Reaction-Rate Kinetics and Distribution of Activation Energies

1970 ◽  
Vol 1 (2) ◽  
pp. 932-933 ◽  
Author(s):  
P. H. Fang
Keyword(s):  
Reaction Rate ◽  
Activation Energies ◽  
Rate Kinetics

A Novel, Label-Free Method for Quantifying Collagen Fibril Formation and Degradation Using DIC Microscopy, Electromagnetic Wave Theory, and Image Processing

2009 ◽  
Author(s):  
Brendan P. Flynn ◽  
Amit Bhole ◽  
Charles DiMarzio ◽  
Jeffrey W. Ruberti
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Electromagnetic Wave ◽  
Collagen Fibril ◽  
Reaction Rate ◽  
Wave Theory ◽  
Label Free ◽  
Averaging Methods ◽  
Rate Kinetics ◽  
Dic Microscopy

Methods to assay fibrillar growth and degradation at sub-light scales include: fluorescence assays using FITC-collagen or FRAP, destructive preparation and measurement using electron microscopy, and light occlusion methods including turbidity and absorption methods. Many of these methods require the outright destruction, or at least modification via labelling, of the sample in question. This requirement can slow experimentation and introduce additional variability or even alter the reaction rate kinetics. The two methods (absorption and turbidity) which are label-free are bulk averaging methods and cannot isolate subsets of fibrils (e.g. fibrils under load).

scholarly journals Aromatization of light naphtha fractions on zeolites 1: Kinetic model

2003 ◽  
Vol 57 (9) ◽  
pp. 399-403 ◽  
Author(s):  
Svetlana Rovenskaja ◽  
Nikolaj Ostrovski
Keyword(s):  
Experimental Data ◽  
Kinetic Model ◽  
Rate Constants ◽  
Reaction Rate ◽  
Reaction Scheme ◽  
Activation Energies ◽  
Modeling And Optimization ◽  
Light Naphtha ◽  
Reaction Rate Constants

On the basis of analyzing kinetic experimental data performed in laboratory integral reactors a lumping kinetic model of the "Zeoforming" process was developed. A reaction scheme of the lumped components was proposed, that was adapted to the technological requirements. The reaction rate constants and activation energies were estimated, that are valid for certain feed compositions. The model is intended for further modeling and optimization of the process.

STUDIES ON THERMOKINETIC METHODS (Ⅰ) DETERMINATION OF REACTION RATE CONSTANTS AND ACTIVATION ENERGIES BY CALORIMETRY

1986 ◽  
Vol 2 (04) ◽  
pp. 363-370 ◽  
Author(s):  
Xie Changli ◽  
◽  
Xu Quiduan ◽  
Qu Songsheng ◽  
Richard K. Owusu.
Keyword(s):  
Rate Constants ◽  
Reaction Rate ◽  
Activation Energies ◽  
Reaction Rate Constants

Interfacial reactions in multilayers intended for microelectronics devices

1998 ◽  
Vol 514 ◽  
Author(s):  
X. Federspiel ◽  
F. Voiron ◽  
M. Ignat ◽  
T. Marieb ◽  
H. Fujimoto
Keyword(s):  
Phase Formation ◽  
Reaction Rate ◽  
Experimental Approach ◽  
Intermetallic Phase ◽  
Activation Energies ◽  
Interfacial Reactions ◽  
Scanning Calorimetry ◽  
Back Scattering ◽  
Apparent Activation Energies ◽  
Kinetics Of

ABSTRACTThe knowledge of the reaction kinetics which can occur at an interface of a couple of materials, remains a crucial issue to establish the structural limits of a diffusion barrier intended for microelectronic structures.In the past years, the interfacial reactions activated at an interface of a couple of materials, as for example aluminum and titanium, have been analyzed extensively using different experimental tools, as for example: Ruthreford Back Scattering (thickness determination) and Differential Scanning Calorimetry (DSC). Then, these experimental methods were useful to deduce parameters, characterizing the interfacial reactions in bulk samples: apparent activation energies, enthalpy of formation. Because in thin films, the kinetics of the reactions that can be activated at an interface will be different; we studied interfacial reactions in submicronic Al/Ti layers.Taking advantage of the accuracy of the DSC (reaction rate determinations and detection of earlier stages of intermetallic phase formation), our experimental approach consisted in a series of isothermal and non-isothermal DSC experiments on submicron Al/Ti layered structures. From the reaction rate determination, analytical methods as the Kissinger Ozawa approach were used, to determine the apparent activation energies of the phase formation. Also the results allowed to model and discuss the first steps of the interfacial reaction.

Modelling biological Cr(VI) reduction in aquifer microcosm column systems

2013 ◽  
Vol 67 (12) ◽  
pp. 2733-2738 ◽  
Author(s):  
Pulane E. Molokwane ◽  
Evans M. N. Chirwa
Keyword(s):  
Reaction Rate ◽  
Removal Rate ◽  
Groundwater Resources ◽  
Cost Effective ◽  
Threshold Concentration ◽  
Batch Reactors ◽  
Flow Process ◽  
Detailed Evaluation ◽  
Rate Kinetics ◽  
Contamination Levels

Several chrome processing facilities in South Africa release hexavalent chromium (Cr(VI)) into groundwater resources. Pump-and-treat remediation processes have been implemented at some of the sites but have not been successful in reducing contamination levels. The current study is aimed at developing an environmentally friendly, cost-effective and self-sustained biological method to curb the spread of chromium at the contaminated sites. An indigenous Cr(VI)-reducing mixed culture of bacteria was demonstrated to reduce high levels of Cr(VI) in laboratory samples. The effect of Cr(VI) on the removal rate was evaluated at concentrations up to 400 mg/L. Following the detailed evaluation of fundamental processes for biological Cr(VI) reduction, a predictive model for Cr(VI) breakthrough through aquifer microcosm reactors was developed. The reaction rate in batch followed non-competitive rate kinetics with a Cr(VI) inhibition threshold concentration of approximately 99 mg/L. This study evaluates the application of the kinetic parameters determined in the batch reactors to the continuous flow process. The model developed from advection–reaction rate kinetics in a porous media fitted best the effluent Cr(VI) concentration. The model was also used to elucidate the logistic nature of biomass growth in the reactor systems.

scholarly journals Metallic Hydrides I: Hydrogen Storage and Other Gas-Phase Applications

MRS Bulletin ◽  
2002 ◽  
Vol 27 (9) ◽  
pp. 688-693 ◽  
Author(s):  
Robert C. Bowman ◽  
Brent Fultz
Keyword(s):  
Hydrogen Storage ◽  
Reaction Rate ◽  
Separation And Purification ◽  
Hydrogen Storage Capacity ◽  
Fuel Gas ◽  
Thermal Switches ◽  
Rate Kinetics ◽  
Initial Activation ◽  
Alloys And Compounds

AbstractA brief survey is given of the various classes of metal alloys and compounds that are suitable for hydrogen-storage and energy-conversion applications. Comparisons are made of relevant properties including hydrogen absorption and desorption pressures, total and reversible hydrogen-storage capacity, reaction-rate kinetics, initial activation requirements, susceptibility to contamination, and durability during long-term thermal cycling. Selected applications are hydrogen storage as a fuel, gas separation and purification, thermal switches, and sorption cryocoolers.

Turbulent mean reaction rates in the limit of large activation energies

1981 ◽  
Vol 110 ◽  
pp. 411-432 ◽  
Author(s):  
N. Peters ◽  
W. Hocks ◽  
G. Mohiuddin
Keyword(s):  
Reaction Rate ◽  
Laminar Flame ◽  
Mixture Fraction ◽  
Beta Function ◽  
Reaction Rates ◽  
Activation Energies ◽  
Premixed Combustion ◽  
Flame Velocity ◽  
Progress Variable ◽  
The Mean

Closed-form expressions for the turbulent mean reaction rate and its covariance with the temperature are derived for premixed and non-premixed combustion. The limit of large activation energies is exploited for a chemical reaction rate that, by virtue of coupling functions, depends on the mixture fraction and a non-equilibrium progress variable only. The probability density function (p.d.f.) formulation with an assumed shape of the p.d.f. is used; a beta-function distribution is assumed for the progress variable. The mean reaction rate is expressed in terms of the mean and the variance of the temperature and, for non-premixed combustion, of the mixture fraction. The reaction kinetics are represented by the non-dimensional activation energy and the laminar flame velocity. For non-premixed systems the possibility of local extinction by flame stretch is considered.

The Reactions of Thrombin with Fibrinogen and Plasma Antithrombin

1965 ◽  
Vol 13 (02) ◽  
pp. 343-360 ◽  
Author(s):  
L. A Kazal ◽  
G. F Grannis ◽  
L. M Tocantins
Keyword(s):  
Amino Acid ◽  
Reaction Rate ◽  
Optimal Conditions ◽  
Bovine Thrombin ◽  
First Order ◽  
Antithrombin Activity ◽  
Effects Of Ph ◽  
Rate Kinetics ◽  
Independent Parameters ◽  
Amino Acid Concentrations

SummaryThe effects of pH, salt and amino acid (β-alanine) concentration on the rate of thrombin formation and antithrombin activity in recalcified plasma was studied from the viewpoint of reaction rate kinetics, and units of thrombin and antithrombin activity defined on this basis. Optimal thrombin activity (fibrin formation) was observed between pH 6.5 and 8.0 and at 0.19 M NaCl. Maximal antithrombin activity occurred at pH 8.5 and 0.10 M sodium chloride.Antithrombin activity, examined under optimal conditions as well as under the influence of changes in pH, and of salt and amino acid concentrations proved to follow first-order reaction kinetics. The activities of thrombin and antithrombin changed in a diphasic manner with increasing concentrations of salt or amino acid and such change may represent subtle protein-protein or protein-salt interactions.The antithrombin activity of fifteen normal plasmas was determined from reaction rate studies of thrombin destroyed during recalcification of human plasma and compared to the inactivation of bovine thrombin by citrated plasma.A concept of “coagulability” of plasma based on the measurement of two independent parameters, fibrinogen and antithrombin, and their kinetic interrelationships, was developed as an approach to a functional concept of hemostasis.

The application of wave-mechanics to reactions involving hydrogen and diplogen

1934 ◽  
Vol 30 (4) ◽  
pp. 508-513
Author(s):  
R. A. Smith
Keyword(s):  
Activation Energy ◽  
Quantum Theory ◽  
Chemical Reactions ◽  
Reaction Mechanisms ◽  
Reaction Rate ◽  
Theoretical Study ◽  
Electronic States ◽  
Activation Energies ◽  
Wave Mechanics

A considerable amount of work has recently been done on the application of wave-mechanics to the theoretical study of chemical reactions. This has consisted chiefly in calculating activation energies and strengths of various bonds by consideration of electronic states in molecules. Some work has also been done on actual reaction mechanisms. It is evident from the latter that, owing to the large masses of the particles concerned, the quantum theory and the classical treatment will give different results only for reactions involving hydrogen or diplogen. Previous attempts to deal with such reactions have consisted simply of calculating the permeabilityG(W) of a barrier of height equal to the activation energy for protons of energyW.The reaction rate is then assumed to be given by

Sign in / Sign up

Export Citation Format

Share Document