to industrial design and operation.
Kinetics of desorption of iodine from borehole waters
International Nuclear Information System (INIS)
Kinetics of mass transfer during iodine desorption by air from water-salt systems and borehole waters of different composition has been studied. With an aid of laboratory installation with film column and sprinkled walls the region of the process procedure in a wide range of phases, concentrations (aqueous iodine solution, sodium chloride solution) and temperatures is determined. Calculation and experimental values of kinetic parameters are obtained. It follows from the data analysis that the process of iodine desorption is complicated by reversible reaction of complexing, its rate being higher than the rate of mass transfer
Kinetics of Conversion of Methane with Electric Field Enhanced Plasma
Institute of Scientific and Technical Information of China (English)
王保伟; 许根慧; 孙洪伟
2004-01-01
Methane conversion was studied with electric field enhanced plasma (EFEP) technique at the atmosphere pressure and low temperature ranging from 323 K to 373 K. The conversion of methane is up to 60%--80%. The kinetics of methane conversion was studied using microreactor. The reaction model of power function type was obtained as: r = 90.99exp (-26980/RT)CA0.226(mol·m-3·s-1). The global kinetics parameters were calculated by the variable simple-pure shape method. The calculating results are in good agreement with experimental data.
Spectroscopy and kinetics of combustion gases at high temperatures
Energy Technology Data Exchange (ETDEWEB)
Hanson, R.K.; Bowman, C.T. [Stanford Univ., CA (United States)
1993-12-01
This program involves two complementary activities: (1) development and application of cw ring dye laser absorption methods for sensitive detection of radical species and measurement of fundamental spectroscopic parameters at high temperatures; and (2) shock tube studies of reaction kinetics relevant to combustion. Species currently under investigation in the spectroscopic portion of the research include NO and CH{sub 3}; this has necessitated the continued operated at wavelengths in the range 210-230 nm. Shock tube studies of reaction kinetics currently are focussed on reactions involving CH{sub 3} radicals.
FY2014 Parameters for Gold Ions in Booster, AGS, and RHIC
Energy Technology Data Exchange (ETDEWEB)
Gardner, C. J. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.
2014-07-30
The nominal parameters for gold ions in Booster, AGS, and RHIC are given for the FY2014 running period. The parameters are worked out using various formulas to derive mass, kinetic parameters, RF parameters, ring parameters, etc.. The ''standard setup'', ''medium-energy'', and ''low-energy'' parameters are summarized in separate sections.
Directory of Open Access Journals (Sweden)
J. Y. Tang
2015-09-01
Full Text Available The Michaelis–Menten kinetics and the reverse Michaelis–Menten kinetics are two popular mathematical formulations used in many land biogeochemical models to describe how microbes and plants would respond to changes in substrate abundance. However, the criteria of when to use which of the two are often ambiguous. Here I show that these two kinetics are special approximations to the Equilibrium Chemistry Approximation kinetics, which is the first order approximation to the quadratic kinetics that solves the equation of enzyme-substrate complex exactly for a single enzyme single substrate biogeochemical reaction with the law of mass action and the assumption of quasi-steady-state for the enzyme-substrate complex and that the product genesis from enzyme-substrate complex is much slower than the equilibration between enzyme-substrate complexes, substrates and enzymes. In particular, I showed that the derivation of the Michaelis–Menten kinetics does not consider the mass balance constraint of the substrate, and the reverse Michaelis–Menten kinetics does not consider the mass balance constraint of the enzyme, whereas both of these constraints are taken into account in the Equilibrium Chemistry Approximation kinetics. By benchmarking against predictions from the quadratic kinetics for a wide range of substrate and enzyme concentrations, the Michaelis–Menten kinetics was found to persistently under-predict the normalized sensitivity ∂ ln v / ∂ ln k2+ of the reaction velocity v with respect to the maximum product genesis rate k2+, persistently over-predict the normalized sensitivity ∂ ln v / ∂ ln k1+ of v with respect to the intrinsic substrate affinity k1+, persistently over-predict the normalized sensitivity ∂ ln v / ∂ ln [ E ]T of v with respect the total enzyme concentration [ E ]T and persistently under-predict the normalized sensitivity ∂ ln v / ∂ ln [ S ]T of v with respect to the total substrate concentration [ S ]T
Indian Academy of Sciences (India)
Jai Prakash
2013-01-01
Ionic thermocurrent (ITC) spectrum is much similar to a thermoluminescence (TL) glow curve involving monomolecular kinetics. It has already been reported that different orders of kinetics are involved in TL processes, which depend specifically on the extent of recombination and simultaneous retrapping. It is found that the involvement of different orders of kinetics in ITC spectrum depends on the experimental conditions of polarization and rate of rapid cooling. Consequently, order of kinetics involved in the ITC spectrum does not represent any specific feature of the system under investigation. An equation is developed which explains the occurrence of ITC spectrum involving any order of kinetics. Dielectric relaxation parameters, order of kinetics and approximate number of dipoles per unit volume are evaluated conveniently and easily following the proposed model.
Kinetics of the biodegradation of green table olive wastewaters by aerobic and anaerobic treatments
Energy Technology Data Exchange (ETDEWEB)
Beltran, J. [Departamento de Ingenieria Quimica y Energetica, Universidad de Extremadura, 06071 Badajoz (Spain)], E-mail: jbelther@unex.es; Gonzalez, T.; Garcia, J. [Departamento de Ingenieria Quimica y Energetica, Universidad de Extremadura, 06071 Badajoz (Spain)
2008-06-15
The biodegradation of the organic pollutant matter present in green table olive wastewater (GTOW) is studied in batch reactors by an aerobic biodegradation and by an anaerobic digestion. In the aerobic biodegradation, the evolution of the substrate (in terms of chemical and biochemical oxygen demand), biomass, and total polyphenolic compounds present in the wastewater are followed during the process, and a kinetic study is performed using Contois' model, which when applied to the experimental results provides the kinetic parameter of this model, resulting in a modified Contois' equation (q = 3.3S/(0.31S{sub 0}X + X), gCOD/gVSS d{sup -1}). Other kinetic parameters were determined: the cellular yield coefficient (Y{sub X/S} = 5.7 x 10{sup -2} gVSS/gCOD) and the kinetic constant of cellular death phase (k{sub d} = 0.16 d{sup -1}). Similarly, in the anaerobic digestion, the evolution of the substrate digested and the methane produced are followed, and the kinetic study is conducted using a modified Monod model combined with the Levenspiel model, due to the presence of inhibition effects. This model leads to the determination of the kinetic parameters: kinetic constant when no inhibitory substance is present (k{sub M0} = 8.4 x 10{sup -2} h{sup -1}), critical substrate concentration of inhibition (TP* = 0.34 g/L) and inhibitory parameter (n = 2.25)
Energy Technology Data Exchange (ETDEWEB)
Ibsen, Lars Bo; Liingaard, M.
2006-12-15
A lumped-parameter model represents the frequency dependent soil-structure interaction of a massless foundation placed on or embedded into an unbounded soil domain. In this technical report the steps of establishing a lumped-parameter model are presented. Following sections are included in this report: Static and dynamic formulation, Simple lumped-parameter models and Advanced lumped-parameter models. (au)
Kinetics of the thermal decomposition of pine needles
Directory of Open Access Journals (Sweden)
Dhaundiyal Alok
2015-12-01
Full Text Available A kinetic study of the pyrolysis process of pine needles was examined using a thermogravimetric analyser. The weight loss was measured in nitrogen atmosphere at a purge flow rate of 100 ml/min. The samples were heated over a range of temperature of 19°C–600°C with a heating rate of 10°C/min. The results obtained from the thermal decomposition process indicate that there are three main stages: dehydration, active and passive pyrolysis. The kinetic parameters for the different samples, such as activation energy and pre-exponential factor, are obtained by the shrinking core model (reaction-controlled regime, the model-free, and the first-order model. Experimental results showed that the shrinking model is in good agreement and can be successfully used to understand degradation mechanism of loose biomass. The result obtained from the reaction-controlled regime represented actual values of kinetic parameters which are the same for the whole pyrolysis process; whereas the model-free method presented apparent values of kinetic parameters, as they are dependent on the unknown function ϕ(C, on the sum of the parameters of the physical processes, and on the chemical reactions that happen simultaneously during pyrolysis. Experimental results showed that values of kinetic constant from the first-order model and the SCM are in good agreement and can be successfully used to understand the behaviour of loose biomass (pine needles in the presence of inert atmosphere. Using TGA results, the simulating pyrolysis can be done, with the help of computer software, to achieve a comprehensive detail of the devolatilization process of different types of biomasses.
Kinetic investigation for slow combustion of biomass
Energy Technology Data Exchange (ETDEWEB)
Haykiri-Acma, H.; Yaman, S. [Istanbul Technical Univ., Istanbul (Turkey). Dept. of Chemical Engineering, Faculty of Chemical and Metallurgical Engineering
2006-07-01
The renewed interest in biomass as a renewable, clean, and inexpensive fuel was discussed. Many different mechanisms take place simultaneously during biomass combustion and also during other thermal processes such as gasification, pyrolysis or carbonization. These mechanisms have a pronounced influence on the design and operation of thermal conversion processes. In addition, product yields and product distributions from the thermal processes are sensitive to the kinetic properties of biomass. In order to evaluate the combustion mechanisms and the combustion kinetics of biomass, the behavior of these constituents under combustion conditions were properly evaluated. In this study, combustion of biomass samples was carried out in a thermogravimetric analyzer by heating them from ambient to 1173 K with heating rates of 5 K/min and 10 K/min under dynamic dry air atmosphere of 40 mL/min. The biomass samples included olive refuse, sunflower seed shell, rapeseed, grape seed, and hybrid poplar. The purpose of the study was to examine the kinetic properties of biomass during slow combustion for the overall combustion process as well as for some definite temperature intervals at which different combustion mechanisms are present according to the type and complexity of biomass used. Derivative thermogravimetric analysis (DTG) curves were derived, and data obtained from these curves were used to compute the kinetic parameters such as activation energy, pre-exponential factor, and governing mechanisms for the combustion processes. The governing mechanisms for individual temperature intervals were examined along with the overall combustion process. The study showed that at lower temperature intervals, the combustion process was controlled primarily by the chemical reaction. At least 3 sequential mechanisms may occur at different temperature intervals during combustion of biomass. Activation energy and pre-exponential factors were determined for each temperature interval
Computer Simulation in Chemical Kinetics
Anderson, Jay Martin
1976-01-01
Discusses the use of the System Dynamics technique in simulating a chemical reaction for kinetic analysis. Also discusses the use of simulation modelling in biology, ecology, and the social sciences, where experimentation may be impractical or impossible. (MLH)
Kinetic model for torrefaction of wood chips in a pilot-scale continuous reactor
DEFF Research Database (Denmark)
Shang, Lei; Ahrenfeldt, Jesper; Holm, Jens Kai;
2014-01-01
the temperature along the reactor and the biomass feeding rate in combination with the kinetic parameters obtained from the tests in the TGA. Together with results from a laboratory scale, batch torrefaction reactor that was used to determine the higher heating value (HHV) and mass loss (y) of the same material......Torrefaction is a mild thermal treatment (200-300 °C) in an inert atmosphere, known to increase the energy density of biomass by evaporation of water and a proportion of the volatiles. In this work a "two-step reaction in series" model was used to describe the thermal degradation kinetics of pine...... wood. The kinetic parameters were determined using a thermogravimetric analyzer (TGA) and the mass loss during the initial heating period was taken into account when deriving the kinetic parameters. It was shown that the experimental results at different heating rates (10-50 °C min-1) are in good...
Kinetics of Slurry Phase Fischer-Tropsch Synthesis
Energy Technology Data Exchange (ETDEWEB)
Dragomir B. Bukur; Gilbert F. Froment; Tomasz Olewski; Lech Nowicki; Madhav Nayapati
2006-12-31
The overall objective of this project is to develop a comprehensive kinetic model for slurry-phase Fischer-Tropsch synthesis (FTS) employing iron-based catalysts. This model will be validated with experimental data obtained in a stirred-tank slurry reactor (STSR) over a wide range of process conditions. Three STSR tests of the Ruhrchemie LP 33/81 catalyst were conducted to collect data on catalyst activity and selectivity under 25 different sets of process conditions. The observed decrease in 1-olefin content and increase in 2-olefin and n-paraffin contents with the increase in conversion are consistent with a concept that 1-olefins participate in secondary reactions (e.g. 1-olefin hydrogenation, isomerization and readsorption), whereas 2-olefins and n-paraffins are formed in these reactions. Carbon number product distribution showed an increase in chain growth probability with increase in chain length. Vapor-liquid equilibrium calculations were made to check validity of the assumption that the gas and liquid phases are in equilibrium during FTS in the STSR. Calculated vapor phase compositions were in excellent agreement with experimental values from the STSR under reaction conditions. Discrepancies between the calculated and experimental values for the liquid-phase composition (for some of the experimental data) are ascribed to experimental errors in the amount of wax collected from the reactor, and the relative amounts of hydrocarbon wax and Durasyn 164 oil (start-up fluid) in the liquid samples. Kinetic parameters of four kinetic models (Lox and Froment, 1993b; Yang et al., 2003; Van der Laan and Beenackers, 1998, 1999; and an extended kinetic model of Van der Laan and Beenackers) were estimated from experimental data in the STSR tests. Two of these kinetic models (Lox and Froment, 1993b; Yang et al., 2003) can predict a complete product distribution (inorganic species and hydrocarbons), whereas the kinetic model of Van der Laan and Beenackers (1998, 1999) can
Kinetic modelling for zinc (II) ions biosorption onto Luffa cylindrica
Oboh, I.; Aluyor, E.; Audu, T.
2015-03-01
The biosorption of Zinc (II) ions onto a biomaterial - Luffa cylindrica has been studied. This biomaterial was characterized by elemental analysis, surface area, pore size distribution, scanning electron microscopy, and the biomaterial before and after sorption, was characterized by Fourier Transform Infra Red (FTIR) spectrometer. The kinetic nonlinear models fitted were Pseudo-first order, Pseudo-second order and Intra-particle diffusion. A comparison of non-linear regression method in selecting the kinetic model was made. Four error functions, namely coefficient of determination (R2), hybrid fractional error function (HYBRID), average relative error (ARE), and sum of the errors squared (ERRSQ), were used to predict the parameters of the kinetic models. The strength of this study is that a biomaterial with wide distribution particularly in the tropical world and which occurs as waste material could be put into effective utilization as a biosorbent to address a crucial environmental problem.
Kinetic modelling for zinc (II) ions biosorption onto Luffa cylindrica
Energy Technology Data Exchange (ETDEWEB)
Oboh, I., E-mail: innocentoboh@uniuyo.edu.ng [Department of Chemical and Petroleum Engineering, University of Uyo, Uyo (Nigeria); Aluyor, E.; Audu, T. [Department of Chemical Engineering, University of Uyo, BeninCity, BeninCity (Nigeria)
2015-03-30
The biosorption of Zinc (II) ions onto a biomaterial - Luffa cylindrica has been studied. This biomaterial was characterized by elemental analysis, surface area, pore size distribution, scanning electron microscopy, and the biomaterial before and after sorption, was characterized by Fourier Transform Infra Red (FTIR) spectrometer. The kinetic nonlinear models fitted were Pseudo-first order, Pseudo-second order and Intra-particle diffusion. A comparison of non-linear regression method in selecting the kinetic model was made. Four error functions, namely coefficient of determination (R{sup 2}), hybrid fractional error function (HYBRID), average relative error (ARE), and sum of the errors squared (ERRSQ), were used to predict the parameters of the kinetic models. The strength of this study is that a biomaterial with wide distribution particularly in the tropical world and which occurs as waste material could be put into effective utilization as a biosorbent to address a crucial environmental problem.
Amyloid protein unfolding and insertion kinetics on neuronal membrane mimics
Qiu, Liming; Buie, Creighton; Vaughn, Mark; Cheng, Kwan
2010-03-01
Atomistic details of beta-amyloid (Aβ ) protein unfolding and lipid interaction kinetics mediated by the neuronal membrane surface are important for developing new therapeutic strategies to prevent and cure Alzheimer's disease. Using all-atom MD simulations, we explored the early unfolding and insertion kinetics of 40 and 42 residue long Aβ in binary lipid mixtures with and without cholesterol that mimic the cholesterol-depleted and cholesterol-enriched lipid nanodomains of neurons. The protein conformational transition kinetics was evaluated from the secondary structure profile versus simulation time plot. The extent of membrane disruption was examined by the calculated order parameters of lipid acyl chains and cholesterol fused rings as well as the density profiles of water and lipid headgroups at defined regions across the lipid bilayer from our simulations. Our results revealed that both the cholesterol content and the length of the protein affect the protein-insertion and membrane stability in our model lipid bilayer systems.
Kinetics of methanol steam reforming over COPZr-2 catalyst
Institute of Scientific and Technical Information of China (English)
Yongfeng Li; Weiming Lin; Lin Yu; Zhifeng Hao; Rongjian Mai
2008-01-01
The COPZr-2 catalyst, which was prepared in our prophase research, showed good catalytic performance in methanol steam reforming reaction. In this article, the best one was chosen as an example to study the reaction kinetics of methanol steam reforming over this type of catalyst. First, the effects of methanol conversion to outlet CO2 and methanol conversion to outlet CO on methanol pseudo contact time W/FMeOH were investigated. Then by applying the reaction route that methanol direct reforming (DR) and methanol decomposition (DE) were carried out in parallel, the reaction kinetic model with power function type was established. And the parameters for the model were estimated using a non-linear regression program which computed weighted least squares of the defined objects function. Finally, the kinetic model passed the correlation test and the F-test.
Crystallization Kinetics within a Generic Modelling Framework
DEFF Research Database (Denmark)
Meisler, Kresten Troelstrup; von Solms, Nicolas; Gernaey, Krist;
2013-01-01
An existing generic modelling framework has been expanded with tools for kinetic model analysis. The analysis of kinetics is carried out within the framework where kinetic constitutive models are collected, analysed and utilized for the simulation of crystallization operations. A modelling...... procedure is proposed to gain the information of crystallization operation kinetic model analysis and utilize this for faster evaluation of crystallization operations....
Institute of Scientific and Technical Information of China (English)
李鹤群; 安崇伟; 杜梦远; 温晓沐; 王晶禹
2016-01-01
The thermal decomposition characteristics of DNTF and 2 ,4 ,6‐trinitrotoluene (TNT) were investigated by means of differential scanning calorimetry at different heating rates .The kinetic parameters of thermal decomposition reaction ,critical tem‐perature of thermal explosion and thermodynamic parameters were calculated ,contrasted and analyzed by Kissinger methed .The results show that the thermal decomposition process of DNTF is different with TNT ,it occurs in two stages and the first acts as the major part .The activation energy of DNTF is 168 .85kJ/mol ,which is about 58kJ/mol higher than that of TNT ,revealing that DNTF has a good thermal stability at low temperature .However ,all the other thermodynamic parameters of DNTF are higher than those of TNT except the free energy of activation .The decomposition peak temperatures and critical temperature of thermal explosion of DNTF are lower than those of TNT .So ,the thermal stability of DNTF is poorer than that of TNT .%采用差示扫描量热法研究了 DNTF和TNT在不同升温速率下的热分解特性；利用Kissinger方法计算和对比分析了DNTF和TNT的热分解反应动力学参数、热爆炸临界温度和热力学参数。结果表明，DNTF的热分解过程不同于TNT ，DNTF的热分解经历了两个阶段，其中第1阶段为主要部分。DNTF的活化能为168．85kJ／mol ，比TNT高约58 kJ／mol ，表明DNTF在低温下有良好的热稳定性。然而，除自由活化能外，DNTF的其他热力学参数均比TNT高。DNTF的热分解峰温和热爆炸临界温度都比 TNT小。因此，与TNT相比，DNTF的热稳定性差。
Computer-Aided Construction of Chemical Kinetic Models
Energy Technology Data Exchange (ETDEWEB)
Green, William H. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
2014-12-31
The combustion chemistry of even simple fuels can be extremely complex, involving hundreds or thousands of kinetically significant species. The most reasonable way to deal with this complexity is to use a computer not only to numerically solve the kinetic model, but also to construct the kinetic model in the first place. Because these large models contain so many numerical parameters (e.g. rate coefficients, thermochemistry) one never has sufficient data to uniquely determine them all experimentally. Instead one must work in “predictive” mode, using theoretical rather than experimental values for many of the numbers in the model, and as appropriate refining the most sensitive numbers through experiments. Predictive chemical kinetics is exactly what is needed for computer-aided design of combustion systems based on proposed alternative fuels, particularly for early assessment of the value and viability of proposed new fuels before those fuels are commercially available. This project was aimed at making accurate predictive chemical kinetics practical; this is a challenging goal which requires a range of science advances. The project spanned a wide range from quantum chemical calculations on individual molecules and elementary-step reactions, through the development of improved rate/thermo calculation procedures, the creation of algorithms and software for constructing and solving kinetic simulations, the invention of methods for model-reduction while maintaining error control, and finally comparisons with experiment. Many of the parameters in the models were derived from quantum chemistry calculations, and the models were compared with experimental data measured in our lab or in collaboration with others.
Uniqueness of thermodynamic projector and kinetic basis of molecular individualism
Gorban, Alexander N.; Karlin, Iliya V.
2004-05-01
Three results are presented: First, we solve the problem of persistence of dissipation for reduction of kinetic models. Kinetic equations with thermodynamic Lyapunov functions are studied. Uniqueness of the thermodynamic projector is proven: There exists only one projector which transforms any vector field equipped with the given Lyapunov function into a vector field with the same Lyapunov function for a given anzatz manifold which is not tangent to the Lyapunov function levels. Second, we use the thermodynamic projector for developing the short memory approximation and coarse-graining for general nonlinear dynamic systems. We prove that in this approximation the entropy production increases. ( The theorem about entropy overproduction.) In example, we apply the thermodynamic projector to derive the equations of reduced kinetics for the Fokker-Planck equation. A new class of closures is developed, the kinetic multipeak polyhedra. Distributions of this type are expected in kinetic models with multidimensional instability as universally as the Gaussian distribution appears for stable systems. The number of possible relatively stable states of a nonequilibrium system grows as 2 m, and the number of macroscopic parameters is in order mn, where n is the dimension of configuration space, and m is the number of independent unstable directions in this space. The elaborated class of closures and equations pretends to describe the effects of “molecular individualism”. This is the third result.
A study of redox kinetic in silicate melt
International Nuclear Information System (INIS)
The aim of this thesis is to understand better iron redox reactions and mechanisms in silicate glasses and melts. Particular interest has been paid to the influence of temperature and chemical composition. For this purpose, the influence of alkali element content, iron content and network formers on the kinetics of redox reactions has been determined through XANES and Raman spectroscopy experiments performed either near the glass transition or above the liquidus temperature. As a complement, electrical conductivity and RBS spectroscopy experiments have been made to characterize the diffusivity of the species that transport electrical charges and the reaction morphology, respectively. Temperature and composition variations can induce changes in the dominating redox mechanism. At a given temperature, the parameters that exert the strongest influence on redox mechanisms are the presence or lack of divalent cations and the existing decoupling between the mobility of network former and modifier elements. Near Tg, the diffusion of divalent cations, when present in the melt, controls the kinetics of iron redox reactions along with a flux of electron holes. Composition, through the degree of polymerization and the silicate network structure, influences the kinetics and the nature of the involved cations, but not the mechanisms of the reaction. Without alkaline earth elements, the kinetics of redox reactions are controlled by the diffusion of oxygen species. With increasing temperatures, the diffusivities of all ionic species tend to become similar. The decoupling between ionic fluxes then is reduced so that several mechanisms become kinetically equivalent and can thus coexist. (author)
Kinetics of in situ combustion. SUPRI TR 91
Energy Technology Data Exchange (ETDEWEB)
Mamora, D.D.; Ramey, H.J. Jr.; Brigham, W.E.; Castanier, L.M.
1993-07-01
Oxidation kinetic experiments with various crude oil types show two reaction peaks at about 250{degree}C (482{degree}F) and 400{degree}C (725{degree}F). These experiments lead to the conclusion that the fuel during high temperature oxidation is an oxygenated hydrocarbon. A new oxidation reaction model has been developed which includes two partially-overlapping reactions: namely, low-temperature oxidation followed by high-temperature oxidation. For the fuel oxidation reaction, the new model includes the effects of sand grain size and the atomic hydrogen-carbon (H/C) and oxygen-carbon (O/C) ratios of the fuel. Results based on the new model are in good agreement with the experimental data. Methods have been developed to calculate the atomic H/C and O/C ratios. These methods consider the oxygen in the oxygenated fuel, and enable a direct comparison of the atomic H/C ratios obtained from kinetic and combustion tube experiments. The finding that the fuel in kinetic tube experiments is an oxygenated hydrocarbon indicates that oxidation reactions are different in kinetic and combustion tube experiments. A new experimental technique or method of analysis will be required to obtain kinetic parameters for oxidation reactions encountered in combustion tube experiments and field operations.
The kinetic regime of the Vicsek model
Chepizhko, A. A.; Kulinskii, V. L.
2009-12-01
We consider the dynamics of the system of self-propelling particles modeled via the Vicsek algorithm in continuum time limit. It is shown that the alignment process for the velocities can be subdivided into two regimes: "fast" kinetic and "slow" hydrodynamic ones. In fast kinetic regime the alignment of the particle velocity to the local neighborhood takes place with characteristic relaxation time. So, that the bigger regions arise with the velocity alignment. These regions align their velocities thus giving rise to hydrodynamic regime of the dynamics. We propose the mean-field-like approach in which we take into account the correlations between density and velocity. The comparison of the theoretical predictions with the numerical simulations is given. The relation between Vicsek model in the zero velocity limit and the Kuramoto model is stated. The mean-field approach accounting for the dynamic change of the neighborhood is proposed. The nature of the discontinuity of the dependence of the order parameter in case of vectorial noise revealed in Gregorie and Chaite, Phys. Rev. Lett., 92, 025702 (2004) is discussed and the explanation of it is proposed.
Energy Technology Data Exchange (ETDEWEB)
Parsa, Z.
1986-10-01
The AGS Booster is designed to be an intermediate synchrotron injector for the AGS, capable of accelerating protons from 200 MeV to 1.5 GeV. The parameters listed include beam and operational parameters and lattice parameters, as well as parameters pertaining to the accelerator's magnets, vacuum system, radio frequency acceleration system, and the tunnel. 60 refs., 41 figs. (LEW)
大庆常渣催化裂解反应动力学模型%Establishment of Kinetic Model for Catalytic Pyrolysis of Daqing Atmospheric Residue
Institute of Scientific and Technical Information of China (English)
刘熠斌; 陈小博; 赵辉; 杨朝合
2009-01-01
An 8-lump kinetic model was proposed to predict the yields of propylene, ethylene and gasoline in the catalytic pyrolysis process of Daqing atmospheric residue. The model contains 21 kinetic parameters and one for catalyst deactivation. A series of experiments were carried out in a riser reactor over catalyst named LTB-2. The ki-netic parameters were estimated by using sub-model method, and apparent activation energies were calculated ac-cording to the Arrhenius equation. The predicted yields coincided well with the experimental values. It shows that the kinetic parameters estimated by using the sub-model method were reliable.
Cure kinetics of epoxy matrix resin by differential scanning calorimetry
Cizmecioglu, M.; Gupta, A.
1982-01-01
A study was made on the cure kinetics of an epoxy neat-resin (Narmco 5208) using Differential Scanning Calorimetry (DSC). Two interrelated analytical methods were applied to dynamic DSC data for evaluating the kinetic parameters, such as activation energy, E, the order of reaction, n, and the total heat of polymerization (or crosslinking), delta H sub t. The first method was proposed by Ellerstein (1968), and uses a thorough differential-integral analysis of a single DSC curve to evaluate the kinetic parameters. The second method was proposed by Kissinger (1957), and uses multiple DSC curves obtained at various heating rates to evaluate E regardless of n. Kinetic analysis of Narmco 5208 epoxy resin showed that the reaction order, n, is substantially affected by the rate of heating; i.e., n is approximately 2 at slow scan rates but is reduced to 1.5 at higher scan rates. The activation energy, E, is not affected by the scan rate, and the average value of E is 25.6 + or - 1.8 kcal/mole.
Enzymatic hydrolysis of protein:mechanism and kinetic model
Institute of Scientific and Technical Information of China (English)
Qi Wei; He Zhimin
2006-01-01
The bioreaction mechanism and kinetic behavior of protein enzymatic hydrolysis for preparing active peptides were investigated to model and characterize the enzymatic hydrolysis curves.Taking into account single-substrate hydrolysis,enzyme inactivation and substrate or product inhibition,the reaction mechanism could be deduced from a series of experimental results carried out in a stirred tank reactor at different substrate concentrations,enzyme concentrations and temperatures based on M-M equation.An exponential equation dh/dt = aexp(-bh) was also established,where parameters a and b have different expressions according to different reaction mechanisms,and different values for different reaction systems.For BSA-trypsin model system,the regressive results agree with the experimental data,i.e.the average relative error was only 4.73%,and the reaction constants were determined as Km = 0.0748 g/L,Ks = 7.961 g/L,kd = 9.358/min,k2 =38.439/min,Ea= 64.826 kJ/mol,Ed= 80.031 kJ/mol in accordance with the proposed kinetic mode.The whole set of exponential kinetic equations can be used to model the bioreaction process of protein enzymatic hydrolysis,to calculate the thermodynamic and kinetic constants,and to optimize the operating parameters for bioreactor design.
Hidden percolation transition in kinetic replication process
Timonin, P. N.; Chitov, G. Y.
2015-04-01
The one-dimensional kinetic contact process with parallel update is introduced and studied by the mean-field approximation and Monte Carlo (MC) simulations. Contrary to a more conventional scenario with single active phase for 1d models with Ising-like variables, we find two different adjacent active phases in the parameter space of the proposed model with a second-order transition between them and a multiphase point where the active and the absorbing phases meet. While one of the active phases is quite standard with a smooth average filling of the space-time lattice, the second active phase demonstrates a very subtle (hidden) percolating order which becomes manifest only after certain transformation from the original model. We determine the percolation order parameter for active-active phase transition and discuss such hidden orders in other low-dimensional systems. Our MC data demonstrate finite-size critical and near-critical scaling of the order parameter relaxation for the two phase transitions. We find three independent critical indices for them and conclude that they both belong to the directed percolation universality class.
Wypijewska, Anna; Bojarska, Elzbieta; STEPINSKI, JANUSZ; Jankowska-Anyszka, Marzena; Jemielity, Jacek; Davis, Richard E.; Darzynkiewicz, Edward
2010-01-01
The activity of C. elegans scavenger decapping enzyme (DcpS) on its natural substrates and dinucleotide cap analogues modified in the nucleoside’s base or ribose moiety, has been examined. All tested dinucleotides were specifically cleaved between β and γ phosphate groups in the triphosphate chain. The kinetic parameters of enzymatic hydrolysis (Km, Vmax) were determined using fluorescence and HPLC methods, as complementary approaches for the kinetic studies of C. elegans DcpS. From the kinet...
International Nuclear Information System (INIS)
A series of measurements characterizing an e beam pumped KrF* laser was carried out using a 200-nsec e-beam pulse having a rise time of 25 nsec at current densities up to 50 A/cm2. These pump conditions are relevent for inertial confinement fusion laser drivers. The measurements include fluorescence efficiency, sidelight suppression of the fluorescence during lasing, and laser energy output over a wide range of laser parameters including: total density 0.5--2.0 amagats, temperature 300--400 K, fluorine density 0.15%--0.5%, current density 38--50 A/cm2 and various mirror transmissions. This data was used to verify and refine a model of KrF* kinetics which was then used to estimate the performance of an angular multiplexed power amplifier suitable for laser fusion applications
Desulfurization kinetics of coal combustion gases
Energy Technology Data Exchange (ETDEWEB)
Braganca, S.R.; Jablonski, A.; Castellan, J.L. [Universidade Federal Rio Grande do Sul, Porto Alegre (Brazil)
2003-06-01
Desulfurization of the gases from coal combustion was studied, using limestone (marble) as the sorbent in a fluidized-bed reactor. The kinetic parameter, k, was measured by analyzing the reduction in SO{sub 2} emissions in relation to time when a batch of limestone was introduced directly into the combustor chamber. The influence of sorbent composition and particle size was also studied. The CaO content in the limestone was more important than the MgO content. Sorbent particle size showed a strong influence on the reaction time and efficiency of desulfurization. The results of this work prove that marble type is very important in the choice of sorbent for a desulfurization process. A magnesian limestone showed a better performance than a dolomite. Therefore, the magnesian limestone is more efficient for a shorter particle residence time, which is characteristic of the bubbling fluidized bed.
Kinetic Stable Delaunay Graphs
Agarwal, Pankaj K; Guibas, Leonidas J; Kaplan, Haim; Koltun, Vladlen; Rubin, Natan; Sharir, Micha
2011-01-01
We consider the problem of maintaining the Euclidean Delaunay triangulation $\\DT$ of a set $P$ of $n$ moving points in the plane, along algebraic trajectories of constant description complexity. Since the best known upper bound on the number of topological changes in the full $\\DT$ is nearly cubic, we seek to maintain a suitable portion of it that is less volatile yet retains many useful properties. We introduce the notion of a stable Delaunay graph, which is a dynamic subgraph of the Delaunay triangulation. The stable Delaunay graph (a) is easy to define, (b) experiences only a nearly quadratic number of discrete changes, (c) is robust under small changes of the norm, and (d) possesses certain useful properties. The stable Delaunay graph ($\\SDG$ in short) is defined in terms of a parameter $\\alpha>0$, and consists of Delaunay edges $pq$ for which the angles at which $p$ and $q$ see their Voronoi edge $e_{pq}$ are at least $\\alpha$. We show that (i) $\\SDG$ always contains at least roughly one third of the Del...
Degradation kinetics and mechanisms of phenolin photo－Fenton process
Institute of Scientific and Technical Information of China (English)
何锋; 雷乐成
2004-01-01
Phenol degradation in photochemically enhanced Fenton process was investigated in this work. UV-VIS spectra of phenol degradation showed the difference between photo-Fenton process and UV/H2O2, which is a typical hydroxyl radical process. A possible pathway diagram for phenol degradation in photo-Fenton process was proposed, and a mathematical model for chemical oxygen demand (COD) removal was developed. Operating parameters such as dosage of H2O2 and ferrous ions, pH, suitable carrier gas were found to impact the removal of COD significantly. The results and analysis of kinetic parameters calculated from the kinetic model showed that complex degradation of phenol was the main pathway for removal of COD: while hydroxyl radicals acted weakly in the photo-Fenton degradation of phenol.
Kinetics of propionate conversion in anaerobic continuously stirred tank reactors
DEFF Research Database (Denmark)
Bangsø Nielsen, Henrik; Mladenovska, Zuzana; Ahring, Birgitte Kiær
2008-01-01
The kinetic parameters of anaerobic propionate degradation by biomass from 7 continuously stirred tank reactors differing in temperature, hydraulic retention time and substrate composition were investigated. In substrate-depletion experiments (batch) the maximum propionate degradation rate, A......-m, was estimated. The results demonstrate that the rate of endogenous substrate (propionate) production should be taken into account when estimating kinetic parameters in biomass from manure-based anaerobic reactors.......(max), and the half saturation constant, K-m, were initially estimated by applying the integrated Michaelis-Menten equation. A(max) was in the range from 22.8 to 29.1 mu mol gVS(-1) h(-1) while K-m, was in the range from 0.46-0.95 mM. In general, A(max) gave a good reflection of the reactor performances. Secondly...
Kinetics with deactivation of methylcyclohexane dehydrogenation for hydrogen energy storage
Energy Technology Data Exchange (ETDEWEB)
Maria, G.; Marin, A.; Wyss, C.; Mueller, S.; Newson, E. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)
1997-06-01
The methylcyclohexane dehydrogenation step to recycle toluene and release hydrogen is being studied as part of a hydrogen energy storage project. The reaction is performed catalytically in a fixed bed reactor, and the efficiency of this step significantly determines overall system economics. The fresh catalyst kinetics and the deactivation of the catalyst by coke play an important role in the process analysis. The main reaction kinetics were determined from isothermal experiments using a parameter sensitivity analysis for model discrimination. An activation energy for the main reaction of 220{+-}11 kJ/mol was obtained from a two-parameter model. From non-isothermal deactivation in PC-controlled integral reactors, an activation energy for deactivation of 160 kJ/mol was estimated. A model for catalyst coke content of 3-17 weight% was compared with experimental data. (author) 3 figs., 6 refs.
Triebwasser-Freese, D.; Tharayil, N.; Preston, C. M.; Gerard, P.
2013-12-01
Recently, it has been suggested that lignin exhibit a turnover rate of less than 6 years, suggesting that the enzymatic mechanisms mediating the decay of lignin are less understood. One factor that could be affecting the mean residence time of lignin in the soil is the catalytic efficiency of soil oxidoreductase enzymes. We characterized the spatial and seasonal transitions in the Michaelis-Menten kinetics and activation energy of the soil oxidoreductase enzyme, peroxidase, across three ecosystems of differing litter chemistries- pine, deciduous forest, and a cultivated field- and associate it to the soil lignin chemistries. To interpret the combined effect of Vmax and Km, the two parameters were integrated into one term which we defined as the catalytic efficiency. Generally, the peroxidases in pine soils exhibited the highest Vmax and Km, resulting in the lowest catalytic efficiency, followed by that in the deciduous soils. Meanwhile, the agricultural soils which exhibited the lowest Vmax and Km contained the highest catalytic efficiency of peroxidase. Through linear regression analysis of the kinetic parameters to the soil lignin chemistry, we discerned that the catalytic efficiency term best associated to the lignin monomer ratios (C/V, P/V, and SCV/V). The Activation Energy of peroxidase varied by depth, and seasons across the ecosystems. However, the Activation Energy of peroxidase did not relate to the lignin chemistry or quantity. Collectively, our results show that although the peroxidase Vmax and Km in the phenolic-poor soils are low, the degradation efficiency of peroxidases in this soils can be equivalent or exceed that of phenolic-rich soils. This study, through the characterization of Michaelis-Menten kinetics, provides a new insight into the mechanisms that could moderate the decomposition of lignin in soils.
Parallelization of Kinetic Theory Simulations
Howell, Jim; Colbry, Dirk; Pickett, Rodney; Staber, Alec; Sagert, Irina; Strother, Terrance
2013-01-01
Numerical studies of shock waves in large scale systems via kinetic simulations with millions of particles are too computationally demanding to be processed in serial. In this work we focus on optimizing the parallel performance of a kinetic Monte Carlo code for astrophysical simulations such as core-collapse supernovae. Our goal is to attain a flexible program that scales well with the architecture of modern supercomputers. This approach requires a hybrid model of programming that combines a message passing interface (MPI) with a multithreading model (OpenMP) in C++. We report on our approach to implement the hybrid design into the kinetic code and show first results which demonstrate a significant gain in performance when many processors are applied.
Kinetic theory and transport phenomena
Soto, Rodrigo
2016-01-01
This textbook presents kinetic theory, which is a systematic approach to describing nonequilibrium systems. The text is balanced between the fundamental concepts of kinetic theory (irreversibility, transport processes, separation of time scales, conservations, coarse graining, distribution functions, etc.) and the results and predictions of the theory, where the relevant properties of different systems are computed. The book is organised in thematic chapters where different paradigmatic systems are studied. The specific features of these systems are described, building and analysing the appropriate kinetic equations. Specifically, the book considers the classical transport of charges, the dynamics of classical gases, Brownian motion, plasmas, and self-gravitating systems, quantum gases, the electronic transport in solids and, finally, semiconductors. Besides these systems that are studied in detail, concepts are applied to some modern examples including the quark–gluon plasma, the motion of bacterial suspen...
KINIK, Absorber Rod Calibration Kinetics
International Nuclear Information System (INIS)
1 - Description of program or function: KINIK is an inverse kinetic code that solves the inverse form of the point kinetic equations using the Runge-Kutta method. An optimization procedure is involved to control the time step and to reduce the running time. Up to 24 delayed neutron groups of different types (in case of heavy water as moderator or beryllium as reflector) are considered. KINIK is commonly applied to determine reactivity worths and to calibrate absorber rods. Following a rod drop, neutron flux or power is recorded as a function of time and used as input. 2 - Method of solution: The inverse point kinetic equations are numerically solved for each time step using the Runge-Kutta method. The input data resulting from measurements are first approximated by polynomials of maximum degree 10 using a least-squares approach
Ordaz, Alberto; López, Juan C; Figueroa-González, Ivonne; Muñoz, Raúl; Quijano, Guillermo
2014-12-15
Biological methane biodegradation is a promising treatment alternative when the methane produced in waste management facilities cannot be used for energy generation. Two-phase partitioning bioreactors (TPPBs), provided with a non-aqueous phase (NAP) with high affinity for the target pollutant, are particularly suitable for the treatment of poorly water-soluble compounds such as methane. Nevertheless, little is known about the influence of the presence of the NAP on the resulting biodegradation kinetics in TPPBs. In this study, an experimental framework based on the in situ pulse respirometry technique was developed to assess the impact of NAP addition on the methane biodegradation kinetics using Methylosinus sporium as a model methane-degrading microorganism. A comprehensive mass transfer characterization was performed in order to avoid mass transfer limiting scenarios and ensure a correct kinetic parameter characterization. The presence of the NAP mediated significant changes in the apparent kinetic parameters of M. sporium during methane biodegradation, with variations of 60, 120, and 150% in the maximum oxygen uptake rate, half-saturation constant and maximum specific growth rate, respectively, compared with the intrinsic kinetic parameters retrieved from a control without NAP. These significant changes in the kinetic parameters mediated by the NAP must be considered for the design, operation and modeling of TPPBs devoted to air pollution control.
Kotasidis, F. A.; Matthews, J. C.; Reader, A. J.; Angelis, G. I.; Zaidi, H.
2014-01-01
Parametric imaging in thoracic and abdominal PET can provide additional parameters more relevant to the pathophysiology of the system under study. However, dynamic data in the body are noisy due to the limiting counting statistics leading to suboptimal kinetic parameter estimates. Direct 4D image re
Selected readings in chemical kinetics
Back, Margaret H
2013-01-01
Selected Readings in Chemical Kinetics covers excerpts from 12 papers in the field of general and gas-phase kinetics. The book discusses papers on the laws of connexion between the conditions of a chemical change and its amount; on the reaction velocity of the inversion of the cane sugar by acids; and the calculation in absolute measure of velocity constants and equilibrium constants in gaseous systems. The text then tackles papers on simple gas reactions; on the absolute rate of reactions in condensed phases; on the radiation theory of chemical action; and on the theory of unimolecular reacti
Chemical kinetics and combustion modeling
Energy Technology Data Exchange (ETDEWEB)
Miller, J.A. [Sandia National Laboratories, Livermore, CA (United States)
1993-12-01
The goal of this program is to gain qualitative insight into how pollutants are formed in combustion systems and to develop quantitative mathematical models to predict their formation rates. The approach is an integrated one, combining low-pressure flame experiments, chemical kinetics modeling, theory, and kinetics experiments to gain as clear a picture as possible of the process in question. These efforts are focused on problems involved with the nitrogen chemistry of combustion systems and on the formation of soot and PAH in flames.