scholarly journals Akinetic model for the consumption of stabilizer in single base gun propellants

2002 ◽  
Vol 67 (2) ◽  
pp. 103-109 ◽  
Author(s):  
Ljiljana Jelisavac ◽  
Milos Filipovic
Keyword(s):  
Life Time ◽  
Order Reaction ◽  
Zero Order ◽  
Final Phase ◽  
Single Base ◽  
First Order ◽  
Low Concentrations ◽  
Zero Order Reaction ◽  
High Concentrations ◽  
Gun Propellants

A suitable kinetic model for the consumption of stabilizer (diphenylamine) in single base gun propellants was investigated and successfully verified. The model assumes that a reaction of shifting order can be applied for the consumption of diphenylamine in single base gun propellants. It was found that the experimental data were well evaluated by a first-order reaction at high concentrations of diphenylamine in the propellant, but by a zero-order reaction at low concentrations during the final phase of the propellant life time. The mechanism of diphenylamine depletion was discussed with relation to the model and the ageing behavior of the propellants. The kinetic parameters of this model, which permit the calculation of the time up to complete consumption of the diphenylamine, were determined. The results were compared with the kinetic data obtained by a widely accepted model, which combines formally reactions of first and zero order, designated as an "exponential and linear" model. All comparisons gave satisfactory agreement.

Urokinase Activation of Plasminogen and Spontaneous Inactivation of the Plasmin Formed

1968 ◽  
Vol 19 (01/02) ◽  
pp. 145-160 ◽  
Author(s):  
W Berg
Keyword(s):  
Order Reaction ◽  
Zero Order ◽  
Inactivation Rate ◽  
First Order Reaction ◽  
Activity Levels ◽  
First Order ◽  
Activation Rate ◽  
Zero Order Reaction ◽  
High Concentrations ◽  
Kinetics Of

SummaryThe kinetics of the activation of plasminogen into plasmin with urokinase and the inactivation rate of the plasmin formed are studied.As a first order reaction is obtained with low plasminogen concentrations and a zero-order reaction is obtained with high concentrations, the activation seems to follow the Michaelis-Menten’s law. The reaction does not go to completion, however. Different activity levels, which are dependent on the urokinase concentration, can be observed.The activation rate increases with temperature. A maximum can be seen at about 42° C.Between 4° C and 15° C, the inactivation of the plasmin formed is minimal, but it increases rapidly at higher temperatures. The inactivation follows approximately a first order reaction with respect to time. If the plasminogen concentration is low, the over-all reaction will be that of two consecutive first order reactions.

Pseudo-Homogenous Kinetics Model for the Synthesis of Dimethyl Carbonate from Urea and Methanol with Heterogeneous Catalyst

2011 ◽  
Vol 233-235 ◽  
pp. 481-486
Author(s):  
Wen Bo Zhao ◽  
Ning Zhao ◽  
Fu Kui Xiao ◽  
Wei Wei
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Dimethyl Carbonate ◽  
Side Reaction ◽  
Order Reaction ◽  
Zero Order ◽  
Kinetics Model ◽  
First Order ◽  
Zero Order Reaction ◽  
Kinetics Of

The synthesis of dimethyl carbonate (DMC) from urea and methanol includes two main reactions: one amino of urea is substituted by methoxy to produce the intermediate methyl carbamate (MC) which further converts to DMC via reaction with methanol again. In a stainless steel autoclave, the kinetics of these reactions was separately investigated without catalyst and with Zn-containing catalyst. Without catalyst, for the first reaction, the reaction kinetics can be described as first order with respect to the concentrations of methanol and methyl carbamate (MC), respectively. For the second reaction, the results exhibit characteristics of zero-order reaction. Over Zn-containing catalyst, the first reaction is neglected in the kinetics model since its rate is much faster than second reaction. After the optimization of reaction condition, the macro-kinetic parameters of the second reaction are obtained by fitting the experimental data to a pseudo-homogenous model, in which a side reaction of DMC synthesis is incorporated since it decreases the yield of DMC drastically at high temperature. The activation energy of the reaction from MC to DMC is 104 KJ/mol while that of the side reaction of DMC is 135 KJ/mol.

Biodegradation Kinetics of Phenols in an Aerobic Biofilm at Low Concentrations

1991 ◽  
Vol 23 (7-9) ◽  
pp. 1375-1384 ◽  
Author(s):  
Erik Arvin ◽  
Bjørn K. Jensen ◽  
Anders Torp Gundersen
Keyword(s):  
Phenol Degradation ◽  
Carbon Sources ◽  
Order Reaction ◽  
Zero Order ◽  
Biofilm Reactor ◽  
Aerobic Biodegradation ◽  
Maximum Capacity ◽  
Low Concentrations ◽  
Zero Order Reaction ◽  
Kinetics Of

Aerobic biodegradation of the phenols: phenol, 2-methylphenol, 4-methylphenol, 2,4-dimethylphenol, 3,5-dimethylphenol and 2,4,6-trimethylphenol was studied in a biofilm reactor to establish kinetic constants under conditions where the phenols were the sole carbon sources. Phenol concentrations were very low, in the µg/l concentration range. 2,4,6-trimethylphenol was not degraded. The degradation of the other phenols was 1'st order at concentrations in the bulk phase below 20-50 µg/l. Zero order reaction seemed to govern the reaction above 200 µg/l. The l'st order rate constants are 3-30 times higher than the constants calculated for easily degradable organic compounds degraded at 100-1000 times higher concentrations (mg/l range). However, the maximum phenol utilization rates and the Monod constants were much lower compared with constants obtained for the microorganisms grown in the mg/l concentration range. The Monod constant was about 100 times lower. The removal of “total biodegradable phenol” (TB-phenol) was very similar to the removal of a specific compound. The degradation of TB-phenol was l'st order at concentrations below 200 µg/l. When the total biodegradable phenol degradation is near its maximum capacity (o'order reaction) there was a preferential degradation of the most easily degradable phenols, phenol and 2-methylphenol, leading to an apparent inhibition of the degradation of the more slowly degradable phenols, in particular 2,4-dimethylphenol and 3,5-dimethylphenol.

scholarly journals Chemical, Microbiological and Sensory Stability of Steam Extracted Jaboticaba (Myrciaria jaboticaba) Juice

Foods ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 732
Author(s):  
Ana Beatriz Neves Martins ◽  
Mariana Canto ◽  
Daniel Perrone ◽  
Mariana Monteiro
Keyword(s):  
Phenolic Compounds ◽  
Reaction Kinetics ◽  
Total Phenolics ◽  
Order Reaction ◽  
Zero Order ◽  
Purchase Intent ◽  
First Order ◽  
Color Changes ◽  
Steam Extraction ◽  
Zero Order Reaction

Jaboticaba (Myrciaria jaboticaba) is a Brazilian berry rich in phenolic compounds, much appreciated for its sweet and slightly acid taste, and highly perishable. Thus, we aimed at producing jaboticaba juice by steam extraction and at investigating its microbiological, sensorial and chemical qualities during storage for up to 168 days. Juice was microbiologically safe and even though unsweetened juice was well accepted, sucrose addition further improved flavor (21%), overall impression (11%) and purchase intent (21%) scores. Cyanidin-3-O-glucoside (C3G) was the major phenolic (40%), followed by gallic (28%) and ellagic acids (21%). Total phenolics contents decreased from 27% (50 °C) to 50% (25 °C), mainly driven by C3G degradation. At 60 °C, total phenolics contents did not change after 42 days since C3G degradation was counterbalanced by gallic acid formation (129%), which followed zero-order reaction kinetics. Anthocyanins degradation followed first-order reaction kinetics (C3G half-life at 25 °C = 21.7 days) and was associated with color changes during storage. In conclusion, steam extraction followed by hot-filling technique ensured a juice with at least six months of shelf life.

Conjugation and excretion of the amino and acetamido benzoic acids

1959 ◽  
Vol 196 (6) ◽  
pp. 1224-1230 ◽  
Author(s):  
P. K. Knoefel ◽  
K. C. Huang ◽  
A. Despopoulos
Keyword(s):  
Glucuronic Acid ◽  
Reaction Rates ◽  
Order Reaction ◽  
Zero Order ◽  
The Body ◽  
Aminobenzoic Acid ◽  
First Order ◽  
Aminobenzoic Acids ◽  
Ortho Isomer ◽  
Zero Order Reaction

The conjugation of the aminobenzoic acids with glycine and glucuronic acid has been measured in the rabbit and the dog. In both species the total conjugation is greatest with the ortho isomer, least with the para. In the rabbit, the amount of hippurate formed is greater than the amount of glucuronide formed, and in each case, greatest with the ortho isomer and least with the para. These relations are determined by the comparative first-order reaction rates, the comparative zero-order reaction rates, the concentration of the aminobenzoic acid in the body at which the reaction changes from first-order to zero-order, and the dose. In the dog, the meta aminobenzoic acid forms more hippurate than glucuronide, as in the rabbit, but for the ortho and para isomers the formation of hippurate is much less than that of glucuronide. The meta and para acetamidobenzoates are conjugated to a smaller extent than are the aminobenzoates. Slices of kidney and liver perform these conjugations to an extent agreeing with that in the whole animal, in some but not all cases. It appears that both species form the three hippurates in the kidney, but in the liver by the rabbit only. Both species form the three glucuronides, probably in both kidney and liver.

Intensification of cooling in a batch reactor with an exothermic reaction by nonisothermal control in stable pseudostationary states

1984 ◽  
Vol 49 (11) ◽  
pp. 2566-2578 ◽  
Author(s):  
Josef Horák ◽  
Petr Beránek ◽  
Dagmar Maršálková
Keyword(s):  
Batch Reactor ◽  
Exothermic Reaction ◽  
Reaction Model ◽  
Order Reaction ◽  
Zero Order ◽  
Coolant Temperature ◽  
Inlet Temperature ◽  
Adaptive Parameter ◽  
Zero Order Reaction ◽  
Set Up

An algorithm is set up and tested for the temperature control of a batch reactor consisting in jump changes in the inlet temperature of entering coolant. This temperature is so chosen that its difference from the temperature of the reaction mixture is near the highest difference at which the stable pseudostationary state of the system still exists. For the prediction of the new coolant inlet temperature, a zero-order reaction model is used with an adaptive parameter estimated from the experimentally established value of the maximum of the reaction mixture overheating at the previous coolant temperature.

The Characteristics and Kinetics of 4-CP with Pb2+ Biodegradation by Fusarium sp.

2013 ◽  
Vol 726-731 ◽  
pp. 2506-2509
Author(s):  
Xiao Xiao Wang ◽  
Xiao Qin Yu ◽  
Jun Ya Pan ◽  
Ji Wu Li
Keyword(s):  
Carbon Source ◽  
Kinetic Equations ◽  
Order Reaction ◽  
Zero Order ◽  
Biodegradation Rate ◽  
Reaction Equation ◽  
Zero Order Reaction ◽  
Kinetics Of ◽  
Additional Carbon Source

The effects of Pb2+concentration, pH and additional carbon source on biodegradation of 4-chlorophenol (4-CP) byFusariumsp. were investigated, and the characteristic and kinetic of 4-CP biodegradation were analyzed. It was concluded that 4-CP biodegradation rate byFusariumsp. decreased a little at concentration of Pb2+0.20 mg/L and 4-CP 50 mg/L. The suitable biodegradation pH was range from 6 to 7. Additional carbon source (phenol) might increase the rate of 4-CP biodegradation. The kinetic equations of 4-CP biodegradation were well accord with the zero order reaction equation at different concentration of Pb2+.

Enzymatic assay of magnesium through glucokinase activation.

1989 ◽  
Vol 35 (11) ◽  
pp. 2212-2216 ◽  
Author(s):  
P Fossati ◽  
M Sirtoli ◽  
G Tarenghi ◽  
M Giachetti ◽  
G Berti
Keyword(s):  
Atomic Absorption Spectrophotometry ◽  
Order Reaction ◽  
Zero Order ◽  
Good Sensitivity ◽  
Test Results ◽  
Enzymatic Method ◽  
Absorption Spectrophotometry ◽  
Routine Work ◽  
Zero Order Reaction ◽  
Glucose 6 Phosphate Dehydrogenase

Abstract We describe an improved enzymatic method for assaying magnesium in serum, plasma, or urine. Magnesium participates as an Mg.ATP complex in a reaction catalyzed by glucokinase (EC 2.7.1.2) coupled to an NADP+-dependent glucose-6-phosphate dehydrogenase (EC 1.1.1.49) reaction. The increase of absorbance at 340 nm, due to the NADPH produced, is proportional to the amount of the activated glucokinase, which in turn is related to the concentration of magnesium in the sample. The method is characterized by a zero-order reaction kinetics, affording a simple and rapid assay with good sensitivity and linearity (up to 2.06 mmol/L) and by working solutions that are stable (refrigerated) for one month. The method is reliable, produces test results that compare closely with those of the atomic absorption spectrophotometry (r greater than or equal to 0.99), is suitable for routine work, and lends itself to automation.

scholarly journals The Kinetics of Clearance from the Circulation of Man of Heparin and a Semi-Synthetic Heparin Analogue

1977 ◽  
Author(s):  
D. A. Lane ◽  
R. Michalski ◽  
V. V. Kakkar
Keyword(s):  
High Specificity ◽  
Antithrombotic Agent ◽  
First Order ◽  
First Order Kinetics ◽  
Zero Order Kinetics ◽  
Low Concentrations ◽  
Equal Dose ◽  
Rapid Clearance ◽  
The Difference ◽  
High Concentrations

A study has been made of a low molecular weight semi-synthetic heparin analogue, (SSHA) that may be clinically useful as an antithrombotic agent because of itsreported high specificity for potentiating antithrombin III activity. The clearance from the circulation of both heparin and the analogue has been studied in man following intravenous injection. Heparin obeyed almost zero order kinetics when assayed using a specific anti-Xa assay and first order kinetics when measured with KCCT. At high concentrations the heparin analogue was cleared with first order kinetics when assayed both with the anti-Xa assay and with KCCT. At low concentrations the analogue produced between one half and two-thirds of the anti-Xa activity of an equal dose of heparin, producing only a small prolongation of KCCT. With increasing dose, the more specific anti-Xa potentiating effect of SSHA decreased in part because of the difference in kinetic behaviour between heparin and SSHAbut largely because of a flattening of its anti-Xa dose response curve. Because of the initial more rapid clearance of higher doses of heparin from plasma when it is measured by the KCCT, these results suggest that the use of KCCT can cause a small underestimate of circulating heparin anti-thrombotic activity.

A preliminary study to predict net nitrogen mineralisation in a flooded rice soil using anaerobic incubation

1994 ◽  
Vol 34 (7) ◽  
pp. 995 ◽  
Author(s):  
JF Angus ◽  
M Ohnishi ◽  
T Horie ◽  
RL Williams
Keyword(s):  
N Uptake ◽  
Order Reaction ◽  
Zero Order ◽  
Organic N ◽  
N Mineralisation ◽  
Anaerobic Incubation ◽  
Flooded Soil ◽  
Order Model ◽  
First Order ◽  
Net Mineralisation

Complementary field and laboratory studies were conducted to determine whether laboratory measurements of net nitrogen (N) mineralisation under anaerobic conditions could be used to predict field rates in a flooded soil and N uptake by a rice crop. The laboratory experiment consisted of measurements of ammonium accumulation at 10, 20, 30, and 40�C for 7, 14, and 28 days of anaerobic incubation. There was no accumulation of ammonium at 10�C, but increasing ammonification rate at temperatures of 20�C was observed, except for a slower rate at 40�C after 14 days. Two models were tested on the data: a zero-order reaction in which rate of mineralisation was a linear function of temperature; a first-order reaction in which net N mineralisation rate was a proportion of a depleting pool of labile organic N. In the second model, the rate was also linearly related to temperature. Both models fitted the laboratory data well (R2 = 0.94 and 0.97, respectively), but the second model accounted better for mineralisation at 40�C for the 28-day incubation. These models were then run, using daily mean temperatures over a rice-growing season, to predict net mineralisation in the field. The predictions were compared with measured net N mineralisation in a flooded soil and N uptake by the crop measured throughout the season in the field from which the incubated soil was sampled. Net N mineralisation and crop uptake increased throughout the season, reaching maximum values of 115 and 111 kg N/ha at maturity. The zero-order and first-order models both predicted net N mineralisation accurately until the middle of the season, after which the zero-order model overestimated net N mineralisation but the first-order model predicted the reduction in the rate of net N mineralisation with reasonable accuracy. The close agreement between the laboratory incubations and field measurements of net mineralisation and crop N uptake suggest that incubation tests may provide useful information for including in a model to assist rice growers' decisions about N fertiliser.

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