Two-Stage Kinetics of Single-Chain Collapse. Polystyrene in Cyclohexane

Abstract The paper contributes to the clarification of the mechanism of one-dimensional pulsating detonation wave propagation for the transition regime with two-scale pulsations. For this purpose, a novel numerical algorithm has been developed for the numerical investigation of the gaseous pulsating detonation wave using the two-stage model of kinetics of chemical reactions in the shock-attached frame. The influence of grid resolution, approximation order and the type of rear boundary conditions on the solution has been studied for four main regimes of detonation wave propagation for this model. Comparison of dynamics of pulsations with results of other authors has been carried out.

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Overall crystallization kinetics of polymorphic propylene–ethylene random copolymers: A two-stage parallel model of Avrami kinetics

Polymer ◽

10.1016/j.polymer.2007.03.075 ◽

2007 ◽

Vol 48 (11) ◽

pp. 3170-3182 ◽

Cited By ~ 6

Author(s):

Y.L. Chiari ◽

M. Vadlamudi ◽

R. Chella ◽

K. Jeon ◽

R.G. Alamo

Keyword(s):

Crystallization Kinetics ◽

Random Copolymers ◽

Parallel Model ◽

Two Stage ◽

Avrami Kinetics ◽

Kinetics Of

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Two-Stage Master Sintering Curve Approach to Sintering Kinetics of Undoped and Al2O3-Doped 8 Mol% Yttria-Stabilized Cubic Zirconia

Journal of the American Ceramic Society ◽

10.1111/j.1551-2916.2010.04199.x ◽

2010 ◽

Vol 94 (4) ◽

pp. 1053-1059 ◽

Cited By ~ 34

Author(s):

Xiaochao Song ◽

Jie Lu ◽

Tianshu Zhang ◽

Jan Ma

Keyword(s):

Two Stage ◽

Sintering Kinetics ◽

Cubic Zirconia ◽

Kinetics Of

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Kinetics of methanol to olefins over AlPO4-bound ZSM-5 extrudates in a two-stage unit with dimethyl ether pre-reactor

Microporous and Mesoporous Materials ◽

10.1016/j.micromeso.2012.07.012 ◽

2012 ◽

Vol 164 ◽

pp. 172-181 ◽

Cited By ~ 19

Author(s):

Markus Menges ◽

Bettina Kraushaar-Czarnetzki

Keyword(s):

Dimethyl Ether ◽

Two Stage ◽

Kinetics Of

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The kinetics and the mechanism of oxidative decarboxylation of benzilic acid by acidic permanganate (stopped-flow technique) An autocatalytic study

Canadian Journal of Chemistry ◽

10.1139/v04-102 ◽

2004 ◽

Vol 82 (9) ◽

pp. 1372-1380 ◽

Cited By ~ 13

Author(s):

Sairabanu A Farokhi ◽

Sharanappa T Nandibewoor

Keyword(s):

Activation Parameters ◽

Oxidative Decarboxylation ◽

Two Stage ◽

First Order ◽

First Order Kinetics ◽

Stage Process ◽

Benzilic Acid ◽

Reaction Constants ◽

Kinetics Of ◽

Good Agreement

The kinetics of the oxidation of benzilic acid by potassium permanganate in an acidic medium were studied spectrophotometrically. The reaction followed a two-stage process, wherein both stages of the reaction followed first-order kinetics with respect to permanganate ion and benzilic acid. The rate of the reaction increased with an increase in acid concentration. Autocatalysis was observed by one of the products, i.e., manganese(II). A composite mechanism involving autocatalysis has been proposed. The activation parameters of the reaction were calculated and discussed and the reaction constants involved in the mechanisms were calculated. There is a good agreement between the observed and calculated rate constants under different experimental conditions.Key words: oxidation, autocatalysis, benzilic acid, two-stage kinetics.

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THE INTERACTION OF PURIFIED FACTOR VIII WITH PLATELETS

10.1055/s-0038-1643616 ◽

1987 ◽

Author(s):

P R GanZ ◽

E S Tackberry ◽

G Rock

Keyword(s):

Factor Viii ◽

Specific Activity ◽

Membrane Surface ◽

Platelet Membrane ◽

Factor X ◽

Single Chain ◽

Physiological Concentration ◽

High Molecular Weight Species ◽

Polyethylene Glycol Precipitation ◽

Kinetics Of

Factor VIII is known to interact with Factors IXa and X to generate activated Factor X. A requirement for phospholipid in this reaction suggests that this "tenase" protein complex is assembled on a membrane surface. As a first step in studying the involvement of Factor VIII in this process, we wished to determine whether purified Factor VIII could interact directly with platelets. Factor VIII utilized in these experiments was purified from heparinized blood by a six-stage procedure including cryoprecipitation, polyethylene glycol precipitation, Affi-Gel Blue, Aminohexyl, polyelectrolyte E5 and immunoaffinity chromatography. This yielded a single-chain high molecular weight species of approximately 260,000 (specific activity 5,200 units/mg). This homogeneous protein was then radiolabelled with Na125I by a procedure which allowed the retention of approximately 60-80% of the procoagulant activity of Factor VIII. The kinetics of binding of 125I-Factor VIII to washed platelets at physiological concentration (approximately 3xl08/mL) was examined. Our results showed that for Factor VIII concentrations between 0.38 and 3.0 ng/mL there was a linear uptake of radiolabelled Factor VIII, whereas for concentrations above 10ng/mL only a slight increase in uptake occurred. To further define the association of purified Factor VIII with the platelet membrane, we also labelled Factor VIII with a bifunctional, photoactivatable cross-linking reagent, N-[4-(p-azido-m-[125]iodophenylazo)benzoyl]3-aminopropyl-N1 -oxysuccinimide ester. Analysis by PAGE showed thatthis reagent reacts predominantly with residues in the light chain or neahe C-terminal portion of Factor VIII. When mixed with thrombin-stimulated platelets, the cross-linked Factor VIII molecule was shown to transfer greater than 80% of the 125I label to a polypeptide of M.W. 80,000-90,000 isolated from platelet lysates. Autoradiographs of the labelled platelet preparations demonstrated that other minor polypeptides were radiolabelled. These experiments suggest that Factor VIII interacts closely with a platelet membrane protein which could represent a binding site for Factor VIII

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PLASMINOGEN ACTIVATION BY SINGLE-CHAIN UROKINASE (scu-PA) IN FUNCTIONAL ISOLATION - DEMONSTRATION OF A NOVEL MECHANISM

10.1055/s-0038-1642907 ◽

1987 ◽

Author(s):

V Ellis ◽

M F Scully ◽

V V Kakkar

Keyword(s):

Human Kidney ◽

Binding Pocket ◽

Moderate Activity ◽

Plasminogen Activation ◽

Single Chain ◽

Irreversible Inhibitor ◽

Peptide Substrates ◽

Sds Page ◽

Catalytic Constant ◽

Kinetics Of

The kinetics of the activation of Glu- and Lys- plasminogen by single-chain urokinase (pro-urokinase) derived from the transformed human kidney cell line, TCL-598, has been studied and compared with two-chain urokinase (UK). Plasminogen activation was determined by the change in fluorescence polarization of fluorescein-labelled aprotinin (Trasylol), an essentially irreversible inhibitor of plasmin. This methodology allows plasmin production by scu-PA to be measured in functional isolation, with no interfering generation of two-chain UK. scu-PA was found to activate plasminogen to plasmin with Michaelis-Menten type kinetics. The Km for this reaction was determined as 70µM, with a catalytic constant of 2.25 min-l. The generation of two-chain plasmin was confirmed by reduced SDS-PAGE. Plasminogen activation by UK was found to have a similar Km but the kcat was 16-fold higher, at 36.0 min-l. This is in contrast to the amidolytic activity of scu-PA which was less than 0.2% that of UK. The activation of scu-PA to UK by plasmin was also characterized. Using these data it is possible to calculate the theoretical rate of plasminogen activation by scu-PA, in the absence of aprotinin when UK will be generated by plasmin action. The calculated rate was in good agreement with that determined experimentally when using the chromogenic substrate, S-2251. These data demonstrate that scu-PA has properties which distinguish it from conventional serine protease zymogens. There is a lack of activity against peptide substrates (and also DFP) demonstrating the inaccessibility of the substrate binding pocket. However, there is moderate activity against plasminogen suggesting that plasminogen may be acting as both an effector and a substrate for scu-PA.

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